Therapeutic Peptides Mitigates TLR4 Pathway Activation by Ang II in Renal and Vascular Smooth Muscle Cells

Angiotensin II (Ang II) plays a critical role in hypertension by activating toll-like receptors (TLRs), particularly TLR4, which contributes to end-organ damage and vascular injury. Ang 1-7, a by-product of the RAAS system, is known to counteract the deleterious effects of Ang II; however, the potential protective effects of the peptides, Ang 1-7 and BNP in Ang II induced TLR4 activation remain unexplored. Therefore, our study primarily focused on investigating the effects of Ang 1-7 and BNP on Ang II-induced TLR4 activation in renal and primary vascular smooth muscle cells (VSMCs). We utilized renal epithelial cells (RECs), renal fibroblasts (RFbs), and VSMCs to assess end-organ damage and vascular dysfunction mediated by Ang II. Gene expression of TLR4 and its downstream markers was evaluated via qPCR. Additionally, the impact of Ang 1-7 and BNP on inflammatory, hypertrophic and fibrotic markers was assessed using qPCR and immunocytochemistry. Ang II stimulation led to the upregulation of TLR4-mediated pathways in RECs and VSMCs, with a significant increase in hypertrophy, fibrosis, and inflammation observed in RECs and RFbs. Treatment with Ang 1-7 and BNP notably reduced TLR4-mediated injury markers and prevented the phenotypic switch. Furthermore, these peptides significantly inhibited Ang II-induced TLR4 pathways in primary VSMCs and RECs. Importantly, the Ang II-induced injury and phenotypic switch were driven by pro-inflammatory and fibrotic markers, which were reversed by peptide treatment. These findings suggest that Ang 1-7 and BNP offer a promising avenue for future research, peptide-based strategies for protecting vital organs.