Protective effects of histamine H4 receptor antagonist on the inflammatory responses in B cells in a mouse model of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS) driven by autoimmune mechanisms. However, growing evidence indicates that B lymphocytes may contribute to the disease through antigen presentation and the production of proinflammatory mediators. This study aimed to examine the effect of JNJ 10191584 (JNJ), a potent and selective H4R antagonist, on the progression of EAE and to uncover the underlying mechanisms. The research explored the potential impact of H4R antagonists on inflammatory responses in B cells within an EAE mouse model of MS. EAE mice received an oral dose of JNJ at 6 mg/kg daily, starting on day 10 and continuing until day 42. Flow cytometry assessed JNJ's effect on the expression of NF-κB p65, IκBα, Notch1, Notch3, IL-2, IL-6, GM-CSF, iNOS, TNF-α, and MCP-1 in CD19+ B cells. RT-PCR was used to evaluate the impact of JNJ on mRNA levels of these inflammatory markers in brain tissue. In EAE mice, JNJ treatment reduced the number of CD19+ cells expressing NF-κB p65, IκBα, Notch1, Notch3, IL-2, IL-6, GM-CSF, iNOS, and MCP-1. Additionally, JNJ decreased mRNA expression of inflammatory markers in brain tissue compared with vehicle-treated mice. These results suggest that targeting H4R with antagonists could offer a new therapeutic approach for MS by specifically modulating B-cell-mediated inflammation.