Role of dup A in virulence of Helicobacter pylori

Helicobacter pylori(H. pylori) is a gastric human pathogen associated with acute and chronic gastritis, 70% of all gastric ulcers, 85% of all duodenal ulcers, and both forms of stomach cancer, mucosal-associated lymphoid tissue(MALT) lymphoma and adenocarcinoma. Recently, attention has focused on possible relationship between presence of certain virulence factor and H. pylori-associated diseases. Some contradictory data between this bacterium and related disorders has been observed since not all the colonized individuals develop to severe disease. The reported diseases plausibility related to H. pylori specific virulence factors became an interesting story about this organism. Although a number of putative virulence factors have been identified including cytotoxin-associated gene a(cag A) and vac A, there are conflicting data about their actual participation as specific risk factor for H. pylori-related diseases. Duodenal ulcer promoting gene a(dup A) is a virulence factor of H. pylori that is highly associated with duodenal ulcer development and reduced risk of gastric cancer. The prevalence of dup A in H. pylori strains isolated from western countries is relatively higher than in H. pylori strains from Asian countries. Current confusing epidemiological reports will continue unless future sophisticated and molecular studies provide data on functional and complete dup A cluster in H. pylori infected individuals. This paper elucidates available knowledge concerning role of dup A in virulence of H. pylori after a decade of its discovery.

Causal role of Helicobacter pylori infection in gastric cancer

Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori（H pylori） is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of Hpylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.

Molecular cross-talk between Helicobacter pylori and human gastric mucosa

Helicobacter pylori (H.pylori) has co-evolved with humans to be transmitted from person to person and to colonize the stomach persistently.A well-choreographed equilibrium between the bacterial effectors and host responses permits microbial persistence and health of the host,but confers a risk for serious diseases including gastric cancer.During its long coexistence with humans,H.pylori has developed complex strategies to limit the degree and extent of gastric mucosal damage and in? ammation,as well as immune effector activity.The present editorial thus aims to introduce and comment on major advances in the rapidly developing area of H.pylori/human gastric mucosa interaction (and its pathological sequelae),which is the result of millennia of co-evolution of,and thus of reciprocal knowledge between,the pathogen and its human host.

Helicobacter pylori gamma-glutamyl transpeptidase and its pathogenic role

Helicobacter pylori(H.pylori)gamma-glutamyl transpeptidase(GGT)is a bacterial virulence factor that converts glutamine into glutamate and ammonia,and converts glutathione into glutamate and cysteinylglycine.H.pylori GGT causes glutamine and glutathione consumption in the host cells,ammonia production and reactive oxygen species generation.These products induce cell-cycle arrest,apoptosis,and necrosis in gastric epithelial cells.H.pylori GGT may also inhibit apoptosis and induce gastric epithelial cell proliferation through the induction of cyclooxygenase-2,epidermal growth factor-related peptides,inducible nitric oxide synthase and interleukin-8.H.pylori GGT induces immune tolerance through the inhibition of T cell-mediated immunity and dendritic cell differentiation.The effect of GGT on H.pylori colonization and gastric persistence are also discussed.

PA1426 regulates Pseudomonas aeruginosa quorum sensing and virulence:an in vitro study

Objective:Pseudomonas aeruginosa(P.aeruginosa)contains a hierarchy of quorum sensing(QS)network,consisting of the las,rhl and pqs systems,which play a key role in coordinating the expression of virulence factors.PA2146 was found to be associated with P.aeruginosa pathogenicity in macrophage and host Immune response.The aim of this study was to investigate the effects of PA2146 on the virulence of P.aeruginosa and explore its mechanism.Methods:PA2146 gene knockout strain and complement strain of P.aeruginosa PAO1 were constructed.The biomass of biofilm was detected by crystal violet staining;the virulence factors were measured,including pyocyanin,rhamnolipid,LasA elastase,LasB elastase and hemolytic activity;RNA-seq and label-free relative quantitative proteomics analyses were carried out to test the influence of PA2146 on transcriptomics and proteomics.This study was approved by the Institutional Review Board of the Third Xiangya Hospital,Central South University,China(approval No.2019-S021).Results:PA2146-deficient strains showed reduced biofilm formation and increased pyocyanin,rhamnolipid,LasA elastase,LasB elastase,and hemolytic activity,as well as increased motility,compared with the wild-type strain.RNA-seq and label-free relative quantitative proteomics analyses revealed that PA2146 repressed the transcription of several genes that are integral to the pqs system and to pyocyanin biosynthesis,and increased the expression of MexEF-OprN efflux pump components at the gene and protein level.Conclusion:PA2146 gene was found to inhibit the pqs system.PA2146 may affect quorum sensing by directly inhibiting the pqs system or by enhancing the expression of MexEF-OprN efflux pump components,thereby promoting efflux of 2-heptyl-4(1H)-quinolone,a Pseudomonas quinolone signal precursor,and thus affecting P.aeruginosa virulence.

