Advancing the mechanistic understanding of the toxicological effects of non-steroidal anti-inflammatory drugs (NSAIDs) using integrated in silico and in vivo approaches

Abstract

Non-steroidal anti-inflammatory drugs (NSAIDs) have been available on the market for over 100 years, and they are some of the most widely and highly consumed pharmaceuticals worldwide. Everyday millions of people take NSAIDs to effectively relieve conditions involving inflammation and pain, however, their long-term therapeutic use is associated with many adverse effects which are characterised by a wide range of severity. Moreover, due to their high volume of consumption, NSAIDs excreted by patients are often detected in the aquatic environment raising concerns about possible adverse effects in aquatic wildlife. These multi-species safety concerns led to various regulatory actions aimed at protecting both human and environmental health over the last 20 years. Nonetheless, after decades of research our understanding of NSAIDs toxicological effects in multiple organs and systems remains incomplete. Here, we describe the development and integration of in silico and in vivo approaches to help further our mechanistic understanding of NSAIDs-mediated effects and to support NSAIDs safety assessment. Novel data mining, integration, and modelling of existing multi-dimensional datasets (Chapter 2) was used to generate accurate in silico predictions of the hazards and risks associated with exposure to both individual NSAIDs, and their mixtures. This computational approach led to the development of an innovative and predictive pharmacology-informed framework able to support the environmental risk assessment of NSAIDs mixtures in the environment, removing the need for additional in vivo testing (Chapter 3). This computational workflow also led to the identification of immunomodulation as a key mode-of-action for NSAIDs warranting further investigation. The in vivo characterisation of NSAIDs immunomodulatory effects in the gastrointestinal tract of zebrafish larvae revealed several novel findings (Chapter 4). Firstly, the activation and transendothelial migration of neutrophils into the intestine was identified as a probable key event in the pathogenesis of NSAIDs-induced enteropathy. Secondly, inhibition of the resolution of inflammation was identified as a novel putative mechanism of toxicity for the non-selective NSAID diclofenac. These effects may significantly hamper the ability of the gastrointestinal mucosa to resolve NSAIDs-induced neutrophilic inflammation, and ultimately lead to tissue damage. Furthermore, significant differences between selective and non-selective NSAIDs were revealed at both cellular and transcriptomic levels. Overall, the experimental results presented in this thesis support the notion that the mechanisms driving NSAIDs effects extend well beyond their primary mode-of-action (cyclooxygenase inhibition), and demonstrate the significance of immunomodulatory processes in mediating these effects within the gastrointestinal tract.