Green L M, Lazarus J P, LaBue M, Shah M M
Department of Microbiology and Molecular Genetics, Loma Linda University Medical Center, California 92357, USA.
Endocrinology. 1995 Aug;136(8):3611-8. doi: 10.1210/endo.136.8.7628400.
MRL-lpr/lpr mice manifest a systemic lupus-like autoimmune disease. As part of this syndrome, the mice spontaneously develop autoimmune thyroiditis, which is morphologically and biochemically similar to human autoimmune thyroiditis. In this study we investigated whether thyroid tissue obtained from sites of chronic inflammation had altered gap junctional communication. Fresh tissue sections revealed that thyroid from the nondiseased mice (MRL-(+)/+) had connexins (Cx) localized to the plasma membrane at points of thyroid cell-cell contact. In contrast, the Cx in diseased mouse (MRL-lpr/lpr) thyroid tissue were not localized to the plasma membrane, and the fluorescent intensity was reduced for Cx43 and Cx26. Northern analysis confirmed that murine thyroid tissue expressed messenger RNA for these Cx. However, the diseased tissue expressed lower levels of Cx32 and Cx26 messenger RNA. The infiltrating cells and their biologically active products present in the diseased thyroid tissue may mediate the reduced Cx expression and aberrant gap junctional assembly. We established primary thyrocyte cultures to determine whether these differences persisted when the inflammatory factors were removed. The nondiseased thyroid cells were communication competent, with fluorescent dye transfer proceeding from the injected cell to primary contacts (95%) and to second and third order neighboring cells in 75% of the trials. Thyroid cells from the diseased mice were communication incompetent, in that 80% of microinjections failed to result in dye transfer to cells in direct contact. Immunocytochemistry indicated that the functional coupling in the normal mouse thyroid cells was associated with Cx43 located in the plasma membrane as assembled gap junctional plaques. The communication-deficient diseased thyroid cells had internalized Cx43 predominantly localized to perinuclear regions of the cells. Collectively, these data document altered Cx-protein distribution in the autoimmune diseased thyroid. The diseased thyroid tissue was devoid of plasma membrane identifiable gap junctions and deficient in intercellular communication. Culturing removed the inflammatory mediators; however, the disease cells retained their communication incompetence. These results suggest that if this deficiency was initiated by components of the inflammation process, then protracted changes must have occurred so that the continued presence of these factors was no longer required to sustain this difference.
MRL-lpr/lpr小鼠表现出一种系统性红斑狼疮样自身免疫性疾病。作为该综合征的一部分，这些小鼠会自发发展为自身免疫性甲状腺炎，其在形态学和生物化学方面与人类自身免疫性甲状腺炎相似。在本研究中，我们调查了从慢性炎症部位获取的甲状腺组织的间隙连接通讯是否发生了改变。新鲜组织切片显示，未患病小鼠（MRL-(+)/+）的甲状腺中，连接蛋白（Cx）定位于甲状腺细胞间接触点的质膜上。相比之下，患病小鼠（MRL-lpr/lpr）甲状腺组织中的Cx并未定位于质膜，且Cx43和Cx26的荧光强度降低。Northern分析证实，小鼠甲状腺组织表达这些Cx的信使RNA。然而，患病组织中Cx32和Cx26信使RNA的表达水平较低。患病甲状腺组织中浸润的细胞及其生物活性产物可能介导了Cx表达的降低和间隙连接组装异常。我们建立了原代甲状腺细胞培养体系，以确定去除炎症因子后这些差异是否仍然存在。未患病的甲状腺细胞具有通讯能力，荧光染料从注射细胞转移到初次接触的细胞（95%），在75%的试验中转移到二级和三级相邻细胞。患病小鼠的甲状腺细胞无通讯能力，因为80%的显微注射未能导致染料转移到直接接触的细胞。免疫细胞化学表明，正常小鼠甲状腺细胞中的功能偶联与位于质膜上组装成间隙连接斑块的Cx43相关。通讯缺陷的患病甲状腺细胞使Cx43内化，主要定位于细胞的核周区域。总体而言，这些数据证明了自身免疫性疾病甲状腺中Cx蛋白分布的改变。患病甲状腺组织缺乏质膜上可识别的间隙连接，细胞间通讯存在缺陷。培养去除了炎症介质；然而，患病细胞仍保持其无通讯能力。这些结果表明，如果这种缺陷是由炎症过程的成分引发的，那么一定发生了持久的变化，以至于不再需要这些因素的持续存在来维持这种差异。
