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

Dietary administration of the glycolytic inhibitor 2-deoxy-D-glucose reduces endotoxemia-induced inflammation and oxidative stress: Implications in PAMP-associated acute and chronic pathology

Pathogen-associated molecular patterns (PAMPs) like bacterial cell wall components and viral nucleic acids are known ligands of innate inflammatory receptors that trigger multiple inflammatory pathways that may result in acute inflammation and oxidative stress-driven tissue and organ toxicity. When dysregulated, this inflammation may lead to acute toxicity and multiorgan failure. Inflammatory events are often driven by high energy demands and macromolecular biosynthesis. Therefore, we proposed that targeting the metabolism of lipopolysaccharide (LPS)-driven inflammatory events, using an energy restriction approach, can be an effective strategy to prevent the acute or chronic detrimental effects of accidental or seasonal bacterial and other pathogenic exposures. In the present study, we investigated the potential of energy restriction mimetic agent (ERMA) 2-deoxy-D-glucose (2-DG) in targeting the metabolism of inflammatory events during LPS-elicited acute inflammatory response. Mice fed with 2-DG as a dietary component in drinking water showed reduced LPS-driven inflammatory processes. Dietary 2-DG reduced LPS-induced lung endothelial damage and oxidative stress by strengthening the antioxidant defense system and limiting the activation and expression of inflammatory proteins, viz., P-Stat-3, NfκΒ, and MAP kinases. This was accompanied by decreased TNF, IL-1β, and IL-6 levels in peripheral blood and bronchoalveolar lavage fluid (BALF). 2-DG also reduced the infiltration of PMNCs (polymorphonuclear cells) in inflamed tissues. Altered glycolysis and improved mitochondrial activity in 2-DG-treated RAW 264.7 macrophage cells suggested possible impairment of macrophage metabolism and, therefore, activation in macrophages. Taken together, the present study suggests that inclusion of glycolytic inhibitor 2-DG as a part of the diet can be helpful in preventing the severity and poor prognosis associated with inflammatory events during bacterial and other pathogenic exposures.

Pathogenicity of Helicobacter pylori in cancer development and impacts of vaccination

Helicobacter pylori affect around 50% of the population worldwide. More importantly, the gastric infection induced by this bacterium is deemed to be associated with the progression of distal gastric carcinoma and gastric mucosal lymphoma in the human. H. pylori infection and its prevalent genotype significantly differ across various geographical regions. Based on numerous virulence factors, H. pylori can target different cellular proteins to modulate the variety of inflammatory responses and initiate numerous "hits" on the gastric mucosa. Such reactions lead to serious complications, including gastritis and peptic ulceration, gastric cancer and gastric mucosa-associated lymphoid structure lymphoma. Therefore, H. pylori have been considered as the type I carcinogen by the Global Firm for Research on Cancer. During the two past decades, different reports revealed that H. pylori possess oncogenic potentials in the gastric mucosa through a complicated interplay between the bacterial factors, various facets, and the environmental factors. Accordingly, numerous signaling pathways could be triggered in the development of gastrointestinal diseases (e.g., gastric cancer). Therefore, the main strategy for the treatment of gastric cancer is controlling the disease far before its onset using preventive/curative vaccination. Increasing the efficiency of vaccines may be achieved by new trials of vaccine modalities, which is used to optimize the cellular immunity. Taken all, H. pylori infection may impose severe complications, for resolving of which extensive researches are essential in terms of immune responses to H. pylori. We envision that H. pylori-mediated diseases can be controlled by advanced vaccines and immunotherapies.

The Role of Morbid Obesity in the Promotion of Metabolic Disruptions and Non-Alcoholic Steatohepatitis by Helicobacter Pylori

Background

Helicobacter pylory (HP) infection has been associated to an increased rate of type 2 diabetes (T2D) and liver disease through its effect on insulin resistance and systemic inflammation. However, results are inconstant and no studies exist in morbidly obese patients, in which both insulin resistance and inflammation coexist.

Material and Methods

Cross-sectional study to evaluate the relationship between HP infection and alterations in carbohydrate metabolism, lipid profile, inflammation markers, and liver disease in patients awaiting for bariatric surgery. HP infection was histologically assessed in gastric antrum biopsy from 416 subjects. Liver biopsy was also available in 93 subjects.

