Lower Airway Rhinovirus Burden and the Seasonal Risk of Asthma Exacerbation.
Am J Respir Crit Care Med. 2011 Aug 4;
Authors: Denlinger LC, Sorkness RL, Lee WM, Evans M, Wolff M, Mathur S, Crisafi G, Gaworski K, Pappas TE, Vrtis R, Kelly EA, Gern JE, Jarjour NN
RATIONALE: Most asthma exacerbations are initiated by viral upper respiratory illnesses. It is unclear whether HRV-induced exacerbations are associated with greater viral replication and neutrophilic inflammation compared to HRV colds. OBJECTIVES: To evaluate viral strain and load in a prospective asthma cohort during a natural cold. METHODS: Adults were enrolled at the first sign of a cold with daily monitoring of symptoms, medication use, and peak expiratory flow rate until resolution. Serial nasal lavage and induced sputum samples were assessed for viral copy number, and inflammatory cell counts. MEASUREMENTS AND MAIN RESULTS: Fifty-two persons with asthma and 14 non-atopic, non-asthmatic controls were studied for over 10 weeks/subject on average; twenty-five participants developed an asthma exacerbation. Detection of human rhinoviruses (HRV) in the preceding 5 days was the most common attributable exposure related to exacerbation. Compared to other infections, those by a minor group A HRV were 4.4-fold more likely to cause exacerbation (p = 0.038). Overall, sputum neutrophils and the burden of rhinovirus in the lower airway were similar in non-atopic controls and the asthma group. However, among HRV-infected participants with asthma, exacerbations were associated with greater sputum neutrophil counts (p = 0.005). CONCLUSIONS: HRV infection is a frequent cause of exacerbations in adults with asthma and a cold and there may be group-specific differences in severity of these events. The absence of large differences in viral burden among groups suggests differential lower airway sensitization to the effects of neutrophilic inflammation in the patients having exacerbations.
PMID: 21816938 [PubMed – as supplied by publisher]
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