Chemotactic activity of Helicobacter pylori sonicate for human polymorphonuclear leucocytes and monocytes

Proinflammatory activation of neutrophils and monocytes by Helicobacter pylori in patients with different clinical presentations

Chronic Helicobacter pylori infection is associated with mucosal inflammation. The aim of the present study was to assess human neutrophil and monocyte activation by H. pylori strains obtained from patients with different clinical presentations. Bacterial sonicates from 12 strains were used to stimulate phagocyte upregulation of CD11b/CD18 adherence molecules assessed by fluorescence flow cytometry and oxidative burst responses assessed by chemiluminescence. A dose-dependent activation of CD11b/CD18 adherence molecules was observed with all strains on both neutrophils and monocytes. The activities were similar for strains from patients with duodenal ulceration and for strains from asymptomatic volunteers irrespective of histopathologic grades of the biopsy specimens from the antral mucosa. The neutrophil chemiluminescence response correlated with histopathologic severity. We conclude that upregulation of neutrophil and monocyte adherence molecules by H. pylori sonicates is not associated with clinical presentation of the infection.

The effect of Helicobacter pylori on neutrophil chemotaxis is independent of cagA

Sixteen Helicobacter pylori strains were studied in order to determine their neutrophil chemotactic activity and the association with the presence cagA gene. Neutrophil chemotactic activity was detected by a modified Boyden chamber method and the results were expressed in terms of chemotactic index (CI). The presence of cagA was determined by PCR. Of the 16 strains, eight were cagA+ and eight were cagA-. All of the isolated strains showed chemotactic activity. The mean value of CI of the patient group was significantly higher than the negative control (P < 0.01). The mean value of CI of zymosan-activated serum (P < 0.05) and the reference strain H. pylori NCTC 11637 (HP11637) (P < 0.01) was significantly higher than the patient group's mean value of CI. There were no statistical significance in the CI between cagA+ and cagA- strains (P > 0.05). It is concluded that H. pylori attracts neutrophils by chemotaxis, however, there is no association with cagA.

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

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. pyloriWE 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. pyloriWE might furthermore be of help in diagnosing H. pylori infection.

Role of gamma interferon in Helicobacter pylori-induced gastric inflammatory responses in a mouse model

The immune responses to Helicobacter pylori infection play important roles in gastroduodenal diseases. The contribution of gamma interferon (IFN-gamma) to the immune responses, especially to the induction of gastric inflammation and to protection from H. pylori infection, was investigated with IFN-gamma gene knockout (IFN-gamma-/-) mice. We first examined the colonizing abilities of eight H. pylori strains with a short-term infection test in order to select H. pylori strains which could colonize the mouse stomach. Only three strains (ATCC 43504, CPY2052, and HPK127) colonized C57BL/6 wild-type mice, although all of the strains except for ATCC 51110 could colonize IFN-gamma-/- mice. The number of H. pylori organisms colonizing the stomach in wild-type mice was lower than that in IFN-gamma-/- mice. Oral immunization with the CPY2052 sonicate and cholera toxin protected against infection with strain CPY2052 in both types of mouse. These findings suggested that IFN-gamma may play a protective role in H. pylori infection, although the degree of its protective ability was estimated to be low. In contrast, in a long-term infection test done to examine the contribution of IFN-gamma to gastric inflammation, CPY2052-infected wild-type mice developed a severe infiltration of mononuclear cells in the lamina propria and erosions in the gastric epithelium 15 months after infection, whereas CPY2052-infected IFN-gamma-/- mice showed no inflammatory symptoms. This result clearly demonstrated that IFN-gamma plays an important role in the induction of gastric inflammation caused by H. pylori infection.

Helicobacter pylori infection and the pathogenesis of duodenal ulceration

Helicobacter pylori is a gram-negative spiral bacterium confined to the habitat of gastric-type epithelium. H. pylori causes duodenal ulceration by a cumulative effect of antral predominant gastritis with increased acid secretion, consequent gastric metaplasia in the duodenum (a site of further colonization by H. pylori), duodenitis, reduced duodenal bicarbonate secretion, and mucosal damage. Bacterial factors influence outcome. Major determinants are the production of a vacuolating toxin and the presence of CagA, an immunodominant product of a nonconserved gene cagA, a marker for the cag pathogenicity island that encodes virulence genes involved in induction of epithelial chemokine responses. In ulcer patients the mucosal immune response is polarized to a T-helper-1 (Th1) cell-mediated response, which may contribute to mucosal damage. Eradication of H. pylori restores acid output to normal. Loss of both acid and bacteria halts gastroduodenitis and allows ulcer healing. Gastric metaplasia does not regress in the short term.

Hypotheses on the role of cytokines in peptic ulcer disease

Helicobacter pylori is the cause of chronic type B gastritis and occurs in almost all patients with duodenal ulcers. Infection with H. pylori is characterized by an increased production of several inflammatory cytokines. Increasing evidence suggests a central role of these cytokines in the pathogenesis of H. pylori-associated gastritis and peptic ulcer disease. Cytokines may be crucial in the recruitment and activation of inflammatory cells and in stimulation of gastrin release. In addition to their proinflammatory properties, cytokines may also inhibit the ulcer occurrence by stimulation of prostaglandins and somatostatin release and by direct impairment of acid secretion. The balance of these factors may determine the clinical outcome of H. pylori infection.

Induction of nitric oxide synthase in vivo and cell injury in rat duodenal epithelium by a water soluble extract of Helicobacter pylori

1. Helicobacter pylori (Hp) infection, which involves the gastric antrum and duodenal mucosa, may be involved in peptic ulceration by stimulating the local release of cytoxic or pro-inflammatory factors. 2. Nitric oxide (NO) is known to be cytotoxic at high concentration. The aim of the present study was therefore to investigate the ability of a water soluble extract of Hp to induce NO synthase in duodenal mucosa and epithelial cells following its administration in vivo in rats and determine its association with cell damage. 3. Administration of Hp water extract (4 ml kg(-1)) led to the expression of the calcium-independent inducible nitric oxide synthase (iNOS) after 4 h in the duodenum, determined as [14C]-arginine conversion to citrulline. 4. This iNOS activity was not reduced by pretreatment with anti-neutrophil serum (0.4 ml kg(-1), i.p., 3 h before challenge). However, dexamethasone pretreatment (1 mg kg(-1), i.v., 2 h before the extract), or administration of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 5 mg kg(-1), i.v., 2.5 h after the extract) reduced this activity. 5. Furthermore, iNOS was expressed in duodenal isolated epithelial cells 4 h after the i.v. challenge with the extract, at a time when the cellular viability was also reduced, as assessed by trypan blue exclusion. 6. Dexamethasone pretreatment, administration of L-NAME, or pretreatment with polymyxin B (1 mg kg(-1), i.v.) which binds endotoxin, reduced both the iNOS activity and epithelial cell damage. 7. The induction of NO synthase by the Hp extract thus results in duodenal epithelial cell injury and such actions could play a role in pathogenesis of peptic ulcer disease.

