Role of endogenous hypergastrinemia in regenerating endocrine pancreas after partial pancreatectomy

Perioperative Drug Treatment in Pancreatic Surgery-A Systematic Review and Meta-Analysis

INTRODUCTION

Pancreatic resections for malignant or benign diseases are associated with major morbidity and changes in physiology. To reduce perioperative complications and enhance recovery, many types of perioperative medical management have been introduced. The aim of this study was to provide an evidence-based overview on the best perioperative drug treatment.

METHODS

The electronic bibliographic databases Medline, Embase, CENTRAL, and Web of Science were systematically searched for randomized controlled trials (RCT) evaluating perioperative drug treatments in pancreatic surgery. The investigated drugs were somatostatin analogues, steroids, pancreatic enzyme replacement therapy (PERT), prokinetic therapy, antidiabetic drugs, and proton pump inhibitors (PPI). Targeted outcomes in each drug category were meta-analyzed.

RESULTS

A total of 49 RCT were included. The analysis of somatostatin analogues showed a significantly lower incidence of postoperative pancreatic fistula (POPF) in the somatostatin group compared to the control group (OR 0.58, 95% CI: 0.45 to 0.74). The comparison of glucocorticoids versus placebo showed significantly less POPF in the glucocorticoid group (OR 0.22, 95% CI: 0.07 to 0.77). There was no significant difference in DGE when erythromycin was compared to placebo (OR 0.33, 95% CI: 0.08 to 1.30). The other investigated drug regimens could only be analyzed qualitatively.

CONCLUSION

This systematic review provides a comprehensive overview on perioperative drug treatment in pancreatic surgery. Some often-prescribed perioperative drug treatments lack high quality evidence and further research is needed.

Current status and perspectives of the future of pancreatic surgery: Establishment of evidence by integration of "art" and "science"

Pancreatic cancer surgery continues to be associated with a high operative morbidity rate, poor long-term survival outcomes, and various challenges in obtaining high-level evidence. Not only is the early postoperative morbidity rate high, but also late morbidity involves lifelong nutritional support for long-term survivors. Due to poor survival outcomes even after curative surgery, pancreatic surgeons have doubts about the role of surgery as the definitive treatment for pancreatic cancer. Additionally, conducting clinical trials to obtain high-level evidence in the field of pancreatic surgery is difficult, and the results have only had a moderate impact on clinical practice due to skepticism regarding their quality. Therefore, quality evidence regarding the extent of resection, mode of approach to dissection, reconstruction methods for pancreatico-enteric anastomosis, determination of resectability, timing of surgery, and the definition of the resection margin is lacking. However, numerous innovative pancreatic surgical procedures have been developed, which may aptly have been called "art" when they were first introduced, regardless of whether they subsequently were supported by scientific evidence. In this review, we provide recent examples of the integration of art and science in the field of pancreatic surgery, which illustrate how the creative ideas of pancreatic surgeons evolved into generally accepted clinical practice. Pancreatic surgeons should be considered "surgical artists," "surgical scientists," and "surgical practitioners." We look forward to more "surgical artists" educating future "surgical artists and scientists" to create a richer "spirit of innovation," leading to a more beautiful integration of art and science in the field of pancreatic surgery.

Gastrin and the Moderate Hypergastrinemias

The antral hormone gastrin potently regulates gastric acid secretion and fundic mucosal growth. Consequently, appropriate gastrin secretion and plasma concentrations are important for the early phases of digestion. This review describes as the first premise the normal biogenesis of gastrin in the antral mucosa, but also mentions the extraantral expression. Subsequently, the molecular nature and concentration levels of gastrin in serum or plasma are overviewed. Third, assays for accurate measurements of plasma or serum concentrations are commented. Finally, the problem of moderate hypergastrinemia due to Helicobacter pylori infections and/or treatment with proton-pump inhibitors (PPI) is discussed. The review concludes that accurate measurement of the true concentrations of bioactive gastrins in plasma is important. Moreover, it suggests that moderate hypergastrinemias are also essential health issues that require serious attention.

Should we still be concerned about the potential side effects of glucagon-like peptide-1 receptor agonists on thyroid C cells?

In recent years, numerous novel anti-diabetic drugs have emerged. Among them, glucagon-like peptide-1 receptor (GLP-1R) agonists developed on the basis of the incretin theory are the most popular and surprising. Thus far, the clinical and experimental efficiency and safety data seem to be good. However, questions about the side effects of GLP-1R agonists, especially on thyroid C cells, still remain. In vivo and in vitro rodent experiments have shown the potential risks of GLP-1R agonists on thyroid C cells. However, the effects of GLP-1R agonists in humans, which have only been studied in experiments using untreated thyroid tissues or C-cell lines, are questionable and differ from that in rodents. C-cell abnormalities are not only dependent on GLP-1R, as many other factors also influence the structure and function of thyroid C cells. Furthermore, there is not enough information from patients with diabetes or tissue samples from subjects treated with GLP-1R agonists and related drugs--especially data obtained during the prandial period or from a long-term study. Therefore, it is important to focus on the possible side effects of GLP-1R agonists on thyroid C cells.

