Host defense mechanism by pulmonary surfactant proteins A and D thiir clinical application

本研究旨在探讨肺表面活性蛋白SP-A和SP-D对宿主防御的分子机制，并探讨其临床应用价值。(1)将大鼠Thr174-Gly194的SP-A区替换为Thr164-Asp184的MBP- a区后，SP-A/MBP- a嵌合体失去了DPPC结合、Ca2+依赖性GalCer结合和与肺泡II型细胞相互作用的SP-A功能，但获得了结合PI的MBP活性。与SP-A区对应的合成肽与LPS和肽聚糖相互作用。(2) SP-A和SP-D分别与CD14的肽部分和寡糖部分相互作用。SP-A和SP-D改变了CD14与LPS的相互作用。(3)急性呼吸窘迫综合征患者BAL液中SP-A水平显著降低，SP-D水平无显著降低。未表现出低SP-A水平的高危ARDS患者未发生ARDS。(4)血清SP-A和SP-D的检测反映了胶原血管病患者的小而多的乳腺病变，这些病变是胸部CT可以检测到的，而平胸Xp无法检测到。(5)利用谷氨酰胺合成酶系统，以CHO-K1细胞和pEE14载体建立了重组SP-A和SP-D的规模化生产体系。(6)糖尿病大鼠BAL液中SP-A和SP-D含量升高，提示SP-A和SP-D作为急性相反应物起作用。(7)通过SP-A/SP-D嵌合体分析，确定了SP-A和SP-D与配体相互作用的羧基末端25个氨基酸。(8)检测SP-A在原发性肺腺癌患者骨髓中的表达。SP-A（免疫染色和mRNA）与细胞角蛋白的表达呈显著相关。骨髓SP-A阳性患者肿瘤纤维化、血管浸润评分高，C-F型Noguchi分型高，提示SP-A表达在肺腺癌微转移检测中的应用价值。少

The purpose of this study were to investigate the molecular mechanism of host defense by pulmonary surfactant proteins SP-A and SP-D and to establish the application for their clinical uses.(1) The SP-A/MBP-A chimera in which the rat SP-A region of Thr174-Gly194 was replaced with the MBP-A region of Thr164-Asp184 lost the SP-A functions of DPPC binding, Ca2+-dependent GalCer binding and interacting with alveolar type II cells but acquired the MBP activity of binding PI. The synthetic peptide corresponding to this SP-A region was used to interact with LPS and peptideglycans.(2) SP-A and SP-D interact with the peptide portion and the oligosaccharide moieties of CD14, respectively. SP-A and SP-D altered the interaction of CD14 with LPS.(3) The SP-A levels but not the SP-D levels significantly decreased in BAL fluids of patients with ARDS. The patients with ARDS at risk that did not exhibit low SP-A levels did not develop ARDS.(4) The detection of serum SP-A and SP-D reflected the small in … More terstitial pathological changes of patients with collagen vascular diseases that might be detected by chest CT but not by plain chest Xp.(5) The large scale production system of recombinant SP-A and SP-D was established by CHO-K1 cells and pEE14 vectors using glutamine synthetase system.(6) The contents of SP-A and SP-D increased in BAL fluids of rats with diabetes mellitus, suggesting that SP-A and SP-D function as acute phase reactants.(7) The carboxy terminal 25 amino acids have been identified to be essential for the interactions of SP-A and SP-D with their ligands by analysis with SP-A/SP-D chimeras.(8) The SP-A expression was examined in bone marrow of patients with primary lung adenocarcinomas. There were significant correlations between expressions of SP-A (immunostaining and mRNA) and cytokeratin. The patients with SP-A positive in bone marrow tend to show high scores of tumor fibrosis and of vessel invasion, and C-F types of Noguchi classification, suggesting the usefulness of SP-A expression to detect micrometastasis of lung adenocarcinomas. Less