Interactions of EGF and ornithine decarboxylase activity in the regulation of gastric mucus synthesis in cigarette smoke exposed rats

Cigarette smoking has been shown to aggravate ulceration and delay ulcer healing. Smokers had a lower level of mucus in their stomachs. In the present study, we examined whether cigarette smoke or its extract reduced mucus production through the suppression of epidermal growth factor (EGF) associated with the reduction of polyamine biosynthesis both in vivo and in vitro. Ornithine decarboxylase (ODC) activities and mucus synthesis were determined in rat gastric mucosa and in human MKN-28 cells. Incubation of MKN-28 cells with EGF (0.01-1.00 ng/mL) significantly increased mucus synthesis in vitro, which was accompanied by an increase of ODC activity. Removal of salivary glands decreased the circulated EGF level and induced a significant reduction of mucus-secreting layer thickness in the gastric mucosa. Cigarette smoke or its extract markedly decreased mucus synthesis in vivo and in vitro, both of which could be completely reversed by intravenous administration of EGF (20 microg/kg) in rats or co-incubation with EGF (1 and 2 ng/mL) in MKN-28 cells. However, ODC activities, which were suppressed by cigarette smoke or its extract, were unaffected by intravenous administration of EGF in rats, or only partially reversed by co-incubation with EGF in MKN-28 cells. These findings indicate that both EGF and ODC activity represent two different entities in the modulation of cigarette smoking on gastric mucus synthesis. The action of EGF on mucus synthesis may only be partially if not dependent on ODC activity in the stomach.     

Role of capsaicin sensory nerves and EGF in the healing of gastric ulcer in rats

Accumulating evidence indicates that capsaicin sensitive afferent fibers play a pivotal role not only in gastroprotection but also in ulcer healing. Denervation of capsaicin sensitive afferent fibers exerts an adverse action on these effects. However, whether such an action is mediated through a depression on epidermal growth factor (EGF) is undefined. In this study, the effects of denervation of sensory neurons with capsaicin (100 mg/kg, s.c.) on acetic acid-induced chronic gastric ulcers and their relationship with the EGF expression in salivary glands, serum and gastric mucosa were investigated. Capsaicin significantly increased ulcer size, decreased gastric mucosal cell proliferation at the ulcer margin, angiogenesis in the granulation tissue and also gastric mucus content. Ulcer induction by itself dramatically elevated EGF levels in salivary glands and serum on day 1 and 4, and also in the gastric mucosa on day 4. However, capsaicin completely abolished these effects. It is concluded that stimulation of EGF expression in salivary glands and serum may be one of the mechanisms by which capsaicin sensitive nerves contribute to the gastroprotective and ulcer healing actions in the stomach.     

