Published online: November 10, 2017
Asthma affects approximately 300 million subjects of all ages and constitutes a major part of the allergy epidemic. The ongoing increase in its prevalence has been associated with profound changes in lifestyle and environmental conditions, including sanitation, thus leading to the hygiene hypothesis. To date, studies extending the concept of the hygiene hypothesis to respiratory tract viruses are still lacking.
In a study recently published in The Journal of Allergy and Clinical Immunology (JACI), Skevaki and colleagues aimed to investigate the effects of a preceding influenza virus infection on the development of experimental asthma. They hypothesized that immune cell cross-reactivity between influenza and certain environmental allergens might be responsible for any effects.
Mice were infected with influenza and, once recovered, subjected to an allergen–induced experimental asthma protocol. Immune memory cells from previously influenza infected mice were transferred to allergen-sensitized animals before allergen exposure. A comprehensive bioinformatic analysis assessed homologies between virus- and allergen- derived proteins. Immune cells from influenza-infected mice were stimulated with potentially cross-reactive allergen-derived peptides. Also, mice were immunized with a pool of virus-derived cross-reactive peptides.
The investigators found a long-lasting influenza-mediated preventive effect against allergen-induced experimental asthma in two murine models. Protection could be attributed to memory T cell cross-reactivity. Four influenza- and 3 allergen-derived candidate peptides with cross-reactivity potential were identified. Immunization with a mixture of the influenza peptides conferred asthma protection, and peptide-immunized mice transferred protection through T memory cells.
The aforementioned results illustrate for the first time heterologous protective immunity of virus-infected animals toward allergens. Such findings have important implications for public health policies regarding vaccination and future strategies for peptide vaccine development. Equally important is the extension of the original hygiene hypothesis.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.