In this review paper, we discuss the contribution of proteomic studies to the discovery of disease-specific biomarkers to monitor the disease and evaluate available treatment options for psoriasis. Psoriasis is one of the most prevalent skin disorders driven by a Th17-specific immune response. Although potential patients have a genetic predisposition to psoriasis, the etiology of the disease remains unknown. During the last two decades, proteomics became deeply integrated with psoriatic research. The data obtained in proteomic studies facilitated the discovery of novel mechanisms and the verification of many experimental hypotheses of the disease pathogenesis. The detailed data analysis revealed multiple differentially expressed proteins and significant changes in proteome associated with the disease and drug efficacy. In this respect, there is a need for proteomic studies to characterize the role of the disease-specific biomarkers in the pathogenesis of psoriasis, develop clinical applications to choose the most efficient treatment options and monitor the therapeutic response. Psoriasis is one of the most prevalent chronic skin disorders. The common symptoms of psoriasis include red patches covered with flaking silvery scales, itching, burning, or soreness, and thickened, pitted, or ridged nails . The hisPsoriasis is a multigenic and multifactorial disorder. The heritability of the disease is complex due to the contribution of multiple susceptibility loci . The genThe term “proteomics” proposed by Mark Wilkins in 1994 applies to the studies that describe and compare sets of proteins expressed in cultured cells, tissues, or the entire organism in desired conditions . DiffereFor their studies, the authors of the earliest papers used 2D gel electrophoresis followed by mass spectrometry, MS . In 2005Ryu et al.  identifiUsing a similar technique, Piruzian et al.  reported3 in the pathogenesis of the disease. Presumably, the authors were the first who analyzed the whole proteome of the human lesional epidermis and reported ten of the most upregulated proteins, such as S100A8 and S100A9. Then, using JunB-Jun double knockout mice, they also characterized the role of S100A8-S100A9 dimer in the inflammatory response triggered by the disease.Several extensive, large-scale comparative proteomic studies were aimed to identify and characterize the molecular mechanisms of psoriasis. The paper by Schonthaler et al.  providedTo reduce the complexity of experimental data, Williamson et al.  replacedComparing the proteomes of the stratum corneum, Méhul et al.  identifiBased on the results of their study, Méhul et al. recommended noninvasive sampling of stratum corneum as a reliable method to quantify protein biomarkers in patients’ skin. As they also noticed, their protocol allowed ranking the drugs according to their clinical efficacy. Compared to normal-looking skin, skin lesions exhibited the elevated expression of chemoattractants of neutrophils (CXCL1 and CXCL8), T-cells (CCL4 and CXCL10), monocytes, and dendritic cells . Moreover, the authors proposed using CXCL1, CXCL8, CXCL10, and the soluble form of ICAM to monitor the progress of alternative topical treatments to rank them on their clinical efficacy .n = 10 and 24, respectively). To the reference, cutaneous T-cell lymphoma is often confused with psoriasis because clinical manifestations of CTCL at the early stages are similar to ones in psoriasis. Analyzing the samples, the authors identified 431 and 543 in CTCL and psoriatic lesional skin, respectively, compared to normal-looking skin. As they noticed, both types of skin lesions shared many of these DEPs. However, IL37 and IL36G were significantly changed in psoriatic lesional skin and were not in patients with CTLC. Contrarily, CCL27 was differentially expressed in CTCL and was not in psoriatic skin lesions. Then, they established a molecular signature of 112 DEPs. This signature allowed them to distinguish the samples obtained from patients with CTCL and psoriasis. In addition, the authors validated the expression of 40 differentially expressed cytokines with the Luminex assay.Notably, the technique developed by Méhul et al. can also help in the differential diagnosis of psoriasis. In a short follow-up study , they anSwindell et al.  performeIn a more recent paper, Szél et al.  demonstrRevealing the genetic vulnerabilities and exploring the main risks triggering the disease are among the principal problems addressed in population-specific studies. These studies appeal to a population of a particular country, people of certain races and ethnicity. In turn, their results help local authorities better define the people’s medical needs and timely provide the correct assistance. Because Asians are 5–6 times less susceptible to psoriasis than the Caucasian population of the industrialized western countries, the studies of people of Asian descent are one of the most valuable parts of population-specific studies. Being one of the largest Asian ethnic groups, the Chinese population represents the high interest in searching for the genetic variants that explain the resistance to the disease.n = 15) labeled with TMT. The authors identified 3686 and quantified 3008 proteins. They found 102 and 124 DEPs with significantly higher and lower abundance in lesional skin, respectively . They also reported S100A9 and MMP3 as the most up- and downregulated proteins in their study . Comparing their data with previously published results, the authors suggested some populational differences between China and other countries. In this regard, they reported SART1 as DEP previously unassociated with the disease. In addition, Wang et al. )n = 20) confirmed the differential expression of six proteins, namely HMOX1, KRT19, LDHA, HSPD1, MAPK1, and CA2. We proposed that these proteins could be a part of a protective mechanism that facilitates an adaptation to the progressing inflammatory response (HMOX1 and LDHA) as well as higher transcription (HSPD60) and proliferation (KRT19) rates. As we believe, the proposed protective mechanism , the authors identified 269 DEPs among other 7269 proteins. Although Zhou et al. 18]), Zhou et al. , reporteMore than half of the proteins encoded in the human genome undergo post-translational modification. Protein modifications influence their interactions with substrates and binding to other proteins, changes cellular location, signal transduction, enzymatic activity, and stability. To date, about two hundred protein modifications are known. Lysine 2-hydroxyisobutyrylation (Khib) is one of several known acetylations that target lysine residues (review in ). In hisp = 0.0004), S100A2 , and SERPINB4  and the transporter of fatty acids FABP5 . Contrarily, the levels of tenascin  and HSP90B1  were significantly higher in lesional skin. Moreover, the ontology analysis revealed the highest representation of modified proteins in the P13K-Akt signaling pathway. Although the authors did not discuss it in the paper, their data indicate that the most modified proteins exhibited lower abundance in lesional skin than normal-looking skin of the patients and vice versa. Respectively, Knib might reduce the functionality of DEPs upregulated by the disease. At the same time, it likely produced the opposite effect downregulated DEPs.In a recent study Ge et al.  analyzedIn conclusion, the reviewed proteomic studies revealed a variety of biomarkers helpful in diagnosing and monitoring the disease. The main remaining challenges to proteomic studies are the complexity of the samples and, especially for skin, the high abundance of insoluble proteins. The role of many potential biomarkers in the pathogenesis of psoriasis remains unclear, and their mechanisms of action are not yet fully explored. As we show below, the constant improvement of techniques and instrumentation already help monitor the therapeutic response and predict the resistance to therapy. In the future, the broad implementation of disease-specific biomarkers to clinical practice will revolutionize our understanding of psoriasis and lead to the development of a personalized approach in medicine.To date, histopathological analysis of skin specimens remains one of the most common and efficient clinical identification methods. However, this method is inconvenient for the patients as taking skin biopsies is invasive. Moreover, it is unlikely that skin specimens would be used to test people for predisposition to psoriasis before they present any skin manifestations. Respectively, there is a need for non-invasive molecular techniques that could help to accomplish these tasks .For the last twenty years, proteomics is often used to identify DEPs in patients’ blood samples compared to blood samples of healthy volunteers and suggest biomarkers for clinical evaluation. Human blood contains essential information about many physiological and pathological conditions. As a reservoir of proteins secreted from different organs and tissues, the blood adequately reflects the status of human health. As psoriasis generally manifests as chronic skin inflammation, the concentration of proinflammatory cytokines in the patients’ plasma is significantly higher than in the plasma of healthy individuals. In this respect, studying the specific metabolic changes produced by psoriasis can be conducted using the patients’ blood. First, the collection of blood by venipuncture is minimally invasive. Second, combining venipuncture with one of the proteomic approaches provides access to relevant biomarkers of the disease. Third, comparing the blood samples taken at different time points allows precise monitoring of the therapeutic response.2+-binding proteins and their peptides increased in the patients’ blood. The authors did not suggest any disease-specific biomarkers for psoriasis because the levels of identified proteins could vary more than 30-fold from patient to patient. However, they recommended their protocol for studies of potential glycoprotein biomarkers. As they noticed in the paper, their original protocol offered a good balance between throughput and sensitivity, and it is crucial to discover new biomarkers.Plavina et al. performed two studies to analyze peptides and proteins from the patients’ blood ,13. In tm/z ratios of the produced ions, ESI-FTICR determines their frequencies and then, it transforms the frequency spectra to the m/z spectra.In the second study , PlavinaThe authors identified 21 DEPs, including thymosin β4, talin 1, γ-actin, filamin, profilin, S100A8/calgranulin A, and S100A9/calgranulin B. Most of the identified proteins were previously associated with different autoimmune and inflammatory disorders. In addition, four of them, namely calgranulins A and B, galectin 3, and galectin 3–binding protein, were either linked to psoriasis or altered in psoriatic serum. Although the results obtained by both methods were consistent with each other, the authors suggested using both protocols in parallel to reveal additional details on the potential blood-circulating biomarkers.Fattahi et al.  identifi3, polymeric immunoglobulin receptor/PIGR, and plasma kallikrein/KLKB1, to distinguish patients and healthy individuals. They also discovered eleven combinations of DEPs that might serve even better for the same purpose. In addition, the authors reported that the expression levels of desmoplakin/DSP, complement C3, PIGR, and KRT17 strongly correlated with patients’ PASI.To find the biomarkers that exhibit the strongest correlations with disease severity, Reindl et al.  compared2–16) and p1977 , could contribute to the development of the inflammatory response in the patients. As they observed in the following experiments with cultured cells, these peptides moderately influenced the secretion of humoral factors  and cytokines .Following similar objectives, Matsuura et al.  analyzedKYNU as a DEG in psoriatic skin. Moreover, KYNU is also synergistically regulated by proinflammatory cytokines IL17 and TNFα that play a central role in the pathogenesis of psoriasis [Using the SomaScan™ technology   based onsoriasis . AlthougRecently, Gęgotek et al.  comparedImmune