The promotion of livestock production is widely believed to support enhanced diet quality and child nutrition, but the empirical evidence for this causal linkage remains narrow and ambiguous. This study examines whether adoption of improved dairy cow breeds is linked to farm-level outcomes that translate into household-level benefits including improved child nutrition outcomes in Uganda. Using nationwide data from Uganda’s National Panel Survey, propensity score matching is used to create an unbiased counterfactual, based on observed characteristics, to assess the net impacts of improved dairy cow adoption. All estimates were tested for robustness and sensitivity to variations in observable and unobservable confounders. Results based on the matched samples showed that households adopting improved dairy cows significantly increased milk yield—by over 200% on average. This resulted in higher milk sales and milk intakes, demonstrating the potential of this agricultural technology to both integrate households into modern value chains and increase households’ access to animal source foods. Use of improved dairy cows increased household food expenditures by about 16%. Although undernutrition was widely prevalent in the study sample and in matched households, the adoption of improved dairy cows was associated with lower child stunting in adopter household. In scale terms, results also showed that holding larger farms tends to support adoption, but that this also stimulates the household’s ability to achieve gains from adoption, which can translate into enhanced nutrition. The global burden of undernutrition remains high, particularly in Sub-Saharan Africa . While aUganda is a low-income country with high prevalence rates of child undernutrition. Recent data show that 29% of Ugandan children below age 5 were stunted (low height for age), with relatively higher stunting rates recorded in rural areas . The comOne of the major challenges to growth of Uganda’s dairy industry has been low productivity linked to low technology use, particularly with regard to use of indigenous cow breeds . The govEvidence on the impact of improved agricultural technologies in low-income countries is slowly growing, but often focusing on enterprise productivity, particularly through household income. The empirical evidence base linking agricultural strategies, including improved dairy cows adoption, to better health and nutrition outcomes, remains narrow, ambiguous, and based on a few heterogeneous studies that lack methodological rigor , 21–23. All these studies are site-specific, based on samples taken from areas with prior deliberate exposure to project activities. Without explicit consideration of differences in breed superiority and effectiveness of dissemination activities, these studies fail to draw and explain clear empirical pathways from adoption to welfare and child nutrition. Moreover, most studies presuppose that the benefits of adoption accrue uniformly across small and large farms, ignoring marginal benefits and costs due to scale.This paper seeks to address such important gaps in the literature. Using a nationally representative sample of 907 Ugandan households, this study’s primary objective is to examine whether adoption of improved dairy cow breeds leads to enhanced child nutrition. Specifically, the analysis considers if differences in adoption status of improved dairy cow breeds are linked to farm-level outcomes  that manifest in household-level outcomes (food and non-food expenditure) as well as individual improvements in child nutrition .The data used for this study were derived from the 2009/2010 round of Uganda National Panel Survey (UNPS), conducted by the Uganda Bureau of Statistics (UBoS). The 2009/2010 round was the first wave of a panel of annual household surveys initiated to track changes in key household welfare indicators by ensuring improved quality and relevance of data on agriculture, food and nutrition security, among others. Moreover, the 2009/2010 also introduced a module on child and maternal anthropometry to assess changes in nutritional indicators. Unfortunately, the analysis for this paper is cross-sectional largely because subsequent data waves did not provide sufficient child anthropometric data observations for a feasible panel analysis.The primary dataset comprised 2,975 households that were selected from the sample of households surveyed in the 2005/2006 round of the Uganda National Household Surveys (UNHS) following a two-stage stratified random sampling design . In the adopters’) if they owned at least one crossbred or exotic dairy cow breed  or as ‘non-adopters’ if they reared only local indigenous dairy cows. To draw the empirical pathway linkages between improved dairy cow ownership and child nutrition, a broad set of potentially intermediate outcome indicators were created for this analysis.Data were collected between September 2009 and August 2010. To minimize recall biases and improve data quality, enumerators made 2 visits 6 months apart to all sampled agricultural households to capture agricultural indicators associated with two major cropping seasons in Uganda. The questionnaire recorded information on demography, assets, income, and expenditure as well as on agricultural production, including details on livestock production. Respondents were required to categorize different livestock breeds owned as either local, crossbreeds or exotic. Using this module, the analysis categorized households either as improved dairy cow adopters  level, annual milk yield per cow, estimated as total annual milk output divided by the number of cows owned, was used as an indicator of productivity. The share of milk sold, calculated as the ratio of the quantity of milk sales to total milk output and expressed as a percentage, proxies enterprise commercialization or milk market participation.At the household level, milk intake and income were used to proxy for different dimensions of food and nutrition security. Annual per capita milk intake of own-produced milk, calculated as the annual milk reported consumed divided by the number of resident household members, was used as a marker of alternate access to ASFs, which serves as a proxy for micronutrient intake or diet quality. Caution should be taken while interpreting this proxy indicator, because it assumes equal distribution of milk among household members, which is seldom the case. Per capita expenditure (PCE) of food and non-food items was calculated by summing all household food and nonfood expenditures and dividing by the number of adult equivalents. Given the different recall periods used in the survey, conversion factors were applied to generate PCE on the basis of a 30-day month. Home-produced food consumption was valued at local market prices. PCE is a strong predictor for wellbeing and serves as a marker of food access for measuring gross food security .The main objective of this study was to measure the extent of undernutrition in children aged 6 to 59 months across adopter and non-adopter households. That is, to test whether adoption status predicts nutrition outcomes in this cross-sectional sample. Anthropometric Z-scores, standardized for age and sex, were computed for height-for-age (HAZ), weight-for-age (WAZ), and weight-for-height (WHZ) using World Health Organization (WHO) Growth Standards . Anthropt-tests and Pearson’s chi-squared test of independence to first assess differences in socioeconomic, demographic and contextual characteristics between adopter and non-adopter households. Similarly, differences in the listed outcome indicators between adopters and non-adopters were assessed. Outcome indicators of interest were: i) annual milk yield to proxy for cow productivity; ii) milk sales as marker for household market participation or commercialization; iii) milk intakes and PCE, representing gross food and micronutrient security. Nutritional outcomes were iv) child anthropometric Z-scores as indicators of undernutrition.Univariate analyses were performed using With only cross-sectional data available, propensity score matching (PSM) methods were used to model the impact of improved dairy cow adoption on child nutrition outcomes and on hypothesized intermediary pathways. A few recent studies have used PSM to draw causal effects to child nutrition and health outcomes , 30, 31.P(X) = Pr(Di = 1|xi). A propensity score p(xi) is obtained using a probit model which estimates the probability of participating in a treatment given a set of relevant observables, xi, likely to be correlated with participation in treatment, and with the outcomes of interest. Di = 1 denotes treatment [The use of PSM is justifiable due to potential non-random self-selection into adoption or non-adoption, which may result in biased estimates. PSM constructs a statistical comparison group based on a model of the probability of participating in the treatment (improved dairy cow adoption): reatment . AdopterImplementation of PSM requires a region of common support or substantial overlap in covariates between adopters and non-adopters; and that the balancing property is satisfied so that households being compared have a common probability of both being adopter and non-adopter . MatchinPSM methods rely on observables to construct a comparison group. To rule out potential effects of unobservables, the analysis further conducted a battery of sensitivity analyses. First, bounding sensitivity method proposed by Rosenbaum  was usedA few limitations of the procedures used are noteworthy. Households were matched using cross-sectional data that does not indicate when a particular household was treated (i.e. adopted improved cows). While cautious in selecting covariates, the level of some covariates could have been determined after households had been treated. To cater for yet another source of potential confounding, all major models were re-estimated without all potentially problematic variables, particularly farm size and assets. Excluding these variables singly or together did not significantly affect neither the estimates nor the balancing properties.A nationally representative dataset  was usedP ≤ .05, and all data analyses were implemented using Stata software package, version 14.1.Statistical significance was set at Adopter households owned at least one crossbred or exotic (non-domestic) dairy cow in the year preceding the survey, while non-adopters owned indigenous dairy cows only. An average household head in dairy cattle-herding households attained below the statutory 7 years of primary education and is aged 48 years. Most households were male-headed, composed of 8 members. The share of dependents was almost 1.5 times more than the working-age members. Adopters were significantly more educated, with larger family size, composed of mostly males of working age.Sampled households owned, on average, 10 acres of land. However, half of these were smallholders, owning below 2 acres. Average asset holdings (excluding housing and livestock) were in excess of Uganda Shillings (UGX) 1 million. Adopters owned more than twice as much land and threefold the value of assets as non-adopters, construing that adopters were significantly wealthier than non-adopters. The majority of households (98%) were engaged in off-farm income activities , perhaps as a risk diversification strategy to offset farm and household cash needs .The sample was relatively balanced, with 40% of households residing in dairy cattle-herding areas of Central and Western Uganda, with a significantly higher proportion of households adopting improved cow breeds in those locations, as would be expected. Irrespective of regional placement, cattle herding, like other agricultural activities, was majorly rural, with the share of