Decreased salivary epidermal growth factor in rheumatoid disease: a possible mechanism for increased susceptibility to gastric ulceration

[Epidermal growth factor: a probable oral and digestive health protector]

The integrity of oral and digestive mucosa depend on many salivary components like the Epidermal Growth Factor (EGF). Sometimes indicative, sometimes stimulated or modulated factor of oral and digestive health, EGF appears as a clinical marker in neoplastic and inflammatory diseases. As cellular growth factor, it protects the digestive mucosa with stimulation of mucus production and with inhibition of gastric secretion. Equally implicated in healing process, it enhances this one, and determines, in patients, more or less sensibility to inflammatory damages. Its strategic place in various pathologies, as stomach ulcer and tumoral process, open research prospects with a real potential of repair and pronostic.

Alteration of gastric ulcerogenic and healing responses in rats with adjuvant-induced arthritis

Gastroenteropathy is the most common among patients who use non-steroidal anti-inflammatory drugs (NSAIDs) for treatment of inflammatory disorders. It is known that rheumatoid arthritic patients are more susceptible to NSAID-induced gastropathy than other NSAID users. This article reviewed our recent studies concerning the influence of arthritic conditions on gastric ulcerogenic response to NSAID and healing response of chronic gastric ulcers in rats. Gastric lesions induced by indomethacin, one of the conventional NSAIDs, were markedly aggravated in arthritic rats. This increased ulcerogenic response in arthritic rats was attributable to nitric oxide production due to up-regulation of inducible nitric oxide synthase. In arthritic rat stomachs, cyclooxygenase (COX)-2 was also up-regulated, where COX-2 selective inhibitors such as rofecoxib or celecoxib provoked gross lesions, although they caused no damage in normal rats. In addition, the healing of chronic gastric ulcers was also delayed in arthritic rats because of less expression of various growth factors such as basic fibroblast growth factors or insulin-like growth factors. Based on these findings, it is concluded that arthritic conditions alter the mucosal ulcerogenic and healing responses in the stomach. Especially, caution should be paid on the use of COX-2 selective inhibitors in rheumatoid arthritic patients.

Effect of Helicobacter pylori eradication on cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression during gastric adaptation to aspirin (ASA) in humans

Gastric adaptation to aspirin is impaired in Helicobacter pylori infection, but the mechanisms underlying this phenomenon are unclear. In this study, we compared gastric mucosal expression of iNOS and COX-2 during 14 days of aspirin ingestion in the same subjects before and 3 months after eradication of H. pylori. Compared to non-infected controls, mucosal expression of COX-2 and iNOS was enhanced before and 3 months after eradication of H. pylori. During aspirin ingestion, mucosal expression of COX-2 remained unchanged before eradication of H. pylori, but increased gradually after successful antimicrobial treatment. Independent of H. pylori status, expression of iNOS increased at the beginning of aspirin intake, but then returned to initial values. We conclude that COX-2 but not iNOS might be involved in gastric adaptation to aspirin in humans and that this mechanism appears to be impaired in H. pylori infection.

Protective action of capsaicin and chilli on haemorrhagic shock-induced gastric mucosal injury in the rat

Chilli and its pungent ingredient, capsaicin, have been shown to protect against experimental gastric mucosal injury induced by various necrotizing agents such as ethanol and aspirin and stress. We investigated the effect of capsaicin and long-term ingestion of chilli on haemorrhagic shock-induced gastric mucosal injury in the rat. Anaesthetized male Sprague-Dawley rats were subjected to haemorrhagic shock by withdrawing blood to reduce the mean arterial blood pressure to 30-40 mmHg with subsequent reinfusion of shed blood. This resulted in gastric mucosal injury with readily identifiable haemorrhagic lesions. Capsaicin (5 mg) administered prior to, but not after, haemorrhagic shock, significantly reduced the gastric mucosal injury in intact animals. Sensory ablation with capsaicin pretreatment (125 mg/kg bodyweight) abolished the gastroprotective effect afforded by capsaicin. Similarly, 4 week intake of chilli powder (360 mg daily) reduced the gastric mucosal injury in intact, but not in capsaicin-desensitized rats. Capsaicin and long-term chilli intake protected against haemorrhagic shock-induced gastric mucosal injury and the protection may be mediated by capsaicin-sensitive afferent neurons. Our studies are of potential significance in the context of stress ulcer disease in the human.