Studies on the gastric mucosal microcirculation. 2. Helicobacter pylori water soluble extracts induce platelet aggregation in the gastric mucosal microcirculation in vivo

BACKGROUND

The exact mechanisms by which Helicobacter pylori infection results in gastric mucosal injury are unclear.

AIMS

To assess in vivo whether H pylori extracts could initiate an inflammatory response in the rat gastric mucosal microcirculation.

METHODS

Extracts of H pylori, Escherichia coli, or distilled water were administered topically to the gastric mucosa of anaesthetised animals. Fluorescence in vivo microscopy assessed macromolecular leakage of labelled albumin from mucosal vessels, leucocyte adherence/rolling, and platelet activity for 90 minutes.

RESULTS

H pylori induced increases (p < 0.001) in adherent platelet thrombi and circulating platelet emboli after five and 15 minutes respectively. Adherent platelet thrombi (mean of four per field of view) remained significantly increased throughout the experiment, but circulating emboli (maximum of five at 30 minutes) decreased with time. Leucocyte adherence did not occur although early transient rolling was observed. An 11% increase (p < 0.02) in albumin leakage occurred after five minutes only. The induction of platelet aggregation was only observed following H pylori administration.

CONCLUSION

This in vivo study demonstrated the ability of H pylori extracts to promote platelet aggregation within gastric mucosal microvessels. Recruitment of leucocytes was not observed. The results suggest that the early events associated with H pylori infection are platelet aggregation with perhaps subsequent leucocyte recruitment by activated platelets.

Carbohydrate binding specificity of the neutrophil-activating protein of Helicobacter pylori

The possible interaction of the neutrophil-activating protein of Helicobacter pylori with target cell glycoconjugates was investigated by the binding of 125I-labeled recombinant protein to glycosphingolipids from human neutrophils in solid phase assays. Thereby, a distinct binding of the neutrophil-activating protein to four bands in the acid glycosphingolipid fraction from human neutrophils was detected, whereas no binding to the non-acid glycosphingolipids or polyglycosyl ceramides from these cells was obtained. When using glycosphingolipids not present in the cell membrane of human neutrophils, it was found that the neutrophil-activating protein also bound to sulfated glycosphingolipids as sulfatide and sulfated gangliotetraosyl ceramide. Comparison of the binding preferences of the protein to reference glycosphingolipids from other sources suggested that in human granulocytes, the neutrophil-activating protein of H. pylori preferentially recognizes glycoconjugates with a terminally unsubstituted NeuAcalpha3Galbeta4GlcNAcbeta3Galbeta4GlcNAcbeta sequence.

Catalase and superoxide dismutase secreted from Helicobacter pylori

BACKGROUND

Previously, we have reported that toxic oxidants produced by activated neutrophils play a pivotal role in the development of Helicobacter pylori-induced gastric mucosal damage. Microorganisms, however, are characterized by their ability to produce a variety of antioxidant enzymes. This study is designed to measure the oxygen radical scavenging enzymes, such as catalase and superoxide dismutase (SOD), and urease in the supernatant of H. pylori (NCTC11637) suspension.

MATERIALS AND METHODS

H. pylori was inoculated on a sheep blood agar plate and harvested. Bacterial suspensions (10(9) cfu/ml phosphate buffer) were washed twice and incubated at 37 degrees C for 1, 2, 12, and 24 hours or were sonicated in ice. Their supernatants were obtained by centrifugation and filtration. SOD activity was measured spectrophotometrically by the cytochrome c method. Catalase activity was assayed by the fall in absorbance at 240 nm as H2O2 is degraded. Urease activity was determined by measuring the release of ammonia using Berthelot reaction.

RESULTS

Activities of both SOD and catalase were detected in the supernatants of 1-hour microaerophilic incubation. Their activities were almost constant in 4-, 12-, and 24-hour microaerobic incubation or sonication. Urease activity was increased dramatically in proportion to the period of microaerobic incubation.

CONCLUSION

Although H. pylori possesses antioxidant as a constitutive compartment, the magnitude of its secretion was below the detectable level. It is not likely that SOD and catalase play a significant role for scavenging the oxidants from injured gastric mucosa, such as infiltrated leukocytes.

Superoxide dismutase activity in Helicobacter pylori-positive antral gastritis in children

Reactive oxygen metabolites have been implicated in gastric mucosal injuries. Superoxide dismutase, a scavenger of superoxide radical, is a key enzyme in gastric mucosal protection against several damaging factors. This study was aimed at investigating the relationship of superoxide dismutase activity to Helicobacter pylori-induced antral gastritis in children. Two groups of 11 children each, one positive and the other negative for Helicobacter pylori, were studied. Biopsies from the antrum and corpus were obtained for evaluation of Helicobacter pylori by CLOtest and histology as well as for superoxide dismutase activity (cytochrome c method). Erythrocytic and serum superoxide dismutase levels were determined as well. Superoxide dismutase activity was significantly higher only in the antrum of children with Helicobacter pylori-induced antral gastritis. There was no significant difference in superoxide dismutase activity in the corpus, erythrocytes, or serum of both groups. These findings may suggest a pathogenic relationship between the presence of Helicobacter pylori and oxygen radicals in inducing antral mucosal injury.

Manifestations of the local gastric immune response in gnotobiotic piglets infected with Helicobacter pylori

Helicobacter pylori, a human gastric bacterial pathogen, was inoculated into gnotobiotic piglets and manifestations of the resultant gastric inflammation was analyzed by in situ immunochemistry and flow cytometric analysis of isolated lamina propria leukocytes (LPL) and peripheral blood leukocytes (PBL) recovered from infected and control piglets. Gastric mucosa tissue sections from uninfected control piglets were essentially negative for cluster differentiation- (CD-) positive leukocytes. Failure to isolate significant numbers of LPL from the gastric lamina propria confirmed this observation. A local and systemic immune response occurs in piglets after infection with H. pylori. This is manifest by the appearance of cells associated with a local immune response in gastric mucosa. In gastric tissue sections from H. pylori-infected piglets, CD4-positive leukocytes were sparse and closely associated with developing lymphoid follicles whereas the CD8-positive cellular phenotype was abundant. The latter formed a continuous band in the lamina propria just above the muscularis mucosa. Perivascular accumulations of lymphocytes in the outer muscular tunic(s) were strongly positive for expression of CD8 antigen. Class II-positive cells were prominent in CD8 lymphocytic infiltrates, developing follicles and vascular endothelia but were uniformly absent from gastric epithelia even in sites overlying areas of immunocyte proliferation and infiltration. Leukocytes possessing the monocyte and granulocyte markers were rare. Plasma cells containing IgA were common in the periphery of developing lymphoid follicles or distributed as discrete foci around individual gastric pits. Fewer numbers of IgG- and IgM-positive plasma cells were identified. When the LPL flow cytometry data were compared with the flow cytometry data obtained from PBL in these same H. pylori-infected piglets, leukocytes bearing the CD8 marker predominated in LPL whereas leukocytes bearing the CD4-reactive and MHC class II markers predominated in PBL. Finally, local ELISA antibody responses were measured in mucosal explant culture supernatants and compared with in vivo antibody levels in sera, bile, and gastric juice. Antibody activity, specific for H. pylori, was detected in supermatants and serum in all three isotypes in actively infected piglets whereas gastric juice lacked antibodies. Gastric explants prepared from piglets in which infection had been successfully eradicated failed to produce local antibody into supermatant fluids. These data support the concept that the gastric inflammation observed is mediated by local immunological events.

