Published ahead of print on March 30, 2007, doi:10.1164/rccm.200701-054OC Am. J. Respir. Crit. Care Med., Volume 175, Number 12, June 2007, 1241-1249 A more recent version of this article appeared on June 15, 2007
Submitted on January 10, 2007 Chronic Asthma Induced Airway Remodeling is Prevented by the Toll-like Receptor 7/8 Ligand S28463Pierre Camateros1,1 Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada, 2 Department of Pulmonary Medicine, Tokyo Medical and Dental University, Tokyo, Japan, 3 Meakins -Christie Laboratories, McGill University, Montreal, Quebec, Canada, 4 Department of Medicine, Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA, USA, 5 The Research Institute of the McGill University Health Center, Montreal, Quebec, Canada, 6 Department of Pathology, Montreal Neurological Hospital, McGill University, Montreal, Quebec, Canada, 7 Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada; Department of Human Genetics, McGill University, Montreal, Quebec, Canada * To whom correspondence should be addressed. E-mail: danuta.radzioch{at}muhc.mcgill.ca.
Rationale: Allergic asthma is a heterogeneous disease whose pathology is a result of improper immune responses to innocuous antigens. We and others have previously shown that one of the Toll-like Receptor (TLR) 7/8 ligands, the synthetic compound S28463 (Resiquimod, R-848) is able to inhibit acute allergic asthma in mice. Objectives: Given that the efficiency of this pharmacological compound against the smooth muscle mass increase and goblet cell hyperplasia that are characteristic of chronic allergic asthma has not been previously assessed, we investigated the ability of this compound to prevent these aspects of chronic airway remodeling. Methods: The impact of S28463 treatment was assessed in a Brown Norway rat model of chronic asthma by histological, morphometric and molecular techniques. Main Results: We demonstrate that treatment with S28463 is able to prevent the development of goblet cell hyperplasia and increases in airway smooth muscle mass, and that this effect is at least partially mediated by inhibiting proliferation of goblet and smooth muscle cells, respectively. Furthermore, we show that the abrogation of airway remodeling is preceded by the inhibition of the inflammatory reaction normally occurring in response to allergen challenge in sensitized animals. This inhibition was associated with a reduction of both TH1 and TH2 cytokine protein expression in the lungs, demonstrating the potent anti-inflammatory effect of this pharmaceutical compound in the context of allergic reactions. Conclusion: Taken together, our results indicate great potential for the use of S28463 as an anti-inflammatory therapeutic agent for the management of chronic asthma. Key words: Resiquimod, R-848, Imidazoquinoline, Airway remodeling, Toll-like Receptor (TLR)
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