Inhibitory Effects of the Two Novel TSPO Ligands 2-Cl-MGV-1 and MGV-1 on LPS-induced Microglial Activation.

Sheelu Monga,Abraham Weizman,Moshe Gavish,Rula Amara,Rafi Nagler

doi:10.3390/cells8050486

Abstract

The 18 kDa translocator protein (TSPO) ligands 2-Cl-MGV-1 and MGV-1 can attenuate cell death of astrocyte-like cells (U118MG) and induce differentiation of neuronal progenitor cells (PC-12). Lipopolysaccharide (LPS) is a bacterial membrane endotoxin that activates cellular inflammatory pathways by releasing pro-inflammatory molecules, including cytokines and chemokines. The aim of the present study was to assess the immuno-modulatory effect of TSPO ligands in activated microglial cells. We demonstrated that the TSPO ligands 2-Cl-MGV-1 and MGV-1 can prevent LPS-induced activation of microglia (BV-2 cell line). Co-treatment of LPS (100 ng/mL) with these TSPO ligands (final concentration- 25 µM) reduces significantly the LPS-induced release of interleukin-6 (IL-6) from 16.9-fold to 2.5-fold, IL-β from 8.3-fold to 1.6-fold, interferon-γ from 16.0-fold to 2.2-fold, and tumor necrosis factor-α from 16.4-fold to 1.8-fold. This anti-inflammatory activity seems to be achieved by inhibition of NF-κB p65 activation. Assessment of initiation of ROS generation and cell metabolism shows significant protective effects of these two novel TSPO ligands. The IL-10 and IL-13 levels were not affected by any of the TSPO ligands. Thus, it appears that the ligands suppress the LPS-induced activation of some inflammatory responses of microglia. Such immunomodulatory effects may be relevant to the pharmacotherapy of neuro-inflammatory diseases.

Highlights

18 kDa Translocator Protein (TSPO) is known to possess immunomodulatory effects [1]
We found that the novel TSPO ligands 2-Cl-MGV-1 and MGV-1 can attenuate the LPS-induced elevation in cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in BV-2 microglia cell line [9]
LDH assay was applied to assess the impact of ethanol as a vehicle on microglial BV-2 cell death

Summary

Introduction

18 kDa Translocator Protein (TSPO) is known to possess immunomodulatory effects [1]. Previous studies have shown that the compounds 2-Cl-MGV-1 [2-(2-chlorophenyl) quinazolin-4-yl dimethylcarbamate] and MGV-1 [2-phenylquinazolin-4-yl dimethylcarbamate] (designed by our laboratory) have low affinity for the TSPO [6]. The affinity of both 2-Cl-MGV-1 and MGV-1 (Ki value) is 825 nM [6]. 2-Cl-MGV-1 and MGV-1 appear to have beneficial effects in prevention of cell death and inflammatory processes in cell culture studies as well as in animal studies [6,7,8,9]. We assessed the impact of 2-Cl-MGV-1 and MGV-1 on in vitro cellular and molecular processes associated with inflammatory responses of microglia

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