PhD Scientific Days 2023

Pharmaceutical Sciences - Posters E

Altered Intestinal Expression of Pattern Recognition Receptors and Distinct Antimicrobial Peptides in Non-Steroidal Anti-Inflammatory Drug-Induced Enteropathy

Text of the abstract

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause significant damage to the distal parts of the small intestine. This enteropathy is characterized by changes in the intestinal microbiota, which contributes to the development of tissue inflammation, but little is known about the mechanisms underlying NSAID-induced dysbiosis. Toll-like receptors (TLRs) are important part of the innate immunity and their activation by potentially pathogenic bacteria triggers a defensive immune response. A part of it is the stimulation of the production of antimicrobial peptides (AMPs), such as defensins and cathelicidin antimicrobial peptide (CAMP). Although interactions between TLRs, AMPs and gut microbiota are intensively studied in the context of inflammatory bowel diseases, they are poorly understood in NSAID enteropathy. In fact, there is only limited data on the effect of NSAIDs on intestinal expression of TLRs and AMPs.
Aim: Analyzing the changes in PRR and AMP expressions in NSAID-treated rats.
Methods: In the first experiment, male Wistar rats were treated once with a single large dose of 20 mg/kg indomethacin by gavage and were euthanized 6, 12, 24, 48 and 72 h later. A sixth group was treated with vehicle (1% hydroxyethylcellulose) and euthanized at 72 h. In the second experiment, rats were treated chronically (twice daily for two weeks) with indomethacin (2 or 4 mg/kg), naproxen (10 or 20 mg/kg)or vehicle. Intestinal injury was assessed macroscopically and by measuring the tissue level of inflammatory proteins. The mRNA levels of CAMP, alpha-defensin 5, β-defensin 2 and TLR-1, -2, -4, -6 and -9 were assessed by qPCR.
Results: A single high dose of indomethacin caused severe enteropathy within 3 days, characterized by weight loss, intestinal ulcers, and shortening of the small intestine. Mucosal inflammation was confirmed by elevated tissue levels of myeloperoxidase, cyclooxygenase-2 and pentraxin 3. Inflammation was accompanied by increased mRNA level of TLR-1, -2 and CAMP, and also that of alpha-defensin 5 tended to rise, whereas the expressions of TLR-4, -6, -9 and β-defensin 2 did not change significantly. Chronic treatment with NSAIDs yielded similar results. Indomethacin treatment increased the jejunal expression of TLR-1 and -2, and both drugs increased the level of CAMP and alpha-defensin 5. However, chronic treatment with naproxen also resulted in higher levels of TLR-4 and β-defensin 2. Conclusion: Here we characterize for the first time the time-dependent alterations of TLRs and AMPs in NSAID enteropathy. Whether these changes contribute to NSAID-induced intestinal dysbiosis is currently under investigation.
Funding: NKFI FK 138842.