Smoking and the pathogenesis of gastroduodenal ulcer – recent mechanistic update

Peptic ulcer is a common disorder of gastrointestinal system and its pathogenesis is multifactorial, where smoking and nicotine have significant adverse effects. Smoking and chronic nicotine treatment stimulate basal acid output which is more pronounced in the smokers having duodenal ulcer. This increased gastric acid secretion is mediated through the stimulation of H₂-receptor by histamine released after mast cell degranulation and due to the increase of the functional parietal cell volume or secretory capacity in smokers. Smoking and nicotine stimulate pepsinogen secretion also by increasing chief cell number or with an enhancement of their secretory capacity. Long-term nicotine treatment in rats also significantly decreases total mucus neck cell population and neck-cell mucus volume. Smoking also increases bile salt reflux rate and gastric bile salt concentration thereby increasing duodenogastric reflux that raises the risk of gastric ulcer in smokers. Smoking and nicotine not only induce ulceration, but they also potentiate ulceration caused by H. pylori, alcohol, nonsteroidal anti-inflammatory drugs or cold restrain stress. Polymorphonuclear neutrophils (PMN) play an important role in ulcerogenesis through oxidative damage of the mucosa by increasing the generation of reactive oxygen intermediates (ROI), which is potentiated by nicotine and smoking. Nicotine by a cAMP-protein kinase A signaling system elevates the endogenous vasopressin level, which plays an aggressive role in the development of gastroduodenal lesions. Smoking increases production of platelet activating factor (PAF) and endothelin, which are potent gastric ulcerogens. Cigarette smoking and nicotine reduce the level of circulating epidermal growth factor (EGF) and decrease the secretion of EGF from the salivary gland, which are necessary for gastric mucosal cell renewal. Nicotine also decreases prostaglandin generation in the gastric mucosa of smokers, thereby making the mucosa susceptible to ulceration. ROI generation and ROI-mediated gastric mucosal cell apoptosis are also considered to be important mechanism for aggravation of ulcer by cigarette smoke or nicotine. Both smoking and nicotine reduce angiogenesis in the gastric mucosa through inhibition of nitric oxide synthesis thereby arresting cell renewal process. Smoking or smoke extract impairs both spontaneous and drug-induced healing of ulcer. Smoke extract also inhibits gastric mucosal cell proliferation by reducing ornithine decarboxylase activity, which synthesises growth-promoting polyamines. It is concluded that gastric mucosal integrity is maintained by an interplay of some aggressive and defensive factors controlling apoptotic cell death and cell proliferation and smoking potentiates ulcer by disturbing this balance.     

Immunoreactivities for epidermal growth factor (EGF) and for EGF receptors in rats with gastric ulcers

Summary The present study was aimed at assessing whether epidermal growth factor (EGF) and its receptors are present in the gastric mucosa during the healing of gastric ulcers. Immunohistochemical, immunochemical and functional studies were performed in rats after induction of ulcers in the oxyntic mucosa. Controls, which included non-operated and sham-operated animals, displayed only rare cells in the bottom of the oxyntic glands showing EGF-like immunoreactivity. Within one day after ulcer induction, a markedly increased number of chief cells in undamaged mucosa showed intense staining. Concomitantly, there was an increased immunoreactivity for EGF receptors in the mucous neck cells. Maximal immunostaining for both compounds was observed at 3 days after ulcer induction; augmented staining was still demonstrable after 3 weeks. RIA revealed significantly increased EGF concentration in the oxyntic mucosa three days after ulcer induction, and at this stage stimulated gastric acid secretion, measured in a parallel group of chronic fistula rats, indicated significant inhibition. The transient increases in EGF-like and EGF receptor immunoreactivities may stimulate gland cell proliferation. The local release of EGF-like substances may also serve to reduce gastric acidity and thereby promote ulcer healing.     

Exposure to cigarette smoke increases apoptosis in the rat gastric mucosa through a reactive oxygen species-mediated and p53-independent pathway

Cigarette smoking is a major risk factor for gastric cancer and peptic ulcer. The aim of our study was to investigate the relationship between exposure to cigarette smoke and apoptosis in the rat gastric mucosa and the mechanism involved. Rats were exposed to different concentrations of cigarette smoke (0, 2, and 4%) once daily for a different number of 1 h periods (1, 3, 6, and 9 d). Apoptosis was identified by the terminal deoxy-transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) method and caspase-3 activity. The mucosal xanthine oxidase (XO) activity and p53 level were also measured. The results showed that exposure to cigarette smoke produced a time- and concentration-dependent increase in apoptosis in the rat gastric mucosa that was accompanied by an increase in XO activity. The increased apoptosis and XO activity could be detected after even a single exposure. In contrast, the level of p53 was elevated only in the later stage of cigarette smoke exposure. The apoptotic effect could be blocked by pretreatment with an XO inhibitor (allopurinol, 20 mg/kg intraperitoneally) or a hydroxyl free radical scavenger (DMSO, 0.2%, 1 ml/kg intravenously). However, neither of these treatments had any effect on the p53 level of the mucosa. In summary, we conclude that exposure to cigarette smoke can increase apoptosis in the rat gastric mucosa through a reactive oxygen species- (ROS) mediated and a p53-independent pathway.     

