title: Prevention of airway inflammation with topical cream containing imiquimod and small interfering RNA for natriuretic peptide receptor.
abstract: BACKGROUND
  Asthma is a complex disease, characterized by reversible airway obstruction, hyperresponsiveness and chronic inflammation. Principle pharmacologic treatments for asthma include bronchodilating beta2-agonists and anti-inflammatory glucocorticosteroids; but these agents do not target the main cause of the disease, the generation of pathogenic Th2 cells. We previously reported reduction in allergic inflammation in mice deficient in the ANP receptor NPRA. Here we determined whether siRNA for natriuretic peptide receptor A (siNPRA) protected against asthma when administered transdermally.
  
  
  METHODS
  Imiquimod cream mixed with chitosan nanoparticles containing either siRNA green indicator (siGLO) or siNPRA was applied to the skin of mice. Delivery of siGLO was confirmed by fluorescence microscopy. The anti-inflammatory activity of transdermal siNPRA was tested in OVA-sensitized mice by measuring airway hyperresponsiveness, eosinophilia, lung histopathology and pro-inflammatory cytokines.
  
  
  RESULTS
  SiGLO appearing in the lung proved the feasibility of transdermal delivery. In a mouse asthma model, BALB/c mice treated with imiquimod cream containing siNPRA chitosan nanoparticles showed significantly reduced airway hyperresponsiveness, eosinophilia, lung histopathology and pro-inflammatory cytokines IL-4 and IL-5 in lung homogenates compared to controls.
  
  
  CONCLUSIONS
  These results demonstrate that topical cream containing imiquimod and siNPRA nanoparticles exerts an anti-inflammatory effect and may provide a new and simple therapy for asthma.
authors.affiliation: Clinical Laboratory Center of First Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China. xwang1@health.usf.edu
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Wang
authors.forename: Weidong
authors.initials: W
authors.lastname: Xu
authors.forename: Subhra
authors.initials: S
authors.lastname: Mohapatra
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Kong
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Richard F
authors.initials: RF
authors.lastname: Lockey
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Mohapatra