Thrombomodulin Switches Signaling and Protease-Activated Receptor 1 Cleavage Specificity of Thrombin.

BACKGROUND: Cleavage of the extracellular domain of PAR1 (protease-activated receptor 1) by thrombin at Arg41 and by APC (activated protein C) at Arg46 initiates paradoxical cytopathic and cytoprotective signaling in endothelial cells. In the latter case, the ligand-dependent coreceptor signaling by EPCR (endothelial protein C receptor) is required for the protective PAR1 signaling by APC. Here, we investigated the role of thrombomodulin in determining the specificity of PAR1 signaling by thrombin. METHODS: We prepared a PAR1 knockout (PAR1-/-) EA.hy926 endothelial cell line by CRISPR/Cas9 and transduced PAR1-/- cells with lentivirus vectors expressing PAR1 mutants in which either Arg41 or Arg46 was replaced with an Ala. Furthermore, human embryonic kidney 293 cells were transfected with wild-type or mutant PAR1 cleavage reporter constructs carrying N-terminal Nluc (NanoLuc luciferase) and C-terminal enhanced yellow fluorescent protein tags. RESULTS: Characterization of transfected cells in signaling and receptor cleavage assays revealed that, upon interaction with thrombomodulin, thrombin cleaves Arg46 to elicit cytoprotective effects by a ß-arrestin-2 biased signaling mechanism. Analysis of functional data and cleavage rates indicated that thrombin-thrombomodulin cleaves Arg46>10-fold faster than APC. Upon interaction with thrombin, the cytoplasmic domain of thrombomodulin recruited both ß-arrestin-1 and -2 to the plasma membrane. Thus, the thrombin cleavage of Arg41 was also cytoprotective in thrombomodulin-expressing cells by ß-arrestin-1-biased signaling. APC in the absence of EPCR cleaved Arg41 to initiate disruptive signaling responses like thrombin. CONCLUSIONS: These results suggest that coreceptor signaling by thrombomodulin and EPCR determines the PAR1 cleavage and signaling specificity of thrombin and APC, respectively.

Thrombomodulin Regulates PTEN/AKT Signaling Axis in Endothelial Cells.

BACKGROUND: We recently demonstrated that deletion of thrombomodulin gene from endothelial cells results in upregulation of proinflammatory phenotype. In this study, we investigated the molecular basis for the altered phenotype in thrombomodulin-deficient (TM-/-) cells. METHODS: Different constructs containing deletions or mutations in the cytoplasmic domain of thrombomodulin were prepared and introduced to TM-/- cells. The phenotype of cells expressing different derivatives of thrombomodulin and tissue samples of thrombomodulin-knockout mice were analyzed for expression of distinct regulatory genes in established signaling assays. RESULTS: The phosphatase and tensin homolog were phosphorylated and its recruitment to the plasma membrane was impaired in TM-/- cells, leading to hyperactivation of AKT (protein kinase B) and phosphorylation-dependent nuclear exclusion of the transcription factor, forkhead box O1. The proliferative/migratory properties of TM-/- cells were enhanced, and cells exhibited hypersensitivity to stimulation by angiopoietin 1 and vascular endothelial growth factor. Reexpression of wild-type thrombomodulin in TM-/- cells normalized the cellular phenotype; however, thrombomodulin lacking its cytoplasmic domain failed to restore the normal phenotype in TM-/- cells. Increased basal permeability and loss of VE-cadherin were restored to normal levels by reexpression of wild-type thrombomodulin but not by a thrombomodulin construct lacking its cytoplasmic domain. A thrombomodulin cytoplasmic domain deletion mutant containing 3-membrane-proximal Arg-Lys-Lys residues restored the barrier-permeability function of TM-/- cells. Enhanced phosphatase and tensin homolog phosphorylation and activation of AKT and mTORC1 (mammalian target of rapamycin complex 1) were also observed in the liver of thrombomodulin-KO mice. CONCLUSIONS: These results suggest that the cytoplasmic domain of thrombomodulin interacts with the actin cytoskeleton and plays a crucial role in regulation of phosphatase and tensin homolog/AKT signaling in endothelial cells.

