Ceramide concentrations in liver, plasma, and very low-density lipoproteins of humans with severe obesity.

Abstract

We investigated the relationships between ceramide species concentrations in liver, plasma and very low-density lipoproteins (VLDL) particles of humans with obesity as well as the relationships between hepatic fat content and hepatic ceramide concentrations and proportional distribution. Twenty-five obese (body mass index >35 kg/m2 ) adults participated in this study. Plasma, VLDL and hepatocellular ceramide concentrations were measured by liquid chromatography/tandem mass spectrometry. The proportionate distribution of measured ceramide species differed between liver, whole plasma and the VLDL fraction. We found significant, positive correlations between the proportion of C14:0, C18:0, C20:0 and C24:1 ceramide in the liver and whole plasma (γ=0.491, p=0.013; γ=0.573, p=0.003; γ=0.479, p=0.015; γ=0.716, p=0.00006; respectively). In contrast, only the proportional contribution of C24:1 ceramide correlated positively between VLDL and liver (γ=0.425, p=0.013). The percent hepatic fat correlated positively with the proportion of C18:1, C18:0 and C20:0 hepatic ceramides (γ=0.415, p=0.039; γ=0.426, p=0.034; γ=0.612, p=0.001; respectively), but not with total hepatic ceramide concentration. The proportions of whole plasma ceramide subspecies, especially C14:0, C18:0, C20:0 and C24:1chain length, are reflective of those of hepatic ceramide subspecies in obese humans; these appear to be markers of hepatic ceramide species composition.