Effect of gastrin on liver regeneration after partial hepatectomy in rats

Molecular Pathways Governing the Termination of Liver Regeneration

The liver has the unique capacity to regenerate, and up to 70% of the liver can be removed without detrimental consequences to the organism. Liver regeneration is a complex process involving multiple signaling networks and organs. Liver regeneration proceeds through three phases: the initiation phase, the growth phase, and the termination phase. Termination of liver regeneration occurs when the liver reaches a liver-to-body weight that is required for homeostasis, the so-called "hepatostat." The initiation and growth phases have been the subject of many studies. The molecular pathways that govern the termination phase, however, remain to be fully elucidated. This review summarizes the pathways and molecules that signal the cessation of liver regrowth after partial hepatectomy and answers the question, "What factors drive the hepatostat?" SIGNIFICANCE STATEMENT: Unraveling the pathways underlying the cessation of liver regeneration enables the identification of druggable targets that will allow us to gain pharmacological control over liver regeneration. For these purposes, it would be useful to understand why the regenerative capacity of the liver is hampered under certain pathological circumstances so as to artificially modulate the regenerative processes (e.g., by blocking the cessation pathways) to improve clinical outcomes and safeguard the patient's life.

Microalgae-Sustainable Source for Alternative Proteins and Functional Ingredients Promoting Gut and Liver Health

Dietary proteins derived from animal sources, although containing well-balanced profiles of essential amino acids, have considerable environmental and adverse health effects associated with the intake of some animal protein-based products. Consuming foods based on animal proteins carries a higher risk of developing non-communicable diseases such as cancer, heart disease, non-alcoholic fatty liver disease (NAFLD), and inflammatory bowel disease (IBD). Moreover, dietary protein consumption is increasing due to population growth, posing a supply challenge. There is, therefore, growing interest in discovering novel alternative protein sources. In this context, microalgae have been recognized as strategic crops that can provide a sustainable source of protein. Compared to conventional high-protein crops, using microalgal biomass for protein production presents several advantages in food and feed in terms of productivity, sustainability, and nutritional value. Moreover, microalgae positively impact the environment by not exploiting land or causing water pollution. Many studies have revealed the potential of microalgae as an alternative protein source with the added value of positive effects on human health due to their anti-inflammatory, antioxidant, and anti-cancer properties. The main emphasis of this review is on the potential health-promoting applications of microalgae-based proteins, peptides, and bioactive substances for IBD and NAFLD.

Cancer Risk After Pernicious Anemia in the US Elderly Population

BACKGROUND & AIMS

Pernicious anemia, a result of autoimmune gastritis, is the most common cause of vitamin B12 deficiency, affecting 2% to 5% of the elderly population. Treatment with vitamin B12 cures the anemia, but not the gastritis. Findings from small studies have indicated that patients with pernicious anemia could have an increased risk of cancer.

METHODS

We performed a population-based, case-control study of individuals in the Surveillance, Epidemiology, and End Results-Medicare database, comparing 1,138,390 cancer cases (age, 66-99 y) with 100,000 matched individuals without cancer (controls). Individuals with pernicious anemia were identified based on their medical claims within the year before selection for the study. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression, and models were adjusted for sex, age, and calendar year of diagnosis and selection.

RESULTS

Compared with controls, we found individuals with pernicious anemia to be at increased risk for noncardia gastric adenocarcinoma (OR, 2.18; 95% CI, 1.94-2.45) and gastric carcinoid tumors (OR, 11.43; 95% CI, 8.90-14.69). In addition, people with pernicious anemia have an increased risk of developing tonsilar cancer (OR, 2.00; 95% CI, 1.40-2.85), hypopharyngeal cancer (OR, 1.92; 95% CI, 1.35-2.73), esophageal squamous cell carcinoma (OR, 2.12; 95% CI, 1.76-2.55), small intestinal cancer (OR, 1.63; 95% CI, 1.32-2.02), liver cancer (OR, 1.49; 95% CI, 1.28- 1.73), myeloma (OR, 1.55; 95% CI, 1.37-1.75), acute myeloid leukemia (OR, 1.68; 95% CI, 1.46-1.93), and myelodysplastic syndrome (OR, 2.87; 95% CI, 2.53-3.26). People with pernicious anemia have a lower risk of rectal cancer than the general population (OR, 0.82; 95% CI, 0.74- 0.92).

