Identification of Andrographolide as an Agonist of Bile Acid TGR5 Receptor in a Cell Line to Demonstrate the Reduction in Hyperglycemia in Type-1 Diabetic Rats

Andrographolide (ADG) is contained in bitter plants, and its effects are widely thought to be associated with taste receptors. The current study used animal studies and cell lines to investigate the role of ADG in diabetic models. The Takeda G-protein-coupled receptor (TGR5) was directly influenced by ADG, and this boosted GLP-1 synthesis in CHO-K1 cells transfected with the TGR5 gene. However, this was not seen in TGR5-mutant cells. The human intestinal L-cell line NCI-H716 showed an increase in GLP-1 production in response to ADG. In NCI-H716 cells, the TGR5 inhibitor triamterene reduced the effects of ADG, including the rise in TGR5 mRNA levels that ADG caused. Additionally, as with the antihyperglycemic impact in type-1 diabetic rats, the increase in plasma-active GLP-1 level caused by ADG was enhanced by a DPP-4 inhibitor. The recovery of the hypoglycemic effect in diabetic rats and the increase in plasma GLP-1 caused by ADG were both suppressed by TGR5 blockers. As a result, after activating TGR5, ADG may boost GLP-1 synthesis in diabetic rats, enhancing glucose homeostasis. In Min-6 cells, a pancreatic cell line grown in culture, ADG-induced insulin secretion was also examined. Blocking GLP-1 receptors had little impact, suggesting that ADG directly affects TGR5 activity in Min-6 cells. A TGR5 mRNA level experiment in Min-6 cells further confirmed that TGR5 is activated by ADG. The current study revealed a novel finding suggesting that ADG may activate TGR5 in diabetic rats in a way that results in enhanced insulin and GLP-1 production, which may be helpful for future research and therapies.

Comparative Study of Two Common In Vitro Models for the Pancreatic Islet with MIN6

BACKGROUND

Islet transplantation is currently considered the most promising method for treating insulin-dependent diabetes. The two most-studied artificial islets are alginate-encapsulated β cells or β cell spheroids. As three-dimensional (3D) models, both artificial islets have better insulin secretory functions and transplantation efficiencies than cells in two-dimensional (2D) monolayer culture. However, the effects of these two methods have not been compared yet. Therefore, in this study, cells from the mouse islet β cell line Min6 were constructed as scaffold-free spheroids or alginate-encapsulated dispersed cells.

METHODS

MIN6 cell spheroids were prepared by using Agarose-base microwell arrays. The insulin secretion level was determined by mouse insulin ELISA kit, and the gene and protein expression status of the MIN6 were performed by Quantitative polymerase chain reaction and immunoblot, respectively.

RESULTS

Both 3D cultures effectively promoted the proliferation and glucose-stimulated insulin release (GSIS) of MIN6 cells compared to 2D adherent cells. Furthermore, 1% alginate-encapsulated MIN6 cells demonstrated more significant effects than the spheroids. In general, three pancreatic genes were expressed at higher levels in response to the 3D culture than to the 2D culture, and pancreatic/duodenal homeobox-1 (PDX1) expression was higher in the cells encapsulated in 1% alginate than that in the spheroids. A western blot analysis showed that 1% alginate-encapsulated MIN6 cells activated the phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (AKT)/forkhead transcription factor FKHR (FoxO1) pathway more than the spheroids, 0.5% alginate-, or 2% alginate-encapsulated cells did. The 3D MIN6 culture, therefore, showed improved effects compared to the 2D culture, and the 1% alginate-encapsulated MIN6 cells exhibited better effects than the spheroids. The upregulation of PDX1 expression through the activation of the PI3K/AKT/FoxO1 pathway may mediate the improved cell proliferation and GSIS in 1% alginate-encapsulated MIN6 cells.

CONCLUSION

This study may contribute to the construction of in vitro culture systems for pancreatic islets to meet clinical requirements.

Ginseng Pectin WGPA Alleviates Exercise-Induced Fatigue by Enhancing Gluconeogenesis

