Effect of Non-Alcoholic Fatty Liver Disease (Nafld) on Hepatic Drug Metabolism Enzymes in Human

Abstract

Significant changes in dietary habits have led to a rampant increase in metabolic disorders. Non-alcoholic fatty liver disease (NAFLD) is one such disorder characterized by the excess buildup of fat in hepatocytes of people who drink little or no alcohol. If not managed, NAFL (simple steatosis) progress into nonalcoholic steatohepatitis (NASH) and further deteriorate to cirrhosis leading to severe illness or even death. Drug disposition proteins (enzymes and transporters) in liver control the systemic exposure of drugs and xenobiotics in human and drive the efficacy as well as adverse events in the body. Therefore, it is critical to address the effect of NAFLD on the abundance of these proteins. A variation would result in an altered pharmacokinetic and/or pharmacodynamic profile of substrate drugs in patients with NAFLD. Most studies were performed in preclinical species (rat, mice) and only a few reports are available in human. The primary objective of this doctoral project was to investigate the effect of NALFD on the abundance of hepatic drug disposition proteins (DDP) in a human liver-bank. The levels of proteins were determined using an LC-MS/MS based label-free, global proteomics method. In addition, CYP3A4 enzyme kinetics parameters were determined using midazolam as a probe substrate. Considerable changes in the protein expression and activity of CYP3A4 and CYP1A2 were found in NAFL and NASH. Only marginal alterations were observed for other cytochrome P450 enzymes in this study. Levels of uridine 5'-diphosphoglucuronosyltransferases (UGT) and sulfotransferases (SULT) in NAFLD were mostly unaltered. Dysregulation of mitochondrial proteins involved in lipid metabolism (ACADSB, ACSM3/5, CPS1) was also observed. A significant downregulation of CYP3A4 protein and activity but not mRNA in NAFLD was observed suggesting that post-transcriptional changes may play a more significant role in the observed phenotypic perturbations for the isoform. Overall, enzyme kinetics and quantitative protein abundance data from this project will be important in the development of physiologically based pharmacokinetic (PBPK) models for prediction of drug disposition in the NAFLD population iv ACKNOWLEDGMENTS First and foremost, I would like to thank and extend my gratitude to my doctoral research advisor, Prof. Fatemeh Akhlaghi. Through this journey of completing my dissertation, she has supported and contributed to my development and growth as a researcher and a person. I am especially indebted to you for believing in me and giving me an opportunity to be a part of your lab. Thank you, Dr. Akhlaghi. I thank my committee member Professors Navindra Seeram and Ingrid Lofgren for their continuous support throughout this process. I also want to acknowledge Prof. Sara Rosenbaum and others who guided and supported me. I would be amiss not to thank Kathleen Hayes for help throughout this journey. I am grateful to my colleagues and friends without whom I couldn't have made it this far. Sravani, thank you for your friendship and support....

Considerations for Physiologically Based Modeling in Liver Disease: From Nonalcoholic Fatty Liver (NAFL) to Nonalcoholic Steatohepatitis (NASH)

“… 36 Protein levels of hepatic CYP2E1 in patients with NAFLD did not seem to increase substantially compared with a BMI‐matched non‐NAFLD control group. 39 The apparent clearance (clearance/oral bioavailability) of chlorzoxazone, a selective CYP2E1 probe, in non‐T2DM NASH patients was only slightly higher (24% difference in mean values) than that of healthy individuals with a similar BMI range. 60 This was in concordance with the formation of 6‐hydroxychlorzoxazone (catalyzed by CYP2E1), which was not altered in obese patients with NAFL, but was higher in morbidly obese NASH patients compared with a non‐NAFLD obese cohort.…”

“…65,66 This is in line with nonsignificant changes in protein levels of CYP2C9 (involved in warfarin metabolism) and CYP4F2 (responsible for catabolism of vitamin K and associated with interindividual variability in warfarin response) in patients with non-cirrhotic NAFLD compared with non-NAFLD individuals with similar BMI. 39 Despite observing no change in warfarin daily dose relative to the control group, Zhang et al 66 reported a lower international normalized ratio to warfarin dose ratio in NAFLD (cirrhosis status not reported), suggesting potential NAFLDmediated alterations in vitamin K regulation or other pharmacodynamic factors that may impact warfarin response. It should be noted, however, that this study did not control for pharmacogenetic factors involved in warfarin response.…”

“…Trends of NAFLD‐associated changes in protein levels of CYP and non‐CYP enzymes generally were consistent across different studies included in Table 2 , although some variation was noted in the extent of fold‐changes compared to controls. Only two studies 30 , 39 used a BMI‐matched non‐NAFLD cohort as the comparator for evaluation of changes in DME abundance. This is particularly important for accurate interpretation of proteomic data due to apparent negative and positive correlations between BMI and activity of CYP3A4 and CYP2E1, respectively.…”