(359b) Graduate Student Award Session: Synthetic Adhesins for Improved Probiotic Performance and Colonization

Probiotics and live therapeutic bacteria (LTB) hold promise to treat a number of chronic conditions by interacting with the immune system, secreting biologics, and modulating the microbiome. However, a primary challenge with the delivery of LTBs is their failure to persist in the gastrointestinal (GI) tract for a reliable period of time. Many pathogenic and commensal bacteria overcome this challenge by adhering to the GI lumen using surface proteins called adhesins, preventing their clearance by peristalsis and enabling the bacteria to establish a colonization niche in the GI tract. In this work, we establish a modular platform that conjugates synthetic adhesins (SA) to the LTB surface, mimicking the binding properties of natural adhesins. Specifically, we demonstrate that both gram-positive and gram-negative LTB surfaces can be modified with biotin without affecting LTB growth or viability. This modification significantly improves bacterial attachment to streptavidin-coated surfaces (p < 0.001) and acts as a building block for further modification of the LTB surface with streptavidin-conjugated SA’s directed against biological targets. We examined LTB attachment in both in vitro and in vivo models using SA’s in the form of antibodies against cellular (ICAM) and mucosal (MUC2) targets. Bacterial attachment to Caco-2 cells, a model intestinal enterocyte cell line, increased 3-fold over an unmodified control (p < 0.001) with ICAM SA’s. Prophylactic treatment of mammalian cells with our SA-LTB significantly reduced subsequent attachment of a model pathogen to the cell monolayer (p < 0.001). By targeting intestinal MUC2, a key mediator of bacterial-host interactions and a common bacterial adhesin target, we demonstrate improved short-term colonization and pharmacokinetics of the LTB. SA-LTB treated mice were colonized 2 days earlier than control animals (p < 0.05), with improvements in the maximum LTB concentration and total therapeutic exposure (p < 0.05). As such, the SA platform mimics natural adhesins’ ability to establish a colonization niche in the GI tract, enabling the LTB to persist and proliferate. This platform represents a rapid method for modifying any bacterial surface, while the amine-based chemistry can be used with a wide range of targeting ligands as SA’s. Overall, bio-inspired SA’s enable control over bacterial adhesion, improving both in vivo colonization and therapeutic potential.