Blood leukocyte differential in Helicobacter pylori infection

Helicobacter pylori causes a chronic infection in gastric mucosa, but its systemic effects are largely unknown. Our aim was to characterize the effect of H. pylori infection and gastric mucosal inflammation on the peripheral blood leukocyte count. An endoscopic series of 96 patients (40 men and 56 women), with a mean age of 62 years (range 49-80) was studied. Endoscopy with eight stepwise biopsies was performed and the occurrence of H. pylori was studied from sections stained with Warthin-Starry. The severity of inflammation in antral and body mucosa was estimated. The peripheral blood leukocyte count and differential count were determined by the automatic flow cytometric method. The total number of blood leukocytes and the numbers of lymphocytes and basophils were significantly increased in H. pylori-positive patients (N = 58), as compared with H. pylori-negative ones (N = 38). The total number of blood leukocytes correlated with the numbers of neutrophils, eosinophils, and mononuclear cells in the gastric mucosa. The number of basophils correlated with the number of mucosal neutrophils and mononuclear inflammatory cells. The results show that mucosal inflammation due to H. pylori infection is reflected in the amount of peripheral blood leukocytes. Basophilia suggests involvement of allergic mechanisms in H. pylori gastritis.

Plasmid DNA is protected against ultrasonic cavitation-induced damage when complexed to cationic liposomes

Cationic liposomes bound to plasmid DNA are currently used for in vitro and in vivo gene therapy applications, but such complexes readily form large, heterogeneous aggregates that are not appropriate for pharmaceutical development. More importantly, size heterogeneity makes studies focused on optimizing gene transfer to cells difficult to conduct or understand. For this reason we have evaluated the effect of microprobe sonication on these complexes in an effort to achieve process-controlled size homogeneity. Complexes were prepared using a 7.2 kb reporter plasmid and the following liposomal lipid combinations: DDAB/DOPE (50:50 mol %), DDAB/DOPE/PEG-PE (50:45:5 mol %), DDAB/EPC (50:50 mol %), DDAB/EPC/PEG-PE (50:45:5, 50:40:10, 50:35:15 mol %), DODAC/DOPE (50:50 mol %), and DODAC/EPC (50:50 mol %) (DDAB, dimethyldioctadecylammonium bromide; DOPE, dioleoylphosphatidylethanolamine; PEG-PE, monomethoxypolyethylene glycol2000 succinate- distearoylphosphatidylethanolamine; EPC, egg phosphatidylcholine; DODAC, dioleoyldimethylammonium chloride). The influence of complex composition and lipid:DNA ratio was evaluated. Particle size was determined before and after complexation and again after sonication using the quasi-elastic light scattering technique. DNA integrity was assessed via agarose gel electrophoresis. Finally, gene transfection was evaluated using CHO cells that were transfected in vitro with sonicated and unsonicated complexes. It is established in this study that size reduction can occur, but this is dependent on cationic and neutral lipid composition and, in some cases, lipid:DNA ratio. Surprisingly, the process of sonication leaves a significant percentage of the plasmid DNA intact and capable of in vitro transfection. This study shows that plasmid DNA can be protected from damage due to sonication by liposome complex formation. This may indicate that more common pharmaceutical methods for size reduction which subject particles to mechanical stress may be applicable in preparation of liposome/DNA formulations for in vivo application.

Grading Helicobacter pylori gastritis in dyspeptic patients

Helicobacter pylori-like organisms (Hp) and polymorphonuclear leucocytes (PMNs) in 2614 gastroduodenal biopsies from 602 patients with dyspepsia, in Al Ain, United Arab Emirates, between October 1990 and October 1992, were histologically graded to determine the prevalence of Hp gastritis and their utilization in the evaluation of treatment efficacy in these patients. Symptoms of functional dyspepsia included, in order of frequency, abdominal pain or discomfort, flatulence, burning sensation, regurgitation, fullness, nausea, vomiting, bloating and belching. The biopsies were paraffin embedded, sectioned and stained with hematoxylin and eosin (H and E) to grade the inflammation. In addition to H and E, several special stains including modified Giemsa (MG), Wharthin-Starry silver and cold Ziehl-Neelsen stains were utilized to clearly identify Hp organisms. Giemsa method was found to be superior to other special stains in visualizing the Hp organisms in paraffin sections, and was utilized in every case. Two immunohistochemical markers for B cells (CD20) and T cells (CD45RO) were utilized for labeling lymphocytes infiltrating the lamina propria of the gastroduodenal biopsies in formalin-fixed paraffin-embedded sections. H and E and MG stained sections were utilized to count PMNs and Hp, and were graded 0, 1, 2, and 3, corresponding to none, mild, moderate, and severe grades of the Sydney system for classification of gastritis, respectively. Of the total initial 2318 endoscopic biopsies, 98.8% of the patients had suitable biopsies for histologic evaluation. Unsuitable biopsies were recovered from patients with gastric carcinoma. Inflammation was seen in 98.5% of 595 patients with suitable biopsies. In 74.5% of these patients the inflammation was active; 37.5, 32.5 and 4.5% had mild, moderate and severe active inflammation, respectively. In the remaining 24% of the 595 patients, the gastritis was chronic without activity or atrophic changes. As many as 73.6% of the patients with suitable biopsies were Hp positive; 39.8, 29.1 and 4.7% had grades 1, 2 and 3 Hp, respectively. Intestinal metaplasia was found in 28.9% of the 602 patients, and was seen more often in Hp positive than Hp negative patients (34.5 vs 14%, P < 0.005, for d.f. = 1; chi 2 = 10.35). Of the Hp positive patients, 172 and 46 patients attended the first and second follow-up endoscopy visits, respectively. The triple treatment was composed of one dose of tinidazole (2gm), doxycycline, 200 mg initial dose and 100 mg daily for two weeks, and bismuth subcitrate (Gist-Brocades nv, Delft, The Netherlands), 2 tablets twice daily for 4 weeks. After triple drug treatment, eradication of Hp was accomplished, histologically, in 38.4 and 45.7% of the patients on first and second follow-up visits, respectively. Thus, the Sydney system-based grading scale provides an objective histological evaluation of Hp gastritis for accurate prevalence studies, and may prove to be of value in estimating treatment efficacy.

