Intestinal TGR5-targeted carrier-drug conjugate improves glycemic control in mice and pigs

Numerous G protein-coupled receptors (GPCRs) expressed in the gastrointestinal tract serve as crucial transducers to regulate a variety of physiological functions upon activation. Takeda G protein-coupled receptor 5 (TGR5), a prominent gastrointestinal GPCR expressed on enteroendocrine L cells, is activated by intestinal bile acids and plays a role in glucose utilization. However, the development of TGR5 agonists has been hindered by the hepatobiliary toxicity associated with long-term supplementation with exogenous agonists. Here, we designed and characterized a biomimetic receptor agonist, which we termed TGR5-targeted carrier-drug conjugate (TGR5-CaDC), that combined the TGR5-activating capabilities of deoxycholic acid, a TGR5 agonist, with the nonabsorbable properties of a carrier. Unlike traditional agonists or carrier-based drug delivery systems, nonabsorbable TGR5-CaDC remained localized in the intestines of mice and pigs, providing high surface concentrations of TGR5 agonists in addition to ensuring strong L cell specificity and TGR5 affinity. TGR5-CaDC treatment also promoted TGR5 cluster aggregation, signal amplification, and increased glucagon-like peptide 1 secretion. Notably, TGR5-CaDC demonstrated sustained glycemic effects with reduced toxicity compared with deoxycholic acid alone or liraglutide in diabetic mice and Bama minipigs. By targeting extracellular binding domains and mimicking native ligand-receptor binding patterns, the design concept underlying this carrier-drug conjugate has the potential for applications in a variety of GPCR-mediated gastrointestinal diseases.