adopters significantly higher in rural areas.Summary statistics of outcome indicators are presented in the lower panel of Sampled households spent a monthly average of UGX 27,507 on food items per capita, which was slightly higher than the average national food poverty line  at the time, but spent about UGX 19,000 on nonfood items . Adopters spent significantly more on food and nonfood items, which can impact quality of life.With regards to anthropometry, most children aged 6 to 59 months in sample households were below the WHO reference population mean height and weight. Average HAZ of –1.44 indicated that sampled children were one-and-a-half standard deviations (SDs) shorter than the reference population, suggesting gross stunting and chronic undernutrition. Similarly, average WAZ of –0.83 implied that weight of sampled children was below the standard. Average WHZ, indicative of more recent short-term deprivation, was not as bad, although still below the WHO recommendation. Children living in adopter households were significantly better nourished than children in non-adopter households, based on HAZ and WAZ scores. It is noteworthy that the number of data points for child anthropometry was substantially than for other variables because: (a) some sampled households had no eligible child, prompting enumerators to skip this section; and (b) some observations were voluntarily omitted from the sample due to measurement error during data processing. Nonetheless, these estimations mimic the Uganda Demographic and Health Survey at the time  .The nature of farm and household characteristics laid out in the previous section hints at a positive selection bias in adoption behavior; that is, households with larger farms, more income and higher education are more likely to adopt improved dairy cows, which could of course bias impacts relating to child nutrition. PSM models were therefore employed to match similar households and compare outcomes across adopters and non-adopters.Preliminary diagnostic steps are necessary before interpreting PSM impact results: A probit model to generate propensity scores upon which to balance the observed characteristics across adopters and non-adopters was in harmony with literature , 42, witFigs Results for the net impact (ATT) of improved dairy cow adoption on outcomes are presented in PSM constructs a comparison group based on a set of observables. To rule out potential effects of unobserved heterogeneity on ATT, a battery of sensitivity analyses were conducted. The treatment effect was robust to the possible presence of hidden bias, Γ, across all significant outcomes . For insS1 Appendix, first row, shows that ‘baseline’ ATT estimates with no simulated confounder were very close to ATT estimates earlier attained , accrued to households with small farms of below midpoint (median) herd size (<2 heads). Small farms attained 56% more milk yield than households with large herd size. In contrast, farm acreage had a stronger leverage on milk yield than herd size: results showed that large-scale farmers, in terms of acreage, achieved much larger and highly significant productivity impacts from adoption of improved dairy cows. But in terms of both herd size and farm acreage, adoption of improved breeds significantly increased milk intakes, milk sales and child HAZ scores by relatively bigger magnitudes in large farms as compared to small farms. Farms of below median herd size and acreage were only significantly better with respect to expenditure on food items.Rigorous empirical studies linking agricultural interventions to nutrition outcomes remain limited. This analysis assessed the potential impact of genetically improved dairy cows on the nutrition of Ugandan children aged below 5 years, while drawing possible pathway linkages to intermediary farm and household outcomes. All impact estimates were tested for robustness and sensitivity to variations in observable and unobservable confounders. Moreover, we made more sense of the estimates by considering scale effects of adoption based on herd size and farm acreage.At the enterprise level, we found that improved dairy cows increased milk yield of adopters by over 200%. These are substantial increases in milk yield, but still lower than the genetic potential of known improved breeds in Uganda and the region. For instance, previous research showed that an improved cow breed can produce over 990 liters/year compared to only 400 liters for local breeds , represeImproved dairy cows further enhanced the share of milk sales, an indicator of market participation, demonstrating the potential of improved agro-technologies in integrating smallholders into modern value chains. Unlike earlier studies, which reported ambiguity between commercialization and own-food consumption, , 44 thisAt the household level, adoption of improved dairy cows significantly increased monthly food expenditures, but the positive impact on nonfood items was imprecisely estimated. The causal effect of adoption on monthly food PCE was about 16% relative to non-adopters, grossly implying that adopters were better off in terms of food access but not necessarily so in terms of nonfood items such as education, health, and clothing. Consequently, actual increased expenditures on food and potential enhancements in non-food expenditure may be attributed to increased milk intake and sales, which could then be reflected in leveraged child nutritional outcomes.Finally, there were positive and consistently significant ATT estimates for HAZ scores, suggesting that children living in adopting households were on average taller than those living in non-adopting households for the same age and gender. However, improved dairy cow adoption did not influence WAZ or WHZ scores, implying that improved cow breeds reduced stunting but certainly not underweight or wasting of children below age 5 years. Although undernutrition was widely widespread in the original study sample and in matched households, the adoption of improved dairy cows was associated with augmented child height in adopter household by 0.48 SDs. These are quite large effects by any standards but are not surprising since milk is a known nutrient-dense ASF. Children who consume cow’s milk are known to attain higher height and bone mass than children who do not consume milk or other ASFs .Turning to scale effects, we found that adoption of improved dairy cows disproportionately benefited households with larger farms (both herd size and acreage). Except for food expenditures, whose adoption impact is more pronounced among smallholder farmers, households with large farms  enjoyed greater adoption effects—in terms of milk yield, intakes and sales. However, farm acreage had a particularly stronger leverage on milk yield than herd size, which makes sense as it would be difficult to hold large herds without sufficient land. Seemingly, holding large farms is influential to adoption but also stimulates the household’s ability to achieve substantial gains from adoption, which may ultimately impact on child nutrition.A few important caveats deserve mentioning. First, we emphasize that there are still few studies that rigorously evaluate the impact of agricultural interventions, drawing pathway linkages to household welfare and nutrition outcomes as was done in this case of improved dairy cows adoption in Uganda. Such an analysis is only possible if nutrition and health metrics are integrated into data collection exercises , including in Uganda. Unfortunately, national-wide data collection systems, which integrate large agricultural and socioeconomic data together with nutrition metrics  in a panel setup are still rare and, often not perfected over several data waves. Moreover, the ability to minimize sample attrition of these metrics in subsequent data collection rounds is essential for analysts to evaluate and design more effective nutrition-sensitive agricultural interventions.Second, the heterogeneous analysis done for this paper teaches us that benefits of agricultural interventions do not necessarily nor uniformly accrue to all households. Had we not stratified the sample by herd size and farm acreage, the strong positive effects of adoption could have appeared to be uniformly distributed. Given sufficient sample size, other forms of stratification  could provide more informative insights.Third and most important, using our convenient choice of stratification, we learn that an agricultural intervention can possibly have different effects at different outcome levels. For this study, we found a disconnect between welfare indicators and child nutrition outcomes—improved dairy cows benefited larger farmers in terms of milk productivity, milk intakes and sales as well as reducing undernutrition but did not necessarily improve their household food security. Conversely, smallholder farmers improved their food expenditures due to adoption but this did not translate into improved nutritional outcomes. Such results suggest that the linkage between agricultural technology, welfare and child nutrition outcomes may not be straight forward, especially for the small farmers. There may be other factors to consider in future studies.In particular, the results indicate that small farmers may have observed less than a minimal threshold required for the technology to leverage child nutritional outcomes. Since adoption stimulates milk sales to some level but does not enhance own-milk intakes for small farms, it is possible that additional income derived from the technology was not sufficiently used to buy more diverse foods or foods of improved quality but rather was spent on other goods that do not directly reduce child undernutrition.However, it is also important to understand gender roles and intra-household food allocation dynamics, which may change in the face of the new technology , 45. If This research is important for Uganda and other countries in similar contexts. It shows how household-level agricultural interventions, specifically improved dairy cows, may help to ensure household food security and increase nutrient-dense ASFs, which in turn may support reduced stunting. This study therefore highlights the need to integrate nutritional metrics into traditional household surveys to allow analysts to better inform policy makers on such links. In addition, more rigorous impact and process evaluations are needed with panel data and possibly with randomization. Such studies should deliberately seek to identify key gaps along the impact pathway, which undeniably, is not well done for this study. The scope of this analysis was only limited to scale effects but future studies could analyze differential effects across other classifications, such as gender, education level, access to infrastructure and markets, among others. Such studies further help draw lessons for optimal targeting depending on need.This study set out to rigorously test whether adoption of improved dairy cows can leverage pathways to improved child nutrition outcomes through enhanced milk productivity, milk intakes and milk sales. Our results show that improved dairy cows can indeed enhance household welfare and child nutrition. However, the analysis of agriculture-nutrition pathways still remains complex, requiring program implementers and researchers to take on a multifaceted approach. Without a comprehensive consideration of aspects such as agricultural and social-cultural norms and practices, gender roles, household resource and food allocation dynamics, dietary norms, among others, in programming for an intervention and in the research evaluation will likely lead to suboptimal policy choices.S1 Appendix(DOCX)Click here for additional data file.S2 Appendix(DOCX)Click here for additional data file.


