Bcl11b Regulates IL-17 Through the TGF-β/Smad Pathway in HDM-Induced Asthma.

Purpose: T helper (Th) 17 cells play a critical role in the development of asthma, but the underlying mechanism of how interieukin (IL)-17 is regulated in allergic airway inflammation is poorly understood. In this study, we investigated the impact of Bcl11b on Th17 response in asthma. Methods: Blood samples from patients with mild asthma (MA) and severe asthma (SA) were collected. Expression of Bcl11b, IL-4, IL-5, IL-13, IL-17A and transforming growth factor (TGF)-beta 1 were determined in CD4(+) T cells and plasma by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Relative mRNA and protein levels of Bcl11b, IL-17A and genes involved in the TGF/Smad signaling pathway were examined by PCR, ELISA and western blot analysis in house dust mite (HDM)-challenged mice. Ectopic expression of Bcl11b in HDM-stimulated primary mouse splenocytes was achieved by nucleofection of Bcl11b expression plasmid. Results: We found significantly decreased Bcl11b but increased IL-17A and TGF-beta 1 expression in patients with asthma and a strongly negative correlation between Bcl11b and these 2 cytokines in SA patients. Similar expression patterns of Bcl11b, IL-17A and TGF-beta 1 were also found in mice with HDM-induced allergic airway inflammation. We demonstrated further that Smad2/3 phosphorylation was increased in HDM-challenged mice and that ectopic expression of Bcl11b in HDM-stimulated primary mouse splenocytes reduced Smad2 phosphorylation and IL-17 expression. Conclusions: Our findings demonstrate a potential effect of Bcl11b in controlling IL-17-mediated inflammation in asthma and suggest that Bcl11b may be a useful therapeutic target for asthma.