Local cellular and immune response by antral mucosa in patients undergoing treatment for eradication of Helicobacter pylori

The association of intestinal parasitosis and H. pylori infection in children and adults from a Mexican community with high prevalence of parasitosis

BACKGROUND

Experimental evidences have suggested that a Th1 response is unable to eliminate H. pylori colonization; whereas a Th2 response, like the one induced by vaccination, reduces H. pylori infection in animal models. Some parasitic infections induce a polarized Th2 response, which theoretically would favor a reduced H. pylori prevalence. The aim of this work was to study the possible association between parasitic infections and H. pylori prevalence.

MATERIALS AND METHODS

The study population included 120 children and 188 adults from a low socioeconomic level village. H. pylori prevalence was determined in serum by ELISA; parasitic infections were identified in feces by microscopic examination; and total serum IgE levels, as an indirect indicator of some parasitic infections, were determined by ELISA.

RESULTS

In children, H. pylori prevalence was no different between those with and without intestinal parasitic infection. By contrast, adults with intestinal parasitic infection had a significantly lower H. pylori prevalence than adults without parasites (62.6% compared with 80.4%; p = 0.006, OR 2.45). Also in adults, but not in children, total IgE levels were significantly higher in those without H. pylori infection than in those with H. pylori infection (p < 0.001).

CONCLUSIONS

Intestinal parasitic infections and serum IgE levels showed an age-dependent association with H. pylori prevalence. In adults, but not in children, intestinal parasitic infections and increased IgE levels where associated with a reduced H. pylori prevalence.

[Epidemiological aspects of Helicobacter pylori infection in childhood and adolescence]

The scope of the review is to study the epidemiological aspects of Helicobacter pylori infection and its importance during childhood and adolescence, focusing on incidence, prevalence, transmission and risk factors. The study's references included the following databases: LILACS (PAHO/ Bireme), MEDLINE, the US's National Library of Medicine and the thesis developed at University of São Paulo for the period 1983 to 1999. It was noted that Helicobacter pylori infection is mainly acquired during childhood, age-related prevalence, main risk factors are associated to low socioeconomic status, and its transmission mechanism remains unclear.

IgE-containing cells in gastric mucosa with and without Helicobacter pylori infection

Gastric mucosa responds with inflammation to Helicobacter pylori (H. pylori) infection. While numerous reports have shown that the immune system produces specific IgG, IgA, and IgM isotype anti H. pylori antibodies, IgE-mediated pathways of H. pylori-associated gastritis are mostly unknown. Our aim was to evaluate whether an increased presence of IgE in the antral gastric mucosa is responsible for the severity of the H. pylori-associated gastritis. The number of IgE-containing cells was estimated in formalin-fixed, paraffin-embedded antral gastric biopsy specimens using immunohistochemistry in three groups of patients: (i) 20 H. pylori-positive cases with moderate inflammation, (ii) 19 H. pylori-negative cases with moderate inflammation, and (iii) 19 H. pylori-negative cases with normal mucosa. In chronic gastritis, the number of IgE-positive cells increased significantly as compared to normal mucosa. In gastritic patients, H. pylori positivity was accompanied by a significant accumulation of IgE-positive cells, mainly plasma cells. These data suggest that IgE-mediated immune response probably plays an important role in the development of H. pylori-associated gastritis.

In situ expression of cell adhesion molecules in chronic gastritis with Helicobacter pylori infection

Helicobacter pylori infection of the stomach results in acute inflammation followed by chronic inflammation, but the mechanism is unknown. Adhesion molecules such as ICAM-1, Mac-1, and LFA-1 may help regulate interactions of immune cells and inflammatory cells. We used immunohistochemistry to locate these molecules in the gastric mucosa of patients with chronic gastritis arising from H. pylori infection. Biopsy specimens were taken from five H. pylori-negative healthy volunteers and 20 H. pylori-positive patients with chronic gastritis for immunohistochemical studies of adhesion molecules. In the gastric mucosa of patients with H. pylori-associated chronic gastritis, ICAM-1 expression was prominent in most of the vessels and inflammatory cells, such as lymphocytes and granulocytes, in the lamina propria. However, no intraepithelial lymphocytes and surface epithelial cells expressed ICAM-1. Antigen-presenting cells (APCs), such as macrophages, expressed ICAM-1 as well as HLA-DR antigen. LFA-1 and Mac-1 were strongly expressed in these immune and inflammatory cells. The number of vascular endothelial cells positive for P-selectin was also greater in H. pylori-positive mucosa. The expression of these molecules decreased remarkably after successful eradication of H. pylori. In conclusion, ICAM-1 is the predominant form among the cell adhesion molecules that are expressed in response to chronic H. pylori infection. The increased expression of ICAM-1 is linked with massive infiltration of inflammatory cells that express LFA-1 and Mac-1, and also with APCs that express HLA-DR, suggesting that ICAM-1 exerts a key role in immuno-inflammatory responses in gastric mucosa of patients with H. pylori-associated gastritis.

