铜绿假单胞菌注射液体外抗肿瘤生物活性检测方法的建立

目的建立铜绿假单胞菌注射液(Pseudomonas aeruginosa,PA-MSHA)体外抗肿瘤生物活性检测方法。方法将系列稀释的PA-MSHA在体外直接作用于人肝癌细胞BEL-7402,光学显微镜下观察细胞的生长状态;MTT比色法检测其对细胞增殖水平的影响;对10批PA-MSHA成品分别检测3次,以半数抑制浓度(IC50)为指标,计算批内和批间变异系数(CV),验证方法的精密性。结果随着PA-MSHA稀释度的降低,光镜下贴壁的BEL-7402细胞数量逐渐减少,细胞皱缩并破碎;MTT比色结果显示,随着PA-MSHA稀释度的降低,孔内颜色逐渐变浅,BEL-7402细胞增殖抑制率逐渐升高,呈一定的剂量-效应关系;10批PA-MSHA成品3次检测的IC50值范围为(3.584～7.778)×108个/ml,批内变异系数为4.58%～24.17%,批间变异系数15.08%～16.95%,总变异系数为15.81%,均符合细胞实验变异系数应小于30%的标准;PA-MSHA成品经该方法检测后,得到的IC50值在(3.109～7.383)×108个/ml范围内时,表明成品的生物活性合格。结论建立了PA-MSHA体外抗肿瘤生物活性检测方法,该方法稳定性好、精密性高,而且具有操作简便、节约成本和时间等优点,可用于对PA-MSHA以及其他类似细菌类生物制品的体外生物活性研究。     

Genomic and Metabolic Characteristics of the Pathogenicity in Pseudomonas aeruginosa

In recent years, the effectiveness of antimicrobials in the treatment of Pseudomonas aeruginosa infections has gradually decreased. This pathogen can be observed in several clinical cases, such as pneumonia, urinary tract infections, sepsis, in immunocompromised hosts, such as neutropenic cancer, burns, and AIDS patients. Furthermore, Pseudomonas aeruginosa causes diseases in both livestock and pets. The highly flexible and versatile genome of P. aeruginosa allows it to have a high rate of pathogenicity. The numerous secreted virulence factors, resulting from its numerous secretion systems, the multi-resistance to different classes of antibiotics, and the ability to produce biofilms are pathogenicity factors that cause numerous problems in the fight against P. aeruginosa infections and that must be better understood for an effective treatment. Infections by P. aeruginosa represent, therefore, a major health problem and, as resistance genes can be disseminated between the microbiotas associated with humans, animals, and the environment, this issue needs be addressed on the basis of an One Health approach. This review intends to bring together and describe in detail the molecular and metabolic pathways in P. aeruginosa’s pathogenesis, to contribute for the development of a more targeted therapy against this pathogen.     

Specific Maltose Derivatives Modulate the Swarming Motility of Nonswarming Mutant and Inhibit Bacterial Adhesion and Biofilm Formation by Pseudomonas aeruginosa

We have demonstrated that specific synthetic maltose derivatives activate the swarming motility of a Pseudomonas aeruginosa nonswarming mutant (rhlA) at low concentration, but inhibit it at high concentration. Although these molecules are not microbicidal, active maltose derivatives with bulky hydrocarbon groups inhibited bacterial adhesion, and exhibited biofilm inhibition and dispersion (IC₅₀ ～20 μM and DC₅₀ ～30 μM , respectively). Because the swarming motility of the rhlA mutant is abolished by the lack natural rhamnolipids, the swarming activation suggests that maltose derivatives are analogues of rhamnolipids. Together, these results suggest a new approach of controlling multiple bacterial activities (bacterial adhesion, biofilm formation, and swarming motility) by a set of disaccharide‐based molecules.     

