Targeted disruption of the gene encoding the murine small subunit of carboxypeptidase N (CPN1) causes susceptibility to C5a anaphylatoxin-mediated shock.
Targeted disruption of the gene encoding the murine small subunit of carboxypeptidase N (CPN1) causes susceptibility to C5a anaphylatoxin-mediated shock.
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DOI：
10.4049/jimmunol.0804207
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发表时间：
2009-05-15
期刊：
影响因子：
--
通讯作者：
Wetsel RA
中科院分区：
文献类型：
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作者：
Mueller-Ortiz SL;Wang D;Morales JE;Li L;Chang JY;Wetsel RA
羧肽酶N（Carboxypeptidase N，CPN）是一种血浆锌金属蛋白酶，由两个具有酶活性的小亚基（CPN 1）和两个保护蛋白质免于降解的大亚基（CPN 2）组成。从历史上看，CPN被认为是炎症的主要调节剂，其酶促裂解功能上重要的精氨酸和赖氨酸氨基酸从强效炎症分子，如补体过敏毒素C3 a和C5 a。由于没有已知的完全CPN缺陷，CPN在体内的生物学影响一直难以评价。在这里，我们报告了一个有针对性的破坏CPN 1基因的完全CPN缺乏症的小鼠一代。CPN 1 −/−小鼠由于眼镜蛇毒因子的急性补体激活而对致死性过敏性休克过敏。这种超敏反应在CPN 1 −/−/C5 aR −/−小鼠中完全消退，但在CPN 1 −/−/C3 aR −/−小鼠中未消退。此外，静脉注射C5 a的CPN 1 −/−小鼠，但C3 a没有，死亡率为100%。当CPN 1 −/−小鼠在C5 a激发前接受抗组胺药治疗时，C5 a诱导的死亡率降低至20%。这些研究首次描述了CPN的完全缺乏，并证明1）CPN在调节过敏毒素介导的休克的致死作用中起着必要的作用，2）这些致死作用主要由C5 a诱导的组胺释放介导，3）C3 a在急性补体激活后对休克无显著作用。
Carboxypeptidase N (CPN) is a plasma zinc metalloprotease, which consists of two enzymatically active small subunits (CPN1) and two large subunits (CPN2) that protect the protein from degradation. Historically, CPN has been implicated as a major regulator of inflammation by its enzymatic cleavage of functionally important arginine and lysine amino acids from potent phlogistic molecules, such as the complement anaphylatoxins C3a and C5a. Because of no known complete CPN deficiencies, the biological impact of CPN in vivo has been difficult to evaluate. Here, we report the generation of a mouse with complete CPN deficiency by targeted disruption of the CPN1 gene. CPN1−/− mice were hypersensitive to lethal anaphylactic shock due to acute complement activation by cobra venom factor. This hypersensitivity was completely resolved in CPN1−/−/C5aR−/− but not in CPN1−/−/C3aR−/− mice. Moreover, CPN1−/− mice given C5a i.v., but not C3a, experienced 100% mortality. This C5a-induced mortality was reduced to 20% when CPN1−/− mice were treated with an antihistamine before C5a challenge. These studies describe for the first time a complete deficiency of CPN and demonstrate 1) that CPN plays a requisite role in regulating the lethal effects of anaphylatoxin-mediated shock, 2) that these lethal effects are mediated predominantly by C5a-induced histamine release, and 3) that C3a does not contribute significantly to shock following acute complement activation.