Antibacterial Effects of Leaf Extract of Nandina domestica and the Underlined Mechanism.

AIM: The study was conducted to investigate the antibacterial and antiasthmatic effects of Nandina domestica leaf extract, to find out its active components, and to assess its safety issue. METHODS: (1) Solid-phase agar dilution method was used for antibacterial activity test of nandina leaf extract and the change of bacterial morphology after treatment was observed under the transmission microscope; (2) guinea pig model of asthma was used to test the asthma prevention effect of nandina leaf extract; (3) alkaloids and flavones were separated from nandina leaf extract and were further analyzed with HPLC-MS; (4) mice model was used to assessment of the safety issue of nandina leaf extract. RESULTS: (1) Nandina leaf extract inhibited the growth of bacteria and destroyed bacterial membrane; (2) nandina leaf extract alleviated animal allergy and asthma; (3) the components reextracted by ethyl acetate were active, in which alkaloids inhibited Gram-positive bacteria and prevented asthma and flavones inhibited Gram-negative bacteria; (4) nandina leaf extract had no toxic effect on mice. CONCLUSION: Nandina leaves inhibit bacterial growth and prevent asthma through alkaloids and flavones, which had integrated function against chronic bronchitis. This study provided theoretical basement for producing new Chinese medicine against chronic bronchitis.

Hsp90 inhibitor induces KG-1a cell differentiation and apoptosis via Akt/NF-κB signaling.

Heat-shock protein 90 (Hsp 90) acts as a molecular chaperone that maintains protein stability and regulates cell proliferation, survival, differentiation and apoptosis. The present study investigated the effect of Hsp90 inhibition on human acute myeloid leukemia (AML) cells using the novel small-molecule inhibitor SNX-2112. We found that SNX-2112 more potently inhibited KG-1a cell growth than the classical Hsp90 inhibitor 17-(2-dimethylaminoethyl)amino­17-demethoxygeldanamycin as determined by CCK-8 assay. Flow cytometry was used to examine the cell cycle, differentiation, and apoptosis, and western blotting and qRT-PCR were used to analyze the underlying mechanism. The results revealed that low concentrations of SNX-2112 arrested the cells in the G2/M phase and induced their differentiation and apoptosis, possibly by suppressing Akt and inhibitor of κB kinase, a component of the nuclear factor (NF)-κB signaling pathway. We also found that SNX-2112 increased the expression of the differentiation transcription factors PU.1 and CCAAT­enhancer-binding protein-α. Thus, SNX-2112 induced KG-1a cell differentiation, cell cycle arrest and apoptosis via modulation of Akt and NF-κB signaling, suggesting that it is a promising therapeutic agent for the treatment of AML.

miR-150 Suppresses the Proliferation and Tumorigenicity of Leukemia Stem Cells by Targeting the Nanog Signaling Pathway.

Proliferation, a key feature of cancer cells, accounts for the majority of cancer-related diseases resulting in mortality. MicroRNAs (miRNAs) plays important post-transcriptional modulation roles by acting on multiple signaling pathways, but the underlying mechanism in proliferation and tumorigenicity is unclear. Here, we identified the role of miR-150 in proliferation and tumorigenicity in leukemia stem cells (LSCs; CD34+CD38- cells). miR-150 expression was significantly down-regulated in LSCs from leukemia cell lines and clinical samples. Functional assays demonstrated that increased miR-150 expression inhibited proliferation and clonal and clonogenic growth, enhanced chemosensitivity, and attenuated tumorigenic activity of LSCs in vitro. Transplantation animal studies revealed that miR-150 overexpression progressively abrogates tumor growth. Immunohistochemistry assays demonstrated that miR-150 overexpression enhanced caspase-3 level and reduced Ki-67 level. Moreover, luciferase reporter assays indicated Nanog is a direct and functional target of miR-150. Nanog silencing using small interfering RNA recapitulated anti-proliferation and tumorigenicity inhibition effects. Furthermore, miR-150 directly down-regulated the expression of other cancer stem cell factors including Notch2 and CTNNB1. These results provide insights into the specific biological behavior of miR-150 in regulating LSC proliferation and tumorigenicity. Targeting this miR-150/Nanog axis would be a helpful therapeutic strategy to treat acute myeloid leukemia.

