State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China.
Department of Animal Science, Texas A&M University, College Station, TX, USA.
Adv Exp Med Biol. 2020;1265:57-70. doi: 10.1007/978-3-030-45328-2_4.
Lung diseases affect millions of individuals all over the world. Various environmental factors, such as toxins, chemical pollutants, detergents, viruses, bacteria, microbial dysbiosis, and allergens, contribute to the development of respiratory disorders. Exposure to these factors activates stress responses in host cells and disrupt lung homeostasis, therefore leading to dysfunctional epithelial barriers. Despite significant advances in therapeutic treatments for lung diseases in the last two decades, novel interventional targets are imperative, considering the side effects and limited efficacy in patients treated with currently available drugs. Nutrients, such as amino acids (e.g., arginine, glutamine, glycine, proline, taurine, and tryptophan), peptides, and bioactive molecules, have attracted more and more attention due to their abilities to reduce oxidative stress, inhibit apoptosis, and regulate immune responses, thereby improving epithelial barriers. In this review, we summarize recent advances in amino acid metabolism in the lungs, as well as multifaceted functions of amino acids in attenuating inflammatory lung diseases based on data from studies with both human patients and animal models. The underlying mechanisms for the effects of physiological amino acids are likely complex and involve cell signaling, gene expression, and anti-oxidative reactions. The beneficial effects of amino acids are expected to improve the respiratory health and well-being of humans and other animals. Because viruses (e.g., coronavirus) and environmental pollutants (e.g., PM2.5 particles) induce severe damage to the lungs, it is important to determine whether dietary supplementation or intravenous administration of individual functional amino acids (e.g., arginine-HCl, citrulline, N-acetylcysteine, glutamine, glycine, proline and tryptophan) or their combinations to affected subjects may alleviate injury and dysfunction in this vital organ.
肺部疾病影响着全球数百万人。各种环境因素，如毒素、化学污染物、清洁剂、病毒、细菌、微生物失调和过敏原，导致了呼吸障碍的发生。这些因素会激活宿主细胞的应激反应，破坏肺部的内稳态，从而导致上皮屏障功能失调。尽管在过去二十年中，肺部疾病的治疗方法取得了重大进展，但考虑到现有药物治疗患者的副作用和疗效有限，仍需要寻找新的干预靶点。鉴于其减轻氧化应激、抑制细胞凋亡和调节免疫反应的能力，营养素（如氨基酸[如精氨酸、谷氨酰胺、甘氨酸、脯氨酸、牛磺酸和色氨酸]、肽和生物活性分子）越来越受到关注，能够改善上皮屏障。在这篇综述中，我们总结了近年来肺部氨基酸代谢的研究进展，以及基于人类患者和动物模型研究数据，氨基酸在减轻炎症性肺部疾病方面的多方面作用。生理氨基酸的作用机制可能很复杂，涉及细胞信号转导、基因表达和抗氧化反应。氨基酸的有益作用有望改善人类和其他动物的呼吸健康和幸福感。由于病毒（如冠状病毒）和环境污染物（如 PM2.5 颗粒）会对肺部造成严重损害，因此确定是否可以通过饮食补充或向受影响的个体静脉内给予单个功能性氨基酸（如盐酸精氨酸、瓜氨酸、N-乙酰半胱氨酸、谷氨酰胺、甘氨酸、脯氨酸和色氨酸）或它们的组合来减轻这个重要器官的损伤和功能障碍，这一点很重要。
