Gastrin stimulates beta-cell neogenesis and increases islet mass from transdifferentiated but not from normal exocrine pancreas tissue

Association and Mechanisms of Proton Pump Inhibitors Use with Type-2Diabetes Mellitus Incidence in Adults: A Systemic Review andMeta-Analysis

BACKGROUND

Proton pump inhibitors (PPIs) are an extensively prescribed class of anti-ulcer drugs. This systematic review aimed to investigate the association between PPI use and the risk of new-onset diabetes mellitus or type 2 diabetes (T2DM) incidence.

METHODS

A comprehensive literature search was conducted in PubMed, Scopus, Cochrane Library, and ClinicalTrials.gov using the search terms "proton pump inhibitor," "proton pump inhibitors," "PPIs," "diabetes mellitus," and "type 2 diabetes" from inception to February 2023. Statistical analyses were performed using the "Review Manager 5.4" version, and a statistically highly significant P-value <0.05 was set.

RESULTS

This systematic review identified 12 studies (8 cohort, 1 RCT, and 3 case-control) with a total of 12, 64, 816 population, and the median age ranged from ≥18 yrs to ≤ 75 yrs. The pooled relative risk (RR) observations of a random-effects meta-analysis model showed that chronic exposure to PPI use has a significant association with T2DM risk incidence (RR, 2.44; 95% confidence interval, 1.31-4.54; I2 = 99%, P < 0.00001). The systematic review findings of the three case-control studies also supported an association of dose-dependent and chronic use of PPIs with an incidence of T2DM among chronic users.

CONCLUSION

The systematic review concludes that chronic PPI exposure increases the risk of T2DM incidence. The authors recommend the shortest possible duration of PPI use and not prescribing PPIs to high-risk prediabetics and those without a compelling indication for PPI use. Regular education to patients regarding adverse reactions with prolonged use may decrease the risk of adverse effects associated with PPIs. The authors suggest that gut dysbiosis, hypergastrinemia, hypomagnesemia, decreased pancreatic secretions and IGF-1 levels, and PXR activation associated with chronic acid suppression among chronic PPI users and the potency of PPIs might explain the association between abnormal glucose metabolism and T2DM incidence. Finally, the authors recommend further randomized controlled trials to investigate the association between PPIs and the risk of new-onset T2DM incidence.

Association between clinical use of lansoprazole and the risk of type 2 diabetes mellitus: a pharmacoepidemiological cohort study

BACKGROUND

Proton pump inhibitors (PPIs) are common and widely used for gastrointestinal-related disorders. Lansoprazole is one of PPIs with potential benefits of anti-inflammation, reduced oxidative stress, and anti-diabetes. The aims of this study are to determine whether lansoprazole imparts differential risk of type 2 diabetes as compared with other PPIs.

METHODS

A population-based retrospective cohort study was conducted using the National Health Insurance Research Database in Taiwan. Patients who received lansoprazole more than 90 days and without records of use of other PPIs between January 1, 2000 and December 31, 2005 (the exposure period) were considered as the exposed cohort (n = 1668). In comparison, patients who received other PPIs more than 90 days and without use of lansoprazole in the exposure period were treated as the comparison cohort (n = 3336).The primary outcome was the new-onset of type 2 diabetes mellitus (T2DM). The association between use of lansoprazole and the risk of T2DM was determined by hazard ratios (HRs) and 95% confidence intervals (CIs) derived from multivariable Cox proportional hazards models.

RESULTS

The lansoprazole cohort showed a significantly reduced risk of T2DM with an adjusted HR of 0.65 (95% CI 0.56-0.76). Interestingly, the inverse association between use of lansoprazole and risk of T2DM was observed in both genders and in various age groups.

CONCLUSION

The present study findings suggest that lansoprazole was associated with a reduced risk of T2DM compared with other PPIs. Further studies are needed to determine the clinical implications of the present study.

Discovery of once-weekly, peptide-based selective GLP-1 and cholecystokinin 2 receptors co-agonizts

A group of long-acting, peptide-based, and selective GLP-1R/CCK-2R dual agonizts were identified by rational design. Guided by sequence analysis, structural elements of the CCK-2R agonist moiety were engineered into the GLP-1R agonist Xenopus GLP-1, resulting in hybrid peptides with potent GLP-1R/CCK-2R dual activity. Further modifications with fatty acids resulted in novel metabolically stable peptides, among which 3d and 3 h showed potent GLP-1R and CCK-2R activation potencies and comparable stability to semaglutide. In food intake tests, 3d and 3 h also showed a potent reduction in food intake, superior to that of semaglutide. Moreover, the acute hypoglycemic and insulinotropic activities of 3d and 3 h were better than that of semaglutide and ZP3022. Importantly, the limited pica response following 3d and 3 h administration in SD rats preliminarily indicated that the food intake reduction effects of 3d and 3 h are independent of nausea/vomiting. In a 35-day study in db/db mice, every two days administration of 3d and 3 h increased islet areas and numbers, insulin contents, β-cell area, β-cell proliferation, as well as improved glucose tolerance, and decreased HbA1c, to a greater extent than ZP3022 and semaglutide. In a 21-day study in DIO mice, once-weekly administration of 3d and 3 h significantly induced body weight loss, improved glucose tolerance, and normalized lipid metabolism, to a greater extent than semaglutide. The current study showed the antidiabetic and antiobesity potentials of GLP-1R/CCK-2R dual agonizts that warrant further investigation.

A GLP-1/glucagon/CCK-2 receptors tri-agonist provides new therapy for obesity and diabetes

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 receptor (GLP-1R) and glucagon receptor (GCGR) dual agonists have exerted promising therapeutic effects for the treatment of obesity and diabetes in clinical development. Moreover, GLP-1R and cholecystokinin 2 receptor (CCK-2R) dual agonists have been shown to restore pancreas function and improve glycemic control in many preclinical studies. In the present study, we describe for the first time that the beneficial effects of GLP-1R/GCGR and GLP-1R/CCK-2R dual agonists can be integrated into one peptide, resulting in significant anti-diabetes and anti-obesity effectiveness.

EXPERIMENTAL APPROACH

The in vitro potency of a novel GLP-1R/GCGR/CCK-2R tri-agonist (xGLP/GCG/gastrin) against GLP-1R, GCGR, CCK-1R and CCK-2R was determined on cells expressing the corresponding receptors by cAMP accumulation or ERK1/2 phosphorylation assays. The in vivo anti-diabetes and anti-obesity effects of xGLP/GCG/gastrin were studied in both db/db and diet induced obesity (DIO) mice.

KEY RESULTS

xGLP/GCG/gastrin was a potent and selective GLP-1R, GCGR, and CCK-2R tri-agonist. In DIO mice, the metabolic benefits of xGLP-1/GCG/gastrin such as reduction of body weight and hepatic lipid contents were significantly better than those of ZP3022 (GLP-1R/CCK-2R dual agonist) and liraglutide. In the short term study in db/db mice, xGLP/GCG/gastrin treatment exerted considerable effects on increasing islet numbers, islet areas, and insulin content. In the long-term treatment study in db/db mice, xGLP-1/GCG/gastrin displayed a significantly sustained improvement in glucose tolerance and glucose control compared with those of liraglutide, ZP3022, cotadutide (GLP-1R/GCGR dual agonist), and xGLP/GCG-15.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate the therapeutic promise of xGLP-1/GCG/gastrin for obesity and diabetes.

