| 目的：对兔NTM角膜炎的临床表现及不同时期的病理变化进行观察。
方法：新西兰白兔48只，随机分为三组：瓣下 NTM感染组、表面NTM感染组、瓣下NTM 感染后使用激素组。模型建立后，对其临床表现进行观察，并分别于不同时间点（术后第5、7、14、21天）行角膜病灶细菌定量培养及组织病理学检查（包括苏木素-伊红染色、抗酸染色和抗CD4+、CD8+单克隆抗体免疫组化染色），观察兔角膜组织的病理改变和免疫反应。
结果：兔NTM角膜炎在感染早期（<7天）角膜反应性水肿、雾状混浊；感染中期（7~14天）出现浅基质层多灶性点、片状灰白致密浸润；感染晚期（>14天）角膜新生血管大量生长，角膜白斑形成。病理观察：感染早期角膜上皮增生，基质层大量中性粒细胞浸润，在炎症细胞附近有大量抗酸染色阳性菌NTM的存在；感染中期以淋巴细胞灶性浸润为主，同时伴有中性粒细胞浸润及纤维结缔组织增生；感染晚期成纤维细胞增生明显，组织修复。三组模型在术后第5天角膜均出现大量的中性粒细胞浸润，此后瓣下组及表面组的中性粒细胞数目逐渐减少，淋巴细胞数目逐渐增加； CD4+、CD8+细胞的浸润量随病程的发展呈现逐渐增加继而逐渐下降的过程；瓣下激素组与其他两组相比，CD4+细胞明显减少，差异有显著性意义（P<0.05）。
结论：NTM角膜炎临床特点为角膜浅基质层多灶性点、片状灰白致密浸润，病变过程中激素使用可使浸润面积增大。该种感染病理表现分三个过程，即早期（<7天）以中性粒细胞浸润为主的急性感染期，中期（7~14天）以淋巴细胞免疫反应为主的免疫反应期，晚期（>14天）则进入炎症修复期；同时T细胞产生的获得性免疫反应在本感染中可能起重要作用。
Abstract Objective: To observe clinical manifestation and pathology change of different time points of rabbit keratitis caused by NTM.
Methods: 48 New Zealand White rabbits were randomly divided into 3 groups: subflap infection group, surface infection group, subflap infection group with corticosteroid. After infection, clinical manifestation of all rabbits were observed. 4 rabbits in each group were sacrificed on 5, 7, 14, 21 day. Bacterial quantitative culture and histopathological examination were performed. The latter included hematoxylin and eosin staining, acid-fast staining, and CD4+ and CD8+ T cells immunohistochemistrical staining.
Results: All rabbits developed NTM keratitis in 4.0±1.2 days after surgery. The typical clinical feature included multifocal intense stromal infiltrates. In the earliest stage (before 7 days), all corneas became cloudy opacity and edematous; In the middle stage (7~4 days ), stromal infiltrates became its mainstay syndrom. In the last stage (after 14 days ), corneal neovascularization was striking and corneal stromal opacity and the scar developed. In the course of this disease, the corticosteroid used may worsen the corneal infiltrates and make the cornea difficult to kill NTM.
In the earliest stage, significant corneal epithelium proliferation was observed. In corneal stroma, There was infiltrates with polymorphonuclear (PMN) leukocytes, around which acid-fast bacilli was present. The infiltrates of plenty of lymphocytes in the cornea was characteristic to the middle stage of NTM keratitis. There were scattered PMN and a few of proliferated fibroblast cells beneath the epithelium. In the last stage, The fibroblast cells obviously proliferated and corneal cured. On the 5th day after surgery, the infiltrates of a large number of PMN wre present in all of cornea of NTM keratitis. Then PMN decreased and lymphocytes increased gradually so as to exceed the number of PMN in subflap infection group and surface infection group. In subflap infection group with corticosteroid, the lymphocyte can not increase obviously. There were significant difference between infection group and infection with corticosteroid group ( p value <0.05). In the last stage, the number of PMN decreased, while that of lymphocyte didn’t change. The number of CD4+, CD8+ T lymphocyte reached peak, then fell down gradually. CD4+ T lymphocyte decreased significantly in subflap infection group with corticosteroid compared with other two groups, and CD8+ T lymphocyte decreasing significantly on 7, 14 day (P<0.05).
Conclusion: The clinical feature of rabbit keratitis is multifocal dense superficial stromal infiltrates. The infiltration can be deteriorated with treatment of corticorsteroid. The pathogenesis of NTM keratitis is divided into three stages: Acute infection stage characterized with PMN infiltrates in earlier period (<7 days), immunoreaction stage characterized with lymphocyte accumulation in middle period (7~14 days), and inflammation recession (>14 days). Acquired immunoreaction should play an important role in NTM keratitis.
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