Antacid talcid activates in gastric mucosa genes encoding for EGF and its receptor. The molecular basis for its ulcer healing action.

In previous studies [Gut 35 (1994) 896-904], we demonstrated that antacid talcid (TAL) accelerates gastric ulcer healing and provides better quality of mucosal restoration within the scar than the omeprazole (OME). However, the mechanisms of TAL-induced ulcer healing are not clear. Since growth factors promote cell proliferation, re-epithelization, angiogenesis and ulcer healing, we studied whether TAL and/or OME affect expression of epidermal growth factor (EGF) and its receptors (EGF-R) in both normal and ulcerated gastric mucosae. Rats with or without acetic acid-induced gastric ulcers (n = 64) received i.g. twice daily 1 mL of either: A) placebo (PLA); B) TAL 100 mg; or C) OME 50 mg x kg(-1) for 14 d. Studies of gastric specimens: 1) ulcer size; 2) quantitative histology; 3) expression of EGF mRNAs was determined by RT/PCR; 4) gastric sections were immunostained with antibodies against EGF and its receptors. In non-ulcerated gastric mucosa of placebo or omeprazole treated group, EGF expression was minimal, while EGF-R was localized to few cells in the mucosal proliferative zone. Gastric ulceration triggered overexpression of EGF and its receptor in epithelial cells of the ulcer margin and scar. In ulcerated gastric mucosa TAL treatment significantly enhanced (versus PLA and omeprazole) expression of EGF and EGF-R. OME treatment reduced expression of EGF in ulcerated mucosa by 55 +/- 2% (P < 0.01). It is concluded that: 1) treatment with TAL activates genes for EGF and its receptor in normal and ulcerated gastric mucosae; 2) since EGF promotes growth of epithelial cells and their proliferation and migration, the above actions of TAL provide the mechanism for its ulcer healing action and improved (versus OME) quality of mucosal restoration.     

Role of salivary glands and epidermal growth factor (EGF) in gastric secretion and mucosal integrity in rats exposed to stress

EGF, produced mainly by salivary glands, inhibits gastric acid secretion, stimulates the proliferation of gastric mucosal cells and protects the mucosa against various ulcerogens, but its role in the pathogenesis of stress ulcerations is unknown. In this study, rats with intact or resected salivary glands were exposed to water immersion and restraint stress (WRS) without and with pretreatment with exogenous EGF or dimethyl PGE2 (dmPGE2) at doses which were shown previously to protect the mucosa against topical irritants. During 1.5-12 h of WRS, the formation of gastric ulcerations increased progressively with the duration of stress reaching peak after 6 h of stress and being significantly higher in rats with removed salivary glands than in intact animals. Gastric acid secretion and DNA synthesis in oxyntic mucosa declined with the duration of WRS, but after sialoadenectomy a significant increase in gastric acid secretion and a further decline in DNA synthesis were observed after WRS. EGF contents in the gastric lumen and the gastric mucosa were several times higher in rats subjected to stress than in control unstressed animals, indicating that stress causes an extensive release of EGF. Both exogenous EGF (17 nmol/kg/h) and dmPGE2 (143 nmol/kg) prevented, in part, the formation of gastric lesions, while inhibiting gastric acid secretion both in rats with intact or resected salivary glands. We conclude that water immersion and restraint stress is accompanied by an excessive release of EGF, which appears to attenuate gastric secretion, enhances the DNA synthesis and may limit the formation of stress-induced gastric ulcerations.     

Translocation of MAP (Erk-1 and -2) kinases to cell nuclei and activation of c-fos gene during healing of experimental gastric ulcers.