Classical and non-classical islet peptides in the control of β-cell function

The dual role of the pancreas as both an endocrine and exocrine gland is vital for food digestion and control of nutrient metabolism. The exocrine pancreas secretes enzymes into the small intestine aiding digestion of sugars and fats, whereas the endocrine pancreas secretes a cocktail of hormones into the blood, which is responsible for blood glucose control and regulation of carbohydrate, protein and fat metabolism. Classical islet hormones, insulin, glucagon, pancreatic polypeptide and somatostatin, interact in an autocrine and paracrine manner, to fine-tube the islet function and insulin secretion to the needs of the body. Recently pancreatic islets have been reported to express a number of non-classical peptide hormones involved in metabolic signalling, whose major production site was believed to reside outside pancreas, e.g. in the small intestine. We highlight the key non-classical islet peptides, and consider their involvement, together with established islet hormones, in regulation of stimulus-secretion coupling as well as proliferation, survival and transdifferentiation of β-cells. We furthermore focus on the paracrine interaction between classical and non-classical islet hormones in the maintenance of β-cell function. Understanding the functional relationships between these islet peptides might help to develop novel, more efficient treatments for diabetes and related metabolic disorders.

Gastrin producing syngeneic mesenchymal stem cells protect non-obese diabetic mice from type 1 diabetes

Progressive destruction of pancreatic islet β-cells by immune cells is a primary feature of type 1 diabetes (T1D) and therapies that can restore the functional β-cell mass are needed to alleviate disease progression. Here, we report the use of mesenchymal stromal/stem cells (MSCs) for the production and delivery of Gastrin, a peptide hormone that is produced by intestinal cells and foetal islets and can increase β-Cell mass, to promote protection from T1D. A single injection of syngeneic MSCs that were engineered to express Gastrin (Gastrin-MSCs) caused a significant delay in hyperglycaemia in non-obese diabetic (NOD) mice compared to engineered control-MSCs. Similar treatment of early-hyperglycaemic mice caused the restoration of euglycemia for a considerable duration, and these therapeutic effects were associated with the protection of, and/or higher frequencies of, insulin-producing islets and less severe insulitis. While the overall immune cell phenotype was not affected profoundly upon treatment using Gastrin-MSCs or upon in vitro culture, pancreatic lymph node cells from Gastrin-MSC treated mice, upon ex vivo challenge with self-antigen, showed a Th2 and Th17 bias, and diminished the diabetogenic property in NOD-Rag1 deficient mice suggesting a disease protective immune modulation under Gastrin-MSC treatment associated protection from hyperglycaemia. Overall, this study shows the potential of production and delivery of Gastrin in vivo, by MSCs, in protecting insulin-producing β-cells and ameliorating the disease progression in T1D.

Dysregulation of β-Cell Proliferation in Diabetes: Possibilities of Combination Therapy in the Development of a Comprehensive Treatment

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia as a result of insufficient insulin levels and/or impaired function as a result of autoimmune destruction or insulin resistance. While Type 1 DM (T1DM) and Type 2 DM (T2DM) occur through different pathological processes, both result in β-cell destruction and/or dysfunction, which ultimately lead to insufficient β-cell mass to maintain normoglycemia. Therefore, therapeutic agents capable of inducing β-cell proliferation is crucial in treating and reversing diabetes; unfortunately, adult human β-cell proliferation has been shown to be very limited (~0.2% of β-cells/24 h) and poorly responsive to many mitogens. Furthermore, diabetogenic insults result in damage to β cells, making it ever more difficult to induce proliferation. In this review, we discuss β-cell mass/proliferation pathways dysregulated in diabetes and current therapeutic agents studied to induce β-cell proliferation. Furthermore, we discuss possible combination therapies of proliferation agents with immunosuppressants and antioxidative therapy to improve overall long-term outcomes of diabetes.

Effects of Proton Pump Inhibitors on Glycemic Control and Incident Diabetes: A Systematic Review and Meta-analysis

CONTEXT

Whether proton pump inhibitors (PPI) can improve glycemic control among individuals with diabetes or decrease the risk of incident diabetes in the general population is unclear.

OBJECTIVE

To evaluate the impact of PPI therapy on glycemic control among individuals with diabetes and the risk of diabetes among those without diabetes.

RESULTS

PubMed, Embase, Scopus, and ClinicalTrials.gov were searched from inception to November 21, 2020. We included studies comparing glycosylated hemoglobin (HbA1c) or fasting blood glucose (FBG) among individuals with diabetes treated with and without PPI therapy as an add-on to standard therapy. Studies evaluating the risk of incident diabetes among individuals taking PPI were assessed. We performed dual independent review, data extraction, and quality assessment. Weighted mean differences between groups or relative risks were imputed using random-effects models.

RESULTS

Seven studies (n = 342) for glycemic control and 5 studies (n = 244 439) for risk of incident diabetes were included. Compared with standard therapy, add-on PPI was associated with a significant decrease in HbA1c (WMD, -0.36 %; 95% CI, -0.68 to -0.05; P = 0.025) and FBG (WMD, -10.0 mg/dL; 95% CI, -19.4 to -0.6; P = 0.037). PPI use did not reduce the risk of incident diabetes (pooled RR, 1.10; 95% CI, 0.89 to 1.34; P = 0.385).

CONCLUSION

Add-on PPI improved glycemic indices among individuals with diabetes but did not alter the risk of incident diabetes. The effects of PPI on glycemic control should be considered when prescribing antacids to patients with diabetes.

Ghrelin peptide improves glial conditioned medium effects on neuronal differentiation of human adipose mesenchymal stem cells

The influences of ghrelin on neural differentiation of adipose-derived mesenchymal stem cells (ASCs) were investigated in this study. The expression of typical neuronal markers, such as protein gene product 9.5 (PGP9.5) and Microtubule Associated Protein 2 (MAP2), as well as glial Fibrillary Acid Protein (GFAP) as a glial marker was evaluated in ASCs in different conditions. In particular, 2 µM ghrelin was added to control ASCs and to ASCs undergoing neural differentiation. For this purpose, ASCs were cultured in Conditioned Media obtained from Olfactory Ensheathing cells (OEC-CM) or from Schwann cells (SC-CM). Data on marker expression were gathered after 1 and 7 days of culture by fluorescence immunocytochemistry and flow cytometry. Results show that only weak effects were induced by the addition of only ghrelin. Instead, dynamic ghrelin-induced modifications were detected on the increased marker expression elicited by glial conditioned media. In fact, the combination of ghrelin and conditioned media consistently induced a further increase of PGP9.5 and MAP2 expression, especially after 7 days of treatment. The combination of ghrelin with SC-CM produced the most evident effects. Weak or no modifications were found on conditioned medium-induced GFAP increases. Observations on the ghrelin receptor indicate that its expression in control ASCs, virtually unchanged by the addition of only ghrelin, was considerably increased by CM treatment. These increases were enhanced by combining ghrelin and CM treatment, especially at 7 days. Overall, it can be assumed that ghrelin favors a neuronal rather than a glial ASC differentiation.

The entero-insular axis: a journey in the physiopathology of diabetes

Glycemic homeostasis is an essential mechanism for the proper working of an organism. However, balance in blood lipid and protein levels also plays an important role. The discovery of the hormone insulin and the description of its function for glycemic control made fundamental scientific progress in this field. However, since then our view of the problem has been deeply influenced only in terms of glucose and insulin (in an insulin-centric and glucose-centric way). Based on recent scientific discoveries, a fine and sophisticated network of hormonal and metabolic interactions, involving almost every apparatus and tissue of the human body, has been theorized. Efficient metabolic homeostasis is founded on these intricate interactions. Although it is still not fully defined, this complex network can undergo alterations that lead to metabolic disorders such as diabetes mellitus (DM). The endocrine pancreas plays a crucial role in the metabolic balance of an organism, but insulin is just one of the elements involved and each single pancreatic islet hormone is worthy of our concern. Moreover, pancreatic hormones need to be considered in a general view, concerning both their systemic function as direct mediators and as hormones, which, in turn, are regulated by other hormones or other substances. This more complex scenario should be taken into account for a better understanding of the pathophysiology and the therapeutic algorithms of DM. As a consequence, improvements in modern medicine could help to contemplate this new perspective. This review is focused on some aspects of gut-pancreas interaction, aiming to integrate this synergy into a wider context involving other organs and tissues.

