Apelin-13 regulated thrombotic inflammation and induced homing of EPCs to promote the dissolution and recanalization of deep vein thrombosis.

Abstract

BACKGROUND: Deep vein thrombosis (DVT) remains a major vascular challenge, characterized by thrombotic inflammation and impaired vascular recanalization. Apelin-13, a bioactive peptide with anti-inflammatory and angiogenic properties, may modulate thrombotic inflammation and enhance endothelial progenitor cells (EPCs) mediated repair. METHODS: A Sprague-Dawley (SD) rat DVT model was established via inferior vena cava (IVC) ligation to investigate Apelin-13's effects on thrombotic inflammation and EPC homing. EPC migration, homing, and differentiation were assessed using Transwell assay, tube formation assay, and immunofluorescence staining for Cluster of Differentiation 34 (CD34)/Ulex Europaeus Agglutinin-1 (UEA-1). In vivo, thrombus dissolution, reendothelialization, and vascular recanalization were evaluated via histomorphometry and immunofluorescence  (CD34, CD31, vWF, Ki67). Pro-inflammatory cytokines (IL-1β, IL-6), pro-angiogenic factors (VEGFA, FGF-2, Ang-1), and vascular active substances (NO, ET-1) were quantified by ELISA. Western blot, co-immunoprecipitation, cellular thermal shift assay, and HDAC activity assays were used to explore the epigenetic mechanism. RESULTS: Exogenous Apelin-13 administration significantly reduced thrombus weight/length, enhanced vascular recanalization, inhibited inflammatory cell infiltration and IL-1β/IL-6 expression, and reduced thrombus cell apoptosis. In vitro, Apelin-13 promoted EPC proliferation, migration, invasion tube formation via APLNR. Mechanistically, Apelin-13 directly interacted with HDAC1, reducing its thermal stability and global HDAC activity, which enhanced histone acetylation (H3K27AC, H3K9AC) at the CXCR4 promoter and upregulated CXCR4 expression. These effects were abrogated by ML221 (APLNR antagonist), AMD3100 (CXCR4 inhibitor), or HDAC1 overexpression. Additionally, Apelin-13 regulated platelet aggregation and upregulated VEGFA, FGF-2, and Ang-1 expression, while downregulating ET-1. CONCLUSION: Apelin-13 promotes thrombus resolution and vascular repair in DVT by suppressing thrombotic inflammation and enhancing EPC function via the APLNR-HDAC1-CXCR4 signaling. These findings offered a novel strategy for improving clinical outcomes.