Antigen presentation plays positive roles in the regenerative response to cardiac injury in zebrafish.

In contrast to adult mammals, adult zebrafish can fully regenerate injured cardiac tissue, and this regeneration process requires an adequate and tightly controlled immune response. However, which components of the immune response are required during regeneration is unclear. Here, we report positive roles for the antigen presentation-adaptive immunity axis during zebrafish cardiac regeneration. We find that following the initial innate immune response, activated endocardial cells (EdCs), as well as immune cells, start expressing antigen presentation genes. We also observe that T helper cells, a.k.a. Cd4+ T cells, lie in close physical proximity to these antigen-presenting EdCs. We targeted Major Histocompatibility Complex (MHC) class II antigen presentation by generating cd74a; cd74b mutants, which display a defective immune response. In these mutants, Cd4+ T cells and activated EdCs fail to efficiently populate the injured tissue and EdC proliferation is significantly decreased. cd74a; cd74b mutants exhibit additional defects in cardiac regeneration including reduced cardiomyocyte dedifferentiation and proliferation. Notably, Cd74 also becomes activated in neonatal mouse EdCs following cardiac injury. Altogether, these findings point to positive roles for antigen presentation during cardiac regeneration, potentially involving interactions between activated EdCs, classical antigen-presenting cells, and Cd4+ T cells.

Evidence for TET-mediated DNA demethylation as an epigenetic alteration in cumulus granulosa cells of women with polycystic ovary syndrome.

Peripheral and tissue-specific alterations in global DNA methylation (5-methylcytosine (5mC)) and DNA hydroxymethylation (5-hydroxymethylcytosine (5hmC)) profiles have been identified as both biomarkers for disease prediction and as hallmarks of dysregulated localized gene networks. Global and gene-specific epigenetic alterations in the 5mC profiles have shown widespread implications in the etiology of polycystic ovary syndrome (PCOS). However, there has been no study in PCOS that integrates the quantification of 5mC and 5hmC signatures alongside the expression levels of DNA methylating and demethylating enzymes as respective indicators of methylation and demethylation pathways. Having previously shown that the 5mC signatures are not substantially altered in PCOS, we assessed the global 5hmC levels in peripheral blood leukocytes and cumulus granulosa cells (CGCs) of 40 controls and 40 women with PCOS. This analysis revealed higher 5hmC levels in CGCs of PCOS women, indicating a more dominant demethylation pathway. Furthermore, we assessed the transcript and protein expression levels of DNA demethylating and methylating enzymes, i.e. ten-eleven translocation methylcytosine dioxygenases (TET1, TET2, TET3) and DNA methyltransferases (DNMT1, DNMT3A and DNMT3B), respectively, in CGCs. The relative transcript and protein expression levels of all three TETs were found to be higher in women with PCOS, and the TET mRNA expression profiles were positively correlated with 5hmC levels in CGCs. Also, all three DNMT genes showed altered transcript expression in PCOS, although only the downregulated DNMT3A transcript was correlated with decreasing 5mC levels. At the protein level, the expression of DNMT1 (maintenance methylation enzyme) was higher, while that of DNMT3A (de novo methylation enzyme) was found to be lower in PCOS compared to controls. Overall, these results indicate that DNA methylation changes in CGCs of PCOS women may arise partly due to intrinsic alterations in the transcriptional regulation of TETs and DNMT3A.

sMAdCAM: IL-6 Ratio Influences Disease Progression and Anti-Viral Responses in SARS-CoV-2 Infection.

The role of sMAdCAM, an important gut immune migratory marker, remains unexplored in COVID-19 pathogenesis considering recent studies positing the gut as a sanctuary site for SARS-CoV-2 persistence. Thus, assimilating profiles of systemic inflammatory mediators with sMAdCAM levels may provide insights into the progression of COVID-19 disease. Also, the role of these markers in governing virus specific immunity following infection remains largely unexplored. A cohort (n = 84) of SARS-C0V-2 infected individuals included a group of in-patients (n = 60) at various stages of disease progression together with convalescent individuals (n = 24) recruited between April and June 2020 from Mumbai, India. Follow-up of 35 in-patients at day 7 post diagnosis was carried out. Th1/Th2/Th17 cytokines along with soluble MAdCAM (sMAdCAM) levels in plasma were measured. Also, anti-viral humoral response as measured by rapid antibody test (IgG, IgM), Chemiluminescent Immunoassay (IgG), and antibodies binding to SARS-CoV-2 proteins were measured by Surface Plasmon Resonance (SPR) from plasma. IL-6 and sMAdCAM levels among in-patients inversely correlated with one another. When expressed as a novel integrated marker-sMIL index (sMAdCAM/IL-6 ratio)-these levels were incrementally and significantly higher in various disease states with convalescents exhibiting the highest values. Importantly, sMAdCAM levels as well as sMIL index (fold change) correlated with peak association response units of receptor binding domain and fold change in binding to spike respectively as measured by SPR. Our results highlight key systemic and gut homing parameters that need to be monitored and investigated further to optimally guide therapeutic and prophylactic interventions for COVID-19.

DNA methylome profiling of granulosa cells reveals altered methylation in genes regulating vital ovarian functions in polycystic ovary syndrome.

