Proteomics-based Analysis Of Differentially Expressed Proteins In The Sera Of Human Small Abdominal Aortic Aneurysm

ObjectiveAbdominal aortic aneurysm (AAA) a complex multifactorial disease. Early detectionand repair of AAA may reduced the high mortality rates associated with rupture. Ourobjective was to uncover proteins that are significantly changed in sera of small or largeAAA patients compared to sera of patients with peripheral atherosclerosis and those ofhealthy people, and to explore the relationship between the differently-expressedproteins and AAA. We hope this Preliminary study may provide some importantbiological clues and direction to search the biomarker of AAA.MethodThe study population consisted of6small AAA (aortic size <55mm),6large patients(aortic size>55mm) and6peripheral atherosclerosis pathents and6healthy controls(aortic size <30mm). Fasting serum samples were collected. After the depletion of thehigh-abundance serum proteins using Aurum serum protein mini kit, two-dimensionalgel electrophoresis was performed to separate serum proteins. The gels were analyzedusing Imagemaster5.0software to measure the normalized intensity volume(%Vol)value, and the%Vol value of each protein spot from individual gel was comparedwhithin four groups using statistical analysis. The differently-expressed protein spotswere selected and manually excised from gels and submitted to trypsin proteolysis. Thecollected peptide mixture was analyzed using MALDI-TOF mass spectrometry to obtainmass data. Protein identification by peptide mass fingerprint was performed using the Mascot search engine in NCBInr database.ResultsThe four groups did not differ significantly at base line, except for a small difference inthe serum cholesterol level. Five protein spots had significantly different expressionamong four groups,4of which showed an up-regulation in AAA patients while theexpression level of1protein spot was reduced. Nine differently-expressed proteins wereidentified successfully by peptide mass fingerprint as follows: glial fibrillary acidicprotein isoform1(GFAP-1), transferrin, transforming acidic coiled-coil containingprotein1(TACC1), haptoglobin precursor, haptoglobin-related protein,α-1-microglobulin, dermcidin preproprotein, glia maturation factor gamma(GMFG),and prealbumin. The normalized intensity volume (expressed by%Vol*100%) value ofserum GFAP-1in healthy controls (1.94±0.72）were higher than that in PAD group(1.29±0.37) and large-AAA group (1.06±0.38)(P<0.05). The normalized intensityvolume value of serum TACC1(4.34±2.64) protein in large-AAA group weresignificantly increased compared with those in healthy control (1.43±1.80), in PADgroup (0.89±1.13), and in small-AAA group (1.62±1.61)(P<0.05). The normalizedintensity volume value of serum haptoglobin precursor and haptoglobin-related proteinin small-AAA group (4.39±1.24) were up-regulated compared with those in healthycontrol (2.32±0.60), in PAD group (2.78±0.97), and in large-AAA group (3.06±1.22)(P<0.05). The normalized intensity volume value of serum GMFG in small-AAA group(2.95±0.32) were higher than those in healthy control (1.88±0.23) and in PAD group(2.02±0.30)(P<0.05), while that in large-AAA group (2.65±1.09) higher than that inhealthy control (1.88±0.23)(P<0.05).ConclusionFour differently-expressed proteins, including GFAP-1, TACC1protein, haptoglobinprecursor, haptoglobin-related protein and GMFG may serve as the potentical cadidatedbiomarker protein of AAA. The proteomics approach may offer some important information regarding the search of biomarker of AAA. Future validation of thesepotential biomarker candidates is needed to facilitate diagnosis and treatment of patientswith small-AAA.