Hyperglycaemia impairs antithrombin secretion: Possible contribution to the thrombotic risk of diabetes

COVID-19-associated coagulopathy and acute kidney injury in critically ill patients

OBJECTIVE

The incidence of thrombotic events and acute kidney injury is high in critically ill patients with COVID-19. We aimed to evaluate and compare the coagulation profiles of patients with COVID-19 developing acute kidney injury versus those who did not, during their intensive care unit stay.

METHODS

Conventional coagulation and platelet function tests, fibrinolysis, endogenous inhibitors of coagulation tests, and rotational thromboelastometry were conducted on days 0, 1, 3, 7, and 14 following intensive care unit admission.

RESULTS

Out of 30 patients included, 13 (43.4%) met the criteria for acute kidney injury. Comparing both groups, patients with acute kidney injury were older: 73 (60-84) versus 54 (47-64) years, p=0.027, and had a lower baseline glomerular filtration rate: 70 (51-81) versus 93 (83-106) mL/min/1.73m2, p=0.004. On day 1, D-dimer and fibrinogen levels were elevated but similar between groups: 1780 (1319-5517) versus 1794 (726-2324) ng/mL, p=0.145 and 608 (550-700) versus 642 (469-722) g/dL, p=0.95, respectively. Rotational thromboelastometry data were also similar between groups. However, antithrombin activity and protein C levels were lower in patients who developed acute kidney injury: 82 (75-92) versus 98 (90-116), p=0.028 and 70 (52-82) versus 88 (78-101) µ/mL, p=0.038, respectively. Mean protein C levels were lower in the group with acute kidney injury across multiple time points during their stay in the intensive care unit.

CONCLUSION

Critically ill patients experiencing acute kidney injury exhibited lower endogenous anticoagulant levels. Further studies are needed to understand the role of natural anticoagulants in the pathophysiology of acute kidney injury within this population.

Fatal deep venous thrombosis and pulmonary embolism secondary to melioidosis in China: case report and literature review

BACKGROUND

Burkholderia pseudomallei is a gram-negative bacterium and the causative pathogen of melioidosis, which manifests a variety ranges of infection symptoms. However, deep venous thrombosis (DVT) and pulmonary embolism (PE) secondary to bacteremic melioidosis are rarely documented in the literature. Herein, we reported a fatal case of melioidosis combined with DVT and PE.

CASE PRESENTATION

A 54-year-old male construction worker and farmer with a history of diabetes was febrile, painful in left thigh, swelling in left lower limb, with chest tightness and shortness of breath for 4 days. He was later diagnosed as DVT of left lower extremity and PE. The culture of his blood, sputum and bone marrow samples grew B. pseudomallei. The subject was administrated with antibiotics (levofloxacin, cefoperazone/tazobactam, and imipenem) according to antimicrobial susceptibility testing and low molecular heparin for venous thrombosis. However, even after appropriate treatment, the patient deteriorated rapidly, and died 2 weeks after admission.

CONCLUSIONS

This study enhanced awareness of the risk of B. pseudomallei bloodstream infection in those with diabetes. If a patient has predisposing factors of melioidosis, when DVT is suspected, active investigation and multiple therapeutic interventions should be implemented immediately to reduce mortality rate.

Effect of poor glycaemic control on plasma levels and activity of protein C, protein S, and antithrombin III in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) patients are predisposed to several diabetes-related complications. Dysregulation of the haemostatic mechanisms have been implicated. There are however no current studies assessing the levels and activity of protein C (PC), protein S (PS), and antithrombin III (AT III), which are essential in haemostatic regulation, in a single cohort of T2DM patients. This study evaluated the effect of poorly-managed T2DM on the levels and activity of PC, PS, and AT III.

METHODS

This cross-sectional study was conducted at the Diabetes Clinic, Cocoa Clinic in Kumasi, Ghana. A total of 242 T2DM patients, comprising 152 patients with poorly-managed diabetes and 90 well-managed diabetes patients, were recruited for the study. Fasting blood glucose, liver function tests and lipid profile were performed for each respondent. Glycated haemoglobin (HbA1c) was estimated by turbidimetric inhibition immunoassay. The levels and activity of PC, PS and AT III were measured by solid phase sandwich ELISA method.

