Autophagy down regulates pro-inflammatory mediators in BV2 microglial cells and rescues both LPS and alpha-synuclein induced neuronal cell death

Claudio Bussi,Ji Ming Wang,Maria Soledad Celej,Jose Ignacio Gallea,Emilia A Gaviglio,Pablo Iribarren,Daniela S Arroyo,Javier Maria Peralta Ramos

doi:10.1038/srep43153

Abstract

Autophagy is a fundamental cellular homeostatic mechanism, whereby cells autodigest parts of their cytoplasm for removal or turnover. Neurodegenerative disorders are associated with autophagy dysregulation, and drugs modulating autophagy have been successful in several animal models. Microglial cells are phagocytes in the central nervous system (CNS) that become activated in pathological conditions and determine the fate of other neural cells. Here, we studied the effects of autophagy on the production of pro-inflammatory molecules in microglial cells and their effects on neuronal cells. We observed that both trehalose and rapamycin activate autophagy in BV2 microglial cells and down-regulate the production of pro-inflammatory cytokines and nitric oxide (NO), in response to LPS and alpha-synuclein. Autophagy also modulated the phosphorylation of p38 and ERK1/2 MAPKs in BV2 cells, which was required for NO production. These actions of autophagy modified the impact of microglial activation on neuronal cells, leading to suppression of neurotoxicity. Our results demonstrate a novel role for autophagy in the regulation of microglial cell activation and pro-inflammatory molecule secretion, which may be important for the control of inflammatory responses in the CNS and neurotoxicity.

Highlights

Autophagy is a ubiquitous eukaryotic intracellular homeostatic process affecting all cell types in multicellular organisms, whereby cells autodigest parts of their cytoplasm for removal or turnover[1]
We evaluated the conversion of LC3B I to LC3B II (LC3 form C-terminally lipidated by phosphatidylethanolamine, displaying higher electrophoretic mobility) with immunoblots
These results suggest that autophagy can be induced in microglial cells by either mammalian target of rapamycin (mTOR) inhibitors or the action of trehalose, which acts in a mTOR independent manner

Summary

Introduction

Autophagy is a ubiquitous eukaryotic intracellular homeostatic process affecting all cell types in multicellular organisms, whereby cells autodigest parts of their cytoplasm for removal or turnover[1]. Glial reactions and increased expression of inflammatory cytokines are recognized as prominent features of PD Inflammatory mediators such as nitric oxide (NO), TNFα,and interleukin-1β(IL-1β)derived from non-neuronal cells including microglia, are believed to modulate the progression of neuronal cell death in PD8–9. We investigated the effects of autophagy on the production of pro-inflammatory molecules in microglial cells treated with alpha-synuclein We report that both trehalose and rapamycin activate autophagy in BV2 microglial cells and down-regulate the production of pro-inflammatory cytokines and nitric oxide (NO) in response to LPS and alpha-synuclein. This impacted on the effect of microglial activation on neuronal cells, leading to suppression of alpha-synuclein-induced neurotoxicity

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Conclusion