Helicobacter pylori regulates stomach diseases by activating cell pathways and DNA methylation of host cells.

One of the most prevalent malignant tumors of the digestive tract is gastric cancer (GC). Age, high salt intake, Helicobacter pylori (H. pylori) infection, and a diet deficient in fruits and vegetables are risk factors for the illness. A significant risk factor for gastric cancer is infection with H. pylori. Infecting gastric epithelial cells with virulence agents secreted by H. pylori can cause methylation of tumor genes or carcinogenic signaling pathways to be activated. Regulate downstream genes' aberrant expression, albeit the precise mechanism by which this happens is unclear. Oncogene, oncosuppressor, and other gene modifications, as well as a number of different gene change types, are all directly associated to the carcinogenesis of gastric cancer. In this review, we describe comprehensive H. pylori and its virulence factors, as well as the activation of the NF-κB, MAPK, JAK/STAT signaling pathways, and DNA methylation following infection with host cells via virulence factors, resulting in abnormal gene expression. As a result, host-related proteins are regulated, and gastric cancer progression is influenced. This review provides insight into the H. pylori infection, summarizes a series of relevant papers, discusses the complex signaling pathways underlying molecular mechanisms, and proposes new approach to immunotherapy of this important disease.

Helicobacter pylori with the Intact dupA Cluster is more Virulent than the Strains with the Incomplete dupA Cluster.

The duodenal ulcer promoting gene (dupA), located in the plasticity region of Helicobacter pylori (H. pylori), is predicted to form a type IV secretory system (T4SS) with vir genes around dupA. In the study, we investigated the association between the dupA cluster status and the virulence of H. pylori in a littoral region of Northeast China. Two hundred and sixty-two H. pylori strains isolated from the chronic gastritis were examined to evaluate the dupA cluster status, cag PAI genes and vacA genotype using PCR and Western blot. Histopathologic evaluations of biopsy specimens were performed to analysis the association between the dupA cluster and the inflammatory response. IL-8 productions in gastric mucosa and from GES-1 cells co-cultured with H. pylori were measured, respectively, to analysis the association between the dupA cluster status and IL-8 production. We found that gastric mucosal inflammatory cell infiltration was significantly higher in patients with dupA-positive H. pylori, including H. pylori with complete dupA cluster (2.71 ± 0.79) and incomplete dupA cluster (2.09 ± 0.61) than in patients with dupA-negative strain (1.73 ± 0.60, p < 0.01), whereas no significant difference in the gastric mucosal atrophy was found according to the status of dupA cluster. Gastric mucosal IL-8 levels were higher in the complete dupA cluster group than in other groups (p < 0.01), and IL-8 production from GES-1 cells was also significantly higher in strains with a complete dupA cluster (1527.9 ± 180.0 pg/ml) than in those with an incomplete dupA cluster (1229.4 ± 75.3 pg/ml, p < 0.01) or those with dupA negative (1201.9 ± 92.3 pg/ml, p < 0.01). In conclusion, the complete dupA cluster in H. pylori is associated with inflammatory cell infiltration and IL-8 secretion, and H. pylori strain with a complete dupA cluster seems to be more virulent than other strains with the incomplete dupA cluster or dupA negative.

Intact long-type DupA protein in Helicobacter pylori is an ATPase involved in multifunctional biological activities.

The function of intact long-type DupA protein in Helicobacter pylori was analyzed using immunoblotting and molecular biology techniques in the study. After cloning, expression and purification, ATPase activity of DupA protein was detected. Antibody was produced for localization and interaction proteins analysis. The dupA-deleted mutant was generated for adhesion and CagA protein translocation assay, susceptibility to different pH, IL-8 secretion assay, cytotoxicity to MKN-45 cells and proteins-involved apoptosis analysis. DupA protein exhibited an ATPase activity (129.5±17.8 U/mgprot) and located in bacterial membrane, while it did not involve the adhesion and CagA protein delivery of H. pylori. DupA protein involved the urease secretion as the interaction proteins. The wild type strain had a stronger growth in low pH than the dupA-deleted mutant (p < 0.001). IL-8 productions from GES-1 cells infected with the wild type strain were significantly higher than from those with the mutant (p < 0.001). The amounts of vital MKN-45 cells were decreased and the numbers of apoptotic cells were increased with the wild type strain, compared to those with the mutant after 12 h (p < 0.05). The increase of cleaved Caspase-3 and Bax was significantly higher and the decrease of Bcl-2 was more obvious in MKN-45 cells exposed to the wild type strain than that exposed to the mutant after 6 h. We demonstrate that intact long-type DupA protein located in membrane as ATPase is a true virulence factor associated with duodenal ulcer development involving the IL-8 induction and urease secretion, while it inhibits gastric cancer cell growth in vitro by activating the mitochondria-mediated apoptotic pathway.

