Introduction In adults and children with RSV infection, a polymorphism in the IL-6 promoter at position −174 predicted illness magnitude. Also, polymorphisms in the IL-10, TNFα and INFγ genes were associated with immune responsiveness and the frequency of complications. Here, the effect of these polymorphisms on illness and seroconversion during infection with rhinovirus type 39 (RV39) was evaluated. Methods Seventy-two adults were genotyped for the selected polymorphisms, experimentally exposed to RV39 and followed for infection, seroconversion and symptoms/signs of illness. Regression analysis was used to determine if these polymorphisms predicted seroconversion and illness magnitude in 57 infected subjects. Results The low production IL-6 (−174, C/C) phenotype was associated with greater symptom magnitudes and the INFγ (+874) phenotype predicted the frequency of seroconversion. No relationship between the IL-10 or TNFα polymorphisms and any measured outcome was documented. IL-6 protein measured in nasal wash fluids of 51 subjects was positively correlated with symptom magnitude but was independent of the IL-6 (−174) genotypes representing high and low production phenotypes. Conclusions These results document significant associations between the IL-6 (−174) and INFγ (+874) gene polymorphisms and specific responses to experimental RV39 infection. For the IL-6 (−174) polymorphism, the results replicate those for RSV infection.

No abstract

Objective-Streptococcus pneumoniae, a leading cause of otitis media (OM), undergoes spontaneous intra-strain variations in colony morphology. Transparent (T) variants are more efficient in colonizing the nasopharynx while opaque (O) variants exhibit greater virulence during systemic infections. This study was intended to delineate the underlying molecular mechanisms by which the predominant S. pneumoniae variant efficiently infects the middle ear (ME) mucosa.Methods-Human ME epithelial cells were preconditioned for 24 hrs under one of the three gas/ pressure conditions designed to simulate those for 1) normal ME (NME), 2) ME with Eustachian tube obstruction (ETO) and 3) ME with tympanostomy tube placement (TT), and then were incubated with ~10 7 CFU/mL of either T or O variants of S. pneumoniae (6A) for 3 hrs. Relative expression levels of genes encoding virulence factors, PsaA (surface adhesion), SpxB (pyruvate oxidase), Ply (pneumolysin), and LytA (autolysin), were assessed separately in epitheliumattached and supernatant bacteria 3 hrs post infection using real-time PCR.Results-Basal levels of the virulence molecules in inocula were comparable between two variants. However, relative expression levels of the gene transcripts were significantly induced in epithelium-attached T variants 3 hrs after infection. Comparing with NME and TT conditions, ETO environment produced the largest effect on the differential expression of the virulence genes in the infected ME epithelial cells between T (induced) and O (suppressed) phenotypic pneumococci.Conclusions-T variant is a predominant phenotype responsible for the pathogenesis of pneumococcal OM.

Streptococcus pneumoniae, a leading cause of otitis media (OM), undergoes spontaneous intra-strain variations in colony morphology. Transparent (T) variant is more efficient in colonizing the nasopharynx while the opaque (O) variant exhibits greater virulence during systemic infections. We hypothesized that changes in middle ear (ME) gas pressure/composition during Eustachian tube (ET) dysfunction and the treatment of that dysfunction, e.g., tympanostomy tube (TT) insertion, play a role in selecting the S. pneumonia variant that can efficiently colonize/infect the ME mucosa. Human ME epithelial cells were preconditioned for 24 hrs under one of three conditions that simulated 1) normal ME, 2) ME with ET obstruction (ETO) and 3) ME with TT; subsequently exposed to a dose (~10 7 CFU/ml) of either T or O variant of S. pneumoniae, and then incubated for 1 hr and 3 hrs. Under the simulated ETO and TT conditions, T variant exhibited a higher growth rate and greater epithelial adherence and killing than did O variants. Attachment of T variant to epithelial cells was documented by scanning electron microscopy. These results suggest that the T-variant is more highly adapted to various ME environments than the O-variants.

To delineate age-dependent and tissuespecific molecular activities of the variant-inclusion fibronectin transcripts in fetal and postnatal skin and airway mucosal wounds during early events of the wound healing process. Fibronectin is involved in multiple steps of the wound healing process. The functional complexity of fibronectin is carried through its protein diversity, which is controlled in part by alternative RNA splicing, a coordinated transcription and RNA processing. From a rabbit model of airway mucosal wound healing, we isolated and cloned an RNA splicing factor, SRp20, that was coexpressed with Fn1 complementary DNA and suppressed in fetal wounds but induced in postnatal wounds. Previous studies revealed a link between the inclusion and/or exclusion of the alternatively spliced Fn1 variants (extra domain A [EDA], extra domain B [EDB], and a variable region [V]) and outcomes of wound repair. Design: Skin and airway mucosal incisional wounds were made in fetal (gestational day 21-23), weanling (4-6 weeks), and adult (Ͼ6 months) rabbits. Tissues (nonwounded and wounded) were collected at 12 hours (all age groups), 24 hours, and 48 hours (weanling only) after wounding. The expression levels of the 3 Fn1 spliced domain (EDA, EDB, and V)-containing messenger RNA (mRNA) species were assessed by real-time polymerase chain reaction. Results: Fn1 spliced variants were either suppressed or showed no change in fetal skin and airway mucosal wounds 12 hours after injury, whereas the spliced mRNAs were induced in postnatal wounds. The augmented molecular activities of Fn1 spliced variants were more prominent in airway mucosal wounds than in skin wounds. Furthermore, the EDA variant was dominantly selected in adult airway mucosal wounds (6-fold increase), which was strikingly different from the adult skin wounds (1-fold). Conclusion: Our study suggests that the age-dependent activation of Fn1-EDA mRNA may play a fundamental role in differentiating fetal wound regeneration from postnatal wound scar formation during the early events of airway mucosal wound healing.