Salmonella-mediated blood‒brain barrier penetration, tumor homing and tumor microenvironment regulation for enhanced chemo/bacterial glioma therapy

Chemotherapy is an important adjuvant treatment of glioma, while the efficacy is far from satisfactory, due not only to the biological barriers of blood‒brain barrier (BBB) and blood‒tumor barrier (BTB) but also to the intrinsic resistance of glioma cells via multiple survival mechanisms such as up-regulation of P-glycoprotein (P-gp). To address these limitations, we report a bacteria-based drug delivery strategy for BBB/BTB transportation, glioma targeting, and chemo-sensitization. Bacteria selectively colonized into hypoxic tumor region and modulated tumor microenvironment, including macrophages repolarization and neutrophils infiltration. Specifically, tumor migration of neutrophils was employed as hitchhiking delivery of doxorubicin (DOX)-loaded bacterial outer membrane vesicles (OMVs/DOX). By virtue of the surface pathogen-associated molecular patterns derived from native bacteria, OMVs/DOX could be selectively recognized by neutrophils, thus facilitating glioma targeted delivery of drug with significantly enhanced tumor accumulation by 18-fold as compared to the classical passive targeting effect. Moreover, the P-gp expression on tumor cells was silenced by bacteria type III secretion effector to sensitize the efficacy of DOX, resulting in complete tumor eradication with 100% survival of all treated mice. In addition, the colonized bacteria were finally cleared by anti-bacterial activity of DOX to minimize the potential infection risk, and cardiotoxicity of DOX was also avoided, achieving excellent compatibility. This work provides an efficient trans-BBB/BTB drug delivery strategy via cell hitchhiking for enhanced glioma therapy.

The influence of bacterial outer membrane vesicles tumor vaccine on tumor cell proliferation and CD8 + T cell infiltration of mouse with pancreatic cancer / 中华消化外科杂志

Objective:To investigate the influence of bacterial outer membrane vesicles (OMVs) tumor vaccine on tumor cell proliferation and CD8 + T cell infiltration of mouse with pancreatic cancer. Methods:The experimental study was conducted. The ovalbumin (OVA) lentivirus vector plasmid pLV-EF1a-hluc-P2A-mNeongreen-CMV-OVA-3Xflag-P2A-puro was used to construct the mouse pancreatic cancer Pan02-OVA cells. The ClyA-Catchers-OMVs (CC-OMVs) originated from Escherichia coli and labeled antigenic peptide SpyTag-OVA were used to construct the OMVs tumor vaccine. Mouse CD8 + T cells were stimulated by OMVs tumor vaccine, and the effects of OMVs tumor vaccine on inhibiting pancreatic cancer cells proliferation and stimulating CD8 + T cell infiltration were analy-zed by in vitro cell killing assay, including the OMVs tumor vaccine stimulated T cell group and the control T cell group, subcutaneous pancreatic cancer model, including the OMVs tumor vaccine group and the control group, and immunohistochemical staining. Observation indicators: (1) identification of mouse pancreatic cancer Pan02-OVA cells; (2) morphological observation of CC-OMVs; (3) inhibi-tion of mouse pancreatic cancer Pan02-OVA cells by OMVs tumor vaccine specific T cells; (4) inhibi-tion of mouse pancreatic cancer by OMVs tumor vaccine; (5) CD8 + T cell infiltration in pancreatic cancer tissue of mouse stimulated by OMVs tumor vaccine. Measurement data with normal distribu-tion were represented as Mean± SD, and comparison between groups was analyzed using the t test. Count data were described as absolute numbers or percentages. Results:(1) Identification of mouse pancreatic cancer Pan02-OVA cells. Results of laser scanning confocal microscopy showed that the mNeongreen fluorescence was expressed in Pan02-OVA cells infected with the OVA lentivirus vector plasmid of pLV-EF1a-hluc-P2A-mNeongreen-CMV-OVA-3Xflag-P2A-puro. Results of Flow cytometry showed that using the mouse pancreatic cancer Pan02 cells as references, the protein expression rate of Flag on the Pan02-OVA cells was 90.7%. (2) Morphological observation of CC-OMVs. Results of transmission electron microscopy analysis showed that the CC-OMVs were in spherical shape, with a diameter <50 nm. (3) Inhibition of mouse pancreatic cancer Pan02-OVA cells by OMVs tumor vaccine specific T cells. Results of cell proliferation toxicity test showed that the absorbance at 450 nm of mouse pancreatic cancer Pan02-OVA cells was 0.41±0.12 and 1.05±0.15 in the OMVs tumor vaccine-stimulated T cell group and the control T cell group, respectively, showing a significant difference between the two groups ( t=9.54, P<0.05). (4) Inhibition of mouse pancreatic cancer by OMVs tumor vaccine. The weight of subcutaneous tumor tissue in the back of mouse was (81±10)g and (153±17)g in the OMVs tumor vaccine group and the control group, respectively, showing a significant difference between the two groups ( t=8.26, P<0.05). (5) CD8 + T cell infiltration in pancreatic cancer tissue of mouse stimulated by OMVs tumor vaccine. Results of immuno-histochemical staining showed that the numbers of CD8 + T cells staining in the mouse back subcu-taneous tumor tissues was 28.7±3.5 and 9.3±1.5 in the OMVs tumor vaccine group and the control group, respectively, showing a significant difference between the two groups ( t=8.74, P<0.05). Conclusion:Bacterial OMVs tumor vaccine can inhibit proliferation of pancreatic cancer cells and increase the numbers of CD8 + T cells infiltrated in pancreatic cancer tissue of mouse.

