transforming-growth-factor-alpha and Stomach-Ulcer

Growth factors and their receptors play important roles in cell proliferation, migration, tissue injury repair and ulcer healing. In gastric mucosa, transforming growth factor alpha (TGF-alpha) and epidermal growth factor (EGF) by activating their common receptor, control cell proliferation. TGF-alpha predominantly plays this role under normal conditions and after acute injury, while EGF exerts its actions mainly during healing of chronic ulcers. During regeneration of injured gastric mucosa, these growth factors serve predominantly to restore the epithelial component. Other growth factors, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) serve to promote restoration of the connective tissue and microvessels (angiogenesis) in injured mucosa. During healing of chronic ulcers, a new epithelial lineage secreting EGF and other growth peptides develops and the majority of cells lining the ulcer margin overexpress the EGF receptor. Activation of the EGF receptor induces dramatic increases in MAP (Erk -1 and -2) kinase activity and phosphorylation levels. Inhibition of this signaling pathway dramatically delays ulcer healing. Granulation connective tissue, which grows under the stimulation of bFGF and VEGF is the major source for regeneration of connective tissue lamina propria and microvessels within the ulcer scar. Other growth factors such as insulin - like growth factor, keratinocyte growth factor, hepatocyte growth factor and trefoil peptides have been implicated in gastrointestinal (gastric ulcers, colitis) regeneration following injury. This paper is intended to provide an overview of the role of growth factors in gastrointestinal mucosal regeneration.

Topics: Animals; Cell Division; Colitis; Epidermal Growth Factor; Gastric Mucosa; Growth Substances; Helicobacter Infections; Helicobacter pylori; Humans; Intestinal Mucosa; Neovascularization, Physiologic; Regeneration; Signal Transduction; Stomach Ulcer; Transforming Growth Factor alpha; Wound Healing

The maintenance of the integrity of the gastrointestinal mucosa and the repair of acute and chronic mucosal lesions are under the influence of various growth factors, especially epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha). EGF originates mainly from salivary glands, whereas TGF-alpha is released locally in the gastric mucosa, particularly when the mucosa is exposed to topical irritants. EGF and TGF-alpha have similar spectra of biological activity, which include the stimulation of the restitution and proliferation of mucosal cells, gastroprotection, vasodilatation, gastric adaptation to noxious substances, healing of acute and chronic lesions and inhibition of gastric acid secretion. Accumulation of EGF in the ulcer area as a result of excessive production by ulcer-associated new cell lineages contributes together with overexpression of EGF receptors in the ulcer area to the migration of cells from the ulcer margin and formation of granulation tissue and microvessels (angiogenesis) during the ulcer healing process.

Topics: Animals; Epidermal Growth Factor; ErbB Receptors; Gastric Mucosa; Granulation Tissue; Humans; Neovascularization, Physiologic; Stomach Ulcer; Transforming Growth Factor alpha; Wound Healing

To investigate and compare the effects of tocotrienol and omeprazole on gastric growth factors in rats exposed to water-immersion restraint stress (WIRS).. Twenty-eight male Wistar rats were randomly assigned to four groups of seven rats. The two control groups were administered vitamin-free palm oil (vehicle) and the two treatment groups were given omeprazole (20 mg/kg) or tocotrienol (60 mg/kg) by oral gavage. After 28 d of treatment, rats from one control group and both treated groups were subjected to WIRS one time for 3.5 h. Gastric lesions were measured and gastric tissues were obtained to measure vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and transforming growth factor-alpha (TGF-α) mRNA expression.. Rats exposed to WIRS for 3.5 h demonstrated the presence of considerable ulcers in the form of gastric erosion. The lesion index in the stressed control (S) group was increased (. Tocotrienol provides gastroprotective effects in WIRS-induced ulcers. Compared to omeprazole, tocotrienol exerts a similar protective effect, albeit through multiple mechanisms of protection, particularly through up-regulation of growth factors that assist in repair of gastric tissue injuries.

