Modulating the rate of fibrin formation and clot structure attenuates microvascular thrombosis in systemic inflammation

Abstract

Systemic inflammation can lead to coagulopathy and disseminated intravascular coagulation (DIC). In prior studies, the recombinant A2 domain of human von Willebrand factor (VWF; A2 protein) attenuated DIC and decreased mortality in lipopolysaccharide (LPS)-treated mice. Here, we performed studies to dissect the mechanism by which the A2 protein moderates DIC. We used confocal microscopy to analyze the fibrin clot structure in plasma from healthy humans and endotoxemic mice, turbidity assays to examine fibrin polymerization, and a murine model for LPS-induced DIC and introduced a loss-of-function mutation into the A2 protein for fibrin. The mutation of the residue E1567 located in the α2 helix of the folded A2 domain of VWF inhibited binding activity for fibrin, possibly mapping a novel region containing a putative binding site for fibrin. The A2 protein increased the initial rate of change of fibrin polymerization, intercalated into the fibrin network, and modified the resultant clot structure in vitro. Furthermore, ex vivo experiments using plasma from mice with endotoxemia treated with the A2 protein revealed an increased rate of fibrin formation and an altered clot structure as compared with plasma from nontreated sick animals. Moreover, and in contrast to the A2 mutant, the A2 protein improved survival and reduced fibrin deposition and microvascular thrombosis in mice with endotoxemia-induced DIC. Importantly, in vivo and in vitro studies indicated that the A2 protein did not affect experimental thrombosis. Thus, we provide evidence for a novel treatment to attenuate systemic inflammation-induced coagulopathy/DIC via targeting fibrin formation, without an increased risk for bleeding.

Endothelial METTL3 (Methyltransferase-Like 3) Inhibits Fibrinolysis by Promoting PAI-1 (Plasminogen Activator Inhibitor-1) Expression Through Enhancing Jun Proto-Oncogene N6-Methyladenosine Modification

“…To identify the role of METTL3 in fibrin formation and fibrinolysis, fibrin formation and fibrinolysis assays 22 , 24 , 32 were carried out in shMETTL3 HUVECs and scramble HUVECs. As shown in Figure 1 H, the final peak turbidities of clots and the time to reach the maximum turbidity were similar in shMETTL3 and scramble HUVECs, but knockdown of METTL3 enhanced fibrinolysis compared with the scramble HUVECs (Figure 1 H).…”

Identification of Thrombosis-Related Genes in Patients with Advanced Gastric Cancer: Data from AGAMENON-SEOM Registry

“…SAA1 has been connected suppressing the microbial-induced inflammation and tissue damage [ 34 ], a protective action in gastric cancer, considering that it is often associated with infections, such as Helicobacter pylori infection [ 35 ]. Given this anti-inflammatory activity, SAA1 could contribute to avoid thrombosis, inasmuch as inflammatory mechanisms can lead to the development of thrombosis [ 36 ]. Nevertheless, there are also other studies that support this gene’s proinflammatory activity [ 37 ]; therefore, its involvement in the inflammation-thrombosis nexus remains subject to debate.…”

Severity-stratified and longitudinal analysis of VWF/ADAMTS13 imbalance, altered fibrin crosslinking and inhibition of fibrinolysis as contributors to COVID-19 coagulopathy

“…There is also a relatively weak correlation between fibrinogen concentration and initial rate (R 2 =0.19, p=0.003). Instead, the alteration is likely the result of increased incorporation of VWF into the fibrin network 40, 41 and FXIII-mediated fibrin fibre compaction 42 . This is supported by a significant correlation between initial rate and both VWF (R 2= 0.45, p<0.0001) and FXIII (R 2 =0.30, p=0.0002) and by a longitudinal relationship between FXIII (increasing to above the normal range) and increased initial rate in patient 21.…”