Involvement of ER stress in the molecular mechanisms of lung injury and pulmonary fibrosis

1.博来霉素诱导肺纤维化中的雌激素受体应激上皮细胞凋亡参与肺损伤和肺纤维化的病理生理过程。我们先前证明了在博来霉素处理的小鼠的肺组织中检测到多泛素化蛋白的积累。多泛素化蛋白的积累可能反映了泛素蛋白酶体途径的失调。已知未折叠和错误折叠蛋白的积累引起内质网（ER）应激和未折叠蛋白反应（UPR）。各种应激均可损伤蛋白质折叠，诱导内质网应激，严重的内质网应激可阻断细胞凋亡信号。目得：本研究旨在探讨雌激素受体应激和不饱和蛋白受体是否参与博莱霉素诱导的小鼠肺纤维化的病理生理过程。我们进行了蛋白质印迹分析和免疫组织化学，以评估ER驻留伴侣GRP78和ER应激相关凋亡因子CHOP的表达和激活， ...更多信息 博来霉素处理的小鼠肺组织中的半胱天冬酶-12。博莱霉素注射后7天CHOP表达增加，14天降至正常水平。Caspase-12在第14天上调并活化。caspase-12在肺泡上皮细胞的免疫反应性增加。GRP78表达在博莱霉素滴注后没有增加。这些结果提示，ER应激可能通过诱导上皮细胞凋亡参与了博莱霉素诱导的小鼠肺纤维化的病理生理过程。2.特发性肺纤维化中的ER应激上皮细胞凋亡被认为参与了特发性肺纤维化的病理生理过程。各种应激均可诱导内质网应激，从而导致细胞凋亡。我们研究了内质网应激与肺纤维化上皮细胞凋亡之间的关系。我们采用免疫印迹分析和免疫组织化学方法检测了8例特发性肺纤维化患者、6例非特异性间质性肺炎患者和8例对照者肺组织中内质网应激相关蛋白GRP78和CHOP的表达。ER应激特异性促凋亡分子CHOP和抗凋亡分子GRP78在肺纤维化肺组织中的表达较正常肺组织明显增加。免疫组化显示肺纤维化组肺上皮细胞GRP78和CHOP阳性信号增强。GRP78和CHOP的免疫反应分级与纤维化的严重程度相关。使用连续切片，一些CHOP阳性染色的细胞似乎对TUNEL染色呈阳性。虽然检查的患者数量很少，我们得出结论，ER应激介导的细胞凋亡，至少CHOP介导的上皮细胞凋亡途径，可能有助于肺纤维化的发展。少

1.ER stress in bleomycin-induced pulmonary fibrosisEpithelial cell apoptosis is involved in pathophysiology of lung injury and pulmonary fibrosis. We previously demonstrated that accumulation of mulit-ubiqitinated protein was detected in lung tissues of bleomycin-treated mice. The accumulation of multi-ubiquitinated protein may reflect the dysregulation of ubiquitin proteasome pathway. It is known that accumulation of unfolded and malfolded proteins causes endoplasmic reticulum(ER) stress and unfolded protein response(UPR). Various stresses can impair protein folding and induce ER stress, and severe ER stress can transduce apoptotic signals. PURPOSE : The purpose of this study is to investigate whether the ER stress and UPR are involoved in pathophysiology of bleomycin-induced pulmonary fibrosis in mice. We performed western blot analysis and immunohistochemistry to assess the expression and activation of ER-resident chaperones GRP78, and ER stress-associated apoptosis factor CHOP, and … More caspase-12 in lung tissue of bleomycin-treated mice. Expression of CHOP was increased at 7 days after bleomycin injection and reduced to normal levels at 14 days. Caspase-12 was upregurated and activated at day 14. The immunoreactivity for caspase-12 was increased in alveolar epithelial cells. GRP78 expression was not increased after bleomycin instillation. These results suggest that ER stress may be involved in the pathophysiology of bleomycin-induced pulmonary fibrosis in mice via induction of apoptosis epithelial cells.2.ER stress in idiopathic pulmonary fibrosisEpithelial cell apoptosis is considered to be involved in the pathophysiology of idiopathic pulmonary fibrosis. Various stresses can induce endoplasmic reticulum stress, which can lead to apoptosis. We investigated the association between endoplasmic reticulum stress and epithelial cell apoptosis in pulmonary fibrosis. We performed western blot analysis and immunohistochemistry to assess the expression ofendoplasmic reticulum stress-associated proteins GRP78 and CHOP in lung tissues from 8 patients with idiopathic pulmonary fibrosis, 6 patients with non-specific interstitial pneumonia, and 8 controls. The expressions of ER stress-specific proapoptotic molecule CHOP and an antiapoptotic molecule GRP78 were significantly increased in the lung tissues of pulmonary fibrosis compared with normal lung parenchyma. The positive signals for GRP78 and CHOP in epithelial cells were increased in pulmonary fibrosis by immunohistochemistry. The immunoreactive grade for GRP78 and CHOP were associated with the severity offibrosis. Some of positively stained cells for CHOP appeared to be positive for TUNEL staining using serial sections. Although the number of patients examined is small, we conclude that ER stress-mediated apoptosis, at least CHOP-mediated apoptosis pathway in epithelial cells, may contribute to the development of pulmonary fibrosis. Less