STING inhibition suppresses butachlor-induced splenic macrophage pyroptosis and M1 polarization via cGAS-STING signaling

Butachlor (BTR), a globally prevalent amide herbicide, poses significant environmental health risks due to its bioaccumulation potential and documented chronic toxicity in mammalian systems. Given the spleen's pivotal role in orchestrating systemic immune homeostasis, this study investigated BTR-induced immunopathological mechanisms in ICR mice following 28-day subacute exposure (10 mg/kg). Histopathological examination revealed significant disorganization of the splenic marginal zone architecture, concomitant with ultrastructural mitochondrial abnormalities and a reduction in mitochondrial membrane potential (ΔΨm). Mitochondrial permeability transition pore opening triggered cytoplasmic translocation of mitochondrial DNA (mtDNA), activating the stimulator of interferon genes (STING) pathway—a master regulator of innate immunity. STING activation initiated bifurcated downstream signaling, evidenced by TBK1 phosphorylation and subsequent IRF3 / NF-κB nuclear translocation. This dual signaling cascade simultaneously executed immunogenic cell death via Gasdermin D-dependent pyroptosis (cleaved GSDMD-NT) and drove macrophage polarization (IFN-α / β, IL-1β, TNF-α). Crucially, pharmacological STING inhibition with C-176 attenuated both pyroptosis (GSDMD cleavage reduced) and inflammatory cytokine surge. Our findings not only pioneer the identification of the mtDNA-STING axis as the central mechanism underlying BTR-induced splenic immunotoxicity but also validate STING inactivation as a targeted strategy to mitigate herbicide-associated immune dysfunction. This work provides critical insights for environmental toxicant risk assessment and immunomodulatory.