Aberrant glycosylation plays a fundamental role in key pathological steps of tumour development and progression. Glycans have roles in cancer cell signalling, tumour cell dissociation and invasion, cell-matrix interactions, angiogenesis, metastasis and immune modulation. Aberrant glycosylation is often cited as a ‘hallmark of cancer’ but is notably absent from both the original hallmarks of cancer and from the next generation of emerging hallmarks. This review discusses how glycosylation is clearly an enabling characteristic that is causally associated with the acquisition of all the hallmark capabilities. Rather than aberrant glycosylation being itself a hallmark of cancer, another perspective is that glycans play a role in every recognised cancer hallmark. The hallmarks of cancer were originally outlined in 2000 and comprise six biological capabilities acquired during the multi-step development of cancer that allow cancer cells to survive, proliferate and disseminate . As cellX (SLeX), Thomsen-nouvelle antigen (Tn), and sialyl-Tn (sTn) antigen have been detected in virtually every cancer type [Aberrant glycosylation in cancer was first described more than 45 years ago –8. The ecer type .Growing evidence supports crucial roles for glycosylation during all steps of tumour progression, and it is well established that glycans regulate tumour proliferation, invasion, metastasis and angiogenesis , 11. AbeGlycosylation is the enzymatic process that produces glycosidic linkages of saccharides to other saccharides, lipids or proteins . Glycosyvia addition of GalNAc, which can then be extended into various different structures. Other types of O-glycans include those attached via O-mannose, and the β-N-acetylglucosamine (O-GlcNAc) [via the amide group of an asparagine residue and are then further processed [The two most common mechanisms by which glycans are linked to proteins are O-linked glycosylation and N-linked glycosylation. In O-linked glycosylation, sugars are added incrementally to the hydroxyl oxygen of serine, threonine residues . A commo-GlcNAc) –20. In Nrocessed . Additiorocessed , 20, 22.Alterations in glycan composition can aid in various stages of cancer progression. The mechanisms that produce altered glycan structures in cancer cells remain poorly understood, but are believed to involve changes in epigenetics, genetic mutations, misregulated expression of glycosyltransferase and chaperone genes, and mislocalisation of glycosyltransferases –26.A fundamental trait of cancer cells is their ability to maintain chronic proliferation . It is wThe extracellular matrix (ECM) imparts the spatial context for the signalling events of various cell surface growth factor receptors, and is composed of a dynamic and complex array of glycoproteins, collagens, glycosaminoglycans and proteoglycans . GlycosyIn addition to inducing and maintaining positively acting growth stimulatory signals, cancer cells must also overcome powerful programs that negatively regulate cell proliferation, many of which depend on the actions of tumour suppressor genes. The two canonical suppressors of proliferation, p53 and RB (retinoblastoma) proteins have both been documented to contain potential glycosylation sites, and their functions may be controlled by dynamic O-GlcNAc modification as well as by phosphorylation –45. O-GlA key feature of cancer cells is a shift from oxidative phosphorylation to aerobic glycolysis . Known aProgrammed cell death by apoptosis serves as a natural mechanism to prevent cancer development, and a hallmark of cancer is the ability of malignant cells to evade apoptosis , 60. GlyCellular accumulation of the glycosphingolipid GD3 contributes to mitochondrial damage and plays a key role in apoptosis . GD3 expAn essential property of cancer cells is to overcome the normal cellular senescence process resulting from the shortening of telomeres. Telomerase activation is a critical step in carcinogenesis and is thought to occur in over 90% of cancers . TranscrThe development of malignant tumours requires the ability of tumour cells to overcome cell-cell adhesion and then invade surrounding tissue. Mounting evidence suggests that certain glycan structures can affect tumour cell invasiveness, including the ability to disseminate through the circulation and metastasise into distant organs . Cancer Glycosylation can also influence the activity and localisation of proteins involved in cell adhesion, including the transmembrane glycoprotein E-cadherin. Over-expression of the enzyme MGAT5 in gastric cancer cells induces E-cadherin mislocalisation from the cell membrane into the cytoplasm , 98. MGAX antigen is upregulated in several types of cancer [As well as reducing cell-cell adhesion and aiding dissociation from the primary tumour, glycans can also promote the adhesion of tumour cells. The SLef cancer , 104, anf cancer , 82. Galf cancer , and Galf cancer .The sialyltransferase ST6GalNAc2 has been identified as a metastasis suppressor in breast cancer cells which is linked to patient survival . Loss ofThrough inducing the process of angiogenesis, development of tumour associated neovasculature enables tumours to acquire nutrients and oxygen as well as the ability to remove metabolic waste including carbon dioxide. The development of vasculature involves growing new endothelial cells and their assembly into tubes (vasculogenesis), and the sprouting (angiogenesis) of new vessels from existing ones. In the adult the vasculature is largely quiescent, but during tumour progression an ‘angiogenic switch’ is activated causing vasculature to continually sprout new vessels and aid tumour growth . A distivia receptor tyrosine kinases (VEGFRs) and plays a pivotal role in angiogenesis during development and in cancer. Glycosylation of both VEGF and the VEGFRs is associated with angiogenesis. VEGF levels are upregulated by O-GlcNAcylation [A key inducer of angiogenesis is vascular endothelial growth factor (VEGF), which signals cylation , and abecylation . Glycanscylation , maintaicylation , controlcylation , and medcylation . Changescylation .Heparan sulfate (HS) proteoglycans are abundantly expressed in the developing and mature vasculature, and play a pivotal role in angiogenesis by facilitating the binding of cell surface pro-angiogenic growth factors –121. HS Acquisition of the cancer hallmarks is made possible in part by the development of genomic instability in cancer cells which generates random mutations and chromosomal rearrangements. The accumulation of mutations can be accelerated by disrupting the surveillance systems that normally monitor genomic integrity. The tumor suppressor p53 has long been known to play a central role in maintaining a stable genome . O-GlcNAx) which act as ‘endothelial zip codes’ for the homing of lymphocytes into inflammatory sites [It has long been recognised that some tumours are densely infiltrated by cells of the immune system and thereby mirror inflammatory conditions in non-neoplastic tissues , 130. Hiry sites .via induction of ‘xenosialitis’[Emerging evidence suggests that key mediators in the inflammatory response may be regulated by glycosylation. NF-κB is a well-characterised orchestrator of inflammation which induces the expression of inflammatory cytokines . The trasialitis’.As well as glycan involvement in the inflammatory response, the inflammatory microenvironment can also reciprocally mediate changes in the glycan composition of cells, which could contribute to tumour malignancy. Pro-inflammatory cytokines can increase the expression of glycosyltransferases involved in the biosynthesis of cancer-associated antigens in pancreatic and gastric cancer cell lines , 144.Cancer immune surveillance is thought to inhibit carcinogenesis and is an important host protection process through which transformed cells are eliminated by immune effector cells. Growing evidence suggests that interactions between tumour specific glycans and lectins on immune cells are involved in modulating the tumour microenvironment . GlycansThe hallmarks of cancer comprise biological capabilities acquired during the multi-step development of cancer that allow cancer cells to survive, proliferate and disseminate . Glycosy


Lipids are essential building blocks synthesized by complex molecular pathways and deposited as lipid droplets (LDs) in cells. LDs are evolutionary conserved organelles found in almost all organisms, from bacteria to mammals. They are composed of a hydrophobic neutral lipid core surrounding by a phospholipid monolayer membrane with various decorating proteins. Degradation of LDs provide metabolic energy for divergent cellular processes such as membrane synthesis and molecular signaling. Lipolysis and autophagy are two main catabolic pathways of LDs, which regulate lipid metabolism and, thereby, closely engaged in many pathological conditons. In this review, we first provide an overview of the current knowledge on the structural properties and the biogenesis of LDs. We further focus on the recent findings of their catabolic mechanism by lipolysis and autophagy as well as their connection ragarding the regulation and function. Moreover, we discuss the relevance of LDs and their catabolism-dependent pathophysiological conditions. Many living organisms store lipids in their cells to produce metabolic energy, in case of insufficient energy sources. Cells preserve lipids by converting them into neutral lipids, such as triacylglycerides (TAG) and sterol esters (SE). These type of lipids are deposited in lipid droplets (LDs) which are also termed as adiposomes, lipid bodies or oil bodies . For a lThe catabolism of LDs into free fatty acids (FAs) is a crucial cellular pathway that is required to generate energy in the form of ATP, and to provide building blocks for biological membrane and hormone synthesis. Lipolysis is a biochemical catabolic pathway that relies on the direct activation of LD-associated lipases, such as adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL) and monoglyceride lipase (MGL) , 10. TogAutophagy is one of the two major degradation pathways in cells supporting cell survival by recycling metabolic components under stress conditions (Ubiquitin-proteasome system being the other pathway). It is initiated by sequestering cytosolic organelles or macromolecules in double-membrane vesicles and delivering them to lysosomes for degradation by the lytic enzymes therein. Cellular building blocks are then released back to cytosol and recycled to ensure cellular homeostasis , 12. BasRecent investigations defined another selective form of macroautophagy termed “lipophagy”. In this autophagy form, LD degradation is controlled by the association of membrane GTPase Rab7 with LDs , 18. MorIn contrast with the traditional view that LDs are simple lipid storage vesicles, because of their dynamic nature and multifunctionality they are today accepted as a distinct intracellular organelles. Recent studies underline physiological importance of these multifunctional organelles, particularly in the context of lipolysis and selective autophagy mechanisms of lipophagy and CMA. Here, we will first summarize biological properties of LDs and then focus on recent findings on molecular regulation of lipolytic and autophagic mechanism. Furthermore, we will discuss the relevance of LDs and related catabolic mechanisms for pathophysiology.Being different from other membrane-enclosed organelles, LDs have a unique structure with a hydrophobic core of neutral lipids surrounded by a monolayer phospholipid membrane, separating hydrophobic neutral lipids from the aqueous cytoplasmic environment .. In theIn mammalian cells, the main constituent (up to 60%) of LD monolayer membranes is phosphatidylcholine (PC) that is followed in abundance by phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), sphingomyelin (SM) and lyso forms of PC and PE –30. PhosBesides membrane phospholipid compositions, LD surface proteins are other factors regulating homeostasis and intracellular interactions of LDs. Membrane surface of LD is decorated with several structural and functional proteins . ProteomIn mammalian LDs, predominant proteins are the members of the PAT protein family, an acronym representing perilipin (PLIN), adipocyte differentiation-related protein , and TIP47 (tail-interacting protein of 47 kDa) proteins. Members of the PAT family share sequence similarity and the ability to bind intracellular LDs, suggesting that they derived from a common ancestral gene . The mosLDs also host many other proteins-related to lipid homeostasis. These proteins can be classified according to their functions, including lipid biogenesis , maintainance of intracellular lipid metabolism (long chain fatty acid CoA ligases) and lipid degradation (patatin-like phospholipase domain containing protein 2 (PNPLA2), CGI-58) .In addition to PAT proteins and lipid homeostasis-related proteins in LDs, there are several groups of proteins that are called ‘refugee proteins’ which seem not to be relevant to the known functions of LDs . These pLD biogenesis is stimulated upon an increase in intracellular free FA levels. In order to prevent lipotoxicity, excessive free fatty acids are converted into neutral