Proton pump inhibitors: impact on glucose metabolism

Diabetes mellitus is a complex chronic disease associated with an absolute insulin deficiency in type 1 diabetes (T1D) and a progressive deterioration of β-cell function in type 2 diabetes (T2D). T2D pathophysiology has numerous defects including incretin deficiency/resistance. Gastrin has demonstrated to be an islet growth factor (like glucagon-like peptide-1, epidermal growth factor, transforming growth factor-α,…) and be able to restore a functional β-cell mass in diabetic animals. This hormone is likely to stimulate insulin secretion during an ordinary protein-rich meal, this is, to have an incretin-like effect. Proton pump inhibitors (PPIs) can raise serum gastrin concentration significantly and therefore, affect to glucose metabolism through promoting β-cell regeneration/expansion and also enhancing insulin secretion. The present paper aims to review studies concerning the effect of PPIs on glucose metabolism. Several research groups have recently explored the potential role of this class of drugs on glycemic control, mainly in T2D. The results show antidiabetic properties for the PPIs with a global glucose-lowering power around 0.6-0.7 % points of HbA1c, but the level of evidence for the available literature is still not high. If these data start to become demonstrated in the ongoing clinical trials, PPIs could become a new antidiabetic agent with a good and safe profile for T2D and even useful for T1D, particularly in the area of islet transplantation to preserve β-cell mass.

Regenerative medicine for insulin deficiency: creation of pancreatic islets and bioartificial pancreas

Recent advances in pancreas organogenesis have greatly improved the understanding of cell lineage from inner cell mass to fully differentiated β-cells. Based upon such knowledge, insulin-producing cells similar to β-cells to a certain extent have been generated from various cell sources including embryonic stem cells (ESCs) and induced pluripotent stem (iPS) cells, although fully differentiated cells comparable to β-cells are not yet available. The bioartificial pancreas is a therapeutic approach to enable allo- and xenotransplantation of islets without immune suppression. Among several types of bioartificial pancreases (BAPs), micro-encapsulated porcine islets are already in use in clinical trials and may, perhaps, replace islet transplantation in the near future. Some types of bioartificial pancreas such as macro-encapsulation are also useful for keeping transplanted cells enclosed in case retrieval is necessary. Therefore, early clinical applications of artificially generated β-like cells, especially those from ESCs or iPS cells, will be considered in combination with retrievable BAPs.

[Morphometric and immunohistochemical patterns of duodenal CCK-cells in rats with portacaval shunts]

INTRODUCTION

End-to-side portacaval shunt (PCS) performed in rats is an appropriate experimental model of chronic liver insufficiency. Functional hepatic injury followed by numerous metabolic and endocrine disorders develops, as well. Due to impaired functional hepatic activity in PCS and to the well known role of the liver in CCK metabolism and elimination, delayed CCK bloodstream elimination may be responsible for increased CCK-A receptor activity. Therefore, we investigated immunohistochemical and morphometric features of duodenal CCK-cells in rats with PCS.

MATERIAL AND METHODS

Male Wistar rats (180 - 250g body weight) were used in this experiment. The animals were divided into two groups: PCS-animals (experimental group (n=27) which underwent an operation) and C - unoperated animals [control group (n=11)].

SURGICAL TECHNIQUE

End-to-side portacaval anastomosis was created using the technique of Lee and Fisher, modified by Bismuth et al. Eight weeks, after the operation, animals were sacrificed. Pancreatic and hepatic weights were measured and samples taken from appropriate segments of the small intestine were used for morphometric and immunohistochemical CCK-cells determination. IMMUNOHISTOCHEMICAL TECHNIQUE: Peroxidase-antiperoxidase (PAP) technique described by Stenberger was applied for detection of intestinal CCK-immunoreactive cells.

RESULTS

Our results indicate that eight weeks after operation liver weight was reduced in animals with PCS compared to control animals (p<0.01). To the contrary, in comparasion with control animals, the pancreatic wight was increased (p<0.01). In the exocrine pancreas of rats with PCS there were lipid droplets and hypertrophy of the acinus cells. The morphometric analysis of CCK-immunoreactive cells in different small intestine segments indicates that in the duodenum of animals with PCS there was a significant cell increase compared to control, unoperated animals.

