阻断血管内皮生长因子C促进角膜移植后新生淋巴管和血管的“分离生长”（英文）

Lymphatic vessels growing apart from blood vessels in transplanted corneas after the blockade of vascular endothelial growth factor C

背景:角膜淋巴管有利于角膜抗原的运输,从而加速了抗原提呈的进程,在角膜免疫中起着重要的作用。然而,由于角膜移植后角膜新生血管和淋巴管呈"平行"生长,因而很难对淋巴管在移植免疫中所起的具体作用大小作出准确的评估。目的:通过阻断血管内皮生长因子C的表达,探索角膜移植后角膜新生淋巴管和血管的生长变化。方法:建立同种异体角膜移植的大鼠模型130只,将受体大鼠随机等分为血管内皮生长因子C拮抗组和对照组。血管内皮生长因子C拮抗组大鼠在移植后第2天起腹腔注射单克隆抗体,隔天1次,连续2周,阻断角膜移植后血管内皮生长因子C的表达。对照组大鼠注射生理盐水。结果与结论:(1)血管内皮生长因子C拮抗组大鼠角膜中血管内皮生长因子C的表达水平显著下降。在对照组中,角膜新生淋巴管和血管呈"平行"生长;(2)在血管内皮生长因子C拮抗组中,血管面积轻度减少,而淋巴管面积呈显著性减少(P<0.05);(3)在对照组中大鼠角膜排斥指数与血管面积、淋巴管面积均呈显著性正相关,而在血管内皮生长因子C拮抗组大鼠角膜中虽然排斥指数与血管面积显著性相关,但排斥指数与淋巴管面积间无相关性;(4)血管内皮生长因子C拮抗组中植片平均存活时间明显大于对照组;(5)说明拮抗血管内皮生长因子C后,角膜新生淋巴管和血管间出现了"分离生长";而拮抗血管内皮生长因子C可以有效抑制角膜移植后的角膜新生淋巴管,从而提高植片的存活率。

BACKGROUND： Corneal lymphangiogenesis is beneficial to the transport of corneal antigenic materials, and accelerates the process of antigen presentation, thereby playing an important role in corneal immunity. However, due to the parallel outgrowth of corneal blood and lymphatic vessels in transplanted corneas, it is often difficult to accurately evaluate the role of corneal lymphatic vessels in allograft rejection. OBJECTIVE： To explore the development of corneal lymphangiogenesis and angiogenesis in transplanted rat corneas after the blockade of vascular endothelial growth factor C （VEGF-C）. METHODS： 130 rats used to establish corneal allogenic transplantation models were equally randomized into two groups： the anti-VEGF-C group and the control group. VEGF-C was blocked in the anti-VEGF-C group by intraperitoneal injection of neutralizing monoclonal anti-VEGF-C antibody every other day for 2 consecutive weeks. Meanwhile, rats in control groups received intraperitoneal injections of saline. Corneal angiogenesis and lymphangiogenesis were characterized using whole mount immunofluorescence, and the immune rejection of the grafts was evaluated by scoring the rejection index （RI）. In addition, the expression of VEGF-C was examined by real-time PCR. The relationship of corneal lymphangiogenesis and angiogenesis to RI in transplanted corneas was also characterized. RESULTS AND CONCLUSION： VEGF-C expression was markedly downregulated after VEGF-C blockade. Corneal lymphangiogenesis developed in parallel with corneal angiogenesis in the control group. While there was a mild reduction in blood vessel area （BVA） and a significant decrease in lymphatic vessel area （LVA） in the anti-VEGF-C group （P 〈 0.05）. In addition, RI was positively correlated with BVA （P 〈 0.05） and LVA （P 〈 0.05） in the control group. However, although RI was significantly correlated with BVA （P 〈 0.05） in the anti-VEGF-C group, the correlation between RI and LVA was not statistically significant （P 〉 0.05）. the graft survival time in the anti-VEGF-C group was significantly increased compared with that in the control group （P 〈 0.05）. Our results show that the outgrowth of lymphatic vessels is separated from that of blood vessels in transplanted corneas by blocking VEGF-C. The blockade of VEGF-C has a significant role in preventing corneal lymphangiogenesis in corneal beds, which results in higher allograft survival rates.