Glucagon-like peptide-1 and its receptor agonist exendin-4 modulate cholangiocyte adaptive response to cholestasis

Comparative Hepatic Outcomes of SGLT2i or DPP4i Compared to GLP-1RA in CHB and T2DM Patients

BACKGROUND

The prevalence of diabetes is increasing among chronic hepatitis B (CHB) patients. However, the relative efficacy of sodium-glucose cotransporter-2 inhibitors (SGLT2i) or dipeptidyl peptidase-4 inhibitors (DPP4i), compared with glucagon-like peptide-1 receptor agonists (GLP-1RA), among such at-risk populations remains unclear in terms of reducing liver-related events (LRE).

METHODS

Using a nationwide database (2019-2022), we identified CHB patients with diabetes (age ≥ 40) and established two new-user cohorts: SGLT2i vs. GLP-1RA and DPP4i vs. GLP-1RA. LREs included hepatocellular carcinoma, cirrhosis, liver transplantation and liver-related mortality. For appropriate balancing, propensity score matching (PSM) was performed for each cohort. Multivariate Cox regression models were used to estimate LRE risk with adjusted hazard ratios (aHR) and 95% confidence intervals (CI).

RESULTS

Propensity score matching provided two separate cohorts: (1) SGLT2i (n = 2297) vs. GLP-1RA (n = 461) and (2) DPP4i (n = 803) vs. GLP-1RA (n = 165) users. The LREs risk was similar across each comparison, with aHRs of 0.82 (95% CI 0.49-1.37) for GLP-1RA (vs. SGLT2i) and 0.93 (95% CI 0.41-2.07) for GLP-1RA (vs. DPP4i), indicating no significant differences. Subgroup analyses showed a trend favouring GLP-1RA over SGLT2i in females, obese individuals, antiviral therapy (AVT) users, those with diabetes complications, longer diabetes duration and physically active individuals. Compared with DPP4i, the trend was observed in AVT users and those with a shorter diabetes duration, though none were statistically significant.

CONCLUSION

Overall LRE risk was comparable between SGLT2i or DPP4i vs. GLP-1RA users. Further prospective studies are required to identify who can benefit from specific medication.

Incretin-based drugs and the risk of gallbladder or biliary tract diseases among patients with type 2 diabetes across categories of body mass index: a nationwide cohort study

Background

Despite emerging evidence of gallbladder or biliary tract diseases (GBD) risk regarding incretin-based drugs, population-specific safety profile considering obesity is lacking. We aimed to assess whether stratification by body mass index (BMI) modifies the measures of association between incretin-based drugs and the risk of GBD.

Methods

We conducted an active-comparator, new-user cohort study using a nationwide claims data (2013-2022) of Korea. We included type 2 diabetes (T2D) patients stratified by Asian BMI categories: Normal, 18.5 to <23 kg/m2; Overweight, 23 to <25 kg/m2; Obese, ≥25 kg/m2. The primary outcome was a composite of GBD, including cholelithiasis, cholecystitis, obstruction of the gallbladder or bile duct, cholangitis, and cholecystectomy. We used 1:1 propensity score (PS) matching and estimated hazard ratios (HR) with 95% confidence intervals (CI) using Cox models.

Findings

New users of DPP4i and SGLT2i were 1:1 PS matched (n = 251,420 pairs; 186,697 obese, 39,974 overweight, and 24,749 normal weight pairs). The overall HR for the risk of GBD with DPP4i vs. SGLT2i was 1.21 (95% CI 1.14-1.28), with no effect modification by BMI (p-value: 0.83). For the second cohort, new users of GLP1RA and SGLT2i were 1:1 PS matched (n = 45,443 pairs; 28,011 obese, 8948 overweight, and 8484 normal weight pairs). The overall HR for the risk of GBD with GLP1RA vs. SGLT2i was 1.27 (1.07-1.50), with no effect modification by BMI (p-value: 0.73).

Interpretation

The increased risks of GBD were presented in both cohorts with no evidence of effect heterogeneity by BMI.

Funding

Ministry of Food and Drug Safety, Health Fellowship Foundation.

Bile acid metabolism and signalling in liver disease

Bile acids (BAs) serve as signalling molecules, efficiently regulating their own metabolism and transport, as well as key aspects of lipid and glucose homeostasis. BAs shape the gut microbial flora and conversely are metabolised by microbiota. Disruption of BA transport, metabolism and physiological signalling functions contribute to the pathogenesis and progression of a wide range of liver diseases including cholestatic disorders and MASLD (metabolic dysfunction-associated steatotic liver disease), as well as hepatocellular and cholangiocellular carcinoma. Additionally, impaired BA signalling may also affect the intestine and kidney, thereby contributing to failure of gut integrity and driving the progression and complications of portal hypertension, cholemic nephropathy and the development of extrahepatic malignancies such as colorectal cancer. In this review, we will summarise recent advances in the understanding of BA signalling, metabolism and transport, focusing on transcriptional regulation and novel BA-focused therapeutic strategies for cholestatic and metabolic liver diseases.

Association between incretin-based drugs and risk of cholangiocarcinoma among patients with type 2 diabetes: A large population-based matched cohort study

AIM

To examine the association between the use of incretin-based drugs [glucagon-like peptide-1 receptor agonists (GLP-1RAs), dipeptidyl peptidase-4 inhibitors (DPP-4Is)] and the risk of cholangiocarcinoma (CCA) in the United States.

METHODS

This large population-based, retrospective cohort study using the TriNetX datasets included adult patients with type 2 diabetes mellitus (T2DM) who were new users of GLP-1RAs, DPP-4Is, or other second- or third-line antidiabetic drugs between 2010 and 2021. The primary outcome was the incidence of CCA.

RESULTS

A total of 3,816,071 patients were included (mean age, 61.4 years, female, 49.3 %). A 51 % and 23 % risk reduction in CCA after 1 year of exposure to GLP-1RAs (hazard ratio 0.49; 95 % CI 0.40-0.60) and DPP4Is (0.77, 95 % CI 0.67-0.90), respectively compared to new second-or third-line users. Results were consistent at 3, 5, and 7 years of follow-up (0.66, 0.71, and 0.72 for GLP-1RAs and 0.84, 0.87, and 0.85 for DPP-4Is, respectively). Compared to new metformin users, GLP-1RA users were associated with a 42 % lower risk of developing CCA, whereas DPP-4I group was not associated with an increased risk.

CONCLUSIONS

GLP-1RAs and DPP-4Is were not associated with a significantly increased risk of CCA. GLP-1RAs even showed a reduced risk of CCA development. They can be considered as safe and effective treatment options for patients with T2DM at risk of CCA.

Glycemic control and cancer outcomes in oncologic patients with diabetes: an Italian Association of Medical Oncology (AIOM), Italian Association of Medical Diabetologists (AMD), Italian Society of Diabetology (SID), Italian Society of Endocrinology (SIE), Italian Society of Pharmacology (SIF) multidisciplinary critical view

BACKGROUND

 Increasing evidence suggests that diabetes increases the risk of developing different types of cancer. Hyperinsulinemia, hyperglycemia and chronic inflammation, characteristic of diabetes, could represent possible mechanisms involved in cancer development in diabetic patients. At the same time, cancer increases the risk of developing new-onset diabetes, mainly caused by the use of specific anticancer therapies. Of note, diabetes has been associated with a ∼10% increase in mortality for all cancers in comparison with subjects who did not have diabetes. Diabetes is associated with a worse prognosis in patients with cancer, and more recent findings suggest a key role for poor glycemic control in this regard. Nevertheless, the association between glycemic control and cancer outcomes in oncologic patients with diabetes remains unsettled and poorly debated.

PURPOSE

 The current review seeks to summarize the available evidence on the effect of glycemic control on cancer outcomes, as well as on the possibility that timely treatment of hyperglycemia and improved glycemic control in patients with cancer and diabetes may favorably affect cancer outcomes.

A real-world disproportionality analysis of semaglutide: Post-marketing pharmacovigilance data

AIM/INTRODUCTION

The recent adverse reactions associated with semaglutide have led the Food and Drug Administration (FDA) to issue a "black box warning", and it is necessary to analyze all reports of adverse reactions to improve the safety of its clinical use.

MATERIALS AND METHODS

Statistical analyses and signal mining were performed by obtaining the adverse event reports related to semaglutide in the FAERS database from the first quarter of 2018 to the fourth quarter of 2023. We used disproportionality and Bayesian analysis to examine clinical and demographic attributes, trends reported quarterly, and contrasts between two distinct indications (obesity and type 2 diabetes).

RESULTS

We found 10 unexpected adverse signals related to "pancreatic cancer", "intestinal obstruction", "cholecystitis", and "polycystic ovary" and both the two different indications had the same serious adverse reaction events occurring.

CONCLUSIONS

This study identified many unexpected signals of serious adverse reactions, suggesting the importance of continuous post-marketing surveillance of semaglutide to understand its potential risks.

