PhD Scientific Days 2024

Poster Session R - Pharmaceutical Sciences and Health Technologies 2.

Altered Expression of Toll-like Receptor 1 and -2 is Associated with Intestinal Dysbiosis in NSAID-Induced Enteropathy.

Text of the abstract

Introduction: It has been known for decades that non-steroidal anti-inflammatory drugs (NSAIDs) can cause small intestinal injury (enteropathy) and gut dysbiosis, yet the underlying mechanisms are not fully understood. Toll-like receptors (TLRs) are crucial regulators of host-microbiota interactions and gut homeostasis, and altered TLR signaling is implicated in several disorders including inflammatory bowel disease (IBD). There is some evidence that TLR2 and TLR4 expressions are changed in NSAID enteropathy, but the available data are scarce and inconclusive. In addition, whether changes in TLRs correlate with NSAID-induced dysbiosis remains to be established.
Aim: We aimed to assess the small intestinal expression of five TLRs (TLR1, -2, -4, -6 and -9) in acute and chronic NSAID enteropathy in rats, and the associations between TLRs and gut bacteria.
Method: Wistar rats received a single high dose of indomethacin (IND, 20 mg/kg), and were euthanized after 6, 12, 24, 48, or 72 h. Control animals received drug solvent (1% hydroxyethyl cellulose). In a second study, rats were treated with lower doses of IND (2 and 4 mg/kg) or its vehicle twice a day for 14 days. Small intestinal levels of inflammatory proteins and TLRs were assessed by qPCR and Western blot, whereas the composition of small intestinal microbiota by 16S rRNA sequencing. Associations between TLRs and bacterial abundances were tested by calculating Spearman’s rank correlation coefficients.
Result: Acute enteropathy induced by high-dose IND was associated with severe tissue inflammation and intestinal dysbiosis. Small intestinal expression of both TLR1 and TLR2 increased in a time-dependent manner, whereas TLR4, -6 and -9 levels remained unaltered. Similarly, chronic treatment with lower doses of IND induced enteropathy and elevation of TLR1 and TLR2 in a dose-dependent fashion. The abundance of several bacteria showed either positive or negative correlation with the expressions of TLR1 and TLR2. In contrast, we found only weak associations between bacteria and TLR4, -6, and -9.
Conclusion: Upregulation of both TLR1 and TLR2 suggests the involvement of the TLR2/TLR1 complex in NSAID-induced acute and chronic enteropathy. In addition, altered TLR signaling is likely to be associated with NSAID-induced dysbiosis. TLR4, -6 and -9 likely have a minor role in NSAID enteropathy.
Funding: NKFI FK 138842