Cytokine induction of peripheral blood mononuclear cells by biofilms and biofilm supernatants of Granulicatella and Abiotrophia spp.

Granulicatella and Abiotrophia species are the normal oral flora bacteria that can occasionally cause infective endocarditis. Although substantial data exists in the literature demonstrating occurrence of these species in infective endocarditis, only a few mechanistic studies on their pathogenicity are found. The aim of this study was to investigate the ability of Granulicatella and Abiotrophia species to elicit immune response from human peripheral blood mononuclear cells (PBMC). Biofilms and biofilm supernatants of Granulicatella elegans CCUG 38949, Granulicatella adiacens CCUG 27809 and Abiotrophia defectiva CCUG 27639 were used to stimulate PBMCs for 24 h. Cytokines produced were first screened using a human cytokine membrane array kit. Further, pro-inflammatory cytokines TNF-α, IL-ß, and IL-17 were quantified by ELISA. The cytokine profiler array showed the induction of 15 different cytokines/chemokines including IL-1ß, IL-6, IL-8, TNF-α, MCP-1, MIP-1α/MIP-1ß and RANTES. ELISA quantification revealed that G. adiacens biofilm induced significantly higher (P < 0.05) levels of IL-1ß, i.e., 1931 (183) pg/ml than G. elegans or A. defectiva. However, in the case of biofilm supernatants A. defectiva was the strongest, inducing 2104 (574) pg/ml. Biofilm supernatants, but not biofilms from all three species induced TNF-α only weakly. IL-17 was undetectable from any of the stimulated samples. In conclusion, Granulicatella and Abiotrophia are potent inducers of inflammatory mediators from human PBMCs. However, biofilms and biofilm supernatants from these species seem to selectively elicit stimulation of certain cytokines.

The upper-airway microbiota and loss of asthma control among asthmatic children.

The airway microbiome has an important role in asthma pathophysiology. However, little is known on the relationships between the airway microbiome of asthmatic children, loss of asthma control, and severe exacerbations. Here we report that the microbiota's dynamic patterns and compositions are related to asthma exacerbations. We collected nasal blow samples (n = 319) longitudinally during a clinical trial at 2 time-points within one year: randomization when asthma is under control, and at time of early loss of asthma control (yellow zone (YZ)). We report that participants whose microbiota was dominated by the commensal Corynebacterium + Dolosigranulum cluster at RD experience the lowest rates of YZs (p = 0.005) and have longer time to develop at least 2 episodes of YZ (p = 0.03). The airway microbiota have changed from randomization to YZ. A switch from the Corynebacterium + Dolosigranulum cluster at randomization to the Moraxella- cluster at YZ poses the highest risk of severe asthma exacerbation (p = 0.04). Corynebacterium's relative abundance at YZ is inversely associated with severe exacerbation (p = 0.002).

In vitro inflammatory responses elicited by isolates of Alloiococcus otitidis obtained from children with otitis media with effusion.

Alloiococcus otitidis is usually detected in children with otitis media (OM) by PCR as it is not often detected by routine culture. Our improved method for its isolation obtained A. otitidis from nearly 50% of 78 children with OM with effusion. The role of A. otitidis in pathogenesis of OM is unclear. This study tested two hypothesis: (1) that fresh isolates of A. otitidis would elicit pro-inflammatory cytokines from THP-1 monocytic cells equivalent to those induced by Streptococcus pneumoniae; (2) priming THP-1 cells with interferon-gamma (IFN-γ) a surrogate for virus infection, would enhance pro-inflammatory responses. Recent clinical isolates of A. otitidis, S. pneumoniae (ATCC 49619) and a blood culture isolate of S. pneumoniae (SP2) were used in the assays. Cytokines were quantified by BioRad bead assay and Luminex 200. IFN-γ priming enhanced cytokine responses. S. pneumoniae ATCC 49619 induced lower responses than SP2 for IL-1ß, IL-6, TNF-α. A. otitidis LW 27 elicited higher IL-1ß and TNF-α responses than either pneumococcal isolate. Small green colony types of A. otitidis induced higher responses than large white colony types for IL-8 and IL-1ß. The hypothesis that A. otitidis elicits cytokines observed in middle ear effusions was supported; the need to use recent clinical isolates in studies of pathogenesis was highlighted.