Helicobacter pylori acquisition in infancy after decline of maternal passive immunity

We evaluated the natural history of Helicobacter pylori infection and the host immune response in 80 infants, and determined seroprevalence of H. pylori infection in their Taiwanese mothers. Decline in passively transferred maternal anti-H. pylori IgG antibodies and subsequent H. pylori infection was assessed in infants over 14 mo. A sensitive and specific, 96-well microtiter ELISA for the detection of H. pylori IgG antibodies was used to evaluate maternal serum (single specimen) and their infants (birth, 1, 2, 3, 6, 12, and 14 mo). Sera were also evaluated by ELISA for the presence of anti-H. pylori IgM antibodies in the infants. Maternal H. pylori IgG seroprevalence was 62.5% [50/80; 95% confidence intervals (CI), 51-73%]. All infants born to the 50 seropositive mothers passively acquired maternal H. pylori IgG. Transplacentally transferred maternal anti-H. pylori IgG lasted until about the 3rd mo of life, and disappeared in nearly all the infants by 6 mo of age. Seven and one-half percent of infants (6/80; 95% CI, 3-16%) acquired H. pylori infection; two were born to H. pylori-negative mothers. Among the six IgG seropositive infants, an IgM response specific for H. pylori antigens was detected and appeared to precede the rise in IgG in five. We conclude that maternal passive transfer of IgG antibodies occurs in the infant and disappears by 6 mo of age. H. pylori infection is acquired in infancy in this population; IgM antibodies against H. pylori are detectable, seem short-lived, and appear to precede IgG antibody development.

Selective adherence of a sucralfate-tetracycline complex to gastric ulcers: implications for the treatment of Helicobacter pylori

The adherence of a sucralfate-tetracycline complex to gastric ulcers and to nearby non-ulcer sites was determined in the rabbit antrum. Persistent gastric ulcers were produced by a previously described method. The presence of the complex was assessed 1 and 4 h after dosing. Drug adherence was determined by quantitation of aluminum in stomach wall biopsies. Significantly more aluminum adhered to ulcer sites than to nearby non-ulcer sites. Adherence of the complex did not significantly decrease from 1 to 4 h. The complexation of tetracycline to sucralfate did not alter the selective adherence of sucralfate to gastric ulcers, providing a mechanism of ulcer site-selective drug delivery in the treatment of Helicobacter pylori gastric ulcer disease.

Oral immunization with Helicobacter pylori urease B subunit as a treatment against Helicobacter infection in mice

BACKGROUND & AIMS

Eradication of Helicobacter pylori infections in humans results in the healing of gastritis and gastric ulcers. This study used a mouse model to test whether oral vaccination can cure Helicobacter infection and gastritis.

METHODS

Mice were infected with Helicobacter felis. Three weeks after infection, the mice were orally immunized with H. pylori urease B subunit. Control mice were simultaneously infected but sham immunized.

RESULTS

Three to 8 weeks after oral immunization of H. felis-infected mice with recombinant H. pylori urease B subunit, the infection cleared and there was no evidence of gastritis. Vaccinated mice remained protected against two consecutive H. felis challenges.

CONCLUSIONS

These results show that the lack of natural immunity against Helicobacter can be overcome by oral immunization and that vaccination offers a novel therapeutic approach to Helicobacter-induced gastritis.

Gastric output of IgA in man: relation to migrating motility complexes and sham feeding

BACKGROUND/AIMS

The immunologic reactivity of the gastric mucosa is poorly understood. The origin and dynamics of immunoglobulin A (IgA) occurring in the gastric lumen were investigated in healthy, Helicobacter pylori-negative volunteers.

METHODS

Gastroduodenal manometric motility recordings were combined with gastric luminal perfusion, enabling calculation of gastric acid output and analysis of the total IgA output.

RESULTS

Acid output and total IgA correlated with the migrating motility complexes (MMC). The gastric IgA release showed maximal values in association with gastric motility phase III (maximal motor activity) and lowest values during phases I and II (none or irregular motor activity). The IgA output correlated with neither swallowed saliva (as indicated by amylase in the gastric perfusate) nor duodenogastric reflux (as indicated by gastric occurrence of bilirubin and/or duodenally infused PEG4000). Stimulation of gastric acid secretion by sham feeding during phase II-like motor activity (n = 6) induced a rapid and transient doubling of IgA output. There was no significant correlation between gastric acid secretion and gastric IgA release.

