Inhibiting interferon regulatory factor 5 attenuates endothelial mesenchymal transition (1152.5)

Abstract

Introduction: Systemic Sclerosis (SSc) is an autoimmune connective tissue disease characterized by oxidative stress, fibrosis and inflammation of skin and internal organs. Tight skin (Tsk/+) mice are an established model of SSc that displays inflammatory and fibrotic features that are consistent with SSc. When endothelial cells (ECs) are cultured on extracellular matrix (ECM) isolated from the skin of Tsk/+ mice they undergo endothelial mesenchymal transition (EndoMT). 4F, an apoA‐I mimetic that inhibits atherosclerosis by many mechanisms, not only decreases myocardial fibrosis in Tsk/+ mice but also decreases interferon regulator factor 5 (IRF5), a transcription factor considered a molecular switch for autoimmunity. The goal of the present study was to determine if directly targeting IRF5 reduces inflammation and oxidative stress in ECs cultured on cardiac ECM of Tsk/+ mice. Methods: KEP20 was designed and developed to specifically inhibit IRF5.The oxidative state of cardiac ECM was determined using the advanced oxidized protein product (AOPP) assay and western blot analysis for 3‐Nitrotyrosine and advanced glycation end products (AGE). ECs were cultured on Tsk/+ cardiac ECM and effects on expression of TGF β, Twist, collagen‐I in ECs ± KEP20 were determined by western blot analysis. Results: Tsk/+ ECM increase the levels of AOPP (13%), 3‐Nitrotyrosine (21%), and AGE (86%) in EC cultures as compared to EC maintained on cardiac ECM C57BL/6J. KEP20 treatments (50µg/mL) of EC cultured on Tsk/+ ECM reduces expression of TGFβ (221%), Twist (35 ± 14.51%), Collagen‐I (137%) compared ECs on Tsk/+ ECM. KEP20 also reduces Twist by 73%, TGFβ by 34% and collagen‐I by 56% compared to the levels in ECs on Tsk/+ ECM. Conclusion: These data indicate inhibiting IRF5 prevents Tsk/+ cardiac matrix from inducing EndoMT as well as increasing EC inflammation and fibrosis and demonstrate that IRF5 is a novel therapeutic target for SSc.