Topics: Animals; Anti-Ulcer Agents; Antioxidants; Disease Models, Animal; Fibroblast Growth Factor 2; Gastric Acid; Gastric Mucosa; Humans; Male; Neovascularization, Physiologic; Omeprazole; Rats; Rats, Wistar; Restraint, Physical; RNA, Messenger; Stomach Ulcer; Stress, Psychological; Tocotrienols; Transforming Growth Factor alpha; Up-Regulation; Vascular Endothelial Growth Factor A

This study aimed to investigate the possible gastroprotective effect of tocotrienol against water-immersion restraint stress (WIRS) induced gastric ulcers in rats by measuring its effect on gastric mucosal nitric oxide (NO), oxidative stress, and inflammatory biomarkers. Twenty-eight male Wistar rats were randomly assigned to four groups of seven rats. The two control groups were administered vitamin-free palm oil (vehicle) and the two treatment groups were given omeprazole (20 mg/kg) or tocotrienol (60 mg/kg) orally. After 28 days, rats from one control group and both treated groups were subjected to WIRS for 3.5 hours once. Malondialdehyde (MDA), NO content, and superoxide dismutase (SOD) activity were assayed in gastric tissue homogenates. Gastric tissue SOD, iNOS, TNF-α and IL1-β expression were measured. WIRS increased the gastric MDA, NO, and pro-inflammatory cytokines levels significantly when compared to the non-stressed control group. Administration of tocotrienol and omeprazole displayed significant protection against gastric ulcers induced by exposure to WIRS by correction of both ulcer score and MDA content. Tissue content of TNF-α and SOD activity were markedly reduced by the treatment with tocotrienol but not omeprazole. Tocotrienol significantly corrected nitrite to near normal levels and attenuated iNOS gene expression, which was upregulated in this ulcer model. In conclusion, oral supplementation with tocotrienol provides a gastroprotective effect in WIRS-induced ulcers. Gastroprotection is mediated through 1) free radical scavenging activity, 2) the increase in gastric mucosal antioxidant enzyme activity, 3) normalisation of gastric mucosal NO through reduction of iNOS expression, and 4) attenuation of inflammatory cytokines. In comparison to omeprazole, it exerts similar effectiveness but has a more diverse mechanism of protection, particularly through its effect on NO, SOD activity, and TNF-α.

Topics: Animals; Antioxidants; Biomarkers; Gastric Mucosa; Inflammation; Interleukin-1beta; Lipid Peroxidation; Male; Malondialdehyde; Nitric Oxide; Omeprazole; Oxidative Stress; Random Allocation; Rats; Rats, Wistar; Stomach; Stomach Ulcer; Superoxide Dismutase; Tocotrienols; Transforming Growth Factor alpha

To observe the effects and mechanisms of Pongamia pinnata root flavonoids (PRF) on the experimental gastric ulcer induced by acetic acid and to study the mechanism of PRF on the quality of ulcer healing.. The models were established by acetic acid erosion, the quality of ulcer healing of PRF on the model of gastric ulcer were observed. The contents of epidermal growth factor (EGF) in serum were determined by radioimmunoassay. The expression of EGF and transforming growth factor-alpha (TGF-alpha) were detected by immunohistochemistry (SP).. PRF significantly inhibited ulcerative formation induced by acetic acid (P < 0.05, P < 0.01). PRF could significantly increase the EGF and TGF-alpha (P < 0.05, P < 0.01) expression of para-ulcer mucosa tissue and improve the EGF contents in blood serum (P < 0.05, P < 0.01).. PRF increases the contents of EGF in serum and the expression of EGF and TGF-alpha in the tissue around gastric ulcer which might be one of possible mechanisms that PRF improves quality of ulcer healing.

Topics: Acetic Acid; Animals; Epidermal Growth Factor; Female; Flavonoids; Gastric Mucosa; Male; Millettia; Plant Roots; Rats; Rats, Sprague-Dawley; Stomach Ulcer; Transforming Growth Factor alpha

Aspirin causes gastroduodenal ulcers and complications. Food bioactive compounds could exert beneficial effects in the gastrointestinal tract. We evaluated whether apple polyphenol extract (APE) reduced aspirin-induced injury to the rat gastric mucosa. Rats were treated with APE (10(-4) m catechin equivalent) before oral aspirin (200 mg/kg). Cyclo-oxygenase-2 (COX-2), transforming growth factor-alpha (TGF alpha) and heparin-binding epidermal-growth-factor-like growth factor (HB-EGF) mRNA and protein expression were assessed by RT-PCR and Western blot analysis, respectively; malondialdehyde (MDA) was determined by HPLC; gastric secretion was evaluated in pylorus-ligated rats. APE decreased acute and chronic aspirin injury both macroscopically and microscopically (approximately 50 % decrease in lesion score; P < 0.05). Aspirin up-regulated mRNA and protein expression of COX-2 and HB-EGF, but not of TGF alpha; APE reduced aspirin-induced mRNA and protein over-expression of COX-2 and HB-EGF; aspirin significantly increased gastric MDA and this effect was counteracted by APE pre-treatment. APE did not significantly affect gastric acid secretion. In conclusion, APE reduces aspirin-induced gastric injury independently of acid inhibition. We speculate that APE might be of therapeutic use in the prophylaxis of aspirin-related gastropathy.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Biological Availability; Cyclooxygenase 2; Drug Evaluation, Preclinical; Flavonoids; Gastric Acid; Gastric Mucosa; Heparin-binding EGF-like Growth Factor; Intercellular Signaling Peptides and Proteins; Lipid Peroxidation; Male; Phenols; Phytotherapy; Plant Extracts; Polyphenols; Rats; Rats, Wistar; Stomach Ulcer; Transforming Growth Factor alpha