Does ceruloplasmin differential express in the brain of Ts65Dn: a mouse mode of Down syndrome?

To investigate the expression of CP in Down syndrome (DS) mouse model, we especially observed the changes in neuronal CP. We systematically analyzed the level of CP in Ts65Dn mouse, including serum CP concentration and enzymatic activity, CP mRNA in brain, the expression of CP protein in brain. The applied technologies were ELISA, chemical colorimetry, RT-PCR, immunohistochemistry. Compared with the control group, there were no differences of significance in the concentration, enzymatic activity and unit activity of serum ceruloplasmin. By RT-PCR, we also found there were no significant differences in the level of CP mRNA. The expression of CP was positive in the endochylema of neuronal cells of both the groups, and there were no significant difference between the two groups. Meanwhile, there were no differences in four regions of the brain (cerebral cortex, hippocampus, thalamus and cerebella). Although the neurotoxic effects of CP related to some neurodegenerative diseases, but whether it does so in DS remains to be determined.

Distribution of Helicobacter pylori virulence markers in patients with gastroduodenal diseases in a region at high risk of gastric cancer.

ABSTRACT BACKGROUND: Helicobacter pylori (H. pylori) is a major human pathogen that is responsible for various gastroduodenal diseases. We investigated the prevalence of H. pylori virulence markers in a region at high risk of gastric cancer. METHODS: One hundred and sixteen H. pylori strains were isolated from patients with gastroduodenal diseases. cagA, the cagA 3' variable region, cagPAI genes, vacA, and dupA genotypes were determined by PCR, and some amplicons of the cagA 3' variable region, cagPAI genes and dupA were sequenced. RESULTS: cagA was detected in all strains. The cagA 3' variable region of 85 strains (73.3%) was amplified, and the sequences of 24 strains were obtained including 22 strains possessing the East Asian-type. The partial cagPAI presented at a higher frequency in chronic gastritis (44.4%) than that of the severe clinical outcomes (9.7%, p < 0.001). The most prevalent vacA genotypes were s1a/m2 (48.3%) and s1c/m2 (13.8%). Thirty-six strains (31.0%) possessed dupA and sequencing of dupA revealed an ORF of 2449-bp. The prevalence of dupA was significantly higher in strains from patients with the severe clinical outcomes (40.3%) than that from chronic gastritis (20.4%, p = 0.02). CONCLUSION: The high rate of East Asian-type cagA, intact cagPAI, virulent vacA genotypes, and the intact long-type dupA may underlie the high risk of gastric cancer in the region.

Preliminary proteomic-based identification of a novel protein for Down's syndrome in maternal serum.

Prenatal screening for Down's syndrome (DS) is in need of improvement. As a powerful platform, proteomics techniques could also be used for identification of new biomarkers for DS screening. In this case-control proteome study, pregnant women were diagnosed prenatally by karyotype analysis from amniotic fluid (AF). Maternal serum samples were collected from six pregnancies with fetuses affected by DS and six pregnancies with normal fetuses. First, we used two-dimensional electrophoresis and mass spectrometry to identify the different levels of expression of proteins in maternal serum between the DS and control groups in the second trimester. Second, we used bioinformatics to analyze the proteins by DAVID. Then, the interesting candidates were further tested by enzyme-linked immunosorbent assay (ELISA). Twenty-nine proteins were successfully identified in maternal serum obtained from pregnancies with fetuses affected by DS. The top five proteins up-regulated were serotransferrin (TF), alpha-1b-glycoprotein (A1BG), desmin (DES), alpha-1-antitrypsin (SERPINA1) and ceruloplasmin (CP), while serum amyloid P-component (APCS) was the most down-regulated protein. These 29 proteins were categorized based on binding, catalytic activity and enzyme regulator activity. The biological roles were involved in biological regulation, metabolic processes, cellular processes and response to a stimulus. Based on ELISA, the median concentrations of CP and complement factor B (CFB) were 332.3 and 412.3 ng/mL, respectively. The concentrations of CP and CFB were significantly higher in the DS group than in the control group (P < 0.05). In conclusion, proteomic approaches offer the possibility of further improving the performance of DS screening and our identification of up- and down-regulated proteins may lead to new candidates for DS screening.

