Genetic and non-genetic risk factors of idiopathic pulmonary fibrosis: A review

Idiopathic pulmonary fibrosis (IPF) is the most common form of fibrosis of internal organs. The etiology and pathogenesis of IPF are still not well understood. However, a growing line of evidence shows that both genetic and non-genetic factors contribute to IPF development. The release of pro-inflammatory cytokines activates the immune cells. The enhanced synthesis of interleukins and cytokines, especially transforming growth factor β1 leads to the proliferation of fibroblasts, increased extracellular matrix formation, and epithelial-mesenchymal transformation of the lung tissue. These pathological changes could lead to fibrosis. Polymorphisms of genes responsible for the function of mucociliary clearance (MUC5B), telomerases (TERT, TERC), as well as signaling pathway related-genes such as Sonic hedgehog, Wnt, and some other genes are also risk factors for IPF development. Epigenetic regulatory mechanisms, such as methylation and acetylation of DNA and histones, may also influence the development and progression of this disease. At present, the role of non-coding RNAs, in particular long non-coding RNAs (lncRNA) in the development of fibrotic processes, is actively studied. LncRNA is an RNA that is longer than 200 base pairs and does not code for any proteins. LncRNAs perform various functions in the cell, from nuclear compartmentation to epigenetic regulation of gene expression and post-translational modification of proteins. In this review, we present the important aspects in the pathogenesis of IPF.