Polycyclic aromatic hydrocarbon-aryl hydrocarbon receptor signaling regulates chronic inflammation in lung-gut axis

Polycyclic aromatic hydrocarbons (PAHs) are broadly identified in environmental pollutants and also formed during the heat processing of meat, including grilling, roasting, smoking, and frying, particularly at high temperatures. Besides, the PAHs influence inflammatory response through activation of aryl hydrocarbon receptor (AhR) signaling. Recently, the role of the PAHs/AhR axis in inflammatory diseases has attracted major attention in the regulation of lung function, gut barrier function, and systemic inflammation. Many experiments have been conducted to determine the role of the PAHs/AhR/cytochrome P450 1A1 signaling activation on elevation of inflammation in the lung-gut axis. In contrast, several dietary AhR ligands can improve inflammatory function by modulating the AhR signaling, thereby strengthening the intestinal barrier. This review includes the pivotal roles of xenobiotic and diet-derived AhR ligands in the regulation of chronic lung diseases and systemic inflammation and their relevance in the lung-gut axis.