Increased ectodomain shedding of cell adhesion molecule 1 as a cause of type II alveolar epithelial cell apoptosis in patients with idiopathic interstitial pneumonia.
Increased ectodomain shedding of cell adhesion molecule 1 as a cause of type II alveolar epithelial cell apoptosis in patients with idiopathic interstitial pneumonia.
复制标题
细胞粘附分子 1 胞外域脱落增加是特发性间质性肺炎患者 II 型肺泡上皮细胞凋亡的原因。
DOI：
10.1186/s12931-015-0255-x
复制
发表时间：
2015-08-01
影响因子：
5.8
通讯作者：
Ito A
中科院分区：
文献类型：
--
作者：
Yoneshige A;Hagiyama M;Inoue T;Mimae T;Kato T;Okada M;Enoki E;Ito A
肺泡上皮细胞（AEC）凋亡作为特发性间质性肺炎（IIP）发展的早期致病事件引起了人们的关注；然而，其致病机制仍不清楚。细胞粘附分子 1 (CADM1) 是免疫球蛋白超家族中的 AEC 粘附分子。它通过蛋白酶介导的胞外域脱落（称为 α-脱落）生成膜相关的 C 末端片段 αCTF。 CADM1 α 脱落增加导致肺气肿肺中 AEC 凋亡。 36 例 IIP 尸检患者的福尔马林固定石蜡包埋肺叶 (n = 39) 分为急性 IIP (n = 10)、纤维化型非特异性 IIP (f-NSIP，n = 10)、隐源性组织性 IIP (n = 9) 和普通 IIP (n = 10)。通过蛋白质印迹法检查肺切片中的CADM1表达，并与对照肺进行比较（n = 10）。 CADM1 α 脱落率计算为 αCTF 与全长 CADM1 的相对量，并通过标准化细胞角蛋白 7（肺上皮标记物）来估计每个上皮细胞的全长 CADM1 水平。通过单链 DNA (ssDNA) 的免疫组织化学检测凋亡 AEC。 NCI-H441 和 A549 人肺上皮细胞用小干扰 RNA (siRNA) 转染以沉默 CADM1 表达，并通过末端核苷酸切口标记测定进行分析。所有IIP亚型中CADM1 α-脱落率均高于对照组（P ≤ 0.019），而f-NSIP中全长CADM1水平较低（P = 0.007）。 α-脱落率和全长CADM1水平相互相关（P = 0.015），并与ssDNA阳性AEC的比例相关（P ≤ 0.024）。转染 siRNA 的 NCI-H441 细胞全长 CADM1 表达率降低 61%，凋亡细胞比例增加 17 倍。 A549 细胞也获得了类似的结果。 CADM1 α-脱落似乎在所有四种 IIP 亚型中均增加，因此通过降低全长 CADM1 水平导致 AEC 凋亡。这种机制尤其影响 f-NSIP。 IIP和肺气肿引起AEC凋亡的分子机制可能相似。本文的在线版本 (doi:10.1186/s12931-015-0255-x) 包含补充材料，可供授权用户使用。
Lung alveolar epithelial cell (AEC) apoptosis has attracted attention as an early pathogenic event in the development of idiopathic interstitial pneumonia (IIP); however, the causative mechanism remains unclear. Cell adhesion molecule 1 (CADM1) is an AEC adhesion molecule in the immunoglobulin superfamily. It generates a membrane-associated C-terminal fragment, αCTF, through protease-mediated ectodomain shedding, termed α-shedding. Increased CADM1 α-shedding contributes to AEC apoptosis in emphysematous lungs. Formalin-fixed, paraffin-embedded lung lobes (n = 39) from 36 autopsied patients with IIP were classified as acute IIP (n = 10), fibrosing-type nonspecific IIP (f-NSIP, n = 10), cryptogenic organizing IIP (n = 9), and usual IIP (n = 10). CADM1 expression in the lung sections was examined by western blotting and compared with control lungs (n = 10). The rate of CADM1 α-shedding was calculated as the relative amount of αCTF to full-length CADM1, and the full-length CADM1 level was estimated per epithelial cell by normalization to cytokeratin 7, a lung epithelial marker. Apoptotic AECs were detected by immunohistochemistry for single-stranded DNA (ssDNA). NCI-H441 and A549 human lung epithelial cells were transfected with small interfering RNA (siRNA) to silence CADM1 expression and analyzed by terminal nucleotide nick end labeling assays. The rate of CADM1 α-shedding was higher in all IIP subtypes than in the control (P ≤ 0.019), and the full-length CADM1 level was lower in f-NSIP (P = 0.007). The α-shedding rate and full-length CADM1 level were correlated with each other (P = 0.015) and with the proportion of ssDNA-positive AECs (P ≤ 0.024). NCI-H441 cells transfected with siRNA exhibited a 61 % lower rate of expression of full-length CADM1 and a 17-fold increased proportion of apoptotic cells. Similar results were obtained with A549 cells. CADM1 α-shedding appeared to be increased in all four IIP subtypes and consequently contributed to AEC apoptosis by decreasing the full-length CADM1 level. This mechanism particularly impacted f-NSIP. The molecular mechanism causing AEC apoptosis may be similar between IIP and emphysema. The online version of this article (doi:10.1186/s12931-015-0255-x) contains supplementary material, which is available to authorized users.