The course of Human Immunodeficiency Virus type 1 (HIV) infection is a dynamic interplay in which both host and viral genetic variation, among other factors, influence disease susceptibility and rate of progression. HIV set-point viral load (spVL), a key indicator of HIV disease progression, has an estimated 30% of variance attributable to common heritable effects and roughly 70% attributable to environmental factors and/or additional non-genetic factors. Genome-wide genotyping and sequencing studies have allowed for large-scale association testing studying host and viral genetic variants associated with infection and disease progression. Host genomics of HIV infection has been studied predominantly in Caucasian populations consistently identifying human leukocyte antigen (HLA) genes and C-C motif chemokine receptor 5 as key factors of HIV susceptibility and progression. However, these studies don’t fully assess all classes of genetic variation  and do not inform on non-European ancestry groups. Additionally, viral sequence variability has been demonstrated to influence disease progression independently of host genetic variation. Viral sequence variation can be attributed to the rapid evolution of the virus within the host due to the selective pressure of the host immune response. As the host immune system responds to the virus, e.g., through recognition of HIV antigens, the virus is able to mitigate this response by evolving HLA-specific escape mutations. Diversity of viral genotypes has also been correlated with moderate to strong effects on CD4+ T cell decline and some studies showing weak to no correlation with spVL. There is evidence to support these viral genetic factors being heritable between individuals and the evolution of these factors having important consequences in the genetic epidemiology of HIV infection on a population level. This review will discuss the host-pathogen interaction of HIV infection, explore the importance of host and viral genetics for a better understanding of pathogenesis and identify opportunities for additional genetic studies. Since the discovery of Human Immunodeficiency Virus type 1 (HIV) in the 1980s, a major goal of the infectious disease research community has been to study the pathogenesis of HIV disease to guide the development of therapeutics and, more recently, a functional cure. Since the start of the epidemic there have been an estimated 77.3 million (59.9–100 million) individuals infected with HIV and, in 2017, an estimated 36.9 million (31.1–43.9 million) individuals living with HIV globally . More thWhile the vast majority of the infected population requires cART to achieve suppressed viral load, it has become widely accepted that some individuals are able to maintain suppression without the use of cART . SpVL can change quite drastically between individuals but has been shown to be relatively constant within a person with a higher viral load being strongly associated with a faster disease progression . Rate ofHigh spVL is a public health concern due to increased transmission risk in all risk groups including intravenous drug users, men who have sex with men (MSM), and heterosexual transmission . AlthougThe ability of an individual to suppress their viral load, in the absence or with the assistance of cART, can significantly decrease HIV disease progression and greatly improve quality of life. This phenomenon has warranted a large amount of time to research the variability of HIV disease progression and has resulted in a wealth of knowledge regarding the complex interaction of HIV and host proteins. There are many factors which impact HIV disease progression such as viral and host genetic diversity, host–pathogen interaction and environmental factors. Although the root causes of variability in spVL and rates of progression are not fully understood, one area that has received significant attention, and produced significant discoveries, is the role of viral and host genetic variability, and the dynamics of host–pathogen interaction.Genome-wide genotyping and sequencing studies have marked a shift in the direction of human genetic research from the use of candidate gene studies to genome-wide approaches allowing for the identification of large number of genetic variants associated with control of HIV infection. Genome-wide association studies (GWAS) provide an unbiased scan of the genome for common single nucleotide polymorphisms (SNPs) and small insertions and deletions (indels) associated with a particular trait . While these types of studies do not provide any causal information, they direct researchers to a region of interest which requires further studies to determine causality. However, GWAS require strict statistical standards and require large sample sizes which can make study designs difficult .The global HIV pandemic originated from the independent zoonotic transmission events between non-human primates and humans which resulted in four different groups of HIV M, N, O, and P . HIV groSince HIV has such a high mutation rate, viral sequencing is an essential process for determining potential drug resistance at the beginning of treatment. Early detection of drug resistance is necessary to help guide treatments options which are most suitable for a particular patient. This process is traditionally performed by sequencing plasma HIV RNA and looking for known variants in the RT, protease (PR), and integrase (IN) genes that are associated with resistance. Recently, the field of HIV sequencing has started a shift from traditional Sanger sequencing methods toward next generation sequencing (NGS) for the detection of low frequency viral variants. While NGS is able to detect more variants than traditional RNA or DNA Sanger sequencing, the clinical relevance of low frequency viral variants still requires more investigation before use in a clinical setting . ParticuViral sequence diversity has been shown to affect disease progression independently of host factors . CurrentInvestigations of within subtype diversity have also identified some differences in rates of progression. In a study looking at 8483 United Kingdom patients prior to antiretroviral therapy, genetic diversity in the polymerase gene explained roughly 5.7% of the variance of spVL in subtype B infected individuals . More reWhile viral sequence variation can have a direct impact on disease progression causing increased or decreased viral load, this may be reflecting host genetic pressure on spVL as variation of viral sequences can be attributed to escape mutations. In a joint host/viral genetic analysis, 23.6% of the variability in HIV spVL mapped to known epitope regions, suggesting that this variability is the result of pathogen evolution away from host HLA . Further∗57:01 is known to strongly decrease the rate of disease progression, however, across multiple continents; it has been shown that HIV is developing an escape mutation, I135X, which attenuates control  gene, the only genotype which has consistently associated with protection against acquisition of HIV infection  patients in 1996, it was discovered that a 32-bp deletion in the gene CCR5 was able to greatly reduce or prevent infection in HIV-exposed individuals homozygous for the deletion allele . The CCRSince the discovery CCR5Δ32, substantial research has been done to identify other genetic variants associated with reduction of HIV susceptibility. Many of these studies have focused on highly HIV exposed seronegative individuals and high-risk populations for identification of susceptibility factors. One large study attempting to determine genetic variants associated with acquisition of HIV examined 848 HIV-negative cases and 531 HIV-positive controls and tested approximately 800,000 SNPs . HoweverP < 5 × 10-8) and six other regions which had suggestive significance (P < 1 × 10-6). However, these results require further investigation as a 2013 study of 6334 patients and 7247 controls of European ancestry was unable to detect any SNPs, outside the major histocompatibility complex (MHC) region of chromosome 6, that met genome-wide significance  cohort of individuals of African (628 cases and 1376 controls) and European (327 cases and 805 controls) ancestry used a large population size in a high risk population to identify susceptibility variants . They reificance . Thus, tHLA variants have been implicated in control of HIV infection in diverse populations  and 2648 progressors (controls), determined that in European samples  and African American samples there were no variants that met genome-wide significance outside of the MHC region of chromosome 6 . This stHLA variants  and Toll-like receptors (TLR) polymorphisms (TLR2 rs3804100 and TLR7 rs179012) explained 13% and 5% of the variance in viral load, respectively. Other factors, such as plasma HIV levels of the transmitting partner and HLA-concordance between partners were able to explain 10% and 6% of the variance, respectively. Additionally, incorporation of genital factors of the transmitting partner was able to explain 46% of the variation of spVL in this population  of the transmitter on spVL . HLA varpulation .HLA alleles and CCR5Δ32 as the only two regions associated with viral load, with no other variants surpassing statistical significance. However, there was a small but measurable contribution (∼5%) from combined common additive effects outside the MHC and CCR5 regions  where it was the only region that met genome-wide significance . In thisTaken together, these studies show that host genetics can explain roughly 30% of variance in viral load, however, a majority of the remaining variance is still unknown but is thought to be environmental factors and/or unidentified host factors. Therefore, to better understand variation in HIV disease progression related to spVL, more research is needed in larger samples using novel analytical methods that provide more power for detecting smaller genetic effects and additional ancestry groups for identifying non-European variants.In order to understand the pathogenesis of HIV infection, it is important to explore how viral and host proteins interact. HIV only encodes nine genes and requires the use of host proteins to establish and maintain infection, termed HIV host dependency factors (HDFs) . GeneralRNA-interference (RNAi) based studies are popular for identifying large numbers of HDFs required for establishing and maintaining infectious diseases and three initial studies proposed over 800 HDFs required during HIV infection . The firShortly after, ∗), SEC13, COG, and THOC2 as key HDFs and characterized the roles of these genes in vitro. Notably, GOLGI49 was identified as a Golgi protein and during knock-down shown to decrease replication of both HIV IIIB (X4-tropic) and BaL (R5-tropic) viruses  analysis can reduce false positives and off target effects, further techniques and standardizations are required. There is currently no standard cell line for HDF work with groups which may explain the variable results observed in these studies. HeLa-derived cell lines and MAGI cells require the addition of CCR5 to become susceptible to R5-tropic HIV infection which strains their physiological relevance. Therefore, without consistent use of cell-types, the physiological landscape of protein expression may cause increased variation and further deviation from the expected in primary cell lines.Recently, genome-wide CRISPR knockouts screens have become more popular for generation of loss-of-function variants as they have increased knock-out reliability and decreased off target effects compared to siRNA methods . This teTPST2, SLC35B2, and ALCAM during HIV pathogenesis were identified, not seen by the previous RNAi-based screens It has been clearly demonstrated that both host and viral genetics play a vital role in determining HIV acquisition and disease progression. Current evidence supports the role that viral subtype has an effect on disease progression, however, there is also evidence against this claim. Overall, viral diversity has been demonstrated to have an impact of disease progression and therefore, it is important to study disease progression in the context of both host and viral genetics.As GWAS have become a useful tool for discovering novel variants associated with a particular trait, it is important to recognize that their use is limited by the diversity of the target population. In 2016, it was reported that “genomics is failing on diversity” with the vast majority (81% over 2511 studies) of GWAS, in all disciplines, being performed in individuals of European ancestry in 2016 . These tin vivo remains an area of active research. Cross-referencing the genes from RNAi and CRISPR genome-wide studies with large databases such as gnomAD for identification of genes which have homozygous loss-of-function in individuals of various populations could provide interesting avenues for new therapeutics. This is akin to reading the natural experiment where healthy individuals with a homozygous loss-of-function gene purported to be necessary for HIV replication could act as valuable resources to determine the gene’s action in vivo.Genome-wide knockout studies have great potential for studying the effects of HDFs for a variety of infectious diseases; however, translation of their physiological relevance in primary cells or As the field of genomics continues to evolve, there is opportunity to leverage the growing wealth of information available to better understand disease acquisition and progression.RT and PM conceived and wrote 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.


