Evaluation of DNA extraction methods from mouse stomachs for the quantification of H. pylori by real-time PCR

Helicobacter pylori-Induced Angiopoietin-Like 4 Promotes Gastric Bacterial Colonization and Gastritis

Helicobacter pylori infection is characterized as progressive processes of bacterial persistence and chronic gastritis with features of infiltration of mononuclear cells more than granulocytes in gastric mucosa. Angiopoietin-like 4 (ANGPTL4) is considered a double-edged sword in inflammation-associated diseases, but its function and clinical relevance in H. pylori-associated pathology are unknown. Here, we demonstrate both pro-colonization and pro-inflammation roles of ANGPTL4 in H. pylori infection. Increased ANGPTL4 in the infected gastric mucosa was produced from gastric epithelial cells (GECs) synergistically induced by H. pylori and IL-17A in a cagA-dependent manner. Human gastric ANGPTL4 correlated with H. pylori colonization and the severity of gastritis, and mouse ANGPTL4 from non-bone marrow-derived cells promoted bacteria colonization and inflammation. Importantly, H. pylori colonization and inflammation were attenuated in Il17a -/-, Angptl4 -/-, and Il17a -/- Angptl4 -/- mice. Mechanistically, ANGPTL4 bound to integrin αV (ITGAV) on GECs to suppress CXCL1 production by inhibiting ERK, leading to decreased gastric influx of neutrophils, thereby promoting H. pylori colonization; ANGPTL4 also bound to ITGAV on monocytes to promote CCL5 production by activating PI3K-AKT-NF-κB, resulting in increased gastric influx of regulatory CD4+ T cells (Tregs) via CCL5-CCR4-dependent migration. In turn, ANGPTL4 induced Treg proliferation by binding to ITGAV to activate PI3K-AKT-NF-κB, promoting H. pylori-associated gastritis. Overall, we propose a model in which ANGPTL4 collectively ensures H. pylori persistence and promotes gastritis. Efforts to inhibit ANGPTL4-associated pathway may prove valuable strategies in treating H. pylori infection.

Optimizing waterborne eDNA capture from waterholes in savanna systems under remote field conditions

Environmental DNA (eDNA) is used for biodiversity assessments in a variety of ecosystems across the globe, whereby different eDNA concentration, preservation and extraction methods can outperform others depending on the sampling conditions and environment. Tropical and subtropical ecosystems in Africa are among the less studied systems concerning eDNA-based monitoring. Waterholes in arid parts of southern Africa represent important agglomeration points for terrestrial mammals, and the eDNA shed into such waterbodies provides a powerful source of information for monitoring mammalian biodiversity in the surrounding area. However, the applied methods for eDNA sampling, preservation and filtering in different freshwater systems vary greatly, and rigorous protocol testing in African freshwater systems is still lacking. This study represents the first attempt to examine variations in eDNA concentration, preservation and extraction methods under remote field conditions using waterborne eDNA in a savanna system. Collected samples were heavily affected by microalgal and bacterial growth, impeding eDNA capture and PCR success. We demonstrate clear effects of the methodological choices, which also depend on the state of eDNA. A preliminary metabarcoding run showed little taxonomic overlap in mammal species detection between two metabarcoding primers tested. We recommend water filtering (using filters with pore sizes >1 μm) over centrifugation for eDNA concentration, Longmire's solution for ambient temperature sample preservation and Qiagen's DNeasy PowerSoil Pro Kit for DNA extraction of these inhibitor-prone samples. Furthermore, at least two independent metabarcoding markers should be utilized in order to maximize species detections in metabarcoding studies.

Tubulointerstitial nephritis antigen-like 1 is a novel matricellular protein that promotes gastric bacterial colonization and gastritis in the setting of Helicobacter pylori infection

The interaction between the gastric epithelium and immune cells plays key roles in H. pylori-associated pathology. Here, we demonstrate a procolonization and proinflammatory role of tubulointerstitial nephritis antigen-like 1 (TINAGL1), a newly discovered matricellular protein, in H. pylori infection. Increased TINAGL1 production by gastric epithelial cells (GECs) in the infected gastric mucosa was synergistically induced by H. pylori and IL-1β via the ERK-SP1 pathway in a cagA-dependent manner. Elevated human gastric TINAGL1 correlated with H. pylori colonization and the severity of gastritis, and mouse TINAGL1 derived from non-bone marrow-derived cells promoted bacterial colonization and inflammation. Importantly, H. pylori colonization and inflammation were attenuated in Tinagl1-/- and Tinagl1ΔGEC mice and were increased in mice injected with mouse TINAGL1. Mechanistically, TINAGL1 suppressed CCL21 expression and promoted CCL2 production in GECs by directly binding to integrin α5β1 to inhibit ERK and activate the NF-κB pathway, respectively, which not only led to decreased gastric influx of moDCs via CCL21-CCR7-dependent migration and, as a direct consequence, reduced the bacterial clearance capacity of the H. pylori-specific Th1 response, thereby promoting H. pylori colonization, but also resulted in increased gastric influx of Ly6Chigh monocytes via CCL2-CCR2-dependent migration. In turn, TINAGL1 induced the production of the proinflammatory protein S100A11 by Ly6Chigh monocytes, promoting H. pylori-associated gastritis. In summary, we identified a model in which TINAGL1 collectively ensures H. pylori persistence and promotes gastritis.

Differential Expression of α-Enolase in Clinical Gastric Tissues and Cultured Normal/Cancer Cells in Response to Helicobacter pylori Infection and cagA Transfection

Background and Objectives: The role of α-enolase (ENO1) in Helicobacter pylori-related gastric lesions might be a critical factor in the pathogenesis, but remains undefined. Materials and Methods: This study investigated the differential expression of α-enolase in clinical gastric specimens and cultured normal/cancer cells in response to H. pylori (cagA+) infection and cagA transfection using qPCR, Western blots and histochemical methods. Results: A total of 172 gastric specimens were collected from 142 patients, the former comprising chronic superficial gastritis (CSG), precancerous diseases (PCDs, including atrophic gastritis, intestinal metaplasia and dysplasia) and gastric cancer (GC) cases. Among the CSG and PCD cases, the H. pylori-infected group had significantly elevated ENO1 mRNA levels compared with the uninfected group. In the GC cases, differential ENO1 expressions were detected between the cancer tissues and the paracancerous tissues. Notably, significant difference was first detected between the GC cell (AGS) and the normal cell (GES-1) as a response of ENO1 to H. pylori infection and cagA transfection. Conclusions: This report reveals that ENO1 expression is associated with H. pylori infection, cagA transfection, co-culture duration, multiplicity of infection, gastric normal/cancerous cell lines and cellular differentiation. The findings may be crucial bases for further ascertaining H. pylori pathogenic mechanism and formulating novel therapeutic and diagnostic strategies.

