Recurrent viral infections during the early years of life cripple a protective immune mechanism in mice and increase the risk of asthma, according to a study published online in Nature Medicine. The identification of this pathway aids our understanding of how environmental triggers may increase the risk of immune disorders in adulthood.
Though recurrent viral infections early in people’s life increase their risk of developing asthma, newborns can be protected from developing allergies through proteins transferred in breast milk. In fact, previous studies have shown that exposure of nursing mice to low doses of allergens protects the newborns from asthma.
Anuradha Ray and colleagues found that breastfed newborn mice protected from asthma, which were repeatedly infected with respiratory syncytial virus no longer exhibited this protective effect and were susceptible to asthma later in life. The virus induces an inflammatory response in the lung that impairs the function of protective immune cells termed regulatory T cells. In turn, these cells produce inflammatory mediators that promote allergic responses.