We examined localization of extracellular signal regulated kinases (Erk) 1 and 2, and c-fos mRNA expression in normal and ulcerated gastric mucosa in rats at 1, 3 and 7 days after gastric ulcer induction. In normal gastric mucosa immunofluorescence signal for Erk-1 and Erk-2 was detectable in surface epithelial, neck and some glandular cells. In gastric mucosa of the ulcer margin, almost all epithelial cells displayed strong Erk-1 and Erk-2 immunoreactivity in the basolateral membranes and the cytoplasm. In addition 19+/-3% of cells showed nuclear localization of the Erk-1 and -2 signal. The c-fos mRNA expression was increased by 790+/-14% and 220+/-10%, respectively in gastric ulcer at 3 and 7 days after ulcer induction. Since in in vitro models nuclear translocation of Erk-1 and -2 triggers cell proliferation, our finding indicates relevance of this mechanism to gastric ulcer healing.     

Cigarette smoke extracts delay wound healing in the stomach: involvement of polyamine synthesis

The association between cigarette smoking and peptic ulcer diseases has been well established. Ornithine decarboxylase (ODC) is crucial for the gastroprotective and mucosal growth promoting effects in gastric ulcer healing. The aim of this study is to elucidate the possible mechanism of how inhibition of ODC activity is involved in the delay of ulcer healing, if any, by cigarette smoke extracts (CSE). CSE were fractionated into chloroform extract (CE) and ethanol extract (EE). In in vivo study, rats with acetic acid-induced ulcers were given CE or EE intragastrically (2.5 or 5 mg/kg) once daily for 3 days. Ulcer sizes were significantly larger after CE or EE administration, followed by an increase in myeloperoxidase activity and a reduction in cell proliferation. However, both CSE stimulated the number of microvessels following the increase of basic fibroblast growth factor. In in vitro studies, the effect of CE or EE (10, 40, or 100 microg/ml) on cell migration and cell proliferation were measured using an in vitro wound model and [(3)H]-thymidine incorporation assay, respectively. Both CSE delayed cell migration and decreased cell proliferation, which were accompanied with a reduction in ODC activity. Exogenous spermidine (5 or 10 microM) could reverse the inhibitory action on cell proliferation and ODC activity induced by CSE. In conclusion, both CSE significantly delayed ulcer healing as a result of reduction in cell proliferation and cell migration. All these effects are, in part, related to the reduction of polyamine synthesis.     

Effect of local injection with basic fibroblast growth factor (BFGF) and neutralizing antibody to BFGF on gastric ulcer healing, gastric secretion, angiogenesis and gastric blood flow.

