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

BUSSI CLAUDIO; PERALTA-RAMOS JAVIER M; ARROYO DANIELA S; GALLEA JOSE I; CELEJ, MARIA S; FLOREY OLIVER; SCHWAB YANNICK; KTISTAKIS NICHOLAS; IRIBARREN PABLO

Dublin

Simposio; Keystone Symposia on Cell Death and Inflammation; 2017

The autophagy pathway plays a crucial role in neurodegenerative diseases, although the precise mechanisms underlying these processes are poorly understood and little is known about the effects of the autophagic process and its regulation in microglial cells (MC).The aim of this study was to evaluate the effects of autophagy on the production of pro-inflammatory mediators by alpha-synuclein (α-syn) stimulated MC, and on neuronal viability in a co-culture model. In addition, we studied the autophagy dynamics in MC after α-syn stimulation.We found that autophagy induction in MC before exogenous α-syn stimulation downregulated IL1β, IL-6, TNF-α and NO production. In addition, it also reduced the phosphorylation of p38 and ERK1/2 MAPKs, which was required for microglial NO production. Besides, we observed in MC/N2A co-cultures that NO production by MC was necessary for neuronal cell death. Moreover, the induction of autophagy in MC decreased mRNA iNOS levels and it promoted neuronal cell survival after α-syn stimulation.Furthermore, we showed by time-lapse experiments with BV2 GFP-LC3 microglial cells that the autophagic protein LC3 is attracted by lysosomes containing α-syn fibrils and we demonstrated by live-CLEM imaging that α-syn is targeted by autophagic vesicles. On the other hand, autophagy inhibition led to MC death after α-syn stimulation, indicating a protective role for autophagy during this process.Taken together, our results provide new evidence about the regulation of the inflammatory response by the autophagy pathway in MC and its role as cell fate modulator.