IMPACT OF HELICOBACTER-PYLORI COLONIZATION ON IMMUNOREACTIVE EPIDERMAL GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-ALPHA IN GASTRIC-JUICE - ITS POTENTIAL PATHOGENETIC IMPLICATIONS

Epidermal growth factor (EGF), pivotal in mucosal protection, is partl y degraded proteolytically at low pH in the gastric milieu; gastric ac id secretion, on the other hand, remains influenced by H. pylori colon ization. The aim of this study, therefore, was to evaluate the impact of low pH and H. pylori colonization status on immunoreactive EGF and the other member of EGF-family, immunoreactive transforming growth fac tor-alpha (TGF-alpha). Eighteen patients with nonulcer dyspepsia (NUD) colonized by H. pylori and 55 NUD patients without H. pylori coloniza tion were investigated. Gastric juice samples were aspirated at the be ginning of the endoscopy procedure and immediately placed on ice, and their pH was recorded. The measurement of immunoreactive EGF and TGF-a lpha was performed using commercially available radioimmunoassays (RIA s) after adjustment of pH to neutral using an assay buffer. Statistica l analysis was performed using Sigma-Stat for Windows. The concentrati on of immunoreactive EGF in patients with NUD colonized by H. pylori w as 80% lower (P < 0.02) than in those without H. pylori and in both gr oups immunoreactive EGF was significantly lower when the pH of gastric juice was below 4.0. The concentration of immunoreactive EGF in H. py lori(+) and H. pylori(-) patients was similar when the pH of aspirated gastric juice was above 4.0. However, with gastric juice pH < 4.0, th e EGF concentration was 64% lower in H. pylori(+) patients than H. pyl ori(-) patients (P < 0.05). In general, the concentration of immunorea ctive TGF-alpha in gastric juice was unaffected by H. pylori colonizat ion or pH of gastric juice. It is concluded that: (1) significantly lo wer immunoreactive EGF concentrations in patients with pH below 4.0 in dicate that immunoreactive EGF but not immunoreactive TGF-alpha is aff ected by an acidic gastric milieu; (2) the further reduction of gastri c juice immunoreactive EGF at pH below 4.0 in patients colonized by H. pylori suggests that this microorganism may elaborate factors that ac celerate its proteolytic degradation or inhibit its rate of synthesis and/or secretion; and (3) this diminished content of immunoreactive EG F at low pH, especially in patients colonized by H. pylori, may facili tate the development and/or progression of mucosal damage.