Exogenous administration of bFGF was shown to accelerate tissue repair predominantly due to an increase in the formation of new microvessels (angiogenesis) suggesting that bFGF plays an important role in healing of gastric ulcer. This study was designed: 1) to examine the effect of local application of bFGF with or without neutralizing antibody (NA) to bFGF and 2) to determine the role of gastric secretion, gastric blood flow (GBF) at the ulcer margin and angiogenesis during gastric ulcer healing with or without local application of NA, bFGF or the combination of NA and bFGF. Chronic gastric ulcers were induced in Wistar rats by subserosal application of acetic acid (ulcer area 28 mm2) and gastric secretion during ulcer healing was assessed using animals additionally equipped with chronic gastric fistulas. The bFGF without or with NA to bFGF (10 ng/100 microl]), irrelevant antibodies (rabbit IgG; 10 microg/100 microl) or vehicle (saline) were locally injected into the subserosa immediately upon ulcer induction (day 0) and at day 2. Rats with acetic acid ulcers without subserosal injections served as controls. At day 11, all animals were anaesthetized and GBF was determined at the ulcer base, ulcer margin as well as in intact mucosa using the H2-gas clearance technique and the area of gastric ulcers was measured by planimetry. Gastric mucosa with ulcer was excised and the percentage of area covered with blood vessels, the number of fibroblasts and the percentage of connective tissue at the ulcer edge was assessed by histology. The gastric ulcers were healed spontaneously in control vehicle-treated rats at day 11 and this was accompanied by the significant increase in the GBF and number of microvessels in the ulcer area. The gastric secretion was suppressed immediately after ulcer induction and increased significantly at day 2 and day 11 but failed to return to that recorded in intact animals. In contrast, local application of bFGF inhibited gastric acid and pepsin outputs at each study time intervals tested and this effect was reversed by addition of NA to bFGF. Locally applied bFGF accelerated significantly ulcer healing and this was accompanied by the greater rise in the GBF of ulcer margin and more marked increase in number of microvessels as compared to those in vehicle-treated rats. Subserosal application of NA to bFGF prolonged significantly the ulcer healing and this effect was accompanied by a significant fall in the GBF at the ulcer margin and a decrease in number of capillaries in ulcer bed without significant alteration in gastric acid and pepsin outputs. The ulcer healing effect of bFGF and accompanying increase in the GBF at ulcer margin and in thenumber of microvessels as well as inhibition of gastric acid secretion evoked by bFGF were significantly attenuated by the addition of NA to bFGF. The number of fibroblasts and the distribution of connective tissue did not differ between groups studied. We conclude that; 1) depletion of endogenous bFGF at the ulcer area by specific NA to bFGF delays healing of gastric ulcers, reduces angiogenesis of ulcer bed and impairs the microcirculatory effect of this growth factor at the ulcer margin indicating that the availability of bFGF in the ulcer area plays a crucial role in the ulcer healing through induction of angiogenesis; 2) this prominent antiulcer effect of locally applied bFGF depends, at least in part, upon the inhibition of acid secretion by this peptide.     

Cigarette smoke induces MUC5AC mucin overproduction via tumor necrosis factor-alpha-converting enzyme in human airway epithelial (NCI-H292) cells

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the U.S. Because cigarette smoking is so importantly implicated in the pathogenesis of COPD and because mucus hypersecretion plays such an important role in COPD, understanding of the mechanisms of smoking-induced mucus hypersecretion could lead to new therapies for COPD. Cigarette smoke causes mucin overproduction via EGF receptor (EGFR) in airway epithelial cells, but the cellular mechanism remains unknown. Airway epithelial cells contain EGFR proligands on their surfaces, which can be cleaved by metalloprotease and subsequently bind to EGFR resulting in mucin production. We hypothesize that TNF-alpha-converting enzyme (TACE) is activated by cigarette smoke, resulting in increased shedding of EGFR proligand, leading to EGFR phosphorylation and mucin induction in human airway epithelial (NCI-H292) cells. Here we show that cigarette smoke increases MUC5AC production in NCI-H292 cells, an effect that is prevented by an EGFR-neutralizing antibody and by specific knockdown of transforming growth factor-alpha (TGF-alpha) using small interfering RNA (siRNA) for TGF-alpha, implicating TGF-alpha-dependent EGFR activation in the responses. Cigarette smoke increases TGF-alpha shedding, EGFR phosphorylation, and mucin production, which are prevented by metalloprotease inhibitors (GM-6001 and TNF-alpha protease inhibitor-1) and by specific knockdown of TACE with TACE siRNA, implicating TACE in smoking-induced responses. Furthermore, pretreatment with antioxidants prevents smoking-induced TGF-alpha shedding and mucin production, suggesting that reactive oxygen species is involved in TACE activation. These results implicate TACE in smoking-induced mucin overproduction via the TACE-proligand-EGFR signal pathway in NCI-H292 cells.     