Helicobacter pylori-positive peptic ulcer patients do not adapt to aspirin

BACKGROUND

Recent studies indicate that eradication of Helicobacter pylori might prevent peptic ulcer formation in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs). On the other hand, gastric adaptation after repeated exposures to aspirin (ASA) is well documented but the influence of H. pylori on this process remains to be elucidated.

AIM

To compare gastric damage and adaptation following repeated exposures to ASA in a group of patients with H. pylori infection, before and after eradication of the bacterium, and in H. pylori-negative controls.

METHODS

Eight healthy volunteers without H. pylori infection and eight patients with duodenal ulcer (DU) history and H. pylori infection before and after H. pylori eradication were given ASA 2 g/day for a period of 14 days. Mucosal damage was evaluated by endoscopy and histology of biopsy samples. Gastric microbleeding, DNA synthesis in the gastric mucosa and mucosal expression, as well as luminal content of transforming growth factor-alpha (TGFalpha) were determined on days 0, 3, 7 and 14 of the ASA course.

RESULTS

In all patients aspirin-induced gastric damage reached a maximum on day 3. In H. pylori-positive patients, this damage was maintained at a similar level up to day 14, whereas in H. pylori-negative controls and H. pylori-eradicated patients this damage significantly lessened on day 14 and was accompanied by elevated DNA synthesis as well as increased mucosal expression and luminal release of TGFalpha.

Role of capsaicin sensitive nerves in epidermal growth factor effects on gastric mucosal injury and blood flow

BACKGROUND

Epidermal growth factor (EGF) and capsaicin protect against experimental gastric mucosal injury. Capsaicin exerts its gastroprotective effect by stimulating afferent neurones leading to release of calcitonin gene related peptide (CGRP) which causes gastric hyperaemia. EGF also causes gastric hyperaemia but whether it acts via capsaicin sensitive neurones is unknown.

AIMS

To assess the influence of: (1) capsaicin desensitisation on EGF effects on gastric mucosal injury and gastric mucosal blood flow: and (2) close arterial infusion of hCGRP8-379, a CGRP antagonist, on EGF effects on gastric mucosal blood flow.

METHODS

The absolute ethanol induced gastric mucosal injury model in the rat was used. Gastric mucosal damage was assessed by planimetry and light microscopy. Gastric mucosal blood flow was measured by laser Doppler flowmetry in a gastric chamber preparation.

RESULTS

Capsaicin desensitisation abolished the gastroprotective and gastric hyperaemic effects of EGF. Close arterial infusion of hCGRP8-37 antagonised the hyperaemic effect of both capsaicin and EGF.

CONCLUSION

Results show that EGF may exert its gastroprotective and gastric hyperaemic effects via capsaicin sensitive afferent neurones.

Infection of Helicobacter pylori in gastric adaptation to continued administration of aspirin in humans

BACKGROUND & AIMS

Involvement of Helicobacter pylori in aspirin-induced gastropathy and adaptation to aspirin remains unclear. The aim of this study was to compare gastric damage and adaptation after repeated exposures to acetylsalicylic acid in the same subjects before and after eradication of H. pylori.

METHODS

Before and after H. pylori eradication, 8 volunteers were given aspirin, 2 g/day during 14 days. Mucosal damage was evaluated by endoscopy and histological analysis of biopsy samples. Gastric microbleeding, DNA synthesis, prostaglandin E2 generation, and luminal contents of transforming growth factor alpha and its immunohistochemical expression were determined on days 0, 3, 7, and 14 of aspirin course.

RESULTS

In all subjects, aspirin-induced gastric damage that reached maximum on day 3. In H. pylori-positive subjects, this damage was maintained at a similar level up to day 14. After H. pylori eradication, the damage was significantly lessened both in endoscopy and histology at day 14 and accompanied by increased mucosal expression and luminal release of transforming growth factor alpha. Prostaglandin E2 generation was significantly greater in H. pylori-positive subjects than after H. pylori eradication, but aspirin treatment resulted in >90% reduction of this generation independent of H. pylori status.

CONCLUSIONS

Gastric adaptation to aspirin is impaired in H. pylori-positive subjects, but eradication of this bacterium restores this process.