Helicobacter pylori infection activates Wnt/β-catenin pathway to promote the occurrence of gastritis by upregulating ASCL1 and AQP5

Helicobacter pylori (H. pylori) infection is a well-recognized contributing factor to gastritis, but the underlying mechanisms remain to be established. It is interesting to note that AQP5 was predicted to be highly expressed in intestinal metaplasia (IM) based on H. pylori infection-related microarray data, and the transcription factor ASCL1 was bioinformatically predicted to associate with AQP5. Therefore, the purpose of this study is to evaluate the mechanistic significance of ASCL1 and AQP5 in H. pylori infection of gastritis. Gastritis mouse models were established by H. pylori infection, followed by determination of AQP5 and ASCL1 in gastric mucosa. Besides, the effects of AQP5 on H. pylori-induced gastritis were explored using AQP5^-/- mice. It was observed that H. pylori infection elevated expression of AQP5 and ASCL1 in gastric mucosa and gastric epithelial cells (GECs). H. pylori induced AQP5 expression by regulating ASCL1 and activated WNT/β-catenin signaling pathway in GECs. It was also found that AQP5 knockdown suppressed inflammatory response and apoptosis in H. pylori-infected mice. Moreover, H. pylori infection-elevated ASCL1 and AQP5 expression promoted apoptosis and inflammation in GECs. Taken together, the key findings of the present study demonstrate that H. pylori infection activated WNT/β-catenin signaling pathway by upregulating ASCL1/AQP5 to induce gastritis.

IL-9 contributes to the host immune response against Helicobacter pylori and helps limit infection in a Mouse Model

BACKGROUND

As an important mediator in lots of diseases, interleukin-9 (IL-9) can be a protector or pro-inflammatory cytokine depending on the complicated inflammatory milieu. Helicobacter pylori (H. pylori) induced a series of immunology cells and cytokines change, and however, the role of IL-9 in H. pylori infection remains unknown.

MATERIALS AND METHODS

Wild-type and IL-9 deficient mice were infected with H. pylori by means of intragastric administration. The colonization of H. pylori bacteria was measured by detecting specific 16s rDNA, and the intensity of inflammation was observed by H&E stain. The expression level of inflammation cytokines was determined by ELISA and quantitative real-time PCR.

RESULTS

IL-9 was increased due to the attack of H. pylori, besides deletion of Il9 aggravated the bacterial colonization and inflammation intensity. In addition, treatment of rmIL-9 reduced colonized H. pylori and inflammation level, indicated that IL-9 was a protector for the host against this bacterium. Followed by the H. pylori infection, interferon (IFN)-γ and interleukin (IL)-17A were up-regulated as expected, and nevertheless, the expression of IL-17A shared a positive relationship with IL-9 while IFN-γ negative associated with IL-9. Moreover, we also proved that Treg cells were not involved in the protective effect of IL-9, and meanwhile, CD4⁺ CD25^- T cells secreted more IFN-γ and less IL-17A in vitro due to the deletion of Il9.

CONCLUSIONS

IL-9 plays a protective role against H. pylori and the protection associated with cytokines change including IFN-γ and IL-17A.

Parabacteroides produces acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration

BACKGROUND

The endoglycosidase heparanase which degrades heparan sulfate proteoglycans, exerts a pro-inflammatory mediator in various inflammatory disorders. However, the function and underlying mechanism of heparanase in acute pancreatitis remain poorly understood. Here, we investigated the interplay between heparanase and the gut microbiota in the development of acute pancreatitis.

METHODS

Acute pancreatitis was induced in wild-type and heparanase-transgenic mice by administration of caerulein. The differences in gut microbiota were analyzed by 16S ribosomal RNA sequencing. Antibiotic cocktail experiment, fecal microbiota transplantation, and cohousing experiments were used to assess the role of gut microbiota.

RESULTS

As compared with wild-type mice, acute pancreatitis was exacerbated in heparanase-transgenic mice. Moreover, the gut microbiota differed between heparanase-transgenic and wild-type mice. Heparanase exacerbated acute pancreatitis in a gut microbiota-dependent manner. Specially, the commensal Parabacteroides contributed most to distinguish the differences between wild-type and heparanase-transgenic mice. Administration of Parabacteroides alleviated acute pancreatitis in wild-type and heparanase-transgenic mice. In addition, Parabacteroides produced acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration.

CONCLUSIONS

The gut-pancreas axis played an important role in the development of acute pancreatitis and the acetate produced by Parabacteroides may be beneficial for acute pancreatitis treatment. Video abstract.

A sensitive electrochemical DNA sensor for detecting Helicobacter pylori based on accordion-like Ti3C2Tx: a simple strategy

A novel electrochemical DNA sensor was designed to detect Helicobacter pylori based on accordion-like Ti₃C₂T_x. Here the multilayer Ti₃C₂T_x obtained by DMSO delamination was used to modify the glass carbon electrode, with a large specific surface area and excellent conductivity. Au nanoparticles were supported on the modified electrode and worked as an effective carrier to fix the capture probe (cpDNA) with sulfhydryl group through the firm binding of Au-S bond. Such an accordion-like Ti₃C₂T_x structure provides an ultrahigh electroactive surface area and ample binding sites for accommodating Au nanoparticles, which is advantageous for the signal amplification during the detection. And further, the sandwich structure formed by hybridizing cpDNA with target DNA sequence (tDNA) and rpDNA (rpDNA is a strand of DNA that can be base-paired with the tested tDNA) increases greatly the current signal and enhances the sensitivity of the electrochemical DNA sensor. Under optimal conditions, the developed electrochemical DNA sensor showed a wide linear range from 10^-11 to 10^-14 M and a low detection limit of 1.6 × 10^-16 M and exhibited good sensitivity, reproducibility, and stability. A novel electrochemical DNA sensor with simple sandwich structure was designed to detect H. pylori based on accordion-like Ti₃C₂T_x.

