1B) with no significant difference in spinal cord pathology (Fig. 1C). Disruption of BBB permeability is another parameter used to assess the neuroinflammatory response in EAE and susceptibility to disease. At day 10 (d10) postimmunization, we found that B6 and H3H4RKO mice had increased BBB permeability during the acute early phase of the disease compared with that of H1H2RKO mice (Fig. 1D).

These results indicate that the combined effect of disrupting H1R and H2R signaling is antipathogenic in EAE, whereas the combined effect of disrupting ABT-263 mw H3R and H4R signaling is propathogenic. HA and HRs have been shown to be important in regulating hematopoiesis [[39-41]]. We examined the frequency of different cell types in the primary and secondary lymphoid tissues of naïve B6, H1H2RKO, and H3H4RKO mice. There was no significant difference in the total number of cells in the thymus, lymph node, or spleen among the three strains (Fig. 2A). ALK inhibitor We also analyzed the frequency of CD4+, CD8+, Foxp3+

Treg, B cell (CD19+), CD11b+, CD11b+Gr1+, NKT (CD1d tetramer+), and NK (NKp46+) cells in primary and secondary lymphoid tissues and found no significant differences in the frequency of these cell types (Fig. 2B, C, D, and E), with the only exception being the lymph node B-cell frequency, which was significantly decreased in H3H4RKO compared with H1H2RKO mice (Fig. 2C). These results strongly suggest that the differences in EAE susceptibility observed between H1H2RKO and H3H4RKO mice are not due to differences in the frequency of immune cells in the primary and secondary lymphoid tissues. Although the exact pathogenic mechanisms underlying MS and EAE are not known, it is thought to be highly dependent on CD4+ T cells capable of producing IFN-γ and/or IL-17 [[2]]. HA and HRs play a role in T-cell polarization, proliferation, and cytokine production [[4]]. Therefore,

to elucidate the immune mechanisms associated with differential EAE susceptibility observed in B6, H1H2RKO, and H3H4RKO mice, we compared their MOG35–55-specific T-cell responses on d10 post immunization. In ex vivo proliferation assays, Protein kinase N1 splenocytes and draining lymph node (DLN) cells from all three strains responded equivalently in a dose-dependent fashion to MOG35–55 (Fig. 3A). Splenic and DLN cells from H1H2RKO mice restimulated ex vivo with MOG35–55 produced significantly less IFN-γ (Fig. 3B) and IL-17 (Fig. 3C) compared with restimulated cells from H3H4RKO mice. In addition, H3H4RKO mice produced significantly more IFN-γ and IL-17 compared with B6 mice. IL-4 was undetectable among the three strains. These results suggest that the differences in EAE susceptibility observed in H3H4RKO mice can, in part, be attributed to increased encephalitogenic Th1 and Th17 effector T-cell responses. Previously, we showed that H1R regulates IFN-γ and IL-4 production by activated CD4+ T cells and Th1/Th2 effector T-cell responses [[31]].