Glucagon-like peptide 1 receptor agonist: A potential game changer for cholangiocarcinoma

Glucagon-like peptide-1 receptor (GLP-1R) agonist, a subgroup of incretin-based anti-diabetic therapies, is an emerging medication with benefits in reducing blood glucose and weight and increasing cardiovascular protection. Contrarily, concerns have been raised about GLP-1R agonists increasing the risk of particular cancers. Recently, several epidemiological studies reported contradictory findings of incretin-based therapy on the risk modification for cholangiocarcinoma (CCA). The first cohort study demonstrated that incretin-based therapy was associated with an increased risk of CCA. Later studies, however, showed a null effect of incretin-based therapy on CCA risk for dipeptidyl peptidase-4 inhibitor nor GLP-1R agonist. Mechanistically, glucagon-like peptide 1 receptor is multifunctional, including promoting cell growth. High GLP-1R expressions were associated with progressive phenotypes of CCA cells in vitro. Unexpectedly, the GLP-1R agonist showed anti-tumor effects on CCA cells in vitro and in vivo with unclear mechanisms. Our recent report also showed that GLP-1R agonists suppressed the expression of GLP-1R in CCA cells in vitro and in vivo, leading to the inhibition of CCA tumor growth. This editorial reviews recent evidence, discusses the potential effects of GLP-1R agonists in CCA patients, and proposes underlying mechanisms that would benefit from further basic and clinical investigation.

Dipeptidyl Peptidase-4 Inhibitors and the Risk of Gallbladder and Bile Duct Disease Among Patients with Type 2 Diabetes: A Population-Based Cohort Study

INTRODUCTION

The use of dipeptidyl peptidase-4 (DPP-4) inhibitors may be associated with an increased risk of gallbladder and bile duct disease among patients with type 2 diabetes.

METHODS

We conducted a population-based cohort study using an active comparator, new-user design. We used data from the United Kingdom Clinical Practice Research Datalink to identify patients newly treated with either a DPP-4 inhibitor or sodium-glucose cotransporter-2 (SGLT-2) inhibitor between January 2013 and December 2020. We fitted Cox proportional hazards models with propensity score fine stratification weighting to estimate the hazard ratio (HR) and its 95% confidence interval (CI) for incident gallbladder and bile duct disease associated with DPP-4 inhibitors compared to SGLT-2 inhibitors.

RESULTS

DPP-4 inhibitors were associated with a 46% increased risk of gallbladder and bile duct disease (4.3 vs. 3.0 events per 1000 person-years, HR 1.46, 95% CI 1.17-1.83). At 6 months and 1 year, 745 and 948 patients, respectively, would need to be treated with DPP-4 inhibitors for one patient to experience a gallbladder or bile duct disease.

CONCLUSIONS

In this population-based cohort study, the use of DPP-4 inhibitors, when compared with SGLT-2 inhibitors, was associated with a moderately increased risk of gallbladder and bile duct disease among patients with type 2 diabetes. This outcome was still quite rare with a high number needed to harm at 6 months and 1 year.

Weight reduction and the risk of gallbladder and biliary disease: A systematic review and meta-analysis of randomized clinical trials

In this meta-analysis, we aim to evaluate the risk of gallbladder and biliary disease of weight management strategies and investigate the association between weight reduction and risk of gallbladder or biliary disease. Randomized controlled trials (RCTs) with a duration of at least 12 weeks that compare antiobesity medications (AOMs) with placebo or bariatric surgery with less intensive weight management strategy were concluded. Weight management strategy was associated with a significant increased risk of gallbladder or biliary disease (OR 1.361, 95% CI 1.147 to 1.614, P < 0.001, I2 = 3.5%), cholelithiasis, cholecystitis, and cholecystectomy compared with placebo or controls. The increased risk of gallbladder or biliary disease was observed both in pharmacotherapies subgroup and bariatric surgery subgroup. With regards of specific pharmacotherapies, an increased risk of gallbladder or biliary disease was observed in trials with glucagon-like peptide 1 receptor agonist (GLP-1 RA) treatments. In addition, trials with indication of obesity and overweight treatment and trials with higher doses showed significant higher risk of gallbladder or biliary disease compared with placebo or controls. In conclusion, weight management strategy was associated with an increased risk of gallbladder or biliary disease when compared with placebo or control groups.

The role of glucagon-like peptide-1 receptor agonists in metabolic dysfunction-associated steatohepatitis

Despite its considerable and growing burden, there are currently no Food and Drug Administration-approved treatments for metabolic dysfunction-associated steatotic liver disease or its progressive form, metabolic dysfunction-associated steatohepatitis (MASH). Several glucagon-like peptide-1 receptor agonists (GLP-1RAs) and other agents are in various phases of clinical development for use in MASH; an ideal therapy should reduce liver fat content, improve chronic liver disease, help mitigate metabolic comorbidities and decrease all-cause mortality. Because of interconnected disease mechanisms, metabolic dysfunction-associated steatotic liver disease/MASH often coexists with type 2 diabetes (T2D), obesity and cardiovascular disease. Various GLP-1RAs are Food and Drug Administration-approved for use in T2D, and two, liraglutide and semaglutide, are approved for overweight and obesity. GLP-1RAs decrease glucose levels and body weight and improve cardiovascular outcomes in people with T2D who are at high risk of cardiovascular disease. In addition, GLP-1RAs have been reported to reduce liver fat content and liver enzymes, reduce oxidative stress and improve hepatic de novo lipogenesis and the histopathology of MASH. Weight loss may contribute to these effects; however, the exact mechanisms are unknown. Adverse events that are commonly associated with GLP-1RAs include vomiting, nausea and diarrhoea. There is a lack of evidence from meta-analyses regarding the increased risk of acute pancreatitis and various forms of cancer with GLP-1RAs. Large-scale, phase 3 trials, which will provide definitive data on GLP-1RAs and other potential therapies in MASH, are ongoing. Given the spectrum of modalities under investigation, it is hoped that these trials will support the identification of pharmacotherapies that provide clinical benefit for patients with MASH.

Cancer biology in diabetes update: Focusing on antidiabetic drugs

The association of type 2 diabetes with certain cancer risk has been of great interest for years. However, the effect of diabetic medications on cancer development is not fully understood. Prospective clinical trials have not elucidated the long-term influence of hypoglycemic drugs on cancer incidence and the safety for cancer-bearing patients with diabetes, whereas numerous preclinical studies have shown that antidiabetic drugs could have an impact on carcinogenesis processes beyond the glycemic control effect. Because there is no evidence of the safety profile of antidiabetic agents on cancer biology, careful consideration would be required when prescribing any medicines to patients with diabetes and existing tumor. In this review, we discuss the potential influence of each diabetes therapy in cancer 'initiation', 'promotion' and 'progression'.

GLP-1 receptor agonist-associated tumor adverse events: A real-world study from 2004 to 2021 based on FAERS

Background: GLP-1 receptor agonists (GLP-1RA) have demonstrated cardiovascular benefits, but the relationship between GLP-1RA and tumors is controversial. Recently, clinical trials reported higher rates of malignancy with semaglutide than control group. As real-world evidence of GLP-1RA-associated tumor risk is very limited, we explored the association of GLP-1RA and all types of neoplasms by mining the FDA Adverse Event Reporting System (FAERS) database. Methods: The FAERS data from the first quarter (Q1) of 2004 to the second quarter (Q2) of 2020 in the AERSMine were extracted to conduct disproportionality analysis, which was used by the proportional reporting ratio (PRR) to assess the relationship between GLP-1RA and all types of neoplasms. Then, the details of disproportionate GLP-1RA-associated tumor cases from Q1 2004 to Q2 2021 in the FAERS Public Dashboard were collected to analyze demographic characteristics. Results: A total of 8718 GLP-1RA-associated tumors were reported. Excluding cases with pre-existing tumors, other glucose-lowering drugs, and other GLP-1RA-related adverse events, diabetes cases with GLP-1RA as the main suspected drug were selected. GLP-1RA did not cause a disproportionate increase in all tumor cases (PRR 0.83) at the SOC level, and there was also no increase in most types of tumors associated with GLP-1RA at the HLGT/HLT levels. Significant signals were detected between GLP-1RA and certain tumors, including thyroid cancers [medullary thyroid cancer (PRR 27.43) and papillary thyroid cancer (PRR 8.68)], pancreatic neoplasms malignant (PRR 9.86), and islet cell neoplasms and APUDoma NEC (PRR 2.86). The combination of GLP-1RA with dipeptidyl-peptidase IV inhibitors (DPP4i) perhaps caused the increased reporting rate in some tumors. Conclusion: Our study provided new real-world evidence for oncology safety information of GLP-1RA. Given the wide use of GLP-1RA, clinicians should be well informed about important potential adverse events. Our pharmacovigilance analysis also prompted clinicians to raise concerns about potential tumor-related adverse effects when combining GLP-1RA with DPP4i.