Helicobacter pylori-Induced Rev-erbα Fosters Gastric Bacteria Colonization by Impairing Host Innate and Adaptive Defense

BACKGROUND & AIMS

Rev-erbα represents a powerful transcriptional repressor involved in immunity. However, the regulation, function, and clinical relevance of Rev-erbα in Helicobacter pylori infection are presently unknown.

METHODS

Rev-erbα was examined in gastric samples from H pylori-infected patients and mice. Gastric epithelial cells (GECs) were isolated and infected with H pylori for Rev-erbα regulation assays. Gastric tissues from Rev-erbα^-/- and wild-type (littermate control) mice or these mice adoptively transferred with CD4⁺ T cells from IFN-γ^-/- and wild-type mice, bone marrow chimera mice and mice with in vivo pharmacological activation or inhibition of Rev-erbα were examined for bacteria colonization. GECs, CD45⁺CD11c^-Ly6G^-CD11b⁺CD68^- myeloid cells and CD4⁺ T cells were isolated, stimulated and/or cultured for Rev-erbα function assays.

RESULTS

Rev-erbα was increased in gastric mucosa of H pylori-infected patients and mice. H pylori induced GECs to express Rev-erbα via the phosphorylated cagA that activated ERK signaling pathway to mediate NF-κB directly binding to Rev-erbα promoter, which resulted in increased bacteria colonization within gastric mucosa. Mechanistically, Rev-erbα in GECs not only directly suppressed Reg3b and β-defensin-1 expression, which resulted in impaired bactericidal effects against H pylori of these antibacterial proteins in vitro and in vivo; but also directly inhibited chemokine CCL21 expression, which led to decreased gastric influx of CD45⁺CD11c^-Ly6G^-CD11b⁺CD68^- myeloid cells by CCL21-CCR7-dependent migration and, as a direct consequence, reduced bacterial clearing capacity of H pylori-specific Th1 cell response.

CONCLUSIONS

Overall, this study identifies a model involving Rev-erbα, which collectively ensures gastric bacterial persistence by suppressing host gene expression required for local innate and adaptive defense against H pylori.

Helicobacter pylori promote inflammation and host defense through the cagA-dependent activation of mTORC1

Mechanistic target of rapamycin complex 1 (mTORC1) functions as regulating different cellular processes, including cell growth, proliferation, motility, survival, metabolism, autophagy, and protein transcription. Recently, it also found to be associated with many infections and inflammatory diseases, playing complex roles in pathogens growth and inflammation regulation. However, the regulation mechanism of mTORC1 in gastric epithelial cells and its role in Helicobacter pylori (H. pylori) infection and related gastritis remain unclear. Here, we identified that the phosphorylation of mechanistic target of rapamycin (mTOR) and the expression of DEP domain-containing mTOR-interacting protein (DEPTOR) was increased in gastric mucosa of H. pylori-infected patients and mice, as well as in H. pylori-infected gastric epithelial cells, which were largely depended on H. pylori cagA. The expression of DEPTOR was regulated via mTORC1, but, in turn, inhibited mTORC1. Knockdown mTOR significantly decreased expression and secretion of cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6, chemokines CCL7 and CXCL16, and antimicrobial peptide LL37 in vitro, while knockdown DEPTOR had the opposite effect. Similar observations were made using mTOR knockout (KO) mice in vivo, moreover. The gastric inflammation was attenuated, while the bacterial burden was increased in mTOR KO mice during H. pylori infection. These findings supported H. pylori promote gastritis and inhibit bacterial colonization through the cagA-dependent activation of mTORC1.

Diagnostic reliability of nested PCR depends on the primer design and threshold abundance of Helicobacter pylori in biopsy, stool, and saliva samples

BACKGROUND

The aim of this work was to find a reliable nested PCR for the detection of Helicobacter pylori in biopsy, stool, and saliva specimens.

MATERIALS AND METHODS

Novel nested PCR was elaborated and validated on 81 clinical biopsy, stool, and saliva samples from the same individual and compared to available H pylori assays: histology, rapid urease test (RUT), stool antigen test (SAT), ¹³ C-urea breath test (UBT).

RESULTS

The efficiency and selectivity of 17 published nested polymerase chain reactions (PCR) available for Helicobacter pylori detection were re-evaluated. Most of them had serious limitations and mistakes in primer design. Hence, we elaborated a nested PCR for the unambiguous identification of H pylori in biopsy, stool, and saliva, using primers targeted to variable regions of the 16S ribosomal RNA (rRNA) gene. Moreover, we determined the detection limit by adding a known number of cells. This number was as low as 0.5 cells in a PCR vial, but due to the DNA isolation procedures, it required 1-5 × 10³ cells/g or ml of specimen. The sensitivity for nested PCR from stomach biopsies was on the same scale as ¹³ C-UBT (93.8%), but it was much lower in amplifications from stool (31.3%). Sequencing of all obtained PCR products exclusively confirmed H pylori-specific DNA sequences.

CONCLUSIONS

Elaborated nested PCR assay can serve as an auxiliary method for controversial samples (patients with bleeding or taking proton-pump inhibitor) in laboratories with basic equipment. The sensitivity and specificity for the amplification from gastric biopsies was almost like ¹³ C-UBT. Despite the good sensitivity, the threshold occurrence and the ability to survive in the oral cavity aside from and independent of the stomach is the reason why H pylori DNA cannot be reliably detected in saliva, stool, and some biopsy samples.

Helicobacter pylori-induced adrenomedullin modulates IFN-γ-producing T-cell responses and contributes to gastritis

Adrenomedullin (ADM) is a multifunctional peptide that is expressed by many surface epithelial cells, but its relevance to Helicobacter pylori (H. pylori)-induced gastritis is unknown. Here, we found that gastric ADM expression was elevated in gastric mucosa of H. pylori-infected patients and mice. In H. pylori-infected human gastric mucosa, ADM expression was positively correlated with the degree of gastritis; accordingly, blockade of ADM resulted in decreased inflammation within the gastric mucosa of H. pylori-infected mice. During H. pylori infection, ADM production was promoted via PI3K–AKT signaling pathway activation by gastric epithelial cells in a cagA-dependent manner, and resulted in increased inflammation within the gastric mucosa. This inflammation was characterized by the increased IFN-γ-producing T cells, whose differentiation was induced via the phosphorylation of AKT and STAT3 by ADM derived from gastric epithelial cells. ADM also induced macrophages to produce IL-12, which promoted the IFN-γ-producing T-cell responses, thereby contributing to the development of H. pylori-associated gastritis. Accordingly, blockade of IFN-γ or knockout of IFN-γ decreased inflammation within the gastric mucosa of H. pylori-infected mice. This study identifies a novel regulatory network involving H. pylori, gastric epithelial cells, ADM, macrophages, T cells, and IFN-γ, which collectively exert a pro-inflammatory effect within the gastric microenvironment.

