Protection of ß2GPI Deficient Mice from Thrombosis Reflects a Defect in PAR3-facilitated Platelet Activation.

Background: Antibodies to ß2-glycoprotein I (ß2GPI) cause thrombosis in antiphospholipid syndrome, however the role of ß2GPI itself in regulation of coagulation pathways in vivo is not well understood. Methods: We developed ß2GPI-deficient mice (Apoh -/- ) by deleting exon 2 and 3 of Apoh using CRISPR/Cas9 and compared the propensity of wild-type (WT) and Apoh -/- mice to develop thrombosis using rose bengal and FeCl 3 -induced carotid thrombosis, laser-induced cremaster arteriolar injury, and inferior vena cava (IVC) stasis models. We also compared tail bleeding times and assessed platelet activation in WT and Apoh -/- mice in the absence and presence of exogenous ß2GPI. Results: Compared to WT littermates, Apoh -/- mice demonstrated a prolonged time to occlusion of the carotid artery after exposure to rose bengal or FeCl 3 , and reduced platelet and fibrin accumulation in cremasteric arterioles after laser injury. Similarly, significantly smaller thrombi were retrieved from the IVC of Apoh -/- mice 48 hours after IVC occlusion. The activated partial thromboplastin time (aPTT) and prothrombin time, as well as aPTT reagent- and tissue factor-induced thrombin generation times using plasma from Apoh -/- and WT mice revealed no differences. However, we observed significant prolongation of tail bleeding in Apoh -/- mice, and reduced P-selectin expression and binding of fibrinogen to the activated α2bß3 integrin on platelets from these mice after stimulation with low thrombin concentrations; these changes were reversed by exogenous ß2GPI. An antibody to PAR3 blocked thrombin-induced activation of WT, but not Apoh -/- platelets, as well as the ability of ß2GPI to restore the activation response of Apoh -/- platelets to thrombin. ß2GPI deficiency did not affect platelet activation by a PAR4-activator peptide, or ADP. Conclusions: In mice, ß2GPI may mediate procoagulant activity by enhancing the ability of PAR3 to present thrombin to PAR4, promoting platelet activation at low thrombin concentrations. Key Points: ß2GPI deficient mice are protected from experimental arterial, venous, and microvascular thrombosis.ß2GPI deficient mice display prolonged tail bleeding times and reduced PAR3-facilitated platelet activation by low concentrations of thrombin.

Aberrant promoter hypermethylation regulates thrombomodulin in high altitude induced deep vein thrombosis.

BACKGROUND: DNA methylation regulates gene expression by inhibiting transcription factor binding to promoter and regulatory regions. Acute hypoxia during altitude exposure is associated with decreased natural anticoagulants and morbid thrombotic events. Thrombomodulin (TM) is a high affinity thrombin binding receptor protein, vital for vascular homeostasis. The purpose of this study is to determine gene expression regulation via methylation of TM gene in high altitude hypoxia induced deep vein thrombosis (DVT) patients. MATERIALS AND RESULTS: Percent 5-methyl cytosine analysis showed increased methylation in high altitude DVT patients (HAP) as compared to high altitude control (HAC) and seal level control (Control) subjects, while TM protein and mRNA levels were decreased in high altitude DVT patients as compared to other two groups. Bisulfite sequencing analysis indicated increased methylation in TM promoter in high altitude DVT patients compared to high altitude controls. Flow cytometry analysis showed decreased TM expression in hypoxia induced primary human umbilical vein endothelial cells (HUVECs). Treatment with specific DNA methyltransferase (DNMT) inhibitor-decitabine during hypoxia, restored TM expression. in vitro global methylation assay showed increased methylation in hypoxia group. Specific concentration of decitabine in hypoxia decreased global methylation showing a direct correlation between DNMTs and methylation. Selective dose of decitabine restored TM levels in HUVECs. DNMT1 and DNMT3B proteins showed to mediate the overall expression of TM. CONCLUSION: TM emerged as a potential candidate for methylation in high altitude DVT patients, regulated by hypoxia-induced epigenetic mechanism. Hypoxia culminates in methylation of DNA sequences in the promoter region of TM gene and increased the expression of DNMT1 and DNMT3B per se in primary HUVECs. Critical DNA methylation events were found to be compromised in high altitude DVT patients.

Transcriptome Profiling Reveals the Endogenous Sponging Role of LINC00659 and UST-AS1 in High-Altitude Induced Thrombosis.

