Double-Edged Role of Interleukin 17A in Streptococcus pneumoniae Pathogenesis During Influenza Virus Coinfection.

BACKGROUND: We sought to determine the role of host interleukin 17A (IL-17A) response against colonizing Streptococcus pneumoniae, and its transition to a pathogen during coinfection with an influenza virus, influenza A H1N1 A/Puerto Rico/8/1934 (PR8). METHOD: Wild-type (WT) C57BL/6 mice were intranasally inoculated with S. pneumoniae serotype 6A to establish colonization and later infected with the influenza strain, PR8, resulting in invasive S. pneumoniae disease. The role of the IL-17A response in colonization and coinfection was investigated in WT, RoRγt-/- and RAG1-/- mice with antibody-mediated depletion of IL-17A (WT) and CD90 cells (RAG1-/-). RESULTS: RAG1-/- mice did not clear colonization and IL-17A neutralization impaired 6A clearance in WT mice. RoRγt-/- mice also had reduced clearance. S. pneumoniae-PR8 coinfection elicited a robust IL-17A response in the nasopharynx; IL-17A neutralization reduced S. pneumoniae invasive disease. RoRγt-/- mice also had reduced S. pneumoniae disease in a coinfection model. Depletion of CD90+ cells suppressed the IL-17A response and reduced S. pneumoniae invasion in RAG1-/- mice. CONCLUSION: Our data show that although IL-17A reduces S. pneumoniae colonization, coinfection with influenza virus elicits a robust innate IL-17A response that promotes inflammation and S. pneumoniae disease in the nasopharynx.

Retailer Compliance as a Predictor of Youth Smoking Participant and Consumption.

BACKGROUND: Ninety percent of smokers report having their first whole cigarette before the age of 19. Policies, such as youth access laws, are essential to prevent youth from becoming future smokers. In Canada, the Tobacco Act prohibits retailers from furnishing tobacco products to individuals under the age of 18. These laws can only be effective when retailers comply with them. This paper investigates the effect of retailer compliance on youth smoking behavior. METHODS: Data on individual smoking behavior in conjunction with provincial retailer compliance rates and cigarette prices for the years 1999-2005 were employed to examine the effects of retailer compliance on youth smoking participation and consumption. RESULTS: Both price and retailer compliance were significant predictors of smoking participation. A large portion of participants endorsed obtaining their cigarettes through social means. Price elasticity of demand for the overall sample was estimated to be -0.54. CONCLUSIONS: Consistent with previous literature, our results found that retailer compliance is an essential component to the successful implementation of youth access laws. Given that youth access laws and retailer compliance did not quell social access to cigarettes, there is an apparent need within schools and communities to reduce the social sale of tobacco products.