The effect of sialoadenectomy on gastric mucosal integrity in the rat: roles of epidermal growth factor and prostaglandin E2

Removal of the salivary glands (SALX) in rats has been shown to increase the susceptibility of gastric mucosa to ulcerogens. In the present study, we have investigated the role of specific salivary glands in this response. In addition, we have examined whether a functional link exists between the salivary glands, epidermal growth factor (EGF), and prostaglandin E2 (PGE2) by determining whether SALX decreases the responsiveness of the mucosa to the protective actions of either of both of these agents. Removal of the parotid salivary glands did not significantly increase ulceration in response to intragastric administration of 100% w/v ethanol. Animals were examined 60 min after ethanol administration. Removal of the submandibular-sublingual gland complexes was associated with a significant increase in the area of mucosal damage and a decrease in gastric pit depth in ethanol-treated animals when compared with sham-operated control rats. Furthermore, in both SALX and control animals, exogenous PGE2 and EGF resulted in a dose-dependent reduction in both groups of animals, although the protective effects of PGE2 and EGF were attenuated in SALX rats. PGE2 and EGF administered in combination resulted in the same degree of protection in both SALX and control rats. Sialoadenectomy resulted in a reduction in mucosal PGE2 synthesis. EGF administration did not consistently increase mucosal PGE2 synthesis. Conversely, sialoadenectomy did not reduce mucosal levels of EGF nor did exogenous PGE2 consistently increase salivary or mucosal content of EGF.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of polysaccharides from Angelica sinensis on gastric ulcer healing

Our previous study showed that a crude extract from Angelica sinensis (ASCE), which mainly consisted of polysaccharides, significantly promoted migration and proliferation of normal gastric epithelial cells. These results strongly suggest that ASCE has a direct wound healing effect on gastric mucosa. However, there is no report concerning the effect of ASCE on gastric ulcer healing in animal models. In this study, we found that ASCE promoted ulcer healing. The area of the ulcer was reduced. This was accompanied with a significant increase in mucus synthesis when compared with the control. Angiogenesis was inhibited by the treatment of ASCE. Cell proliferation, ODC and EGFR protein expression was not affected in this process. Thus, the mechanism of how ASCE accelerates ulcer healing in addition to its effect on mucus synthesis remains to be investigated.     

Evaluation of Acetic Acid-Induced Chronic Gastric Ulcer Healing by Propionyl-L-Carnitine Administration

The aim of our study was to investigate the healing effect of propionyl-L-carnitine (PLC) on chronic gastric ulcers and its underlying mechanisms. This study included rats with gastric ulcers induced by applying serosal glacial acetic acid. These rats were then given either saline (vehicle) or PLC at doses of 60 and 120 mg/kg, administered orally 3 days after ulcer induction for 14 consecutive days. Our study found that treatment with PLC resulted in a reduction of the gastric ulcer area, a faster rate of ulcer healing, and stimulated mucosal restoration. Additionally, the treatment with PLC reduced the number of Iba-1+ M1 macrophages while increasing the number of galectin-3+ M2 macrophages, as well as desmin+ microvessels, and α-SMA+ myofibroblasts in the gastric ulcer bed. The mRNA expression of COX-2, eNOS, TGF-β1, VEGFA, and EGF in the ulcerated gastric mucosa was greater in the PLC-treated groups compared with the vehicle-treated rats. In conclusion, these findings suggest that PLC treatment may accelerate gastric ulcer healing by stimulating mucosal reconstruction, macrophage polarization, angiogenesis, and fibroblast proliferation, as well as fibroblast-myofibroblast transition. This process is associated with the upregulation of TGF-β1, VEGFA, and EGF, as well as modulation of the cyclooxygenase/nitric oxide synthase systems.     

Growth factors in ulcer healing: lessons from recent studies.