Therefore, the design of antifouling (bio)sensing interfaces capable to minimize these undesired processes is a substantial outstanding challenge in electrochemical biosensing. For this purpose, efficient antifouling strategies involving the use of carbon materials, metallic nanoparticles, catalytic redox couples, nanoporous electrodes, electrochemical activation, and (bio)materials have been proposed so far. In this article, biomaterial-based strategies involving polymers, hydrogels, peptides, and thiolated self-assembled monolayers are reviewed and critically discussed. The reported strategies have been shown to be successful to overcome (bio)fouling in a diverse range of relevant practical applications. We highlight recent examples for the reliable sensing of particularly fouling analytes and direct/continuous operation in complex biofluids or harsh environments. Opportunities, unmet challenges, and future prospects in this field are also pointed out. Despite the huge progress demonstrated by electrochemical biosensors for individual and/or multiplexed determination of a wide variety of relevant analytes including biomarkers at different molecular levels, the determination of certain compounds such as phenols and neurotransmitters ,2, the dTherefore, the development of (bio)sensing interfaces that combine high sensitivity and antifouling ability by preventing byproducts, macromolecules and polymeric substrates from absorbing onto the electrode surface is essential for expanding the practical applicability of biosensors to allow reliable measurements ,5.It is worth noting that the exceedingly broad types of fouling agents and the ways in which they foul electrodes make equally broad the strategies developed to impart fouling resistance to the electrochemical sensors . HoweverThe following sections review the most relevant aspects of the main strategies involving biomaterials reported so far to develop electrochemical biosensors with excellent antifouling properties, capable to be employed in the analysis of undiluted or scarcely diluted complex samples and/or to provide excellent performance after prolonged incubation in raw biological fluids and in extreme pH media. Other nonfouling strategies involving the use of carbon materials, metallic nanoparticles, catalytic redox couples, nanoporous electrodes and electrochemical activation have been reviewed previously  and are Nonspecific protein adsorption can be minimized by modifying electrode surfaces with hydrophilic, conducting, zwitterionic, and pH-responsive methacrylate polymers. While hydrophilic polymers avoid biofouling by forming a hydration layer, hydrophobic surfaces prevent it by releasing the adsorbed proteins and cells ,8.The most commonly employed polymer to date for this purpose is poly (ethylene glycol) (PEG)-containing polymers and reagents, because of their commercial availability . RecentlAs for the polymer composition employed and since many conjugation chemistries required for chemical immobilization of biomolecules affect negatively the stability and/or function of the polymer ,16, thinPEG is a nontoxic and highly hydrophilic biocompatible polymer. It is considered the “gold standard” of antibiofouling polymers and has been widely used to reduce nonspecific protein adsorption . SurfaceThe protein resistance of long-chain PEG modified interfaces is attributed to both hydration and steric hindrance effects ,8. Each BRCA1) in human serum. The biosensor involved immobilization of specific capture DNA probe onto a glassy carbon electrode (GCE) modified with the (PANI/PEG) nanofibers, a direct hybridization assay, and differential pulse voltammetric (DPV) monitoring of the decrease in the methylene blue (MB) signal after the hybridization with the target DNA  with excellent antifouling properties in complex matrices (100% bovine serum). Sun et al. have reported very recently a method to fabricate antifouling microarrays for protein sensing through photopolymerization of biomimetic betaine compounds . The mic® L100 3−/4−, a linear correlation with the logarithmic value of AFP concentration was observed between 10.0 fg mL−1 and 100.0 pg mL−1 with a LOD value of 3.1 fg mL−1. Importantly, the biosensor showed satisfying antifouling ability after 30 min incubation in 1−2% serum and was successfully applied to the analysis of 1/10,000 (v/v) diluted human serum samples. The same group has recently proposed an antifouling aptasensing interface for immunoglobulin E (IgE) through mixed self-assembly of thiolated zwitterionic peptide/specific aptamer onto a macroporous Au substrate electrochemically fabricated with the aid of multilayer polystyrene nanospheres self-assembled on a GCE . A. Ap-MBA re probe . These DTernary SAMs have been used for the preparation of nucleic acid-based biosensors ,66,67,68Exhaustive optimization studies performed with ternary monolayers demonstrated that the fabrication protocol, nature, and concentration of the functional groups; chain length of the third component ,53; and Dharuman et al. ,70,71 weWang´s research group proposed in a pioneering way the use of ternary DNA SAM-interfaces prepared by co-immobilization of a short cyclic  or lineaThese ternary monolayers, assembled onto 16-Au electrode arrays prepared by photolithography ,66,67,68Bradley´s research group proposed the use of ternary SAMs composed of a redox-tagged peptide, MCH, and a linear dithiol, PEG  or PDT ,73 to coESR1). PEGylated ESR1 DNA capture probes were co-immobilized in the presence of either a PEG alkanethiol (thiolated hexadacanetriethyelene glycol), a mixture of PEG alkanethiol and MCH or a bipodal aromatic PEG alkanethiol (dithiolated aromatic triethylene glycol) onto an electrode array chip consisting of 16 square-shaped gold electrodes arrayed in a 4×4 configuration with a geometrical area per electrode of 1 mm2. The strategy, consisting of co-assembled thiolated ESR1 capture probes and bipodal aromatic PEG alkanethiol at a ratio of 1:100, provided better performance in terms of sensitivity and minimal nonspecific binding. The method was applied to the analysis of the product resulting from the polymerase chain reaction (PCR) amplification of the genetic material extracted from breast cancer cells (MCF-7) and detected 0.17 nM of the synthetic amplicon. Henry et al.  comparedPyramidal tetrahedral DNA nanostructures are reproducible self-assembled onto gold surfaces by using four carefully designed ss-DNA probes (three of them thiolated) which constitute the six edges of a DNA tetrahedron and leave pendant a linear sequence at the top of the bound tetrahedron c 76,77],7776,77]Goda et al.  reportedMcQuistan et al.  proposed−1 vs 10 µg mL−1) which falls in the serum clinically relevant range (1–10 ng mL−1) and also prevented nonspecific binding of the human serum albumin used as control protein, compared to the high nonspecific binding observed at the MCH-based sensors. Jolly et al.  proposedIt is unquestionable that despite the tremendous possibilities and capabilities provided by electrochemical biosensors for the determination of relevant analytes in different fields, the requirements involved in the determination of fouling analytes, such as phenols and neurotransmitters, of target analytes directly in samples rich in proteins, with extreme pH values (denaturing the biorecognition elements), or after prolonged incubation periods of the biosensors in this type of matrices are important challenges yet to be faced up.With this purpose, efficient electrode modification strategies with a wide range of antifouling (bio)materials  have been critically discussed in this review. These strategies have addressed severe electrode (bio)fouling processes and have allowed the preparation of biosensors able to perform the electrochemical determination of fouling analytes or in fouling samples with excellent performance. Although a comparison with the use of nonbiological antifouling nanomaterials is out of the scope of this review, as far as we know, their properties have not been thoroughly compared under identical conditions. In principle, the use of biomaterials should be advantageous mainly in terms of reproducibility, simplicity, biocompatibility and versatility. Additionally, as antifouling (bio)materials have been used in specific areas, it is difficult to make a general choice among them as more adequate for real applications and even to carry out an exhaustive comparison of their performance. Nevertheless, the recently reported use of commercial methacrylate polymeric coatings appears as a particularly interesting antifouling strategy in terms of biocompatibility, simplicity, preparation time, and versatility to be further explored to allow continuous electrochemical