Evaluation of novel TGR5 agonist in combination with Sitagliptin for possible treatment of type 2 diabetes

Mechanism of action of the bile acid receptor TGR5 in obesity

G protein-coupled receptors (GPCRs) are a large family of membrane protein receptors, and Takeda G protein-coupled receptor 5 (TGR5) is a member of this family. As a membrane receptor, TGR5 is widely distributed in different parts of the human body and plays a vital role in regulating metabolism, including the processes of energy consumption, weight loss and blood glucose homeostasis. Recent studies have shown that TGR5 plays an important role in glucose and lipid metabolism disorders such as fatty liver, obesity and diabetes. With the global obesity situation becoming more and more serious, a comprehensive explanation of the mechanism of TGR5 and filling the gaps in knowledge concerning clinical ligand drugs are urgently needed. In this review, we mainly explain the anti-obesity mechanism of TGR5 to promote the further study of this target, and show the electron microscope structure of TGR5 and review recent studies on TGR5 ligands to illustrate the specific binding between TGR5 receptor binding sites and ligands, which can effectively provide new ideas for ligand research and promote drug research.

Single shot interscalene regional anesthesia provides noninferior analgesia and decreased complications compared with an indwelling catheter for arthroscopic and reconstructive shoulder surgery

BACKGROUND

There is an abundance of literature comparing the efficacy, safety, and complication rates of regional anesthesia in shoulder surgery. The purpose of this study was to compare analgesia efficacy, and complication rates between single shot and continuous catheters in patients undergoing arthroscopic or reconstructive shoulder surgery in a large cohort.

METHODS

Consecutive patients (n = 1888) who underwent shoulder arthroplasty or arthroscopic shoulder surgery and had regional anesthesia were included. Patients had either a single-shot interscalene block (SSIB) or an SSIB with a continuous interscalene nerve block with a catheter (CIB). The decision for SSIB or CIB was selected based on patient risk factors and surgeon preference. Patients received phone calls on postoperative days 1, 2, 7, and 14 to assess for pain levels (numeric rating scale [NRS]) and complications.

RESULTS

One hundred sixty patients received SSIB, and 1728 patients received CIB. The postoperative NRS scores at day 1 were also similar. There were 3 complications (2%) in the SSIB group and 172 complications (10%) in the CIB group. Ten patients in the CIB group required emergency department (ED) visits secondary to block complications compared with no ED visits in the SSIB group.

CONCLUSION

In 1888 consecutive patients, SSIB and CIB provided similar pain relief following shoulder surgery. However, patients who received CIB had significantly more complications and ED visits than patients who received SSIB. The potential benefits of longer pain relief may not outweigh the risks of CIB vs. SSIB in common shoulder procedures.

Emerging Applications of Metabolomics to Assess the Efficacy of Traditional Chinese Medicines for Treating Type 2 Diabetes Mellitus

Diabetes is a common and complex disease that can exacerbate the complications related to cardiovascular disease, and this is especially true for type 2 diabetes mellitus (T2DM). In addition to the standard pharmacological therapies, T2DM has also been treated with nonconventional regimens such as traditional Chinese medicine (TCM), e.g., herbal medicines and TCM prescriptions, although the mechanisms underlying the therapeutic benefits remain unclear. In this regard, many studies have used metabolomics technology to elucidate the basis for the efficacy of TCM for T2DM. Metabolomics has recently attracted much attention with regard to drug discovery and pharmacologically relevant natural products. In this review, we summarize the application of metabolomics to the assessment of TCM efficacy for treating T2DM. Increasing evidence suggests that the metabolic profile of an individual patient may reflect a specific type of T2DM syndrome, which may provide a new perspective for disease diagnosis. In addition, TCM has proved effective for countering the metabolic disorders related to T2DM, and this may constitute the basis for TCM efficacy. Therefore, further determining how TCM contributes to the reversal of metabolic disorders, such as using network pharmacology or by assessing the contribution of host–gut microbiota interactions, will also provide researchers with new potential targets for pharmacologic-based therapies.

