Design of Gut-Restricted Thiazolidine Agonists of G Protein-Coupled Bile Acid Receptor 1 (GPBAR1, TGR5)

Abstract

Bile acid signaling and metabolism in the gastrointestinal tract have wide-ranging influences on systemic disease. G protein-coupled bile acid receptor 1 (GPBAR1, TGR5) is one of the major effectors in bile acid sensing, with demonstrated influence on metabolic, inflammatory, and proliferative processes. The pharmacologic utility of TGR5 agonists has been limited by systemic target-related effects such as excessive gallbladder filling and blockade of gallbladder emptying. Gut-restricted TGR5 agonists, however, have the potential to avoid these side effects and consequently be developed into drugs with acceptable safety profiles. We describe the discovery and optimization of a series of gut-restricted TGR5 agonists that elicit a potent response in mice, with minimal gallbladder-related effects. The series includes 12 (TGR5 EC: human, 143 nM; mouse, 1.2 nM), a compound with minimal systemic availability that may have therapeutic value to patients with type 2 diabetes mellitus, nonalcoholic steatohepatitis, or inflammatory bowel disease.

Intestinal TGR5 agonism improves hepatic steatosis and insulin sensitivity in Western diet-fed mice

“…Takeda G protein-coupled receptor 5 (TGR5) agonist activities of RDX8940 and the known TGR5 agonists INT-777 and GPBAR-A were assessed in human embryonic kidney (HEK) 293 cells (American Type Culture Collection, Manassas, VA) stably transfected to heterologously express human or mouse TGR5, as described previously (9).…”

“…Solubility of RDX8940 was assessed in fed-state simulated intestinal fluid (FeSSIF) and a potassium phosphate buffer pH 2.5 (150 mM ionic strength), as described previously (9).…”

“…Permeability of RDX8940 was estimated using human colorectal adenocarcinoma (Caco-2) and Madin-Darby canine kidney (MDCK) bidirectional permeability assays. Caco-2 cells and MDCK cells were cultured into monolayers on 96-well Millicell 0.4-µm polycarbonate membrane inserts (EMD Millipore, Billerica, MA) for 21–25 days, and on HTS Transwell 24-well 0.4-µm polyester membrane inserts (Corning, NY) for 48 h, respectively, before each assay was carried out, as described previously, with the following modifications (9). RDX8940 (10 μM in transport buffer with a final DMSO concentration of 1% or 0.1% for Caco-2 or MDCK, respectively) was added to the donor side of the inserts [on either the apical (A) or basolateral (B) side of the cells] in duplicate, and transport buffer was added to the receiver side.…”

“…The proximal and distal small intestine, cecum, and small and distal colon were collected from each animal into five separate tubes and frozen immediately until the day of analysis. RDX8940 was quantified in mouse plasma and tissue samples using HPLC-MS/MS, as described previously with the following modifications (9). Working solutions of standards were diluted 1:10 in pooled C57BL/6 mouse K 3 -EDTA plasma (Bioreclamation IVT, Liverpool, NY) or blank homogenized tissue matrix, which was prepared by homogenizing tissue from treatment-naïve animals (pooled C57BL/6 mouse small intestine, cecum, and colon) in 1:1 acetonitrile:water with stainless-steel balls for 5 min at room temperature.…”

Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1

“…Accumulated evidence, indicate how bile acids are important modulators of the whole body metabolism, bridging the microbiome to the brain, likely being key signaling molecules in the pathogenesis of obesity and type 2 diabetes. Indeed remittance from diabetes experienced by RYGB or SG patients, has been attributed to the elevation of circulating bile acids ( 37 , 38 , 357 ), warranting further investigation, especially the development of gut-restricted TGR5 agonists ( 358 ).…”