The role of insulin and incretin-based drugs in biliary tract cancer: epidemiological and experimental evidence

Insulin and incretin-based drugs are important antidiabetic agents with complex effects on cell growth and metabolism. Emerging evidence shows that insulin and incretin-based drugs are associated with altered risk of biliary tract cancer (BTC). Observational study reveals that insulin is associated with an increased risk of extrahepatic cholangiocarcinoma (ECC), but not intrahepatic cholangiocarcinoma (ICC) or gallbladder cancer (GBC). This type-specific effect can be partly explained by the cell of origin and heterogeneous genome landscape of the three subtypes of BTC. Similar to insulin, incretin-based drugs also exhibit very interesting contradictions and inconsistencies in response to different cancer phenotypes, including BTC. Both epidemiological and experimental evidence suggests that incretin-based drugs can be a promoter of some cancers and an inhibitor of others. It is now more apparent that this type of drugs has a broader range of physiological effects on the body, including regulation of endoplasmic reticulum stress, autophagy, metabolic reprogramming, and gene expression. In particular, dipeptidyl peptidase-4 inhibitors (DPP-4i) have a more complex effect on cancer due to the multi-functional nature of DPP-4. DPP-4 exerts both catalytic and non-enzymatic functions to regulate metabolic homeostasis, immune reaction, cell migration, and proliferation. In this review, we collate the epidemiological and experimental evidence regarding the effect of these two classes of drugs on BTC to provide valuable information.

Association between glucagon-like peptide-1 receptor agonists and biliary-related diseases in patients with type 2 diabetes: A nationwide cohort study

STUDY OBJECTIVE

Clinical trials have suggested that glucagon-like peptide-1 receptor agonists (GLP-1RAs) may be associated with a higher risk of biliary-related diseases in patients with type 2 diabetes. Limited real-world studies have examined the comparative biliary safety of GLP-1RAs versus other antihyperglycemic drugs. We aimed to estimate the comparative risk of biliary-related diseases between GLP-1RAs and sodium glucose cotransporter 2 inhibitors (SGLT2is), which are indicated for patients with similar diabetes severity in Taiwan.

DESIGN

Retrospective cohort study.

DATA SOURCE

Taiwan National Health Insurance Database during 2011 to 2018.

PATIENTS

Patients with type 2 diabetes who initiated GLP-1RAs or SGLT2is.

INTERVENTION

GLP-1RAs versus SGLT2is.

MEASUREMENTS AND MAIN RESULTS

We used an on-treatment approach to examine the effect of continuous use and an intention-to-treat approach to assess the effect of initiation of GLP-1RAs versus SGLT2is. We used Coxregression models to estimate the hazard ratios (HRs) and 95% confidenceintervals (CIs) for the composite hospitalized biliary-related diseases, including acute cholecystitis or cholecystectomy, choledocholithiasis, and acute cholangitis, after matching each GLP-1RA initiator to up to 10 SGLT2iinitiators using propensity scores (PSs). Among 78,253 PS-matched patients, GLP-1RA use was associated with a numerically higher risk of biliary-related diseases versus SGLT2i use in the on-treatment analysis, with an HR of 1.20 (95% CI, 0.93-1.56) for the composite outcome, an HR of 1.22 (95% CI, 0.92-1.62) for acute cholecystitis or cholecystectomy, an HR of 1.20 (95% CI, 0.69-2.07) for choledocholithiasis, and an HR of 1.14 (95% CI,0.82-2.42) for acute cholangitis. The HRs were more pronounced in theintention-to-treat analysis (1.27 [95% CI, 1.05-1.53] for the composite outcome, 1.29 [95% CI, 1.04-1.58] foracute cholecystitis or cholecystectomy, 1.74 [95% CI, 1.23-2.46] for choledocholithiasis, and 1.31 [95% CI, 0.89-1.94] for acute cholangitis). The increased risk of the composite outcome associated with GLP-1RAs was more evident in patients aged 〉60 years, women, and 120 days after treatment initiation. Liraglutide, but not dulaglutide, was associated with an elevated risk.

CONCLUSIONS

GLP-1RAs might be associated with an elevated risk of biliary-related diseases compared to SGLT2is in Asian patients with type 2 diabetes.

Glucagon-Like Peptide-1 Receptor Agonists and Hepatic Decompensation Events in Patients With Cirrhosis and Diabetes

BACKGROUND & AIMS

The study sought to compare the effectiveness of glucagon-like peptide-1 receptor agonists (GLP-1RAs) with dipeptidyl peptidase-4 (DPP-4) inhibitors, sulfonylureas, or sodium-glucose cotransporter-2 (SGLT-2) inhibitors in reducing decompensation events, among patients with cirrhosis and type 2 diabetes.

METHODS

This population-based, retrospective cohort study included patients with type 2 diabetes and cirrhosis, in a commercial healthcare database (IBM MarketScan). We constructed 3 pairwise, 1:1 propensity score (PS)-matched cohorts of adults initiating GLP-1RAs or a comparator medication (ie, DPP-4 inhibitors [2006-2020], sulfonylurea [2005-2020], or SGLT-2 inhibitors [2013-2020]). Patients were followed in an as-treated approach for decompensation events (ie, ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, hepatic encephalopathy, or esophageal variceal hemorrhage). Within each PS-matched cohort, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs), controlling for >90 baseline characteristics.

RESULTS

Over 132 days of median follow-up (interquartile range, 73-290 days), PS-matched rates of any decompensation were significantly lower among GLP-1RA initiators, versus DPP-4 inhibitor initiators (105.2 vs 144.0 per 1000 person-years [PY]; HR, 0.68; 95% CI, 0.53-0.88; n = 1431 pairs), and versus sulfonylureas (97.3 vs 144.0 per 1000 PY; HR, 0.64; 95% CI, 0.48-0.84; n = 1246 pairs). Similar, inverse associations were found for individual decompensation events, including ascites, spontaneous bacterial peritonitis, or hepatorenal syndrome (HR, 0.66; 95% CI, 0.45-0.97; and HR, 0.66; 95% CI, 0.46-0.94, respectively); esophageal variceal hemorrhage (HR, 0.62 [95% CI, 0.41-0.92; and HR, 0.59; 95% CI, 0.37-0.92, respectively); and hepatic encephalopathy (HR, 0.76; 95% CI, 0.55-1.06; and HR, 0.60; 95% CI, 0.39-0.92, respectively). Results persisted in subgroups of patients with and without previously decompensated cirrhosis. In contrast, decompensation rates were similar when GLP-1RAs and SGLT-2 inhibitors were directly compared (103.5 vs 112.8 per 1000 PY; HR, 0.89; 95% CI, 0.62-1.28).

CONCLUSIONS

Among cirrhotic patients with type 2 diabetes, we find high rates of decompensation, consistent with previous reports; these rates were substantially lower among GLP-1RA initiators compared with DPP-4 inhibitors or sulfonylureas.

Liraglutide prevents high glucose induced HUVECs dysfunction via inhibition of PINK1/Parkin-dependent mitophagy

Functional loss of endothelial cells will lead to development and progression of atherosclerosis in diabetic patients. However, dysfunction of endothelial cells in diabetes has yet to be fully understood. We aimed to characterize the potential effects of liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist, on preventing high glucose-induced endothelial dysfunction and excessive mitophagic response. Pretreatment with liraglutide prevented downregulation of eNOS phosphorylation and NO secretion, and reduced apoptosis and oxidative stress of the human umbilical vein endothelial cells (HUVECs) exposed to high glucose. We further demonstrated that liraglutide likely mediated such protective effects by reducing PINK1/Parkin mediated mitophagy. Liraglutide markedly decreased high glucose-induced mitochondrial ROS, lessened PINK1 expression and mitochondrial accumulation of Parkin, but recovered SIRT1 expression. Seahorse analysis revealed that liraglutide mitigated high glucose-induced reduction of basal and maximum respiration rates as well as spare respiration capacity. Inhibition of Parkin by RNA silencing not only resulted in increased mitochondrial and cytosolic ROS and reduced mitochondrial mass and mitochondrial membrane potential, but also led to increased apoptotic responses in high glucose treated HUVECs which were not preventable by liraglutide. Together, our study reveals that liraglutide acts upstream of the PINK1/Parkin pathway to effectively counteract high glucose induced cell dysfunction by suppression of the PINK1/Parkin-dependent mitophagy. Therefore, its use as an adjunct therapy for type 2 diabetes mellitus is warranted to reduce the risk of atherosclerosis. Further research is required to examine the exact molecules, including SIRT1, upstream of the PINK1/parkin pathway that liraglutide targets to maintain the mitochondrial homeostasis.

The Neglected Role of Bile Duct Epithelial Cells in NASH

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide, and affects 25% of the population in Western countries. NAFLD is the hepatic manifestation of the metabolic syndrome, linked to insulin resistance, which is the common pathogenetic mechanism. In approximately 40% of NAFLD patients, steatosis is associated with necro-inflammation and fibrosis, resulting in nonalcoholic steatohepatitis (NASH), a severe condition that may progress to cirrhosis and liver cancer. Although the hepatocyte represents the main target of the disease, involvement of the bile ducts occurs in a subset of patients with NASH, and is characterized by ductular reaction and activation of the progenitor cell compartment, which incites portal fibrosis and disease progression. We aim to dissect the multiple biological effects that adipokines and metabolic alterations exert on cholangiocytes to derive novel information on the mechanisms driven by insulin resistance, which promote fibro-inflammation and carcinogenesis in NASH.

