Zhang G-Y, Yi C-G, Li X, Ma B, Li Z-J, Chen X-L, Guo S-Z, Gao W-Y
Department of Hand and Plastic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Xueyuan West Road 109, Wenzhou 325027, Zhejiang Province, China.
Br J Dermatol. 2009 Apr;160(4):762-70. doi: 10.1111/j.1365-2133.2008.08989.x. Epub 2008 Dec 2.
Peroxisome proliferator-activated receptor (PPAR)-gamma agonists are increasingly used in patients with diabetes and some studies have suggested a beneficial effect on organ fibrosis. However their effects on dermal fibrosis in keloids are unknown.
To investigate the effect of the PPAR-gamma agonist troglitazone on transforming growth factor (TGF)-beta1-induced collagen type I expression in keloid fibroblasts.
Keloid fibroblasts were cultured and exposed to different concentrations of troglitazone in the presence of TGF-beta1. The mRNA expression of PPAR-gamma was determined by semiquantitative reverse transcriptase-polymerase chain reaction. The protein of PPAR-gamma, Smad2, Smad3, phoshpo-Smad2/3 and collagen type I was determined by Western blotting and collagen synthesis was evaluated by measuring (3)H-proline incorporation. The effect of troglitazone on cell viability was evaluated by the colorimetric conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide.
PPAR-gamma was expressed at a moderate level in keloid fibroblasts. Troglitazone depressed TGF-beta1-stimulated collagen type I expression and collagen synthesis in keloid fibroblasts in a concentration-dependent manner. Moreover, troglitazone inhibited expression and phosphorylation of TGF-beta1-induced Smad2/3. Cell viability was unaffected. These inhibitory effects of troglitazone were reversed by the PPAR-gamma-specific antagonist GW9662.
Our data suggest that PPAR-gamma is present in keloid fibroblasts and PPAR-gamma activation inhibits TGF-beta1-induced collagen type I expression at least in part by decreasing collagen synthesis. PPAR-gamma may be a promising therapeutic target for keloids.
过氧化物酶体增殖物激活受体（PPAR）-γ激动剂在糖尿病患者中应用日益广泛，一些研究提示其对器官纤维化有有益作用。然而，它们对瘢痕疙瘩皮肤纤维化的影响尚不清楚。
研究PPAR-γ激动剂曲格列酮对转化生长因子（TGF）-β1诱导的瘢痕疙瘩成纤维细胞中Ⅰ型胶原表达的影响。
培养瘢痕疙瘩成纤维细胞，并在TGF-β1存在的情况下使其暴露于不同浓度的曲格列酮。通过半定量逆转录-聚合酶链反应测定PPAR-γ的mRNA表达。通过蛋白质印迹法测定PPAR-γ、Smad2、Smad3、磷酸化Smad2/3和Ⅰ型胶原的蛋白质水平，并通过测量³H-脯氨酸掺入评估胶原合成。通过3-[4,5-二甲基噻唑-2-基]-2,5-二苯基四氮唑溴盐的比色转化评估曲格列酮对细胞活力的影响。
PPAR-γ在瘢痕疙瘩成纤维细胞中中等水平表达。曲格列酮以浓度依赖的方式抑制TGF-β1刺激的瘢痕疙瘩成纤维细胞中Ⅰ型胶原表达和胶原合成。此外，曲格列酮抑制TGF-β1诱导的Smad2/3的表达和磷酸化。细胞活力未受影响。曲格列酮的这些抑制作用被PPAR-γ特异性拮抗剂GW9662逆转。
我们的数据表明PPAR-γ存在于瘢痕疙瘩成纤维细胞中，PPAR-γ激活至少部分通过减少胶原合成来抑制TGF-β1诱导的Ⅰ型胶原表达。PPAR-γ可能是瘢痕疙瘩有前景的治疗靶点。
