Clinical Significance of Increased VEGF, TGF-β1, and YKL-40, a Chitinase like Protein, in Serum of the Children with Asthma

Background: Vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β₁, and platelet derived growth factor (PDGF) are known to be involved in the pathogenesis of inflammation and remodeling in asthmatic airways. YKL-40, a chitinase-like protein, and clusterin have been reported to be biomarkers for severe asthma. We examined serum levels of growth factors, YKL-40 and clusterin in children with acute asthma or stable asthma and investigated their correlation with clinical findings and lung function parameters.

Methods: Forty-one children (≥6yrs of age) with asthma were enrolled and 2 groups were defined: 23 patients admitted with asthma exacerbation and 18 patients with stable asthma. Serum levels of VEGF, TGF-β_1, PDGF-BB, YKL-40, and clusterin were measured using ELISA, and assessed in relation to the clinical and spirometric parameters. Fifteen age-matched controls were also studied.

Results: VEGF, TGF-β_1, and YKL-40 levels in children with acute asthma were significantly elevated compared to controls. VEGF and YKL-40 levels in stable asthma group were higher than in controls and not different from those in acute asthma group. VEGF levels in acute asthma group correlated significantly with asthma severity. TGF-β₁ levels in stable asthma group showed a significant inverse correlation with FEV₁% and FEF_25-75%. YKL-40 had no relationship with clinical and spirometric parameters.

Conclusions: Our study suggests that increased VEGF and YKL-40 might affect asthmatic airways not only during acute exacerbation but also in stable state. It also suggests that serum TGF-β₁ might be a biomarker for airway obstruction in children with asthma.