Farnesoid X receptor (FXR) as a potential therapeutic target for lung diseases: a narrative review

Farnesoid X receptor (FXR), which is encoded by the gene, is a ligand-activated transcription factor and a member of the nuclear receptor (NR) superfamily. As a receptor for bile acid (BA), FXR has been shown to play a key role in the regulation of BA metabolism, lipid metabolism, and the inflammatory response. This article reviews the roles of FXR in the pathogenesis of various lung diseases, and identifies potential diagnostic indicators or therapeutic targets for these diseases. The PubMed and National Center for Biotechnology Information (NCBI) online databases were searched to retrieve relevant articles published from 2000 to 2024. FXR was originally found to be expressed in BA-targeted organs, such as the liver and intestine. However, recent studies have shown that FXR is also expressed in "non-classical" BA-targeted organs, such as the lung and blood vessels. FXR is not only involved in the pathophysiology of a series of diseases of the gastrointestinal tract and liver, but is also involved in various lung diseases. Recent evidence suggests that FXR participates in the pathogenesis of lung diseases through multiple mechanisms. In addition, FXR may be a potential therapeutic target for some lung diseases. For example, FXR has been reported to promote the occurrence and development of non-small cell lung cancer (NSCLC) by inducing the expression of programmed death ligand 1 (PD-L1) and subsequently suppressing anti-tumor immunity in the tumor microenvironment. In this review, we summarized the current knowledge of the roles of FXR in different lung diseases. A better understanding of the roles and mechanisms of FXR in lung diseases will provide new perspectives for the treatment of lung diseases.