Extraction, identification and relative quantification of outer membrane vesicles of Klebsiella pneumoniae / 中华检验医学杂志

Objective:Based on the modified ultracentrifugation method, the outer membrane vesicles (OMV) secreted by Klebsiella pneumoniae were rapidly separated, identified and quantified. Methods:Standard strains of classic Klebsiella Pneumoniae (cKP) purchased from the Clinical Laboratory Center of the National Health Commission, and hypervirulent Klebsiella pneumoniae (hvKP) which was donated by Taiwan University were cultured in M9 basal media for 9 hours, and the OMV were extracted by modified ultracentrifugation. The shape and size of OMV were identified by transmission electron microscopy (TEM), relative quantification by Stewart phospholipids analysis method. Two groups were compared using independent samples t test. Results:It was observed under the TEM that most of the OMV secreted by cKP and hvKP showed spherical vesicle structure and a small part were irregular. The diameter of OMV ranged from 20 to 250 nm, multiple vesicles could be seen in clusters. Relative quantification found that the number of OMV secreted by hvKP were more than cKP ( P<0.05). Conclusions:This study successfully achieved the extraction, identification and quantification of OMV from Klebsiella pneumoniae through the modified ultracentrifugation method, which provided a foundation for further study about the function and mechanism of OMV, and also provided new ideas for the treatment of bacteria. Based on the ultracentrifugation method, the OMV secreted by Klebsiella pneumoniae were rapidly separated and extracted, then identified and quantified.

Reactividad de sueros de ratones inmunizados con vesículas de membrana externa derivadas de Salmonella entérica / Reactivity of sera from mice immunized with outer membrane vesicles derived from Salmonella enterica

La fiebre tifoidea causada por Salmonella Paratyphi A (fiebre paratifoidea) es indistinguible de la producida por Salmonella Typhi y el grado de incidencia ha aumentado en los últimos años, especialmente en el sudeste asiático. Por otro lado, la diarrea y otras complicaciones entéricas causadas por Salmonella Enteritidis y Salmonella Typhimurium continúan siendo un problema de salud grave, especialmente en países subdesarrollados. Las vacunas continúan siendo la forma más efectiva de prevenir estas enfermedades. Existen vacunas basadas en el polisacárido capsular de Salmonella Typhi que protegen contra la fiebre tifoidea; sin embargo, no hay vacunas efectivas licenciadas para uso en humanos que prevengan las enfermedades producidas por los serotipos de Salmonella no tifoideas. El desarrollo de una formulación con capacidad para proteger contra estas enfermedades sigue siendo un desafío para la comunidad científica. En este trabajo se evaluó, mediante Western blot, la reactividad de los sueros de ratones inmunizados por vía subcutánea con formulaciones basadas en vesículas de membrana externa derivadas de Salmonella Paratyphi A, Salmonella Enteritidis y Salmonella Typhimurium, contra los respectivos lisados celulares, para identificar la formulación que induce la mejor respuesta inmunológica cruzada. Los resultados obtenidos indicaron una alta reactividad de todos los sueros a los lisados, sin una diferencia aparente entre ellos. Sin lugar a dudas, se deberán realizar pruebas de inmunogenicidad seguidas de pruebas de retos cruzados para identificar un candidato vacunal. Estos resultados sugieren que las vesículas de membrana externa empleadas en este estudio están compuestas por antígenos posiblemente conservados en los tres serotipos de Salmonella y que pueden inducir una respuesta inmune de amplio espectro y protección cruzada(AU)

Typhoid fever caused by Salmonella Paratyphi A (paratyphoid fever) is indistinguishable from that caused by Salmonella Typhi and the degree of incidence has increased in recent years, especially in Southeast Asia. On the other hand, diarrhea and other enteric complications caused by Salmonella Enteritidis and Salmonella Typhimurium continue to be a serious health problem, especially in underdeveloped countries. Vaccines continue to be the most effective way to prevent these diseases. There are vaccines based on Salmonella Typhi capsular polysaccharide, which protects against typhoid fever; however, there are no effective vaccines licensed for use in humans to prevent disease caused by nontyphoidal Salmonella serotypes. Developing a formulation capable of protecting against these diseases remains a challenge for the scientific community. In this work, the reactivity of the sera of mice immunized subcutaneously with formulations based on Outer Membrane Vesicles (OMV) derived from Salmonella Paratyphi A, Salmonella Enteritidis and Salmonella Typhimurium, was evaluated by Western blot, against the respective cell lysates to identify the formulation that induces the best cross immune response. The results obtained indicated a high reactivity of all the sera to the lysates; without an apparent difference between them. Undoubtedly, immunogenicity tests followed by cross-challenge tests should be performed to identify a vaccine candidate. These results suggest that the OMV used in this study are composed of possibly conserved antigens in the three Salmonella serotypes and that they can induce a broad-spectrum immune response and cross protection(AU)