For the production and vesicle storage of histamine, Enterochromaffin-like (ECL) cells express histidine decarboxylase (HDC) and vesicular monoamine transporter 2 (VMAT2). Although HDC and VMAT2 show dynamic changes during gastric ulcer healing, the control system of their expression has not been fully investigated. In the present study, we investigated the effect of transforming growth factor-alpha (TGF-alpha) and proinflammatory cytokines on HDC and VMAT2 expression in rat ECL cells. Time course changes in the expression of TGF-alpha during the healing of acetic acid-induced ulcers were studied. EGF receptor (EGFR) expression was also examined in ECL cells, whereas the direct effects of TGF-alpha and proinflammatory cytokines on HDC and VMAT2 expression in ECL cells were investigated using in vivo and in vitro models. During the process of ulcer healing, expression of TGF-alpha mRNA was markedly augmented. Furthermore, EGFR was identified in isolated ECL cells. TGF-alpha stimulated HDC and VMAT2 mRNA expression and protein production and also increased histamine release from ECL cells. Selective EGFR tyrosine kinase inhibitor tyrphostin AG1478 almost completely inhibited HDC and VMAT2 gene expression induced by TGF-alpha in vivo and in vitro. During gastric mucosal injury, TGF-alpha was found to stimulate ECL cell functions by increasing HDC and VMAT2 expression.

Topics: Acetic Acid; Animals; Blotting, Northern; Cell Separation; Cells, Cultured; Enterochromaffin Cells; Gastric Mucosa; Gene Expression Regulation, Enzymologic; Histidine Decarboxylase; Immunohistochemistry; Kinetics; Male; Membrane Glycoproteins; Membrane Transport Proteins; Neuropeptides; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Stomach Ulcer; Transforming Growth Factor alpha; Vesicular Biogenic Amine Transport Proteins; Vesicular Monoamine Transport Proteins

The present study was designed to investigate the effects of microemulsion and aqueous solution containing transforming growth factor alpha (TGF-alpha) and/or aprotinin administered intragastrically (i.g.) on healing of acute gastric ulcers induced by acetylsalicylic acid (ASA). The microemulsion was prepared by modification of the microemulsion formulation described in our previous study. Acute gastric lesions were induced by the application of ASA (150 mg/kg in 1.5 ml of 0.2N HCl i.g.). TGF-alpha in solution or microemulsion formulations were administered at a dose of 10 microg/kg per 24h i.g. for 2 days. The effects of TGF-alpha on the healing was evaluated with the measurement of ulcer score, basal gastric acid secretion, total protein content of gastric fluid, gastric mucus level and histological analysis. The results indicated that the highest decrease in ulcer area was observed in group treated with microemulsion containing TGF-alpha plus aprotinin (TA-ME). TGF-alpha in microemulsion formulation was more effective than TGF-alpha in solution formulation in the increase of gastric mucus secretion, in the decrease of gastric acid secretions and ulcer scores. Histological evaluation of the gastric mucosa samples revealed that, best recovery was obtained in the TA-ME treated group.

