NEUROTROPHIC FACTOR MODULATION OF CORNEAL ENDOTHELIUM

角膜内皮作为流体进入角膜的屏障发挥作用，并维持角膜的透明度。人角膜内皮细胞（CEC），像神经元细胞一样，在体内基本上不能再生。正如神经营养因子促进神经元的存活一样，营养因子也可以促进CEC的存活。睫状神经营养因子（CNTF）最初是从睫状体、虹膜和脉络膜的眼组织提取物中发现和分离的。CNTF诱导神经元中VIP基因的表达，VIP是一种也显示神经营养活性的神经肽。在供体人中，初步研究表明，VIP免疫反应性和VIP mRNA存在于CEC中，CNTF和VIP受体均在CEC中表达，CNTF在角膜中表达，并且VIP免疫反应性在器官培养物中的CNTF处理的人角膜中上调。此外，对牛角膜的初步研究表明：1）CEC中存在CNTF受体和VIP mRNA，2）VIP处理有助于环钻角膜纽扣中的CEC在随后的过氧化氢处理中存活，3）VIP有助于在角膜器官培养物中保存CEC的六边形细胞边界。我们的长期目标是证明CNTF和VIP是人类CEC的营养因子，能够1）延长角膜移植的保存时间和2）保持完整性。移植的角膜在接受者眼中。我们的具体目标是：检验假设1。CNTF诱导人CEC中VIP蛋白的表达是通过CNTF诱导VIP基因表达介导的。2. VIP从人CEC释放，是人CEC的自分泌因子，并且衰老对VIP/VIP受体表达有影响。CNTF和VIP有助于维持储存的人角膜和人角膜器官培养物中CEC细胞-细胞连接和细胞-基质附着的活力、屏障功能和完整性。

The corneal endothelium functions as a barrier to fluid movement into the cornea and maintains the transparency of the cornea. Human corneal endothelial cells (CEC), like neuronal cells, essentially do not regenerative in vivo. Just as the survival of neurons is promoted by neurotrophic factors, the survival of CEC may also be promoted by trophic factors. Ciliary neurotrophic factor (CNTF) was discovered and originally isolated from an extract of eye tissues consisting of ciliary body, iris, and choroid. CNTF induces in neurons the expression of the gene for VIP, a neuropeptide that also shows neurotrophic activities. In donor human, preliminary studies showed that VIP-immunoreactivities and VIP mRNA are present in the CEC, that both CNTF and VIP receptors are expressed in CEC, that CNTF is expressed in the cornea, and that the VIP-immunoreactivities are up- regulated in CNTF- treated human corneas in organ cultures. Further, preliminary studies of the bovine cornea showed 1) the presence of CNTF receptor and VIP mRNA in the CEC, 2) VIP treatment helped the CEC in trephined cornea buttons to survive subsequent hydrogen peroxide treatment, and 3) VIP helped to preserve the hexagonal cell borders of the CEC in cornea organ cultures. Our long-term goal is to demonstrate that CNTF and VIP are trophic factors of human CEC capable of 1) prolonging the duration of preservation of corneas for transplantation and 2) maintaining the integrity. Of transplanted corneas in recipient eyes. Our specific aims are: To test the hypothesis that 1. The CNTF-induced VIP protein expression in human CEC is mediated through CNTF induction of VIP gene expression. 2. VIP is released from human CEC and is an autocrine factor for human CEC, and that there is an effect of aging on VIP/VIP receptor expression. 3, CNTF and VIP help to maintain the viability, the barrier function, & the integrity of CEC cell-cell junction and cell-matrix attachment in stored human corneas and in human cornea organ cultures.