lipids and stored in cytosolic LDs. However, recent studies suggested that LDs are not only cytoplasmic but also can be found in the nuclei , 61. AltDue to the unique hydrophobic/hydrophilic (amphipathic) structure of LDs, mechanisms of biogenesis of this organelle in the cell attracted much attention and several hypotheses were proposed –64. BeinNeutral lipid synthesis is regulated by complex pathways involving lipid metabolism enzymes and structural proteins that are permanently or transiently located to the ER and LDs. The first step of neutral lipid synthesis requires free FA activation. As free FA are chemically inert, their activation step is critical for LD biogenesis pathway. In mammalian cells, acyl-coA synthetase (ACS) enzymes activate long chain FAs to acyl-coA by esterifying with coenzyme A (CoA) Fig.  69]. De. De69]. As intracellular FA promote LD formation, synthesized neutral lipids form a ‘lens’ between the leaflets of ER bilayer. Biophysical and in silico predictions suggest that, when TG holding limit of bilayer membranes is reached , the lenOnce LDs are synthesized, they typically keep growing because of the excessive amount of intracellular FA in cells and reach a final size. The size of LDs varies within a wide range (0.4–100 μm) in different cell types . Even inOne possible mechanism is growth of LDs through fusion of highly mobile smaller LDs , 77. AltDrosophila embryos, histones are found in high abundance on the surface of LDs and they are rapidly transferred to the nucleus when needed [Interestingly, LDs were involved in various pathological events and innate immunity . LDs wern needed . Recentln needed . Neuropan needed –92. In an needed . Proteinn needed .As the LDs reside at the center of cellular lipid and energy homeostasis, their catabolism is strictly under the control of hormones and activation of enzymes. So far, LDs are known to break down mostly by lipolysis, however, recent discoveries that showed a molecular connection between lipolysis and autophagy mechanisms led to the identification of the involvement of selective autophagic forms, lipophagy and CMA, in LD catabolism.Under fed conditions, LDs store TAGs mainly in adipose tissues and hydrolysis of ester bonds between long chain FAs and glycerol backbone in TAGs is called “lipolysis”. During the first step of lipolysis, protein kinase A (PKA) phosphorylates one of the PAT protein family member, PLIN1, and leads to its proteasomal degradation . This, rUnder nutrient deprivation, products of lipolysis are secreted from the adipose tissue to the periphery via bloodstream, which are then used for β-oxidation and ATP production. In contrast, in non-adipose tissues, mitochondria or peroxisomes can directly oxidize products of lipolysis through β-oxidation and release acetyl-CoA .Lipophagy was first described in mouse hepatocytes under starvation . It was Substrate labeling is a general mechanism used by cellular degradation machineries. So, how does lipophagic machinery preferentially recognize LDs as substrates? Proteomic analyses of LDs from different organisms showed that membrane GTPase Rab7 is associated with LDs and suggested a universal role of Rab7 in the regulation of LD docking and degradation . InvolveIn adipocytes, the membrane curvature protein Bif-1 was found as a novel regulator protein for lipophagy . InductiC. elegans [Although the role of lipophagy in LD degradation was first described in hepatocytes , 108, se elegans  and some elegans . Indeed,More recently, involvement of another selective type of autophagy, CMA, in degradation of LD-associated PLINs proteins, PLIN2 and PLIN3 was described . In thisEven though basic molecular mechanisms of lipolysis, lipophagy and CMA are different, recent investigations indicate that these independent pathways actually cross-talk. For example, ATG2A, an essential autophagy protein was also found on LDs, and genetic knock-down of ATG2A and ATG2B resulted in defective lipophagy as well as LD accumulation . A recenOn the other hand, the existance of a reverse relationship between lipolysis and lipophagy has also been shown in which lipolysis-dependent LDs breakdown regulated autophagosome formation. LDs was shown in close proximity of autophagosomes with transient ‘kiss and run’ interactions contributing to autophagosome biogenesis . In thisAs LDs play central role in the regulation of intracellular lipid and energy metabolism, abnormalities of LD-related mechanisms, including lipolysis, lipophagy and CMA are involved in many pathological and physiological conditions. For example, neutral lipid storage disease (NLSD), atherosclerosis, obesity etc. , 125.Neutral Lipid Storage Disease (NLSD) is a heterogenous group of rare autosomal recessive disorder characterized by abnormal accumulation of LDs in multiple tissues and lymphocytes. Mutations in one of the two genes coding for ATGL or CGI-58 (proteins located on the surface of LDs) are associated with the NLSD , 127. BoObesity is a common health problem, which is characterized by excessive lipid storage in various cell types such as adipocytes, muscle cells and hepatocytes. Different types and degrees of obesity were shown to be directly related with the lipophagic activity of cells and the size of their lipid storages . AdditioAccumulation of LDs in tissues in high amounts may cause chronic inflammation which is identified as one of the hallmarks of obesity-related metabolic disorders. Indeed, enlarged LDs in the adipose tissue may lead to cellular remodeling, and finally lead to macrophage-driven chronic inflammation . ActivatThe important role of lipophagy regarding LD breakdown in hepatocytes suggests that impaired lipophagy may contribute to the development of steatotic liver diseases such as non-alcoholic and alcoholic steatohepatitis . These dPromotion of lipophagy by resveratrol treatment was shown to attenuate methionine choline-induced non-alcoholic steatohepatitis . ConsistLiver fibrosis may be the first step of more serious cirrhotic liver conditions. Hepatic stellate cells (HSCs) activation for the development of this condition, and lipophagy plays a role as well , 147. HSToday, it is well known that after many years of chronic non-alcoholic or alcoholic steatotic liver diseases or hepatitis virus infection hepatocellular carcinoma (HCC) might develop. Hepatitis B virus (HBV) and hepatitis C virus (HCV) replication was shown to be induced by autophagy activation both in vitro and in vivo studies , 150. A LIPA gene encoding lysosomal acid lipases (LAL). Deficient LAL activity lead to insufficient lipolysis and eventually intracellular accumulation of cholesterol ester and TGs [Cholesterol ester storage disease (CESD) is an autosomal recessive genetic disease caused by the mutation of the  and TGs . The mos and TGs . The inv and TGs . LDs are and TGs .Accumulation of cholesterol in macrophage foam cells also contribute to another common disease, atherosclerosis. The main cause of the disease is the accumulation of excessive cholesterol in arterial walls eventually leading to heart failure, stroke and cardiac dysfunction. Excessive cholesterol is esterified by ACAT enzymes and stored as cholesterolester (CE) in LDs of macrophages. Studies revealed that LD-associated proteins ACAT1 and ABCA1 regulating cholesterol esterification play crucial roles in atherosclerosis. In hyperlipidemic mice, deletion of ACAT1 results in both impairment of ABCA1 dependent cholesterol efflux and elevated atherosclerosis . MoreovePdcd4 knockout mice displayed increased atherosclerosis, indicating a link between autophagy and atherogenesis [The importance of lipophagic activation in controlling intracellular LDs level and the recent finding that lipophagy contribute LD mobilization in macrophages provides a new point of view in the pathogenesis of atherosclerosis. In addition to the dysfunction of above mentioned LD-associated proteins, it is likely that defective lipophagy may compromise the chronic exposure to excessive circulating lipids of the artery wall macrophages and may result in their remodelling into “foam cells”. However, the significance of insufficient lipophagy underlying foam cell formation or progression is still not known. On the other hand, in a recent study on the tumor-supressor gene programmed cell death 4 (PDCD4), it was demonstrated that the protein inhibited autophagy in macrophages, and ogenesis .AGPAT2), seipin (BCSL2) and caveolin (CAV1). In addition, lamin A/C (LMNA), peroxisome proliferator-activated receptor-γ (PPARG), Akt2/protein kinase B (AKT2), and endoprotease Face-1 (ZMPSTE24) were identified as defective genes in partial lipodystrophies [Apart from excessive accumulation of lipids, deficiency of LDs in cells may lead to lipodystrophies. Particularly, defects in the synthesis of neutral lipids lead to deficiencies in LD formation and lead to the formation of abnormal or degenerative white adipose tissue. Genetic causes of lipodystrophies include various genes encoding proteins related to LD synthesis, storage and regulation such as acylglycerol-phosphate acyltransferase (trophies . Insuffitrophies .In recent years, except the neutral lipid storage function of LDs, understanding of their various metabolic roles and intracellular interactions with many compartments makes this field as an attractive research area. Novel findings in selective types of autophagy, lipophagy and CMA, also contributed to a better of understanding of intracellular catabolic pathways regulating LDs. More importantly, signals that madiate the crosstalk between lipolysis and lipophagy lead to the consideration of these mechanisms as promising therapeutic targets. However there are a large number of questions that still need to be answered. Particularly, the pathophysiological relevance of LDs and their catabolic mechanisms must be further examined in order to discover potential therapies for common metabolic diseases such as obesity or atherosclerosis.


In addition, undifferentiated iPSCs in the differentiation culture generate safety concerns. On the other hand, somatic stem cells or progenitors—if can be identified, isolated and expanded—could offer a better and safer choice for regenerative medicine.Lung-related diseases are the third-leading cause of human death throughout the world. Lethal lung diseases such as chronic obstructive pulmonary disease (COPD), pulmonary fibrosis and bronchiectasis are characterized by irreversible, progressive damage of the lung tissue. The ability to regenerate human lung tissue, if successful, would constitute a breakthrough in modern medicine. Despite years of research, however, currently there is no effective strategy to regenerate lost bronchioles or alveoli in humans. Stem cell-based regenerative medicine holds great potential for combating tissue damage in lung diseases and other disorders by providing unlimited materials for transplant  by SOX9 expression. SOX9 is a known marker for embryonic lung progenitor cells and also stem/progenitor cells of other tissues such as liver and gut. Interestingly, in gut the SOX9+ progenitors reside in the crypt, an invaginated structure similar to the airway rugae. From a trace amount of bronchoscopic brush-off lung tissues, the authors isolated SOX9+ BCs and expanded them in vitro expanded cells into immune-deficient mice, Ma et al. generated a chimeric lung with both human and mouse tissues. The regenerated human alveoli established intact vasculature system and were functional. However, human type II alveoli cells were not generated, which is likely due to the limited potency of the human cells and/or species difference. More importantly, in this study, for the first time the authors explored the clinical feasibility of autologous SOX9+ BC transplantation to treat two patients with bronchiectasis. The results showed recovery of patients’ pulmonary function and improvement of bronchi dilation on CT over time. Although it is a very small sample size, the results of this pilot trial are consistent with their observation in the mouse model, and pave the road for a large-scale controlled clinical study in the future. Interestingly, the authors also showed that the anti-lung fibrosis drug Pirfenidone could boost stem cell transplantation efficiency in a TGFβ-dependent manner, suggesting the possible combination of traditional chemical pills and stem cell transplantation for combating lung diseases.By transplanting the Although Ma et al. established an applicable system for human lung regeneration, there are still several issues remain unsolved—for instance, whether the stem cell transplantation therapy works well in treating other lung-related diseases, such as emphysema or idiopathic pulmonary fibrosis, and the long term effect of stem cell transplantation remains unexplored.In summary, the identification and culture of human lung stem/progenitor cells reported in this study hold great potential for developing regenerative medicine therapy for treating lung diseases. Considering chronic lung diseases are life threatening with only palliative treatments available, the significance of lung stem/progenitor cell-based transplantation would be tremendous, which provides exciting translational opportunities ahead.