Optogenetics in oral and craniofacial research

Optogenetics combines optics and genetic engineering to control specific gene expression and biological functions and has the advantages of precise spatiotemporal control,noninvasiveness,and high efficiency.Genetically modified photosensory sensors are engineered into proteins to modulate conformational changes with light stimulation.Therefore,optogenetic techniques can provide new insights into oral biological processes at different levels,ranging from the subcellular and cellular levels to neural circuits and behavioral models.Here,we introduce the origins of optogenetics and highlight the recent progress of optogenetic approaches in oral and craniofacial research,focusing on the ability to apply optogenetics to the study of basic scientific neural mechanisms and to establish different oral behavioral test models in vivo(orofacial movement,licking,eating,and drinking),such as channelrhodopsin(ChR),archaerhodopsin(Arch),and halorhodopsin from Natronomonas pharaonis(NpHR).We also review the synergic and antagonistic effects of optogenetics in preclinical studies of trigeminal neuralgia and maxillofacial cellulitis.In addition,optogenetic tools have been used to control the neurogenic differentiation of dental pulp stem cells in translational studies.Although the scope of optogenetic tools is increasing,there are limited large animal experiments and clinical studies in dental research.Potential future directions include exploring therapeutic strategies for addressing loss of taste in patients with coronavirus disease 2019(COVID-19),studying oral bacterial biofilms,enhancing craniomaxillofacial and periodontal tissue regeneration,and elucidating the possible pathogenesis of dry sockets,xerostomia,and burning mouth syndrome.

Quorum Sensing:An Emerging Role for Vibrio Infection and Host Defense

Quorum sensing(QS)is a mechanism that allows bacteria to regulate various physiological and biochemical functions by secreting,sensing and responding to signaling molecules called autoinducers(AIs).In Vibrio species,QS plays a crucial role in modulating different biological characteristics.QS can influence the formation of biofilms,which are communities of bacteria encased in a protective matrix.It also controls flagella formation and motility,ensuring that Vibrio spp.can move efficiently in response to environmental cues.Additionally,QS in Vibrio spp.regulates the production of different virulence factors based on cell density.This enables the bacteria to adjust their virulence strategies accordingly,enhancing pathogenicity.QS also influences the interaction between Vibrio spp.and their host.Following infection by Vibrio spp.,QS can affect the host immune response and colonization processes.Understanding the role of QS in these interactions is crucial for unraveling the complex dynamics between Vibrio spp.and the host.In summary,research on QS in Vibrio spp.has revealed its significance in regulating various biological phenotypes,controlling virulence factor production and affecting host defense.It provides valuable insights into the intricate mechanisms underlying microbial behavior,host adaptation and Vibrio spp.pathogenesis.

A versatile Tn7 transposon-based bioluminescence tagging tool for quantitative and spatial detection of bacteria in plants

Investigation of plant-bacteria interactions requires quantification of in planta bacterial titers by means of cumbersome and time-consuming colony-counting assays.Here,we devised a broadly applicable tool for bioluminescence-based quantitative and spatial detection of bacteria in plants.We developed vectors that enable Tn7 transposon-mediated integration of the luxCDABEluciferase operon into a specific genomic location found ubiquitously across bacterial phyla.These vectors allowed for the generation of bioluminescent transformants of various plant pathogenic bacteria from the genera Pseudomonas,Rhizobium(Agrobacterium),and Ralstonia.Direct luminescence measurements of plant tissues inoculated with bioluminescent Pseudomonas syringae pv.tomato DC3000(Pto-lux)reported bacterial titers as accurately as conventional colony-counting assays in Arabidopsis thaliana,Solanum lycopersicum,Nicotiana benthamiana,and Marchantia polymorpha.We further showed the usefulness of our vectors in converting previously generated Pto derivatives to isogenic bioluminescent strains.Importantly,quantitative bioluminescence assays using these Pto-lux strains accurately reported the effects of plant immunity and bacterial effectors on bacterial growth,with a dynamic range of four orders of magnitude.Moreover,macroscopic bioluminescence imaging illuminated the spatial patterns of Pto-lux growth in/on inoculated plant tissues.In conclusion,our vectors offer untapped opportunities to develop bioluminescence-based assays for a variety of plant-bacteria interactions.