Polychlorinated Biphenyl 138 Induces Toxicant-Associated Steatohepatitis via Hepatic Iron Overload and Adipose Inflammation.

Toxicant-associated steatohepatitis (TASH) is caused by environmental toxicants rather than metabolic factors; however, its pathogenic mechanisms remain poorly understood. Polychlorinated biphenyl 138 (PCB138), a persistent lipophilic contaminant that bioaccumulates in adipose tissue, may promote TASH through unclear mechanisms. In this study, we investigated whether PCB138 induces liver injury via hepatic iron dysregulation and adipose-liver inflammatory signaling. Male C57BL/6 mice received intraperitoneal PCB138 (1, 5, 10, or 50 mg/kg, four injections over six weeks). HepG2 hepatocytes were treated with PCB138 with or without ferric ammonium citrate (FAC), and PCB138-exposed 3T3-L1 adipocytes were co-cultured with HepG2 cells using a Transwell system. PCB138 dose-dependently increased serum transaminase and hepatic non-heme iron levels, with Hamp upregulation, macrophage infiltration, and fibrosis. In HepG2 cells, PCB138 synergized with FAC to elevate intracellular Fe2+, induced Hamp, suppressed Slc40a1, and upregulated inflammatory/profibrotic genes. In Transwell co-cultures, TNF-α, IL-6, and IL-1β from PCB138-exposed adipocytes amplified hepatic iron dysregulation and fibrotic responses. These findings demonstrated that PCB138 induced TASH through hepatic iron dysregulation and adipose-derived inflammatory signaling, independent of steatosis. These results highlighted the iron-adipose axis as a novel mechanistic link between PCB138 exposure and liver injury, offering potential therapeutic targets.