cells, primarily the lymphocytes, which infiltrate psoriatic skin, are one of the principal sources of proinflammatory cytokines. These cells secrete koebnerisin/S100A15 and psoriasin/S100A7) . Then, kExploring the proteomic profiles of epidermal keratinocytes, lymphocytes, and dermal fibroblasts of psoriasis patients and healthy volunteers, Łuczaj et al. found differences in the expression patterns of thioredoxin and glycolytic enzymes . In patin = 31) who had noticed the first signs of the disease no longer than 30 days before the blood collection. The latter explains their ability to identify many new disease-associated proteins .In turn, the study conducted by Li et al.  providesp < 0.01), CCL22, and IL12B discovered a strong correlation with PASI. Moreover, the expression of TNFRSF8 and CD14 correlated with the VAS score, i.e., a quantitative assessment of itch intensity. In addition, Xu et al. [Summarizing the previous findings on psoriasis biomarkers in the human sera, Xu et al.  developeu et al.  split thIn summary, various proteomic studies have identified more than 100 potential biomarkers in patients’ blood. On the other hand, the diversity of psoriasis complicates their validation, and the similarity of different autoimmune disorders makes it difficult to prove their relevance to a particular disease. Future studies of potential biomarkers are needed to explain correlations of their levels and severity of psoriasis by connecting their mechanisms of action and biological activities to the pathogenesis of the disease.Psoriasis is known for its complexity and heterogeneity. The complexity of psoriasis presumes that the disease alters the expression of multiple genes and causes serious miss-regulation of various signaling pathways. Moreover, the disease causes pathological changes in many tissues and organs. Heterogeneity of psoriasis appears in multiple skin phenotypes and associated comorbidities that significantly affect the patients’ quality of life. Although many treatment options are available, the cure for psoriasis is yet not found. Up to a third of psoriasis patients do not respond well to the prescribed therapies. On the other hand, patients non-responding to one of the biologics can experience an improvement after switching to another .n = 5). They also showed that syndecan 1/CD138 and transferrin receptor protein 1/TRF1/CD71 expression could serve as prognostic factors in the assessment of treatment efficiency. In addition, they discovered that the levels of CD45, CD2, CD4, and CD8 was significantly decreased in responders suggesting that these DEPs could monitor the presence of leukocytes and different subpopulations of T-cells.The first attempt to use a proteomic method to monitor the disease response to a therapeutic agent was performed by Bonnekoh et al. in 2007 . In theiKolbinger et al.  comparedn = 10) before and after the treatment with etanercept. The authors discovered a higher expression of TNF-dependent proteins in patients’ blood. They also saw an altered expression of proteins belonged to the interferon signature that normalized after the treatment. For reference, a similar response to etanercept was previously discovered in the skin [Foulkes et al. used SomaScan  to explothe skin .The study performed by Medvedeva et al.  clarifieIn summary, the development of therapeutic antibodies and small molecules targeting psoriasis into clinical practice resulted in significant improvement for patients with severe psoriasis. Although the previously performed proteomic studies have allowed to identify some biomarkers of the therapeutic response in inflammatory skin diseases ,73, the Although psoriasis is considered a skin disease, the patients often experience comorbidities, such as cardiovascular diseases, metabolic syndrome, inflammatory bowel disease, etc. . Moreovec domain of IgG1. It binds and neutralizes TNF, one of the key proinflammatory cytokines in psoriasis [Patients with psoriasis more frequently experience myocardial infarction, stroke, and coronary heart disease . To assesoriasis . Tofacitsoriasis . Both drsoriasis . In the soriasis . In the As we have already mentioned above, psoriasis patients are often diagnosed with comorbidities. At some point in their life, ~30% of patients develop psoriatic arthritis. In contrast, ~15% of patients with arthritis develop psoriasis . In addiTo achieve this goal, Cretu et al.  performen = 5) before analyzing them by LC-MS/MS, and only two proteins, namely ITGB5 and POSTN, were validated by ELISA, other attempts to identify the biomarkers of psoriatic arthritis followed. Recently, Leijten et al. [n = 18), patients with psoriatic arthritis (n = 20), and healthy volunteers (n = 19). Comparing the protein expression in psoriasis patients and patients with psoriatic arthritis, the authors failed to identify proteins with altered expression in one of the groups. At the same time, they found that ICAM-1 and CCL18 had the strongest positive correlation with the number of swollen joints  while PI3 and IL17RA exhibited the strongest correlation with PASI score . They also reported that both groups of patients were separable by hierarchical clustering. The latter suggested the existence of a hidden molecular signature characteristic for psoriasis patients predisposed to psoriatic arthritis, despite that the authors did not report it in their paper. Thus, theoretically, it may be possible to identify people with a predisposition to psoriatic arthritis among psoriasis patients. Respectively, we may be able to timely and efficiently advise these patients and control their disease.Because Cretu’s study had two significant limitations: the researchers pooled samples . According to the authors, 14 proteins, namely SIRT2, NAA50, ARF6, ADPRHL2, SF3B6, SH3KBP1, UBA3, SCP2, RPS5, NUDT5, NCBP1, SYNE1, NDUFB7, and HTATSF1, can be potential biomarkers of psoriatic arthritis. These proteins were differentially expressed in psoriasis patients with psoriatic arthritis and were not in patients without it. Although the authors minimized the number of samples used in their MS study, they validated their results on the best candidate biomarker SIRT2 by Western blot on a larger group of participants (n = 21). Based on the results of their analysis, Zue et al. [After iTRAQ-labeling, the authors analyzed the samples by LC-MS/MS and discovered 60 proteins with differential expression between two groups of patients  by upwards of 50% . Psoriasn = 23) and healthy volunteers (n = 10). The authors analyzed the expression of 273 proteins associated with the inflammatory response. They identified 17 differentially expressed proinflammatory cytokines, including IL17A, IL6, and CCL20. Their levels were significantly higher in the patients’ blood. Analyzing the data, Elnabawi et al. [p < 0.001) and PASI . The addition of CCL6 as an independent variable to the original computer model increased its specificity and efficiency. Respectively, the authors recommended CCL6 as a biomarker of impaired vascular health in psoriasis patients.Recently, Elnabawi et al.  proposedi et al.  discoveri et al. , stronglMoreover, the same group also reported  of a prop < 0.01) and entire aorta . Moreover, it positively correlated with carotid intima-media thickness  and coronary artery calcium score  in psoriasis patients without cardiovascular disease and statin treatment. In this regard, the authors concluded that the GDF15 level in the patient’s blood could serve as a biomarker of subclinical atherosclerosis in patients with psoriasis.Using the same experimental approach, Kaiser et al.  comparedAs the changes in the proteome of psoriasis patients are well-documented, psoriasis may serve as a model in comparative studies that explore the molecular bases of other chronic inflammatory disorders. To date, several papers have compared the inflammatory potentials of psoriasis, atopic dermatitis , alopecin = 59), psoriasis (n = 22), and healthy volunteers (n = 18), the authors discovered significant differences between the two groups of patients. They showed upregulation of many identified cardiovascular biomarkers in either group of patients . This finding suggested that both disorders increase the risk of cardiovascular events. Ten mutually miss-regulated proteins included the markers of Th1  and Th17 (CCL20 and IL17C) immune responses, and several other proteins, namely IL2RA, IL16, IL20, BLMH, and CDCP1. In patients with atopic dermatitis, the authors found a significantly higher abundance of DEPs involved in Th1 , Th2 , Th17/Th22 (S100A12), and Th1/Th17/Th22 (IL12/IL23p40) signaling pathways. This finding suggests a higher inflammatory potential of atopic dermatitis over psoriasis. In addition, the authors showed a significantly higher expression of proteins associated with atherosclerosis  in the same group of patients. Respectively, the authors concluded that although both diseases share cardiovascular risk factors, such as arterial hypertension, diabetes mellitus, and hypercholesterolemia, patients with atopic dermatitis exhibit a stronger systemic inflammation compared to psoriasis patients.Brunner’s paper  was the n = 35), atopic dermatitis (n =49), moderate-to-severe psoriasis (n = 19), and healthy volunteers (n = 36). Comparing three groups of patients, the authors revealed similar miss-regulations of immune, cardiovascular, and atherosclerosis biomarkers. They found that patients with the advanced forms of alopecia areata exhibited the highest systemic inflammatory tone, and higher expression of cardiovascular risk biomarkers , compared to the other groups of patients as well as their fellow groupmates without total involvement (30 < SALT < 95).The study conducted by Glickman et al.  revealedThe point made by the authors that alopecia areata is a systemic disorder may potentially revolutionize the treatment of the disease. The data presented in this paper justify the necessity of the systemic approach for the therapy of alopecia areata and its advanced forms. The proposed benefits of systemic treatment may include but are not limited to lowering the frequency of cardiovascular events. For instance, it will improve the control of comorbidities and the patients’ quality of life.2 > 0.25, p < 0.1). They also proposed a simple linear model that distinguishes both groups of patients using only two variables, namely the expression levels of peptidase inhibitor 3 (PI3) and lipocalin 2 (LCN2).In the two subsequent studies, the authors compared the blood  and the 1 , IL12/IL23 , and Th17  inflammatory responses in both groups of patients. In addition, they discovered a significantly higher abundance of proteins associated with cardiovascular events  in their lesional skin. The authors showed a significantly higher expression of proinflammatory cytokines, namely, TNF, CCL20, IL6, IL8, and IL12B , compared to healthy control. In contrast, they did not observe similar changes in normal-looking skin of psoriasis patients.Examining the skin samples, Navrazhina et al.  found th1, and Th17 immune responses, as well as biomarkers of atherosclerosis, are upregulated in both patients’ blood and skin [The results of data analysis performed by the authors allow considering hidradenitis suppurativa as a systemic disorder. Navrazhina et al. noticed that cytokines associated with IL12/IL23 signaling pathway, Thand skin ,51. MoreLong-term consumption of methotrexate (MTX), which is one of the most frequently prescribed drugs for psoriasis, causes severe adverse reactions, such as liver injuries and the following hepatic fibrosis . At the n = 60) using MALDI-TOF MS. They divided the patients into two groups depending on whether patients exhausted their high cumulative MTX doses . The authors discovered that patients’ urine contained the precursors of serum albumin and cathepsin B . They also found haptoglobin (HP), prostaglandin-H2 d-isomerase (PTGDS), inter-α-trypsin inhibitor heavy chain H4 (ITIH4), precursor of transferrin (p-TF), zinc-α2-glycoprotein (AZGP1), apolipoprotein D (APOD), cadherin E (CDH1) and cadherin N (CDH2) in patients’ who exhausted they high cumulative MTX dose. The authors reported that p-ALB and p-CATHB were absent in healthy control. At the same time, the other named proteins were undetectable in the samples of patients who consumed less than 1500 mg MTX. As only the levels of ITIH4 and CDH2 were significantly different between the two groups of patients, Swelm et al. [To identify specific biomarkers of MTX-induced hepatic fibrosis visible at an early stage of fibrosis, van Swelm et al.  comparedm et al.  suggesteTo date, both research and clinical scientists know about the potential benefits of the proteomic approach . The established protein biomarkers of psoriasis are suitable for the diagnostics of the disease, monitoring the therapeutic response, and predicting the treatment outcome . For the


