GLPG-0974

Constipation is a common functional gastrointestinal disorder, which needs more effective treatment approaches. Houpo Paiqi Mixture (HPPQM) is a type of Chinese patent medicine developed from a classical formula that has been widely applied to the treatment of intestinal motility disorder. Here we aim to assess the effectiveness of HPPQM in the treatment of constipation in rat models and its potential mechanism.

UPLC-MS/MS was performed to investigate the chemical component of HPPQM. Rats were randomly divided into normal control, constipation model (CM), HPPQM (low, middle and high dose) and mosapride groups. Loperamide 8 mg/kg was given orally to induce CM. The small intestine motility, colonic contraction, rectum propulsion, and histological feature of the colon were significantly improved in HPPQM group, compared with CM group (P < 0.05). Results of 16S rRNA sequencing revealed that HPPQM treatment strikingly restructured intestinal microbiota in constipated rats by increasing the relative abundances of Bacteroides and Akkermansia and decreasing the relative abundances of Prevotella and Lactobacillus. The levels of GPR43, 5-HT, 5-HT4R, cAMP, PKA were decreased while SERT was increased in constipated rats (P < 0.05), which could be restored to normal levels by treatment with HPPQM (P < 0.05). Differences in amplitude between experimental CLSMs (with HPPQM added) and control CLSMs were discovered, starting at the concentration of 40 nL/mL (P < 0.05). It was found that GLPG0974 and GR113808 could significantly reduce this reactivity (P < 0.05).

HPPQM manifested a curative effect in constipated rats by promoting intestinal motility. The underlying mechanisms might be related to modulating gut microbiota and activating 5-HT-cAMP-PKA signal pathway.

The G protein-coupled receptors, GPR43 (free fatty acid receptor 2, FFA2) and GPR41 (free fatty acid receptor 3, FFA3), are activated by short-chain fatty acids produced under various conditions, including microbial fermentation of carbohydrates. Previous studies have implicated this receptor energy homeostasis and immune responses as well as in cell growth arrest and apoptosis. Here, we observed the expression of both receptors in human blood cells and a remarkable enhancement in leukemia cell lines (HL-60, U937, and THP-1 cells) during differentiation. A reporter assay revealed that GPR43 is coupled with Gα_i and Gα_12/13 and is constitutively active without any stimuli. Specific blockers of GPR43, GLPG0974 and CATPB function as inverse agonists because treatment with these compounds significantly reduces constitutive activity. In HL-60 cells, enhanced expression of GPR43 led to growth arrest through Gα_12/13 . In addition, the blockage of GPR43 activity in these cells significantly impaired their adherent properties due to the reduction of adhesion molecules. We further revealed that enhanced GPR43 activity induces F-actin formation. However, the activity of GPR43 did not contribute to butyrate-induced apoptosis in differentiated HL-60 cells because of the ineffectiveness of the inverse agonist on cell death. Collectively, these results suggest that GPR43, which possesses constitutive activity, is crucial for growth arrest, followed by the proper differentiation of leukocytes.