Reversal of autoimmunity by mixed chimerism enables reactivation of β cells and transdifferentiation of α cells in diabetic NOD mice

Cure of autoimmune type 1 diabetes (T1D) requires both reversal of autoimmunity and regeneration or resupply of insulin-producing β cells. We have observed that combination therapy with induction of haploidentical mixed chimerism and administration of gastrin and epidermal growth factor (EGF) cures firmly established T1D. The predominant source of β cell regeneration in mice comes from reactivation of dysfunctional insulin^lo β cells and transdifferentiation of α cells. These studies have provided insights into β cell regeneration mechanisms in firmly established autoimmune T1D, in particular, reactivation of the insulin^lo β cells after reversal of autoimmunity by induction of haploidentical mixed chimerism. These studies also provide a preclinical scientific basis for the feasibility of cure of long-standing T1D in humans.

Type 1 diabetes (T1D) results from the autoimmune destruction of β cells, so cure of firmly established T1D requires both reversal of autoimmunity and restoration of β cells. It is known that β cell regeneration in nonautoimmune diabetic mice can come from differentiation of progenitors and/or transdifferentiation of α cells. However, the source of β cell regeneration in autoimmune nonobese diabetic (NOD) mice remains unclear. Here, we show that, after reversal of autoimmunity by induction of haploidentical mixed chimerism, administration of gastrin plus epidermal growth factor augments β cell regeneration and normalizes blood glucose in the firmly established diabetic NOD mice. Using transgenic NOD mice with inducible lineage-tracing markers for insulin-producing β cells, Sox9⁺ ductal progenitors, Nestin⁺ mesenchymal stem cells, and glucagon-producing α cells, we have found that both reactivation of dysfunctional low-level insulin expression (insulin^lo) β cells and neogenesis contribute to the regeneration, with the latter predominantly coming from transdifferentiation of α cells. These results indicate that, after reversal of autoimmunity, reactivation of β cells and transdifferentiation of α cells can provide sufficient new functional β cells to reach euglycemia in firmly established T1D.

Stapled and Xenopus Glucagon-Like Peptide 1 (GLP-1)-Based Dual GLP-1/Gastrin Receptor Agonists with Improved Metabolic Benefits in Rodent Models of Obesity and Diabetes

Diabetes is characterized by pancreas dysfunction and is commonly associated with obesity. Hypoglycemic agents capable of improving β-cell function and reducing body weight therefore are gaining increasing interest. Though glucagon-like peptide 1 receptor (GLP-1R)/cholecystokinin 2 receptor (CCK-2R) dual agonist ZP3022 potently increases β-cell mass and improves glycemic control in diabetic db/db mice, the in vivo half-life (t_1/2) is short, and its body weight reducing activity is limited. Here, we report the discovery of a series of novel GLP-1R/CCK-2R dual agonists. Starting from Xenopus GLP-1, dual cysteine mutation was conducted followed by covalent side chain stapling and albumin binder incorporation, resulting in a stabilized secondary structure, increased agonist potency, and improved stability. Further C-terminal conjugation of gastrin-6 generated GLP-1R/CCK-2R dual agonists, among which 6a and 6b showed higher stability and hypoglycemic activity than liraglutide and ZP3022. Desirably, 6a and 6b exhibited prominent metabolic benefits in diet-induced obesity mice without causing nausea responses and exerted considerable effects on β-cell restoration in db/db mice. These preclinical studies suggest the potential role of GLP-1R/CCK-2R dual agonists as effective agents for treating diabetes and related metabolic disorders.

Short-Term Effect of Hypergastrinemia Following Esomeprazole Treatment On Well-Controlled Type 2 Diabetes Mellitus: A Prospective Study

Objective:

Proton pump inhibitor (PPI) drugs reduce gastric acid secretion and lead to an increase in serum gastrin levels. Many preclinical and some clinical researches have established some positive effects of gastrin or PPI therapy on glucose regulation. The aim of this study was to prospectively investigate the short term effects of esomeprazole on glycaemic control in patients with type 2 diabetes mellitus. In addition, the presence of an association between this effect and gastrin levels was evaluated.

Methods:

Thirty-two subjects with type 2 diabetes mellitus were enrolled and grouped as intervention (n=16) and control (n=16). The participants in the intervention group were prescribed 40 mg of esomeprazole treatment for three months. At the beginning of the study and at the 3rd month, HbA1c level (%) and gastrin levels (pmol/L) of participants were assessed. Then, the groups were compared in terms of their baseline and 3rd month values.

Results:

In the intervention group, the mean gastrin level increased significantly from 34.3±14.4 pmol/L to 87.4±43.6 pmol/L (p<0.001). The mean HbA1c level was similar to the pre-treatment level (6.3±0.7% vs. 6.4±0.9%, p=0.441). There were no statistically significant differences in all parameters of the control group. The majority of individuals were on metformin monotherapy (65.6 %). The subgroup analysis of metformin monotherapy revealed that, in intervention group, there was a significant increase in gastrin levels (39.9±12.6 vs. 95.5±52.5, p=0.026), but the HbA1c levels did not change (6.0±0.4 % vs. 5.9±0.6 %, p=0.288); and in control group, gastrin levels did not change (37.5 ± 26.7 vs. 36.1 ±23.3, p=0.367), but there was an increase in HbA1c levels (6.1 ± 0.50 vs. 6.4 ± 0.60, p=0.01).

Conclusion:

Our study demonstrates that esomeprazole has no extra benefit for the controlled diabetic patient in three months. However, in only the metformin-treated subgroup, esomeprazole may prevent the rise in HbA1c level.

Effect of Proton-Pump Inhibitors on Glucose and Insulin Metabolism on Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Some studies have revealed an improvement in glucose metabolism after proton-pump inhibitors (PPI) therapy; however, this evidence is inconclusive and limited.

OBJECTIVE

The study aimed to examine the effect of PPI on glucose and insulin metabolism in patients with type 2 diabetes through a systematic review and meta-analysis.

METHODS

Only randomized controlled trials evaluating the impact of PPI on glucose or insulin concentrations in type 2 diabetes were searched in PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases. A meta-analysis was conducted using a random-effects model and generic inverse variance method. Sensitivity analysis was performed using the leave-one-out method.

RESULTS

Meta-analysis revealed no significant effect of PPI intervention on fasting glucose (mean difference [MD] -11.42 [95% CI, -29.68 to 6.83], I2 = 80%, p = 0.22), fasting insulin (MD 1.51 [95% CI, -0.36 to 3.37], I2 = 32%, p = 0.11), HOMA-IR (MD -0.16 [-0.98 to 0.65], I2 = 0%, p = 0.70), HOMA-β (MD 19.97 [-21.59 to 61.52], I2 = 71%, p = 0.35), and HbA1c concentrations (MD -0.34 [-0.99 to 0.31], I2 = 89%, p = 0.30).

CONCLUSION

The treatment with PPI, in the short term, had no significant effects on glucose and insulin metabolism in patients with type 2 diabetes.