Results

Both impaired fasting glucose and T2D were similar when comparing subjects with and without HP infection (24.2% vs. 22%, p = 0.290 and 29.4% vs. 29.1%, p = 0.916, respectively), with no differences between groups in the HOMA-IR, lipid profile neither inflammatory parameters. However, HP infection was higher among subjects with a BMI ≥ 40.0 kg/m² in comparison with lower degrees of obesity (71.7% vs. 60.0%, p = 0.041). In addition, subjects without HP infection showed higher degrees of steatosis (44.1±26.4% vs. 32.0±20.7%, p = 0.038), as well as a lower prevalence of non-alcoholic steatohepatitis (9.3% vs. 30.7%, p = 0.023).

Conclusions

In patients with morbid obesity, HP infection does not seem to be associated with abnormal carbohydrate metabolism. In addition, less advanced degrees of non-alcoholic fatty disease were observed. We suggest that low-grade inflammation that accompanies obesity mitigates the diabetogenic effect of HP, so the presence of obesity should be considered in studies that evaluate the HP metabolic effects.

BH3-only protein Bim is associated with the degree of Helicobacter pylori-induced gastritis and is localized to the mitochondria of inflammatory cells in the gastric mucosa

BH3-only protein, Bim, is a pro-apoptotic protein that mediates mitochondria-dependent cell death. However, the role of Bim in Helicobacter pylori-associated gastritis remains unclear. This study aimed to assess the cellular localization of Bim and its possible role in H. pylori-induced gastritis. The study was conducted on biopsy specimens obtained from 80 patients who underwent upper gastrointestinal endoscopy (H. pylori-negative: n=30, positive: n=50). Association between Bim mRNA expression and severity of gastritis was evaluated and the localization of Bim was examined by immunofluorescence. Bim mRNA expression was positively correlated with the degree of gastritis, as defined by the Sydney system. Immunohistochemical analysis confirmed increased Bim expression in H. pylori-infected gastric mucosa compared with uninfected mucosa in both humans and mice. Bim localized in myeloperoxidase- and CD138-positive cells of H. pylori-infected lamina propria and submucosa of the gastric tract, indicating that this protein is predominantly expressed in neutrophils and plasma cells. In contrast, Bim did not localize in CD20-, CD3-, or CD68-positive cells. Bim was expressed in the mitochondria, where it was partially co-localized with activated Bax and cleaved-PARP. In conclusion, Bim is expressed in neutrophils and plasma cells in H. pylori-associated gastritis, where it may participate in the termination of inflammatory response by causing mitochondria-mediated apoptosis in specific leucocytes.

Expression of adhesion and activation molecules on circulating monocytes in children with Helicobacter pylori infection

OBJECTIVES

The aim of this study was to assess the cell surface expression of adhesion (CD11a, CD11b, CD11c, CD18, CD54, and CD58) and activation (CD14, HLA-DR, and CD16) molecules on the circulating monocytes in Helicobacter pylori (H. pylori)-infected and noninfected children with gastritis, with the goal of comparing the results with those obtained from the controls.

MATERIALS AND METHODS

 Ninety-four children were studied: 47 of them with H. pylori infection (of those 25 children after the failure of eradication therapy) and 26 children with gastritis where H. pylori infection was excluded, as well as 21 controls. H. pylori infection status was assessed based on [¹³C] urea breath test, rapid urease test, and histology. Analysis of the monocyte surface molecule expression was carried out by flow cytometry.

RESULTS

 H. pylori-infected children and children who experienced a failure of the eradication therapy differed significantly in the expression of adhesion and activation molecule on circulating monocytes. A decrease, both in the proportion of CD11c- and CD14-bearing monocytes, and the expression of CD11c and CD14 molecules on circulating monocytes, was found in children in whom the eradication therapy failed (p < .05). Low expression of CD11b (p = .04) and CD18 (p = .02) integrins on monocytes was also observed. Additionally, the percentage of HLA-DR-bearing monocytes was decreased (p = .04), while the CD16 density receptor was increased (p = .02). Compared with the controls, low percentage of CD16-positive monocytes was noted in noninfected children with gastritis (p = .01).

CONCLUSION

H. pylori eradication therapy in children causes inhibition of inflammatory response via a reduction in CD11b, CD11c, and CD18 beta2 integrin monocyte expression.