BACKGROUND: The pathophysiology of deep vein thrombosis (DVT) is considered as multifactorial, where thrombus formation is an interplay of genetic and acquired risk factors. Little is known about the expression profile and roles of long noncoding RNAs (lncRNAs) in human subjects developing DVT at high altitude. METHODS: Using RNAseQ, we compared peripheral blood mRNA and lncRNA expression profile in human high-altitude DVT (HA-DVT) patients with high-altitude control subjects. We used DESeq to identify differentially expressed (DE) genes. We annotated the lncRNAs using NONCODE 3.0 database. In silico putative lncRNA-miRNA association study unravels the endogenous miRNA sponge associated with our candidate lncRNAs. These findings were validated by small-interfering RNA (siRNA) knockdown assay of the candidate lncRNAs conducted in primary endothelial cells. RESULTS: We identified 1,524 DE mRNAs and 973 DE lncRNAs. Co-expressed protein-coding gene analysis resulted in a list of 722 co-expressed protein-coding genes with a Pearson correlation coefficients >0.7. The functional annotation of co-expressed genes and putative proteins revealed their involvement in the hypoxia, immune response, and coagulation cascade. Through its miRNA response elements to compete for miR-143 and miR-15, lncRNA-LINC00659 and UXT-AS1 regulate the expression of prothrombotic genes. Furthermore, in vitro RNA interference (siRNA) simultaneously suppressed lncRNAs and target gene mRNA level. CONCLUSION: This transcriptome profile describes novel potential mechanisms of interaction between lncRNAs, the coding genes, miRNAs, and regulatory transcription factors that define the thrombotic signature and may be used in establishing lncRNAs as a biomarker in HA-DVT.

Gene Expression Profiling Reveals the Shared and Distinct Transcriptional Signatures in Human Lung Epithelial Cells Infected With SARS-CoV-2, MERS-CoV, or SARS-CoV: Potential Implications in Cardiovascular Complications of COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative virus for the current global pandemic known as coronavirus disease 2019 (COVID-19). SARS-CoV-2 belongs to the family of single-stranded RNA viruses known as coronaviruses, including the MERS-CoV and SARS-CoV that cause Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS), respectively. These coronaviruses are associated in the way that they cause mild to severe upper respiratory tract illness. This study has used an unbiased analysis of publicly available gene expression datasets from Gene Expression Omnibus to understand the shared and unique transcriptional signatures of human lung epithelial cells infected with SARS-CoV-2 relative to MERS-CoV or SARS-CoV. A major goal was to discover unique cellular responses to SARS-CoV-2 among these three coronaviruses. Analyzing differentially expressed genes (DEGs) shared by the three datasets led to a set of 17 genes, suggesting the lower expression of genes related to acute inflammatory response (TNF, IL32, IL1A, CXCL1, and CXCL3) in SARS-CoV-2. This subdued transcriptional response to SARS-CoV-2 may cause prolonged viral replication, leading to severe lung damage. Downstream analysis of unique DEGs of SARS-CoV-2 infection revealed changes in genes related to apoptosis (NRP1, FOXO1, TP53INP1, CSF2, and NLRP1), coagulation (F3, PROS1, ITGB3, and TFPI2), and vascular function (VAV3, TYMP, TCF4, and NR2F2), which may contribute to more systemic cardiovascular complications of COVID-19 than MERS and SARS. The study has uncovered a novel set of transcriptomic signatures unique to SARS-CoV-2 infection and shared by three coronaviruses, which may guide the initial efforts in the development of prognostic or therapeutic tools for COVID-19.

Study of Metal-Metal Interactions and Their Biomarkers Using an Intestinal Human Cell Line.

From the time of dietary intake to their utilization, the number of important interactions occurs among mineral elements, which can affect their bioavailability because of similarity in physicochemical properties and common absorptive pathways. However, the studies that have analyzed the interactions among copper, iron, and zinc have conflicting results and need further exploration. HT-29 cells grown to confluence in 6-well plates were incubated with increasing concentrations (0 to 200 µM) of Cu, Fe, and Zn for 3 and 6 h for uptake studies. Interaction studies involved measuring the uptake of metal in the presence of 0:1-4:1 ratio of the other metal for 3 h using atomic absorption spectrophotometer. The concentration of metal biomarkers and cytokines was also measured in the cell lysate following extracellular supplementation. The presence of 50 µM Zn significantly decreased (P < 0.05) cellular Cu uptake in HT-29 cells at 0.5:1 Cu:Zn ratio and also the cellular Fe uptake at the ratios 0.5:1, 2:1, and 4:1 Fe:Zn. The presence of 50 µM Fe significantly (P < 0.05) decreased cellular Cu uptake at the ratios 1:1, 2:1, and 4:1 Cu:Fe. The concentration of metallothionein responded significantly (P < 0.05) to changes in extracellular Zn concentration (supplementation and depletion). There was a decrease in concentration of IL-1ß and TNF-α (P < 0.05) with an increasing extracellular concentration of Cu and Fe. The results of the study indicated that the presence of one mineral in the diet and multi mineral supplement may influence the bioavailability of the other mineral. Copper and iron may find application in promoting gut health.

