Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06519, USA.
Arterioscler Thromb Vasc Biol. 2013 Mar;33(3):489-500. doi: 10.1161/ATVBAHA.112.300893. Epub 2013 Jan 3.
To assess the role claudin-5, an endothelial cell (EC) tight junction protein, plays in establishing basal permeability levels in humans by comparing claudin-5 expression levels in situ and analyzing junctional organization and function in 2 widely used models of cultured ECs, namely human dermal microvascular (HDM)ECs and human umbilical vein (HUV)ECs.
By immunofluorescence microscopy, ECs more highly express claudin-5 (but equivalently express vascular endothelial-cadherin) in human dermal capillaries versus postcapillary venules and in umbilical and coronary arteries versus veins, correlating with known segmental differences in tight junction frequencies and permeability barriers. Postconfluent cultured HDMECs express more claudin-5 (but equivalent vascular endothelial-cadherin) and show higher transendothelial electric resistance and lower macromolecular flux than similarly cultured HUVECs. HDMEC junctions are more complex by transmission electron microscopy and show more continuous claudin-5 immunofluorescence than HUVEC junctions. Calcium chelation or dominant negative vascular endothelial-cadherin overexpression decreases transendothelial electric resistance and disrupts junctions in HUVECs, but not in HDMECs. Claudin-5 overexpression in HUVECs fails to increase transendothelial electric resistance or claudin-5 continuity, whereas claudin-5 knockdown in HDMECs, but not in HUVECs, reduces transendothelial electric resistance and increases antibody accessibility to junctional proteins.
Claudin-5 expression and junctional organization control HDMEC and arteriolar-capillary paracellular barriers, whereas HUVEC and venular junctions use vascular endothelial-cadherin.
通过比较原位表达水平并分析 2 种常用培养的内皮细胞（EC）模型中的连接组织和功能，即人真皮微血管（HDM）EC 和人脐静脉（HUV）EC，评估紧密连接蛋白 Claudin-5 在人类中建立基础通透性水平中的作用。
通过免疫荧光显微镜，与已知的紧密连接频率和通透性屏障的节段性差异相关，与后微静脉相比，HDM 毛细血管中的 EC 更高度表达 Claudin-5（但同等表达血管内皮钙黏蛋白），与后微静脉相比，HDM 毛细血管中的 EC 更高度表达 Claudin-5（但同等表达血管内皮钙黏蛋白），而在脐动脉和冠状动脉中与静脉相比，HDM 毛细血管中的 EC 更高度表达 Claudin-5（但同等表达血管内皮钙黏蛋白）。传代培养的 HDMEC 表达更多 Claudin-5（但同等表达血管内皮钙黏蛋白），表现出比类似培养的 HUVEC 更高的跨内皮电阻和更低的大分子通量。HDMEC 连接通过透射电子显微镜更为复杂，并且 Claudin-5 免疫荧光更为连续，而 HUVEC 连接则更为复杂。钙螯合或显性负性血管内皮钙黏蛋白过表达降低 HUVEC 的跨内皮电阻并破坏连接，但不影响 HDMEC。在 HUVEC 中过表达 Claudin-5 不能增加跨内皮电阻或 Claudin-5 的连续性，而 Claudin-5 在 HDMEC 中的敲低，而不是在 HUVEC 中，降低跨内皮电阻并增加抗体与连接蛋白的可及性。
Claudin-5 表达和连接组织控制 HDMEC 和小动脉毛细血管旁通屏障，而 HUVEC 和小静脉连接则使用血管内皮钙黏蛋白。
