Chronic inflammation in the stomach induces metaplasia, the pre-cancerous lesion that precedes inflammation-driven neoplastic transformation. While Hedgehog signaling contributes to the initiation of ...some cancers, its role in gastric transformation remains poorly defined. We found that Helicobacter-infected C57BL/6 mice develop extensive mucous cell metaplasia at 6 month but not at 2 months post-infection. Gastric metaplasia coincided with the appearance of CD45(+)MHCII(+)CD11b(+)CD11c(+) myeloid cells that were normally not present in the chronic gastritis at 2 months. The myeloid regulatory gene Schlafen-4 was identified in a microarray analysis comparing infected WT versus Gli1 null mice and was expressed in the CD11b(+)CD11c(+) myeloid population. Moreover this same population expressed IL-1β and TNFα pro-inflammatory cytokines. By 6 months, the mucous neck cell metaplasia (SPEM) expressed IL-6, phosphorylated STAT3 and the proliferative marker Ki67. Expression was not observed in Gli1 mutant mice consistent with the requirement of Gli1 to induce this pre-neoplastic phenotype. Ectopic Shh ligand expression alone was not sufficient to induce SPEM, but with Helicobacter infection synergistically increased the histologic severity observed with the inflammation. Therefore Hedgehog signaling is required, but is not sufficient to generate pre-neoplastic changes during chronic gastritis. Gli1-dependent myeloid cell differentiation plays a pivotal role in the appearance of myeloid cell subtypes ostensibly required for SPEM development. Moreover, it suggests that therapies capable of targeting this phenotypic switch might prevent progression to metaplasia, the pre-neoplastic change that develops prior to dysplasia and gastric cancer, which also occurs in other epithelial-derived neoplasias initiated by chronic inflammation.
The gut microbiota is essential for the maintenance of intestinal immune homeostasis and is responsible for breaking down dietary fiber into short-chain fatty acids (SCFAs). Butyrate, the most ...abundant bioactive SCFA in the gut, is a histone deacetylase inhibitor (HDACi), a class of drug that has potent immunomodulatory properties. This characteristic of butyrate, along with our previous discovery that conventional dendritic cells (DCs) are required for the development of experimental colitis, led us to speculate that butyrate may modulate DC function to regulate gut mucosal homeostasis. We found that butyrate, in addition to suppressing LPS-induced bone marrow-derived DC maturation and inhibiting DC IL-12 production, significantly induced IL-23 expression. The upregulation of mRNA subunit IL-23p19 at the pretranslational level was consistent with the role of HDACi on the epigenetic modification of gene expression. Furthermore, the mechanism of IL-23p19 upregulation was independent of Stat3 and ZBP89. Coculture of splenocytes with LPS-stimulated DCs pretreated with or without butyrate was performed and showed a significant induction of IL-17 and IL-10. We demonstrated further the effect of butyrate in vivo using dextran sulfate sodium (DSS)-induced colitis and found that the addition of butyrate in the drinking water of mice worsened DSS-colitis. This is in contrast to the daily intraperitoneal butyrate injection of DSS-treated mice, which mildly improved disease severity. Our study highlights a novel effect of butyrate in upregulating IL-23 production of activated DCs and demonstrates a difference in the host response to the oral vs. systemic route of butyrate administration.
