Down-regulation of collagen and connective tissue growth factor expression with hepatocyte growth factor in lung fibroblasts from white scleroderma patients via two signaling pathways

作者：Bogatkevich Galina S^*; Ludwicka Bradley Anna; Highland Kristin B; Hant Faye; Nietert Paul J; Singleton C Beth; Silver Richard M

来源：Arthritis and Rheumatism, 2007, 56(10): 3468-3477.

DOI：10.1002/art.22874

Objective. To study the mechanisms by which hepatocyte growth factor (HGF) down-regulates collagen and connective tissue growth factor (CTGF) in scleroderma (systemic sclerosis [SSc]) lung fibroblasts.
Methods. CTGF, type I collagen, and I kappa B alpha expression, together with MAPK phosphorylation, were studied by immunoblotting of lung fibroblasts derived from white SSc patients. Matrix metalloproteinase I (MMP-1) expression in cell culture medium samples was measured by enzyme-linked immunosorbent assay, MMP-1 activity was studied using an MMP-1 assay, and NF-kappa B DNA binding activity was determined using a transcription factor assay.
Results. In lung fibroblasts from white SSc patients, HGF activated MAPK (ERK-1/2) signaling pathways and MMP-1, while it inhibited NF-kappa B and significantly down-regulated CTGF and collagen in a time-and dose-dependent manner. Small interfering RNA (siRNA)-mediated depletion of Grb2 expression disrupted c-Met receptor downstream signaling, which resulted in diminished HGF-induced ERK-1/2 phosphorylation and the recovery of HGF-inhibited expression of MMP-1, NF-kappa B, collagen, and CTGF. The MAPK inhibitor, U0126, blocked MMP-1 activity and restored HGF-inhibited collagen and CTGF accumulation. Inhibition of MMP activity by MMP inhibitor GM1489 and inhibition of MMP-1 expression by siRNA did not prevent HGF-induced ERK-1/2 phosphorylation and NF-kappa B activity, but significantly restored HGF-inhibited collagen and CTGF accumulation. NF-kappa B inhibitor BAY 11-7082 did not interfere with MAPK phosphorylation or MMP-1 expression and activation, but significantly inhibited NF-kappa B DNA binding activity and acted synergistically with HGF to completely diminish the expression of CTGF.
Conclusion. In lung fibroblasts from white SSc patients, HGF down-regulates the accumulation of CTGF via MAPK/MMP-1 and NF-kappa B signaling pathways, whereas collagen down-regulation is mediated mainly by a MAPK/MMP-1-dependent pathway.

• 出版日期2007-10