Bovine milk inhibits proteolytic degradation of epidermal growth factor in human gastric and duodenal lumen

Degradation of epidermal growth factor (EGF) in human gastric and duodenal lumen was analyzed by incubating 125I-labeled or unlabeled human recombinant EGF with human gastric or duodenal luminal fluids in vitro. Degradation of EGF was assessed by measuring the generation of acid soluble radioactivity or by reversed-phase high-performance liquid chromatography (HPLC). Incubation with gastric luminal fluids resulted in a time- and dose-dependent degradation of labeled and unlabeled EGF at pH 2.5 but not at pH 7.5. Duodenal luminal fluids, on the other hand, degraded EGF at pH 7.5 but not at pH 2.5. The rate of degradation of unlabeled EGF in gastric luminal fluids was nearly 12-fold higher than the rate of degradation of labeled EGF, whereas only a slight difference in rates of degradation of labeled and unlabeled EGF was observed in duodenal luminal fluids. High-performance liquid chromatography analysis detected three major degradation products that eluted with retention time of 17.5 min, 20.0 min, and 22.5 min that was associated with a reduction of intact EGF (retention time 23.5 min). Defatted and decaseinated supernatant of bovine milk effectively inhibited the degradation of EGF in both gastric and duodenal luminal fluids. Dietary derived protease inhibitors, such as soya bean trypsin inhibitor, lima bean trypsin inhibitor, egg white protease inhibitor, and Bowman-Birk protease inhibitor prevented EGF degradation in duodenal luminal fluids but failed to inhibit EGF degradation in gastric luminal fluids. These results suggest that bovine milk may contain specific inhibitors that protect EGF from proteolytic degradation in human gastric lumen.

Decreased levels of salivary prostaglandin E2 and epidermal growth factor in recurrent aphthous stomatitis

Prostaglandin E2 and epidermal growth factor are two important cytoprotective compounds in saliva. This study investigated their salivary levels in controls and individuals with minor recurrent aphthous stomatitis. The development of recurrent aphthous stomatitis was divided into three stages: (1) early active stage (mucosal redness); (2) active stage (mucosal ulceration); (3) convalescent stage. Unstimulated mixed saliva was collected from each volunteer. Salivary prostaglandin E2 and epidermal growth factor concentrations were determined by radioimmunoassay. Their levels (mean +/- SEM) were significantly lower during the active stage of ulceration as compared to the control: (a) for prostaglandin E2, 200 +/- 55 versus 73 +/- 11 pg/mg salivary protein (p < 0.01), 447 +/- 123 versus 112 +/- 19 pg/ml saliva (p < 0.01), 215 +/- 30 versus 63 +/- 12 pg/min salivary flow (p < 0.01), control (n = 12) versus active stage (n = 15); (b) for epidermal growth factor, 1.09 +/- 0.17 versus 0.67 +/- 0.17 ng/mg salivary protein (p < 0.05); 2.51 +/- 0.53 versus 0.84 +/- 0.19 pg/ml saliva (p < 0.05), 1.24 +/- 0.26 versus 0.41 +/- 0.09 pg/min salivary flow (p < 0.05), control (n = 12) versus active stage (n = 12). Salivary prostaglandin E2 and epidermal growth factor showed stage-dependent alterations during the development of the stomatitis. The prostaglandin E2 concentration decreased significantly during the active stage of ulceration, and then increased significantly during the convalescent stage. However, the recovery of salivary epidermal growth factor after the ulceration was slower than that of the prostaglandin E2. It is suggested that the diminution of prostaglandin E2 and epidermal growth factor in the saliva may be associated with the ulcer development.

Role of epidermal growth factor in peptic ulcer healing

In recent years, increasing interest has been focused on peptide growth factors, and impressive progress has been made in the understanding of their role in tumor development and progression. However, evidence is mounting that peptides such as epidermal growth factor and transforming growth factor-alpha may be of much more physiological than pathological importance. This brief article is intended to give a rapid overview of the available data supporting a role for epidermal growth factor and its human homologue urogastrone in peptic ulcer healing.

Increased gastric juice epidermal growth factor after non-steroidal anti-inflammatory drug ingestion

Epidermal growth factor (EGF), present in saliva and gastric juice, is a potent mitogen and an important element of mucosal defence. Changes in salivary and gastric juice epidermal growth factor in response to non-steroidal anti-inflammatory drug (NSAIDs) ingestion were measured to assess the role of EGF in gastric mucosal adaptation to NSAIDs. Patients with arthritis underwent endoscopy with collection of saliva and gastric juice for EGF measurement, before and two weeks after continuous NSAID ingestion. During this period patients also received either the prostaglandin analogue misoprostol or placebo in addition to their NSAID. In the misoprostol group (n = 5) there was no observed mucosal damage and no change in either salivary or gastric juice EGF. In the placebo group (n = 10) three patients developed erosions. Salivary EGF did not change (mean (SEM) 3.02 (0.54) ng/ml v 2.80 (0.41) ng/ml) but gastric juice EGF increased from 0.42 (0.12) ng/ml to 0.69 (0.14) ng/ml (p < 0.05). This increased EGF could contribute to the increased cellular proliferation observed during NSAID ingestion and may represent an important mechanism underlying gastric mucosal adaptation.

