Pathogenicity of a disease-associated human IL-4 receptor allele in experimental asthma. Mus musculus

Polymorphisms in the interleukin-4 receptor α chain (IL-4Rα) have been linked to asthma incidence and severity, but a causal relationship has remained uncertain. In particular, a glutamine to arginine substitution at position 576 (Q576R) of IL-4Rα has been associated with severe asthma, especially in African Americans. We show that mice carrying the Q576R polymorphism exhibited intense allergen-induced airway inflammation and remodeling. The Q576R polymorphism did not affect proximal signal transducer and activator of transcription (STAT) 6 activation, but synergized with STAT6 in a gene target– and tissue-specific manner to mediate heightened expression of a subset of IL-4– and IL-13–responsive genes involved in allergic inflammation. Our findings indicate that the Q576R polymorphism directly promotes asthma in carrier populations by selectively augmenting IL-4Rα–dependent signaling. Keywords: Cell population analysis Overall design: To determine potential mechanisms underlying the trophic effects of the R576 allele on airway inflammation and remodeling, we first compared the gene expression profile in the lungs of doxycycline-treated B6.129Il4raR576/R576/IL-13tg mice versus B6.129Il4raR576/R576 littermates that lacked the IL-13tg (n = 11 and 5, respectively). We similarly compared the gene expression profile in the lungs of doxycycline-treated B6.Il4raQ576/Q576/IL-13tg mice versus tg-negative littermates (n = 8 and 5, respectively). Lastly, we directly compared the gene expression profiles in the doxycycline-treated B6.129Il4raR576/R576/IL-13tg versus B6.Il4raQ576/Q576/IL-13tg mice.