Reciprocal activation between STAT3 and miR-181b regulates the proliferation of esophageal cancer stem-like cells via the CYLD pathway.

BACKGROUND: Recent studies have suggested that cancer cells contain subpopulations that can initiate tumor growth, self-renew, and maintain tumor cell growth. However, for esophageal cancer cells, the relationship between STAT3, microRNAs and cancer stem cells remains unclear. METHODS: Serum-free culture was used to enrich esophageal cancer stem-like cells (ECSLC). Flow cytometry determined the proportion of ECSLC. qPCR were performed to examine expression level of stemness factors, mesenchymal markers, ATP-binding cassette (ABC) transporters, STAT3, miR-181b, CYLD. Western blot were performed to analyze the expression of STAT3, p-STAT3 and CYLD (cylindromatosis). BALB/c mice xenograft studies were conducted to evaluate the tumorigenicity of enriched ECSLC. Sphere formation assay and colony formation assays were employed to analyze the relationship between STAT3 and miR-181b. Luciferase assays were used to evaluate activity which CYLD is a target of miR-181b. RESULTS: Sphere formation cells (SFCs) with properties of ECSLC were enriched. Enriched SFCs in serum-free suspension culture exhibited cancer stem-like cell properties and increased single-positive CD44 + CD24-, stemness factor, mesenchymal marker expression ABC transporters and tumorigenicity in vivo compared with the parental cells. Additionally, we found that reciprocal activation between STAT3 and miR-181b regulated SFCs proliferation. Moreover, STAT3 directly activated miR-181b transcription in SFCs and miR-181b then potentiated p-STAT3 activity. Luciferase assays indicated that CYLD was a direct and functional target of miR-181b. CONCLUSION: The mutual regulation between STAT3 and miR-181b in SFCs was required for proliferation and apoptosis resistance. STAT3 and miR-181b control each other's expression in a positive feedback loop that regulates SFCs via CYLD pathway. These findings maybe is helpful for targeting ECSLC and providing approach for esophageal cancer treatments.

Isolation and characterization of two novel plasmids from pathogenic Leptospira interrogans serogroup Canicola Serovar Canicola strain Gui44.

BACKGROUND: Previous genomic analysis of pathogenic Leptospira has identified two circular chromosomes but no plasmid. This study aims to investigate potential extrachromosomal elements of L.interrogans serovar Canicola strain Gui44. METHODOLOGY: Two novel plasmids, pGui1 and pGui2, were isolated from the pathogenic strain Gui44, using a modified alkaline lysis method. Southern blotting was performed to determine the presence and size of them. Then, 454 and Hiseq sequencing were applied to obtain and analyze the complete sequences of the two plasmids. Furthermore, real-time quantitative PCR and next-generation sequencing were used to compare relative copy numbers of the two plasmids with that of the chromosomes. Finally, after serial passages in vitro for more than 2 years, the strain Gui44 was subsequently re-sequenced to estimate stability of the two plasmids. PRINCIPAL FINDINGS: The larger plasmid, pGui1, 74,981 base pairs (bp) in length with GC content of 34.63%, possesses 62 open reading frames (ORFs). The smaller plasmid, pGui2, is 66,851 bp in length with GC content of 33.33%, and contains 63 ORFs. The replication initiation proteins encoded by pGui1 and pGui2 demonstrate significant sequence similarity with LA1839 (86% and 88%), a well-known replication protein in another pathogenic L.interrogans serovar Lai strain Lai, suggesting the ability for autonomous plasmid replication. Quantitative PCR and next-generation sequencing confirms a single copy of both plasmids and their stable presence in the strain Gui44 with in vitro serial passages after more than 2 years. Interestingly, the two plasmids both contain a significant number of novel genes (35 in pGui1 and 52 in pGui2). CONCLUSIONS: This report confirms the presence of two separate circular plasmids in serovar Canicola strain Gui44 and provides a new understanding of genomic organization, adaptation, evolution and pathogenesis of Leptospira, which will aid in the development of in vivo genetic manipulation systems in pathogenic Leptospira species.

Leptospira interrogans enolase is secreted extracellularly and interacts with plasminogen.

