RESVERATROL DOWNREGULATES LIPOPOLYSACCHARIDE-INDUCED MICROGLIAL ACTIVATION

FRANCHI, ANA MARÍA; STERN, ANÍBAL; CORREA, FERNANDO; TICCHI JULIA

Mar del Plata

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2019

Background: Microglial cells play an important role in the central nervous system (CNS) innate immune response. Excessive activation of these cells is considered to be detrimental and has been implicated in many neurodegenerative and neuropsychiatric disorders. Therefore, a lot of efforts are being made in searching for compounds with a good safety profile that could modulate microglial function. Resveratrol, a naturally occurring stilbene with anti-inflammatory, antioxidant and epigenetic properties, showed neuroprotective effects in several models of CNS disorders. However, little is known regarding the molecular mechanisms involved in resveratrol neuroprotective effects. Therefore, our aim was to explore whether the MAPK and NF-kB signaling pathways were involved in the modulatory effects of resveratrol on microglial BV2 cell line response to lipopolysaccharide (LPS). Methods and Results: cell cultures of the murine microglial cell line BV2 were exposed to LPS and/or resveratrol and at different time-points supernatants, total mRNA or proteins were collected. We first evaluated the potential cytotoxicity of resveratrol with an MTT assay. We observed that only at the concentration of 50-100 µM showed cytotoxicity. Therefore, we used a concentration of 10 µM resveratrol in our subsequent experiments. Next, we evaluated the mRNA expression of the proinflammatory cytokines Il-1b and Il-6 and found that resveratrol negatively modulated the LPS-induced mRNA levels of these cytokines. When we studied the potential involvement of MAPK and NF-κB signaling pathways, we found that resveratrol inhibited the activation (phosphorylation) of ERK1/2, SAPK/JNK, p38 MAPK and the p65 subunit of NF-κB complex. Overall, these results suggest that resveratrol dampens the LPS-induced activation of signaling pathways. Since it has been shown that resveratrol can modulate the activity of SIRT1 (a member of the NAD+-dependent histone deacetylase family of enzymes targeting both histone and non-histone substrates), we decided to analyze whether resveratrol could prevent the changes in the acetylation pattern of histone-3 (H3) induced by LPS. We found that LPS increased the acetylation of H3 and resveratrol prevented this effect. Conclusions: During the inflammatory process in the CNS, microglia play an important role by creating an environment that enhances the production of various pro-inflammatory factors, which consequently cause neuronal dysfunction and neurodegeneration. Since resveratrol is capable of exerting anti-inflammatory and antioxidant activities in several cell types, we studied the effects of resveratrol on microglial LPS-induced activation. Collectively, our results suggest resveratrol exerts neuroprotective effects by suppressing the LPS-enhanced expression of pro-inflammatory mediators such as pro-inflammatory cytokines as well the epigenetic changes in microglial cell cultures. Since resveratrol has a good safety profile, it could result in an ideal candidate for neuroprotection in situations of neuroinflammation.