Significant correlations between the average number of HRS and visual field mean deviation  and pattern standard deviation  were found. Conclusions: OCT images from glaucoma patients showed a higher number of HRS when compared with healthy controls. As HRS have been hypothesized to be a sign of neuroinflammation, these results may support the role of neuroinflammation in glaucoma etiopathogenesis.Purpose: To compare the number of hyper-reflective retinal spots (HRS) in optical coherence tomography (OCT) images of healthy controls and patients affected with primary open angle glaucoma (POAG). Methods: Thirty patients affected with POAG and 34 healthy controls were recruited and underwent raster OCT examination of the macular region. Among the acquired B-scans, the one with the lowest foveal thickness was selected, and a central area of 3000 μm was defined , in order to identify HRS. HRS were defined as small point-like hyper-reflective elements, detectable at the visual inspection of the OCT image. HRS were independently counted by two investigators in the ROI of each OCT scan. Results: Inter-rater agreement for HRS counting was good to excellent . More HRS were found in the OCT images from glaucoma patients, in comparison with healthy controls (average value: 90.5 ± 13.02 and 74.72 ± 11.35, for glaucoma and healthy subjects, respectively;  Glaucoma is a neurodegenerative disease consisting of a non-uniform group of ocular disorders characterized by a number of clinical features including visual field (VF) defects, retinal ganglion cell (RGC) death and progressive degeneration of the optic nerve. This optic neuropathy represents a complex, multifactorial disease, in which several molecular pathways are involved. Growing evidence suggests that the interaction of RGCs and glial cells, including microglial cells, retinal astrocytes and Muller cells, is critically important for the process of glaucomatous neurodegeneration ,2. IndeeThe environment created by various stress stimuli in the glaucomatous tissue is a major initiator of neuroinflammatory pathways . In thisThe presence of activated retinal microglial cells has recently been associated with the presence of hyper-reflective spots (HRS) in macular B-scan images obtained by the means of optical coherence tomography (OCT) ,8. More To the best of our knowledge, the presence and number of HRS in primary open angle glaucoma (POAG) patients have not been investigated. Aim of this study is to compare the number of HRS in the OCT macular B-scans of patients affected by POAG and healthy controls.This observational study was carried out at the Ophthalmology Clinic of the IRCCS Policlinico San Matteo Foundation and Hospital, Pavia, Italy. All participants were treated in accordance with the ethical tenets on human research of the Declaration of Helsinki. The approval of the local Ethics Committee was also obtained (protocol no. 20190103536). All participants signed an informed consent form, both for their participation in the study and for publication of the results.Subjects already diagnosed with POAG were consecutively enrolled among the patients attending the Glaucoma Service of the abovementioned clinic. POAG was defined as the presence of an ophthalmoscopically abnormal optic disc , an open angle at gonioscopy (Shaffer grade III or IV), and the presence of an abnormal VF consistent with glaucoma. Inclusion criteria were an age between 50 and 80 years, at least 3 reliable and non-progressing VF tests in the previous 2 years , Carl Zeiss Meditec, Dublin, OH, USA), and an IOP between 10 and 18 mm Hg at enrollment visit (Goldmann applanation tonometry). VF progression was assessed by means of the Guided Progression Analysis (GPA) software package of the HFA. GPA has been validated in previous studies, and is a simple and practical method to evaluate functional progression in patients affected with POAG ,13,14. PAllowed hypotensive topical medications were β-blockers, α2-adrenergic agents and carbonic anidrase inhibitors, administered as single agents or as fixed combinations. Patients under treatment with a prostaglandin analogue were excluded, due to the known pro-inflammatory effects of prostaglandins .Controls were recruited from the healthy attendees of the outpatient service, typically scheduled for routine ophthalmological visits. Inclusion criteria were an age between 50 and 80 years and no sign or history of ophthalmological diseases.Exclusion criteria for both the groups of subjects affected with POAG and healthy controls were: a diagnosis of diabetes and/or autoimmune diseases, myopia higher than 3 diopters, media opacities preventing a reliable ophthalmological and OCT examination, cataract surgery performed within the previous 12 months, lifetime history of any other intraocular surgery.All participants underwent a complete ophthalmological examination, including best-corrected visual acuity, biomicroscopy of the anterior segment, IOP measurement with Goldmann applanation tonometry, fundus evaluation after pupil dilation with 1% tropicamide eye drops, and OCT analysis of the macular region with Spectralis OCT . All OCT scans were acquired using the Automatic Real-Time mode of Spectralis OCT, adjusted to 20 frames. To be eligible for the analysis, OCT scans had to show a quality score above 25 dB.Spectralis OCT is a spectral domain OCT incorporating a confocal scanning laser ophthalmoscope, capable of acquiring posterior pole B-scans with a resolution of approximately 7 µm. For study purposes, a standard volume analysis comprising of 25 equally spaced horizontal B-scans was acquired. Among the acquired B-scans, the one with the thinnest foveal thickness, as determined by the Spectralis OCT software, was selected and imported into the ImageJ software as a “.tiff image” . A custoHRS were counted in the ROI of each processed image, after 2× image magnification, by two independent, masked investigators. HRS were defined as isolated, punctiform (≤30 µm), and moderately reflective  spots with no back shadowing . They weUnit of analysis was the eye. If both eyes were eligible, one eye was randomly chosen for the analysis. Continuous variables were described as mean and standard deviation (SD), and were tested for normality using a Shapiro–Wilk test. Categorical variables were reported as frequency and percentage. A Mann–Whitney-Wilcoxon rank sum test was used to compare population characteristics at enrollment.The intra- and inter-rater agreement was evaluated by means of the intraclass correlation coefficient (ICC). OCT scans acquired from the first 10 enrolled subjects were used for inter-rater agreement evaluation. For intra-rater agreement assessment, OCT images from the first 5 enrolled subjects were used. In this last case, each investigator analyzed the same image 5 times, for a total of 50 measurements (25 measurements per investigator). A two-way ICC model was used for all the analyses. An ICC value less than 0.5 is indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability, and values greater than 0.90 indicate excellent reliability .An independent t-test or a Mann–Whitney–Wilcoxon rank sum test was used to compare HRS numerosity in the glaucoma and control group, according to data distribution. Comparisons were performed for each investigator and for the average counts of the two investigators. A sample size of 28 subjects per group was calculated, in order to achieve a 80% power to detect a difference between groups of 10 HRS, with a pooled standard deviation of 13 and an α-error of 0.05.IOP, age and VF mean deviation (MD) and pattern standard deviation (PSD) were correlated to the average HRS numerosity  in the entire study group. In this analysis, a Pearson correlation test was used for normally distributed data, otherwise a Spearman’s rank correlation test was performed.Significance level was set at 0.05. All analyses were performed using an in-house software library based on the Python SciPy environment  and withp = 0.08). All enrolled subjects were Caucasian. Mean IOP for controls and glaucoma patients was 14.56 ± 2.16 mm Hg and 15.30 ± 5.02 mm Hg, respectively (p = 1.00).Thirty-four eyes of 34 healthy controls and 30 eyes of 30 POAG patients were enrolled . Mean agp < 0.01, Inter-rater agreement for HRS counting was good to excellent , while intra-rater agreement was good to excellent for the first investigator  and moderate to excellent for the second investigator . HRS were detected in 100% of the eyes. A greater number of HRS were detected in the OCT images from POAG eyes, when compared with healthy controls  and IOP  were not correlated to HRS numerosity.Significant correlations between HRS number and MD  [Although the exact nature of HRS remains unknown, the hypothesis that they may represent, at least in some eyes, activated and aggregated microglial cells is consistent. HRS have been described, both in the early stages of DR  and imme = 0.01) . These rSeveral histopathological and animal model studies have suggested a link between neuroinflammation and glaucoma,  being glThe finding of an increased number of HRS in the central retina of POAG patients, when compared to controls, supports the hypothesis that HRS may represent, in these eyes, foci of activated microglia. HRS were counted at the level of the inner retina, i.e., between the internal limiting membrane and the outer plexiform layer, because these retinal strata, comprising the ganglionar cell layer and the retinal nerve fiber layer, are the most affected in the glaucomatous disease . IOP injSignificant correlations were found between the number of HRS and the MD and PSD value. More specifically, the HRS number increased with the decrease of the MD value, and with the increase of the PSD value. According to these results, more damaged VF tests were associated with a higher number of HRS. This is an interesting finding, suggesting a possible correlation between structure and function, with functional damage increasing along with retinal neuroinflammation. Although this hypothesis is intriguing, dispersion of data in our analysis does not allow us to draw definitive conclusions on the topic, and studies with bigger sample size are required. In the case where these results would be confirmed, HRS may represent an in vivo biomarker of the glaucomatous disease, disclosing several possibilities, including an early pre-functional diagnosis, the evaluation of the state of the disease, and the evaluation of its response to different treatments.In the present study, the number of HRS was generally higher than previously reported, both in healthy controls  and in pThe study has certain limitations. Indeed, the ability of different OCT instruments to detect HRS may vary, and the present results might not apply to all commercially available OCT platforms. Moreover, even if counting HRS within a given OCT scan is straightforward, rater variability may obviously affect the results. Future technical developments in OCT imaging may allow for the automatic determination of HRS counts.HRS evaluation in macular OCT B-scans seems to be a promising field of research in glaucoma, and could lead to a novel OCT biomarker of inflammatory processes occurring in glaucoma patients. Further studies are needed, with larger sample sizes, in order to confirm present results and explore their potential clinical implications.


