LAUSR

Respiratory viral infections are common in the general population and one of the most important causes of asthma aggravation and exacerbation. Despite many studies, it is not well understood how viral infections cause more severe symptoms and exacerbations in asthmatics. We develop a mathematical model of two types of macrophages that play complementary roles in fighting viral infection: classically $$(\hbox {CA}$$(CA-$$\hbox {M}\Phi )$$MΦ) and alternatively activated macrophages $$(\hbox {AA}$$(AA-$$\hbox {M}\Phi )$$MΦ). $$\hbox {CA}$$CA-$$\hbox {M}\Phi $$MΦ destroy infected cells and tissues to remove viruses, while $$\hbox {AA}$$AA-$$\hbox {M}\Phi $$MΦ repair damaged tissues. We show that a higher viral load or longer duration of infection provokes a stronger immune response from the macrophage system. By adjusting the parameters, we model the differences in response to respiratory viral infection in normal and asthmatic subjects and show how this skews the system toward a response that generates more severe symptoms in asthmatic patients.