Role of lipid rafts in persistent Helicobacter pylori infection: a narrative review

Background and Objective

The distribution of components in the cell membrane is not uniform, but is organized into specific functional microdomains, known as “lipid rafts”. These lipid rafts consist of cholesterol, sphingolipids, and various proteins. Studies have shown that lipid rafts contain multiple proteins that are closely related to signal transduction and immune response. Furthermore, lipid rafts are the sites where a variety of pathogens invade the cells, and are associated with the persistent infection of some pathogens, especially Helicobacter pylori (Hp). We are going to explore a new method to treat Hp by discussing the important role of lipid rafts in Hp persistent infection.

Methods

Papers on lipid rafts were retrieved to analyze the evolution of the definition of lipid raft, research techniques, and studies on the correlation of lipid rafts with pathogens infecting host cells.

Key Content and Findings

Hp uses cholesterol-α-glucosyltransferase (CGT) to extract cholesterol from the lipid rafts of host cell membrane and destroys the integrity of the lipid rafts, which contributes to its immune escape; Using drugs to inhibit the destruction of lipid rafts by CGT can inhibit the growth of Hp and help the body clear Hp.

Conclusions

Lipid rafts are key to persistent Hp infection, and a new field of research on pathogen-host cell interactions and signal transduction. Researches on lipid rafts may promote a new breakthrough in the field of treatment of Hp.

Association between Helicobacter pylori infection and the risk of colorectal cancer: A systematic review and meta-analysis

BACKGROUND

The existing evidence on the relationship between Helicobacter pylori infection and the risk of colorectal cancer is inconsistent. We conducted a systematic review with a meta-analysis to explore this relationship and to determine whether the relationship varies according to the study characteristics.

METHODS

We searched the PubMed, OVID, EMBASE database, and the reference lists of pertinent articles published up to October 2019 by 2 researchers independently. Summary odds ratios (OR) with their 95% confidence intervals (CIs) were estimated using a random-effects model.

RESULTS

Forty seven studies including 17,416 cases of colorectal cancer (CRC) and 55,811 cases of control were included. Overall, H. pylori infection was associated with an increased risk of CRC (OR = 1.70 95% CI 1.64-1.76, I = 97%), although there was significant heterogeneity among the studies. Subgroup analysis revealed that the positive correlation might vary by the design of study conducted.

CONCLUSION

This meta-analysis demonstrates a positive association between H. pylori infection and the risk of colorectal cancer.

(-)-Epigallocatechin-3-gallate induces interferon-λ2 expression to anti-influenza A virus in human bronchial epithelial cells (BEAS-2B) through p38 MAPK signaling pathway

Background

(-)-Epigallocatechin-3-gallate (EGCG), a major component of green tea, has been found to inhibit the influenza virus. However, the mechanism of EGCG anti-influenza virus effect needs to be further explored.

Methods

BEAS-2B cells were treated with different concentrations of EGCG or were treated with EGCG for different times. CCK8 assay was used to detect the cell viability, and quantitative real time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay were employed to measure the interferon (IFN)-λ2 mRNA and protein expression levels. The phospho-p38 mitogen-activated protein kinase (P-p38 MAPK), phospho-extracellular signal-regulated kinase (P-ERK), and phospho-c-Jun N-terminal kinase (P-JNK) expression were tested by western blot. Then, p38 MAPK, ERK, and JNK inhibitor were used to study the effect of p38 MAPK, ERK, and JNK signaling pathways on IFN-λ2 expression. The BEAS-2B cells were treated with EGCG, EGCG and IFN λ2 neutralizing antibody or control antibody for 12 h, and were infected with influenza A virus (IAV) (H1N1) for 1 h. After 12 h, nucleoprotein (NP) mRNA and protein expression levels of H1N1 were assessed by qRT-PCR and western blot.

Results

The IFN-λ2 mRNA and protein expression levels in BEAS-2B cells were up-regulated after EGCG (treatment in time- and dose-dependent manners the concentration range from 0 to 50 µg/mL had no cytotoxicity). Meanwhile, the P-p38 MAPK, P-ERK, and P-JNK expression levels were up-regulated. IFN-λ2 mRNA and protein expression was inhibited after p38 MAPK inhibitor pre-treatment, but not by ERK and JNK inhibitors. Furthermore, the expression of H1N1 NP gene and protein decreased after EGCG pre-treatment, while IFN-λ2 neutralizing antibody attenuated the effect of EGCG inhibiting the expression of H1N1 NP gene and protein.