The expression of CB1 and CB2 was modified as well. Moreover, ZnONPs elicited an increase in blood pressure. In conclusion, long-time oral administration of ZnONPs induce dyslipidemia and atherosclerosis eliciting alterations in aorta contractility, CB1 and CB2 receptors expression, and an increase in blood pressure in healthy rats.ZnO nanoparticles (ZnONPs) have been shown to have therapeutic potential in some diseases such as diabetes and cancer. However, concentration-dependent adverse effects have also been reported. Studies which evaluate the effects of ZnONPs on the cardiovascular system are scarce. This study aimed to evaluate the cardiovascular effects of a low dose of ZnONPs administered chronically in healthy rats. Changes in dyslipidemia biomarkers, blood pressure, aortic wall structure, vascular contractility, and expression of cannabinoid receptors in the aorta wall were evaluated. Healthy rats were divided into two groups: control or treated . The treated rats received an oral dose of 10 mg/kg/day. The results showed that treatment with ZnONPs induced dyslipidemia from the first month, increasing atherosclerosis risk, which was confirmed by presence of atherosclerotic alterations revealed by aorta histological analysis. In in vitro assays, ZnONPs modified the aorta contractile activity in response to the activation of cannabinoid receptors (CB Zinc oxide nanoparticles (ZnONPs) are being studied widely due to their multiple applications. Previous works on biological systems show that ZnONPs have antibacterial, antifungal, antiviral, anticancer, and antidiabetic activity. In the field of engineering, it has been reported that ZnONPs are useful in solar cells, gas sensors, chemical sensors, biosensors, and photodetectors . The potIn this context, recent studies have evaluated the effects of ZnONPs on the cardiovascular system reporting interesting observations ,14. Firs1 and CB2 cannabinoid receptors in the aorta wall.The lack of knowledge of the ZnONPs’ effects on the cardiovascular system, as well as the discrepancies in the risk of generating atherosclerosis, made us propose a study to evaluate the effects of a low dose of ZnONPs administered chronically on blood pressure, structure of the aortic wall, dyslipidemia biomarkers, and vascular contractility. On the other hand, pathophysiological studies carried out to better understand the mechanisms involved in atherosclerosis suggest an important role of the endocannabinoid system in the progression of this disease ,16,17,18Male rats of the Wistar strain with an average weight of 310 ± 10 g were used for the study. All the animals were kept in a room with controlled temperature conditions (24 °C) and 12:12 h of light-dark cycles. During all experimental protocols they had free access to water and food. All the procedures used were approved by the bioethics committee of the University Center for Biomedical Research of the University of Colima .n = 30) and treated with ZnONPs , then each group was subdivided into three groups (n = 10 per group) corresponding to one, two, and three months of treatment.Sixty rats were randomly divided into two experimental groups: control . For the treatment, a fresh dispersion was prepared at a concentration of 5 mg/mL diluted in 0.9% sodium chloride solution. In order to have a homogeneous dispersion, the mixture was sonicated in an ultrasonic bath with pulse cycles of 30 s and 30 s of rest, and a pulse amplitude of 50%. Freshly dispersed the ZnONPs were administered intragastrically with a daily dose of 10 mg/kg for one, two, and three months, corresponding to each experimental group. The ZnONPs used in this study have a spherical shape, with an average size of 17 nm. These data were previously reported by our research group .Before measuring the blood pressure, for a week the rats were adapted to the restrain tube and acclimatized to the experimentation room. On the day of the experiment, the measurement was carried out as follows: the rat was place into the restraining tube and holders inside tube were adjusted to prevent movement of the animal. Subsequently, a volume pressure recording sensor coupled occlusion cuff was placed on the rat tail base, and measurements were made using a non-invasive Mouse and Rat Blood Pressure System . Five recordings were made with a 1-min rest between each recording, and the average of the blood pressure was calculated for each rat. This equipment used to measure blood pressure has a high reliability photoelectric sensor to detect pulsation at a room temperature of 32 °C or less, avoiding stress to the rat and alterations in blood flow due to excessive heat. The rat tail temperature was recorded during the blood pressure measurement (30 ± 1.5 °C).Blood samples were obtained by an intracardiac puncture at 30, 60, and 90 days from each experimental group, then the serum was separated by centrifugation at 3000 rpm for five min. The serum was aliquoted and stored at −80 °C until later analysis. Following the protocols recommended by the manufacturer , total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), triglycerides (TG), as well as gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) enzymes were determined in the samples.The atherogenic index was calculated from the equation: Log10 (TG/HDL-C).In each experimental group, the descending aorta was removed, placed in a Sylgard-coated Petri dish filled with oxygenated Krebs-Henseleit (SKH) solution, to remove surrounding adipose and connective tissue. A fragment of the aorta was fixed in 10% buffered formalin, embedded in paraffin, cut (5 μm sections), and stained with the hematoxylin-eosin technique for histological analysis. Another fragment of the aorta was used for the study of vascular contractility, and the immunohistochemical analysis.1 and CB2 receptor expression in the aorta wall was studied immunohistochemically followed by confocal microscopy. Cross sections (2 mm) of the aorta were fixed in 4% paraformaldehyde, embedded in paraffin, cut, place on a slide, deparaffinized, and rehydrated. Next, aorta sections were blocked  and incubated with rabbit polyclonal Anti-CB1  or rabbit polyclonal Anti-CB2  primary antibody and co-labeled with mouse monoclonal Anti-alpha smooth muscle Actin antibody  overnight. The next day, primary antibodies were removed, and the samples were incubated with secondary antibodies for 2 h ; and Alexa Fluor-568 anti-mouse, 1:50, Thermo Fisher Scientific, Waltham, MA, USA). Nuclei were counterstained with DAPI. Then a coverslip was placed using an antifade reagent . Finally, images were acquired using a confocal microscope , 3-D blind deconvolved , and subsequently analyzed with ZEN2009 (Zeiss), and Image J software .CB1 and CB2, on aorta contractility were evaluated in vitro. For these experiments, the following protocol was carried out: aortic rings approximately 2 mm wide were mounted in an isolated organ bath filled with Krebs-Henseleit solution (KHS) bubbled with carbogen . The ring was then fixed between two stainless steel wires, one of them coupled to an isometric force transducer (Radnoti) whose signal was amplified  and digitized by an analog-digital interface . The initial tension of the ring was adjusted to 2 g and stabilized for 60 min. Then a contracture was generated with phenylephrine (1 μM) reaching its maximum response after approximately 15 min. At this point, the effect of the agonists ACPA 30 μM (selective for CB1 receptor) or HU308 10 μM (selective for CB2 receptor) on tension was evaluated. The tension records were acquired and analyzed with Axoscope and Clampfit software , respectively.It is well documented that the cannabinoid receptors participate in the regulation of blood pressure at the vascular level. Therefore, to know if treatment with ZnONPs modifies the contractility at this level, the effects of selective agonists for both receptors, CB4, 1.2 KH2PO4, 25 NaHCO3, 2 CaCl2, added with 2 g D-Glucose, pH 7.4.The bath temperature was kept constant at 37 °C for the duration of the experiment. The composition of the KH solution was the following (in mM): 118 NaCl, 5 KCl, 1.2 MgSOp < 0.05. All the processing and statistical analyses of the data were carried out with GraphPad Prism 8 software.Data were expressed as means ± standard error. The experimental groups were analyzed using a one-way analysis of variance and the comparison between pairs of groups was performed with the Bonferroni test. The differences were considered significant with The treatment with ZnONPs did not alter total cholesterol and serum HDL-C in healthy rats in the first 2 months. However, three months later, the total cholesterol and HDL-C increased significantly to 29% and 81% respectively compared to the control group . ZnONPs The first parameter evaluated was the thickness of the aorta wall. The thickness significantly increased since the first month of the treatment and was maintained for three months as shown in The histological analysis in the slides stained with hematoxylin-eosin did not reveal differences in the first month of the treatment, foam cells and normal cholesterol drops were observed in both groups, control and treated a,b. Furt1 receptor agonist) induced 20% vasorelaxation in the aorta of untreated rats (ACPA (CBted rats a. Intereted rats a.2 receptor agonist) was evaluated on aorta contractile activity, a vasoconstrictor effect (19%) was observed in untreated rats. In ZnONPs-treated rats, the vasoconstriction effect HU308 was lower than that observed in untreated rats. The vasoconstriction was not statistically significant in the first two months. After the third month, the vasoconstriction was completely abolished, and 5% vasorelaxation was even observed  is a parameter used for the diagnosis of arterial hypertension. In this study, the oral administration of ZnONPs in healthy rats significantly increased SBP (18%) after three months in compared to the non-treated control group as shown in 1 and CB2 cannabinoid receptors in healthy rats, were evaluated.In the present study, the effects of the long-term oral administration of ZnONPs (10 mg/kg) on lipid profile, blood pressure, vascular structure, and contractility, as well as on the expression of CBThe results of the present research showed that ZnONPs induce changes in the serum lipid profile. They mainly increase triglycerides during the first two months of the treatment and total cholesterol and HDL-C after three months . In addiWe were also interested to know