Antidiabetic Medications and the Risk of Prostate Cancer in Patients with Diabetes Mellitus: A Systematic Review and Meta-analysis

BACKGROUND

Antidiabetic medications (ADMs) may modify prostate cancer (PCa) risk in patients with diabetes mellitus (DM). Accordingly, the current study assessed the possible associations between ADMs and the risk of PCa in diabetics.

METHODS

A systematic literature search (PubMed, Embase and Cochrane Library) identified studies evaluating the associations between ADMs and incidence of PCa. A meta-analysis followed PRISMA was performed using odds ratio (OR) with 95% confidence interval (CI) as effect measures.

RESULTS

In total of 47 studies involving 3,094,152 patients with diabetes were included. Results of meta-analysis of the observational studies suggested no significant association between metformin, thiazolidinediones, sulfonylureas, insulin or dipeptidyl peptidase-4 inhibitors administration and the risk of PCa (All p-values > 0.05). Separate analysis of randomized controlled trials (RCTs) revealed a significant reduction in PCa risk with thiazolidinediones (OR = 0.55, p = 0.04) or glucagon-like peptide-1 receptor agonists (GLP-1RA) administration (OR = 0.53, p = 0.006), whereas no significant association was found in SGLT2 inhibitors (p = 0.3).

CONCLUSION

Thiazolidinediones or GLP-1RA administration may have benefits in PCa based on RCTs, however, further research is needed to confirm these findings.

Novel therapeutic targets for cholestatic and fatty liver disease

Cholestatic and non-alcoholic fatty liver disease (NAFLD) share several key pathophysiological mechanisms which can be targeted by novel therapeutic concepts that are currently developed for both areas. Nuclear receptors (NRs) are ligand-activated transcriptional regulators of key metabolic processes including hepatic lipid and glucose metabolism, energy expenditure and bile acid (BA) homoeostasis, as well as inflammation, fibrosis and cellular proliferation. Dysregulation of these processes contributes to the pathogenesis and progression of cholestatic as well as fatty liver disease, placing NRs at the forefront of novel therapeutic approaches. This includes BA and fatty acid activated NRs such as farnesoid-X receptor (FXR) and peroxisome proliferator-activated receptors, respectively, for which high affinity therapeutic ligands targeting specific or multiple isoforms have been developed. Moreover, novel liver-specific ligands for thyroid hormone receptor beta 1 complete the spectrum of currently available NR-targeted drugs. Apart from FXR ligands, BA signalling can be targeted by mimetics of FXR-activated fibroblast growth factor 19, modulation of their enterohepatic circulation through uptake inhibitors in hepatocytes and enterocytes, as well as novel BA derivatives undergoing cholehepatic shunting (instead of enterohepatic circulation). Other therapeutic approaches more directly target inflammation and/or fibrosis as critical events of disease progression. Combination strategies synergistically targeting metabolic disturbances, inflammation and fibrosis may be ultimately necessary for successful treatment of these complex and multifactorial disorders.

Alterations in microbiota and their metabolites are associated with beneficial effects of bile acid sequestrant on icteric primary biliary Cholangitis

Background: Increasing data suggests an interaction between bile acids and intestinal microbiota in the pathogenesis of primary biliary cholangitis (PBC). Bile acid sequestrants are widely used to bind bile acids in the intestinal lumen and are therefore posited to impact gut bacteria. Herein we aimed to investigate the effects of cholestyramine on the bile acid profile and gut microbiome in a cohort of icteric PBC patients.Results: Thirty-three PBC patients were treated with cholestyramine, serum and stool samples were collected at baseline, 4 and 16 weeks. Shotgun metagenomic sequencing and targeted metabolomic profiling were performed. Following cholestyramine administration, patients exhibited a high interpersonal variability in remission of cholestasis, and were therefore dichotomized according to the decrease of total bilirubin. Gut microbial co-abundance networks showed distinct taxa interactions between subjects with superior remission (SR) and those with inferior remission (IR) at baseline. After treatment, compositional shifts of the microbiome in the SR group were characterized with enrichment of two Lachnospiraceae species, typically producing short-chain fatty acids (SCFAs). In contrast, Klebsiella pneumonia, a commensal pathobiont, was only increased in the IR group. Correspondingly, metabolome analysis demonstrated that patients with SR, but not IR, were marked by elevations of SCFAs including valeric acid and caproic acid. Finally, integrative analysis identified robust associations between the variations of microbiota, metabolites, and inflammatory cytokines in SR group, indicating potential mechanistic links.Conclusions: Beneficial responses caused by cholestyramine were closely related with compositional and functional alterations in gut commensal, highlighting the possibility of exploring bile acid-microbiota interactions for treating PBC.

Mechanism of cholangiocellular damage and repair during cholestasis

The mechanism of damage of the biliary epithelium remains partially unexplored. However, recently many works have offered new evidence regarding the cholangiocytes' damage process, which is the main target in a broad spectrum of pathologies ranging from acute cholestasis, cholangiopathies to cholangiocarcinoma. This is encouraging since some works addressed this epithelium's relevance in health and disease until a few years ago. The biliary tree in the liver, comprised of cholangiocytes, is a pipeline for bile flow and regulates key hepatic processes such as proliferation, regeneration, immune response, and signaling. This review aimed to compile the most recent advances on the mechanisms of cholangiocellular damage during cholestasis, which, although it is present in many cholangiopathies, is not necessarily a common or conserved process in all of them, having a relevant role cAMP and PKA during obstructive cholestasis, as well as Ca²⁺-dependent PKC in functional cholestasis. Cholangiocellular damage could vary according to the type of cholestasis, the aggressor, or the bile ducts' location where it develops and what kind of damage can favor cholangiocellular carcinoma development.

Use of incretin-based drugs and risk of cholangiocarcinoma: Scandinavian cohort study

AIMS/HYPOTHESIS

Concerns have been raised regarding a potential association of use of the incretin-based drugs dipeptidyl peptidase 4 (DPP4) inhibitors and glucagon-like peptide-1 (GLP-1)-receptor agonists with risk of cholangiocarcinoma. We examined this association in nationwide data from three countries.

METHODS

We used data from nationwide registers in Sweden, Denmark and Norway, 2007-2018, to conduct two cohort studies, one for DPP4 inhibitors and one for GLP-1-receptor agonists, to investigate the risk of incident cholangiocarcinoma compared with an active-comparator drug class (sulfonylureas). The cohorts included patients initiating treatment episodes with DPP4 inhibitors vs sulfonylureas, and GLP-1-receptor agonists vs sulfonylureas. We used Cox regression models, adjusted for potential confounders, to estimate hazard ratios from day 366 after treatment initiation to account for cancer latency.

RESULTS

The main analyses of DPP4 inhibitors included 1,414,144 person-years of follow-up from 222,577 patients receiving DPP4 inhibitors (median [IQR] follow-up time, 4.5 [2.6-7.0] years) and 123,908 patients receiving sulfonylureas (median [IQR] follow-up time, 5.1 [2.9-7.8] years) during which 350 cholangiocarcinoma events occurred. Use of DPP4 inhibitors, compared with sulfonylureas, was not associated with a statistically significant increase in risk of cholangiocarcinoma (incidence rate 26 vs 23 per 100,000 person-years; adjusted HR, 1.15 [95% CI 0.90, 1.46]; absolute rate difference 3 [95% CI -3, 10] events per 100,000 person-years). The main analyses of GLP-1-receptor agonists included 1,036,587 person-years of follow-up from 96,813 patients receiving GLP-1-receptor agonists (median [IQR] follow-up time, 4.4 [2.4-6.9] years) and 142,578 patients receiving sulfonylureas (median [IQR] follow-up time, 5.5 [3.2-8.1] years) during which 249 cholangiocarcinoma events occurred. Use of GLP-1-receptor agonists was not associated with a statistically significant increase in risk of cholangiocarcinoma (incidence rate 26 vs 23 per 100,000 person-years; adjusted HR, 1.25 [95% CI 0.89, 1.76]; absolute rate difference 3 [95% CI -5, 13] events per 100,000 patient-years).

CONCLUSIONS/INTERPRETATION

In this analysis using nationwide data from three countries, use of DPP4 inhibitors and GLP-1-receptor agonists, compared with sulfonylureas, was not associated with a significantly increased risk of cholangiocarcinoma.

