- [Show abstract] [Hide abstract] ABSTRACT: Background The natural course of otitis media (OM) in most children is acute and self-limiting; however, approximately 10%-20% of children can experience persistent or recurrent OM. Determining the host factors that influence outcome of OM will help us design better therapies. This study focused on the role of Toll-like receptor 2 (TLR2) in a pneumococcal OM mouse model.Methods The middle ears (MEs) of wild-type (WT) and TLR2(-/-) mice were inoculated with Streptococcus pneumoniae (Spn) serotype 19F via transbullar injection. ME TLR2 expression in WT mice was determined by qRT-PCR and immunofluorescence. ME pathological manifestations, inflammatory response and pneumococcal clearance between WT and TLR2(-/-) mice were compared after Spn inoculation.ResultsTLR2 expression in ME mucosa was markedly enhanced following infection with Spn in WT mice. In contrast to WT mice, TLR2(-/-) mice exhibited unaffected early ME inflammatory response. During late stage of ME infection, however, the absence of TLR2 can lead to reduced macrophage recruitment, impaired Spn clearance and prolonged ME inflammation.Conclusion Our results demonstrate that TLR2 signaling is critical for bacterial clearance and timely resolution of inflammation in OM induced by Spn.
- [Show abstract] [Hide abstract] ABSTRACT: Interaction between virulence factors of streptococcus pneumoniae and innate immune receptors elicits host responses through specific signaling pathways during infection. Insights into the signaling events may provide a better knowledge of the starting events for host-pathogen interaction. Here we demonstrated a significant induction of innate immune response elicited by recombinant streptococcus pneumoniae endopeptidase O (rPepO), a newer pneumococcal virulence protein, both in vivo and in vitro. Intratracheal instillation of rPepO protein resulted in significant increase of cytokines production and neutrophils infiltration in mouse lungs. TLR2 or TLR4 deficient mice subjected to rPepO treatment showed decreased cytokines production, reduced neutrophils infiltration and intensified tissue injury as compared with WT mice. Upon stimulation, cytokines TNF-α, IL-6, CXCL1 and CXCL10 were produced by peritoneal exudate macrophages (PEMs) in a TLR2 and TLR4 dependent manner. rPepO- induced cytokines production was markedly decreased in TLR2 or TLR4 deficient PEMs. Further study revealed that cytokines induction relied on the rapid phosphorylation of p38, Akt and p65, not the activation of ERK or JNK. While in TLR2 or TLR4 deficient PEMs the activation of p65 was undetectable. Taken together, these results indicate for the first time that the newer pneumococcal virulence protein PepO activates host innate immune response partially through TLR2 and TLR4 signaling pathways.
- [Show abstract] [Hide abstract] ABSTRACT: To develop a mouse model for acute otitis media (AOM) via transbullar injection method and evaluate its feasibility and practicability. The middle ears (ME) of C57BL/6 mice were inoculated via transbullar injection method with 5 µl streptococcus pneumoniae (S.pn) 19F suspension (1×10(7) CFU/ml), and the control group was inoculated equivalent phosphate buffered solution (PBS). Behavior changes were observed daily following inoculation. The ME tissues for histological examination and the middle ear lavage fluid (MELF) for total cells quantification, S.pn load determination and cytokines measurement were collected at 12 h, day 1, 2, 3, 5, 7 after inoculation, respectively. Within 24 hours after instillation, the density of S.pn and the level of acute inflammatory cytokines in ME cavity increased rapidly, some mucosal hyperplasia was evident and leukocytic infiltration (primarily neutrophils) began. The level of ME inflammatory response reached maximal at 2-3 days after inoculation, with extensive effusion, leukocytic infiltration and mucosal thickening. Meanwhile, the density of S.pn decreased gradually. Bacterial clearance was completed by day 5 with extensive resolution of ME inflammation, although mucosal hyperplasia did not resolute until day 7. A mouse model for AOM is successfully established via transbullar injection method, laying foundation for future study of AOM.
