A collaborative study led in the laboratories of Prof. Fabrice Bureau (Welbio investigator at ULg), Dr. Thomas Marichal and Sebastian Johnston (Professor at Imperial College London and Director of the MRC & Asthma UK in Allergic Mechanisms of Asthma) helps to elucidate how the virus responsible for the seasonal cold shapes our immune system to promote severe exacerbations of asthma in individuals suffering from their disease. The results of this study haves been published in Nature Medicine.
The first author of the study, Dr. Marie Toussaint (a Belgian postdoctoral researcher in Professor Johnston's laboratory), first discovered that during a rhinovirus infection in asthmatic individuals, self DNA was rapidly released and detected in the airways of these patients, in a place where it is not found in normal conditions. In addition, the larger the amounts of DNA detected, the more individuals developed severe respiratory symptoms of asthma exacerbation. These human data therefore suggested that self DNA could be responsible for these exacerbations.
In order to study in details the role played by self DNA, Dr. Toussaint developed an experimental model of asthma exacerbation induced by rhinovirus in mice. As observed in humans, rhinovirus induced an exaggeration of the asthmatic response in mice, but also the release of DNA in the airways. Surprisingly, the treatment of these rhinovirus-infected mice with a DNA-degrading compound completely cured them of asthma exacerbations! Moreover, DNA injection alone recapitulated many of the asthmatic symptoms induced by rhinovirus, which clearly demonstrates the involvement of self DNA in exacerbations.
In conclusion, this international study identifies an entirely new and important role for host DNA in asthma exacerbations induced by the cold virus. It suggests that controlling the release of DNA into the respiratory tract or accelerating its elimination represent potential therapeutic options for the treatment of viral-induced asthma exacerbations.
References : Toussaint M. et Al, Host DNA released by NETosis promotes rhinovirus-induced type-2 allergic asthma exacerbation. Nature Medicine (2017) doi: 10.1038/nm.4332