Explore The Glycoproteins As Biomarkers For Intracranial Aneurysm Formation And Ruputure

Background:Subarachnoid hemorrhage (SAH) resulting from ruptured intracranial aneurysm (IA) is a devastating condition that presents a significant public risk through high rates of morbidity and mortality. Although the detail mechanisms underlying the initiation, progression and rupture of IA have not been completely elucidated, an accumualting body of evidence implicates that IA formation and progression appear to result from the hemodynamic stress, degeneration of mural cells, destruction of extracellular matrix and a mounting inflammatory response. At present, there are no cost-effective methods available that can be used to discover the early unruptured IA and predict the risk of rupture.Objectives:Screen the glycoproteins as biomarkers for IA formation and rupture in cerebrospinal fluid (CSF); Validate the biomarker candidates in the CSF used for proteomic screening as well as in an independent set of matched CSF and plasma samples; Evaluate the specificity and sensitivity of the biomarker candidates with statistical analysis; Discuss the potential roles of the biomarker candidates in the IA formation and rupture.Methods:A complementary proteomic approach which integrated lectin-affmity column for glycoprotein enrichment and a multiplex quantitative proteomic method, iTRAQ (isobaric Tagging for Relative and Absolute Protein Quantification), in conjunction with multidimensional chromatography, followed by high-throughput tandem mass spectrometry MALDI-TOF/TOF, was employed to simultaneously measure relative changes in the gylcoproteins of cerebrospinal fluid (CSF) obtained from patients with ruptured IA (RIA) and unruptured IA (UIA) compared to the healthy controls (HC) and disease controls (DC). One protein-receptor tyrosine kinase Axl with a unique change in RIA was validated in CSF used for proteomic screening as well as in an independent set of matched CSF and plasma samples by ELISA detection kit. The sensitivity at95%specificity of Axl in CSF and plasma was evaluated with receiver operating characteristic curve (ROC curve).Results:Firstly, A total of294glycoproteins were identified in human CSF with high evidence. Approximately half of these proteins had definite glycosylation sites with a variety of glycosylation types according to the protein database UniprotKB. Secondly, the proteomic findings showed the quantitative changes in RIA and UIA as compared to HC and DC. Among294identified CSF proteins,59,24and33of the proteins displayed quantitative changes unique to RIA, UIA or IA, respectively. At last, one of these unique proteins-receptor tyrosine kinase Axl which had a unique increase in RIA was confirmed in CSF and plasma by ELISA detection kit. ROC curve analysis results showed that the sensitivity at95%specificity of Axl in CSF to differentiate RIA from UIA was60%. As compared to CSF, the sensitivity at95%specificity of Axl in plasma to differentiate RIA from HC was40%and the sensitivity to differentiate RIA from UIA was25%.Conclusion:A potential glycoprotein biomarker-Axl was identified and confirmed in CSF as well as in plasma, which might be as a promising biomarker to predict the rupture of IA. The further investigation of the relations between Axl and IA formation and rupture might facilitate to reveal the pathogenesis of IA and discover the new therapeutic target.