Differently Expressed Circular RNAs in Lacrimal Sacs From Patients With Chronic Dacryocystitis

This study was designed to identify differently expressed circular RNAs (circRNAs) and investigate their potential roles in lacrimal sacs from patients with chronic dacryocystitis. The lacrimal sac samples of three chronic dacryocystitis patients and three control subjects were collected for RNA sequencing after ribosomal RNA was depleted. Differently expressed circRNAs and messenger RNAs (mRNAs) were used for co-expression analysis. CircRNA-microRNA (miRNA)-mRNA interaction network were also established by miRanda software. Meanwhile, pathway and functional enrichment analysis were conducted for the down- and up-regulated mRNAs in the circRNA-mRNA co-expression network. The expression levels of circRNAs and mRNAs in chronic dacryocystitis and control samples were validated by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). In all the 3,909 circRNAs predicted through RNA sequencing, 25 circRNAs (20 up-regulated and 5 down-regulated) expressed differently in chronic dacryocystitis samples. Besides, there identified 1,486 differentially expressed mRNAs. Of these differently expressed circRNAs and mRNAs, eight were validated by qRT-PCR, including MYH2, DSP, CD27, CCL5, FN1, has_circ_0004792, has_circ_0001062, and has_circ_0115476. Gene Ontology (GO) analysis indicated that the majority of altered mRNAs in this co-expression network were involved in immune system processes and meanwhile Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these altered expressed mRNAs were also amplified in bacterial invasion of epithelial cells, both of which were thought to be involved in the pathogenesis of chronic dacryocystitis. In the circRNA-miRNA-mRNA interaction network, six circRNAs were found to be related to Th1 and Th2 cell differentiation, which was closely associated with the development of chronic dacryocystitis. This study identified statistically significant differences between circRNAs and mRNAs of lacrimal sac samples of chronic dacryocystitis patients and control individuals and provides novel insight into the regulatory mechanism of circRNAs, miRNAs, and mRNAs in the pathogenesis of chronic dacryocystitis.