Pancreatic cancer is one of the deadliest types of cancer, and despite extensive basic and pre-clinical research efforts, existing therapeutics remain largely ineffective. During pancreatic cancer progression, neo-plastic transformation of epithelial cells is typically accompanied by a fibrotic response, driven by activation of stromal cells, and which leads to extensive deposition and remodeling of the pancreatic extracellular matrix (ECM) and to reduced tumor vasculature patency . The resin vivo) imaging technologies and high-end mouse and patient-derived models of pancreatic cancer to uncover a novel therapeutic approach, whereby transient or pulsed ‘priming’ of the tumor using Fasudil, a pharmacological Rho-kinase inhibitor, leads to a decrease in ECM deposition and remodeling and tips the balance in favor of the anti-tumor properties of the matrix while maintaining normal tissue functions of the organ [Recently, we used multi-photon intravital (he organ . As suchAssessment of micro-metastatic events in secondary sites such as the liver revealed that ‘priming’ with Fasudil also impaired cancer cells resistance to shear stress in the circulation, reduced cell streaming and coordinated colonization of the liver, while also blocking ECM remodeling, which is typically required to form a favorable niche at the secondary site Figure . TogetheThe dual effect of Fasudil ‘priming’ on both the ECM and tumor vasculature highlights the intricate crosstalk between distinct stromal compartments Figure . This isPancreatic cancer is a highly heterogeneous disease, and development of patient-centered, targeted therapeutics is emerging as a promising approach. In our study, assessment of ‘priming’ with Fasudil in stratified patient-derived xenografts demonstrated that the level of response to transient ROCK targeting is intimately linked to the initial tumor ECM signature Figure . This coIn conclusion, chronic treatment regimes are often administered at limited tolerable doses and lead to difficult to manage side effects. Moving forward, researchers and clinicians will have to rethink treatment timeline and dosages; we suggest that iterative ‘priming’ to re-equilibrate the tumor-stroma feedback loop may be of great benefits for pancreatic cancer care.


Epidemiology: incidence and prevalence:About 5% of the world’s population has chronic hepatitis B virus (HBV)infection, and nearly 25% of carriers develop chronic hepatitis, cirrhosis, andhepatocellular carcinoma (HCC). The prevalence of chronic HBV infection in humanimmunodeficiency virus (HIV)-infected individuals is 5%-15%; HIV/HBV coinfectedindividuals have a higher level of HBV replication, with higher rates ofchronicity, reactivation, occult infection, and HCC than individuals with HBVonly. The prevalence of HBV genotype A is significantly higher among men whohave sex with men (MSM), compared with the rest of the population.Molecular mechanisms of infection, pathology, andsymptomatology: HBV replication begins with entry into thehepatocyte. Sodium taurocholate cotransporting polypeptide was identified in2012 as the entry receptor of HBV. Although chronic hepatitis B develops slowly,HIV/HBV coinfected individuals show more rapid progression to cirrhosis and HCC.Transmission and protection: The most common sourcesof HBV infection are body fluids. Hepatitis B (HB) vaccination is recommendedfor all children and adolescents, and all unvaccinated adults at risk for HBVinfection . Although HB vaccinationcan prevent clinical infections (hepatitis), it cannot prevent 100% ofsubclinical infections. Treatment and curability:The goal of treatment is reducing the risk of complications(cirrhosis and HCC). Pegylated interferon alfa and nucleos(t)ide analogues (NAs)are the current treatments for chronic HBV infection. NAs have improved theoutcomes of patients with cirrhosis and HCC, and decreased the incidence ofacute liver failure. STI andsexually transmitted disease (STD) should beused, the American Sexual Health Association (ASHA) makes a distinction between thetwo terms STI.A sexually transmitted infection (STI) is defined as an infection that results fromtransmission of a pathogenic organism by sexual contact  and that accounts for anoticeable amount of illness in the general population or in a defined subpopulation1inutero or during delivery. As a typical STI, HBV infection is present inall types of populations. Sexual contact and vertical transmission from mother toinfant are responsible for the large majority of HBV infections worldwide Organisms such as hepatitis B virus (HBV) that cause infections via sexualtransmission can also cause infections via other routes, such as percutaneoustransmission by contaminated needles and vertical transmission HBV infection as an STI is well documented. It is mainly common among men who havesex with men (MSM), because multiple partners are common in this population; andanal sex is usually more traumatic than vaginal intercourse, resulting in increasedrisk of exposure to blood 4Routine immunization with hepatitis B (HB) vaccine is strongly recommended for theprevention of HBV infection in MSM and other individuals at risk for STIs. HBvaccination of adults has been found to be effective at conferring immunity toindividuals who are exposed to HBV via sexual transmission. However, the firstpriority is directly preventing the spread of HBV by the most reliable andappropriate method, which is use of a condom for safe sexual contact.Chronic HBV infection is the cause of chronic hepatitis, cirrhosis, andhepatocellular carcinoma (HCC) The purpose of this article is to provide up-to-date information on HBV and HBVinfection as a major STI.Hepadnaviridae. It is a verysmall, partially double-stranded DNA virus. Humans are known to be the onlynatural host. HBV reaches the liver through the systemic circulation and canonly replicate in hepatocytes HBV is classified in the family The infectious HB virion has a diameter of 42-47 nm and is a double-shelledparticle in serum. Its concentration can be as high as 108 virions per mL611The HBV genome consists of a partially double-stranded, circular DNAmolecule. Its total genome is 1700-2800 nucleotides long or 3020-3320nucleotides long . Everynucleotide in the genome is active in 4 highly overlapping coding regions,or open reading frames (ORFs), as shown in Fig. 1 13141513HBV infection can cause acute hepatitis, acute liver failure, or chronichepatitis, or can cause an asymptomatic infection. Chronic HBV infection canresult in cirrhosis or HCC. The probability that a person with HBV infectionwill progress to chronic infection is strongly dependent on the person’s ageat the time of HBV infection In addition to age when first infected, the rates of progression of HBVinfection are generally affected by gender, the level of HBV replication,HBV genotypes and variants, coinfecting viruses , hostlifestyle , exposure to carcinogenic substances, hostgenetic factors, and probably comorbidities  The natural history of chronic HBV infection can be separated into fivestages, which are not necessarily sequential The initial stage represents the incubation period. When HBV is activelyreplicating, HBV DNA, HBeAg, and HBsAg are detected in the serum HBeAg can be detected in the serum. A somewhat lower level of HBV DNA isseen in some patients, who are clearing HBV, than in stage 1 232627The stage of inactive chronic hepatitis may follow the seroconversion toanti-HBe and clearance of HBeAg. The stage is characterized by very lowor undetectable HBV DNA in the serum and serum aminotransferase levelsin the reference range 31The HBeAg-negative chronic hepatitis stage may follow clearance of HBeAgand development of anti-HBe during the inactive chronic infection stage(stage 3) or directly from the immune active/clearance stage (stage 2).It is important to distinguish inactive HBV carriers from individualsnegative for HBeAg who have chronic hepatitis. The former patients willhave a good outcome with a very low risk of complications, while thelatter have a high risk of progressive liver disease, includingdecompensated cirrhosis and HCC In the final stage, HBV reactivation may occur spontaneously or may betriggered by cancer chemotherapy or other immunosuppressive therapies,and may result in serious acute-on-chronic hepatitis. Occult HBVinfection is defined as persistence of HBV DNA in the liver ofindividuals in whom HBsAg is undetectable in the blood. Individuals whohave cleared HBsAg and are negative for serum HBV DNA but anti-HBcpositive may develop reactivation if they are being treated with potentimmunosuppressive medications HBsAg loss before the onset of cirrhosis is associated with improvedoutcome, with a reduced risk of cirrhosis, decompensation, and HCC NTCP was recently identified as a receptor for HBV entry, which enabled theestablishment of a susceptible cell line that can efficiently support HBVinfection. This discovery should lead to a deeper understanding of therequirements for effective HBV infection and clarification of the molecularmechanism of HBV entry.The replication cycle of HBV begins with entry of the virus into hepatocytes,which is mediated by the binding of the pre-S1 region on the virion envelope tothe hepatocellular NTCP This cccDNA is responsible for viral persistence and is highly resistant toantiviral therapy. It serves as the template for the transcription of viralmRNAs. The pregenome mRNA serves for the synthesis of core protein (nucleocapsidsubunit) and viral reverse transcriptase. The viral genome is replicated byreverse transcription of pregenomic RNA. During this process, both the proteinand the RNA are removed An increase in the level of viral envelope proteins inhibits synthesis of highlevels of cccDNA, which can be toxic to hepatocytes. Once partiallydouble-stranded DNA has been produced, nucleocapsids can undergo a maturationevent that enables them to obtain an outer envelope via budding into the ER. Themature nucleocapsids may be recycled into the nucleus to mediate viralpersistence, or secreted as Dane particles through exocytosis to infect otherhepatocytes 3738More than one third of the world’s population are estimated to be infected withHBV. About 5% of the world’s population are chronic carriers of HBV, and HBVinfection causes more than one million deaths every year Based on the data from Western cohorts, HIV/HBV coinfection has a profound impacton almost every aspect of the natural history of HBV infection 414345An estimated 240 million people are chronically infected with hepatitis B In low-prevalence (< 2%) regions, the lifetime risk of HBV infection is lessthan 20%. Sexual transmission and percutaneous transmission during earlyadulthood are the main routes of spreading the infection. About 12% ofHBV-infected individuals live in the low-prevalence regions, which include NorthAmerica, northern and western Europe, Australia, and New Zealand 48In intermediate-prevalence (3% - 5%) regions, sexual and percutaneoustransmission and vertical transmission during delivery are the major routes ofinfection. These regions include eastern and southern Europe, Japan, theMediterranean basin, the Middle East, Latin and South America, and Central Asia.One study reported that approximately 43% of HBV-infected individuals live insouthern, central, and western Asia; eastern Europe; Russia; and Central andSouth America. The lifetime risk of HBV infection is 20% - 60% In high-prevalence (10% - 20%) regions, transmission occurs predominantly ininfants and children. During early childhood, HBV is transmitted vertically fromthe mother to infant or occurs via close contact. In some regions, percutaneousexposure to contaminated needles or an unsafe injection is also a possible routeof HBV infection. Since most infections in children are asymptomatic, there islittle evidence of acute HBV-related disease, but the rates of chronic liverdisease and HCC in adults are high. Approximately 45% of individuals infectedwith HBV live in high-prevalence regions. The lifetime risk of