RESULTS

There was a negative correlation between HbA1c and the levels and activity of PC, PS and AT III. The levels and activity of PC [(5.78 vs 4.64 μg/ml, p<0.0001) and (42.22 vs 36.21 U/ml, p = 0.01) respectively], PS [(22.55 vs 20.29 μg/ml, p = 0.010) and (235.94 vs 211.67 U/ml, p<0.0001) respectively] and AT III [(16.28 vs 14.41μg/ml, p<0.0001) and (176.01 vs 160.09 U/ml, p = 0.03) respectively] were significantly increased in patients with well-managed T2DM compared to the poorly-managed diabetes patients. Likewise, the levels and activity of PC, PS, and AT III was higher among T2DM patients using statins than patients who were statin-naïve. Among patients with well-managed T2DM, those who were on statins had significantly higher levels and activities of PC, PS, and AT III compared to well-managed T2DM patients not on statins. However, there no statistically significant differences between the level and activity of PC, PS, and AT III among poorly-managed T2DM patients with respect to statin status.

CONCLUSION

Poorly-managed type 2 diabetes mellitus is associated with reduced levels and activity of PC, PS and AT III compared to well-managed T2DM. Though use of statins may improve the levels and activity of the PC, PS and AT III in T2DM, their effect is limited in the presence of poorly-controlled T2DM. Proper management of diabetes is essential to reduce the likelihood of thrombotic events among T2DM patients.

Is diabetes a hypercoagulable state? A critical appraisal

Diabetes mellitus (DM), a chronic disease with an increasing incidence and prevalence worldwide, is an established risk factor for arterial cardiovascular, cerebrovascular and peripheral vascular diseases including acute myocardial infarction, stroke and peripheral artery disease. On the other hand, its role as independent risk factor for venous thromboembolism (VTE) and for cardioembolic stroke or systemic embolism (SE) in patients with atrial fibrillation (AF) is more conflicting. Venous and arterial thromboses have traditionally been regarded as separate diseases, but recent studies have documented an association between these vascular complications. Cardiovascular risk factors may contribute to unprovoked VTE, and VTE may be an early symptomatic event in patients at high cardiovascular risk, including diabetic patients. Compelling evidences suggest that DM is associated with a higher risk of development and progression of AF. Furthermore, in AF patients with a coexisting DM the risk of cardioembolic stroke/SE appeared increased. Thus, DM has been included as one of the items of the CHADS2 score and of the subsequent CHA2DS2-VASc score that have been developed to assess the arterial tromboembolic risk of AF patients. Such a high incidence of thromboembolic events observed in these clinical subsets may be attributable to the DM-related prothrombotic state due to a number of changes in primary and secondary hemostasis. Although of potential clinical interest, unfortunately, to date, no study has properly evaluated the effects of drugs used to control blood glucose levels on the risk of venous thromboembolism and arterial cardioembolic events in patients with DM.

Quantitative analysis of the murine lipid droplet-associated proteome during diet-induced hepatic steatosis

Hepatic steatosis is characterized by the accumulation of lipid droplets (LDs), which are composed of a neutral lipid core surrounded by a phospholipid monolayer embedded with many proteins. Although the LD-associated proteome has been investigated in multiple tissues and organisms, the dynamic changes in the murine LD-associated proteome in response to obesity and hepatic steatosis have not been studied. We characterized the hepatic LD-associated proteome of C57BL/6J male mouse livers following high-fat feeding using isobaric tagging for relative and absolute quantification. Of the 1,520 proteins identified with a 5% local false discovery rate, we report a total of 48 proteins that were increased and 52 proteins that were decreased on LDs in response to high-fat feeding. Most notably, ribosomal and endoplasmic reticulum proteins were increased and extracellular and cytosolic proteins were decreased in response to high-fat feeding. Additionally, many proteins involved in fatty acid catabolism or xenobiotic metabolism were enriched in the LD fraction following high-fat feeding. In contrast, proteins involved in glucose metabolism and liver X receptor or retinoid X receptor activation were decreased on LDs of high-fat-fed mice. This study provides insights into unique biological functions of hepatic LDs under normal and steatotic conditions.

The hyperglycemic byproduct methylglyoxal impairs anticoagulant activity through covalent adduction of antithrombin III

INTRODUCTION

The blood coagulation system is a tightly regulated balance of procoagulant and anticoagulant factors, disruption of which can cause clinical complications. Diabetics are known to have a hypercoagulable phenotype, along with increased circulating levels of methylglyoxal (MGO) and decreased activity of the anticoagulant plasma protein antithrombin III (ATIII). MGO has been shown to inhibit ATIII activity in vitro, however the mechanism of inhibition is incompletely understood. As such, we designed this study to investigate the kinetics and mechanism of MGO-mediated ATIII inhibition.

METHODS

MGO-mediated ATIII inhibition was confirmed using inverse experiments detecting activity of the ATIII targets thrombin and factor Xa. Fluorogenic assays were performed in both PBS and plasma after incubation of ATIII with MGO, at molar ratios comparable to those observed in the plasma of diabetic patients. LC-coupled tandem mass spectrometry was utilized to investigate the exact mechanism of MGO-mediated ATIII inhibition.

