Indications of Helicobacter pylori Eradication Treatment and Its Influence on Prescriptions and Effectiveness (Hp-EuReg).

BACKGROUND: The influence of indications for Helicobacter pylori investigation on prescriptions and effectiveness is unknown. The aim of the study was to assess the impact of indications for H. pylori investigation on prescriptions, effectiveness, compliance, and tolerance. METHODS: International, prospective, non-interventional registry of the management of H. pylori infection by European gastroenterologists (Hp-EuReg). Treatment-näive patients registered from 2013 to 2023 at e-CRF AEG-REDCap were analyzed. The effectiveness was assessed by modified intention-to-treat analysis. RESULTS: Overall, 53,636 treatment-naïve cases from 34 countries were included. Most frequent indications were: dyspepsia with normal endoscopy (49%), non-investigated dyspepsia (20%), duodenal ulcer (11%), gastric ulcer (7.7%), and gastroesophageal reflux disease (GERD) (2.6%). Therapy effectiveness varied by indication: duodenal ulcer (91%), gastric ulcer (90%), preneoplastic lesions (90%), dyspepsia with normal endoscopy (89%), GERD (88%), and non-investigated dyspepsia (87%). Bismuth-metronidazole-tetracycline and clarithromycin-amoxicillin-bismuth quadruple therapies achieved 90% effectiveness in all indications except GERD. Concomitant clarithromycin-amoxicillin-tinidazole/metronidazole reached 90% cure rates except in patients with non-investigated dyspepsia; whereas sequential clarithromycin-amoxicillin-tinidazole/metronidazole proved optimal (≥90%) in patients with gastric ulcer only. Adverse events were higher in patients treated for dyspepsia with normal endoscopy and duodenal ulcer compared with the remaining indications (23% and 28%, p < 0.001). Therapeutic compliance was higher in patients with duodenal ulcer and preneoplastic lesions (98% and 99%, p < 0.001). CONCLUSION: In Europe, patients with gastric or duodenal ulcers and preneoplastic lesions showed higher H. pylori treatment effectiveness. Bismuth and non-bismuth quadruple therapies achieved optimal results in almost all indications. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02328131.

Helicobacter pylori resistance to current therapies.

PURPOSE OF REVIEW: Helicobacter pylori eradication rates have fallen in recent years, mainly because of the emergence of antibiotic-resistant infections. Indeed the WHO has recently designated clarithromycin-resistant H. pylori infection a high priority for antibiotic resistance research and development. This review aims to discuss the most up-to-date information on the methods to detect H. pylori antibiotic resistance, the recent data on resistance rates, and the most appropriate treatment strategies to overcome antibiotic resistance. RECENT FINDINGS: There has been active research into the development and assessment of genotypic diagnostic assays for both the invasive and noninvasive detection of antibiotic-resistant infection. There are regional variations in the prevalence of H. pylori antibiotic resistance. Primary resistance rates in general are on the rise and high rates of clarithromycin resistance (>15%) have been reported in many parts of the world. SUMMARY: Optimizing antimicrobial susceptibility testing by both invasive and noninvasive means is crucial to accurately evaluate resistance rates for the optimization of both regional and personalized H. pylori treatment strategies.

RBP-J-Regulated miR-182 Promotes TNF-α-Induced Osteoclastogenesis.