Safety of Semaglutide

The glucagon-like peptide-1 receptor agonist (GLP-1RA) semaglutide is the most recently approved agent of this drug class, and the only GLP-1RA currently available as both subcutaneous and oral formulation. While GLP-1RAs effectively improve glycemic control and cause weight loss, potential safety concerns have arisen over the years. For semaglutide, such concerns have been addressed in the extensive phase 3 registration trials including cardiovascular outcome trials for both subcutaneous (SUSTAIN: Semaglutide Unabated Sustainability in Treatment of Type 2 Diabetes) and oral (PIONEER: Peptide InnOvatioN for the Early diabEtes tReatment) semaglutide and are being studied in further trials and registries, including real world data studies. In the current review we discuss the occurrence of adverse events associated with semaglutide focusing on hypoglycemia, gastrointestinal side effects, pancreatic safety (pancreatitis and pancreatic cancer), thyroid cancer, gallbladder events, cardiovascular aspects, acute kidney injury, diabetic retinopathy (DRP) complications and injection-site and allergic reactions and where available, we highlight potential underlying mechanisms. Furthermore, we discuss whether effects are specific for semaglutide or a class effect. We conclude that semaglutide induces mostly mild-to-moderate and transient gastrointestinal disturbances and increases the risk of biliary disease (cholelithiasis). No unexpected safety issues have arisen to date, and the established safety profile for semaglutide is similar to that of other GLP-1RAs where definitive conclusions for pancreatic and thyroid cancer cannot be drawn at this point due to low incidence of these conditions. Due to its potent glucose-lowering effect, patients at risk for deterioration of existing DRP should be carefully monitored if treated with semaglutide, particularly if also treated with insulin. Given the beneficial metabolic and cardiovascular actions of semaglutide, and the low risk for severe adverse events, semaglutide has an overall favorable risk/benefit profile for patient with type 2 diabetes.

Cyclic AMP Signaling in Biliary Proliferation: A Possible Target for Cholangiocarcinoma Treatment?

Cholangiocarcinoma is a lethal disease with scarce response to current systemic therapy. The rare occurrence and large heterogeneity of this cancer, together with poor knowledge of its molecular mechanisms, are elements contributing to the difficulties in finding an appropriate cure. Cholangiocytes (and their cellular precursors) are considered the liver component giving rise to cholangiocarcinoma. These cells respond to several hormones, neuropeptides and molecular stimuli employing the cAMP/PKA system for the translation of messages in the intracellular space. For instance, in physiological conditions, stimulation of the secretin receptor determines an increase of intracellular levels of cAMP, thus activating a series of molecular events, finally determining in bicarbonate-enriched choleresis. However, activation of the same receptor during cholangiocytes' injury promotes cellular growth again, using cAMP as the second messenger. Since several scientific pieces of evidence link cAMP signaling system to cholangiocytes' proliferation, the possible changes of this pathway during cancer growth also seem relevant. In this review, we summarize the current findings regarding the cAMP pathway and its role in biliary normal and neoplastic cell proliferation. Perspectives for targeting the cAMP machinery in cholangiocarcinoma therapy are also discussed.

CD26/DPP-4: Type 2 Diabetes Drug Target with Potential Influence on Cancer Biology

Simple Summary

Dipeptidyl peptidase (DPP)-4 inhibitor is widely used for type 2 diabetes. Although DPP-4/CD26 has been recognized as both a suppressor and inducer in tumor biology due to its various functions, how DPP-4 inhibitor affects cancer progression in diabetic patients is still unknown. The aim of this review is to summarize one unfavorable aspect of DPP-4 inhibitor in cancer-bearing diabetic patients.

Abstract

DPP-4/CD26, a membrane-bound glycoprotein, is ubiquitously expressed and has diverse biological functions. Because of its enzymatic action, such as the degradation of incretin hormones, DPP-4/CD26 is recognized as the significant therapeutic target for type 2 diabetes (T2DM); DPP-4 inhibitors have been used as an anti-diabetic agent for a decade. The safety profile of DPP-4 inhibitors for a cardiovascular event in T2DM patients has been widely analyzed; however, a clear association between DPP-4 inhibitors and tumor biology is not yet established. Previous preclinical studies reported that DPP-4 suppression would impact tumor progression processes. With regard to this finding, we have shown that the DPP-4 inhibitor induces breast cancer metastasis and chemoresistance via an increase in its substrate C-X-C motif chemokine 12, and the consequent induction of epithelial-mesenchymal transition in the tumor. DPP-4/CD26 plays diverse pivotal roles beyond blood glucose control; thus, DPP-4 inhibitors can potentially impact cancer-bearing T2DM patients either favorably or unfavorably. In this review, we primarily focus on the possible undesirable effect of DPP-4 inhibition on tumor biology. Clinicians should note that the safety of DPP-4 inhibitors for diabetic patients with an existing cancer is an unresolved issue, and further mechanistic analysis is essential in this field.

Incretin-based therapy and risk of cholangiocarcinoma: a nested case-control study in a population of subjects with type 2 diabetes

BACKGROUND AND AIMS

One cohort and several basic science studies have raised suspicion about an association between incretin therapies and cholangiocarcinoma. Our aim was to verify the occurrence of CC in relation to incretin-based medication use versus any antidiabetic treatment in an unselected population of diabetic patients.

METHODS

A population-based matched case-control study was conducted using administrative data from the Region of Piedmont (4,400,000 inhabitants), Italy. From a database of 312,323 patients treated with antidiabetic drugs, we identified 744 cases hospitalized for cholangiocarcinoma from 2010 to 2016 and 2976 controls matched for gender, age and initiation of antidiabetic therapy; cases and controls were compared for exposure to incretin-based medications. All analyses were adjusted for risk factors for CC, as ascertained by hospital discharge records. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by fitting a conditional logistic model.

RESULTS

The mean age of the sampled population (cases and controls, 75 years) was very high, with no gender prevalence. Five per cent was treated with incretin-based medications. After adjusting for possible confounders, we found no increased risk of cholangiocarcinoma associated with the use of either DPP4i (OR 0.98, 95% CI 0.75-1.29: p = 0.89) or GLP-1-RA (OR 1.09, 95% CI 0.63-1.89; p = 0.76) in the 24 months before hospital admission. Neither the duration of the therapy nor the dose modified the risk of cholangiocarcinoma.

CONCLUSIONS

Our findings suggest that, in an unselected population, the use of both classes of incretin-based medications is not associated with an increased risk of cholangiocarcinoma.

Review: Diabetes, Obesity, and Cancer-Pathophysiology and Clinical Implications

Obesity and diabetes have both been associated with an increased risk of cancer. In the face of increasing obesity and diabetes rates worldwide, this is a worrying trend for cancer rates. Factors such as hyperinsulinemia, chronic inflammation, antihyperglycemic medications, and shared risk factors have all been identified as potential mechanisms underlying the relationship. The most common obesity- and diabetes-related cancers are endometrial, colorectal, and postmenopausal breast cancers. In this review, we summarize the existing evidence that describes the complex relationship between obesity, diabetes, and cancer, focusing on epidemiological and pathophysiological evidence, and also reviewing the role of antihyperglycemic agents, novel research approaches such as Mendelian Randomization, and the methodological limitations of existing research. In addition, we also describe the bidirectional relationship between diabetes and cancer with a review of the evidence summarizing the risk of diabetes following cancer treatment. We conclude this review by providing clinical implications that are relevant for caring for patients with obesity, diabetes, and cancer and provide recommendations for improving both clinical care and research for patients with these conditions.

Incretin based drugs and risk of cholangiocarcinoma among patients with type 2 diabetes: population based cohort study

OBJECTIVE

To determine whether use of dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists are associated with an increased risk of cholangiocarcinoma in adults with type 2 diabetes.

DESIGN

Population based cohort study.

SETTING

General practices contributing data to the UK Clinical Practice Research Datalink.

PARTICIPANTS

154 162 adults newly treated with antidiabetic drugs between 1 January 2007 and 31 March 2017, followed until 31 March 2018.

MAIN OUTCOME MEASURES

Use of DPP-4 inhibitors and GLP-1 receptor agonists was modelled as a time varying variable and compared with use of other second or third line antidiabetic drugs. All exposures were lagged by one year to account for cancer latency and to minimise reverse causality. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals of incident cholangiocarcinoma associated with use of DPP-4 inhibitors and GLP-1 receptor agonists, separately. A post hoc pharmacovigilance analysis was conducted using the World Health Organization's global individual case safety report database, VigiBase, to estimate reporting odds ratios of cholangiocarcinoma.

RESULTS

During 614 274 person years of follow-up, 105 incident cholangiocarcinoma events occurred (rate 17.1 per 100 000 person years). Use of DPP-4 inhibitors was associated with a 77% increased hazard of cholangiocarcinoma (hazard ratio 1.77, 95% confidence interval 1.04 to 3.01). Use of GLP-1 receptor agonists was associated with an increased hazard with a wide confidence interval (hazard ratio 1.97, 0.83 to 4.66). In the pharmacovigilance analysis, the use of DPP-4 inhibitors and GLP-1 receptor agonists were both associated with increased reporting odds ratios for cholangiocarcinoma, compared with use of sulfonylureas or thiazolidinediones (1.63, 1.00 to 2.66, 4.73, 2.95 to 7.58, respectively).

CONCLUSION

Compared with use of other second or third line antidiabetic drugs, use of DPP-4 inhibitors, and possibly GLP-1 receptor agonists, might be associated with an increased risk of cholangiocarcinoma in adults with type 2 diabetes.

Colesevelam attenuates cholestatic liver and bile duct injury in Mdr2-/- mice by modulating composition, signalling and excretion of faecal bile acids

BACKGROUND AND AIMS

Interruption of the enterohepatic circulation of bile acids (BAs) may protect against BA-mediated cholestatic liver and bile duct injury. BA sequestrants are established to treat cholestatic pruritus, but their impact on the underlying cholestasis is still unclear. We aimed to explore the therapeutic effects and mechanisms of the BA sequestrant colesevelam in a mouse model of sclerosing cholangitis.