Leptospira interrogans is the agent for leptospirosis, an important zoonosis in humans and animals across the globe. Surface proteins of invading pathogens, such as L. interrogans, are thought to be responsible for successful microbial persistence in vivo via interaction with specific host components. In particular, a number of invasive infectious agents exploit host proteolytic pathways, such as one involving plasminogen (Pg), which aid in efficient pathogen dissemination within the host. Here we show that L. interrogans serovar Lai binds host Pg and that the leptospiral gene product LA1951, annotated as enolase, is involved in this interaction. Interestingly, unlike in related pathogenic Spirochetes, such as Borrelia burgdorferi, LA1951 is not readily detectable in the L. interrogans outer membrane. We show that the antigen is indeed secreted extracellularly; however, it can reassociate with the pathogen surface, where it displays Pg-binding and measurable enzymatic activity. Hamsters infected with L. interrogans also develop readily detectable antibody responses against enolase. Taken together, our results suggest that the L. interrogans enolase has evolved to play a role in pathogen interaction with host molecules, which may contribute to the pathogenesis of leptospirosis.

A surface enolase participates in Borrelia burgdorferi-plasminogen interaction and contributes to pathogen survival within feeding ticks.

Borrelia burgdorferi, a tick-borne bacterial pathogen, causes a disseminated infection involving multiple organs known as Lyme disease. Surface proteins can directly participate in microbial virulence by facilitating pathogen dissemination via interaction with host factors. We show here that a fraction of the B. burgdorferi chromosomal gene product BB0337, annotated as enolase or phosphopyruvate dehydratase, is associated with spirochete outer membrane and is surface exposed. B. burgdorferi enolase, either in a recombinant form or as a membrane-bound native antigen, displays enzymatic activities intrinsic to the glycolytic pathway. However, the protein also interacts with host plasminogen, potentially leading to its activation and resulting in B. burgdorferi-induced fibrinolysis. As expected, enolase displayed consistent expression in vivo, however, with a variable temporal and spatial expression during spirochete infection in mice and ticks. Despite an extracellular exposure of the antigen and a potential role in host-pathogen interaction, active immunization of mice with recombinant enolase failed to evoke protective immunity against subsequent B. burgdorferi infection. In contrast, enolase immunization of murine hosts significantly reduced the acquisition of spirochetes by feeding ticks, suggesting that the protein could have a stage-specific role in B. burgdorferi survival in the feeding vector. Strategies to interfere with the function of surface enolase could contribute to the development of novel preventive measures to interrupt the spirochete infection cycle and reduce the incidences of Lyme disease.

[Study on manufacturing materials of imitation snails].

OBJECTIVE: To make imitation snails by using substances with chemotaxis to Schistosoma japonicum miracidia. METHODS: The imitation snails were made by using Fe3+, gelatin and agar. The modified comparison method of Roberts was used to observe the chemotaxis of imitation snails and snail conditioned water (SCW) to Schistosoma japonicum miracidia. RESULTS: The mixture consisting of 0.1 or 0.5 mol/L Fe3+, 9% or 10% gelatin, and that consisting of 0.5 mol/L Fe3+, 9% gelatin, 2% or 1% agar could be used to make the imitation snails. The chemotaxis of imitation snails made by the mixtures above was stronger than that of SCW. CONCLUSION: The mixtures made by certain proportion of Fe3+, gelatin or gelatin and agar can be used to make imitation snails.

Development of O-antigen gene cluster-specific PCRs for rapid typing six epidemic serogroups of Leptospira in China.

BACKGROUND: Leptospira is the causative agent of leptospirosis. The O-antigen is the distal part of the lipopolysaccharide, which is a key component of outer membrane of Gram-negative bacteria and confers serological specificity. The epidemiology and clinical characteristics of leptospirosis are relative to the serology based taxonomic unit. Identification of Leptospira strains by serotyping is laborious and has several drawbacks. RESULTS: In this study, the O-antigen gene clusters of four epidemic Leptospira serogroups (serogroup Canicola, Autumnalis, Grippotyphosa and Hebdomadis) in China were sequenced and all genes were predicted in silico. Adding published sequences of two serogroups, Icterohaemorrhagiae (strain Lai and Fiocruz L1-130) and Sejroe (strain JB197 and L550), we identified six O-antigen-specific genes for six epidemic serogroups in China. PCR assays using these genes were developed and tested on 75 reference strains and 40 clinical isolates. CONCLUSION: The results show that the PCR-based assays can be reliable and alternative means for rapid typing of these six serogroups of Leptospira.

