Immunoregulation of colonic cytokine mRNA expression by passive cigarette smoking and red wine consumption in experimentally induced colitis rats

Cigarette smoking had been implicated to have beneficial effect on ulcerative colitis (UC) in man. Besides nicotine, the phenolic compounds present in cigarette smoke could be involved in such action, due to their potential antioxidant property. The present investigation aimed to study the effects of passive cigarette smoking and ingestion of red wine, which also contains abundant amount of phenolic compounds, on experimental UC. Male Sprague-Dawley rats were exposed to 4% cigarette smoke (in a smoking chamber) for one hour daily, or received oral administration of red wine (4 ml/kg) twice daily for 7 days. Enema 2,4-d initrobenzene sulfonic acid in ethanol (DNBS. 30 mg/250 μl) was administered on day 4 to the treated and control rats to induce UC-like colitis. All rats were sacrificed on day 8. Results had demonstrated a time-dependent profile of DNBS-induced colonic damages in control rats, which was attenuated by passive cigarette smoking. Nevertheless, similar protective effect was not achieved by red wine consumption. The mRNA expression of the proinflammatory cytokine tumor necrosis factor-a (TNF-a) was increased, while that of the immunoregulatory cytokine interleukin- I0 (IL-1O) was decreased markedly in the colonic tissue of colitis rats, when compared with normal animals. On the other hand, the diminution of TNF-a mRNA expression was lessened in the passive cigarette smoking and red wine ingestion groups of co litis animals, with a concomitant preservation of the drop of IL-10 mRNA express ion. But these were not associated with a restorative effect on the suppression of the inducible nitric ox ide (NO) synthase mRNA expression in colitis rats. Nonetheless, the elevation of myeloperoxidase (neutrophil)-derived free radicals in the colitis tissue was significantly reduced in the passive cigarette smoking and red wine ingestion groups of rats. These findings suggest that both passive cigarette smoking and red wine consumption could ameliorate the development of UC-like colitis in rats by concurrently regulating the colonic mRNA expression of TNF-a and IL-10. The protective effect of passive cigarette smoking and the mild anti-inflammatory effect of red wine were not mediated via a NO-dependent pathway, but may involve the inhibition of neutrophilderived free radicals formation following the immunoregulation of cytokines.