IgG subclass responses in childhood Helicobacter pylori duodenal ulcer: evidence of T-helper cell type 2 responses

Effect of Helicobacter pylori and Helminth Coinfection on the Immune Response to Mycobacterium tuberculosis

Tuberculosis remains one of the main causes of morbidity and mortality worldwide despite decades of efforts to eradicate the disease. Although the immune response controls the infection in most infected individuals (90%), the ability of the bacterium to persist throughout the host's life leads to a risk of reactivation. Underlying conditions including human immunodeficiency virus (HIV) infection, organ transplantation, and immunosuppressive therapies are considered risk factors for progression to active disease. However, many individuals infected with Mycobacterium tuberculosis may develop clinical disease in the absence of underlying immunosuppression. It is also possible that unknown conditions may drive the progression to disease. The human microbiota can be an important modulator of the immune system; it can not only trigger inflammatory disorders, but also drive the response to other infectious diseases. In developing countries, chronic mucosal infections with Helicobacter pylori and helminths may be particularly important, as these infections frequently coexist throughout the host's life. However, little is known about the interactions of these pathogens with the immune system and their effects on M. tuberculosis clinical disease, if any. In this review, we discuss the potential effects of H. pylori and helminth co-infections on the immune response to M. tuberculosis. This may contribute to our understanding of host-pathogen interactions and in designing new strategies for the prevention and control of tuberculosis.

Associations between Helicobacter pylori infection, co-morbid infections, gastrointestinal symptoms, and circulating cytokines in African children

BACKGROUND

Refugee children have complex medical needs and often have multiple infections. The relationship between infection, gastrointestinal symptoms, and systemic inflammation is poorly understood. We investigated these parameters in refugee children with a high prevalence of Helicobacter pylori, helminth, and malaria infection.

MATERIALS AND METHODS

African refugee children were recruited at resettlement health screening. Data were collected on demography, gastrointestinal symptoms, co-morbid infection, and serum for peripheral cytokine levels. Helicobacter pylori infection was diagnosed by a fecal-based immunoassay.

RESULTS

Data from 163 children were analyzed, of which 84.0% were positive for H. pylori. Infected children were significantly older (9.2 years +/- 3.7 vs 7.1 years +/- 3.9, p = .01). Half the cohort (84/163, 51.5%) described gastrointestinal symptoms but these were not strongly associated with co-morbid infections. Helicobacter pylori-infected children had significantly lower circulating log-interleukin-8 (IL-8) (odds ratio 0.61, 95% confidence interval (CI) 0.40, 0.94, p = .025). Helminth infections were common (75/163, 46%) and associated with elevated log-IL-5 (beta: 0.42, 95% CI 0.077, 0.76). Children with malaria (15/163, 9.2%) had elevated log-tumor necrosis factor-alpha (TNFalpha) and log-IL-10 (beta: 0.67, 95% CI 0.34, 1.0 and beta: 1.3, 95% CI 0.67, 1.9, respectively). IL-10 : IL-12 ratios were increased in H. pylori-infected children with malaria or helminth infections. Symptoms were generally not associated with levels of circulating peripheral cytokines irrespective of co-morbid infection diagnosis.

CONCLUSIONS

There is a high prevalence of asymptomatic H. pylori infection in recently resettled African refugee children. Gastrointestinal symptoms were not predictive of H. pylori nor of helminth infections. Serum cytokines, particularly IL-5, IL-10, and TNFalpha, were significantly elevated in children with malaria and helminth infections but not in those with H. pylori infection.

Helicobacter pylori HopE and HopV porins present scarce expression among clinical isolates

AIM

To evaluate how widely Helicobacter pylori (H. pylori) HopE and HopV porins are expressed among Chilean isolates and how seroprevalent they are among infected patients in Chile.

METHODS

H. pylori hopE and hopV genes derived from strain CHCTX-1 were cloned by polymerase chain reaction (PCR), sequenced and expressed in Escherichia coli AD494 (DE3). Gel-purified porins were used to prepare polyclonal antibodies. The presence of both genes was tested by PCR in a collection of H. pylori clinical isolates and their expression was detected in lysates by immunoblotting. Immune responses against HopE, HopV and other H. pylori antigens in sera from infected and non-infected patients were tested by Western blotting using these sera as first antibody on recombinant H. pylori antigens.

RESULTS

PCR and Western blotting assays revealed that 60 and 82 out of 130 Chilean isolates carried hopE and hopV genes, respectively, but only 16 and 9, respectively, expressed these porins. IgG serum immunoreactivity evaluation of 69 H. pylori-infected patients revealed that HopE and HopV were infrequently recognized (8.7% and 10.1% respectively) compared to H. pylori VacA (68.1%) and CagA (59.5%) antigens. Similar values were detected for IgA serum immunoreactivity against HopE (11.6%) and HopV (10.5%) although lower values for VacA (42%) and CagA (17.4%) were obtained when compared to the IgG response.

CONCLUSION

A scarce expression of HopE and HopV among Chilean isolates was found, in agreement with the infrequent seroconversion against these antigens when tested in infected Chilean patients.

