DN203316, a novel PPARδ agonist, suppresses ferroptotic signaling and fibrogenesis in metabolic dysfunction-associated steatohepatitis

Recently, ferroptosis has emerged as a pathogenic mechanism that drives metabolic dysfunction-associated steatohepatitis (MASH); however, the upstream triggers and their relevance to fibrosis remain poorly understood. Here we identified dietary cholesterol-induced ferroptosis and the downregulation of peroxisome proliferator-activated receptor delta (PPARδ) as central drivers of MASH pathogenesis. To investigate this, human liver samples and cholesterol-enriched dietary murine models of MASH were examined in parallel with mechanistic studies in hepatocytes and hepatic stellate cells (HSCs). Cholesterol-induced MASH was associated with pronounced hepatic lipid peroxidation and the selective downregulation of PPARδ. The loss of PPARδ disrupted redox homeostasis and sensitized hepatocytes to ferroptosis, whereas exosomal double-stranded DNA released from ferroptotic hepatocytes activated STING-TBK1-IRF3 and induced expression of profibrotic genes in HSCs. These effects were reversed by either overexpression of hepatocyte-specific PPARδ or pharmacologic treatment with DN203316, a novel and highly selective PPARδ agonist. In vivo, DN203316 mitigated ferroptosis, inflammation and fibrosis without inducing metabolic derangement. These findings were substantiated by clinical data demonstrating a marked increase in lipid peroxidation and STING-driven HSC activation in liver tissues from patients with MASH. In conclusion, PPARδ is a key regulator of cholesterol-induced ferroptosis and exosome-mediated fibrogenic signaling in MASH. DN203316 offers a promising therapeutic strategy to suppress ferroptosis, disrupt hepatocyte-HSC crosstalk and attenuate disease progression.