Identification of degradation impurity of TGR5 receptor agonist-ZY12201 by LC-MS technique during force degradation study

Forced degradation study is a systemic characterization of degradation products of active pharmaceutical ingredient (API) at conditions which posses more harsh environment that accelerates degradation of API. Forced degradation and stability studies would be useful in selection of proper, packaging material and storage conditions of the API. These are also useful to demonstrate degradation pathways and degradation products of the API and further characterisation of the degradation products using mass spectrometry. TGR5 is a G protein-coupled receptor, activation of which promotes secretion of glucagon-like peptide-1 (GLP-1) and modulates insulin secretion. The potent and orally bioavailable TGR5 agonist, ZY12201, shows activation of TGR5 which increase secretion of GLP-1 and help in lowering blood glucose level in animal models. Hence it is necessary to establish and study degradation pathway and stability of API for better handling and regulatory approval. Force degradation studies of ZY12201 have shown presence of one oxidative impurity during oxidative degradation in HPLC analysis. The oxidized product is further characterized by LC-MS to elucidate structure of impurity and characterize its degradation pathway.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42452-021-04660-y.

Design, synthesis and evaluation of 1-benzyl-1H-imidazole-5-carboxamide derivatives as potent TGR5 agonists

TGR5 is emerging as an important and promising target for the treatment of diabetes, obesity and other metabolic syndromes. A series of novel 1-benzyl-1H-imidazole-5-carboxamide derivatives was designed, synthesized and evaluated in vitro and in vivo. The most potent compounds 19d and 19e exhibited excellent agonistic activities against hTGR5, which was superior to those of the reference drugs INT-777 and LCA. In addition, compounds 19d and 19e exhibited good selectivity against FXR and presented significant glucose-lowering effects in vivo. Compound 19d could stimulate GLP-1 secretion by activating of TGR5.

Anticipatory guidance and systematic review of prescribing combination incretin therapy in the treatment of type 2 diabetes

WHAT IS KNOWN AND OBJECTIVE

Few studies have evaluated the efficacy and safety of combining a glucagon-like peptide-1 receptor agonist and dipeptidyl peptidase-4 inhibitor in patients with type 2 diabetes mellitus. Clinicians may frequently encounter this drug therapy combination in practice and should be aware of clinical evidence and risks associated with its use.

METHODS

A literature search was conducted in Embase (1947-April 20, 2020), Medline - Ovid (1946-April 21, 2020), Medline - PubMed (1946-April 21, 2020), Cochrane Library CENTRAL Register of Controlled Trials (1991-April 20, 2020) and Web of Science (1900-April 17, 2020). Databases were searched using keywords and subject headings to identify studies assessing efficacy and safety of combination incretin therapy. The search identified 1255 studies. Of these, 383 were excluded for duplicate citations. Articles were then excluded based on title and abstract screen.

RESULTS AND DISCUSSION

Six studies were included. A small reduction in haemoglobin A1c and weight loss was found by combining incretin therapy. Adverse effects such as hypoglycaemia, gastrointestinal upset and pancreatitis were infrequent.

WHAT IS NEW AND CONCLUSION

On current evidence, the small benefit in glycaemic control that may be realized by using combination incretin therapy is unlikely to be offset by the potential increased risk of pancreatitis or additional cost. Additional long-term prospectively designed studies are needed to better understand the efficacy and safety of combination incretin therapy.

Design of G-protein-coupled bile acid receptor 1 (GPBAR1, TGR5) soft drugs with reduced gallbladder-filling effects

The G-protein-coupled bile acid receptor TGR5 agonists were widely developed in type 2 diabetes and gastrointestinal disorders, but were also full of challenges, due to the systemic on-targeted side effects, especially the gallbladder-filling effects. Here, to circumvent these risks, several TGR5 agonists with soft-drug designation had been designed and synthesized with the properties of rapid metabolized after drug effect. Among them, compound 19 showed negligible systemic exposure and favorable gallbladder safety on a 3-day continuous administration, providing a novel strategy for developing TGR5 agonists.

TGR5 agonist ameliorates insulin resistance in the skeletal muscles and improves glucose homeostasis in diabetic mice

BACKGROUND AND PURPOSE

TGR5 plays an important role in many physiological processes. However, the functions of TGR5 in the regulation of the glucose metabolism and insulin sensitivity in the skeletal muscles have not been fully elucidated. We synthesized MN6 as a potent and selective TGR5 agonist. Here, the effect of MN6 on insulin resistance in skeletal muscles was evaluated in diet-induced obese (DIO) mice and C2C12 myotubes, and the underlying mechanisms were explored.

METHODS

The activation of MN6 on human and mouse TGR5 was evaluated by a cAMP assay in HEK293 cell lines stable expressing hTGR5/CRE or mTGR5/CRE cells. GLP-1 secretion was measured in NCI-H716 cells and CD1 mice. The acute and chronic effects of MN6 on regulating metabolic abnormalities were observed in ob/ob and DIO mice. 2-deoxyglucose uptake was examined in isolated skeletal muscles. Akt phosphorylation, glucose uptake and glycogen synthesis were examined to assess the effects of MN6 on palmitate-induced insulin resistance in C2C12 myotubes.

