Project description:Background: We employed DNA microarray technology to investigate the host response to Streptococcus pneumoniae in a mouse model of asymptomatic carriage. Over a period of six weeks, we profiled transcript abundance and complexity in the Nasal Associated Lymphoid Tissue (NALT) to identify genes whose expression differed between pneumococcal-colonized and uncolonized states. Results: Colonization with S. pneumoniae altered the expression of hundreds of genes over the course of the study, demonstrating that carriage is a dynamic process characterized by increased expression of a set of early inflammatory responses, including induction of a Type 1 Interferon response, and the production of several antimicrobial factors. Subsequent to this initial inflammatory response, we observed increases in transcripts associated with T cell development and activation, as well as wounding, basement membrane remodeling, and cell proliferation. Our analysis suggests that microbial colonization induced expression of genes encoding components critical for controlling JAK/STAT signaling, including stat1, stat2, socs3, and mapk1, as well as induction of several Type 1 Interferon-inducible genes and other antimicrobial factors at the earliest stages of colonization. Conclusions: Examining multiple time points over six weeks of colonization demonstrated that asymptomatic carriage stimulates a dynamic host response characterized by temporal waves with distinct biological programs. Our data suggest that the usual response to the presence of the pneumocccus is an initial controlled inflammatory response followed by activation of host physiological processes such as response to wounding, basement membrane remodeling, and increasing cellular numbers that ultimately allow the host to maintain an intact epithelium and eventually mount a preventive adaptive immune response. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied.
Project description:Secondary bacterial pneumonia following influenza infection is a significant cause of mortality worldwide. Upper respiratory tract pneumococcal carriage is important as both determinants of disease and population transmission. The immunological mechanisms that contain pneumococcal carriage are well-studied in mice but remain unclear in humans. Loss of this control of carriage following influenza infection is associated with secondary bacterial pneumonia during seasonal and pandemic outbreaks. We used a human type 6B pneumococcal challenge model to show that carriage acquisition induces early degranulation of resident neutrophils and recruitment of monocytes to the nose. Monocyte function associated with clearance of pneumococcal carriage. Prior nasal infection with live attenuated influenza virus induced inflammation, impaired innate function and altered genome-wide nasal gene responses to pneumococcal carriage. Levels of the cytokine IP-10 promoted by viral infection at the time of pneumococcal encounter was positively associated with bacterial density. These findings provide novel insights in nasal immunity to pneumococcus and viral-bacterial interactions during co-infection.
Project description:Streptococcus pneumoniae (Spn) is the predominant causative organism of acute otitis media (AOM) in children. A human cDNA microarray comprising 30,968 human genome probes was used to evaluate the transcriptional changes that occur in peripheral blood mononuclear cells (PBMC) at the onset of clinical AOM caused by Spn infection in children after comparison of microarray results with the pre-infection healthy stage of the same children.
Project description:Interspecies coaggregation promotes transcriptional changes of oral bacteria, contributing to the development of structurally balanced biofilms as well as oral diseases such as periodontitis. Streptococcus gordonii (S. gordonii) is an early colonizer of the oral cavity, and Fusobacterium nucleatum (F. nucleatum) may act as a bridge adhering to both early and late oral colonizers. These two species were commonly detected in healthy and periodontitis-diseased oral sites and could interact with immune cells such as macrophages. However, little research explored how intergeneric coaggregation affected transcriptional changes in S. gordonii and F. nucleatum subsp. polymorphum and how these gene changes might affect both species’ pathogenicity. The present study investigated transcriptional changes of both species in response to dual-species physical association using dual RNA-seq. Results indicated that after 30-min dual-species coaggregation, 148 genes were significantly up-regulated, and 124 genes were significantly down-regulated in S. gordonii. A total of 154 genes were significantly down-regulated, and 10 genes were significantly up-regulated in F. nucleatum subsp. polymorphum. A majority of up-regulated S. gordonii genes were involved in the biosynthesis and export of cell-wall proteins and the pathway of carbohydrate metabolism, and a group of down-regulated S. gordonii genes were associated with fatty acid biosynthesis and peptidoglycan biosynthesis. The transcriptome profiles indicated that the interspecies coaggregation led to a reduced level of DNA repair and lipopolysaccharides virulence in F. nucleatum subsp. polymorphum. The present study revealed that dual-species coaggregation induced a wide array of gene changes in S. gordonii and F. nucleatum subsp. polymorphum, enhancing S. gordonii’s adherence ability and attenuating F. nucleatum subsp. polymorphum's ability to produce LPS.
Project description:Plasmid carriage requires appropriate expression of the genes on the plasmid or host chromosome through cooperative transcriptional regulation. To clarify the impact of plasmid carriage on the host chromosome, we compared the chromosomal RNA maps of plasmid-free and plasmid-containing host strains using the incompatibility group P-7 archetype plasmid pCAR1, which is involved in carbazole degradation, and three distinct Pseudomonas strains. The possession of pCAR1 altered gene expression related to the iron acquisition systems in each host. Expression of the major siderophore pyoverdine was greater in plasmid-containing P. putida KT2440 and P. aeruginosa PAO1 than in the plasmid-free host strains, in part due to the expression of carbazole-degradative genes on pCAR1. The mexEFoprN operon encoding an efflux pump of the resistance-nodulation-cell division (RND) family was specifically upregulated by the carriage of pCAR1 in P. putida KT2440, whereas the expression of orthologous genes in the other species remained unaltered. Induction of the mexEFoprN genes increased the resistance of pCAR1-containing KT2440 to chloramphenicol compared to pCAR1-free KT2440. Our findings indicate that the possession of pCAR1 altered the growth rate of the host via the expression of genes on pCAR1 and the host chromosomes.