Novel nucleotide variations in the thrombomodulin (THBD) gene involved in coagulation pathways can increase the risk of recurrent pregnancy loss (RPL).

Recurrent pregnancy loss (RPL) is a common but complex complication in fertility conditions, affecting about 15-20% of couples. Although several causes have been proposed for RPL, it occurs in about 35-60% of cases without a known explanation. A strong assumption is that genetic factors play a role in the etiology and pathophysiology of PRL. Therefore, several genes are proposed as candidates in the pathogenesis of RPL. The current study aimed to investigate the effects of nucleotide changes in the THBD (thrombomodulin) gene as an RPL-related candidate gene. This gene encodes a cell receptor for thrombin and is involved in reproductive loss in RPL cases. Its involvement in the natural anticoagulant system has been extensively studied. By genetic screening of the entire coding and noncoding regions of the THBD gene, we found twenty-seven heterozygous and homozygous nucleotide changes. Ten of them led to amino acid substitutions, seven variants were identified in the promoter region, and eight of them occurred in 3'UTR. Potentially, the pathogenicity effects of these variations on THBD protein were evaluated by several prediction tools. The numerous genomic variations prompted noticeable modifications of the protein's structural and functional properties. Furthermore, in-silico scores were consistent with deleterious effects for these mutations. The results of this study provide genetic information that will be useful in the future for clinicians, scientists, and students to understand the unknown causes of RPL better. It may also pave the way for developing diagnostic/prognostic approaches to help treat PRL patients.

The role of thrombomodulin in modulating ITGB3 expression and its implications for triple-negative breast cancer progression.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer (BC) compared to other BC subtypes in clinical settings. Currently, there are no effective therapeutic strategies for TNBC treatment. Therefore, there is an urgent need to identify suitable biomarkers or therapeutic targets for TNBC patients. Thrombomodulin (TM) plays a role in cancer progression and metastasis in many different cancers. However, the role of TM in TNBC is not yet fully understood. First, silenced-TM in MDA-MB-231 cells caused an increase in proliferative and metastatic activity. In contrast, overexpression of TM in Hs578T cells caused a reduction in proliferation, invasion, and migration rate. Using RNA-seq analysis, we found that Integrin beta 3 (ITGB3) expression may be a downstream target of TM. Furthermore, we found an increase in ITGB3 levels in TM-KD cells by QPCR and western blot analysis but a decrease in ITGB3 levels in TM-overexpressing cells. We found phospho-smad2/3 levels were increased in TM-KD cells but decreased in TM-overexpressing cells. This implies that TM negatively regulates ITGB3 levels through the activation of the smad2/3 pathway. Silencing ITGB3 in TM-KD cells caused a decrease in proliferation and migration. Finally, we found that higher ITGB3 levels were correlated with poor overall survival and relapse-free survival in patients with TNBC. Our results indicated a novel regulatory relationship between TM and ITGB3 in TNBC.

Expression of human thrombomodulin by GalTKO.hCD46 pigs modulates coagulation cascade activation by endothelial cells and during ex vivo lung perfusion with human blood.

Thrombomodulin is important for the production of activated protein C (APC), a molecule with significant regulatory roles in coagulation and inflammation. To address known molecular incompatibilities between pig thrombomodulin and human thrombin that affect the conversion of protein C into APC, GalTKO.hCD46 pigs have been genetically modified to express human thrombomodulin (hTBM). The aim of this study was to evaluate the impact of transgenic hTBM expression on the coagulation dysregulation that is observed in association with lung xenograft injury in an established lung perfusion model, with and without additional blockade of nonphysiologic interactions between pig vWF and human GPIb axis. Expression of hTBM was variable between pigs at the transcriptional and protein level. hTBM increased the activation of human protein C and inhibited thrombosis in an in vitro flow perfusion assay, confirming that the expressed protein was functional. Decreased platelet activation was observed during ex vivo perfusion of GalTKO.hCD46 lungs expressing hTBM and, in conjunction with transgenic hTBM, blockade of the platelet GPIb receptor further inhibited platelets and increased survival time. Altogether, our data indicate that expression of transgenic hTBM partially addresses coagulation pathway dysregulation associated with pig lung xenograft injury and, in combination with vWF-GP1b-directed strategies, is a promising approach to improve the outcomes of lung xenotransplantation.