if this dyslipidemia induced by ZnONPs also elicited changes in the vascular structure. Our results showed that aorta wall thickness increased , an obse1 receptor, with agonists such as anandamide, induces vasorelaxation [1 receptor decreases the atherosclerosis risk while activation of the CB2 receptor decreases the progression of the atherosclerosis acting as a cardioprotective agent [1 receptor expression has been associated with vascular smooth muscle cell proliferation and atherosclerosis [1 receptor agonist, has been reported to induce aortic vasorelaxation in previous studies [Ca1.1) and blocking of the calcium channel, voltage-dependent, L type, alpha 1C subunit (Cav1.2) [1 receptors expression induced by ZnONPs , and phospholipase C (PLC) way [2 receptors shown in this study  . It has (Cav1.2) , and thi(Cav1.2) , which m(Cav1.2) . The aboy ZnONPs . In the bolished b. LittlePLC) way . These mis study b could b1 receptors expression and decreased CB2 receptor expression in the aorta wall (1 receptor as atherogenic and the CB2 receptor as atheroprotective [1 receptor and decreased CB2 receptor with the development of atherosclerosis. However, future studies are needed to elucidate the molecular signaling mechanism by which increased expression of the CB1 receptor induces atherosclerosis.ZnONPs increased CBrta wall . At presotective ,18,42,43Finally, the current study shows that ZnONPs induced an increase in the systolic blood pressure in healthy rats. To our knowledge, it is the first report of this effect. Some studies have analyzed the effect of ZnONPs on cardiovascular function but not on blood pressure ,51,52,531 and CB2 receptor expression, vascular contractility, and increased blood pressure. ZnONPs-induced atherosclerosis is associated with increased expression of the CB1 receptor and decreased expression of the CB2 receptor in the aorta wall.Chronic administration of ZnO nanoparticles by oral route induced dyslipidemia and atherosclerotic lesions, which was accompanied by alterations at the structural level, CB


The tumor microenvironment plays an important role in tumor development and metastasis. Collagens are major components of the extracellular matrix and can influence tumor development and metastasis by activating discoidin domain receptors (DDRs). This work shows the different roles of DDRs in various cancers and highlights the complexity of anti-DDR therapies in cancer treatment.The tumor microenvironment is a complex structure composed of the extracellular matrix (ECM) and nontumoral cells (notably cancer-associated fibroblasts (CAFs) and immune cells). Collagens are the main components of the ECM and they are extensively remodeled during tumor progression. Some collagens are ligands for the discoidin domain receptor tyrosine kinases, DDR1 and DDR2. DDRs are involved in different stages of tumor development and metastasis formation. In this review, we present the different roles of DDRs in these processes and discuss controversial findings. We conclude by describing emerging DDR inhibitory strategies, which could be used as new alternatives for the treatment of patients. The development of tumors, particularly those of epithelial origin that lead to carcinoma a,b, begiTo grow further, the tumor cell mass attracts cells of different types such as endothelial, immune, and fibroblastic cells, together forming the tumor stroma or tumor microenvironment TME, a 1]. At. At1]. AThe multistep metastatic cascade was established in 2003 by Fidler . The firSubsequently, tumor cells arrest in the vasculature of distant organs and extravasate b. In theThe ECM, one of the noncellular components of the TME, is composed of proteins, glycoproteins, proteoglycans, and polysaccharides, and it can be divided into the basement membrane and interstitial matrix. Epithelial cells are surrounded by the basement membrane, which is mainly composed of laminins, type IV collagen, nidogen, and heparan sulfate proteoglycans. The basement membrane separates the epithelial cells from the interstitial matrix. The latter is composed of collagens, elastin, proteoglycans, fibronectin, and other proteins. As a whole, the ECM forms an interconnected network. During tumor development, the ECM is continuously remodeled, with new synthesis and proteolytic degradation of the matrix components . CollageIn most cancers, e.g., colorectal or breast cancer, high collagen expression is associated with a poor prognosis. However, in some cancers, collagens may play an important role in limiting tumor cell activation or in constituting an obstacle to tumor growth . In addiDictyostelium discoideum, a discoidin-like domain, and an extracellular juxta-membrane domain (EJXM). The transmembrane domain is followed by an intracellular juxta-membrane domain (IJXM) and by the tyrosine kinase domain (TKD). DDR1 and DDR2 are encoded by single genes present in chromosome 6 (6p21.33) and 1 (1q23.3), respectively. Alternative splicing results in DDR1 isoforms, a, b, c, d, and e (DDRs are a family of tyrosine kinase receptors (TKRs) with two members, DDR1 and DDR2. DDRs share an extracellular domain similar to the discoidin I lectin of the amoeba d, and e . DDR1b ad, and e  12]..DictyostBoth receptors bind to fibrillar collagens with certain ligand specificities; DDR1 preferentially binds to collagen I–V and VIII while DDR2 binds to collagen I–III, V, and X . In addiSeveral tyrosine residues are phosphorylated, notably Tyr513 and Tyr792, 796, and 797 within a clustering DDR1b, allowing the recruitment of various adaptor proteins involved in signal transduction . RecentlNevertheless, DDRs can induce intracellular signaling independent of tyrosine kinase activity or of collagen binding. The formation of linear invadosomes is mediated by collagen binding to DDR1 and activation of the Cdc42-GEF (guanine nucleotide-exchange factor) Tuba, and it is independent of tyrosine kinase activity . The invThe regulation of DDR expression is not well understood. Hypoxia is a positive regulator of DDR1 and DDR2 expression in nontumor cells, such as mesenchymal stem cells and smooth muscle cells ,28, and DDR1 activity may be regulated by a shedding mechanism. Collagens are able to activate DDR1 and some batimastat-sensitive proteinases. In turn, active proteinases, such as MT1-MMP-1, MT2-MMP, MT3-MMP , and a disintegrin and metalloproteinase (ADAM) 10 cleave DDR1 at EJXM, leaving a 62 kDa intracellular membrane anchored protein. This cleavage is responsible for inhibiting the tyrosine kinase activity of DDR1, but nothing is known about the function of the extracellular part of DDR1 ,47,48.In this review, we focus primarily on the involvement of DDRs in carcinoma development and metastasis. We discuss the potential roles of these receptors in certain stages of metastasis.The transformation of a normal cell into a cancer cell involves different mechanisms such as gene activation/inactivation and chromosomal abnormalities. DDR1 is not important for tumor initiation, but it is critical in early tumor development and progression in KRAS -driven lung adenocarcinoma  Figure a,b. DDR1−/− mice have significantly fewer Ki-67+ proliferative cells . D. D81]. DIn lung cancer, DDR1 inhibition decreases the activity of MMP2 and MMP9 . ModulatLike DDR1, DDR2 is involved in the modulation of MMP expression in ovarian cancer where it regulates the expression of MMP1–3, 7, and 13 mRNAs and the activity of MMP2 and MT1-MMP . In humaBasement membrane degradation is mediated by the formation of specialized structures called invadosomes which degrade the basement membrane while maintaining cell-cell contacts and tissue integrity . The invDDR2 is required to elaborate linear invadosomes in endothelial cells and to facilitate matrix degradation in association with VEGF , but it is not known if DDR2 plays the same role in cancer cells . Table 2After basement membrane degradation, cells encounter collagen I in the interstitial matrix a. AligneCIP1 decreases [The structure of collagen I can be impacted by aging, affecting many biological processes. DDR1 is very sensitive to these changes and, consequently, the regulation of proliferation and apoptosis is altered. For instance, the proteolytic degradation of collagen I by MT1-MMP, which increases with aging, was shown to decrease DDR1 activation, tumor growth, and inhibition of apoptosis . This efecreases .DDR2 expressed by cells of the TME is also involved in collagen remodeling.Inhibition of DDR2 in CAFs or in mesenchymal stem cells impacts their mechanotransduction function, disturbs collagen fiber organization, and decreases matrix stiffness and TACS-3 signature, leading to inhibition of breast tumor cell invasion ,99.EMT is a critical process involved in cancer development and progression. Depending on the context, this mechanism can lead epithelial cells to undergo multiple intermediate steps accompanied by physiological and morphological changes, transforming them in extreme cases into mesenchymal cells. EMT can be reversed by an event called mesenchymal-to-epithelial transition (MET). Both transitions are regulated by the induction or repression of transcription factors such as Zeb1/2, Snail1/2, and Twist among others, as well as the modulation of the expression of epithelial (E-cadherin) and mesenchymal  markers . DDRs haSome studies highlighted that DDR1 can induce EMT in vitro. For instance, in prostate cancer, DDR1 activates Pyk2 and MKK7 (Mitogen-activated protein kinase kinase 7), resulting in increased expression of the mesenchymal markers vimentin and N-cadherin and decreased expression of the epithelial marker E-cadherin . In gast−/− and MMTV-PyMT mice revealed that a loss of DDR1 expression increases the level of vimentin in the primary tumor while E-cadherin expression decreases. In the absence of DDR1, tumor cells exhibit a basal phenotype leading to enhanced invasion and are associated with the development of breast cancers of poor prognosis [Conversely, several studies have shown that DDR1 expression is decreased during EMT. In breast cancer, a negative correlation between DDR1 and Zeb1 was found in carcinoma tissues. In the tumor, H-Ras is able to induce EMT by increasing Zeb1 and decreasing miR-200c expression. Zeb1 leads to suppression of E-cadherin expression and a reduction in DDR1 expression . This nerognosis . In the rognosis . This norognosis .The role of DDR2 in EMT activation is less controversial. An association between DDR2 and Snail1 has been revealed