Multiagonist Unimolecular Peptides for Obesity and Type 2 Diabetes: Current Advances and Future Directions

The ever-increasing prevalence of obesity and Type 2 diabetes has necessitated the development of newer and more effective approaches for achieving efficient glycemic control and weight loss. Conventional treatment methods often result in weight gain, further deteriorating the already impaired metabolic control in people with obesity/Type 2 diabetes. Alleviation of obesity and diabetes achieved after bariatric surgeries highlight the therapeutic importance of gut-brain axis and entails development of more patient-friendly approaches replicating the positive metabolic effects of bariatric surgery. Given the potential involvement of several gut hormones in the success of bariatric surgery, the therapeutic importance of synergistic interaction between these hormones for improved metabolism cannot be ignored. Many unimolecular multiagonist peptides are in preclinical and clinical trials as they maximize the combinatorial metabolic efficacy by concurrent activation of multiple gut hormone receptors. This review summarizes the ongoing developments of multiagonist peptides as novel therapeutic approaches against obesity-diabetes.

Lansoprazole enhances the antidiabetic effect of dapagliflozin in fortified diet-fed streptozotocin-treated diabetic rats

Dapagliflozin (DAPA) is used for treating type 2 diabetes, whereas lansoprazole (LPZ) is used as a traditional antiulcer drug. The present study investigated the possible antidiabetic effects of LPZ on fortified diet-fed streptozotocin (FDF/STZ)-induced insulin-resistant diabetic rats. On the basis of the current results, it can be concluded that LPZ could be used as an add-on drug along with the conventional treatment for T2D as it showed beneficial effects in the current experimental model of insulin resistance.

Characterization of Insulin and Glucagon Genes and Their Producing Endocrine Cells From Pygmy Sperm Whale (Kogia breviceps)

Insulin and glucagon are hormones secreted by pancreatic β and α cells, respectively, which together regulate glucose homeostasis. Dysregulation of insulin or glucagon can result in loss of blood glucose control, characterized by hyperglycemia or hypoglycemia. To better understand the endocrine physiology of cetaceans, we cloned and characterized the insulin and glucagon genes from pygmy sperm whale (Kogia breviceps). We obtained the complete coding sequences of the preproinsulin and preproglucagon genes, which encodes the preproinsulin protein of 110 amino acid (aa) residues and encodes the preproglucagon protein of 179 aa residues, respectively. Sequence comparison and phylogenetic analyses demonstrate that protein structures were similar to other mammalian orthologs. Immunohistochemistry and immunofluorescence staining using insulin, glucagon, and somatostatin antibodies allowed analysis of pygmy sperm whale islet distribution, architecture, and composition. Our results showed the pygmy sperm whale islet was irregularly shaped and randomly distributed throughout the pancreas. The architecture of α, β, and δ cells of the pygmy sperm whale was similar to that of artiodactyls species. This is the first report about insulin and glucagon genes in cetaceans, which provides new information about the structural conservation of the insulin and glucagon genes. Furthermore, offers novel information on the properties of endocrine cells in cetacean for further studies.

Antidiabetic effects and sustained metabolic benefits of sub-chronic co-administration of exendin-4/gastrin and xenin-8-Gln in high fat fed mice

The present study has examined the antidiabetic effects of 21 days co-administration of xenin-8-Gln with the dual-acting fusion peptide, exendin-4/gastrin, as well as persistence of beneficial metabolic benefits, in high fat fed (HFF) mice. Xenin-8-Gln, exendin-4 and gastrin represent compounds that activate receptors of the gut-derived hormones, xenin, glucagon-like peptide-1 (GLP-1) and gastrin, respectively. Twice-daily administration of exendin-4/gastrin, xenin-8-Gln or a combination of both peptides significantly reduced circulating glucose, HbA1c and cumulative energy intake. Combination therapy with xenin-8-Gln and exendin-4/gastrin increased circulating insulin. All HFF mice treated with exendin-4/gastrin presented with body weight similar to lean control mice on day 21. Each treatment improved glucose tolerance and the glucose-lowering actions of glucose dependent insulinotropic polypeptide (GIP), as well as augmenting glucose- and GIP-induced insulin secretion, with benefits being most prominent in the combination group. Administration of exendin-4/gastrin alone, and in combination with xenin-8-Gln, increased pancreatic insulin content and improved the insulin sensitivity index. Pancreatic beta-cell area was significantly increased, and alpha cell area decreased, by all treatments, with the combination group also displaying enhanced overall islet area. Notably, metabolic benefits were generally retained in all groups of HFF mice, and especially in the combination group, following discontinuation of the treatment regimens for 21 days. This was associated with maintenance of increased islet and beta-cell areas. Together, these data confirm the antidiabetic effects of co-activation of GLP-1, gastrin and xenin cell signalling pathways, and highlight the sustainable benefits this type of treatment paradigm can offer in T2DM.

Premises for Cholecystokinin and Gastrin Peptides in Diabetes Therapy

Gastrin and cholecystokinin (CCK) are classical gastrointestinal peptide hormones. Their biogenesis, structures, and intestinal secretory patterns are well-known with the striking feature that their receptor-bound 'active sites' are highly homologous and that this structure is conserved for more than 500 million years during evolution. Consequently, gastrin and CCK are agonists for the same receptor (the CCK2 receptor). But in addition, tyrosyl O-sulphated CCK are also bound to the specific CCK1 receptor. The receptors are widely expressed in the body, including pancreatic islet-cell membranes. Moreover, CCK and gastrin peptides are at various developmental stages and diseases expressed in pancreatic islets; also in human islets. Accordingly, bioactive gastrin and CCK peptides stimulate islet-cell growth as well as insulin and glucagon secretion. In view of their insulinotropic effects, gastrin and CCK peptides have come into focus as drug targets, either alone or in combination with other insulinotropic gut hormones or growth factors. So far, modified CCK and gastrin peptides are being examined as potential drugs for therapy of type 1 as well as type 2 diabetes mellitus.

Disease-Modifying Therapies in Type 1 Diabetes: A Look into the Future of Diabetes Practice

The novel understanding that the presence of multiple islet autoantibodies, indicating islet autoimmunity, inevitably leads to type 1 diabetes mellitus (T1DM) has necessitated the development of a new staging classification system for the condition. Coupled with an improved understanding of the disease course, the realization that T1DM appears to be more heterogeneous than previously thought has led to unique opportunities to develop more targeted therapies that may be applied even before the onset of dysglycemia or symptoms. To date, several therapies have been trialed to delay or halt disease progression in both presymptomatic and clinical T1DM, each demonstrating varying degrees of effectiveness, toxicity, and utility. Key research supports the eventual implementation of immunotherapy in autoimmune diabetes, potentially calling for a paradigm shift among care providers. It will likely be necessary to develop new approaches to trial design and to address potential barriers to progress before an effective treatment for the disease may be achieved.

SIRT1 Activation Promotes β-Cell Regeneration by Activating Endocrine Progenitor Cells via AMPK Signaling-Mediated Fatty Acid Oxidation

Induction of β-cell regeneration from endogenous cells represents a highly promising strategy in stem cell-based treatment for patients with diabetes. Recently, calorie restriction has been shown to affect the regulation of tissue and cell regeneration, including β cells, via metabolic related mechanisms. Here, we examined the potential utility of sirtuin 1 (SIRT1), a calorie restriction mimetic, for stimulating β-cell regeneration and the underlying mechanisms of such stimulation. The present results showed that SIRT1 activation with SRT1720 promoted β-cell regeneration in streptozotocin (STZ)-induced β-cell-deficient neonatal rats. This beneficial effect involved enhanced activation of neurogenin3 (NGN3)-positive endocrine progenitors from pancreatic ductal cells, rather than an expansion of residual β cells. A dynamic expression profile of SIRT1 was observed in endocrine progenitors both during β-cell regeneration in neonatal rats and in the second transition phase of mouse pancreas development. Consistently, SRT1720 treatment upregulated endocrine progenitor differentiation in cultured pancreatic rudiments. Upregulation of NGN3 by SIRT1 activation was through stimulating AMP-activated protein kinase (AMPK) signaling-mediated fatty acid oxidation (FAO) in human pancreatic progenitor cells; AMPK inhibition abolished these effects. The present findings demonstrate a promotional effect of SIRT1 activation on β-cell restoration and endocrine progenitor differentiation that involves regulation of AMPK signaling-mediated FAO. Stem Cells 2019;37:1416-1428.

