Anti-TNF-α antibody normalizes serum leptin in IL-2 deficient mice

Objective: A recent study reports that the interleukin-2 deficient (IL-2(-/-)) mouse model of autoimmune and inflammatory bowel disease (IBD) with elevated pro-inflammatory cytokine production has elevated leptin concentrations during food deprivation. The objective of this study was to examine whether increased tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, contributes to the abnormally elevated leptin in IL-2(-/-) mice. Methods: Eight week old, IL-2(-/-) and wild-type control (IL-2(+/+)), male mice were fed regular laboratory mouse food for two weeks. At the end of the study, blood was collected in the fed state, IL-2(-/-) and IL-2(+/+) mice were injected with either anti-TNF-alpha monoclonal antibody or normal saline, and blood was collected in the starved state. Results: The IL-2(-/-) mice consumed less food and lost weight. Administration of anti-TNF-alpha antibody markedly reduced serum leptin concentrations in IL-2(-/-) and control mice after food deprivation. Serum leptin in the IL-2(-/-) mice not receiving anti-TNF-alpha antibody increased significantly in the starved state. Serum concentrations of TNF-alpha were higher in IL-2(-/-) mice compared to controls in both the fed and starved state. Conclusions: These results suggest that elevated TNF-alpha may be one mechanism for the sustained elevated leptin observed in IL-2(-/-) mice during food deprivation.