Bioinformatics characterization of differential proteins in serum of mothers carrying Down syndrome fetuses: combining bioinformatics and ELISA.

INTRODUCTION: Characterization of novel proteins in maternal serum derived from mothers carrying Down syndrome (DS) fetuses. MATERIAL AND METHODS: Based on last comparative proteomic analysis, five significant differences of expressed proteins in serum from four groups have been confirmed by ELISA. DAVID and GeneGo MetaCore were used to bioinformatically analyze candidate protein markers. RESULTS: The serum levels of ceruloplasmin (CP) and complement factor B (CFB) were significantly increased in mother carried DS fetuses (346.5 ng/ml and 466.8 ng/ml vs. 248.6 ng/ml and 293.5 ng/ml, p< 0.05). Twenty-nine proteins were mainly categorized into binding, catalytic activity and enzyme regulator activity proteins, and their biological roles were involved in biological regulation, metabolic processes, cellular processes, and response to stimuli. The immune response alternative complement pathway was the most significant GeneGo Pathway related to DS. CONCLUSIONS: These 29 proteins have relations with the development of Down syndrome, especially CP and CFB play more important roles.

Antibody specific to thioredoxin reductase as a new biomarker for serodiagnosis of invasive aspergillosis in non-neutropenic patients.

BACKGROUND: Invasive aspergillosis (IA) is an important cause of mortality in critically ill patients, but the diagnosis is difficult as clinical and radiological signs are neither sensitive nor specific. Serum galactomannan (GM) is a useful marker for IA, but exhibits low sensitivity in non-neutropenic patients. In our previous work, strong antibody reactivity to thioredoxin reductase of Aspergillus fumigatus was found in non-neutropenic IA patients. METHODS AND RESULTS: Using recombinant thioredoxin reductase GliT (TR), an antigenic protein secreted by A. fumigatus, as the coating antigen, an enzyme-linked immunosorbent assay (ELISA) for detecting anti-TR antibodies was developed. The antibody response to TR in IA animal models and 42 non-neutropenic patients with culture- and/or histology-documented IA was investigated. The results showed that anti-TR antibody was detectable in rabbit serum 7-9 days after exposure to the fungus. The sensitivity and specificity of the anti-TR antibody assay in patients were 80.9% and 96%, respectively, while the sensitivity of GM in this group of patients was only 52.3%. The specificity of the assay was confirmed by testing the sera from patients infected with other pathogenic fungal species and bacteria.

Study on norcantharidin-induced apoptosis in SMMC-7721 cells through mitochondrial pathways.

OBJECTIVE: To investigate the mechanism of norcantharidin (NCTD)-induced SMMC-7721 hepatoma cell apoptosis. METHODS: SMMC-7721 cell growth inhibition was measured by the MTT method. Apoptosis was detected by Annexin V/propidium iodide staining. The mitochondrial membrane potential was measured by flow cytometry. Western blot analysis was used to evaluate the level of cytochrome c, caspase-3, AIF, Bcl-2 and Bax expression. RESULTS: NCTD inhibited SMMC-7721 cell growth in a time- and dose-dependent manner. The cells treated with NCTD showed the loss of mitochondrial membrane potential. The activities of caspase-3, cytochrome c, AIF, and Bax were up-regulated after NCTD treatment at different doses. The expression of Bcl-2 was decreased after treatment with NCTD. CONCLUSIONS: NCTD could induce SMMC-7721 cell apoptosis. The activation of the mitochondrial pathway was involved in the process of NCTD-induced SMMC-7721 cell apoptosis.

[The type IV secretion system encoded by the cag PAI of Helicobacter pylori].

Helicobacter pylori is a human-specific gastric pathogen that colonizes over half the world's population. Infection with this bacterium is associated with a spectrum of gastric pathologies ranging from mild gastritis to peptic ulcers and gastric cancer. A strong predictor of severe disease outcome is infection with a bacterial strain harbouring the cag (cytotoxin associated gene) pathogenicity island (PAI), a 40 kb stretch of DNA that encodes homologues of several components of a type IV secretion system (TFSS). One gene within the cag PAI, cagA, has been shown to encode a substrate for the TFSS which is translocated into host cells, inducing the dephosphrylation of host cell proteins and leading to changes in the morphology or shape of AGS gastric epithelial cells. Furthermore, the TFSS is involved in the induction of proinflammatory cytokines. It appeears to play a key role in H. pylori pathogenesis. Very little is known about the H. pylori cag PAI-encoded TFSS, the expression of Cag proteins in H. pylori, and the functions of individual proteins encoded by the cag PAI. Only by exploring the mechanistic details of the interplay between H. pylori and eukaryotic cells can we endeavour to understand how these cellular interactions play out at the tissue and organismal level during the lifelong coexistence of bacterium and host.

