The effect of irisin administration on the immune system in obese female and male rats

Obesity is defined as the accumulation of more fat than normal in the body. The increase in adipose tissue in obesity causes an increase in circulating pro-inflammatory cytokines such as IL-1β and IL-6 and increases apoptosis. In the literature, it is stated that exercise has a positive effect on both obesity and immune system cells. However, the effects of irisin hormone, which is an adipo-myokine released into the circulation with exercise, on immune system disorders that occur with obesity is not fully understood. In this thesis, it was aimed to determine the possible role of irisin hormone applied to obese female and male rats on the immune system. Two main groups of Sprague-Dawley female and male rats were used in the study. Both groups were divided into 4 subgroups including control, irisin, obese and obese+irisin (n=10, for each group) groups. Adult female and male rats in the obese and obese+irisin group were fed a high-fat diet of 60% kcal for an average of 14 weeks and 22 weeks, respectively. Afterward, oscillation of the subcutaneous irisin (100 ng/kg/day) was performed for 28 day by a mini-osmotic pump to male and female rats in the irisin and obese+irisin groups. At the end of the study, all female and male animals were decapitated and blood samples were taken. IL-1β, IL-6, IL-10, Caspase-3 and Caspase-9 levels were examined by ELISA (Enzyme-Linked Immunosorbent Assay) method. In line with the data obtained, IL-1β, IL-6, Caspase-3 and Caspase-9 levels were increased and IL-10 levels decreased in the obese group in female rats compared to the control group. In the obese+irisin group with irisin infusion, it was found that IL-1β, IL-6, Caspase-3 and Caspase-9 levels decreased and IL-10 increased compared to the obese group. In male rats, IL-6, Caspase-3 and Caspase-9 levels were increased in the obese group compared to the control group, and IL-10 levels were decreased. No statistical significance was found in the IL-1β level. In the obese+irisin group, IL-6, Caspase-3 and Caspase-9 levels decreased and IL-10 increased compared to the obese group. However, no significant difference was observed in IL-1β level. In conclusion, this thesis shows that irisin hormone may play a regulatory role on obesity-related immune system disorders.