BACKGROUND: Women with polycystic ovary syndrome (PCOS) manifest a host of ovarian defects like impaired folliculogenesis, anovulation, and poor oocyte quality, which grossly affect their reproductive health. Addressing the putative epigenetic anomalies that tightly regulate these events is of foremost importance in this disorder. We therefore aimed to carry out DNA methylome profiling of cumulus granulosa cells and assess the methylation and transcript expression profiles of a few differentially methylated genes contributing to ovarian defects in PCOS. A total of 20 controls and 20 women with PCOS were selected from a larger cohort of women undergoing IVF, after carefully screening their sera and follicular fluids for hormonal and biochemical parameters. DNA extracted from cumulus granulosa cells of three women each, from control and PCOS groups was subjected to high-throughput, next generation bisulfite sequencing, using the Illumina HiSeq 2500® platform. Remaining samples were used for the validation of methylation status of some identified genes by pyrosequencing, and the transcript expression profiles of these genes were assessed by quantitative real-time PCR. RESULTS: In all, 6486 CpG sites representing 3840 genes associated with Wnt signaling, G protein receptor, endothelin/integrin signaling, angiogenesis, chemokine/cytokine-mediated inflammation, etc., showed differential methylation in PCOS. Hypomethylation was noted in 2977 CpGs representing 2063 genes while 2509 CpGs within 1777 genes showed hypermethylation. Methylation differences were also noted in noncoding RNAs regulating several ovarian functions that are dysregulated in PCOS. Few differentially methylated genes such as aldo-keto reductase family 1 member C3, calcium-sensing receptor, resistin, mastermind-like domain 1, growth hormone-releasing hormone receptor and tumor necrosis factor, which predominantly contribute to hyperandrogenism, premature luteolysis, and oocyte development defects, were explored as novel epigenetic candidates in mediating ovarian dysfunction. Methylation profiles of these genes matched with our NGS findings, and their transcript expression patterns correlated with the gene hypo- or hypermethylation status. CONCLUSION: Our findings suggest that the epigenetic dysregulation of genes involved in important processes associated with follicular development may contribute to ovarian defects observed in women with PCOS.

Pathomechanisms of polycystic ovary syndrome: Multidimensional approaches.

Polycystic ovary syndrome is a complex endocrine disorder affecting numerous women of reproductive age across the globe. Characterized mainly by irregular menses, hirsutism, skewed LH: FSH ratios and bulky polycystic ovaries, this multifactorial endocrinopathy results in unfavorable reproductive and metabolic sequelae, including anovulatory infertility, type 2 diabetes, metabolic syndrome and cardiovascular disease in later years. Increasing evidence has shown that the manifestation of polycystic ovary syndrome (PCOS) is attributable to a cumulative impact of altered genetic, epigenetic and protein profiles which bring about a systemic dysfunction. While genetic approaches help ascertain role of causal variants in its etiology, tissue-specific epigenetic patterns help in deciphering the auxiliary role of environmental, nutritional and behavioral factors. Proteomics is advantageous, linking both genotype and phenotype and contributing to biomarker discovery. Investigating molecular mechanism underlying PCOS is imperative in order to gain insight into the pathophysiology of PCOS and formulate novel diagnostic and treatment strategies. In this review we have summarized these three aspects, which have been successfully utilized to delineate the pathomechanisms of PCOS.

LINE1 CpG-DNA Hypomethylation in Granulosa Cells and Blood Leukocytes Is Associated With PCOS and Related Traits.

Context: Altered global DNA methylation is indicative of epigenomic instability concerning chronic diseases. Investigating its incidence and association with polycystic ovary syndrome (PCOS) is essential to understand the etiopathogenesis of this disorder. Objectives: We assessed global DNA methylation differences in peripheral blood leukocytes (PBLs) and cumulus granulosa cells (CGCs) of controls and women with PCOS; and their association with PCOS and its traits. Design, Setting, Participants, Main Outcome Measure: This study included a total of 102 controls and women with PCOS. Forty-one women undergoing controlled ovarian hyperstimulation (COH) and 61 women not undergoing COH were recruited from in vitro fertilization (IVF) and infertility clinics. DNA methylation was measured by ELISA for 5'-methyl-cytosine content and bisulfite sequencing of 5'-untranslated region (5'-UTR) of long interspersed nucleotide element-1 (LINE1/L1). Results: Total 5'-methyl-cytosine and L1 methylation levels in PBLs and CGCs were similar between controls and women with PCOS. Methylation assessed at CpG sites of L1 5'-UTR revealed a single CpG-site (CpG-4) to be consistently hypomethylated in PBLs of both PCOS groups and CGCs of stimulated PCOS group. In unstimulated women, hypomethylation at CpG-4 was strongly associated with PCOS susceptibility, whereas in stimulated group it showed strong associations with PCOS and its hormonal traits. Furthermore, CGCs demonstrated consistent global and CpG-DNA hypomethylation relative to PBLs, irrespective of normal or disease states. Conclusion: Our study revealed strong association of single hypomethylated CpG-site with PCOS. Identification and characterization of more such methyl-CpG signatures in repetitive elements in larger study populations would provide valuable epigenetic insights into PCOS.