Gastric helicobacter infection induces a Th2 phenotype but does not elevate serum cholesterol in mice lacking inducible nitric oxide synthase

Persistent Helicobacter felis infection in (C57BL/6 x 129SvEv)F1 mice induces chronic gastritis. Expression of inducible nitric oxide synthase (iNOS) is upregulated in response to Helicobacter infection. In this study, 20 10-week-old iNOS-/- mice and 20 wild-type [(C57BL/6 x 129SvEv)F1] mice were infected with H. felis by oral gavage and were assessed histologically and serologically at 32 weeks postinfection. Equal numbers of uninfected controls were sham inoculated. The mice were scored for severity of gastric inflammation, hyperplasia, glandular atrophy, and mucous metaplasia in the corpus and for the level of helicobacter colonization. The immunoglobulin G1 (IgG1), IgG2a, and IgG2c antibody responses to H. felis were determined. As a secondary measure, serum cholesterol levels were assessed. iNOS-/- mice have a propensity for increased serum cholesterol, and although controversial, several human epidemiologic studies have demonstrated an association between Helicobacter infection and several risk factors for cardiovascular disease, including elevated serum cholesterol. Nevertheless, no differences in serum cholesterol levels were observed between the H. felis-infected and -uninfected iNOS-/- mice in this study. The uninfected animals had minimal to no gastric pathology. The gastric pathology scores for the infected animals were reduced significantly in the iNOS-deficient mice relative to those for the wild-type mice (all P <0.01). Helicobacter-infected iNOS-/- mice had chronic lymphoid infiltration and negligible to mild glandular atrophy and mucous metaplasia in the fundic mucosa, while H. felis-infected wild-type mice had severe atrophic and metaplastic mucosal changes. The atrophic gastritis in the infected wild-type mice, particularly the female mice, was also accompanied by greater granulocytic infiltration, antral hyperplasia, and diminished antral colonization, unlike that in the infected iNOS-/- mice. iNOS-/- mice developed significantly lower Th1-associated IgG2c antibody responses to H. felis (P <0.0003); the Th2-associated IgG1 responses were similar (P=0.09), suggesting a greater effect of the iNOS defect on Th1 responses. H. felis colonization was significantly greater in the iNOS-deficient mice. These findings are indicative of an impaired Th1 component of the H. felis-induced inflammatory response when the influence of iNOS is removed.     

Helicobacter pylori gastritis in cats with long-term natural infection as a model of human disease

A natural infection with Helicobacter pylori (H. pylori) in domestic cats (Felis cattus) less than 2 years of age has been well described in a closed colony of animals. Six cats from this colony that were serially evaluated by culture, polymerase chain reaction, and light and electron microscopy for a period of 3 years demonstrated persistent gastric colonization with a single cag(-) vac(+) strain of H. pylori. In these cats, as well as five other 5- to 6-year-old cats that were examined, a long-term infection resulted in chronic diffuse lymphofollicular atrophic gastritis with areas of mucosal dysplasia in the antrum and predominantly midsuperficial gastritis in the body and cardia. Topographically, the distribution of lesions was similar in both young and older cats and closely resembled that found in humans, with the most severe changes occurring in the gastric antrum. Few granulocytes and no significant elevation in mast cells were seen in older H. pylori-infected cats compared with uninfected controls; however, marked increases in interepithelial globule leukocytes and numerous active mucosal lymphoid follicles were present in infected animals. Indices of gastritis were significantly greater in older infected cats when compared with uninfected controls and younger cats (P < 0.05). The antral cell proliferation index of infected older cats was significantly (P = 0.021) greater than that of uninfected controls. Apoptotic indices of the gastric antrum and body of infected cats were significantly (P = 0.01) increased versus controls. Chronic infection with H. pylori in cats shares many features of long-term H. pylori infection in humans, including the development of preneoplastic processes. This similarity provides useful, comparative insights into host-pathogen interactions.     

Characterization of feline Helicobacter pylori strains and associated gastritis in a colony of domestic cats.