Reprogramming Cells to Make Insulin

Type 1 diabetes is a disease characterized by the destruction of insulin-secreting β-cells in the pancreas. Individuals are treated for this disease with lifelong insulin replacement. However, one attractive treatment possibility is to reprogram an individual’s endogenous cells to acquire the ability to secrete insulin, essentially replacing destroyed β-cells. Herein, we review the literature on the topic of reprogramming endodermal cells to produce insulin.

Endogenous Pancreatic β Cell Regeneration: A Potential Strategy for the Recovery of β Cell Deficiency in Diabetes

Endogenous pancreatic β cell regeneration is a potential strategy for β cell expansion or neogenesis to treat diabetes. Regeneration can occur through stimulation of existing β cell replication or conversion of other pancreatic cells into β cells. Recently, various strategies and approaches for stimulation of endogenous β cell regeneration have been evaluated, but they were not suitable for clinical application. In this paper, we comprehensively review these strategies, and further discuss various factors involved in regulation of β cell regeneration under physiological or pathological conditions, such as mediators, transcription factors, signaling pathways, and potential pharmaceutical drugs. Furthermore, we discuss possible reasons for the failure of regenerative medicines in clinical trials, and possible strategies for improving β cell regeneration. As β cell heterogeneity and plasticity determines their function and environmental adaptability, we focus on β cell subtype markers and discuss the importance of research evaluating the characteristics of new β cells. In addition, based on the autoimmunologic features of type 1 diabetes, NOD/Lt-SCID-IL2rg null (NSG) mice grafted with human immune cells and β cells are recommended for use in evaluation of antidiabetic regenerative medicines. This review will further understand current advances in endogenous β cell regeneration, and provide potential new strategies for the treatment of diabetes focused on cell therapy.

Emerging hormonal-based combination pharmacotherapies for the treatment of metabolic diseases

Obesity and its comorbidities, such as type 2 diabetes mellitus and cardiovascular disease, constitute growing challenges for public health and economies globally. The available treatment options for these metabolic disorders cannot reverse the disease in most individuals and have not substantially reduced disease prevalence, which underscores the unmet need for more efficacious interventions. Neurobiological resilience to energy homeostatic perturbations, combined with the heterogeneous pathophysiology of human metabolic disorders, has limited the sustainability and efficacy of current pharmacological options. Emerging insights into the molecular origins of eating behaviour, energy expenditure, dyslipidaemia and insulin resistance suggest that coordinated targeting of multiple signalling pathways is probably necessary for sizeable improvements to reverse the progression of these diseases. Accordingly, a broad set of combinatorial approaches targeting feeding circuits, energy expenditure and glucose metabolism in concert are currently being explored and developed. Notably, several classes of peptide-based multi-agonists and peptide-small molecule conjugates with superior preclinical efficacy have emerged and are currently undergoing clinical evaluation. Here, we summarize advances over the past decade in combination pharmacotherapy for the management of obesity and type 2 diabetes mellitus, exclusively focusing on large-molecule formats (notably enteroendocrine peptides and proteins) and discuss the associated therapeutic opportunities and challenges.

The adenosine, adrenergic and opioid pathways in the regulation of insulin secretion, beta cell proliferation and regeneration

Insulin, a key hormone produced by pancreatic beta cells precisely regulates glucose metabolism in vertebrates. In type 1 diabetes, the beta cell mass is destroyed, a process triggered by a combination of environmental and genetic factors. This ultimately results in absolute insulin deficiency and dysregulated glucose metabolism resulting in a number of detrimental pathophysiological effects. The traditional focus of treating type 1 diabetes has been to control blood sugar levels through the administration of exogenous insulin. Newer approaches aim to replace the beta cell mass through pancreatic or islet transplantation. Type 2 diabetes results from a relative insulin deficiency for the prevailing insulin resistance. Treatments are generally aimed at reducing insulin resistance and/or augmenting insulin secretion and the use of insulin itself is often required. It is increasingly being recognized that the beta cell mass is dynamic and increases insulin secretion in response to beta cell mitogens and stress signals to maintain glycemia within a very narrow physiological range. This review critically discusses the role of adrenergic, adenosine and opioid pathways and their interrelationship in insulin secretion, beta cell proliferation and regeneration.

The effect of hypergastrinemia following sleeve gastrectomy and pantoprazole on type 2 diabetes mellitus and beta-cell mass in Goto-Kakizaki rats

PURPOSE

Metabolic surgery alters the secretion of gastrointestinal hormones that influence glycemic control. Elevated gastrin has been suggested to benefit patients with type 2 diabetes and has been reported following sleeve gastrectomy in rats. The present study compares the effect of hypergastrinemia following sleeve gastrectomy with proton-pump inhibitor therapy on glycemic control and beta-cell mass in lean, diabetic animals.

METHODS

Thirty-three diabetic Goto-Kakizaki rats were randomized into pantoprazole + sham operation (GK-PPI), sleeve gastrectomy (GK-SG) and vehicle + sham operation (GK-V). Body weight, glucose parameters, HbA1c, glucagon-like peptide 1, gastrin, insulin and lipids were evaluated for eighteen postoperative weeks. Total beta-cell mass was quantified by optical projection tomography.

RESULTS

After surgery, body weight development was equal among groups (P _g = 0.75). Fasting and stimulated gastrin increased for GK-PPI and GK-SG vs. GK-V (p < 0.05 for all). Fasting blood glucose was decreased for GK-PPI and GK-SG vs. GK-V (p < 0.05 and p = 0.052). HbA1c was lower for GK-SG vs. GK-V at 6 weeks and for GK-PPI vs. GK-V at twelve- and eighteen weeks postoperative (p < 0.05 for all); a borderline difference was observed for GK-SG vs. GK-V at 18 weeks (p = 0.054). Total- and LDL cholesterol was elevated for GK-PPI compared to the other two groups (p < 0.05 for all). Beta-cell mass did not differ among groups (p = 0.35).

CONCLUSIONS

Hypergastrinemia following sleeve gastrectomy and pantoprazole has a similar, modest effect on glycemic control in Goto-Kakizaki rats but does not enhance beta-cell mass after 18 weeks. Hypergastrinemia in the setting of T2DM might be of clinical relevance.

Expression of Gastrin Family Peptides in Pancreatic Islets and Their Role in β-Cell Function and Survival

OBJECTIVES

Modulation of cholecystokinin (CCK) receptors has been shown to influence pancreatic endocrine function.

METHODS

We assessed the impact of the CCKA and CCKB receptor modulators, (pGlu-Gln)-CCK-8 and gastrin-17, respectively, on β-cell secretory function, proliferation and apoptosis and glucose tolerance, and investigating alterations of CCK and gastrin islet expression in diabetes.

RESULTS

Initially, the presence of CCK and gastrin, and expression of their receptors were evidenced in β-cell lines and mouse islets. (pGlu-Gln)-CCK-8 and gastrin-17 stimulated insulin secretion from BRIN-BD11 and 1.1B4 β-cells, associated with no effect on membrane potential or [Ca]i. Only (pGlu-Gln)-CCK-8 possessed insulin secretory actions in isolated islets. In agreement, (pGlu-Gln)-CCK-8 improved glucose disposal and glucose-induced insulin release in mice. In addition, (pGlu-Gln)-CCK-8 evoked clear satiety effects. Interestingly, islet colocalization of CCK with glucagon was elevated in streptozotocin- and hydrocortisone-induced diabetic mice, whereas gastrin coexpression in α cells was reduced. In contrast, gastrin colocalization within β-cells was higher in diabetic mice, while CCK coexpression with insulin was decreased in insulin-deficient mice. (pGlu-Gln)-CCK-8 and gastrin-17 also augmented human and rodent β-cell proliferation and offered protection against streptozotocin-induced β-cell cytotoxicity.