RESULTS

MN6 potently activated human and mouse TGR5 with EC₅₀ values of 15.9 and 17.9 nmol/L, respectively, and stimulated GLP-1 secretion in NCI-H716 cells and CD1 mice. A single oral dose of MN6 significantly decreased the blood glucose levels in ob/ob mice. Treatment with MN6 for 15 days reduced the fasting blood glucose and HbA1c levels in ob/ob mice. MN6 improved glucose and insulin tolerance and enhanced the insulin-stimulated glucose uptake of skeletal muscles in DIO mice. The palmitate-induced impairment of insulin-stimulated Akt phosphorylation, glucose uptake and glycogen synthesis in C2C12 myotubes could be prevented by MN6. The effect of MN6 on palmitate-impaired insulin-stimulated Akt phosphorylation was abolished by siRNA-mediated knockdown of TGR5 or by the inhibition of adenylate cyclase or protein kinase A, suggesting that this effect is dependent on the activation of TGR5 and the cAMP/PKA pathway.

CONCLUSIONS

Our study identified that a TGR5 agonist could ameliorate insulin resistance by the cAMP/PKA pathway in skeletal muscles; this uncovered a new effect of the TGR5 agonist on regulating the glucose metabolism and insulin sensitivity in skeletal muscles and further strengthened its potential value for the treatment of type 2 diabetes.

Scutellariae Radix and Coptidis Rhizoma Improve Glucose and Lipid Metabolism in T2DM Rats via Regulation of the Metabolic Profiling and MAPK/PI3K/Akt Signaling Pathway

Aim Scutellariae Radix (SR) and Coptidis Rhizoma (CR) have often been combined to cure type 2 diabetes mellitus (T2DM) in the clinical practice for over thousands of years, but their compatibility mechanism is not clear. Mitogen-activated protein kinase (MAPK) signaling pathway has been suggested to play a critical role during the process of inflammation, insulin resistance, and T2DM. This study was designed to investigate their compatibility effects on T2DM rats and explore the underlying mechanisms by analyzing the metabolic profiling and MAPK/PI3K/Akt signaling pathway. Methods The compatibility effects of SR and CR were evaluated with T2DM rats induced by a high-fat diet (HFD) along with a low dose of streptozocin (STZ). Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to discover potential biomarkers. The levels of pro-inflammatory cytokines; biochemical indexes in serum, and the activities of key enzymes related to glycometabolism in liver were assessed by ELISA kits. qPCR was applied to examine mRNA levels of key targets in MAPK and insulin signaling pathways. Protein expressions of p65; p-p65; phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K); phosphorylated-PI3K (p-PI3K); protein kinase B (Akt); phosphorylated Akt (p-Akt) and glucose transporter 2 (Glut2) in liver were investigated by Western blot analysis. Results Remarkably, hyperglycaemia, dyslipidemia, inflammation, and insulin resistance in T2DM were ameliorated after oral administration of SR and CR, particularly their combined extracts. The effects of SR, CR, low dose of combined extracts (LSC) and high dose of combined extracts (HSC) on pro-inflammatory cytokine transcription in T2DM rats showed that the MAPK pathway might account for the phenomenon with down-regulation of MAPK (P38 mitogen-activated protein kinases (P38), extracellular regulated protein kinases (ERK), and c-Jun N-terminal kinase (JNK)) mRNA, and protein reduction in p-P65. While mRNA levels of key targets such as insulin receptor substrate 1 (IRS1), PI3K, Akt2, and Glut2 in the insulin signaling pathway were notably up-modulated, phosphorylations of PI3K, Akt, and expression of Glut2 were markedly enhanced. Moreover, the increased activities of phosphoenolpyruvate carboxykinase (PEPCK), fructose-1,6-bisphosphatase (FBPase), glucose 6-phosphatase (G6Pase), and glycogen phosphorylase (GP) were highly reduced and the decreased activities of glucokinase (GK), phosphofructokinase (PFK), pyruvate kinase (PK), and glycogen synthase (GS) in liver were notably increased after treatment. Further investigation indicated that the metabolic profiles of plasma and urine were clearly improved in T2DM rats. Fourteen potential biomarkers (nine in plasma and five in urine) were identified. After intervention, these biomarkers returned to normal level to some extent. Conclusion The results showed that SR, CR, and combined extract groups were normalized. The effects of combined extracts were more remarkable than single herb treatment. Additionally, this study also showed that the metabonomics method is a promising tool to unravel how traditional Chinese medicines work.