Increased osteoclastogenesis is responsible for osteolysis, which is a severe consequence of inflammatory diseases associated with bone destruction, such as rheumatoid arthritis and periodontitis. The mechanisms that limit osteoclastogenesis under inflammatory conditions are largely unknown. We previously identified transcription factor RBP-J as a key negative regulator that restrains TNF-α-induced osteoclastogenesis and inflammatory bone resorption. In this study, we tested whether RBP-J suppresses inflammatory osteoclastogenesis by regulating the expression of microRNAs (miRNAs) important for this process. Using high-throughput sequencing of miRNAs, we obtained the first, to our knowledge, genome-wide profile of miRNA expression induced by TNF-α in mouse bone marrow-derived macrophages/osteoclast precursors during inflammatory osteoclastogenesis. Furthermore, we identified miR-182 as a novel miRNA that promotes inflammatory osteoclastogenesis driven by TNF-α and whose expression is suppressed by RBP-J. Downregulation of miR-182 dramatically suppressed the enhanced osteoclastogenesis program induced by TNF-α in RBP-J-deficient cells. Complementary loss- and gain-of-function approaches showed that miR-182 is a positive regulator of osteoclastogenic transcription factors NFATc1 and B lymphocyte-induced maturation protein-1. Moreover, we identified that direct miR-182 targets, Foxo3 and Maml1, play important inhibitory roles in TNF-α-mediated osteoclastogenesis. Thus, RBP-J-regulated miR-182 promotes TNF-α-induced osteoclastogenesis via inhibition of Foxo3 and Maml1. Suppression of miR-182 by RBP-J serves as an important mechanism that restrains TNF-α-induced osteoclastogenesis. Our results provide a novel miRNA-mediated mechanism by which RBP-J inhibits osteoclastogenesis and suggest that targeting of the newly described RBP-J-miR-182-Foxo3/Maml1 axis may represent an effective therapeutic approach to suppress inflammatory osteoclastogenesis and bone resorption.

LFA-1/ICAM-1 Ligation in Human T Cells Promotes Th1 Polarization through a GSK3ß Signaling-Dependent Notch Pathway.

In this study, we report that the integrin LFA-1 cross-linking with its ligand ICAM-1 in human PBMCs or CD4(+) T cells promotes Th1 polarization by upregulating IFN-γ secretion and T-bet expression. LFA-1 stimulation in PBMCs, CD4(+) T cells, or the T cell line HuT78 activates the Notch pathway by nuclear translocation of cleaved Notch1 intracellular domain (NICD) and upregulation of target molecules Hey1 and Hes1. Blocking LFA-1 by a neutralizing Ab or specific inhibition of Notch1 by a γ-secretase inhibitor substantially inhibits LFA-1/ICAM-1-mediated activation of Notch signaling. We further demonstrate that the Notch pathway activation is dependent on LFA-1/ICAM-1-induced inactivation of glycogen synthase kinase 3ß (GSK3ß), which is mediated via Akt and ERK. Furthermore, in silico analysis in combination with coimmunoprecipitation assays show an interaction between NICD and GSK3ß. Thus, there exists a molecular cross-talk between LFA-1 and Notch1 through the Akt/ERK-GSK3ß signaling axis that ultimately enhances T cell differentiation toward Th1. Although clinical use of LFA-1 antagonists is limited by toxicity related to immunosuppression, these findings support the concept that Notch inhibitors could be attractive for prevention or treatment of Th1-related immunologic disorders and have implications at the level of local inflammatory responses.

Differential modulation of Helicobacter pylori lipopolysaccharide-mediated TLR2 signaling by individual Pellino proteins.

BACKGROUND: Eradication rates for current H. pylori therapies have fallen in recent years, in line with the emergence of antibiotic resistant infections. The development of therapeutic alternatives to antibiotics, such as immunomodulatory therapy and vaccines, requires a more lucid understanding of host-pathogen interactions, including the relationships between the organism and the innate immune response. Pellino proteins are emerging as key regulators of immune signaling, including the Toll-like receptor pathways known to be regulated by H. pylori. The aim of this study was to characterize the role of Pellino proteins in the innate immune response to H. pylori lipopolysaccharide. MATERIALS AND METHODS: Gain-of-function and loss-of-function approaches were utilized to elucidate the role of individual Pellino proteins in the Toll-like receptor 2-mediated response to H. pylori LPS by monitoring NF-ĸB activation and the induction of proinflammatory chemokines. Expression of Pellino family members was investigated in gastric epithelial cells and gastric tissue biopsy material. RESULTS: Pellino1 and Pellino2 positively regulated Toll-like receptor 2-driven responses to H. pylori LPS, whereas Pellino3 exerted a negative modulatory role. Expression of Pellino1 was significantly higher than Pellino3 in gastric epithelial cells and gastric tissue. Furthermore, Pellino1 expression was further augmented in gastric epithelial cells in response to infection with H. pylori or stimulation with H. pylori LPS. CONCLUSIONS: The combination of low Pellino3 levels together with high and inducible Pellino1 expression may be an important determinant of the degree of inflammation triggered upon Toll-like receptor 2 engagement by H. pylori and/or its components, contributing to H. pylori-associated pathogenesis by directing the incoming signal toward an NF-kB-mediated proinflammatory response.

