Relationship between interleukin-8 levels and myeloperoxidase activity in human gastric mucosa

Helicobacter pylori secretary Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation

Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 μM diphenyleneiodonium (DPI), 50 μM salicyl hydroxamic acid (SHX), 5 μM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 μM of NOS2 inhibitor l-NMMA and 10 μM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 μM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS. This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.

The effect of Lactobacillus reuteri supplementation in Helicobacter pylori infection: a placebo-controlled, single-blind study

Background

Helicobacter pylori is the major cause of chronic gastritis, and considered as a risk factor for peptic ulcer and gastric cancer. The H. pylori standard antibiotic therapy fails in about 25–30% of cases, particularly because of the increasing occurrence of resistance to antibiotics. The aim of the current study was to investigate whether the strain Lactobacillus reuteri DSM17648 which has been previously shown to reduce Helicobacter pylori load additionally improves gastrointestinal symptoms in H. pylori positive subjects when used in a 28 days supplementation.

Methods

In a single-blinded, placebo controlled study 24 H. pylori-positive adults (13 females, 11 males; median age: 43.5) with mild dyspepsia (mean GSRS score: 11.82) received placebo for 28 days followed by Pylopass™ containing the L. reuteri DSM 17648 (2 × 10¹⁰ cells per day) for the following 28 days. After 28 days of Pylopass™ supplementation the change in H. pylori load was measured by ¹³C urea breath test (¹³C-UBT) and the change in symptoms were determined by the Gastrointestinal Symptom Rating Scale (GSRS). In addition, blood assessments were conducted to measure the physiological changes relevant in terms of safety.

Results

After a 28-day supplementation phase with Pylopass™ there was a trend for reduction of H. pylori load in 62.5% of the subjects and for the overall GSRS scores in 66.7% of subjects. The overall GSRS scores from baseline to day 56 following all 24 subjects undergoing the placebo phase followed by the Pylopass™ phase was significantly decreased (p = 0.005). The mean 13C-UBT δ value decreased by 22.5% during the Pylopass™ supplementation phase (− 3.14), while the mean 13C-UBT δ increased by 37.3% (+ 3.79) in the placebo phase. No side effects were reported in either study phase.

Conclusion

The results demonstrated that L. reuteri DSM17648 has the potential to suppress H. pylori infection, and may lead to an improvement of H. pylori-associated gastro intestinal symptoms. Further studies with adequate power should be performed.

Trial registration

Clinicaltrials.gov: NCT02051348 (January 30, 2014).

Oxidative stress: an essential factor in the pathogenesis of gastrointestinal mucosal diseases

Reactive oxygen species (ROS) are generated as by-products of normal cellular metabolic activities. Superoxide dismutase, glutathione peroxidase, and catalase are the enzymes involved in protecting cells from the damaging effects of ROS. ROS are produced in response to ultraviolet radiation, cigarette smoking, alcohol, nonsteroidal anti-inflammatory drugs, ischemia-reperfusion injury, chronic infections, and inflammatory disorders. Disruption of normal cellular homeostasis by redox signaling may result in cardiovascular, neurodegenerative diseases and cancer. ROS are produced within the gastrointestinal (GI) tract, but their roles in pathophysiology and disease pathogenesis have not been well studied. Despite the protective barrier provided by the mucosa, ingested materials and microbial pathogens can induce oxidative injury and GI inflammatory responses involving the epithelium and immune/inflammatory cells. The pathogenesis of various GI diseases including peptic ulcers, gastrointestinal cancers, and inflammatory bowel disease is in part due to oxidative stress. Unraveling the signaling events initiated at the cellular level by oxidative free radicals as well as the physiological responses to such stress is important to better understand disease pathogenesis and to develop new therapies to manage a variety of conditions for which current therapies are not always sufficient.

The effect on serum myeloperoxidase activity and oxidative status of eradication treatment in patients Helicobacter pylori infected

OBJECTIVES

Myeloperoxidase activity has been investigated after eradication of Helicobacter pylori (H. pylori) in infected patients in previous studies but the results are controversial. The aim of this study was to investigate effect on serum myeloperoxidase activity and oxidative status of eradication treatment in H. pylori-infected patients.

DESIGN AND METHODS

Gastric biopsy specimens were obtained from 30 H. pylori infected patients. Serum myeloperoxidase activity was measured by enzyme-linked immunoassay. Oxidative status was determined using total antioxidant capacity (TAC) and total oxidant status (TOS) measurement and calculation of oxidative stress index (OSI).