infection ishigher than 60%, as demonstrated by the presence of anti-HBc in sera adw2, adw4,adrq+, adrq, ayw1,ayw2, ayw3, ayw4 andayr - have been identified Based on some of the antigenic determinants of HBsAg, nine serological types -referred to as subtypesetal. speculated in their review that HBV subgenotypes A2 and C arelikely to predominate in populations at high risk of infection via sexualtransmission 58HIV-seropositive MSM populations predominantly coinfected with HBV genotype Ahave been reported in European countries and Japan 5455Individuals infected with genotypes C and F have higher rates of HCC thanindividuals infected with genotypes B and D 60616364266768Currently, most liver biopsies are performed to confirm the existence ofchronic hepatitis and to determine its level of activity. This sectionmainly describes chronic hepatitis, which plays an important role in HBVinfection.Because acute hepatitis B is always diagnosed by clinical symptoms andserologic markers related to HBV infection, liver biopsies are not oftenperformed. In general, acute hepatitis shows more areas of spottyparenchymal inflammation and more severe damage than typical chronichepatitis. The lesions mainly contain diffuse sinusoidal and portalmononuclear infiltrates ,swollen hepatocytes and/or necrotic hepatocytes  70In chronic HBV infection, there is a varying degree of predominantlylymphocytic portal inflammation with interface hepatitis and spottylobular inflammation. The inflammation is minimal in the immune-tolerantor inactive chronic infection stages, but is prominent in theimmune-active stage. Bridging necrosis is identified as inflammation"connecting" portal tracts to one another or to central veinsThe hepatocytes that express a high level of HBsAg may have a"ground-glass" cytoplasm, which can be highlighted by specialimmunohistochemical stains (Shikata’s orcein and Victoria blue).Ground-glass hepatocytes may also be seen in other conditions Cirrhosis is diagnosed when the loss of normal central-portalrelationships is observed. The atypical enlargement of nuclei with anincrease in the nuclear-cytoplasmic ratio, known as "large cellchange", is very common in cirrhosis. This cytologic abnormalityshould only be used to support the evidence of regeneration andarchitectural abnormalities, which is used for diagnosing cirrhosisThe serologic markers of HBV infection are as follows: HBsAg and thecorresponding antibody anti-HBs, HBeAg and the corresponding antibodyanti-HBe, immunoglobulin M antibody to hepatitis B core antigen (IgManti-HBc), immunoglobulin G antibody to hepatitis B core antigen (IgGanti-HBc), and serum HBV DNA. The diagnosis of acute or chronic HBVinfection requires serologic testing (Table 3) Total anti-HBc is present over the entire lifetime of the infectedindividual. It is found in individuals with chronic HBV infection and inthose who recover from HBV infection “Serologic markers related to HBVinfection”. As described in that subsection, thepersistence of HBeAg indicates the transition to chronic HBV infection The incubation period (duration from exposure to HBV to onset of symptoms) ofHBV-infected individuals with acute hepatitis ranges from 60 to 150 days,with an average of 90 days 7510The natural history of HBV infection, including the transition to chronicinfection, is described in the “Etiology” section. Chronic HBV infection isdefined as either the presence of HBsAg in the serum for at least 6 monthsor the presence of HBsAg in a person who tests negative for IgM anti-HBc787981The manifestations of HBV infection during the acute phase vary fromsubclinical hepatitis to acute hepatitis and acute hepatic failure. Duringthe chronic phase, disease progression varies from asymptomatic chronicinfection to chronic hepatitis, cirrhosis, and HCC Acute hepatitis B is an illness that begins with general fatigue, loss ofappetite, nausea, vomiting, body aches, low-grade fever, dark urine, andjaundice. The illness lasts for several weeks and then gradually improves inmost affected individuals. A few individuals may develop more severe liverdisease (acute hepatic failure) and may die. In addition, acute hepatitis Binfection may be entirely asymptomatic and may go unrecognized Some acute hepatitis B patients (about 1%) may develop acute liver failure,which is characterized by evidence of decompensated liver disease and isfatal in up to 50% of cases Individuals with chronic HBV infection may be asymptomatic or may manifestthe signs and symptoms associated with chronic hepatic inflammation.Patients with chronic active hepatitis, especially during the replicativestage, can manifest symptoms similar to acute hepatitis . Physical examination ofpatients with chronic HBV infection can reveal the typical characteristicsof chronic liver disease, including hepatomegaly, splenomegaly, musclewasting, palmar erythema, spider angioma, and vasculitis.In cases with progressive liver disease, the following manifestations may bepresent: hepatic decompensation, hepatic encephalopathy, somnolence,disturbed sleep patterns, mental confusion, coma, ascites, varicealbleeding, coagulopathy, ascites, jaundice, peripheral edema, gynecomastia,testicular atrophy, and collateral abdominal veins (caput medusa). Pleuraleffusion and hepatopulmonary and portopulmonary syndrome may occur inpatients with cirrhosis. Patients with cirrhosis may have the followingfindings: ascites, jaundice, history of variceal bleeding, peripheral edema,gynecomastia, testicular atrophy, and collateral abdominal veins.Extrahepatic manifestations of HBV infection occur in 1% to 10% of patients,and include serum-sickness-like syndrome, acute necrotizing vasculitis(polyarteritis nodosa), membranous glomerulonephritis (MGN)8690A variety of cutaneous lesions can appear during the early course of viralhepatitis, including transient maculopapular rash.As described previously, HBV is transmitted mainly via percutaneous or permucosalexposure to HBV-containing body fluids. The most critical source of infection isblood (serum) HBV is efficiently transmitted by sexual contact 24Heterosexual transmission is still important, as shown by the 40% transmissionrate to nonimmune partners of patients with acute HBV hepatitis or chronic HBVinfection 9698The 2015 Centers for Disease Control and Prevention (CDC) guidelines describefive major strategies for the prevention and control of STIs (Table 5) Over the past 10 years, condom use by unprotected heterosexuals has increasedin the United States, suggesting that information on the prevention of STIsis being widely disseminated and understood In summary, safe sex practices, including minimizing the number of sexpartners and using barrier protection, can reduce the risk of HBVinfection.Both HBIG and HB vaccines have been approved for preventing HBV infection103HBIG is prepared from human plasma containing a high concentration ofanti-HBs and provides short-term (3 to 6 months) protection from HBVinfection. It is typically used as post-exposure prophylaxis along with HBvaccination for individuals who have never been vaccinated or who have notresponded to HB vaccination. The recommended dose of HBIG is 0.06 mL/kgHB vaccines contain HBsAg that is produced by a recombinant yeast strain106HB vaccination is the most effective method of preventing HBV infection 109HB vaccine is available for younger children, adolescents, and healthy adults6HB vaccine-induced immune memory has been established to last for more than20 years 111112In 1992, WHO recommended that all countries should introduce universal HBvaccination into their routine immunization programs Both passive-active postexposure prophylaxis (simultaneous administration ofHBIG and HB vaccine at separate sites) and active postexposure prophylaxis have been demonstrated to be highlyeffective for preventing HBV infection The primary treatment goals for patients with HBV infection are preventing theprogression to severe liver disease. The prevention of cirrhosis, hepaticfailure, and HCC are most important. The risk factors for progression of chronicHBV include male gender, older age, family history of HCC, elevatedalpha-fetoprotein (AFP) level, and coinfection with other viruses  For the best outcome, a synergistic approach that decreases the viral load anduses immunotherapeutic interventions to boost the immune response is neededPatients with acute hepatitis B are treated by supportive care, with nospecific treatment. Patient care is focused on maintaining comfort andadequate nutritional balance, including replacement of fluids lost fromvomiting and diarrhea. Patients with chronic HBV infection should bereferred for evaluation to a provider experienced in the management ofchronic HBV infection 5 copies/mL)  and the serum ALT level is elevated  for 3-6 months. For patients with chronic HBVinfection who are negative for HBeAg, treatment is advised when the serumlevel of HBV DNA is at or greater than 2,000 IU/mL (104copies/mL) and the serum ALT is elevated  for 3-6 months In general, for patients with chronic HBV infection who are positive forserum HBeAg, treatment is advised when the serum level of HBV DNA is at orgreater than 20,000 IU/mL (10Treatment of HIV infection with nucleos(t)ide analogs active against HBVgreatly improves the outcomes of hepatic disease, including cirrhosis andHCC, in HIV-HBV coinfected patients, especially when tenofovir is part ofthe antiviral regimen The National Institutes of Health (NIH) also advises that immediate therapyis not usually indicated for the following patients: 1) patients who are inthe immune-tolerant stage, with chronic hepatitis B and high serum levels ofHBV DNA but normal serum ALT levels or little activity on liver biopsy; 2)patients who are in an inactive chronically infected/low replicative stageand have low serum levels of or undetectable HBV DNA and normal serum ALTlevels; and 3) patients who are not immunosuppressed and have latent HBVinfection, defined as detection of HBV DNA in the absence of HBsAg The therapeutic agents cleared by FDA for the treatment of chronic hepatitisB can achieve sustained suppression of HBV replication and remission ofliver disease IFNs are naturally produced cytokines. They induce direct antiviral activityby stimulating the host’s antiviral immune response and mediatingconflicting effects on viral replication. PEG-IFN-α 2a has a longerhalf-life and enhanced efficacy relative to standard IFN-α. Pegylationlowers the rate of absorption following subcutaneous injection, reducesrenal clearance, and decreases the immunogenicity of IFN The advantages of IFN therapy are the absence of viral resistance, the finitecourse of treatment , an increased chance of sustainedvirological response (SVR), and HBeAg and HBsAg clearance; compared withpatients treated by NAs 25The NIH recommends nucleos(t)ide therapy for the treatment of HBV-infectedpatients with acute liver failure as well as for cirrhotic patients who arepositive for serum HBV DNA; and for patients with clinical complications,cirrhosis, advanced fibrosis with serum positive for HBV DNA, orreactivation of chronic HBV during or after chemotherapy orimmunosuppression Entecavir, a guanosine nucleoside analogue, is a first-line agent for thetreatment of HBV infection Results of a retrospective study indicated that assessment of serum HBV DNAlevels 12 months after initiation of entecavir therapy may be useful forevaluating entecavir therapy for NA-naïve, HBV-infected patients In another study, after 240 weeks of continuous entecavir therapy forHBeAg-positive patients, 94% of patients had less than 300 copies/mL ofserum HBV DNA, and 80% had normal ALT levels. An additional 23% of patientsachieved HBeAg seroconversion, and HBsAg disappeared in 1.4% of thepatients. Only 1 patient developed resistance to treatment with entecavirwithin 5 years of treatment Another study found that long-term treatment with entecavir  for NA-naïve patients withchronic HBV infection and advanced fibrosis or cirrhosis, resulted indurable virologic suppression, continued