Background & Aims Stress alters brain–gut interactions and could exacerbate intestinal disorders, including irritable bowel syndrome. Alterations in the intestinal microbiota have been associated ...with irritable bowel syndrome. Maintenance of healthy microbiota requires nucleotide-binding oligomerization domain protein-like receptors, pyrin-domain containing (NLRP)-6 inflammasomes. We investigated the involvement of NLRP6 in water-avoidance stress (WAS)-induced intestinal disorders in mice. Methods B57BL6 mice were subjected to WAS for 1 hour each day for 10 days; body weights and intestinal inflammation and permeability were analyzed. We investigated signaling via the NLRP3 and NLRP6 inflammasomes, and the role of corticotropin-releasing hormone (CRH) in WAS-associated inflammation and NLRP6 inhibition. Mice that were not exposed to stress were co-housed with mice subjected to WAS to determine the effects of WAS-induced dysbiosis, measured by sequencing bacterial 16S ribosomal RNA. We also assessed the effects of a peroxisome proliferator-activated receptor-γ agonist and probiotics. Results WAS-induced small-bowel inflammation (enteritis) was associated with inhibition of NLRP6, but not NLRP3, and was prevented by a peroxisome proliferator-activated receptor-γ agonist, which induced epithelial expression of NLRP6. CRH was released during WAS and inhibited NLRP6 expression. WAS induced alterations in the gut microbiota of mice; co-housed nonstressed mice developed enteritis associated with increased CRH and decreased levels of NLRP6. Probiotic therapy reduced intestinal inflammation in mice with WAS-induced enteritis. Conclusions Exposure of mice to stress inhibits NLRP6 and alters the composition of the gut microbiota, leading to intestinal inflammation. These findings might explain the benefits of probiotics for patients with stress-associated gastrointestinal disorders.
Background & Aims Gut dysbiosis is closely involved in the pathogenesis of inflammatory bowel disease (IBD). However, it remains unclear whether IBD-associated gut dysbiosis contributes to disease ...pathogenesis or is merely secondary to intestinal inflammation. We established a humanized gnotobiotic (hGB) mouse system to assess the functional role of gut dysbiosis associated with 2 types of IBD: Crohn's disease (CD) and ulcerative colitis (UC). Methods Germ-free mice were colonized by the gut microbiota isolated from patients with CD and UC, and healthy controls. Microbiome analysis, bacterial functional gene analysis, luminal metabolome analysis, and host gene expression analysis were performed in hGB mice. Moreover, the colitogenic capacity of IBD-associated microbiota was evaluated by colonizing germ-free colitis-prone interleukin 10–deficient mice with dysbiotic patients' microbiota. Results Although the microbial composition seen in donor patients' microbiota was not completely reproduced in hGB mice, some dysbiotic features of the CD and UC microbiota (eg, decreased diversity, alteration of bacterial metabolic functions) were recapitulated in hGB mice, suggesting that microbial community alterations, characteristic for IBD, can be reproduced in hGB mice. In addition, colonization by the IBD-associated microbiota induced a proinflammatory gene expression profile in the gut that resembles the immunologic signatures found in CD patients. Furthermore, CD microbiota triggered more severe colitis than healthy control microbiota when colonized in germ-free interleukin 10–deficient mice. Conclusions Dysbiosis potentially contributes to the pathogenesis of IBD by augmenting host proinflammatory immune responses. Transcript profiling: GSE73882.
Background
The Maastricht V/Florence Consensus Report recommends amoxicillin‐fluoroquinolone triple or quadruple therapy as a second‐line treatment for Helicobacter pylori infection. An important ...caveat of amoxicillin‐fluoroquinolone rescue therapy is poor eradication efficacy in the presence of fluoroquinolone resistance. The study aimed to investigate the efficacies of tetracycline‐levofloxacin (TL) quadruple therapy and amoxicillin‐levofloxacin (AL) quadruple therapy in the second‐line treatment of H. pylori infection.
Methods
Consecutive H. pylori‐infected subjects after the failure of first‐line therapies were randomly allocated to receive either TL quadruple therapy (tetracycline 500 mg QID, levofloxacin 500 mg QD, esomeprazole 40 mg BID, and tripotassium dicitrato bismuthate 300 mg QID) or AL quadruple therapy (amoxicillin 500 mg QID, levofloxacin 500 mg QD, esomeprazole 40 mg BID, and tripotassium dicitrato bismuthate 300 mg QID) for 10 days. Post‐treatment H. pylori status was assessed 6 weeks after the end of therapy.
