Abstract
Experimental autoimmune encephalomyelitis (EAE) is mediated by myelin-specific CD4+ T cells secreting Th1 and/or Th17 cytokines. Signal transducer and activator of transcription (STAT) family proteins have essential roles in transmitting Th1 and/or Th17 cytokine-mediated signals. However, most studies demonstrating the importance of the STAT signaling system in EAE have focused on distinct members of this family, often looking at their role specifically in the central nervous system, or in vitro. There is limited information available regarding the temporal and spatial expression patterns of each STAT protein and interplay between STAT proteins over the course of EAE development in critical lymphatic organs in vivo. In the present study, we demonstrate dramatic and progressive decrease of all six STAT family members (STAT1, STAT2, STAT3, STAT4, STAT5, STAT6) in the spleen and lymph nodes through the course of EAE development in SJL/J mice, in contrast with almost steady expression of thymic STAT proteins. Decreased splenic and lymphatic STAT expression was accompanied by significant enlargement of the spleen and lymph nodes, and histological proliferation of T cell areas with remodeling of the splenic microstructure in EAE mice. All STAT family members except STAT2 were mainly confined in T cell areas in spleen, whereas they were distributed in a protein specific manner in thymus. We present here a comprehensive analysis of all six members of the STAT family in spleen, lymph nodes and thymus through the development phase of EAE. Results suggest that EAE induced inflammatory T cells may develop distinct biological features different from normal splenic T cells due to altered STAT signaling.
Highlights
Experimental autoimmune encephalomyelitis (EAE) in mice is a commonly used animal model of multiple sclerosis (MS) that has provided valuable insight into the pathobiology of the human disease [1,2]
Stat expression is significantly decreased in the spleen during EAE development Signal transducer and activator of transcription (STAT) proteins move between cytoplasm and nuclei [28], each STAT family member was quantified in both cytoplasmic and nuclear extracts isolated from thymus and spleen
Western blot analysis demonstrated that expression of all STAT family members, except STAT2, decreased significantly (**P
Summary
Experimental autoimmune encephalomyelitis (EAE) in mice is a commonly used animal model of multiple sclerosis (MS) that has provided valuable insight into the pathobiology of the human disease [1,2]. EAE is induced in mice by active priming with myelin proteins or specific myelin peptide epitopes in adjuvant. Demyelination and paralytic episodes are associated with infiltration of myelin-specific inflammatory Th1 CD4+ T cells into the central nervous system (CNS) [3]. Initially described as an IL-12 driven Th1 cell mediated disease, it was recently shown that EAE can be an IL-23 driven Th17 cell mediated disease [4]. EAE can be induced by adoptive transfer of myelin-specific CD4+ T cells [5]. All the above data demonstrate the significance of T cells in EAE induction [6]. The mechanisms which underlie T cell proliferation and differentiation associated with EAE induction and development are not fully understood, and details of the signaling pathways that induce Th1 or Th17 cells in EAE are complex and not completely known
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