Autophagy induction by TLR2 ligands regulates leukocyte recruitment in the brain

ARROYO DANIELA S; GAVIGLIO EMILIA A; PERALTA-RAMOS JAVIER M; BUSSI CLAUDIO; AVALOS PAULA; CANCELA LILIANA M; IRIBARREN P

Mar del Plata

Congreso; LXII Reunión Anual de la Sociedad Argentina de Inmunología; 2014

Sociedad Argentina de Inmunología

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 inflammation 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 significant increase 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 confirmed that PGN-induced recruitment of CD11b/CD45high cells was dependent on 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 induced recruitment of different CD11b/CD45high populations cells to the CPU. Therefore, we evaluated by flow citometry 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 expression 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 inflamed mouse brain.