METHODS

Mdr2^-/- mice received colesevelam for 8 weeks. Gene expression profiles of BA homeostasis, inflammation and fibrosis were explored in liver, intestine and colon. Hepatic and faecal BA profiles and gut microbiome were analysed. Glucagon-like peptide 1 (GLP-1) levels in portal blood were measured by ELISA. Furthermore, Mdr2^-/- mice as well as wild-type 3,5-diethoxy-carbonyl-1,4-dihydrocollidine-fed mice were treated with GLP-1-receptor agonist exendin-4 for 2 weeks prior to analysis.

RESULTS

Colesevelam reduced serum liver enzymes, BAs and expression of proinflammatory and profibrogenic markers. Faecal BA profiling revealed increased levels of secondary BAs after resin treatment, while hepatic and biliary BA composition showed a shift towards more hydrophilic BAs. Colonic GLP-1 secretion, portal venous GLP-1 levels and intestinal messenger RNA expression of gut hormone Proglucagon were increased, while ileal Fgf15 expression was abolished by colesevelam. Exendin-4 treatment increased bile duct mass without promoting a reactive cholangiocyte phenotype in mouse models of sclerosing cholangitis. Microbiota analysis showed an increase of the phylum δ-Proteobacteria after colesevelam treatment and a shift within the phyla Firmicutes from Clostridiales to Lactobacillus.

CONCLUSION

Colesevelam increases faecal BA excretion and enhances BA conversion towards secondary BAs, thereby stimulating secretion of GLP-1 from enteroendocrine L-cells and attenuates liver and bile duct injury in Mdr2^-/- mice.

Animal models of cholestasis: An update on inflammatory cholangiopathies

Cholestasis is a frequent clinical condition initiating or complicating chronic liver diseases, particularly cholangiopathies, where the biliary epithelium is the primary target of the pathogenetic sequence. Until a few decades ago, understanding of cholestasis relied mostly on the experimental model of bile duct ligation in rodents. However, a simple model of biliary obstruction cannot reproduce the complex mechanisms and networks leading to cholestasis in cholangiopathies. These networks are underpinned by an intricate dysregulation of pro-inflammatory and pro-fibrotic signals involving besides cholangiocytes, multiple cell elements of both innate and adaptive immunity. Therefore, in the last years, a wide range of animal models of biliary injury have been developed, mostly in mice, following three main approaches, chemical induction, immunization and genetic manipulation. In this review, we will give an update of the animal models of the two main cholangiopathies, primary sclerosing cholangitis and primary biliary cholangitis, which have provided us with the most relevant insights into the pathogenesis of these still controversial diseases.

Pathobiology of biliary epithelia

Cholangiocytes are epithelial cells that line the intra- and extrahepatic biliary tree. They serve predominantly to mediate the content of luminal biliary fluid, which is controlled via numerous signaling pathways influenced by endogenous (e.g., bile acids, nucleotides, hormones, neurotransmitters) and exogenous (e.g., microbes/microbial products, drugs etc.) molecules. When injured, cholangiocytes undergo apoptosis/lysis, repair and proliferation. They also become senescent, a form of cell cycle arrest, which may prevent propagation of injury and/or malignant transformation. Senescent cholangiocytes can undergo further transformation to a senescence-associated secretory phenotype (SASP), where they begin secreting pro-inflammatory and pro-fibrotic signals that may contribute to disease initiation and progression. These and other concepts related to cholangiocyte pathobiology will be reviewed herein. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

TGR5 contributes to hepatic cystogenesis in rodents with polycystic liver diseases through cyclic adenosine monophosphate/Gαs signaling

Hepatic cystogenesis in polycystic liver disease is associated with increased levels of cyclic adenosine monophosphate (cAMP) in cholangiocytes lining liver cysts. Takeda G protein receptor 5 (TGR5), a G protein-coupled bile acid receptor, is linked to cAMP and expressed in cholangiocytes. Therefore, we hypothesized that TGR5 might contribute to disease progression. We examined expression of TGR5 and Gα proteins in cultured cholangiocytes and in livers of animal models and humans with polycystic liver disease. In vitro, we assessed cholangiocyte proliferation, cAMP levels, and cyst growth in response to (1) TGR5 agonists (taurolithocholic acid, oleanolic acid [OA], and two synthetic compounds), (2) a novel TGR5 antagonist (m-tolyl 5-chloro-2-[ethylsulfonyl] pyrimidine-4-carboxylate [SBI-115]), and (3) a combination of SBI-115 and pasireotide, a somatostatin receptor analogue. In vivo, we examined hepatic cystogenesis in OA-treated polycystic kidney rats and after genetic elimination of TGR5 in double mutant TGR5^-/- ;Pkhd1^del2/del2 mice. Compared to control, expression of TGR5 and Gα_s (but not Gα_i and Gα_q ) proteins was increased 2-fold to 3-fold in cystic cholangiocytes in vitro and in vivo. In vitro, TGR5 stimulation enhanced cAMP production, cell proliferation, and cyst growth by ∼40%; these effects were abolished after TGR5 reduction by short hairpin RNA. OA increased cystogenesis in polycystic kidney rats by 35%; in contrast, hepatic cystic areas were decreased by 45% in TGR5-deficient TGR5^-/- ;Pkhd1^del2/del2 mice. TGR5 expression and its colocalization with Gα_s were increased ∼2-fold upon OA treatment. Levels of cAMP, cell proliferation, and cyst growth in vitro were decreased by ∼30% in cystic cholangiocytes after treatment with SBI-115 alone and by ∼50% when SBI-115 was combined with pasireotide.

CONCLUSION

TGR5 contributes to hepatic cystogenesis by increasing cAMP and enhancing cholangiocyte proliferation; our data suggest that a TGR5 antagonist alone or concurrently with somatostatin receptor agonists represents a potential therapeutic approach in polycystic liver disease. (Hepatology 2017;66:1197-1218).

Biology of Cholangiocytes: From Bench to Bedside

Cholangiocytes, the lining epithelial cells in bile ducts, are an important subset of liver cells. They are activated by endogenous and exogenous stimuli and are involved in the modification of bile volume and composition. They are also involved in damaging and repairing the liver. Cholangiocytes have many functions including bile production. They are also involved in transport processes that regulate the volume and composition of bile. Cholangiocytes undergo proliferation and cell death under a variety of conditions. Cholangiocytes have functional and morphological heterogenecity. The immunobiology of cholangiocytes is important, particularly for understanding biliary disease. Secretion of different proinflammatory mediators, cytokines, and chemokines suggests the major role that cholangiocytes play in inflammatory reactions. Furthermore, paracrine secretion of growth factors and peptides mediates extensive cross-talk with other liver cells, including hepatocytes, stellate cells, stem cells, subepithelial myofibroblasts, endothelial cells, and inflammatory cells. Cholangiopathy refers to a category of chronic liver diseases whose primary disease target is the cholangiocyte. Cholangiopathy usually results in end-stage liver disease requiring liver transplant. We summarize the biology of cholangiocytes and redefine the concept of cholangiopathy. We also discuss the recent progress that has been made in understanding the pathogenesis of cholangiopathy and how such progress has influenced therapy.

New therapeutic concepts in bile acid transport and signaling for management of cholestasis

The identification of the key regulators of bile acid (BA) synthesis and transport within the enterohepatic circulation has revealed potential targets for pharmacological therapies of cholestatic liver diseases. Novel drug targets include the bile BA receptors, farnesoid X receptor and TGR5, the BA-induced gut hormones, fibroblast growth factor 19 and glucagon-like peptide 1, and the BA transport systems, apical sodium-dependent bile acid transporter and Na⁺ -taurocholate cotransporting polypeptide, within the enterohepatic circulation. Moreover, BA derivatives undergoing cholehepatic shunting may allow improved targeting to the bile ducts. This review focuses on the pathophysiological basis, mechanisms of action, and clinical development of novel pharmacological strategies targeting BA transport and signaling in cholestatic liver diseases. (Hepatology 2017;65:1393-1404).

Regulators of Cholangiocyte Proliferation

Cholangiocytes, a small population of cells within the normal liver, have been the focus of a significant amount of research over the past two decades because of their involvement in cholangiopathies such as primary sclerosing cholangitis and primary biliary cholangitis. This article summarizes landmark studies in the field of cholangiocyte physiology and aims to provide an updated review of biliary pathogenesis. The historical approach of rodent extrahepatic bile duct ligation and the relatively recent utilization of transgenic mice have led to significant discoveries in cholangiocyte pathophysiology. Cholangiocyte physiology is a complex system based on heterogeneity within the biliary tree and a number of signaling pathways that serve to regulate bile composition. Studies have expanded the list of neuropeptides, neurotransmitters, and hormones that have been shown to be key regulators of proliferation and biliary damage. The peptide histamine and hormones, such as melatonin and angiotensin, angiotensin, as well as numerous sex hormones, have been implicated in cholangiocyte proliferation during cholestasis. Numerous pathways promote cholangiocyte proliferation during cholestasis, and there is growing evidence to suggest that cholangiocyte proliferation may promote hepatic fibrosis. These pathways may represent significant therapeutic potential for a subset of cholestatic liver diseases that currently lack effective therapies.