CONCLUSIONS

In a population-based, case-control study of individuals in the Surveillance, Epidemiology, and End Results-Medicare database, we found individuals with pernicious anemia to have significantly increased risks of gastric carcinoid tumors, adenocarcinomas, and other cancers located throughout the body.

Gastrin is not required for liver regeneration

BACKGROUND

Although several growth factors are known to be essential for liver regeneration, the role of gastrin remains controversial.

METHODS

Liver regeneration was examined in wild-type (WT) and gastrin-deficient (gastrin KO) mice at days 2 and 10 after partial (40%) hepatectomy by measurement of liver weight. Hepatocyte proliferation and circulating gastrin concentrations were measured at the same time points by immunohistochemistry and radioimmunoassay, respectively.

RESULTS

There was no significant difference in the rate of liver regeneration between gastrin KO and WT mice. Hepatocyte proliferation in both groups was increased at day 2 but had returned to baseline values by day 10. At day 2, hepatocyte proliferation in the gastrin KO mice was significantly higher than in WT animals, whereas at day 10, proliferation was significantly greater in the WT mice. The circulating gastrin concentration in the WT mice was significantly lower at day 10 than in unoperated WT animals.

CONCLUSION

This study suggests that gastrin is not essential for liver regeneration after partial hepatectomy.

Efeito do omeprazol e do pantoprazol sobre a regeneração hepática após hepatectomia parcial em ratos

OBJETIVO: Avaliar os efeitos do omeprazol e do pantoprazol sobre a regeneração hepática após hepatectomia parcial. MÉTODOS: Cinqüenta e oito ratos Wistar machos foram divididos em 4 grupos: Grupo SHAM, Grupo HP, Grupo PANTO e Grupo OMEP. Eles foram submetidos a hepatectomia parcial de 67% (Grupos HP, PANTO e OMEP) ou laparotomia (Grupo SHAM). Os fígados foram removidos 32 e 56 horas após a operação. Depois, os animais foram sacrificados. Em todos os grupos, as substâncias (solução salina, omeprazol e pantoprazol) foram aplicadas diariamente a partir do momento em que foram operados até o sacrifício. RESULTADOS: O índice de mitose no Grupo SHAM não foi significativo. Trinta e duas horas após a hepatectomia, a contagem de mitoses foi de 1,2 ± 1,09 para o Grupo HP, 1,2 ± 1,6 para o Grupo OMEP e 2,6 ± 3,2 para o Grupo PANTO. Na análise após 56 horas, os valores foram 1,6 ± 0,89 para o HP, 2 ± 1,8 para o OMEP e 2,6 ± 0,54 para o PANTO. Esses resultados não foram estatisticamente significativos. CONCLUSÃO: O omeprazol e o pantoprazol, agentes inibidores da bomba de prótons (H+, K+-ATPase), não interferem na regeneração hepática 32 e 56 horas após hepatectomia parcial a 67% em ratos.

Detection of anti-HAV antibody with dot immunogold filtration assay

AIM: To establish a rapid, sensitive and specific immunogold assay for detection of hepatitis A virus infection.

METHODS: Rabbit monoclonal antibodies to anti-human IgM and IgG (Dako) were dotted on a nitrocellulose membrane (NCM) respectively to capture the human sera IgM and IgG. Then the captured antibodies would conjugate to HAV antigen, which was revealed by mouse anti-HAV IgG conjugated to gold particles. Final results were assessed by blind method.