CONCLUSION

In liver cirrhosis, plasma CCK-8 concentration increases. In PCS, performed in rats, as an experimental model of chronic liver insufficiency, proliferation of CCK-cells in the small intestine leads to pancreatic hypertrophy and hyperplasia.

Aging is associated with decreased pancreatic acinar cell regeneration and phosphatidylinositol 3-kinase/Akt activation

BACKGROUND & AIMS

The effects of aging on pancreatic acinar cell proliferation have not been clearly defined. Phosphatidylinositol 3-kinase (PI3K)-mediated phosphorylation of Akt is a critical step for proliferation of various cell types and insulin secretion from pancreatic endocrine cells; however, its role in acinar cell proliferation is not known. The purpose of this study was to (1) delineate the effects of aging on pancreatic regeneration after partial pancreatectomy (Px) and (2) define the involvement of the PI3K/Akt pathway in pancreatic regeneration.

METHODS

Following partial Px, pancreatic regeneration and activation of the PI3K pathway were compared in young and aged mice. Activation of the PI3K/Akt pathway was evaluated by Akt phosphorylation (pAkt). The role of the PI3K pathway in pancreatic regeneration after partial Px was assessed by effects of a pharmacologic PI3K inhibitor wortmannin or small interfering RNA (siRNA) to the p85alpha regulatory subunit. To confirm further the critical role of the PI3K/Akt pathway in pancreatic acinar cell proliferation, IGF-1-mediated cell proliferation was determined in cultured acinar cells pretreated with wortmannin or p85alpha siRNA.

RESULTS

Pancreatic regeneration and pAkt expression after partial Px were significantly decreased with aging. Treatment with wortmannin or p85alpha siRNA reduced pancreatic regeneration after partial Px. The IGF-1-mediated cell proliferation in vitro was completely blocked by wortmannin or p85alpha siRNA but not by the MEK/ERK inhibitor PD98059.

CONCLUSIONS

PI3K/Akt activation plays a critical role in the regeneration of pancreatic acini after resection. Furthermore, pancreatic regeneration is markedly attenuated in the aged pancreas most likely because of decreased PI3K/Akt activation.

Randomized prospective trial of the effect of induced hypergastrinemia on the prevention of pancreatic atrophy after pancreatoduodenectomy in humans

OBJECTIVE

To investigate whether gastrin has regenerative effect on the pancreas and in particular whether it prevents the atrophy of the distal pancreas after resection of pancreas in humans.

SUMMARY BACKGROUND DATA

Although pancreatic regeneration after resection is well documented in animals, atrophy rather than regeneration of the distal remnant pancreas commonly occurs following pancreatoduodenectomy in humans. Of the many factors involving pancreatic regeneration, gastrin has been shown to have trophic effect on the pancreas in an animal model.

METHODS

Between March 1999 and May 2000, a randomized prospective study was performed in 56 patients who underwent pylorus-preserving pancreatoduodenectomy for periampullary neoplasms. Patients were allocated to either a lansoprazole group or a control group. The lansoprazole members were given oral lansoprazole (30 mg/d) over 12 weeks postoperatively to induce hypergastrinemia. During the study period, 19 patients were excluded for different reasons; in the end a total of 37 patients (lansoprazole, n = 18; control, n = 19) were eligible for study. The volume of the distal pancreas as determined using thin-sectioned spiral CT data, nutritional status, and endocrine (insulin level, glucose tolerance test) and exocrine function (stool elastase) of the pancreas and serum gastrin levels were measured before surgery and 3 months after surgery. The two groups were clinically comparable.

RESULTS

Serum gastrin level was elevated in the lansoprazole group. In this group, the mean volume of the distal pancreas was reduced by 10% after pylorus-preserving pancreatoduodenectomy, whereas severe pancreatic atrophy occurred in the control group. Postoperative insulin and stool elastase levels were higher in the lansoprazole group than in the control group.

CONCLUSIONS

This study is the first prospective randomized trial of induced hypergastrinemia on the regeneration of the pancreas in humans. It may be possible to use induced hypergastrinemia in the treatment or prevention of pancreatic insufficiency following resection or injury.

Studies on hypertrophic effect of 90% partial pancreatectomy on the stomach in rats

INTRODUCTION

Stomach changes after major pancreatectomy (Px) are unclear. We previously reported that 90% Px increased stomach weight in rats similarly to endogenous hypergastrinemia by lansoprazole, a proton-pump inhibitor.

AIM

To investigate the role of endogenous gastrin in gastric hypertrophy after Px.