Topics: Animals; Aspirin; Gastric Mucosa; Injections, Intralesional; Male; Mice; Rats; Rats, Wistar; Stomach Ulcer; Transforming Growth Factor alpha

To determine the role of mucosal gene expression of cyclooxygenase 2 (COX-2), pS2 (belongs to trefoil peptides), inducible nitric oxide synthase (iNOS) and transforming growth factor alpha (TGFalpha) in gastric adaptation to water immersion and restraint stress (WRS) in rats.. Wistar rats were exposed to single or repeated WRS for 4 h every other day for up to 6 d. Gastric mucosal blood flow (GMBF) was measured by laser Doppler flowmeter-3. The extent of gastric mucosal lesions were evaluated grossly and histologically and expressions of COX-2, pS2,iNOS and TGFalpha were determined by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot.. The damage to the surface of gastric epithelium with focal areas of deep haemorrhagic necrosis was induced by repeated WRS. The adaptative cytoprotection against stress was developed with activation of cell proliferation in the neck regions of gastric glands. The ulcer index (UI) in groups II, III and IV was markedly reduced as compared with group I (I: 47.23+/-1.20; IV: 10.39+/-1.18,P<0.01). GMBF significantly decreased after first exposure to WRS with an adaptive increasement of GMBF in experimental groups after repetitive challenges with WRS. After the 4th WRS, the value of GMBF almost restored to normal level (I: 321.87+/-8.85; IV: 455.95+/-11.81, P<0.01). First WRS significantly decreased the expression of pS2 and significantly increased the expressions of COX-2, iNOS and TGFalpha. After repeated WRS, pS2 and TGFalpha expressions gradually increased (pS2: I: 0.37+/-0.02; IV: 0.77+/-0.01; TGFalpha: I: 0.86+/-0.01; IV: 0.93+/-0.03, P<0.05) with a decrease in the expressions of COX-2 and iNOS (COX-2: I: 0.45+/-0.02; IV: 0.22+/-0.01; iNOS: I: 0.93+/-0.01; IV: 0.56+/-0.01, P<0.01). Expressions of pS2, COX-2, iNOS and TGFalpha showed regular changes with a good relationship among them.. Gastric adaptation to WRS injury involves enhanced cell proliferation, increased expression of pS2 and TGFalpha, and reduced expression of COX-2 and iNOS. These changes play an important role in adaptation of gastric mucosa after repeated WRS.

Topics: Adaptation, Physiological; Animals; Cyclooxygenase 2; Gastric Mucosa; Isoenzymes; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Prostaglandin-Endoperoxide Synthases; Proteins; Rats; Rats, Wistar; Stomach; Stomach Ulcer; Stress, Physiological; Transforming Growth Factor alpha; Trefoil Factor-1; Tumor Suppressor Proteins

Transforming growth factor (TGF) alpha accelerates wound healing, especially in gastric ulcers. Transforming growth factor alpha can be affected by acid and pepsin in the gastric juice. Oxidative stress also plays a role in the formation of gastric lesions. This study was designed (1) to investigate the effects of microemulsion dosage form on the healing of gastric ulcers, and (2) to determine the relationship between oxidative mechanisms and TGF-alpha during ulcer healing.. Gastric ulcers were induced in Wistar rats (male, 200 +/- 25 g), by 150 mg/kg acidified aspirin application. The animals were divided into five groups consisting of 7-11 animals. The rats were killed after ulcer induction with aspirin (acute ulcer), or 2 days after ulcer induction (chronic ulcer), or after the daily application of microemulsion and TGF-alpha for 2 days. The ulcer area was measured planimetrically. Thiobarbituric acid reactive substance, glutathione, and gastric mucus levels of tissues were measured by spectrophotometric methods. The total nitric oxide level was measured by a VCl3/Griess assay. Statistical comparisons were made by an analysis of variance and the Mann-Whitney U-test.. The ulcer area and malondialdehyde level of gastric tissue both decreased and the glutathione level increased to intact gastric tissue levels, while the mucus and total nitric oxide levels increased significantly after the application of intragastric TGF-alpha.. These findings suggest that TGF-alpha accelerates the healing process after aspirin-induced gastric injury, and a relationship was observed between this application and the oxidative reactions.

Topics: Analysis of Variance; Animals; Aspirin; Biomarkers; Disease Models, Animal; Gastric Mucosa; Glutathione; Male; Malondialdehyde; Nitric Oxide; Oxidative Stress; Probability; Random Allocation; Rats; Rats, Wistar; Sensitivity and Specificity; Spectrophotometry; Statistics, Nonparametric; Stomach Ulcer; Transforming Growth Factor alpha