Cardiac Ameliorative Effect of Moringa oleifera Leaf Extract in High-Fat Diet-Induced Obesity in Rat Model

The consumption of a high-fat diet is linked to the development of obesity and considered a risk factor for cardiovascular diseases. The aim of this study was to evaluate the effect of the methanolic extract of Moringa oleifera leaves (MEML) on the high-fat diet- (HFD-) induced obesity and cardiac damage in rats. MEML, at a dose of 200 mg/kg/bw and 400 mg/kg/bw, was orally administrated to obese rats for 12 weeks. M. oleifera leaves were proved to be rich in nutrients and minerals. Diversity of phenolic compounds in MEML was evidenced via LC-ESI-MS analysis. The chronic administration of HFD in rats led to an increase in the body weight gain, total cholesterol, and triglycerides and reduction in the HDL-C levels. The obtained results indicated a significant increase (p < 0.05) in the cardiac marker enzyme level in obese rats. A significant decrease (p < 0.05) in the levels of cardiac catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities was accompanied with an increase of malondialdehyde (MDA) level in the high-fat diet group when compared to those of the control. The treatment with the MEML alleviated abnormalities in the serum biochemical parameters, balanced the antioxidant status, and reestablished the normal histological structure of the heart especially in the case of the higher concentration. Moringa oleifera leaves may be a promising candidate in the management of obesity and its related complications such as heart problems.

The bovine epimural microbiota displays compositional and structural heterogeneity across different ruminal locations

Dairy cattle are globally important agricultural animals. Central to their biology is the rumen, which houses an essential microbial community, or microbiome, important for providing nutrition from otherwise host-inaccessible dietary components. The rumen environment is noted for its substantial spatial heterogeneity, as illustrated by the stratification into ruminal solid and liquid phases. A third microbiota found directly attached to the ruminal epithelium (the epimural microbiota) also exists but is less well understood because of challenges in sampling the ruminal epithelium. As a result, our understanding of the epimural microbiota is based on analyses of cannulated animals sampled at a single location-the ventral sac-and does not account for other ruminal locations, which may have importance for overall rumen function. To address this knowledge gap, we hypothesize that the epimural microbiota at different ruminal locations differs due to known morphological, physiological, and functional differences across the geographic spread of the rumen epithelium. Here, we characterized bacterial epimural communities at different sites within 8 lactating Holstein dairy cows using 16S rRNA gene sequencing. Four different sites were sampled via rumen tissue biopsy: cranial sac (CS), ventral sac (VS), caudodorsal blind sac (CDBS), and caudoventral blind sac (CVBS). We found that locations differed in both epimural bacterial community structure and composition, with the CDBS community displaying the greatest diversity. Across all sampling sites, epimural bacterial communities were dominated by members of the phyla Bacteroidetes, Firmicutes, and Proteobacteria. Bacteria within Prevotellaceae, Butyrivibrio, Campylobacter, Mogibacterium, and Desulfobulbus all showed high relative sequence abundance and differential distributions according to sample location. There appears to be a core epimural microbiota present across all locations in all cows, although relative abundance was highly variable. The difference in relative abundance in epimural microbial communities, perhaps influenced by host physiology and the diversity within rumen contents, likely has important consequences for nutrition acquisition and general health. To the best of our knowledge, this work represents the first characterization of the ruminal epimural microbiota across different epithelial locations for any bovine ruminant.

Upexpression of BHLHE40 in gastric epithelial cells increases CXCL12 production through interaction with p-STAT3 in Helicobacter pylori-associated gastritis

BHLHE40, a member of the basic helix-loop-helix transcription factor family, has been reported to play an important role in inflammatory diseases. However, the regulation and function of BHLHE40 in Helicobacter pylori (H pylori)-associated gastritis is unknown. We observed that gastric BHLHE40 was significantly elevated in patients and mice with H pylori infection. Then, we demonstrate that H pylori-infected GECs express BHLHE40 via cagA-ERK pathway. BHLHE40 translocates to cell nucleus, and then binds to cagA protein-activated p-STAT3 (Tyr705). The complex increases chemotactic factor CXCL12 expression (production). Release of CXCL12 from GECs fosters CD4⁺ T cell infiltration in the gastric mucosa. Our results identify the cagA-BHLHE40-CXCL12 axis that contributes to inflammatory response in gastric mucosa during H pylori infection.

Helicobacter pylori-induced matrix metallopeptidase-10 promotes gastric bacterial colonization and gastritis

The interaction between gastric epithelium and immune response plays key roles in H. pylori-associated pathology. We demonstrated a procolonization and proinflammation role of MMP-10 in H. pylori infection. MMP-10 is elevated in gastric mucosa and is produced by gastric epithelial cells synergistically induced by H. pylori and IL-22 via the ERK pathway. Human gastric MMP-10 was correlated with H. pylori colonization and the severity of gastritis, and mouse MMP-10 from non-BM-derived cells promoted bacteria colonization and inflammation. H. pylori colonization and inflammation were attenuated in IL-22-/-, MMP-10-/-, and IL-22-/-MMP-10-/- mice. MMP-10-associated inflammation is characterized by the influx of CD8+ T cells, whose migration is induced via MMP-10-CXCL16 axis by gastric epithelial cells. Under the influence of MMP-10, Reg3a, E-cadherin, and zonula occludens-1 proteins decrease, resulting in impaired host defense and increased H. pylori colonization. Our results suggest that MMP-10 facilitates H. pylori persistence and promotes gastritis.

