The role of CNS TLR2 activation in mediating innate versus adaptive neuroinflammation.

We examined the effects of intra-cerebro-ventricular (ICV) injection of Zymosan, a TLR2 agonist, on naive versus EAE animals. The neuro-inflammatory response was characterized by immune-fluorescent staining for IBA-1+ microglia/ macrophages and CD3+ T cells, and by semi-quantitative real time PCR for TLR2 and immune cytokines. The nature of the immune cells isolated from EAE brain tissue was assessed by their proliferative response to the PLP peptide autoantigen. Survival and clinical scores were monitored; demyelination and axonal loss were quantified by gold-black and Bielschowsky stains. Our findings showed that Zymosan injection in naïve mice induced a massive neuro-inflammatory response without any clinical manifestations. In EAE mice, ICV Zymosan induced a severe acute toxic response with 80% mortality. Surviving animals returned to pre-injection clinical score, and their course of disease was not altered as compared to control EAE group. Demyelination and axonal loss were not affected by ICV Zymosan injection. Quantification of immune response in the brain by real time PCR, immunofluorescent stains and proliferative response to PLP peptide suggested that TLR2 activation induces innate but not adaptive immune response. We conclude that EAE mice are hypersensitive to CNS TLR2 activation with a severe toxic response. This might represent the susceptibility of multiple sclerosis patients to even trivial infections. As CNS TLR2 activation does not alter the clinical and pa...

Source: Experimental Neurology - September 2, 2015 Category: Neurology Authors: Luz A, Fainstein N, Einstein O, Ben-Hur T Tags: Exp Neurol Source Type: research