Department of Dermatology, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
PLoS One. 2012;7(2):e32272. doi: 10.1371/journal.pone.0032272. Epub 2012 Feb 23.
Cathepsin B (CTSB) is a proteolytic enzyme potentially modulating angiogenic processes and extracellular matrix remodeling. While matrix metalloproteinases are shown to be implicated in tissue fibrosis and vasculopathy associated with systemic sclerosis (SSc), the role of cathepsins in this disease has not been well studied. The aim of this study is to evaluate the roles of CTSB in SSc. Serum pro-CTSB levels were determined by enzyme-linked immunosorbent assay in 55 SSc patients and 19 normal controls. Since the deficiency of transcription factor Fli1 in endothelial cells is potentially associated with the development of SSc vasculopathy, cutaneous CTSB expression was evaluated by immunostaining in Fli1(+/-) and wild type mice as well as in SSc and control subjects. The effects of Fli1 gene silencing and transforming growth factor-β (TGF-β) on CTSB expression were determined by real-time PCR in human dermal microvascular endothelial cells (HDMECs) and dermal fibroblasts, respectively. Serum pro-CTSB levels were significantly higher in limited cutaneous SSc (lcSSc) and late-stage diffuse cutaneous SSc (dcSSc) patients than in healthy controls. In dcSSc, patients with increased serum pro-CTSB levels showed a significantly higher frequency of digital ulcers than those with normal levels. CTSB expression in dermal blood vessels was increased in Fli1(+/-) mice compared with wild type mice and in SSc patients compared with healthy controls. Consistently, Fli1 gene silencing increased CTSB expression in HDMECs. In cultured dermal fibroblasts from early dcSSc, CTSB expression was decreased compared with normal fibroblasts and significantly reversed by TGF-β1 antisense oligonucleotide. In conclusion, up-regulation of endothelial CTSB due to Fli1 deficiency may contribute to the development of SSc vasculopathy, especially digital ulcers, while reduced expression of CTSB in lesional dermal fibroblasts is likely to be associated with skin sclerosis in early dcSSc.
组织蛋白酶 B（CTSB）是一种潜在的调节血管生成过程和细胞外基质重塑的蛋白水解酶。虽然基质金属蛋白酶（matrix metalloproteinases）被认为与系统性硬化症（systemic sclerosis，SSc）相关的组织纤维化和血管病变有关，但在这种疾病中，组织蛋白酶的作用尚未得到很好的研究。本研究旨在评估 CTSB 在 SSc 中的作用。通过酶联免疫吸附试验（enzyme-linked immunosorbent assay）测定了 55 例 SSc 患者和 19 例正常对照者的血清前 CTSB 水平。由于内皮细胞转录因子 Fli1 的缺失可能与 SSc 血管病变的发展有关，因此通过免疫染色评估了 Fli1（+/-）和野生型小鼠以及 SSc 和对照者的皮肤 CTSB 表达。通过实时 PCR 分别在人真皮微血管内皮细胞（human dermal microvascular endothelial cells，HDMECs）和真皮成纤维细胞中测定了 Fli1 基因沉默和转化生长因子-β（transforming growth factor-β，TGF-β）对 CTSB 表达的影响。局限性皮肤型 SSc（limited cutaneous SSc，lcSSc）和晚期弥漫性皮肤型 SSc（diffuse cutaneous SSc，dcSSc）患者的血清前 CTSB 水平明显高于健康对照组。在 dcSSc 中，血清前 CTSB 水平升高的患者与正常水平的患者相比，出现手指溃疡的频率明显更高。与野生型小鼠相比，Fli1（+/-）小鼠的皮肤血管中 CTSB 表达增加，与健康对照组相比，SSc 患者的皮肤血管中 CTSB 表达也增加。同样，Fli1 基因沉默增加了 HDMECs 中的 CTSB 表达。与正常成纤维细胞相比，早期 dcSSc 的真皮成纤维细胞中 CTSB 表达减少，而 TGF-β1 反义寡核苷酸可显著逆转这一现象。总之，由于 Fli1 缺乏导致内皮细胞 CTSB 的上调可能有助于 SSc 血管病变的发展，特别是手指溃疡，而病变真皮成纤维细胞中 CTSB 的表达减少可能与早期 dcSSc 的皮肤硬化有关。
