Severity of gastric intestinal metaplasia predicts the risk of gastric cancer: a prospective multicentre cohort study (GCEP).

OBJECTIVE: To investigate the incidence of gastric cancer (GC) attributed to gastric intestinal metaplasia (IM), and validate the Operative Link on Gastric Intestinal Metaplasia (OLGIM) for targeted endoscopic surveillance in regions with low-intermediate incidence of GC. METHODS: A prospective, longitudinal and multicentre study was carried out in Singapore. The study participants comprised 2980 patients undergoing screening gastroscopy with standardised gastric mucosal sampling, from January 2004 and December 2010, with scheduled surveillance endoscopies at year 3 and 5. Participants were also matched against the National Registry of Diseases Office for missed diagnoses of early gastric neoplasia (EGN). RESULTS: There were 21 participants diagnosed with EGN. IM was a significant risk factor for EGN (adjusted-HR 5.36; 95% CI 1.51 to 19.0; p<0.01). The age-adjusted EGN incidence rates for patients with and without IM were 133.9 and 12.5 per 100 000 person-years. Participants with OLGIM stages III-IV were at greatest risk (adjusted-HR 20.7; 95% CI 5.04 to 85.6; p<0.01). More than half of the EGNs (n=4/7) attributed to baseline OLGIM III-IV developed within 2 years (range: 12.7-44.8 months). Serum trefoil factor 3 distinguishes (Area Under the Receiver Operating Characteristics 0.749) patients with OLGIM III-IV if they are negative for H. pylori. Participants with OLGIM II were also at significant risk of EGN (adjusted-HR 7.34; 95% CI 1.60 to 33.7; p=0.02). A significant smoking history further increases the risk of EGN among patients with OLGIM stages II-IV. CONCLUSIONS: We suggest a risk-stratified approach and recommend that high-risk patients (OLGIM III-IV) have endoscopic surveillance in 2 years, intermediate-risk patients (OLGIM II) in 5 years.

Silver, silicon co-substituted hydroxyapatite modulates bacteria-cell competition for enhanced osteogenic function.

Combating bacteria while promoting tissue regeneration is an aim of highest priority for employing biomaterials in orthopedics that often embroiled with pre-operative contamination. Through simulating a surgical site infection environment and an infected implant site, we showcase the ability of a functionally modified hydroxyapatite, Ag,Si-HA that permits preferential adhesion of human bone marrow derived mesenchymal stem cells (BMSCs) over co-cultured bacterial pathogen,Pseudomonas aeruginosa, by displaying immediate suppression and killing of the bacteria present with minimum cytotoxicity for 28 d. And, at the same time, Ag,Si-HA stimulates BMSCs towards osteogenic differentiation despite being within the contaminated milieu. These findings provide well-defined requirements for incorporating antibacterial properties to biomaterials in managing pre-operative contamination. In addition, it highlights the dual positive attributes of Ag,Si-HA as an effective antibacterial biomaterial and at the same time, promotes bone tissue regeneration.

Crystallization of a nonclassical Kazal-type Carcinoscorpius rotundicauda serine protease inhibitor, CrSPI-1, complexed with subtilisin. Corrigendum.

The name of the first author in the article by Tulisas et al. [(2009), Acta Cryst. F65, 533-535] is corrected.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro.

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

Extracellular galectin-3 counteracts adhesion and exhibits chemoattraction in Helicobacter pylori-infected gastric cancer cells.

Galectin-3 (Gal-3) is a ß-galactoside lectin that is upregulated and rapidly secreted by gastric epithelial cells in response to Helicobacter pylori infection. An earlier study reported the involvement of H. pylori cytotoxin-associated gene A (cagA) in the expression of intracellular Gal-3. However, the role of extracellular Gal-3 and its functional significance in H. pylori-infected cells remains uncharacterized. Data presented here demonstrate secretion of Gal-3 is an initial host response event in gastric epithelial cells during H. pylori infection and is independent of CagA. Previously, Gal-3 was shown to bind to H. pylori LPS. The present study elaborates the significance of this binding, as extracellular recombinant Gal-3 (rGal-3) was shown to inhibit the adhesion of H. pylori to the gastric epithelial cells. Interestingly, a decrease in H. pylori adhesion to host cells also resulted in a decrease in apoptosis. Furthermore, the study also demonstrated a chemoattractant role of extracellular rGal-3 in the recruitment of THP-1 monocytes. This study outlines the previously unidentified roles of extracellular Gal-3 where it acts as a negative regulator of H. pylori adhesion and apoptosis in gastric epithelial cells, and as a chemoattractant to THP-1 monocytes. Our findings could contribute to the better understanding of how Gal-3 acts as a modulator under H. pylori-induced pathological conditions.