histologic improvement, andreversal of fibrosis or cirrhosis Tenofovir is the newest antiviral agent. It is a nucleotide-analogue(adenosine monophosphate) inhibitor of viral reverse transcriptase. It maybe used as first-line therapy for treatment-naïve patients The tests that should be used and the frequency of testing will depend on thepatient’s serological profile (HBeAg-positive or -negative) and HBV DNAviral levels For individuals with inactive chronic HBV infection, the current guidelinesrecommend monitoring for serum HBV DNA and ALT levels at least annually232828Despite notable progress regarding many aspects of HBV infection, particularlywith respect to prevention and treatment, chronic HBV infection remains strictlynoncurable, because residual HBV cccDNA can always be detected in the liver,even after clearance of HBsAg and development of anti-HBs in the serum There is ongoing discussion on the meaning of "cured’ of chronic HBVinfection". The primary treatment goal for HBV infection is to improvepatient quality of life and reduce the risk of death from liver disease "Absolute cure" means that the patient is free of HBV. That is, thereare no HB virions and cccDNA anywhere in the body, including hepatocytes. Thepatient recovers to the degree of health and medical condition prior to HBVinfection, and the probability of developing cirrhosis or HCC depends on age andgender. Although this type of cure is uncommon, it is the most desirable "Functional cure" means that HBV progression can be controlled. Thepatient recovers to his or her state of health equal to that of a person who hasrecovered spontaneously from HBV infection. Both have a similar likelihood ofdeveloping cirrhosis or HCC. Current therapy can only achieve "functionalcure" through suppression of HBV replication "Apparent virologic cure" is defined as a sustained off-drugsuppression of virologic markers and the normalization of liver function. Thislast definition includes an SVR, which is the ongoing suppression of viral loadfollowing the cessation of therapy, and adds the disappearance of allcirculating viral markers (seroclearance), and the possible suppression ofcccDNA. A complicating factor with HBV infection is that patients who haveachieved a serologic resolution of infection  can develop reactivation of their diseasebecause of immunosuppression or the use of anti-inflammatory medications 142An "apparent virologic cure" or "functional cure" as adesirable endpoint for therapy is supported by a recent study looking at therisk of HCC in patients with or without spontaneous seroclearance of HBVseromarkers 146HBV infection is one of the common STIs having a major worldwide impact on apatient’s clinical health status and on public health, and is also associated withliver-related morbidity and mortality. New HBV infections in industrializedcountries are becoming increasingly concentrated among individuals at risk for STIs,infants, and injection drug users. HB vaccines have been an effective preventionstrategy for individuals at risk through sexual exposure, especially MSM andheterosexuals with multiple sex partners. The proper education of persons at riskfor STIs may also help with their acceptance of HB vaccination.Regarding the persistence of HB vaccine-induced immunity, the effectiveness ofroutine HB vaccination might not last long enough to prevent 100% of HBV infections.In our opinion, postvaccination serologic testing, especially for anti-HBs, shouldbe introduced for groups at high risk for HBV infection, after carefulconsideration. Potential causes of vaccine failure, such as infection with HBVvariants, require further study. The need for booster doses to preservevaccine-induced immunity should be evaluated regularly, especially for infants whosemothers were infected, individuals with occupational risk, sexually activeindividuals such as MSM, or individuals under immunosuppression.


Various neurological diseases have recently been associated with neuroinflammation and worsening outcomes. Subarachnoid hemorrhage has been shown to generate a potent neuroinflammatory response. Heparin is a potential effective anti-inflammatory agent to prevent initial injury as well as delayed neurological decline. Different mechanisms of action for heparin have been proposed including, but not limited to the binding and neutralization of oxyhemoglobin, decreased transcription and signal transduction of endothelin-1, inhibition of binding to vessel wall selectins and vascular leakage into the subarachnoid space as well as direct binding and neutralization of inflammatory molecules. With a reasonably safe side-effect profile, heparin has shown significant promise in small series in human studies of aneurysmal subarachnoid hemorrhage in decreasing both initial and delayed neurological injury. Further studies are needed to validate various neuroprotective features of heparin in subarachnoid hemorrhage as well as other disease states. Neuroinflammation has been recently associated with worse functional outcomes in patients afflicted by a plethora of neurological diseases, but especially in aneurysmal subarachnoid hemorrhage (aSAH) . InflammUnfractionated heparin is a highly sulfated glycosaminoglycan polymer with the most negative charge of any biological molecule . Inflammin vitro models  and the ET-1 promoter. In addition, heparin decreased the expression of the erythroid transcription factor family (GATA)-binding capacity, which is essential for ET-1 function in the endothelial cells , 11. ET-o models , 13.Heparin and its low-molecular weight derivatives are potent inhibitors of the adhesion molecules P- and L-selectin, which mediate leukocyte rolling, the initial event governing leukocyte transmigration from vessel walls into areas of inflammation , 15. TheTranslocation of inflammatory leukocytes into an injured area through vascular leakage is a hallmark of the initiation of the inflammatory response. Presence of leukocytes in the subarachnoid space is a specific marker of inflammation . The accPrior studies have also shown that microthromboembolisms may have contributed to delayed neurological deficits, therefore possibly implicating the anticoagulation effect of heparin in the neuroprotective effects observed . This hySome authors hypothesize that a combination of the hemorrhage volume, vasoparalysis, and decreased cerebrospinal fluid resorption associated with aSHA triggers an increase in intracranial pressure leading to significant transient ischemia. This has been considered by various authors to be the cause of the initial neurological injury following the ictus, especially when associated with loss of consciousness at presentation , 29. HepThe evidence supporting heparin’s anti-inflammatory role is further supported with evidence from traumatic brain injury (TBI) and chronic neurodegeneration research. Nagata et al. has shown that early administration of heparin is associated with a significant decrease in post-TBI inflammation and preservation of cognitive outcomes. These results were further supported by prior studies investigating the role of low-molecular weight fractionated heparin, enoxaparin , 33–35. In addition to the transient ischemia state associated with SAH, significant vasogenic edema and blood–brain barrier dysfunction plague this patient population and represent a dismal prognostic factor . HeparinThese neuroprotective effects have been shown to correlate with a decrease in clinical vasospasm and a specific decrease in the delayed neurological injury, namely long-term cognitive decline following subarachnoid hemorrhage , 44, 45.Heparin is today a venerable, ever-young drug that has not ceased to bewilder and amaze. With its seemingly ubiquitous properties, heparin seems to show promise in various neuropathologies, with a predictable and manageable side-effect profile. Further research is needed to establish heparin as a completely safe and effective intervention in patients with subarachnoid hemorrhage. Together, with its success in other experimental neurological insults such as TBI, stroke, meningitis, cancer, etc., heparin seems to be emerging as a potential silver bullet for mitigating the delayed neurological injury commonly seen after aSHA.RJ designed the concept of the review. NK conducted the review, compiled the information, and drafted the initial manuscript. Both authors critically reviewed and approved the final version of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


There is no consensus on the best technology to be employed for tracheal replacement. One particularly promising approach is based upon tissue engineering and involves applying autologous cells to transplantable scaffolds. Here, we present the reported pre-clinical and clinical data exploring the various options for achieving such seeding.Various cell combinations, delivery strategies, and outcome measures are described. Mesenchymal stem cells (MSCs) are the most widely employed cell type in tracheal bioengineering. Airway epithelial cell luminal seeding is also widely employed, alone or in combination with other cell types. Combinations have thus far shown the greatest promise. Chondrocytes may improve mechanical outcomes in pre-clinical models, but have not been clinically tested. Rapid or pre-vascularization of scaffolds is an important consideration. Overall, there are few published objective measures of post-seeding cell viability, survival, or overall efficacy.. Systematic in vivo work is required to assess differences between tracheal grafts seeded with combinations of clinically deliverable cell types using objective outcome measures, including those for functionality and host immune response.There is no clear consensus on the optimal cell-scaffold combination and mechanisms for seedingThe online version of this article (10.1007/s40778-017-0108-2) contains supplementary material, which is available to authorized users. Treatment outcomes for long-segment tracheal disease in children have been steadily improving over the last decade, due mostly to advances in the slide tracheoplasty technique and improvements in post-operative care . However. Personalized scaffolds created in this way should not evoke conventional immune rejection responses and can thus be implanted without the need for immunosuppressive medication. In children, functional regeneration and remodeling of the replaced tissue might obviate the risk of the child outgrowing the transplant and needing serial re-transplantation.Interest in the field of regenerative medicine has grown exponentially in recent decades, and the subfield of tissue engineering sits at the intersection between cell biology, materials science, and engineering. In contrast to passive implants and medical constructs that are already widely employed across human and veterinary medicine, tissue-engineered medical devices aim to functionally repair, replace, or regenerate living tissue , 9. The The trachea was initially considered, perhaps naively, to be a convenient “starter organ” on which to concentrate tissue engineering efforts, due to its relatively simple tubular anatomy and “basic” primary function of passive air conduction to the lungs . Given tHere, we critically review recent advances in the field, focusing on the application of autologous cells in tissue-engineered tracheal replacements and, specifically, on the use of such constructs in clinically relevant in vivo orthotopic transplantation models.The ideal tissue-engineered scaffold for airway transplantation would be capable of promoting exogenous cell engraftment and endogenous cell ingrowth, proliferation, and appropriate differentiation, while maintaining a patent airway. Moreover, this scaffold must be able to promote the rapid establishment and support of vasculature, to allow cell survival and functional differentiation . To dateThe alternative “synthetic” strategy employs non-toxic materials, such as synthetic polymers, to create an entirely de novo scaffold . ScaffolAs yet, there is no international