Gourhant, L. | bioRxiv Science

bioRxiv2026

HDAC6 is a novel regulator of endothelial-to-mesenchymal transition in venous thrombosis

Background: Venous thromboembolism (VTE), which encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE), is a frequent disease associated with thrombus formation and vein wall remodeling. Hence, fibrosis might result from endothelial-to-mesenchymal transition (EndMT), characterized by the loss of endothelial markers and the acquisition of mesenchymal markers. In chronic thromboembolic pulmonary hypertension, transforming growth factor (TGF{beta}), the most potent inducer of EndMT, impairs thrombus resolution. However, the molecular mechanisms implicated in TGF[beta] signaling in the context of VTE are unknown. We hypothesized that epigenetic processes regulate the TGF{beta} signaling pathway in endothelial cells promoting EndMT and vascular fibrosis. Aims: To determine if the histone deacetylase 6 (HDAC6) regulates the TGF{beta} signaling pathway in endothelial cells promoting EndMT and delays venous thrombosis. Methods: To study the role of HDAC6 in EndMT, endothelial cells were treated with a pharmacological inhibitor (TCS20b) and incubated with TGF{beta} and thrombin for 2, 3, and 5 days. Real time PCR and Western blot were performed to analyze endothelial and mesenchymal marker expression and TGF{beta} signaling. An experimental model of VTE was used to study the role of HDAC6 on thrombus size overtime. Animals were treated or not with a specific HDAC6 inhibitor (tubastatin A) for 7 to 21 days. Analysis of RNAseq data sets publicly available were used to confirm our main results. Within group and treatment differences were analyzed using two-way ANOVA and Tukeys multiple comparisons. Results: Expression of the mesenchymal markers, calponin and transgelin, was increased by TGF{beta} and thrombin. Interestingly these changes were inhibited in presence of TCS20b. TGF{beta} mediated these effects through ERK1/2 and HDAC6 activation. Inhibition of HDAC6 in vivo reduced thrombus size 7 days after surgery compared to controls. This was associated with reduced expression of the EndMT marker transgelin in endothelial cells compared to the control animals. We found that FN1-EDA expression was associated with EndMT and regulated by HDAC6 in vitro. This marker was also associated with thrombosis in the RNAseq data set that we analyzed and potentially in patients with recurrent DVT. Conclusion: We found that HDAC6 regulates EndMT in venous thrombosis and impairs thrombus resolution. HDAC6 also regulates expression FN1-EDA that appears to be a strong marker associated with DVT and DVT recurrence. Thus, HDAC6 might represent an attractive therapeutic target for patients with a high risk of recurrent VTE.

physiology↗

bioRxiv2024

Extracellular RNA induce neutrophil recruitment via endothelial TLR3 during venous thrombosis after vascular injury

BackgroundVenous thromboembolism is associated with endothelial cell activation that contributes to the inflammation-dependent activation of the coagulation system. Cellular damages are associated with the release of different species of extracellular RNA (eRNA) involved in inflammation and coagulation. TLR3, which recognizes (viral) double-stranded RNA, single-stranded RNA, and also self-RNA fragments might be the receptor of these eRNA during venous thromboembolism. We investigate how eRNA regulate endothelial function through TLR3 and contribute to venous thromboembolism. Methods and ResultsThrombus formation and size in WT and TLR3 deficient (-/-) mice were monitored by ultrasonography after venous thrombosis using the FeCl3 and stasis models. Mice were treated with RNase1, poly(I:C) or RNA extracted from murine endothelial cells (eRNA). Gene expression and signaling pathway activation were analyzed in HEK293T cells overexpressing TLR3 in response to eRNA or in HUVECs transfected with a siRNA against TLR3. Plasma clot formation on treated HUVECs was analyzed. Thrombosis exacerbated RNA release in vivo and increased RNA content within the thrombus. RNase1 treatment reduced thrombus size compared to vehicle-treated mice. Poly(I:C) and eRNA treatments increased thrombus size in WT mice, but not in TLR3-/- mice, by bolstering neutrophil recruitment. Mechanistically, TLR3 activation in endothelial cells promotes CXCL5 secretion and neutrophil recruitment in vitro. eRNA triggered plasma clot formation. eRNA mediate these effects through TLR3-dependent activation of NF{kappa}B. ConclusionsWe show that eRNA and TLR3 activation enhance venous thromboembolism through neutrophil recruitment and secretion of CXCL5.

physiology↗