Doxorubicin-loaded bacterial outer-membrane vesicles exert enhanced anti-tumor efficacy in non-small-cell lung cancer

More efficient drug delivery system and formulation with less adverse effects are needed for the clinical application of broad-spectrum antineoplastic agent doxorubicin (DOX). Here we obtained outer-membrane vesicles (OMVs), a nano-sized proteoliposomes naturally released by Gram-negative bacteria, from attenuated and prepared doxorubicin-loaded O0MVs (DOX-OMV). Confocal microscopy and distribution study observed that DOX encapsulated in OMVs was efficiently transported into NSCLC A549 cells. DOX-OMV resulted in intensive cytotoxic effects and cell apoptosis as evident from MTT assay, Western blotting and flow cytometry due to the rapid cellular uptake of DOX. In A549 tumor-bearing BALB/c nude mice, DOX-OMV presented a substantial tumor growth inhibition with favorable tolerability and pharmacokinetic profile, and TUNEL assay and H&E staining displayed extensive apoptotic cells and necrosis in tumor tissues. More importantly, OMVs' appropriate immunogenicity enabled the recruitment of macrophages in tumor microenvironment which might synergize with their cargo DOX . Our results suggest that OMVs can not only function as biological nanocarriers for chemotherapeutic agents but also elicit suitable immune responses, thus having a great potential for the tumor chemoimmunotherapy.

Propolis polyphenolic compounds affect the viability and structure of Helicobacter pylori in vitro

ABSTRACT To evaluate the anti-Helicobacter pylori activity of the major polyphenol compounds of propolis and their cellular damage, both as single molecule or in combination. Honey bees propolis were fractionated by using CPC and preparative HPLC. Four major polyphenols (chrysin, pinocembrin, galangin and caffeic acid phenethyl ester) were identified by thin layer chromatography-mass spectroscopy and liquid chromatography-mass spectroscopy. These compounds inhibited both ATCC and clinical H. pylori strains, with caffeic acid phenethyl ester being the most active. The four compounds presented minimum inhibitory concentration in the range 256-1024 µg ml−1 and a fractional inhibitory concentration of 64-512 µg ml−1. In mixtures all compounds showed an indifference effect (FIC < 0.15) but chrysin + galangin which was synergistic (FIC = 2.0). Killing curves show a similar behavior as the antibiotic amoxycillin. On the other hand, analyses by transmission electron microscopy at sub inhibitory concentration show vesicle formation and cell lysis after exposition to both individual polyphenol compounds and in mixture. The major compounds of propolis show anti-H. pylori activity both as individual compounds and in mixture. When combined they present mainly indifference but exert a lytic activity upon H. pylori, suggesting a potential bactericidal activity of propolis.

A labelling method for bacterial outer membrane vesicles based on luciferase report gene / 临床检验杂志

Objective@#To establish a labeling method for bacterial outer membrane vesicle (OMV) based on luciferase reporting gene. @*Methods@#By utilizing the characteristics that high abundance of outer membrane protein A (OmpA) presented on the surface of bacterial OMV, the outer membrane protein-luciferase fusion protein was constructed to position the luciferase on the surface of the outer membrane vesicle, and the number of bacterial OMV was evaluated based on the luciferase activity. @*Results@#The OmpA-NanoLuc fusion protein expression vector was constructed successfully, and the outer membrane vesicles secreted by the subject strains after the expression of the fusion protein displayed stable luciferase activity. The number of bacterial outer membrane vesicles was semi-quantitative detrmined by measuring the activity of fluorescein enzyme. @*Conclusion@#A semi-quantitative method based on luciferase labeling was developed for the detection of extracellular vesicles, which could be used to evaluate the secretion level of specific strains.

