OBJECTIVETo investigate the role of connective tissue growth factor (CTGF) in pulmonary fibrosis in rats with hyperoxia-induced chronic lung disease (CLD).

METHODSEighty premature rats were randomly exposed to hyperxia (FiO2=0.90) or room air (control group) (n=40 each). CLD was induced by hyperoxia exposure. The expression of CTGF mRNA and transforming growth factor-beta 1 (TGF-beta 1), the levels of type I collagen and the proliferating cell nuclear antigen (PCNA) index were assayed with enzyme linked immunoadsorbent (ELISA), immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) on days 1, 3, 7, 14 and 21 after exposure.

RESULTSThere were no differences in the levels of type I collagen, PCNA index, TGF-beta 1 protein and CTGF mRNA between the CLD and the control groups within 3 days after exposure. In the CLD group, the expression of TGF-beta 1 protein increased on the 7th day, remained at a higher level on the 14th and 21st day after exposure; the higher levels of type I collagen, PCNA index and CTGF mRNA were detected on the 14th day and peaked on the 21st day after exposure when comparing the control group. CTGF mRNA expression was positively correlated with type I collagen levels in the CLD group (gamma=0.89, P < 0.01).

CONCLUSIONSThe expression of CTGF in lung tissues is associated with pulmonary fibrosis in CLD rats.