Epitope-loaded nanoemulsion delivery system with ability of extending antigen release elicits potent Th1 response for intranasal vaccine against Helicobacter pylori

BACKGROUND

Helicobacter pylori (H. pylori) infection remains a global public health issue, especially in Asia. Due to the emergence of antibiotic-resistant strains and the complexity of H. pylori infection, conventional vaccination is the best way to control the disease. Our previous study found that the N-acetyl-neuroaminyllactose-binding hemagglutinin protein (HpaA) is an effective protective antigen for vaccination against H. pylori infection, and intranasal immunization with the immunodominant HpaA epitope peptide (HpaA 154-171, P22, MEGVLIPAGFIKVTILEP) in conjunction with a CpG adjuvant decreased bacterial colonization in H. pylori-infected mice. However, to confer more robust and effective protection against H. pylori infection, an optimized delivery system is needed to enhance the P22-specific memory T cell response.

RESULTS

In this study, an intranasal nanoemulsion (NE) delivery system offering high vaccine efficacy without obvious cytotoxicity was designed and produced. We found that this highly stable system significantly prolonged the nasal residence time and enhanced the cellular uptake of the epitope peptide, which powerfully boosted the specific Th1 responses of the NE-P22 vaccine, thus reducing bacterial colonization without CpG. Furthermore, the protection efficacy was further enhanced by combining the NE-P22 vaccine with CpG.

CONCLUSION

This epitope-loaded nanoemulsion delivery system was shown to extend antigen release and elicit potent Th1 response, it is an applicable delivery system for intranasal vaccine against H. pylori.

Helicobacter pylori-induced IL-33 modulates mast cell responses, benefits bacterial growth, and contributes to gastritis

Interleukin (IL)-induced inflammatory responses are critical for the pathogenesis of Helicobacter pylori (H. pylori)-induced gastritis. IL-33 represents a recently discovered proinflammatory cytokine involved in inflammatory diseases, but its relevance to H. pylori-induced gastritis is unknown. Here, we found that gastric IL-33 mRNA and protein expression were elevated in gastric mucosa of both patients and mice infected with H. pylori, which is positively correlated with bacterial load and the degree of gastritis. IL-33 production was promoted via extracellular regulated protein kinases (ERK) signaling pathway activation by gastric epithelial cells in a cagA-dependent manner during H. pylori infection, and resulted in increased inflammation and bacteria burden within the gastric mucosa. Gastric epithelial cell-derived IL-33 promoted TNF-α production from mast cells in vitro, and IL-33 increased TNF-α production in vivo. Increased TNF-α inhibited gastric epithelial cell proliferation, conducing to the progress of H. pylori-associated gastritis and bacteria colonization. This study defined a patent regulatory networks involving H. pylori, gastric epithelial cell, IL-33, mast cell, and TNF-α, which jointly play a pathological effect within the gastric circumstances. It may be a valuable strategy to restrain this IL-33-dependent pathway in the treatment of H. pylori-associated gastritis.

Efficacy and pharmacological mechanism of pronase-enhanced low-dose antibiotics for Helicobacter pylori eradication

This study examined the efficacy and pharmacological mechanism of pronase-assisted low-dose antibiotics for eradication of Helicobacter pylori. Mongolian gerbils infected with H. pylori received 7-day treatment (omeprazole, different concentrations of pronase, amoxicillin, and clarithromycin), and the efficacy was assessed using the eradication rate and the colonization of H. pylori. In Mongolian gerbils orally administered pronase, the thickness of the gastric mucous layer (GML) was examined using immunohistochemical and alcian blue staining, and the concentrations of amoxicillin in gastric tissue and serum were detected using high-performance liquid chromatography (HPLC). The eradication rates were 80.0% (12/15) in the high-pronase quadruple group (HPQG) and 86.7% (13/15) in the high-antibiotic group (HAG) (P = 1.000). The antibiotic dose in the HPQG was only 1/20 that in the HAG. Thirty minutes after oral treatment with pronase, the sticky protein of the GML was hydrolyzed, and the GML became thinner. Higher amoxicillin concentrations in both the gastric tissue and serum were observed in the pronase group than in the Am10 group. The concentration of amoxicillin in the Am10-plus-Pr108 group in gastric tissue was 3.8 times higher than in the Am10 group in 5 min. Together, these data suggest that pronase significantly reduced the dose of antibiotics used in H. pylori eradication. The pharmacological mechanism is likely pronase removal of the mucus layer, promoting chemical factor (i.e., gastric acid and pepsinogen) distribution and increasing the antibiotic concentrations in the deep GML, which acted on H. pylori collectively. Thus, pronase may enhance the level of antibiotics for eradication of H. pylori in the clinic.

Development of a novel DNA extraction method for identification and quantification of Mycobacterium avium subsp. paratuberculosis from tissue samples by real-time PCR

Mycobacterium avium subsp. paratuberculosis (Map) is the causative agent of Johne's disease in ruminants and possibly associated with human Crohn's disease. One impediment in furthering our understanding of this potential association has been the lack of an accurate method for detection of Map in affected tissues. Real time polymerase chain reaction (RT-PCR) methods have been reported to have different sensitivities in detection of Map. This is in part attributable to the difficulties of extracting Map DNA and removing PCR inhibitors from the clinical specimens. The maximum efficiency of RT-PCR can only be achieved by using high quality DNA samples. In this study, we present a novel pre-treatment method which significantly increases Map DNA recovery and decreases PCR inhibitors (p<0.05). When the pre-treatment method was combined with the DNeasy Blood and Tissue kit (Qiagen), PCR inhibition was not detected in any of three different RT-PCR methods tested in this study. The results obtained with the IS900 probe showed an excellent Kappa value (0.849) and a high correlation coefficient r (0.940) compared to the results of culture method. When used to examine unknown field samples (n=15), more positive tissues were identified with DNA extracts prepared with pre-treatment method than without (5 vs 3). This improved Map DNA extraction method from tissue samples will make RT-PCR a more powerful tool for a wide range of applications for Map identification and quantification.