Estandarización de un ELISA para la cuantificación de anticuerpos IgG contra vesículas de membrana externa de Salmonella Paratyphi A / Standardization of an ELISA for the quantification of IgG antibodies against outer membrane vesicle of Salmonella Paratyphi A

Salmonella Paratyphi A es un patógeno exclusivo de humanos, siendo la segunda causa más común de fiebre entérica en el sudeste asiático. Recientemente la incidencia en este continente ha aumentado, desplazando a Salmonella entérica serotipo Typhi como la primera causa de fiebre entérica. En la actualidad no existen vacunas licenciadas contra S. Paratyphi A. El Instituto Finlay de Vacunas se encuentra trabajando en la obtención de un candidato vacunal basado en vesículas de membrana externa (VME) contra S. Paratyphi A, por lo que se hizo necesario contar con una técnica para la evaluación de su inmunogenicidad. El objetivo de este trabajo fue la estandarización de un ELISA para la cuantificación de anticuerpos IgG contra VME de S. Paratyphi A. Para ello, se determinaron las mejores condiciones de este ensayo en cuanto a concentración óptima de recubrimiento y dilución de trabajo del conjugado. Además, se definió el intervalo y linealidad de la curva, la precisión intra e interensayo, la especificidad y el límite de detección. La curva de calibración se generó con un suero estándar interno y presentó un buen ajuste lineal con un R² =0.98. Los coeficientes de variación en los ensayos de precisión intra e interensayo estuvieron en los intervalos establecidos para cada uno (=10 por ciento, =20 por ciento respectivamente). Los resultados obtenidos avalan el empleo de este ELISA cuantitativo para la evaluación de la inmunogenicidad de formulaciones de VME de S. Paratyphi A en fases de investigación y desarrollo(AU)

Salmonella Paratyphi A, is an exclusive pathogen of humans, being the second most common cause of enteric fever in Southeast Asia. Recently the incidence of this disease in this continent has increased, displacing Salmonella enterica serotype Typhi as the first cause of enteric fever. Currently there are no vaccines licensed against S. Paratyphi A. The Finlay Institute of Vaccines is working on obtaining a vaccine candidate based on outer membrane vesicles (VME) against S. Paratyphi A, so it became necessary to develop a technique for the evaluation of its immunogenicity. The objective of this work was the standardization of an ELISA for the quantification of IgG antibodies against VME of S. Paratyphi A. The best conditions of this assay were determined in terms of optimum concentration of coating and working dilution of the conjugate. In addition, the interval and linearity of the curve, the intra- and inter-assay precision, the specificity and the limit of detection were defined. The calibration curve was generated with an internal standard serum and presented a good linear fit with an R² =0.98. The coefficients of variation in the intra- and interassay precision tests were in the intervals established for each one (=10 percent, =20 percent respectively). The results obtained support the use of this quantitative ELISA for the evaluation of the immunogenicity of VME formulations of S. Paratyphi A in research and development phases(AU)

Identification of the alpha-enolase P46 in the extracellular membrane vesicles of Bacteroides fragilis

BACKGROUND Members of the Bacteroides fragilis group are the most important components of the normal human gut microbiome, but are also major opportunistic pathogens that are responsible for significant mortality, especially in the case of bacteraemia and other severe infections, such as intra-abdominal abscesses. Up to now, several virulence factors have been described that might explain the involvement of B. fragilis in these infections. The secretion of extracellular membrane vesicles (EMVs) has been proposed to play a role in pathogenesis and symbiosis in gram-negative bacteria, by releasing soluble proteins and other molecules. In B. fragilis, these vesicles are known to have haemagglutination and sialidosis activities, and also contain a capsular polysaccharide (PSA), although their involvement in virulence is still not clear. OBJECTIVE The aim of this study was to identify proteins in the EMV of the 638R B. fragilis strain by mass spectrometry, and also to assess for the presence of Bfp60, a surface plasminogen (Plg) activator, previously shown in B. fragilis to be responsible for the conversion of inactive Plg to active plasmin, which can also bind to laminin-1. METHODS B. fragilis was cultured in a minimum defined media and EMVs were obtained by differential centrifugation, ultracentrifugation, and filtration. The purified EMVs were observed by both transmission electron microscopy (TEM) and immunoelectron microscopy (IM). To identify EMV constituent proteins, EMVs were separated by 1D SDS-PAGE and proteomic analysis of proteins sized 35 kDa to approximately 65 kDa was performed using mass spectrometry (MALDI-TOF MS). FINDINGS TEM micrographs proved the presence of spherical vesicles and IM confirmed the presence of Bfp60 protein on their surface. Mass spectrometry identified 23 proteins with high confidence. One of the proteins from the B. fragilis EMVs was identified as an enolase P46 with a possible lyase activity. MAIN CONCLUSIONS Although the Bfp60 protein was not detected by proteomics, α-enolase P46 was found to be present in the EMVs of B. fragilis. The P46 protein has been previously described to be present in the outer membrane of B. fragilis as an iron-regulated protein.