RESULTS: Sera from 96 patients with acute hepatitis were used for our study. Compared with well-recognized standard (Abbott Laboratory, USA), the sensitivity and specificity of IgM-DIGFA (self-made) were 91.3% (42/46) and 96.0% (48/50), and those of IgM-ELISA (Kehua, Shanghai) were 97.8% (45/46) and 100.0% (50/50). The identical results were produced from the study with reagents at different conditions, and the study was repeated in 15 negative sera and 10 positive sera. The serum anti-HAV IgG was tested with DIGFA at the same time. In comparison with ELISA, the sensitivity and specificity of DIGFA for IgG anti-HAV were 87.2% (41/47) and 91.8% (45/49), respectively.

CONCLUSION: This assay can detect anti-HAV IgM and IgG simultaneously, and be done within 3 min. The simplicity, rapidity and specificity of the assay were useful for screening and epidemiological study.

Gastric autoimmune disorders in patients with chronic hepatitis C before, during and after interferon-alpha therapy

AIM: To explore the prevalence of autoimmune gastritis in chronic hepatitis C virus (HCV) patients and the influence of a-interferon (IFN) treatment on autoimmune gastritis.

METHODS: We performed a prospective study on 189 patients with positive anti-HCV and viral RNA enrolled in a 12-month IFN protocol. We evaluated: a) the baseline prevalence of autoimmune gastritis, b) the impact of IFN treatment on development of biochemical signs of autoimmune gastritis (at 3, 6 and 12 mo), c) the evolution after IFN withdrawal (12 mo) in terms of anti-gastric-parietal-cell antibodies (APCA), gastrin, anti-thyroid, and anti-non-organ-specific antibodies.

RESULTS: APCA positivity and 3-fold gastrin levels were detected in 3 (1.6%) and 9 (5%) patients, respectively, at baseline, in 25 (13%) and 31 (16%) patients at the end of treatment (both P < 0.001, vs baseline), and in 7 (4%) and 14 (7%) patients 12 mo after withdrawal (P = 0.002 and P = 0.01 respectively, vs baseline; P = not significant vs end of treatment). The development of autoimmune gastritis was strictly associated with the presence of autoimmune thyroiditis (P = 0.0001), no relationship was found with other markers of autoimmunity.

CONCLUSION: In HCV patients, IFN frequently precipitates latent autoimmune gastritis, particularly in females. Following our 12-month protocol, the phenomenon generally regressed. Since APCA positivity and high gastrin levels are associated with the presence of antithyroid antibodies, development of autoimmune thyroiditis during IFN treatment may provide a surrogate preliminary indicator of possible autoimmune gastritis to limit the need for invasive examinations.

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.

Fatores hepatotróficos e regeneração hepática. Parte I: o papel dos hormônios

No complexo processo de proliferação celular, os hormônios agem de diferentes maneiras ao atingirem seus receptores nos tecidos-alvo. Os principais fatores ligados ao crescimento hepático são HGF, TGF-alpha, IL-6, TNF-alpha, norepinefrina, EGF e insulina. O GH estimula tanto o fígado a produzir fatores de crescimento, como a expressão genética do HGF e a síntese de DNA. Hormônios tireoideanos aumentam a capacidade proliferativa dos hepatócitos. A insulina age sinergicamente com GH e glucagon. Não tem potencial mitogênico primário mas intensifica o estímulo regenerativo iniciado pela epinefrina e norepinefrina. Esta amplifica os sinais mitogênicos do EGF e HGF, induz a secreção de EGF e antagoniza os efeitos inibitórios do TGF-beta 1. O glucagon isoladamente não produz efeitos mas provavelmente participa na síntese de DNA e da resposta homeostásica pela qual a glicemia é mantida estável durante a regeneração. Também há indícios de ação hepatotrófica da gastrina.