in several studies on breast cancer ,90,98, oAlthough a link has been established between DDRs and some factors modulating the EMT process, especially in vitro where a few signaling pathways have started to emerge, the mechanisms involved need to be further elucidated in vivo. DDRs have been extensively studied for their impact on migration and invasion. There are two main mechanisms of migration: cells moving individually  or collectively in a cohesive multicellular unit (collective migration). Migration can be influenced by cytoskeletal organization, remodeling of the surrounding matrix by migrating cells, and cell–matrix interaction and force generation . AdhesioDDRs are involved in migration and invasion processes as shown in numerous in vitro studies.DDR1 modulates the organization of the cytoskeleton and, consequently, has an impact on cell migration. In squamous cell carcinoma, DDR1 is localized at cell–cell contacts in association with E-cadherin and is able to regulate cytoskeletal organization, particularly actomyosin organization, and collective migration. The DDR1/E-cadherin/Par3/Par6 complex controls the localization of RhoE which antagonizes Rho/ROCK, modulating actomyosin contractility at cell–cell contacts. At these sites, actomyosin forces are weaker, allowing coordinated movement of the clustered cells . In oralDDR2 has also been shown to promote migration and invasion in many cancers. Inhibition of DDR2 expression in gastric cancer  or hepatAlthough, in most cases, DDR1 and DDR2 have been shown to promote migration and invasion, few studies have shown their involvement in inhibiting both processes. DARPP-32  binds to the IJXM domain of DDR1 and decreases collagen-stimulated invasion of breast cancer cells .Very few studies have analyzed the impact of DDRs on migration and invasion in vivo; instead, they focused on the establishment of metastasis as in gastric cancer . PCA-1 iThere are two different routes for tumor dissemination: blood vessels or lymphatic vessels b. AngiogDDR1, in renal cell carcinoma and in gastric cancer cells, induces the secretion of angiogenic factors involved in endothelial cell tube formation in vitro ,119. In DDR1 is also important for lymphangiogenesis. Gastric tumors develop fewer lymphatic vessels if DDR1 expression is inhibited  and lympslie mouse model carrying a deletion in the DDR2 gene. When melanoma cells are injected, tumor development is impacted with decreased tumor angiogenesis and increased tumor necrosis; nevertheless, the remaining vasculature is mature and functional. In these tumors, proangiogenic factors or receptors such as VEGFR2, Ang-2 (Angiopoietin-2) or MMP9 are decreased, and antiangiogenic factors such as Ang-1 are increased [In contrast to endothelial cells, in colon carcinoma, DDR2 is weakly expressed at the surface of normal endothelial cells; however, overexpression of the receptor enhances angiogenesis in vitro and in vivo. After injection of VEGF-containing Matrigel, angiogenesis is impacted in the ncreased . In hepancreased .Nothing is known about the role of DDRs in the mechanism of intravasation.No evidence for a role of DDRs in tumor cell survival in the bloodstream or extravasation has been established a–c. NeveRecently, DDR1 expressed by the liver metastatic niche was found to be important for micrometastasis implantation. DDR1 siRNA-injected mice have fewer hepatic stellate cells (HSCs), differentiated myofibroblasts, and angiogenesis ). Consequently, less collagen is secreted into the niche and the number of micrometastases is reduced .−/− mice showed an increase in micrometastasis foci compared to a DDR2+/+ mice. This result can be explained by increased HSC differentiation into myofibroblasts and increased LSEC activation and angiogenesis in DDR2−/− mice. Furthermore, tumor cell adhesion to LSECs from DDR2−/− mice is increased if these cells are exposed to tumor cell supernatants, suggesting that this may cause an increase in tumor cell extravasation in vivo. Lastly, the liver tumor niche in DDR2−/− mice promotes tumor cell colonization (see below) [slie mice showed a reduction in the number of lung metastases [The importance of DDR2 in the metastatic niche depends of the metastatic tissue. In a model of liver metastasis, intrasplenic injection of colon cancer cells into DDR2e below) . In conttastases .However, different types of collagen are found at higher levels in the serum from patients with cancer, and serum collagen IV is a biomarker for peritoneal dissemination of gastric cancer . In breaThe involvement of DDRs in tumor cell extravasation is still poorly documented.Sox2. This mechanism of DDR1-induced metastatic colonization is independent of its tyrosine kinase activity. The formation of large DDR1 clusters is crucial for this mechanism, because collagen IV, which induces only small-size clusters, is not involved in the colonization process. Inhibition of TM4SF1 alters not only the metastases of breast tumors to the lungs, but also to the brain and bone. However, the involvement of DDR1 in brain and bone metastasis has not been assessed [The first demonstration of DDR1 involvement in tumor colonization c was eleassessed . Recentlassessed , but it assessed . In contassessed .−/− mice develop a liver niche favorable for micrometastasis development, as well as for tumor colonization. DDR2−/− HSCs exposed to colon cancer cell supernatants overexpress genes  involved in immune suppression, angiogenesis, and cancer cell growth. Therefore, the number of proliferating tumor cells is increased in liver metastases if DDR2 is not expressed in the liver [DDR2 has also been found to play a role in metastasis formation; however, again, it is not clear which step(s) of the metastatic process is (are) involved. In addition, DDR2 expression in tumor cells and in the metastatic niche may influence tumor metastatic colonization. In lung metastases of breast tumor cells, DDR2 expression by tumor cells is important for metastasis development, but its expression in the metastatic niche is dispensable . In conthe liver .The association or crosstalk of DDR1 with other transmembrane proteins results in distinct outcomes. Through a collagen- and tyrosine kinase-independent mechanism, DDR1 binding to E-cadherin increases the strength of cell–cell interactions. In breast cancer, some studies showed crosstalk between DDR1 and the insulin and IGF receptors, IR-A and IGF-1R (Insulin like Growth Factor 1 Receptor) . IGF-1 aLastly, DDR1 can associate with TM4SF1 to induce metastatic tumor colonization as described above . No crosDDRs are upregulated in many cancers and appear to be promising biomarkers; thus, their inhibition an attractive strategy. DDR1 and DDR2 can be targeted by tyrosine kinase inhibitors such as dasatinib, nilotinib, and imatinib . These i50  values of 6.8 and 7.0 nM, respectively [50  values of 86 nM and 9 nM, respectively [In recent years, several DDR1-specific inhibitors have been developed. In 2013, the pyrazolo pyrimidin benzamide 7rh and 7rj selective DDR1 inhibitors were discovered. They can inhibit the enzyme activity with ICectively . In vitrectively , gastricectively , and lunectively  cancers.ectively ,146. DDRectively . DDR1-INectively . Recentlectively . DDR1 inectively . Furtherectively .Fewer compounds are known that can specifically and selectively inhibit DDR2. Actinomycin D, the potent mammalian transcription inhibitor, can impair the interaction between DDR2 and collagen, preventing DDR2 activation . CompounToday, the difficulty with patient management lies in the tumor heterogeneity that does not allow a universal treatment, as well as in the lack of effective treatment, which leads to the appearance of resistance and cancer relapse. Some researchers have highlighted the role of DDR1 in treatment resistance in lung , breast + T-cell counts in bladder, breast, colon, and sarcoma cancers. Melanoma metastasis in mouse lungs is largely inhibited if mice receive both treatments in combination [DDR2 is also involved in treatment resistance. DDR2 has been identified as a critical target for improved response to anti-PD1 (Programmed death-ligand 1) immunotherapy. The combination of anti-PD1 therapy and DDR2 inhibition with dasatinib shows a reduction in tumor burden and results in an increase in CD8bination . Despitebination . On the bination . No specDDRs are involved in different stages of tumor development and metastasis. No evidence has been observed for their involvement in tumor initiation, but DDR1 and DDR2 play a role in tumor cell proliferation c and morIn almost all stages of metastasis, apparently contradictory results have been obtained. Different hypotheses may explain the contrasted effects of DDR1 and DDR2 manipulation on proliferation, EMT, MMP induction, migration, invasion, and metastasis. First, DDR1 activity may depend on the type of cell and of the presence or absence of an interacting protein (such as DARPP-32) . Second,Most of the late metastasis cascade  has not been studied individually but as a whole after injection of tumor cells into the bloodstream. It will be interesting to clarify in which step(s) DDRs are involved.There are not many studies that focused on the analysis of the impact of DDR1 and DDR2 within the same cancer, although, very often, both receptors are expressed. Further studies analyzing the relationship between the two receptors in tumor development are needed.DDR inhibitors used in cancer treatment, such as dasatinib or nilotinib, are not specific DDR inhibitors. Further in vivo analysis of cancer development during treatment using specific DDR1 or DDR2 inhibitors, such as 7rh, 2.45, or WRG-28, in different cancers are needed.DDRs are receptors for ECM collagens. They are expressed at the extracellular membrane of tumor cells and of many cells of the TME such as CAFs and immune cells. In many cancers, DDR1 or DDR2 are overexpressed, suggesting a role for DDRs in tumor development and metastasis. They are involved in the proliferation and migration of tumor cells and in the formation of micro- and macrometastases. However, the impact of DDRs in tumor development or metastasis seems to be cancer-dependent and may be explained by the DDR1 isoform expressed or by interaction with other receptors. Further experiments are needed to clarify the activities of DDRs in different cancers. These studies will be facilitated by the development of specific DDR inhibitors that are being characterized in vitro and in vivo.