RESULTS AND CONCLUSIONS

MGO concentration-dependently attenuated inhibition of thrombin and factor Xa by ATIII in PBS-based assays, both in the presence and absence of heparin. In addition, MGO concentration-dependently inhibited ATIII activity in a plasma-based system, to the level of plasma completely deficient in ATIII, again both in the presence and absence of heparin. Results from LC-MS/MS experiments revealed that MGO covalently adducts the active site Arg 393 of ATIII through two distinct glyoxalation mechanisms. We posit that active site adduction is the mechanism of MGO-mediated inhibition of ATIII, and thus contributes to the underlying pathophysiology of the diabetic hypercoagulable state and complications thereof.

The infective polymerization of conformationally unstable antithrombin mutants may play a role in the clinical severity of antithrombin deficiency

Mutations affecting mobile domains of antithrombin induce conformational instability resulting in protein polymerization that associates with a severe clinical phenotype, probably by an unknown gain of function. By homology with other conformational diseases, we speculated that these variants might infect wild-type (WT) monomers reducing the anticoagulant capacity. Infective polymerization of WT polymers and different P1 mutants (p.R425del, p.R425C and p.R425H) were evaluated by using native gels and radiolabeled WT monomers and functional assays. Human embryonic kidney cells expressing the Epstein-Barr nuclear antigen 1 (HEK-EBNA) cells expressing inducible (p.R425del) or two novel constitutive (p.F271S and p.M370T) conformational variants were used to evaluate intracellular and secreted antithrombin under mild stress (pH 6.5 and 39°C for 5 h). We demonstrated the conformational sensitivity of antithrombin London (p.R425del) to form polymers under mild heating. Under these conditions purified antithrombin London recruited WT monomers into growing polymers, reducing the anticoagulant activity. This process was also observed in the plasma of patients with p.R425del, p.R425C and p.R425H mutations. Under moderate stress, coexpression of WT and conformational variants in HEK-EBNA cells increased the intracellular retention of antithrombin and the formation of disulfide-linked polymers, which correlated with impaired secretion and reduction of anticoagulant activity in the medium. Therefore, mutations inducing conformational instability in antithrombin allow its polymerization with the subsequent loss of function, which under stress could sequestrate WT monomers, resulting in a new prothrombotic gain of function, particularly relevant for intracellular antithrombin. The in vitro results suggest a temporal and severe plasma antithrombin deficiency that may contribute to the development of the thrombotic event and to the clinical severity of these mutations.

α-1-antitrypsin gene delivery reduces inflammation, increases T-regulatory cell population size and prevents islet allograft rejection

Antiinflammatory clinical-grade, plasma-derived human α-1 antitrypsin (hAAT) protects islets from allorejection as well as from autoimmune destruction. hAAT also interferes with disease progression in experimental autoimmune encephalomyelitis (EAE) and in collagen-induced arthritis (CIA) mouse models. hAAT increases IL-1 receptor antagonist expression in human mononuclear cells and T-regulatory (Treg) cell population size in animal models. Clinical-grade hAAT contains plasma impurities, multiple hAAT isoforms and various states of inactive hAAT. We thus wished to establish islet-protective activities and effect on Treg cells of plasmid-derived circulating hAAT in whole animals. Islet function was assessed in mice that received allogeneic islet transplants after mice were given hydrodynamic tail-vein injection with pEF-hAAT, a previously described Epstein-Barr virus (EBV) plasmid construct containing the EBV nuclear antigen 1 (EBNA1) and the family of repeat EBNA1 binding site components (designated "EF") alongside the hAAT gene. Sera collected from hAAT-expressing mice were added to lipopolysaccharide (LPS)-stimulated macrophages to assess macrophage responsiveness. Also, maturation of peritoneal cells from hAAT-expressing mice was evaluated. hAAT-expressing mice accepted islet allografts (n = 11), whereas phosphate-buffered saline-injected animals (n = 11), as well as mice treated with truncated-hAAT-plasmid (n = 6) and untreated animals (n = 20) rapidly rejected islet allografts. In hAAT-expressing animals, local Treg cells were abundant at graft sites, and the IL-1 receptor antagonist was elevated in grafts and circulation. Sera from hAAT-expressing mice, but not control mice, inhibited macrophage responses. Finally, peritoneal cells from hAAT-expressing mice exhibited a semimature phenotype. We conclude that plasmid-derived circulating hAAT protects islet allografts from acute rejection, and human plasma impurities are unrelated to islet protection. Future studies may use this in vivo approach to examine the structure-function characteristics of the protective activities of AAT by manipulation of the hAAT plasmid.