Serum exosomal miR-150-5p in rheumatic heart disease-associated angiogenesis

The focus of this study is on Rheumatic heart disease (RHD), an autoimmune consequence of rheumatic fever leading to mitral valve damage. Aim is to explore the role of exosomes derived from RHD patients in promoting angiogenesis during RHD pathogenesis. Exosomes were isolated via column chromatography from the pericardial fluid (PF) and serum of RHD patients, pericardial fluid from non-RHD patients undergoing coronary artery bypass grafting (CABG) surgery, and serum of healthy individuals. These exosomes were characterized by transmission electron microscopy (TEM) and western blotting. Human umbilical vein endothelial cells (HUVECs) cultured from umbilical cord(s), were treated with purified exosomes from RHD, CABG patients or healthy individuals. Exosome treatment induced morphological changes in HUVECs, including elongation and tube-like structure formation.

The qRT-PCR gene expression analysis revealed significant upregulation of angiogenic markers (VEGF-A 2.7-fold, MMP2 1.5-fold) and inflammatory cytokine (IL-4 15.17-fold), in HUVECs stimulated with RHD serum exosomes. Conversely, there was downregulation of anti- angiogenic genes (RASA-1 0.65-fold and endostatin 0.4-fold). Notably, elevated levels of miR- 150-5p (34.29 + 9.524-fold mean difference; p= 0.0007) were detected in serum-derived exosomes from RHD patients compared to healthy controls. Stimulation of HUVECs with RHD serum exosomes resulted in reduction in the expression of TP53 (0.227-fold; p= 0.006), a known target of miR-150-5p. Furthermore, transfection of HUVECs with miR-150-5p mimics induced the formation of angiogenic endothelial tubes, underscoring the role of miR-150-5p in promoting angiogenesis.