BackgroundExposure to second-hand tobacco smoke (SHS) is one of the prime risk factors for chronic lung disease development. Smoking during pregnancy may lead to birth defects in the newborn that include pulmonary dysfunction, increased susceptibility to opportunistic pathogens, or initiation of childhood respiratory manifestations such as bronchopulmonary dysplasia (BPD). Moreover, exposure to SHS in early childhood can have negative impact on lung health, although the exact mechanisms are unclear. Autophagy is a crucial proteostatic mechanism modulated by cigarette smoke (CS) in adult lungs. Here, we sought to investigate whether SHS exposure impairs autophagy in pediatric lungs.MethodsPregnant C57BL/6 mice were exposed to room air or SHS for 14 days. The newborn pups were subsequently exposed to room air or SHS (5 h/day) for 1 or 14 days, and lungs were harvested. Soluble and insoluble protein fractions isolated from pediatric mice lungs were subjected to immunoblotting for ubiquitin (Ub), p62, VCP, HIF-1α, and β-actin.ResultsOur data shows that short-term exposure to SHS (1 or 14 days) leads to proteostasis and autophagy-impairment as evident by significant increase in accumulation of ubiquitinated proteins (Ub), p62 (impaired-autophagy marker) and valosin-containing protein (VCP) in the insoluble protein fractions of pediatric mice lungs. Moreover, increased HIF-1α levels in SHS-exposed mice lungs points towards a novel mechanism for SHS-induced lung disease initiation in the pediatric population. Validating the in vivo studies, we demonstrate that treatment of human bronchial epithelial cells (Beas2b cells) with the proteasome inhibitor (MG-132) induces HIF-1α expression that is controlled by co-treatment with autophagy-inducing drug, cysteamine.ConclusionsSHS-exposure induced proteostasis/autophagy impairment can mediate the initiation of chronic lung disease in pediatric subjects. Hence, our data warrants the evaluation of proteostasis/autophagy-inducing drugs, such as cysteamine, as a potential therapeutic intervention strategy for SHS-induced pediatric lung diseases.

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二手烟 (SHS) 诱导的蛋白质稳态/自噬损伤在小儿肺部疾病中的作用

背景接触二手烟草烟雾 (SHS) 是慢性肺病发展的主要危险因素之一。怀孕期间吸烟可能导致新生儿出生缺陷，包括肺功能障碍、对机会性病原体的易感性增加，或开始出现儿童呼吸系统表现，如支气管肺发育不良 (BPD)。此外，尽管确切机制尚不清楚，但在儿童早期接触 SHS 会对肺部健康产生负面影响。自噬是由成人肺中的香烟烟雾 (CS) 调节的重要蛋白质稳态机制。在这里，我们试图调查 SHS 暴露是否会损害小儿肺部的自噬。方法将怀孕的 C57BL/6 小鼠暴露于室内空气或 SHS 中 14 天。随后将新生幼崽暴露于室内空气或 SHS（5 小时/天）中 1 或 14 天，和肺被收获。从小儿小鼠肺中分离出的可溶性和不溶性蛋白质组分进行了泛素 (Ub)、p62、VCP、HIF-1α 和 β-肌动蛋白的免疫印迹。结果我们的数据显示短期暴露于 SHS（1 或 14 天）导致对蛋白质稳态和自噬受损的影响，通过泛素化蛋白 (Ub)、p62（受损自噬标记物）和含 valosin 蛋白（VCP）在儿科小鼠肺的不溶性蛋白质组分中的积累显着增加是显而易见的。此外，暴露于 SHS 的小鼠肺中 HIF-1α 水平的增加表明 SHS 诱导的儿科人群肺部疾病发生的新机制。验证体内研究，我们证明用蛋白酶体抑制剂 (MG-132) 处理人支气管上皮细胞 (Beas2b 细胞) 诱导 HIF-1α 表达，该表达受自噬诱导药物半胱胺的共同治疗控制。可以介导儿科受试者慢性肺病的发生。因此，我们的数据保证了对蛋白质稳态/自噬诱导药物（如半胱胺）的评估，作为 SHS 诱导的小儿肺部疾病的潜在治疗干预策略。