L Brigato

Analysis of Helicobacter pylori vacA and cagA genotypes and serum antibody profile in benign and malignant gastroduodenal diseases.

Background—Helicobacter pylori species comprise different strains, cytotoxic and non-cytotoxic, which can be identified on the basis of their genomic pattern. Aims—(1) To evaluate the polymorphism of the vacA gene and to ascertain whether thecagA gene is present in patients with gastric adenocarcinoma. (2) To study the anti-H pylori antibody profile using western blotting. Patients—Twenty one patients with gastric adenocarcinoma and 71 with H pyloriassociated benign disease (nine gastric ulcer, 29 duodenal ulcer, 25 antral gastritis, and eight duodenitis). Methods—The polymerase chain reaction was used to verify the presence or absence ofcagA and to study the polymorphism of vacA in gastric mucosal samples obtained during endoscopy for patients with benign diseases and at surgery for patients with gastric adenocarcinoma. Fasting sera were used to assess anti-H pylori antibodies against different H pyloriantigens by western blotting. Results—cagAgene and the allele s1 of vacAwere significantly less frequent in patients with antral gastritis (60% and 60%) compared with patients with gastric adenocarcinoma (94% and 100%) and with other non-malignant gastroduodenal diseases (93% and 87%) (χ2=16.01, p<0.001; and χ2=13.97, p<0.01). In patients with gastric adenocarcinoma, antibodies against a 74 kDa H pylori antigen were less frequently found than in patients with benign diseases. Conclusions—H pylori infection caused bycagApositive/vacA s1 strains is a frequent finding in patients with gastric adenocarcinoma. Prospective studies are needed to confirm whether the low incidence of positive serological response to the 74 kDa H pyloriantigen in patients with gastric adenocarcinoma is important.

An Unidentified Pancreatic Cancer Cell Product Alters Some Intracellular Pathways of Glucose Metabolism in Isolated Rat Hepatocytes

In this study we assessed whether conditioned media from a human pancreatic cancer cell line (MIA PaCa 2) can interfere with some intracellular pathways involved in glucose metabolism in isolated rat hepatocytes. The hepatocytes, isolated from Male Wistar rats, were incubated with MIA PaCa 2-conditioned or nonconditioned media. Conditioned and nonconditioned hepatocytes were run for 120 min in the presence or absence of insulin (100 mM) and were sampled at fixed time intervals. Supernatant glucose levels decreased to a similar extent over time in both conditioned and nonconditioned hepatocytes, while lactate levels significantly increased in nonconditioned hepatocytes with respect to conditioned hepatocytes. A pyruvate kinase activity increase was observed only in nonconditioned hepatocytes and was biphasic in nature, since this increased activity was detected both after a few and after 30 min following insulin stimulation. The cyclic AMP level increase was significantly higher in conditioned than in non-conditioned hepatocytes. It appears that MIA PaCa 2 cells produce a factor(s) that may interfere with one of the insulin-mediated intracellular pathways of glucose metabolism, namely, glycolysis. This detrimental effect on glycolysis is supported by the blunted rise in lactate concentration in the medium after the glucose challenge. This substance(s) probably transfers its signal inside the target cells, activating the adenylate cyclase pathway. These results support the hypothesis that pancreatic cancer is the cause rather than the consequence of diabetes mellitus.

Serum antibodies anti-H. pylori and anti-CagA: a comparison between four different assays.

