IRF5 distinguishes severe asthma in humans and drives Th1 phenotype and airway hyperreactivity in mice.

Severe asthma (SA) is a significant problem both clinically and economically, given its poor response to corticosteroids (CS). We recently reported a complex type 1-dominated (IFN-γ-dominated) immune response in more than 50% of severe asthmatics despite high-dose CS treatment. Also, IFN-γ was found to be critical for increased airway hyperreactivity (AHR) in our model of SA.

Mitochondrial H2O2 in Lung Antigen-Presenting Cells Blocks NF-κB Activation to Prevent Unwarranted Immune Activation.

Inhalation of environmental antigens such as allergens does not always induce inflammation in the respiratory tract. While antigen-presenting cells (APCs), including dendritic cells and macrophages, take up inhaled antigens, the cell-intrinsic molecular mechanisms that prevent an inflammatory response during this process, such as activation of the transcription factor NF-κB, are not well understood. Here, we show that the nuclear receptor PPARγ plays a critical role in blocking NF-κB activation in response to inhaled antigens to preserve immune tolerance.