- [Show abstract] [Hide abstract] ABSTRACT: Airway inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and asthma are associated with elevated expression of IL-32, a recently described cytokine that appears to play a critical role in inflammation. However, thus far, the regulation of pulmonary IL-32 production has not been fully established. We examined the expression of IL-32 by TNF-α in primary human lung fibroblasts. Human lung fibroblasts were cultured in the presence or absence of TNF-α and/or other cytokines/TLR ligands or various signaling molecule inhibitors to analyze the expression of IL-32 by quantitative RT-PCR and enzyme-linked immunosorbent assay. Next, activation of Akt and JNK signaling pathways were investigated by Western blot. IL-32 mRNA of 4 spliced isoforms (α, β, γ, and δ) was up-regulated upon TNF-α stimulation, which was associated with a significant IL-32 protein release from TNF-α-activated human lung fibroblasts. The combination of IFN-γ and TNF-α induced enhanced IL-32 release in human lung fibroblasts, whereas IL-4, IL-17A, IL-27 and TLR ligands did not alter IL-32 release in human lung fibroblasts either alone, or in combination with TNF-α. Furthermore, the activation of Akt and JNK pathways regulated TNF-α-induced IL-32 expression in human lung fibroblasts, and inhibition of the Akt and JNK pathways was able to suppress the increased release of IL-32 to nearly the basal level. These data suggest that TNF-α may be involved in airway inflammation via the induction of IL-32 by activating Akt and JNK signaling pathways. Therefore, the TNF-α/IL-32 axis may be a potential therapeutic target for airway inflammatory diseases. This article is protected by copyright. All rights reserved.
- [Show abstract] [Hide abstract] ABSTRACT: Interaction between pneumococcal virulence factors and innate immune receptors triggers host responses via specific signaling pathways after infection. By generating deficient mutant, we showed here that, compared with wild-type parent strain, glycosyl hydrolase 25 relating to invasion protein mutant strain was impaired in rapid dissemination into vessel and caused less severe inflammation in mice lungs. Further study demonstrated that the lack of this protein in Streptococcus pneumoniae caused an increased susceptibility to the whole blood or neutrophils, while this impairment could be recovered by supplementing recombinant GHIP (rGHIP). Additionally, secreted glycosyl hydrolase 25 relating to invasion protein could be detected in culture medium, and purified protein was capable to induce the release of tumor necrosis factor alpha and interleukin 6 from peritoneal macrophage. Further investigations revealed that the induction of interleukin 6 by this virulence factor depended on the phosphorylation of c-Jun N- terminal kinase and p38 mitogen activated protein kinase and Toll-like receptor 2. Taken together, glycosyl hydrolase 25 relating to invasion protein, a novel pneumococcal virulence factor, appeared to play a critical role in bacterial survival and the induction of host innate immune response during pneumococcal infection. This article is protected by copyright. All rights reserved.
- [Show abstract] [Hide abstract] ABSTRACT: Rapid and accurate identification of mycobacteria to the species level is important to provide epidemiological information and to guide the appropriate treatment, especially identification of the Mycobacterium tuberculosis (MTB) which is the leading pathogen causing tuberculosis. The genetic marker named as Mycobacterium tuberculosis specific sequence 90 (mtss90) was screened by a bioinformatics software and verified by a series of experiments. To test its specificity, 266 strains of microorganisms and human cells were used for the mtss90 conventional PCR method. Moreover, the efficiency of mtss90 was evaluated by comparing 16S rDNA (Mycobacterium genus-specific), IS6110 (specific identification of MTB complex), mtp40 (MTB-specific) and PNB/TCH method (traditional bacteriology testing) in Mycobacterium strains. All MTB isolates were mtss90 positive. No amplification was observed from any other tested strains with M. microti as an exception. Compared with the traditional PNB/TCH method, the coincidence rate was 99.1 % (233/235). All of the mtss90 positive strains were IS6110 and 16S rDNA positive, indicating a 100 % coincidence rate (216/216) between mtss90 and these two genetic markers. Additionally, mtss90 had a better specificity than mtp40 in the identification of MTB. Lastly, a real-time PCR diagnostic assay was developed for the rapid identification of MTB. In conclusion, mtss90 may be an efficient alternative marker for species-specific identification of MTB and could be used for the diagnosis of tuberculosis combined with other genetic markers.