sensing and biosensing in real-world applications regardless composition and pH of the sample.However, given the diversity of electrode fouling analytes, the coexistence of different fouling agents in the same sample and the wide variety of fouling samples where relevant analytes should be analyzed, more research on antifouling strategies is required to minimize the significant impact of electrode fouling and ensure their appropriate functioning in harsh environments. In addition, currently reported antifouling approaches should be evaluated against a wider variety of fouling agents and matrices, particularly biological samples and matrices that are a complex mixture of proteins, peptides, lipids, and carbohydrates. Nevertheless, new strategies should be developed to overcome constraints or improve the performance of the existing ones. Moreover, it is worth to mention that in many cases the fouling resistance of a given strategy is evaluated only towards one analyte or a particular matrix sample which limits a general assessment of how the antifouling strategy may work in other environments or over other electrochemical substrates. This lack of information makes not straightforward to extrapolate the particular results to select a priori a strategy able to meet the demands for a particular application. In this context, the use of computational approaches, such as the Quantitative Structure–Property Relationship (QSPR), may help tremendously the prediction of the behavior of (bio)materials under different environments as well as the design of in silico strategies able to meet the required antifouling demands, thus saving a lot of experimental work. Therefore, future efforts must be aimed at evaluating antifouling strategies against different concentrations of the same fouling agent  and with a wide variety of fouling agents and matrices  to develop strategies with broad applicability. Most antifouling strategies involve modification of the electrode surface with a coating or film to impart fouling resistance. The modifier choice depends on the analyte, conditions of the system, and the type of electrode. However, the pathways involved in electrode fouling and the mechanisms by which antifouling strategies can minimize or eliminate fouling are generally poorly understood. Therefore, research should be driven also to advance in that knowledge aiming to develop efficient and versatile antifouling strategies able to address unmet challenges and extend the range of applications. The active pursuit of new strategies to improve the already remarkable antifouling properties imparted by current strategies is encouraging and envisions better materials to be used in a near future. New materials with unique or improved properties will lead to develop highly stable electrochemical biosensing systems for continuous on-body determination or in vivo monitoring of important analytes directly in a variety of body fluids of different pH range and composition.It is important to note that these antifouling (bio)material-based electrochemical sensors have been reported so far as prototypes and tested only under laboratory conditions. Therefore, their commercialization is still far away. The development of versatile strategies by a better understanding of the antifouling mechanisms will allow their application under different conditions. The optimization of storage stability and transportation conditions of the antifouling (bio)material-based electrochemical sensors are also important challenges to face up for constructing marketable devices with reliable and proper functioning in different environments.


Glucocorticoids regulate fundamental processes of the human body and control cellular functions such as cell metabolism, growth, differentiation, and apoptosis. Moreover, endogenous glucocorticoids link the endocrine and immune system and ensure the correct function of inflammatory events during tissue repair, regeneration, and pathogen elimination via genomic and rapid non-genomic pathways. Due to their strong immunosuppressive, anti-inflammatory and anti-allergic effects on immune cells, tissues and organs, glucocorticoids significantly improve the quality of life of many patients suffering from diseases caused by a dysregulated immune system. Despite the multitude and seriousness of glucocorticoid-related adverse events including diabetes mellitus, osteoporosis and infections, these agents remain indispensable, representing the most powerful, and cost-effective drugs in the treatment of a wide range of rheumatic diseases. These include rheumatoid arthritis, vasculitis, and connective tissue diseases, as well as many other pathological conditions of the immune system. Depending on the therapeutically affected cell type, glucocorticoid actions strongly vary among different diseases. While immune responses always represent complex reactions involving different cells and cellular processes, specific immune cell populations with key responsibilities driving the pathological mechanisms can be identified for certain autoimmune diseases. In this review, we will focus on the mechanisms of action of glucocorticoids on various leukocyte populations, exemplarily portraying different autoimmune diseases as heterogeneous targets of glucocorticoid actions: (i) Abnormalities in the innate immune response play a crucial role in the initiation and perpetuation of giant cell arteritis (GCA). (ii) Specific types of CD4+ T helper (Th) lymphocytes, namely Th1 and Th17 cells, represent important players in the establishment and course of rheumatoid arthritis (RA), whereas (iii) B cells have emerged as central players in systemic lupus erythematosus (SLE). (iv) Allergic reactions are mainly triggered by several different cytokines released by activated Th2 lymphocytes. Using these examples, we aim to illustrate the versatile modulating effects of glucocorticoids on the immune system. In contrast, in the treatment of lymphoproliferative disorders the pro-apoptotic action of glucocorticoids prevails, but their mechanisms differ depending on the type of cancer. Therefore, we will also give a brief insight into the current knowledge of the mode of glucocorticoid action in oncological treatment focusing on leukemia. Hormones enable intercellular communication as well as the exchange of information between different organ systems throughout the human body. They are involved in a variety of processes such as growth, development, and metabolism. The synthesis and secretion of hormones is subject to stringent regulations, comprising positive, and negative feedback loops as crucial mechanisms. Steroids are lipophilic hormones that are subdivided into mineralocorticoids produced in the zona glomerulosa of the adrenal cortex, glucocorticoids produced in the zona fasciculata as well as sex hormones produced in the zona reticularis and to a great extent in the gonads. Since it has been demonstrated that natural glucocorticoids also have some mineralocorticoid effects, the classification into these groups is not completely accurate. The term “glucocorticoids” is more suitable when talking about synthetic glucocorticoids , because these drugs are more restricted to glucocorticoid effects only .The initial step of steroid hormone biosynthesis is the conversion of cholesterol to the precursor pregnenolone in the mitochondria. Steroid hormone biosynthesis is mainly realized by enzymes of the cytochrome P450 family . Sex horBetween 5 and 30 mg of the active endogenous  glucocorticoid cortisol is produced per day, regulated by the hypothalamic–pituitary–adrenal (HPA) axis. Glucocorticoids bind to glucocorticoid receptors that are present in cells throughout the body, including cells in the hypothalamus and pituitary gland, which are part of the negative feedback loop controlling the glucocorticoid production. Furthermore, the hormone concentration varies in a circadian manner peaking at 9 a.m. in the morning and reaching the lowest plasma concentration at midnight.The dehydrogenation of cortisol to its inactive form cortisone is promoted by the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) type 1 in the liver. The same enzyme also exhibits reductase activity promoting the reverse reaction. The type 2 11β-HSD is only able to convert the active into the inactive form due to its sole dehydrogenase activity. Depending on the balance and activity of both enzymes, the intracellular glucocorticoid concentration and thus the tissue sensitivity for glucocorticoids varies . In addiGlucocorticoids are lipophilic substances with a low molecular weight that can easily pass cellular membranes and bind to the glucocorticoid receptor in the cytosol. The cytosolic glucocorticoid receptor is