The Study Of Specific MicroRNA In Plasma As Early Diagnosis Biomarkers In Manganese-induced Parkinsonism

Objective: Manganese can enter the body through various ways and accumulate in the human body,resulting in progressive and persistent neurotoxic effects,known as manganism.The early stage of manganism is similarity neurotic symptom and autonomic nervous dysfunction.Continuous progress will lead to damage of extrapyramidal system of central nervous system,the clinical manifestations and neuropathological biochemistry are similar to Parkinson's disease(PD).The development of manganism to advanced stage is delayed and irreversible.Therefore,the discovery of disease-specific early diagnostic markers has great economic and social benefits in order to obtain early diagnosis and treatment.The purpose of this study was to screen microRNA(microRNA)specifically expressed in plasma of patients with manganese-induced parkinsonism,and to explore the diagnostic value of plasma microRNA as an early biomarker of manganese-induced parkinsonism.Methods: MicroRNAs in peripheral blood of manganese-induced parkinsonism group,mild manganism group,Parkinson's disease group and healthy control group were collected for second generation sequencing and screening of differentially expressed microRNAs.Quantificational Real-time Polymerase Chain Reaction(qRT-PCR)was used to verify the expression level.The function of differentially expressed microRNAs was explored by bioinformatics analysis.Results: By second generation sequencing,15182448 Raw data were obtained for each sample.After removing the low-quality,short and Poly-A sequence,the average number of clean data for each sample was 14459404.There were significant differences in the expression of 222 microRNAs between the manganese-induced parkinsonism group and the normal control group.There were significant differences in the expression of 462 microRNAs between the mild manganism group and the normal control group.There were significant differences in the expression of 204 microRNAs between the Parkinson's disease group and the normal control group(log2 FC > 1.0,P < 0.05).There were 71 identical microRNAs significantly up-regulated in manganese-induced parkinsonism group and mild manganism group The four microRNAs that regulate the key proteins in chaperone-mediated autophagy were predicted and verified by qRT-PCR.The results showed that the levels of miR-3120,miR-301 b and miR-21 in mild manganism group were significantly higher than those in normal control group,and there was no significant difference in miR-370;The expression of miR-3120 in mild manganism group was significantly higher than that in Parkinson's disease group,There was no difference in the expression of microRNA-301 b,microRNA-21 and microRNA-370 between the two groups;there was no significant difference in miR-3120,miR-301 b,miR-370 and miR-21 between manganese-induced parkinsonism group and mild manganism group.there was no significant difference in miR-3120?miR-370 and miR-21 between parkinson's disease group and normal control group,and the level of microRNA-301 b in the Parkinson's disease group was significantly lower than that in the normal control group(P<0.05).Conclusions :(1)Manganese-induced parkinsonism and Parkinson's disease have different expression profiles of microRNAs in peripheral plasma;(2)Chronic manganese exposure can significantly up-regulate the expression of miR-3120 and miR-301 b which targeting HSP70 and miR-21 which targeting LAMP-2A,leading to abnormal aggregation of protein transformation and degradation damage,which may be the main pathogenesis of manganese poisoning;(3)miR-3120 is expected to be an early specific biomarker for differentiating Manganese-induced parkinsonism from primary Parkinson's disease.