Differential Lipid Profiles in Experimental Steatohepatitis: Role for Imaging Mass Spectrometry as a Diagnostic Aid
Author(s): Emine B Yalcin, Kavin Nunez, Dale S Cornett, and Suzanne M de la Monte
Background. Ethanol, tobacco-specific nitrosamine ketone (NNK), and ethanol+NNK exposures cause steatohepatitis, suggesting that smoking can be a cofactor in alcoholic liver disease. Study design. We used MALDI-TOF imaging mass spectrometry (IMS) to characterize hepatic lipid profiles in steatohepatitis caused by ethanol, NNK, and ethanol+NNK. Results. Ethanol, NNK, and ethanol+NNK increased levels and altered the profiles of hepatic phospholipids. Ethanol caused striking accumulations of m/z 932.7 phosphatidylinositol (PI). NNK increased hepatic levels of PIs with m/z’s of 934.8, 960.8, and 962.7. Relative abundance of PIs with m/z’s of 857.9 or 883.7 increased progressively from control to NNK, then ethanol, and finally ethanol+NNK, indicating differential and additive effects of these exposures. In contrast, no differences occurred with respect to phosphatidylethanolamine (m/z 766.9), phosphatidylserine (m/z 810.9) or PIs with m/z of 960.8 or 962.7. Principal component analysis generated distinct exposure-related hepatic lipid profiles. Conclusion. MALDI-IMS could serve as a complementary diagnostic aid for differentiating underlying causes of steatohepatitis.