Differing Outcome of Experimental Autoimmune Encephalitis in Macrophage/Neutrophil- and T Cell-Specific gp130-Deficient Mice.

gp130 cytokines are differentially involved in regulating the T helper (H) 17-driven pathogenesis of experimental autoimmune encephalomyelitis (EAE), the animal model of human multiple sclerosis. Interleukin (IL)-6 directly promotes the development of TH17 cells through the gp130/IL-6R complex. By contrast, IL-27 has been shown to suppress a TH17 immune response by gp130/ IL-27R-alpha (alpha) receptor ligation. The IL-27-dependent regulation of a TH17 development could be mediated on the level of CD4 T cells. However, because IL-27 also suppresses the secretion of the TH17-driving cytokines IL-6 and IL-12/23p40 in accessory cells, TH17 immune responses may also be controlled by IL-27 on the level of macrophages and/or neutrophils. To analyze these opposing effects of gp130 engagement on the pathogenesis of EAE, we immunized CD4(+) T cell-specific gp130-deficient (CD4cre(pos)gp130(loxP/loxP)) and macrophage/neutrophil-specific gp130-deficient (LysMcre(pos)gp130(loxP/loxP)) mice with the myelin-oligodendrocyte-glycoprotein peptide MOG(35-55). Whereas inflammatory immune responses, TH17 differentiation, and pathology in CD4cre(pos)gp130(loxP/loxP) mice were mitigated, disease progression was eventually enhanced in LysMcre(pos)gp130(loxP/loxP) mice. Exacerbated disease in MOG(35-55)-immunized LysMcre(pos)gp130(loxP/loxP) mice was associated with an elevated development of TH17 cells and increased infiltration of the central nervous system with leukocytes indicating a suppressive role of macrophage/neutrophil-gp130. To further prove IL-6 to be responsible for the control of inflammation during EAE through gp130 on macrophages/neutrophils, we immunized LysMcre(pos)IL-6R(loxP/loxP) mice. In contrast to LysMcre(pos)gp130(loxP/loxP) mice, neuropathology in MOG(35-55)-immunized macrophage/neutrophil-specific IL-6R-deficient mice was not enhanced indicating that the alleviation of EAE through macrophage/neutrophil-gp130 is mediated independently of IL-6. Together, this different pathology in macrophage/neutrophil- and CD4 T cell-specific gp130-deficient mice suggests that gp130 cytokines modulate TH17 inflammation differentially by targeting distinct cell types.