Understanding the dimorphic lifestyles of human gastric pathogen Helicobacter pylori using the SWATH-based proteomics approach.

Helicobacter pylori may reside in the human stomach as two morphological forms: the culturable spiral form and the viable but non-culturable (VBNC) coccoid form. This bacterium transforms from spiral to coccoid under in vitro suboptimal conditions. However, both spiral and coccoid have demonstrated its infectivity in laboratory animals, suggesting that coccoid may potentially be involved in the transmission of H. pylori. To determine the relevance of the coccoid form in viability and infectivity, we compared the protein profiles of H. pylori coccoids obtained from prolonged (3-month-old) culture with that of 3-day-old spirals of two H. pylori standard strains using SWATH (Sequential Window Acquisition of all Theoretical mass spectra)-based approach. The protein profiles reveal that the coccoids retained basal level of metabolic proteins and also high level of proteins that participate in DNA replication, cell division and biosynthesis demonstrating that coccoids are viable. Most interestingly, these data also indicate that the H. pylori coccoids possess higher level of proteins that are involved in virulence and carcinogenesis than their spiral counterparts. Taken together, these findings have important implications in the understanding on the pathogenesis of H. pylori-induced gastroduodenal diseases, as well as the probable transmission mode of this bacterium.

Galectin 3 acts as an enhancer of survival responses in H. pylori-infected gastric cancer cells.

Galectin 3 (Gal-3) is upregulated in gastric epithelial cells as a host response to Helicobacter pylori infection. However, the significance of Gal-3 expression in H. pylori-infected cells is not well established. We analyzed Gal-3 intracellular expression, localization, and its effects in H. pylori-infected gastric epithelial cells. The predominantly nuclear confined Gal-3 was shown to be upregulated and exported out to the cytoplasm in H. pylori-infected AGS cells. The nuclear export was channeled through CRM-1 (exportin-1) protein. Interestingly, knock down of Gal-3 expression led to reduced NF-κB promoter activity and interleukin-8 (IL-8) secretion, suggesting its pro-inflammatory roles. Furthermore, Gal-3 was found to be pro-proliferative and anti-apoptotic in nature, as its knock down caused a reduction in cell proliferation and an increase in apoptosis, respectively. Taken together, our data suggest the expression and upregulation of Gal-3 as a critical endogenous event in H. pylori infection that interferes with various intracellular events, causing prolonged cell survival, which is characteristic in carcinogenesis.

Instrumental Role of Helicobacter pylori γ-Glutamyl Transpeptidase in VacA-Dependent Vacuolation in Gastric Epithelial Cells.

Helicobacter pylori causes cellular vacuolation in host cells, a cytotoxic event attributed to vacuolating cytotoxin (VacA) and the presence of permeant weak bases such as ammonia. We report here the role of γ-glutamyl transpeptidase (GGT), a constitutively expressed secretory enzyme of H. pylori, in potentiating VacA-dependent vacuolation formation in H. pylori-infected AGS and primary gastric cells. The enhancement is brought about by GGT hydrolysing glutamine present in the extracellular medium, thereby releasing ammonia which accentuates the VacA-induced vacuolation. The events of vacuolation in H. pylori wild type (WT)- and Δggt-infected AGS cells were first captured and visualized by real-time phase-contrast microscopy where WT was observed to induce more vacuoles than Δggt. By using semi-quantitative neutral red uptake assay, we next showed that Δggt induced significantly less vacuolation in AGS and primary gastric epithelial cells as compared to the parental strain (P<0.05) indicating that GGT potentiates the vacuolating effect of VacA. Notably, vacuolation induced by WT was significantly reduced in the absence of GGT substrate, glutamine (P<0.05) or in the presence of a competitive GGT inhibitor, serine-borate complex. Furthermore, the vacuolating ability of Δggt was markedly restored when co-incubated with purified recombinant GGT (rGGT), although rGGT itself did not induce vacuolation independently. Similarly, the addition of exogenous ammonium chloride as a source of ammonia also rescued the ability of Δggt to induce vacuolation. Additionally, we also show that monoclonal antibodies against GGT effectively inhibited GGT activity and successfully suppressed H. pylori-induced vacuolation. Collectively, our results clearly demonstrate that generation of ammonia by GGT through glutamine hydrolysis is responsible for enhancing VacA-dependent vacuolation. Our findings provide a new perspective on GGT as an important virulence factor and a promising target in the management of H. pylori-associated gastric diseases.

