To investigate the regulatory effects of sphingosine kinase-2 (SphK2) on the function of activated astrocytes and the progression of experimental autoimmune encephalomyelitis (EAE) in mice.

Primary mouse astrocytes were isolated from wild-type (WT) C57BL/6 mice and sphk2 gene knock-out (sphk2^-/-) mice and stimulated in vitro with interleukin 17 (IL-17). Real-time PCR was used to measure the expression of inflammatory cytokines and chemokines at mRNA levels. Western blot and immunofluorescence were used to detect the expression of glial fibrillary acidic protein (GFAP) and the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3). An EAE mouse model was constructed using myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55) polypeptide. Western blot was used to detect the expression of GFAP and p-STAT3 at protein level and real-time PCR was used to detect the expression of inflammatory cytokines and chemokines at mRNA level in spinal cords. Hematoxylin-Eosin (HE) and Luxol fast blue (LFB) staining were used to observe the changes in inflammatory cell infiltration and demyelination in spinal cords.

Compared with the WT group, the phosphorylation of STAT3 was obviously reduced in in vitro activated mouse astrocytes of sphk2^-/- mice, and the expression of inflammatory cytokines and chemokines including monocyte chemotactic protein 1 (MCP-1), TNF-α and IL-6 at mRNA level was also significantly decreased. Compared with the WT EAE group, changes in the above-mentioned cytokines and relative proteins insphk2^-/- EAE mice in vivo were similar to those in vitro. Moreover, inflammatory cell infiltration and demyelination were significantly reduced in spinal cords of sphk2^-/- EAE mice. However, no significant difference in in vitro or in vivo GFAP expression was observed between WT and sphk2^-/- mice.

SphK2 might regulate the function of reactive astrocytes through STAT3 molecular pathway, thereby regulating the production of inflammatory cytokines and chemokines and participating in the pathological process of EAE.

Sphingosine kinase-2; Astrocytes; Experimental autoimmune encephalomyelitis; Glial fibrillary acidic protein; Signal transduction and transcription activator 3; inflammatory cytokines