CONCLUSIONS

We highlight the direct involvement of CCKA and CCKB receptors in pancreatic β-cell function and survival.

Role of islet peptides in beta cell regulation and type 2 diabetes therapy

The endocrine pancreas is composed of islets of Langerhans, which secrete a variety of peptide hormones critical for the maintenance of glucose homeostasis. Insulin is the primary regulator of glucose and its secretion from beta-cells is tightly regulated in response to physiological demands. Direct cell-cell communication within islets is essential for glucose-induced insulin secretion. Emerging data suggest that islet connectivity is also important in the regulating the release of other islet hormones including glucagon and somatostatin. Autocrine and paracrine signals exerted by secreted peptides within the islet also play a key role. A great deal of attention has focused on classical islet peptides, namely insulin, glucagon and somatostatin. Recently, it has become clear that islets also synthesise and secrete a range of non-classical peptides, which regulate beta-cell function and insulin release. The current review summarises the roles of islet cell connectivity and islet peptide-driven autocrine and paracrine signalling in beta-cell function and survival. The potential to harness the paracrine effects of non-classical islet peptides for the treatment of type 2 diabetes is also briefly discussed.

Pancreatic β Cell Regeneration as a Possible Therapy for Diabetes

Diabetes is the result of having inadequate supply of functional insulin-producing β cells. Two possible approaches for replenishing the β cells are: (1) replacement by transplanting cadaveric islets or β cells derived from human embryonic stem cells/induced pluripotent stem cells and (2) induction of endogenous regeneration. This review focuses on endogenous regeneration, which can follow two pathways: enhanced replication of existing β cells and formation of new β cells from cells not expressing insulin, either by conversion from a differentiated cell type (transdifferentiation) or differentiation from progenitors (neogenesis). Exciting progress on both pathways suggest that regeneration may have therapeutic promise.

Regenerative medicine and cell-based approaches to restore pancreatic function

The pancreas is a complex organ with exocrine and endocrine components. Many pathologies impair exocrine function, including chronic pancreatitis, cystic fibrosis and pancreatic ductal adenocarcinoma. Conversely, when the endocrine pancreas fails to secrete sufficient insulin, patients develop diabetes mellitus. Pathology in either the endocrine or exocrine pancreas results in devastating economic and personal consequences. The current standard therapy for treating patients with type 1 diabetes mellitus is daily exogenous insulin injections, but cell sources of insulin provide superior glycaemic regulation and research is now focused on the goal of regenerating or replacing β cells. Stem-cell-based models might be useful to study exocrine pancreatic disorders, and mesenchymal stem cells or secreted factors might delay disease progression. Although the standards that bioengineered cells must meet before being considered as a viable therapy are not yet established, any potential therapy must be acceptably safe and functionally superior to current therapies. Here, we describe progress and challenges in cell-based methods to restore pancreatic function, with a focus on optimizing the site for cell delivery and decreasing requirements for immunosuppression through encapsulation. We also discuss the tools and strategies being used to generate exocrine pancreas and insulin-producing β-cell surrogates in situ and highlight obstacles to clinical application.

Modulation of Specific Beta Cell Gene (Re)Expression during In Vitro Expansion of Human Pancreatic Islet Cells

The need for transplantable beta cells with a stable phenotype has given rise to several strategies including the expansion of existing pancreatic islets and/or growth of new ones. In vitro studies of beta cell proliferation on extracellular matrices plus growth factors have highlighted a possible cell expansion technique; however, the technique was accompanied with loss of insulin secretion. Herein we showed that human islet cell proliferation was marked by a decreased expression of specific differentiation markers, particularly insulin, insulin promoting factor-1 (IPF-1), and glucokinase. After a 6-day expansion period, we tried to reexpress the beta cell differentiation markers with compounds known for their differentiation and/or insulin-secreting properties. Sodium butyrate was a potent factor of IPF-1, insulin, and glucokinase gene reexpression; it also clearly induced secretion of gastrin, a known neogenic factor. Other compounds, namely TGF-β, calcitriol, GLP-1, and activin A, efficiently enhanced the glucose sensor machinery, particularly Glut-1 and glucokinase, thus triggering glucose responsiveness. Our results indicate that specific beta cell gene expression may be induced after expansion and dedifferentiation. This rekindles interest in human beta cell expansion. The possible stabilization of specialized genes needed by beta cells to fulfill their role as nutrient sensors and metabolic regulators may also be of interest to ensure graft maintenance and efficiency.

The Impact of Gastric Atrophy on the Incidence of Diabetes

Gastric atrophy results in lower plasma ghrelin, higher gastrin secretion, a change in gut microbiota, and altered dietary nutrient absorption, which may be associated with the incidence of diabetes. Helicobacter pylori (H. pylori) infection is a major cause of gastric atrophy and is associated with diabetes in some reports. Since there is no study which investigates the impact of gastric atrophy on diabetes, we conduct a prospective cohort study to examine the relationship between H. pylori infection, gastric atrophy, and incident diabetes. In this study, subjects with gastric atrophy had a lower risk of incident diabetes, compared to those without gastric atrophy. The extent of gastric atrophy, measured by serum pepsinogen (PG) I/II ratio, was correlated with age, H. pylori IgG titer, HOMA2-IR, and HOMA2%B. When gastric atrophy is more extensive, presented as a lower serum PG I/II ratio, the risk of incident diabetes is lower. On the other hand, there was no significant association between H. pylori infection and the incidence of diabetes. In conclusion, the presence and the extent of gastric atrophy, but not H. pylori infection, are associated with incident diabetes. Further studies are needed to investigate the detailed mechanisms and the potential applications of the findings to guide diabetes screening and treatment strategies.

Effect of moderate and high intensity chronic exercise on the pancreatic islet morphometry in healthy rats: BDNF receptor participation

The function and morphology of β-cells is largely dependent on insulin demand. As β-cells cover a bigger cell proportion in pancreas islets, changes of insulin producer cells affect the whole pancreatic islet morphology. Growth factors as the neurotrophins regulate the pancreas physiology, besides; physical exercise increases insulin sensitivity, and further modifies brain derived neurotrophic factor (BDNF) concentration in plasma. The aim of this study was to investigate the effects of chronic exercise (running in a treadmill for 8 weeks) intensity on pancreatic islet morphometry in healthy state. The BDNF receptor effect on the pancreatic islet morphometry was also evaluated. Adult male Wistar rats were divided in 6 groups: Control (C); moderate intensity training (MIT); high intensity training (HIT) did not treat with BDNF receptor inhibitor (K252a), and C, MIT and HIT treated with K252a. The results shown that chronic exercise induces β-cells hypertrophy without BDNF receptor participation. On the other hand, the moderate exercise increases the number of β cells per islet; the last effect does not require TrkB participation. In sedentary conditions, the K252a treatment reduced the β-cell density. Exercise intensity has differential effects on pancreas islet morphometry in healthy model; furthermore, BDNF receptor plays a role to maintain the amount of β-cells in sedentary state.

Impact of proton pump inhibitor treatment on pancreatic beta-cell area and beta-cell proliferation in humans

INTRODUCTION

Gastrin has been shown to promote beta-cell proliferation in rodents, but its effects in adult humans are largely unclear. Proton pump inhibitors (PPIs) lead to endogenous hypergastrinaemia, and improved glucose control during PPI therapy has been reported in patients with diabetes. Therefore, we addressed whether PPI treatment is associated with improved glucose homoeostasis, islet cell hyperplasia or increased new beta-cell formation in humans.