Effect of gastrin and anti-gastrin antibodies on proliferation of hepatocyte cell lines

Gastrin (G-17) and its precursor glycine-extended gastrin (G-17-gly) have been shown to be trophic to some gastrointestinal tumors. This in vitro study assessed the effect of G-17, G-17-gly, anti-gastrin antibodies (anti-G-17), and the CCK-B receptor antagonist PD135,158 on three hepatoma cell lines (PLC/PRF/5, HepG2 and MCA-RH7777) and an embryonic liver cell line (WRL68). The pancreatic adenocarcinoma cell line AR42J was used as a positive control. G-17 and G-17-gly caused significant proliferation of AR42J and WRL68 cell lines. G-17-gly but not G-17 induced significant proliferation of the PLC/PRF/5 cell line. Anti-G-17 and PD135,158 significantly inhibited unstimulated AR42J and WRL68 cell lines. Anti-G-17 also inhibited the proliferative effects of G-17 and G-17-gly on AR42J, WRL68, and PLC/PRF/5 cell lines, whereas PD135,158 inhibited the proliferative effect of G-17 only. G-17 and G-17-gly as well as anti-G-17 and PD135,158 had no effect on HepG2 and MCA-RH77777 cell lines. It is concluded that G-17-stimulated proliferation is mediated via the CCK-B receptor and G-17-gly via a separate, as yet uncharacterized, receptor. There may therefore be a role for gastrin in embryonic hepatocellular proliferation and perhaps also in the proliferation of some hepatocellular tumors.

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.

Regenerative capacities of normal and cirrhotic livers following 70% hepatectomy in rats and the effect of alpha-tocopherol on cirrhotic regeneration

BACKGROUND

The regeneration of normal and cirrhotic liver has been very well demonstrated after partial hepatectomy; although the tissue regenerated by cirrhotic liver is also cirrhotic. The structural differences of the regenerated tissues between normal and cirrhotic livers may also indicate different regeneration capacities. The objective of this study was to compare the regeneration capacities of normal and cirrhotic livers by bromodeoxyuridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) labeling indices in replicating nuclei and mitotic figures in cells in partially hepatectomized normal and cirrhotic rats and to study the effect of alpha-tocopherol on cirrhotic liver regeneration.

METHODS

Five groups of adult Wistar rats comprised normal livers, cirrhotic livers, regenerated normal livers, regenerated cirrhotic livers, and alpha-tocopherol-treated regenerated cirrhotic livers. Cirrhosis was induced by intragastric administration of carbon tetrachloride and phenobarbital in the drinking water of the rats. Liver regeneration capacities in normal and cirrhotic rats and following partial hepatectomy in normal and cirrhotic rats and cirrhotic rats that were administered alpha-tocopherol were evaluated through BrdU incorporation, PCNA labeling, and mitotic indices.

RESULTS

BrdU and PCNA labeling and mitotic indices were zero for normal rats and 4.3 +/- 3.5, 6.5 +/- 5, and 2.5 +/- 1.5 for cirrhotic rats, respectively. The values after partial hepatectomy in normal and cirrhotic rats were 46.2 +/- 8.7 and 27.8 +/- 7.5 for BrdU labeling, 83.7 +/- 6.5 and 51.3 +/- 6.8 for PCNA labeling, and 31.8 +/- 4.2 and 18.6 +/- 3.4 for mitotic index, respectively. For the fifth group comprising cirrhotic rats that were administered alpha-tocopherol and had undergone partial hepatectomy, BrdU incorporation, PCNA labeling, and mitotic indices were 37.5 +/- 6.3, 76.5 +/- 6.2, and 27.2 +/- 4.2, respectively. When the cirrhotic liver regeneration group was compared with the normal liver regeneration group, rates of liver regeneration in the cirrhotic group were significantly depressed (P < 0.01). Although the BrdU incorporation and PCNA labeling indices of the alpha-tocopherol-administered cirrhotic liver regeneration group indicated significantly lower rates of liver regeneration when compared with the normal liver regeneration group (P < 0.05), the liver regeneration rates of the alpha-tocopherol-administered cirrhotic group were also significantly higher than those of the cirrhotic liver regeneration group that was not administered alpha-tocopherol (P < 0.01).