Repression of the proapoptotic cellular BIK/NBK gene by Epstein-Barr virus antagonizes transforming growth factor ß1-induced B-cell apoptosis.

UNLABELLED: The Epstein-Barr virus (EBV) establishes a lifelong latent infection in humans. EBV infection of primary B cells causes cell activation and proliferation, a process driven by the viral latency III gene expression program, which includes EBV nuclear proteins (EBNAs), latent membrane proteins, and untranslated RNAs, including microRNAs. Some latently infected cells enter the long-lived memory B-cell compartment and express only EBNA1 transiently (Lat I) or no EBV protein at all (Lat 0). Targeting the molecular machinery that controls B-cell fate decisions, including the Bcl-2 family of apoptosis-regulating proteins, is crucial to the EBV cycle of infection. Here, we show that BIK (also known as NBK), which encodes a proapoptotic "sensitizer" protein, is repressed by the EBNA2-driven Lat III program but not the Lat I program. BIK repression occurred soon after infection of primary B cells by EBV but not by a recombinant EBV in which the EBNA2 gene had been knocked out. Ectopic BIK induced apoptosis in Lat III cells by a mechanism dependent on its BH3 domain and the activation of caspases. We show that EBNA2 represses BIK in EBV-negative B-cell lymphoma-derived cell lines and that this host-virus interaction can inhibit the proapoptotic effect of transforming growth factor ß1 (TGF-ß1), a key physiological mediator of B-cell homeostasis. Reduced levels of TGF-ß1-associated regulatory SMAD proteins were bound to the BIK promoter in response to EBV Lat III or ectopic EBNA2. These data are evidence of an additional mechanism used by EBV to promote B-cell survival, namely, the transcriptional repression of the BH3-only sensitizer BIK. IMPORTANCE: Over 90% of adult humans are infected with the Epstein-Barr virus (EBV). EBV establishes a lifelong silent infection, with its DNA residing in small numbers of blood B cells that are a reservoir from which low-level virus reactivation and shedding in saliva intermittently occur. Importantly, EBV DNA is found in some B-cell-derived tumors in which viral genes play a key role in tumor cell emergence and progression. Here, we report for the first time that EBV can shut off a B-cell gene called BIK. When activated by a molecular signal called transforming growth factor ß1 (TGF-ß1), BIK plays an important role in killing unwanted B cells, including those infected by viruses. We describe the key EBV-B-cell molecular interactions that lead to BIK shutoff. These findings further our knowledge of how EBV prevents the death of its host cell during infection. They are also relevant to certain posttransplant lymphomas where unregulated cell growth is caused by EBV genes.

The second Irish Helicobacter pylori Working Group consensus for the diagnosis and treatment of Helicobacter pylori infection in adult patients in Ireland.

BACKGROUND: There has been an increase in resistance to many of the antimicrobials used to treat Helicobacter pylori ( H. pylori ) nationally and internationally. Primary clarithromycin resistance and dual clarithromycin and metronidazole resistance are high in Ireland. These trends call for an evaluation of best-practice management strategies. OBJECTIVE: The objective of this study was to revise the recommendations for the management of H. pylori infection in adult patients in the Irish healthcare setting. METHODS: The Irish H. pylori working group (IHPWG) was established in 2016 and reconvened in 2023 to evaluate the most up-to-date literature on H. pylori diagnosis, eradication rates and antimicrobial resistance. The 'GRADE' approach was then used to rate the quality of available evidence and grade the resulting recommendations. RESULTS: The Irish H. pylori working group agreed on 14 consensus statements. Key recommendations include (1) routine antimicrobial susceptibility testing to guide therapy is no longer recommended other than for clarithromycin susceptibility testing for first-line treatment (statements 6 and 9), (2) clarithromycin triple therapy should only be prescribed as first-line therapy in cases where clarithromycin susceptibility has been confirmed (statement 9), (3) bismuth quadruple therapy (proton pump inhibitor, bismuth, metronidazole, tetracycline) is the recommended first-line therapy if clarithromycin resistance is unknown or confirmed (statement 10), (4) bismuth quadruple therapy with a proton pump inhibitor, levofloxacin and amoxicillin is the recommended second-line treatment (statement 11) and (5) rifabutin amoxicillin triple therapy is the recommend rescue therapy (statement 12). CONCLUSION: These recommendations are intended to provide the most relevant current best-practice guidelines for the management of H. pylori infection in adults in Ireland.