Twenty-four young adult domestic cats from a commercial vendor were found to be infected with Helicobacter pylori. Histopathologic analyses, selected electron microscopy, and urease mapping were performed on mucosal samples collected from the cardias and fundi, bodies, and antra of these cats' stomachs. H. pylori organisms were abundant in all areas of the stomach on the basis of histologic evaluation and urease mapping. H. pylori infection was associated with a moderate to severe lymphofollicular gastritis in 21 of 24 cats (88%). The gastritis was most pronounced in the antral region and consisted mainly of multifocal lymphoplasmacytic follicular infiltrates in the deep mucosa. The severity of gastritis in the antrum corresponded to high numbers of H. pylori there on the basis of the use of the urease assay as an indicator of H. pylori colonization. Ten of 24 cats (42%) also had small to moderate numbers of eosinophils in the gastric mucosa. All 24 cats had gastric lymphoid follicles, with follicles being most prevalent in the antrum. Electron microscopy of gastric tissue revealed numerous H. pylori organisms, some of which were closely adhered to the mucosal epithelium. Human H. pylori gene-specific primers to ureA and ureB amplified products of similar sizes from H. pylori cat isolates. Digestion of the products with restriction enzymes resulted in fragments characteristic of the restriction fragment length polymorphism patterns of H. pylori isolates from humans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative evaluation of inflammatory and immune responses in the early stages of chronic Helicobacter pylori infection

The early consequences of Helicobacter pylori infection and the role of bacterial virulence determinants in disease outcome remain to be established. The present study sought to measure the development of host inflammatory and immune responses and their relationship to the putative bacterial virulence factors cag pathogenicity island (cagPAI), vacA allele, and oipA in combination with bacterial colonization density in a feline model of the early stages of H. pylori infection. Gastric tissues obtained from infected and uninfected cats were evaluated for H. pylori ureB, cagPAI, vacA allele, and oipA and colonization density (urease, histology, and real-time PCR). Inflammation was assessed by measuring mRNA upregulation of gamma interferon (IFN-gamma), interleukin (IL)-1 alpha, IL-1 beta, IL-4, IL-6, IL-8, IL-10, and IL-12 p40 and histopathology. The mucosal immune response was characterized by morphometric analysis of lymphoid follicles and by differentiating lymphocyte populations with antibodies against surface markers. Infecting H. pylori strains were positive for vacAs1 but lacked cagPAI and an active oipA gene. Colonization density was uniform throughout the stomach. Upregulation of IFN-gamma, IL-1 alpha, IL-1 beta, and IL-8 and increased severity of inflammatory infiltrates and fibrosis were observed in infected cats. The median number and total area of lymphoid aggregates were 5 and 10 times greater, respectively, in the stomachs of infected than uninfected cats. Secondary lymphoid follicles in uninfected cats were rare and positive for BLA.36 and B220 but negative for CD3 and CD79 alpha, whereas in infected cats they were frequent and positive for BLA.36, CD79 alpha, and CD3 but negative for B220. Upregulation of IFN-gamma, IL-1 alpha, IL-1 beta, and IL-8 and marked hyperplasia of secondary lymphoid follicles are early consequences of H. pylori infection in cats. The response appears to be similar to that of infected people, particularly children, can develop independently of the pathogenicity factors cagPAI and oipA, and is not correlated with the degree of colonization density or urease activity.     

Helicobacter pylori-induced gastritis in the domestic cat.

Helicobacter pylori has been cultured from the inflamed gastric mucosae of naturally infected cats; the lesions in H. pylori-infected cat stomachs mimic many of the features seen in H. pylori-infected human stomachs. To determine whether H. pylori-negative specific-pathogen-free cats with normal gastric mucosae were susceptible to colonization by this bacterium and whether gastritis developed after infections, four H. pylori-negative cats treated with cimetidine were orally dosed three times with 3 ml (1.5 x 10(8) CFU/ml) of H. pylori every 4 days. All four cats became persistently colonized as determined by gastric cultures and PCRs from serial gastric biopsy samples and necropsy samples at 7 months postinfection. H. pylori was not isolated from the two control cats, nor were their gastric tissues positive by PCR; one of the two cats had a few focal lymphocytic aggregates in the body submucosa, whereas the second cat had a normal gastric mucosa. All four H. pylori-infected cats had multifocal gastritis consisting of lymphoid aggregates plus multiple large lymphoid nodules, which were most noticeable in the antral mucosa. In addition, one H. pylori-infected cat had a moderate diffuse infiltration of polymorphonuclear leukocytes in the subglandular region of the antrum. H. pylori-like organisms were focally distributed in glandular crypts of the antrum. Two of the H. pylori-infected cats had significant (eightfold) increases over baseline in levels of immunoglobulin G H. pylori serum antibody. The H. pylori isolates from the four experimentally infected cats had restriction fragment length polymorphism patterns specific for the flaA gene that were identical to those of the inoculating strain. H. pylori readily colonizes the cat stomach and produces persistent gastritis.     

