Circulating CircRNAs Panel Acts as a Biomarker for the Early Diagnosis and Severity of Parkinson's Disease

Abstract

Parkinson's disease (PD) is a chronic and progressive degenerative disease of the central nervous system. Degenerative neuropathy can occur in patients with PD even before typical clinical symptoms appear in the preclinical stage. Therefore, if the early diagnosis of degenerative diseases can be timely and the correlation with the disease progression can be explored, the disease progression will be slowed down and the quality of life of patients will be improved. In this study, the circRNA microarray was employed to screen the dysregulated circRNA in plasma samples of PD. Four circRNAs (circ_0085869, circ_0004381, circ_0017204, and circ_0090668) were obtained with increased levels in PD patients by cross comparison and preliminary verification in PD comparing with healthy controls. Further validation found the circRNA panel was consistent with the training set. The ROC curve also revealed a high diagnostic ability of circ_0004381 and circ_0017204 in predicting the early stage of PD from healthy controls. circ_0085869, circ_0004381, circ_0017204, and circ_0090668 also presented a high ability to distinguish the late stage of PD from early stage. In conclusion, circulating circRNA panel might be a potential fingerprint for predicting the early diagnosis of PD and may act as a biomarker for disease progression.

Keywords: PD; ROC Curve; circRNA; plasma; risk score function.

FIGURE 1

The landscape of circRNA expression in plasma sample of PD and healthy controls. (A) Cluster analysis of differently expressed circRNAs (three plasma samples from patients diagnosed with PD and three healthy controls). (B) The scatter plots of dysregulated circRNAs in different stage of PD comparing with healthy control. (C) Candidate gene pathway enrichment.

FIGURE 2

CircRNA expression in training set. (A) The relative expression level of six circRNAs in PD patients and healthy control used in microarray detection. (B) Total 20 paired plasma from PD patients in each group, and 20 controls were used in RT-qPCR analysis. Data was presented as mean ± SEM. Data was analyzed with student t-test. n.s. indicated no significant, * indicated p < 0.05 and ** indicated p < 0.01.

FIGURE 3

Validation of candidate circRNA in validation set. Total 80 paired plasma from PD patients with different stages, and 80 healthy controls were used in RT-qPCR analysis. Data was presented as mean ± SEM. Data was analyzed with student t-test, * indicated p < 0.05.

FIGURE 4

Relative expression of circRNA panel in PD subgroups. (A) Relative expression of circRNA panel in males and females of PD. (B) Relative expression of circRNA panel in PD for different age groups of onset. Data was presented as mean ± SEM. * indicated p < 0.05, n.s. indicated no significant.

FIGURE 5

ROC analysis of circRNA panel predicting early PD (stage 1) by using risk score analysis. (A) Training set. (B) Validation set.

FIGURE 6

ROC analysis of circRNA panel predicting late PD (stage 2–5) by using risk score analysis. (A) Training set. (B) Validation set.

FIGURE 7

Stability detection of circRNA panel in human plasma. RT-qPCR was applied for detecting the expression level of the four circRNAs. Data was presented as mean ± SEM with log-transformed. No significant difference was observed in each group.