Insulin-Induced Lipoatrophy in Type I Diabetes: A possible tumor necrosis factor-α-mediated dedifferentiation of adipocytes

Abstract

OBJECTIVE To test the hypothesis that tumor necrosis factor (TNF)-α may mediate the loss and the dedifferentiation of subcutaneous fat tissue in the insulin-induced lipoatrophies of a diabetic patient who presented extensive lesions. RESEARCH DESIGN AND METHODS An in vitro exploration of cytokine production by peripheral blood mononuclear cells (PBMC) from the reported case was performed and compared with the same explorations of PBMC from three nondiabetic subjects and three diabetic patients without lipoatrophic lesions. A proliferation test and an evaluation of TNF-α and interleukin (IL)-6 production from PBMC in presence of insulin were studied. RESULTS The production of TNF-α and IL-6 by the macrophages of the patient in presence of insulin were dramatically increased in comparison with control subjects. This process needed cooperation with other lymphoid cells and was abrogated by dexamethasone. CONCLUSIONS In our reported case, a local hyperproduction of TNF-α from macrophages that was induced by the injected insulin could explain the dedifferentiation of the adipocytes of the subcutaneous tissue and the reversion that was induced by the local injection of dexamethasone.