J Korean Rheum Assoc.  2004 Dec;11(4):387-397.

Hypoxia Induces the Expression of Connective Tissue Growth Factor in Dermal Fibroblasts

• Hong KH
• Yoo SA
• Kang SS
• Shin YJ
• Kim WU
• Cho CS

Abstract

OBJECTIVE
Connective tissue growth factor (CTGF) has been proposed to play a role in fibrotic process of systemic sclerosis. Since hypoxia was known to be associated with fibrosis in several profibrogenic conditions, we investigated whether CTGF expression in dermal fibroblast is regulated by hypoxia caused by microvascular loss.
METHODS
Dermal fribroblasts from patient with systemic sclerosis and normal controls were cultured in the presence of cobalt chloride (CoCl2), a chemical inducer of HIF-1alpha or hypoxic culture conditions. Expression of HIF-1alpha, VEGF and CTGF was evaluated by semiquantitative reverse transcription-polymerase chain reaction and Western blotting.
RESULTS
Scleroderma fibroblasts expressed increased levels of HIF-1alpha, VEGF and CTGF compared to normal dermal fibroblasts. Dermal fibroblasts exposed to various concentration of CoCl2 (1~100microM) enhanced the expression of CTGF mRNA in dose-dependent fashion. Actinomycin D significantly blocked the hypoxia-mediated up-regulation of CTGF mRNA expression, whereas cycloheximide did not block the up-regulation. Up-regulation of CTGF by hypoxia was not mediated by endogenous production of transforming growth factor (TGF)-beta. In time-kinetics study, dermal fibroblasts from scleroderma patients exhibited earlier peak expression of CTGF mRNA than those from normal dermal fibroblasts. In addition, simultaneous treatment of suboptimal concentration of CoCl2 and TGF-beta exhibited the up-regulation of CTGF mRNA in additive fashion. Interferon-gamma did not modulate the expression of CTGF mRNA induced by CoCl2, while the up-regulation of CTGF by TGF-beta was downregulated by Interferon-gamma in a dose-dependent fashion.
CONCLUSION
These data indicate that hypoxia up-regulates the expression of CTGF in dermal fibroblasts and provide the evidence that hypoxia caused by microvascular alterations contributes the progression of fibrosis in systemic sclerosis by up-regulation of CTGF.

Keyword

Systemic sclerosis; Hypoxia; Connective tissue growth factor; Dermal fibroblast; Transforming gronth factor-beta

MeSH Terms

Anoxia*
Blotting, Western
Cobalt
Connective Tissue Growth Factor*
Connective Tissue*
Cycloheximide
Dactinomycin
Fibroblasts*
Fibrosis
Humans
Interferon-gamma
RNA, Messenger
Scleroderma, Systemic
Transforming Growth Factor beta
Transforming Growth Factors
Up-Regulation
Vascular Endothelial Growth Factor A
Cobalt
Connective Tissue Growth Factor
Cycloheximide
Dactinomycin
Interferon-gamma
RNA, Messenger
Transforming Growth Factor beta
Transforming Growth Factors
Vascular Endothelial Growth Factor A