Leptin modulates autophagy in human CD4(+)CD25(-) conventional T cells.

Objective. In this report we show that the adipocytokine leptin directly modulates autophagy in human CD4(+)CD25(-) conventional (Tconv) T cells. Results. In vitro treatment with recombinant human leptin determined an inhibition of autophagy during T cell receptor (TCR) stimulation, and this phenomenon was dose- and time-dependent The events were secondary to the activation of the mammalian-target of rapamycin (mTOR)-pathway induced by leptin, as testified by its reversion induced by mTOR inhibition with rapamycin. At molecular level these phenomena associated with Bcl-2 up-regulation and its interaction with Beclin-1, whose complex exerts a negative effect on autophagy. Materials/methods. The impact of leptin on autophagy of Tconv cells was determined at biochemical level by western blotting and by flow cytometry; the interaction between BCL-2 and Beclin-1 by co-immunoprecipitation assays. Conclusions. Our results, suggest that in unconditioned, freshly-isolated human Tconv cells, autophagy and proliferation are controlled by leptin during TCR-engagement, and that both phenomena occur alternatively indicating a balance between these processes during immune activation.