The effect of gender on Helicobacter felis-mediated gastritis, epithelial cell proliferation, and apoptosis in the mouse model

The murine Helicobacter felis model has been extensively used to investigate the importance of host factors in the development of chronic gastritis. The effect of gender in this murine model is unknown. Male and female C57BL/6J mice were infected with H felis for up to 1 year. At 4, 8, 19, 36, and 52 weeks post-infection, gastric histopathology, epithelial cell proliferation, and apoptosis were examined and compared with age- and gender-matched controls. In female mice, infection with H felis resulted in an earlier onset of chronic gastric inflammation, epithelial hyperplasia, and oxyntic cell loss than males. In females, there was a trend towards increased gastric pathology compared with males, with long-term-infected female mice having significantly greater (p < 0.05) chronic inflammation than male mice. The histopathological differences in male and female mice did not relate to the density of H felis infection. Female mice infected with H felis had significantly increased gastric epithelial cell proliferation in the cardia and corpus at both 8 and 52 weeks post-infection (p < 0.05). Epithelial cell apoptosis in the glandular mucosa of the corpus at 36 and 52 weeks post-infection was significantly increased (p < 0.05) in female mice compared with uninfected gender controls. In contrast, there was no significant increase in epithelial cell proliferation or apoptosis in any area of the stomach at any time point after H felis infection in male mice. These results demonstrate that there are gender differences in the gastric inflammatory and epithelial response to H felis in the murine model. The functional importance of gender should be considered in future murine studies on H felis- and H pylori-induced chronic gastritis.     

Light and electron microscopic immunohistochemical investigation on G and D cells in antral mucosa in Helicobacter pylori-related gastritis.

Recently, it has been recognized that Helicobacter pylori (H. pylori) infection is associated with an exaggeration of basal and meal gastrin secretion. We investigate whether there is a relationship between H. pylori-related chronic gastritis and G-cell and D-cell number and granule density index of G and D cells. - The number of antral G cells and D cells and granule density index of D and G cells are compared between thirty two patients with H. pylori-related chronic gastritis and twelve patients without H. pylori and inflammation. Antral mucosal biopsy specimens are examined using light and electron immunohistochemical techniques. - The number of G cells is the same in either infected or uninfected patients (98.40 +/- 11.39, 109.25 +/- 12.76 vs 101.17 +/- 7.72 for infected patients with non atrophic and with mild atrophic chronic gastritis and uninfected controls, respectively) except for the cases with moderate gastric mucosal atrophy, where G cells (58.22 +/- 5.63) decrease in number. The number of D cells is decreased in all patients with H. pylori-related gastritis. G cell granule density index is significantly (p < 0.05) increased in patients with H. pylori-related chronic gastritis than in controls (3.15 +/- 0.43 vs 2.528 +/- 0.01). D cell granule density index is similar between patients with H. pylori chronic gastritis and controls (3.18 +/- 0.05 vs 3.166 +/- 0.12). It is concluded that decreased D cells number in patients with H. pylori-related chronic gastritis might be one of the reasons for the existing hypergastrinaemia.     

Bile reflux and intestinal metaplasia in gastric mucosa.

AIM: To determine associations between enterogastric bile reflux and gastric mucosal pathology. METHOD: A retrospective study using fasting gastric juice bile acid measurements and antral or prestomal biopsy specimens from 350 patients, 66 of whom had previously undergone surgery that either bypassed or disrupted the pyloric sphincter. RESULTS: Bile reflux was positively associated with reactive gastritis and negatively with Helicobacter pylori density. After stratification for previous surgery, age, and H pylori status, the histological feature most strongly associated with bile reflux was intestinal metaplasia, including all its subtypes. The prevalence of intestinal metaplasia was greatest in patients with both H pylori infection and high bile acid concentrations. Bile reflux was also positively associated with the severity of glandular atrophy, chronic inflammation, lamina propria oedema and foveolar hyperplasia. CONCLUSIONS: Bile reflux is a cause of reactive gastritis. It modifies the features of H pylori associated chronic gastritis. The changes are not confined to patients who have had surgery to their stomachs. The positive associations with atrophy and intestinal metaplasia have implications for models of gastric carcinogenesis.     

