Effects of garlic (Allium sativum) extract on the expression of receptor for advanced glycation end products and proinflammatory cytokines secretion in peripheral blood mononuclear cells from patients with type 2 diabetes mellitus

Receptor for advanced glycation end products (RAGE) plays a causative role in diabetes. Garlic (Allium sativum) belongs to compounds with anti-glycation activity that can be considered as probable therapeutic approaches in delaying or preventing the onset of diabetes complications. The aim of this study was to evaluate the influence of garlic on the RAGE expression and proinflammatory cytokines secretion in peripheral blood mononuclear cells (PBMCs) from patients with type 2 diabetes mellitus.
The PBMCs were isolated from 20 patients with fasting blood sugar level above 126 mg/dl and treated with R10 fraction and whole garlic extract in presence or absence of glycated albumin. The expression of RAGE was detected using flow cytometry and the proinflammatory cytokines secretion was evaluated by ELISA.
Glycated albumin increased RAGE expression and proinflammatory cytokines secretion. Treatment with whole garlic extract significantly reduced TNF-α and IL-1β secretion and RAGE expression by PBMCs but R10 fraction augmented the proinflammatory cytokines and RAGE expression in absence or presence of glycated albumin.
Downregulation of RAGE expression was associated with decreased secretion of IL-1β and TNF-α from PBMCs after treatment with whole garlic, while R10 fraction of garlic significantly augmented RAGE expression and proinflammatory cytokines secretion. These data indicates that modulation of RAGE expression may be one plausible reason for the garlic effects on proinflammatory cytokines secretion.