Immune and inflammatory responses to Helicobacter pylori infection

The gastroduodenal response to chronic Helicobacter pylori infection is characterized by the infiltration of plasma cells, lymphocytes, neutrophils and monocytes into the mucosa. Eradication studies have shown that this inflammatory response represents a specific reaction to the presence of H. pylori. As well as stimulating specific local T and B cell responses and a systemic antibody response, H. pylori infection also induces a local pro-inflammatory cytokine response. Interleukin-8 (IL-8), which is expressed and secreted by gastric epithelial cells, may be an important host mediator inducing neutrophil migration and activation. IL-8 mRNA and protein secretion in gastric epithelial cell lines can be up-regulated by the cytokines tumour necrosis factor-alpha and IL-1 and also by type I strains of H. pylori (expressing the vacuolating toxin and cytotoxin-associated protein, CagA). The gastric epithelium thus plays an active role in mucosal defence. Neutrophil activation and the production of reactive oxygen metabolites will be induced directly by bacterial factors and indirectly via host-derived cytokines, products of complement activation and bioactive lipids. Strain variation in the induction of both IL-8 from epithelial cells and the oxidative burst in neutrophils may be an important factor determining the extent of mucosal injury. There is now increasing evidence from both in vivo and in vitro studies that type I strains induce an enhanced inflammatory response and mucosal damage. An understanding of the bacterial mediators of mucosal inflammation is important in elucidating the role of chronic H. pylori infection in the pathogenesis of gastroduodenal disease.

Enhanced levels of chemiluminescence and platelet activating factor in urease-positive gastric ulcers

Helicobacter pylori are believed to play an important role in the formation of gastric ulcer in a syndrome characterized by a high urease activity. On the other hand, the production of oxygen radicals and platelet activating factor (PAF) is enhanced in gastric ulcers. The present study is designed to investigate the relationship between the different aspects of gastric mucosal injury, urease activity, oxygen radical production, and PAF content in gastric specimens. Biopsy specimens taken from 35 gastric ulcer patients were studied. Urease activity was detected by a rapid urease test (CLO). Oxygen radical production was measured as a value of luminol-dependent chemiluminescence (ChL) and PAF content was determined by radioimmunoassay in the biopsy samples. The CLO-positive rate was significantly higher in the gastric ulcer group in comparison with that in controls. ChL values and PAF content were significantly increased in gastric ulcers, especially in CLO-positive specimens. The CLO-positive rate, ChL values, and PAF content were also found to be increased at a distant site beyond the ulcer lesions. During the course of macroscopic ulcer healing of CLO-positive cases, the CLO positive level and the ChL values were not significantly decreased, although PAF content was significantly lower. Enhanced oxygen radical and PAF production were observed not only in the ulcer region but also at a distant site from the ulcer in the urease-positive gastric mucosa. The persistent enhancement of ChL values during the healing stage of urease-positive gastric ulcers suggests its involvement in the recurrence of gastric ulcers.

Severe gastric mucosal damage induced by NSAIDs in healthy subjects is associated with Helicobacter pylori infection and high levels of serum pepsinogens

Helicobacter pylori infection and NSAIDs are considered the two most important exogenous factors in ulcer disease. The interrelation between the two factors is not, however, clear. Moreover, serum pepsinogen has been suggested as a risk marker for the development of NSAID-induced gastrointestinal lesions. Fifty-one healthy volunteers, enrolled in a prospective, double-blind study carried out to evaluate gastrointestinal side effects of meloxicam and piroxicam, were analyzed to determine whether: (1) the prevalence of H. pylori correlates with the occurrence and severity of NSAID-induced gastrointestinal lesions, and (2) serum pepsinogen A and C levels could be used as markers of NSAID-induced mucosal damage. Upper endoscopy was performed by the same investigator before and after 28 days of treatment with placebo, meloxicam (7.5 mg/day and 15 mg/day), or piroxicam (20 mg/day). NSAID-induced damage was graded separately for hemorrhages and erosion ulcers according to Lanza's scale. There were no statistically significant differences in the prevalence of H. pylori in subjects with and without NSAID-induced mucosal lesions. However, there was a positive association between H. pylori infection and the severity of mucosal damage: total mean endoscopic score was 2.9 +/- 0.3 in H. pylori-positive subjects versus 1.6 +/- 0.5 in H. pylori-negative subjects (P < 0.05). Pepsinogen A and C levels increased from 55.3 +/- 3 to 149.4 +/- 15 and from 6.3 +/- 0.5 to 11.5 +/- 2.2, respectively (P < 0.05) in subjects who developed severe endoscopic injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of adhesion molecules on human granulocytes after stimulation with Helicobacter pylori membrane proteins: comparison with membrane proteins from other bacteria

Type B gastritis in its active form is characterized by a dense infiltration of the lamina propria with granulocytes. Since the bacterium Helicobacter pylori does not invade the epithelial barrier, a signaling pathway chemoattractive for granulocytes must exist across this mucosal boarder. One possible mechanism tested was whether granulocytes are directly activated by water-soluble membrane proteins (WSP) from H. pylori. These findings were compared with the effects of WSP from other bacteria (Helicobacter felis, Campylobacter jejuni, Escherichia coli, and Staphylococcus aureus). A unique activation pattern by H. pylori WSP was found. Like all other WSP tested, they induced an upregulation of CD11b but had no influence on CD11c and, most strikingly, CD62L expression. In contrast, E. coli WSP, e.g., not only induce a strong CD11b and CD11c expression but also lead to a loss in surface CD62L. The lack of CD62L shedding conserves rolling of granulocytes along the endothelium, creating a favorable precondition for granulocytes to stick more readily to activated endothelium after H. pylori stimulation via CD11b-CD54 receptor-counterreceptor interaction. This may explain why H. pylori infection is a very strong stimulus for granulocyte infiltration. The active fraction for the induction of CD11b on granulocytes is a heat- and protease-sensitive protein with a molecular mass between 30 and 100 kDa. One activation step involved may be the binding of WSP to CD15 determinants on granulocytes with subsequent induction of CD11b.

Characterization of a Helicobacter pylori neutrophil-activating protein

Helicobacter pylori-associated gastritis is mainly an inflammatory cell response. In earlier work we showed that activation of human neutrophils by a cell-free water extract of H. pylori is characterized by increased expression of neutrophil CD11b/CD18 and increased adhesiveness to endothelial cells. The work reported here indicates that the neutrophil-activating factor is a 150,000-molecular-weight protein (150K protein). Neutrophil proadhesive activity copurified with this protein, which is a polymer of identical 15K subunits. Specific antibody, prepared against the purified 15K subunit, neutralized the proadhesive activity of the pure protein and of water extracts obtained from different strains of H. pylori. The gene (napA) for this protein (termed HP-NAP, for H. pylori neutrophil-activating protein) was detected, by PCR amplification, in all of the H. pylori isolates tested; however, there was considerable strain variation in the level of expression of HP-NAP activity in vitro. HP-NAP could play an important role in the gastric inflammatory response to H. pylori infection.

Occurrence of gastric ulcers in gnotobiotic piglets colonized by Helicobacter pylori

Archival gastric tissues from 10 of 39 gnotobiotic piglets colonized with Helicobacter pylori 26695 contained stromal leukocytic inflammation along with ulcers and erosions. In contrast, gastric tissues from 54 archival control piglets were devoid of both inflammation and ulcers. These data confirm the hypothesis that H. pylori infection alone is ulcerogenic.

