ABSTRACT
Objective:To explore the correlation of serum neurogenic exosome MicroRNA-211-5p(miR-211-5p)levels and brain derived neurotrophic factor(BDNF)levels with cognitive impairment in patients with Parkinson's disease and their diagnostic value.Methods:A total of 80 patients with Parkinson's disease(PD)admitted to the Second Hospital of Jiaxing City from January 2017 to April 2018 were enrolled.According to the Montreal cognitive assessment scale, patients were divided into the cognitive impairment group(n=36)and the non-cognitive impairment group(n=44). Meanwhile, 30 healthy people who took health check-ups during the same period were selected as the control group.Exosomes were extracted from peripheral blood of subjects by using the ExoQuick kit, and the neurogenic exosomes were separated by an L1 cell adhesion molecule(L1CAM)biotinylated antibody.BDNF levels in the exosomes were measured with an enzyme-linked immunosorbent assay(ELISA), and the expression level of miR-211-5p in the exosome was determined by real-time fluorescence quantitative PCR(RT-QPCR).Results:There was a correlation between BDNF and miR-211-5p( r=-0.805, P<0.001)in serum neurogenic exosomes( r=-0.805, P<0.001). BDNF was correlated with miR-211-5p in both the PD and control groups( r=-0.785 and-0.867, P=0.002 and 0.001). The miR-211-5p level was higher and the BDNF level was lower in the PD group than in the control group(0.30±0.08 vs. 0.17±0.04, 0.55±0.06 mg/L vs. 0.75±0.06 mg/L, t=7.125 and 6.368, P=0.000 and 0.000). The BDNF level was lower(0.45±0.07 mg/L vs.0.63±0.07 6.368 and 0.75±0.08 mg/L, t=8.999 and 7.608, P=0.000 and 0.000)and the MiR-211-5p level was higher(0.36±0.07 vs. 0.24±0.05 and 0.17±0.04, t=10.923 and 7.520, P=0.000 and 0.000)in the cognitive impairment group than in the non-cognitive impairment and control groups.The receiver-operating characteristics(ROC)curve showed that the area under the curve of miR-211-5p as a measure for cognitive impairment in Parkinson's disease was 0.860(95% CI: 0.770-0.950)with a threshold of 0.32.The area under the curve of BDNF as a measure for cognitive impairment in Parkinson's disease was 0.891(95% CI: 0.822-0.961)with a threshold of 0.67.BDNF seemed to be the target gene of miR-211-5p, since the latter could inhibit BDNF expression by reducing BDNF mRNA levels. Conclusions:Human serum neurogenic exosome miR-211-5p is highly expressed in PD patients with cognitive impairment and has the potential to be used as one of diagnostic parameters for cognitive impairment in PD patients.The high expression of serum neurogenic exosome miR-211-5p may be related to the inhibition of BDNF by reducing its mRNA levels.