The leukotriene B4 receptor, BLT1, is required for the induction of experimental autoimmune encephalomyelitis

Leukotriene B4 (LTB4) is a potent chemoattractant and activator of neutrophils, macrophages and T cells. These cells are a key component of inflammation and all express BLT1, a high affinity G-protein-coupled receptor for LTB4. However, little is known about the neuroimmune functions of BLT1. In this study, we describe a distinct role for BLT1 in the pathology of experimental autoimmune encephalomyelitis (EAE) and TH1/TH17 immune responses. BLT1 mRNA was highly upregulated in the spinal cord of EAE mice, especially during the induction phase. BLT1−/− mice had delayed onset and less severe symptoms of EAE than BLT1+/+ mice. Additionally, inflammatory cells were recruited to the spinal cord of asymptomatic BLT1+/+, but not BLT1−/− mice before the onset of disease. Ex vivo studies showed that both the proliferation and the production of IFN-γ, TNF-α, IL-17 and IL-6 were impaired in BLT1−/− cells, as compared with BLT1+/+ cells. Thus, we suggest that BLT1 exacerbates EAE by regulating the migration of inflammatory cells and TH1/TH17 immune responses. Our findings provide a novel therapeutic option for the treatment of multiple sclerosis and other TH17-mediated diseases.