Engineered Bacteroides thetaiotaomicron sense gut inflammation and deliver therapeutic molecules to alleviate colitis in mice.

Engineered therapeutic microbes for intestinal inflammation must be capable of gut colonization, sensitive detection of disease-associated biomarkers and targeted delivery of therapeutic molecules. Examples of microbes displaying all three characteristics are limited. Here we engineered Bacteroides thetaiotaomicron, a human gut commensal bacterium with colonization ability, colonic tropism and innate anti-inflammatory properties, as a chassis to create programmable bacterial strains termed Btbots. We developed genetic circuits that were integrated into the bacterial chromosome to sense two intestinal inflammation biomarkers, deoxycholic acid (DCA) and nitric oxide (NO), and to enhance surface display and secretion of therapeutic molecules in response. Btbots with these biosensors were developed that either display trefoil factor-3 to facilitate mucosal repair or secrete interleukin-35 to suppress inflammation. These Btbots sensed DCA and NO biomarkers and released therapeutic agents, alleviating colitis and modulating the gut microenvironment and microbiota in mouse models. This work establishes a proof of concept for localized sensing and consequent therapeutic molecule release for gastrointestinal applications, whose clinical potential awaits further investigation.