Effect Of Conective Tissue Growth Factor On Hypoxic Pulmonary Hypertension

Objective To evaluate the role of conective tissue growth factor (CTGF) in the pathogenesis of hypoxic pulmonary hypertension, we observed the change of lung tissue CTGF level of rats with hypoxia-induced pulmonary hypertension, investigated the role of hypoxia in the synthesis and secretion of CTGF in cultured human umbilical vein endothelial cells (UVECs).Methods (1) Twenty male SD rats were randomly divided into control group and hypoxic group. Mean pulmonary arterial pressure (mPAP) was measured by a right cardiac catheterization. The right ventricle (RV) and left ventricle plus septum (LV+S) of rat were weighed respectively, and the RV/(LV+S) was calculated. The index of wall thickness of pulmonary arterioles which are the percentage of vascular wall thickness/vascular external diameter (WT%) and the percentage of vascular wall area/total vascular area (WA%) was measured by a computerized image analyzer. CTGF mRNA and protein expression in pulmonary arterioles were observed in situ hybridization and immunohistochemistry. CTGF mRNA expression in lung tissue was observed by real-time reverse transcriptase-polymerase chain reaction. (2) Cultured human umbilical vein endothelial cells (UVECs) were treated with hypoxia (oxygen concentration is 3%). Real-time reverse transcriptase-polymerase chain reaction was adopted to measure CTGF mRNA in UVESCs. Enzyme-linked immunosorbent assay was adopted to measure CTGF concentrations in supernatant fluid of UVECs.Results (1) Compared with control rats, the mPAP of rats had been markedly elevated after hypoxia (P<0.01), as well as WT%,WA% of pulmonary arterioles and RV/(LV+S) (P<0.01). In rats exposed to hypoxia, the expression of CTGF mRNA in lung tissue and pulmonary arterioles was significantly up-regulated, the CTGF protein level in pulmonary arterioles was also increased (P<0.01), as compared with control rats. Linear correlation analysis showed that lung tissue CTGF mRNA and protein level in pulmonary arterioles, and CTGF mRNA level in lung tissue were significantly associated with WT% and WA% (P<0.01). (2) Compared with control group, there was no change of CTGF mRNA in UVESCs after treated with hypoxia for 6 hours (P>0.05), which were increased after treated with hypoxia for 12 hours (P<0.05), and became more significant after 24 hours (P<0.01). But the CTGF concentrations in supernatant fluid of UVECs after treated with hypoxia for 6 hours was increased as compared with the control groups (P<0.05), and get more significant after 12 hours (P<0.01). There was no further increase for 24 hours treated with hypoxia (P>0.05).Conclusions (1) Chronic hypoxia stimulates synthesis and release of CTGF. CTGF plays an important role in regulating the pulmonary vascular remodeling. (2) Hypoxia up-regulates CTGF gene transcription, increases the production and release of CTGF in cultured human umbilical vein endothelial cells (UVECs).