Differential Expression of Vascular Endothelial Growth Factor-A165 Isoforms Between Intracranial Atherosclerosis and Moyamoya Disease

Abstract

Background: Vascular endothelial growth factor-A₁₆₅ (VEGF-A₁₆₅) has been identified as a combination of 2 alternative splice variants: proangiogenic VEGF-A₁₆₅a and antiangiogenic VEGF-A₁₆₅b. Intracranial atherosclerotic disease (ICAD) and moyamoya disease (MMD) are 2 main types of intracranial arterial steno-occlusive disorders with distinct capacities for collateral formation. Recent studies indicate that VEGF-A₁₆₅ regulates collateral growth in ischemia. Therefore, we investigated if there is a distinctive composition of VEGF-A₁₆₅ isoforms in ICAD and MMD.

Methods: Sixty-six ICAD patients, 6 MMD patients, and 5 controls were enrolled in this prospective study. ICAD and MMD patients received intensive medical management upon enrollment. Surgery was offered to 9 ICAD patients who had recurrent ischemic events, 6 MMD patients, and 5 surgical controls without ICAD. VEGF-A₁₆₅a and VEGF-A₁₆₅b plasma levels were measured at baseline, within 1 week after patients having surgery, and at 1, 3, and 6 months after treatment.

Results: A significantly higher baseline VEGF-A₁₆₅a/b ratio was observed in MMD compared to ICAD (P = .016). The VEGF-A₁₆₅a/b ratio increased significantly and rapidly after surgical treatment in ICAD (P = .026) more so than in MMD and surgical controls. In patients with ICAD receiving intensive medical management, there was also an elevation of the VEGF-A₁₆₅a/b ratio, but at a slower rate, reaching the peak at 3 months after initiation of treatment (baseline versus 3 months VEGF-A₁₆₅a/b ratio, P = .028).

Conclusions: Our study shows an increased VEGF-A₁₆₅a/b ratio in MMD compared to ICAD, and suggests that both intensive medical management and surgical revascularization elevate the VEGF-A₁₆₅a/b ratio in ICAD patients.

Keywords: VEGF-A(165)–isoforms–intracranial atherosclerosis–moyamoya disease.

Figure 1.

Flow diagram demonstrating the numbers of patients (N) and samples (n) in each group and time point, as well as the attrition quantities with their reasons at each step. In the surgical patients, only 2 samples were lost due to sample hemolysis at 6-month follow up. An inter-duplicate variance of ELISA measurements ≥20% was defined as invalid measurement and the data was excluded.

Figure 2.

Comparison of baseline VEGF-A₁₆₅ (A), VEGF-A₁₆₅a (B), and VEGF-A₁₆₅b (C) levels in ICAD, MMD, and controls. The box plots graph shows that MMD patients have a significantly higher level of VEGF-A₁₆₅a compared to controls (p=0.026) and a significantly lower level of VEGF-A₁₆₅b compared to ICAD (p=0.0006) and controls (p=0.0070). The total levels of VEGF-A₁₆₅ were not different between the three groups (p=0.31). The highest levels of VEGF-A₁₆₅a were observed in MMD, while the highest levels of VEGF-A₁₆₅b were seen in ICAD. VEGF, vascular endothelial growth factor; ICAD, intracranial atherosclerotic disease; MMD, moyamoya disease; *, p<0.05; **, p<0.01; ***, p<0.001.

Figure 3.

Elevation of VEGF-A₁₆₅a/b ratio within one week after surgery according to etiology. The bar graph shows that the VEGF-A₁₆₅a/b ratio elevated in all the groups, but only in ICAD was the increase significant (p=0.026). VEGF, vascular endothelial growth factor; ICAD, intracranial atherosclerotic disease; MMD, moyamoya disease; *, p<0.05.

Figure 4.

Box plots of VEGF-A₁₆₅a (A), VEGF-A₁₆₅b (B), and VEGF-A₁₆₅a/b ratio (C) at different time points after surgical revascularization (in red) and medical treatment (in blue) in ICAD patients. The upper halves of panel A, B, and C show the surgical effects on the variations of VEGF-A₁₆₅a, VEGF-A₁₆₅b, and the VEGF-A₁₆₅a/b ratio, respectively. Surgery significantly increased the VEGF-A₁₆₅a/b ratio within one week after surgery (p=0.026), with the ratio gradually declining to the lowest value at six months. Additionally, the VEGF-A₁₆₅b level within one week was significantly lower than at baseline (p=0.047). The lower halves of panel A, B, and C illustrate the medical effect on the VEGF-A₁₆₅a level, the VEGF-A₁₆₅b level, and the VEGF-A₁₆₅a/b ratio, respectively. The VEGF-A₁₆₅a/b ratio progressively increased and reached its peak after three months during intensive medical management (p=0.028). A significant difference between baseline and three months was also found in the VEGF-A₁₆₅a level (p=0.015). VEGF-A₁₆₅b levels did not change during follow-up (p=0.38). VEGF, vascular endothelial growth factor; ICAD, intracranial atherosclerotic disease; *, p<0.05; **, p<0.01.