Recombinant soluble thrombomodulin attenuates cisplatin-induced intestinal injury by inhibiting intestinal epithelial cell-derived cytokine secretion.

BACKGROUND: Intestinal injury is one of the main side-effects of cisplatin chemotherapy, impairing the quality of life in patients with cancer. In this study, we investigated the protective effects of recombinant soluble thrombomodulin (rsTM), which is a potent anti-inflammatory agent, on cisplatin-induced intestinal injury. METHODS: We first evaluated the effects of rsTM on intestinal injury caused by cisplatin in mice in vivo. Disease progression was monitored by analyzing loss of body weight and histological changes in intestinal tissue. We then investigated the effects of rsTM on mouse intestinal organoid formation and growth in vitro. Gene expression levels were analyzed by quantitative real-time polymerase chain reaction and Western blotting. RESULTS: rsTM treatment significantly attenuated the loss of body weight, histological damage and gene expression levels of pro-inflammatory cytokines such as interleukin-6, tumor necrosis factor-α and high-mobility group box-1 in a cisplatin-treated mouse model. Furthermore, rsTM alleviated the inflammatory response and apoptosis in a cisplatin-treated intestinal epithelial organoid model. CONCLUSION: rsTM suppresses cisplatin-induced intestinal epithelial cell-derived cytokine production and alleviates intestinal mucositis.

Soluble thrombomodulin alleviates Diquat-induced acute kidney injury by inhibiting the HMGB1/IκBα/NF-κB signalling pathway.

Our research aimed to investigate whether soluble thrombomodulin (sTM) relieved Diquat (DQ)-induced acute kidney injury (AKI) via HMGB1/IκBα/NF-κB signaling pathways. An AKI rat model was constructed using DQ. Pathological changes in renal tissue were detected by HE and Masson staining. Gene expression was determined using qRT-PCR, IHC, and western blotting. Cell activity and apoptosis were analysed using CCK-8 and Flow cytometry, respectively. An abnormal kidney structure was observed in DQ rats. The levels of blood urea nitrogen (BUN), creatinine (CRE), uric acid (UA), oxidative stress, and inflammatory responses in the DQ group increased on the 7th day but decreased on the 14th day, compared with the control group. Additionally, HMGB1, sTM, and NF-kappaB (NF-κB) expression had increased in the DQ group compared with the control group, while the IκKα and IκB-α levels had decreased. In addition, sTM relieved the damaging effects of diquat on renal tubular epithelial cell viability, apoptosis, and the inflammatory response. The levels of HMGB1, TM, and NF-κB mRNA and protein were significantly decreased in the DQ + sTM group compared with the DQ group. These findings indicated that sTM could relieve Diquat-induced AKI through HMGB1/IκBα/NF-κB signaling pathways, which provides a treatment strategy for Diquat-induced AKI.

COMBINATION THERAPY WITH A SENSE OLIGONUCLEOTIDE TO INDUCIBLE NITRIC OXIDE SYNTHASE MRNA AND HUMAN SOLUBLE THROMBOMODULIN IMPROVES SURVIVAL OF SEPSIS MODEL RATS AFTER PARTIAL HEPATECTOMY.