RESULTS

After 2 weeks of the eradication treatment, serum myeloperoxidase activity, TOS and OSI values were significantly lower (all; p<0.001), while TAC was significantly higher (p<0.001).

CONCLUSIONS

Our results indicate that eradication treatment in H. pylori-infected patients may affect both oxidative stress and myeloperoxidase activity which is an important biomarker in pathogenesis of atherosclerosis.

Inhibition of Helicobacter pylori infection in humans by Lactobacillus reuteri ATCC 55730 and effect on eradication therapy: a pilot study

BACKGROUND

Several studies report an inhibitory effect of probiotics on Helicobacter pylori.

AIM

To test whether Lactobacillus reuteri ATCC 55730 reduces H. pylori intragastric load in vivo, decreases dyspeptic symptoms, and affects eradication rates after conventional treatment.

MATERIALS AND METHODS

In a double-blind placebo-controlled study, 40 H. pylori-positive subjects were given L. reuteri once a day for 4 weeks or placebo. All underwent upper endoscopy, (13)C-urea breath test, and H. pylori stool antigen determination at entry and (13)C-urea breath test and H. pylori stool antigen (used as both qualitative and semiquantitative markers) after 4 weeks of treatment. Sequential treatment was administered subsequently to all.

RESULTS

In vivo, L. reuteri reduces H. pylori load as semiquantitatively assessed by both (13)C-urea breath test delta-value and H. pylori stool antigen quantification after 4 weeks of treatment (p < .05). No change was shown in patients receiving placebo. L. reuteri administration was followed by a significant decrease in the Gastrointestinal Symptom Rating Scale as compared to pretreatment value (p < .05) that was not present in those receiving placebo (p = not significant). No difference in eradication rates was observed.

CONCLUSIONS

L. reuteri effectively suppresses H. pylori infection in humans and decreases the occurrence of dyspeptic symptoms. Nevertheless, it does not seem to affect antibiotic therapy outcome.

Cellular mucosal defense during Helicobacter pylori infection: a review of the role of glutathione and the oxidative pentose pathway

Helicobacter pylori is the primary cause of gastritis and peptic ulcer disease and is known to infect greater than 50% of the world's population. It is also known to lead to the onset of gastric cancer and unless treated, lasts throughout life in most individuals. Mouse models of H. pylori infection have improved our ability to study this organism and can be used to investigate the host mucosal response to the infection, particularly the early events postinoculation. Previous studies have shown that H. pylori infection leads to an increased production of reactive oxygen species within the gastric mucosa which are thought to play a major role in the mediation of associated disease. Recent studies have shown differences in the availability of an important antioxidant, glutathione, during chronic H. pylori infection. The availability of glutathione is primarily controlled by the activity of the oxidative pentose pathway. This review proposes that the severity of inflammation and damage associated with H. pylori infection is dependent on the ability of mucosal cells to counteract the increased load of reactive oxygen species. It is hypothesized that the oxidative pentose pathway and glutathione availability are important factors modulating this response. It is suggested that the therapeutic regulation of glutathione availability could provide a novel method for preventing or reducing the damage caused during H. pylori infection.

13C-urea breath test: reproducibility and association with the severity of Helicobacter pylori-associated antral gastritis

BACKGROUND

The purpose of the present paper was to assess the reproducibility of the (13)C-urea breath test ((13)C-UBT) and its ability to reflect the level of Helicobacter pylori-associated inflammation.

METHODS

Asymptomatic H. pylori-positive subjects (n = 21) performed the (13)C-UBT six times. The H. pylori-positive symptomatic subjects (n = 55) performed the (13)C-UBT and had antral biopsies taken for histopathology, culture, urease activity assay and myeloperoxidase activity assay.

RESULTS

No significant intraindividual variation in (13)C-UBT results were observed for the asymptomatic subjects. The (13)C-UBT results were significantly higher in symptomatic subjects with a moderate to severe gastritis compared to a mild gastritis and to no inflammation (34.5 +/- 4.4 vs 17.7 +/- 2.8 vs 1.7 +/- 0.1, respectively, P < 0.01). The (13)C-UBT results significantly correlated with urease (r = 0.55) and myeloperoxidase activity (r = 0.82) but not with bacterial load. conclusion: The (13)C-UBT is a reproducible determinant of H. pylori infection and non-invasively assesses the severity of antral inflammation.

Production of chemokines and reactive oxygen species by human neutrophils stimulated by Helicobacter pylori

BACKGROUND

Bacteria have different characteristics in stimulation of human neutrophils to produce reactive oxygen species (ROS) and chemokines. This study examined the ability of Helicobacter pylori to induce production of ROS and chemokines by human neutrophils.

