IL-22 and Lactobacillus delbrueckii mitigate alcohol-induced exacerbation of DSS-induced colitis

Ulcerative colitis (UC) is characterized by cycles of active disease flare and inactive disease remission. During UC remission, IL-22 is up-regulated, acting as a hallmark of entrance into UC remission. Recently, we found that in our mouse model of binge alcohol and dextran sodium sulfate (DSS)-induced colitis, alcohol increases severity of UC pathology. In this study, we assessed not only whether alcohol influenced IL-22 expression and thereby perpetuates UC, but also whether recombinant IL-22 (rIL-22) or treatment with a probiotic could alleviate exacerbated symptoms of UC. Levels of large intestine IL-22 were significantly decreased ∼6.9-fold in DSS ethanol compared with DSS vehicle. Examination of lamina propria (LP) cells in the large intestine revealed IL-22+ γδ T cells in DSS vehicle-treated mice were significantly increased, while IL-22+ γδ T cells in DSS ethanol mice were unable to mount this IL-22 response. We administered rIL-22 and found it restored weight loss of DSS ethanol-treated mice. Colonic shortening and increased Enterobacteriaceae were also attenuated. Administration of Lactobacillus delbrueckii attenuated weight loss (p < 0.01), colon length (p < 0.001), mitigated increases in Enterobacteriaceae, increased levels of IL-22, and increased levels of p-STAT3 back to that of DSS vehicle group in DSS ethanol mice. In contrast, sole administration of L. delbrueckii supernatant was not sufficient to reduce UC exacerbation following alcohol. Our findings suggest L. delbrueckii contributes to repair mechanisms by increasing levels of IL-22, resulting in phosphorylation of STAT3, thus attenuating the alcohol-induced increases in intestinal damage after colitis.