Toll-like receptor 2 ligands promote microglial cell death by inducing autophagy

ARROYO, DANIELA S.; GAVIGLIO, EMILIA A.; PERALTA RAMOS, JAVIER M.; BUSSI, CLAUDIO; AVALOS, M.P.; CANCELA LM.; IRIBARREN P.

Mar del Plata

Congreso; Congreso SAI / SAIC 2014; 2014

SAI / SAIC

Microglial cells (MC) are phagocytes in the central nervous system that become activated in pathological conditions, resulting in microgliosis, manifested by increased cell numbers and infla-mation in the affected regions. We previously demonstrated that TLR2 has the potential to induce autophagy in MC. Considering this, in this work we evaluated if autophagy play a role in the regulation of the activation and the recruitment of myeloid cells to the brain. We previously observed that injection of peptidoglycan (PGN; TLR2 ligand) from S. aureus, in mouse brain parenchyma (caudate putamen; CPU), resulted in a significantincrease in the number of LC3B positive CD45+ microglia/macrophages cells in the site of injection (p<0,001). In addition, coinjection of PGN and LY294002 or 3-MA (inhibitors of autophagy) failed to cause the increase of LC3B punctate parenchymal microglia (p<0,001). In another set of experiments, we observed that PGN injection, increased the frecuency CD11b/CD45+ cells (and particularly in the CD11b/CD45high fraction) in the CPU of mice compared to controls (p<0.05). We confirmedthat PGN-induced recruitment of CD11b/CD45high cells was dependent by TLR2 activation, since injection of PGN in CPU of TLR2KO mice was unable to reproduce that effect (p<0,001). Moreover, we found that PGN injection indu-ced recruitment of different CD11b/CD45high population cells to the CPU. Therefore, we evaluated by flowcitometry the phenotype of the CD11b/CD45+ cells. We observed increased expression of MHC class II and CD86 molecules in these cells. Finally, we found that coinjection of PGN and LY294002 or 3M-A reduced the recruitment of CD11b/CD45high cells to the CPU and the ex-pression of MHC class II and CD86 molecules in these cells. Our results suggest that autophagy induction by TLR2 agonists may regulate the leukocyte subpopulations in inflamedmouse brain.