ubiquitously expressed by nucleated cells and resides in the cytoplasm as a multi-protein complex. Proteins and co-factors stabilize the receptor and support a specific conformation leading to a high binding affinity for its ligands –9. Two mThe hormone-receptor complex is translocated into the nucleus as a homodimer and binds to palindromic DNA-binding sites in the promoter region of different target genes, so called glucocorticoid response elements. This genomic mechanism of glucocorticoid action is known as transactivation, which describes the binding to positive glucocorticoid response elements leading to the activation of the transcription of anti-inflammatory but also regulatory proteins. These include for example IL-10, Annexin 1, and IκB as well as enzymes of gluconeogenesis such as tyrosine aminotransferase, serine dehydrogenase, or phosphoenol pyruvate carboxykinase. In contrast, the term transrepression refers to an impairment of the expression of immunoregulatory and proinflammatory proteins caused by (i) competition for nuclear co-activators between the hormone-receptor-complex and transcription factors; (ii) direct or indirect interaction with transcription factors like NF-κB and AP-1. Similarly, glucocorticoids diminish gene expression by a mechanism referred to as cis-repression, which involves binding to negative glucocorticoid response elements. Genomic mechanisms of glucocorticoid action result in “delayed effects,” meaning that the protein level does not change directly after glucocorticoid administration. The duration of the delay depends on different factors, including transport within the bloodstream, onset of activation/translocation of the hormone-receptor complex and the transcriptional and translational processes themselves. Nevertheless, the description of rapid improvements which are observed within a few minutes—especially after intravenous or intraarticular injection of high glucocorticoid doses—demonstrates the existence of non-genomic effects. These are triggered by (i) proteins released from the multi-protein complex after the binding of glucocorticoids to the cytosolic receptor, (ii) interactions with membrane-bound receptors, and (iii) nonspecific effects resulting from the interaction of glucocorticoids with cellular membranes , 16.More pronounced glucocorticoid effects are observed with increasing glucocorticoid dosages, as receptor saturation is achieved . UnfortuThese findings clearly show that our knowledge concerning the mechanisms of glucocorticoid action—including the desirable anti-inflammatory and the undesirable adverse effects—is yet insufficient. Nevertheless, these drugs still represent an indispensable component of the treatment of most inflammatory diseases because of their efficient and cost-effective characteristics. However, the considerable toll taken by adverse events must not be neglected and the development of an equally effective alternative with a more favorable side-effect profile would be most desirable. The extent and importance of glucocorticoid toxicity has been reviewed elsewhere , 28 and The immune system consists of two major components: The innate immune response represents our first line of defense and includes physical and chemical barriers such as the skin and tears. In addition, non-specialized cells recognize foreign invaders by components like bacterial lipopolysaccharide and destroy them by phagocytosis or release of toxic substances. The adaptive immune response—our second line of defense—includes B and T lymphocytes. While the former are responsible for antibody production, the latter can differentiate into distinct subpopulations that participate in B cell maturation or possess cytotoxic potential –31. The Since the establishment and the course of autoimmune diseases are driven by different cell populations, glucocorticoid application targets diverse leukocyte populations and thus the mechanism of glucocorticoid action varies. Recently, Franco et al. have investigated the transcriptional effects of glucocorticoids on nine primary human cell types. They found 9,457 genes to be differentially expressed in response to glucocorticoids, whereas only 25 of them (0.3%) involved all cell types examined, demonstrating that the transcriptional response of each cell type is quite distinct .The next chapters will illustrate the versatile modulating effects of glucocorticoids on the immune system on the basis of exemplary diseases involving the respective leukocyte population. Glucocorticoid regimens used in daily practice according to current guidelines are presented in Giant cell arteritis (GCA) is defined as a granulomatous large-vessel vasculitis, which primarily involves medium- and large-caliber branches of the aorta , 58, 59.Glucocorticoids represent a most effective therapy and, therefore, remain—despite the recently shown favorable effects of the IL-6 receptor inhibitor Tocilizumab —the primin vitro . In. Inin viDeng et al., however, have shown that glucocorticoids suppress the production of Th17-promoting cytokines  , but IFNAt higher glucocorticoid dosages, for instance in form of pulse therapy in complicated GCA and in case of established visual loss, rapid non-genomic effects as already described in the introduction contribute to their therapeutic efficacy [reviewed in ].Rheumatoid arthritis (RA) is a systemic autoimmune disease that affects up to 1% of the population worldwide with a higher prevalence in women than in men. RA patients suffer from pain, immobility, and fatigue leading to decreased quality of life . The patGlucocorticoids play a very important role in the treatment of RA, rapidly suppressing inflammatory activity especially at disease onset and during flares , 80–82. When the Th1/Th2 paradigm dominated the understanding of the pathogenesis of autoimmune diseases, RA was defined as a Th1-driven disease because CD4+ T cells identified to be enriched in synovial fluids from RA patients were prone to secrete IFN-γ but not IL-4 , 94. Theper se shed new light on the contribution of inflammatory Th subsets to the initiation of RA . Clinical manifestations of this autoimmune disease are diverse, affecting a wide spectrum of organs and tissues. The pathogenesis of the disease is not yet fully understood, but beside environmental factors a genetic susceptibility to SLE has been described including a variety of nucleotide polymorphisms [reviewed elsewhere ]. PlasmaAlterations in B cell maturation and differentiation affect several B cell subsets, targeting different checkpoints of B cell development. In SLE patients the frequency of antibody producing plasma cells in the peripheral blood is increased and correlates with autoantibody production and disease activity . It has Although B cells have emerged as central players in SLE, B cell depletion failed repeatedly as a therapeutic strategy in clinical trials. For example, the EXPLORER study demonstrated that rituximab, a CD20 antibody, did not show any statistically significant efficacy in achieving treatment response compared to placebo. Moreover, a recent reanalysis confirmed these findings, reevaluating the data with the help of newly available disease activity scores , 138.There is only one therapeutic antibody approved by the FDA and the EMA for SLE therapy, namely belimumab, which neutralizes BAFF/BLyS and thereby decreases the number of newly formed B cells , 140.The management of SLE strongly depends on the course of the disease. Glucocorticoids represent highly effective agents in order to immediately control the inflammatory process in SLE. Systemic glucocorticoids are required as initiation therapy in severe SLE, whereas maintenance immunosuppressive therapy is added in order to enable steroid tapering. Nevertheless, especially in acute, organ-threatening disease high-dose intravenous pulse therapy  is often used to reduce disease activity . InteresHowever, the mechanism of glucocorticoid action in SLE patients is largely unknown. A study in MRL/MpSlac-lpr mice with systemic autoimmune symptoms similar to human SLE analyzed prednisone action on plasma cell differentiation with regard to the impact of regulatory factors, including IL-21, Blimp-1, and Bcl-6 . The percentages of plasma cells and plasma cell precursors as well as activated T cells were decreased after 13 weeks of prednisone treatment . In addiPRDM1, which encodes BLIMP-1 involved in terminal differentiation and reduced proliferation of B cells and IL10, (ii) functionally impaired BCR signaling by suppressing CR2 and CD19 which encode the two components of the B cell co-receptor complex that serve as an enhancer of BCR-mediated signaling and (iii) selectively impaired TLR signaling by downregulation of TLR1, TLR6, and