Ligand-dependent enhancement of human antithrombin gene expression by retinoid X receptor alpha and thyroid hormone receptor beta

Decreased antithrombin activity and inflammation in cats

OBJECTIVES

The objective of this study was to determine if inflammatory markers are associated with antithrombin activity in cats.

METHODS

For a retrospective population of 231 cats admitted to a referral hospital, antithrombin activity was classified as decreased (n = 77), intermediate (n = 97) or in the upper quartile (n = 57). Odds ratios (ORs) were calculated for an association between decreased or upper quartile activity and hypoalbuminemia, hyperfibrinogenemia, band neutrophilia and toxic change. Multiple logistic regression was performed to determine if an association between band neutrophilia and decreased antithrombin activity was independent of decreased hepatic synthesis, consumptive coagulopathy or protein loss.

RESULTS

Cats with decreased antithrombin activity were more likely than cats with intermediate-to-upper quartile activity to have band neutrophilia (OR 2.85, P = 0.0050), hypoalbuminemia (OR 12.1, P <0.0001) or toxic neutrophils (OR 4.47, P <0.0001). Cats with antithrombin activity in the upper quartile were less likely than those with intermediate-to-low activity to have hypoalbuminemia (OR 0.31, P = 0.0023) or toxic neutrophils (OR 0.44, P = 0.033). In a regression model that included other mechanisms for decreased antithrombin, band neutrophilia remained associated with decreased antithrombin activity (adjusted OR 2.62, P = 0.013).

CONCLUSIONS AND RELEVANCE

Contrary to previous studies suggesting antithrombin is a feline positive acute phase protein, this study demonstrates an association between decreased antithrombin activity and inflammation. Further studies are needed to determine the mechanistic basis of this association.

Dexamethasone Preconditioning in Cardiac Procedures Reduces Decreased Antithrombin Activity and Is Associated to Beneficial Outcomes: Role of Endothelium

Introduction: Decreased antithrombin (AT) activity in patients scheduled for cardiovascular surgery under cardiopulmonary bypass (CPB) is related to increased postoperative complications and hospitalization time. Indirect evidence suggests that glucocorticoids mitigate this decreased AT activity. To better understand the beneficial effects of AT we have analyzed: (i) the clinical relevance of acute dexamethasone (DX) administration before cardiac surgery on AT activity, (ii) the modulation by DX of AT expression in human endothelial cells (hECs), (iii) the activity of AT on migration and angiogenesis of hECs, or on angiogenesis of rat aorta. Methods: A retrospective cohort study in patients undergoing aortic valve replacement surgery was designed to evaluate the effect of DX administration on AT activity at five separate time points: preoperatively, during CPB, at intensive care unit admission and at 12 and 24 h post-intervention. We have analyzed also clinical differences in postoperative outcomes as safety and the length of stay in hospitalization. Changes in mRNA levels of AT induced by DX were determined by qRT-PCR in human coronary (hCEC), aorta (hAEC) and cardiac microvasculature (hCMEC) endothelial cells. AT activity on migration and angiogenesis were also assayed. Angiogenic growth of rat aortic rings incubated in Matrigel® was determined in presence and absence of AT. Results: The cohort comprised 51 patients in the control group and 29 patients in the group receiving dexamethasone. Preoperative DX supplementation reduced intraoperative decrease of AT activity (67.71 ± 10.49% DX treated vs. 58.12 ± 9.11% untreated, p < 0.001) that could be related to a decrease in the hospitalization time (7.59 ± 4.08 days DX treated vs. 13.59 ± 16.00 days untreated, p = 0.014). Treatment of hECs with 500 nM DX slightly increased AT expression. Incubation with 0.5 and 1 IU/mL of AT increased migration and angiogenesis in hCAECs and hAECs, but not in hCMECs. The same concentrations of AT potentiated angiogenic sprouting of new vessels from rat aorta. Conclusion: Preoperative DX supplementation could be an interesting procedure to avoid excessive decrease in AT levels during cardiac surgery. Positive outcomes associated with maintaining adequate AT levels could be related to its potential beneficial effect on endothelial function (migration and angiogenesis).

Genes associated with venous thromboembolism in colorectal cancer patients

Essentials The underlying pathophysiological mechanisms behind cancer-associated thrombosis are unknown. We compared expression profiles in tumor cells from patients with and without thrombosis. Tumors from patients with thrombosis showed significant differential gene expression profiles. Patients with thrombosis had a proinflammatory status and increased fibrin levels in the tumor.

SUMMARY

Background Venous thromboembolism (VTE) is a frequent complication in patients with cancer, and is associated with significant morbidity and mortality. However, the mechanisms behind cancer-associated thrombosis are still incompletely understood. Objectives To identify novel genes that are associated with VTE in patients with colorectal cancer (CRC). Methods Twelve CRC patients with VTE were age-matched and sex-matched to 12 CRC patients without VTE. Tumor cells were isolated from surgical samples with laser capture microdissection approaches, and mRNA profiles were measured with next-generation RNA sequencing. Results This approach led to the identification of new genes and pathways that might contribute to VTE in CRC patients. Application of ingenuity pathway analysis indicated significant links with inflammation, the methionine degradation pathway, and increased platelet function, which are all key processes in thrombus formation. Tumor samples of patients with VTE had a proinflammatory status and contained higher levels of fibrin and fibrin degradation products than samples of those without VTE. Conclusion This case-control study provides a proof-of-principle that tumor gene expression can discriminate between cancer patients with low and high risks of VTE. These findings may help to further unravel the pathogenesis of cancer-related VTE. The identified genes could potentially be used as candidate biomarkers to select high-risk CRC patients for thromboprophylaxis.