CONCLUSIONS

Cirrhotic livers revealed a significantly depressed capacity for regeneration following partial hepatectomy. alpha-Tocopherol administration seemed to improve the rates of regeneration in cirrhotic rats with respect to the BrdU incorporation, PCNA labeling, and mitotic indices.

Antibodies raised by gastrimmune inhibit the spontaneous metastasis of a human colorectal tumour, AP5LV

Both precursor forms of gastrin and mature amidated gastrin peptides can enhance proliferation of colorectal tumours and may regulate growth in an autocrine manner. The purpose of this study was to evaluate the effect of neutralization of precursor and amidated gastrin on primary and secondary in vivo growth of a human colorectal tumour. The human colorectal cell line, AP5LV, when injected into the muscle layer of the abdominal wall of severe combined immunodeficient (SCID) mice, grows as a well-vascularized primary tumour and metastasis to the lung. AP5LV expressed the precursor gastrin forms; progastrin and glycine-extended gastrin and gastrin/CCKB receptors, as assessed by immunocytochemistry. Gastrimmune is a gastrin immunogen in which the amino terminus of the gastrin-17 molecule is linked to diphtheria toxoid and induces antibodies which neutralise the amidated and glycine-extended forms of gastrin-17. Rabbit antiserum, raised against Gastrimmune, was administered intravenously into SCID mice bearing AP5LV tumours. Control animals were treated with antiserum raised against diphtheria toxoid only. Antibodies raised against Gastrimmune significantly limited the growth of primary AP5LV tumours, as assessed by median cross-sectional area (controls = 244 mm2; antibody-treated = 179 mm2; P = 0.033). In addition Gastrimmune-induced antiserum limited the growth of lung metastasis as assessed by nodule number (controls = 3.5; antibody-treated = 1.0; P = 0.0001) and nodule cross-sectional as assessed by image analysis (controls = 11.9 mm2; antibody-treated = 3.75 mm2; P = 0.0064). In conclusion in vivo neutralization of gastrin forms, which may potentially be fueling growth by an autocrine pathway, inhibited both primary growth and, to a greater degree, lung metastasis of a human colorectal tumour cell line. Immunization against tumour-associated gastrin forms may provide an effective therapy for advanced colorectal cancer.

Expression and processing of gastrin in hepatocellular carcinoma, fibrolamellar carcinoma and cholangiocarcinoma

BACKGROUND/AIMS

Gastrin is a trophic factor within the normal gastrointestinal tract and is also a mitogen for a number of gastrointestinal and non-gastrointestinal tumours. Precursor forms of gastrin including progastrin (proG) and glycine-extended gastrin (G-gly) as well as the fully processed amidated gastrin (G-NH2) are expressed by tumours. There has been little study of the role of gastrin in either normal liver or liver tumours. The aim of this study was to identify the expression of CCK-B/gastrin receptor (CCK-BR), proG, G-gly and G-NH2 in normal liver and liver tumours.

METHODS

Tissue sections from patients with hepatocellular carcinoma, fibrolamellar carcinoma, cholangiocarcinoma as well as normal liver biopsies were assessed for expression of CCK-BR and gastrin isoforms.

RESULTS

Most liver tumours express CCK-BR and are able to process gastrin as far as proG and G-gly, although not as far as the amidated form. There appears to be little expression of the receptor and no expression of precursor forms of gastrin in normal liver.

CONCLUSIONS

Liver tumours express the CCK-BR and precursor forms of gastrin. This expression may be associated with tumour proliferation.