The endotoxin of Helicobacter pylori is a modulator of host-dependent gastritis.

Atrophic gastritis caused by Helicobacter pylori is the precursor lesion in the development of intestinal-type gastric adenocarcinoma. In animal models, atrophic gastritis induced by Helicobacter felis has been shown to be host dependent, developing in some mouse strains and not in others. The lipopolysaccharide (LPS) of H. pylori has been suggested to play a role in the induction of gastritis. The goal of this study was to compare the inflammation induced by long-term infection of the C3H/He and the C3H/HeJ strains of mice with H. felis. C3H/HeJ mice are unresponsive to LPS. Six months after infection, severe atrophic gastritis had developed in the body mucosae of all infected C3H/He mice, with replacement of parietal and chief cells. Atrophy was associated with a loss of the H. felis from the antral mucosa. In contrast, no atrophy was seen in the infected C3H/HeJ non-LPS responder animals, and heavy colonization of the antrum remained. There were no significant differences between both the quantitative and qualitative serum immunoglobulin G (IgG) and salivary IgA levels in both strains of mice. The main difference between the two strains of long-term-infected mice was a lack of macrophage infiltration in the lamina propria. Immunization induced good protective immunity to challenge with viable H. felis. Helicobacter-induced, host-dependent gastritis is likely to be cell mediated. The C3H/He and C3H/HeJ mouse model provides an excellent opportunity to investigate the cellular basis of atrophic gastritis.     

Outbred mice with long-term Helicobacter felis infection develop both gastric lymphoid tissue and glandular hyperplastic lesions

Experimental infection of mice with Helicobacter felis reproduces many aspects of the gastritis observed in Helicobacter pylori-infected humans. The development of gastric inflammatory lesions in chronically infected inbred mice is host-dependent; in BALB/c mice, gastric B-cell MALT lymphomas were observed, whilst other murine hosts (e.g. C57BL/6) developed severe glandular hyperplasia. The aims of this investigation were to characterize and immunophenotype Helicobacter-induced inflammatory lesions in mice with an outbred genetic background. Swiss mice (n=10 per group) were either inoculated with a suspension of H. felis or left untreated. H. felis-inoculated mice and age-matched control animals were killed 13 months later. The severity of gastric inflammatory lesions in the animals was graded and the number and distribution of B (CD45R(+)) and T (CD3(+)) lymphocytes in lymphoid tissues was determined by immunohistochemistry. Compared with control mice, animals with long-term H. felis infection developed severe hyperplastic gastritis (0.80+/-0.63 vs. 2.7+/-0.68), with epithelial dedifferentiation (0. 40+/-0.52 vs. 2.3+/-0.82) and lengthening of the pits and glands (0. 46+/-0.05 vs. 0.8+/-0.19). Gastric CD45R(+) and CD3(+) lymphocyte scores were significantly elevated (r=0.803) in infected animals, while lymphoepithelial lesions and polymorphonuclear leucocyte infiltrates were absent. Although prominent lymphoid follicles were present in the tissues of all infected animals, and in one control animal, only a proportion (55%) of the mucosal follicles had a dominant B-cell phenotype (defined as > or =75% CD45R(+) labelling), and all were poorly labelled with anti-mouse immunoglobulin antibodies. It was concluded that the lesions in outbred Swiss mice differed from B-cell MALT lymphomas. In contrast to inbred mice, outbred animals developed both glandular and lymphoid tissue lesions to chronic H. felis infection. It is suggested that the default T-helper phenotype of the host influences glandular lesion formation or B-cell lymphomagenesis in this model of infection.     

Rapid development of severe hyperplastic gastritis with gastric epithelial dedifferentiation in Helicobacter felis-infected IL-10(-/-) mice.

