Nifuroxazide Pretreatment Protects Against Acute CdCl2 Exposure-Induced Toxicity via Modulating the USP21/AIM2 Inflammasome Axis.

Cadmium (Cd) is a ubiquitous environmental pollutant with an exceptionally long biological half-life (10-30 years) and high multi-organ toxicity. While chronic cadmium exposure has been extensively studied, the pathological mechanisms and prophylactic strategies for acute cadmium poisoning remain poorly defined. Here, we established an acute cadmium intoxication model in C57BL/6 mice via intraperitoneal injection of CdCl2 (5 mg/kg) and assessed pathological and molecular changes 12 h post-exposure. Histopathological examination revealed overt hepatic damage and mild extrahepatic changes in kidney and spleen. Mechanistically, acute cadmium challenge disrupted systemic redox homeostasis, as evidenced by significant reductions in superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and total antioxidant capacity (T-AOC). Concurrently, cadmium triggered a robust inflammatory response, upregulating pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and lactate dehydrogenase (LDH) release, and activated the pyroptotic pathway, as shown by elevated cleaved caspase-1 and GSDMD-N levels. To identify potential prophylactic agents, we investigated nifuroxazide (NFX), a multifunctional agent with known anti-cancer, antioxidant, and anti-inflammatory properties. Our results indicate that NFX pretreatment protects against cadmium-induced acute liver injury. Mechanistically, these data support the involvement of the USP21-AIM2 axis in this protection. USP21, a deubiquitinase, stabilizes AIM2 by removing its ubiquitin chains. Cadmium exposure increased USP21-mediated AIM2 deubiquitination, decreased AIM2 ubiquitination, and promoted AIM2 protein accumulation, accompanied by AIM2 inflammasome activation and hepatic stellate cell pyroptosis. In contrast, NFX pretreatment was associated with reduced USP21-mediated AIM2 deubiquitination, increased AIM2 ubiquitination and reduced AIM2 protein accumulation, and suppressed hepatic stellate cell pyroptosis. Collectively, these findings indicate that NFX pretreatment protects against acute CdCl2-induced hepatic injury with mild improvements in extrahepatic tissue histology, and support the involvement of the USP21-AIM2 axis in regulating AIM2 inflammasome protein stability.