Regulatory mechanisms of gut microbiota on intestinal CYP3A and P-glycoprotein in rats with dextran sulfate sodium-induced colitis / 药学学报

As important constituents of the first-line of host defense barrier, intestinal cytochrome P450 3A (CYP3A) and P-glycoprotein (P-gp) play important roles in disease pathogenesis as well as drug absorption and exposure. Clinical reports and experimental data revealed diminished intestinal CYP3A and P-gp expression accompanying with gut dysbiosis in inflammatory bowel disease. Yet whether gut dysbiosis is associated with the down-regulation of CYP3A and P-gp and the underlying mechanisms are unclear. In this study, daily administration of fresh feces from normal rats and rats with ulcerative colitis (UC) induced by dextran sulfate sodium to normal rats resulted in alterations of gut bacterial compositions. Intestinal CYP3A2 and P-gp were significantly down-regulated in rats receiving UC feces. Outer-membrane vesicles (OMVs) are nano-scale special buds of the outer membrane which are produced by Gram-negative bacteria and mediate diverse functions including interactions within bacterial communities and communications with host. Expressions of CYP3A4 and P-gp mRNA were diminished in human epithelial colorectal adenocarcinoma cells (Caco-2) treated by OMVs from all different groups with OMVs from UC rats or rats receiving UC feces showing more significant effects.Moreover, the OMVs fractions within 30 000-50 000 Daltons from both normal and UC rats elicited more effects than fractions of other molecular weights. Treatment of Caco-2 cells with toll like receptor 4 (TLR4) inhibitor resatorvid (TAK-242) or TLR4 silence RNA (siRNA) blocked CYP3A4 and P-gp down-regulation induced by bacterial OMVs. Taken together, we proved in this study that gut microbiota can down-regulate intestinal CYP3A and P-gp partially through producing OMVs to activate the TLR4 signaling pathway.

Caracterização do secretoma de cepas de Xylella fastidiosa / Characterization of the secretome Xylella fastidiosa strains

As doenças causadas pelo fitopatógeno Xylella fastidiosa, uma bactéria Gram-negativa, devem-se aos seus múltiplos fatores de virulência, tais como formação de biofilme, secreção de enzimas de degradação da parede celular do xilema (CWDE), expressão de proteínas de adesão e produção de vesículas de membrana externa (OMVs). Esses fatores de virulência são controlados por uma via de sinalização mediada por DSF (fatores de sinalização difusíveis de natureza lipídica) e relacionada com percepção de quórum. Nesse trabalho, tivemos como objetivo ampliar a caracterização do secretoma de cepas selvagens e mutantes de X. fastidiosa para evidenciar proteínas e metabólitos potencialmente associados à adaptação ao hospedeiro, virulência e patogenicidade. Desenvolvemos, paralelamente, três estudos empregando como abordagens metodológicas a proteômica, a metabolômica e a transcritômica. No primeiro estudo, comparamos o secretoma (exoproteoma) da cepa Temecula1 selvagem (WT) e do mutante no gene da sintase de DSF (ΔrpfF), o qual exibe fenótipo de hipervirulência em videiras. A este estudo associamos a comparação dos transcritomas dessas cepas. Os resultados mostraram que, mesmo no cultivo in vitro, X. fastidiosa expressa e secreta fatores de virulência previamente conhecidos (lipases-esterases e proteases), além de toxinas (microcinas) que, supostamente, teriam papel de controlar bactérias competidoras pelo mesmo nicho. No segundo estudo caracterizamos a composição de OMVs secretadas no cultivo in vitro por X. fastidiosa Fb7 e 9a5c (cepas isoladas de laranjeiras) e Temecula1 (cepa isolada de videira). Demonstramos que Fb7 produz até 57% mais OMVs que 9a5c e Temecula1 e identificamos um total de 202 proteínas distintas nas OMVs produzidas pelas 3 cepas, ampliando consideravelmente o número de proteínas secretadas por meio de OMVs descrito, até então, para X. fastidiosa. Entre as proteínas enriquecidas, citamos adesinas afimbriais, porinas, lipoproteínas, hidrolases (lipases/esterases, proteases e peptidases) e uma pectina-liase putativa. Destacamos a detecção da enzima L-ascorbato oxidase nas OMVs e sugerimos que esta enzima poderia atuar na depleção do ascorbato produzido pelo hospedeiro vegetal. Além disso, demonstramos, pela primeira vez, que OMVs de X. fastidiosa transportam ácidos graxos da família DSF, sugerindo um papel adicional para OMVs nesse fitopatógeno. Finalmente, no terceiro estudo verificamos alterações relevantes no perfil de metabólitos secretados por X. fastidiosa em resposta a sua interação com metabólitos secretados por Burkholderia phytofirmans, proposta como uma cepa para o biocontrole da doença de Pierce de videiras. Confirmamos que o sobrenadante de B. phytofirmans possui um composto de natureza apolar que induz a formação de biofilme em X. fastidiosa, contudo ainda não foi possível decifrar a natureza química deste composto