The authors compare efficacy of two ELISA assays (one supplied by DIAMEDIX [Delta Biological s.r.l.], and the other by RADIM [RADIM I]) in detecting total anti‐H. pylori antibodies, and of two further ELISA methods (one supplied by EUROSPITAL [Helori CTX IgG] and the other by RADIM [RADIM 2]) in identifying anti‐CagA antibodies, using sera from 69 controls (20 adults and 49 children) and from 96 patients, obtained before endoscopy. Seventy‐three of the patients had H. pylori infection, while the remaining 23 were H. pylori negative (histology and polymerase chain reaction [PCR]). Fifty‐two of the H. pylori positive patients, had cagA‐positive strain infection, identified by PCR. The DIAMEDIX assay was found to be more sensitive (92%) than RADIM 1 (79%) in identifying H. pylori positive patients, irrespective of the infecting strain. On the other hand, the DIAMEDIX assay was less specific than RADIM 1 for H. pylori‐negative patients (43% vs. 83%). However, when patients already treated for H. pylori infection were excluded from the group of H. pylori‐negative patients, the DIAMEDIX assay had a specificity of 89%. In identifying anti‐CagA antibodies, the kit supplied by RADIM (RADIM 2) had a sensitivity of 90% and a specificity of 94%, whereas that supplied by EUROSPITAL had a sensitivity of 100% and a specificity of 76%. The performances of the two methods in the identification of anti‐CagA antibodies were found to be similar. The authors conclude that, in view of its high sensitivity, the DIAMEDIX assay may be useful in screening for H. pylori infection. J. Clin. Lab. Anal. 13:194–198, 1999.

Portal but not peripheral serum levels of interleukin 6 could interfere with glucose metabolism in patients with pancreatic cancer

UNLABELLED Interleukin 6 (IL-6), an autocrine growth factor for many tumors, seems to favour tumor spread to the liver. Our aims were first to evaluate the pattern of portal and systemic IL-6 levels in patients with pancreatic cancer (PC, n = 18) and chronic pancreatitis (CP, n = 22) compared with controls (CS, n = 20); and second, to ascertain whether there was any relation between IL-6 levels and tumor spread or PC-associated Diabetes mellitus. For all subjects, a fasting serum sample was obtained from a cubital vein; a portal serum sample was obtained from nine PC and three CP patients. In cubital and portal sera we measured IL-6, interleukin 1 beta (IL-1b), CA 19-9, c-reactive protein (CRP) and amylase. Systemic IL-6 levels were significantly higher in PC patients than in CS. In PC, portal IL-6 levels were significantly higher than the corresponding systemic values. The same pattern was found in the three CP patients, whereas IL-1b, CA 19-9, CRP and amylase portal levels were the same as systemic values. No correlation was found between PC stage and systemic or portal IL-6 levels. Portal IL-6 levels were correlated with the corresponding fasting serum glucose values. A significant correlation was found between IL-6 values and CRP, ALT, total bilirubin, GGT and creatinine, but not amylase. IN CONCLUSION (1) Portal IL-6, which is partly of pancreatic origin, is first metabolised in the liver; (2) Systemic IL-6 reflects hepatic and renal functions rather than local conditions in the pancreas; (3) IL-6 does not appear to influence PC spread; (4) IL-6, which is released in large amounts by the inflamed pancreas, may contribute to determining diabetes, thus interfering with the signal transducing pathways involved in glucose metabolism in liver cells.

Helicobacter pylori non-cytotoxic genotype enhances mucosal gastrin and mast cell tryptase.

AIMS: To determine the association, if any, between H pylori genotype and the gastric mucosal variations in the levels of gastrin, somatostatin, tryptase, and histamine. METHODS: 49 patients affected by duodenal ulcer and 48 by non-ulcer dyspepsia were studied. To identify the H pylori genotype, the presence of the cagA gene and vacA alleles m1, m2, s1, and s2 were analysed by polymerase chain reaction. Gastrin, somatostatin, tryptase, and histamine were measured in antral mucosal biopsies. RESULTS: 57 patients were infected with H pylori (30 with duodenal ulcer and 27 with non-ulcer dyspepsia). Gastrin and tryptase were increased in patients with H pylori infection, although the variations were statistically significant only for gastrin; somatostatin and histamine were not influenced by H pylori infection. In patients with non-ulcer dyspepsia the absence of the cagA gene and the presence of vacA alleles s2 and m2 were associated with higher values of tryptase and to a lesser extent of gastrin. These associations were not found in patients with duodenal ulcer. CONCLUSIONS: The cagA negative s2m2 strain of H pylori may be less dangerous for the gastric mucosa than other H pylori strains since it enhances tryptase production by gastric mucosal mast cells; this enzyme is thought to stimulate tissue turnover and favour wound healing.

