Heterogeneity of Helicobacter pylori cag genotypes in experimentally infected mice

Our aim was to assess whether the Helicobacter pylori population recovered from experimentally infected mice show heterogeneity in cag genotypes. Wild-type FVB/N mice were challenged with strain Hp1 and sacrificed 8 weeks later. Direct PCR on gastric tissue was performed using primers for glmM and cagA, and for these two genes and for cagE and virB11 using DNA from the infecting and the emerging strains. The gastric tissues of two of five mice were PCR+ for glmM but not cagA. For the infecting strain, the PCRs for all four genes studied were strongly positive, but the sweeps from the emerging strains from both mice gave weaker signals for cagA and cagE. Examination of single colonies showed reduced or absent signals for cagA and cagE in relation to glmM and virB11. Serial dilution PCR of sweep isolates from the mice showed a 10- to 100-fold decrease in cagA signal compared to the infecting strain. The decrease of cagA and cagE, but not virB11, amplification and lack of cagA hybridization in Southern blots indicates a selective loss of the right half of the cag island during murine infection. This phenomenon is consistent with host-induced adaptive changes of cag genotype in the population of colonizing H. pylori cells.

New immunological assays for the diagnosis of Helicobacter pylori infection

There are several types of immunological tests available for the diagnosis and management of Helicobacter pylori infection. Most commercially available serological kits use the enzyme linked immunosorbent assay (ELISA) test format. Originally the kits used crude antigen preparations although many of the newer kits use a more purified antigen preparation, with often increased specificity but lower sensitivity. Near patient test kits are based either on latex agglutination or immunochromatography. Generally they have low sensitivities compared with laboratory tests. Western blotting, ELISA, and recombinant immunoblot assays (RIBA) have also been developed into commercially available kits and can be used to indicate the presence of specific virulence markers. An antigen detection kit has been developed for the detection of Helicobacter pylori in faeces. Immunological reagents have also been combined with other diagnostic modalities to develop immunohistochemical stains and DNA immunoassays. Helicobacter pylori is now recognised as the cause of gastritis and most cases of peptic ulcer disease (PUD); its long term carriage increases the risk of gastric adenocarcinoma sixfold and it is designated as a class I carcinogen. H pylori has also been implicated as a cause of gastric mucosa associated lymphoid tissue lymphomas. Its relation to non-ulcer dyspepsia remains controversial. Additionally, long term carriage of the organism may be associated with short stature in young girls and, in the general population, as a possible risk factor for the development of vasospastic disorders and possibly skin immunopathology such as urticaria. With the recognition of H pylori as an important human pathogen, it has become one of the growing number of organisms to have its complete genome sequence mapped. Serology is an important method of determining colonisation status and can be used for diagnosis, as a screening procedure, or to follow the efficacy of eradication regimens. Most serological assays are in the ELISA format although some are based on the latex agglutination reaction. These latter are used principally as near patient assays. Most assays detect IgG in serum although some detect serum IgA. More recently developed assays detect IgA in saliva and the production of affinity purified antibodies has led to the development of an antigen detection assay for faecal specimens. Serological reagents have also been used in immunocytochemistry and to speed up the detection of amplified products of the polymerase chain reaction (PCR)-DNA immunoassays.

Differential expression profiling of long non-coding RNA GAS5 and miR-126-3p in human cancer cells in response to sorafenib

Long non-coding RNAs (lncRNAs) and microRNAs are involved in numerous physio-pathological conditions included cancer. To better understand the molecular mechanism of the oral antitumor multikinase inhibitor sorafenib, we profiled the expression of a panel of lncRNAs and miRNAs by qPCR array in a sorafenib-treated hepatocellular carcinoma (HCC) cell line. Among the most affected ncRNAs, we found that sorafenib mediated the dysregulation of the lncRNAs GAS5, HOTTIP and HOXA-AS2 and the miR-126-3p, in a panel of human cancer cell lines (HCC, renal and breast carcinomas). By luciferase gene reporter assay, we discovered that GAS5 may act as a sponge for miR-126-3p in HCC cells. The expression level of GAS5 and miR-126-3p was verified in human liquid and/or solid biopsies from HCC patients. miR-126-3p expression in HCC tissues was decreased respect to their correspondent peritumoral tissues. The levels of plasmatic circulating miR-126-3p and GAS5 were significantly higher and lower in HCC patients compared to healthy subjects, respectively. This study highlighted the capability of sorafenib to modulate the expression of a wide range of ncRNAs and specifically, GAS5 and miR-126-3p were involved in the response to sorafenib of different cancer cell types.

Serological assays for identification of human gastric colonization by Helicobacter pylori strains expressing VacA m1 or m2

The Helicobacter pylori vacA gene encodes a secreted protein (VacA) that alters the function of gastric epithelial cells and T lymphocytes. H. pylori strains containing particular vacA alleles are associated with differential risk of disease. Because the VacA midregion may exist as one of two major types, m1 or m2, serologic responses may potentially be used to differentiate between patients colonized with vacA m1- or vacA m2-positive H. pylori strains. In this study, we examined the utility of specific antigens from the m regions of VacA as allele-specific diagnostic antigens. We report that serological responses to P44M1, an H. pylori m1-specific antigen, are observed predominantly in patients colonized with m1-positive strains, whereas responses to VacA m2 antigens, P48M2 and P55M2, are observed in patients colonized with either m1- or m2-positive strains. In an Asian-American population, serologic responses to VacA m region-specific antigens were not able to predict the risk of development of gastric cancer.

