Project description:Streptococcus pneumoniae is a major cause of invasive diseases, such as pneumoniae, meningitis and sepsis resulting in high mortality. The molecular mechanisms and disease developing mechanism underlying pneumococcal infection remain unknown. Previously, we reported that S. pneumoniae β-galactosidase (BgaA) is evolutionarily conserved and contributes to pneumococcal pathogenesis in mouse sepsis model. BgaA is also known to play a role in pneumococcal growth, resistance to human neutrophil opsonophagocytic killing, bacterial adherence to human epithelial cells. In this study, since the detailed role that BgaA plays in sepsis remain unknown, we focused on the role of BgaA in pneumococcal sepsis. Our in vitro assays showed that BgaA promoted bacterial association with human lung epithelial and vascular endothelium cells. BgaA also contributes to pneumococcal survival with human blood by suppressing neutrophils killing, whereas BgaA did not affect pneumococcal survival in mouse blood. In a mouse sepsis model, mice infected with S. pneumoniae bgaA deletion mutant strain exhibited up-regulated host innate immunity pathways, and suppressed tissue damages and blood coagulation as compared to mice infected with the wild-type strain. These results suggest that BgaA works as a multifunctional virulence factor for inducing host tissue damages and blood coagulation. BgaA could be an attractive target for drug and vaccine development.
Project description:Treatment of pneumococcal infections is limited by antibiotic resistance and exacerbation of disease by bacterial lysis releasing pneumolysin toxin and other inflammatory factors. We identified a novel peptide in the Klebsiella pneumoniae secretome, which enters Streptococcus pneumoniae via its AmiA-AliA/AliB permease. Subsequent downregulation of genes for amino acid biosynthesis and peptide uptake was associated with reduction of pneumococcal growth in defined medium and human cerebrospinal fluid, irregular cell shape, decreased chain length and decreased genetic transformation. The bacteriostatic effect was specific to S. pneumoniae and Streptococcus pseudopneumoniae with no effect on Streptococcus mitis, Haemophilus influenzae, Staphylococcus aureus or K. pneumoniae. Peptide sequence and length were crucial to growth suppression. The peptide reduced pneumococcal adherence to primary human airway epithelial cell cultures and colonization of rat nasopharynx, without toxicity. We also analysed the effect of peptide on the proteome of S. pneumoniae. We found alteration of the proteome by the peptide with some proteins turned on or off in line with the transcriptomic changes. We therefore identified a peptide with potential as a therapeutic for pneumococcal diseases suppressing growth of multiple clinical isolates, including antibiotic resistant strains, while avoiding bacterial lysis and dysbiosis.
Project description:Influenza A virus (IAV) predisposes individuals to secondary infections with the bacterium Streptococcus pneumoniae (the pneumococcus). Infections may manifest as pneumonia, sepsis, meningitis or otitis media (OM). It remains controversial as to whether secondary pneumococcal disease is due to the induction of an aberrant immune response or IAV induced immunosuppression. Moreover, as the majority of studies have been performed in the context of pneumococcal pneumonia, it remains unclear how far these findings can be extrapolated to other pneumococcal disease phenotypes. Here, we demonstrate that the viral hemagglutinin (HA) mediates bacterial OM by inducing a pro-inflammatory response in the middle ear cavity in a replication-dependent manner. Importantly, our findings show that it is the inflammatory response that mediates pneumococcal replication; not viral suppression of the immune system or epithelial damage. This study provide the first evidence that HA induced inflammation drives pneumococcal replication in the middle ear cavity, which has important consequences to the treatment of pneumococcal OM.
Project description:The objective of this study is to: 1) Characterize the immune responsiveness to administration of non-live vaccines in three cohorts of healthy adult subjects through the analysis of blood leukocytes transcriptional profiles. 2) Validate whole blood transcriptional profiles generated from standard 3mL blood draws versus 200uL blood draws obtained by finger stick. 3) Discover potential biomarkers for immune-responsiveness to non-live vaccines. A total of 621 blood samples were collected either by venipuncture (387) or finger prick (234) from four groups of healthy adults receiving either, 2009/10 seasonal influenza or 23-valent pneumococcal vaccine or placebo (saline) injections. Subjects were recruited in 3 cohorts with 4-7 individuals per group; cohort 3 was recruited for validation of the systemic day 1 immune signature in response to seasonal influenza and pneumococcal vaccination. From each subject, peripheral blood was drawn into Tempus tubes (Applied Biosystems) or obtained by finger prick into micro capillaries and then transferred into tempus reagent to lyse blood cells and stabilize RNA before storing at -80ºC until mRNA extraction. The training set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 1 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The test set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 2 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The validation set for confirming systemic day 1 transcriptome immune signature in response to seasonal influenza and pneumococcal vaccination was performed in cohort 3 which included 6 healthy adult individuals receiving seasonal influenza vaccine and 4 healthy adult individuals receiving pneumococcal vaccine. The training set for transcriptional profiling of blood obtained by finger prick was performed in cohort 2 and the test set in cohort 1.