Interleukin (IL)-10 is a potent anti-inflammatory and immune-regulatory cytokine. Mice deficient in IL-10 production (IL-10(-/-)) develop a spontaneous inflammatory bowel disease, indicating that IL-10 is an important regulator of the mucosal immune response in vivo. To study the role of IL-10 in the host response to gastric Helicobacter infection, stomachs of IL-10(-/-) and wild-type mice were colonized with Helicobacter felis, as a model of human H. pylori infection. Within 4 weeks of H. felis infection, wild-type mice develop a mild, focal chronic gastritis. In contrast, H. felis-infected IL-10(-/-) mice develop a severe hyperplastic gastritis, characterized by a dense, predominantly mononuclear cell inflammation of the mucosa and submucosa and epithelial cell proliferation and dedifferentiation. Within 4 weeks of H. felis infection, there are striking alterations in the character of the gastric epithelium from IL-10(-/-) mice, including a profound loss of parietal and chief cells, focal de novo production of acidic mucins, and marked epithelial proliferation with disordered epithelial architecture. These findings indicate that, in the absence of IL-10, the inflammatory and immunological responses of the murine host to gastric colonization with Helicobacter is a rapidly evolving pathological process with features that mimic those associated with H. pylori infection in humans. H. felis-infected IL-10(-/-) mice may provide a model with which to investigate the cellular and molecular changes that stem from gastric infection with H. pylori.     

Prevalence and varieties of Helicobacter species in dogs from random sources and pet dogs: animal and public health implications.

Gastric bacteria of a variety of ultrastructural morphologies have been identified in or isolated from domestic carnivores, but their prevalence in different populations of animals and their clinical significance are still unknown. The purposes of this study were (i) to evaluate the prevalence and morphologic types of gastric bacterial in three different populations of dogs; (ii) to determine which of the organisms were culturable, and if the cultured organisms were morphologically similar to the organisms seen in situ; (iii) to identify the isolated organisms; and (iv) to determine if gastric bacteria were associated with gastritis. Three groups of dogs were examined: healthy laboratory dogs, healthy dogs from an animal shelter, and pet dogs with various nongastric illnesses. Of these, 100% of laboratory and shelter dogs and 67% of pet dogs were colonized by large, tightly coiled gastric spiral bacteria morphologically similar to Gastrospirillum hominis or Helicobacter felis (referred to as gastrospirilla). Regardless of the presence or density of gastric bacteria, all of the dogs in the study except one had mild to moderate gastritis. Helicobacter spp. were isolated from only 6 of 39 stomachs cultured, and only three of the organisms isolated were morphologically similar to the bacteria seen in situ. Five helicobacters were identified by 16S rDNA (genes coding for rRNA) sequence analysis. Three were strains of H. felis, one was H. bilis, and one was a novel helicobacter morphologically similar to "Flexispira rappini." Gastrospirilla are almost universal in the stomachs of domestic dogs, and in most infected dogs, they do not appear to be associated with clinical signs or histologic lesions compared with uninfected dogs. Nongastrospirillum helicobacters are rare in dogs and are not histologically detectable. Helicobacter pylori was not isolated from domestic dogs.     

Identification of non-Helicobacter pylori spiral organisms in gastric samples from humans, dogs, and cats

Tightly coiled bacteria are a rare cause of gastric pathology in humans and represent a mixture of species for which a zoonotic origin is suspected. Similar organisms are common inhabitants of the gastric mucosae of carnivores and pigs. It was the goal of the present study to determine the actual occurrence of each individual Helicobacter species in human, canine, and feline stomachs in order to better understand the possible zoonotic significance. Gastric biopsy samples from humans with histological evidence of non-Helicobacter pylori spiral bacteria (n = 123) and samples from the gastric antrum, corpus, and cardia from dogs (n = 110) and cats (n = 43) were subjected to a multiplex PCR, enabling the identification of Helicobacter felis, Helicobacter bizzozeronii, Helicobacter salomonis, and "Candidatus Helicobacter suis." A PCR for detecting H. pylori was applied to all human samples. Single infections with "Candidatus Helicobacter suis," H. felis, H. bizzozeronii, H. salomonis, a hitherto unknown genotype of a non-H. pylori spiral organism (Helicobacter-like organism 135 [HLO135]), and H. pylori were identified in 30.9%, 8.9%, 2.4%, 11.4%, 7.3%, and 8.9% of the human biopsy samples, respectively. Mixed infections (16.3%) with two or even three of these were also found. In the canine stomach, H. bizzozeronii (70.0%) was encountered as the main spiral organism, while H. felis (62.7%) and HLO135 (67.4%) were the predominant Helicobacter species found in the feline gastric mucosa. Although the majority of human non-H. pylori organisms are Helicobacter species naturally occurring in the stomachs of pigs, cats, and dogs, the frequent identification of H. salomonis in human gastric biopsy samples is in contrast to its rare identification in pet carnivore samples, urging us to suspect other sources of infection.     

