PM2.5-induced lung injury in rats: Identification of differential circRNAs and analysis of circRNA–miRNA–mRNA regulatory networks

Exposure to high levels of fine particulate matter (PM) over a long period is strongly associated with an increased risk of morbidity and mortality from respiratory diseases. Although PM 2.5 has been demonstrated to cause lung damage, the exact mechanisms are not fully understood. In this study, six-week-old SPF-grade SD rats were used as an experimental model for PM 2.5 exposure via the endotracheal drip method. A library of circRNAs in rat lung tissues was constructed, and 16,020 circRNAs were successfully predicted, with the highest percentage being of the all-exon type. Validation of the screened differentially expressed circRNAs (DEcircRNAs) was performed using an RNase R digestion assay, Sanger sequencing, and RT-qPCR. In addition, bioinformatics analyses were used to predict the potential miRNA binding sites of the circRNAs and the target genes of miRNAs. A circRNA–miRNA–mRNA regulatory network was constructed and validated through miRNA pull-down experiments. The results showed that exposure to PM 2.5 significantly altered the expression profile of circRNAs in rat lung tissue. The DEcircRNAs and their host genes were found to be primarily associated with physiological processes such as neuromuscular regulation. The constructed circRNA–miRNA–mRNA regulatory network indicated that circRNA4503, circRNA4511, and ciRNA131 (asso-type circRNA131) can adsorb miR-340–5p via the ceRNA mechanism. This process regulates the expression of the target genes DMD, HECW2 , and SGIP1 , which play a role in the pathological processes of lung diseases. In conclusion, this study establishes a new theoretical foundation for understanding the molecular mechanisms underlying PM 2.5 -induced lung injury. PM 2.5 enters the lungs through respiration, resulting in altered circRNA expression profiles. Among them, circRNA4503, circRNA4511, and ciRNA131 are highly likely to release miR-340–5p through the ceRNA mechanism, affecting the expression levels of target genes DMD, HECW2, and SGIP1, and thus are deeply involved in the pathological process of lung diseases. • PM 2.5 causes altered gene expression profiles of rat lung circRNAs. • Construction of a circRNA-miRNA-mRNA regulatory network stimulated by PM 2.5 . • circ4503/4511/ci131 targets miR-340–5p, modulating DMD/HECW2/SGIP1 in lung injury.