谷氨酰胺缺乏将哮喘状态转变为中性粒细胞气道炎症
2021/10/20
摘要
背景：L-谷氨酰胺(Gln)通过快速上调MAPK磷酸酶(MKP)-1来抑制过敏性气道炎症，MKP-1通过使p38和JNK丝裂原活化蛋白激酶(MAPKs)失活而发挥炎症的负性调节作用。然而，内源性谷氨酰胺的作用仍有待阐明。
目的：探讨内源性谷氨酰胺(Gln)对卵清蛋白致敏的小鼠哮喘模型中MKP-1诱导和过敏性气道炎症的调节机制。
方法：采用谷氨酰胺转运蛋白ASCT2抑制剂L-γ-谷氨酰-对硝基苯胺 (GPNA)和谷氨酰胺合成酶小干扰siRNA降低内源性Gln水平。注射表达MKP-1的慢病毒以实现MKP-1的过表达。采用我们先前研发的基于卵清蛋白的小鼠模型评估哮喘表型，该模型适用于检查包括中性粒细胞浸润在内的一系列哮喘事件。采用 Gln 测定试剂盒分析 Gln 水平。
结果：GPNA或谷氨酰胺合成酶siRNA成功地耗尽了内源性Gln水平。重要的是，稳态的MKP-1诱导根本没有发生，这导致了谷氨酰胺缺陷小鼠中p38 MAPK和胞浆磷脂酶A2(cPLA2)磷酸化的延长。谷氨酰胺缺乏增强了所有检查的哮喘反应，但它表现出增加中性粒细胞计数的强烈倾向，这在MKP-1过表达的肺中未观察到。这种中性粒细胞增多受到 cPLA2抑制剂和白三烯B4抑制剂的抑制，但不受地塞米松的抑制。
结论：谷氨酰胺缺乏导致MKP-1诱导以及p38 MAPK 和 cPLA2激活受损，导致中性粒细胞的增加，比嗜酸性气道炎症更严重。
Glutamine deficiency shifts the asthmatic state toward neutrophilic airway inflammation
June-Mo Kim, Yoo Na Im, Yun-Jo Chung, Jung-Ho Youm, Suhn Young Im, Myung Kwan Han, Hern Ku Lee
Abstract
BACKGROUND:The administration of L-glutamine (Gln) suppresses allergic airway inflammation via the rapid upregulation of MAPK phosphatase (MKP)-1, which functions as a negative regulator of inflammation by deactivating p38 and JNK mitogen-activated protein kinases (MAPKs). However, the role of endogenous Gln remains to be elucidated.
OBJECTIVE:We investigated the mechanism by which endogenous Gln regulates MKP-1 induction and allergic airway inflammation in an ovalbumin-based murine asthma model.
METHODS:We depleted endogenous Gln levels using L-γ-glutamyl-p-nitroanilide (GPNA), an inhibitor of the Gln transporter ASCT2, and glutamine synthetase small interfering (si)RNA. Lentivirus expressing MKP-1 was injected to achieve overexpression of MKP-1. Asthmatic phenotypes were assessed using our previously developed ovalbumin-based murine model, which is suitable for examining sequential asthmatic events, including neutrophil infiltration. Gln levels were analyzed using a Gln assay kit.
RESULTS:GPNA or glutamine synthetase siRNA successfully depleted endogenous Gln levels. Importantly, homeostatic MKP-1 induction did not occur at all, which resulted in prolonged p38 MAPK and cytosolic phospholipase A2 (cPLA2 ) phosphorylation in Gln-deficient mice. Gln deficiency augmented all examined asthmatic reactions, but it exhibited a strong bias toward increasing the neutrophil count, which was not observed in MKP-1-overexpressing lungs. This neutrophilia was inhibited by a cPLA2 inhibitor and a leukotriene B4 inhibitor, but not by dexamethasone.
CONCLUSION:Gln deficiency leads to the impairment of MKP-1 induction and activation of p38 MAPK and cPLA2 , resulting in the augmentation of neutrophilic, more so than eosinophilic, airway inflammation.