Exogenously administered TGF alpha has been shown to protect rodent gastric mucosa against injury caused by acid-dependent and acid-independent injury. The present study examined whether the gastroprotective effects of TGF alpha on stress-induced gastric ulceration in the rat involves activation of capsaicin-sensitive sensory neurons. Fasted male SD rats were subjected to water restraint stress (WRS) for four hours. Thereafter, rats were euthanized; the stomach opened and macroscopic areas of gastric ulceration quantitated (mm(2)). Gastric tissue contents of TGF alpha and the sensory neuropeptide, calcitonin gene-related peptide (CGRP) were determined by radioimmunoassay. Prior to stress rats received TGF alpha 50, 100 or 200 microg/kg by intraperitoneal injection. Sensory denervation was accomplished by high dose capsaicin treatment. WRS caused severe ulceration in the gastric corpus; 46.1 + 6.6 mm(2). Parenteral administration of TGF alpha caused dose-dependent reduction in gastric injury: 34.7 + 4.9 mm(2) with 50 microg/kg (p < 0.05); 25.4 + 3.6 mm(2) with 100 microg/kg (p < 0.001) and 9.4 + 0.8 mm(2) with 200 microg/kg (p < 0.001). The gastroprotective action of TGF alpha (200 microg/kg, i.p.) was abolished by capsaicin-induced sensory denervation. In addition, WRS ulceration was associated with significant reduction in gastric CGRP (-42%) and TGF alpha (-48%) content. Reduction in CGRP content was prevented by TGF alpha pretreatment. We conclude that: 1) TGF alpha caused dose-dependent gastroprotection against WRS ulceration, 2) TGF alpha-mediated gastric mucosal protection was prevented by capsaicin-induced sensory denervation and, 3) stress-induced injury was associated with significant reduction in gastric content of both TGF alpha and CGRP.

Topics: Animals; Calcitonin Gene-Related Peptide; Capsaicin; Dose-Response Relationship, Drug; Gastric Mucosa; Immersion; Immobilization; Injections, Intraperitoneal; Male; Neurons, Afferent; Rats; Rats, Sprague-Dawley; Stomach; Stomach Ulcer; Stress, Psychological; Sympathectomy, Chemical; Transforming Growth Factor alpha

Leptin was shown to exhibit similar to cholecystokinin (CCK) cytoprotective activity against acute gastric lesions, but its role in ulcer healing has not been examined. The aims of this study were: (1) to compare the effects of exogenous leptin to those of CCK on the course of healing of chronic gastric ulcers; (2) to study the gene and protein expression of leptin at the ulcer margin during ulcer healing; and (3) to assess the effects of leptin administration on the mucosal gene expression of main growth factor such as transforming growth factor alpha (TGFalpha). Gastric ulcers were produced in rats by the acetic acid method. Rats with ulcers were divided in following treatment groups: (1) vehicle; (2) leptin (10 microg/kg i.p.); (3) CCK (10 microg/kg s.c.); and (4) leptin or CCK with or without tyrphostin A46 (200 microg/kg i.p.), an inhibitor of epidermal growth factor (EGF)-receptor tyrosine kinase or NG-nitro-L-arginine (20 mg/kg i.g.), a blocker of nitric oxide synthase. Animals were euthanized 9 days after ulcer induction. The area of gastric ulcers and the gastric blood flow at the ulcer area were determined. In addition, mucosal biopsy samples were taken from the ulcer area for histological evaluation as well as for the determination of mRNA and protein expression for leptin and constitutive nitric oxide synthase (cNOS) and inducibile nitric oxide synthase (iNOS) by reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot, respectively. In addition, the gene expression for TGFalpha was analyzed by RT-PCR. Both leptin and CCK reduced significantly the ulcer area as compared to vehicle-treated group by approximately 50%. The treatment with tyrphostin or N(G)-nitro-L-arginine reversed in part the acceleration of ulcer healing by leptin and CCK. The expression of leptin mRNA and protein was significantly increased at the ulcer edge. The leptin-induced acceleration of ulcer healing was associated with increased expression of transcripts for TGFalpha as well as increased mRNA and protein expression for cNOS and iNOS at the ulcer margin. We conclude that leptin accelerates ulcer healing by mechanisms involving the up-regulation of TGFalpha and increased production of nitric oxide due to up-regulation of cNOS and iNOS in the ulcer area.

Topics: Animals; Enzyme Inhibitors; Gastric Mucosa; Gastrointestinal Agents; Leptin; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type III; Nitroarginine; Rats; Rats, Wistar; RNA, Messenger; Sincalide; Stomach Ulcer; Transforming Growth Factor alpha; Tyrphostins

Adrenomedullin (AM) is a potent vasodilatory peptide. While its growth-regulating action in some cultured cells has been recognized, expression of AM and its receptor during gastric ulcer healing has not been explored. Specimens of gastric walls from control rats or gastric ulcers were obtained at 1, 3, 7, and 14 days after gastric ulcer induction. AM and its receptor mRNAs expression were determined by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. By RT-PCR, AM mRNA was increased by 167% at three days, while AM receptor mRNA was increased by 234% at seven days (both P < 0.05). By in situ hybridization, AM and AM receptor mRNAs were increased at ulcer margin from three days after ulcer induction. By immunohistochemistry, AM was increased in the ulcer margin at three and seven days. In separate in vitro studies using a rat gastric epithelial (RGM1) cell line, AM treatment significantly increased transforming growth factor-alpha mRNA expression and cell proliferation.