Role of compliance in Helicobacter pylori eradication treatment: Results of the European Registry on H. pylori management.

BACKGROUND: Adherence to Helicobacter pylori (H. pylori) eradication treatment is a cornerstone for achieving adequate treatment efficacy. OBJECTIVE: To determine which factors influence compliance with treatment. METHODS: A systematic prospective non-interventional registry (Hp-EuReg) of the clinical practice of European gastroenterologists. Compliance was considered adequate if ≥90% drug intake. Data were collected until September 2021 using the AEG-REDCap e-CRF and were subjected to quality control. Modified intention-to-treat analyses were performed. Multivariate analysis carried out the factors associated with the effectiveness of treatment and compliance. RESULTS: Compliance was inadequate in 646 (1.7%) of 38,698 patients. The non-compliance rate was higher in patients prescribed longer regimens (10-, 14-days) and rescue treatments, patients with uninvestigated dyspepsia/functional dyspepsia, and patients reporting adverse effects. Prevalence of non-adherence was lower for first-line treatment than for rescue treatment (1.5% vs. 2.2%; p < 0.001). Differences in non-adherence in the three most frequent first-line treatments were shown: 1.1% with proton pump inhibitor + clarithromycin + amoxicillin; 2.3% with proton pump inhibitor clarithromycin amoxicillin metronidazole; and 1.8% with bismuth quadruple therapy. These treatments were significantly more effective in compliant than in non-compliant patients: 86% versus 44%, 90% versus 71%, and 93% versus 64%, respectively (p < 0.001). In the multivariate analysis, the variable most significantly associated with higher effectiveness was adequate compliance (odds ratio, 6.3 [95%CI, 5.2-7.7]; p < 0.001). CONCLUSIONS: Compliance with Helicobacter pylori eradication treatment is very good. Factors associated with poor compliance include uninvestigated/functional dyspepsia, rescue-treatment, prolonged treatment regimens, the presence of adverse events, and the use of non-bismuth sequential and concomitant treatment. Adequate treatment compliance was the variable most closely associated with successful eradication.

A role for TLR4 in Clostridium difficile infection and the recognition of surface layer proteins.

Clostridium difficile is the etiological agent of antibiotic-associated diarrhoea (AAD) and pseudomembranous colitis in humans. The role of the surface layer proteins (SLPs) in this disease has not yet been fully explored. The aim of this study was to investigate a role for SLPs in the recognition of C. difficile and the subsequent activation of the immune system. Bone marrow derived dendritic cells (DCs) exposed to SLPs were assessed for production of inflammatory cytokines, expression of cell surface markers and their ability to generate T helper (Th) cell responses. DCs isolated from C3H/HeN and C3H/HeJ mice were used in order to examine whether SLPs are recognised by TLR4. The role of TLR4 in infection was examined in TLR4-deficient mice. SLPs induced maturation of DCs characterised by production of IL-12, TNFα and IL-10 and expression of MHC class II, CD40, CD80 and CD86. Furthermore, SLP-activated DCs generated Th cells producing IFNγ and IL-17. SLPs were unable to activate DCs isolated from TLR4-mutant C3H/HeJ mice and failed to induce a subsequent Th cell response. TLR4⁻/⁻ and Myd88⁻/⁻, but not TRIF⁻/⁻ mice were more susceptible than wild-type mice to C. difficile infection. Furthermore, SLPs activated NFκB, but not IRF3, downstream of TLR4. Our results indicate that SLPs isolated from C. difficile can activate innate and adaptive immunity and that these effects are mediated by TLR4, with TLR4 having a functional role in experimental C. difficile infection. This suggests an important role for SLPs in the recognition of C. difficile by the immune system.

