Schlafen-8 is essential for lymphatic endothelial cell activation in experimental autoimmune encephalomyelitis

Abstract

Schlafen-8 (Slfn8) is a member of the Schlafen family of proteins, which harbor helicase domains and are induced by LPS and interferons. It has been reported that the Schlafen family are involved in various cellular functions, including proliferation, differentiation and regulation of virus replication. Slfn8 has been implicated in T-cell differentiation in the thymus. However, the roles of Slfn8 in the immune system remains unclear. In this study, we generated Slfn8 knockout mice (Slfn8^−/−) and investigated the immunological role of Slfn8 using the T-cell-mediated autoimmune model experimental autoimmune encephalomyelitis (EAE). We found that the clinical score was reduced in Slfn8^−/− mice. IL-6 and IL-17A cytokine production, which are associated with EAE onset and progression, were decreased in the lymph nodes of Slfn8^−/− mice. Immune cell populations in Slfn8^−/− mice, including macrophages, neutrophils, T cells and B cells, did not reveal significant differences compared with wild-type mice. In vitro activation of Slfn8^−/− T cells in response to TCR stimulation also did not reveal significant differences. To confirm the involvement of non-hematopoietic cells, we isolated CD45⁻ CD31⁺ endothelial cells and CD45⁻CD31⁻ gp38⁺ fibroblastic reticular cells by FACS sorting. We showed that the levels of IL-6 and Slfn8 mRNA in CD45⁻ CD31⁺ endothelial cells were increased after EAE induction. In contrast, the level of IL-6 mRNA after EAE induction was markedly decreased in CD31⁺ endothelial cells from Slfn8^−/− mice. These results indicate that Slfn8 may play a role in EAE by regulating inflammation in endothelial cells.