ABSTRACT: Sepsis after a major hepatectomy is a critical problem. In septic shock, the inflammatory mediator, nitric oxide (NO), is overproduced in hepatocytes and macrophages. The natural antisense (AS) transcripts, non-coding RNAs, are transcribed from a gene that encodes inducible nitric oxide synthase (iNOS). iNOS AS transcripts interact with and stabilize iNOS mRNAs. A single-stranded "sense oligonucleotide" (designated as SO1) corresponding to the iNOS mRNA sequence inhibits mRNA-AS transcript interactions and reduces iNOS mRNA levels in rat hepatocytes. In contrast, recombinant human soluble thrombomodulin (rTM) treats disseminated intravascular coagulopathy by suppressing coagulation, inflammation, and apoptosis. In this study, the combination therapy of SO1 and a low dose of rTM was evaluated for hepatoprotection in a rat septic shock model after partial hepatectomy. Rats underwent 70% hepatectomy, followed by intravenous (i.v.) injection of lipopolysaccharide (LPS) after 48 h. SO1 was injected (i.v.) simultaneously with LPS, whereas rTM was injected (i.v.) 1 h before LPS injection. Similarly to our previous report, SO1 increased survival after LPS injection. When rTM, which has different mechanisms of action, was combined with SO1, it did not interfere with the effect of SO1 and showed a significant increase in survival compared with LPS alone treatment. In serum, the combined treatment decreased NO levels. In the liver, the combined treatment inhibited iNOS mRNA and protein expression. A decreased iNOS AS transcript expression by the combined treatment was also observed. The combined treatment decreased mRNA expression of the inflammatory and pro-apoptotic genes while increasing that of the anti-apoptotic gene. Furthermore, the combined treatment reduced the number of myeloperoxidase-positive cells. These results suggested that the combination of SO1 and rTM has therapeutic potential for sepsis.

Atypical Hemolytic Uremic Syndrome in a Pregnant Patient with a Thrombomodulin Gene Variant Treated with Plasma Exchange and Eculizumab.

BACKGROUND Hemolytic uremic syndrome (HUS) includes the triad of thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. The atypical form of HUS is a rare disease characterized by complement overactivation, and it can be from genetic or acquired causes. Genetic causes involve mutation in one of the factors in the alternative complement pathway or inhibitors. Malignant hypertension and pregnancy are the most important acquired causes. The optimal management of patients with aHUS is with eculizumab, which is recombinant antibody against human complement component C5. CASE REPORT This report describes the case of a 25-year-old woman with frequent hospitalizations for poorly controlled hypertension who presented at 20 weeks of gestation with headache, vomiting, and a blood pressure of 230/126 mmHg. The patient had acute kidney injury with hematuria and proteinuria, and kidney biopsy showed hypertensive arteriolar nephrosclerosis and fibrinoid arteriolar necrosis consistent with thrombotic microangiopathy. Further work-up with a genetic panel showed heterozygosity for the thrombomodulin (THBD) gene. She was started on treatment with plasma exchange and eculizumab, a recombinant monoclonal antibody that inhibits terminal complement activation at the C5 protein. The patient responded well to the treatment at the time of her initial outpatient follow-up. CONCLUSIONS This case shows the potential of severe renal manifestation of aHUS, and the need for a kidney biopsy in cases of severe uncontrolled hypertension presenting with kidney injury. If evidence of aHUS is found, prompt treatment with plasma exchange and eculizumab should be initiated.

DNA methylation changes and increased mRNA expression of coagulation proteins, factor V and thrombomodulin in Fuchs endothelial corneal dystrophy.

Late-onset Fuchs endothelial corneal dystrophy (FECD) is a disease affecting the corneal endothelium (CE), associated with a cytosine-thymine-guanine repeat expansion at the CTG18.1 locus in the transcription factor 4 (TCF4) gene. It is unknown whether CTG18.1 expansions affect global methylation including TCF4 gene in CE or whether global CE methylation changes at advanced age. Using genome-wide DNA methylation array, we investigated methylation in CE from FECD patients with CTG18.1 expansions and studied the methylation in healthy CE at different ages. The most revealing DNA methylation findings were analyzed by gene expression and protein analysis. 3488 CpGs had significantly altered methylation pattern in FECD though no substantial changes were found in TCF4. The most hypermethylated site was in a predicted promoter of aquaporin 1 (AQP1) gene, and the most hypomethylated site was in a predicted promoter of coagulation factor V (F5 for gene, FV for protein). In FECD, AQP1 mRNA expression was variable, while F5 gene expression showed a ~ 23-fold increase. FV protein was present in both healthy and affected CE. Further gene expression analysis of coagulation factors interacting with FV revealed a ~ 34-fold increase of thrombomodulin (THBD). THBD protein was detected only in CE from FECD patients. Additionally, we observed an age-dependent hypomethylation in elderly healthy CE.Thus, tissue-specific genome-wide and gene-specific methylation changes associated with altered gene expression were discovered in FECD. TCF4 pathological methylation in FECD because of CTG18.1 expansion was ruled out.