Inflammation and proliferation - a causal event of host response to Helicobacter pylori infection.

Helicobacter pylori is a major aetiological agent in the development of various gastroduodenal diseases. Its persistence in gastric mucosa is determined by the interaction between various host, microbial and environmental factors. The bacterium colonizes the gastric epithelium and induces activation of various chemokine mediators, including NFκB, the master regulator of inflammation. H. pylori infection is also associated with an increase in expression of cell cycle regulators, thereby leading to mucosal cell hyper-proliferation. Thus, H. pylori-associated infections manifest activation of key host response events, which inadvertently could lead to the establishment of chronic infection and neoplastic progression. This article reviews and elaborates the current knowledge in H. pylori-induced activation of various host signalling pathways that could promote cancer development. Special focus is placed on the inflammatory and proliferative responses that could serve as suitable biomarkers of infection, since a sustained cell proliferation in an environment rich in inflammatory cells is characteristic in H. pylori-associated gastric malignancies. Here, the role of ERK and WNT signalling in H. pylori-induced activation of inflammatory and proliferative responses respectively is discussed in detail. An in depth analysis of the underlying signalling pathways and interacting partners causing alterations in these crucial host responses could contribute to the development of successful therapeutic strategies for the prevention, management and treatment of H. pylori infection.

An amidation/cyclization approach to the synthesis of N-hydroxyquinolinones and their biological evaluation as potential anti-plasmodial, anti-bacterial, and iron(II)-chelating agents.

A 26-member library of novel N-hydroxyquinolinone derivatives was synthesized by a one-pot Buchwald-type palladium catalyzed amidation and condensation sequence. The design of these rare scaffolds was inspired from N-hydroxypyridones and 2-quinolinones classes of compounds which have been shown to have rich biological activities. The synthesized compounds were evaluated for their anti-plasmodial and anti-bacterial properties. In addition, these compounds were screened for their iron(II)-chelation properties. Notably, four of these compounds exhibited anti-plasmodial activities comparable to that of the natural product cordypyridone B.

TLR cross-talk confers specificity to innate immunity.

Cross-talk within the innate immune pathways is highly complex and contains many unknowns. Here, we discuss the different combinations of PAMPs, together with the sequence, order, and dosage of consecutive PAMP challenges, which determine the nature of the immune response by macrophages. The engagement of different Toll-like receptor (TLR) ligands leads to quantitatively and qualitatively unique cytokine production, showing that TLR pathway crosstalk enables the innate immune system to orchestrate immediate local and global responses. It is likely that multiple pathways are involved in the regulation of cytokine synergy, including many that have yet to be discovered.

Preferential silent survival of intracellular bacteria in hemoglobin-primed macrophages.

Hemolysis releases hemoglobin (Hb), a prooxidant, into circulation. While the heme iron is a nutrient for the invading pathogens, it releases ROS, which is both microbicidal and cytotoxic, making it a double-edged sword. Previously, we found a two-pass detoxification mechanism involving the endocytosis of Hb into monocytes in collaboration with vascular endothelial cells to overcome oxidative damage. This prompted us to examine the effect of Hb priming on host cell viability and intracellular bacterial clearance during a hemolytic infection. Here, we demonstrate that Hb-primed macrophages harbor a higher intracellular bacterial load but with suppressed apoptosis. p-ERK and p-p38 MAPK were significantly downregulated, with concomitant impairment of Bax and downstream caspases. The Hb-primed cells harboring intracellular bacteria upregulated anti-inflammatory IL-10 and downregulated proinflammatory TNF-α, which further enhanced the infectivity of the neighboring cells. Our findings suggest that opportunistic intracellular pathogens exploit the Hb-scavenging machinery of the host to silently persist within the circulating phagocytes by suppressing apoptosis while escaping immune surveillance.

