Investigating the Therapeutic Potential of IAP Antagonism for the Treatment of Duchenne Muscular Dystrophy

Abstract

Duchenne muscular dystrophy (DMD) is a severe, X-linked genetic disorder characterized by progressive muscle degeneration and fibrosis due to the absence of dystrophin. Despite advancements in supportive care, current treatments remain palliative, underscoring the urgent need for therapies targeting fibrosis and inflammation to improve patient outcomes. While the role of inhibitor of apoptosis proteins (IAPs), particularly cellular-IAPs 1 and 2 (cIAP1/2) in skeletal muscle pathology are increasingly recognized, their specific contribution to muscle fibrosis and the inflammatory response in DMD remains poorly understood. This study investigated the therapeutic potential of LCL161, a Second Mitochondria-derived Activator of Caspases (SMAC) mimetic targeting cIAP1/2, in both adult and juvenile D2.mdx mice, a severe mouse model of DMD. Using a comprehensive approach combining functional, histological and biochemical analyses, I evaluated the impact of LCL161 on muscle pathology. In adult D2.mdx mice, LCL161 treatment showed marginal effects on muscle damage and strength, with a trend toward reduced fibrosis in the gastrocnemius muscle and modulation of the cytokine/chemokine profile. Conversely, juvenile D2.mdx mice exhibited reduced muscle damage without improved grip strength, accompanied by increased necrosis in the gastrocnemius and significant decreases in Tnfα and Pax7 expression. The muscle and age-dependent responses suggest that the therapeutic efficacy of LCL161 is influenced by the timing and severity of disease progression. This warrants further investigation into the mechanisms by which IAP inhibition influences muscle regeneration, inflammation, and fibrosis in DMD.