Tribbles 3: a novel regulator of TLR2-mediated signaling in response to Helicobacter pylori lipopolysaccharide.

Helicobacter pylori causes chronic gastritis, peptic ulcers, and gastric carcinoma. Gastric epithelial cells provide the first point of contact between H. pylori and the host. TLRs present on these cells recognize various microbial products, resulting in the initiation of innate immunity. Although previous reports investigated TLR signaling in response to intact H. pylori, the specific contribution of H. pylori LPS with regard to functional genomics and cell-signaling events has not been defined. This study set out to define downstream signaling components and altered gene expression triggered by H. pylori LPS and to investigate the role of the signaling protein tribbles 3 (TRIB3) during the TLR-mediated response to H. pylori LPS. Cotransfections using small interfering RNA and dominant-negative constructs demonstrated that H. pylori LPS functions as a classic TLR2 ligand by signaling through pathways involving the key TLR signaling components MyD88 adaptor-like, MyD88, IRAK1, IRAK4, TNFR-associated factor 6, IκB kinase ß, and IκBα. Microarray analysis, real-time PCR, and ELISA revealed the induction of a discrete pattern of chemokines as a direct effect of LPS:TLR2 signaling. H. pylori infection was associated with decreased expression of TRIB3 in human gastric epithelial cell lines and tissue samples. Additionally, H. pylori decreased expression of C/EBP homologous protein and activating transcription factor 4, the transcription factors involved in the induction of TRIB3 expression. Furthermore, knockdown of TRIB3 and C/EBP homologous protein enhanced TLR2-mediated NF-κB activation and chemokine induction in response to H. pylori LPS. Thus, modulation of TRIB3 by H. pylori and/or its products may be an important mechanism during H. pylori-associated pathogenesis.

Analysis of Clinical Phenotypes through Machine Learning of First-Line H. pylori Treatment in Europe during the Period 2013-2022: Data from the European Registry on H. pylori Management (Hp-EuReg).

The segmentation of patients into homogeneous groups could help to improve eradication therapy effectiveness. Our aim was to determine the most important treatment strategies used in Europe, to evaluate first-line treatment effectiveness according to year and country. Data collection: All first-line empirical treatments registered at AEGREDCap in the European Registry on Helicobacter pylori management (Hp-EuReg) from June 2013 to November 2022. A Boruta method determined the "most important" variables related to treatment effectiveness. Data clustering was performed through multi-correspondence analysis of the resulting six most important variables for every year in the 2013-2022 period. Based on 35,852 patients, the average overall treatment effectiveness increased from 87% in 2013 to 93% in 2022. The lowest effectiveness (80%) was obtained in 2016 in cluster #3 encompassing Slovenia, Lithuania, Latvia, and Russia, treated with 7-day triple therapy with amoxicillin-clarithromycin (92% of cases). The highest effectiveness (95%) was achieved in 2022, mostly in Spain (81%), with the bismuth-quadruple therapy, including the single-capsule (64%) and the concomitant treatment with clarithromycin-amoxicillin-metronidazole/tinidazole (34%) with 10 (69%) and 14 (32%) days. Cluster analysis allowed for the identification of patients in homogeneous treatment groups assessing the effectiveness of different first-line treatments depending on therapy scheme, adherence, country, and prescription year.

Comparison of the management of Helicobacter pylori infection between the older and younger European populations.