Project description:The objective of this study is to: 1) Characterize the immune responsiveness to administration of non-live vaccines in three cohorts of healthy adult subjects through the analysis of blood leukocytes transcriptional profiles. 2) Validate whole blood transcriptional profiles generated from standard 3mL blood draws versus 200uL blood draws obtained by finger stick. 3) Discover potential biomarkers for immune-responsiveness to non-live vaccines. A total of 621 blood samples were collected either by venipuncture (387) or finger prick (234) from four groups of healthy adults receiving either, 2009/10 seasonal influenza or 23-valent pneumococcal vaccine or placebo (saline) injections. Subjects were recruited in 3 cohorts with 4-7 individuals per group; cohort 3 was recruited for validation of the systemic day 1 immune signature in response to seasonal influenza and pneumococcal vaccination. From each subject, peripheral blood was drawn into Tempus tubes (Applied Biosystems) or obtained by finger prick into micro capillaries and then transferred into tempus reagent to lyse blood cells and stabilize RNA before storing at -80ºC until mRNA extraction. The training set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 1 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The test set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 2 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The validation set for confirming systemic day 1 transcriptome immune signature in response to seasonal influenza and pneumococcal vaccination was performed in cohort 3 which included 6 healthy adult individuals receiving seasonal influenza vaccine and 4 healthy adult individuals receiving pneumococcal vaccine. The training set for transcriptional profiling of blood obtained by finger prick was performed in cohort 2 and the test set in cohort 1.
Project description:Streptococcus pneumoniae is an opportunistic human pathogen that typically colonizes the nasopharyngeal passage and causes lethal disease in other host niches such as the lung or the meninges. How pneumococcal genes are expressed and regulated at the different stages of its life cycle, as commensal or as pathogen, has not been entirely described. To chart the transcriptional responses of S. pneumoniae, we quantified the transcriptome under 22 different infection-relevant conditions. The transcriptomic compendium exposed a high level of dynamic expression and, strikingly, all annotated pneumococcal genomic features were expressed in at least one of the studied conditions. By computing the correlation of gene expression of every two genes across all studied conditions, we created a co-expression matrix that provides valuable information on both operon structure and regulatory processes. The co-expression data is highly consistent with well-characterized operons and regulons, such as the PyrR, ComE and ComX regulons, and had allowed us to identify a new member of the competence regulon. Finally, we created an interactive data center (www.veeninglab.com/pneumoexpress) that enables users to access the expression data as well as the co-expression matrix in an intuitive and efficient manner, providing a valuable resource to the pneumococcal research community.
Project description:Analysis of pulmonary gene expression in two mouse strains, resistant (BALB/c) and susceptible (CBA/Ca) to Streptococcus pneumoniae infection. Data collected at 6h post-infection and for control animals (PBS-treated). The list of differentially expressed genes was created by comparisons of infected versus PBS-treated animals and PBS-treated BALB/c versus CBA/Ca. The hypothesis tested in the present study was that pulmonary transcriptomes of both mouse strains differ during pneumococcal infection and in non-disease conditions. Results provided important information on differences in immune responses between both mouse strains. The results identified genes and pathways uniquely regulated by only one of the tested mouse strains helping to understand molecular mechanism behind resistance or susceptibility to pneumococcal infections. Total RNA obtained from lung tissue from BALB/cOlaHsd and CBA/CaOlaHsd mouse strains (Harlan) 6 hours post intranasal infection with Streptococcus pneumoniae serotype 2 strain D39 dose 5.0E06 or PBS-treated animals
Project description:In the present study, we used RNA sequencing on mouse splenocytes to describe the immune recall in the days following pneumococcal lung infection. Mice were sacrificed at days 1, 2, 4, and 7 after Streptococcus pneumoniae (TIGR4 serotype 4) intranasal infection and splenocytes were cultured in the presence or absence of the same inactivated bacterial strain to access the transcriptomic profile.
Project description:Purpose: Influenza virus infections affect millions of people annually. Current available vaccines provide varying rates of protection. There is a knowledge gap on how the nasal microbiota, particularly established pneumococcal colonization, shapes the response to influenza vaccination. Methods: In this study, we inoculated healthy adults with live S. pneumoniae and vaccinated them three days later with either TIV or LAIV. Vaccine-induced immune responses were assessed in nose, blood and lung. Results: Nasal pneumococcal colonization had no impact upon TIV-induced antibody responses to influenza, which manifested in all compartments. However, pre-existing pneumococcal colonization dampened LAIV-mediated mucosal antibody responses, primarily IgA in the nose and IgG in the lung. Pulmonary influenza-specific cellular responses were more apparent in the LAIV group compared to either TIV or an unvaccinated group. Conclusions: These results indicate that TIV and LAIV elicit differential immunity to adults and that LAIV immunogenicity is diminished by the nasal presence of S. pneumoniae. This important confounder should be considered when assessing LAIV efficacy.
Project description:Rationale: Streptococcus pneumoniae is the most common bacterial cause of community acquired pneumonia. Some clinical trials have demonstrated a beneficial effect of corticosteroid therapy in community acquired pneumonia, but the mechanisms of this benefit remain unclear. Objectives: To investigate the biologic effects of corticosteroids in pneumococcal pneumonia in mice and in patients Methods: We studied lower respiratory tract transcriptomes from an observational cohort of mechanically ventilated patients and from a pneumonia model in mice. We also carried out comprehensive physiologic, biochemical, and histological analyses in mice to identify mechanisms of lung injury in S. pneumoniae with and without adjunctive steroid therapy. Measurement and Main Results: Transcriptomic analysis identified pleiotropic effects of steroid therapy on the lower respiratory tract in critically ill patients with pneumococcal pneumonia, findings that were reproducible in mice. In mice with pneumonia, dexamethasone in combination with ceftriaxone reduced (1) pulmonary edema formation, (2) alveolar protein permeability, (3) proinflammatory cytokine release, (4) histopathology lung injury score, and (5) hypoxemia, but did not increase bacterial burden. Conclusions: In combination with appropriate antibiotics in mice, treatment of pneumococcal pneumonia with steroid therapy reduces hypoxemia, pulmonary edema, lung permeability, and histologic criteria of lung injury, and also altered inflammatory responses at the protein and gene expression level. The concordance of transcriptional data in the mouse model and in patients with pneumococcal pneumonia supports the translational relevance of this work.