METHODS

H. pylori strains (1.5 x 108 CFU/ml) were cocultured with 5 x 104 neutrophils isolated from healthy subjects. Samples were incubated with human serum with or without IgG antibodies to H. pylori. ROS production was measured using luminol-dependent chemiluminescence (LmCL), and the concentrations of chemokines (IL-8, RANTES, MIP-1alpha and MCP-1) were measured by ELISA.

RESULTS

The mean of the highest LmCL (peak height; PH) value stimulated by H. pylori was 3318 in the absence of serum. PH increased to 4687 when incubated with anti-H. pylori antibody-positive sera (p <.001) but antibody-negative sera did not affect LmCL response. The mean final concentration of IL-8 produced in the absence of serum was 142.6 pg/ml. Increased IL-8 production was seen by addition of antibody positive serum (p <.01). IL-8 production was not significantly correlated with production of ROS. On the other hand, H. pylori stimulation did not induce neutrophil production of RANTES, MIP-1alpha or MCP-1.

CONCLUSIONS

H. pylori was capable of inducing IL-8 production by human neutrophils, but not C-C chemokines. Production of C-X-C dominant chemokine by neutrophils is consistent with the pathological characteristics of H. pylori-induced gastritis, where persistent neutrophil infiltration is present.

Colonisation density and topographic localisation of Helicobacter pylori do not depend on the cagA status

AIMS

To explore the correlation between the cagA status of Helicobacter pylori and the density and topographic localisation of H pylori.

METHODS

Gastric antral biopsy specimens were taken from 716 consecutive patients, including 293 H pylori positive patients (124 men, 169 women; mean age, 52.6 years; range, 12-87). A serum sample was taken for determination of IgG anti-CagA antibodies (sensitivity of 94.4% and specificity of 92.5%). The density of H pylori was assessed semiquantitatively (grades I-IV) in biopsy specimens stained with the modified Giemsa stain. Topographic localisation was classified as follows: score A, H pylori closely attached to the mucosa; score B, H pylori attached to the mucosa and in the mucus; and score C, H pylori solely in the mucus.

RESULTS

CagA antibodies were present in 154 (52.5%) of the patients. There was no significant difference in colonisation density and cagA status: grade I, 23 (14%); grade II, 78 (50.6%); grade III, 42 (27.5%); and grade IV, 11 (7.2%) in the cagA(+) strains and 29 (21.2%), 57 (40.8%), 38 (27%), and 15 (11%), respectively, in the cagA(-) strains. There was no difference in topographic localisation between cagA(+) and cagA(-)H pylori. Mean anti-CagA titres were 0.84, 0.84, 0.89, and 0.73 in patients with grades I-IV bacterial density, respectively.

CONCLUSION

Antibody titres do not correlate with H pylori density and there is no difference in density between cagA(+) and cagA(-)H pylori strains. In addition there is no difference in topographic localisation between cagA(+) and cagA(-) H pylori strains.

Interactions among gastric somatostatin, interleukin-8 and mucosal inflammation in Helicobacter pylori-positive peptic ulcer patients

BACKGROUND

To investigate whether Helicobacter pylori infection, but not drugs, affects gastric somatostatin, interleukin-8 (IL-8), histological inflammation through eradication therapy, and interactions among these parameters.

METHODS

Twenty-eight H. pylori-positive patients (21 males; mean age 47.0 years) with either gastric ulcer (GU: n = 11) or duodenal ulcer (n = 17) diagnosed endoscopically were treated with dual therapy. Eradication was defined as negative microbiologic tests and 13C-urea breath test. Levels of antral and gastric juice somatostatin and mucosal IL-8 were measured by radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Histology was assessed by the Sydney system.

RESULTS

H. pylori was eradicated in 15 patients (10 males, 6 GU) out of 28 (54%). The patients' backgrounds did not affect the eradication of H. pylori. Successes in eradication significantly increased antral and juice somatostatin contents, and dramatically decreased IL-8 levels and histological gastritis. In contrast, persistent H. pylori infection did not affect somatostatin and histological gastritis. An inverse correlation was present between changes in somatostatin levels and histological activity. No relationship was observed in changed values between antral somatostatin and IL-8.