[Study on molluscicidal effect of the extracts from sarcotesta of Ginkgo biloba].

OBJECTIVE: To observe the molluscicidal activity and the fish acute toxicity of the molluscicides extracted from Ginkgo biloba sarcotesta by benzinum (EGSB) (with major component of ginkgolic acid), arecoline (ARE) and their combination. METHODS: Oncomelania hupensis snails were immersed in different concentrations of dry powder sarcotesta of Ginkgo biloba (DPGB), extract of Ginkgo biloba sarcotesta by water (EGSW) and EGSB by WHO recommended method for molluscicide screening to observe the molluscicidal activity, and also the inhibiting effect on the snails' climbing-up as well as acute toxicity to Brachydanio rerio. Niclosamide was used as control. RESULTS: The three extractions from Ginkgo biloba all showed molluscicidal activity, with EGSB as the best. Its 24 h LC50 and LC90 were 0.65 mg/L and 5.50 mg/L, and the 48 h LC50 and LC90 were 0.07 mg/L and 0.85 mg/L, respectively. The combination of EGSB and ARE showed better effect than EGSB alone. Its 24 h LC50 and LC90 were 0.26 mg/L and 0.56 mg/L respectively, a sharp decrease by 60% and 90% compared to EGSB (P<0.05). Under the concentration of 2.50 mg/L of EGSB, the rate of snails' climbing-up was 10%, while under the concentration of 0.16 mg/L of the EGSB+ARE combination, the rate was 8%. The inhibition on the snails' climbing-up of the combination was stronger than EGSB. The fish survived for 24 h and 10th respectively at the concentration of 1 x LC90 and 2 x LC90 of EGSB. Under the concentration of 2 x LC90 of the combination, only 50% of the fish died and no fish died at the concentration of 1 x LC90. The toxicity of the combination was lower than EGSB alone. CONCLUSION: EGSB shows an adequate molluscicidal activity and it is worth of further investigation.

Type IV secretion system in Helicobacter pylori: a new insight into pathogenicity.

OBJECTIVE: To review the research progress on Type IV secretion system (T4SS) in Helicobacter pylori. DATA SOURCES: The data used in this review were identified by searching of PUBMED (1995 - 2007) online resources using the key terms 'Type IV secretion system' and 'Helicobacter pylori'. STUDY SELECTION: Mainly original articles and critical reviews written by major pioneer investigators of this field were selected. RESULTS: The research progress on T4SS in Helicobacter pylori was summarized. The structure and function was discussed. CONCLUSIONS: T4SS is not only involved in toxin secretion and injection of virulence factors into eukaryotic host target cells, but also involved in horizontal DNA transfer to other bacteria and eukaryotic cells, through DNA uptake from or release into the extracellular milieu. It provides a new insight into the pathogenicity of Helicobacter pylori and a novel target for antimicrobials development. However, many challenges remain for us in understanding the biological role of T4SS in Helicobacter pylori.

Research progress on Helicobacter pylori outer membrane protein.

Helicobacter pylori (H pylori), one of the most common bacterial pathogens on human beings, colonizes the gastric mucosa. In its 95 paralogous gene families, there is a large outer membrane protein (OMP) family. It includes 32 members. These OMP are important for the diagnosis, protective immunity, pathogenicity of H pylori and so on. They are significantly associated with high H pylori density, the damage of gastric mucosa, high mucosal IL-8 levels and severe neutrophil infiltration. We introduce their research progress on pathogenicity.

Construction of prokaryotic expression system of ltB-ureB fusion gene and identification of the recombinant protein immunity and adjuvanticity.

