title: A balanced IL-1β activity is required for host response to Citrobacter rodentium infection.
abstract: Microbial sensing plays essential roles in the innate immune response to pathogens. In particular, NLRP3 forms a multiprotein inflammasome complex responsible for the maturation of interleukin (IL)-1β. Our aim was to delineate the role of the NLRP3 inflammasome in macrophages, and the contribution of IL-1β to the host defense against Citrobacter rodentium acute infection in mice. Nlrp3(-/-) and background C57BL/6 (WT) mice were infected by orogastric gavage, received IL-1β (0.5 µg/mouse; ip) on 0, 2, and 4 days post-infection (DPI), and assessed on 6 and 10 DPI. Infected Nlrp3(-/-) mice developed severe colitis; IL-1β treatments reduced colonization, abrogated dissemination of bacteria to mesenteric lymph nodes, and protected epithelial integrity of infected Nlrp3(-/-) mice. In contrast, IL-1β treatments of WT mice had an opposite effect with increased penetration of bacteria and barrier disruption. Microscopy showed reduced damage in Nlrp3(-/-) mice, and increased severity of disease in WT mice with IL-1β treatments, in particular on 10 DPI. Secretion of some pro-inflammatory plasma cytokines was dissipated in Nlrp3(-/-) compared to WT mice. IL-1β treatments elevated macrophage infiltration into infected crypts in Nlrp3(-/-) mice, suggesting that IL-1β may improve macrophage function, as exogenous administration of IL-1β increased phagocytosis of C. rodentium by peritoneal Nlrp3(-/-) macrophages in vitro. As well, the exogenous administration of IL-1β to WT peritoneal macrophages damaged the epithelial barrier of C. rodentium-infected polarized CMT-93 cells. Treatment of Nlrp3(-/-) mice with IL-1β seems to confer protection against C. rodentium infection by reducing colonization, protecting epithelial integrity, and improving macrophage activity, while extraneous IL-1β appeared to be detrimental to WT mice. Together, these findings highlight the importance of balanced cytokine responses as IL-1β improved bacterial clearance in Nlrp3(-/-) mice but increased tissue damage when given to WT mice.
authors: Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada ; Centre of Excellence for Gastrointestinal Inflammation and Immunity Research (CEGIIR), University of Alberta, Edmonton, Alberta, Canada.
authors: Misagh
authors: M
authors: Alipour
authors: Yuefei
authors: Y
authors: Lou
authors: Daniel
authors: D
authors: Zimmerman
authors: Michael W
authors: MW
authors: Bording-Jorgensen
authors: Consolato
authors: C
authors: Sergi
authors: Julia J
authors: JJ
authors: Liu
authors: Eytan
authors: E
authors: Wine
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology; D044082:Citrobacter rodentium / Q000276:immunology*; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D005260:Female; D007113:Immunity, Innate; D058847:Inflammasomes / Q000235:genetics / Q000276:immunology; D053583:Interleukin-1beta / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse