Impaired host immunity contributes to Helicobacter pylori eradication failure

Association between triglyceride-glucose index and Helicobacter pylori infection: a cross-sectional study

Background

Mounting research suggests that insulin resistance (IR) is associated with Helicobacter pylori (H. pylori) infection. The triglyceride-glucose (TyG) index has received widespread attention due to its high sensitivity in assessing IR. This study examined the association between H. pylori infection and TyG index.

Methods

This cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 1999 - 2000. Participants were categorized into quartile groups (Q1-Q4) based on their TyG index. Weighted multivariable-adjusted logistic regression and subgroup analysis were used to explore the correlation between TyG index and H. pylori infection. Furthermore, sensitivity analysis was conducted to assess the robustness of our findings.

Results

This study included 2,918 participants, 1,101 of whom were infected with H. pylori. The mean TyG index for all participants was 8.56 ± 0.67. Patients who were H. pylori positive had higher levels of TyG index compared with H. pylori seronegative participants (8.74 ± 0.03 vs. 8.57 ± 0.03, P < 0.05). The fourth quartile of the TyG index showed the highest odds of H. pylori infection compared to Q1 (OR = 2.37, 95%CI: 1.52 to 3.71, P  <  0.001). Sensitivity analysis indicated that the association between TyG index and H. pylori infection remained strong even after excluding participants with cardiovascular diseases or taking lipid-lowering medications, as well as patients with diabetes or taking glucose-lowering medications.

Conclusions

In this study, a stable and strong positive association was found between TyG index and H. pylori infection. IR may be significantly associated with H. pylori infection. Further studies are necessary to elucidate the underlying mechanisms and potential clinical implications of these findings.

Association between Helicobacter pylori infection and type 2 diabetes mellitus: a retrospective cohort study and bioinformatics analysis

PURPOSE

This study aimed to preliminarily investigate the association and possible mechanisms between Helicobacter. pylori (H. pylori) infection and type 2 diabetes mellitus (T2DM) through data collection, statistical analysis, and bioinformatics analysis.

METHODS

A retrospective cohort study, including a total of 4406 participants who attended annual health checkups at Xian GEM Flower Changqing Hospital, was conducted to explore the correlation between the incidence of T2DM and H. pylori infection. To uncover the potential mechanisms underlying the interaction between the two diseases, differentially expressed genes (DEGs) common to T2DM and H. pylori infection were identified using the GEO database and Venn diagrams. These DEGs were then analyzed through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and protein-protein interaction (PPI) analysis.

RESULTS

In total, 2053 participants were classified into the H. pylori-positive group and 2353 into the H. pylori-negative group. H. pylori infection was associated with a higher risk of T2DM occurrence (adjusted HR 1.59; 95% CI 1.17-2.15, P = 0.003). The average disease-free survival time was 34.81 months (95% CI 34.60-35.03 months) in the H. pylori positive group and 35.42 months (95% CI 35.28-35.56 months) in the H. pylori negative group. Multivariate analysis and subgroup analyses also showed that H. pylori infection increased the risk of developing T2DM. A total of 21 DEGs between T2DM and H. pylori infection were identified and enriched in 7 signaling pathways, indicating specific protein interactions.

CONCLUSIONS

The prevalence of T2DM was associated with H. pylori infection. T2DM and H. pylori infection may interact with each other through metabolic and immune pathways.

Is Diabetes Mellitus a Predisposing Factor for Helicobacter pylori Infections?

PURPOSE OF REVIEW

This review aims to analyse the consistency of reports suggesting the role of Diabetes Mellitus in the pathogenesis of Helicobacter pylori (H. pylori).

RECENT FINDINGS

There have been numerous controversies citing the prevalence of H. pylori infections in patients suffering from type 2 diabetes mellitus (T2DM). This review investigates the possible crosstalk between H. pylori infections and T2DM and also designs a meta-analysis to quantify the association. Subgroup analyses have also been conducted to deduce factors like geography and testing techniques, in playing a role in stratification analysis. Based on a scientific literature survey and meta-analysis of databases from 1996 to 2022, a trend towards more frequent H. pylori infections in patients with diabetes mellitus was observed. The highly diversified nature of H. pylori infections across age, gender, and geographical regions requires large interventional studies to evaluate its long-term association with diabetes mellitus. Further possible linkage of the prevalence of diabetes mellitus concomitant with that of H. pylori infected patients has also been delineated in the review.

Recent research progress on the correlation between metabolic syndrome and Helicobacter pylori infection

Background

Globally, metabolic syndrome (MS) and Helicobacter pylori (HP) infection, which have gained an epidemic status, are major challenges to human health, society, and medical professionals. Recent studies have demonstrated that MS is closely related to HP infection. Additionally, HP is an important risk factor for gastric cancer. However, systematic reviews on HP are lacking. This review aimed to summarize and analyze the potential correlation of HP infection with MS and its components, as well as the underlying mechanism, to provide reference and strategies for clinical prevention and treatment.

Methodology

Previous studies examining the correlation between HP and MS since 1990 were retrieved from the PubMed, Web of Science, and Embase databases. The potential correlation between HP infection and MS and its components was comprehensively analyzed. The keywords "Helicobacter pylori," "HP," "metabolic syndrome," "hypertension," "obesity," "diabetes," or "dyslipidemia" were used in all fields. No language restrictions were imposed.

Results

MS was strongly correlated to HP infection. The inflammatory response and inflammatory factors produced during HP infection are important etiological factors for insulin resistance and MS. The co-occurrence of long-term chronic inflammation and immune dysfunction with MS may be the predisposing factor for HP infection. MS components, such as diabetes, hypertension, dyslipidemia, and obesity were also correlated with HP infection in one or both directions.

Conclusions

HP infection and MS may promote the pathogenesis of each other. The contribution of HP infection and MS to gastric cancer cannot be ruled out based on co-occurrence. The MS components diabetes and obesity may be bidirectionally correlated with HP infection.

Association between Helicobacter pylori infection and the risk of type 2 diabetes mellitus based on a middle-aged and elderly Chinese population

Evidence about the relationship between Helicobacter pylori (Hp) infection and type 2 diabetes mellitus (T2DM) is inconsistent and contradictory. This study attempted to investigate this association in the middle-aged and elderly Chinese population and analyze the joint effects of Hp infection and some risk factors on T2DM. Following a cross-sectional design, participants were recruited from the First Affiliated Hospital of Anhui Medical University in Hefei City, China. Hp status was measured using a ¹⁴C urea breath test. A total of 1,288 participants, including 90 diabetic patients and 1,198 nondiabetic subjects, were recruited in the current study. The participants with T2DM had a greater prevalence of Hp infection than participants without T2DM (26.67% versus 18.11%, p = 0.045). Furthermore, we found that Hp infection was closely associated with an incremental risk of T2DM [odds ratio (OR) = 1.77, 95% confidence intervals (CI): 1.04-3.00] after adjustment for potential confounders. In addition, we observed that the participants who were Hp-positive and ≥60 years old (OR = 9.16, 95% CI: 3.29-25.52), Hp-positive and obese (OR = 3.35, 95% CI: 1.57-7.14) or Hp-positive and hypertensive (OR = 6.10, 95% CI: 3.10-12.01) had a significantly higher risk for T2DM than those who were Hp-negative and ≤50 years old, Hp-negative and nonobese or Hp-negative and nonhypertensive. These findings imply that Hp infection is associated with an increased risk of T2DM in the middle-aged and elderly Chinese population. The association could be further elevated by the combination of Hp infection and some traditional risk factors.

The association between gastric bacterial infection and low level of vitamin D among patients with type 2 diabetes mellitus

Objectives: The present research aimed to find an association between infection by Helicobacter pylori and vitamin D deficiency in type 2 diabetic Iraqis attending Al-Yarmouk Teaching Hospital. Methods: According to fasting blood glucose, the samples were divided into a non-diabetic group with ten diabetic individuals and a diabetic group with thirty individuals. Results: The anti-H. pylori (IgG) levels were 86.77±58.62 NTU/μL in diabetic patients compared with 10.12_7.40 NTU/μL in non-diabetic group. Vitamin D levels were decreased significantly in infected patients compared to non-infected subjects. Conclusion: The H. pylori-infected patients have recorded the lowest level of vitamin D than non-infected individuals.

Helicobacter pylori infection is associated with diabetes among Chinese adults

AIMS/INTRODUCTION

Several epidemiological studies investigated the effect of Helicobacter pylori infection on diabetes, but the conclusions remained inconsistent. We aimed to explore the relationship between H. pylori infection and diabetes, as well as glycemic metabolism profiles.

MATERIALS AND METHODS

A cross-sectional study including 58,482 Chinese adults was carried out between January 2016 and December 2017. H. pylori infection was diagnosed by the 13 C-urea breath test. Multivariate regression analyses were carried out to evaluate the association of H. pylori infection with diabetes.

RESULTS

Of the 58,482 participants, 3,449 (5.9%) had diabetes. The H. pylori-positive participants had a higher rate of diabetes (7.3% vs 5.2%, P < 0.001), and higher levels of fasting plasma glucose (5.36 ± 1.12 mmol/L vs 5.28 ± 0.95 mmol/L, P < 0.001) and glycated hemoglobin A1c (5.63 ± 0.68% vs 5.57 ± 0.60%, P < 0.001) than the H. pylori negative group. Multivariate regression analyses showed that H. pylori infection was positively related to diabetes (odds ratio 1.25, 95% confidence interval 1.15-1.35). Among the H. pylori-positive participants, the elevated levels of fasting plasma glucose and glycated hemoglobin A1c were 0.033 mmol/L (95% confidence interval 0.016-0.049 mmol/L) and 0.024% (95% confidence interval 0.008-0.041%), respectively. Additionally, H. pylori infection was significantly related to diabetes in participants aged ≥44 years, but not in participants aged <44 years.

CONCLUSIONS

The present study showed that H. pylori infection is associated with diabetes among Chinese adults. More attention should be paid to adults with H. pylori infection for effective prevention of diabetes.

The Interaction of Helicobacter pylori Infection and Type 2 Diabetes Mellitus

Helicobacter pylori is one of the most common human pathogens that can cause gastrointestinal (GI) disorders, including simple gastritis, gastric ulcer, and malignant gastritis. In some cases, such as immunodeficiency and underlying diseases, it can be problematic as opportunistic infections. Diabetes mellitus (type 2) (T2DM) is one of the H. pylori underlying diseases. Since GI problems are observed in diabetic patients, it is necessary to treat H. pylori infection. In this review, we aimed to evaluate the possible relationship between H. pylori and T2DM according to epidemiological surveys of 70 studies retrieved from databases, including Scopus, PubMed, and Google Scholar about the relationship between H. pylori and T2DM, and discuss the reported background mechanisms of this correlation. According to the results of our study, the different studies have shown that H. pylori is more prevalent in Type 2 diabetic patients than healthy individuals or nondiabetic patients. The reason is development of H. pylori infection-induced inflammation and production of inflammatory cytokines as well as different hormonal imbalance by this bacterium, which are associated with diabetes mellitus. On the other hand, by tracing anti-H. pylori antibodies in patients with diabetes mellitus and occurrence of symptoms such as digestive problems in >75% of these patients, it can be concluded that there is a relationship between this bacterium and T2DM. Considering the evidence, it is crucially important that the probability of infection with H. pylori is evaluated in patients with T2DM so that medical process of the patient is followed with higher cautious.

How far are we from vaccination against Helicobacter pylori infection?

INTRODUCTION

Helicobacter pylori infection results in chronic gastritis, peptic ulcer, or gastric cancer; therefore, eradication of this bacterium is essential. The strategy for developing effective vaccines against H. pylori entails immunization of mice with a combination of classical and recombinant H. pylori antigens, but this has proven to be onerous in all cases.

AREAS COVERED

We have reviewed literature databases in PubMed and Scopus using the key words H. pylori, vaccine, and vaccination and have conducted a systematic review of published clinical trials and animal model studies on vaccines against H. pylori and have tried to summarize why the vaccines are not effective or only partially effective.

EXPERT COMMENTARY

This is the perfect time to review vaccine development against H. pylori as, after several failed attempts, promising results were reported by Zeng et al. in 2015. Successful vaccine development requires knowledge of both the immune mechanisms active during natural infection by H. pylori, owing to the complicated host response against the pathogen, and the factors that allow the persistence of bacteria, such as genetic diversity of H. pylori. Moreover, various clinical trials are needed to prove vaccine efficacy.

Olfactomedin-4 in digestive diseases: A mini-review

Olfactomedin-4 (OLFM4, GW112, hGC-1) is a glycoprotein belonging to the olfactomedin family. The expression of OLFM4 is strong in the small intestine, colon and prostate, and moderate in the stomach and bone marrow. Previous studies have revealed that OLFM4 is closely associated with many digestive diseases. Up-regulation of OLFM4 has been detected in the Helicobacter pylori (H. pylori)-infected gastric mucosa, inflammatory bowel disease tissue and gastrointestinal malignancies, including gastric cancer, colorectal cancer, pancreatic cancer and gallbladder cancer. Down-regulation of OLFM4 has also been detected in some cases, such as in poorly differentiated, advanced-stage and metastatic tumors. Studies using OLFM4-deficient mouse models have revealed that OLFM4 acts as a negative regulator of H. pylori-specific immune responses and plays an important role in mucosal defense in inflammatory bowel disease. Patients with OLFM4-positive gastric cancer or colorectal cancer have a better survival rate than OLFM4-negative patients. However, the prognosis is worse in pancreatic cancer patients with high levels of expression of OLFM4. The NF-κB, Notch and Wnt signaling pathways are involved in the regulation of OLFM4 expression in digestive diseases, and its role in pathogenesis is associated with anti-inflammation, apoptosis, cell adhesion and proliferation. OLFM4 may serve as a potential specific diagnostic marker and a therapeutic target in digestive diseases. Further studies are required to explore the clinical value of OLFM4.

Strategies used by helicobacter pylori to establish persistent infection

Helicobacter pylori (H. pylori) is a Gram-negative and motile bacterium that colonizes the hostile microniche of the human stomach, then persists for the host's entire life, if not effectively treated. Clinically, H. pylori plays a causative role in the development of a wide spectrum of diseases including chronic active gastritis, peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Due to the global distribution of H. pylori, it is no exaggeration to conclude that smart strategies are contributing to adaptation of the bacterium to its permanent host. Thirty-four years after the discovery of this bacterium, there are still many unanswered questions. For example, which strategies help the bacterium to survive in this inhospitable microniche? This question is slightly easier to answer if we presume the same clinical concept for both persistent infection and disease. Understanding the mechanisms governing H. pylori persistence will improve identification of the increased risk of diseases such as gastric cancer in patients infected with this bacterium. A well-defined and long-term equilibrium between the human host and H. pylori allows bacterial persistence in the gastric microniche; although this coexistence leads to a high risk of severe diseases such as gastric cancer. To escape the bactericidal activity of stomach acid, H. pylori secretes large amounts of surface-associated and cytosolic urease. The potential to avoid acidic conditions and immune evasion are discussed in order to explain the persistence of H. pylori colonization in the gastric mucosa, and data on bacterial genetic diversity are included. Information on the mechanisms related to H. pylori persistence can also provide the direction for future research concerning effective therapy and management of gastroduodenal disorders. The topics presented in the current review are important for elucidating the strategies used by H. pylori to help the bacterium persist in relation to the immune system and the many unfavorable features of living in the gastric microniche.

Association of Helicobacter pylori infection with type 2 diabetes

The last three decades have witnessed a rapid rise in the number of people with type 2 diabetes (T2DM), and China has the largest population of diabetes in the world. Patients with T2MD are more susceptible to a variety of infections due to impaired host immunity. Helicobacter pylori (H. pylori) hosted in the human stomach is the pathogen of a series of gastric and extragastric diseases, and has infected > 50% of the world population. H. pylori infection is rapidly becoming a serious threat to public health. Epidemiological surveys have indicated an obvious relationship between H. pylori and diabetes. H. pylori infection in T2MD cases can induce systemic inflammation, increase the risk of diabetic nephropathy and retinopathy, and is associated closely with the micro- and macro-vascular complications. Chronic H. pylori infection may have a harmful impact on pancreatic β-cells and may be a risk factor for T2MD and insulin resistance. Treatment of H. pylori infection and control of T2MD are becoming increasingly challenging due largely to the huge population of patients with the two diseases and to the relative complexity of treatment regimens. Further clinical and basic studies are needed to control H. pylori infection and T2MD effectively.

Implication of Cytotoxic Helicobacter pylori Infection in Autoimmune Diabetes

Background. Type 1 diabetes (T1D) and type 2 diabetes (T2D) have been linked to Helicobacter pylori infection, although results are conflicting. No previous study addressed a possible link between H. pylori infection and latent autoimmune diabetes in adults (LADA). In this study, a correlation among H. pylori infection and the risk of autoimmune diabetes in comparison with T2D was investigated. Methods. Sera from 234 LADA patients, 105 patients with late-onset T1D, and 156 patients with T2D were analyzed for anti-H. pylori and the cytotoxin-associated antigen (CagA) IgG antibodies. Results. H. pylori seroprevalence was comparable in LADA (52%), late-onset T1D (45%), and T2D (49%) with no gender differences. The seroprevalence of CagA IgG was significantly higher in autoimmune diabetes (late-onset T1D: 45%, LADA: 40%) compared to T2D (25%; p < 0.028). Conclusions. Although H. pylori seroprevalence was similar in LADA, T1D, and T2D, anti-CagA positivity was significantly increased among patients with autoimmune diabetes, suggesting that more virulent H. pylori strains might be a trigger for immune mechanisms involved in their pathogenesis.

Potential effect of chronic Helicobacter pylori infection on glucose metabolism of Mongolian gerbils

AIM: To assess the effect of Helicobacter pylori (H. pylori) infection on metabolic parameters in Mongolian gerbils.

METHODS: A total of 40 male, 5- to 8-wk-old, specific-pathogen-free Mongolian gerbils (30-50 g) were randomly allocated into two groups: a control group (n = 20) and an H. pylori group (n = 20). After a two-week acclimation period, the control group was administered Brucella broth and the H. pylori group was challenged intra-gastrically five times every other day with approximately 10⁹/CFU H. pylori ATCC43504 (CagA+, VacA+). Each group was then divided into two subgroups, which were sacrificed at either 6 or 12 mo. The control and H. pylori subgroups each contained 10 Mongolian gerbils. Body weight, abdominal circumference, and body length were measured, and body mass index (BMI) and Lee’s index were calculated. Biochemical assays were used to detect serum indexes, including glucose, glycated hemoglobin (GHb), glycated hemoglobin A1c (HbA1c), triacylglycerol, and total cholesterol, using an automatic biochemistry analyzer. Inflammatory cytokines, including interleukin (IL)-1β, IL-2, IL-4, IL-10, IL-12, tumor necrosis factor-α (TNF-α) and interferon (IFN)-γ, were assayed using ELISA. The expression of insulin and insulin-like growth factor 1 (IGF-1) was detected by immunohistochemistry, and islet apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

RESULTS: At each time point, body weight, abdominal circumference, BMI, and Lee’s index were increased after H. pylori infection. However, these differences were not significant. H. pylori infection significantly increased the GHb (5.45 ± 0.53 vs 4.98 ± 0.22, P < 0.05) and HbA1c (4.91 ± 0.61 vs 4.61 ± 0.15, P < 0.05) levels at 12 mo. We observed no significant differences in serum biochemical indexes, including fasting blood glucose, triacylglycerol and total cholesterol, at 6 or 12 mo after infection. H. pylori infection significantly increased the expression of IGF-1 (P < 0.05). Insulin levels from the pancreas and the apoptotic rate of islet β-cells remained unchanged. Also, we observed no significant differences among cytokines levels, including IL-1β, IL-2, IL-4, IL-10, IL-12, TNF-α and IFN-γ. IL-4 was the only exception, which increased at 6 (44.36 ± 25.17 vs 17.38 ± 3.47, P < 0.05) and 12 mo (33.41 ± 10.00 vs 18.91 ± 5.31, P < 0.05) after H. pylori infection.

CONCLUSION: Long-term H. pylori infection is significantly associated with high levels of HbA1c in Mongolian gerbils, indicating a potential role of H. pylori infection in glucose dysregulation.

Helicobacter pylori vs immune system or antibiotics

Helicobacter pylori (H. pylori) infection has often no clinical signs and is one of the most common bacterial infections. All infected subjects have histology of active chronic gastritis. In some cases patients develop peptic ulcer and minority of them develop gastric cancer. Gastric cancer is multifactorial disease, thus various progressions of H. pylori infection and disease are dependent on the host genetic factors, the characteristics of the individual’s immune response, environmental factors, and different bacterial virulence factors of the individual bacterial strains. Eradication of the bacteria plays a crucial role in the treatment of these cases however antibiotic therapy does not always help. Bacteria often develop resistance to antibiotics so we recommend that not only screening for H. pylori also the strain determination should have some diagnostic value, especially in the patients who already developed gastritis. Furthermore, for such patients assessment of disease progression (atrophic or metaplastic gastritis) could be followed by polymorphism determination. Until now we cannot predict the disease based only on single polymorphism. Bacteria successfully neutralize the responses of the immune systems using different enzymes or even components of the host immune response. However, the influence of immune system and its components could represent new ways of treatments and could help to eradicate the infection.

Helicobacter pylori infection and insulin resistance in diabetic and nondiabetic population

Helicobacter pylori (HP) is a common worldwide infection with known gastrointestinal and nongastrointestinal complications. One of the gastrointestinal side effects posed for this organism is its role in diabetes and increased insulin resistance. The aim of this study was to evaluate the association between HP and insulin resistance in type 2 diabetic patients and nondiabetics. This cross-sectional study was carried out from May to December 2013 on 211 diabetic patients referred to diabetes clinic of Shahid Beheshti Hospital of Qom and 218 patients without diabetes. HP was evaluated using serology method and insulin resistance was calculated using HOMA-IR. The prevalence of H. pylori infection was 55.8% and 44.2% in diabetics and nondiabetics (P = 0.001). The study population was divided into two HP positive and negative groups. Among nondiabetics, insulin resistance degree was 3.01 ± 2.12 and 2.74 ± 2.18 in HP+ and HP- patients, respectively (P = 0.704). Oppositely, insulin resistance was significantly higher in diabetic HP+ patients rather than seronegative ones (4.484 ± 2.781 versus 3.160 ± 2.327, P = 0.013). In diabetic patients, in addition to higher prevalence of HP, it causes a higher degree of insulin resistance.

The immune response and antibacterial therapy

The host's immune defence mechanisms are indispensable factors in surviving bacterial infections. However, in many circumstances, the immune system alone is inadequate. Since the 1940s, the use of antibacterial therapy has saved millions of lives, improving the span and quality of life of individuals. Unfortunately, we are now facing an era where antibacterial agents are threatened by resistance. In addition to targeting bacteria, some antibacterial agents affect various aspects of the immune response to infection. Since many antibacterial drugs are failing in efficacy due to resistance, it has been strongly suggested that any synergy between these drugs and the immune response be exploited in the treatment of bacterial infections. This review explores the influence of antibacterial therapy on the immune response and new approaches that could exploit this interaction for the treatment of bacterial infections.

Helicobacter pylori infection and diabetes: Is it a myth or fact?

Helicobacter pylori (H. pylori) is one of the most common human bacterial pathogens, and infection causes a wide array of gastric disorders, including simple gastritis, peptic ulcers and gastric malignancies. Gastrointestinal inflammation caused by H. pylori can influence the absorption of glucose and lipids, which are also abnormal in diabetes mellitus. Type 2 diabetes mellitus (T2DM), formerly known as non-insulin-dependent diabetes mellitus or adult-onset diabetes, is a metabolic disorder that is characterized by high levels of blood glucose resulting from insulin resistance and relative insulin deficiency. It is an emerging pandemic and is rapidly becoming a serious threat to public health. Emerging data now indicate a strong relationship between H. pylori infection and the incidence of T2DM. The mechanisms underlying the pathogenesis of diabetes are complex, involving insulin resistance, chronic inflammation, insulin secretion deficiency as a result of pancreas β-cell dysfunction, glucotoxicity, and lipotoxicity. H. pylori infection is known to be involved in the pathogenesis of insulin resistance, and the growing awareness of its role in diabetes is important for the early detection of glucose dysregulation and prevention of T2DM in high-risk communities. This review probes the possible relationship between H. pylori and diabetes according to epidemiological surveys and discusses putative mechanisms underlying this correlation.

Differences in the antigens of Helicobacter pylori strains influence on the innate immune response in the in vitro experiments

The immune response to Helicobacter pylori importantly determines the pathogenesis of infection as well as the success of antibiotic eradication of the bacteria. Strains of H. pylori were gathered from 14 patients who failed to eradicate H. pylori infection with antibiotics—therapy resistant strains (TRS)—or from patients who were able to eradicate H. pylori infection—therapy susceptible strains (TSS). The THP-1 cells were stimulated with H. pylori antigens. Cathepsin X expression on THP-1 cells and concentration of cytokines in the supernatant of THP-1 cells were measured with a flow cytometer. TSS H. pylori antigens increased the proportion of cathepsin X positive cells compared to TRS H. pylori antigens. TSS H. pylori antigens induced higher secretion of IL-12 and IL-6 compared to TRS H. pylori antigens (P < 0.001; 0.02). Polymyxin B, a lipid A inhibitor, lowered the secretion of IL-12 and IL-6 in TRS and TSS. We demonstrated a H. pylori strain-dependent cathepsin X and cytokine expression that can be associated with H. pylori resistance to eradication due to lack of effective immune response. Differences in lipid A of H. pylori might have an influence on the insufficient immune response, especially on phagocytosis.

Helicobacter pylori susceptible/resistant to antibiotic eradication therapy differ in the maturation and activation of dendritic cells

BACKGROUND

The natural course of Helicobacter pylori infection, as well as the success of antibiotic eradication is determined by the immune response to bacteria. The aim of the study is to investigate how different Helicobacter pylori isolates influence the dendritic cells maturation and antigen-presenting function in order to elucidate the differences between Helicobacter pylori strains, isolated from the patients with successful antibiotic eradication therapy or repeated eradication failure.

MATERIALS AND METHODS

Dendritic cells maturation and antigen presentation were monitored by flow cytometry analysis of the major histocompatibility complex class II (MHC-II), Toll-like receptor (TLR) and costimulatory molecules expression, and by determining cytokine secretion.

RESULTS

Dendritic cells stimulated with Helicobacter pylori isolated from patients with repeated antibiotic eradication failure expressed less human leukocyte antigen (HLA-DR), CD86, TLR-2, and interleukin-8 (IL-8) compared to Helicobacter pylori strains susceptible to antibiotic therapy; the latter expressed lower production of IL-10. Polymyxin B inhibition of lipopolysaccharide reduces IL-8 secretion in the group of Helicobacter pylori strains susceptible to antibiotic therapy. The differences in IL-8 secretion between both groups are lipopolysaccharide dependent, while the differences in secretion of IL-10 remain unchanged after lipopolysaccharide inhibition. Inhibitor of cathepsin X Mab 2F12 reduced the secretion of IL-6, and the secretion was significantly lower in the group of Helicobacter pylori strains isolated from patients with repeated antibiotic eradication failure.

CONCLUSION

Helicobacter pylori strains, susceptible/resistant to antibiotic eradication therapy, differ in their capability to induce DCs maturation and antigen-presenting function.

Inhibition of cathepsin X enzyme influences the immune response of THP-1 cells and dendritic cells infected with Helicobacter pylori

Background

The immune response to Helicobacter pylori importantly determines the outcome of infection as well as the success of eradication therapy. We demonstrate the role of a cysteine protease cathepsin X in the immune response to H. pylori infection.

Materials and methods

We analysed how the inhibition of cathepsin X influenced the immune response in experiments when THP-1 cells or dendritic cells isolated from patients were stimulated with 48 strains of H. pylori isolated from gastric biopsy samples of patients which had problems with the eradication of bacteria.

Results

The experiments, performed with the help of a flow cytometer, showed that the expression of Toll-like receptors (TLRs), especially TLR-4 molecules, on the membranes of THP-1 cells or dendritic cells was higher when we stimulated cells with H. pylori together with inhibitor of cathepsin X 2F12 compared to THP-1 cells or dendritic cells stimulated with H. pylori only, and also in comparison with negative control samples. We also demonstrated that when we inhibited the action of cathepsin X in THP-1 cells, the concentrations of pro-inflammatory cytokines were lower than when THP-1 cell were stimulated with H. pylori only.

Conclusions

We demonstrated that inhibition of cathepsin X influences the internalization of TLR-2 and TLR-4. TLR-2 and TLR-4 redistribution to intra-cytoplasmic compartments is hampered if cathepsin X is blocked. The beginning of a successful immune response against H. pylori in the case of inhibition of cathepsin X is delayed.

Association between Helicobacter pylori infection and diabetes mellitus: a meta-analysis of observational studies

AIMS

Some studies have shown Helicobacter pylori (H. pylori) infection to be associated with diabetes mellitus, but the relationship remains controversial. This meta-analysis was designed to quantify the association between H. pylori infection and diabetes.

METHODS

A computerized search of PubMed and Embase was carried out. Studies that provided data on H. pylori infection in both diabetes and control groups were selected. An unconditional logistic regression model was used to analyze potential parameters related to H. pylori prevalence. Subgroup analyses were conducted for types of diabetes, methods of detection, geographical distribution, hemoglobin A1c (HbA1c) levels and evidence grade.

RESULT

Forty-one studies were identified, involving 14,080 patients, with a total H. pylori infection rate of 42.29%. The OR for H. pylori infection was increased to 1.33 (95% CI: 1.08-1.64; P=0.008) among the patients with diabetes. Subgroup analysis revealed a significantly higher infection rate of H. pylori in the type 2 diabetes group versus the control group: OR=1.76, 95% CI: 1.40-2.21, P<0.00001.

CONCLUSIONS

The pooled data suggests a trend toward more frequent H. pylori infections in diabetes patients, especially in type 2 diabetes patients. As this is a meta-analysis of observational studies, more randomized controlled trials should be done in the future.

Evaluation of CD103 (αEβ7) integrin expression by CD8 T cells in blood as a surrogate marker to predict cervical T cell responses in the female genital tract during HIV infection

Mucosal homing receptors expressed by blood T cells may be useful surrogates for measuring mucosal T cell immune responses at the site of HIV transmission. Here, we investigated whether HIV-specific responses by T cells expressing the mucosal integrin receptor CD103 in blood reliably predicted corresponding HIV-specific responses at the cervix. The frequency of CD8+ T cells expressing CD103 in blood correlated significantly with the number of CD103+CD8+ T cells from the cervix suggesting that CD103 was involved in trafficking of T cells from blood to the cervical mucosa. TGF-β concentrations in plasma were significantly associated with the frequency of CD103 expression by blood but not cervical CD8 T cells. The majority of Gag-responsive CD8 T cells were CD103+ in both blood and at the cervix. Despite this, the magnitude of Gag-specific IFN-γ responses by CD103+CD8+ T cells in blood did not predict similar Gag-specific responses at the cervix.

Smoking and drinking habits are important predictors of Helicobacter pylori eradication

PURPOSE

The aim of the study was to evaluate the effect of smoking and drinking habits, in separate and joint analyses, on the efficacy of H. pylori eradication.

MATERIALS AND METHODS

A total of 250 patients were recruited. They were treated with a 7-day course of omeprazole, amoxicillin, tinidazole (OAT), omeprazole amoxicillin, clarithromycin (OAC) or omeprazole, clarithromycin, tinidazole (OCT). The efficacy of H. pylori eradication was tested with a CLO-test and histology 4 weeks after the completion of antibacterial therapy.

RESULTS

Drinking was found not to affect the efficacy of H. pylori eradication in any therapeutic group, while smoking decreased it in the OAC group (smokers 69.6%, non-smokers 94.3%, p=0.006). In the OAT treated group H. pylori eradication rate was lower in smokers-non-drinkers than in smokers-drinkers and non-smokers-non-drinkers (38.9% vs 83.2% and 70.0%, p=0.002 and p=0.034, respectively), while in the OAC treated group, smokers-non-drinkers had lower eradication efficacy than non-smokers-drinkers and non-smokers-non-drinkers (59.1% vs 100% and 91.3%, p=0.01 and p=0.012, respectively). In the OCT treated group, differences between subgroups were not significant.

CONCLUSIONS

Smoking and drinking habits when analyzed jointly are more useful to predict the outcome of H. pylori eradication than when analyzed separately.

Levels of interleukin-18 are markedly increased in Helicobacter pylori-infected gastric mucosa among patients with specific IL18 genotypes

BACKGROUND

The cellular immune response in gastric mucosa infected with Helicobacter pylori is proposed to be predominantly of the T helper cell type 1 type.

