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，而这种疾病的特点是细胞外基质如胶原的过度积累。先前的研究表明胶原沉积和病变激活的成纤维细胞产生更多的胶原。然而，胶原质的变化尚未被研究。在这个项目中，我们专注于I型拼贴中的一种成熟类型的三价交联，组氨酸二羟基赖氨酸氨基亮氨酸（HHL），并使用我们最近建立的敏感HPLC系统对HHL进行定量。HHL为I型胶原提供了稳定性和生理特性。与正常个体或病灶周围的正常皮肤相比，系统性硬化症或morphea的硬化皮肤样本中HHL与I型胶原的摩尔比分别显著增加。体内HHL形成的调控机制尚不清楚。我们正在研究阐明控制HHL形成的因素，使用补充l -抗坏血酸2-磷酸的体外三维培养系统。该培养体系可为成纤维细胞提供类似于体内条件的最佳培养条件。初步实验显示，缺氧或低血清浓度不影响赖氨酸氧化酶的活性，赖氨酸氧化酶是介导胶原分子活性位点形成的关键酶。总之，HHL可能通过阻止胶原降解参与了纤维硬化性疾病的发展。

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.