Clostridium difficile (C.difficile) is considered to be the major cause of the antibiotic-associated diarrhea and pseudomembranous colitis in animals and humans.The prevalence of C.difficile infections (CDI) has been increasing since 2000.Two exotoxins of C.difficile,Toxin A (TcdA) and Toxin B (TcdB),are the main virulence factors of CDI,which can induce glucosylation of Rho GTPases in host cytosol,leading to cell morphological changes,cell apoptosis,and cell death.The mechanism of TcdB-induced cell death has been investigated for decades,but it is still not completely understood.It has been reported that TcdB induces endoplasmic reticulum stress via PERK-elF2α signaling pathway in CT26 cell line (BALB/C mouse colon tumor cells).In this study,we found that salubrinal,a selective inhibitor of elF2α dephosphorylation,efficiently protects CT26 cell line against TcdB-induced cell death and tried to explore the mechanism underlying in this protective effect.Our results demonstrated that salubrinal protects CT26 cells from TcdB-mediated cytotoxic and cytopathic effect,inhibits apoptosis and death of the toxin-exposed cells via caspase-9-dependent pathway,elF2α signaling pathway,and autophagy.These findings will be helpful for the development of CDI therapies.