The Study On Protective Regulation Mechanism Of Bacterial Component Blp On Escherichia Coli-induced Inflammatory Responses In Mice

Escherichia coli(E.coli),a gram-negative bacterium,is an important pathogen that causes several mammalian diseases.In fact,the outer membrane components of E.coli,lipopolysaccharide(LPS)and bacterial lipoprotein,can induce host innate immune response through Toll-like receptor 4(TLR4)and TLR2,respectively.However,the detailed roles of E.coli Braun lipoprotein(BLP)in the regulation of host inflammatory response to E.coli infection remain unclear.In this study,we sought to determine the effects of BLP on E.coliinduced host inflammatory response and lethality using mouse models.Experiments using the pathogenic E.coli wild-type(WT)strain(BLP-positive),E.coli DH5α strain(BLPpositive),and E.coli JE5505 strain(BLP-negative)indicated that the presence of BLP could attenuate E.coli-induced inflammatory responses in mice,which is characterized by alleviated mortality and organ(liver and lung)damage,and decreased proinflammatory cytokine(TNF-α and IL-1β)and chemokine(RANTES)production in mouse serum and organs.Furthermore,compared to E.coli JE5505,BLP-positive strains and E.coli JE5505 combined with BLP treatment induced enhanced anti-inflammatory cytokine(IL-10)production in mouse serum and organs.These findings align with those observed in WT E.coli-and E.coli JE5505-stimulated mouse peritoneal macrophages.Altogether,our results demonstrate that the bacterial component BLP plays crucial and protective roles in E.coliinfected mice by regulating the production of inflammatory mediators,which may influence the outcome of inflammation in host response to E.coli infection.