TLR2 HAPLOTYPE REGULATES SEVERITY AND COURSE OF EAE BY MODULATING THE PROINFLAMMATORY ATTITUDE OF CNS-SPECIFIC T CELLS .

Objective: M. Tuberculosis-derived motives play an essential role in the induction of the experimental model of Multiple Sclerosis, the experimental autoimmune encephalomyelitis (EAE). To examine the role of TLR2 (the main receptor for M tuberculosis) in the development of EAE, we crossed SJL mice with wild type B6 mice (B6wt) or B6129-Tlr2tm1kir/3 that fail to express TLR2 (B6tlr2-). Gene dosage is partially reflected by expression of TLR2, since activated T cells and CDR3- cells from lymph nodes of F1 (SJL x B6tlr2-) mice display a reduced level of TLR2 on their surface with respect to F1 (SJL x B6wt). SJL and B6 strains are both prone to develop EAE following immunization with myelin-derived peptides (PLP139-151 (p139) and MOG35-47, respectively). There are however relevant differences between these two models. First, opposite to B6, SJL mice develop EAE without the need for pertussis toxin (PTx) administration; second, SJL mice develop a relapsing remitting EAE, while B6 undergo a progressive/chronic form of the disease. Methods: SJL and breeding couples for C57/BL6wt and C57/BL6tlr2- mice were bred in the animal housing facility of our University. We used protocols of immunization and immunoscope analysis as described respectively in Nicolò 2006 and Ria 2004. We performed real time PCR with SYBRgreen method (Biorad®) to study IFN, FoxP3, IL17, IL13, IL10, IL12, IL23 expression. The histological examination of CNS were performed in collaboration with the Anathomy Institute of our University. Results: We show here that both F1 mice develop EAE when immunized with p139. Surprisingly, disease is more severe in F1 (SJL x B6tlr2-) mice than in F1 (SJL x B6wt) mice. F1 (SJL x B6tlr2-) mice also consistently showed a partial remission of EAE symptoms, while F1 (SJL x B6wt) mice did not. Histological examination of CNS shows more frequently rostral infiltrates and demyelination in F1(SJL x B6tlr2-) mice than in F1 (SJL x B6wt) mice, that presented seriously damaged spinal cord. Conclusions: In these two strains we analyzed the influence of polymorphic site of TLR2 on polarization of T cells by the expression of cytokines. Interestingly we observed that there is a significantly increase of IFNgamma and IL17 in the F1 (SJL x B6tlr2-) group with respect to F1 (SJL x B6wt) providing a mechanistic interpretation for the role of TLR2 haplotype in the modulation of severity of EAE.