TLR7 CD38(lo)IgD(-)], plasmablasts [CD19(hi)CD38(hi)IgD(-)], and plasma cells [CD19(lo/-)CD38(hi)IgD(-)]. They added low and high concentrations of prednisolone at the beginning of each differentiation step and found a significant inhibition of B cell proliferation and differentiation in the last step, whereas IgG production was decreased in step 2 and 3 only at high glucocorticoid concentrations (100 ng/ml) . Interesand TLR7 .However, responses to glucocorticoids differ from patient to patient suffering from SLE. This may, at least in part, be related to the glucocorticoid receptor α whose alteration has been demonstrated in several autoimmune diseases –150. In in vitro study in human B cells. In general, GILZ mRNA and protein expression in peripheral blood mononuclear cells obtained from patients with SLE were downregulated compared to controls and correlated negatively with different markers of disease activity. An analysis of human B cell subsets revealed that intracellular GILZ was significantly decreased in circulating HLA-DRlo plasmablasts  in pati disease .In the past decade, several additional factors including p-glycoprotein and the macrophage migration inhibitory factor (MIF) have been identified in the context of glucocorticoid resistance in SLE [reviewed in ]. P-glycAlthough glucocorticoids are highly effective in the treatment of SLE, these drugs bear the risk of severe adverse effects, especially when given over a longer period of time and/or at higher dosages. A study analyzing the relationship between glucocorticoids and damage accrual in SLE demonstrated that medium to high mean daily prednisone doses and higher cumulative doses were associated with an increased occurrence of adverse effects. Eighteen patients developed new damage attributable to glucocorticoid treatment including cataracts, osteoporotic fractures, avascular necrosis, and diabetes mellitus . New druContrary to Th1 cells CD4+ T helper cells type 2 (Th2) are mainly involved in eosinophil activity as well as IgE production caused by an immunoglobulin class-switch in B cells . Th2 celPhysiologically, Th2 cells exert their main function in the control of helminth infections. This mechanism of defense, referred to as the “type 2 response,” involves players of both the innate and adaptive immune system. Besides the activation and proliferation of Th2 cells and the secretion of their characteristic cytokines, this cascade comprises eosinophil and basophil granulocytes, mast cells as well as IgE secreted by plasma cells . ConsideWith a lifetime prevalence of about 40%, allergic diseases represent the most common immune disorder in western countries, affecting both children and adults . The GerGlucocorticoids, administered both topically and systemically, represent indispensable agents in the treatment of atopic disorders . GeneralFirstly, one has to distinguish between short-term and long-term drug effects. Temporary application of supraphysiological glucocorticoid doses results in an inhibition of Th2 cytokine production , 3 202––202–205.Secondly, the effect of glucocorticoid administration on Th2 cells in atopic patients appears to differ from the Th2 enhancement generally caused by these drugs. Hydrocortisone significantly reduced the presence of IgE, histamine, and type 2 cytokines in serum and skin samples from AD patients . CorrespFinally, the beneficial glucocorticoid actions in allergic diseases are not only caused by their impact on Th2 lymphocytes. On the contrary, several players of the type 2 immune response are equally affected by glucocorticoid treatment. Namely, mast cell maturation and activation, FcεRI expression as well as mediator production and release are inhibited by glucocorticoid exposure –227. FurThe last chapter will give a brief insight into the mechanisms of glucocorticoid action in cancer therapies. Interestingly, the effects of glucocorticoids on different cancer subtypes and thereby the underlying mechanisms vary, even regarding opposite effects. This may be related to the subtype of cancer itself including its location, the affected cell type, the microenvironment and emerging comorbidities. Also, the glucocorticoid dose ranging from low to high daily dosages, and the level of glucocorticoid receptor expression and activity play an important role. In addition to that, the co-existence of other receptors of the steroid receptor family, namely the androgen and the estrogen receptors, can affect glucocorticoid action, especially in breast or prostate cancer, since there are also differences in receptor positive and receptor negative cancer subtypes. Another beneficial effect on different subtypes of cancer should not be neglected: Glucocorticoids are used as co-therapy during chemotherapy or radiotherapy in order to reduce side effects. They have been shown to improve mood, increase appetite and thereby lessen weight loss, reduce fatigue, diminish ureteric obstruction, prevent vomiting, and alleviate pain –250.www.gekid.de; www.statistik.at).In the following, we will concentrate on hematopoietic malignancies which form a particular subset of cancerous conditions that were first discovered as such in the Nineteenth century when Rudolf Virchow coined the term “leukemia,” meaning “white blood.” Glucocorticoids play a crucial role in the treatment of these malignancies, among others as part of the CHOP regimen to treat non-Hodgkin lymphoma as well as in myeloma therapy. Nevertheless, due to the considerable differences of glucocorticoid effects on diverse cancer types, we will focus on one subtype here, namely leukemia. The epidemiology of the disease is summarized in Four different types of leukemia are described: chronic lymphoblastic leukemia (CLL), chronic myeloid leukemia (CML), acute myeloid leukemia (AML), and acute lymphoblastic leukemia (ALL). CLL is the most common leukemic disease in western industrialized countries, where the disease constitutes 95% of the overall cases in older individuals (50 years and older) . The maiThe inhibition of B cell apoptosis and the dysregulation of proliferation and differentiation are the main causes of CLL. They lead to an accumulation of mature CD5-positive, CD10-negative, CD20 weakly positive, and CD23-positive B cells within blood, bone marrow and solid lymphoid organs –254. Thein vitro effects of the combination of ibrutinib and dexamethasone on the proliferation and metabolic stress markers in lymphocytes obtained from patients suffering from CLL. They demonstrated an enhanced inhibition of cell cycle progression, an increase in apoptosis and a decrease in DNA damage in lymphoid B cells by a combination of dexamethasone and ibrutinib compared to the tyrosine kinase inhibitor alone  , resulting in transcripts and fusion proteins with unusual tyrosine kinase activity  represents the standard induction therapy in ALL . The speThe glucocorticoid-induced cell death in leukemia is mediated by the glucocorticoid receptor via transrepression and transactivation (please see Introduction). It has been demonstrated that the repression of anti-apoptotic BCL2 and the activation of the antagonizing pro-apoptotic BIM induce cell death in ALL , 270. OtFinally, the underlying mechanisms which mediate glucocorticoid-induced cell death in leukemia are diverse and not yet well-understood. The existence and the development of glucocorticoid resistance after long-term therapy aggravate treatment strategies or reverse the achieved remission. This applies to both the treatment of cancer and the treatment of inflammatory autoimmune diseases.After highlighting the effects of glucocorticoids in different immune cells in the context of a variety of immunopathologies, we have to conclude that the understanding of the mode of glucocorticoid action in the scope of immune responses and glucocorticoid resistance is still incomplete. Although glucocorticoids have ranked among the most potent immunosuppressive drugs in daily clinical care for more than 70 years, knowledge on their mechanisms of action on cellular and sub-cellular levels in an immune cell type-specific manner and in the context of the respective immunopathology remains scarce. Further research into this topic will enhance our comprehension of the capacity spectrum of glucocorticoid action and the establishment of glucocorticoid resistance, also providing guidance for personalized therapy.TG, LE, and CS designed the concept. CS and LE prepared the figures. All authors wrote the manuscript and read and approved the final version of the manuscript.FB reports receiving consultancy fees, honoraria and/or travel expenses, and grant/study support from Horizon Pharma and Mundipharma. The remaining 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.