EGCG-Mediated Potential Inhibition of Biofilm Development and Quorum Sensing in Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa), one of the dangerous multidrug resistance pathogens, orchestrates virulence factors production through quorum sensing (QS). Since the exploration of QS inhibitors, targeting virulence to circumvent bacterial pathogenesis without causing significant growth inhibition is a promising approach to treat P. aeruginosa infections. The present study has evaluated the anti-QS and anti-infective activity of epigallocatechin-3-gallate (EGCG), a bioactive ingredient of the traditional green tea, against P. aeruginosa. EGCG showed significant inhibitory effects on the development of biofilm, protease, elastase activity, swimming, and swarming motility, which was positively related to the production of C4-AHL. The expression of QS-related and QS-regulated virulence factors genes was also evaluated. Quantitative PCR analysis showed that EGCG significantly reduced the expression of las, rhl, and PQS genes and was highly correlated with the alterations of C4-AHL production. In-vivo experiments demonstrated that EGCG treatment reduced P. aeruginosa pathogenicity in Caenorhabditis elegans (C. elegans). EGCG increased the survival of C. elegans by 23.25%, 30.04%, and 36.35% in a dose-dependent manner. The findings of this study strongly suggest that EGCG could be a potential candidate for QS inhibition as an anti-virulence compound against bacterial infection.     

Design and Synthesis of Galactosylated Bifurcated Ligands with Nanomolar Affinity for Lectin LecA from Pseudomonas aeruginosa

Lectin A (LecA) from Pseudomonas aeruginosa is an established virulence factor. Glycoclusters that target LecA and are able to compete with human glycoconjugates present on epithelial cells are promising candidates to treat P. aeruginosa infection. A family of 32 glycodendrimers of generation 0 and 1 based on a bifurcated bis‐galactoside motif have been designed to interact with LecA. The influences both of the central multivalent core and of the aglycon of these glycodendrimers on their affinity toward LecA have been evaluated by use of a microarray technique, both qualitatively for rapid screening of the binding properties and also quantitatively (K_d). This has led to high‐affinity LecA ligands with K_d values in the low nanomolar range (K_d=22 nm for the best one).     

Properties of poly(AAc‐co‐HPMA‐cl‐EGDMA) hydrogel‐bound lipase of Pseudomonas aeruginosa MTCC‐4713 and its use in synthesis of methyl acrylate

Microbial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organic solvents. Various extracellular thermoalkaliphilic lipases have been reported from Pseudomonas sp. In the present study, a purified alkaline thermoalkalophilic extracellular lipase of Pseudomonas aeruginosa MTCC‐4713 was efficiently immobilized onto a synthetic poly(AAc‐co‐HPMA‐cl‐EGDMA) hydrogel by adsorption and the bound lipase was evaluated for its hydrolytic potential towards various p‐nitrophenyl acyl esters varying in their C‐chain lengths. The bound lipase showed optimal hydrolytic activity towards p‐nitrophenyl palmitate (p‐NPP) at pH 8.5 and temperature 45°C. The hydrolytic activity of the hydrogel‐bound lipase was markedly enhanced by the presence of Hg²⁺, Fe³⁺, and NH salt ions in that order. The hydrogel‐immobilized lipase (25 mg) was used to perform esterification in various n‐alkane(s) that resulted in ～ 84.9 mM of methyl acrylate at 45°C in n‐heptane under shaking (120 rpm) after 6 h, when methanol and acrylic acid were used in a ratio of 100 mM:100 mM, respectively. Addition of a molecular sieve (3Å × 1.5 mm) to the reaction system at a concentration of 100 mg/reaction vol (1 mL) resulted in a moderate enhancement in conversion of reactants into methyl acrylate (85.6 mM). During the repetitive esterification under optimum conditions, the hydrogel‐bound lipase produced 71.3 mM of ester after 10th cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 183–191, 2007     

原油降解菌株Pseudomonas.aeruginosa AS1生理生化性质及分类研究

原油降解菌株AS1筛选自延长油田油水样,对延长轻质原油具有良好降解能力,通过生理生化指标和16SrDNA基因序列分析进行了菌种鉴定,原油降解菌株AS1的16SrDNA基因序列与Pseu-domonas aeruginosa的相似度为99.1%,因而将其命名为P.aeruginosa AS1。该菌株的最适生长温度为37℃,能以延长轻质原油、液体石蜡为唯一碳源生长,并能合成鼠李糖脂类生物表面活性剂,该表面活性剂对柴油、煤油和原油等均有很好的乳化效果,在常温下形成EI24值为100%的乳状液。鉴于P.aerugi-nosa AS1的良好生物属性,该菌株有进一步进行微生物矿场试验的潜力。     

Cells Were a More Important Foaming Factor than Free Rhamnolipids in Fermentation of Pseudomonas aeruginosa E03-40 for High Rhamnolipid Production