The prevalence of Helicobacter pylori remains high in the older population. Specific age-related peculiarities may impact the outcomes of H. pylori treatment. The aim of the study was to evaluate the diagnostics and effectiveness of H. pylori eradication between the younger and older European populations. "European Registry on H. pylori Management (Hp-EuReg)" data from 2013 to 2022 were analyzed. Patients were divided into older (≥ 60 years) and younger (18-59 years) groups. Modified intention-to-treat (mITT) and per-protocol (PP) analysis was performed. 49,461 patients included of which 14,467 (29%) were older-aged. Concomitant medications and penicillin allergy were more frequent among the older patients. Differences between younger and older populations were observed in treatment duration in first-line treatment and in proton pump inhibitors (PPIs) doses in second-line treatment. The overall incidence of adverse events was lower in the older adults group. The overall first-line treatment mITT effectiveness was 88% in younger and 90% in the older patients (p < 0.05). The overall second-line mITT treatment effectiveness was 84% in both groups. The effectiveness of the most frequent first- and second-line triple therapies was suboptimal (< 90%) in both groups. Optimal efficacy (≥ 90%) was achieved by using bismuth and non-bismuth-based quadruple therapies. In conclusion, the approach to the diagnostics and treatment of H. pylori infection did not generally differ between younger and older patients. Main differences were reported in the concurrent medications, allergy to penicillin and adverse events both in first- and second-line treatment. Optimal effectiveness rates were mostly achieved by using bismuth and non-bismuth-based quadruple therapies. No clinically relevant differences in the effectiveness between the age groups were observed.

Combined antrum and corpus biopsy protocol improves Helicobacter pylori culture success.

BACKGROUND: Helicobacter pylori (H. pylori) causes chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. Eradication rates have fallen, mainly due to antimicrobial resistance. Consensus guidelines recommend that first-line treatment is based on the local prevalence of antimicrobial resistance and that rescue therapies are guided by antimicrobial susceptibility testing (AST). However, H. pylori culture is challenging and culture-based AST is not routinely performed in the majority of hospitals. Optimisation of H. pylori culture from clinical specimens will enable more widespread AST to determine the most appropriate antimicrobials for H. pylori eradication. AIM: To determine whether dual antrum and corpus biopsy sampling is superior to single antrum biopsy sampling for H. pylori culture. METHODS: The study received ethical approval from the joint research ethics committee of Tallaght University Hospital and St. James's Hospital. Patients referred for upper gastrointestinal endoscopy were invited to participate. Biopsies were collected in tubes containing Dent's transport medium and patient demographics were recorded. Biopsies were used to inoculate Colombia blood agar plates. Plates were incubated under microaerobic conditions and evaluated for the presence of H. pylori. Statistical analyses were performed using Graphpad PRISM. Continuous variables were compared using the two-tailed independent t-test. Categorical variables were compared using the two-tailed Fisher exact test. In all cases, a P value less than 0.05 was considered significant. RESULTS: In all, samples from 219 H. pylori-infected patients were analysed in the study. The mean age of recruited patients was 48 ± 14.9 years and 50.7% (n = 111) were male. The most common endoscopic finding was gastritis (58.9%; n = 129). Gastric ulcer was diagnosed in 4.6% (n = 10) of patients, while duodenal ulcer was diagnosed in 2.7% (n = 6). Single antrum biopsies were collected from 73 patients, whereas combined antrum and corpus biopsies were collected from 146 patients. There was no significant difference in age, sex or endoscopic findings between the two groups. H. pylori was successfully cultured in a significantly higher number of cases when combined antrum and corpus biopsies were used compared to a single antrum biopsy [64.4% (n = 94/146) vs 49.3% (36/73); P = 0.04)]. CONCLUSION: Combined corpus and antrum biopsy sampling improves H. pylori culture success compared to single antrum biopsy sampling.

Bfl-1 is a crucial pro-survival nuclear factor-κB target gene in Hodgkin/Reed-Sternberg cells.

Hodgkin/Reed-Sternberg (H/RS) cells are believed to represent clonal progeny of Germinal Centre B cells that have escaped negative selection by evading apoptosis. Aberrant constitutive activity of the transcription factor NF-κB plays a key role in the pathogenesis of Hodgkin's Lymphoma (HL), conferring a survival advantage on H/RS cells. Bfl-1 is a pro-survival NF-κB target gene from the Bcl-2 family of apoptosis-regulating proteins. Here, we report that bfl-1 (also known as A1 or GRS) is frequently expressed in primary H/RS cells from HL tumor biopsies and that elevated bfl-1 expression is a feature of H/RS derived cell lines. We show that bfl-1 is an NF-κB target gene in this cell context and that this regulation is effected through a p65-binding DNA element located in its promoter. We demonstrate that ectopic Bfl-1 can rescue cultured H/RS cells from apoptosis induced by pharmacological inhibitors of NF-κB, and that knockdown of bfl-1 potentiates the pro-apoptotic effect of these agents. These findings are the first indication that Bfl-1 plays a crucial role in setting the elevated threshold of resistance of this malignant cell type to apoptosis.

