Clinical and Translational Research
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Apr 27, 2021; 13(4): 433-455
Published online Apr 27, 2021. doi: 10.4254/wjh.v13.i4.433
Bile acid indices as biomarkers for liver diseases I: Diagnostic markers
Jawaher Abdullah Alamoudi, Wenkuan Li, Nagsen Gautam, Marco Olivera, Jane Meza, Sandeep Mukherjee, Yazen Alnouti
Jawaher Abdullah Alamoudi, Wenkuan Li, Nagsen Gautam, Yazen Alnouti, Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198, United States
Jawaher Abdullah Alamoudi, Department of Pharmaceutical Sciences, College of Pharmacy, Princess Nourah Bint Abdulrahman University, Riyadh 11564, Saudi Arabia
Marco Olivera, Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198, United States
Jane Meza, Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, United States
Sandeep Mukherjee, Department of Internal Medicine, College of Medicine, Creighton University Medical Center, Omaha, NE 68124, United States
Author contributions: Alamoudi JA is the primary researcher, collected and analyzed data, wrote the manuscript, prepared figures and formatted manuscript for publication; Li W and Gautam N helped in the liquid chromatography-tandem mass spectrometry sample analysis; Meza J supervised, reviewed, and approved all statistical analysis and provided intellectual input and feedback on manuscript; Olivera M and Mukherjee S helped in recruiting and consenting patients and sample collection as well as experimental design; Alnouti Y is the primary investigator who was responsible for the experimental design and supervising all aspects of this project and manuscript preparation.
Supported by University of Nebraska Medical Center-Clinical Research Center and Great Plains Health Research Consortium; and Society of American Gastrointestinal and Endoscopic Surgeons, No. 36-5360-2186-001.
Institutional review board statement: The study was reviewed and approved by the University of Nebraska Medical Center Institutional Review Board (approval No. 487-10-EP).
Clinical trial registration statement: This study is registered at ClinicalTrials.gov. The registration identification number is NCT01200082.
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors declare that there is no conflict of interests in this study.
Data sharing statement: Technical appendix, statistical code, and data set available from the corresponding author at yalnouti@unmc.edu. Participants gave informed consent for data sharing.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Yazen Alnouti, PhD, Professor, Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 557 S 42nd Street, Omaha, NE 68198, United States. yalnouti@unmc.edu
Received: January 5, 2021
Peer-review started: January 5, 2021
First decision: January 25, 2021
Revised: February 11, 2021
Accepted: March 22, 2021
Article in press: March 22, 2021
Published online: April 27, 2021
ARTICLE HIGHLIGHTS
Research background

Bile acids (BA) have been extensively investigated for decades as biomarkers for numerous hepatobiliary diseases. However, these efforts never translated into a widespread in the clinic, due to the extreme inter-and intra-individual variability of total and individual BA concentrations and the marked differences in the physiological and pathological properties of the different individual BA. To this end, we have developed the concept of “BA indices”, which demonstrated their use as diagnostic biomarkers for cholestatic liver diseases.

Research motivation

Biomarkers currently used in the clinic are not specific to the liver or bile duct injurie. BA were extensively investigated for decades as biomarkers for numerous hepatobiliary diseases. This could be attributed to the marked differences in the physiological and pathological properties of the different individual BA. BA indices have much lower variability than the absolute BA concentrations used to calculate them. Indeed, we have demonstrated that BA indices offered numerous advantages over absolute total and individual BA concentrations including low inter- and intra-individual variability and were resistant to covariate influences such as age, gender, body mass index, food consumption, and moderate alcohol consumption.

Research objectives

The objective of this project was to discover and validate diagnostic biomarkers of cholestatic liver diseases based on the urinary BA profile. We have developed the concept of “BA indices”, which are ratios calculated from the absolute concentrations of individual BA and their metabolites. BA indices have much lower variability than the absolute BA concentrations used to calculate them, which enabled their use as diagnostic biomarkers for cholestatic liver diseases.

Research methods

We analyzed urine samples by liquid chromatography-tandem mass spectrometry and compared the urinary BA profile between patients with hepatobiliary diseases vs healthy controls by statistical analysis (independent sample-t-test, Mann-Whitney test, Mixed effects models, by pairwise comparisons using Bonferroni’s adjustment, receiver operating characteristic curve analyses, Univariate and multivariate logistic regression analysis).

Research results

The results of this study demonstrated that total and all individual BA increased in patients with 11 different cholestatic diseases. However, the high inter-individual variability of BA absolute concentrations makes most of them statistically insignificant and prevent their utilization as diagnostic markers. In contrast, BA indices had much lower inter- and intra-individual variability, which allowed their use as diagnostic and prognostic markers for liver diseases. Furthermore, we have shown that several BA indices outperformed non-BA markers, currently used in the clinic, as diagnostic markers to differentiate our patient pool as well as individual cholestatic diseases against healthy controls.

Research conclusions

BA indices demonstrated high area under the receiver operating characteristic curves, and changes of BA indices were associated with the risk of having a liver disease as determined by the logistic regression analysis, which demonstrated their use as diagnostic biomarkers for cholestatic liver diseases.

Research perspectives

We have developed survival models based on BA indices to predict the prognosis of hepatobiliary diseases which is illustrated in the second paper of this series.