Oral indomethacin modifies small intestine biofilms and host-microbe interaction mediators

Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause small intestinal injury and dysbiosis. Although NSAID-induced dysbiosis is well-characterized and contributes to enteropathy, the changes in host-bacterial interactions during enteropathy remain largely unexplored. Here we assessed the expression pattern of six toll-like receptors (TLRs) and three antimicrobial peptides (AMPs) over the course of indomethacin (IND)-induced enteropathy in rats, and evaluated their correlations with inflammation and dysbiosis. In addition, we assessed for the first time the effect of IND on small intestinal mucosal biofilm structure.

Mucosal injury, inflammation and expression of TLR and AMP genes were evaluated at five time points following IND administration. Gut microbiota composition was determined by 16S rRNA gene sequencing. Small intestinal mucosal biofilms were visualized using fluorescent in situ hybridisation.

We found that TLR1, TLR2 and cathelicidin were upregulated, TLR5 was downregulated, whereas TLR6 and TLR9 were not altered in enteropathy. TLR4 expression showed only subtle differences, but correlated with α-defensin 5 and β-defensin 2 levels. We found several correlations between TLRs, AMPs, inflammation and gut bacteria in severe enteropathy, but in early disease stage TLR1, TLR2, TLR5 and cathelicidin expression were more strongly associated with inflammation, whereas TLR4 and defensins were more dependent on gut dysbiosis. IND treatment also caused mild damage to the mucosal microbiota biofilm.

This is the first comprehensive characterization of the time-dependent changes in TLRs, AMPs and mucosal biofilm in NSAID-treated rats, which may help to identify new strategies for the treatment of enteropathy.