Department of Anatomy and Cell Biology, Martin Luther University of Halle-Wittenberg, Grosse Steinstrasse 52, D-06097 Halle/Saale, Germany.
Ann Anat. 2010 Apr 20;192(2):65-9. doi: 10.1016/j.aanat.2010.01.006. Epub 2010 Feb 20.
The ocular surface, constantly exposed to environmental pathogens, is particularly vulnerable to infection. Hence an advanced immune defence system is essential to protect the eye from microbial attack. Antimicrobial peptides, such as beta-defensins, are essential components of the innate immune system and are the first line of defence against invaders of the eye. High concentrations of L-arginine and L-lysine are necessary for the expression of beta-defensins. These are supplied by epithelial cells in inflammatory processes. The limiting factor for initiation of beta-defensin production is the transport of L-arginine and L-lysine into the cell. This transport is performed to 80% by only one transporter system in the human, the y(+)-transporter. This group of proteins exclusively transports the cationic amino acids L-arginine, L-lysine and L-ornithine and is also known under the term cationic amino acid transporter proteins (CAT-proteins). Various infections associated with L-arginine deficiency (for example psoriasis, keratoconjuctivitis sicca) are also associated with an increase in beta-defensin production. For the first time, preliminary work has shown the expression of human CATs in ocular surface epithelia and tissues of the lacrimal apparatus indicating their relevance for diseases of the ocular surface. In this review, we summarize current knowledge on the human CATs that appear to be integrated in causal regulation cascades of beta-defensins, thereby offering novel concepts for therapeutic perspectives.
眼部表面不断暴露于环境病原体中，因此特别容易受到感染。因此，先进的免疫防御系统对于保护眼睛免受微生物攻击至关重要。抗菌肽（如β-防御素）是先天免疫系统的重要组成部分，是抵御眼部入侵物的第一道防线。高浓度的 L-精氨酸和 L-赖氨酸对于β-防御素的表达是必要的。这些物质由上皮细胞在炎症过程中提供。β-防御素产生的起始限制因素是 L-精氨酸和 L-赖氨酸进入细胞的转运。这种转运在人类中仅由一种转运体系统（y(+)-转运体）完成 80%。这组蛋白质专门运输阳离子氨基酸 L-精氨酸、L-赖氨酸和 L-鸟氨酸，也被称为阳离子氨基酸转运蛋白（CAT 蛋白）。与 L-精氨酸缺乏相关的各种感染（例如银屑病、干燥性角结膜炎）也与β-防御素的产生增加有关。初步研究首次表明，人 CAT 在眼部表面上皮细胞和泪器组织中表达，表明它们与眼部表面疾病有关。在这篇综述中，我们总结了目前关于人 CAT 的知识，这些 CAT 似乎整合在β-防御素的因果调节级联中，从而为治疗提供了新的概念。