Glucagon-like Peptide-1 and the Central/Peripheral Nervous System: Crosstalk in Diabetes

Glucagon-like peptide-1 (GLP-1) is released in response to meals and exerts important roles in the maintenance of normal glucose homeostasis. GLP-1 is also important in the regulation of neurologic and cognitive functions. These actions are mediated via neurons in the nucleus of the solitary tract that project to multiple regions expressing GLP-1 receptors (GLP-1Rs). Treatment with GLP-1R agonists (GLP-1-RAs) reduces ischemia-induced hyperactivity, oxidative stress, neuronal damage and apoptosis, cerebral infarct volume, and neurologic damage, after cerebral ischemia, in experimental models. Ongoing human trials report a neuroprotective effect of GLP-1-RAs in Alzheimer's and Parkinson's disease. In this review, we discuss the role of GLP-1 and GLP-1-RAs in the nervous system with focus on GLP-1 actions on appetite regulation, glucose homeostasis, and neuroprotection.

Exenatide improves both hepatic and adipose tissue insulin resistance: A dynamic positron emission tomography study

Glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1-RAs) act on multiple tissues, in addition to the pancreas. Recent studies suggest that GLP-1-RAs act on liver and adipose tissue to reduce insulin resistance (IR). Thus, we evaluated the acute effects of exenatide (EX) on hepatic (Hep-IR) and adipose (Adipo-IR) insulin resistance and glucose uptake. Fifteen male subjects (age = 56 ± 8 years; body mass index = 29 ± 1 kg/m2 ; A1c = 5.7 ± 0.1%) were studied on two occasions, with a double-blind subcutaneous injection of EX (5 μg) or placebo (PLC) 30 minutes before a 75-g oral glucose tolerance test (OGTT). During OGTT, we measured hepatic (HGU) and adipose tissue (ATGU) glucose uptake with [18 F]2-fluoro-2-deoxy-D-glucose/positron emission tomography, lipolysis (RaGly) with [U-2 H5 ]-glycerol, oral glucose absorption (RaO) with [U-13 C6 ]-glucose, and hepatic glucose production (EGP) with [6,6-2 H2 ]-glucose. Adipo-IR and Hep-IR were calculated as (FFA0-120min ) × (Ins0-120min ) and (EGP0-120min ) × (Ins0-120min ), respectively. EX reduced RaO, resulting in reduced plasma glucose and insulin concentration from 0 to 120 minutes postglucose ingestion. EX decreased Hep-IR (197 ± 28 to 130 ± 37; P = 0.02) and increased HGU of orally administered glucose (23 ± 4 to 232 ± 89 [μmol/min/L]/[μmol/min/kg]; P = 0.003) despite lower insulin (23 ± 5 vs. 41 ± 5 mU/L; P < 0.02). EX enhanced insulin suppression of RaGly by decreasing Adipo-IR (23 ± 4 to 13 ± 3; P = 0.009). No significant effect of insulin was observed on ATGU (EX = 1.16 ± 0.15 vs. PLC = 1.36 ± 0.13 [μmol/min/L]/[μmol/min/kg]).

CONCLUSION

Acute EX administration (1) improves Hep-IR, decreases EGP, and enhances HGU and (2) reduces Adipo-IR, improves the antilipolytic effect of insulin, and reduces plasma free fatty acid levels during OGTT. (Hepatology 2016;64:2028-2037).

Inhibition of intestinal bile acid absorption improves cholestatic liver and bile duct injury in a mouse model of sclerosing cholangitis

BACKGROUND AND AIMS

Approximately 95% of bile acids (BAs) excreted into bile are reabsorbed in the gut and circulate back to the liver for further biliary secretion. Therefore, pharmacological inhibition of the ileal apical sodium-dependent BA transporter (ASBT/SLC10A2) may protect against BA-mediated cholestatic liver and bile duct injury.

METHODS

Eight week old Mdr2(-/-) (Abcb4(-/-)) mice (model of cholestatic liver injury and sclerosing cholangitis) received either a diet supplemented with A4250 (0.01% w/w) - a highly potent and selective ASBT inhibitor - or a chow diet. Liver injury was assessed biochemically and histologically after 4weeks of A4250 treatment. Expression profiles of genes involved in BA homeostasis, inflammation and fibrosis were assessed via RT-PCR from liver and ileum homogenates. Intestinal inflammation was assessed by RNA expression profiling and immunohistochemistry. Bile flow and composition, as well as biliary and fecal BA profiles were analyzed after 1week of ASBT inhibitor feeding.

RESULTS

A4250 improved sclerosing cholangitis in Mdr2(-/-) mice and significantly reduced serum alanine aminotransferase, alkaline phosphatase and BAs levels, hepatic expression of pro-inflammatory (Tnf-α, Vcam1, Mcp-1) and pro-fibrogenic (Col1a1, Col1a2) genes and bile duct proliferation (mRNA and immunohistochemistry for cytokeratin 19 (CK19)). Furthermore, A4250 significantly reduced bile flow and biliary BA output, which correlated with reduced Bsep transcription, while Ntcp and Cyp7a1 were induced. Importantly A4250 significantly reduced biliary BA secretion but preserved HCO3(-) and biliary phospholipid secretion resulting in an increased HCO3(-)/BA and PL/BA ratio. In addition, A4250 profoundly increased fecal BA excretion without causing diarrhea and altered BA pool composition, resulting in diminished concentrations of primary BAs tauro-β-muricholic acid and taurocholic acid.

CONCLUSIONS

Pharmacological ASBT inhibition attenuates cholestatic liver and bile duct injury by reducing biliary BA concentrations in mice.

GLP-1 receptor agonists: effects on the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, and its incidence has been increasing recently. In addition to hepatic complications, NAFLD is also recognized as an independent risk factor for cardiovascular disease. Unfortunately, the current therapies for NAFLD display variable efficacy; a novel and effective drug is urgently needed. Glucagon-like peptide-1 (GLP-1), a receptor agonist is a new drug approved for treating type 2 diabetes. Recently, these types of agents have shown a novel therapeutic effect on NAFLD. However, the mechanisms of GLP-1 receptor agonists on the treatment of NAFLD have not yet been explained precisely. Recent studies have demonstrated that GLP-1 reverses the progression of NAFLD not only indirectly through an incretin effect that improves key parameters involved in NAFLD, but also a direct effect on lipid metabolism of hepatocytes and inflammation in liver. In this review, we provided an overview of the role and mechanisms of GLP-1 in the therapy of NAFLD.

Activation of the developmental pathway neurogenin-3/microRNA-7a regulates cholangiocyte proliferation in response to injury

The activation of the biliary stem-cell signaling pathway hairy and enhancer of split 1/pancreatic duodenal homeobox-1 (Hes-1/PDX-1) in mature cholangiocytes determines cell proliferation. Neurogenin-3 (Ngn-3) is required for pancreas development and ductal cell neogenesis. PDX-1-dependent activation of Ngn-3 initiates the differentiation program by inducing microRNA (miR)-7 expression. Here we investigated the role Ngn-3 on cholangiocyte proliferation. Expression levels of Ngn-3 and miR-7 isoforms were tested in cholangiocytes from normal and cholestatic human livers. Ngn-3 was knocked-down in vitro in normal rat cholangiocytes by short interfering RNA (siRNA). In vivo, wild-type and Ngn-3-heterozygous (+/-) mice were subjected to 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding (a model of sclerosing cholangitis) or bile duct ligation (BDL). In the liver, Ngn-3 is expressed specifically in cholangiocytes of primary sclerosing cholangitis (PSC) patients and in mice subjected to DDC or BDL, but not in normal human and mouse livers. Expression of miR-7a-1 and miR-7a-2 isoforms, but not miR-7b, was increased in DDC cholangiocytes compared to normal ones. In normal rat cholangiocytes, siRNA against Ngn-3 blocked the proliferation stimulated by exendin-4. In addition, Ngn-3 knockdown neutralized the overexpression of insulin growth factor-1 (IGF1; promitotic effector) observed after exposure to exendin-4, but not that of PDX-1 or VEGF-A/C. Oligonucleotides anti-miR-7 inhibited the exendin-4-induced proliferation in normal rat cholangiocytes, but did not affect Ngn-3 synthesis. Biliary hyperplasia and collagen deposition induced by DDC or BDL were significantly reduced in Ngn-3(+/-) mice compared to wild-type.

CONCLUSION

Ngn-3-dependent activation of miR-7a is a determinant of cholangiocyte proliferation. These findings indicate that the reacquisition of a molecular profile typical of organ development is essential for the biological response to injury by mature cholangiocytes.