The diseases caused by the phytopathogen Xylella fastidiosa, a Gram-negative bacterium, are due to multiple virulence factors, such as biofilm formation, secretion of xylem cell wall degradation enzymes (CWDE), expression of adhesion proteins and production of outer membrane vesicles (OMVs). These virulence factors are controlled by a DSF (diffusible signaling factors of a lipidic nature) mediating signaling pathway and related to quorum sensing perception. In this work, we aimed to extend the characterization of the secretoma of wild type and mutants strains of X. fastidiosa to uncover proteins and metabolites potentially associated to host adaptation, virulence and pathogenicity. We developed three studies in parallel using proteomics, metabolomics and transcriptomics as methodological approaches. In the first study, we compared the secretome (exoproteome) of the wild type strain Temecula1 (WT) and of DSF synthase mutant (ΔrpfF) which exhibits hypervirulence phenotype in grapevines. We also compared the transcriptomes of these strains. Our results showed that, even in in vitro culture, X. fastidiosa expresses and secretes previously known virulence factors (lipasesesterases and proteases), as well as toxins (microcins) that might play a role in controlling competing bacteria in the same niche. In the second study, we characterized the composition of OMVs secreted by in vitro cultures of X. fastidiosa Fb7 and 9a5c (strains isolated from orange trees) and Temecula1 (strain isolated from grapevine). We have shown that Fb7 produces up to 57% more OMVs than the 9a5c and Temecula1. Moreover we identified a total of 202 distinct proteins in the OMVs produced by these three strains, increasing considerably the number of OMVs secreted proteins so far described for X. fastidiosa. Among the proteins enriched in OMVs, we point out afimbrial adhesins, porins, lipoproteins, hydrolases (lipases/esterases, proteases and peptidases) and a putative pectin-lyase. We highlight the detection of the enzyme L-ascorbate oxidase in the OMVs and we suggest that this enzyme could act in the depletion of ascorbate produced by the plant host. In addition, we have demonstrated, for the first time, that X. fastidiosa OMVs transport fatty acids from the DSF family, suggesting an additional role for OMVs in this phytopathogen. Finally, in the third study we verified relevant changes in the profile of metabolites secreted by X. fastidiosa in response to the interaction with metabolites secreted by Burkholderia phytofirmans that has been sugested as a biocontrol strain for Pierce's disease in grapevines. We confirm that the B. phytofirmans supernatant has a non-polar compound that induces biofilm formation in X. fastidiosa, but it has not yet been possible to elucidate the chemical nature of this compound

Rapid Assessment of Microbiota Changes in Individuals with Autism Spectrum Disorder Using Bacteria-derived Membrane Vesicles in Urine

Individuals with autism spectrum disorder (ASD) have altered gut microbiota, which appears to regulate ASD symptoms via gut microbiota-brain interactions. Rapid assessment of gut microbiota profiles in ASD individuals in varying physiological contexts is important to understanding the role of the microbiota in regulating ASD symptoms. Microbiomes secrete extracellular membrane vesicles (EVs) to communicate with host cells and secreted EVs are widely distributed throughout the body including the blood and urine. In the present study, we investigated whether bacteria-derived EVs in urine are useful for the metagenome analysis of microbiota in ASD individuals. To address this, bacterial DNA was isolated from bacteria-derived EVs in the urine of ASD individuals. Subsequent metagenome analysis indicated markedly altered microbiota profiles at the levels of the phylum, class, order, family, and genus in ASD individuals relative to control subjects. Microbiota identified from urine EVs included gut microbiota reported in previous studies and their up- and down-regulation in ASD individuals were partially consistent with microbiota profiles previously assessed from ASD fecal samples. However, overall microbiota profiles identified in the present study represented a distinctive microbiota landscape for ASD. Particularly, the occupancy of g_Pseudomonas, g_Sphingomonas, g_Agrobacterium, g_Achromobacter, and g_Roseateles decreased in ASD, whereas g_Streptococcus, g_Akkermansia, g_Rhodococcus, and g_Halomonas increased. These results demonstrate distinctively altered gut microbiota profiles in ASD, and validate the utilization of urine EVs for the rapid assessment of microbiota in ASD.

Plesiomonas shigelloides exports a lethal cytotoxic-enterotoxin (LCE) by membrane vesicles

ABSTRACT Plesiomonas shigelloides isolated from water in Brazil was previously described as a hemorrhagic heat-labile cytotoxic-enterotoxin producer. We purified this toxin from culture supernatants using ion metallic affinity chromatography (IMAC) followed by molecular exclusion chromatography. The pure toxin presented molecular mass of 50 kDa and isoelectric point (pI) around 6.9 by 2D electrophoresis. When injected intravenously, the purified cytotoxic-enterotoxin induced also severe spasms followed by sudden death of mice. Hence, we entitled it as lethal cytotoxic-enterotoxin (LCE). The presence of membrane vesicles (MVs) on cell surfaces of P. shigelloides was observed by scan electron microscopy (SEM). From these MVs the LCE toxin was extracted and confirmed by biological and serological assays. These data suggest that P. shigelloides also exports this cytotoxic-enterotoxin by membrane vesicles, a different mechanism of delivering extra cellular virulence factors, so far not described in this bacterium.