Identification of 2 Novel Polymorphisms and rs3138521 in 5′ Untranslated Region of SERPINC1 Gene in North Indian Population With Deep Vein Thrombosis

Antithrombin III (AT) is the most important endogenous anticoagulant, and genetic variability in SERPINC1, gene encoding AT, is low. Mutations leading to AT deficiency and increased thrombotic risk are well known; however, only 2 studies have reported mutations in regulatory region of SERPINC1 gene till date. Aim of the present study was to identify genetic variations in SERPINC1 5′ untranslated region (UTR) in Indian patients with deep vein thrombosis (DVT) having AT deficiency. DNA sequencing was used to identify underlying genetic defects in SERPINC1 regulatory region. In silico tools TFBIND and PROMO were used to identify transcription factor binding sites in the promoter region. We have identified 2 novel polymorphisms, g.25G>A and g.−1A>T, and 2 known g.67G>A and rs3138521 5′ UTR polymorphisms in SERPINC1 regulatory region in Indian patients with DVT for the first time. In present study, allele frequencies of rs3138521 (S: 0.37 and F: 0.63) were similar to that reported in Western population and were not associated with low plasma AT levels ( P value .5). This is the first report of regulatory region polymorphisms in SERPINC1 gene in Indian population. Our results strongly suggest that similar studies should be included when ever no mutation is detected in protein-coding region of AT gene.

Identification of Regulatory Mutations in SERPINC1 Affecting Vitamin D Response Elements Associated with Antithrombin Deficiency

Antithrombin is a crucial anticoagulant serpin whose even moderate deficiency significantly increases the risk of thrombosis. Most cases with antithrombin deficiency carried genetic defects affecting exons or flanking regions of SERPINC1.We aimed to identify regulatory mutations inSERPINC1 through sequencing the promoter, intron 1 and 2 of this gene in 23 patients with antithrombin deficiency but without known genetic defects. Three cases with moderate antithrombin deficiency (63–78%) carried potential regulatory mutations. One located 200 bp before the initiation ATG and two in intron 1. These mutations disrupted two out of five potential vitamin D receptor elements (VDRE) identified in SERPINC1 with different software. One genetic defect, c.42-1060_-1057dupTTGA, was a new low prevalent polymorphism (MAF: 0.01) with functional consequences on plasma antithrombin levels. The relevance of the vitamin D pathway on the regulation of SERPINC1 was confirmed in a cell model. Incubation of HepG2 with paricalcitol, a vitamin D analog, increased dose-dependently the levels of SERPINC1transcripts and antithrombin released to the conditioned medium. This study shows further evidence of the transcriptional regulation of SERPINC1 by vitamin D and first describes the functional and pathological relevance of mutations affecting VDRE of this gene. Our study opens new perspectives in the search of new genetic defects involved in antithrombin deficiency and the risk of thrombosis as well as in the design of new antithrombotic treatments.

Functional consequences of the prothrombotic SERPINC1 rs2227589 polymorphism on antithrombin levels

Genetic factors involved in the interindividual variability of antithrombin have not been identified. We studied two polymorphisms of the gene coding for antithrombin (SER-PINC1) in 298 Spanish Caucasian blood donors: rs3138521, a DNA length polymorphism located on the promoter region and rs2227589, a SNP located on intron 1 that has been described as a mild thrombotic risk factor. We detected a complete linkage disequilibrium between these polymorphisms (D'=0.999). The rs3138521 polymorphism has no functional consequences. However, the rs2227589 SNP significantly associated with plasma anti-FXa activity and antithrombin levels: carriers of the A allele had slightly but significantly lower anticoagulant activity and levels than GG subjects (97.0+/-7.3% vs. 94.6+/-8.4%; p=0.032; 99.5+/-5.8% vs. 94.8+/-5.6%; p=0.001; respectively). Our results identified a functional effect of the rs2227589 polymorphism not explained by its linkage with the promoter polymorphism that support the moderate thrombotic risk associated with the A allele.

Disruption of Nuclear Vitamin D Receptor Gene Causes Enhanced Thrombogenicity in Mice

Vitamin D metabolites influence the expression of various genes involved in calcium homeostasis, cell differentiation, and regulation of the immune system. Expression of these genes is mediated by the activation of the nuclear vitamin D receptor (VDR). Previous studies have shown that a hormonally active form of vitamin D, 1alpha,25-dihydroxyvitamin D3, exerts anticoagulant effects in cultured monocytic cells. To clarify whether activation of VDR plays any antithrombotic actions in vivo, hemostatic/thrombogenic systems were examined in normocalcemic VDR knock-out (KO) mice on a high calcium diet and compared with wild type and hypocalcemic VDRKO mice that were fed a regular diet. Platelet aggregation was enhanced significantly in normocalcemic VDRKO mice compared with wild type and hypocalcemic VDRKO mice. Aortic endothelial nitric-oxide (NO) synthase expression and urinary NOx excretions were reduced in hypocalcemic VDRKO mice, but not in normocalcemic VDRKO mice. Northern blot and RT-PCR analyses revealed that the gene expression of antithrombin in the liver as well as that of thrombomodulin in the aorta, liver and kidney was down-regulated in hypo- and normocalcemic VDRKO mice. Whereas tissue factor mRNA expression in the liver and kidney was up-regulated in VDRKO mice regardless of plasma calcium level. Furthermore, VDRKO mice manifested an exacerbated multi-organ thrombus formation after exogenous lipopolysaccharide injection regardless of the calcemic conditions. These results demonstrate that activation of nuclear VDR elicits antithrombotic effects in vivo, and suggest that the VDR system may play a physiological role in the maintenance of antithrombotic homeostasis.