A missense mutation in lectin domain of thrombomodulin causing functional deficiency.

Thrombomodulin (TM) functions in coagulation, fibrinolysis and inflammation by its cofactor activity for protein C, thrombin-activatable fibrinolysis inhibitor (TAFI) activation and high mobility group box 1 (HMGB1) degradation induced by thrombin. It has been widely reported that mutations in TM are related to thromboembolic diseases but hardly in lectin domain. Here we report our findings about the functional deficiencies in TM caused by substitution of aspartate with tyrosine at residue 126. Three patients suffering from recurrent thromboembolic diseases were identified with this mutation and their plasma soluble TM levels were decreased. Transfected cells expressing wild-type TM or the variant and corresponding proteins were used to examine TM functions in vitro. The cofactor activity of the mutant for protein C, TAFI activation was reduced to approximately 50% and 60% respectively. Loss in anti-inflammation due to weakened HMGB1 degradation was also observed. And the study with thrombosis models of mice suggested the decreased inhibition of thrombus development of the mutant. Together the results showed deleterious changes on TM function caused by this mutation, which may explain the thrombophilia tendency of the patients. This work provided supportive evidence that mutation in lectin domain of TM might be related to thrombotic diseases and may help us better understand the physiological roles of TM.

Recombinant Thrombomodulin Has Anti-tumor Effects and Enhances the Effects of Gemcitabine for Pancreatic Cancer Through G-protein Coupled Receptor 15.

BACKGROUND/AIM: Thrombomodulin™ has cytoprotective and anti-inflammatory function by interacting with G-protein coupled receptor 15 (GPR15). Recombinant TM (rTM), which comprises the extracellular regions of TM, is approved for treatment of disseminated intravascular coagulation. We investigated the anti-tumor effect of rTM for pancreatic ductal adenocarcinoma (PDAC) through GPR15. MATERIALS AND METHODS: We evaluated the expression of GPR15 in human PDAC cell lines and the anti-tumor effect and signals of rTM in vitro and in vivo. To test whether GPR15 would be responsible for the inhibition of cell proliferation by rTM, we evaluated the cell viability of the GPR15 knockdown cells treated with rTM using GPR15-targeting siRNA. RESULTS: We identified PDAC cell lines with GPR15 expression and discovered that rTM inhibited tumor growth and enhanced the effects of gemcitabine (GEM) for the PDAC cell line in a GPR15-dependent manner. Furthermore, we showed that rTM inhibited nuclear factor-kappaB (NF-[Formula: see text]B) and extracellular signal-regulated kinase (ERK) activation through interactions with GPR15. CONCLUSION: We demonstrated that rTM had anti-tumor effect and enhancement of cytotoxic effect of GEM for PDAC cells by inhibiting NF-[Formula: see text]B and ERK activation via GPR15 and suggest that rTM is a potential therapeutic option for PDAC.

Genetic and immune changes in Tibetan high-altitude populations contribute to biological adaptation to hypoxia.