Growth factors such as epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and more recently vascular endothelial growth factor (VEGF) have been used extensively to heal experimental gastric, duodenal and colonic ulcers in animal models. Encouraging results have been reported in clinical trials with EGF and bFGF. Since our laboratory has been involved with the initial ulcer healing studies with bFGF, PDGF and VEGF, we summarize here the major lessons from these studies and from literature data. These conclusions relate to the role of: 1) gastrointestinal (GI) secretion; 2) epithelial versus vascular components of the healing; 3) efficacy in the upper and lower GI tract; 4) quality of ulcer healing; as well as 5) the endogenous origin; and 6) molar potency of growth factors. Namely, among these growth factors only EGF inhibits gastric acid and stimulates duodenal bicarbonate secretion, while chronic administration of bFGF slightly enhances gastric secretion and PDGF has no effect demonstrating that potent ulcer healing can be achieved without influencing acid base and mucus secretion. This might be related to the fact that these growth factors stimulate with varying potency virtually all the cellular elements needed for ulcer healing, e.g., epithelial cell proliferation and migration by EGF > bFGF > PDGF, fibroblast proliferation by bFGF > PDGF and angiogenesis by VEGF > bFGF > PDGF > EGF. Conceptually, the most interesting results were obtained recently with VEGF which is virtually specific for angiogenesis, illustrating that stimulation of vascular factors is sufficient for ulcer healing because epithelial cells apparently spontaneously proliferate and migrate over a dense granulation tissue to complete the healing process. Since these growth factors directly stimulate the cell components of ulcer healing, it is probably not surprising that they are active in both upper and lower GI tract lesions, produce good quality of ulcer healing in comparison with spontaneously healed duodenal ulcers which are hypovascular and muscle regeneration is not part of natural healing. Contrary to other antiulcer drugs, these growth factors are endogenously derived and play a role in the natural history of ulcer healing, and since these relatively large peptides (18-45 kDa) are active in ng quantities, their molar potency is 2-7 million times superior to cimetidine-like drugs. Thus growth factors are endogenously derived very potent antiulcer drugs which act independently of GI secretion, are active in upper and lower GI lesions, and since they stimulate virtually all the cells of the healing process, they produce an excellent quality of ulcer healing.     

Relationship between vascular endothelial growth factor and angiogenesis in spontaneous and indomethacin-delayed healing of acetic acid-induced gastric ulcers in rats.

Angiogenesis is an important event for gastric ulcer healing. Vascular endothelial growth factor (VEGF) is known to be a potent stimulator of angiogenesis. This study consequently examined VEGF production, VEGF mRNA expression and angiogenesis during the spontaneous and indomethacin-delayed healing of acetic acid-induced ulcers in rats. The production of VEGF, taking place in the normal mucosa, was significantly elevated by ulceration. The mRNA expression of three isoforms of VEGF (VEGF188, VEGF164 and VEGF120) was also detected. Following the increase in VEGF production, angiogenesis was significantly promoted in the ulcer base. VEGF-immunoreactivity was observed in granulocytes, fibroblasts and regenerated epithelial cells. Indomethacin markedly inhibited prostaglandin E2 synthesis in the ulcer base, resulting in the prevention of ulcer healing. Angiogenesis was also significantly inhibited by indomethacin, but neither VEGF production nor VEGF mRNA expression was reduced. Such results suggest that VEGF might play a role in angiogenesis in the spontaneous healing of gastric ulcers in rats. However, the inhibition of angiogenesis in indomethacin-delayed ulcer healing is not explainable on VEGF expression.     

Solcoseryl in prevention of stress-induced gastric lesions and healing of chronic ulcers

