Production of C5a by ASP, a serine protease released from Aeromonas sobria
Production of C5a by ASP, a serine protease released from Aeromonas sobria
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DOI：
10.4049/jimmunol.181.5.3602
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发表时间：
2008-09-01
影响因子：
4.4
通讯作者：
Baba, Hideo
中科院分区：
文献类型：
--
作者：
Nitta, Hidetoshi;Imamura, Takahisa;Baba, Hideo
温和气单胞菌在感染部位引起脓和水肿。然而，这些影响的机制尚未阐明。补体第5组分（C5）的氨基末端片段C5a模拟这些事件。为了研究C5a在sobria感染病理生理中的作用，我们检测了C5a通过丝氨酸蛋白酶（ASP）从人C5中释放的情况，ASP是由sobria细菌分泌的一种假定的毒力因子。C5与具有酶活性的ASP一起孵育，在ASP浓度为3 nM时，以剂量依赖性的方式诱导中性粒细胞迁移，并以孵育时间依赖性的方式在短短7分钟内诱导豚鼠皮内注射部位的中性粒细胞积累和中性粒细胞超氧化物释放。这些对中性粒细胞的影响被c5a受体拮抗剂抑制。含C5而不含C3的ASP孵育液引起血管渗漏，并呈剂量和孵育时间依赖性，可被组胺h -1受体拮抗剂抑制。与这些C5a样活性一起，ASP裂解C5仅释放一个C5a Ag，其分子量与C5a相似。使用抗c5a抗体进行免疫印迹检测，发现在ASP作用下，人血浆中产生c5a样片段。这些结果表明，ASP在体内可能通过C5产生C5a而引起中性粒细胞迁移和血管渗漏，ASP不影响C5a和中性粒细胞C5a受体的功能。通过C5a的产生，ASP可能与该细菌感染引起的脓和水肿的诱导有关。
Aeromonas sobria causes pus and edema at sites of infection. However, the mechanisms underlying these effects have not been elucidated. C5a, the amino-terminal fragment of the complement 5th component (C5), mimics these events. To investigate the involvement of C5a in the pathophysiology of A. sobria infection, we examined release of C5a from human C5 by a serine protease (ASP), a putative virulence factor secreted by this bacterium. C5 incubated with enzymatically active ASP induced neutrophil migration in a dose-dependent manner from an ASP concentration of 3 nM and in an incubation time-dependent manner in as little as 7 min, with neutrophil accumulation in guinea pigs at intradermal injection sites and neutrophil superoxide release. These effects on neutrophils were inhibited by a C5a-receptor antagonist. The ASP incubation mixture with C5 but not C3 elicited vascular leakage in a dose- and incubation time-dependent manner, which was inhibited by a histamine H-1-receptor antagonist. Together with these C5a-like activities, ASP cleaved C5 to release only one C5a Ag, the m.w. of which was similar to that of C5a. Immunoblotting using an anti-C5a Ab revealed generation of a C5a-like fragment from human plasma incubated with ASP. These results suggest that ASP-elicited neutrophil migration and vascular leakage via C5a production from C5 could occur in vivo, which was supported by that ASP did not affect functions of C5a and neutrophil C5a receptor. Through C5a generation, ASP could be associated with the induction of pus and edema caused by infection with this bacterium.