Conclusions

EGCG inhibited IAV H1N1 by inducing the expression of IFN-λ2 in BEAS-2B cells through the p38 MAPK signaling pathway.

Helicobacter pylori and gastrointestinal and neurological diseases: Study protocol of an umbrella review of systematic reviews and meta-analyses

BACKGROUND

Systematic reviews showed that Helicobacter pylori (HP) infection is a major risk for developing gastric cancer and gastric ulcer and that it might be the cause of inflammatory bowel diseases, functional gastrointestinal disorders, and neurological diseases like Alzheimer disease. However, the robustness of the evidence was not tested. We will perform an umbrella review to systematically evaluate current evidence on the correlation between HP infection and gastrointestinal and neurological diseases.

METHODS

We will search OVID MEDLINE, EMBASE, and the Cochrane library for systematic reviews that evaluate the correlation of HP with gastrointestinal and neurological diseases, from inception to 1 July, 2019. Two reviewers will independently screen titles and abstracts of retrieved articles for eligible studies, and they will extract information for data analysis. We will assess heterogeneity between studies using I statistics and evaluate small-study effect in each systematic review through Egger test. Excess significance bias will be evaluated by compared the expected number of clinical studies with positive findings with the observed number. Quality of each systematic review will be assessed by using AMSTAR2 checklist.

ETHICS AND DISSEMINATION

This umbrella review is anticipated to be finished in December 2019, and the results will be published in a peer-reviewed journal and disseminated through conference presentation or poster. Because all of the data used in this systematic review and meta-analysis has been published, this review does not require ethical approval.Registration: PROSPERO CRD42019137226.

Fluid shear stress-induced IL-8/CXCR signaling in human ovarian cancer cells

Background

Interleukin-8 (IL-8) released from mechanosensitive cancer cells plays a key role in the inflammation and metastasis of solid carcinomas. In this study, we have explored IL-8 and its receptors signal transduction process of human ovarian cancer cells under conditions of FSS.

Methods

After the fluid shear stress was loaded, LightCycler™ system and quantitative sandwich ELISA were employed to assay the IL-8 mRNA expression and protein production, respectively. IL-8 reporter gene pEGFP1-IL8USCS was constructed for determining IL-8 gene transcriptional activation through gene transfer and flow cytometric analysis. NF-κB nuclear translocation was observed by immunocytofluorescent staining. Western blot was used to examine IκB phosphorylation and degradation. RT-PCR, Northern blot and immunofluorescence were used to determine the expression of a cell-surface chemokine receptor CXCR2 at mRNA and protein levels.

Results

IL-8 mRNA expression and protein production had biphasic responses to low shear stress (1.5 dyne/cm²), with the peaks at 1 and 2 h respectively. There was an increase in enhanced green fluorescent protein expression in pEGFP1-IL8USCS-transfected SKOV3 cells subjected to a fluid shear stress of 1.5 dyne/cm² for 2 h. Following the application of shear stress of 1.5 dyne/cm², NF-κB p65 became detectable in the cell nuclei, and Phosphorylated IκB in cell lysates increased significantly. CXCR2, which was constitutively present on the surface of SKOV3 cells, increased following exposure to fluid shear stress for 60 min.

Conclusions

Fluid shear stress triggered IL-8/CXCR2 signaling of SKOV3 cells is an early gene activation, and the activation can be mediated through NF-κB. This observation suggested that fluid shear stress-induced IL-8 activation and the downstream signal pathways may have an important contribution to the pathogenesis and development of both inflammation and metastasis of ovarian carcinomas.

[Relationship of OPRM1 118A/G gene polymorphism and oxycodone analygesic dose in paitents with cancer pain]

OBJECTIVE

To investigate the relationship between OPRM1 118A/G gene polymorphism and oxycodone analgesic dose in patients with cancer pain.

METHODS

DNA sequencing was used to detect the genotypies of OPRM1 118 A/G site in 203 patients with moderate and severe cancer pain, and to compare the relationship between the pain degree and the dose of oxycodone at 3 and 30 days after treatment in patients with different genotypes.

RESULTS

The fequencies of AA, AG and GG genotypes at the OPRM1 118 A/G site were 34.78%, 52.70%, and 12.52%, respectively. The dosage of oxycodone in GG genotype was significantly higher than that in AA genotype and AG genotype (15.44±10.19 vs. 10.25±4.53, 10.49±5.26; 89.15±27.69 vs. 43.59±12.19, 48.27±18.79) on the 3 and 30 day after treatment, difference was statistically significant (P< 0.05).