Results
The study was early terminated after an interim analysis. In the TL quadruple group, 50 out of 56 patients (89.3%) had successful eradication of H. pylori infection. Cure of H. pylori infection was achieved only in 39 of 52 patients (69.6%) receiving AL quadruple therapy. Intention‐to‐treat analysis showed that TL quadruple therapy achieved a markedly higher eradication rate than AL quadruple therapy (95% confidence interval: 4.8% to 34.6%; p = 0.010). Further analysis revealed that TL quadruple therapy had a high eradication rate for both levofloxacin‐susceptible and resistant strains (100% and 88.9%). In contrast, AL quadruple therapy yielded a high eradication for levofloxacin‐susceptible strains (90.9%) but a poor eradication efficacy for levofloxacin‐resistant strains (50.0%). The two therapies exhibited comparable frequencies of adverse events (37.5% vs 21.4%) and drug adherence (98.2% vs 94.6%).
Conclusions
Ten‐day TL quadruple therapy is more effective than AL quadruple therapy in the second‐line treatment of H. pylori infection in a population with high levofloxacin resistance.
To evaluate the outcomes of furazolidone- and amoxicillin-based quadruple therapy for treatment of
(
) infection and identify predictors of failed eradication.
Patients with
infection treated with ...furazolidone, amoxicillin, bismuth, and proton pump inhibitor therapy (January 2015 to December 2015) who received the
C-urea breath test > 4 wk after treatment were evaluated. Demographic and clinical data including prior
treatment attempts, medication adherence, alcohol and cigarette consumption during therapy, and treatment-related adverse events were recorded by reviewing medical records and telephone surveys.
eradication rates for overall and subgroups were evaluated. Multivariate analysis was performed to identify independent predictors of failed
eradication.
Of the 992 patients treated and retested for
infection, the overall eradication rate was 94.5% 95% confidence interval (CI): 94.1%-95.9%.
eradication rate of primary therapy was 95.0% (95%CI: 93.5%-96.5%), while that of rescue therapy was 91.3% (95%CI: 86.8%-95.8%). Among the 859 patients who completed the study protocol, 144 (17%) reported treatment-related adverse events including 24 (3%) leading to premature discontinuation. On multivariate analysis, poor medication adherence adjusted odds ratio (AOR) = 6.7, 95%CI: 2.8-15.8, two or more previous
treatments (AOR = 7.4, 95%CI: 2.2-24.9), alcohol consumption during therapy (AOR = 4.4, 95%CI: 1.5-12.3), and possibly smoking during therapy (AOR = 1.9, 95%CI: 0.9-4.3) were associated with failed
eradication.
Furazolidone- and amoxicillin-based quadruple therapy for
infection in an area with a high prevalence of clarithromycin resistance demonstrated high eradication rates as primary and rescue therapies with a favorable safety profile. Patient education targeting abstinence from alcohol during therapy and strict medication adherence may further optimize
eradication.
Background:
Epidemiologic data suggest a protective effect of Helicobacter pylori infection against the development of autoimmune disease. Laboratory data illustrate H. pylori's ability to induce ...immune tolerance and limit inflammatory responses. Numerous observational studies have investigated the association between H. pylori infection and inflammatory bowel disease (IBD). Our aim was to perform a systematic review and meta‐analysis of this association.
Methods:
Medline, EMBASE, bibliographies, and meeting s were searched by 2 independent reviewers. Of 369 s reviewed, 30 promising articles were reviewed in detail. Twenty‐three studies met our inclusion criteria (subject N = 5903). Meta‐analysis was performed with the metan command in Stata 10.1.
Results:
Overall, 27.1% of IBD patients had evidence of infection with H. pylori compared to 40.9% of patients in the control group. The estimated relative risk of H. pylori infection in IBD patients was 0.64 (95% confidence interval CI: 0.54–0.75). There was significant heterogeneity in the included studies that could not be accounted for by the method of IBD and H. pylori diagnosis, study location, or study population age.