An Overview of Helicobacter pylori Infection.

Helicobacter pylori (H. pylori) represents one of the most widespread bacterial infections globally. Infection causes chronic gastritis and increases the risk of peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. The pioneering discovery of H. pylori by Marshall and Warren in the early 1980s has initiated fervent research into H. pylori as a pathogen ever since. This chapter aims to provide an overview of our understanding of H. pylori infection and its management, with a focus on current options for diagnosis, the challenges associated with H. pylori eradication, and the need for alternative therapeutic strategies based on furthering our understanding of host: H. pylori interactions.

Molecular Detection of Antibiotic-Resistant Helicobacter pylori.

Antimicrobial susceptibility testing (AST) for H. pylori is essential to accurately assess the prevalence of antibiotic resistance in each population. Antibiotic resistance rates form the basis of local guidelines for H. pylori treatment and AST may also be used as a personalized medicine approach to tailor therapy. This chapter provides an update on global antibiotic resistance rates and describes molecular mechanisms that confer H. pylori antibiotic resistance. An overview on the advantages and limitations of molecular AST using both invasive and noninvasive approaches is also provided.

Helicobacter pylori Virulence Factor Genotyping.

Helicobacter pylori (H. pylori) infection causes chronic gastritis, peptic ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. Bacterial, host, and environmental factors influence the progression of disease from superficial gastritis to cancer. H. pylori is genetically diverse, and expression of its specific virulence factors has been linked to increased risk of more severe pathologies. Described in this chapter is a protocol for detecting important H. pylori virulence factors by firstly extracting DNA from culture material or stomach tissue biopsies, followed by PCR amplification and agarose gel electrophoresis.

Three paralogous clusters of the miR-17~92 family of microRNAs restrain IL-12-mediated immune defense.

MicroRNAs (miRNAs) have been widely implicated in immune regulation, but evidence for the coordinated function of paralogous miRNA clusters remains scarce. Here, by using genetically modified mice with individual or combined cluster deficiencies, we found that three paralogous clusters of the miR-17~92 family of miRNAs collectively suppressed IL-12 production in macrophages. Accordingly, miR-17~92 family miRNAs deficiencies resulted in heightened production of IL-12 and thus enhanced the host defense against intracellular pathogen Listeria monocytogenes in vivo. Mechanistically, different members of the miR-17~92 family of miRNAs acted on a common target, PTEN, to inhibit IL-12 expression by modulating the PI3K-Akt-GSK3 pathway. In addition, the expression of miR-17~92 family miRNAs was collectively inhibited by the transcription factor RBP-J, and RBP-J-associated macrophage functional defects were genetically rescued by deleting three clusters of miR-17~92 family miRNAs on a RBP-J null background. Thus, our results illustrated key roles of three clusters of miR-17~92 family miRNAs in cooperatively controlling IL-12-mediated immune responses and identified miR-17~92 family miRNAs as functional targets of RBP-J in macrophages.

Purification of Total RNA from Stomach Tissue Biopsies.

In order to further our understanding of the physiological consequences of Helicobacter pylori infection , analysis of clinical tissue specimens is required. To this end, RNA is frequently isolated from stomach biopsies of H. pylori-infected patients and compared to samples from uninfected controls to monitor gene expression using molecular methods such as reverse-transcription real-time PCR, microarrays, and next-generation sequencing. The successful purification of sufficient quantities of high-quality RNA is essential for accurate and reproducible downstream analysis. This chapter describes the key steps for high-quality RNA purification from human tissue samples, including sample collection and storage, tissue disruption and lysis, RNA purification, and assessment of RNA yield and quality.