Failure to produce enough of an antiviral protein called interferon-lambda may be linked to increased susceptibility to infection with rhinovirus - a common trigger for asthma exacerbations - according to a study by Sebastian Johnston and colleagues in the September 2006 issue of Nature Medicine.
The authors infected volunteers with rhinovirus, a virus that normally causes common colds. They found that clinical markers of lung function impairment were inversely correlated with the amount of interferon-lambda produced by the volunteers' lung cells; volunteers with lower levels of the antiviral protein tended to have worse lung function in response to the viral infection. In parallel studies done on cells directly infected in the lab, the authors also showed that virus replication was linked with the amount of interferon-lambda produced by the cells, and that supplying more interferon-lambda could block virus replication.
The work does not show that a deficiency in interferon-lambda causes asthma - it is possible that not producing enough interferon could be a consequence, not a cause of the asthma in humans - but it does indicate that interferon therapy might be a viable approach to treat asthma exacerbations, particularly those caused by rhinovirus infection.
Sebastian Johnston (Imperial College London, UK)
Abstract available online.
C) Nature Medicine press release.
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