Thesis
Development of adverse outcome pathways framework for the identification of novel mechanistic and clinical insights into the cardiotoxic actions of thiazolidinediones
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17136
- Person Identifier (Local)
- 202071294
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Type 2 diabetes mellitus (T2DM) represents a burgeoning global pandemic that has currently afflicted nearly half a billion individuals. With the uncertainties surrounding the underlying pathoetiogenesis and course of T2DM, lifelong medication adherence remains the central cornerstone of comprehensive disease management. Thiazolidinediones (TZDs), represented by pioglitazone and rosiglitazone, are a class of cost-effective oral anti-diabetic agents that pose a marginal hypoglycaemia risk. While TZDs initially demonstrated efficacy in maintaining glycaemic control, safety concerns, particularly regarding their cardiotoxicity, have restricted their clinical usefulness. The uncharacterised mechanisms underlying TZD-induced cardiotoxicity continue to fuel debate, limiting the broader application of TZDs as a treatment option. Capitalising on the increasing potential of omics technologies, this project integrated an adverse outcome pathway framework that combined traditional in vitro toxicity testing with multi-omics approaches to illuminate the mechanisms underlying the cardiotoxicity debate surrounding TZD use. In vitro cytotoxicity testing of TZDs against AC16 human adult cardiomyocytes and primary human cardiac fibroblasts revealed a novel crosstalk between TZDs and mitochondrial dysfunction, manifested by perturbations in mitochondrial energetics and the induction of oxidative stress independent of PPAR-γ activation, highlighting two potential key mechanisms by which TZDs exert their cytotoxic actions on cardiac cells. Accordingly, to gain a more comprehensive understanding of the metabolic changes induced by TZDs, an untargeted liquid chromatography–mass spectrometry (LC–MS)-based toxicometabolomics pipeline was used, with AC16 cells as a model system. The toxicometabolomics analysis revealed a significant modulation in carnitine content after the acute administration of either TZD agent, reflecting the potential disruption of the mitochondrial carnitine shuttle. Furthermore, perturbations were observed in purine metabolism and amino acid fingerprints, strongly conveying aberrations in the cardiac energetics associated with TZD use. The analysis of our findings also highlighted alterations in polyamine (spermine and spermidine) and amino acid (Ltyrosine and valine) metabolisms, which are known modulators of cardiac hypertrophy, suggesting a potential link to TZD cardiotoxicity that necessitates further research. To further complement the metabolic changes found at the most downstream molecular level, an LC–MS-based toxicoproteomics pipeline on AC16 cells was conducted. Our toxicoproteomics analysis revealed a mitochondrial dysfunction accompanying TZD exposure that primarily stemmed from impaired oxidative phosphorylation, with distinct signalling mechanisms observed for both agents. Furthermore, our analysis revealed additional mechanistic aspects of cardiotoxicity, showing drug specificity. The downregulation of various proteins involved in the protein machinery and protein processing in the endoplasmic reticulum was observed in rosiglitazone-treated cells, implicating proteostasis in rosiglitazone cardiotoxicity. Regarding pioglitazone, the findings suggest the potential activation of the interplay between the complement and coagulation systems and the disruption of the cytoskeletal architecture, which was primarily mediated by the integrin-signalling pathways responsible for pioglitazoneinduced myocardial contractile failure. Finally, to move beyond association and establish causality in the observed effects, a multi-omics approach that integrated toxicoproteomics and toxicometabolomics data was implemented. A network analysis of proteometabolomic data revealed a distinct fingerprint of disrupted biochemical pathways, which were primarily related to energy metabolism. In addition, the study identified a marked disruption in the glutathione system, indicating an imbalanced redox state triggered by TZD exposure. In conclusion, the combined findings from our framework illuminate novel molecular mechanisms, potentially offering a resolution to the decades-long controversy surrounding the cardiotoxicity of TZDs. This research showcases the transformative power of combining traditional and omics-based methods that enables the re-evaluation of long-neglected medications and signals a new era of safer medications and improved patient compliance.
- Advisor / supervisor
- Rattray, Nicholas
- Khadra, Ibrahim
- Resource Type
- DOI
- Funder
关系
项目
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PDF of thesis T17136 | 2025-01-16 | 公开 | 下载 |