Human TH1 and TH2 cells targeting rhinovirus and allergen coordinately promote allergic asthma.

BACKGROUND: Allergic asthmatic subjects are uniquely susceptible to acute wheezing episodes provoked by rhinovirus. However, the underlying immune mechanisms and interaction between rhinovirus and allergy remain enigmatic, and current paradigms are controversial. OBJECTIVE: We sought to perform a comprehensive analysis of type 1 and type 2 innate and adaptive responses in allergic asthmatic subjects infected with rhinovirus. METHODS: Circulating virus-specific TH1 cells and allergen-specific TH2 cells were precisely monitored before and after rhinovirus challenge in allergic asthmatic subjects (total IgE, 133-4692 IU/mL; n = 28) and healthy nonallergic controls (n = 12) using peptide/MHCII tetramers. T cells were sampled for up to 11 weeks to capture steady-state and postinfection phases. T-cell responses were analyzed in parallel with 18 cytokines in the nose, upper and lower airway symptoms, and lung function. The influence of in vivo IgE blockade was also examined. RESULTS: In uninfected asthmatic subjects, higher numbers of circulating virus-specific PD-1+ TH1 cells, but not allergen-specific TH2 cells, were linked to worse lung function. Rhinovirus infection induced an amplified antiviral TH1 response in asthmatic subjects versus controls, with synchronized allergen-specific TH2 expansion, and production of type 1 and 2 cytokines in the nose. In contrast, TH2 responses were absent in infected asthmatic subjects who had normal lung function, and in those receiving anti-IgE. Across all subjects, early induction of a minimal set of nasal cytokines that discriminated high responders (G-CSF, IFN-γ, TNF-α) correlated with both egress of circulating virus-specific TH1 cells and worse symptoms. CONCLUSIONS: Rhinovirus induces robust TH1 responses in allergic asthmatic subjects that may promote disease, even after the infection resolves.

Wheezing exacerbations in early childhood: evaluation, treatment, and recent advances relevant to the genesis of asthma.

Children who begin wheezing during early childhood are frequently seen by health care providers in primary care, in hospitals, and in emergency departments, and by allergists and pulmonologists. When a young child, such as the 2 year-old patient presented here, is evaluated for wheezing, a frequent challenge for clinicians is to determine whether the symptoms represent transient, viral-induced wheezing or whether sufficient risk factors are present to suspect that the child may experience recurrent wheezing and develop asthma. Most factors that influence prognosis are not mutually exclusive, are interrelated (ie, cofactors), and often represent gene-environment interactions. Many of these risk factors have been, and continue to be, investigated in prospective studies to decipher their relative importance with the goal of developing new therapies and interventions in the future. The etiologies of wheezing in young children, diagnostic methods, treatment, prognostic factors, and potential targets for prevention of the development of asthma are discussed.