Rhamnolipids are among the best‐known biosurfactants. Severe foaming occurs in aerobic rhamnolipid fermentation and negatively affects operation and economics of the biosurfactant production. In this study the foaming properties were examined with samples taken along a Pseudomonas aeruginosa fermentation that produced 55 g l^?1 rhamnolipids with a maximum volumetric productivity of 0.080 g l^?1 h^?1 and a maximum specific productivity of 0.013 g g^?1 h^?1. For a better understanding of the process, the broth samples were also centrifuged to prepare cell‐free supernatants and cell suspensions in water, and all samples were evaluated under fixed foaming conditions. In addition to the time profiles of foam rise, the initial foaming rates and maximum foam volumes were determined. Contrary to the general assumption, the cells, not rhamnolipids, were the main foaming agents in the fermentation. Soluble components including rhamnolipids had secondary roles. Supernatant foaming was higher after the culture entered the rhamnolipid‐producing stationary phase; however, the foaming appeared to decrease with increasing rhamnolipid concentrations at high concentrations (>15 g l^?1). The pH effects on foaming of broths, supernatants, and cell suspensions were also studied. Broth foaming was 55 and 80 % less at pH 5.5 and 5.0, respectively, compared to that at pH 6.5. Cell growth and rhamnolipid production at lower pH should be included in future studies. In addition, strain selection or genetic engineering and medium modification to reduce cell hydrophobicity are suggested as useful strategies to address the foaming issue of rhamnolipid fermentation.     

Giving Drugs a Second Chance: Antibacterial and Antibiofilm Effects of Ciclopirox and Ribavirin against Cystic Fibrosis Pseudomonas aeruginosa Strains

Drug repurposing is an attractive strategy for developing new antibacterial molecules. Herein, we evaluated the in vitro antibacterial, antibiofilm, and antivirulence activities of eight FDA-approved “non-antibiotic” drugs, comparatively to tobramycin, against selected Pseudomonas aeruginosa strains from cystic fibrosis patients. MIC and MBC values were measured by broth microdilution method. Time–kill kinetics was studied by the macro dilution method, and synergy studies were performed by checkerboard microdilution assay. The activity against preformed biofilms was measured by crystal violet and viable cell count assays. The effects on gene expression were studied by real-time quantitative PCR, while the cytotoxic potential was evaluated against IB3-1 bronchial CF cells. Ciclopirox, 5-fluorouracil, and actinomycin D showed the best activity against P. aeruginosa planktonic cells and therefore underwent further evaluation. Time–kill assays indicated actinomycin D and ciclopirox, contrarily to 5-fluorouracil and tobramycin, have the potential for bacterial eradication, although with strain-dependent efficacy. Ciclopirox was the most effective against the viability of the preformed biofilm. A similar activity was observed for other drugs, although they stimulate extracellular polymeric substance production. Ribavirin showed a specific antibiofilm effect, not dependent on bacterial killing. Exposure to drugs and tobramycin generally caused hyperexpression of the virulence traits tested, except for actinomycin D, which downregulated the expression of alkaline protease and alginate polymerization. Ciclopirox and actinomycin D revealed high cytotoxic potential. Ciclopirox and ribavirin might provide chemical scaffolds for anti-P. aeruginosa drugs. Further studies are warranted to decrease ciclopirox cytotoxicity and evaluate the in vivo protective effects.     

A nonconventional method for drying of Pseudomonas aeruginosa and its comparison with conventional methods

In this study, preparation of dried cultures of Pseudomonas aeruginosa using nonconventional drying method, namely, low-temperature low-humidity (LTLH) drying was investigated. The effect of carrier materials (whey protein, corn starch, and trehalose) was examined one at a time and also in combinations (to explore the synergistic effect). The results were compared with those obtained using spray drying and freeze drying in terms of cell survival and dry cell powder yield. The powder samples were analyzed also for morphology, flowability, particle size, and moisture content. In LTLH drying, good cell survival was observed along with high powder yield when compared with that in spray drying. Corn starch showed the highest cell survival (91%) and powder yield (94%, w/w) among the carrier materials employed besides resulting in good cell survival (65%) even after a storage period of 6 months.     

