hsa_circ_0015388 Reduces Macrophage Derived Reactive Oxygen Species in Crohn’s Disease

Abstract Background Crohn’s disease (CD) is a refractory inflammatory bowel disease with an unclear etiology. CircularRNA (circRNA) has been highlighted as a novel class of functional noncoding RNAs associated with the pathogenesis of various diseases. However, the functions of circRNA in CD remain unclear. Methods Biopsies were obtained from noninflammatory sites in the terminal ileum of the CD group (n = 4) and non-CD group (n = 4) and analyzed for circRNA expression using RNA sequencing. The significantly altered circRNAs were validated in the CD group (n = 45) and non-CD group (n = 15) using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Transcriptome analysis was conducted using circRNA-downregulated macrophage-like THP-1 cells. Reactive oxygen species (ROS) levels, cytokine mRNA expression, phagocytosis, and migration were evaluated in circRNA-downregulated THP-1 cells. Results CircularRNA sequencing analysis revealed significant differences in 31 circRNAs between the CD group and non-CD group. Quantitative reverse transcriptase-polymerase chain reaction analysis for each circRNA demonstrated significant upregulation of hsa_circ_0015388 in the CD group. Hsa_circ_0015388 was expressed in THP-1 cells, but not in HCEC-1CT and Caco-2/bbe. Transcriptome analysis in THP-1 cells transfected with scramble or hsa_circ_0015388 siRNA (small interfering RNA) showed a significant alteration in innate immune response related pathway. Reactive oxygen species production was significantly increased in the hsa_circ_0015388 downregulated THP-1 cells. Reactive oxygen species induction in the hsa_circ_0015388 knocked down THP-1 was diminished by the inhibition of TNFSF10. Conclusion A comprehensive analysis of circRNA expression revealed that 31 circRNAs were dysregulated in the CD group. Hsa_circ_0015388 is expressed in macrophages and negatively regulates ROS function inhibiting the TNFSF10 pathway. This study first revealed that hsa_circ_0015388 plays a role in the pathogenesis of CD by suppressing ROS production in macrophages.