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Clinical & Experimental Allergy

Interleukin-1β and interleukin-1ra levels in nasal lavages during experimental rhinovirus infection in asthmatic and non-asthmatic subjects

Authors


Josephine de Kluijver, Lung Function Laboratory, C2-P-62, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands. E-mail: J.de_Kluijver@lumc.nl

Summary

Background Exacerbations of asthma are often associated with rhinovirus (RV)-induced common colds. During experimental RV-infection in healthy subjects, increased levels of the pro-inflammatory mediator IL-1β and the anti-inflammatory IL-1 receptor antagonist (IL-1ra) have been found in nasal lavage.

Objective We postulated that the balance between nasal pro- and anti-inflammatory mediator expression is disturbed in asthma, resulting in more extensive inflammation following RV-exposure in asthma.

Methods We determined IL-1ra, IL-1β, and IL-8 in nasal lavages (days −2, 3, and 6) of non-asthmatics and asthmatics (with and without pre-treatment with the inhaled steroid budesonide) before and after experimental RV16-infection (days 0 and 1).

Results Following RV16-infection, a significant increase in IL-8 was observed in the placebo- and budesonide-treated asthmatics (P=0.033 and 0.037, respectively), whereas IL-1β only increased in the two asthma groups combined (P=0.035). A small, but significant, increase in IL-1ra was only observed in the budesonide-treated asthmatics (P=0.047). At baseline, IL-1ra levels were significantly higher in the non-asthmatics than in the placebo-treated asthmatics (P=0.017).

Conclusion These results demonstrate differences between non-asthmatic and asthmatic subjects in the basal levels of nasal cytokines and their inhibitors, and in the effect of experimental RV-infection on these levels. The results indicate that RV may enhance inflammation more markedly in asthmatics, and suggest that this may in part be explained by lower IL-1ra levels. In addition, the observation that budesonide-treatment may result in higher nasal IL-1ra levels supports the hypothesis that steroids act in part by increasing the endogenous anti-inflammatory screen.

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