Abstract
The present investigation assessed the potential of green tea phytochemical epigallocatechin-3-gallate (EGCG) in alleviating age-associated aberrations in immunity, hypothalamus-pituitary-adrenal (HPA) axis and redox homeostasis using 16 months old male Swiss albino mice. Four groups of animals (n = 6 per group) were supplemented with either aqueous EGCG at 25, 50 and 100 mg/kg/animal or vehicle control for 6 weeks. A concurrent analysis of CD4+ and CD8+ lymphocytes in splenocytes, differential leucocyte population, T cell differentiation markers in peripheral blood mononuclear cells (PBMCs), neutrophil functions, immunoglobulins profile in intestine, circulatory HPA axis hormonal levels as well as inflammatory and oxidative stress in the liver was performed. We observed a remarkable increase in plasma dehydroepiandrosterone (DHEA) levels of 100 mg EGCG fed animals while eosinophils and monocytes counts in blood increased. EGCG consumption increased the fraction of CD3+CD8+ cells in splenocytes and CD28 expression on PBMCs. The immunoglobulins profile revealed decreased production of secretory IgA, IgE and IgG1/IgG2a ratio. Liver extracts showed increase in superoxide dismutase activity and total antioxidant capacity while lipid peroxidation along with inflammatory markers (IL-6 and TNF-α) decreased. Our results collectively show that EGCG consumption during aging strengthens systemic immunity by enhancing cellular immune response and simultaneously attenuating antibody response aided by an increase in adrenal DHEA production. Thus, consumption of green tea may be beneficial in alleviating some of the deleterious aspects of aging and immunosenescence in elderly.