Overcoming inhibition in real-time diagnostic PCR

PCR is an important and powerful tool in several fields, including clinical diagnostics, food analysis, and forensic analysis. In theory, PCR enables the detection of one single cell or DNA molecule. However, the presence of PCR inhibitors in the sample affects the amplification efficiency of PCR, thus lowering the detection limit, as well as the precision of sequence-specific nucleic acid quantification in real-time PCR. In order to overcome the problems caused by PCR inhibitors, all the steps leading up to DNA amplification must be optimized for the sample type in question. Sampling and sample treatment are key steps, but most of the methods currently in use were developed for conventional diagnostic methods and not for PCR. Therefore, there is a need for fast, simple, and robust sample preparation methods that take advantage of the accuracy of PCR. In addition, the thermostable DNA polymerases and buffer systems used in PCR are affected differently by inhibitors. During recent years, real-time PCR has developed considerably and is now widely used as a diagnostic tool. This technique has greatly improved the degree of automation and reduced the analysis time, but has also introduced a new set of PCR inhibitors, namely those affecting the fluorescence signal. The purpose of this chapter is to view the complexity of PCR inhibition from different angles, presenting both molecular explanations and practical ways of dealing with the problem. Although diagnostic PCR brings together scientists from different diagnostic fields, end-users have not fully exploited the potential of learning from each other. Here, we have collected knowledge from archeological analysis, clinical diagnostics, environmental analysis, food analysis, and forensic analysis. The concept of integrating sampling, sample treatment, and the chemistry of PCR, i.e., pre-PCR processing, will be addressed as a general approach to overcoming real-time PCR inhibition and producing samples optimal for PCR analysis.

Cathelicidin protects against Helicobacter pylori colonization and the associated gastritis in mice

Cathelicidin, an antimicrobial peptide of the innate immune system, has been shown to modulate microbial growth, wound healing and inflammation. However, whether cathelicidin controls Helicobacter pylori infection in vivo remains unexplored. This study sought to elucidate the role of endogenous and exogenous mouse cathelicidin (CRAMP) in the protection against H. pylori infection and the associated gastritis in mice. Results showed that genetic ablation of CRAMP in mice significantly increased the susceptibility of H. pylori colonization and the associated gastritis as compared with the wild-type control. Furthermore, replenishment with exogenous CRAMP, delivered via a bioengineered CRAMP-secreting strain of Lactococcus lactis, reduced H. pylori density in the stomach as well as the associated inflammatory cell infiltration and cytokine production. Collectively, these findings indicate that cathelicidin protects against H. pylori infection and its associated gastritis in vivo. Our study also demonstrates the feasibility of using the transformed food-grade bacteria to deliver cathelicidin, which may have potential clinical applications in the treatment of H. pylori infection in humans.

Systemic immunization with an epitope-based vaccine elicits a Th1-biased response and provides protection against Helicobacter pylori in mice

Vaccine-mediated Th1-biased CD4+ T cell responses have been shown to be crucial for protection against Helicobacter pylori (H. pylori). In this study, we investigated whether a vaccine composed of CD4+ T cell epitopes together with Th1 adjuvants could confer protection against H. pylori in a mouse model. We constructed an epitope-based vaccine, designated Epivac, which was composed of predicted immunodominant CD4+ T cell epitopes from H. pylori adhesin A (HpaA), urease B (UreB) and cytotoxin-associated gene A product (CagA). Together with four different Th1 adjuvants, Epivac was administered subcutaneously and the prophylactic potential was examined. Compared to non-immunized mice, immunization with Epivac alone or with a Th1 adjuvant significantly reduced H. pylori colonization, and better protection was observed when an adjuvant was used. Immunized mice exhibited a strong local and systemic Th1-biased immune response, which may contribute to the inhibition of H. pylori colonization. Though a significant specific antibody response was induced by the vaccine, no correlation was found between the intensity of the humoral response and the protective effect. Our results suggest that a vaccine containing CD4+ T cell epitopes is a promising candidate for protection against H. pylori infection.

Assessment of methods for detection of Helicobacter pylori in animal models

Helicobacter pylori (H. pylori) is a major risk factor for chronic gastritis and peptic ulcer and is closely related to the occurrence of gastric cancer and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Rational use of animal models is very helpful for the clinical and preclinical investigation of H. pylori. However, the methods for detection of H. pylori in animal models were less reported. Most of the reported methods require the animal to be executed, and those not requiring killing the animal were less developed. This review will introduce seven methods for detection of H. pylori in animal models. These methods can meet the requirements for appropriate and accurate detection of H. pylori in different investigation conditions.

Evaluation of antioxidant and antiulcerogenic activities of Opuntia ficus indica f. inermis flowers extract in rats

The Opuntia ficus indica f. inermis methanolic flowers extract (OMFE) was phytochemical studied, in vitro tested for their potential antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, linoleic acid peroxidation assays and in vivo evaluated for its ability to prevent ethanol-induced gastric ulcer in rats. The OMFE was rich in polysaccharide, phenolics and flavonoids contents and exhibited a moderate in vitro antioxidant activity when compared with (+)-catechin and ascorbic acid. Pre-treatment with OMFE at oral doses 250, 500 and 1000 mg/kg body weight was found to provide a dose-dependent protection against ethanol-induced gastric ulcer by averting the deep necrotic lesions of the gastric epithelium, by preserving normal antioxidant enzymes activities, by inhibiting the lipid peroxidation, the oxidation of protein and the DNA fragmentation in gastric mucosa. The antiulcerogenic activity of OMFE might be due to a possible synergistic antioxidant and antihistaminic-like effects.

Therapeutic efficacy of oral immunization with attenuated Salmonella typhimurium expressing Helicobacter pylori CagA, VacA and UreB fusion proteins in mice model

Therapeutic vaccination is a desirable alternative for controlling Helicobacter pylori (H. pylori) infection. In the present study, attenuated Salmonella vector vaccines were constructed that expressed fusion proteins complexed with H. pylori CagA, VacA and UreB in different arrangements, and their therapeutic efficacy was evaluated in H. pylori-infected mice. Oral therapeutic immunization with attenuated Salmonella, which expressed the fused protein CVU, significantly decreased H. pylori colonization in the stomach; protection was related to specific CD4(+) T cell Th1 type responses and serum IgG and mucosal sIgA antibody responses. These findings suggested that therapeutic efficacy was related to the arrangement of the fusion protein. It is possible that arrangement decides the expression of recombinant antigen in mice, and the latter results in different therapeutic efficacy. The attenuated Salmonella vector vaccine, which expressed the fused protein arrangement CVU, is superior to others, and could be a candidate vaccine against H. pylori.