Liposomal Delivery of Newly Identified Prophage Lysins in a Pseudomonas aeruginosa Model

Pseudomonas aeruginosa is a Gram-negative opportunistic bacterium that presents resistance to several antibiotics, thus, representing a major threat to human and animal health. Phage-derived products, namely lysins, or peptidoglycan-hydrolyzing enzymes, can be an effective weapon against antibiotic-resistant bacteria. Whereas in Gram-positive bacteria, lysis from without is facilitated by the exposed peptidoglycan layer, this is not possible in the outer membrane-protected peptidoglycan of Gram-negative bacteria. Here, we suggest the encapsulation of lysins in liposomes as a delivery system against Gram-negative bacteria, using the model of P. aeruginosa. Bioinformatic analysis allowed for the identification of 38 distinct complete prophages within 66 P. aeruginosa genomes (16 of which newly sequenced) and led to the identification of 19 lysins of diverse sequence and function, 5 of which proceeded to wet lab analysis. The four purifiable lysins showed hydrolytic activity against Gram-positive bacterial lawns and, on zymogram assays, constituted of autoclaved P. aeruginosa cells. Additionally, lysins Pa7 and Pa119 combined with an outer membrane permeabilizer showed activity against P. aeruginosa cells. These two lysins were successfully encapsulated in DPPC:DOPE:CHEMS (molar ratio 4:4:2) liposomes with an average encapsulation efficiency of 33.33% and 32.30%, respectively. The application of the encapsulated lysins to the model P. aeruginosa led to a reduction in cell viability and resulted in cell lysis as observed in MTT cell viability assays and electron microscopy. In sum, we report here that prophages may be important sources of new enzybiotics, with prophage lysins showing high diversity and activity. In addition, these enzybiotics following their incorporation in liposomes were able to potentiate their antibacterial effect against the Gram-negative bacteria P. aeruginosa, used as the model.     

Screening of Molecular Virulence Markers in Staphylococcus aureus and Pseudomonas aeruginosa Strains Isolated from Clinical Infections

Staphylococcus (S.) aureus and Pseudomonas (Ps.) aeruginosa are two of the most frequently opportunistic pathogens isolated in nosocomial infections, responsible for severe infections in immunocompromised hosts. The frequent emergence of antibiotic-resistant S. aureus and Ps. aeruginosa strains has determined the development of new strategies in order to elucidate the different mechanisms used by these bacteria at different stages of the infectious process, providing the scientists with new procedures for preventing, or at least improving, the control of S. aureus and Ps. aeruginosa infections. The purpose of this study was to characterize the molecular markers of virulence in S. aureus and Ps. aeruginosa strains isolated from different clinical specimens. We used multiplex and uniplex PCR assays to detect the genes encoding different cell-wall associated and extracellular virulence factors, in order to evaluate potential associations between the presence of putative virulence genes and the outcome of infections caused by these bacteria. Our results demonstrate that all the studied S. aureus and Ps. aeruginosa strains synthesize the majority of the investigated virulence determinants, probably responsible for different types of infections.     

Potent and selective synthetic modulators of a quorum sensing repressor in Pseudomonas aeruginosa identified from second-generation libraries of N-acylated L-homoserine lactones

Bacteria can coordinate group behavior using chemical signals in a process called quorum sensing (QS). The QS system in the opportunistic pathogen Pseudomonas aeruginosa is largely governed by the LasR receptor and its cognate chemical signal, N-(3-oxo)-dodecanoyl L-homoserine lactone (OdDHL). LasR also appears to share this signal with an orphan LuxR-type receptor in P. aeruginosa, termed QscR, which represses LasR activity. Non-native molecules that modulate QscR would represent valuable tools to study the role of this novel QS repressor protein in P. aeruginosa. We performed a critical analysis of previously identified, non-native N-acylated L-homoserine lactone (AHL) activators and inhibitors of QscR to determine a set of structure-activity relationships (SARs). Based on these SAR data, we designed, synthesized, and screened several second-generation libraries of AHLs for new ligands that could target QscR. These studies revealed the most active AHL agonists and antagonists of QscR reported to date, with activities ranging from nanomolar to low micromolar in a QscR bacterial reporter strain. Several of these AHLs were highly selective for QscR over LasR and other LuxR-type receptors. A small subset of the new QscR activators, however, were also found to inhibit LasR; this demonstrates the exciting potential for the synergistic modulation of these integral P. aeruginosa QS receptors by using a single synthetic compound.     

