Tseng S C, Li D Q
Department of Ophthalmology, University of Miami School of Medicine, Florida, USA.
Cornea. 1996 Mar;15(2):168-78. doi: 10.1097/00003226-199603000-00010.
Frozen sections of corneoscleral buttons from normal and aniridic donors were stained with hematoxylin and periodic acid-Schiff, monoclonal antibodies AE-5 and AK-2 (to cornea-specific K3 and K12 keratins, respectively), and AM-3 (to conjunctival goblet cells) as well as with subtype-specific antibodies to seven different protein kinase C (PKC) subtypes, the signal transduction isoenzymes increasingly implicated in the regulation of cell growth and differentiation. Compared with the normal cornea, the aniridic cornea showed decreased AE-5 and AK-2 stainings, increased AM-3 staining, attenuated Bowman's membrane, invasion of new blood vessels, and limbal epithelial hyperplasia. In the normal tissue, the corneal epithelium expressed PKC alpha, lambda, and zeta; the limbal and conjunctival epithelia expressed additional PKC gamma. Conjunctival goblet cells expressed only PKC lambda. Within a given epithelium, different PKC subtypes had different cell-layer distributions. In the aniridic tissue, some of the four normally expressed subtypes were expressed in different cell layers, especially at the limbal region. PKC beta and PKC delta, which were normally weakly expressed, were markedly up-regulated. These results support the conclusion that the aniridic cornea does indeed manifest features of limbal stem cell deficiency with decreased corneal epithelial phenotype and increased conjunctival epithelial phenotype. Different capacities of proliferation and differentiation may be affected by the differential expression of PKC subtypes by different cell layers of normal ocular surface epithelia. The aberrant expression of PKC subtypes in aniridia may thus result in abnormal proliferation and differentiation noted in its ocular surface epithelia. Because limbal stem cells are the ultimate source of corneal proliferation and differentiation, we postulate that limbal deficiency in aniridia is a result of abnormal limbal stem cells.
对来自正常和无虹膜供体的角膜巩膜纽扣状组织的冰冻切片进行苏木精和过碘酸希夫染色、使用单克隆抗体AE - 5和AK - 2（分别针对角膜特异性角蛋白K3和K12）、AM - 3（针对结膜杯状细胞）以及七种不同蛋白激酶C（PKC）亚型的亚型特异性抗体进行染色，这些信号转导同工酶越来越多地参与细胞生长和分化的调节。与正常角膜相比，无虹膜角膜显示AE - 5和AK - 2染色减少、AM - 3染色增加、Bowman膜变薄、新生血管侵入以及角膜缘上皮增生。在正常组织中，角膜上皮表达PKCα、λ和ζ；角膜缘和结膜上皮表达额外的PKCγ。结膜杯状细胞仅表达PKCλ。在给定的上皮组织内，不同的PKC亚型具有不同的细胞层分布。在无虹膜组织中，四种正常表达的亚型中的一些在不同细胞层中表达，尤其是在角膜缘区域。通常弱表达的PKCβ和PKCδ明显上调。这些结果支持以下结论：无虹膜角膜确实表现出角膜缘干细胞缺乏的特征，角膜上皮表型减少，结膜上皮表型增加。正常眼表上皮不同细胞层中PKC亚型的差异表达可能影响增殖和分化的不同能力。因此，无虹膜中PKC亚型的异常表达可能导致其眼表上皮出现异常增殖和分化。由于角膜缘干细胞是角膜增殖和分化的最终来源，我们推测无虹膜中的角膜缘缺陷是角膜缘干细胞异常的结果。