Topics: Adrenomedullin; Animals; Immunohistochemistry; In Situ Hybridization; Male; Peptides; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; Receptors, Adrenomedullin; Receptors, Peptide; RNA, Messenger; Stomach Ulcer; Transforming Growth Factor alpha; Wound Healing

We investigated the role of thromboxane (TX) A2 in gastric ulcer healing in rats. Acetic acid ulcers were produced in male Donryu rats. TXA2 synthesis in the stomachs with ulcers was significantly elevated in ulcerated tissue, but not in intact tissue, compared with that in the gastric mucosa of normal rats. Indomethacin inhibited both TXA2 and prostaglandin E2 (PGE2) synthesis in ulcerated tissue, while NS-398 (selective cyclooxygenase-2 inhibitor) reduced only PGE2 synthesis. OKY-046 (TXA2 synthase inhibitor) dose-relatedly inhibited only TXA2 synthesis. The maximal effect of OKY-046 (80% inhibition) was found at more than 30 mg/kg. When OKY-046 was administered for 14 days, the drug at more than 30 mg/kg significantly accelerated ulcer healing without affecting acid secretion. The maximal reduction of ulcerated area by OKY-046 was about 30%, compared with the area in the control. Histological studies revealed that regeneration of the mucosa was significantly promoted by OKY-046, but neither maturation of the ulcer base nor angiogenesis in the base were affected. OKY-046 and TXB2 had no effect on proliferation of cultured rat gastric epithelial cells, but U-46619 (TXA2 mimetic) dose-relatedly prevented the proliferation without reducing cell viability. These results indicate that the increased TXA2, probably derived from cyclooxygenase-1 in ulcerated tissue, exerts a weak inhibitory effect on ulcer healing in rats. The effect of TXA2 might be due partly to prevention of gastric epithelial cell proliferation at the ulcer margin.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cell Division; Cell Line; Cell Survival; Enzyme Inhibitors; Epithelial Cells; Gastric Mucosa; Male; Methacrylates; Rats; Rats, Inbred Strains; Stomach; Stomach Ulcer; Thromboxane A2; Thromboxane-A Synthase; Transforming Growth Factor alpha; Vasoconstrictor Agents

Prostaglandins (PGs), hepatocyte growth factor (HGF), and induction of cyclooxygenase (PG synthetase, COX) play important roles in the repair process of gastric mucosa. We hypothesized that nonsteroidal anti-inflammatory drugs (NSAIDs), including indomethacin (IND), retard the healing of ulcers by suppressing these factors. In this study, we investigated the effects of cytokines, growth factors, and IND on production of PG and HGF, and induction of COX using cultured human gastric fibroblasts. Exogenous PGs significantly increased HGF production in a dose-dependent manner. Among various potential stimulants tested, interleukin-1 beta (IL-1 beta) dramatically increased PGE2 production and significantly stimulated HGF production. IL-1 beta induced COX-2 but not COX-1 protein. IND significantly reduced both basal and IL-1 beta-induced PGE2 release and HGF production. These results suggest that the IL-1 beta-PG-HGF pathway plays a role in the repair process of gastric mucosa. Further, NSAIDs may delay the healing of gastric mucosal ulcer, in part through suppression of HGF expression via inhibition of endogenous PG production.