METHODS

Interleukin (IL)-18, IL-12, and interferon (IFN)-gamma levels were measured in gastric mucosal biopsy specimens by reverse-transcription polymerase chain reaction (PCR) and by enzyme-linked immunosorbent assay; IL18 polymorphisms were determined by PCR.

RESULTS

Biopsy specimens from 128 patients (56 with nonulcer dyspepsia, 28 with gastric ulcers, 28 with duodenal ulcers, and 16 with gastric cancer) were examined; 96 patients had H. pylori infection. IL-18 levels were markedly up-regulated in mucosa infected with H. pylori (P < .001), whereas IL-12 and IFN-gamma levels were independent of H. pylori status. IL-18 levels correlated with IFN-gamma levels only in infected patients (R = 0.31 to R = 0.51). IL-18 levels were the determining factor for monocyte infiltration in H. pylori-infected mucosa (P < .001). H. pylori-infected patients displaying IL18 -607C/C and -137G/G had higher IL-18 levels than did those with other genotypes and were more likely to experience treatment failure.

CONCLUSION

H. pylori infection induces IL-18 in the gastric mucosa. H. pylori-infected patients with IL18 -607C/C and -137G/G have higher IL-18 levels, which causes severe gastric inflammation. IL18 genotype might be a marker for predicting the effects of eradication therapy.

Clarithromycin resistance, tumor necrosis factor alpha gene polymorphism and mucosal inflammation affect H. pylori eradication success

Several bacterial and host-related factors concur in causing Helicobacter pylori eradication failure. We ascertained the role of bacterial virulence genes (cagA, vacA), clarithromycin resistance [Cla(R), 23S ribosomal RNA (rRNA) mutations], host polymorphism of CYP2C19 (polyphosphoinositide, PPI, metabolism) and of the cytokines IL-1B-31C>T, IL-1RN VNTR, IFN-gamma+874A>T, TNF-alpha-1031T>C, TNF-alpha-857C>T, TNF-alpha-376G>A, TNF-alpha-308G>A, TNF-alpha-238G>A, IL-10-1082A>G, IL-10-819C>T, IL-10-592C>A, IL-12A+6686G>A, IL-12B+15485A>C. Two groups of H. pylori-infected and H. pylori-treated patients were retrospectively identified: 45 not eradicated and 57 eradicated. Treatment failure was significantly correlated with Cla(R) (all resistant strains in non-eradicated patients); with TNF-alpha-238, IL10-819, IL10-592, IL-12B+15485 single nucleotide polymorphism (SNP); with IL10 ATA/ATA haplotype; and with antral inflammatory grade. On considering Cla(S)-infected patients only, logistic regression analysis (eradication = dependent; TNF-alpha-238, IL12B + 15485 genotypes, IL10 ATA/ATA as present or absent, antral gastritis grade = covariates) confirmed as significantly correlated with eradication antral gastritis grade only (Exp(B) = 6.48; 95% CI, 1.2-35.01). In conclusion, the bacterial determinant causing triple therapy failure is clarithromycin resistant, being virulence genes not involved. The host related factors that favor eradication are those linked to inflammation: a higher inflammatory infiltrate in the mucosa, possibly favored by genotypes able to down regulate the anti-inflammatory cytokine response, enhance the chance of eradication success.

Specific T cell responses to Helicobacter pylori predict successful eradication therapy

OBJECTIVE

The aim of our prospective study was to test a specific T cell response to Helicobacter pylori before therapy and compare it to the success of H. pylori eradication 12 months later.

METHODS

A total of 14 dyspeptic patients and 10 patients with previous H. pylori eradication failure were recruited into the study; before therapy their gastric samples for H. pylori cultivation and blood samples for dendritic cell cultivation were obtained. H. pylori antigens were produced to prime dendritic cells for stimulation of T lymphocyte response.

RESULTS

The level of cytokine response by T cells was measured and results were compared with the success of H. pylori eradication one year later. There was a significantly increased response in expression of IFN-gamma and IL-4 molecules by DCs stimulated T cells in subjects that successfully eradicated H. pylori compared with those who failed to eradicate the infection. Our results support the hypothesis that successful H. pylori eradication requires established anti-H. pylori immune response besides antibiotic treatment.

CONCLUSION

Effective IFN-gamma cytokine response to H. pylori antigens seems to be of particular importance. Immunisation could be therefore beneficial for H. pylori eradication, while immunodeficiency could cause the failure in H. pylori eradication.

Third-line rescue therapy for Helicobacter pylori infection

H pylori gastric infection is one of the most prevalent infectious diseases worldwide. The discovery that most upper gastrointestinal diseases are related to H pylori infection and therefore can be treated with antibiotics is an important medical advance. Currently, a first-line triple therapy based on proton pump inhibitor (PPI) or ranitidine bismuth citrate (RBC) plus two antibiotics (clarithromycin and amo-xicillin or nitroimidazole) is recommended by all consensus conferences and guidelines. Even with the correct use of this drug combination, infection can not be eradicated in up to 23% of patients. Therefore, several second line therapies have been recommended. A 7 d quadruple therapy based on PPI, bismuth, tetracycline and metronidazole is the more frequently accepted. However, with second-line therapy, bacterial eradication may fail in up to 40% of cases. When H pylori eradication is strictly indicated the choice of further treatment is controversial. Currently, a standard third-line therapy is lacking and various protocols have been proposed. Even after two consecutive failures, the most recent literature data have demonstrated that H pylori eradication can be achieved in almost all patients, even when antibiotic susceptibility is not tested. Different possibilities of empirical treatment exist and the available third-line strategies are herein reviewed.

Selective reduction of anti-Helicobacter pylori IgG subclass antibody in gastric carcinoma

BACKGROUND

Epidemiological studies have demonstrated strong links between Helicobacter pylori infection and gastric adenocarcinoma. Recent studies suggest that cell-mediated immunity influences the outcome of infection, including the development of gastric adenocarcinoma. The T-cell response can be characterized in terms of the secreted cytokine profile, which in turn influences the B-cell response including the balance of IgG subclass antibody.

METHODS

Serum anti-H. pylori IgG, IgG1 and IgG2 antibodies were studied by ELISA in subjects with benign gastric diseases, gastric dysplasia and gastric adenocarcinoma.

RESULTS

The distribution patterns of IgG subclass anti-H. pylori antibody varies significantly between H. pylori-linked benign and malignant disease in subjects infected with H. pylori. Significantly lower IgG2 levels were found in subjects with gastric adenocarcinoma compared with those with reflux esophagitis, chronic gastritis, gastric ulcer, and peptic ulcer, while IgG1 antibody remained at similar levels in both benign and malignant disease. A limited study of seropositive subjects with premalignant change was consistent with the fall in IgG2 antibody pre-dating malignant change, although pre-eradication results are needed to validate these data.

