Wasylnka J A, Moore M M
Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
Infect Immun. 2000 Jun;68(6):3377-84. doi: 10.1128/IAI.68.6.3377-3384.2000.
Invasive lung disease caused by Aspergillus species is a potentially fatal infection in immunocompromised patients. The adhesion of Aspergillus fumigatus conidia to proteins in the basal lamina is thought to be an initial step in the development of invasive aspergillosis. The purpose of this study was to determine the mechanism of adhesion of A. fumigatus conidiospores to basal-lamina proteins and to determine whether conidia possess unique adhesins which allow them to colonize the host. We compared conidia from different Aspergillus species for the ability to bind to purified fibronectin and intact basal lamina. Adhesion assays using immobilized fibronectin or type II pneumocyte-derived basal lamina showed that A. fumigatus conidia bound significantly better than those of other Aspergillus species to both fibronectin and intact basal lamina. Neither desialylation nor complete deglycosylation of fibronectin decreased the binding of A. fumigatus conidia to fibronectin, suggesting that oligosaccharides on fibronectin were not involved in conidiospore binding. Further evidence for this hypothesis came from experiments using purified fragments of fibronectin; A. fumigatus conidia preferentially bound to the nonglycosylated 40-kDa fragment which contains the glycosaminoglycan (GAG) binding domain. Negatively charged carbohydrates, including dextran sulfate and heparin, as well as high-ionic-strength buffers, inhibited binding of A. fumigatus conidia to both fibronectin and intact basal lamina, suggesting that negatively charged carbohydrates on the surface of the conidium may bind to the GAG binding domain of fibronectin and other basal-lamina proteins. These data provide evidence for a novel mechanism of conidial attachment whereby adherence to fibronectin and other basal-lamina proteins is mediated via negatively charged carbohydrates on the conidial surface.
曲霉菌种引起的侵袭性肺部疾病在免疫功能低下的患者中是一种潜在的致命感染。烟曲霉分生孢子与基膜中的蛋白质粘附被认为是侵袭性曲霉病发展的初始步骤。本研究的目的是确定烟曲霉分生孢子与基膜蛋白的粘附机制，并确定分生孢子是否具有使其能够在宿主体内定殖的独特粘附素。我们比较了不同曲霉菌种的分生孢子与纯化的纤连蛋白和完整基膜的结合能力。使用固定化纤连蛋白或II型肺细胞衍生的基膜进行的粘附试验表明，烟曲霉分生孢子与纤连蛋白和完整基膜的结合明显优于其他曲霉菌种。纤连蛋白的去唾液酸化或完全去糖基化均未降低烟曲霉分生孢子与纤连蛋白的结合，这表明纤连蛋白上的寡糖不参与分生孢子的结合。这一假设的进一步证据来自使用纤连蛋白纯化片段的实验；烟曲霉分生孢子优先与包含糖胺聚糖（GAG）结合域的非糖基化40 kDa片段结合。带负电荷的碳水化合物，包括硫酸葡聚糖和肝素，以及高离子强度缓冲液，均抑制烟曲霉分生孢子与纤连蛋白和完整基膜的结合，这表明分生孢子表面带负电荷的碳水化合物可能与纤连蛋白和其他基膜蛋白的GAG结合域结合。这些数据为分生孢子附着的新机制提供了证据，即通过分生孢子表面带负电荷的碳水化合物介导与纤连蛋白和其他基膜蛋白的粘附。
