Glycosphingolipids Prevent APAP and HMG-CoA Reductase Inhibitors-mediated Liver Damage: A Novel Method for "Safer Drug" Formulation that Prevents Drug-induced Liver Injury.

Background and Aims: Acetaminophen (APAP) and HMG-CoA reductase inhibitors are common causes of drug-induced liver injury (DILI). This study aimed to determine the ability to reduce APAP- and statins-mediated liver injury by using formulations that combine glycosphingolipids and vitamin E. Methods: Mice were injected with APAP or with statins and treated before and after with ß-glucosylceramide (GC), with or without vitamin E. Mice were followed for changes in liver enzymes, liver histology, hepatic expression of JNK, STAT3 and caspase 3, as well as intrahepatic natural killer T cells (NKT) and the serum cytokine levels by flow cytometry. Results: Administration of GC before or after APAP alleviated the liver damage, as noted by a reduction of the liver enzymes, improvement in the liver histology and decreased hepatic caspase 3 expression. Beneficial effect was associated with a reduction of the intrahepatic NKT, JNK expression in the liver, and increased glutathione in the liver, and decreased TNF-α serum levels. Synergistic effect of co-administration of GC with vitamin E was observed. Similar protective effect of GC on statin-mediated liver damage was documented by a reduction in liver enzymes and improved liver histology, which was mediated by reduction of NKT, increased STAT3 expression in the liver, and reduced the TGF-ß and IL17 levels. Conclusions: ß-glycosphingolipids exert a hepatoprotective effect on APAP- and statins-mediated liver damage. Vitamin E exerted a synergistic effect to that of GC. The generation of "safer drug" formulations, which include an active molecule combined with a hepatoprotective adjuvant, may provide an answer to the real unmet need of DILI.

Decreased STAT-1 phosphorylation by a thio analogue of beta-D-glucosylceramide is associated with altered NKT lymphocyte polarization.

UNLABELLED: Glycolipid presentation to natural killer T (NKT) lymphocytes by CD1 proteins is important for antigen recognition. It was recently suggested that beta-glycolipids exert an immune-modulatory effect on NKT lymphocytes, alleviating immune-mediated disorders. The current study aimed to determine the effect of ligand structure on intrahepatic NKT lymphocyte function in concanavalin A (ConA) hepatitis, an NKT-mediated disorder. C57BL/6 mice were injected with a non-degradable beta-D-glucosylceramide containing a thioglycosidic bond (GCT), beta-D-glucosylceramide (GC), or vehicle. The phosphorylation of STAT-1, intrahepatic NKT lymphocyte number, and serum IFN-gamma levels were determined. Liver damage was assessed by serum transaminases and the degree of apoptosis. The administration of GCT led to a significant inhibitory effect on intrahepatic NKT lymphocytes. Both GCT and GC led to a decrease in STAT-1 phosphorylation and a decrease in IFN-gamma serum levels. These effects were associated with the alleviation of ConA immune-mediated hepatitis, as determined by a similar substantial decrease in serum transaminases and a profound decrease in apoptosis as noted by TUNEL assay, and were NKT-type I dependent. CONCLUSION: Alteration of the chemical structure of the GC by replacing the O-glycosidic bond with an S-glycosidic bond results in a non-degradable molecule GCT and significantly suppresses intrahepatic NKT lymphocytes. These results suggest that cellular events that alter the enzymatic pathways of glycosylceramides serve as an initial stimulus for NKT cell polarization in vivo.