Neuroprotective Properties of Quinone Reductase 2 Inhibitor M-11, a 2-Mercaptobenzimidazole Derivative

The ability of NQO2 to increase the production of free radicals under enhanced generation of quinone derivatives of catecholamines is considered to be a component of neurodegenerative disease pathogenesis. The present study aimed to investigate the neuroprotective mechanisms of original NQO2 inhibitor M-11 (2-[2-(3-oxomorpholin-4-il)-ethylthio]-5-ethoxybenzimidazole hydrochloride) in a cellular damage model using NQO2 endogenous substrate adrenochrome (125 µM) and co-substrate BNAH (100 µM). The effects of M-11 (10–100 µM) on the reactive oxygen species (ROS) generation, apoptosis and lesion of nuclear DNA were evaluated using flow cytometry and single-cell gel electrophoresis assay (comet assay). Results were compared with S29434, the reference inhibitor of NQO2. It was found that treatment of HT-22 cells with M-11 results in a decline of ROS production triggered by incubation of cells with NQO2 substrate and co-substrate. Pre-incubation of HT-22 cells with compounds M-11 or S29434 results in a decrease of DNA damage and late apoptotic cell percentage reduction. The obtained results provide a rationale for further development of the M-11 compound as a potential neuroprotective agent.

Toll-like receptor 7 (TLR7) modulates anti-nucleosomal autoantibody isotype and renal complement deposition in mice exposed to syngeneic late apoptotic cells

ObjectivesThe objectives of this study were to determine whether late apoptotic cell material directly induces autoantibodies characteristic of systemic lupus erythematosus (SLE) and to investigate the innate recognition pathways involved.MethodsB6, B6.MyD88–/–, B6.TLR7–/– and B6.TLR9–/– mice were subcutaneously injected with B6 syngeneic late apoptotic thymocytes (SLATs) without adjuvant on days 0, 10, 24 and 37. Sera were tested for IgG antibodies to histones and double-stranded DNA (dsDNA) by ELISA and Crithidia luciliae indirect immunofluorescence. IgG and C3 deposition in kidney glomeruli was assessed by immunostaining and fluorescence microscopy.ResultsSLAT injections induced anti-dsDNA and anti-histone antibodies of the IgG1 and IgG2b isotypes in B6 but not MyD88–/– mice. TLR7–/– and TLR9–/– mice injected with SLATs produced delayed or slightly more robust responses, respectively. SLAT injections induced IgG deposits in renal glomeruli of B6, TLR7–/– and TLR9–/– mice that were absent in MyD88–/– mice. Unlike B6 and TLR9–/– animals, TLR7–/– mice failed to exhibit IgG colocalised glomerular C3 deposits and demonstrated autoantibodies of primarily the IgG2a isotype.ConclusionsLate apoptotic cell-induced anti-histone and anti-dsDNA antibodies require MyD88 but not Toll-like receptor (TLR)9. Moreover, TLR7 promotes glomerular C3 deposition, possibly through a mechanism of altered antibody isotype switching.