Five month persistence of Helicobacter pylori infection in guinea pigs

Seven Dunkin-Hartley guinea pigs were infected with the Sydney strain of H. pylori (SS1). Gastric histopathology was evaluated and serum antibody response to H. pylori cell-surface proteins was analysed by enzyme immunoassay (EIA) and immunoblot. Tissue and faecal samples from five control animals were analysed for the presence of naturally occurring Helicobacter spp. infection by culture and Helicobacter genus-specific PCR. The H. pylori infection persisted for 5 months, in most animals accompanied by a histologically severe antral gastritis, exhibiting focal degeneration and necrosis of gastric crypt epithelium. Increased numbers of mitotic figures were observed in the gastric epithelium, indicating a regenerative process. Infected animals displayed specific antibodies towards H. pylori cell-surface proteins in immunoblot, whereas EIA was of dubious value creating false-positive results. Serum complement C3 and cholesterol levels appeared to be elevated in infected animals. Helicobacter spp. infection was not detected in the control animals. The persistent infection, accompanied by severe gastritis and a prominent serum antibody response, and the apparent absence of a natural Helicobacter spp. infection makes the guinea pig model useful in H. pylori research.     

Helicobacter felis gastritis in gnotobiotic rats: an animal model of Helicobacter pylori gastritis.

The gastric spirillum Helicobacter felis, originally isolated from the cat stomach, colonizes the stomachs of germfree rats. Studies were designed to examine the pathological and serological responses of germfree rats inoculated orally with H. felis. At 2 weeks postinoculation, the gastric mucosa of germfree rats had lymphocytes and eosinophils scattered in small foci throughout the subglandular region of the antrum. Small numbers of lymphocytes were present in the subglandular portion of the antral mucosa that focally extended through the lamina propria towards the luminal surface. Eight weeks postinoculation, the inflammation was confined to the antrum. It was characterized by increased numbers of lymphocytes and eosinophils in the subglandular areas, with focal aggregates of lymphocytes in the submucosa. Some lymphoid aggregates extended from the submucosa through the muscularis mucosa and lamina propria to the luminal surface. H. felis was demonstrated with the Warthin-Starry stain, bacterial culture, and urease assay, particularly in the antrum. H. felis also produced a significant immunoglobulin G antibody titer at 2, 4, and 8 weeks postinoculation as well as a transitory immunoglobulin M response at 2 to 4 weeks postinoculation. Contact control rats were not infected, inferring that fecal-oral spread of H. felis did not occur.     

Impact of Helicobacter pylori eradication on morphological changes in gastric mucosa

The purpose of the study was to examine gastric mucosal morphological changes in patients with gastroduodenal pathology after eradication therapy for Helicobacter pylori (H. pylori). A hundred and thirty-eight patients (40 females and 98 males) were examined. Of them, there were 122 patients with duodenal peptic ulcer, 8 with gastric peptic ulcer, 5 with erosive gastritis, 2 with chronic atrophic antral gastritis, and 1 with non-atrophic gastritis. Two months and a year after therapy, manifestations of gastric mucosal atrophy, the degree of inflammation, and its activity significantly diminished in patients with complete H. pylori eradication. Positive changes were observed mainly in the antral portion of the stomach. In patients with partial eradication, chronic inflammation and its activity became less. Two months and a year following therapy, positive changes in the gastric mucosa were absent in patients without H. pylori eradication.     

Helicobacter pylori associated gastric diseases and lymphoid tissue hyperplasia in gastric antral mucosa