Epilepsy is characterized by the regular occurrence of seizures, which follow a stereotypical sequence of alterations in the electroencephalogram. Seizures are typically a self limiting phenomenon, concluding finally in the cessation of hypersynchronous activity and followed by a state of decreased neuronal excitability which might underlie the cognitive and psychological symptoms the patients experience in the wake of seizures. Many efforts have been devoted to understand how seizures spontaneously stop in hope to exploit this knowledge in anticonvulsant or neuroprotective therapies. Besides the alterations in ion-channels, transmitters and neuromodulators, the successive build up of disturbances in energy metabolism have been suggested as a mechanism for seizure termination. Energy metabolism and substrate supply of the brain are tightly regulated by different mechanisms called neurometabolic and neurovascular coupling. Here we summarize the current knowledge whether these mechanisms are sufficient to cover the energy demand of hypersynchronous activity and whether a mismatch between energy need and supply could contribute to seizure control. Epilepsy is a common neurological disease characterized by the manifestation of unprovoked seizures . An epil2) which in turn leads to activation of adenosine receptors, extracellular acidosis and opening of KATP channels due to local shortage of ATP. These changes build up consecutively during the course of a seizure establishing conditions that not only contribute to the cessation of the activity but could potentially alter the normal neuronal functioning in the postictal phase. Conversely, disturbed energy metabolism could by itself favor seizure initiation by altering the ability of the tissue to recover transmembrane ion gradients following neuronal activity, as it is seen in mitochondrial encephalopathies , pyruvate, fructose 1,6 bisphosphate, ketogenic diet, CO2 inhalation, carbonic anhydrase inhibitors, adenosine 1 agonists). The last part is devoted to the mechanisms of seizure-induced neurovascular decoupling, which might be responsible for postictal hypometabolism and have been suggested to be associated with cognitive disturbances. We apologize that we cannot extensively discuss all aspects of seizure termination and regulation of neuronal energy metabolism as well as the anti-seizure mechanisms associated to caloric restriction and ketogenic diet.In the following we provide a short overview of the literature about the alterations of neurometabolic coupling during seizures and how these could contribute to seizure control. We discuss possible therapeutic targets which exploit metabolism-related mechanisms  concentrations . First, the adenine nucleotide translocator is activated leading to a decrease in mitochondrial ATP and mitochondrial membrane potential (ψ) as the exchange of ATP (3 negative charges) for ADP (2 negative charges) is an electrogenic process. The shift in cytosolic and mitochondrial ATP/ADP ratio and the decrease in ψ activate F0F1-ATPase, further draining the ψ. As a consequence, complexes IV, III, and I of the ETC are activated by associated shifts in the electron carriers, cytochrome C and ubiquinone (QH2). This activation results in the initial oxidation shift in mitochondrial NADH, which can be observed by NADH-autofluorescence  channel complex leading to increased matrix Ca2+ concentration. Matrix Ca2+ plays a key regulatory role as it can enhance ETC in a potassium dependent manner . Typical biphasic changes in the redox state of flavin and adenine dinucleotides (FADH2 and NADH) can be observed following physiological stimulus in vivo . On the other hand, metabolic disturbances during frequently recurring seizures or in chronic epileptic tissue rather favor than limit the occurrence of hypersynchronous activity  in a brain slice preparation Schoknecht and colleges showed that a fivefold increase in CMRO2 was able to compensate for the enhanced energy demand of seizures whereas the decrease in overall cytosolic ATP content remained relatively small  receptor antagonist DPCPX could reverse completely the antiseizure effect of 4CIN  indicatiin vitro  suggestiin vitro .in vivo models  receptor currents  and a proton (H+), possess anticonvulsant effects  of the tissue, local pO2 depends solely on the rate of respiration and the diffusion distance from the surface  and thereby the efficiency of oxidative metabolism is improved during seizure-like events. Notably, at maximum CMRO2, tissue pO2 as well as the reducing equivalents for the ETC were not rate limiting for the energy metabolism, suggesting that shortage of these factors is not a necessary prerequisite for seizure termination , seizures induce reversible vasodilation and disproportionally high increases in the blood flow, resulting in an overshooting supply of oxygenated hemoglobin, underlying the seizure-associated BOLD response . The fireceptors .2 dip and temporary reduction of the blood flow was documented in the tissue surrounding the epileptic focus as well as in the contralateral hemisphere  into parenchymal arterioles with the advantages of capillary imaging in brain slices . Manipulating substrate availability, preventing glycolysis, lactate uptake as well as enhancing pentose phosphate shunt might have both acute pro- or anticonvulsant effects, whereas chronic dietary changes can exert seizure control via epigenetic mechanisms. Thus targeting negative feedback mechanisms involved in metabolism dependent regulation of excitability as well as supporting cellular bioenergetics and protecting neurovascular coupling may represent promising therapeutic approaches in the treatment of epilepsy.In conclusion, substantial evidence suggests that seizure termination can occur in the presence of intact neurometabolic coupling and overshooting neurovascular responses without immediate limitation on the metabolism. On the other hand, enhanced energy metabolism exerts a strong negative feedback on neuronal excitability, mostly via adenosine and pH changes. Free radical-dependent damage of mitochondrial enzymes and the subsequent disturbances in energy metabolism observed in chronic epileptic tissue were found to be rather proconvulsive (RK, NB, OP, and ZG reviewed the bibliography and wrote the first draft of the manuscript. AF, SG, and JO added substantial comments after critical reading of the text.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.


Though thrombolysis with tPA has been proven to be effective in treating AIS within the time window, the majority of AIS patients fail to receive tPA due to various reasons. Current medical therapies for AIS have limited efficacy and pose a risk of intracerebral hemorrhage. ADAMTS13  is a metalloprotease that effectively breaks down the von Willebrand Factor (VWF), a key factor in thrombus formation. Previous studies have proven that dysfunction of ADAMTS13 is associated with many diseases. Recently, ADAMTS13 has been reported to be closely related to stroke. In this review, we briefly described the structure of ADAMTS13 and its role in thrombosis, inflammation, as well as angiogenesis. We then focused on the relationship between ADAMTS13 and AIS, ranging from ischemic stroke occurrence, to AIS treatment and prognosis. Based on research findings from  Stroke is one of the leading causes of death and disability in both developing and developed countries . IschemiADAMTS13 , also known as the von Willebrand factor-cleaving protease (VWFCP), is predominantly synthesized in the liver. It cleaves the ultra-large molecule—von Willebrand factor (VWF), a key player in initiating platelet tethering and subsequent platelet adhesion , into smADAMTS13, originally named VWFCP, was purified from the human plasma for the first time in 1996 . ThereafADAMTS13, a metalloprotease containing 1,427 amino acid residues, is predominantly secreted by hepatic stellate cells . It has Recently, more functions of ADAMTS13 have been revealed with the identification of a substrate-induced conformational activation mechanism. ADAMTS13 circulates in a quiescent form, maintained by an autoinhibitory interaction between its N-terminal spacer domain and its C-terminal CUB-domains . Its actThe critical role of ADAMTS13 in thrombosis is exemplified by its importance in the pathogenesis of thrombotic thrombocytopenic purpura (TTP). TTP is a life-threatening microangiopathic disorder of the blood-coagulation system, caused by the deficiency of ADAMTS13 either in quantity or in quality . MutatioAdhesion of platelets is the first step not only in thrombosis but also in inflammation mediated by VWF. ADAMTS13 down-regulates both thrombosis and inflammation through cleavage of VWF. Previous studies have demonstrated that ADAMTS13 prevents the formation of thrombi in injured microvenules and regulates thrombosis in arterioles by altering the interaction between platelets and VWF , 20.in vitro experiment has shown that plasmin cleaves VWF at K1491-R1492 in the A1-A2 linker region in a shear- and glycan-dependent manner (−/−) leads to aggravated inflammatory and thrombotic responses. Treatment with ADAMTS13 decreases the severity of colitis through its anti-inflammatory mechanism , but it counteracts the angiogenic activity of VEGF  mice through bone marrow transplantation to determine the function of different types of VWF in stroke. They found that no difference was seen in infarct size and post-ischemic inflammation between Plt-VWF and Plt-VWF/ADAMTS13−/− mice, but the infarct size and post ischemic inflammation were significantly aggravated in EC-VWF and wild-type mice and attenuated in VWF−/− mice compared with those of Plt-VWF or Plt-VWF/ADAMTS13−/− mice  mice, Plt-VWF mice with ADAMTS13 deficiency, and endothelial cell-derived VWF , and vascular maturation is also reliant on angiopoietins (Angs) 1 and 2 . It was Currently, thrombolysis with tissue plasminogen activator (tPA) remains the most effective therapy for patients with AIS, but it has a high risk of intracerebral hemorrhage. Although studies on the efficacy of ADAMTS13 in managing ischemic stroke is still at the stage of animal research, it has shown advantages and is expected to provide a new direction for the treatment of ischemic stroke. It has been reported that recombinant ADAMTS13 (rADAMTS13), when injected into mice before ischemia reperfusion, significantly reduced the infarct volume and improved prognosis without eliciting intracerebral hemorrhage. To further explore the effect of ADAMTS13 on ischemic stroke, the team injected tPA, VWF, and rADAMTS13 into ischemic stroke mice and tested the permeability of the blood brain barrier along with intracerebral hemorrhage. It was found that 540 ng VWF increased the permeability of the blood brain barrier, which was completely reversed by rADAMTS13. Interestingly, rADAMTS13 alone had no effect on the permeability of the blood-brain barrier. Injections of tPA led to intracerebral hemorrhage and the volume of the hematoma was reduced by rADAMTS13. Injections of rADAMTS13 alone did not lead to intracerebral hemorrhage. Simultaneous injections of both VWF and tPA did not show significant differences in intracerebral hemorrhage from injections of tPA alone . A study−/− mice were significantly lower than those in wild-type mice 14 days after the ischemic stroke onset, and that deposition of destructed blood-brain barrier and peripheral serum proteins were significantly increased in ADAMTS13−/− mice. In contrast, VWF−/− mice showed significantly more new microvasculature after reperfusion than wild type mice. Injections of rADAMTS13 to wild type mice 7 days after stroke onset increased the formation of neovasculature and repair of blood vessels, and significantly improved the 14-day prognosis after stroke , but increased to normal later (≥3 months). It was speculated that ADAMTS13 might play an important role in counteracting thrombus formation in ischemic stroke. In addition, no correlation was found between levels of ADAMTS13 and subtypes of stroke. This study did not examine the relationship between levels of ADAMTS13 and the prognosis of ischemic stroke patients . The RotIn summary, the structure and function of ADAMTS13 have been elucidated in the past 20 years. It has been proven that ADAMTS13 is closely related to the occurrence, development, and prognosis of ischemic stroke, protecting the brain from ischemia-reperfusion injury. The VWF:ADAMTS13 ratio has a strong correlation with the risk of stroke. Complete deficiency in ADAMTS13 alone does not lead to ischemic stroke but a prothrombotic state, and the latter may result in ischemic stroke in conjunction with additional genetic or environmental factors. The activity and levels of ADAMTS13 have a good predictive value for the occurrence and prognosis of ischemic stroke. In addition, animal studies on ADAMTS13 in the treatment of AIS have made remarkable progress, especially in the model of conformational activation. ADAMTS13 is expected to become a new therapeutic agent for ischemic stroke.XChen, XCheng, and DW devised the review. XChen and XCheng conducted literature review and provided the first draft. XChen, XCheng, and SZ created the figures. All authors contributed to manuscript revision and approved the submitted version.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.


