Involvement of Regulatory T Cells and Their Cytokines Repertoire in Chemopreventive Action of Fish Oil in Experimental Colon Cancer

Gut-associated immune response plays a major role in pathogenesis of many diseases including cancer. Modulation of intestinal immune response via dietary components might influence prognosis of colon carcinoma. This study was designed to evaluate the effect of differential ratios of fish oil (FO) and corn oil (CO) on T cells in experimental colon carcinoma. Male Wistar rats were divided into six groups: Group I received purified diet while Groups II and III received purified diet supplemented with FO:CO(1:1) and FO:CO(2.5:1), respectively. These were further subdivided into controls and treated with ethylenediaminetetraacetic acid (EDTA) or N,N'-dimethylhydrazine dihydrochloride (DMH), respectively. Regulatory T cells (natural and induced; nTregs and iTregs), helper T cells, surface markers (CD28, TCR, TCR), and intracellular cytokines in CD4(+) cells were analyzed in colonic intraepithelial lymphocytes (IELs). DMH treatment led to a significant decrease in nTregs and increase in iTregs. Treatment with FO/CO resulted in an increase in both Tregs as compared to DMH group. Intracellular interleukin (IL)-10 and IL-6 levels increased on DMH treatment, while FO/CO treatment decreased their levels. DMH treatment led to elevation of CD4(+) cells expressing surface markers in comparison to control group. This expression decreased considerably with FO/CO. FO modulates immune response against colon cancer by altering Tregs and their cytokine repertoire.