Martin C A, el-Sabban M E, Zhao L, Burakoff R, Homaidan F R
Division of Gastroenterology and Nutrition, Winthrop University Hospital, Mineola, NY 11501, USA.
Cell Adhes Commun. 1998 Mar;5(2):83-95. doi: 10.3109/15419069809040283.
Activated macrophages (M phi) found in the intestinal lesions of patients with inflammatory bowel disease (IBD) secrete many inflammatory mediators which can regulate intestinal epithelial cell (IEC) function. However, little is known about direct M phi-IEC interactions. Two potential mechanisms by which cells may interact are through specific receptor-ligand binding of adhesion molecules, such as integrins or cadherins, and by exchange of cytoplasmic substances through transmembraneous channels called gap junctions. We investigated whether M phi could adhere to epithelial cells in culture and form transmembrane communication channels as defined by dye transfer. Primary cultures of murine M phi and a M phi cell line, P388D1, adhered to Mode-K and IEC6, but not CMT-93 IEC. Antibody blocking studies determined that P388D1-Mode-K binding was partially dependent on beta 2 integrin (CD18) function, Mode-K constitutively expressed CD106 (VCAM-1) and cell associated fibronectin, while P388D1 expressed low levels of CD49d/CD29 (VLA4) but blocking antibodies to these surface molecules did not inhibit P388D1-Mode-K adherence. Transfer of calcein dye from M phi to IEC was quantitated by flow cytometry and was dependent on M phi-IEC adhesion. Dye transfer was concentration dependent in that the fluorescence intensity of Mode-K was proportional to the number of adherent P388D1 cells as well as the dye load of the M phi. These results indicate that M phi interact with IEC by adhesion and possibly through gap junctions and may thus regulate IEC function by direct cell-cell communication.
在炎症性肠病（IBD）患者肠道病变中发现的活化巨噬细胞（M phi）分泌许多可调节肠道上皮细胞（IEC）功能的炎症介质。然而，关于M phi与IEC之间的直接相互作用却知之甚少。细胞间相互作用的两种潜在机制是通过粘附分子（如整合素或钙粘蛋白）的特异性受体 - 配体结合，以及通过称为缝隙连接的跨膜通道交换细胞质物质。我们研究了M phi在培养中是否能粘附于上皮细胞并形成如染料转移所定义的跨膜通讯通道。小鼠M phi的原代培养物和M phi细胞系P388D1粘附于Mode-K和IEC6，但不粘附于CMT-93 IEC。抗体阻断研究确定P388D1与Mode-K的结合部分依赖于β2整合素（CD18）的功能，Mode-K组成性表达CD106（VCAM-1）和细胞相关纤连蛋白，而P388D1表达低水平的CD49d/CD29（VLA4），但针对这些表面分子的阻断抗体并不抑制P388D1与Mode-K的粘附。通过流式细胞术对钙黄绿素染料从M phi转移到IEC进行定量，其依赖于M phi与IEC的粘附。染料转移呈浓度依赖性，即Mode-K的荧光强度与粘附的P388D1细胞数量以及M phi的染料负载量成正比。这些结果表明M phi通过粘附以及可能通过缝隙连接与IEC相互作用，因此可能通过直接的细胞间通讯调节IEC功能。