Mechanism of IL-1β enhance Blood-Brain Tumor Barrier permeability / 中国药理学通报

Aim To study the effect of IL-1β on pro-tein expression of vascular endothelial growth factor in glioma cells and plasma membrane microcapsule struc-ture protein caveolin-1 and plasma membrane vesicles in brain microvascular endothelial cells, and prelimi-narity discuss the possible mechanism of IL-1β opening blood tumor barrier. Methods The tumor barrier mod-el was established by transwell in vitro. The effect of IL-1β on the expression of VEGF in glioma cells and caveolin-1 in brain microvascular endothelial cells was dynamically monitored by Western blot. TEM was used to observe the number of plasma membrane vesicles of brain microvascular endothelial cells. Sodium fluores-cein leakage test was used to assess the permeability of blood tumor barrier after IL-1β. Results The tumor barrier model was successfully established by transwell in vitro. When IL-1β treated the model of blood tumor barrier,the expression of VEGF increased,and reached the peak at 60min,and recovered to the initial state at 120min. The permeability of the blood tumor barrier model was the highest at 60min. In addition,our re-sults also found that,the protein expression of plasma membrane microcapsule structure protein caveolin-1 and number of plasma membrane vesicles in brain mi-crocapsule endothelial cells reached peak at 60 min, subsequently reduced and returned to non drug state at 120min. Conclusion IL-1β increases blood tumor barrier permeability,which may be related to IL-1β in-creasing the number of plasma membrane vesicles through VEGF/ caveolin-1 pathway.

Bacillus spp. or Bacillus spp.-Derived Membrane Vesicles Induce the Intrinsic Pathways of Apoptosis of Human Colon Cancer Cell Lines

The striking increase in colorectal cancer (CRC) has shown the great fatality in Korea for more than 15 years. The leading edge of this rising incidence rate is mainly due to the people's dietary changes in Korea. Some studies have reported that the dietary fiber does not have significant cytotoxic effects on CRC cells, which contrasts to the effects of probiotics. It gives a positive evaluation that the nonpathogenic spore-forming Bacillus species among the probiotics including fermented bacteria might have optimistic effects on CRC incidence rate. Recently, we isolated Bacillus lentus (BL) from Korean soybean fermented food. BL showed the cytotoxic effect on human colon carcinoma cell lines HCT116 and SW480. Interestingly, BL did not have effect on human dermal fibroblast cells and human hepatoma cell line HepG2. It suggested that BL has the target cell-specific cytotoxicity toward human colon carcinoma cells. To clarify the death signaling pathway underlying the BL-induced apoptosis in cancer cells, we analyzed the expression of caspases, Bax and Bcl-2 by western blotting. The apoptotic effects by cytotoxic elements were executed by direct BL contact or membrane-derived vesicles isolated from BL. Treatment of HCT116 with BL activated caspase-9, -3 and increased cleavage form of poly (ADP-ribose) polymerase (PARP). However, caspase-8 activity was not increased by BL. BL-activated intrinsic pathway increased the pro-apoptotic Bax, decreased the anti-apoptotic Bcl-2 proteins on mitochondria, disrupted the mitochondrial membrane potential, and then released the cytochrome c from mitochondria. The membrane-derived vesicles (MVs) from BL induced apoptosis of the HCT116. Here, we propose that BL as a strong candidate for the development of apoptosis-specific anti-tumor agent will give great contribution to the understandings of the tumor-microbe interdisciplinary areas.

Identification of Outer Membrane Vesicles Derived from Orientia tsutsugamushi

Orientia tsutsugamushi, a causative pathogen of Scrub typhus, is a gram-negative intracellular bacterium. Outer membrane vesicles (OMVs) are produced from the membrane of bacteria and play many roles related to the survival of the pathogen. However, there have been no reports confirming whether O. tsutsugamushi indeed produce OMVs. O. tsutsugamushi boryong was cultured in ECV-304 cells for the purification of OMVs. Western blot analysis and immunoenrichment using anti-O. tsutsugamushi monoclonal antibody and electron microscopy were employed for identification and characterization of OMVs. We confirm the presence of OMVs derived from O. tsutsugamushi, and also found that those OMVs contain a major surface antigen of 56-kDa protein and variant immunogenic antigens.

Efeito imunomodulador de vesículas de membrana obtidas de macrófagosinfectados por leishmania sobre macrófagos não infectados / Immunomodulatory Effect of membrane vesicles obtained from macrophages Leishmania infection of uninfected macrophages

Vesículas de membrana (VMs) derivadas de macrófagos infectados com microorganismos intracelulares têm capacidade inflamatória. Estas vesículas podem conter antígenos do patógeno, carrear moléculas de MHC II e componentes celulares que podem atuar como PAMPs ou DAMPs induzindo resposta imune. Na infecção por Leishmania, a indução de uma resposta do tipo Th1 é crucial para promoção de proteção contra o parasito. O objetivo do trabalho foi avaliar a capacidade imunomoduladora de VMs derivadas de macrófagos infectados com L. amazonensis sobre a produção de citocinas por outros macrófagos. VMs foram visualizadas por microscopia eletrônica tanto em preparações celulares como no precipitado obtido por sucessivas centrifugações de sobrenadantes de cultivos celulares. Foi observada por citometria de fluxo a presença de marcadores celulares específicos (F4/80 e CD11b) nas VMs, bem como MHC II. O tratamento de macrófagos não infectados com VMs derivadas de macrófagos infectados com L. amazonensis ocasionou aumento consistente da produção de IL-12p70 e IL-1β. Estas vesículas poderiam, portanto, favorecer a modulação da resposta imune em favor do combate ao parasito.