The effects of silver, silicon-containing apatite towards bacteria and cell responses.

An integrated approach is proposed to incorporate silicon and silver into hydroxyapatite (HA) to enhance the biological response and reduce implant-related infection in bone substitutes. This study examined the responses of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria to silver, silicon-containing apatite (Ag,Si-HA). Scanning electron microscopy images revealed significant reduction in adherence of S. aureus and E. coli bacteria on Ag,Si-HA as compared to HA. The antibacterial property of Ag,Si-HA was shown from a 7-log reduction of S. aureus population in the test solution and on the sample's surface as compared to HA at day 7. Rapid inhibition of the adherent bacteria suggested that the antibacterial action of Ag incorporated in Ag,Si-HA could be attributed to the Ag(+) ions on the crystal surface rather than the released Ag(+) ions. Presence of Ag may influence the biological response of HA and as such, the long-term interaction between human adipose-derived mesenchymal stem cells and Ag,Si-HA was evaluated in-vitro. An alamarBlue™ assay showed higher cell proliferation for Ag,Si-HA as compared to HA from day 3 onwards. Immunofluorescence staining revealed well-spread actin cytoskeletons on Ag,Si-HA. In addition, signs of extracellular matrix secretion and biomineralization were observed on Ag,Si-HA at day 14 onwards. Results demonstrated enhanced bone differentiation on Ag,Si-HA, as indicated by a higher level of protein expressions (type 1 collagen and osteocalcin) from day 14 to 21. Therefore, the incorporation of Ag and Si complement each other by endowing HA with antibacterial property, and concurrently promoting biological performance of the cells.

Site specific immobilization of a potent antimicrobial peptide onto silicone catheters: evaluation against urinary tract infection pathogens.

Bacterial colonization of urinary catheters is a common problem leading to Catheter Associated Urinary Tract Infections (CAUTIs) in patients, which result in high treatment costs and associated complications. Due to the advantages of antimicrobial peptides (AMPs) compared to most other antimicrobial molecules, an increasing number of AMP-coated surfaces is being developed but their efficacy is hindered by suboptimal coating methods and loss of peptide activity upon surface tethering. This study aims to address this issue by employing a methodic approach that combines a simple selective chemical immobilization platform developed on a silicone catheter with the choice of a potent AMP, Lasioglossin-III (Lasio-III), to allow site specific immobilization of Lasio-III at an effective surface concentration. The Lasio-III peptide was chemically modified at the N-terminal with a cysteine residue to facilitate cysteine-directed immobilization of the peptide onto a commercial silicone catheter surface via a combination of an allyl glycidyl ether (AGE) brush and polyethylene glycol (PEG) based chemical coupling. The amount of immobilized peptide was determined to be 6.59 ± 0.89 µg cm-2 by Sulfo-SDTB assay. The AMP-coated catheter showed good antimicrobial activity against both Gram positive and negative bacteria. The antimicrobial properties of the AMP-coated catheter were sustained for at least 4 days post-incubation in a physiologically relevant environment and artificial urine and prevented the biofilm growth of E. coli and E. faecalis. Adenosine tri-phosphate leakage and propidium iodide fluorescence studies further confirmed the membranolytic mode of action of the immobilized peptide. To the best of our knowledge, this is the first proof-of-concept study that reports the efficacy of AMP immobilization by sulfhydryl coupling on a real catheter surface.

Helicobacter pylori γ-glutamyl transpeptidase: a formidable virulence factor.

Helicobacter pylori (H. pylori) produce an enzyme known as γ-glutamyl transpeptidase (HpGGT) that is highly conserved and common to all strains. HpGGT has been gaining increasing attention as an important virulence factor of the bacterium, having been demonstrated to be an important colonization factor in several animal models and has also recently been strongly associated with the development of peptic ulcer disease. From the results of various independent researcher groups, it is clear that HpGGT acts through several pathways to damage gastric epithelial cells including the induction of apoptosis and cell cycle arrest, production of reactive oxygen species leading to DNA damage, promotion of inflammation by increasing cyclooxygenase-2 and interleukin-8 expression, and upregulation of heparin-binding epidermal growth factor-like growth factor resulting in cell survival and proliferation. In addition, the potential role of HpGGT in promoting gastric carcinogenesis will also be discussed in this review. Apart from affecting the gastric epithelium, HpGGT also has immunomodulatory actions on host immune cells where it displays an antiproliferative effect on T cells by inducing cell cycle arrest and also works with other H. pylori virulence factors to skew dendritic cells towards a tolerogenic phenotype, possibly contributing to the persistence of the pathogen in the gastric mucosa.

