Proteomic analysis of the effects of aged garlic extract and its FruArg component on lipopolysaccharide-induced neuroinflammatory response in microglial cells.

Hui Zhou,Jilong Li,Zezong Gu,Thomas P Mawhinney,C Michael Greenlief,Valeri V Mossine,Jianlin Cheng,Paula N Brown,Kevin L Fritsche,Dennis B Lubahn,Dineo L Nknolise,Zhenzhou Chen,Zhe Qu,Mark Hannink,Grace Y Sun,Shawn Hayley

doi:10.1371/journal.pone.0113531

Hui Zhou, Jilong Li + Show 14 more

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https://doi.org/10.1371/journal.pone.0113531

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Abstract

Aged garlic extract (AGE) is widely used as a dietary supplement, and is claimed to promote human health through anti-oxidant/anti-inflammatory activities with hypolipidemic, antiplatelet and neuroprotective effects. Prior studies of AGE have mainly focused on its organosulfur compounds, with little attention paid to its carbohydrate derivatives, such as N-α-(1-deoxy-D-fructos-1-yl)-L-arginine (FruArg). The goal of this study is to investigate actions of AGE and FruArg on antioxidative and neuroinflammatory responses in lipopolysaccharide (LPS)-activated murine BV-2 microglial cells using a proteomic approach. Our data show that both AGE and FruArg can significantly inhibit LPS-induced nitric oxide (NO) production in BV-2 cells. Quantitative proteomic analysis by combining two dimensional differential in-gel electrophoresis (2D-DIGE) with mass spectrometry revealed that expressions of 26 proteins were significantly altered upon LPS exposure, while levels of 20 and 21 proteins exhibited significant changes in response to AGE and FruArg treatments, respectively, in LPS-stimulated BV-2 cells. Notably, approximate 78% of the proteins responding to AGE and FruArg treatments are in common, suggesting that FruArg is a major active component of AGE. MULTICOM-PDCN and Ingenuity Pathway Analyses indicate that the proteins differentially affected by treatment with AGE and FruArg are involved in inflammatory responses and the Nrf2-mediated oxidative stress response. Collectively, these results suggest that AGE and FruArg attenuate neuroinflammatory responses and promote resilience in LPS-activated BV-2 cells by suppressing NO production and by regulating expression of multiple protein targets associated with oxidative stress.

Highlights

Garlic is one of the most widely used botanicals worldwide, and studies have shown its beneficial effects against hypercholesterolemia and hypertension, and protection against cardiovascular disease and stroke [1,2,3]
While many studies have focused on the organosulfur compounds in Aged garlic extract (AGE), including S-allyl-L-cysteine (SAC), allicin and allyl thiosulfinates [6], less attention has been paid to the carbohydrate derivatives, such as N-a-(1-deoxy-Dfructos-1-yl)-L-arginine (FruArg), as bioactive components [7, 8]
Treatment of BV-2 cells with various concentrations of AGE (0.1%, 0.2%, 0.5%, and 1%) or FruArg (2, 3, 4, and 5 mM) in the presence of LPS suppressed nitric oxide (NO) levels in a concentration-dependent manner (Figure 2A, left plot)

Summary

Introduction

Garlic is one of the most widely used botanicals worldwide, and studies have shown its beneficial effects against hypercholesterolemia and hypertension, and protection against cardiovascular disease and stroke [1,2,3]. While many studies have focused on the organosulfur compounds in AGE, including S-allyl-L-cysteine (SAC), allicin and allyl thiosulfinates [6], less attention has been paid to the carbohydrate derivatives, such as N-a-(1-deoxy-Dfructos-1-yl)-L-arginine (FruArg), as bioactive components [7, 8]. FruArg belongs to the class of fructosamines, which originate from a nonenzymatic reaction between glucose and arginine [9]; they modify proteins in vivo and are widely used as a diagnostic marker of long-term glucose concentration in diabetics. There is evidence that fructose-amino acids can act as immune-stimulants and inhibit tumorigenesis and metastasis in animal models of cancer [10,11,12,13]

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