PATIENTS AND METHODS

Pancreatic tissue specimens from 60 patients with and 33 patients without previous PPI therapy were examined. The group was subdivided into patients without diabetes (n = 27), pre-diabetic patients (n = 31) and patients with diabetes (n = 35).

RESULTS

Fasting glucose and HbA1c levels were not different between patients with and without PPI therapy (P = 0.34 and P = 0.30 respectively). Beta-cell area was higher in patients without diabetes than in patients with pre-diabetes or diabetes (1.33 ± 0.12%, 1.05 ± 0.09% and 0.66 ± 0.07% respectively; P < 0.0001). There was no difference in beta-cell area between patients with and without PPI treatment (1.05 ± 0.08% vs 0.87 ± 0.08%, respectively; P = 0.16). Beta-cell replication was rare and not different between patients with and without PPI therapy (P = 0.20). PPI treatment was not associated with increased duct-cell replication (P = 0.18), insulin expression in ducts (P = 0.28) or beta-cell size (P = 0.63).

CONCLUSIONS

These results suggest that in adult humans, chronic PPI treatment does not enhance beta-cell mass or beta-cell function to a relevant extent.

β-Cell dedifferentiation, reduced duct cell plasticity, and impaired β-cell mass regeneration in middle-aged rats

Limitations in β-cell regeneration potential in middle-aged animals could contribute to the increased risk to develop diabetes associated with aging. We investigated β-cell regeneration of middle-aged Wistar rats in response to two different regenerative stimuli: partial pancreatectomy (Px + V) and gastrin administration (Px + G). Pancreatic remnants were analyzed 3 and 14 days after surgery. β-Cell mass increased in young animals after Px and was further increased after gastrin treatment. In contrast, β-cell mass did not change after Px or after gastrin treatment in middle-aged rats. β-Cell replication and individual β-cell size were similarly increased after Px in young and middle-aged animals, and β-cell apoptosis was not modified. Nuclear immunolocalization of neurog3 or nkx6.1 in regenerative duct cells, markers of duct cell plasticity, was increased in young but not in middle-aged Px rats. The pancreatic progenitor-associated transcription factors neurog3 and sox9 were upregulated in islet β-cells of middle-aged rats and further increased after Px. The percentage of chromogranin A+/hormone islet cells was significantly increased in the pancreases of middle-aged Px rats. In summary, the potential for compensatory β-cell hyperplasia and hypertrophy was retained in middle-aged rats, but β-cell dedifferentiation and impaired duct cell plasticity limited β-cell regeneration.

The use of proton pump inhibitors decreases the risk of diabetes mellitus in patients with upper gastrointestinal disease: A population-based retrospective cohort study

OBJECTIVES

The aim of this study was to investigate the effects of proton pump inhibitors (PPIs) on the risk of diabetes mellitus (DM) among patients with upper gastrointestinal disease (UGID).

METHODS

This was a retrospective cohort study with a follow-up period of 5 years. We identified 388,098 patients who were diagnosed with UGID between 2000 and 2006 from the Longitudinal Health Insurance Database of the Taiwan National Health Insurance program. We used Cox proportional hazard ratio (HR) to compare the risk of DM between UGID patients received PPIs and those did not receive PPIs. HRs were adjusted for possible confounders, including age, sex, hypertension, gout and/or hyperuricemia, coronary artery disease, stroke, pancreatitis, hyperlipidemia, obesity, H2-blocker use, and clozapine or olanzapine use. The dose-related effects of PPIs on the risk of DM were evaluated according to the defined daily dose (DDD).

RESULTS

The adjusted HR was 0.80 (95% CI, 0.73-0.88) for the study group (UGID patients with PPIs) compared with comparison group I (UGID patients without PPIs). Among patients who used PPIs, those older than 60 years of age had a lower risk of DM (HR, 0.73; 95% CI, 0.63-0.83) than those younger than 40 years. Additionally, the effect of PPIs was significantly dose-dependent (P for trend <0.001). Patients with UGID who received >540 DDDs of PPIs exhibited the greatest reduction in the risk of DM.

CONCLUSIONS

Our results demonstrated a decreased risk of DM in UGID patients who used PPIs; the risk appeared to be significantly dose-dependent.

Pancreatic β Cell Mass Death

Type two diabetes (T2D) is a challenging metabolic disorder for which a cure has not yet been found. Its etiology is associated with several phenomena, including significant loss of insulin-producing, beta cell (β cell) mass via progressive programmed cell death and disrupted cellular autophagy. In diabetes, the etiology of β cell death and the role of mitochondria are complex and involve several layers of mechanisms. Understanding the dynamics of those mechanisms could permit researchers to develop an intervention for the progressive loss of β cells. Currently, diabetes research has shifted toward rejuvenation and plasticity technology and away from the simplified approach of hormonal compensation. Diabetes research is currently challenged by questions such as how to enhance cell survival, decrease apoptosis and replenish β cell mass in diabetic patients. In this review, we discuss evidence that β cell development and mass formation are guided by specific signaling systems, particularly hormones, transcription factors, and growth factors, all of which could be manipulated to enhance mass growth. There is also strong evidence that β cells are dynamically active cells, which, under specific conditions such as obesity, can increase in size and subsequently increase insulin secretion. In certain cases of aggressive or advanced forms of T2D, β cells become markedly impaired, and the only alternatives for maintaining glucose homeostasis are through partial or complete cell grafting (the Edmonton protocol). In these cases, the harvesting of an enriched population of viable β cells is required for transplantation. This task necessitates a deep understanding of the pharmacological agents that affect β cell survival, mass, and function. The aim of this review is to initiate discussion about the important signals in pancreatic β cell development and mass formation and to highlight the process by which cell death occurs in diabetes. This review also examines the attempts that have been made to recover or increase cell mass in diabetic patients by using various pharmacological agents.

Pancreatic regulation of glucose homeostasis

In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.

Regenerating gene (REG) product and its potential clinical usage

INTRODUCTION

The regenerating gene (Reg) was identified in regenerating islets and its related genes were revealed to constitute the Reg gene family. Reg family proteins act as growth factors for several cells. Recently, autoimmunity against the Reg family proteins has been reported in several diseases. In addition, the Reg family genes were found to be expressed in a large number of cancers and to influence prognosis.

AREAS COVERED

The historical background and current view of the structure, function, and expression of Reg family genes/proteins and their physiological/pathological significance in several diseases are described. Based on the findings, the diagnostic/therapeutic potential of Reg family genes/proteins is also discussed.

EXPERT OPINION

Autoimmunity against Reg family proteins may be a new diagnostic marker and/or therapeutic target for immune-mediated diseases. Treatment aimed at the expansion of the β-cell mass by the Reg genes/proteins, combined with the abrogation of autoimmunity, constitutes a potential approach for the treatment of diabetes. Conversely, some cancer cells have gained the ability to overexpress the Reg genes/proteins, thereby enhancing their proliferative capacities, resulting in these cells having a considerable growth advantage. Thus, the Reg genes/proteins are expected to be a new prognostic marker in cancer and/or a future therapeutic target.