- [Show abstract] [Hide abstract] ABSTRACT: Streptococcus pneumoniae is a Gram-positive and human-restricted pathogen colonizing the nasopharynx with an absence of clinical symptoms as well as a major pathogen causing otitis media (OM), one of the most common childhood infections. Upon bacterial infection, neutrophils are rapidly activated and recruited to the infected site, acting as the frontline defender against emerging microbial pathogens via different ways. Evidence shows that interleukin 17A (IL-17A), a neutrophil-inducing factor, plays important roles in the immune responses in several diseases. However, its function in response to S. pneumoniae OM remains unclear. In this study, the function of IL-17A in response to S. pneumoniae OM was examined using an in vivo model. We developed a model of acute OM (AOM) in C57BL/6 mice and found that neutrophils were the dominant immune cells that infiltrated to the middle ear cavity (MEC) and contributed to bacterial clearance. Using IL-17A knockout (KO) mice, we found that IL-17A boosted neutrophil recruitment to the MEC and afterwards induced apoptosis, which was identified to be conducive to bacterial clearance. In addition, our observation suggested that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was involved in the recruitment and apoptosis of neutrophils mediated by IL-17A. These data support the conclusion that IL-17A contributes to the host immune response against S. pneumoniae by promoting neutrophil recruitment and apoptosis through the p38 MAPK signaling pathway.
- [Show abstract] [Hide abstract] ABSTRACT: Streptococcus pneumoniae DnaJ is recognized as a virulence factor whose role in pneumococcal virulence remains unclear. Here, we attempted to reveal the contribution of DnaJ in pneumococcal virulence from the identification of its interacting proteins using co-immunoprecipitation method. dnaJ was cloned into plasmid pAE03 generating pAE03-dnaJ-gfp which was used to transform S. pneumoniae D39 strain. Then anti-GFP coated beads were used to capture GFP-coupled proteins from the bacterial lysate. The resulting protein mixtures were subjected to SDS-PAGE and those differential bands were determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry. We finally obtained nine proteins such as DnaK, Gap, Eno, SpxB using this method. Furthermore, to confirm the interaction between DnaJ and these candidates, bacterial two-hybrid system was employed to reveal, for example, the interaction between DnaJ and DnaK, Eno, SpxB. Further protein expression experiments suggested that DnaJ prevented denaturation of Eno and SpxB at high temperature. These results help to understand the role of DnaJ in the pathogenesis of S. pneumoniae.
Dataset: Supplementary material
- [Show abstract] [Hide abstract] ABSTRACT: Hsp100/Clp proteins have crucial functions in the protein quality control, stress tolerance, and virulence of many pathogenic bacteria. ClpE is an important virulence factor involved in adherence and invasion in Streptococcus pneumoniae. To explore the underlying mechanism, we screened ClpE interaction proteins using a bacterial two-hybrid system and co-immunoprecipitation. We used ClpE as bait and constructed the pBT-ClpE bait plasmid for two-hybrid screening. Then, we constructed ClpE::GFP fusion for co-immunoprecipitation screening using anti-GFP monoclonal antibody. We obtained eight potential ClpE interaction proteins, including carbamoyl-phosphate synthase, pyruvate oxidase (SpxB), phosphoenolpyruvate-protein phosphotransferase, aminopeptidase N (pepN), L-lactate dehydrogenase, ribosomal protein S4, sensor histidine kinase (SPD_2019), and FtsW (a cell division protein). FtsW, SpxB, pepN, and SPD_2019 were confirmed to interact with ClpE using Bacterial Two-hybrid or Co-immunoprecipitation. Morphologic observations found that ΔclpE strain existed in abnormal division. β-Galactosidase activity assay suggested that ClpE contributed to the degradation of FtsW. Furthermore, FtsW could be induced by heat shock. The results suggested that ClpE might affect cell division by regulating the level of FtsW. These data may provide new insights in studying the role of ClpE in S. pneumoniae.
- [Show abstract] [Hide abstract] ABSTRACT: IL-27 is involved in inflammatory reactions. CXCL10 is an important chemokine contributing to airway inflammatory diseases. In this study, we investigated whether IL-27 modulated the synthesis of CXCL10 in primary human lung fibroblasts (HLF). HLF were activated by IL-27 alone, or in combination with other cytokines. CXCL10 synthesis was measured by real-time PCR and ELISA. Examination of transcriptional regulation was performed via transient transfection of promoter constructs, whereas mRNA stability was assessed by actinomycin D chase and real-time PCR. The underlying signaling pathways were studied by Western blot and intracellular staining using flow cytometry. Our results demonstrated that IL-27 induced and synergized with TNF-α to upregulate CXCL10 mRNA and protein levels in a steroid-insensitive manner. This synergistic CXCL10 production was dependent on transcriptional regulation of CXCL10 gene promoter activity and the enhanced stability of CXCL10 mRNA by IL-27 and TNF-α, and this synergism was regulated by the activation of p38 MAPK and PI3K-Akt dominantly and in a little part via NF-kB. Interestingly, IL-27 promoted basal and enhanced TNF-α-induced phosphorylation of p38 MAPK and Akt, but not IkBα. Besides, the enhanced CXCL10 mRNA stability occurred via a p38 MAPK-dependent pathway. Finally, clinical analysis showed that IL-27 was detected in BAL of patients with asthma, COPD, and PTB, and the increased IL-27 levels was correlated with the increased CXCL10 levels in patients with COPD and PTB. Our findings suggest that IL-27 has the potential to amplify airway inflammation via the induction of CXCL10 from HLF in combination with TNF-α.