Membrane vesicles (MV) derived macrophages infected with intracellular microbes are proinflammatory. These vesicles contain antigens of the pathogen, carry MHC II molecules and cellular components that can act as PAMPs or DAMPs inducing immune responses. In Leishmania infection the induction of a Th1 response is crucial for the protection against the parasite. The aim of the study was to evaluate whether vesicles derived from macrophages infected with L. amazonensis had the capacity to modulate the response of other macrophages. MV were visualized by electron microscopy in cellular preparations as well in the precipitate obtained by centrifugation of cell supernatants. Flow cytometry revealed the presence of specific cellular markers (F4/80 and CD11b) in the MV, as well as MHC II. Treatment of noninfected macrophages with MV derived from L. amazonensis-infected macrophages consistently caused increased production of IL-12p70 and IL-1β. These vesicles can favor the modulation of the immune response in favor of combating the parasite.

Staphylococcus aureus Membrane Vesicles and Its Potential Role in Bacterial Pathogenesis

The production of extracellular vesicles is a ubiquitous process in both Gram-negative and Gram-positive bacteria. Gram-negative bacteria produce and secrete outer membrane vesicles during in vitro culture and in vivo infection and their contribution to bacterial pathogenesis has been well characterized. However, little is known about extracellular vesicles in Gram-positive bacteria. Until now, only few Gram-positive bacterial species, Staphylococcus aureus, Bacillus anthracis, B. cereus, and B. subtilis, have been found to produce membrane vesicles (MVs), but their contribution to bacterial pathogenesis has not been understood. Here, I discuss S. aureus MVs in terms of MV production, interaction of MVs with host cells, and immune response against MVs to understand its potential role in S. aureus pathogenesis.

Effects of ethanol on Na+-dependent solute uptake in rabbit renal brush-border membrane vesicles

This study was undertaken to examine the effect of ethanol on Na+-dependent transport systems (glucose, phosphate, and dicarboxylate) in renal brush-border membrane vesicles (BBMV). Ethanol inhibited Na+-dependent uptakes of glucose, phosphate, and succinate in a dose-dependent manner, but not the uptakes of Na+-independent. The H+/TEA antiport was reduced by 8% ethanol. Kinetic analysis showed that ethanol caused a decrease in Vmax of three transport systems, leaving Km values unchanged. Ethanol decreased phlorizin binding, which was closely correlated with the decrease in Vmax of Na+-glucose uptake. These results indicate that ethanol inhibits Na+-dependent uptakes of glucose, phosphate, and dicaboxylate and that the reduction in Vmax of Na+-glucose uptake is caused by a decrease in the number of active carrier proteins in the membrane.

Increase of intracellular Ca2+ concentration by Vibrio vulnificus cytolysin in rat platelets; triggering mechanism of platelet cytolysis

Vibrio vulnificus cytolysin caused platelet cytolysis and increased intracellular calcium concentration ((Ca2+))i) of rat platelets in a concentration-dependent manner. In the presence of V. vulnificus cytolysin (3 HU/ml), lactate dehydrogenase (LDH) activity was increased from 1.3+/-0.4% of control to 64.3+/-3.4% in platelet suspension buffer. In Ca2+-free platelet suspension buffer, however, V. vulnificus cytolysin did not induce (Ca2+)i increase and LDH release. Addition of EGTA (2 mM) to suspension buffer after the initial Ca2+ influx reversed (Ca2+)i to the control level. However, a Ca2+ channel blocker verapamil (20 muM) or mefenamic acid (20 muM) did not inhibit V. vulnificus cytolysin-induced (Ca2+)i increase and LDH release. Divalent cations such as Co2+, Cd2+ or Mn2+ (2 mM each) also did not alter V. vulnificus cytolysin-induced (Ca2+)i increase and LDH release. V. vulnificus cytolysin (3 HU/ml)-induced calcium influx was completely blocked by lanthanum (2 mM). Lanthanum (2 mM) also completely blocked V. vulnificus cytolysin (3 HU/ml)-induced LDH release. Osmotic protectants such as, raffinose, sucrose or PEG600 (50 mM each) did not inhibit the lytic activity of V. vulnificus cytolysin. In conclusion, lanthanum sensitive Ca2+ influx plays a significant role in Vibrio vulnificus cytolysin-induced platelet cytolysis and thrombocytopenia in V. vulnificus infection.