In their review they discuss the role of AhR in asthma and COPD, focusing upon how AhR modulates the immunological responses in allergic and inflammatory diseases such as bronchitis, asthma, and chronic obstructive pulmonary disease (COPD) and the crosstalk of AhR signaling with other ligand-activated transcription factors such as peroxisome proliferator-activated receptors (PPARs). This evidence concerns the gene AHR and chronic obstructive pulmonary disease.