The Microbiome Activates CD4 T-cell-mediated Immunity to Compensate for Increased Intestinal Permeability

TY - JOUR

T1 - The Microbiome Activates CD4 T-cell-mediated Immunity to Compensate for Increased Intestinal Permeability

AU - Edelblum, Karen L

AU - Sharon, Gil

AU - Singh, Gurminder

AU - Odenwald, Matthew A

AU - Sailer, Anne

AU - Cao, Severine

AU - Ravens, Sarina

AU - Thomsen, Irene

AU - El Bissati, Kamal

AU - McLeod, Rima

AU - Dong, Chen

AU - Gurbuxani, Sandeep

AU - Prinz, Immo

AU - Mazmanian, Sarkis K

AU - Turner, Jerrold R

PY - 2017/6/10

Y1 - 2017/6/10

N2 - BACKGROUND & AIMS: Despite a prominent association, chronic intestinal barrier loss is insufficient to induce disease in human subjects or experimental animals. We hypothesized that compensatory mucosal immune activation might protect individuals with increased intestinal permeability from disease. We used a model in which intestinal barrier loss is triggered by intestinal epithelial-specific expression of constitutively active myosin light chain kinase (CA-MLCK). Here we asked whether constitutive tight junction barrier loss impacts susceptibility to enteric pathogens.METHODS: Acute or chronic Toxoplasma gondii or Salmonella typhimurium infection was assessed in CA-MLCK transgenic or wild-type mice. Germ-free mice or those lacking specific immune cell populations were used to investigate the effect of microbial-activated immunity on pathogen translocation in the context of increased intestinal permeability.RESULTS: Acute T gondii and S typhimurium translocation across the epithelial barrier was reduced in CA-MLCK mice. This protection was due to enhanced mucosal immune activation that required CD4+ T cells and interleukin 17A but not immunoglobulin A. The protective mucosal immune activation in CA-MLCK mice depended on segmented filamentous bacteria (SFB), because protection against early S typhimurium invasion was lost in germ-free CA-MLCK mice but could be restored by conventionalization with SFB-containing, not SFB-deficient, microbiota. In contrast, chronic S typhimurium infection was more severe in CA-MLCK mice, suggesting that despite activation of protective mucosal immunity, barrier defects ultimately result in enhanced disease progression.CONCLUSIONS: Increased epithelial tight junction permeability synergizes with commensal bacteria to promote intestinal CD4+ T-cell expansion and interleukin 17A production that limits enteric pathogen invasion.

AB - BACKGROUND & AIMS: Despite a prominent association, chronic intestinal barrier loss is insufficient to induce disease in human subjects or experimental animals. We hypothesized that compensatory mucosal immune activation might protect individuals with increased intestinal permeability from disease. We used a model in which intestinal barrier loss is triggered by intestinal epithelial-specific expression of constitutively active myosin light chain kinase (CA-MLCK). Here we asked whether constitutive tight junction barrier loss impacts susceptibility to enteric pathogens.METHODS: Acute or chronic Toxoplasma gondii or Salmonella typhimurium infection was assessed in CA-MLCK transgenic or wild-type mice. Germ-free mice or those lacking specific immune cell populations were used to investigate the effect of microbial-activated immunity on pathogen translocation in the context of increased intestinal permeability.RESULTS: Acute T gondii and S typhimurium translocation across the epithelial barrier was reduced in CA-MLCK mice. This protection was due to enhanced mucosal immune activation that required CD4+ T cells and interleukin 17A but not immunoglobulin A. The protective mucosal immune activation in CA-MLCK mice depended on segmented filamentous bacteria (SFB), because protection against early S typhimurium invasion was lost in germ-free CA-MLCK mice but could be restored by conventionalization with SFB-containing, not SFB-deficient, microbiota. In contrast, chronic S typhimurium infection was more severe in CA-MLCK mice, suggesting that despite activation of protective mucosal immunity, barrier defects ultimately result in enhanced disease progression.CONCLUSIONS: Increased epithelial tight junction permeability synergizes with commensal bacteria to promote intestinal CD4+ T-cell expansion and interleukin 17A production that limits enteric pathogen invasion.

U2 - 10.1016/j.jcmgh.2017.06.001

DO - 10.1016/j.jcmgh.2017.06.001

M3 - SCORING: Journal article

C2 - 28795125

VL - 4

SP - 285

EP - 297

JO - CELL MOL GASTROENTER

JF - CELL MOL GASTROENTER

SN - 2352-345X

IS - 2

ER -