Gastrin stimulates gastric mast cells in rabbits

In a previous study we demonstrated that in human gastric mucosa tryptase was localized only in mast cells and that its levels were correlated with serum gastrin, suggesting a link between gastrin action and mucosal mast cell function. The aim of the present study was to discover whether pentagastrin injection could stimulate gastric mucosal mast cells in rabbits. Ten female rabbits (group S) were injected s.c. with pentagastrin (10 μg/kg); another group of ten animals (group C) was injected s.c. with an equal volume of saline solution. One hour after the injection the rabbits were sacrificed and their stomachs removed. Antrum (A), corpus (C) and fundus (F) mucosal homogenates were assayed for total protein, tryptase, pepsinogen A (PGA), histamine and gastrin. Histamine tissue levels were significantly lower in group S than in group C in the antrum (Mann-Whitney test: U=82,P<0.01) and in the corpus (U=83,P<0.005). Tryptase levels were significantly higher in group S than in group C in all gastric areas (antrum: U=95,P<0.001; corpus: U=85,P<0.005 and fundus: U=75,P<0.05). Total protein PGA and gastrin did not vary significantly between groups. In group C, no signficant correlations were found among the five parameters. In group S, corpus tryptase was correlated with fundus tryptase (Spearmansr=0.831,P<0.01). The same relationship was observed for histamine (r=0.672,P<0.05). In group S, antrum gastrin was inversely correlated with antrum tryptase (r=0.903,P<0.001), and with corpus PGA (r=−0.806,P<0.05). This study demonstrates that bolus pentagastrin administration stimulates gastric mucosal mast cells in the rabbit.

Polymorphonuclear oxidative burst after Helicobacter pylori water extract stimulation is not influenced by the cytotoxic genotype but indicates infection and gastritis grade.

Abstract H. pylori-associated gastric mucosal inflammation is characterized by the presence of polymorphonuclear (PMN) leukocyte infiltrate, which is more severe when the infecting strain is cagA positive. After appropriate stimuli, such as bacterial products, PMN release large amounts of oxygen derived free radicals and proteases, to kill the bacterium. H. pylori seems to be particularly resistant to the oxidative machinery of PMN, which can in turn damage the host gastric mucosa. We evaluated peripheral PMN oxidative burst response after stimulation with water extracts from cagA positive (WEcagA+) or negative (WEcagA−) H. pylori strains in infected (n=31) and non-infected patients (n=32) in comparison with healthy controls (n=16); the influence of gastric mucosal inflammatory infiltrate and activity grade on PMN oxidative burst were also assessed. PMN oxidative burst was measured by FACS analysis. H. pylori water extracts were obtained from bacterial culture. H. pylori genotype was determined by means of the polymerase chain reaction. The PMN oxidative burst in H. pylori infected patients was significantly higher than that in H. pylori negative or healthy controls, no differences being found when the results following WEcagA+ and WEcagA-stimulation were compared. The difference in PMN oxidative burst obtained after WEcagA− and E. coli (standard stimulus for PMN oxidative burst) stimulation discriminated H. pylori infected from non-infected patients with a sensitivity of 90 % and a specificity of 97 %. The grade of PMN oxidative burst correlated with PMN infiltration grade of the gastric mucosa. Our findings allow to conclude that PMN oxidative burst activation by H. pylori WE is species-but not strain-correlated. PMN priming, probably consequent to the action of soluble mediators released by mononuclear cells, makes PMN hyper-responsive to H. pylori products, thus favoring the release in the gastric mucosa of infected patients of large amounts of oxygen-derived free radicals, which are not enough to eliminate the infection, but may contribute to damaging the gastric mucosa itself. Peripheral PMN oxidative burst response to H. pylori WE might furthermore be of help in diagnosing H. pylori infection.