AIM: To investigate the relation between Helicobacter pylori associated gastroduodenal diseases and lymphoid tissue hyperplasia in the antral mucosa and to pursue its evolution after eradication of H pylori. METHODS: Gastric antral biopsy specimens were obtained from 438 patients with H pylori positive gastroduodenal diseases (185 chronic gastritis, 69 gastric ulcer, and 184 duodenal ulcer) and 50 H pylori negative healthy controls. Lymphoid follicles and aggregates were counted and other pathological features were scored according to the updated Sydney system for classification of chronic gastritis. After a course of anti-H pylori treatment, biopsy specimens were obtained at four to six weeks, 12 months, and 24 months in the chronic gastritis patient group. RESULTS: The total prevalence of lymphoid follicles and aggregates in the biopsies was 79.9% (350 of 438; 95% confidence intervals (CI), 0.76 to 0.84). The prevalence and density of lymphoid follicles and aggregates were significantly different in the various gastroduodenal diseases. The highest prevalence (89.9%; 95% CI, 0.83 to 0.97) and density (0.82) of lymphoid follicles and aggregates occurred in patients with gastric ulcers. The lowest prevalence of lymphoid follicles and aggregates was found in patients with chronic gastritis (74.6%; 95% CI, 0.68 to 0.81), and the lowest density of lymphoid follicles and aggregates (0.56) was seen in patients with duodenal ulcers. The prevalence and density of lymphoid follicles and aggregates correlated strongly with the activity and severity of gastric antral mucosal inflammation. The eradication of H pylori resulted in a decrease in the prevalence and density of lymphoid follicles and aggregates. CONCLUSION: The prevalence and density of lymphoid follicles and aggregates in gastric antral mucosal biopsies correlated closely with H pylori infection.     

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.     

Serological discrimination of dogs infected with gastric Helicobacter spp. and uninfected dogs

Characterization of the humoral immune responses of people to Helicobacter pylori infection has facilitated the investigation of the host response to bacterial virulence factors and the development of sensitive and specific diagnostic tests. Dogs are commonly infected with gastric Helicobacter spp., but the presence of multiple Helicobacter spp. and possible coinfection in individual dogs have complicated serological evaluation. Evaluation of the antigenic homology of Helicobacter spp. revealed that the major protein bands of Helicobacter felis and Helicobacter bizzozeronii, two Helicobacter spp. that infect dogs, were very similar to UreA (29 to 31 kDa), UreB (63 to 66 kDa), and HSP (58 to 60 kDa) of H. pylori, and sera from infected and uninfected dogs bound in a similar way to each antigen. Immunoblotting and an enzyme-linked immunosorbent assay (ELISA) with H. felis ATCC 49179 antigen were performed with 101 serum samples (from 78 infected dogs and 23 uninfected dogs). Samples from uninfected dogs (median = 8) had fewer bands on immunoblotting than samples from infected dogs (median = 16) (P < 0.05). Combinations of the presence of any two of the low-molecular-mass bands (19, 25, 30, 32, and 37 kDa) or the high-molecular-mass bands (86 and 94 kDa) were found almost solely in samples from infected dogs (P < 0.0001). Kinetic ELISA results were significantly higher for samples from infected dogs (median = 0. 0802 optical density unit [OD]/min) than for samples from uninfected dogs (median = 0.01428 OD/min). The combination of ELISA and immunoblotting results gave a specificity of 95.6% and a sensitivity of 79.8%. No correlation between ELISA results, colonization density, degree of inflammation, and presence of lymphoid follicles was observed. The results indicate substantial antigenic homology between H. felis, H. pylori, and H. bizzozeronii. The combination of ELISA and immunoblotting was a highly specific and moderately sensitive indicator of infection. The degree of seropositivity assessed by ELISA was not related to bacterial colonization density, the degree of gastric inflammation, or the presence of lymphoid follicles.     

Mucosal lymphocyte subsets and HLA-DR antigen expression in paediatric Helicobacter pylori-associated gastritis

Paediatric studies may provide important insights into the immunopathology of Helicobacter pylori-associated gastritis, as mucosal changes reflect different stages of the immunoinflammatory response. We characterized, by quantitative immunohistochemistry, gastric mucosal lymphocyte phenotype and HLA-DR antigen expression and evaluated correlation with histopathology, in H. pylori-infected (Hp+ve) and uninfected children (Hp-ve). In the infected group, lamina propria CD3+ and IgA plasmocyte cell numbers were significantly higher and a trend for predominance of CD8+ over CD4+ was observed both in epithelium and lamina propria. A correlation of inflammation score with lamina propria CD3+ and CD4+ cell numbers and of CD45RO+ T lymphocytes with density of colonization was observed. The proportion of epithelial cells expressing HLA-DR antigen was significantly higher in the Hp+ve group and furthermore, glandular HLA-DR expression correlated with lamina propria CD3+ cell numbers, emphasizing the potential role of epithelial cells as antigen-presenting cells at this stage of infection.