UNDERSTANDING MOLECULAR AND PHENOTYPIC EFFECTS OF CYCLO-OXYGENASE IN ZEBRAFISH

The aim of this project is to elucidate the effects of COX inhibitors on immune and gastro-intestinal system of zebrafish and to explore the interplay between the two responses. Using NSAIDs that differ in their ability to inhibit the two COX enzymes, the student will seek molecular and phenotypic signatures that define action in zebrafish larvae. Particular attention will be given to the dynamics of activation and migration of immune cells and their relationship with the manifestation of tissue damage.

Exposure to COX-inhibitors will be carried out using healthy fish as well as fish undergoing inflammatory responses. The latter will be triggered by pre-treatment with lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria. The comparison of the drug-induced responses in healthy versus "inflamed" fish will help to elucidate the role played by the physiological state of the organism in determining effect type and magnitude. The effects on immune and gastro-intestinal systems will be quantified using a diverse set of imaging, flow cytometry, and molecular techniques. Zebrafish is an excellent model for inflammation biology as many aspects of its biology closely resemble the human system. Due to the high relevance of the modulation of COX-mediated pathways for both human, animal and environmental health, the use of zebrafish will also maximise the translational values of the data generated in this project across fields. This high translational potential is fully in line with the rapidly emerging "One Health" vision, which recognizes the inextricable link between human and environmental health.

Project background

Non-steroidal anti-inflammatory drugs (NSAIDs) are used by millions of people worldwide every day to treat a wide variety of conditions that involve pain, fever and inflammation. These compounds act by inhibiting one or both isoforms of the enzyme cyclo-oxygenase (COX1, COX2), which catalyse the synthesis of prostanoids. In healthy humans, low levels of prostanoids play important homeostatic functions; however, their biosynthesis increases dramatically during inflammation, leading, among other things, to pain and poor thermoregulation. The inhibition of prostanoids biosynthesis via COX inhibitors is therefore a highly effective therapeutic strategy in pain and fever management. However, long-term therapeutic use of NSAIDs can adversely affect the gastro-intestinal tract (e.g. dyspepsia, gastric ulcer, bleeding), but also kidney, liver and cardiovascular system. Significant efforts have been allocated to understand the mechanisms of toxicity of NSAIDs and to mitigate these risks. For example, many NSAIDs modulate both COX1 and COX2. It has been hypothesised that whereas the inhibition of COX2 in the gastrointestinal tract is beneficial, the inhibition of COX1 contributes significantly to the drug-induced toxicity. This mechanistic perspective represented the rationale for the development of selective-COX2 inhibitors that minimise the risk of gastro-intestinal toxicity. Despite the great advancements achieved in the understanding of NSAIDs pharmacology and toxicology, many aspects of the mechanisms of action of COX inhibitors and of their biological significance still remain to be elucidated.

The importance of understanding these mechanisms is not only limited to human health, but it has also critical importance for environmental health and for the protection of animal health.