Immunohistochemical distribution of epimorphin in human and mouse tissues

A novel protein epimorphin has been identified as a mesenchymal signal factor. We reported previously ubiquitous expression of epimorphin in normal skin and a significant increased expression in diseased human skin. The present immunofluorescence study was conducted to determine systematically the distribution of epimorphin in adult human organs with an anti-epimorphin monoclonal antibody. Epimorphin was found to be widely distributed in all human organs examined. It was present in the connective tissue adjacent to or around various epithelial tissues, muscles and vessels. In particular, strong staining was present on the endomysium of muscles, the adventitia of blood vessels, along the sinusoidal lining of hepatocytes and connective tissue around epithelial cells, exocrine and endocrine glands. The results suggest that epimorphin may play a key role in maintaining normal tissue structure and interaction between mesenchymal tissue and epithelial tissue in vivo.

The liver regenerative response elicited by antisecretory agents in partially hepatectomized rats: a comparison between omeprazole and famotidine

Liver regeneration after omeprazole (OMP) or famotidine (FAM) administration was examined in 66% hepatectomized rats. The regeneration was evaluated by the liver weight as a percentage of body weight (LRR) and the proportion of hepatocytes in mitosis per 1,000 counts (MI). Administration of OMP 0.4 mg/kg per day for 3 or 7 days suppressed LRR and MI 3 and 7 days after hepatectomy. However, the administration of FAM 0.8 mg/kg per day for 3 or 7 days did not change either LRR or MI. Increased gastrin levels in the blood were seen only after OMP administration. The food intake was unchanged by OMP or FAM, but FAM increased water intake. The liver functional score, glutamic pyruvic transaminase and alkaline phosphatase in the blood all increased with OMP, but FAM had no apparent effect on the hepatic or renal function. These observations suggest that a large dosage of OMP suppresses liver regeneration, while FAM appears to have no meaningful effect on regeneration.

Endogenous gastrin and cholecystokinin do not promote growth of rat liver

BACKGROUND

The purpose of the study was to evaluate the trophic effects of endogenous hypergastrinemia and hypercholecystokininemia on intact and regenerating rat liver. We also examined the effects on the liver of portacaval shunting (PCS) alone or together with hypergastrinemia or hyperCCKemia. PCS is known to enhance the trophic effects of gastrin on the so-called enterochromaffin-like cells of the stomach and of CCK on the pancreas.

METHODS

Hypergastrinemia was induced by treatment with omeprazole (400 mumol/kg/day) or extirpation of the acid-producing part of the stomach (fundectomy). HyperCCKemia was induced by pancreaticobiliary diversion (PBD). After 4 weeks half of the rats were killed; the rest underwent partial hepatectomy and were killed 60 h later. PCS rats were killed 4 weeks after start of omeprazole treatment or after PBD. The concentrations of circulating gastrin and CCK were measured by radioimmunoassay. The liver weight and DNA content were analyzed.

RESULTS

Endogenous hypergastrinemia and hyperCCKemia failed to stimulate growth of either intact or regenerating liver. There were no differences in liver weight and DNA content between rats subjected to PCS and to combinations of PCS and omeprazole treatment, on the one hand, and PCS and PBD, on the other.

CONCLUSION

Gastrin and CCK are unlikely to be physiologically important in the regulation of liver growth and regeneration in the rat.

Liver regeneration is enhanced by omeprazole in rats following partial hepatectomy

The effect of omeprazole on liver regeneration was studied in rats following partial (65 per cent) hepatectomy. Omeprazole 0.2 mg/kg increased the relative liver weight (weight of liver as a proportion of body-weight) and mitotic index (P < 0.05). There was no difference in food and water intake. The serum gastrin concentration was significantly higher in animals receiving omeprazole 0.2 mg/kg than in controls (P < 0.05). Omeprazole administration induced an increase in the level of serum alkaline phosphatase (P < 0.05) but had no effect on serum albumin, glutamic-pyruvic transaminase and total bilirubin levels. Omeprazole stimulates liver regeneration after partial hepatectomy and this regeneration may be mediated by gastrin.