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* = Presenting author

P110 Cigarette smoke modulates the effect of dextran sulfate sodium–induced colitis on a subpopulation of T-cells in blood and colon in mice

J. Daniluk*1, U. Daniluk2, M. Rusak3, J. Reszec4, M. Dabrowska3, A. Dabrowski1

1Medical University of Bialystok, Department of Gastroenterology and Internal Medicine, Bialystok, Poland, 2Medical University of Bialystok, Department of Paediatrics, Gastroenterology and Allergology, Bialystok, Poland, 3Medical University of Bialystok, Department of Haematological Diagnostics, Bialystok, Poland, 4Medical University of Bialystok, Department of Medical Pathomorphology, Bialystok, Poland

Background

Cigarette smoke (CS) induces protective anti-inflammatory effect during ulcerative colitis and improves the course of the disease. The mechanism of this phenomenon remains unknown. Reports have shown marked increase in CD4 and CD8 colonic T-cells in animal models of DSS-induced colitis. However, the effect of CS on these cells in mice with DSS-induced colitis has not been studied yet.The aim of this study was to evaluate the effect of CS on the course of intestinal inflammation and differences in complete blood count (CBS) and subpopulations of lymphocytes in blood (CD4+, CD8+, CD4+CD25+CD127- Treg, and CD4+ cells expressing IL-4, IL-13, and IFN-γ) and colon (CD4+, CD8+, and CD20+) in an animal model of DSS-induced colitis.

Methods

C57BL6/cmdb mice were divided into 4 groups: the control group, the colitis group treated with 2.5% DSS, the cigarette-smoking group, and group exposed on both CS and 2.5% DSS. Mice were exposed on CS for 4 weeks using the Teague smoking exposure system, reproducing human smoking habit. Colitis was induced with 2.5% DSS added in drinking water for 7 days, starting from week 4. Peripheral subpopulations of lymphocytes were assessed using flow cytometry. The intestinal infiltration by T-cells was evaluated by immunohistochemistry.

Results

Compared with control, mice exposed to CS alone demonstrated significant increase in red blood count (p = 0.007) and haemoglobin level (p = 0.007) and decrease of lymphocytes count (p = 0.031) in complete blood cell count (CBC) with concomitant increase of percentage of CD4+ cells (p = 0.007) and T-cells producing IFNγ (p = 0.007). On the contrary, treatment with 2.5% DSS alone enhanced blood lymphocytes percentage in comparison to control (p = 0.015), but without significant differences in lymphocytes subpopulations. Interestingly, combination of CS exposure and DSS treatment, resulted in similar a effect to CS exposure alone, ie, decrease of peripheral lymphocytes count with increased percentage of CD4+ subpopulation (p = 0.007) and T-cells producing IFNγ (p = 0.007) compared with mice treated with DSS alone. Histology evaluation revealed enhanced lymphocytic infiltration of submucosal and muscular layers of the intestine of CS+DSS+ mice with predominance of CD8 cells compared with other groups.

Conclusion

Our results demonstrate that CS exposure prevented increase of peripheral lymphocyte number after DSS treatment and enhanced the percentage of CD4+ cells and T-cells producing IFNγ in blood and CD8+ cells in colon. These mechanisms may be involved in protective action of smoking in ulcerative colitis; however, further i are required.