- [Show abstract] [Hide abstract] ABSTRACT: Dental follicle stem cells are a group of cells possessing osteogenic, adipogenetic and neurogenic differentiations, but the specific mechanism underlying the multilineage differentiation remains still unclear. Great attention has been paid to bone morphogenetic protein-9 (BMP-9) due to its potent osteogenic activity. In the present study, rat dental follicle stem cells were isolated and purified, and cells of passage 3 underwent adenovirus mediated BMP-9 gene transfection to prepare dental follicle stem cells with stable BMP-9 expression. Detection of alkaline phosphatase (ALP) and calcium deposition showed dental follicle stem cells transfected with BMP-9 gene could significantly promote the osteogenesis. In addition, SB203580 and PD98059 were employed to block the p38 mitogen-activated protein kinase (p38MAPK) and extracellular signal-regulated kinase (ERK1/2), respectively. Detection of ALP and calcium deposition revealed the BMP-9 induced osteogenic differentiation of dental follicle stem cells depended on MAPK signaling pathway.
- [Show abstract] [Hide abstract] ABSTRACT: Pneumolysin (Ply) is an essential virulence factor of S. pneumoniae, which can induce apoptosis in a variety of host cells to facilitate infection of pathogenic bacteria by as yet unclear mechanisms. To confirm the apoptosis-inducing properties of pneumolysin in endothelial cells, human umbilical vein endothelial cells (HUVECs) were exposed to pneumolysin. The proliferation of HUVECs was inhibited by pneumolysin in a dose- and time-dependent manner. Flow cytometry analysis and ultrastructural changes of the cells indicated the apoptotic response. Exposure to pneumolysin significantly increased the number of apoptotic cells and the activities of caspases-3 and -8. This change was associated with activation of p38 mitogen-activated protein kinase (MAPK) and suppression of extracellular signaling regulation kinase (ERK)1/2. Pre-exposure to the p38 MAPK inhibitor SB-203850 prevented human endothelial cells from apoptosis induced by pneumolysin. In conclusion, these findings demonstrate that pneumolysin induces apoptosis in endothelial cells and the involvement of p38 MAPK activation and ERK1/2 deactivation.
- [Show abstract] [Hide abstract] ABSTRACT: Increasing mortality, morbidity and economic costs have been paid to pneumococcal diseases every year. Currently, vaccination is the most promising strategy to reduce the occurrence of pneumococcal infection. In this study, we investigated the protective efficacy of immunization with recombinant DnaJ (hsp40) protein against infections of different serotypes of Streptococcus pneumoniae. We demonstrated that mucosal immunization with DnaJ antigen could induce both systemic and mucosal antibodies for DnaJ and stimulate the release of high levels of IL-10, IFN-γ and IL-17A. Moreover, this mucosal vaccination could reduce nasal or lung colonization of pneumococcus and elicit protection against different serotypes of invasive pneumococcal infections. As well, we found that intraperitoneal immunization with DnaJ could also protect against invasive infections caused by different serotypes of pneumococcus, and passive immunization with antibodies specific for DnaJ confirmed that this protection was antibody-mediated. Our results therefore support the potential of DnaJ as a conserved pneumococcal protein vaccine.
