Keloids are characterized by fibroblast activation and altered architecture of extracellular matrix (ECM). Excessive deposition of ECM molecules and irregular organization of collagen fibers have been observed in keloids. However, the ultrastructural alteration of collagen has not been fully investigated. In this study, the differences in tissue structure, collagen ultrastructure, matrix components, mechanical properties and collagen assembling molecules between keloids and their extra-lesional skins (ELSs) were explored using histology, transmission electron microscope (TEM), qPCR, Western blot, immunohistochemistry and bioinformatics. Histological evaluation showed thinner fibers in keloids with increased contents of collagen III and proteoglycans, which were supported by TEM findings of thinner collagen fibrils and less developed D-band periodicity in keloids than in ELSs (p < 0.05). In addition, total collagen and water contents were significantly increased (p < 0.05) along with richer proteoglycan production in keloids vs ELSs, which also led to increased stiffness and decreased maximal load in keloids compared with ELSs. Mechanism study showed that multiple molecules related to matrix assembly were significantly upregulated in keloids (p < 0.05). In particular, lumican and collagen V showed high degrees in co-expression analysis and their upregulation levels were revealed from microarray data, which were also verified in keloids at both gene and protein levels (p < 0.05). Nevertheless, siRNA knockdown of lumican failed to affect in vitro collagen assembly, but caused upregulated collagen V expression along with the upregulation of focal adhesion kinase, TGF-β1, TGF-β3 and PDGF, among which some are known for capable of enhancing collagen V expression. In conclusion, this study demonstrates impaired collagen assembly along with enhanced expression of lumican and collagen V, both are known for interfering with collagen fibril assembly.

瘢痕loid的特征在于成纤维细胞活化和细胞外基质（ECM）结构的改变。在瘢痕loid中已观察到ECM分子的过多沉积和胶原纤维的不规则组织。但是，胶原的超微结构改变尚未得到充分研究。在这项研究中，使用组织学，透射电子显微镜（TEM），qPCR，Western blot，研究了瘢痕loid及其病变外皮肤（ELS）之间的组织结构，胶原超微结构，基质成分，力学性能和胶原组装分子的差异，免疫组织化学和生物信息学。组织学评估显示，瘢痕loid中的纤维更细，胶原蛋白III和蛋白聚糖的含量增加，p  ＜0.05）。另外， 与ELSs相比，瘢痕loid中的胶原蛋白和水的总含量显着增加（p <0.05），并且蛋白聚糖的产生更丰富，这也导致瘢痕s的硬度增加和最大负荷降低。机理研究表明，瘢痕loid中与基质组装相关的多个分子显着上调（p  <0.05）。尤其是，卢米肯和胶原V在共表达分析中显示出很高的水平，并且从微阵列数据中揭示了它们的上调水平，这也在瘢痕loid中的基因和蛋白质水平上得到了证实（p  <0.05）。然而，lumican的siRNA敲低未能影响体外胶原组件，但具有粘着斑激酶的上调引起沿上调胶原V表达，TGF- β 1，TGF- β 3和PDGF，其中一些是为能够增强胶原V表达的公知的。总而言之，这项研究表明胶原蛋白组装受损，同时增强了lumican和V胶原蛋白的表达，两者均会干扰胶原纤维的组装。