背景：L-谷氨酰胺(Gln)通过快速上调MAPK磷酸酶(MKP)-1来抑制过敏性气道炎症，MKP-1通过使p38和JNK丝裂原活化蛋白激酶(MAPKs)失活而发挥炎症的负性调节作用。然而，内源性谷氨酰胺的作用仍有待阐明。
目的：探讨内源性谷氨酰胺(Gln)对卵清蛋白致敏的小鼠哮喘模型中MKP-1诱导和过敏性气道炎症的调节机制。
方法：采用谷氨酰胺转运蛋白ASCT2抑制剂L-γ-谷氨酰-对硝基苯胺 (GPNA)和谷氨酰胺合成酶小干扰siRNA降低内源性Gln水平。注射表达MKP-1的慢病毒以实现MKP-1的过表达。采用我们先前研发的基于卵清蛋白的小鼠模型评估哮喘表型，该模型适用于检查包括中性粒细胞浸润在内的一系列哮喘事件。采用 Gln 测定试剂盒分析 Gln 水平。
结果：GPNA或谷氨酰胺合成酶siRNA成功地耗尽了内源性Gln水平。重要的是，稳态的MKP-1诱导根本没有发生，这导致了谷氨酰胺缺陷小鼠中p38 MAPK和胞浆磷脂酶A2(cPLA2)磷酸化的延长。谷氨酰胺缺乏增强了所有检查的哮喘反应，但它表现出增加中性粒细胞计数的强烈倾向，这在MKP-1过表达的肺中未观察到。这种中性粒细胞增多受到 cPLA2抑制剂和白三烯B4抑制剂的抑制，但不受地塞米松的抑制。
结论：谷氨酰胺缺乏导致MKP-1诱导以及p38 MAPK 和 cPLA2激活受损，导致中性粒细胞的增加，比嗜酸性气道炎症更严重。
(中日友好医院呼吸与危重症医学科 王静茹 摘译 林江涛 审校)
(Allergy. 2021 Oct 3. doi: 10.1111/all.15121.)
(Allergy. 2021 Oct 3. doi: 10.1111/all.15121.)
Glutamine deficiency shifts the asthmatic state toward neutrophilic airway inflammation
June-Mo Kim, Yoo Na Im, Yun-Jo Chung, Jung-Ho Youm, Suhn Young Im, Myung Kwan Han, Hern Ku Lee
Abstract
BACKGROUND:The administration of L-glutamine (Gln) suppresses allergic airway inflammation via the rapid upregulation of MAPK phosphatase (MKP)-1, which functions as a negative regulator of inflammation by deactivating p38 and JNK mitogen-activated protein kinases (MAPKs). However, the role of endogenous Gln remains to be elucidated.
OBJECTIVE:We investigated the mechanism by which endogenous Gln regulates MKP-1 induction and allergic airway inflammation in an ovalbumin-based murine asthma model.
METHODS:We depleted endogenous Gln levels using L-γ-glutamyl-p-nitroanilide (GPNA), an inhibitor of the Gln transporter ASCT2, and glutamine synthetase small interfering (si)RNA. Lentivirus expressing MKP-1 was injected to achieve overexpression of MKP-1. Asthmatic phenotypes were assessed using our previously developed ovalbumin-based murine model, which is suitable for examining sequential asthmatic events, including neutrophil infiltration. Gln levels were analyzed using a Gln assay kit.
RESULTS:GPNA or glutamine synthetase siRNA successfully depleted endogenous Gln levels. Importantly, homeostatic MKP-1 induction did not occur at all, which resulted in prolonged p38 MAPK and cytosolic phospholipase A2 (cPLA2 ) phosphorylation in Gln-deficient mice. Gln deficiency augmented all examined asthmatic reactions, but it exhibited a strong bias toward increasing the neutrophil count, which was not observed in MKP-1-overexpressing lungs. This neutrophilia was inhibited by a cPLA2 inhibitor and a leukotriene B4 inhibitor, but not by dexamethasone.
CONCLUSION:Gln deficiency leads to the impairment of MKP-1 induction and activation of p38 MAPK and cPLA2 , resulting in the augmentation of neutrophilic, more so than eosinophilic, airway inflammation.
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哮喘发展中的细胞和全身能量代谢失调——一种假说生成方法
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