DNA methylation variations in familial female and male breast cancer

In total, ~25% of familial breast cancer (BC) is attributed to germline mutations of the BRCA1 and BRCA2 genes, while the rest of the cases are included in the BRCAX group. BC is also known to affect men, with a worldwide incidence of 1%. Epigenetic alterations, including DNA methylation, have been rarely studied in male breast cancer (MBC) on a genome-wide level. The aim of the present study was to examine the global DNA methylation profiles of patients with BC to identify differences between familial female breast cancer (FBC) and MBC, and according to BRCA1, BRCA2 or BRCAX mutation status. The genomic DNA of formalin-fixed paraffin-embedded tissues from 17 women and 7 men with BC was subjected to methylated DNA immunoprecipitation and hybridized on human promoter microarrays. The comparison between FBC and MBC revealed 2,846 significant differentially methylated regions corresponding to 2,486 annotated genes. Gene Ontology enrichment analysis revealed molecular function terms, such as the GTPase superfamily genes (particularly the GTPase Rho GAP/GEF and GTPase RAB), and cellular component terms associated with cytoskeletal architecture, such as 'cytoskeletal part', 'keratin filament' and 'intermediate filament'. When only FBC was considered, several cancer-associated pathways were among the most enriched KEGG pathways of differentially methylated genes when the BRCA2 group was compared with the BRCAX or BRCA1+BRCAX groups. The comparison between the BRCA1 and BRCA2+BRCAX groups comprised the molecular function term 'cytoskeletal protein binding'. Finally, the functional annotation of differentially methylated genes between the BRCAX and BRCA1+BRCA2 groups indicated that the most enriched molecular function terms were associated with GTPase activity. In conclusion, to the best of our knowledge, the present study was the first to compare the global DNA methylation profile of familial FBC and MBC. The results may provide useful insights into the epigenomic subtyping of BC and shed light on a possible novel molecular mechanism underlying BC carcinogenesis.

Characterization of a novel chaperone/usher fimbrial operon present on KpGI-5, a methionine tRNA gene-associated genomic island in Klebsiella pneumoniae

Background

Several strain-specific Klebsiella pneumoniae virulence determinants have been described, though these have almost exclusively been linked with hypervirulent liver abscess-associated strains. Through PCR interrogation of integration hotspots, chromosome walking, island-tagging and fosmid-based marker rescue we captured and sequenced KpGI-5, a novel genomic island integrated into the met56 tRNA gene of K. pneumoniae KR116, a bloodstream isolate from a patient with pneumonia and neutropenic sepsis.

Results

The 14.0 kb KpGI-5 island exhibited a genome-anomalous G + C content, possessed near-perfect 46 bp direct repeats, encoded a γ₁-chaperone/usher fimbrial cluster (fim2) and harboured seven other predicted genes of unknown function. Transcriptional analysis demonstrated expression of three fim2 genes, and suggested that the fim2A-fim2K cluster comprised an operon. As fimbrial systems are frequently implicated in pathogenesis, we examined the role of fim2 by analysing KR2107, a streptomycin-resistant derivative of KR116, and three isogenic mutants (Δfim, Δfim2 and ΔfimΔfim2) using biofilm assays, human cell adhesion assays and pair-wise competition-based murine models of intestinal colonization, lung infection and ascending urinary tract infection. Although no statistically significant role for fim2 was demonstrable, liver and kidney CFU counts for lung and urinary tract infection models, respectively, hinted at an ordered gradation of virulence: KR2107 (most virulent), KR2107∆fim2, KR2107∆fim and KR2107∆fim∆fim2 (least virulent). Thus, despite lack of statistical evidence there was a suggestion that fim and fim2 contribute additively to virulence in these murine infection models. However, further studies would be necessary to substantiate this hypothesis.

Conclusion

Although fim2 was present in 13% of Klebsiella spp. strains investigated, no obvious in vitro or in vivo role for the locus was identified, although there were subtle hints of involvement in urovirulence and bacterial dissemination from the respiratory tract. Based on our findings and on parallels with other fimbrial systems, we propose that fim2 has the potential to contribute beneficially to pathogenesis and/or environmental persistence of Klebsiella strains, at least under specific yet-to-be identified conditions.

