Leptin Activates Human B Cells to Secrete TNF-α, IL-6, and IL-10 via JAK2/STAT3 and p38MAPK/ERK1/2 Signaling Pathway

Leptin, one of the adipokines, functions as a hormone and a cytokine. In this investigation, we show for the first time that leptin, in a concentration-dependent manner, activates human peripheral blood B cells to induce secretion of IL-6, IL-10, and TNF-α. Leptin increased B cells expressing CD25 and HLA-DR. Leptin induces phosphorylation of Janus activation kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), p38 mitogen-activated protein kinase (p38MAPK), and extracellular signal-regulated kinase (ERK1/2). Furthermore, leptin-induced cytokine secretion by B cells was blocked by inhibitors of JAK2, STAT3, p38MAPK, and ERK1/2. These data demonstrate that leptin activates human B cells to secrete cytokines via activation of JAK2/STAT3 and p38MAPK/ERK1/2 signaling pathways, which may contribute to its inflammatory and immunoregulatory properties

Increased activation and cytokine secretion in B cells stimulated with leptin in aged humans

Abstract Aging is associated chronic inflammation and autoimmunity, and increased levels of leptin. Increased levels of leptin are associated with inflammation and autoimmunity. We have recently reported that leptin activates B cells to induce secretion of proinflammatory and anti-inflammatory cytokines. Role of B cells and leptin in inflammation associated with aging has not been explored. In this study we demonstrate that leptin activates and induces significantly greater amount of IL-6, TNF-α, and IL-10 by B cells from aged humans as compared to young controls. This is associated with increased leptin-induced phosphorylation of STAT3 (signal transducer and activator of transcription-3) in B cells from aged humans as compared to young subjects. These data suggest that leptin-induced B cell-derived proinflammatory cytokines may play a role in chronic inflammation associated with human aging