Immobilization studies of an engineered arginine-tryptophan-rich peptide on a silicone surface with antimicrobial and antibiofilm activity.

With the rapid rise of antibiotic-resistant-device-associated infections, there has been increasing demand for an antimicrobial biomedical surface. Synthetic antimicrobial peptides that have excellent bactericidal potency and negligible cytotoxicity are promising targets for immobilization on these target surfaces. An engineered arginine-tryptophan-rich peptide (CWR11) was developed, which displayed potent antimicrobial activity against a broad spectrum of microbes via membrane disruption, and possessed excellent salt resistance properties. A tethering platform was subsequently developed to tether CWR11 onto a model polymethylsiloxane (PDMS) surface using a simple and robust strategy. Surface characterization assays such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX) confirmed the successful grafting of CWR11 onto the chemically treated PDMS surface. The immobilized peptide concentration was 0.8 ± 0.2 µg/cm(2) as quantitated by sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate (sulfo-SDTB) assay. Antimicrobial assay and cytotoxic investigation confirmed that the peptide-immobilized surface has good bactericidal and antibiofilm properties, and is also noncytotoxic to mammalian cells. Tryptophan-arginine-rich antimicrobial peptides have the potential for antimicrobial protection of biomedical surfaces and may have important clinical applications in patients.

CD163 and IgG codefend against cytotoxic hemoglobin via autocrine and paracrine mechanisms.

Lysis of RBCs during numerous clinical settings such as severe hemolytic anemia, infection, tissue injury, or blood transfusion releases the endogenous damage-associated molecular pattern, hemoglobin (Hb), into the plasma. The redox-reactive Hb generates cytotoxic reactive oxygen species, disrupting the redox balance and impairing the immune-responsive blood cells. Therefore, it is crucial to understand how the immune system defends against the cytotoxic Hb. We identified a shortcut "capture and quench" mechanism of detoxification of Hb by the monocyte scavenger receptor CD163, independent of the well-known dominant antioxidant, haptoglobin. Our findings support a highly efficient two-pass mechanism of detoxification and clearance of Hb: 1) a direct suppression of Hb-pseudoperoxidase activity by CD163, involving an autocrine loop of CD163 shedding, sequestration of Hb, recycling, and homeostasis of CD163 in human monocytes and 2) paracrine transactivation of endothelial cells by the shedded soluble CD163 (sCD163), which further detoxifies and clears residual Hb. We showed that sCD163 and IgG interact with free Hb in the plasma and subsequently the sCD163-Hb-IgG complex is endocytosed into monocytes via FcγR. The endocytosed sCD163 is recycled to restore the homeostasis of CD163 on the monocyte membrane in an autocrine cycle, whereas the internalized Hb is catabolized. Using ex vivo coculture experiments, we demonstrated that the monocyte-derived sCD163 and IgG shuttle residual plasma Hb into the proximal endothelial cells. These findings suggest that CD163 and IgG collaborate to engage monocytes and endothelial cells in a two-pass detoxification mechanism to mount a systemic defense against Hb-induced oxidative stress.

The synergy in cytokine production through MyD88-TRIF pathways is co-ordinated with ERK phosphorylation in macrophages.

