Influence of recurrent viral respiratory tract infections on lung function trajectories

Recurrent respiratory viral infections in early childhood have been suggested as a major risk factor for asthma development. We propose that recurrent exposure to viral components lead to a lung function trajectory which favors the development of chronic lung diseases. Therefore, one-week-old C57BL/6J wildtype mice were exposed to poly(I:C), as surrogate for viral double stranded RNA, for four times in the first four weeks. Non-invasive lung function was recorded over twelve weeks. Six weeks after the last exposure, mice were sacrificed after a final invasive lung function measurement and bronchoalveolar lavage, serum, and lungs were obtained. Our findings showed that recurrent early poly(I:C) exposure had no physiological effect on spontaneous breathing pattern, body weight and growth, but led to structural changes of the lung: The dynamic and static compliance of poly(I:C)-exposed mice as well as the alveoli size was increased. In conclusion, recurrent exposure to poly(I:C) in early childhood led to emphysematous features in mice that might favor the development of chronic lung diseases.