Microcephaly is a neurodevelopmental condition characterized by a small brain size associated with intellectual deficiency in most cases and is one of the most frequent clinical sign encountered in neurodevelopmental disorders. It can result from a wide range of environmental insults occurring during pregnancy or postnatally, as well as from various genetic causes and represents a highly heterogeneous condition. However, several lines of evidence highlight a compromised mode of division of the cortical precursor cells during neurogenesis, affecting neural commitment or survival as one of the common mechanisms leading to a limited production of neurons and associated with the most severe forms of congenital microcephaly. In this context, the emergence of the endoplasmic reticulum (ER) and the Golgi apparatus as key guardians of cellular homeostasis, especially through the regulation of proteostasis, has raised the hypothesis that pathological ER and/or Golgi stress could contribute significantly to cortical impairments eliciting microcephaly. In this review, we discuss recent findings implicating ER and Golgi stress responses in early brain development and provide an overview of microcephaly-associated genes involved in these pathways. Magoh display microcephaly due to an increase of neuronal apoptosis and a depletion of the intermediate progenitors [Brain size and how it has been tuned during evolution is a fascinating issue and studying cortical development in mammals represents a relevant approach to decipher the complex regulation of neural stem cells division and the pathological phenotypes associated with its failure, such as microcephaly. Microcephaly affects around 2% of the population worldwide and is one of the most frequent neurological signs encountered in neurodevelopmental disorders. It is characterized by a small brain size and is frequently associated with intellectual disability (ID) of variable severity. The dramatic increase in congenital microcephaly associated with the recent outbreak of Zika virus in Brazil as well as the identification of a large number of rare genetic forms of microcephaly over the last two decades have largely contributed to the understanding of the underlying mechanisms. They often involve a compromised division of cortical precursor cells affecting their neural commitment or survival and ultimately leading to a limited production of neurons. That brain size is determined by a fine regulation of cell number and the role of apoptosis has been exemplified in several mouse models: For example, mice haploinsufficient for genitors . Conversgenitors . HoweverCorticogenesis is a complex and organized process regulated in time that takes place during pregnancy and results in the formation of the cortex from the dorsal neuroepithelium of the telencephalon. In humans, the cortex is thought to comprise more than 20 billion neurons , most ofImpairment of corticogenesis ultimately leading to a decreased production of neurons results in a congenital failure of brain growth called primary microcephaly (PM), a condition often associated with ID of variable severity. In clinics, PM is initially diagnosed through the measurement of the occipito-frontal circumference (OFC) of the head that increases during infancy following established curves. An OFC smaller than the age- and gender-adjusted mean by more than two standard deviations (SD) at birth is by definition indicative of PM. Underlying causes may be environmental factors  or genetic mutations , 16. In Despite this heterogeneity, several lines of evidence accumulated over the last years converge collectively toward mechanisms compromising chromosomal segregation and mitotic division especially in the developing cortex thereby leading to the exhaustion of the neural progenitor pool either through increased apoptosis or by premature differentiation and that results in PM. The various genes that have been associated with PM over the last 15 years have actually contributed greatly to the understanding of the main pathways involved in normal development and whose deregulation elicits PM . Among tMutations in several genes encoding DNA replication factors or DNA repair proteins have been identified in PM, pointing out genome instability as a frequent cause of PM –21. DNA MCPH genes, a family of 25 genes identified so far, most of which encode centrosomal, microtubule- or kinetochore-associated proteins; MCPH genes are highly expressed during brain development and in most cases their protein products are involved in the regulation of the mitotic spindle (including its formation and orientation), in the control of cell cycle or in the segregation of chromosomes especially during the division of progenitors of the ventricular zone at the onset of corticogenesis . Deficiency in MCPH genes causes PM and the most frequent form of PM, MCPH5, is associated with loss of function of ASPM , a protein localized at the minus end of microtubules at the centrosome [in vivo of several MCPH proteins such as ASPM, WDR62 or CDK5RAP2 results in premature neuronal differentiation of the progenitors in the developing neocortex [Deregulation of the cell cycle control as a mechanism of PM is unambiguously illustrated by the ntrosome . Defectintrosome , 32. Likntrosome –39. Depentrosome . In highntrosome , the othntrosome . Aneuplontrosome , 44 and ntrosome . Howeverntrosome . Likewiseocortex , 35, 47,eocortex .. However, when the UPR faces a significant overload of misfolded cargos and fails to normalize the situation it ultimately mediates apoptotic cell death [. In addition to its role in the PERK-eIF2α-ATF4 arm of the UPR, eIF2α lies at the core of the translation initiation machinery as one of the three subunits α, β and γ of the eukaryotic translation initiation factor 2 (eIF2) complex. eIF2 associates with GTP and the initiator methionyl-tRNA, and binds to the small 40s ribosomal subunit to participate in protein translation [As the main site of protein synthesis, the ER permanently faces important flows of nascent polypeptides that need to be properly folded, matured and transported. These processes are helped by a number of chaperone proteins (such as heat shock proteins from the Hsp70 and Hsp90 families or the glucose-regulated protein BiP/GRP78) and folding enzymes  that are critical in maintaining ER proteostasis , 50. Misll death . In mammll death . These tll death . Upon acnslation . PhosphoAlthough ER proteostasis is important in all cells and tissues, its particular role during brain development, especially during corticogenesis, has been highlighted by several studies suggesting that ER stress and the UPR physiologically participate in embryonic cortical development. Several stress-regulated chaperones and folding enzymes including BiP/GRP78, GRP74, PDI and Calreticulin were found particularly abundant in mouse embryonic cerebral cortex as compared to adult brain, and all three UPR pathways are activated during CNS  development, including in the ventricular zone of the developing cortex –58. In aex vivo and in vivo models of ethanol-induced neuronal cell damage [in vivo and in human neural stem cells ex vivo and contributes to the development of microcephaly in mice, mainly through over-activation the PERK-eIF2α-ATF4 pathway, which (as seen in the Elp3 knock out model) results in an impairment of indirect neurogenesis [PPP1R15B result in increased eIF2α phosphorylation and stress resistance and also cause microcephaly, short stature and impaired glucose metabolism  [PPP1R15B mutations, at least in vitro [ATF4 have not been reported in human pathology, forced expression of the gene in Xenopus embryos resulted in severe microcephaly with absence of eyes [In human as well, several lines of evidence indicate that interfering with ER stress pathways during brain development results in neurodevelopmental disorders including PM. For example, alcohol dependence during pregnancy can induce fetal alcohol spectrum disorders (FASD), a condition commonly associated with PM and ID, due to high vulnerability of the immature brain to ethanol exposure . A deregl damage –68 that l damage , 70. Alcl damage . ZIKA vil damage –74 and ml damage . ZIKV trogenesis . In lineogenesis . HomozygM616817) , 79. Proin