Avaliação da resposta imune inata no desenvolvimento do modelo de Encefalomielite Autoimune Experimental (EAE)

Abstract

Multiple sclerosis (MS) is an inflammatory, chronic demyelinating disease of the central nervous system (CNS). It is in most cases severe and disabling, affecting about 2.5 million people worldwide. Experimental autoimmune encephalomyelitis (EAE) is a murine model of autoimmune disease mediated by Th1 and Th17 lymphocytes developed for studying MS. The induction protocol model uses the complete Freund's adjuvant (CFA) containing the pathogen associated molecular patterns (PAMPs) that bind to Toll-like receptors (TLRs) expressed on antigen presenting cells (APC), crucial for activation T lymphocytes. These receptors are necessary for the induction of EAE by activating signal pathways in cells of the innate and adaptive immunity, which can induce the production of pro-inflammatory mediators responsible for the CNS lesions or anti-inflammatory mediators that can participate in the regulation of disease. The present study evaluated the innate immune response in the initial phase of development of EAE in C57BL/6 mice immunized with MOG35-55 peptide (myelin oligodendrocyte glycoprotein) and CFA (group EAE) or CFA alone (group MOG negative). The animals were sacrificed on days 2, 4 and 7 after induction model. The inguinal lymph nodes and spinal cord were removed and subjected to histological, serum cytokines and chemokines, as well as evaluating the expression of TLRs. The results showed that only animals of group EAE developed clinical signs of disease. This group also showed an intense cellular infiltrate in the spinal cord on day 7 after induction, high levels of chemokines CCL5 and CCL20 and cytokines IL-6, IL-12, IL-1β, TNF-α, IFN-γ, IL-17, IL-10 and TGF-β in the CNS, and increased number of APCs expressing TLR3, TLR4 and TLR9. Thus, these data suggest that expression of TLRs and production of pro-inflammatory cytokines are shown as being critical for the induction of EAE, and increased anti-inflammatory patterns, still in the initial points of development of the disease, suggests the use of these patterns as regulation mechanisms of the experimental model and possibly the MS.