With the development of medicine and sport science, growing attention has been paid to the recovery of exercise-induced fatigue. Ginseng pectin has been shown to be important for a variety of biological functions. Although many studies suggest that ginseng pectin plays an important role in the alleviation of exercise-induced fatigue, the underlying mechanism still remains unclear. In this study, C57BL/6J mice were subjected to a wheel apparatus for exhaustive exercise and fed with ginseng pectin WGPA (acidic fraction of water-soluble ginseng polysaccharides) afterwards. Subsequently, a series of physiological and biochemical indexes, such as blood lactic acid, blood glucose, muscle glycogen, insulin, and glucagon, is evaluated. Meanwhile, enzymatic activity and mRNA level of key enzymes involved in hepatic gluconeogenesis are analyzed. Our results demonstrate that the treatment of ginseng pectin WGPA can result in enhanced gluconeogenesis and decreased insulin and in turn facilitate the recovery of exercise-induced fatigue. In response to WGPA treatment, both phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6 phosphatase (G6Pase) activity were upregulated, indicating that these two enzymes play a critical role in WGPA-induced upregulation in gluconeogenesis. Moreover, mRNA level of G6Pase, but not PEPCK, was increased upon WGPA treatment, suggesting that G6Pase expression is regulated by WGPA. Importantly, the presence of WGPA downregulated insulin both in vivo and in vitro, suggesting the upregulation in gluconeogenesis may be due to alterations in insulin. Together, we provide evidence that ginseng pectin WGPA is able to alleviate exercise-induced fatigue by reducing insulin and enhancing gluconeogenesis.

Impact of ductal interventions on diabetes in patients with chronic pancreatitis

BACKGROUND AND AIM

Even though ductal interventions in chronic pancreatitis (CP) are known to improve pain, its impact on diabetes is unclear. In this cohort study, we evaluated the impact of ductal interventions on diabetes in these patients.

METHODS

Consecutive patients with CP visiting the pancreas clinic between August 1, 2011, and July 21, 2012, were enrolled and followed until December 2018. Detailed clinical, laboratory, imaging, and treatment data were recorded at enrolment and follow-up. Patients were followed up every 6 months through hospital visit and/or telephonic interview. Risk factors for diabetes were evaluated using logistic regression. The impact of ductal interventions on diabetes was evaluated using Kaplan-Meier survival analyses and Cox proportional hazards.

RESULTS

A total of 644 patients were enrolled of which 137 were excluded. Of these, 326 (64.3%) patients had idiopathic CP, and 283 (55.8%) patients underwent ductal intervention. The cumulative incidence of diabetes was 57.9%. Median duration between symptom onset and ductal intervention was similar irrespective of diabetes (2.6 [0.6-6.0] vs 3.0 [1.0-5.5] years; P = 0.69). Alcohol intake and pancreatic ductal calculi were independent risk factors for diabetes (odds ratio [95% confidence interval] of 2.05 (1.18-3.55), P = 0.01, and 2.05 (1.28-3.28), P = 0.003, respectively). Kaplan-Meier analyses revealed that diabetes free interval was significantly longer in patients undergoing ductal interventions, predominantly in those with idiopathic CP with obstructive ductal calculi (hazard ratio [95% confidence interval] 0.39 [0.28-0.55]; P < 0.0001). There were no differences in glycemic status in patients with non-idiopathic CP and those with pre-existing diabetes.

CONCLUSION

Early ductal intervention could delay development of diabetes in patients with idiopathic CP with obstructive ductal calculi.

Risk factors for development of endocrine insufficiency in chronic pancreatitis

Endocrine insufficiency is a common and frequent complication of chronic pancreatitis. Identifying the role of pancreatic damage in the development of diabetes is important for early identification and appropriate management.

METHODS

All consecutive CP patients between January 2019 and May 2020 were retrospectively studied. Relevant statistical tests were performed. A two sided p value < 0.05 was considered statistically significant.

RESULTS

Total 587 chronic pancreatitis patients were included of which 118 (20.1%) patients developed diabetes with duration of 12 (IQR 4-48) months. Older age (OR 1.079; 95% CI 1.045-1.113; p < 0.001), presence of pancreatic parenchymal (OR 2.284; 95% CI 1.036-5.038; p = 0.041) and ductal (OR 2.351; 95% CI 1.062-5.207; p = 0.035) calcifications, exocrine insufficiency (OR 6.287; 95% CI 2.258-17.504; p < 0.001), and pancreatic duct stricture (OR 3.358; 95% CI 1.138-9.912; p = 0.028) were independently associated with development of diabetes mellitus in chronic pancreatitis patients. On cox-regression analysis, smoking (HR 2.370; 95% CI 1.290-4.354; p = 0.005) and pancreatic ductal calcification (HR 2.033; 95% CI 1.286-3.212; p = 0.002) were independently associated with earlier onset of diabetes mellitus in patients with chronic pancreatitis.

CONCLUSION

Pancreatic calcification, pancreatic duct stricture and pancreatic exocrine insufficiency are associated with development of diabetes mellitus in chronic pancreatitis indicating disease progression. Smoking is the modifiable risk factors associated with early onset of diabetes mellitus in CP patients.