环境烟草烟雾对小鼠泪膜功能和角膜上皮组织结构的影响

目的　探讨环境烟草烟雾（enviromental tobacco smoke，ETS）对小鼠泪膜功能和角膜上皮组织结构的影响。方法　选取SPF级c57BL雄性小鼠12只，随机分为对照组和ETS干预组，每组6只。对照组不进行ETS干预，ETS干预组进行ETS干预，每天2次，一次30 min，干预12周。在干预前及干预后对各组小鼠进行泪膜功能检测，包括泪膜破裂时间、荧光素染色(FL)评分；干预后摘取小鼠角膜组织，行HE染色，在光学显微镜下观察小鼠角膜上皮结构变化情况。结果　干预12周后，对照组泪膜破裂时间和FL评分与干预前相比，差异均无统计学意义(均为P>0.05)；而ETS干预组泪膜破裂时间较干预前明显缩短，FL评分较干预前明显增加，差异均有统计学意义（均为P<0.05)。ETS干预组干预12周后泪膜破裂时间较对照组明显缩短，FL评分较对照组明显增加，差异均有统计学意义(均为P<0.05)；两组干预前泪膜破裂时间和FL评分差异均不明显（均为P>0.05）。FL染色结果显示:干预12周后，对照组小鼠角膜上皮完整，角膜染色呈阴性；ETS干预组整个角膜上皮荧光素着染区域明显增加，呈点片状。HE染色结果显示:干预12周后，对照组未见角膜上皮层数的改变，厚度也基本未变，基底细胞仍为单层柱状上皮细胞，表层上皮较完整；ETS干预组可见角膜上皮细胞层数增多，厚度增加，细胞排列紊乱，表层上皮细胞有损失及脱落，角膜表面不光滑。干预前对照组小鼠上皮细胞为（5±1）层，干预后基本不变；ETS干预组干预后为（7±1）层；干预后两组上皮细胞层数比较差异有统计学意义（P＜0.05）。结论　ETS会影响小鼠泪膜功能，损伤小鼠角膜上皮的组织结构。

Influence of environmental tobacco smoke on tear film function and structure of corneal epithelial tissues in mice

Objective　To investigate the influence of environmental tobacco smoke (ETS) on tear film function and structure of corneal epithelial tissues in mice. Methods　Totally 12 male c57BL mice were randomly divided into control group and ETS group, 6 mice in each group. Mice in control group did not receive ETS intervention, and those in ETS group were intervened by ETS two times a day for 12 weeks, 30 minutes each. Tear film function was detected before and after ETS intervention, including break-up time of tear film (BUT), corneal florescence staining (FL) score, etc. Corneal tissues were removed after intervention, and received HE staining. Changes of corneal epithelial tissues were observed under light microscope. Results　Compared with that before intervention, there was no significant difference in BUT or FL score for control group at 12-week intervention (both P>0.05); while BUT obviously reduced and FL score obviously increased in ETS group at 12-week intervention (both P<0.05). Compared with control group, BUT obviously reduced and FL score obviously increased in ETS group after 12-week intervention, but the differences were statistically significant (all P<0.05). There was no statistical difference in BUT or FL score between the two groups before intervention (all P>0.05). FL staining results showed: corneal epithelium was intact and corneal staining was negative in control group after 12-week intervention; fluorescein staining area in the whole corneal epithelium was obviously increased in dot-flake shape in ETS group at 12-week intervention. HE staining results showed: there was no change in number or thickness of corneal epithelial layers, basal cells were single-layer columnar epithelial cells and surface epithelium was intact in control group after 12-week intervention. In ETS group, number and thickness of corneal epithelial cell layers increased, there was disordered cell arrangement, surface epithelial cell loss or falling off, and unsmooth corneal surface. The number of epithelial cell layers was 5±1 before intervention and basically unchanged after intervention in control group; the number of epithelial cell layers was 7±1 after intervention in ETS group; statistical difference was found in number of epithelial cell layers after intervention between the two groups (P<0.05). Conclusion　 ETS can influence tears film function in mice and damage the structure of corneal epithelial tissues.