Lack of CerS2 Suppresses the Development of Experimental Autoimmune Encephalomyelitis by Impairing the Migratory Potential of Neutrophils (P5.343)

Objective: evaluate Ceramide contribution to CNS inflammatory processes in MS and define possible new therapeutical Targets Background: Ceramide synthases (CerS) synthesize chain length specific ceramides which are supposed to mediate cellular processes in a chain length dependent manner. Methods: Bone marrow cells were cultured in RPMI 1640 Glutamax. Human blood was collected within the biobanking project at the Dept of Neurology (Frankfurt/Main) from 37RRMS , 23PMSpatients and 16controls. Bone marrow transplantation was achieved using 10- to 12-week-old female 129S4/SvJae×C57BL/6 mice (CerS2-WT, CerS2-KO). Tissue studies, immunohistochemistry, isolation of immune cells, Real-time qPCR and determination of sphingolipid concentrations and FACS analysis were performed. Western blot analysis was done for protein extract separation. Results: In EAE, we observed a significant elevation of CerS2/C24-ceramides in CD11b+ blood-cells (monocytes and neutrophils) corresponding to the finding that CerS2-mRNA expression and C24-Ceramide levels were significantly increased 2.2 and 1.5 fold in WBCs of MS patients. The increased CerS2 mRNA/C24-Ceramide expression in neutrophils/monocytes seems to mediate pro-inflammatory effects, since specific genetic deletion of CerS2 in blood cells or total genetic deletion of CerS2 significantly delayed the onset of clinical symptoms due to a reduced amount of immune cells, predominantly neutrophils, in the CNS. Chemokine receptor CXCR2 on neutrophils promotes their migration into the CNS (which is a prerequisite for further immunecell recruitment and inflammatory processes causing MS). Neutrophils isolated from CerS2-KO EAE mice showed significantly lower chemokine receptor CXCR2 mRNA-expression levels resulting in a reduced migratory potential towards CXCL2 compared to CerS2-WT EAE mice. Most importantly, G-CSF induced CXCR2 expression is significantly reduced in CerS2-KO neutrophils and migratory potential significantly impaired. Conclusions: Our our data strongly indicate that G-CSF induced CXCR2 expression is CerS2 dependent regulated and that CerS2 thereby promotes the migration of neutrophils and contributes by these pro-inflammatory effects to the development of EAE and MS. Disclosure: Dr. Mayer has received personal compensation for activities with Biogen and Genzyme as a speaker. Dr. Barthelmes has nothing to disclose. Dr. Pewzner-Jung has nothing to disclose. Dr. Schmitz has nothing to disclose. Dr. Maenner has nothing to disclose. Dr. Foerch has received personal compensation for activities with Genzyme, Teva, Bayer, Merck. Dr. Eberle has nothing to disclose. Dr. Tafferner has nothing to disclose. Dr. Ferreiros Bouzas has nothing to disclose. Dr. Birod has nothing to disclose. Dr. Geisslinger has nothing to disclose. Dr. Futerman has nothing to disclose. Dr. Grosch has nothing to disclose. Dr. Birod has nothing to disclose. Dr. Schuhmann has nothing to disclose.