Autophagy induction: a critical event for the modulation of cell death/survival and inflammatory responses by adipokines.

Adipose tissue acts as a dynamic endocrine organ playing critical roles in many metabolic and immune responses. Endocrine functions by adipose tissue are achieved by secretion of diverse cytokines and hormones, collectively called adipokines. Adiponectin and leptin the most abundantly expressed adipokines within adipose tissue have an impact on various physiological responses. While both adiponectin and leptin are secreted from the same location, their physiological functions are not identical. Adiponectin possesses potent anti-inflammatory properties and anti-tumor activities, whereas leptin acts as a pro-inflammatory hormone and generates tumor-promoting effects. Autophagy, a highly conserved intracellular self-digestive process, is implicated in the maintenance of diverse physiological responses. In particular, autophagy plays dual roles in the regulation of cell death/survival (e.g., inducing cell death and cytoprotection) and is associated with anti-inflammatory actions. Increasing recent evidence has indicated that autophagy is implicated in various biological responses by adipokines. Therefore, autophagy would be a promising target for the management of inflammation and tumor growth by adipokines. In this review, we summarize the effects of adiponectin and leptin on autophagy induction and highlight their implications in modulating inflammatory responses and tumor growth.