Streptococcus pneumoniae causes high mortality as a major pneumonia-inducing pathogen. In pneumonia, control of innate immunity is necessary to prevent organ damage. We assessed the role of microRNAs (miRNAs) as regulators in pneumococcal infection of human macrophages. Exposure of primary blood-derived human macrophages with pneumococci resulted in transcriptional changes in several gene clusters and a significant deregulation of 10 microRNAs. Computational network analysis retrieved miRNA-146a as one putatively important regulator of pneumococci-induced host cell activation. Its induction depended on bacterial structural integrity and was completely inhibited by blocking Toll-like receptor 2 (TLR-2) or depleting its mediator MyD88. Furthermore, induction of miRNA-146a release did not require the autocrine feedback of interleukin 1β and tumor necrosis factor α released from infected macrophages, and it repressed the TLR-2 downstream mediators IRAK-1 and TRAF-6, as well as the inflammatory factors cyclooxygenase 2 and interleukin 1β. In summary, pneumococci recognition induces a negative feedback loop, preventing excessive inflammation via miR-146a and potentially other miRNAs.
Background Community-acquired pneumonia (CAP) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) represent a major burden of disease and death and their differential diagnosis is critical. A potential source of relevant accessible biomarkers are blood-borne small extracellular vesicles (sEVs). Methods We performed an extracellular vesicle array to find proteins on plasma sEVs that are differentially expressed and possibly allow the differential diagnosis between CAP and AECOPD. Plasma samples were analyzed from 21 healthy controls, 24 patients with CAP, and 10 with AECOPD . The array contained 40 antibodies to capture sEVs, which were then visualized with a cocktail of biotin-conjugated CD9, CD63, and CD81 antibodies. Results We detected significant differences in the protein decoration of sEVs between healthy controls and patients with CAP or AECOPD. We found CD45 and CD28 to be the best discrimination markers between CAP and AECOPD in receiver operating characteristic analyses, with an area under the curve >0.92. Additional ensemble feature selection revealed the possibility to distinguish between CAP and AECOPD even if the patient with CAP had COPD, with a panel of CD45, CD28, CTLA4 (cytotoxic T-lymphocyte-associated protein 4), tumor necrosis factor–R-II, and CD16. Conclusion The discrimination of sEV-associated proteins is a minimally invasive method with potential to discriminate between CAP and AECOPD.
Lower respiratory infections, such as community-acquired pneumonia (cAp), and chronic obstructive pulmonary disease (copD) rank among the most frequent causes of death worldwide. improved diagnostics and profound pathophysiological insights are urgent clinical needs. in our cohort, we analysed transcriptional networks of peripheral blood mononuclear cells (pBMcs) to identify central regulators and potential biomarkers. We investigated the mRnA-and miRnA-transcriptome of pBMcs of healthy subjects and patients suffering from CAP or AECOPD by microarray and Taqman Low Density Array. Genes that correlated with PBMC composition were eliminated, and remaining differentially expressed genes were grouped into modules. One selected module (120 genes) was particularly suitable to discriminate AECOPD and CAP and most notably contained a subset of five biologically relevant mRNAs that differentiated between CAP and AECOPD with an AUC of 86.1%. Likewise, we identified several microRNAs, e.g. miR-545-3p and miR-519c-3p, which separated AECOPD and CAP. We furthermore retrieved an integrated network of differentially regulated mRNAs and microRNAs and identified HNF4A, MCC and MUC1 as central network regulators or most important discriminatory markers. in summary, transcriptional analysis retrieved potential biomarkers and central molecular features of cAp and AecopD. Community acquired pneumonia (CAP) is clinically defined by a sudden onset of severe illness that is accompanied by signs of lower respiratory tract infection, fever, cough and dyspnoea 1. When left untreated, severe secondary effects such as organ damage and occurrence of bacteria in the blood (bacteremia) can ensue. While subject to variance due to region, season and population characteristics, the incidence of CAP is estimated to lie between 1.5 and 14 cases per 1,000 persons per year, with children under 5 years of age and the elderly of more than 65 years being most strongly affected 2. Immunocompromised persons also bear a higher risk of CAP contraction. The leading underlying cause of CAP is infection with the gram-positive bacterium Streptococcus pneumoniae, accounting for 30-35% of CAP cases worldwide 3. The initial colonization of the nasopharynx and the upper respiratory tract often remains asymptomatic. Aspiration into the alveoli can cause severe respiratory or systemic disease, depending on the host immune status and the pneumococcal serotype 1. As CAP is a multifaceted disease with a host of potential causative agents, the robust identification of microR-NAs that are functionally involved in pneumonia depends on the pathogen. In severe Influenza A Virus (H1N1)
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