P < 0.05). The instantaneous elastic modulus, delay elastic modulus, and viscosity coefficient of the two paddy soils (no tillage and plough tillage soils) decreased with the increase of moisture content. However, the variation rules of relaxation time and delay viscosity coefficient with moisture content differed between these two paddy soils. Specifically, the strain rate of the two paddy soils decreased as moisture content decreased, where the total strain combines elastic strain, viscous strain, and viscoelastic strain. The initial strain rate and steady strain rate of the plough tillage paddy soils were lower than that of the no tillage paddy soils. The established creep model equation could be used to obtain viscoelastic rheological parameters of paddy soil in a wide range. The fitting equations between rheological parameters and moisture content were introduced into Burgers model, and the coupling equations between creep deformation and moisture content and time were derived, which could be used to predict the creep properties and deformation behavior of paddy soil in a certain range of no tillage and ploughed field. Overall, this study has a certain theoretical significance for the development and improvement of paddy soil rheology theory, and can also provide theoretical basis and technical support for the research of agricultural machinery design optimization, field water, soil conservation, soil tillage and compaction related simulation analysis in the middle and lower reaches of the Yangtze River.The rheological properties parameters of paddy soil affect the interaction between the tillage tools and soil, thus influencing the operation quality and power consumption. In order to study the effects of tillage methods and moisture content on the rheological properties parameters of paddy soil in the middle and lower reaches of the Yangtze River, uniaxial compression creep tests of paddy soils with four moisture contents under no tillage  and plough tillage  were carried out using a TMS-PRO texture analyzer. The creep properties curves obtained from the tests, and the rheological constitutive equation of paddy soil under compression was established by Burgers viscoelastic model. Respectively, the quantitative change rules of creep properties of paddy soil with different moisture contents under different tillage methods and the correlation between these parameters were explored. The results showed that the moisture content under the three-year plough tillage and no tillage methods had significant influence on the rheological properties parameters of paddy soil ( Soil is a three-phase porous mixture composed of solid particles, liquid water, and air –3. StudyAt present, studies on the creep properties of agricultural materials mainly focus on fluidity, rheological models, and plant materials, with scarce attention on the rheological properties parameters in farmland soil. For example, Tabatabaeefar  reportedCreep model, as an important part of rheological theory, is widely used in agricultural engineering. It mainly includes mechanical damage of fruit, creep model construction of agricultural products, mechanical properties of seeds and rheological properties of flour. Ma et al.  carried Altering tillage methods and moisture content significantly affects the creep properties of soil, thus affecting the interaction mode and stress state between tillage tools and soil –23. At pBased on the above research progress, there remain few studies on the rheological properties parameters of farmland soil with creep model, especially the lack of systematic and reliable theoretical calculation models for soil creep properties. Understanding the soil creep properties is largely significant to guide the research and development of agronomy and tillage machinery. In the early stage of our research, we studied the physical composition, physical-chemical properties, and plastic-liquid limit index of paddy soil of the paddy-upland rotation area in the middle and lower of the Yangtze River , 39. In The experiment was conducted from October 2017 to September 2020 in the modern Agricultural Science and Technology Experimental Base of Huazhong Agricultural University . The base located in Hongshan District, Wuhan City, Hubei province, is characterized by a subtropical moist monsoon climate with seasonal changes in temperature, annual average temperature of 15.8–17.5°C, annual average rainfall of 1000–1500 mm that more concentrated in 6–8 months, annual frost-free period of 211–272 days, and common annual sunshine of 1810–2100 h . The samThe adopted test was a split plot design, and the employed tillage method was divided into three years of no tillage (NT) and three-year plough tillage (PT). The secondary plot was for the moisture content. Considering the range of moisture content in the cultivation period and the convenience of soil sample preparation, the days of drying field was set 12 days. By varying the days of drying field to changes in the moisture content, each main area was characterized by 4 different moisture contents to make a total of 8 treatments. The four treatments of no tillage field were defined as NTT, NTS, NTN and NTV, corresponding to 3, 6, 9 and 12 days of drying field. Respectively, four treatments of ploughed field were also defined according to the above method, namely PTT, PTS, PTN and PTV.2 each. The field had been ploughed for 3 consecutive years with no tillage. On this basis, the zone grouping test was carried out, with each zone covering 20 m2 and the groups within the field randomly arranged. The experiment was set to be repeated 5 times. No tillage paddy field was cultivated in semi-drought mode. The field was ditched and ridged according to the direction of water flow, with a ridge width of 80 cm, ditch width of 30 cm, and depth of 30 cm. Water was irrigated in the trench, and the rice was planted on the water level or surface on both sides of the ridge top, with 6 rows planted in each ridge. A conventional transplanter was used for transplanting rice paddy fields in the spring, and topdressing was applied in the earing stage of rice. After the rice harvesting, the soil was ploughed with a share plow (20–25 cm). The straw was turned over and buried in the soil. Then, the surface was exposed, passed through the leisure period, and rotated 3 times before sowing.The effects of moisture content and tillage on the creep properties of paddy soil were studied in two adjacent test plots with an area of 800 mA five-point sampling method was used to collect soil samples in the middle rice harvest field of the experimental area . During The TMS-PRO texture analyzer (American FTC company) was used as the main test equipment, which provided a maximum test force of 1000 N and accuracy of ±1%. Other auxiliary tools include the TJSD-750 soil penetrometer/compaction meter , Vernier caliper, ring-knife, tape measure, and XMA-600 electric blast drying box .Before the test, a pre-experiment was conducted to explore the loads of NT and PT paddy soils under different moisture contents without yield and disintegration. During the test, the sample was fixed onto the test bench. The disk head moved downward at a movement rate of 20 mm/min, and the predetermined load was 60 N, which reached the predetermined load and retained pressure of 900 s. After 900 s, the disk head returned to the initial position automatically, and the strain and time relation were measured. The indoor temperature and humidity were determined to be 25.4 ± 1.5°C and 65.3 ± 4.8%, respectively .R2) and root mean squared error (RMSE) were calculated by residual analysis, and WLS (Weighted Least Squares) was adopted to evaluate the performance of different models in fitting the creep properties with moisture content. One-way ANOVA was used with moisture content as the only factor. Differences between the treatments were assessed using their variance and a least significant difference (LSD) multiple comparison test at an α = 0.05 level of significance to determine if significant differences existed among the rheological parameters in different moisture content.Analysis of variance (ANOVA) and correlation analysis were performed using the SPSS statistical package  to test the effects of soil moisture content on creep properties. Descriptive statistics, including the mean, standard deviation (SD) and coefficient of variation (CV), were analyzed. Coefficients of the determination . The data in the According to formula , MATLAB E2 and delayed viscosity coefficient η2. For NT paddy soil, the viscosity coefficient, delayed viscosity coefficient, and relaxation time ranged 577.616–3426.444 MPa·s, 34.237–129.393 MPa·s, and 58.589–103.288 s with average values of 2155.842 MPa·s, 110.271 MPa·s, and 82.463 s, respectively. In comparison, PT paddy soil exhibited a viscosity coefficient of 3135.026–9414.022 MPa·s (average of 7255.669 MPa·s), relaxation time of 57.092–71.572 s (average of 59.212 s), and delayed viscosity coefficient of 137.678–1228.459 MPa·s (average of 515.460 MPa·s). The above analysis shows that in the internal structure of PT paddy soil and NT paddy soil, the elastic deformation resistance of the spring element E1 is less than that of spring element E2 in the Kelvin model. Also, the viscous resistance to deformation of the viscous element η1 is stronger than the delayed viscous element η2 in the Kelvin model. Moreover, the fluidity of the internal structure of PT paddy soil is weaker than that of NT soil.Instantaneous elastic deformation will occur in paddy soil under a load, for which the instantaneous elastic modulus and delay elastic modulus represent the elastic mechanical properties of paddy soil. For NT paddy soil, the instantaneous elastic modulus and delay elastic modulus ranged 0.189–1.075 MPa and 0.333–2.200 MPa with average values of 0.712 and of 1.427 MPa, respectively. For PT paddy soil, the instantaneous elastic modulus and delay elastic modulus ranged 0.418–1.642 MPa and 2.411 to 17.164 MPa with average values of 0.850 MPa and 8.110 MPa, respectively. The viscosity coefficient characterizes the fluidity of paddy soil, where a larger value indicates a stronger anti-deformation viscosity resistance and poor fluidity. Relaxation time, also known as elastic lag time, is the result of the comprehensive action of the delayed elastic modulus The mean values of rheological mechanical parameters of the two paddy soils were compared within 12 days. The instantaneous elastic modulus, delay elastic modulus, viscosity coefficient, and delayed viscosity coefficient of NT paddy soil were lower than those of PT paddy soil. The relaxation time of NT paddy