Topics: Alprostadil; Anti-Inflammatory Agents, Non-Steroidal; Cholera Toxin; Cyclic AMP; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Fibroblasts; Gastric Mucosa; Gene Expression Regulation, Enzymologic; Hepatocyte Growth Factor; Humans; Indomethacin; Interleukin-1; Isoenzymes; Membrane Proteins; Peptic Ulcer; Prostaglandin Antagonists; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Stomach Ulcer; Transforming Growth Factor alpha; Tumor Necrosis Factor-alpha

Growth factors such as epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) have been shown to share common receptor (EGFR) and to accelerate ulcer healing due to stimulation of cell proliferation, but the time sequence of expression of EGF and TGF alpha during ulcer healing has not been investigated. In this study the rate of cell proliferation and the gastric secretion and gene expression of mRNA for EGF and TGF alpha were determined during ulcer healing.. Gastric ulcers were induced in 150 Wistar rats by serosal application of 100% acetic acid (ulcer area, 14 mm2). Some of these animals were also equipped with a gastric fistula for the assessment of gastric secretion during ulcer healing. The animals were killed 0, 2, 4, 6, or 8 days after ulcer induction, and the ulcer area was determined. The mucosal sections with gastric ulcer were immunostained for proliferating cell nuclear antigen (PCNA) and for immunoexpression of EGF, TGF alpha, and EGFR. The expression of mRNA EGF and mRNA TGF alpha was also determined in the ulcer margin by reverse transcriptase (RT) polymerase chain reaction (PCR) using specific primers.. Two, 4, 6, and 8 days after ulcer induction the gastric ulcer area was gradually reduced from the initial size (day 0) by 47%, 70%, 80%, and 87%, respectively, and this was accompanied by an increase in PCNA with its maximum on day 4. The gastric acid and pepsin secretion was significantly reduced by 75% and 79%, respectively, on day 2 after ulcer induction but then the secretion tended to return to normal value by day 8. The expression of EGF, TGF alpha, and EGFR was negligible on day 0 but increased significantly during the healing, reaching maximum on day 4. Expression of EGF mRNA was detected on days 2, 4, and 6, and that of TGF alpha mRNA on days 2, 4, 6, and 8 after ulcer induction, with the most intense signals for both transcripts observed on day 2.. 1) The enhancement in cell proliferation during ulcer healing may be mediated by increased release of EGF and TGF alpha; 2) the expression of EGF and TGF alpha mRNA precedes the overexpression of these growth factors at the ulcer margin during ulcer healing; and 3) the overexpression of growth factors coincides with the inhibition of gastric secretion and increased blood flow at the ulcer margin, indicating that these factors affect gastric secretion and blood flow in the course of ulcer healing.

Topics: Animals; Cell Division; Epidermal Growth Factor; ErbB Receptors; Female; Gastric Acid; Gastrins; Gene Expression; Immunohistochemistry; Male; Rats; Rats, Wistar; Regional Blood Flow; RNA, Messenger; Stomach; Stomach Ulcer; Time Factors; Transforming Growth Factor alpha; Wound Healing

Expression of members of the epidermal growth factor family, including epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), amphiregulin (AR), and Cripto, as well as their putative receptor, epidermal growth factor receptor (EGFR), was studied immunohistochemically in human gastric mucosa to evaluate their possible roles in cell proliferation of normal and regenerative gastric mucosa. We also examined the correlation betwen cell proliferation and EGFR by double immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and EGFR. In normal gastric mucosa, TGF-alpha, Cripto, and AR immunoreactivities were observed in the surface epithelial and parietal cells of gastric fundic glands, respectively. EGF immunoreactivity was not observed in any of normal mucosa examined. EGFR immunoreactivity was detected on foveolar cells in proliferative zones and in parietal cells. Double immunostaining revealed that EGFR immunoreactivity was distributed much more widely than PCNA immunoreactivity. PCNA positive epithelial cells adjacent to gastric ulcer margin expressed relatively intense EGFR but did not express any of the growth factors examined. On the other hand, relatively intense immunoreactivity of both TGF-alpha and Cripto was detected in PCNA-negative regenerative epithelium located distant from gastric ulcer margin. Relative immunoreactivity of AR in regenerative gastric epithelium associated with ulcer was not different from that in normal gastric mucosa. TGF-alpha, AR, and Cripto are considered to play important roles in normal gastric mucosal proliferation, and TGF-alpha and Cripto may be involved in ulcer healing, possibly via a paracrine mechanism.