Emerging opportunities for the treatment of metabolic diseases: Glucagon-like peptide-1 based multi-agonists

Obesity is a pathogenic gateway to the metabolic syndrome and the complications thereof, thus interventions aimed at preventing or reversing the metabolic derangements underlying obesity hold great therapeutic promise. However, the complexity of energy balance regulation, combined with the heterologous pathophysiology of human obesity, renders effective medicinal intervention very difficult. Indeed, the search for the silver bullet in anti-obesity medicines has been laden with drugs of underwhelming efficacy and unacceptable side effects. This can partly be the consequence that many of these drug interventions have been historically directed at single molecular targets. New multi-molecular combination therapies have shown promising clinical outcomes in terms of weight loss, yet multi-functional single molecules may offer even more advantages than adjunctive co-treatments. Single molecules with integrated activities derived from multiple hormones involved in the physiological control of metabolism have emerged as one of the more promising candidates for reversing obesity. The inclusion of glucagon-like peptide-1 (GLP-1) as one of the constituents is a unifying factor amongst the majority of these unimolecular multi-agonists. The scope of this review is to summarize the current preclinical and clinical landscape of GLP-1-based therapies, focusing on combinatorial therapies with a particular emphasis on single molecule compounds displaying multi-agonist properties.

Mapping Mammalian Cell-type-specific Transcriptional Regulatory Networks Using KD-CAGE and ChIP-seq Data in the TC-YIK Cell Line

Mammals are composed of hundreds of different cell types with specialized functions. Each of these cellular phenotypes are controlled by different combinations of transcription factors. Using a human non islet cell insulinoma cell line (TC-YIK) which expresses insulin and the majority of known pancreatic beta cell specific genes as an example, we describe a general approach to identify key cell-type-specific transcription factors (TFs) and their direct and indirect targets. By ranking all human TFs by their level of enriched expression in TC-YIK relative to a broad collection of samples (FANTOM5), we confirmed known key regulators of pancreatic function and development. Systematic siRNA mediated perturbation of these TFs followed by qRT-PCR revealed their interconnections with NEUROD1 at the top of the regulation hierarchy and its depletion drastically reducing insulin levels. For 15 of the TF knock-downs (KD), we then used Cap Analysis of Gene Expression (CAGE) to identify thousands of their targets genome-wide (KD-CAGE). The data confirm NEUROD1 as a key positive regulator in the transcriptional regulatory network (TRN), and ISL1, and PROX1 as antagonists. As a complimentary approach we used ChIP-seq on four of these factors to identify NEUROD1, LMX1A, PAX6, and RFX6 binding sites in the human genome. Examining the overlap between genes perturbed in the KD-CAGE experiments and genes with a ChIP-seq peak within 50 kb of their promoter, we identified direct transcriptional targets of these TFs. Integration of KD-CAGE and ChIP-seq data shows that both NEUROD1 and LMX1A work as the main transcriptional activators. In the core TRN (i.e., TF-TF only), NEUROD1 directly transcriptionally activates the pancreatic TFs HSF4, INSM1, MLXIPL, MYT1, NKX6-3, ONECUT2, PAX4, PROX1, RFX6, ST18, DACH1, and SHOX2, while LMX1A directly transcriptionally activates DACH1, SHOX2, PAX6, and PDX1. Analysis of these complementary datasets suggests the need for caution in interpreting ChIP-seq datasets. (1) A large fraction of binding sites are at distal enhancer sites and cannot be directly associated to their targets, without chromatin conformation data. (2) Many peaks may be non-functional: even when there is a peak at a promoter, the expression of the gene may not be affected in the matching perturbation experiment.

Activation of GLP-1 and gastrin signalling induces in vivo reprogramming of pancreatic exocrine cells into beta cells in mice

AIMS/HYPOTHESIS

Lineage conversion of non-beta cells into insulin-producing cells has been proposed as a therapy for the cure of diabetes. Glucagon-like peptide-1 (GLP-1) and its derivatives can induce beta cell neogenesis in vitro and beta cell mass expansion in vivo, but GLP-1 signalling has not been shown to regulate cell fate decisions in vivo. We therefore tested the impact of GLP-1 receptor (GLP1R) expression on beta cell differentiation in vivo.

METHODS

Mice overexpressing GLP1R in pancreatic exocrine cells were generated by Cre-mediated recombination in sex-determining region Y-box 9 (SOX9)-expressing cells and then treated with exendin-4 and/or gastrin. Histological analysis was performed to detect cellular reprogramming from the exocrine lineage into insulin-producing cells.

RESULTS

Whereas no newly generated beta cells were detected in the mice treated with exendin-4 alone, treatment with gastrin only induced the conversion of exocrine cells into insulin-producing cells. Furthermore, the overexpression of GLP1R, together with gastrin and exendin-4, synergistically promoted beta cell neogenesis accompanied by the formation of islet-like clusters. These newly generated beta cells expressed beta cell specific transcription factors, such as pancreatic and duodenal homeobox 1 (PDX1), NK6 homeobox 1 (NKX6.1) and musculoaponeurotic fibrosarcoma oncogene family A (MafA). These mice showed no histological evidence of pancreatitis or pancreatic dysplasia in their acini and had normal plasma amylase levels.

CONCLUSIONS/INTERPRETATION

Activation of GLP-1 and gastrin signalling induces beta cell neogenesis in the exocrine lineage without any deleterious pancreatic changes, which may lead to a potential therapy to cure diabetes by generating surrogate beta cells.

Combination Therapy Reverses Hyperglycemia in NOD Mice With Established Type 1 Diabetes

An increasing number of therapies have proven effective at reversing hyperglycemia in the nonobese diabetic (NOD) mouse model of type 1 diabetes (T1D), yet situations of successful translation to human T1D are limited. This may be partly due to evaluating the effect of treating immediately at diagnosis in mice, which may not be reflective of the advanced disease state in humans at disease onset. In this study, we treated NOD mice with new-onset as well as established disease using various combinations of four drugs: antithymocyte globulin (ATG), granulocyte-colony stimulating factor (G-CSF), a dipeptidyl peptidase IV inhibitor (DPP-4i), and a proton pump inhibitor (PPI). Therapy with all four drugs induced remission in 83% of new-onset mice and, remarkably, in 50% of NOD mice with established disease. Also noteworthy, disease remission occurred irrespective of initial blood glucose values and mechanistically was characterized by enhanced immunoregulation involving alterations in CD4+ T cells, CD8+ T cells, and natural killer cells. This combination therapy also allowed for effective treatment at reduced drug doses (compared with effective monotherapy), thereby minimizing potential adverse effects while retaining efficacy. This combination of approved drugs demonstrates a novel ability to reverse T1D, thereby warranting translational consideration.

Renoprotective effect of lansoprazole in streptozotocin-induced diabetic nephropathy in wistar rats

Proton pump inhibitors (PPIs) have exhibited glucose lowering action in animal models of diabetes; however, their potential in diabetes-related complications has not yet been evaluated. Hence, the present study has been undertaken to investigate the renoprotective potential of lansoprazole in streptozotocin-induced diabetic nephropathy in wistar rats. Diabetic nephropathy was induced with a single injection of streptozotocin (STZ, 45 mg/kg, i.p.). Lansoprazole (40 mg/kg; 80 mg/kg, p.o.; 4 weeks) was administered to diabetic rats after 4 weeks of STZ treatment. A battery of biochemical tests such as serum glucose, glycated hemoglobin, blood urea nitrogen (BUN), serum creatinine, albumin, and kidney weight/body weight (%) ratio were performed to evaluate the renal functions. Oxidative stress was determined by estimating renal thiobarbituric acid reactive species (TBARS) and reduced glutathione (GSH) levels. Lipid profile was assessed by determining serum cholesterol (TC), triglyceride (TG), and high-density lipoprotein (HDL). The STZ-treated rats demonstrated deleterious alterations in kidney functions, enhanced oxidative stress, and disturbed lipid profile. Administration of lansoprazole to diabetic rats significantly reduced serum glucose, glycated hemoglobin, BUN, creatinine, albumin levels, and oxidative stress. Serum lipids like TC and TG were decreased, and HDL was enhanced in lansoprazole-treated STZ rats. The findings of our study indicate that renoprotective effects of lansoprazole may be attributed to its glucose-lowering, lipid-lowering, and antioxidative potential.