Neutrophil degranulation by Helicobacter pylori proteins

Mucosal biopsy specimens from patients with Helicobacter pylori infection in gastric antrum contain an increased amount of myeloperoxidase. This study was performed to elucidate the interaction of H pylori sonicate protein(s) and neutrophils concerning myeloperoxidase release. Neutrophil degranulation with myeloperoxidase release was examined in a direct stimulating assay. Priming activity of H pylori was examined after preincubating neutrophils in sonicate, either crude or modified by heat treatment, pronase inactivation and dialysis, and stimulating with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or serum opzonised zymosan (OZ). It was found that H pylori sonicate protein(s) stimulates neutrophil degranulation with myeloperoxidase release in a concentration dependent way. The activity was distinct from fMLP and capable of priming the subsequent fMLP and OZ response. Experiments with the modified bacterial sonicate suggest the activity is caused by a protein, but the findings show that non-protein molecules, for example, lipopolysaccarides were also part of the H pylori sonicate priming activity. The increased mucosal myeloperoxidase in H pylori associated disease can be a direct consequence of bacteria derived stimulation of inflammatory neutrophils.

Increased gastric production of interleukin-8 and tumour necrosis factor in patients with Helicobacter pylori infection

AIMS

To investigate the role of interleukin-8 (IL-8) and tumour necrosis factor (TNF) in patients infected with Helicobacter pylori.

METHODS

The study population comprised 52 patients with dyspepsia attending for upper gastrointestinal endoscopy. Of these patients, 35 were infected with H pylori. IL-8 and TNF concentrations in plasma, gastric juice, and gastric biopsy homogenate supernatant fluid were measured by radioimmunoassay and L929 cell bioassay, respectively.

RESULTS

The concentrations of IL-8 and TNF in gastric juice and gastric biopsy homogenates were substantially greater in patients infected with H pylori. In H pylori positive patients IL-8 concentrations in gastric juice and gastric biopsy homogenates were higher in those with moderate gastritis than in those with mild gastritis. There was a positive correlation between IL-8 and TNF concentrations in gastric juice and gastric biopsy homogenate supernatant fluid from H pylori positive patients. There were no significant differences between H pylori positive and negative patients with respect to IL-8 and TNF plasma concentrations.

CONCLUSION

This study suggests that increased gastric production of IL-8 and TNF may be implicated in the pathogenesis of H pylori associated gastroduodenal disease.

Helicobacter pylori induced interleukin-8 expression in gastric epithelial cells is associated with CagA positive phenotype

AIMS

To use a range of natural phenotypically variant strains of Helicobacter pylori with disparate CagA and VacA (vacuolating cytotoxin) expression to determine which bacterial factors are more closely associated with epithelial interleukin-8 (IL-8) induction.

METHODS

Gastric epithelial cells (AGS and KATO-3) were co-cultured with five H pylori strains which were variously shown to express the cagA gene/CagA protein, VacA and/or to exhibit biological cytotoxicity. Secreted IL-8 was assayed by enzyme leaked immunosorbent assay (ELISA) and IL-8 messenger RNA (mRNA) was assayed using a reverse transcription polymerase chain reaction based technique (RT-PCR).

RESULTS

Strains expressing CagA, including a variant strain (D931) which is non-cytotoxic and does not express the VacA protein, were found to upregulate epithelial IL-8 secretion and gene expression. In contrast, strains with no CagA expression, even in the presence of VacA and/or biological cytotoxicity, (G104, BA142), failed to induce IL-8 protein or mRNA above control values.

CONCLUSIONS

These results strongly support a role for H pylori CagA or coexpressed factors other than the cytotoxin in upregulation of gastric epithelial IL-8. Increased epithelial IL-8 secretion and concomitant neutrophil chemotaxis and activation in addition to direct cytotoxicity may be an important factor in tissue damage and ulceration.

Activation of phagocytes by Helicobacter pylori correlates with the clinical presentation of the gastric infection

Only a minority of subjects with Helicobacter pylori infection develop clinical gastroduodenal disease. It is unclear whether host factors or bacterial virulence properties contribute to the pathogenic mechanisms. We have previously demonstrated a 25-35-kDa protein with phagocyte stimulatory activity in bacterial sonicates. Protein preparations were made from 15 H. neutrophil and monocyte chemotaxis and chemiluminescence was assessed with cells from healthy donors in comparison with N-f-methionyl-leucyl-phenylalanine and C5a anaphylatoxin. The potency of bacterial protein(s) for induction of monocyte chemiluminescence was significantly higher for strains from ulcer patients (1 +/- 1 microgram/ml induced > or = twofold increase of control response) and chronic active gastritis (1 +/- 1 microgram/ml) compared with superficial gastritis (> 1,000 microgram/ml, p<0.05). Neutrophil activation was also significantly more potent with strains from duodenal ulcer disease. The chemotactic activity of bacterial preparations was not significantly different between the groups. We conclude that bacterial strains with pronounced activation of phagocytes are associated with the presence of clinical ulcer disease, supporting the existence of ulcerogenic strains.

Gastritis: terminology, etiology, and clinicopathological correlations: another biased view

The histological approach to gastritis, especially the chronic forms, has undergone a series of re-evaluations by different experts over the past decade, mainly because of the recognition of individual disease patterns that have specific clinical and epidemiological implications. The most spectacular of these was the discovery of Helicobacter pylori and its common gastritis, its relation to almost all duodenal peptic ulcers and to most gastric peptic ulcers, its potential as a precursor of first multifocal atrophic gastritis and later tubule-forming gastric carcinomas, and its status as a cause of gastric mucosal lymphomas. During this same decade other classes of gastric reaction and inflammations have been recognized, including chemical injury and lymphocytic gastritis. Also in the same decade the importance of non-steroidal anti-inflammatory drugs (NSAIDs) has emerged as a cause of gastric mucosal injuries. To add emphasis to all these discoveries, biopsies are being performed on stomachs in almost epidemic numbers and each biopsy specimen has the potential of having the features of one or more of these injuries as well as injuries that have yet to be described. To cope with this rapidly expanding gastric inflammatory informational extravaganza, pathologists need some way of dealing with the various entities comfortably and some method of cataloging them in ways that are understandable both to them and to the endoscopists with whom they work. However, if emerging data about the chronic gastritides are correct, it is conceivable that the need to diagnose them, from a strictly clinical standpoint, is limited. Either we may know what is in the biopsy specimen before we see it or what we see may not be important, although it may be intellectually challenging.

CagA/cytotoxic strains of Helicobacter pylori and interleukin-8 in gastric epithelial cell lines

AIMS

To investigate: (1) whether Helicobacter pylori directly induces interleukin-8 (IL-8) message expression and protein secretion in established gastric epithelial cell lines; and (2) if CagA/cytotoxin positive and negative strains of H pylori differ in their ability to induce epithelial IL-8.

