Bidirectional role of IL-6 signal in pathogenesis of lung fibrosis.
Bidirectional role of IL-6 signal in pathogenesis of lung fibrosis.
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DOI：
10.1186/s12931-015-0261-z
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发表时间：
2015-08-20
影响因子：
5.8
通讯作者：
Kasuya Y
中科院分区：
文献类型：
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作者：
Kobayashi T;Tanaka K;Fujita T;Umezawa H;Amano H;Yoshioka K;Naito Y;Hatano M;Kimura S;Tatsumi K;Kasuya Y
已知各种信号参与肺纤维化的发病机制。我们的目的是确定哪种信号在早期炎症阶段主要被动员，然后调节肺纤维化的发展。小鼠接受3 mg/kg体重的博来霉素（BLM）的单次剂量，并在滴注后（dpi）的指定天数处死。肺匀浆和切片小鼠在早期炎症阶段进行磷酸蛋白阵列分析和免疫荧光研究，分别。对小鼠支气管肺泡灌洗液（BALF）进行白细胞介素（IL）-6酶联免疫吸附测定（EIA）和浸润细胞群的评价。本实验观察了内源性和外源性IL-6对BLM诱导的A549细胞和2型肺细胞凋亡信号的影响。此外，评价了IL-6中和抗体对BLM诱导的肺损伤的作用。磷酸化蛋白阵列显示，BLM诱导肺中IL-6受体下游分子如Stat 3和Akt在3dpi时磷酸化。免疫荧光研究表明，在3 dpi，磷酸化Stat 3和Akt的信号定位于2型肺细胞，BLM诱导的IL-6样免疫反应主要在2型肺细胞中观察到。通过应用IL-6中和抗体、PI 3 K抑制剂或Stat 3抑制剂增强BLM处理的A549细胞和2型肺细胞中的半胱天冬酶的活化。EIA显示BLM诱导的BALF中的IL-6是双相的，第一次增加从0.5到3 dpi，然后第二次增加从8到10 dpi。IL-6中和抗体阻断IL-6的第一次增加可增强2型肺细胞的凋亡和嗜中性粒细胞浸润，并显著加速肺纤维化。相反，通过IL-6中和抗体阻断IL-6的第二次增加可改善肺纤维化。本研究表明IL-6在肺纤维化的发病机制中可能起双向作用。特别地，在BLM损伤的肺的早期炎症阶段IL-6的上调通过以自分泌/旁分泌方式调节2型肺细胞的细胞命运而具有抗纤维化活性。本文的在线版本（doi：10.1186/s12931-015-0261-z）包含补充材料，可供授权用户使用。
Various signals are known to participate in the pathogenesis of lung fibrosis. Our aim was to determine which signal is predominantly mobilized in the early inflammatory phase and thereafter modulates the development of lung fibrosis. Mice received a single dose of 3 mg/kg body weight of bleomycin (BLM) and were sacrificed at designated days post-instillation (dpi). Lung homogenates and sections from mice in the early inflammatory phase were subjected to phospho-protein array analysis and immunofluorescence studies, respectively. Bronchoalveolar lavage fluid (BALF) from mice was subjected to an enzyme-linked immunosorbent assay (EIA) for interleukin (IL)-6 and evaluation of infiltrated cell populations. The effects of endogenous and exogenous IL-6 on the BLM-induced apoptotic signal in A549 cells and type 2 pneumocytes were elucidated. In addition, the effect of IL-6-neutralizing antibody on BLM-induced lung injury was evaluated. Phospho-protein array revealed that BLM induced phosphorylation of molecules downstream of the IL-6 receptor such as Stat3 and Akt in the lung at 3 dpi. At 3 dpi, immunofluorescence studies showed that signals of phospho-Stat3 and -Akt were localized in type 2 pneumocytes, and that BLM-induced IL-6-like immunoreactivity was predominantly observed in type 2 pneumocytes. Activation of caspases in BLM-treated A549 cells and type 2 pneumocytes was augmented by application of IL-6-neutralizing antibody, a PI3K inhibitor or a Stat3 inhibitor. EIA revealed that BLM-induced IL-6 in BALF was biphasic, with the first increase from 0.5 to 3 dpi followed by the second increase from 8 to 10 dpi. Blockade of the first increase of IL-6 by IL-6-neutralizing antibody enhanced apoptosis of type 2 pneumocytes and neutrophilic infiltration and markedly accelerated fibrosis in the lung. In contrast, blockade of the second increase of IL-6 by IL-6-neutralizing antibody ameliorated lung fibrosis. The present study demonstrated that IL-6 could play a bidirectional role in the pathogenesis of lung fibrosis. In particular, upregulation of IL-6 at the early inflammatory stage of BLM-injured lung has antifibrotic activity through regulating the cell fate of type 2 pneumocytes in an autocrine/paracrine manner. The online version of this article (doi:10.1186/s12931-015-0261-z) contains supplementary material, which is available to authorized users.