CONCLUSIONS

These results indicate that eradication of H. pylori, but not the drugs used, induced an increase in somatostatin levels in the antrum and gastric juice, suggesting a close relationship between H. pylori and gastric somatostatin regulation. A close correlation between an increase in gastric somatostatin levels and the normalization of histological activity was present, suggesting that certain peptide-immune interactions in the gastric mucosa exist in H. pylori infection.

A sequential study of the pathology associated with the infection of sheep with adult and larval Ostertagia circumcincta

Disturbances in the physiology of the abomasa of sheep infected with either adult Ostertagia circumcincta given via abomasal cannulae, or larvae (L3) given intraruminally were matched by pathological changes in tissues collected by repeated mucosal biopsy. Within 2-3 days of the transplant of adult worms, abomasal pH had increased markedly in five out of six animals, and there also had been rapid increases in serum gastrin and pepsinogen concentrations in all animals. Reductions in parietal cell number were recorded as early as 1 day after the transplant of adults and were associated with the rapid accumulation of many neutrophils and eosinophils. Mucosal hyperplasia, with increased numbers of cells closer in appearance to mucous/mucous neck cells, was a relatively late development, being most pronounced in the latter part of the infection. In sheep given larvae, changes in secretory physiology were again matched by a concurrent fall in parietal cell number and by the accumulation of inflammatory cells. Changes became maximal when most worms could be expected to be present as adults, confirming the role of adults in the natural disease. Some abnormalities were detected in biopsies collected from animals maintained free of parasites and, although milder in degree, there were similarities to those observed in parasitised tissues, there being fewer parietal cells, a modest degree of mucous cell hyperplasia and inflammatory infiltrates of predominantly neutrophils. These changes were the likely result of trauma to the tissues in the immediate vicinity of the cannula, due either to the presence of the cannula itself or to the frequent collection of biopsy material from areas close to it.

Interleukin-8 expression by human neutrophils activated by Helicobacter pylori soluble proteins

BACKGROUND

Helicobacter pylori soluble proteins may serve as chemoattractants for neutrophils. Once extravasated and attracted to the gastric mucosa, neutrophils themselves may be a source of interleukin-8 (IL-8), further amplifying the inflammatory response. We evaluated IL-8 expression and the activation of human neutrophils by H. pylori products.

METHODS

After neutrophils had been stimulated with H. pylori culture supernatant, IL-8 mRNA expression was assessed by quantitative reverse transcription polymerase chain reaction, using synthetic standard RNA at 0, 1, 2, 4, and 9 h. The amount of IL-8 protein was measured by enzyme-linked immunosorbent assay (ELISA). Lymphocyte function-associated antigen-1beta (LFA-1beta) (CD18) expression was determined with flow cytometry, and myeloperoxidase secretion was analyzed with ELISA. After acetohydroxamic acid (AHA) and/or N-tert-butoxycarbonyl-methionyl-leucyl-phenylalanine (BOC-MLP) was added to H. pylori culture supernatant, IL-8 ELISA was analyzed for 9 h.

RESULTS

IL-8 mRNA expression by stimulated neutrophils was 16 to 67 times greater than by controls, peaking at 2 h after stimulation. The amount of IL-8 protein was markedly increased at 4 h after stimulation. H. pylori culture supernatant enhanced LFA-1beta expression and myeloperoxidase secretion by neutrophils. AHA and/or BOC-MLP decreased IL-8 production at 2-4 h after stimulation.

CONCLUSIONS

H. pylori-induced neutrophil recruitment may be mediated via IL-8 expressed by neutrophils activated by H. pylori soluble proteins. This may explain the gastric mucosal inflammatory response to the non-invasive organism.

Helicobacter pylori infection induces cyclooxygenase-2 expression in human gastric mucosa

Recent studies indicate that expression of mitogen-inducible cyclooxygenase-2 (COX-2) occurs in gastrointestinal tumors. We investigated the effects of Helicobacter pylori (H. pylori) infection, a class I carcinogen for the human stomach, on gastric COX-2 expression using immunohistochemistry. Human subjects without macroscopic lesions, as determined by endoscopic screening, were biopsied for H. pylori infection. The biopsy samples were immunohistochemically examined for COX-2 expression. COX-2 was expressed in gastric epithelia and subepithelial inflammatory cells in all H. pylori-infected subjects. There was no expression of COX-2 in the gastric mucosa of H. pylori-negative subjects. COX-2 expression has been reported in gastrointestinal carcinomas, gastrointestinal cancer cell-lines, and in the gut after carcinogenic treatment. The present study demonstrates that H. pylori infection leads to gastric mucosal expression of COX-2, indicating that the enzyme is involved in H. pylori-related gastric pathology in humans.