Conclusions:
These results suggest a protective benefit of H. pylori infection against the development of IBD. Heterogeneity among studies and the possibility of publication bias limit the certainty of this finding. Further studies investigating the effect of eradication of H. pylori on the development of IBD are warranted. Because environmental hygiene and intestinal microbiota may be strong confounders, further mechanistic studies in H. pylori mouse models are also necessary to further define the mechanism of this negative association. (Inflamm Bowel Dis 2009;)
The host immune response to gastrointestinal (GI) infections, hypersensitivity reactions, or GI cancers comprises numerous pathways that elicit responses on different host cells. Some of these ...include (1) the stimulation of mast cells
their IgE receptor, (2) the production of antibodies leading to antibody-mediated cytotoxic T/natural killer cell killing, (3) the activation of the complement pathway, and (4) the activation of the adaptive immune response
antigen-presenting cell, T cell, and B cell interactions. Within the plethora of these different responses, several host immune cells represent major key players such as those of myeloid lineage (including neutrophils, macrophages, myeloid-derived suppressor cells) or lymphoid lineage (including T and B cells). In this review, we focus on newly identified metabolites and metabolite receptors that are expressed by either myeloid or lymphoid lineages. Irrespective of their source, these metabolites can in certain instances elicit responses on a wide range of cell types. The myeloid-expressed metabolic enzymes and receptors which we will discuss in this review include arginase 2 (Arg2), indoleamine-2,3-dioxygenase 1 (IDO1), hydroxycarboxylic acid receptor 2 (Hcar2; also called GPR109A), and immunoresponsive gene 1 (Irg1). We will also review the role of the lymphoid-expressed metabolite receptor that binds to the sphingosine-1-phosphate (S1P) sphingolipid. Moreover, we will describe the synthesis and metabolism of retinoic acid, and its effect on T cell activation. The review will then discuss the function of these metabolites in the context of GI disease. The review provides evidence that metabolic pathways operate in a disease- and context-dependent manner-either independently or concomitantly-in the GI tract. Therefore, an integrated approach and combinatorial analyses are necessary to devise new therapeutic strategies that can synergistically improve prognoses.
Background & Aims Helicobacter pylori infection increases gastric regulatory T cell (Treg) response, which may contribute to H pylori immune escape. We hypothesize that H pylori directs Treg skewing ...by way of dendritic cells (DCs) and thus inhibits interleukin-17+ helper T cells (Th17) immunity. Methods Two-photon microscopy was used to locate DCs in gastric lamina propria of mice. The induction of Th17 and Treg responses by bacteria-pulsed murine bone marrow–derived DCs was analyzed by cytokine production and stimulation of T-cell proliferation. The effect of VacA, CagA, transforming growth factor-β (TGF-β), and IL-10 on Th17/Treg balance was assessed. The in vivo significance of Tregs on the H pylori –specific Th17 response and H pylori density was determined by using anti-CD25 neutralizing antibodies to deplete Tregs in mice. Results We showed that mucosal CD11c+ DCs are located near the surface of normal gastric epithelium, and their number increased after H pylori infection. Study of the direct interaction of DCs with H pylori showed a Treg-skewed response. The Treg skewing was independent of H pylori VacA and CagA and dependent on TGF-β and IL-10. In vivo Treg skewing by adoptive transfer of H pylori –pulsed DCs reduces the ratio of gastric IL-17/Foxp3 mRNA expressions. The depletion of CD25+ Tregs results in early reduction of H pylori density, which is correlated with enhanced peripheral H pylori –specific Th17, but not Th1, response. Conclusions Overall, our study indicates that H pylori alters the DC-polarized Th17/Treg balance toward a Treg-biased response, which suppresses the effective induction of H pylori –specific Th17 immunity.
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