BACKGROUND: Tibetans have lived at very high altitudes for thousands of years, and have a distinctive suite of physiological traits that enable them to tolerate environmental hypoxia. Expanding awareness and knowledge of the differences in hematology, hypoxia-associated genes, immune system of people living at different altitudes and from different ethnic groups may provide evidence for the prevention of mountain sickness. METHOD: Ninety-five Han people at mid-altitude, ninety-five Tibetan people at high-altitude and ninety-eight Han people at high-altitude were recruited. Red blood cell parameters, immune cells, the contents of cytokines, hypoxia-associated gene single nucleotide polymorphisms (SNPs) were measured. RESULTS: The values of Hematocrit (HCT), Mean cell volume (MCV) and Mean cell hemoglobin (MCH) in red blood cell, immune cell CD19+ B cell number, the levels of cytokines Erb-B2 receptor tyrosine kinase 3 (ErbB3) and Tumor necrosis factor receptor II (TNF-RII) and the levels of hypoxia-associated factors Hypoxia inducible factor-1α (HIF-1α), Hypoxia inducible factor-2α (HIF-2α) and HIF prolyl 4-hydroxylase 2 (PHD2) were decreased, while the frequencies of SNPs in twenty-six Endothelial PAS domain protein 1 (EPAS1) and Egl-9 family hypoxia inducible factor 1 (EGLN1) were increased in Tibetan people at high-altitude compared with that of Han peoples at high-altitude. Furthermore, compared with mid-altitude individuals, high-altitude individuals showed lower blood cell parameters including Hemoglobin concentration (HGB), HCT, MCV and MCH, higher Mean cell hemoglobin concentration (MCHC), lower immune cells including CD19+ B cells, CD4+ T cells and CD4/CD8 ratio, higher immune cells containing CD8+ T cells and CD16/56NK cells, decreased Growth regulated oncogene alpha (GROa), Macrophage inflammatory protein 1 beta (MIP-1b), Interleukin-8 (IL-8), and increased Thrombomodulin, downregulated hypoxia-associated factors including HIF1α, HIF2α and PHD2, and higher frequency of EGLN1 rs2275279. CONCLUSIONS: These results indicated that biological adaption to hypoxia at high altitude might have been mediated by changes in immune cells, cytokines, and hypoxia-associated genes during the evolutionary history of Tibetan populations. Furthermore, different responses to high altitude were observed in different ethnic groups, which may provide a useful knowledge to improve the protection of high-altitude populations from mountain sickness.

Epigenetic repression of THBD transcription by BRG1 contributes to deep vein thrombosis.

BACKGROUND: Deep vein thrombosis (DVT) with its major complication, pulmonary embolism, is a global health problem. Endothelial dysfunction is involved in the pathogenesis of DVT. We have previously demonstrated that endothelial specific deletion of Brahma-related gene 1 (BRG1) ameliorates atherosclerosis and aneurysm in animal models. Whether endothelial BRG1 contributes to DVT development remains undetermined. METHODS: DVT was induced in mice by ligation of inferior vena cava. Deletion of BRG1 in endothelial cells was achieved by crossing the Cdh5-ERT-Cre mice with the Brg1loxp/loxp mice. RESULTS: Here we report that compared to the wild type mice, BRG1 conditional knockout (CKO) mice displayed substantially decreased DVT susceptibility characterized by decreased weight and size of thrombus and reduced immune infiltration. In endothelial cells, thrombomodulin (THBD) expression was significantly decreased by TNF-α stimulation, while BRG1 knockdown or inhibition recovered THBD expression. Further analysis revealed that BRG1 deficiency decreased the CpG methylation levels of the THBD promoter induced by TNF-α. Mechanistically, BRG1 directly upregulated DNMT1 expression after TNF-α treatment in endothelial cells. More importantly, administration of a small-molecule BRG1 inhibitor PFI-3 displayed potent preventive and therapeutic potentials in the DVT model. CONCLUSIONS: Our findings implicate BRG1 as an important regulator of DVT pathogenesis likely through epigenetic regulation of THBD expression in endothelial cells and provide translational proof-of-concept for targeting BRG1 in DVT intervention.

MiR-550a-3p restores damaged vascular smooth muscle cells by inhibiting thrombomodulin in an in vitro atherosclerosis model.

