Proteomics Analysis of Blood Serums from Alzheimer’s Disease Patients Using iTRAQ Labeling Technology

Abstract

Alzheimer' disease (AD) is the most common form of dementia affecting up to 6% of the population over the age of 65. In order to discover differentially expressed proteins that might serve as potential biomarkers, the serums from AD patients and healthy controls were compared and analyzed using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ). For the first time, AD biomarkers in serums are investigated in the Han Chinese population using iTRAQ labeled proteomics strategy. Twenty-two differentially expressed proteins were identified and out of which nine proteins were further validated with more sample test. Another three proteins that have been reported in the literature to be potentially associated with AD were also investigated for alteration in expression level. Functions of those proteins were mainly related to the following processes: amyloid-β (Aβ) metabolism, cholesterol transport, complement and coagulation cascades, immune response, inflammation, hemostasis, hyaluronan metabolism, and oxidative stress. These results support current views on the molecular mechanism of AD. For the first time, differential expression of zinc-alpha-2-glycoprotein (AZGP1), fibulin-1 (FBLN1), platelet basic protein (PPBP), thrombospondin-1 (THBS1), S100 calcium-binding protein A8 (S100A8), and S100 calcium-binding protein A9 (S100A9) were detected in the serums of AD patients compared with healthy controls. These proteins might play a role in AD pathophysiology and serve as potential biomarkers for AD diagnosis. Specifically, our results strengthened the crucial role of Aβ metabolism and blood coagulation in AD pathogenesis and proteins related to these two processes may be used as peripheral blood biomarkers for AD.

iTRAQ‐Based Proteomic Analysis Reveals Protein Profile in Plasma from Children with Autism

“…The iTRAQ analysis was performed according to the previous study . Plasma proteins (100 μg) were reduced, alkylated, and digested with trypsin (Promega, Madison, WI, USA) at a ratio of 1:30 at 37 °C for overnight, and then labeled with the iTRAQ reagents (AB Sciex, Foster City, CA, USA).…”

“…The dried samples were reconstituted in 100 μL double‐distilled water and injected into the Agilent HPLC (HPLC; Agilent Technologies, Santa Clara, CA, USA) with a high pH RP column (Durashell, C18, 250 mm × 4.6 mm, 5 μm; Bonna‐Agela Technologies, Inc., Wilmington, DE, USA). Peptides were eluted and combined into 10 groups and lyophilized and stored at −80 °C …”

“…An Ultra 2D Plus nanoflow HPLC (Eksigent, Inc., Dublin, CA, USA) coupled with Triple TOF 5600 system (AB Sciex) was used for analytical separation of peptides . Microfluidic traps and nanofluidic columns packed with ChromXP C18 (3 μm, 2.1 × 100 mm, Eksigent) were utilized for online trapping and desalting, while nanofluidic columns packed with ChromXP C18 (3 μm × 150 cm, Eksigent) were employed in analytical separation.…”

Quantitative Proteomic Profiling of Cerebrospinal Fluid to Identify Candidate Biomarkers for Alzheimer's Disease

“…Several groups have used proteomics approaches to discover biomarkers for AD [4–6]. Russell et al combined tissue and fluid proteomics with tandem mass tags (TMT) for detection of low-abundance peptides in biological fluids [7].…”

Regulation of Cellular Redox Signaling by Matricellular Proteins in Vascular Biology, Immunology, and Cancer

“…Curiously, treatment of astrocytes with resveratrol alone significantly increased TSP1 mRNA levels (29), whereas others have found that b-amyloid inhibits TSP1 release from astrocytes (200). These findings may be relevant to the accumulating evidence linking the neurodegenerative condition, Alzheimer's disease and TSP1 (19,200,232). Further studies employing exogenous ROS and gene silencing of ROS enzymatic sources would be useful to evaluate possible ROS-stimulated feed-forward induction of TSP1.…”