The role of prolactin in the pathogenesis of autoimmune disease

Prolactin has emerged in recent years as a major regulator of both the maturation and the function of lymphocytes. Prolactin abnormalities, which include elevated serum levels, decreased bioactivity, abnormal circadian rhythm, and exaggerated secretion after stimulation by TRH, are associated with various autoimmune conditions in humans. Some animal experiments and observations in humans indicate that proiactin has an important role in the pathogenesis of autoimmune disease. There are several mechanisms through which prolactin could promote the development of autoimmunity. It is concluded that prolactin abnormalities alone are not likely to cause autoimmunity, but rather additional regulatory defects are perhaps also required for disease to develop.

A contemporary view of salivary research

The past 50 years of salivary research has been marked by a series of changing perceptions as new techniques and technologies have illuminated the complexities of the secretory mechanism, salivary composition, and function. The modern era began with the innovations of electrophoresis, chromatography, histochemistry, immunochemistry, electron microscopy, and microphysiology. The idea of saliva as primarily a digestive fluid composed of salts, amylase, and mucin was rapidly broadened to encompass a wide spectrum of protective proteins with the dual responsibility of protecting both hard and soft tissues. Characterization of the secretory IgA and nonimmunological antibacterial systems and the proteins responsible for the regulation of calcium and phosphate levels dominated the research in the 1960s and 1970s. An appreciation of the nature, formation, and role of the salivary pellicle and the interplay between bacterial adherence and agglutination provided a clinical thrust. Morphologists and physiologists redefined the secretory process on a molecular level. The 1980s saw the union of structure and function, both in terms of synthesis and release of the secretory products and their specific roles in the oral cavity in health and disease. The excitement of the 1990s is in the genetic control of processes and products, elucidating the mechanisms, and using the information to improve on nature: an era of great expectations and hubris. This article is essentially a personal guided tour through the past 50 years of salivary research.

Hormones in self tolerance and autoimmunity: a role in the pathogenesis of rheumatoid arthritis?

Recent studies indicate that pituitary hormones play an important role in immunoregulation. The evidence that endocrine abnormalities are associated with, and may contribute to the development of autoimmune disease is reviewed and discussed. Patients suffering from rheumatoid arthritis show a number of endocrine abnormalities that indicate altered pituitary function. The decreased bioactivity of prolactin and possible inadequate glucocorticoid response to inflammation found in patients may have an etiological role in rheumatoid arthritis. The further clarification of the possible role of endocrine factors in the etiology of autoimmune disease is needed urgently.

Role of salivary epidermal growth factor in the pathogenesis of Barrett's columnar lined oesophagus

Epidermal growth factor (EGF) is implicated in the regeneration of epithelial cells at the site of inflammation or ulceration in the gastrointestinal tract. Single parotid EGF concentration and production was studied in 64 patients with Barrett's columnar lined oesophagus (CLO), in 22 patients with severe reflux oesophagitis without columnar metaplasia and in 51 normal controls. In control patients, mean salivary EGF concentration was 2790 pg/ml (median 1450 pg/ml; range 450-16,500 pg/ml) and mean single parotid EGF production was 2550 pg/min (median 1750 pg/min; range 790-18,000 pg/min). Patients with severe reflux oesophagitis had a similar EGF concentration (mean 3112 pg/ml; median 1500 pg/ml; range 300-16,000 pg/ml) and production (mean 3100 pg/min; median 2200 pg/min; range 790-17,950 pg/min) to controls. Patients with CLO had a 62 per cent lower mean EGF concentration (mean 1197 pg/ml; median 640 pg/ml; range 233-4500 pg/ml) (P less than 0.001, Mann-Whitney U test) and a 60 per cent lower EGF production (mean 1254 pg/min; median 800 pg/min; range 170-3125 pg/min) (P less than 0.001, Mann-Whitney U test) than patients with severe reflux oesophagitis. A subpopulation with malignant change in CLO (n = 16) had a similar EGF concentration and production to the CLO group as a whole (mean 1240 and 1300 pg/min, respectively). Low salivary EGF levels are associated with Barrett's CLO but not with severe oesophagitis without columnar metaplasia. EGF levels do not identify those patients who will subsequently develop malignant change.