Background: Angiopoietin (Ang) -1 and -2 are glycoproteins that play roles in vascular development, angiogenesis, and lung vascular permeability. Although the serum concentrations of Ang-1 and -2 have been evaluated in patients with sepsis, those in patients with idiopathic pulmonary fibrosis (IPF) have received less attention.
Objective: To elucidate the clinical significance of Ang-1 and -2 in patients with IPF.
Methods: Seventy-five patients with IPF were retrospectively studied. Serum concentrations of Ang-1 and -2 at diagnosis of IPF were measured by enzyme-linked immunosorbent assay. The relationships of the Ang-1 and -2 concentrations with pulmonary function test results, high-resolution computed tomography findings, histologic findings, occurrence of acute exacerbation of IPF (AE-IPF), and prognosis were evaluated.
Results: The median patient age was 68 year-old and the median observation period was 44 months. IPF patients with high Ang-2 concentrations showed a significantly lower forced vital capacity (FVC) (2.28 vs. 2.69 L, respectively; p = 0.047) and lower percent diffusion lung capacity for carbon monoxide (%DLCO) (61.4 vs. 81.4%, respectively; p = 0.015) than patients with low Ang-2 concentrations. Serum Ang-2 concentrations were negatively correlated with %DLCO (r = -0.375, p = 0.021) and the change in %FVC in 12 months (r = -0.348, p = 0.043). The Ang-2 concentration was significantly higher in several patients with AE-IPF than in patients in stable condition (p = 0.011). Finally, patients with high Ang-2 concentrations showed a significantly worse prognosis than those with low Ang-2 concentrations (log-rank p = 0.039). Multivariate analysis showed that the serum Ang-2 concentration, but not the Ang-1 concentration, was a significant prognostic factor in patients with IPF (hazard ratio 1.439, p = 0.028).
Conclusion: Increases in the serum Ang-2 concentration were associated with disease progression and poor prognosis in patients with IPF.
Keywords: Angiogenesis; Angiopoietin; Idiopathic pulmonary fibrosis; Usual interstitial pneumonia.
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