Although specific single Toll-like receptor (TLR) ligands are known to drive the development of Th1 or Th2 immunity, the outcome of different combinations of TLR ligands on innate immunity is not well defined. Spatiotemporal dynamics are critical in determining the specificity of the immune response, but the mechanisms underlying combinatorial TLR stimulation remain unclear. Here, we tested pairwise combinations of TLR ligands separated by different time intervals for their effect on cytokine production in macrophages. We observed that stimulation via a combination of MyD88- and TRIF-utilizing adaptors leads to a highly synergistic cytokine response. On a timescale of 4-24 h, macrophages pretreated with poly(I:C) (TLR3 ligand) are cross-primed to a second stimulation with R848 (TLR7 ligand) and vice versa, and each condition exhibits different optimal time windows of synergistic response for each cytokine. We show that the synergy resulting from combinatorial stimuli (poly(I:C) and R848 is also regulated by the order and dosage of the TLR agonists. Secondary response genes, which depend on new protein synthesis for transcription, show greater synergy than primary response genes, and such enhancement is abolished when new protein synthesis is inhibited. Synergistic cytokine production appears concordant with sustained ERK phosphorylation, suggesting that the de novo factors act via inhibition of ERK dephosphorylation, for example, by the downregulation of dual specificity phosphatase 6. Taken together, our findings illustrate a checkpoint in the innate immune system, where the synchronization of timing of both MyD88 and TRIF pathways is required for a maximal cytokine response and potential memory effect in macrophages.

Effect of silver content on the antibacterial and bioactive properties of silver-substituted hydroxyapatite.

The long-term success of a biomaterial used during surgery may be compromised by infection. A possible effective solution is to make the biomaterial osteoconductive and antibacterial. A range of silver-substituted hydroxyapatite (AgHA) of up to 1.1 wt. % of Ag was synthesized. AgHA displayed a rod-like morphology of dimensions ~50 nm in length and ~15 nm in width. Phase-pure AgHA was demonstrated in the X-ray diffraction patterns and Fourier transform infrared spectroscopy spectra. Comparing with hydroxyaptite (HA), 0.5AgHA exhibited a 3-log reduction in the number of bacteria. Diffusion of the entrapped Ag(+) ions towards the crystal structure surface was revealed by an increase of 6 at. % Ag in the X-ray photoelectron spectroscopy results. Furthermore, less than 0.5 ppm of Ag(+) ions being released from 0.5AgHA into the deionized water medium was evidenced from the inductively coupled plasma mass spectrometry results. AgHA produced by co-precipitation gave rise to minimal release of Ag(+) ions. It was hypothesized that the diffused surface Ag(+) ions damaged the bacteria cell membrane and impede its replication. With the culturing time, significant increase in the number of human mesenchymal stem cells (p < 0.05) was demonstrated on 0.5AgHA.

Persistent Helicobacter pylori specific Th17 responses in patients with past H. pylori infection are associated with elevated gastric mucosal IL-1ß.

BACKGROUND: Ongoing Helicobacter pylori (HP) infection triggers a chronic active gastritis. Eradicating HP reduces gastric inflammation, but does not eliminate it. We sought to characterize this persistent gastritis, and demonstrate the persistence of HP-specific Th17 responses in individuals previously infected with HP but who no longer had evidence of ongoing infection. METHODOLOGY/PRINCIPAL FINDINGS: Study subjects were divided into 3 groups 55 individuals had active HP infection (group A), 41 were diagnosed with previous HP infection (group P), and 59 were naïve to HP (group N). Blood and gastric tissue were obtained with written informed consent from all subjects, and immune responses were evaluated using flow cytometry, semi-quantitative real time PCR, immunofluorescent staining, ELISA, and multiplex cytometric bead array for cytokine quantification. Elevated IL-17A responses were observed in patients from group A compared to group N. Interestingly, IL-17A responses remained persistently elevated in the blood and gastric mucosa of individuals from group P, despite the absence of ongoing HP infection. Using purified CD4(+) T cells as effectors and antibodies that blocked antigen presentation by MHC Class II, we showed that these persistent IL-17A responses were mediated primarily by HP-specific Th17 cells, rather than other immune cells that have also been described to secrete IL-17A. Gastric mucosal IL-1ß levels were also persistently elevated in group P, and neutralisation of IL-1ß reduced the HP-specific IL-17A response of purified CD4(+) T cells to autologous HP-pulsed antigen presenting cells in vitro, suggesting a functional association between IL-1ß and the persistent Th17 response in group P patients. CONCLUSIONS/SIGNIFICANCE: Despite lack of ongoing HP infection, HP-specific Th17 cells persist in the blood and gastric mucosa of individuals with past HP infection. We speculate that this persistent inflammation might contribute to gastric mucosal pathology, for example, persistent increased gastric cancer risk despite eradication of HP.