Thrombomodulin (TM) is involved in the pathological process of atherosclerosis; however, the underlying mechanism remains unclear. Oxidised low-density lipoprotein (Ox-LDL; 100 µg/mL) was used to induce human vascular smooth muscle cells (HVSMCs) into a stable atherosclerotic cell model. The expression levels of miR-550a-3p and TM were detected by real-time reverse transcription-polymerase chain reaction. Cell proliferation was estimated using CCK8 and EDU assays. Wound scratch and transwell assays were used to measure the ability of cells to invade and migrate. Propidium iodide fluorescence-activated cell sorting was used to detect apoptosis and cell cycle changes. A dual-luciferase reporter assay was performed to determine the binding of miR-550a-3p to TM. Our results suggested the successful development of a cellular atherosclerosis model. Our data revealed that TM overexpression significantly promoted the proliferation, invasion, migration, and apoptosis of HVSMCs as well as cell cycle changes. Upregulation of miR-550a-3p inhibited the growth and metastasis of HVSMCs. Furthermore, miR-550a-3p was confirmed to be a direct target of TM. Restoration of miR-550a-3p expression rescued the effects of TM overexpression. Thus, miR-550a-3p might play a role in atherosclerosis and, for the first time, normalised the function of injured vascular endothelial cells by simultaneous transfection of TM and miR-550a-3p. These results suggest that the miR-550a-3p/TM axis is a potential therapeutic target for atherosclerosis.

Association of SNP (rs1042579) in thrombomodulin gene and plasma thrombomodulin level in North Indian children with Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is the commonest systemic vasculitis in children. It predisposes to development of coronary artery abnormalities (CAAs). Thrombomodulin (THBD) gene polymorphism rs1042579 is associated with high risk of cerebrovascular diseases. However, association of THBD polymorphism (rs1042579) and plasma thrombomodulin (TM) levels with susceptibility to KD and CAAs remains unclear. METHODS AND RESULTS: Polymorphism in THBD gene (rs1042579) was analysed in 50 KD patients and 50 age, gender and ethnicity matched controls using Sanger sequencing. Plasma TM levels were measured by ELISA. RESULTS: Mean plasma TM level (± SD) in KD patients was 2549.41 (± 853.18) pg/ml and in controls was 2298.03 (± 869.14) pg/ml; p = 0.042. Mean plasma TM levels in CC genotype was 2299.98 (± 834.88) pg/ml and in CT/TT genotype was 2837.96 (± 857.14) pg/ml; p = 0.005. Genotyping data did not reveal significant differences in patients with KD as compared to controls (p = 0.25), and in KD patients with and without CAAs (p = 0.407). Odds of finding T allele in cases were 2.07 times greater than in controls (p = 0.093). CONCLUSIONS: This is the first study from India, and second in the world, that investigates association of THBD gene polymorphism with KD. This is also the first study to assess plasma TM levels in KD patients. Our data show that plasma TM levels were significantly higher in KD patients with CT/TT genotypes. Further, the polymorphism rs1042579 at exon 1 of THBD gene was found to be more common in KD patients than in controls although the difference was not statistically significant.

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.

Genetic prediction of ICU hospitalization and mortality in COVID-19 patients using artificial neural networks.

There is an unmet need of models for early prediction of morbidity and mortality of Coronavirus disease-19 (COVID-19). We aimed to a) identify complement-related genetic variants associated with the clinical outcomes of ICU hospitalization and death, b) develop an artificial neural network (ANN) predicting these outcomes and c) validate whether complement-related variants are associated with an impaired complement phenotype. We prospectively recruited consecutive adult patients of Caucasian origin, hospitalized due to COVID-19. Through targeted next-generation sequencing, we identified variants in complement factor H/CFH, CFB, CFH-related, CFD, CD55, C3, C5, CFI, CD46, thrombomodulin/THBD, and A Disintegrin and Metalloproteinase with Thrombospondin motifs (ADAMTS13). Among 381 variants in 133 patients, we identified 5 critical variants associated with severe COVID-19: rs2547438 (C3), rs2250656 (C3), rs1042580 (THBD), rs800292 (CFH) and rs414628 (CFHR1). Using age, gender and presence or absence of each variant, we developed an ANN predicting morbidity and mortality in 89.47% of the examined population. Furthermore, THBD and C3a levels were significantly increased in severe COVID-19 patients and those harbouring relevant variants. Thus, we reveal for the first time an ANN accurately predicting ICU hospitalization and death in COVID-19 patients, based on genetic variants in complement genes, age and gender. Importantly, we confirm that genetic dysregulation is associated with impaired complement phenotype.