Mycobacterium behavior in wastewater treatment plant, a bacterial model distinct from Escherichia coli and Enterococci

Mycobacteria are waterborne emerging pathogens causing infections in human. Mycobacteria have been previously isolated from wastewater and sludge, but their densities were not estimated due to cultural biases. In order to evaluate the impact of wastewater treatment processes on mycobacteria removal, we used a real time PCR method. First we compared six DNA extraction methods and second we used the more efficient DNA extraction procedure (i.e., enzymatic lysis combined with hexadecyltrimethylammonium bromide-NaCl procedure) in order to quantify Mycobacterium. With the aim to identify parameters that could serve as indicator of mycobacterial behavior, mycobacterial densities were measured in parallel to those of Escherichia coli and enterococci, and to concentrations of chemical parameters usually monitored in wastewater. Mycobacterium reached 5.5 × 10⁵ ± 3.9 × 10⁵ copies/L in the influent, but was not detected in the effluent after decantation and biofiltration. Most mycobacteria (98.6 ± 2.7%, i.e. 2.4 ± 0.7 log₁₀) were removed by the physical-chemical decantation, and the remaining mycobacteria were removed by biofiltration. In contrast, enterococci and E. coli were lightly removed by decantation step and mainly removed by biofiltration. Our results showed that Mycobacterium corresponds to a hydrophobic behavior linked to insoluble compound removal, whereas enterococci and E. coli refer to hydrophilic behaviors linked to soluble compound removals.

A comparison of methods for extracting DNA from Coxiella burnetii as measured by a duplex qPCR assay

AIMS

To determine the optimal DNA extraction method for the detection of Coxiella burnetii including the small-cell variant (SCV) by real-time PCR (qPCR) in clinical samples.

METHODS AND RESULTS

A duplex qPCR detecting two Coxiella burnetii gene targets (com1 and IS1111a genes) was developed. Each target in this PCR had a sensitivity of one copy number per reaction. DNA extraction methods were compared on spiked negative samples and included a silica column kit, a chloroform separation prior to a silica column method and a chloroform/phenol separation and DNA precipitation method.

CONCLUSIONS

The silica column extraction method was more efficient at recovering C. burnetii DNA, from large-cell and small-cell variants, than a chloroform or chloroform/phenol method. The silica column method was useful on spiked human samples including serum, buffy coat and bone marrow samples.

SIGNIFICANCE AND IMPACT OF STUDY

This study demonstrated that a simple column kit method is efficient to use for the detection of C. burnetii in clinical samples including the SCV.

Induction of a Th17 cell response by Helicobacter pylori Urease subunit B

Th17 cells represent a novel subset of CD4(+) T cells, which is associated with Helicobacter pylori infection. In the present study, we investigated the potential role of Urease subunit B (UreB) in the induction of Th17 cell response. Co-cultured splenic lymphocytes from H. pylori-infected mice with the recombinant UreB (rUreB) elevated IL-17 secretion and caused an increase in the number of Th17 cells. The expression of IL-6 and IL-23 p19 was significantly increased in rUreB-stimulated macrophages. Whole cell protein (WCP) of UreB-deficient strain (UreB(-) strain) induced less Th17 cell responses than that of wild-type strain. In addition, subcutaneous and intranasal immunization of rUreB elicited antigen-specific Th17 cell responses. Intranasal immunization of rUreB reduced H. pylori colonization in the stomach, which was closely related with the increased rUreB-specific Th17 cell responses. These results suggest that UreB is an important protein which is able to elicit Th17 cell responses against H. pylori both in vivo and in vitro.

Helicobacter pylori-induced Th17 responses modulate Th1 cell responses, benefit bacterial growth, and contribute to pathology in mice

CD4(+) T cell responses are critical for the pathogenesis of Helicobacter pylori infection. The present study evaluated the role of the Th17 subset in H. pylori infection. H. pylori infection induced significant expression of IL-17 and IFN-gamma in mouse gastric tissue. IL-23 and IL-12 were increased in the gastric tissue and in H. pylori-stimulated macrophages. Cell responses were examined by intracellular staining for IFN-gamma, IL-4, and IL-17. Mice infected with H. pylori developed a mixed Th17/Th1 response; Th17 responses preceded Th1 responses. Treatment of mice with an anti-IL-17 Ab but not a control Ab significantly reduced the H. pylori burden and inflammation in the stomach. H. pylori colonization and gastric inflammation were also lower in IL-17(-/-) mice. Furthermore, administration of recombinant adenovirus encoding mouse IL-17 increased both H. pylori load and inflammation. Further analysis showed that the Th1 cell responses to H. pylori were downregulated when IL-17 is deficient. These results together suggest that H. pylori infection induces a mixed Th17/Th1 cell response and the Th17/IL-17 pathway modulates Th1 cell responses and contributes to pathology.

Psychological stress enhances the colonization of the stomach by Helicobacter pylori in the BALB/c mouse

Helicobacter pylori infection is a risk factor for development of peptic ulcers, and psychological stress (PS) may have a role in the pathogenesis of this condition. However, no interaction between PS and H. pylori infection (HI) has been established in the development of peptic ulcer, because colonization by H. pylori is the first step in the infection of the gastric mucosa, we examined H. pylori colonization of the stomach in BALB/c mice after PS. The mice were subjected to PS in a communication box test, in which they observed other mice experiencing a physical stressor (electrical) before they were inoculated with H. pylori. We found that the H. pylori colonization in the stomach of psychologically stressed mice was significantly greater than in the control mice (P < 0.05), and histological examination showed that the gastric mucosal injury in the stressed mice was more extensive than in the control mice (P < 0.05). To explore the underlying mechanisms, we administered RU486 (a type II glucocorticoid (GC) receptor antagonist) to antagonize the effect of endogenous corticosterone: this treatment decreased colonization by H. pylori in the psychologically stressed mice. We conclude that HI of the stomach of BALB/c mice is enhanced by PS, and the effect may be mediated by GCs.

DNA extraction from bovine faeces: current status and future trends

There is an increasing interest in the detection and enumeration of micro-organisms pathogenic for human and present in bovine faeces. This interest is because pollution of the environment by animal faeces may affect the safety of food and of drinking or recreational water. Detection and quantification of microbial pathogens carried out using DNA extracted from the faecal matrix are affected by the quality and the quantity of the DNA extracts, which are critical factors that limit the accuracy and sensitivity of molecular studies. This review compares published methods on DNA extraction from bovine faeces, focusing on the extent to which the success of DNA amplification is affected by issues related to the faeces. Following a general discussion on the DNA extraction methods used for faeces, we focus particularly on issues related to the faecal environment itself. The objective is to identify information that can be used to improve the sensitivity of those PCR methods used after direct DNA extraction.