CONCLUSION

Substantial amounts of IgA are released into the human stomach, most likely originating from the gastric mucosa. The up-regulation of IgA release in association with the activity front of the MMC and anticipatory to food intake suggests a neuroendocrine control of gastric mucosal immune responses.

Immunization of BALB/c mice against Helicobacter felis infection with Helicobacter pylori urease

BACKGROUND/AIMS

Because Helicobacter pylori is a potentially dangerous human pathogen, the protective potential of oral immunization with H. pylori urease and its subunits was evaluated in an animal model.

METHODS

Mice were orally immunized with H. pylori sonicate, urease, or recombinant enzymatically inactive urease subunits and then challenged with Helicobacter felis. Control mice were sham-immunized.

RESULTS

H. felis colonization was present 5 days after challenge in 9 of 10 sham-immunized, 6 of 9 sonicate-immunized, and 3 of 10 urease-immunized animals (P = 0.031 vs. sham-immunized). Twelve days after challenge, urease B-immunized mice had a weaker colonization than sham-immunized controls, whereas urease A had no effect. After 70 days, most urease A- and urease B-immunized mice had cleared the colonization (10/17: P = 0.0019; 16/20: P = 0.00002 vs. sham-immunized). In urease B-immunized animals, protection was often associated with corpus gastritis.

CONCLUSIONS

Oral immunization with H. pylori urease protects mice against H. felis infection. Enzymatically inactive urease A and B subunits contain protective epitopes. It is unclear whether protection depends on the development of a mononuclear inflammatory response in the gastric corpus. Our observations should encourage the development of a human vaccine.

Omeprazole. An update of its pharmacology and therapeutic use in acid-related disorders

Omeprazole, a gastric acid pump inhibitor, dose-dependently controls gastric acid secretion: the drug has greater antisecretory activity than histamine H2-receptor antagonists. Omeprazole 20 to 40 mg/day is more effective than histamine H2-receptor antagonists in the short term treatment of duodenal ulcer, gastric ulcer and reflux oesophagitis. Available data suggest that omeprazole 10 to 40 mg/day is also more effective than ranitidine in the maintenance therapy of duodenal ulcer and reflux oesophagitis. The drug is also effective in patients with duodenal ulcer, gastric ulcer or reflux oesophagitis poorly responsive to histamine H2-receptor antagonists. The efficacy of omeprazole 20 mg/day appears to be similar to that of lansoprazole 30 mg/day in the short term treatment of duodenal ulcer, gastric ulcer and reflux oesophagitis. However, most available studies have been reported in abstract form only, and 2 of 3 studies in patients with duodenal ulcer have shown greater healing rates at 2 (but not 4) weeks with lansoprazole. Helicobacter pylori eradication decreases duodenal ulcer relapse rates and appears to be associated with improved duodenal ulcer healing rates. Evidence also suggests that H. pylori eradication is associated with reduced gastric ulcer relapse rates. Omeprazole monotherapy may suppress but does not eradicate H. pylori infection. Eradication rates with omeprazole 20 or 40 mg twice daily plus amoxicillin usually up to 2 g/day (3 g/day in a few studies) for 2 weeks appear to be similar to those of standard triple therapy (bismuth salt plus metronidazole, plus tetracycline or amoxicillin) or omeprazole plus clarithromycin, although eradication rates vary widely. Omeprazole plus amoxicillin appears to be better tolerated than triple therapy and represents a first-line treatment alternative in patients with H. pylori-associated peptic ulcer disease. Omeprazole plus amoxicillin plus metronidazole appears to be more effective than omeprazole plus amoxicillin in patients with metronidazole-sensitive H. pylori infection. Omeprazole remains a treatment of choice in patients with Zollinger-Ellison syndrome. The dosages should be adjusted according to individual response. However, relatively low dosages of 10 to 40 mg/day may be sufficient in some patients. The drug has also shown promise in the treatment of children with severe reflux oesophagitis, in patients with reflux oesophagitis and coexisting systemic sclerosis, and in the prevention of aspiration pneumonia. Evidence suggests that omeprazole is more effective than ranitidine in patients with nonsteroidal anti-inflammatory drug (NSAID)-induced gastric damage who continue to take NSAIDs, especially in patients with large gastric ulcers; however, completion of ongoing studies is required to verify this.(ABSTRACT TRUNCATED AT 400 WORDS)