CONCLUSIONS

These studies indicate that subjects with low levels of IgG2 anti-H. pylori antibody are at risk of gastric adenocarcinoma, and that the previously described linkage between gastric adenocarcinoma and low total IgG antibody does not simply reflect reduced gastric colonization. The diagnostic value of this assay for pre-endoscopy screening is attractive.

Role of chronic infection and inflammation in the gastrointestinal tract in the etiology and pathogenesis of idiopathic parkinsonism. Part 2: response of facets of clinical idiopathic parkinsonism to Helicobacter pylori eradication. A randomized, double-blind, placebo-controlled efficacy study

BACKGROUND

Links between etiology/pathogenesis of neuropsychiatric disease and infection are increasingly recognized.

AIM

Proof-of-principle that infection contributes to idiopathic parkinsonism.

METHODS

Randomized, double-blind, placebo-controlled efficacy study of proven Helicobacter pylori eradication on the time course of facets of parkinsonism. Intervention was 1 week's triple eradication therapy/placebos. Routine deblinding at 1 year (those still infected received open-active), with follow-up to 5 years post-eradication. Primary outcome was mean stride length at free-walking speed, sample size 56 for a difference, active vs. placebo, of 3/4 (between-subject standard deviation). Recruitment of subjects with idiopathic parkinsonism and H. pylori infection was stopped at 31, because of marked deterioration with eradication failure. Interim analysis was made in the 20 who had reached deblinding, seven of whom were receiving antiparkinsonian medication (long-t(1/2), evenly spaced) which remained unchanged.

RESULTS

Improvement in stride-length, on active (n = 9) vs. placebo (11), exceeded size of effect on which the sample size was calculated when analyzed on intention-to-treat basis (p = .02), and on protocol analysis of six weekly assessments, including (p = .02) and excluding (p = .05) those on antiparkinsonian medication. Active eradication (blind or open) failed in 4/20, in whom B-lymphocyte count was lower. Their mean time course was: for stride-length, -243 (95% CI -427, -60) vs. 45 (-10, 100) mm/year in the remainder (p = .001); for the ratio, torque to extend to flex relaxed arm, 349 (146, 718) vs. 58 (27, 96)%/ year (p < .001); and for independently rated, visual-analog scale of stance-walk videos (worst-best per individual identical with 0-100 mm), -64 vs. -3 mm from anterior and -50 vs. 11 lateral (p = .004 and .02).

CONCLUSIONS

Interim analysis points to a direct or surrogate (not necessarily unique) role of a particular infection in the pathogenesis of parkinsonism. With eradication failure, bolus release of antigen from killed bacteria could aggravate an effect of ongoing infection.

Evaluation of anti-Helicobacter pylori IgG2 antibody for the diagnosis of Helicobacter pylori infection in western and Chinese populations

BACKGROUND

The performance of commercial Helicobacter pylori diagnostic kits developed for particular geographic regions has often been found to be of poor diagnostic value when applied to other regions, possibly because of infections being caused by different H. pylori strains in different regions.

AIM

To evaluate the performance of an IgG2 anti-H. pylori enzyme-linked immunoassay test (Helirad Alert) for detection of H. pylori infection in both Australian and Hong Kong (Chinese) subjects.

METHODS

Serum samples were tested for H. pylori specific IgG2 and IgG antibodies by enzyme-linked immunoassay kits using identical antigen preparation in 168 Australian and 160 Hong Kong (Chinese) subjects diagnosed with dyspepsia.

RESULTS

Using a cut-off value determined by analysis of H. pylori-negative Australian samples, the sensitivity, specificity and accuracy of the IgG2 assay were 77.8, 97.4 and 91.1%, respectively, for the Australian samples and 96.3, 83.8 and 90% for Hong Kong samples. For the IgG assay, sensitivity, specificity and accuracy were 87.0, 99.1 and 95.2% for Australian samples and 97.5, 75 and 86.3% for Hong Kong samples respectively. Receiver-operating characteristic analysis showed better discrimination of H. pylori status when the IgG2 assay was applied to Hong Kong samples, while the IgG assay was better in the Australian samples.

CONCLUSION

These data demonstrate that the Helirad Alert enzyme-linked immunoassay could provide a reliable method for screening H. pylori infection in both western and Chinese populations.

Rifabutin- and furazolidone-based Helicobacter pylori eradication therapies after failure of standard first- and second-line eradication attempts in dyspepsia patients

BACKGROUND

Optimal management approach is not well defined for subjects who fail initial first- and second-line Helicobacter pylori eradication attempts and are dealt on a case-by-case basis by the specialists.

AIM

To evaluate the efficacy and safety of standard and 'rescue' eradication therapies at primary and secondary care levels.

METHODS

H. pylori infected dyspepsia patients referred to our C13 urea breath testing laboratory between January 1999 to February 2002 were included. Eradication failure at secondary care level was treated using strategies including antibiotic sensitivity testing and the use of rifabutin- and furazolidone-based therapies.

RESULTS

3280 patients received standard first-line eradication therapy, which was successful in 2530 (77%) patients. Second-line therapy (bismuth-based 'quadruple') or triple therapy (altering constituent antibiotics) was successful in 56% of 270 treated patients. Subsequent eradication attempts using rifabutin-based (n = 34) and furazolidone-based (n = 10) regimens were successful in 38% and 60% patients respectively. H. pylori eradication rates were significantly different for guidelines compliant (94.8%) and non-compliant (82%) groups (P = 0.0001). H. pylori eradication rates for non-ulcer dyspepsia (40%) and peptic ulcer disease (36%) were not significantly different.

CONCLUSIONS

Available H. pylori eradication therapies remain very effective and compliance to guidelines achieves high success rates. Furazolidone-based 'rescue' regimen achieved high eradication rates after failure of the standard first-line, second-line and rifabutin-based therapies.

Update on the immunologic basis of Helicobacter pylori gastritis

PURPOSE OF REVIEW

Helicobacter pylori is a ubiquitous bacterial pathogen that has evolved to chronically infect the gastric mucosal surface, evade host immune clearance, and cause peptic ulcer disease or gastric neoplasia in a significant minority of infected individuals. Understanding the colonization, persistence, and virulence determinants of the bacterium as well as the innate and adaptive immune responses of the host are critically important if we are to develop novel treatment strategies for eradication of infection and prevention of H. pylori-induced gastroduodenal disease.

RECENT FINDINGS

Substantial progress has been made in understanding the role of CagA in altering gastric epithelial cell signaling pathways. Intracellular CagA has been shown to activate the Ras/MEK/ERK mitogen activated protein kinase cascade and to associate with epithelial tight-junction scaffolding protein ZO-1. CagA was shown to regulate cellular responses and possibly contribute to gastritis by phosphorylation-dependent pathways. A phosphorylation-independent mechanism for CagA intracellular effects has also been proposed. The potential for CagA to disrupt the apical junctional barrier and for the outer membrane protein oipA to promote IL-8 secretion and gastric inflammation have also been explored. A number of different mechanisms by which H. pylori escapes and evades host immune attack to cause chronic indolent inflammation have been uncovered. Meanwhile, the examination and development of new adjuvants and vaccine delivery mechanisms to induce mucosal immune responses against key bacterial antigens has been a continuing focus of investigation in both animal and human studies.

