替加环素/壳聚糖纳米粒对碱烧伤角膜新生血管的作用

The effect of tigecycline/chitosan nanoparticles on corneal neovascularization after alkali burn

目的探究负载替加环素(tigecycline,TGC)的壳聚糖(chitosan,CS)纳米粒复合物对碱烧伤角膜新生血管(corneal neovascularization,CNV)的影响。方法制备TGC/CS纳米粒,检测其外形、粒径,检测并计算其包封率、载药量及体外释药情况。选取40只新西兰大白兔,随机分TGC/CS纳米粒组(A组)、TGC组(B组)、空白CS纳米粒组(C组)和生理盐水对照组(D组),每组10只,右眼制作碱烧伤模型,以右眼为实验眼,左眼为对照眼,分别使用TGC/CS纳米粒、TGC、CS纳米粒、生理盐水滴右眼,每日2次,共进行28 d。使用裂隙灯显微镜观察CNV情况并测量新生血管长度,病理切片HE染色观察其角膜结构、新生血管和细胞浸润情况等病理变化,Western blot法检测角膜组织核转录因子-κB(nuclear transcription factor-κB,NF-κB)、血管内皮生长因子(vascular endothelial growth factor,VEGF)、基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)的表达。结果TGC/CS纳米粒大部分为规则的球形,粒径为(235.84±34.59)nm,包封率为(67.17±0.29)%,载药量为(59.67±0.29)%,体系较为稳定,有缓释功能。TGC/CS纳米粒对兔角膜及结膜无损伤作用。CNV面积在碱烧伤后7 d、14 d、28 d时,A组明显少于B、C、D组,B组明显小于C、D组,差异均有统计学意义(均为P<0.05),C组面积小于D组但其差异无统计学意义(P>0.05)。HE染色结果显示,碱烧伤后7 d各组角膜上皮细胞部分损伤,基质水肿,大量炎症细胞浸润,部分新生血管生成;碱烧伤后14 d各组角膜结构部分恢复,中等量炎症细胞浸润,CNV面积达到顶峰,碱烧伤后28 d各组角膜各层结构基本复原,炎症细胞大量减少,新生血管萎缩,整个过程中C、D两组炎症程度最重,B组次之,A组炎症最轻。Western blot结果显示,A、B、C、D组的NF-κB、MMP-9相对表达均依次增加,差异均有统计学意义(均为P<0.05);A组VEGF相对表达量小于B、C、D组,B组VEGF相对表达量小于C、D组,差异均有统计学意义(均为P<0.05),C组与D组VEGF相对表达量基本相同。结论TGC/CS纳米粒能够通过下调角膜组织中的NF-κB、VEGF、MMP-9的表达减少碱烧伤CNV的生成且对眼表无损害。

Objective To investigate the effect of chitosan(CS)nanoparticles loaded with tigecycline(TGC)on corneal neovascularization after alkali burn.Methods We prepare TGC/CS nanoparticles and observe their shape,particle size,and calculate encapsulation efficiency,drug loading and drug release in vitro.Six New Zealand white rabbits were selected.The right eye was the subjects and the left eye was the control.New Zealand white rabbits were randomly divided into TGC/CS nanoparticles group(group A),TGC group(group B),blank chitosan(CS)nanoparticles group(group C),and normal saline control group(group D),10 eyes in each group.TGC/CS nanoparticles,TGC eyes,CS nanoparticles and normal saline were used for group A,B,C,and D,accordingly for 28 days.The corneal neovascularization(CNV)was observed under slit lamp microscope and the length of CNV was measured.HE staining was used to observe the corneal structure,neovascularization and cell infiltration.The expressions of nuclear transcription factor-κB(NF-κB),vascular endothelial growth factor(VEGF),matrix metalloproteinase-9(MMP-9)were detected by Western blot.Results Most of TGC/CS nanoparticles were regular spheres,with a diameter of(235.84±34.59)nm,a entrapment efficiency of(67.17±0.29)%and a drug loading of(59.67±0.29)%respectively.The system was stable and had sustained-release function.TGC/CS nanoparticles had no damage to the cornea and conjunctiva of rabbits.The CNV area of group A was significantly less than that of group B,C and D at 7,14 and 28 days after alkali burn,while group B was significantly less than group C and D,and the differences were statistically significant(all P>0.05),the CNV area of group C was smaller than that of group D but the difference is not statistically significant(P>0.05).HE staining showed that on day 7 after alkali burn,some epithelial cells were damaged,matrix edema,a large number of inflammatory cells infiltrated,and some neovascularization;on day 14 after alkali burn,the corneal structure was partially restored,with a medium amount of inflammatory cells infiltrated,CNV area reached the peak,and on day 28 after alkali burn,the structure of each layer was basically restored,a large number of inflammatory cells were reduced,neovascularization was atrophic,and the inflammation degree of group C and D was the heaviest,group B was in the middle,and group A was the lightest.The results of Western blot showed that the relative expression of NF-κB and MMP-9 in group A,B,C,and D increased in turn,and the differences were significant(all P<0.05);the relative expression of VEGF in group A was less than that in group B,C and D,and group B was less than that in group C and D,and the differences were significant(all P<0.05),and group C and group D were basically the same.Conclusion TGC/CS nanoparticles can reduce the neovascularization in alkali burned cornea by down regulating the expression of NF-κB,VEGF and MMP-9 in cornea,and they has no harm to the ocular surface.