Identification of Blood Circular RNAs as Potential Biomarkers for Acute Ischemic Stroke

Abstract

Many hospitals lack facilities for accurate diagnosis of acute ischemic stroke (AIS). Circular RNA (circRNA) is highly expressed in the brain and is closely associated with stroke. In this study, we examined whether the blood-borne circRNAs could be promising candidates as adjunctive diagnostic biomarkers and their pathophysiological roles after stroke. We profiled the blood circRNA expression in mice subjected to experimental focal cerebral ischemia and validated the selected circRNAs in AIS patients. We demonstrated that 128, 198, and 789 circRNAs were significantly altered at 5 min, 3 h, and 24 h after ischemic stroke, respectively. Our bioinformatics analysis revealed that the circRNA-targeted genes were associated with the Hippo signaling pathway, extracellular matrix-receptor interaction, and fatty acid metabolism at 5 min, 3 h and 24 h after ischemic stroke, respectively. We verified that many of these circRNAs existed in the mouse brain. Furthermore, we found that most of the predicted circRNA-miRNA interactions apparently exhibited functional roles in terms of regulation of their target gene expression in the brain. We also verified that many of these mouse circRNAs were conserved in human. Finally, we found that circBBS2 and circPHKA2 were differentially expressed in the blood of AIS patients. These results demonstrate that blood circRNAs may serve as potential biomarkers for AIS diagnosis and reveal the pathophysiological responses in the brain after ischemic stroke.

RNA-seq Identifies circRNAs Expression Profiles and Potential Biomarkers for Intracerebral Hemorrhage

“…These characteristics make circRNAs promising biomarkers in many human diseases [14]. In the stroke eld, circRNA expression pro le changes in IS have been described, supporting circRNAs as potential biomarkers and therapeutic targets in IS [21][22][23][24][25]. Additionally, two recent studies revealed that the circRNA expression pro les signi cantly changed after ICH in rat brain tissues [26,27].…”

“…There is growing evidence that circRNAs could serve as potential biomarkers in peripheral blood in coronary artery disease, early preeclampsia and cancers [16][17][18][19][20]. Moreover, multiple recent studies have reported circRNA expression pro les changed in ischemic stroke (IS) [21][22][23][24][25], suggesting that circRNAs are potential biomarkers and therapeutic targets in IS. In addition, two recent studies reported that circRNA expression pro les are altered after ICH in rat brain tissue [26,27].…”

Circular RNA circCCDC9 alleviates ischaemic stroke ischaemia/reperfusion injury via the Notch pathway

“…As the blood‐brain barrier was impaired during acute ischaemic stroke, differentially expressed circRNAs enter the bloodstream and thereby can be used as biomarkers for evaluating the progression of stroke. A study profiling the expression of circRNAs in the blood of mice with induced focal ischaemic stroke suggested that circPHKA2 and circBBS2 were promising markers for diagnosing acute ischaemic stroke 25 . Plasma circDLGAP4 is thought to be a promising biomarker for the diagnosis and evaluation of ischaemic brain damage 13 .…”

The role of circular RNAs in brain and stroke

“…While using rodent models, 128, 198, and 789 circRNAs were found to be significantly changed at 5 min, 3 h, and 24 h after IS in mice blood sample. After validation by IS patient blood sample, hsa-circ-0090002 and hsa-circ-0039457 were reported to be differentially downregulated [53]. Besides, after 45minute-transient middle cerebral artery occlusion (MCAO), circRNA microarrays revealed that 1027 circRNAs were significantly changed in 48 hours after reperfusion in the ischemic brain versus the sham group in which 914 circR-NAs were notably increased, while the other 113 were notably decreased.…”

“…KEGG pathway analysis predicted that mmu-circRNA-015947 might be involved in apoptosis, metabolism and immune-related pathways, which are known to play a role in cerebral I/R injury [58]. The detailed information summary is shown in Table 1 [49][50][51][52][53][54][55][56][57][58]. Besides, circHECTD1 expression was upregulated in IS recurrence patients versus non-recurrence patients (160 : 160).…”