Quantification of diatom and dinoflagellate biomasses in coastal marine seawater samples by real-time PCR

Two real-time PCR assays targeting the small-subunit (SSU) ribosomal DNA (rDNA) were designed to assess the proportional biomass of diatoms and dinoflagellates in marine coastal water. The reverse primer for the diatom assay was designed to be class specific, and the dinoflagellate-specific reverse primer was obtained from the literature. For both targets, we used universal eukaryotic SSU rDNA forward primers. Specificity was confirmed by using a BLAST search and by amplification of cultures of various phytoplankton taxa. Reaction conditions were optimized for each primer set with linearized plasmids from cloned SSU rDNA fragments. The number of SSU rDNA copies per cell was estimated for six species of diatoms and nine species of dinoflagellates; these were significantly correlated to the biovolumes of the cells. Nineteen field samples were collected along the Swedish west coast and subjected to the two real-time PCR assays. The linear regression of the proportion of SSU rDNA copies of dinoflagellate and diatom origin versus the proportion of dinoflagellate and diatom biovolumes or biomass per liter was significant. For diatoms, linear regression of the number of SSU rDNA copies versus biovolume or biomass per liter was significant, but no such significant correlation was detected in the field samples for dinoflagellates. The method described will be useful for estimating the proportion of dinoflagellate versus diatom biovolume or biomass and the absolute diatom biovolume or biomass in various aquatic disciplines.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Novel methods of quantitative real-time PCR data analysis in a murine Helicobacter pylori vaccine model

Monitoring of Helicobacter pylori in the stomach is important to assess the efficacy of new vaccines against the pathogen. To realise the full potential of quantitative real-time PCR (q-PCR), this technology has to offer accurate and easy models of post-PCR data analysis. In this work, we used a variety of absolute and relative approaches of q-PCR data analysis to monitor the H. pylori infection in the stomach of immunized mice. Relative quantification was performed with Ct-based methods, with the DART program, and with two methods based on the mathematical analysis of raw fluorescence kinetics, the LinReg program and the Sigmoidal Curve Fitting Method. The different calculation methods were validated in mice immunized with cell lysates of Lactococcus lactis expressing the H. pylori urease subunit B in combination with cholera toxin. The H. pylori load was found to be reduced in immunized mice by a factor of 50-144, depending on the calculation method employed. We found that relative quantification using DART, LinReg and Sigmoidal Curve Fitting methods generated similar results (infection ratios of 54-58) with absolute quantification results (54-65). Results were very different to those using relative quantification Ct-based methods without a correction for PCR efficiency (ratio of 92-144) and with results based on conventional culture method (ratio of 34). Overall, this study demonstrates that q-PCR associated with a relative quantification analysis is a powerful tool for the monitoring of microorganisms in tissue. It could be used as an alternative to standard curve approach especially for the investigation of microbial load in vaccine models.

Real-time polymerase chain reaction quantification of canine DNA

The accurate quantification of target DNA is an important step in the short tandem repeat analysis of forensic biological samples. By utilizing quantification data to control the amount of template DNA in the polymerase chain reaction (PCR), forensic scientists can optimize testing and minimize the consumption of limited samples. The ability to identify and quantify target DNA in mixed-species samples is crucial when it may be overwhelmed by nontarget DNA, as in cases of dog attack. We evaluated two quantitative real-time PCR assays for dynamic range, species specificity, and inhibition by humic acid. While both assays proved to be highly sensitive and discriminating, the Melanocortin-1 Receptor (MC1R) gene Taqman assay had the advantages of a shorter run time, greater efficiency, and safer reagents. In its application to forensic casework, the MC1R assay has been advantageous for quantifying dog DNA in a variety of mixed-species samples and facilitating the successful profiling of individual dogs.

Mucosal immunization with a urease B DNA vaccine induces innate and cellular immune responses against Helicobacter pylori

BACKGROUND

Helicobacter pylori is recognized as a major risk factor for recurrent gastroduodenal inflammatory diseases and gastric adenocarcinoma. The high prevalence of H. pylori infection worldwide, the risks of side-effects from antibiotic therapy, and increasing resistance to antibiotics are the main primers for the development of improved H. pylori vaccines. The antigenic potential of its urease enzyme, a critical virulence factor required for colonization of the gastric mucosa, has been demonstrated in animal and human studies. An important but controversial issue in H. pylori vaccine studies is the type of immune response required to control infection. A new approach in H. pylori vaccinology is the administration of DNA vaccines, which has included heat-shock protein and catalase DNA vaccines.

MATERIALS AND METHODS

The H. pylori urease subunit B construct or vector alone was administered to mice via the intranasal route. Spleens and stomachs were examined on day 0 and weeks 3, 6, and 12 after immunization. Proliferation of spleen cells was assessed using the carboxyfluorescein diacetate succinimidyl ester-based flow cytometry assay and cytokine secretion from cultured spleen cells was detected by ELISA, after stimulation with the urease subunit B recombinant antigen. Total RNA was isolated from stomach and spleen tissue and the expression of beta-defensin and cytokine genes was monitored by reverse transcription followed by polymerase chain reaction (RT-PCR). Immunized mice were challenged with H. pylori and bacterial DNA quantified by TaqMan PCR.

RESULTS

The urease B subunit DNA vaccine increased INF-gamma secretion and splenocyte proliferation without inducing adverse effects in the spleen. Increase in gastric beta-defensin 1 and marked induction in local IL-10 : IFN-gamma ratio up to 12 weeks post-immunization suggest a potential role for local innate immune responses in protection at the site of infection. Although significant bacterial reduction in the stomachs of urease B subunit DNA-immunized mice was observed, intermediate reduction was also noted in the vector group. Increased defensin expression and adjuvant effects of the cytosine preceding guanosine motifs may contribute to this phenomenon. Our data confirm that cytosine preceding guanosine motifs, even without coadministration with antigen, can reduce extracellular bacterial load.

CONCLUSIONS

In this study, a DNA construct encoding the urease B subunit was assessed for its immune profile and its ability to reduce bacterial colonization in the murine stomach. Our studies suggest that local innate immune responses may play a greater role than previously supposed in limiting H. pylori colonization in the gastric mucosa.