Prolonged administration of secretin to normal rats increases biliary proliferation and secretin-induced ductal secretory activity

BACKGROUND AND AIM

Cholangiocyte proliferation is coordinately regulated by a number of gastrointestinal hormones/peptides, some of which display stimulatory effects and some have inhibitory actions on cholangiocyte proliferation. Enhanced biliary proliferation [for example after bile duct ligation (BDL) and partial hepatectomy] is associated with increased expression of secretin receptor (SR), cystic fibrosis transmembrane conductance regulator (CFTR) and Cl(-)/HCO3 (-) anion exchanger 2 and secretin-stimulated ductal secretion, whereas loss/damage of bile ducts [for example after acute carbon tetrachloride (CCl4) administration] is associated with reduced secretin-stimulated ductal secretory activity. There is growing information regarding the role of gastrointestinal hormones the regulation of biliary growth. For example, while gastrin, somatostatin and serotonin inhibit bile duct hyperplasia of cholestatic rats by downregulation of cAMP signaling, secretin has been shown to stimulate the proliferation of normal mice by activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent signaling. However, no information exists regarding the stimulatory effects of secretin on biliary proliferation of normal rats. Thus, we evaluated the in vivo and in vitro effect of secretin on biliary proliferation, the expression of markers key of ductal secretion and secretin-stimulated ductal secretion.

METHODS

Normal male rats were treated with saline or secretin (2.5 nmoles/kg BW/day by osmotic minipumps for one week). We evaluated: (I) intrahepatic bile duct mass (IBDM) in liver sections and PCNA expression in purified cholangiocytes; (II) SR and CFTR mRNA expression and secretin-stimulated cAMP levels in purified cholangiocytes; and (III) secretin-stimulated bile and bicarbonate secretion in bile fistula rats. In vitro, normal rat intrahepatic cholangiocyte lines (NRIC) were treated with BSA (basal) or secretin (100 nM) for 24 to 72 hours in the absence/presence of a PKA or a MEK inhibitor before evaluating proliferation by MTS assays.

RESULTS

Prolonged administration of secretin to normal rats increased IBDM and PCNA expression in purified cholangiocytes compared to saline-treated normal rats. Also, secretin increased the expression of proteins (SR and CFTR) that are key in the regulating ductal secretion and enhanced secretin-stimulated cAMP levels and bile and bicarbonate secretion. In vitro, secretin increased the proliferation of NRIC, increase that was prevented by PKA and MAPK inhibitors.

CONCLUSIONS

We have demonstrated that secretin stimulates both in vivo and in vitro biliary proliferation and secretin-stimulated ductal secretory activity in normal rats. We suggest that the stimulatory effect of secretin on biliary proliferation and secretion may be important for preventing biliary dysfunction during ductopenic disorders.

Chronic inflammation and cytokines in the tumor microenvironment

Acute inflammation is a response to an alteration induced by a pathogen or a physical or chemical insult, which functions to eliminate the source of the damage and restore homeostasis to the affected tissue. However, chronic inflammation triggers cellular events that can promote malignant transformation of cells and carcinogenesis. Several inflammatory mediators, such as TNF-α, IL-6, TGF-β, and IL-10, have been shown to participate in both the initiation and progression of cancer. In this review, we explore the role of these cytokines in important events of carcinogenesis, such as their capacity to generate reactive oxygen and nitrogen species, their potential mutagenic effect, and their involvement in mechanisms for epithelial mesenchymal transition, angiogenesis, and metastasis. Finally, we will provide an in-depth analysis of the participation of these cytokines in two types of cancer attributable to chronic inflammatory disease: colitis-associated colorectal cancer and cholangiocarcinoma.

Recent advances in the morphological and functional heterogeneity of the biliary epithelium

This review focuses on the recent advances related to the heterogeneity of different-sized bile ducts with regard to the morphological and phenotypical characteristics, and the differential secretory, apoptotic and proliferative responses of small and large cholangiocytes to gastrointestinal hormones/peptides, neuropeptides and toxins. We describe several in vivo and in vitro models used for evaluating biliary heterogeneity. Subsequently, we discuss the heterogeneous proliferative and apoptotic responses of small and large cholangiocytes to liver injury and the mechanisms regulating the differentiation of small into large (more differentiated) cholangiocytes. Following a discussion on the heterogeneity of stem/progenitor cells in the biliary epithelium, we outline the heterogeneity of bile ducts in human cholangiopathies. After a summary section, we discuss the future perspectives that will further advance the field of the functional heterogeneity of the biliary epithelium.

PDX-1/Hes-1 interactions determine cholangiocyte proliferative response to injury in rodents: possible implications for sclerosing cholangitis

BACKGROUND & AIMS

Cholangiocyte proliferation plays a role in the progression of cholangiopathies, in particular in primary sclerosing cholangitis. The mechanisms regulating cholangiocyte proliferation are still undefined. Pancreatic Duodenal Homeobox protein 1 (PDX-1) is expressed by reactive cholangiocytes. In the adult pancreas, PDX-1 regulates the proliferative response to injury of ductal cells. Its effects can be counteracted by Hairy and enhancer of split 1 (Hes-1). We aimed at studying whether PDX-1/Hes-1 interactions regulate cholangiocyte proliferation in response to injury.

METHODS

The effect of the loss of PDX-1 on cholangiocyte proliferation was studied in vitro. In vivo PDX-1-heterozygous (+/-) mice were subjected to either DDC feeding (a model of sclerosing cholangitis) or to bile duct ligation (BDL). PDX-1/Hes-1 interactions on cell proliferation were determined by exposure to All-trans Retinoic Acid (At-RA), an inductor of Hes-1.

RESULTS

In vitro, cholangiocyte proliferation was undetectable in cells pre-treated with PDX-1 siRNA. In vivo, increases in bile duct mass and collagen deposition observed after DDC feeding or BDL were significantly reduced in PDX-1(+/-) mice. Hes-1 expression is reduced in proliferating cholangiocytes; At-RA induced a dose-dependent increase in Hes-1 and a decrease in PDX-1 expression. At-RA neutralized the increases in PDX-1 expression and cell proliferation, both in vitro and in vivo in DDC mice. PDX-1 is overexpressed and Hes-1 downregulated in cholangiocytes isolated from PSC livers.

CONCLUSIONS

Hes-1 downregulation allows PDX-1 to act as a major determinant of cholangiocyte proliferation in response to cholestatic injury. These findings provide novel mechanistic insights into the pathophysiology of cholangiopathies.

Natural history and management of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic inflammatory autoimmune disease that mainly targets the cholangiocytes of the interlobular bile ducts in the liver. It is a rare disease with prevalence of less than one in 2000. Its prevalence in developing countries is increasing presumably because of growth in recognition and knowledge of the disease. PBC is thought to result from a combination of multiple genetic factors and superimposed environmental triggers. The contribution of the genetic predisposition is evidenced by familial clustering. Several risk factors, including exposure to infectious agents and chemical xenobiotics, have been suggested. Common symptoms of the disease are fatigue and pruritus, but most patients are asymptomatic at first presentation. The prognosis of PBC has improved because of early diagnosis and use of ursodeoxycholic acid, the only established medical treatment for this disorder. When administered at adequate doses of 13–15 mg/kg/day, up to two out of three patients with PBC may have a normal life expectancy without additional therapeutic measures. However, some patients do not respond adequately to ursodeoxycholic acid and might need alternative therapeutic approaches.

Hepatic progenitor cells activation, fibrosis, and adipokines production in pediatric nonalcoholic fatty liver disease

Hepatic progenitor cells (HPCs) play a major role in liver repair and regeneration. We evaluated HPC involvement in pediatric nonalcoholic fatty liver disease (pNAFLD). Thirty biopsies of consecutive children and adolescents with untreated NAFLD (19 with nonalcoholic steatohepatitis [NASH] and 11 without NASH) were studied using immunohistochemistry and immunofluorescence. HPCs and HPC-expressing adipokines (e.g., adiponectin, resistin, and glucagon-like peptide 1 [GLP-1]) were counted and correlated with steatosis, inflammation, hepatocyte ballooning, fibrosis, and NAFLD activity score (NAS). The HPC compartment was expanded in pNAFLD, especially in children with NASH, and was independently associated with degree of fibrosis (r = 0.303; P = 0.033). NASH livers were also characterized by increased hepatocyte apoptosis, cell-cycle arrest, and an expanded pool of intermediate hepatocytes. Adiponectin expression in HPCs of pNAFLD patients was down-regulated with respect to the healthy liver, and this expression was inversely correlated with NAS score (r = -0.792; P < 0.001) and steatosis (r = -0.769; P < 0.001). Resistin expression in HPCs increased in pNAFLD and was related to degree of fibrosis (r = 0.432; P < 0.05). GLP-1 was overexpressed in HPCs of pNAFLD patients, and GLP-1 expression was related to degree of steatosis (r = 0.577; P < 0.05) and NAS (r = 0.594; P < 0.01).

CONCLUSIONS

HPC activation is involved in the response of the liver to oxidative stress in pNAFLD and is correlated with fibrosis and the progression toward NASH. HPCs express adiponectin, resistin, and GLP-1, which become available to resident liver cells and are strongly associated with the severity of NAFLD. These results may have important pathophysiological implications in the modulation of hepatic insulin resistance and the progression of liver injury.