Fructo-oligosaccharide reduces inflammation in a dextran sodium sulphate mouse model of colitis

Fructo-oligosaccharide (FOS) is a prebiotic that stimulates the colonic growth of bifidobacteria to promote intestinal health. This study assessed whether FOS can reduce intestinal damage associated with ulcerative colitis and accelerate recovery in a mouse model. C57BL/6 mice received 2% dextran sulphate sodium for 7 days (days 8-14). FOS (1.5 g/mL) treatment was administered twice daily (n=10/group): before and during colitis (days 1-14); during colitis (days 10-14); and during colitis and the recovery period (days 10-19). Disease activity was scored daily and colonic damage was assessed by histological analysis. FOS treatment significantly reduced disease activity and damage in the distal colon (P < .05). Treatment with FOS (days 10-14) had increased crypt depth (116+/-6 microm) compared to water treatment (90+/-4 microm, P < .05). FOS treatment (days 10-19) produced a faster recovery from damage with increased crypt depth and crypt area. These results demonstrate the protective effect of FOS treatment.

Response of IgG1 and IgG2 subclasses to Helicobacter pylori in subjects with chronic inflammation of the gastric mucosa, atrophy and gastric cancer in a country with high Helicobacter pylori infection prevalence

Polarized immune response to Helicobacter pylori and induction of chronic inflammation may increase the risk of gastric atrophy and adenocarcinoma. We studied the association of the response of IgG1 and IgG2 antibodies to H. pylori with grade of gastric chronic inflammation and atrophy in a population with a high prevalence of H. pylori, and compared these data with the data obtained from the study of gastric cancer patients, as well as with the data for CagA positivity. Altogether, 114 persons from two adult population samples from Estonia and 45 consecutive gastric cancer patients were studied. All patients were positive for the H. pylori antibody determined by ELISA. Adenocarcinoma was classified histologically according to the Laurén's system. The response of the IgG subclasses to H. pylori (acid glycine-extracted whole cell proteins) was determined by ELISA and the results were compared with the ELISA results for the recombinant fragment of the CagA protein. Helicobacter pylori IgG level was lower in atrophic gastritis compared with nonatrophic gastritis (chronic inflammation) (p=0.001). In the group of cancer patients, the response of IgG and IgG1 was lower compared with both gastritis groups (p=0.01 and p=0.0002 for IgG, and p=0.001 and p=0.0005 for IgG1). IgG2 was lower for gastric cancer localized in the corpus (p=0.03). In conclusion, atrophic gastritis and gastric cancer were associated with a significant decline in IgG and IgG1 response to H. pylori compared with nonatrophic gastritis. Higher value of CagA antibodies was seen in gastric cancer and in gastric atrophy compared with nonatrophic gastritis; in gastric cancer patients, IgG1 response to H. pylori was correlated with CagA status.

The biology of Helicobacter pylori infection, a major risk factor for gastric adenocarcinoma

Helicobacter pylori infection of the human stomach is the most important risk factor for development of gastric cancer. Whereas persistent viral infection leads to a number of cancers, H. pylori was the first bacteria linked to a human cancer. The exact mechanisms that lead to cancer induction are not clear, but study of the bacterial factors important for colonization and the host responses to the infection are starting to yield important clues.

Inflammation, immunity, and vaccines for Helicobacter infection

Pro-inflammatory cytokines such as IL-18, IFN-gamma, and IL-1beta play a significant role in the inflammation induced by Helicobacter. During the recent years of H. pylori research, the main focus has been on development of vaccines for therapeutic or prophylactic use against the infection. Both bacterial components of H. pylori as well as engineered vaccines have been tested as well as different forms of administration including systemic and oral/intranasal pathways.

Intestinal helminthiasis in Colombian children promotes a Th2 response to Helicobacter pylori: possible implications for gastric carcinogenesis

BACKGROUND

Colombians living in coastal Tumaco have a lower incidence of Helicobacter pylori-associated gastric cancer compared with residents of Pasto in the high Andes. Considering the risk for H. pylori disease seems affected by features of bacterial virulence and host polymorphisms, other poorly understood influences, such as concurrent helminthiasis, may also be important.

METHODS

Fecal samples from 211 children were tested for parasites and sera from another cohort of 159 children and 92 adults were tested for IgE and H. pylori-specific IgG.

RESULTS

Most individuals (95%) from both areas were H. pylori seropositive, with a predominant response of IgG1 followed by IgG2 and low IgG3 and IgG4 antibodies. Compared with Pasto children, Tumaco children were more commonly infected with helminths (P = 0.000), had higher serum IgE levels (P < 0.03), and had higher Th2-associated IgG1 responses to H. pylori (P < 0.0002). Other IgG isotype responses all increased with age but were not significantly different between children and adults from either area.

CONCLUSIONS

These results suggest that intestinal helminthiasis in children promotes Th2-polarizing responses to H. pylori and may decrease gastric cancer risk in these individuals later in life. Concurrent helminthiasis may alter inflammatory responses to H. pylori and thus affect the progression of gastritis to gastric atrophy, dysplasia, and cancer.