Background

Surfactant proteins (SP) A and D belong to collectin family proteins, which play important roles in innate immune response in the lung. We previously demonstrated that cigarette smoke (CS) increases the acrolein modification of SP-A, thereby impairing the innate immune abilities of this protein. In this study, we focused on the effects of CS and its component, acrolein, on the innate immunity role of another collectin, SP-D.

Methods

To determine whether aldehyde directly affects SP-D, we examined the lungs of mice exposed to CS for 1 week and detected aldehyde-modified SP-D using an aldehyde reactive probe. The structural changes in CS extract (CSE) or acrolein-exposed recombinant human (h)SP-D were determined by western blot, liquid chromatography-electrospray ionization tandem mass spectrometry, and blue native-polyacrylamide gel electrophoresis analyses. Innate immune functions of SP-D were determined by bacteria growth and macrophage phagocytosis.

Results

Aldehyde-modified SP-D as well as SP-A was detected in the lungs of mice exposed to CS for 1 week. Exposure of hSP-D to CSE or acrolein induced an increased higher-molecular -weight of hSP-D and acrolein induced modification of five lysine residues in hSP-D. These modifications led to disruption of the multimer structure of SP-D and attenuated its ability to inhibit bacterial growth and activate macrophage phagocytosis.

Conclusion

CS induced acrolein modification in SP-D, which in turn induced structural and functional defects in SP-D.

General Significance

These results suggest that CS-induced structural and functional defects in SP-D contribute to the dysfunction of innate immune responses in the lung following CS exposure.

中文翻译：

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香烟烟雾中的丙烯醛会减弱表面活性蛋白 D 介导的先天免疫反应。

 背景

表面活性蛋白 (SP) A 和 D 属于集合素家族蛋白，在肺部先天免疫反应中发挥重要作用。我们之前证明，香烟烟雾（CS）会增加 SP-A 的丙烯醛修饰，从而损害该蛋白质的先天免疫能力。在这项研究中，我们重点研究了 CS 及其成分丙烯醛对另一种集合素 SP-D 的先天免疫作用的影响。

 方法

为了确定醛是否直接影响 SP-D，我们检查了暴露于 CS 1 周的小鼠的肺部，并使用醛反应探针检测了醛修饰的 SP-D。通过蛋白质印迹、液相色谱-电喷雾电离串联质谱法和蓝色天然聚丙烯酰胺凝胶电泳分析来确定 CS 提取物 (CSE) 或暴露于丙烯醛的重组人 (h)SP-D 的结构变化。 SP-D 的先天免疫功能由细菌生长和巨噬细胞吞噬作用决定。

 结果

在暴露于 CS 1 周的小鼠的肺部中检测到醛修饰的 SP-D 和 SP-A。 hSP-D暴露于CSE或丙烯醛诱导hSP-D的较高分子量增加，并且丙烯醛诱导hSP-D中五个赖氨酸残基的修饰。这些修饰导致 SP-D 多聚体结构的破坏，并削弱了其抑制细菌生长和激活巨噬细胞吞噬作用的能力。

 结论

CS诱导SP-D中的丙烯醛修饰，进而诱导SP-D中的结构和功能缺陷。

 一般意义

这些结果表明，CS 诱导的 SP-D 结构和功能缺陷导致 CS 暴露后肺部先天免疫反应功能障碍。