Pilot study of the utility and acceptability of tampon sampling for the diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis infections by duplex realtime polymerase chain reaction in United Kingdom sex workers

We aimed to evaluate the acceptability of self-collected tampon samples for the screening of female sex workers for sexually transmitted infections. We recruited 65 sex workers, and 63 agreed to provide tampon samples. The tampon samples were processed by realtime polymerase chain reaction (PCR) targeting Neisseria gonorrhoeae and Chlamydia trachomatis. Urethral and endocervical swabs were also obtained from 61 of 63 participants and tested using culture (N. gonorrhoeae) and the BD ProbeTec strand displacement amplification (SDA) (C. trachomatis) assay. Tampon sampling was preferred by 95% of the women and all favoured being tested away from genitourinary medicine clinics; the most common reasons cited were avoidance of embarrassment (40%) and convenience (30%). Besides near-universal acceptability of tampon sampling, the tampon sampling-PCR approach described in this study appeared to have enhanced sensitivity compared with conventional testing, suggesting the possibility of a residual hidden burden of N. gonorrhoeae and/or C. trachomatis genital infections in UK female sex workers.

Helicobacter pylori seroconversion in asymptomatic blood donors: a five-year follow-up

Several techniques have been developed to diagnose Helicobacter pylori infection and two noninvasive methods are available: carbon 13-urea breath test (UBT) and serology. Measurement of IgG serum antibodies by enzyme-linked immunosorbent assay (ELISA) is a reliable and inexpensive method for detection of infection. The aim of this study was to assess the seroconversion by different techniques after five to eight years. In 1990, 588 of 1,010 asymptomatic donors were found to be seronegative by ELISA, based on an H. pylori whole-cell suspension lysate (sensitivity and specificity: 92% and 97%). In 1995 serum samples from 418 of 588 seronegative donors were collected and retested using the same antigen. 411 of 418 samples were frankly negative, and 7 donors were found to be seroconverted. This group of seven sera represents the object of the study. They were retested by ELISA and western blotting using a different antigen (NCTC). To standardize our techniques, sera from 43 H. pylori positive and 47 H. pylori negative patients according to culture, histology, urease test, and UBT were used. The cutoff for ELISA-NCTC was 0.53 AI (absorbance index) (mean value + 2 SD), and for western blotting was negativity for CagA or <10 bands (sensitivity and specificity: 95% and 96%; 98% and 81% for ELISA and western blotting respectively). According to the results obtained in 1990 and 1995, seven donors were found to be seroconverted by ELISA using sonicated antigen; in five the seroconversion was confirmed by ELISA using NCTC antigen and in two there was concordance with WB. Four of the seven donors were contacted and asked to undergo UBT and a further serum sample was drawn to be reassessed in 1998. A seroconversion was found in all four donors by ELISA, while WB and UBT confirmed the seroconversion in only three of four donors. In conclusion the in-house ELISA used performed well compared to other theoretically better serologic assays and confirmed the low seroconversion rate for H. pylori infection in adult populations living in developed countries.

Indole-containing arene-ruthenium complexes with broad spectrum activity against antibiotic-resistant bacteria

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A new family of indole-containing arene ruthenium organometallic compounds are active against several bacterial species and drug resistant strains

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Bactericidal activity observed against various Gram negative, Gram positive and acid-fast bacteria, demonstrating broad-spectrum inhibitory activity

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Compound series exhibits low toxicity against human cells

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Shows considerable promise as next generation antibiotics

Antimicrobial resistant (AMR) bacteria are emerging and spreading globally, threatening our ability to treat common infectious diseases. The development of new classes of antibiotics able to kill or inhibit the growth of such AMR bacteria through novel mechanisms of action is therefore urgently needed. Here, a new family of indole-containing arene ruthenium organometallic compounds are screened against several bacterial species and drug resistant strains. The most active complex [(p-cym)Ru(O-cyclohexyl-1H-indole-2-carbothioate)Cl] (3) shows growth inhibition and bactericidal activity against different organisms (Acinetobacter baumannii, Mycobacterium abscessus, Mycobacterium tuberculosis, Staphylococcus aureus, Salmonella enterica serovar Typhi and Escherichia coli), demonstrating broad-spectrum inhibitory activity. Importantly, this compound series exhibits low toxicity against human cells. Owing to the novelty of the antibiotic family, their moderate cytotoxicity, and their inhibitory activity against Gram positive, Gram negative and acid-fast, antibiotic resistant microorganisms, this series shows significant promise for further development.

Nitric oxide induces the distinct invisibility phenotype of Mycobacterium tuberculosis

During infection Mycobacterium tuberculosis (Mtb) forms physiologically distinct subpopulations that are recalcitrant to treatment and undetectable using standard diagnostics. These difficult to culture or differentially culturable (DC) Mtb are revealed in liquid media, their revival is often stimulated by resuscitation-promoting factors (Rpf) and prevented by Rpf inhibitors. Here, we investigated the role of nitric oxide (NO) in promoting the DC phenotype. Rpf-dependent DC Mtb were detected following infection of interferon-γ-induced macrophages capable of producing NO, but not when inducible NO synthase was inactivated. After exposure of Mtb to a new donor for sustained NO release (named NOD), the majority of viable cells were Rpf-dependent and undetectable on solid media. Gene expression analyses revealed a broad transcriptional response to NOD, including down-regulation of all five rpf genes. The DC phenotype was partially reverted by over-expression of Rpfs which promoted peptidoglycan remodelling. Thus, NO plays a central role in the generation of Rpf-dependent Mtb, with implications for improving tuberculosis diagnostics and treatments.