Gulati A K, Reddi A H, Zalewski A A
Anat Rec. 1984 May;209(1):21-7. doi: 10.1002/ar.1092090104.
Extracellular matrix is known to play an important role during development and maintenance of various tissues. In the present study, changes in two extracellular matrix glycoproteins, fibronectin and laminin, were investigated in skeletal muscle undergoing immune rejection. Purified antibodies against fibronectin and laminin were used to analyze the matrix by indirect immunofluorescence at various intervals after transplantation of extensor digitorum longus muscle in rats. Fibronectin and laminin were localized in the pericellular basement membrane zone of the normal myofibers; however, the cytoplasm was devoid of both glycoproteins. Transplanted muscle grafts underwent a process of degeneration and then an initial regeneration during the first 7 days. This regeneration effort ceased with the onset of muscle rejection in 14-day transplants. At this time, fibronectin was seen in the cytoplasmic region as well as the extracellular matrix of myofibers and myotubes. At later time intervals, an increased intensity of staining for fibronectin was seen throughout the rejected muscle. In muscle grafts undergoing regeneration but not rejection (i.e., nonantigenic grafts), such an increase in the presence of fibronectin was not seen ( Gulati et al., 1982). The distribution of laminin did not change during the rejection process and was localized in the basement membrane zone of myofibers and myotubes, although the overall configuration of the basement membranes was deformed and collapsed. It appears that the basement membranes are resistant to degradation, and staining for laminin persists in rejected muscle. These results show marked changes in the extracellular matrix of muscle undergoing rejection. The appearance of fibronectin during the initial stages of muscle rejection may have a causal relationship to the process of immune defence mechanism; however, the exact role of fibronectin remains elusive.
细胞外基质在各种组织的发育和维持过程中发挥着重要作用。在本研究中，对经历免疫排斥的骨骼肌中两种细胞外基质糖蛋白——纤连蛋白和层粘连蛋白的变化进行了研究。在大鼠趾长伸肌移植后的不同时间间隔，使用针对纤连蛋白和层粘连蛋白的纯化抗体通过间接免疫荧光分析基质。纤连蛋白和层粘连蛋白定位于正常肌纤维的细胞周围基底膜区；然而，细胞质中没有这两种糖蛋白。移植的肌肉移植物在最初7天经历了变性过程，然后开始初步再生。在14天移植的肌肉排斥开始时，这种再生努力停止。此时，在肌纤维和肌管的细胞质区域以及细胞外基质中都可以看到纤连蛋白。在随后的时间间隔，在整个被排斥的肌肉中观察到纤连蛋白染色强度增加。在经历再生但未发生排斥的肌肉移植物（即非抗原性移植物）中，未观察到纤连蛋白存在的这种增加（古拉蒂等人，1982年）。层粘连蛋白的分布在排斥过程中没有变化，并且定位于肌纤维和肌管的基底膜区，尽管基底膜的整体结构变形和塌陷。似乎基底膜对降解具有抗性，并且在被排斥的肌肉中层粘连蛋白的染色持续存在。这些结果表明，经历排斥的肌肉的细胞外基质发生了显著变化。纤连蛋白在肌肉排斥初始阶段的出现可能与免疫防御机制的过程存在因果关系；然而，纤连蛋白的确切作用仍然难以捉摸。