Topics: Amphiregulin; Cell Division; EGF Family of Proteins; Epidermal Growth Factor; ErbB Receptors; Gastric Mucosa; Glycoproteins; GPI-Linked Proteins; Growth Substances; Humans; Immunoenzyme Techniques; Intercellular Signaling Peptides and Proteins; Membrane Glycoproteins; Neoplasm Proteins; Parietal Cells, Gastric; Proliferating Cell Nuclear Antigen; Stomach Ulcer; Transforming Growth Factor alpha; Wound Healing

Trefoil peptides are gut peptides that have been implicated in the repair of the gastric mucosa after injury. Previous studies suggest that epidermal growth factor (EGF) receptor ligands may induce the expression of trefoil peptides. Because transforming growth factor-alpha (TGF-alpha) is a major EGF receptor ligand in the gut, we tested the hypothesis that mice with a TGF-alpha null mutation (knockout) would have reduced trefoil peptide expression compared with wild-type controls after gastric ulceration. The rate of macroscopic ulcer healing was the same in knockout and wild-type mice. Spasmolytic polypeptide (SP) and intestinal trefoil factor (ITF) expression were quantified in tissue and gastric lavage. SP and ITF levels in tissue fell within 48 h of ulceration (P < 0.05), but secretion into gastric juice was unchanged. ITF peptide expression was increased (as was SP expression) in wild-type but not knockout mice 42 and 72 days after injury (P < 0.05). The induction of SP and ITF expression in the latter stages of injury repair has a TGF-alpha-dependent component and suggests a role for these peptides in gastric differentiation and cell positioning.

Topics: Animals; Duodenum; Gastric Fundus; Gastric Mucosa; Growth Substances; Heterozygote; Intestinal Mucosa; Mice; Mice, Inbred C57BL; Mice, Knockout; Mucins; Muscle Proteins; Neuropeptides; Peptide Biosynthesis; Peptides; RNA, Messenger; Stomach Ulcer; Time Factors; Transcription, Genetic; Transforming Growth Factor alpha; Trefoil Factor-2; Trefoil Factor-3

A model of gastric ulceration in the rat has been used to determine the expression of four messenger RNAs (mRNAs) encoding peptides considered to play active parts in the healing response. The trefoil peptides, rat spasmolytic polypeptide (rSP) and rat intestinal trefoil factor (rITF), along with epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) were the molecules studied. Ulceration was caused under anaesthesia by brief application of a liquid nitrogen-filled cryoprobe to the gastric serosal surface and RNA expression was monitored over the next 10 days. Each mRNA was quantified by ribonuclease protection assay, and mRNAs encoding rSP and rITF were localized within tissue sections by hybridization in situ with 35S antisense riboprobes. Ulceration induced the very rapid expression of first rSP and then rITF mRNA, whereas the mRNAs encoding EGF and TGF alpha increased at later times, with maxima recorded at 3 and 6 days, respectively. Hybridization in situ detected extensive rSP mRNA expression in the regenerative epithelia. The pronounced, but temporally different patterns of mRNA induction after ulceration suggest that the trefoil peptides may fulfil different and more immediate roles than the more 'traditional' healing proteins EGF and TGF alpha.

Topics: Animals; Cold Temperature; Epidermal Growth Factor; Gastric Mucosa; Gene Expression; Growth Substances; Immunoenzyme Techniques; Male; Mucins; Muscle Proteins; Neuropeptides; Peptide Biosynthesis; Peptides; Rats; Rats, Wistar; RNA, Messenger; Stomach Ulcer; Transforming Growth Factor alpha; Trefoil Factor-2; Trefoil Factor-3; Wound Healing

Transforming growth factor alpha (TGF) and epidermal growth factor (EGF) present in the gastric mucosa are polypeptides with similar biologic activity. This study compares the activity of TGF and EGF in the protection against injury by 100% ethanol and stress and in healing of acute gastric ulcerations. TGF and EGF (12.5-100 micrograms/kg-h) infused subcutaneously 30 min before and during ethanol or stress decreased mucosal lesions dose-dependently. The ID50 for ethanol- and stress-induced lesions after TGF were 40 and 70 micrograms/kg-h and after EGF 60 and 100 micrograms/kg-h. TGF and EGF infused subcutaneously into intact rats inhibited gastric acid secretion but did not affect the gastric blood flow or mucosal generation of prostaglandin E2 (PGE2). Both TGF and EGF also significantly enhanced the healing of stress-induced lesions and the restoration of DNA synthesis. Ethanol and stress reduced blood flow in the oxyntic mucosa by 68% and 51%, respectively, and this effect was partially reversed by EGF and TGF. Pretreatment with indomethacin (5 mg/kg intraperitoneally), which reduced mucosal generation of PGE2 by 85%, decreased in part the protection by TGF and EGF against ethanol-induced damage and virtually abolished the protective action of these peptides against stress-induced injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Disease; Animals; Blood Flow Velocity; Epidermal Growth Factor; Gastric Mucosa; Indomethacin; Rats; Rats, Wistar; Stomach Ulcer; Transforming Growth Factor alpha; Wound Healing