Neutral Ceramidase Secreted Via Exosome Protects Against Palmitate-Induced Apoptosis in INS-1 Cells.

Aims: To investigate the effects of neutral ceramidase (NCDase) packaged in exosomes that are secreted from β-cells on free fatty acid (FFA)-induced β-cells apoptosis and its role in regulation of sphingolipid-mediated signaling pathway. Methods: HPLC and Western blotting were performed to determine NCDase activity and expression. Annexin V-fluorescein-isothiocyanate/propidium iodide flow cytometry was used to assess apoptosis. Electrospray ionization tandem mass spectrometry was used for ceramide (Cer), sphingosine-1-phosphate (S1P), and sphingosine (SPH) determination. Results: INS-1 cells over-expressed NCDase secreted active NCDase via exosomes. Exosomes isolated from the cultured medium of INS-1 cells that oxpressed NCDase could ameliorate palmitate-induced apoptosis. Furthermore, the results showed that exosome-derived NCDase treatment reduced intracellular Cer/S1P ratio. Conclusions: β-cell secreted active NCDase via exosome, the exosome-packaged-NCDase protected β-cells from FFA-induced apoptosis through regulating sphingolipid metabolites and it might be a potential treatment for β-cell lipotoxicity and type 2 diabetes.