Assessment of plasma soluble Tie-2 level to distinguish moyamoya disease from atherosclerotic cerebrovascular disease and predict postoperative neovascularization

OBJECTIVE Moyamoya disease (MMD) is a chronic steno-occlusive cerebrovascular disease and features the formation of hazy collateral vessels at the base of the brain. Angiopoietin (Ang)–1 and -2, their receptor Tie-2, and vascular endothelial growth factor (VEGF) that regulate angiogenesis might be important in MMD pathophysiology and postoperative collateral formation. The goal of this study was to determine whether levels of these angiogenic factors could predict collateralization in patients with MMD. METHODS A total of 196 patients with MMD and 57 with atherosclerotic cerebrovascular disease serving as controls were enrolled. Ang-1, Ang-2, Tie-2, and VEGF mRNA levels were analyzed in middle cerebral artery (MCA) arterial wall specimens by using real-time quantitative polymerase chain reaction. MCA and peripheral plasma concentrations of Ang-1, Ang-2, soluble Tie-2 (sTie-2), and VEGF were examined by enzyme-linked immunosorbent assay. Cerebral arteriography was performed 6 months after bypass surgery to assess the postoperative collateralization. RESULTS In MCA specimens, patients with MMD exhibited higher expression levels of Ang-1 and Ang-2 but lowered VEGF expression. The patients with MMD had significantly higher concentrations of Ang-1 and Ang-2 but lower levels of VEGF in MCA plasma. Peripheral plasma concentrations of these growth factors were not changed. MCA and peripheral plasma sTie-2 levels were both reduced in patients with MMD. The 6-month follow-up showed that patients with good collateral formation had lower sTie-2 levels in both MCA and peripheral plasma. Furthermore, the Suzuki stage and peripheral plasma sTie-2 level were significantly correlated with good postoperative collateral formation on multivariate analysis. CONCLUSIONS Ang-1, Ang-2, Tie-2, and VEGF are involved in MMD pathogenesis. The peripheral plasma level of sTie-2 can differentiate MMD from atherosclerotic cerebrovascular disease and serve as a novel biomarker to predict postoperative collateral formation.