自噬增强缓解香烟烟雾引起的 CFTR 功能障碍、神经酰胺积累和 COPD 肺气肿发病机制。
Autophagy augmentation alleviates cigarette smoke-induced CFTR-dysfunction, ceramide-accumulation and COPD-emphysema pathogenesis.
机构信息
College of Medicine, Central Michigan University, Mt Pleasant, MI, USA.
Dept. of Molecular Biology, University of Duisburg-Essen, Germany and Dept. of Surgery, University of Cincinnati, OH, USA.
出版信息
Free Radic Biol Med. 2019 Feb 1;131:81-97. doi: 10.1016/j.freeradbiomed.2018.11.023. Epub 2018 Nov 28.
In this study, we aimed to investigate precise mechanism(s) of sphingolipid-imbalance and resulting ceramide-accumulation in COPD-emphysema. Where, human and murine emphysema lung tissues or human bronchial epithelial cells (Beas2b) were used for experimental analysis. We found that lungs of smokers and COPD-subjects with increasing emphysema severity demonstrate sphingolipid-imbalance, resulting in significant ceramide-accumulation and increased ceramide/sphingosine ratio, as compared to non-emphysema/non-smoker controls. Next, we found a substantial increase in emphysema chronicity-related ceramide-accumulation in murine (C57BL/6) lungs, while sphingosine levels only slightly increased. In accordance, the expression of the acid ceramidase decreased after CS-exposure. Moreover, CS-induced (sub-chronic) ceramide-accumulation was significantly (p < 0.05) reduced by treatment with TFEB/autophagy-inducing drug, gemfibrozil (GEM), suggesting that autophagy regulates CS-induced ceramide-accumulation. Next, we validated experimentally that autophagy/lipophagy-induction using an anti-oxidant, cysteamine, significantly (p < 0.05) reduces CS-extract (CSE)-mediated intracellular-ceramide-accumulation in p62 + aggresome-bodies. In addition to intracellular-accumulation, we found that CSE also induces membrane-ceramide-accumulation by ROS-dependent acid-sphingomyelinase (ASM) activation and plasma-membrane translocation, which was significantly controlled (p < 0.05) by cysteamine (an anti-oxidant) and amitriptyline (AMT, an inhibitor of ASM). Cysteamine-mediated and CSE-induced membrane-ceramide regulation was nullified by CFTR-inhibitor-172, demonstrating that CFTR controls redox impaired-autophagy dependent membrane-ceramide accumulation. In summary, our data shows that CS-mediated autophagy/lipophagy-dysfunction results in intracellular-ceramide-accumulation, while acquired CFTR-dysfunction-induced ASM causes membrane ceramide-accumulation. Thus, CS-exposure alters the sphingolipid-rheostat leading to the increased membrane- and intracellular- ceramide-accumulation inducing COPD-emphysema pathogenesis that is alleviated by treatment with cysteamine, a potent anti-oxidant with CFTR/autophagy-augmenting properties.
在这项研究中，我们旨在探究脂类失衡的精确机制和由此导致的 COPD 肺气肿中神经酰胺的积累。为此，我们使用了人或鼠的肺气肿肺组织或人支气管上皮细胞（Beas2b）进行了实验分析。我们发现，与非肺气肿/非吸烟者对照相比，吸烟者和 COPD 患者中肺气肿严重程度不断增加的患者的肺组织表现出脂类失衡，导致神经酰胺显著积累和神经酰胺/鞘氨醇比例增加。接下来，我们发现，在 C57BL/6 鼠的肺部中，与肺气肿慢性相关的神经酰胺积累显著增加，而鞘氨醇水平仅略有增加。相应地，在 CS 暴露后，酸性神经酰胺酶的表达下降。此外，CS 诱导的（亚慢性）神经酰胺积累通过用 TFEB/自噬诱导药物 gemfibrozil (GEM) 治疗显著降低（p < 0.05），表明自噬调节 CS 诱导的神经酰胺积累。接下来，我们通过实验验证了使用抗氧化剂半胱胺诱导自噬/脂自噬可显著降低 CSE 介导的 p62+ 聚集体内神经酰胺积累。除了细胞内积累，我们还发现 CSE 还通过 ROS 依赖性酸性鞘氨醇酶（ASM）激活和质膜转位诱导膜神经酰胺积累，半胱胺（抗氧化剂）和阿米替林（ASM 的抑制剂）可显著控制（p < 0.05）这一过程。CFTR 抑制剂 172 可消除半胱胺介导和 CSE 诱导的膜神经酰胺调节，表明 CFTR 控制氧化还原受损的自噬依赖性膜神经酰胺积累。综上所述，我们的数据表明，CS 介导的自噬/脂自噬功能障碍导致细胞内神经酰胺积累，而获得性 CFTR 功能障碍诱导的 ASM 导致膜神经酰胺积累。因此，CS 暴露改变了脂类调节机制，导致膜和细胞内神经酰胺积累增加，从而导致 COPD 肺气肿的发病机制，而用半胱胺治疗可缓解这一过程，半胱胺是一种具有 CFTR/自噬增强特性的有效抗氧化剂。
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