Objective: To explore the effect of plasminogen activator inhibitor-1 (PAI-1) on the proliferation and conversion of rat embryonic lung fibroblasts and the synthesis of collagen, and therefore to explore the function of PAI-1 in pulmonary fibrosis.
Methods: The embryonic lung fibroblasts from pregnant Wistar rats were isolated and cultured in vitro. The reproduction rate of fibroblasts at 12 h, 24 h, and 48 h after being stimulated by PAI-1 with different concentrations (5, 10, 20, 40, 80, and 100 µg/L) was measured by MTT assay. After being stimulated by PAI-1 with the most suitable concentration (20 µg/L) for 48 h and 72 h, the expression of proliferating cell nuclear antigen (PCNA) was measured by immunocytochemical technique, and the mRNA expression of α-SMA and type-1 collagen at 24 h and 48 h was measured by real-time PCR.
Results: PAI-1 with different concentrations stimulated the proliferation of fibroblasts. The highest proliferation rate and absorbance in concentration of 20 µg/L and at 12 h were 62.6% and 0.573 ± 0.039. The comparison of different concentrations showed that the difference was significant (F = 111.112, P = 0.000). Therefore, 20 µg/L was selected as the most suitable concentration. Using immunocytochemical method, the optical density of PCNA at 48 h and 72 h were 3685 ± 686 and 2530 ± 477 after being stimulated with 20 µg/L PAI-1. The comparison showed significant difference (F = 7.85, P = 0.02). The expression of α-SMA increased (230 ± 11)% and (159 ± 9)% at 24 h and 48 h after being stimulated with 20 µg/L PAI-1, and the difference was significant (F = 39.92, P = 0.0003). The expression of type-1 collagen increased (92 ± 8)% and (65 ± 12)%, the difference being significant (F = 32.61, P = 0.0006).
Conclusion: PAI-1 can promote the proliferation and conversion of fibroblasts and the synthesis of collagen, which may be involved in the pathogenesis of pulmonary interstitial fibrosis.