vitro . Interes of eyes .EIF2S3, the gene encoding eIF2γ that was shown to compromise eIF2 complex integrity and translation initiation, cause MEHMO (#MIM300148), a syndrome associating epilepsy, hypogonadism, obesity and microcephaly with ID [OSGEP, TP53RK, TPRKN or LAGE3, which encode the four subunits of the KEOPS complex  result in Galloway-Mowat syndrome , an early-onset nephrotic disorder with severe PM [OSGEP, TP53RK, TPRKN resulted in impaired protein translation, ER stress and the activation of the PERK-eIF2α-ATF4 and IRE1α-XBP1 pathways [The contribution of eIF2α in both UPR and translation initiation suggests that both processes are regulated at least in part by common factors and that a deficiency in translational accuracy could also result in microcephaly in humans. Indeed, mutations in  with ID . Loss-ofevere PM . The KEOevere PM . CRISPR/pathways . Thus, lpathways , a defecThe GA is a highly dynamic organelle that permanently adapts its morphology and processing capacities in response to secretory flows depending on cell demand. In several pathologies where its secretory function is overwhelmed or compromised, including neurodegenerative and neurodevelopmental diseases, the GA appears swollen and/or fragmented , 85. Of However, defects observed at the level of the GA do not always result from alteration of ER functions. It is now clear that the GA can directly initiate and modulate signalling cascades , and the. These target genes encode several glycosylation enzymes , as well as factors involved in Golgi structure and vesicular transport such as WIPI49, ACBD3, the golgins GM130 and Giantin, the small GTPase Rab20 and Syntaxin 3A [A first Golgi stress pathway is mediated by the bHLH leucine zipper transcription factor E3 (TFE3). TFE3 expression increases upon Golgi stress such as monensin (MON) treatment  and the transcription factor translocates into the nucleus. There, it activates the expression of genes that include in their promoter the consensus sequence "ACGTGGC" called the Golgi apparatus stress response element (GASE)   or golgicide A (GCA) in addition to MON, and the study of their mechanisms of action has considerably helped identifying key factors involved in the regulation of Golgi morphology and activation of stress response. A second signaling pathway mediated through the CREB3 transcription factor has indeed been uncovered thanks to a genetic screen for resistance to BFA-induced toxicity : The ADPAlso identified in the same genetic screen for resistance to BFA-induced toxicity , TRAPPC1. Another pathway triggered by diminished levels of glycosylation enzymes for mucins has been reported very recently [Alternative Golgi stress pathways could be initiated by the abnormal accumulation of certain compounds in the GA that are capable of activating a signaling cascade. Such a mechanism involving abnormally/insufficiently glycosylated proteoglycans has been proposed by Hiderou Yoshida . Treatmerecently . This mutrans-Golgi network (TGN), also plays a role in the ribbon structure and binds phosphatidylinositol-4-phosphate (PtdIns-4-P) and actomyosin to stretch the Golgi and promote budding [Recent studies have revealed a role for several other Golgi proteins in sensing distress potentially caused by glucose starvation, oxygen deprivation or DNA damage, indicating that the GA is sensitive to a broad range of cell stressing agents and suggesting that additional signaling pathways activated in response to these situations remain to be identified. The Golgi reassembly stacking protein GRASP55, whose main known function in mammalian cells is to ensure the lateral linking of Golgi stacks into a single ribbon, is relocated to the autophagosome-lysosome interface upon glucose starvation where it promotes autophagosome maturation , 109. GO budding , but rel budding . GOLPH3  budding , 113 and budding –117.et al. showed that this apical distribution of the GA is mediated by a lipid signaling pathway, involving the two highly related lipid transfer proteins PITPNA and PITPNB. PITPNA/PITPNB potentiate the PtdIns-4-P-dependent recruitment of GOLPH3 to Golgi membranes, which in turn interacts with MYO18A and F-actin to direct the loading of the GA to apical compartments [et al. described how GOLPH3 induces Golgi membrane curvature upon binding to PtdIns-4-P-rich lipid bilayers and how this membrane-shaping function of GOLPH3 is a pre-requisite to enable efficient anterograde trafficking through its direct interaction with MYO18A [In addition to its canonical functions in processing newly synthesized proteins and lipids and regulating their sorting and routing to their final destination in most cells, the GA possess particular features specific to aRGCs that underpin a crucial role of the GA in maintaining neural stem cell polarity that may have consequences for neural progenitor cell fate transition during corticogenesis in mammals . By contartments . In a moh MYO18A . Collecth MYO18A . Furtherh MYO18A .Among the growing number of Golgi-related genes known to be associated with disease (Golgipathies) over 40% affect the central or peripheral nervous systems, highlighting the critical importance of the GA to neural function , 123. AsFor example, following TFE3 translocation into the nucleus various target genes are activated, among which are a number of glycosylation enzymes such as sialyltransferases and fucosyltransferases as mentioned above. Interestingly, abnormal fucosylation and sialic acid deficiency have been reported in association with congenital disorder of glycosylation type IA , the most common form of CDG  , 125. CDARFGEF2) in patients with an autosomal recessive periventricular heterotopia with microcephaly  [ARFGEF2 encodes BIG2, a guanine nucleotide-exchange factor involved in vesicle trafficking between endosomes and the TGN during cortical development [Another example has been reported by Sheen and colleagues who identified loss-of-functions mutations in the ADP-ribosylation Factor Guanine Exchange Factor 2 (#608097) . ARFGEF2elopment . A more elopment . BIG2 alelopment . Loss ofelopment . Treatinelopment . Thus, ielopment , 135.The TRAPP complex, which in addition to its role as tether also modulates the response to Golgi stress through several of its subunits as mentioned above, was first identified in yeast where three related complexes have been described. Despite a high degree of conservation with yeast, only two complexes, homologous of TRAPP II and III have been reported so far in mammals . In humaPathways associated with ER stress are by far more studied and have received more attention than those associated with Golgi stress which are only starting to be deciphered. It has become obvious nevertheless that both organelles dynamically and specifically react to various cell stresses to maintain proper cellular homeostasis. Why brain development would be so strongly affected by defects in ER/Golgi stress control is still an open question. One key particularity of neocortical development is that neural stem cells need to divide and differentiate actively in a short period of time and according to a spatially regulated pattern, which involves sequential waves of progenitors and neurons production. Hence, a deregulation of ER or Golgi stress pathways in the developing brain may understandably end in catastrophic outcome. In addition, brain development strongly relies on highly polarized cells at every step of corticogenesis from the first neuroepithelial cells to aRGCs, bRGCs and to neurons. As polarity establishment and maintenance are both highly dependent on traffic through the secretory pathway, an impairment of cell polarity could be one of the reasons to explain the particular vulnerability of the brain to ER/Golgi stress. Proper control of the extracellular environment, stem cell niches, may also be particularly important and rely on intense and proper function of the secretory pathway in such a short time. This pinpoints the essential adaptive capacities of the mammalian brain in addressing and solving the permanent aggressions and disequilibrium that it experiences and suggests that additional cell homeostasis pathways, whose deregulation might be associated with microcephaly, will be identified in the near future.