P160 γδ T CELLS, IL-22, THE PROBIOTIC, LACTOBACILLUS DELBRUECKII, AND THE ROLE THEY PLAY IN ATTENUATION OF ALCOHOL INDUCED EXACERBATION OF DSS-COLITIS

Abstract

Ulcerative colitis is characterized by cycles of active disease flare and inactive disease remission. During UC remission, IL-22 expression can be upregulated, acting as a hallmark of entrance into a UC remission period. Recently, we found that in our mouse model of binge alcohol consumption after DSS-induced colitis, alcohol increases severity of UC flare symptoms. In this study, we assessed whether alcohol influenced IL-22 expression and thereby perpetuates UC flare. Male C57BL/6 mice received 2% DSS or water ad libitum for 5 days. On day 5, DSS was removed to mimic entrance into remission. Additionally on day 5, DSS and Sham mice were subdivided into mice gavaged with ethanol (∼3g/kg) or with water on days 5, 6, and 7. Three hours after the last gavage on day 7, mice were humanely euthanized. Large intestine lamina propria (LP) cells were isolated. The percentage of total IL-22+ LP cells was significantly decreased (p<0.05) in DSS Ethanol compared to DSS Vehicle. No differences in IL-22+ T cells, Innate Lymphoid Cells Type 3, or neutrophils were observed. Examination of I γδ T cells revealed DSS Vehicle treated mice had a significantly increased percentage of IL-22+ γδ T cells, while DSS Ethanol treated mice were unable to mount this response. Therefore, we hypothesized that by re-establishing IL-22, through either rIL-22 or a probiotic, we could alleviate the alcohol-induced exacerbation of UC. Firstly, rIL-22 administration substantially restored weight loss of DSS Ethanol treated mice back to that of DSS Vehicle (∼12.5% back to ∼6% on day 7). Increased colonic shortening (p<0.001) and increased Enterobacteriaceae copy number were also attenuated following binge alcohol and colitis with IL-22 treatment. Knockout of STAT3 in IECs resulted in loss of IL-22 protection, demonstrating STAT3 is required for protection. Secondly, we utilized Lactobacillus delbrueckii, a common probiotic known to play a role in IL-22 release. Treatment with Lacto attenuated both weight loss and colon length in DSS Ethanol mice back to levels of DSS alone (p<0.01 and p<0.001, respectively). Additionally, Lacto treatment mitigated increases in Enterobacteriaceae copy number seen in DSS Ethanol mice and trended towards an increase in IL-22 in DSS Ethanol + Lacto mice. Levels of pSTAT3 were decreased in DSS Ethanol treated mice compared to DSS Vehicle, but administration of Lacto in DSS Ethanol mice increased levels of pSTAT3 back to that of the DSS Vehicle group. Treatment with Lacto supernatant alone was not sufficient to mitigate the exacerbation of UC following ethanol. Our findings suggest that both rIL-22 and Lactobacillus delbrueckii utilize the IL-22/pSTAT3 signaling pathway to attenuate alcohol-induced increases in ulcerative colitis symptoms. (R21AA022324, R21AA025806, T32AA013527, F30AA027442, F31AA025536)