Solcoseryl, a deproteinized extract of calf blood, protects the gastric mucosa against various topical irritants and enhances the healing of chronic gastric ulcerations but the mechanisms of these effects have been little studied. This study was designed to elucidate the active principle in Solcoseryl and to determine the role of prostaglandins (PG) and polyamines in the antiulcer properties of this agent. Using both, the radioimmunoassay and radioreceptor assay, EGF-like material was detected in Solcoseryl preparation. Solcoseryl given s.c. prevented the formation of stress-induced gastric lesions and this was accompanied by an increase in the generation of PGE2 in the gastric mucosa. Similar effects were obtained with EGF. Pretreatment with indomethacin, to suppress mucosal generation of prostaglandins (PG), greatly augmented stress-induced gastric ulcerations and antagonized the protection exerted by both Solcoseryl and EGF. Solcoseryl, like EGF, enhanced the healing of chronic gastro-duodenal ulcerations. This effect was abolished by the pretreatment with difluoromethylornithine, an inhibitor of ornithine decarboxylase, the key enzyme in the biosynthesis of polyamines. The healing effects of Solcoseryl and EGF was also reduced by prednisolone which decreased the angiogenesis in the granulation tissue in the ulcer area. These results indicate that Solcoseryl 1. contains EGF-like material, 2. displays the protective and ulcer healing effects similar to those of EGF and involving both PG and polyamines and 3. acts via similar mechanism as does EGF.     

Serum and Gastric Luminal Epidermal Growth Factor in Helicobacter Pylori—Associated Gastritis and Peptic Ulcer Disease

Background Helicobacter pylori is the cause of chronic (type B) gastritis, duodenal ulceration (DU), and gastric ulceration (GU). Smoking is associated with delayed ulcer healing. Epidermal growth factor (EGF) is produced in the salivary and Brunner's glands of the upper gastrointestinal tract, inhibits gastri acid secretion, and is a powerful mitogen. Materials and Methods. We sought to determine gastric luminal EGF (GL-EGF) in smokers and patients with Hp-associated DU and the effect of Hp eradication. Our aim was to determine GL-EGF in patients with GU and the effect of ulcer healing and to measure serum EGF in patients with Hp gastritis with or without DU disease. Results. GL-EGF was reduced in smokers compared to control (p= .008). Subjects with HP gastritis had reduced GL-EGF compared to controls (p= .0002). There was no difference in GL-EGF between Hp-positive subjects who had DU and those with chronic gastritis alone. Eradication of Hp from those patients with DU had no effect on the low levels of GL-EGF. There was no difference between GL-EGF in Hp gastritis alone and in Hp-associated active GU. GL-EGF fell after ulcer healing (p= .04), a difference confirmed by analysis of paired samples from patients before and after ulcer healing (p= .03). There was no difference in serum EGF between controls and subjects with Hp infection. There was no difference in serum EGF in subjects with DU-associated and non-ulcer-associated gastritis. Conclusions. Subjects with Hp gastritis, or those who smoke, had low concentrations of GL-EGF regardless of whether DU was present. Eradication of Hp did not return the concentrations of GL-EGF to normal in DU subjects. Individuals with Hp gastritis and inactive GU had low levels of GL-EGF compared to non-ulcer Hp infection. The relative increase in GL-EGF that occurred with ulceration of the gastric mucosa may have resulted from the development of an ulcer-associated cell lineage. Serum EGF did not play a role in the pathogenesis of Hp gastritis or of associated DU ulcer disease.     

Bacterial colonization and healing of gastric ulcers: the effects of epidermal growth factor

Experimental gastric ulcers are rapidly colonized by various bacteria, resulting in significantly impaired healing. Epidermal growth factor (EGF) is capable of preventing bacterial colonization of the healthy intestinal mucosa. In this study, we examined the possibility that EGF accelerates gastric ulcer healing by reducing bacterial colonization of the ulcer. Gastric ulcers were induced by serosal application of acetic acid. The effect of daily administration of EGF on ulcer healing and bacterial colonization was assessed and compared with the effect of daily treatment with broad-spectrum antibiotics. EGF administration reduced colonization levels and accelerated ulcer healing as effectively as the antibiotic treatment. EGF was without effect on acid secretion or neutrophil infiltration into the ulcer. Bacterial growth was not inhibited in the presence of EGF in vitro. These results demonstrate that EGF reduces bacterial colonization during an established infection of a compromised mucosal surface. This effect may contribute to the ability of EGF to accelerate gastric ulcer healing. This effect is acid independent and not due to an anti-inflammatory effect or to direct bactericidal actions.