Molecular characterization of the pL40 protein in Leptospira interrogans.

Leptospirosis is a widespread zoonotic disease caused by pathogenic leptospires. The identification of outer membrane proteins (OMPs) conserved among pathogenic leptospires, which are exposed on the leptospiral surface and expressed during mammalian infection, has become a major focus of leptospirosis research. pL40, a 40 kDa protein coded by the LA3744 gene in Leptospira interrogans, was found to be unique to Leptospira. Triton X-114 fractionation and flow cytometry analyses indicate that pL40 is a component of the leptospiral outer membrane. The conservation of pL40 among Leptospira strains prevalent in China was confirmed by both Western blotting and PCR screening. Furthermore, the pL40 antigen could be recognized by sera from guinea pigs and mice infected with low-passage L. interrogans. These findings indicate that pL40 may serve as a useful serodiagnostic antigen and vaccine candidate for L. interrogans.

Identification of a novel prophage-like gene cluster actively expressed in both virulent and avirulent strains of Leptospira interrogans serovar Lai.

DNA microarray analysis was used to compare the differential gene expression profiles between Leptospira interrogans serovar Lai type strain 56601 and its corresponding attenuated strain IPAV. A 22-kb genomic island covering a cluster of 34 genes (i.e., genes LA0186 to LA0219) was actively expressed in both strains but concomitantly upregulated in strain 56601 in contrast to that of IPAV. Reverse transcription-PCR assays proved that the gene cluster comprised five transcripts. Gene annotation of this cluster revealed characteristics of a putative prophage-like remnant with at least 8 of 34 sequences encoding prophage-like proteins, of which the LA0195 protein is probably a putative prophage CI-like regulator. The transcription initiation activities of putative promoter-regulatory sequences of transcripts I, II, and III, all proximal to the LA0195 gene, were further analyzed in the Escherichia coli promoter probe vector pKK232-8 by assaying the reporter chloramphenicol acetyltransferase (CAT) activities. The strong promoter activities of both transcripts I and II indicated by the E. coli CAT assay were well correlated with the in vitro sequence-specific binding of the recombinant LA0195 protein to the corresponding promoter probes detected by the electrophoresis mobility shift assay. On the other hand, the promoter activity of transcript III was very low in E. coli and failed to show active binding to the LA0195 protein in vitro. These results suggested that the LA0195 protein is likely involved in the transcription of transcripts I and II. However, the identical complete DNA sequences of this prophage remnant from these two strains strongly suggests that possible regulatory factors or signal transduction systems residing outside of this region within the genome may be responsible for the differential expression profiling in these two strains.

Genetic diversity among major endemic strains of Leptospira interrogans in China.

BACKGROUND: Leptospirosis is a world-widely distributed zoonosis. Humans become infected via exposure to pathogenic Leptospira spp. from contaminated water or soil. The availability of genomic sequences of Leptospira interrogans serovar Lai and serovar Copenhageni opened up opportunities to identify genetic diversity among different pathogenic strains of L. interrogans representing various kinds of serotypes (serogroups and serovars). RESULTS: Comparative genomic hybridization (CGH) analysis was used to compare the gene content of L. interrogans serovar Lai strain Lai with that of other 10 L. interrogans strains prevailed in China and one identified from Brazil using a microarray spotted with 3,528 protein coding sequences (CDSs) of strain Lai. The cutoff ratio of sample/reference (S/R) hybridization for detecting the absence of genes from one tested strain was set by comparing the ratio of S/R hybridization and the in silico sequence similarities of strain Lai and serovar Copenhageni strain Fiocruz L1-130. Among the 11 strains tested, 275 CDSs were found absent from at least one strain. The common backbone of the L. interrogans genome was estimated to contain about 2,917 CDSs. The genes encoding fundamental cellular functions such as translation, energy production and conversion were conserved. While strain-specific genes include those that encode proteins related to either cell surface structures or carbohydrate transport and metabolism. We also found two genomic islands (GIs) in strain Lai containing genes divergently absent in other strains. Because genes encoding proteins with potential pathogenic functions are located within GIs, these elements might contribute to the variations in disease manifestation. Differences in genes involved in O-antigen biosynthesis were also identified for strains belonging to different serogroups, which offers an opportunity for future development of genomic typing tools for serological classification. CONCLUSION: CGH analyses for pathogenic leptospiral strains prevailed in China against the L. interrogans serovar Lai strain Lai CDS-spotted microarrays revealed 2,917 common backbone CDSs and strain specific genes encoding proteins mainly related to cell surface structures and carbohydrated transport/metabolism. Of the 275 CDSs considered absent from at least one of the L. interrogans strains tested, most of them were clustered in the rfb gene cluster and two putative genomic islands (GI A and B) in strain Lai. The strain-specific genes detected via this work will provide a knowledge base for further investigating the pathogenesis of L interrogans and/or for the development of effective vaccines and/or diagnostic tools.

