Experimental autoimmune encephalomyelitis is a T cell-mediated demyelinating disease of the CNS that serves as a model for the human disease multiple sclerosis. Increased expression of the chemokine CCL2 in the CNS has been demonstrated to be important in the development of demyelinating disease presumably by attracting inflammatory cells. However, the mechanism of how CCL2 regulates disease pathogenesis has not been fully elucidated. Using radiation bone marrow chimeric mice we demonstrated that optimum disease was achieved when CCL2 was glia derived. Furthermore, CNS production of CCL2 resulted in the accumulation of iNOS-producing CD11b+CD11c+ dendritic cells and TNF-producing macrophages important for demyelination. Lack of glial-derived CCL2 production did not influence experimental autoimmune encephalomyelitis by altering either Th1 or Th17 cells, as there were no differences in these populations in the CNS or periphery between groups. These results demonstrate that the glial-derived CCL2 is important for the attraction of TNF- and iNOS-producing dendritic cells and effector macrophages to the CNS for development of subsequent autoimmune disease.

Chemokines and their receptors play a critical role in orchestrating the immune response during experimental autoimmune encephalomyelitis (EAE). Expression of CCR4 and its ligand CCL22 has been observed in ongoing disease. Here we describe a role for CCR4 in EAE, illustrating delayed and decreased disease incidence in CCR4−/− mice corresponding with diminished CNS infiltrate. Peripheral T cell responses were unaltered in CCR4−/− mice; rather, disease reduction was related to reduced CD11b+Ly6Chi inflammatory macrophage (iMϕ) numbers and function. These results provide evidence that CCR4 regulates EAE development and further supports the involvement of CCR4 in iMϕ effector function.

This article focuses on the distinct role of chemokines and chemokine receptors during CNS inflammation in experimental autoimmune encephalomyelitis (EAE) as an animal model for multiple sclerosis (MS). We review the evidence that chemokines and chemokine receptors have an intrinsic role in regulating and amplifying the inflammatory reactions in EAE or MS leading to disease outcome. A variety of studies examining temporal chemokine expression patterns, using chemokine and chemokine receptor knockout mice as well as administering passive anti-chemokine antibodies indicates that these molecules are critical regulatory components for leukocyte recruitment and/or leukocyte retention in the CNS. Therefore, chemokine and chemokine receptor expression is tightly interrelated to composition of inflammatory cells in CNS lesions and the onset of clinical diseases and provide viable targets for therapeutic intervention.