METHODS

Gastric epithelial cell lines were co-cultured with H pylori NCTC 11637 and 10 clinical isolates (four cytotoxic, six non-cytotoxic) and secreted IL-8 was measured by enzyme linked immunosorbent assay (ELISA). Specific induction of gastric epithelial IL-8 mRNA was examined by reverse transcription and polymerase chain reaction (RT-PCR) amplification.

RESULTS

H pylori (NCTC 11637) induced IL-8 secretion from three gastric epithelial cell lines (KATO-3, ST42, AGS) but not from MKN 45 (gastric) or intestinal (SW480, HT29) cell lines. H mustelae did not stimulate IL-8 secretion from KATO-3, ST42, and AGS cells. H pylori induced IL-8 secretion was reduced by heat killing, sonication, freeze thawing or formalin fixation of the bacteria. CagA/cytotoxin positive strains of H pylori induced significantly higher IL-8 secretion than CagA/cytotoxin negative strains in the three positive gastric epithelial cell lines (KATO-3, ST42: p < 0.01; AGS: p < 0.02). A significant increase (p < 0.01) in the expression of IL-8 mRNA relative to G3PDH mRNA was observed in KATO-3 cells after three hours of co-culture with CagA/cytotoxin positive strains.

CONCLUSIONS

H pylori directly increases gastric epithelial IL-8 mRNA expression and IL-8 protein secretion in a strain specific manner. Induction of epithelial IL-8 by CagA/cytotoxin positive strains is likely to result in neutrophil chemotaxis and activation and thus mucosal damage. These observations on epithelial IL-8 may explain the association between CagA/cytotoxin positive strains and gastroduodenal disease.

Helicobacter pylori-induced microvascular protein leakage in rats: role of neutrophils, mast cells, and platelets

BACKGROUND/AIMS

Previous studies indicate that a water extract of Helicobacter pylori (HPE) can promote neutrophil-endothelial cell interactions in vivo and in vitro. The objectives of this study were to assess whether HPE alters the rate of albumin leakage in rat mesenteric venules and identify the factors that mediate the HPE-induced microvascular dysfunction.

METHODS

Intravital microscopy was used to continuously monitor leukocyte adherence and emigration and albumin leakage in rat mesenteric venules during superfusion with HPE.

RESULTS

HPE increased leukocyte adherence and emigration and microvascular albumin leakage. The enhanced albumin leak could be subdivided into two components: an early (within 10 minutes) and a later (within 30 minutes) phase. HPE also elicited perivenular mast cell degranulation and the formation of platelet-leukocyte aggregates within post-capillary venules. The HPE-induced early phase of albumin leakage was attenuated by pretreatment with a mast cell stabilizer. The HPE-induced late phase of albumin leakage was reduced by monoclonal antibodies directed against either CD11b/CD18 or intercellular adhesion molecule 1. A monoclonal antibody against P-selectin also inhibited the HPE-induced platelet-leukocyte aggregation and reduced the later phase of albumin leak.

CONCLUSIONS

HPE-induced microvascular dysfunction appears to be a consequence of interstitial and intravascular cell-cell interactions.

Relationship between infective load of Helicobacter pylori and reactive oxygen metabolite production in antral mucosa

Helicobacter pylori infection has been associated with stimulation of gastric mucosal reactive oxygen metabolite production. To provide further evidence of a causal relationship we looked for a dose-response relationship. We studied antral biopsy material from 110 patients. Quantitative H. pylori assessments were made using histologic and microbiologic methods. Reactive oxygen metabolite production was measured by luminol-dependent chemiluminescence. The usefulness of timed urease test colour changes as a guide to infective load was assessed. There was a positive association between mucosal reactive oxygen metabolite production and histologic (p = 0.002, n = 69) and microbiologic (Spearman's R = +0.6, p = 0.05, n = 18) quantitative H. pylori assessments. H. pylori infective load varied markedly over small areas (coefficient of repeatability of paired cultures (in colony-forming units/mg) = 1.9 x 10(6). Urease test timing correlated with histologic (p = 0.01) and microbiologic (p = 0.03) H. pylori quantitation. Histologically assessed mucosal damage was related to quantitative H. pylori assessment and to mucosal reactive oxygen metabolite production (p = 0.0001). These results support the hypothesis that H. pylori stimulates gastric mucosal reactive oxygen metabolite production and that this phenomenon is of pathogenic importance.

Helicobacter pylori stimulates antral mucosal reactive oxygen metabolite production in vivo

To determine if reactive oxygen metabolites have a pathogenic role in Helicobacter pylori (H pylori) related gastroduodenal disease, this study measured their production in antral mucosal biopsy specimens. Two related chemiluminescence techniques were used comparing H pylori positive (n = 105) and negative patients (n = 64) with a similar spectrum of macroscopic disease. After chemiluminescence assays, biopsy specimens were graded histologically. Increased luminol dependent chemiluminescence (detecting reactive oxygen metabolites through peroxidase catalysed reactions) was found in H pylori positive patients (median photon emission = 6.4 x 10(3)/min/mg wet weight (95% confidence intervals 3.6 to 9.9)) but not H pylori negative cases (-0.9 (-1.3 to -0.6)) (p = 0.0001). Similar results were found using lucigenin (which reacts directly with oxygen metabolites, particularly superoxide): (H pylori positive 0.9 (0.1 to 3.2); H pylori negative -1.2 (-3.4 to -0.6)) (p = 0.0003). Chemiluminescence was greater in H pylori positive compared with negative tissue when samples were grouped by equivalent macroscopic or microscopic damage. This difference was in part accounted for by a greater neutrophil infiltration in the H pylori positive mucosa, but when biopsy specimens with equivalent neutrophil infiltration could be compared directly, positive specimens gave greater chemiluminescence than negative. Smoking, drugs, and alcohol consumption had no independent effect. It is concluded that excess mucosal reactive oxygen metabolite production is associated with H pylori gastric antral infection and may be an important pathogenic mechanism. There is no evidence for reactive oxygen metabolite participation in the pathogenesis of gastric mucosal injury in cases unrelated to H pylori infection.

Helicobacter pylori-associated gastritis and dyspepsia. The influence on migrating motor complexes

Twenty-five patients with dyspepsia were included. In 19 patients with a median age of 48 (range, 20-72) years endoscopy and histologic examination of biopsy specimens from the antrum and corpus of the stomach showed Helicobacter pylori-positive gastritis as the only pathologic finding. In six patients with a median age of 42 (range, 32-56) years H. pylori-negative gastritis was found. After an overnight fast the patients underwent an ambulatory duodenal motility study for 6-8 h. Twenty-five young healthy men served as the control group. In patients with H. pylori-positive gastritis the duration of phase I of the migrating motor complex (MMC) was significantly shorter than in the control group. The median value was 33 min (quartiles, 24-49), and in controls 56 min (40-136 min). Phase II was of significantly longer duration, with a median value of 88 min (51-121 min) in the patient group and 39 min (22-89 min) in the control group. The duration of phase III and the whole MMC cycle was similar in the two groups. However, in the patients with H. pylori-negative gastritis the values of the duration of the different phases of the MMC were similar to those of the patients with H. pylori-positive gastritis. Nine patients were reexamined after eradication of the H. pylori infection, and the motility pattern had changed to the characteristics found in normals. In conclusion, the patients with dyspepsia and gastritis showed a disturbed motility pattern. The disturbance was similar whether there was colonization of H. pylori or not.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of the local immune response in the pathogenesis of peptic ulcer formation