Increases in Nonspecific Immunoglobulin E and Eosinophils after H. pylori Eradication

Helicobacter pylori infection has been reported to be inversely associated with allergic disorders. We by chance experienced a patient with atrophic gastritis who presented marked elevations of both nonspecific serum immunoglobulin E and eosinophil counts after H. pylori eradication. A 49-year-old Japanese man received eradication of H. pylori using lansoprazole 60 mg/day, amoxicillin 1,500 mg/day, and clarithromycin 400 mg/day for 7 days. Serum immunoglobulin E increased to more than four times its pretreatment level, 306 → 485 → 1,325 U/ml, and peripheral eosinophil counts increased to more than three times, 99 → 139 → 298 per μl. Deducing from the current case, H. pylori eradication might develop allergic disorders in some patients.

Cathepsin X prevents an effective immune response against Helicobacter pylori infection

Cathepsin X, a cysteine protease, has been shown to regulate an immune response by activating beta-2 integrin receptors. In this study we demonstrate its role in regulating the immune response to infection with H. pylori. The level of cathepsin X was determined in THP-1 monocyte cells primed with H. pylori antigens isolated from subjects suffering from gastritis, who had either eradicated or not the disease after the antibiotic therapy. We show that the specific clinical outcome of H. pylori eradication therapy correlates strongly with the membrane expression of cathepsin X in stimulated THP-1 cells, being significantly higher after stimulation with H. pylori strains from those subjects who did not respond to antibiotic therapy. The same antigens elicit a more vigorous immune response, increased expression of MHC II, however trigger inadequate cytokine profile (IFN-gamma and IL-4) to eradicate the pathogen. We propose that cathepsin X mediated activation of beta-2 integrin receptor Mac-1 suppresses the stimulatory signal in the form of cytokines. Cathepsin X co-localizes on the membrane of THP-1 cells with Mac-1 integrin receptor and its inhibition increases homotypic aggregation and mononuclear cell proliferation, events that are associated with low Mac-1 activity. Our study highlights the diversity of the innate immune response to H. pylori antigens leading to either successful eradication of the infection or maintenance of chronic inflammation, revealing cathepsin X location and activity as a regulator of the effectiveness of H. pylori eradication.

Vascular risks and complications in diabetes mellitus: the role of helicobacter pylori infection

Patients with diabetes mellitus (DM) are at risk for Helicobacter pylori infection. This infection has been linked to atherosclerosis and its vascular complications. The aim of this study was to evaluate the: (1) prevalence of H pylori infection in patients with DM; (2) association between diabetic vascular complications and H pylori infection; and (3) influence of H pylori infection on atherosclerosis and inflammatory biomarkers. In this study, we evaluated 80 patients with DM for atherosclerosis; cardiac, cerebral, and peripheral vascular diseases; retinopathy; neuropathy; and nephropathy. We estimated the blood levels of glucose, glycosylated hemoglobin, complete blood cell count, erythrocytic sedimentation rate, lipid profile, tumor necrosis factor-alpha, interleukin (IL)-6, and anti-H pylori IgG antibodies. H pylori infection was detected in 85% of patients versus 76.7% for control subjects. Carotid artery intima-media thickness was significant in H pylori-infected patients. IL-6 and tumor necrosis factor-alpha were significantly associated with H pylori infection. In multivariate analysis, blood glucose, triglycerides, erythrocytic sedimentation rate, IL-6, and tumor necrosis factor-alpha increased the odds for atherothrombotic cause of cerebral ischemia in H pylori infection. We concluded that H pylori infection is common in DM and seems to be linked to the presence of atherosclerosis and ischemic cerebrovascular stroke. This effect could be mediated by increasing cytokine levels.

Helicobacter pylori infection as an independent risk factor for cerebral ischemia of atherothrombotic origin

Chronic infection may increase the risk for ischemic stroke. Presently, it is insufficiently established whether Helicobacter pylori infection represents a risk factor for ischemic stroke. We analyzed IgG antibodies against H. pylori in 109 patients with acute cerebral ischemia and 82 age- and sex-matched control patients with non-vascular and non-inflammatory neurological diseases. Antibody titers were significantly higher in patients than in control subjects (p=0.007). H. pylori seropositivity tended to be more common in patients (odds ratio (OR) 1.55, 95% confidence interval (ci) 0.87-2.76), but this trend was further attenuated in multivariate analysis (OR 1.42; 95% 0.75-2.67) with hypertension, diabetes mellitus, current or previous smoking, previous cerebral ischemia and low socioeconomic status. H. pylori seropositivity increased the odds for cerebral ischemia of atherothrombotic origin in univariate (OR 3.63; 95% ci 1.37-9.65) and multivariate analysis (OR 3.53; 95% ci 1.09-11.4). H. pylori seropositivity may be an independent risk factor for stroke of atherothrombotic origin.

