[Connective tissue growth factor synergistically with transforming growth factor beta 1 to promote renal fibrosis].

OBJECTIVE: To investigate the influence of CTGF and TGF-beta(1) on the synthesis and secretion of matrix metalloproteinase-2 (MMP-2) and myofibrotic activation in renal fibroblasts.

METHODS: Equal numbers of renal fibroblasts (NRK-49F) were planted and divided into vechile, CTGF treated alone, TGF-beta(1) treated alone, and CTGF plus TGF-beta(1) treated groups. Gelatin zymography and Western-blot analysis were used for assay of the MMP-2 activity and protein level in the supernatant cultured medium, respectively. The levels of MMP-2 mRNA were assessed by real time-PCR. Western-blot analysis was carried out to measure the expression of alpha-smooth muscle actin (alpha-SMA), a maker protein of myofibroblast in cells, and the levels of extracellular matrix (ECM) component Fibronectin in supernantant medium.

RESULTS: The activity and protein level of MMP-2 were no significant difference between the groups when cells were stimulated for 24 hours. While cells were stimulated for 48 hours, 100 ng/ml CTGF and 5 ng/ml TGF- beta(1) induce a increase in MMP-2 activity and protein levels compared with vechile, respectively (P < 0.05); different dose of CTGF plus TGF-beta(1) had the tendency to suppress MMP-2 activity and protein level, and a significant decrease was seen in 50 ng/ml CTGF plus 5 ng/ml TGF-beta(1) group, 100 ng/ml CTGF plus 5 ng/ml TGF-beta(1) group compared with CTGF group and TGF-beta(1) group, respectively (P < 0.05). When cells were stimulated for 12 hours, the levels of MMP-2 mRNA were increased significantly in 100 ng/ml CTGF group and 5 ng/ml TGF-beta(1) group compared with vechile respectively beta(1.72), 1.68 vs 1.29, (P < 0.01), decreased significantly in CTGF plus TGF-beta(1) group compared with CTGF group and TGF-beta(1) group, respectively (0.67 vs 1.72, 1.68, P < 0.01). 100 ng/ml CTGF had no prominent effect on the expression of alpha-SMA in cells and FN in supernatant medium (P > 0.05), whereas 5 ng/ml TGF-beta(1) significantly stimulated both the expression of alpha-SMA and FN (P < 0.05), and CTGF plus TGF-beta(1) induced more alpha-SMA and FN compared with TGF-beta(1) (P < 0.05).

CONCLUSION: CTGF synergistically with TGF-beta(1) to induce the formation of myofibroblasts and down-regulate the production of MMP-2 in renal fibroblast.