AIM: To construct ltB-ureB fusion gene and its prokaryotic expression system and identify immunity and adjuvanticity of the expressed recombinant protein. METHODS: The ureB gene from a clinical Helicobacter pylori (H pylori) strain Y06 and the ltB gene from Escherichia coli (E. coli) strain 44851 were linked into ltB-ureB fusion gene by PCR. The fusion gene sequence was analyzed after T-A cloning. A prokaryotic recombinant expression vector pET32a inserted with ltB-ureB fusion gene (pET32a-ltB-ureB) was constructed. Expression of the recombinant LTB-UreB protein (rLTB-UreB) in E. coli BL21DE3 induced by isopropylthio-beta-D-galactoside (IPTG) at different concentrations was detected by SDS-PAGE. Western blot assays were used to examine the immunoreaction of rLTB-UreB by a commercial antibody against whole cell of H pylori and a self-prepared rabbit anti-rUreB serum, respectively, and determine the antigenicity of the recombinant protein on inducing specific antibody in rabbits. GM1-ELISA was used to demonstrate the adjuvanticity of rLTB-UreB. Immunoreaction of rLTB-UreB to the UreB antibody positive sera from 125 gastric patients was determined by using ELISA. RESULTS: In comparison with the corresponding sequences of original genes, the nucleotide sequence homologies of the cloned ltB-ureB fusion gene were 100%. IPTG with different dosages of 0.1-1.0 mmol/L could efficiently induce pET32a-ltB-ureB-E.coli BL21DE3 to express the rLTB-UreB. The output of the target recombinant protein expressed by pET32a-ureB-E.coli BL21DE3 was approximately 35% of the total bacterial proteins. rLTB-UreB mainly presented in the form of inclusion body. Western blotting results demonstrated that rLTB-UreB could combine with the commercial antibody against whole cell of H pylori and anti-rUreB serum as well as induce rabbit to produce specific antibody. The strong ability of rLTB-UreB binding bovine GM1 indicated the existence of adjuvanticity of the recombinant protein. All the UreB antibody positive sera from the patients (125/125) were positive for rLTB-UreB. CONCLUSION: A recombinant prokaryotic expression system with high expression efficiency of the target fusion gene ltB-ureB was successfully established. The expressed rLTB-UreB showed qualified immunogenicity, antigenicity and adjuvanticity. All the results mentioned above laid a firm foundation for further development of H pylori genetically engineered vaccine.

Construction of prokaryotic expression system of 2 148-bp fragment from cagA gene and detection of cagA gene, CagA protein in Helicobacter pylori isolates and its antibody in sera of patients.

AIM: To construct a prokaryotic expression system of a Helicobacter pylori (H pylori) cagA gene fragment and establish enzyme-linked immunosorbent assays (ELISA) for detecting CagA and its antibody, so as to understand the manner in which the infection of CagA-expressing H pylori (CagA(+) H pylori) isolates cause diseases. METHODS: H pylori strains in gastric biopsy specimens from 156 patients with positive results in rapid urease test were isolated. PCR was used to detect the frequency of cagA gene in the 109 H pylori isolates and to amplify a 2 148-bp fragment (cagA1) of cagA gene from a clinical strain Y06. A prokaryotic expression system of cagA1 gene was constructed, and the expression of the target recombinant protein (rCagA1) was examined by SDS-PAGE. Western blotting and immunodiffusion assay were employed to determine the immunoreactivity and antigenicity of rCagA1, respectively. Two ELISAs were established to detect CagA expression in 109 H pylori isolates and the presence of CagA antibody in the corresponding patients' sera, and the correlations between infection with CagA(+) H pylori and gastritis as well as peptic ulcer were analyzed. RESULTS: Of all the clinical specimens obtained, 80.8% (126/156) were found to have H pylori isolates and 97.2% of the isolates (106/109) were positive for cagA gene. In comparison with the reported data, the cloned cagA1 fragment possessed 94.83% and 93.30% homologies with the nucleotide and putative amino acid sequences, respectively. The output of rCagA1 produced by the constructed recombinant prokaryotic expression system was approximately 30% of the total bacterial protein. rCagA1 was able to bind to the commercial antibody against the whole-cells of H pylori and to induce the immunized rabbits to produce antibody with an immunodiffusion titer of 1:4. A proportion as high as 92.6% of the H pylori isolates (101/109) expressed CagA and 88.1% of the patients' serum samples (96/109) were CagA antibody-positive. The percentage of CagA(+) H pylori strains (97.9%) isolated from the biopsy specimens of peptic ulcer appeared to be higher than that from gastritis (88.5%), but the difference was not statistically significant (chi (2)=3.48, P>0.05). CONCLUSION: rCagA1 produced by the prokaryotic expression system constructed in this study possesses good immunoreactivity and antigenicity, and the established ELISAs can be used to detect CagA of H pylori and its antibody. H pylori isolates show high frequencies of cagA gene and CagA expression, but the infections by CagA(+) H pylori strains are not the most decisive factors to cause gastric diseases.