Neutrophil serine proteinases inactivate surfactant protein D by cleaving within a conserved subregion of the carbohydrate recognition domain
Neutrophil serine proteinases inactivate surfactant protein D by cleaving within a conserved subregion of the carbohydrate recognition domain
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DOI：
10.1074/jbc.m402936200
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发表时间：
2004-06-25
影响因子：
4.8
通讯作者：
Belaaouaj, A
中科院分区：
文献类型：
--
作者：
Hirche, TO;Crouch, EC;Belaaouaj, A
表面活性蛋白 D (SP-D) 在先天免疫中发挥着重要作用，包括防御细菌、真菌和呼吸道病毒。由于 SP-D 与响应急性炎症和感染而浸润肺部的中性粒细胞特异性相互作用，因此我们检验了中性粒细胞来源的丝氨酸蛋白酶 (NSP)：中性粒细胞弹性蛋白酶、蛋白酶 3 和组织蛋白酶 G 降解 SP-D 的假设。所有三种人 NSP 以时间和剂量依赖性方式特异性切割重组大鼠和天然人 SP-D 十二聚体，这与钙浓度相互依赖。 NSP 产生相似的、相对稳定的二硫键交联的免疫反应片段，其大小类似于 35 kDa（还原的），并且对主要断裂片段进行测序，明确地将主要切割位点定位于碳水化合物识别结构域的高度保守的子区域。体外裂解显着降低了 SP-D 促进细菌聚集和与酵母甘露聚糖结合的能力。 SP-D 与分离的鼠中性粒细胞一起孵育会产生类似的片段，并且合成和天然丝氨酸蛋白酶抑制剂可抑制裂解。此外，遗传性缺乏中性粒细胞弹性蛋白酶和/或组织蛋白酶G的中性粒细胞降解SP-D的能力受损。使用急性细菌性肺炎小鼠模型，我们观察到 SP-D 在中性粒细胞浸润部位的积累，与支气管肺泡灌洗液中类似 35-kDa SP-D 片段的出现一致。总之，我们的数据表明，中性粒细胞衍生的丝氨酸蛋白酶在炎症部位裂解 SP-D，对其生物学功能具有潜在的有害影响。
Surfactant protein D (SP-D) plays important roles in innate immunity including the defense against bacteria, fungi, and respiratory viruses. Because SP-D specifically interacts with neutrophils that infiltrate the lung in response to acute inflammation and infection, we examined the hypothesis that the neutrophil-derived serine proteinases (NSPs): neutrophil elastase, proteinase-3, and cathepsin G degrade SP-D. All three human NSPs specifically cleaved recombinant rat and natural human SP-D dodecamers in a time- and dose-dependent manner, which was reciprocally dependent on calcium concentration. The NSPs generated similar, relatively stable, disulfide cross-linked immunoreactive fragments of similar to35 kDa ( reduced), and sequencing of a major catheptic fragment definitively localized the major sites of cleavage to a highly conserved subregion of the carbohydrate recognition domain. Cleavage markedly reduced the ability of SP-D to promote bacterial aggregation and to bind to yeast mannan in vitro. Incubation of SP-D with isolated murine neutrophils led to the generation of similar fragments, and cleavage was inhibited with synthetic and natural serine proteinase inhibitors. In addition, neutrophils genetically deficient in neutrophil elastase and/or cathepsin G were impaired in their ability to degrade SP-D. Using a mouse model of acute bacterial pneumonia, we observed the accumulation of SP-D at sites of neutrophil infiltration coinciding with the appearance of similar to35-kDa SP-D fragments in bronchoalveolar lavage fluids. Together, our data suggest that neutrophil-derived serine proteinases cleave SP-D at sites of inflammation with potential deleterious effects on its biological functions.