Lactobacillus johnsonii Attenuates Citrobacter rodentium–Induced Colitis by Regulating Inflammatory Responses and Endoplasmic Reticulum Stress in Mice

Probiotics are beneficial in intestinal disorders. However, the benefits of Lactobacillus johnsonii in experimental colitis remain unknown.This study aimed to investigate the benefits of L. johnsonii against Citrobacter rodentium-induced colitis.Thirty-six 5-wk-old female C57BL/6J mice were randomly assigned to 3 groups (n = 12): control (Ctrl) group, Citrobacter rodentium treatment (CR) group (2 × 109 CFU C. rodentium), and Lactobacillus johnsonii and Citrobacter rodentium cotreatment (LJ + CR) group (109 CFU L. johnsonii with C. rodentium). Colon length, mucosal thickness, proinflammatory cytokine genes, and endoplasmic reticulum stress were tested.The CR group had greater spleen weight, mucosal thickness, and Ki67+ cells (0.4-4.7 times), and a 23.8% shorter colon length than the Ctrl group, which in the LJ + CR group were 22.4%-77.6% lower and 30% greater than in the CR group, respectively. Relative to the Ctrl group, serum proinflammatory cytokines and immune cell infiltration were greater by 0.3-1.6 times and 6.2-8.8 times in the CR group, respectively; relative to the CR group, these were 19.9%-61.9% and 69.5%-84.2% lower in the LJ + CR group, respectively. The mRNA levels of lysozyme (Lyz) and regenerating islet-derived protein III were 22.7%-36.5% lower and 1.5-2.7 times greater in the CR group than in the Ctrl group, respectively, whereas they were 22.2%-25.7% greater and 57.2%-76.9% lower in the LJ + CR group than in the CR group, respectively. Cell apoptosis was 11.9 times greater in the CR group than in the Ctrl group, and 87.4% lower in the LJ + CR group than in the CR group. Consistently, the protein abundances of C/EBP homologous protein (CHOP), cleaved caspase 1 and 3, activating transcription factor 6α (ATF6A), and phospho-inositol-requiring enzyme 1α (P-IRE1A) were 0.3-2.1 times greater in the CR group and 31.1%-60.4% lower in the LJ + CR group. All these indexes did not differ between the Ctrl and LJ + CR groups, except for CD8+ T lymphocytes and CD11b+ and F4/80+ macrophages (1-1.5 times greater in LJ + CR) and mRNA concentration of Lyz2 (20.1% lower in LJ + CR).L. johnsonii supplementation is a promising nutritional strategy for preventing C. rodentium-induced colitis in mice.