soil was higher than that of PT paddy soil. From the aspect of moisture content, the instantaneous elastic modulus, viscosity coefficient, and delay elastic modulus of the two paddy soils decreased as moisture content increased, and the maximum was obtained by NTV and PTV treatments. The variation trend of relaxation time and delayed viscosity coefficient of the two paddy soils were different with moisture content. The maximum value of relaxation time was due to the NTT, PTV treatment, while the maximum delayed viscosity coefficient was attributed to the NTV, PTV treatment.P < 0.01) and had a significant influence on the relaxation time of NT (P < 0.05). Moisture content also demonstrated a significant effect on the instantaneous modulus of elasticity, delay elasticity modulus, viscosity coefficient, delayed viscosity coefficient, and relaxation time of PT paddy soil (P < 0.01).ANOVA was performed for NT and PT paddy soils with different moisture contents . The moiTo construct the model between moisture content and rheological mechanical parameters, the most basic mathematical and five most widely-used functional relationships were selected, i.e. polynomial, logarithmic, exponential, power function, and linear models. A numerical analysis method and SPSS Statistics 21.0 software were used to explore the quantitative change relationship between the moisture content and rheological parameters of paddy soil. The polynomial, logarithmic model, exponential, power function, and linear relationships between moisture content and rheological parameters of paddy soil were obtained by fitting, as shown in F value of the optimal fitting model was greater than the critical value of F0.05. At the same time, the P value of the model was less than 0.05, which indicated that it passed the significance test of the regression model. Comprehensive analysis of the above test results revealed differences between the optimal fitting models of the rheological parameters and moisture content of NT and PT paddy soils.The large standard deviation of fitting parameters in E1, viscosity coefficient η1, and delay elastic modulus E2 were very significantly positive correlated (P < 0.01). The instant elastic modulus E1 and delay viscosity coefficient η2 were also significantly positive correlated (P < 0.05). For PT paddy soil, the instantaneous elastic modulus E1 was very significantly positively correlated with significant delay elastic modulus E2, relaxation time Tr, and delay viscosity coefficient η2 (P < 0.01). The results suggested that when the instantaneous elastic modulus E1 of paddy soil was larger, the delay elastic modulus E2 was larger, and the stable creep of paddy soil was faster. In other words, a greater instantaneous elastic modulus E1 of NT paddy soil means a greater viscosity coefficient η1 and delay viscosity coefficient η2, reflecting that viscosity increases with a greater elasticity and worse internal mobility of paddy soil. Moreover, the viscosity coefficient η1 of NT paddy soil was very significantly positively correlated with the delay elastic modulus E2 (P < 0.01) and negatively correlated with relaxation time Tr (P < 0.05). The results showed that the stronger viscosity of NT paddy soil, the longer time to reach stable creep. For PT paddy soil, a greater instantaneous elastic modulus E1 correlated with a higher delay elastic modulus E2, relaxation time Tr, and delay viscosity coefficient η2. This reflected that with increased elasticity, the elasticity and viscosity of the Kelvin element in Burgers model were enhanced, further increasing the stable creep time. In addition, a very significant positive correlation was found between delayed elastic modulus E2 and viscosity coefficient η1, relaxation time Tr, and delayed viscosity coefficient η2 (P < 0.01). The relaxation times Tr of NT and PT paddy soil were very significantly correlated with the viscosity coefficient (η1 or η2). The bigger the viscosity coefficient η1 of NT paddy soil was, the smaller the relaxation time Tr. The greater the delay viscosity coefficient η2 of PT paddy soil was, the greater the relaxation time Tr. The above analysis indicated that there were both positive and negative correlations between the creep model parameters of paddy soil, further reflecting the differences between the creep properties of NT and PT paddy soil.For NT paddy soil, the instant elastic modulus J(t) is used to represent the creep energy and creep strain of the material under the action of unit stress, which can be expressed as:Je stands for elastic compliance; Je = 1/E1; Jv(t) represents viscosity compliance; Jv(t) = t/η1; Jve(t) represents the viscoelastic compliance; Jve(t) = [1-exp(-E2t/η2)]/E2, σ0 represents the stress on the material; and t is time of applied stress. According to the expression of creep compliance J(t), the elastic compliance Je is the instantaneous elastic deformation under the stress applied to paddy soil, which does not change with time. The coefficient of viscosity compliance Jv(t), which increases slowly and linearly with time, is the reciprocal of the coefficient viscosity η1, where the creep curve shows the creep rate of uniform creep stage of paddy soil. The viscoelastic compliance Jve(t) is influenced by the delay elastic modulus E2 and delay viscosity coefficient η2. As time increases, the viscoelastic compliance Jve(t) gradually increases, then the growth rate slows down to a fixed value. The creep curve illustrates the decelerating creep stage of paddy soil.When describing the viscoelasticity of a material in Burgers model, the creep flexibility The creep curve fitting results of NT and PT paddy soil in ε1(t), ε2(t), ε3(t), ε4(t), ε5(t), ε6(t), ε7(t), and ε8(t) correspond to NTT, NTS, NTN, NTV, PTT, PTS, PTN, and PTV treatments. By substituting the fitting model between moisture content and rheological mechanical parameters of paddy soil in Where εe(t), viscous strain εv(t), and viscoelastic strain εve(t). The proportion of each strain in the total strain was further analyzed using the following proportion:It can be seen that the total creep deformation of paddy soil consists of elastic strain The strain rate is an index that represents the rate of creep change and strain change per unit time, which can be expressed as follows:Using formula , the dervNm corresponding to NTT, NTS, NTN, and NTV were determined to be 0.062, 0.026, 0.011, and 0.016%·s-1 respectively, with steady-state creep stage rates vNn of 0.0035, 0.0009, 0.0008, and 0.0006%·s-1. The initial creep rates vPm corresponding to PTT, PTS, PTN, and PTV were 0.01517, 0.00629, 0.00576, and 0.00184%·s-1 respectively, with steady-state creep rates vPn of 0.00064, 0.000263, 0.000257, and 0.000212%·s-1. The corresponding creep rates of each treatment in the initial and steady-state stages were shown in From formula , it coulvNm is the initial creep rate (NT); vNm is the steady-state creep stage rate (NT); vPm is the initial creep rate (PT); vPN is the steady-state creep stage rate (PT).Where: The purpose of this study is to study the creep properties of paddy soil by creep tests. The rheological parameters of paddy soil were obtained by creep model. The instantaneous elastic modulus, viscosity coefficient, delay elastic modulus, relaxation time, and delay viscosity coefficient of soil are important parameters of soil properties, including fluidity, deformation, failure, and adhesion. Changes in the tillage method and moisture content will affect these creep properties, altering the action mode and stress state of tillage tools and soil, thus influencing the tillage quality of soil, action nature of tillage tools, and growth of crop roots. The effects of the tillage method and moisture content on soil creep properties and soil tillage performance are discussed in the following sections.Different tillage methods affect the physical composition and soil structure of the surface layer of paddy soil , subsequThe instantaneous elastic modulus, delay elastic modulus, and viscosity coefficient of paddy soil under each moisture content are inversely proportional to moisture content. The degree of soil deformation is related to the soil structure, pores between soils, and flow of water in the pores, which affect the composition and microstructure of soil . When thBased on the above findings, it can be concluded that the relationship between moisture content and creep properties of paddy soil is complex, especially for the relaxation time and delayed viscosity coefficient of NT paddy soil. In the 5 fitting models, the fitting determination coefficients were all less than 0.90. Therefore, it is necessary to further study the influence of mechanical parameters under the combined action of viscoelasticity and the rheological coupling mechanism among soil particles, organic matter, and water in paddy soil to advance the research on the regulation of soil tillage.Based on Burgers model, this study analyzed the significant and quantitative relationship between the rheological parameters and moisture content of paddy soil under different tillage methods in the middle and lower reaches of the Yangtze River. Correlation analysis of the above mechanical properties revealed the different viscoelasticity of the internal structure of paddy soil with different tillage methods and moisture content. Under the three-year plough tillage and no tillage methods, the total creep deformation of paddy soil with different moisture content is based on elastic strain, viscous strain, and viscoelastic strain, while the strain rate is determined by the viscoelastic strain rate and viscous strain rate. The initial strain rate and steady strain rate of PT paddy soil were found to be lower than those of NT paddy soil.This study provides an important theoretical basis for the dynamic analysis of soil in relation to the tillage machinery, soil compaction, farmland water, and soil regulation. Since soil is a kind of complex nonlinear viscoelastic plastic material, there is no mature rheological theory to explain its complex creep properties, which are influenced by numerous factors. The purpose of this study is to study the creep properties of paddy soil by creep tests. In addition to the moisture content and tillage methods mentioned in this paper, soil temperature, particle size distribution, crop root system, and trace element content are other pertinent factors of soil. Therefore, the creep properties of soil need to be further studied in combination with multidisciplinary knowledge to better understand and monitor soil for agricultural means.S1 Fig(TIF)Click here for additional data file.S2 Fig(TIF)Click here for additional data file.