The Role of Circulating CircRNAs and MicroRNAs in Acute Lung Injury

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a devastating cause of morbidity and mortality characterized by alveolar epithelial and endothelial injury. Despite recent advances in pathogenetic mechanisms and therapy strategies of ALI, efforts to identify circulating factors that predict severity of ALI/ARDS patients have been unrevealing. Circular RNAs (circRNAs) are a novel class of endogenous non-coding RNA with a covalently continuous closed-loop structure. Compared with traditional linear RNAs, circRNAs are more stable and resistant to RNase R due to the absence of 5' caps and 3' tails, which show clear advantages in acting as novel molecular biomarkers for many diseases. In addition, many studies have reported that circRNAs can bind to microRNAs (miRNAs), acting as "miRNA sponges" which are named competitive endogenous RNAs (ceRNAs), and can regulate gene expression at the transcriptional or post-transcriptional level. Evidence indicates that circRNAs play important roles in cancers and other diseases such as tuberculosis and intervertebral disc degeneration. As no published research has studied the expression and role of circRNAs in the pathology and pathogenesis of ALI/ARDS, the investigators aimed to validate the aberrant expression of circRNAs in ALI/ARDS and explore the potential pathological mechanism in which circRNAs are involved.