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Effect of Kidney Disease and Gut-Derived Uremic Toxins on Flavin Monooxygenases: Clinical and Translational Research Studies

Prokopienko, Alexander (2019) Effect of Kidney Disease and Gut-Derived Uremic Toxins on Flavin Monooxygenases: Clinical and Translational Research Studies. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Cardiovascular disease (CVD) is the leading cause of death in patients with kidney disease. Unfortunately, therapeutic strategies targeting traditional risk factors have limited impact on reducing CVD outcomes, suggesting that non-traditional CVD risk factors may play an important role in kidney disease. In fact, the altered kidney disease gut microbiome is a source of several non-traditional CVD risk factors. In particular, trimethylamine-N-oxide (TMAO) is formed from gut microbiota production of trimethylamine and hepatic flavin monooxygenase (FMO) metabolism. The overarching objective of this dissertation was to investigate the effect of kidney disease and gut-derived toxins on flavin monooxygenase activity. To achieve these goals, an analytical method was developed and validated to measure gut-derived toxins including kynurenic acid, hippuric acid, indoxyl sulfate and p-cresol sulfate.

In vitro studies utilizing rat microsomes demonstrated significant increases in the formation of TMAO in the kidney disease group versus the control, suggesting increased FMO activity. Although gene and protein expression of FMO were not changed, metabolic activation elicited by octylamine and presence of human uremic serum increased FMO-mediated TMAO formation. Ex vivo translational studies using primary cultures of human hepatocytes demonstrated that exposure to indoxyl sulfate, a gut-derived toxin, increases FMO3 expression and FMO-mediated TMAO formation. The findings suggest that metabolic activation and indoxyl sulfate exposure increase FMO activity and represent novel mechanisms that contribute to increased TMAO formation in kidney disease and may be a therapeutic target to reduce TMAO exposure and CVD.

In a pilot clinical study, a novel strategy to reduce formation of TMAO with diindolylmethane was investigated in Stage 3-4 kidney disease patients. Gut-derived uremic toxins and corresponding intestinal microbiome profiles were also assessed. The findings demonstrated that diindolylmethane reduced serum TMAO concentrations in males compared to females. The microbiota composition was also significantly altered in the kidney disease patients compared to control. Furthermore, the microbiota was a strong predictor of gut-derived toxin exposure.

Collectively, this work advances our understanding of potential increases in FMO activity and microbiota alterations in kidney disease that will facilitate future work to develop therapeutic strategies to reduce CVD.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Prokopienko, AlexanderAJPROKOP@pitt.eduAJPROKOP
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorNolin, Thomasnolin@pitt.edunolin
Committee MemberPoloyac, Samuelpoloyac@pitt.edupoloyac
Committee ChairVenkataramanan, Ramanrv@pitt.edurv
Committee MemberJohnston, Paulpaj18@pitt.edupaj18
Committee MemberMcDermott, Leelam179@pitt.edulam179
Committee MemberStubbs,
Date: 13 August 2019
Date Type: Publication
Defense Date: 24 July 2019
Approval Date: 13 August 2019
Submission Date: 9 August 2019
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 234
Institution: University of Pittsburgh
Schools and Programs: School of Pharmacy > Pharmaceutical Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: kidney disease drug metabolism cardiovascular disease
Date Deposited: 13 Aug 2019 12:15
Last Modified: 13 Aug 2021 05:15


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