Mucosal immune responses are designed to provide local protection against infection, without inducing excessive amounts of inflammation that would alter epithelial integrity or function. It has become clear that the epithelium not only serves as a barrier to exclude pathogens, but also initiates host responses to infection. Gastric epithelial cells infected with Helicobacter pylori can respond within hours to produce inflammatory mediators that recruit and activate neutrophils. The gastric epithelium can also be recognized by local T-cells, resulting in their activation and ability to induce epithelial damage. During infection with H. pylori, there is a remarkable increase in the level of local IgG antibodies, which may also recognize and damage the epithelium. Thus, activated neutrophils, T-cells and auto-antibodies may contribute to a weakened epithelial barrier that allows luminal acid and other factors to contribute to peptic ulceration. The epithelium appears to play a key role in the initiation of the local inflammatory and immune responses that may contribute to the more serious sequelae associated with H. pylori infection.

Interleukin-8 expression in Helicobacter pylori infected, normal, and neoplastic gastroduodenal mucosa

AIMS

To investigate the expression of interleukin-8 (IL-8) in Helicobacter pylori infected normal and neoplastic gastroduodenal mucosa, and in established gastric cancer cell lines.

METHODS

Immunofluorescence techniques were used to localise IL-8 in cryosections of gastric (n = 25) and duodenal (n = 17) endoscopic biopsy specimens an in resected gastric tumour tissue samples from 16 patients. Two gastric cancer cell lines (Kato 3 and MKN 45) were examined for IL-8 protein expression by immunofluorescence and for the presence of IL-8 mRNA by reverse transcription followed by the polymerase chain reaction (RT-PCR).

RESULTS

IL-8 was localised to the epithelium in histologically normal gastric mucosa, with particularly strong expression in the surface cells. IL-8 expression was also a feature of surface epithelium in the duodenal bulb, but was much reduced in the second part of the duodenum. In chronic H pylori-associated gastritis gastritis gastric epithelial IL-8 expression was increased and expression of IL-8 within the lamina propria was evident. By contrast, large areas of IL-8 negative epithelium were observed in the body mucosa of a subject with Ménétrier's disease. In gastric carcinoma the tumour cells were positive for IL-8. IL-8 was also detected by immunofluorescence in unstimulated Kato 3 and MKN 45 cells, and constitutive IL-8 gene expression in these cell lines was confirmed by detection of IL-8 mRNA by RT-PCR.

CONCLUSIONS

Immunoreactive IL-8, a potent neutrophil chemotactic and activating factor, is present in the epithelium of both normal and inflamed gastric mucosa with increased expression in the latter. There is site dependent variation in epithelial IL-8 expression within the gastroduodenal mucosa. The expression of the pro-inflammatory cytokine IL-8 in gastric carcinoma cells may influence peritumoural cellular infiltrates.

Mechanisms involved in Helicobacter pylori-induced inflammation

BACKGROUND

Helicobacter pylori infection is associated with mucosal inflammation. The aims of the present study were to assess whether a water extract of H. pylori promotes neutrophil (polymorphonuclear leukocyte [PMN]) adherence to endothelial cells and define the molecular basis of this adhesive interaction.

METHODS

Intravital microscopy was used to study leukocyte adhesive interactions in rat mesenteric venules in situ. PMN-endothelial cell adhesive interactions were studied in vitro using human PMNs and monolayers of human umbilical vein endothelial cells (HUVEC).

RESULTS

In vivo, superfusion of rat mesentery with the H. pylori extract increased leukocyte adhesion and emigration in venules. In vitro, adhesion of human PMNs to HUVEC was increased by the H. pylori extract in a concentration-dependent manner. Pretreatment of HUVEC alone with H. pylori extract had no effect on PMN adherence, whereas pretreatment of PMN alone significantly increased their adherence to HUVEC. The extract-induced adhesion was significantly diminished by monoclonal antibodies (MAb) directed against either CD11a, CD11b, or CD18 on neutrophils, and by MAbs against intercellular adhesion molecule-1 (ICAM-1), but not E- or P-selectin, on endothelial cells.

CONCLUSIONS

These studies suggest that products of H. pylori elicit gastrointestinal inflammation by promoting PMN adhesion to endothelial cells via CD11a/CD18- and CD11b/CD18-dependent interactions with ICAM-1.

Interaction of Helicobacter pylori (strain 151) and Campylobacter coli with human peripheral polymorphonuclear granulocytes

Helicobacter pylori associated gastritis is characterized by dense mucosal inflammatory infiltrations with predominantly neutrophilic granulocytes, together with a local and systemic immune response. Nevertheless, the natural course of the infection is chronic in nature, and active phagocytosis of H. pylori by mucosal granulocytes was only rarely observed. The aim of the present study was to investigate with electronmicroscopic methods the interaction of H. pylori with freshly harvested human peripheral granulocytes, with Campylobacter coli as control organism. Bacteria, either untreated or opsonized with complement or antiserum, were coincubated with phagocytes for up to 120 min. After defined time periods the following parameters were electronmicroscopically evaluated: i) internalization of bacteria., ii) morphological characteristics of bacteria and phagocytes, iii) decrease of lysosomes, and iv) by use of myeloperoxidase staining, the characteristics of phagolysosomal fusion. In the absence of complement, both organisms were internalized to a comparable extent. However, in contrast to C. coli, remarkable amounts of H. pylori cells remained extracellularly attached even after 120 min of coincubation, as well as internalized bacteria remained morphologically largely unimpaired. If complement was present, internalization and morphological destruction of H. pylori cells were significantly enhanced. The latter was characterized by rounding and swelling of H. pylori cells. It was already apparent in the extracellular space, and therefore probably induced by a complement effect, rather than by tee phagocytic action. Decrease of lysosomes, in general paralleled the degree of microbial uptake. Myeloperoxidase staining experiments furthermore showed an obviously regular consumption of lysosomal granules. However, if complement opsonization was excluded, lysosomal degranulation was not accompanied by a corresponding degradation of H. pylori cells, the latter indicating an at least partial resistance to phagocyte caused microbicidal mechanisms. In most of those cases ingested H. pylori cells were, in contrast to C. coli, surrounded by a rather "tight" phagosome. A possible explanation for this phenomenon could be a "leakage" of the phagosomal membrane, possibly caused by membranotoxic ammonia produced by the organism. If such an impairment of the phagocytic action would occur in vivo, it could lead to an impaired cellular defense, and therefore contribute to the chronic course of H. pylori infections.