METHODOLOGY

In male Wistar rats, we compared the wet weight of the stomach and serum gastrin levels between normal (n = 10) or sham-operated controls (n = 10) and 90% partially pancreatectomized rats (n = 7). Then, using Northern blot analysis, we compared gene expression of gastrin, cholecystokinin-B (CCK-B) receptor, and somatostatin in the stomach among normal controls (n = 7), sham-operated rats (n = 7), and 90% partially pancreatectomized rats (n = 8). The samples were obtained on the third and seventh postoperative days (POD).

RESULTS

Wet weight of the stomach was significantly heavier in the Px rats than in the sham-operated controls (3.90 +/- 0.12 mg/g vs 2.63 +/- 0.07mg/g; p< 0.0001) on the 14th POD. Serum gastrin levels were also higher in the Px rats than in controls (161.4 +/- 13.35 pg/mL vs 110.6 +/- 5.67 pg/mL; p< 0.005) on the 14th POD. Gene expression of gastrin in the stomach on the 7th POD was significantly higher in the Px rats than in the sham-operated rats (p < 0.05), and gene expression of CCK-B receptor clearly increased in the Px rats on the 7th POD, when compared with that of controls (p < 0.05). Gastric somatostatin gene expression in both operated groups increased approximately twice as much as in normal controls after operation (p < 0.005). However, on the 7th POD, it returned to control levels only in Px rats and not in sham-operate rats (p < 0.05).

CONCLUSION

Increased gene expression of gastrin and CCK-B receptor suggests that gastrin may act as a trophic factor on the stomach after partial Px. Moreover, the relative decrease in gastric somatostatin gene expression may also influence gastric hypertrophy after Px.

Extragastric effects of gastrin gene knock-out mice

Gastrin is a peptide hormone that regulates both acid secretion and growth of the gastric oxyntic mucosa. Recent studies suggest that gastrin, in both its amidated, and less processed forms (glycine-extended gastrin and progastrin) may also exert biological activity in other organs in the gastrointestinal tract. This article will review the studies performed to date addressing the physiological role of gastrin outside of the gastric mucosa, with particular emphasis on the information gleaned from gastrin-deficient mice. Most of these studies address the potential role for the less processed forms of gastrin in regulating the proliferation of the colonic mucosa and colon cancers. There is also some data to support a potential role for gastrin in the regulation of the pancreas and the kidney, although the effects of gastrin deficiency on the function of these organs in mice have not yet been rigorously studied.

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

It is still unclear which factors regulate pancreatic regeneration and beta-cell neogenesis and which precursor cells are involved. We evaluated the role of intravenously infused gastrin in regenerating pancreas of duct-ligated rats. The ligation of exocrine ducts draining the splenic half of the pancreas resulted in acinoductal transdifferentiation within the ligated part but not in the unligated part. We found that infusion of gastrin from day 7 to 10 postligation resulted in a doubling of the beta-cell mass in the ligated part as measured by morphometry. This increase in insulin-expressing cells was not associated with increased proliferation, hypertrophy, or reduced cell death of the beta-cells. Furthermore, we found an increased percentage of single, extra-insular beta-cells and small beta-cell clusters induced by gastrin infusion. These changes occurred only in the ligated part of the pancreas, where transdifferentiation of the exocrine acinar cells to ductlike cells (metaplasia) had occurred, and was not found in the normal unaffected pancreatic tissue. In conclusion, we demonstrate that administration of gastrin stimulates beta-cell neogenesis and expansion of the beta-cell mass from transdifferentiated exocrine pancreas.

Gastrin as a growth factor in the gastrointestinal tract

The peptide hormone gastrin, released from antral G cells, is known to stimulate the synthesis and release of histamine from ECL cells in the oxyntic mucosa via CCK-2 receptors. The mobilized histamine induces acid secretion by binding to the H(2) receptors located on parietal cells. Recent studies suggest that gastrin, in both its fully amidated and less processed forms (progastrin and glycine-extended gastrin), is also a growth factor for the gastrointestinal tract. In this article, we review the recent evidence (including those from the transgenic and knockout mice) for the trophic targets of both the amidated and less processed forms of gastrin in the gastrointestinal tract, pancreas and liver. It has been established that the major trophic effect of amidated gastrin is for the oxyntic mucosa of stomach, where it causes increased proliferation of gastric stem cells and ECL cells, resulting in increased parietal and ECL cell mass. There is insufficient evidence to support that amidated gastrin is a trophic factor for the rest of gastrointestinal tract, exocrine pancreas and liver. On the other hand, the major trophic target of the less processed gastrin (e.g. glycine-extended gastrin) appears to be the colonic mucosa. There is no evidence to suggest that it is trophic for the stomach. It remains to be examined whether the rest of gastrointestinal tract, pancreas and liver are the trophic targets by glycine-extended gastrin and progastrin.