| Objective: Alzheimer’s disease is a neurodegenerative disease,occurring in aged people and remain for a long-term,there are memory disorders,life can not take care of themselves and other symptoms,early detection and treatment is necessary.Recently,nerve imaging can visually show the degree of degeneration in the hippocampus which,determine the severinity of disease,but it it is not economical and feasible as it require prolonged stationary condition of the subject to scan the hippocampus.Biomarkers discovery provides another diagnostic tool for early and rapid detection of AD.In biomarker research,cerebrospinal fluid is considered a gold standard sample,but the sampling process is very difficult due to panic situation during sampling.Alternatively,peripheral blood can reflect the disease to a certain extent,and the sampling is much easier.Use of peripheral blood to find the biological markers of Alzheimer’s disease,is conducive to the diagnosis of the disease.In this study,healthy control,AD and MCI group as the research object,select the appropriate proteomics research technology,based on the applicability of these technologies and advantages and disadvantages,combined use in the experiment to screen out the candidate biomarkers of Alzheimer’s disease,and through a variety of verification methods,is committed to repeated validation to ensure the accuracy of the results,from the candidate biomarkers identified credible biomarker.Methods: In the first part of this study,the proteins i.e Apolipoprotein A1,Haptoglobin,Alpha-1-antitrypsin,Clusterin,C-reative protein,Matrix metalloproteinase 9,Calgranulin A,Calgranulin B and Alpha-2-macroglobulin were selected from the already published literature.These proteins were identified by ELISA technique in patients with Alzheimer’s disease and healthy controls.In the second part of this study,patients with Alzheimer’s disease and healthy controls,the biomarkers of Alzheimer’s disease were studied by using iTRAQ,the protein chip technique and bioinformatics analysis.At the same time,some proteins were identified by ELISA technique and WB,including Afamin and Platelet Basic protein,Fibulin-1,Plasma protease C1 inhibitor,Thrombospondin-1,Inter-alpha-trypsin inhibitor heavy chain H4,Ceruloplasmin and Fibrinogen gamma chain.In the third part of this study,patients with MCI and healthy controls,the expression of differential proteins in two groups was studied by iTRAQ technique.Results: First,a number of biomarkers in the literature were validated,and a total of six proteins were statistically significant.Haptoglobin was significantly up-regulated and the expression levels of Apolipoprotein A1,Alpha-1-antitrypsin,Matrix metalloproteinase 9,Calgranulin A and Calgranulin B were significantly down-regulated.Especially,the trend of Apolipoprotein A1,Calgranulin A and Calgranulin B is found consistent among these six proteins with that reported in the literature.Then,these six proteins were screened by iTRAQ and protein chip technology.Platelet basic protein,Fibulin-1 and Fibrinogen gamma chain were found significantly up-regulated while,Plasma protease C1 inhibitor,Thrombospondin-1,Afamin and Ceruloplasmin significantly down-regulated.Specially,Plasma protease C1 inhibitor trends in ELISA is consistent with previous literature and i TRAQ,the trends of Fibulin-1 and Thrombospondin-1 in ELISA are consistent with iTRAQ,Ceruloplasmin and Fibrinogen gamma chains trends in ELISA are consistent with literature,protein chip and WB.Finally,differential protein was screened from MCI group and control group by iTRAQ and protein chip technology.Conclusions: The results of this study show that the incidence of Alzheimer’s disease may be related to the expression levels of Apolipoprotein A1,Calgranulin A,Calgranulin B,Plasma protease C1 inhibitor,Thrombospondin-1,Thrombospondin-1,changes in Ceruloplasmin and Fibrinogen gamma chain.These proteins may serve as potential biomarkers of Alzheimer’s disease.Simultaneously,Serum paraoxonase/arylesterase 1 is required to be further validated.This study provides grounds for the biomarkers discovery and requires further insights to declare them as biomarkers. |
