The role of collagen in bone strength 胶原对骨硬度所扮演的角色

Abstract

Bone is a complex tissue of which the principal function is to resist mechanical forces and fractures. Bone strength depends not only on the quantity of bone tissue but also on the quality, which is characterized by the geometry and the shape of bones, the microarchitecture of the trabecular bones, the turnover, the mineral, and the collagen. Different determinants of bone quality are interrelated, especially the mineral and collagen, and analysis of their specific roles in bone strength is difficult. This review describes the interactions of type I collagen with the mineral and the contribution of the orientations of the collagen fibers when the bone is submitted to mechanical forces. Different processes of maturation of collagen occur in bone, which can result either from enzymatic or nonenzymatic processes. The enzymatic process involves activation of lysyl oxidase, which leads to the formation of immature and mature crosslinks that stabilize the collagen fibrils. Two type of nonenzymatic process are described in type I collagen: the formation of advanced glycation end products due to the accumulation of reducible sugars in bone tissue, and the process of racemization and isomerization in the telopeptide of the collagen. These modifications of collagen are age-related and may impair the mechanical properties of bone. To illustrate the role of the crosslinking process of collagen in bone strength, clinical disorders associated with bone collagen abnormalities and bone fragility, such as osteogenesis imperfecta and osteoporosis, are described.

摘要

骨是一个复杂的组织，其主要功能是抵制外力和骨折。 骨强度不仅取决于骨组织的数量，而且质量，这是由几何形状和骨骼的特点，对骨小梁，矿物质，以及胶原蛋白的微架构。 骨质量的不同决定因素是相互关联的，尤其是矿物质和胶原蛋白，骨强度和其具体的作用分析是困难的。 本文介绍的矿物质和第一型胶原蛋白纤维的骨头时提交的机械力方向贡献胶原的相互作用。 胶原蛋白成熟的过程发生在不同骨，这可能会导致酶或从非酶过程之一。 酶的过程涉及赖氨酰氧化酶，从而导致交联未成熟和成熟稳定的胶原纤维的形成激活。 两种类型的非酶过程中介绍了I型胶原：采用先进的糖化终产物由于在骨组织还原糖积累，以及消旋和异构化的过程中形成的胶原端肽。 胶原蛋白的这些修改是与年龄有关，并可能损害骨骼的力学性能。 为了说明在骨胶原交联过程中的作用强度，骨胶原和骨异常脆弱，如成骨不全症，骨质疏松症相关的临床疾病，进行了描述。