- [Show abstract] [Hide abstract] ABSTRACT: Zinc metalloprotease B (ZmpB) is present in all isolated pneumococcal strains and contributes to the pathogenesis of pneumococcal infection. In this study, recombinant ZmpB was cloned and expressed in Escherichia coli. The expression of ZmpB by different pneumococcal strains was detectable by Western blotting with antisera raised to recombinant ZmpB. Flow cytometry analysis demonstrated that anti-ZmpB polyclonal antibodies could bind to the cell surface of the pneumococcal strains analyzed. Both recombinant ZmpB protein and anti-ZmpB polyclonal antibodies significantly inhibited the adhesion of Streptococcus pneumoniae D39 to A549 cells. In mouse models, mucosal immunization with recombinant ZmpB could significantly reduce pneumococcal lung colonization caused by S. pneumoniae serotypes 19F and 14 and significantly increase mice survival times following invasive pneumococcal challenge with different pneumococcal strains, including serotypes 2, 3, 6B, and 14. Furthermore, intraperitoneal immunization with recombinant ZmpB in combination with the recombinant pneumolysin mutant (DeltaA146 Ply) and heat shock protein 40 (DnaJ) could enhance the protection against pneumococcal infection compared to protection provided by single-protein antigens. Passive immunization with hyperimmune antisera against these three antigens also demonstrated that the combination of three hyperimmune antisera could provide better protection than single antisera. Taken together, our results suggest that ZmpB is a good candidate pneumococcal vaccine antigen.
- [Show abstract] [Hide abstract] ABSTRACT: Pneumococcal polysaccharide-based vaccines are effective in preventing pneumococcus infection; however, some drawbacks preclude their widespread use in developing and undeveloped countries. Here, we evaluated the protective effects of ATP-dependent caseinolytic protease (ClpP), pneumolysin mutant (DeltaA146 Ply), putative lipoate-protein ligase (Lpl), or combinations thereof against pneumococcal infections in mice. Vaccinated mice were intraperitoneally and/or intranasally challenged with different pneumococcal strains. In intraperitoneal challenge models with pneumococcal strain D39 (serotype 2), the most striking protection was obtained with the combination of the three antigens. Similarly, with the intranasal challenge models, (i) additive clearance of bacteria in lungs was observed for the combination of the three antigens and (ii) a combination vaccine conferred complete protection against intranasal infections of three of the four most common pneumococcal strains (serotypes 14, 19F, and 23F) and 80% protection for pneumococcal strain 6B. Even so, immunity to this combination could confer protection against pneumococcal infection with a mixture of four serotypes. Our results showed that the combination vaccine was as effective as the currently used vaccines (PCV7 and PPV23). These results indicate that system immunization with the combination of pneumococcal antigens could provide an additive and broad protection against Streptococcus pneumoniae in pneumonia and sepsis infection models.
- [Show abstract] [Hide abstract] ABSTRACT: Toosendanin, a triterpenoid derivative isolated from Melia toosendan Sieb. et Zucc., possesses different pharmacological effects in humans and an important value in agriculture. As indicated by previous reports, the molecular mechanisms of toosendanin's anticancer effects remain poorly clarified. In this study we used both in vivo and in vitro models to investigate the anti-cancer effects of toosendanin and their possible molecular mechanisms. In the in vitro experiment, human hepatocellular carcinoma cell lines [SMMC-7721(p53+) and Hep3B (p53-)] were coincubated with toosendanin of different concentrations (0.1~ 0.9 µM). Anti-proliferation effects were observed to be in a dose- and time-dependent manner. The IC(50) of TSN treated after 72 h for SMMC-7721 and Hep3B cells was 0.5 µM and 0.9 µM, respectively. Results from morphological analysis, annexin V staining, detection of caspases activity, and expressions of Bcl-2, Bax, and Fas indicated that the anticancer effects of toosendanin were associated with its induction of apoptosis via the mitochondria-dependent pathway in p53- and p53+ hepatocellular carcinoma cells. In the IN VIVO experiment, BALB/c mice were s.c. inoculated with mouse hepatocellular carcinoma H (22) cells. Both high-dose (0.69 mg/kg) and low-dose (0.173 mg/kg) toosendanin administrated intraperitoneally resulted in strongly suppressive effects on the tumorigenicity and apoptotic response. Results from the immunohistochemistry for Bcl-2, Bax, as well as for Fas showed that the anticancer effects of toosendanin were induced via apoptosis in a mitochondria-dependent manner, which confirmed the findings in the in vitro experiment. The findings above demonstrate that toosendanin possesses strong anticancer effects in vivo and in vitro via inducing mitochondria-dependent apoptosis in hepatocellular carcinoma cells.