Immune Response Gene-1 [IRG1]/itaconate protect against multi-organ injury via inhibiting gasdermin D-mediated pyroptosis and inflammatory response

Abstract

Sepsis is a multiple organ dysfunction syndrome due to a dysregulated response to infection with unacceptably high mortality. Currently, no effective treatment exists for sepsis. IRG1/itaconate has been considered to play a protective role for various inflammatory diseases. In the present study, we explored the protective role and mechanisms of IRG1/itaconate on lipopolysaccharide (LPS)-induced multi-organ injury. The LPS-induced sepsis model was used. IRG1^-/- and wild type mice were used to explore the protective role of IRG1/itaconate on multi-organ injury. GSDMD^-/- mice were used to explore the effect of GSDMD-mediated pyroptosis on LPS-induced model. RAW264.7 cells and bone-marrow-derived macrophages (BMDMs) were used for in vitro studies. In vivo experiments, we found IRG1 deficiency aggravated LPS-induced multi-organ injury especially lung injury. 4-Octyl itaconate (4-OI), a derivative of itaconate, significantly ameliorated LPS-induced acute lung, liver, and kidney injury. Furthermore, IRG1/4-OI decreased serum interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) level, macrophage infiltration, and TUNEL-positive cells in lung and liver tissue. Western blot showed IRG1/itaconate decreased the expressions of p-ERK, p-P38, p-JNK, and p-P65 and increased the expression of Nrf2/HO-1 in lung tissue. Meanwhile, 4-OI inhibited the expression of GSDMD-N. In vitro experiments, 4-OI inhibited ROS production and promoted apoptosis under LPS stimulation in RAW264.7 cells. Furthermore, 4-OI inhibited nuclear factor-kappaB/mitogen-activated protein kinase pathways and GSDMD-medicated pyroptosis in BMDMs. Finally, we used GSDMD^-/- mice to explore the effect of pyroptosis on LPS-induced multi-organ injury. The results showed that GSDMD deficiency significantly ameliorated lung injury. In conclusion, our data demonstrated that IRG1/itaconate protect against multi-organ injury via inhibiting inflammation response and GSDMD-indicated pyroptosis, which may be a promising agent for protecting against sepsis.

Keywords: Inflammation; LPS; Multi-organ injury; Pyroptosis; Sepsis.