micro-RNAs dependent regulation of DNMT and HIF1α gene expression in thrombotic disorders.

MicroRNAs (miRNAs) are involved in a wide variety of cellular processes and post-transcriptionally regulate several mechanism and diseases. However, contribution of miRNAs functioning during hypoxia and DNA methylation together is less understood. The current study was aimed to find a shared miRNAs signature upstream to hypoxia (via HIF gene family members) and methylation (via DNMT gene family members). This was followed by the global validation of the hypoxia related miRNA signature using miRNA microarray meta-analysis of the hypoxia induced human samples. We further concluded the study by looking into thrombosis related terms and pathways enriched during protein-protein interaction (PPI) network analysis of these two sets of gene family. Network prioritization of these shared miRNAs reveals miR-129, miR-19band miR-23b as top regulatory miRNAs. A comprehensive meta-analysis of microarray datasets of hypoxia samples revealed 29 differentially expressed miRNAs. GSEA of the interacting genes in the DNMT-HIF PPI network indicated thrombosis associated pathways including "Hemostasis", "TPO signaling pathway" and "angiogenesis". Interestingly, the study has generated a novel database of candidate miRNA signatures shared between hypoxia and methylation, and their relation to thrombotic pathways, which might aid in the development of potential therapeutic biomarkers.

Perspective: DNA Copy Number Variations in Cardiovascular Diseases.

Human genome contains many variations, often called mutations, which are difficult to detect and have remained a challenge for years. A substantial part of the genome encompasses repeats and when such repeats are in the coding region they may lead to change in the gene expression profile followed by pathological conditions. Structural variants are alterations which change one or more sequence feature in the chromosome such as change in the copy number, rearrangements, and translocations of a sequence and can be balanced or unbalanced. Copy number variants (CNVs) may increase or decrease the copies of a given region and have a pivotal role in the onset of many diseases including cardiovascular disorders. Cardiovascular disorders have a magnitude of well-established risk factors and etiology, but their correlation with CNVs is still being studied. In this article, we have discussed history of CNVs and a summary on the diseases associated with CNVs. To detect such variations, we shed light on the number of techniques introduced so far and their limitations. The lack of studies on cardiovascular diseases to determine the frequency of such variants needs clinical studies with larger cohorts. This review is a compilation of articles suggesting the importance of CNVs in multitude of cardiovascular anomalies. Finally, future perspectives for better understanding of CNVs and cardiovascular disorders have also been discussed.

Comprehensive Gene expression meta-analysis and integrated bioinformatic approaches reveal shared signatures between thrombosis and myeloproliferative disorders.

Thrombosis is a leading cause of morbidity and mortality in patients with myeloproliferative disorders (MPDs), particularly polycythemia vera (PV) and essential thrombocythemia (ET). Despite the attempts to establish a link between them, the shared biological mechanisms are yet to be characterized. An integrated gene expression meta-analysis of five independent publicly available microarray data of the three diseases was conducted to identify shared gene expression signatures and overlapping biological processes. Using INMEX bioinformatic tool, based on combined Effect Size (ES) approaches, we identified a total of 1,157 differentially expressed genes (DEGs) (697 overexpressed and 460 underexpressed genes) shared between the three diseases. EnrichR tool's rich library was used for comprehensive functional enrichment and pathway analysis which revealed "mRNA Splicing" and "SUMO E3 ligases SUMOylate target proteins" among the most enriched terms. Network based meta-analysis identified MYC and FN1 to be the most highly ranked hub genes. Our results reveal that the alterations in biomarkers of the coagulation cascade like F2R, PROS1, SELPLG and ITGB2 were common between the three diseases. Interestingly, the study has generated a novel database of candidate genetic markers, pathways and transcription factors shared between thrombosis and MPDs, which might aid in the development of prognostic therapeutic biomarkers.