Microbial metalloproteinases mediate sensing of invading pathogens and activate innate immune responses in the lepidopteran model host Galleria mellonella
Microbial metalloproteinases mediate sensing of invading pathogens and activate innate immune responses in the lepidopteran model host Galleria mellonella
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DOI：
10.1128/iai.01385-06
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发表时间：
2007-01-01
影响因子：
3.1
通讯作者：
Vilcinskas, Andreas
中科院分区：
文献类型：
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作者：
Altincicek, Boran;Linder, Monica;Vilcinskas, Andreas
金溶素、假溶血素和杆菌溶血素等类金属蛋白酶代表了多种细菌病原体的毒力因子。最近，我们发现，向大蜡蛾幼虫体内注射热溶血素，可以介导强烈的免疫反应。热裂解素介导的血淋巴蛋白的蛋白分解产生了各种小尺寸(1；3 kDa)的蛋白片段(Protfrags)，它们是天然免疫反应的有力诱导者。在这项研究中，我们报道了丝氨酸蛋白酶的级联激活，就像细菌脂多糖(LPS)所描述的那样，导致随后的酚氧化酶原激活导致黑化，这是昆虫的一种基本免疫防御反应。免疫相关基因表达的实时定量逆转录-聚合酶链式反应分析显示，纯化的蛋白攻击后的转录速率与脂多糖攻击后的转录速率相似。此外，我们通过对未经处理的幼虫和受到Protfrags或LPS攻击的幼虫的血淋巴蛋白进行比较蛋白质组学分析，确定了分泌到血淋巴中的免疫反应蛋白的诱导作用。由于梅氏革兰氏菌是最近建立的一种有价值的新生隐球菌致病模型，本研究结果加深了我们对梅氏革兰氏菌免疫应答机制的理解。所获得的结果支持提出的危险模型，即免疫系统在感染过程中除了识别微生物模式分子外，还感知内源性警报信号。
Thermolysin-like metalloproteinases such as aureolysin, pseudolysin, and bacillolysin represent virulence factors of diverse bacterial pathogens. Recently, we discovered that injection of thermolysin into larvae of the greater wax moth, Galleria mellonella, mediated strong immune responses. Thermolysin-mediated proteolysis of hemolymph proteins yielded a variety of small-sized (< 3 kDa) protein fragments (protfrags) that are potent elicitors of innate immune responses. In this study, we report the activation of a serine proteinase cascade by thermolysin, as described for bacterial lipopolysaccharides (LPS), that results in subsequent prophenoloxidase activation leading to melanization, an elementary immune defense reaction of insects. Quantitative real-time reverse transcription-PCR analyses of the expression of immune-related genes encoding the inducible metalloproteinase inhibitor, gallerimycin, and lysozyme demonstrated increased transcriptional rates after challenge with purified protfrags similar to rates after challenge with LPS. Additionally, we determined the induction of a similar spectrum of immune-responsive proteins that were secreted into the hemolymph by using comparative proteomic analyses of hemolymph proteins from untreated larvae and from larvae that were challenged with either protfrags or LPS. Since G. mellonella was recently established as a valuable pathogenicity model for Cryptococcus neoformans infection, the present results add to our understanding of the mechanisms of immune responses in G. mellonella. The obtained results support the proposed danger model, which suggests that the immune system senses endogenous alarm signals during infection besides recognition of microbial pattern molecules.