Chapter 7 - Leptin: an immunological adjuvant to improve vaccine response in infectious diseases

Abstract

Leptin is an adipokine secreted from the adipocytes of adipose tissue and is directly proportional to the body fat mass in both mice and humans. It acts as pleiotropic molecules such as hormone/cytokine. As a hormone, it influences nutritional status and regulates neuroendocrine function, mainly in energy deficiency conditions. As a cytokine, leptin induces proinflammatory cytokines, affects thymic homeostasis, and Th1 cell differentiation. It also influences haematopoiesis, thermogenesis, reproduction, and angiogenesis. Notably, leptin also modulates both in innate and adaptive immune responses. Lack of leptin or lack of sensitivity is an important cause for cytokine dysregulation in humans, which is extended to inflammatory responses that cause autoimmune disease and susceptibility toward infectious disease. Thus, leptin has been considered as a central molecule, which has shown varied interrelated functions in many disorders, such as infectious and non-infectious diseases. The chapter will summarize the potential role of leptin as an immunological adjuvant to improve the vaccine response in infectious diseases.