SUMMARY

H. pylori induces gastritis through production of a variety of antigens, virulence factors, and soluble mediators. The bacterium also dysregulates, disarms, and evades host immune responses to maintain chronic colonization of the gastric mucosa. Understanding the mechanisms of its growth and survival in the human stomach are essential for the development of an effective vaccine and other novel eradication strategies.

Treatment of Helicobacter gastritis with IL-4 requires somatostatin

Fifty percent of the world's population is infected with Helicobacter pylori; however, treatment has been insufficient to eradicate the organisms due to rising antibiotic resistance. Helicobacter infection is characterized by induction of a T helper 1 lymphocyte (Th1) immune response, hypergastrinemia, and suppressed tissue somatostatin (SOM) levels. However, the mechanism by which the immune response regulates acid secretion is not known. We show here that treatment with IFN-gamma, a Th1 cytokine, was sufficient to induce gastritis, increase gastrin, and decrease SOM levels within 7 days. In contrast, the T helper 2 lymphocyte cytokine IL-4 increased SOM levels and effectively suppressed gastrin expression and secretion. This result demonstrated reciprocal regulation of acid regulatory peptides by immune modulators. IL-4 pretreatment prevented gastritis in infected wild-type but not in SOM null mice. Thus, the ability of IL-4 to oppose a Th1-mediated infection required SOM. Immunofluorescence was used to document the presence of IL-4 receptors on the gastric SOM-secreting cell (D cell). Moreover, IL-4 stimulated SOM release from primary D cell cultures. Treatment of mice chronically infected with Helicobacter felis for 2 mo with the SOM analogue octreotide resolved the inflammation. Thus, a mechanism by which IL-4 resolves inflammation in the stomach is by stimulating the release of SOM from gastric D cells.

Immunobiotics and the probiotic evolution

The term 'probiotic' was coined by the food industry to describe microbes beneficial to health. Scientific criticism based on poorly characterised isolates, soft clinical targets, and an absence of a mechanistic framework limited value of this concept. Current clinical and animal model studies support a role for certain 'probiotics', activating the common mucosal system through the stimulation of gut antigen-presenting cells to both promote protection and to switch regulatory mechanisms. It is concluded that a new term is required to identify bacteria that promote health through driving mucosal immune mechanisms, compared to those with strictly local effects. The term 'immunobiotics' is suggested as appropriate to fulfil this need.

Effect of total secondary carotenoids extracts from Chlorococcum sp on Helicobacter pylori-infected BALB/c mice

Helicobacter pylori is a human pathogen associated with type B gastritis, peptic ulcer disease and gastric cancer. A high intake of carotenoids has been suggested to prevent development of gastric malignancies. Microalgae Chlorococcum sp. could accumulate secondary carotenoids under stress conditions. The aim of the present study was to investigate whether dietary cell extract of Chlorococcum sp. could affect the bacterial load of H. pylori infected BALB/c mice and whether it could induce modulation of cytokine production. BALB/c mice were infected with H. pylori three times at 2-day intervals. Two weeks later, they were orally fed with cell extract of Chlorococcum sp. for the following 2 weeks. Animals were killed at the end of the experiments. Stomachs were removed and paraffin sections were stained for histology examination. Splenocytes were obtained and cultured in vitro with H. pylori sonicate to evaluate induction of interferon gamma (IFN-gamma) and interleukin 4 (IL-4) secretion. Mice treated with carotenoids-rich algal meal showed significantly reduced bacterial load and gastric inflammation. These changes were associated with a shift of the T-lymphocytes response from a predominant T helper type 1 (Th1) response dominated by IFN-gamma to a Th1/Th2 response with IFN-gamma and IL-4.

Review article: the treatment of refractory Helicobacter pylori infection

The occurrence of refractory Helicobacter pylori infection is increasing. When the bacteria are not eradicated it means that the antibiotics have not reached the gastric mucosa at a sufficient concentration and over a sufficient time lapse to kill them. The main reasons for this are poor patient compliance, resistant bacteria, low gastric pH and a high bacterial load. Therefore, when administering a new treatment, it is important to choose antibiotics which do not face resistance problems and which increase the dosage of antisecretory drugs and the duration of treatment and, if possible, to add a topical agent such as bismuth salt. The recommended empirical strategy is to prescribe quadruple therapy or, alternatively, 2-week triple therapy including amoxicillin-metronidazole, tetracycline-metronidazole or amoxicillin-rifabutin. However, when H. pylori is susceptible, clarithromycin can still be used. In the case of a high level of metronidazole resistance, furazolidone can be employed. In each case, it is important to ensure good patient compliance, and counselling is helpful in this regard. However, the best approach remains the prevention of refractory H. pylori infection and, for this purpose, antimicrobial susceptibility testing before first-line therapy is important and should be encouraged.

Helicobacter pylori- inflammation, immunity and vaccines

The mechanisms by which Helicobacter pylori escape the host immune response remains an important topic. Regulatory T cells appear to play a role in the persistence of the infection and the control of tissue damage. In the thought that the host genetic background influences the cross-talk between pathogens and hosts, the impact of cytokine polymorphisms on the outcome of H. pylori has been further delineated in the review period. On the other hand, several additional genes of H. pylori have been shown to participate in the pro-inflammatory cytokine and chemokine response to the infection. Finally, progress has been achieved in vaccine development, with new vaccine delivery systems and routes of immunization tested in animal models and human volunteers.

Treatment of Helicobacter pylori infection

Review of the recently published data on Helicobacter pylori management highlights various interesting aspects. Current H. pylori eradication guidelines generally suggest a noninvasive 'test and treat' strategy for all dyspeptic patients with certain age limits depending on the local gastric neoplasia risk. According to the 'Maastricht 2-2000 Consensus Report' treatment should be thought of as a 'package' considering first- and second-line eradication therapies together. Various centres have published their results using novel antimicrobial formulations and 'rescue' and 'sequential' therapies. Review suggests that care at the specialist level remains a challenge and guidelines are deficient particularly as regards the selection and duration of eradication therapies. Results indicate that differences for CYP2C19 genotype and the selection of proton pump inhibitors have no significant role in determining eradication rates whereas antibiotic resistance and socio-economic factors play a variable role according to different geographical areas. Compliance remains an important factor in determining clinical outcome at the primary and secondary levels worldwide.