Activation of human phagocytes by Helicobacter pylori. A novel interaction with neutrophils and monocytes distinct from that of N-formylated oligopeptides

Sonicate proteins from Helicobacter pylori activate human neutrophils and monocytes for chemotactic and oxidative burst responses. The molecular nature of this activity and its interaction with the phagocyte membrane is unknown. Cross-stimulation experiments were performed with human neutrophils and monocytes preincubated in H. pylori sonicate and subsequently stimulated with the established and characterised stimuli N-f-methionyl-leucyl-phenylalanine (fMLP), the complement split product C5a (in zymosan-activated serum, ZAS), and phorbol-myristate-acetate (PMA). Checkerboard experiments confirmed the sonicate to be truly chemotactic, whereas no chemokinetic activity was demonstrated. At high concentrations of sonicate (1 mg/ml), a depressed chemotactic and oxidative burst response was observed, whereas the viability was > 98%. At lower concentrations (0.01-0.1 mg/ml), only weak deactivation could be induced for monocytes, i.e. the cells had a normal function. With neutrophils, even low concentrations of sonicate depressed the oxidative burs responsiveness. However, the reduced activity was unrelated to the stimulus applied indicating that H. pylori protein(s) activate human neutrophils and monocytes by a membrane binding site distinct from that of previously described receptors.

Production of chemoattractant by Helicobacter pylori

Helicobacter pylori is present in the antral region of the stomach in a majority of patients with gastritis type B. The specific mechanism whereby the organism participates in the development of disease remains uncertain. Since the organism is not invasive, we postulate that H. pylori produces a chemoattractant that recruits inflammatory cells to the antral region of the stomach. H. pylori was grown under microaerophilic conditions at 37 degrees C for 72 hr in Brucella broth containing 1% fetal bovine serum. Culture supernates were harvested after removal of organisms by centrifugation and filtration. The putative chemoattractant in culture supernates as well as that which might be present endogenously in the growth medium (negative control) was assayed against human neutrophils (PMN) in modified Boyden blind-well chambers using 3.0-microns membranes. We found that H. pylori supernates are chemotactic and showed up to 130% activity when compared to the positive chemoattractant control (zymosan-activated serum, a source of C5a). Minimal activity was observed with virgin growth medium. The chemoattractant activity is proportional to the number of colony forming units (CFU) of H. pylori. Preliminary characterization of the activity shows that the chemoattractant is stable in a boiling water bath for 15 min, activity is lost within 1 hr in acid or alkali, and the chemotactic factor has an approximate molecular weight of 8500 daltons. The factor has no amino-sugar and is negative for the lipid A portion of lipopolysaccharide.(ABSTRACT TRUNCATED AT 250 WORDS)

Local and systemic immune responses in murine Helicobacter felis active chronic gastritis

Helicobacter felis inoculated per os into germfree mice and their conventional non-germfree counterparts caused a persistent chronic gastritis of approximately 1 year in duration. Mononuclear leukocytes were the predominant inflammatory cell throughout the study, although polymorphonuclear cell infiltrates were detected as well. Immunohistochemical analyses of gastric mucosa from H. felis-infected mice revealed the presence of mucosal B220+ cells coalescing into lymphoid follicles surrounded by aggregates of Thy-1.2+ T cells; CD4+, CD5+, and alpha beta T cells predominated in organized gastric mucosal and submucosal lymphoid tissue, and CD11b+ cells occurred frequently in the mucosa. Follicular B cells comprised immunoglobulin M+ (IgM+) and IgA+ cells. Numerous IgA-producing B cells were present in the gastric glands, the lamina propria, and gastric epithelium. Infected animals developed anti-H. felis serum IgM antibody responses up to 8 weeks postinfection and significant levels of IgG anti-H. felis antibody in serum, which remained elevated throughout the 50-week course of the study.

Incidence of Helicobacter pylori strains activating neutrophils in patients with peptic ulcer disease

A total of 61 human gastric isolates of Helicobacter pylori were studied for their ability to induce an oxidative burst in human neutrophils measured by luminol enhanced chemiluminescence. About one third of the strains induced strong and rapid chemiluminescence in neutrophils even without serum opsonins and agglutinated these cells on glass slides within two minutes. For other strains complement was required, although even then the reactions remained at a lower level. The activating and agglutinating property was bound to the cells, heat labile, and sensitive to several enzymes but resistant to acid. Strains possessing such activity were more common in patients with peptic ulcer disease than in patients with active chronic gastritis only (p = 0.0261, Fisher's exact test, two tailed). The activity shown might be a new indicator for ulcerogenic strains and could also partly explain the accumulation of neutrophils in the gastric mucosa during H pylori infection.

Gastric interleukin-8 and IgA IL-8 autoantibodies in Helicobacter pylori infection

Gastric infection with Helicobacter pylori is frequently characterized by neutrophil infiltration. The production of the neutrophil-activating peptide (NAP-1/IL-8) and mucosal IgA autoantibodies to IL-8 by human antral biopsies have been examined during short-term in vitro culture. Detectable IL-8 was secreted by 84% of H. pylori-negative patients with normal antral mucosa (range < 0.07-61.5 ng/mg biopsy protein, n = 19). Concentrations in 4 patients with reactive gastritis and 10 with inactive gastritis were not significantly different from subjects with normal mucosa. In H. pylori-positive patients with active gastritis and neutrophil infiltration into the epithelium (n = 17) IL-8 secretion was significantly increased relative to subjects with normal mucosa (P < 0.0001), inactive gastritis (P < 0.001) and reactive gastritis (P < 0.01). IL-8 concentrations in active gastritis were significantly correlated with the extent of epithelial surface degeneration (r = 0.64). IgA autoantibodies were present in 19 patients (13 active, 4 inactive gastritis) and concentrations were significantly correlated with IL-8 production (P < 0.001). Gastric synthesis of IL-8 is likely to be an important factor in regulating mucosal neutrophil infiltration and activation in patients with H. pylori infection. The local production of IgA antibodies to IL-8 may represent a down-regulatory response of the host to limit mucosal damage associated with a chronic bacterial infection.

Activation of human phagocyte oxidative metabolism by Helicobacter pylori

A characteristic feature of chronic antral gastritis is the abundant inflammatory response in close association with Helicobacter pylori, but the immunopathological mechanisms of tissue damage are unknown. Because reactive oxygen radicals have been implicated in the tissue damage of other chronic inflammatory disorders, we investigated the potential ability of H. pylori sonicate to influence the oxidative burst responsiveness of human polymorphonuclear leukocytes and monocytes. For both cell types, a dose-dependent stimulation in a chemiluminescence system was observed. Furthermore, preincubation in sonicate caused a marked priming of the cells to subsequent stimulation with the oligopeptide N-f-methionyl-leucyl-phenylalanine and phorbol-myristate-acetate. The sonicate activity was nondialysable, completely destroyed by proteinase and resistant to heat treatment. However, dialysis of boiled sonicate significantly reduced the activity, suggesting the breakdown of a larger molecule(s) to smaller fragments still biologically active. Preliminary experiments suggest that the activity is 25-35 kilodaltons. The demonstration of a protein with stimulatory activity for production of reactive oxygen radicals by human phagocytes may contribute to the understanding of the immunopathology associated with H. pylori infection.