The Impact of Obesity on Immune Response to Infection and Vaccine: An Insight into Plausible Mechanisms

Abstract

Though we know much about development of obesity and its associated complications like type II diabetes, cardiovascular diseases, hypertension and cancer, our knowledge is very limited about the impact of this metabolic syndrome on immune functions per se. Studies in obese humans and animal models have earlier shown, altered lymphocyte numbers, and reduced lymphocyte responsiveness to mitogen stimulation, dysregulated cytokine expression, decreased natural killer cells, macrophage and dendritic cell functions, leading to reduced resistance to infections involving a number of organisms such as Mycobacterium tuberculosis, Coxsackie virus, Helicobacter pyroli and influenza. Several obesity-associated hormonal changes such as leptin resistance, hyperinsulinemia, and metabolic changes such as excessive inflammation and altered glucose, amino acid and fatty acid metabolism which are required for the functionality of T cells could affect the immune response. This review tries to explore these possibilities and project them as plausible mechanism(s), which could affect the response to infectious diseases and vaccine in obese conditions.