Study of adventitial inflammation and inflammatory factors in pathogenesis of allograft arteriosclerosis in rats

Objective To study the roles of serum inflammatory factors IL-6 and TNF-α and allograft adventitial inflammation in the pathogenesis of allograft arteriosclerosis in rats. Methods Thirty-six allogeneic allograft rats and 16 syngeneic allograft rats were randomly divided into 4 groups (9 rats in each experimental group and 4 in each control group): A, harvested at Week 1 post-operation; B, harvested at Week 2 post-operation; C, harvested at Week 3 post-operation; D, harvested at Week 4 post-operation. Blood samples were collected before transplantation and after harvest. The method of ELISA was used for testing serum inflammatory factors including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), HE staining for pathologic changes of aortic allograft and immunohistochemical method for expression of α-actin, cyclin dependent kinase-1 (CDK1) and proliferating cell nuclear antigen (PCNA). Compare the inflammatory factors and other observations between groups and preoperative. Results At Week 1 post-operation, a large amount of inflammatory cell infiltration in adventitia was observed; at Week 2 post-operation, slight collagen fibers hyperplasia with inflammatory infiltration; at Week 4 post-operation, obvious odventitia thickening with a large number of smooth muscle cells, collagen fibers and inflammatory cells, smooth muscle cells migration from adventitia to intima. Expressions of α-actin, CDK1 and PCNA kept increasing with time in adventitia (P < 0.05). There was a significant increase in serum TNF-α level in Groups A, B, C and D, as compared with pre-operative basal level (P <0.01). There was no difference between controls and pre-operative basal level. IL-6 level slightly declined in the middle stage, but finally increased in experimental group B (P <0.0.5) while it significantly increased in Groups A, C, D (P <0.01). In the control groups A, B, C, it was higher than pre-operative level (P < 0.05). In experimental groups A, C, D, it had a significant increase as compared with controls (P < 0.01). Conclusions In abdominal aortic allograft models, obvious angiosclerosis was found in adventitia and intima in accordance with the severity of odventitial inflammation. Thus the inflammatory factors and inflammatory cell infiltration in odventitia are both involved in the pathogenesis of early allograft arteriosclerosis. Key words: Transplants;  Arteriosclerosis;  Inflammation