Lung and Gut Microbiota Changes Associated with Pseudomonas aeruginosa Infection in Mouse Models of Cystic Fibrosis

Cystic fibrosis (CF) disease leads to altered lung and gut microbiomes compared to healthy subjects. The magnitude of this dysbiosis is influenced by organ-specific microenvironmental conditions at different stages of the disease. However, how this gut-lung dysbiosis is influenced by Pseudomonas aeruginosa chronic infection is unclear. To test the relationship between CFTR dysfunction and gut-lung microbiome under chronic infection, we established a model of P. aeruginosa infection in wild-type (WT) and gut-corrected CF mice. Using 16S ribosomal RNA gene, we compared lung, stool, and gut microbiota of C57Bl/6 Cftr ^tm1UNCTgN(FABPCFTR) or WT mice at the naïve state or infected with P. aeruginosa. P. aeruginosa infection influences murine health significantly changing body weight both in CF and WT mice. Both stool and gut microbiota revealed significantly higher values of alpha diversity in WT mice than in CF mice, while lung microbiota showed similar values. Infection with P. aeruginosa did not changed the diversity of the stool and gut microbiota, while a drop of diversity of the lung microbiota was observed compared to non-infected mice. However, the taxonomic composition of gut microbiota was shown to be influenced by P. aeruginosa infection in CF mice but not in WT mice. This finding indicates that P. aeruginosa chronic infection has a major impact on microbiota diversity and composition in the lung. In the gut, CFTR genotype and P. aeruginosa infection affected the overall diversity and taxonomic microbiota composition, respectively. Overall, our results suggest a cross-talk between lung and gut microbiota in relation to P. aeruginosa chronic infection and CFTR mutation.     

绿脓杆菌及其鞭毛蛋白联合rhIL-12体外对慢性乙型肝炎患者细胞免疫功能的影响

目的探讨绿脓杆菌及其鞭毛蛋白联合rhIL-12体外对慢性乙型肝炎患者细胞免疫功能的影响,为rhIL-12作为佐剂应用于临床提供理论依据。方法取健康人及慢性乙型肝炎患者外周血单个核细胞(PBMCs),分别与绿脓杆菌、鞭毛蛋白、rhIL-12、绿脓杆菌+rhIL-12、鞭毛蛋白+rhIL-12孵育,ELISA法检测细胞培养上清中IFNγ的含量。结果绿脓杆菌和鞭毛蛋白组只诱导产生低水平的IFNγ,rhIL-12组诱导产生IFNγ的水平较阴性对照组显著提高;而绿脓杆菌+rhIL-12组、鞭毛蛋白+rhIL-12组诱导产生IFNγ的水平显著高于绿脓杆菌、鞭毛蛋白和rhIL-12组,差异均有统计学意义,且rhIL-12的作用呈剂量依赖性。结论绿脓杆菌及其鞭毛蛋白联合rhIL-12体外能显著提高健康人和慢性乙型肝炎患者PBMCs产生IFNγ的水平,增强其细胞免疫应答。     

Polymicrobial Biofilm Organization of Staphylococcus aureus and Pseudomonas aeruginosa in a Chronic Wound Environment

Biofilm on the skin surface of chronic wounds is an important step that involves difficulties in wound healing. The polymicrobial nature inside this pathogenic biofilm is key to understanding the chronicity of the lesion. Few in vitro models have been developed to study bacterial interactions inside this chronic wound. We evaluated the biofilm formation and the evolution of bacteria released from this biofilm on the two main bacteria isolated in this condition, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimics the chronic wound environment. We observed that all species constituted a faster biofilm in the CWM compared to a traditional culture medium (p < 0.01). The percentages of biofilm formation were significantly higher in the mixed biofilm compared to those determined for the bacterial species alone (p < 0.01). Biofilm organization was a non-random structure where S. aureus aggregates were located close to the wound surface, whereas P. aeruginosa was located deeper in the wound bed. Planktonic biofilm-detached bacteria showed decreased growth, overexpression of genes encoding biofilm formation, and an increase in the mature biofilm biomass formed. Our data confirmed the impact of the chronic wound environment on biofilm formation and on bacterial lifecycle inside the biofilm.