REGULATORY MECHANISM FOR THE FORMATION OF TRIVALENT CROSS-LINK (HHL) OF TYPE I COLLAGENS IN ACQUIRED CONNECTIVE TISSUE DISEASES

获得性纤维硬化性疾病的病因尚不清楚，而该疾病的特征在于细胞外基质如胶原的过度积聚。先前的研究已经证明胶原的沉积和损伤活化的成纤维细胞产生更多的胶原。然而，胶原蛋白的质的变化还没有被研究。在这个项目中，我们已经集中在一个成熟的类型的三价交联，histidinohydroxyylysinonorleucine（HHL），在I型胶原和quuntified HHL使用一个敏感的HPLC系统，我们最近建立的。HHL为Ⅰ型胶原提供了稳定性和生理特性，在系统性硬化症和硬斑病患者的皮肤组织中，HHL与Ⅰ型胶原的摩尔比分别比正常人和病变周围正常皮肤显著增加，HHL在体内形成的调控机制尚不清楚。我们正在调查，以阐明控制HHL形成的因素，在体外三维培养系统补充L-抗坏血酸2-磷酸。该培养体系可为成纤维细胞提供与体内条件相似的最佳培养条件。初步的实验结果表明，低氧或低血清浓度并不影响赖氨酰氧化酶的活性，赖氨酰氧化酶是介导胶原分子反应位点形成的关键酶，HHL可能通过阻止胶原降解而参与纤维硬化性疾病的发生。

The etiology of acquired fibrosclerotic diseases remains unknown while the disease are characterized by excessive accumulation of extracellular matrices such as collagens. Previuous studies have demonstrated deposition of collagens and lesional activated fibroblasts produce more collagens. The qualitative changes of collagens, however, has not been investigated. In this project, we have focused on a mature type of trivalent cross-links, histidinohydroxylysinonorleucine (HHL), in type I collage and quntified HHL using a sensitive HPLC system that we have recently established. HHL provide type I collagens with stability and physiological properties.The molar ratio of HHL to type I collagen was significantly increased in the sclerotic skin samples from systemic sclerosis or morphea as compared with normal individuals or perilesional normal skin, respectively.The regulatory mechanism for the HHL formation in vivo is quite unknown. We are under investigation to elucidate factors that control the HHL formation using an in vitro three-dimensional culture system supplemented with L-ascorbic acid 2-phosphate. This culture system can provide fibroblasts with an optimal culture condition similar to in vivo condition. Preliminary experiments revealed that hypoxia or low serum concentration did not affect the activity of lysyl oxidase, a key enzyme that mediate the formation of reactive sites in collagen molecules.In conclusion, HHL may be involved in the development of fibrosclerotic diseases possibly by preventing collagens from degradation.