Helicobacter pylori lipopolysaccharide hinders polymorphonuclear leucocyte apoptosis

A prominent histologic feature of Helicobacter pylori infection is a dense infiltration of polymorphonuclear leukocytes (PMNL) in gastric mucosa. H. pylori lipopolysaccharide (LPS) has been recognized as a primary virulence factor evoking acute mucosal inflammatory reaction. Previous works have shown that H. pylori LPS immunologic activities are lower than those of enterobacterial LPS. However, the effect of H. pylori LPS on spontaneous PMNL apoptosis, and mechanisms by which this H. pylori LPS may promote PMNL survival remain to be established. In this study, we investigated, by both morphologic and biochemical approaches, the action of H. pylori LPS on PMNL apoptosis in vitro, using broth culture filtrates (BCF) of H. pylori strains with different genotypes. We found that BCF from H. pylori caused a significant delay in spontaneous PMNL apoptosis and this delay was independent of the VacA, cag pathogenicity island and urease status. We demonstrated that LPS in BCF is responsible for this effect because it was abrogated by the LPS antagonist B287 (a synthetic analog of Rhodobactersphaeroides lipid A). Moreover, BCF from H. pylori induced P42/44MAP kinase activation in PMNL. Similar results were obtained with BCF of an Escherichia coli strain. Taken together these data suggest that longer survival of PMNL induced by H. pylori LPS may increase gastric epithelium injury in H. pylori-associated diseases.

Inhibition of nonopsonic Helicobacter pylori-induced activation of human neutrophils by sialylated oligosaccharides

Certain strains of Helicobacter pylori have nonopsonic neutrophil-activating capacity. Some H. pylori strains and the neutrophil-activating protein of H.pylori (HPNAP) bind selectively to gangliosides of human neutrophils. To determine if there is a relationship between the neutrophil-activating capacity and the ganglioside-binding ability, a number of H. pylori strains, and HPNAP, were incubated with oligosaccharides, and the effects on the oxidative burst of subsequently challenged neutrophils was measured by chemiluminescence and flow cytometry. Both by chemiluminescence and flow cytometry a reduced response was obtained by incubation of H.pylori with sialic acid-terminated oligosaccharides, whereas lactose had no effect. The reductions obtained with different sialylated oligosaccharides varied to some extent between the H. pylori strains, but in general 3'-sialyllactosamine was the most efficient inhibitor. Challenge of neutrophils with HPNAP gave no response in the chemiluminescence assay, and a delayed moderate response with flow cytometry. Preincubation of the protein with 3'-sialyllactosamine gave a slight reduction of the response, while 3'-sialyllactose had no effect. The current results suggest that the nonopsonic H. pylori-induced activation of neutrophils occurs by lectinophagocytosis, the recognition of sialylated glycoconjugates on the neutrophil cell surface by a bacterial adhesin leads to phagocytosis and an oxidative burst with the production of reactive oxygen metabolites.

The immune response against Helicobacter pylori--a direct linkage to the development of gastroduodenal disease

Helicobacter pylori infects about half of the world's population. H. pylori elicits marked immune responses, but the infection is commonly life-long. Some infected individuals remain asymptomatic, while others develop significant gastroduodenal disease. We review the underlying host immune response to H. pylori which programs for persistence and evolution of gastroduodenal disease.

The Helicobacter pylori neutrophil-activating protein is an iron-binding protein with dodecameric structure

The neutrophil-activating protein (HP-NAP) of Helicobacter pylori is a major 17 kDa antigen of the immune response of infected individuals. Amino acid sequence comparison indicated a high similarity between HP-NAP and both bacterial DNA-protecting proteins (Dps) and ferritins. The structure prediction and spectroscopic analysis presented here indicate a close similarity between HP-NAP and Dps. Electron microscopy revealed that HP-NAP forms hexagonal rings of 9-10 nm diameter with a hollow central core as seen in Dps proteins, clearly different from the 12 nm icositetrameric (24 subunits) ferritins. However, HP-NAP is resistant to thermal and chemical denaturation similar to the ferritin family of proteins. In addition, HP-NAP binds up to 40 atoms of iron per monomer and does not bind DNA. We therefore conclude that HP-NAP is an unusual, small, ferritin that folds into a four-helix bundle that oligomerizes into dodecamers with a central hole capable of binding up to 500 iron atoms per oligomer.