In silico and microarray-based genomic approaches to identifying potential vaccine candidates against Leptospira interrogans.

BACKGROUND: Currently available vaccines against leptospirosis are of low efficacy, have an unacceptable side-effect profile, do not induce long-term protection, and provide no cross-protection against the different serovars of pathogenic leptospira. The current major focus in leptospirosis research is to discover conserved protective antigens that may elicit longer-term protection against a broad range of Leptospira. There is a need to screen vaccine candidate genes in the genome of Leptospira interrogans. RESULTS: Bioinformatics, comparative genomic hybridization (CGH) analysis and transcriptional analysis were used to identify vaccine candidates in the genome of L. interrogans serovar Lai strain #56601. Of a total of 4727 open reading frames (ORFs), 616 genes were predicted to encode surface-exposed proteins by P-CLASSIFIER combined with signal peptide prediction, alpha-helix transmembrane topology prediction, integral beta-barrel outer membrane protein and lipoprotein prediction, as well as by retaining the genes shared by the two sequenced L. interrogans genomes and by subtracting genes with human homologues. A DNA microarray of L. interrogans strain #56601 was constructed for CGH analysis and transcriptome analysis in vitro. Three hundred and seven differential genes were identified in ten pathogenic serovars by CGH; 1427 genes had high transcriptional levels (Cy3 signal > or = 342 and Cy5 signal > or = 363.5, respectively). There were 565 genes in the intersection between the set encoding surface-exposed proteins and the set of 307 differential genes. The number of genes in the intersection between this set of 565 and the set of 1427 highly transcriptionally active genes was 226. These 226 genes were thus identified as putative vaccine candidates. The proteins encoded by these genes are not only potentially surface-exposed in the bacterium, but also conserved in two sequenced L. interrogans. Moreover, these genes are conserved among ten epidemic serovars in China and have high transcriptional levels in vitro. CONCLUSION: Of the 4727 ORFs in the genome of L. interrogans, 226 genes were identified as vaccine candidates by bioinformatics, CGH and transcriptional analysis on the basis of the theory of reverse vaccinology. The proteins encoded by these genes might be useful as vaccine candidates as well as for diagnosis of leptospirosis.

Genome-wide transcriptional analysis of temperature shift in L. interrogans serovar lai strain 56601.

BACKGROUND: Leptospira interrogans is an important mammalian pathogen. Transmission from an environmental source requires adaptation to a range of new environmental conditions in the organs and tissues of the infected host. Several studies have shown that a shift in culture temperature from 28 degrees C to 37 degrees C, similar to that encountered during infection of a host from an environmental source, is associated with differential synthesis of several proteins of the outer membrane, periplasm and cytoplasm. The whole genome of the Leptospira interrogans serogroup Icterohaemorrhagiae serovar lai type strain #56601 was sequenced in 2003 and microarrays were constructed to compare differential transcription of the whole genome at 37 degrees C and 28 degrees C. RESULTS: DNA microarray analyses were used to investigate the influence of temperature on global gene expression in L. interrogans grown to mid-exponential phase at 28 degrees C and 37 degrees C. Expression of 106 genes differed significantly at the two temperatures. The differentially expressed genes belonged to nine functional categories: Cell wall/membrane biogenesis genes, hemolysin genes, heat shock proteins genes, intracellular trafficking and secretion genes, two-component system and transcriptional regulator genes, information storage and processing genes, chemotaxis and flagellar genes, metabolism genes and genes with no known homologue. Real-time reverse transcription-PCR assays confirmed the microarray data. CONCLUSION: Microarray analyses demonstrated that L. interrogans responds globally to temperature alteration. The data delineate the spectrum of temperature-regulated gene expression in an important human pathogen and provide many new insights into its pathogenesis.