Ogawa Yoko, Razzaque Mohammed S, Kameyama Kaori, Hasegawa Go, Shimmura Shigeto, Kawai Masataka, Okamoto Shinichiro, Ikeda Yasuo, Tsubota Kazuo, Kawakami Yutaka, Kuwana Masataka
Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan.
Invest Ophthalmol Vis Sci. 2007 Mar;48(3):1079-86. doi: 10.1167/iovs.06-0601.
Uncontrolled fibrosis due to excessive accumulation of extracellular matrix proteins in the lacrimal glands of patients with chronic graft-versus-host disease (cGVHD) is well documented. Heat-shock protein 47 (HSP47) is involved in the molecular maturation of collagen and has been shown to have a fibrogenic role in various fibrotic diseases. In this study, the role of HSP47 in the pathogenesis of lacrimal gland of patients with cGVHD was investigated.
The expression of HSP47, Ki67 (a proliferation marker), types I and III collagen, and alpha-smooth muscle actin (alpha-SMA) was examined in tissue sections and in primary cultures of fibroblasts obtained from the lacrimal glands of patients with cGVHD (n = 8) and Sjögren's syndrome (SS; n = 7).
Tissue sections of the lacrimal glands of patients with cGVHD showed markedly increased expression of HSP47 in fibroblasts around the medium-sized ducts than did those from patients with SS. The elevated expression of HSP47 in patients with cGVHD was mostly detected in Ki67-positive fibroblasts and was associated with increased accumulation of types I and III collagen in and around the fibrotic areas. Primary fibroblast cultures generated from cGVHD lacrimal gland showed higher HSP47 mRNA expression than did fibroblasts isolated from SS biopsy tissue, as determined by RT-PCR (P < 0.05). In contrast, alpha-SMA was higher in the SS than cGVHD fibroblasts at both mRNA and protein levels, and more lacrimal gland fibroblasts in the SS were positive for alpha-SMA than cGVHD (P < 0.01).
In cGVHD, increased expression of HSP47 may promote excessive collagen assembly in and around the periductal areas where fibroblasts are mostly in an active state. The less alpha-SMA in the cGVHD lacrimal gland fibroblasts suggests a relative lack of myofibroblastic transformation. It is likely that fibroblasts incapable of myofibroblastic transformation are the main source of HSP47 and collagen production, and the resultant effect is the periductal fibrotic changes seen in lacrimal glands of patients with cGVHD.
慢性移植物抗宿主病（cGVHD）患者泪腺中细胞外基质蛋白过度积累导致的失控性纤维化已有充分记录。热休克蛋白47（HSP47）参与胶原蛋白的分子成熟，并且已证实在各种纤维化疾病中具有促纤维化作用。在本研究中，调查了HSP47在cGVHD患者泪腺发病机制中的作用。
检测了cGVHD患者（n = 8）和干燥综合征（SS；n = 7）患者泪腺组织切片及原代培养成纤维细胞中HSP47、Ki67（一种增殖标志物）、I型和III型胶原蛋白以及α平滑肌肌动蛋白（α-SMA）的表达。
cGVHD患者泪腺组织切片显示，与SS患者相比，中导管周围成纤维细胞中HSP47的表达明显增加。cGVHD患者中HSP47的表达升高主要在Ki67阳性成纤维细胞中检测到，并且与纤维化区域内及周围I型和III型胶原蛋白的积累增加有关。通过逆转录聚合酶链反应（RT-PCR）测定，由cGVHD泪腺产生的原代成纤维细胞培养物显示出比从SS活检组织分离的成纤维细胞更高的HSP47 mRNA表达（P < 0.05）。相反，SS中的α-SMA在mRNA和蛋白质水平上均高于cGVHD成纤维细胞，并且SS中泪腺成纤维细胞α-SMA阳性的比cGVHD更多（P < 0.01）。
在cGVHD中，HSP47表达增加可能会促进导管周围区域内及周围的过度胶原蛋白组装，而成纤维细胞大多处于活跃状态。cGVHD泪腺成纤维细胞中较少的α-SMA表明肌成纤维细胞转化相对不足。无法进行肌成纤维细胞转化的成纤维细胞可能是HSP47和胶原蛋白产生的主要来源，其最终结果是cGVHD患者泪腺中出现导管周围纤维化改变。
