Chronic Intermittent Hypoxia Exacerbates High-Fat Diet-Induced MASLD Through Lipid Metabolic Reprogramming, Impaired Antioxidant Defense, and NF-κB/NLRP3 Activation.

Chronic intermittent hypoxia (CIH), the cardinal pathophysiological feature of obstructive sleep apnea, is increasingly recognized as an important modifier of metabolic dysfunction-associated steatotic liver disease (MASLD), but the underlying mechanisms remain incompletely understood. In this study, male C57BL/6 mice were fed a standard diet or a high-fat diet (HFD) and exposed to normoxia or CIH for 8 weeks. Histological, ultrastructural, biochemical, transcriptomic, proteomic, and metabolomic analyses were integrated to characterize hepatic alterations induced by CIH under metabolic stress. CIH markedly aggravated HFD-induced liver injury, as evidenced by increased body fat, hepatomegaly, serum transaminases, steatosis, mitochondrial ultrastructural alterations, and inflammatory infiltration. Mechanistically, CIH promoted hepatic lipid metabolic reprogramming by suppressing the PPARα/CPT1A fatty acid β-oxidation axis while enhancing the SREBP-1c/FASN/PLIN2 lipogenic pathway, impaired the Nrf2/HO-1/SLC7A11/GPX4 antioxidant defense system, increased lipid peroxidation and iron accumulation, and activated NF-κB/NLRP3 signaling. These findings support a multifactorial model in which CIH functions as an additional hypoxic stressor that exacerbates HFD-induced MASLD-like liver injury through coordinated metabolic, oxidative, and inflammatory dysregulation.