Concomitant suppression of COX-1 and COX-2 is insufficient to induce enteropathy associated with chronic NSAID use.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used medications for the management of chronic pain; however, they are associated with gastrointestinal (GI) adverse events. Although many mechanisms have been suggested, NSAID-induced enteropathy has been thought to be primarily due to inhibition of both cyclooxygenases (COX) -1 and -2, which results in suppression of prostaglandin synthesis. Here we report that concomitant postnatal deletion of and over 10 months failed to cause intestinal injury in mice unless they were treated with naproxen or its structural analog, phenylpropionic acid, which is not a COX inhibitor. double knockout mice exhibit a distinct gut microbiome composition, and cohousing them with controls rescues their dysbiosis and delays the onset of NSAID-induced GI bleeding. Suppression of bile acid synthesis is also protective. In both the UK Biobank and All of Us human cohorts, coadministration of antibiotics with NSAIDs is associated with an increased frequency of GI bleeding. These results show that prostaglandin suppression plays a trivial role in NSAID-induced enteropathy. However, deletion causes dysbiosis of the gut microbiome that amplifies the enteropathic response to NSAIDs.