Redox imbalance and NF-κB activation drives 1,3-diphenylguanidine (DPG)-induced hepatotoxicity in grass carp (Ctenopharyngodon idella): HSP70 as a protective therapeutic target.

As a widely utilized rubber vulcanization agent, 1,3-diphenylguanidine (DPG) has been identified as inherently toxic to aquatic organisms. The study elucidates the molecular pathways of DPG-induced hepatotoxicity and evaluates potential therapeutic strategies. In this study, grass carp exposed to DPG exhibited mild to moderate hepatic edema, sinusoidal congestion, with serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels elevated by 25.0 % and 46.3 %, respectively. Furthermore, a 2.46-fold increase in TUNEL-positive hepatocytes was observed following DPG exposure. RNA-sequencing analysis revealed significant upregulation of pro-inflammatory genes, autophagy-related genes, oxidative stress regulators and heat shock protein 70 (HSP70). Meanwhile, DPG exposure induces hepatic oxidative injury, but nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activation is unable to counteract reactive oxygen species (ROS) accumulation. Additional experiments demonstrated that DPG exposure induced nuclear factor κB (NF-κB)-mediated inflammation and excessive autophagy in the liver. Moreover, immunohistochemistry and Western blot analyses indicated a significant increase in HSP70 protein expression following DPG exposure. Spearman correlation analysis revealed positive associations between HSP70 and inflammation-related genes and heme oxygenase-1 (HO-1) after DPG exposure. In vitro experiments demonstrated that the HSP70 agonist ML346 effectively reduced hepatocyte inflammation and apoptosis. Collectively, our study demonstrated that DPG exert hepatotoxic effects by disrupting redox balance, promoting NF-κB-mediated inflammation and excessive autophagy. Targeting HSP70 may represent a promising strategy for mitigating DPG-induced liver injury, proposing a potential solution for DPG-related aquatic toxicity.