尿激酶型纤溶酶原激活物受体 (uPAR) 基因失活诱导小鼠皮肤和肺纤维化及外周微血管病：硬皮病的新实验模型？

Inactivation of urokinase-type plasminogen activator receptor (uPAR) gene induces dermal and pulmonary fibrosis and peripheral microvasculopathy in mice: a new model of experimental scleroderma?

机构信息

Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, University of Florence, Florence, Italy.

Department of Experimental and Clinical Medicine, Section of Internal Medicine and Division of Rheumatology, Azienda Ospedaliero-Universitaria Careggi, University of Florence, Florence, Italy.

出版信息

Ann Rheum Dis. 2014 Sep;73(9):1700-9. doi: 10.1136/annrheumdis-2013-203706. Epub 2013 Jul 12.

DOI:10.1136/annrheumdis-2013-203706

PMID:23852693

Abstract

OBJECTIVE

Urokinase-type plasminogen activator receptor (uPAR) is a key component of the fibrinolytic system involved in extracellular matrix remodelling and angiogenesis. The cleavage/inactivation of uPAR is a crucial step in fibroblast-to-myofibroblast transition and has been implicated in systemic sclerosis (SSc) microvasculopathy. In the present study, we investigated whether uPAR gene inactivation in mice could result in tissue fibrosis and peripheral microvasculopathy resembling human SSc.

METHODS

The expression of the native full-length form of uPAR in human skin biopsies was determined by immunohistochemistry. Skin and lung sections from uPAR-deficient (uPAR(-/-)) and wild-type (uPAR(+/+)) mice at 12 and 24 weeks of age were stained with haematoxylin-eosin, Masson's trichrome and Picrosirius red. Dermal thickness and hydroxyproline content in skin and lungs were quantified. Dermal myofibroblast and microvessel counts were determined by immunohistochemistry for α-smooth muscle actin and CD31, respectively. Endothelial cell apoptosis was assessed by TUNEL/CD31 immunofluorescence assay.

RESULTS

Full-length uPAR expression was significantly downregulated in SSc dermis, especially in fibroblasts and endothelial cells. Dermal thickness, collagen content and myofibroblast counts were significantly greater in uPAR(-/-) than in uPAR(+/+) mice. In uPAR(-/-) mice, dermal fibrosis was paralleled by endothelial cell apoptosis and severe loss of microvessels. Lungs from uPAR(-/-) mice displayed non-specific interstitial pneumonia-like pathological features, both with inflammation and collagen deposition. Pulmonary pathology worsened significantly from 12 to 24 weeks, as shown by a significant increase in alveolar septal width and collagen content.

CONCLUSIONS

uPAR(-/-) mice are a new animal model closely mimicking the histopathological features of SSc. This model warrants future studies.

摘要

目的

尿激酶型纤溶酶原激活物受体（uPAR）是细胞外基质重塑和血管生成中纤溶系统的关键组成部分。uPAR 的裂解/失活是成纤维细胞向肌成纤维细胞转化的关键步骤，并与系统性硬化症（SSc）微血管病变有关。在本研究中，我们研究了 uPAR 基因敲除是否会导致类似于人类 SSc 的组织纤维化和外周微血管病变。

方法

通过免疫组织化学法确定人皮肤活检中天然全长形式 uPAR 的表达。12 周和 24 周龄 uPAR 缺陷（uPAR(-/-)）和野生型（uPAR(+/+)）小鼠的皮肤和肺组织切片用苏木精-伊红、马松三色和苦味酸红染色。皮肤和肺组织的真皮厚度和羟脯氨酸含量进行定量分析。通过α-平滑肌肌动蛋白和 CD31 的免疫组织化学法分别确定真皮肌成纤维细胞和微血管计数。通过 TUNEL/CD31 免疫荧光法评估内皮细胞凋亡。

结果

SSc 真皮中全长 uPAR 的表达显著下调，尤其是在成纤维细胞和内皮细胞中。uPAR(-/-)小鼠的真皮厚度、胶原含量和肌成纤维细胞计数明显高于 uPAR(+/+)小鼠。在 uPAR(-/-)小鼠中，真皮纤维化与内皮细胞凋亡和微血管严重丢失并存。uPAR(-/-)小鼠的肺显示出非特异性间质性肺炎样的病理特征，既有炎症又有胶原沉积。从 12 周到 24 周，肺泡间隔宽度和胶原含量显著增加，表明肺部病理学显著恶化。