Noncoding RNAs: New Players in Pulmonary Medicine and Sarcoidosis.

Noncoding RNAs (ncRNAs) are coded by 98% of human genomic DNA. They are grouped into two major classes according to length: small ncRNAs and long ncRNAs. They regulate genome organization, stability, and physiological processes that maintain cellular homeostasis. Recently, great interest has emerged in ncRNAs because of their significant roles in the development of inflammatory diseases, including sarcoidosis. Some have been introduced as novel markers for disease activity, such as increased levels of microRNA-34a in peripheral blood mononuclear cells of patients with sarcoidosis, re-emphasizing the inflammatory component in sarcoidosis. They are also important factors in the outcome of sarcoidosis. Dysregulation of microRNA-let7f leads to overexpression of profibrotic factors and could be related to the pathogenesis of pulmonary fibrosis in patients with sarcoidosis, owing to their stimulatory effect on collagen expression and deposition. However, many unanswered questions remain about the association of ncRNAs and sarcoidosis. By understanding the functions of ncRNAs in T-helper cell type 1 and T-helper cell type 17, we may uncover the mechanism of action of those cells in sarcoidosis. Further translational research is needed to define the RNA gene fingerprint of different sarcoidosis stages.