Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes,becoming sometimes life threatening for the patients.Therefore,aggressive antibiotic therapies are administered,wh...Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes,becoming sometimes life threatening for the patients.Therefore,aggressive antibiotic therapies are administered,which often require the use of last-resort drugs,if the infection is caused by multi-drug-resistant bacteria.Reducing the risk of bacterial contamination of medical devices in the hospitals has thus become an emerging issue.Promising routes to control these infections are based on materials provided with intrinsic bactericidal properties(i.e.,chemical action)and on the design of surface coatings able to limit bacteria adhesion and fouling phenomena(i.e.,physical action),thus preventing bacterial biofilm formation.Here,we report the development and validation of coatings made of layer-by-layer deposition of electrospun poly(vinylidene fluoride-co-trifluoro ethylene)P(VDF-TrFE)fibers with controlled orientations,which ultimately gave rise to antifouling surfaces.The obtained 10-layer surface morphology with 90°orientation fibers was able to efficiently prevent the adhesion of bacteria,by establishing a superhydrophobic-like behavior compatible with the Cassie-Baxter regimen.Moreover,the results highlighted that surface wettability and bacteria adhesion could be controlled using fibers with diameter comparable to bacteria size(i.e.,achievable via electrospinning process),by tuning the intra-fiber spacing,with relevant implications in the future design of biomedical surface coatings.展开更多
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.PA214...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.展开更多
Microbial species often occur in complex communities and exhibit intricate synergistic and antagonistic interactions.To avoid predation and compete for favorable niches,bacteria have evolved specialized protein secret...Microbial species often occur in complex communities and exhibit intricate synergistic and antagonistic interactions.To avoid predation and compete for favorable niches,bacteria have evolved specialized protein secretion systems.The type VI secretion system(T6SS)is a versatile secretion system widely distributed among Gram-negative bacteria that translocates effectors into target cells or the extracellular milieu via various physiological processes.Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases,and it has three independent T6SSs(H1-,H2-,and H3-T6SS).In this study,we found that the H3-T6SS of highly virulent P.aeruginosa PA14 is negatively regulated by OxyR and OmpR,which are global regulatory proteins of bacterial oxidative and acid stress.In addition,we identified a H3-T6SS effector PA14_33970,which is located upstream of VgrG3.PA14_33970 interacted directly with VgrG3 and translocated into host cells.Moreover,we found that H3-T6SS and PA14_33970 play crucial roles in oxidative,acid,and osmotic stress resistance,as well as in motility and biofilm formation.PA14_33970 was identified as a new T6SS effec-tor promoting biofilm formation and thus named TepB.Furthermore,we found that TepB contributes to the virulence of P.aeruginosa PA14 toward Caenorhabditis elegans.Overall,our study indicates that H3-T6SS and its biofilm-promot-ing effector TepB are regulated by OxyR and OmpR,both of which are important for adaptation of P.aeruginosa PA14 to multiple stressors,providing insights into the regulatory mechanisms and roles of T6SSs in P.aeruginosa.展开更多
文摘Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes,becoming sometimes life threatening for the patients.Therefore,aggressive antibiotic therapies are administered,which often require the use of last-resort drugs,if the infection is caused by multi-drug-resistant bacteria.Reducing the risk of bacterial contamination of medical devices in the hospitals has thus become an emerging issue.Promising routes to control these infections are based on materials provided with intrinsic bactericidal properties(i.e.,chemical action)and on the design of surface coatings able to limit bacteria adhesion and fouling phenomena(i.e.,physical action),thus preventing bacterial biofilm formation.Here,we report the development and validation of coatings made of layer-by-layer deposition of electrospun poly(vinylidene fluoride-co-trifluoro ethylene)P(VDF-TrFE)fibers with controlled orientations,which ultimately gave rise to antifouling surfaces.The obtained 10-layer surface morphology with 90°orientation fibers was able to efficiently prevent the adhesion of bacteria,by establishing a superhydrophobic-like behavior compatible with the Cassie-Baxter regimen.Moreover,the results highlighted that surface wettability and bacteria adhesion could be controlled using fibers with diameter comparable to bacteria size(i.e.,achievable via electrospinning process),by tuning the intra-fiber spacing,with relevant implications in the future design of biomedical surface coatings.
基金This study was supported by the National Natural Science Foundation of China(grant No.82072350 to YW).
文摘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.
基金supported by grants of the National Key R&D Program of China(Grants 2021YFA0909600)National Natural Science Foundation of China(Grants 31970114,32100034 and 32100149).
文摘Microbial species often occur in complex communities and exhibit intricate synergistic and antagonistic interactions.To avoid predation and compete for favorable niches,bacteria have evolved specialized protein secretion systems.The type VI secretion system(T6SS)is a versatile secretion system widely distributed among Gram-negative bacteria that translocates effectors into target cells or the extracellular milieu via various physiological processes.Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases,and it has three independent T6SSs(H1-,H2-,and H3-T6SS).In this study,we found that the H3-T6SS of highly virulent P.aeruginosa PA14 is negatively regulated by OxyR and OmpR,which are global regulatory proteins of bacterial oxidative and acid stress.In addition,we identified a H3-T6SS effector PA14_33970,which is located upstream of VgrG3.PA14_33970 interacted directly with VgrG3 and translocated into host cells.Moreover,we found that H3-T6SS and PA14_33970 play crucial roles in oxidative,acid,and osmotic stress resistance,as well as in motility and biofilm formation.PA14_33970 was identified as a new T6SS effec-tor promoting biofilm formation and thus named TepB.Furthermore,we found that TepB contributes to the virulence of P.aeruginosa PA14 toward Caenorhabditis elegans.Overall,our study indicates that H3-T6SS and its biofilm-promot-ing effector TepB are regulated by OxyR and OmpR,both of which are important for adaptation of P.aeruginosa PA14 to multiple stressors,providing insights into the regulatory mechanisms and roles of T6SSs in P.aeruginosa.