CONCLUSION

For cancer pain patients with GG genotype of OPRM1 118A/G site, if they need to achieve the same analgesic effect as patients with AA and AG genotype, the dose of oxycodone should be increased.

Phylogenetic analysis of clinical strains of Helicobacter pylori isolated from patients with gastric diseases in Tibet

BACKGROUND

Helicobacter pylori (H. pylori) is a Gram-negative pathogenic bacterium that causes chronic gastritis and other gastric diseases in humans. In Tibet, China, the infection of H. pylori is an important risk factor that caused gastric cancer.

METHODS

To understand the characteristics of this pathogen in Tibet, five strains of H. pylori were isolated from three patients' oral cavity or stomach who had either a gastric ulcer or gastritis. We performed genome sequences of these five clinical strains on Illumina Hiseq, and 55,016-63666 SNVs/InDels were identified by comparing to the reference strain of H. pylori 26995.

RESULTS

The phylogenetic analysis with multi-locus sequence typing (MLST) showed that five Tibetan strains were defined as hpEurope population and their proteins encoded by the cagA gene also presented a western type. Also, the strains that were isolated from the same patients' oral cavity and stomach exhibited homology in molecular evolution.

CONCLUSIONS

This is the first study to investigate the phylogenetic population structure of the epidemic strains of H. pylori in Tibet, which may improve cognition of Tibetan strains and confirm the homology of the strains from oral cavity and stomach.

[Phylogenetic study of drug resistance genes from clinical isolates of Helicobacter pylori]

To carry out phylogenetic analysis for drug-resistance genes from clinical isolates of Helicobacter pylori (Hp) among patients with gastric diseases from Tibet, China.

METHODS

Hp strains were isolated and cultured from saliva and gastric mucosal tissues derived from patients with gastric diseases. Nine strains (including 5 isolated from oral tissues, 1 isolated from gastric tissues, and 3 representative strains of SS international standard strains used for animal models) were tested for common antibiotic resistance. Together with an ACTT 11637 international standard strain, these were subjected to re-sequencing to obtain drug-resistance genes. Such genes from various sources were compared with the resistance genes of Hp strains recorded by the NCBI website. Combined with results of drug-resistance experiments, correlation between molecular evolution and drug-resistance was analyzed.

RESULTS

Testing of gastric mucosal tissues and salivary samples from 217 patients has found 89 Hp strains, which yielded a total infection rate of 41.01%. The resistance rates of 9 representative Hp strains for clarithromycin, amoxicillin, metronidazole, levofloxacin and tetracycline were 77.8%, 77.8%, 44.4%, 77.8%, and 77.8%, respectively. Compared with the reference strain, the similarity between clarithromycin-resistance genes was 99%, and that between amoxicillin- and metronidazole-resistance genes was 96%-97%. A2143G mutation was also found in clarithromycin-resistant genes of three Hp strains.

CONCLUSION

The sensitivity of Hp to metronidazole is much higher in patients from Tibet region, and the sensitivity of Hp to clarithromycin, amoxicillin, levofloxacin and tetracycline is poor. Resistance mutations are consistent with drug resistance.

[Adhesion and inhibiting adhesion of Helicobacter pylori to SGC-7901 cell in vitro by four Lactobacilli from human]

OBJECTIVE

To investigate the adherence ability of four Lactobacilli to gastric epithelial cell SGC-7901 and the ability of inhibiting the adherence of Helicobacter pylori to the cells.

METHODS

The light microscope and scanning electron microscope were used to detect Lactobacilli that adhering to SGC-7901 cells after co-culturing for 2 hours. Using FITC-conjuncted antibody, the adhered Helicobacter pylori density was evaluated under fluorescence microscope after pretreatment with live or nonviable Lactobacilli.

RESULTS

Four Lactobacilli's live and nonviable stains could adhere to SGC-7901 tightly and obviously inhibit the adherence of Helicobacter pylori, but their adherence ability was not different, excluding their live stains adherence ability. And their inhibiting ability were different, of which the best was Lac15, the worst was Lac12.

CONCLUSION

Four Lactobacilli can inhibit the adherence of Helicobacter pylori to gastric epithelial cell SGC-7901 in vitro, and they should be further evaluated in vivo.