consensus on the ideal biomaterial for supporting tracheal regeneration in vivo . The resPublished clinical data are limited to single, disparate, case reports, in which there are often unique and specific confounding issues associated with individual patient’s anatomical anomalies or co-morbidities. In such reports, it is impossible to establish a relationship between clinical outcomes and particular mechanistic processes from the use of specific cells and scaffolds. However, the synthetic strategy has recently largely fallen out of favor in Europe and the USA in the light of concerns raised regarding the conduct of the research reported in the synthetic case , 36. Rep. While seeded somatic cells have not been shown to persist long-term within tissue-engineered grafts after transplantation, they seem to have an essential role in tissue remodeling and in vivo functional regeneration [The main property of an ideal tracheal replacement is the mechanical ability to withstand collapse under the physiological internal and external pressure changes of respiration. In addition, the proximal airways play an active role as the frontline defense against inhaled pathogens. The highly specialized pseudostratified ciliated epithelium, containing cells of both innate and adaptive immune systems, acts to trap and remove inhaled pathogens and debris. Overall, the current key goals in the field of tracheal replacement therapies are (1) to generate constructs that recapitulate native tracheal biomechanics, (2) to support a functional mucosa, and (3) to rapidly re-vascularize to ensure cell survivalneration . Unseedeneration . Howeverneration •. This iReflective of the tissue composition of the native trachea, the three most widely studied autologous cell types for tracheal seeding in the pre-clinical setting  are a popular choice for recellularization in many tissue-engineered organ types  due to tMSCs are thought to be somewhat immunoprivileged cells, and they possess potent immunosuppressive properties, particularly against allogeneic T cells . These cThere is increasing pre-clinical evidence to support the benefit of MSC seeding for tracheal tissue engineering, albeit in relatively small-scale studies. Suzuki et al. compared the use of allogeneic rat adipose-derived MSC-soaked collagen sponges compared to collagen alone in the repair of anterior tracheal defects in rats and found that the inclusion of MSCs accelerated vascularization and the regeneration of a well-organized epithelium in 2 weeks . BatioglClinically, MSCs have been used as the main cell type for pre-implantation seeding in three published cases  to be included in tissue-engineered grafts is hampered by the lack of studies that have investigated critical variables such as the numbers of cells seeded or the methods used to propagate the cells ex vivo. As a result, the number of MSCs or chondrocytes required, the optimal techniques used to apply them to the scaffold to achieve seeding “success,” and the parameters by which “success” can be judged all remain unclear. When surveying the existing literature, the reported scaffold cell seeding density varies widely  and seeding strategies in this context. It is clear that future pre-clinical studies should undergo rigorous and systematic experimental design to maximize the generation of clinically useful data regarding the roles of seeded cells, particularly with respect to graft mechanical stability, cartilage maintenance, epithelialization, stenosis, and vascularization.ESM 1(DOCX 35.7 kb).ESM 2(DOCX 86.9 kb).


In vitro, oxidative stress causes increased release of inflammatory mediators (senescence-associated secretory phenotype and damage-associated molecular pattern markers) that can be packaged inside the exosomes. These exosomes traverse through tissues layers, reach maternal tissues to increase overall inflammatory load transitioning them from a quiescent to active state. Animal model studies have shown that fetal exosomes can travel from fetal to the maternal side. Thus, aging fetal membranes and membrane-derived exosomes cargo fetal signals to the uterus and cervix and may trigger parturition. This review highlights a novel hypothesis in human parturition research based on data from ongoing research using human fetal membrane model system.Human parturition is an inflammatory process that involves both fetal and maternal compartments. The precise immune cell interactions have not been well delineated in human uterine tissues during parturition, but insights into human labor initiation have been informed by studies in animal models. Unfortunately, the timing of parturition relative to fetal maturation varies among viviparous species—indicative of different phylogenetic clocks and alarms—but what is clear is that important common pathways must converge to control the birth process. Herein, we hypothesize a novel signaling mechanism initiated by human fetal membrane aging and senescence-associated inflammation. Programmed events of fetal membrane aging coincide with fetal growth and organ maturation. Mechanistically, senescence involves in telomere shortening and activation of p38 mitogen-activated signaling kinase resulting in aging-associated phenotypic transition. Senescent tissues release inflammatory signals that are propagated  To addrin utero is associated with the development of the fetus, with acceleration of this process projected to have long-term programming consequences in later life, potentially predisposing to adult-onset diseases. We posit that aging of the fetal membranes developmentally synchronize with the fetus to dictate the duration of pregnancy. As we have reported, progressive reductions in telomere length of fetal membrane cell chromosomes parallel those in fetal leukocytes  from amniochorionic cells to maternal tissues. Accelerated fetal membrane aging, manifested as telomere length reduction, is influenced by biochemical mediators of OS generated within fetal organs as they mature  , 29. ProWe also want to acknowledge that fetal membranes are not the only tissues that undergo aging. Multiple reports have suggested decidual aging and its association with term and preterm parturition –45. ThesSenescence-associated secretory proteins include cytokines, chemokines, angiogenic and other growth factors, matrix degrading enzymes as well as their endogenous inhibitors, cell adhesion molecules, proapoptotic receptors, and their ligands . Many ofAs mentioned above, SASP markers are well reported to be associated with human parturition. Several studies have reported a higher concentration of pro-inflammatory cytokines and chemokines at term labor compared to term not in labor –56. SimiIn vitro experiments have shown that HMGB1 released from senescent fetal cells in a feedforward loop cause increased expression of TLR2 and TLR4, cause p38MAPK-mediated senescence and inflammatory cytokine release in amnion epithelial cells. Both senescence activation and inflammatory cytokine release were inhibited by p38MAPK inhibitor SB 203580. This suggests the activation of pathway mediated by p38AMPK (2 repeats) as a stimulant, Polettini et al. showed amnion cells undergo p38MAPK-mediated senescence and inflammatory cytokine release  direct chemical diffusion to adjacent tissue layers or (2) encapsulated within exosomes, which can be transported to sites of functional activity in the myometrium, decidua, or cervix. One of the limiting steps in the former transport approach is that SASPs and DAMPs, including free HMGB1, are modified by acetylation or oxidization rendering very short half-lives in biologic fluids due to proteolytic degradation . By contTrafficking of exosomes, delivery of cargo at specific sites and their functional role have not been well reported during pregnancy. Recent findings by Chang et al. reported expression and trafficking of placental microRNAs at the feto-maternal interface. In a model of humanized mouse, authors report expression of 160-kb human 19 miRNA cluster (C19MC) locus or lentivirally express C19MC miRNA members selectively in the placenta of mouse . PregnanIn vitro experiments have shown that oxidatively stressed fetal membrane cells secrete exosomes richer in inflammatory mediators than cells grown under control conditions (in situ. In human amnion cells exposed to OS in vitro, exosomes were secreted into the conditioned media and could be passively transferred to human myometrial cell cultures, where they fused with the uterine cells and activated host cell COX-2, connexin-43, and cytokine mRNA expression. Salomon et al. have also shown the functional effect of exosomes under different oxygen tension (via exosomes.nditions . Exosomenditions , 81, 88.nditions . Exosome tension . These cin vivo and during storage (Because exosome contents are specific to the derivative cell, they constitute a real-time “fingerprint” of their cell of origin . Thus, e storage .in utero, at the time of fertilization. In utero programming involves both embryonic and extraembryonic tissue longevity, ultimately creating a homeostatic, stable environment preparing the fetus for independent extrauterine existence as a neonate. However, given their strategic layering between the fetus and the maternal decidua and myometrium, it appears that the fetal membranes tissues monitor the timing of gestation and promote expulsion of the intrauterine contents via an outburst of sterile inflammatory mediators. These mediators are propagated vectorially, from the fetal-to-maternal direction, promoting labor-associated changes in the myometrium. Concomitant with fetal maturation, tissues of the fetal membranes age and senesce, generating exosomes that carry molecules that are transformed into a uterotonic payload (In summary, our thesis provides a new concept of the mechanisms underlying human parturition. We emphasize that along with its embryonic development program, the process of organismal aging of any mammal, including the human, starts  payload , 6, 74. p38MAPK inhibitors could be used to prevent or even reverse cellular damage, providing a potential therapeutic strategy to mitigate fetal membrane aging and PTB .Exosomes expressing selective fetal membrane-specific antigens could be sampled from maternal blood as cell-specific, non-invasive “liquid biopsies” to longitudinally monitor amniochorionic membrane aging during pregnancy.Given the physical characteristics of exosomes, they are suitable to a variety of mechanical separation methods that currently confound standard “OMICs” approaches to the quantification of “free” biomarkers. Moreover, enhanced stability of exosomes in biologic fluids is likely to enhance biomarker sensitivity and assay performance.Custom exosomes could be used as therapeutic delivery vehicles that contain cargo that promotes uterine quiescence.If these concepts and our preliminary data are confirmed and supported by continuing investigation, several testable hypotheses are self-evident:In summary, we propose a novel concept of parturition in humans mediated by paracrine factors generated by natural and physiologic aging of fetal cells through senescence. The aging trajectory of fetal membranes and placenta are likely reflections of fetal growth and maturation. Aging, an inflammatory condition, generate inflammatory mediators, including DAMPs and well characterized uterotonins and propagate them to various feto-maternal tissues through exosomes. These communication channels reflect physiologic status of their cells of origin. Thus, exosome cargo contents reflect pregnancy status and, therefore, can function as potential biomarkers. Ongoing research has successfully isolated placental-derived exosomes from maternal plasma during normal and abnormal pregnancies . Future RM, SM, and RT conceived the idea and drafted the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer, GR, and handling editor declared their shared affiliation, and the handling editor states that the process nevertheless met the standards of a fair and objective review.