Increased sphingomyelin content impairs HDL biogenesis and maturation in human Niemann-Pick disease type B
Increased sphingomyelin content impairs HDL biogenesis and maturation in human Niemann-Pick disease type B
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DOI：
10.1194/jlr.m500487-jlr200
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发表时间：
2006-03-01
影响因子：
6.5
通讯作者：
Marcil, M
中科院分区：
文献类型：
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作者：
Lee, CY;Lesimple, A;Marcil, M
我们之前报道过人类 B 型尼曼匹克病 (NPD-B) 与低 HDL 相关。在这项研究中，我们通过检查 NPD-B 患者的 HDL 样本和通过无脂载脂蛋白 A-I (apoA-I) 与 NPD-B 成纤维细胞孵育产生的新生高密度脂蛋白 (LpA-I) 来研究这种 HDL 缺乏的病理生理学。有趣的是，从患者血浆中分离的 LpA-I 和 HDL 的鞘磷脂 (SM) 质量显着增加（接近 50-100%）。 LCAT 动力学参数（V-max 和 Km）分析表明，LpA-I 或来自 NPD-B 的血浆 HDL，以及富含 SM 的重构 HDL，表现出 LCAT 介导的胆固醇酯化严重降低。重要的是，我们记录了 NPD-B LpA-I 的 SM 富集并不归因于 SM 或未酯化胆固醇向无脂 apoA-I 的细胞传质增加。最后，我们获得证据表明，来自 HUVEC、THP-1 和正常成纤维细胞（但不包括 NPD-B 成纤维细胞）的条件培养基含有活性分泌型鞘磷脂酶 (S-SMase)，可介导 [H-3] SM 标记的 LpA-I 和 HDL3 的水解。此外，突变体 SMase (Delta R608) 在 CHO 细胞中的表达表明 DR608 合成正常，但分泌和活性有缺陷。我们的数据表明，NPD 中的 S-SMase 缺陷会导致 HDL 的 SM 富集，从而损害 LCAT 介导的新生 HDL 成熟并导致 HDL 缺乏。因此，S-SMase 和 LCAT 可能协同作用，并在新生 HDL 颗粒的生物发生和成熟中发挥至关重要的作用。
We previously reported that human Niemann-Pick Disease type B (NPD-B) is associated with low HDL. In this study, we investigated the pathophysiology of this HDL deficiency by examining both HDL samples from NPD-B patients and nascent high density lipoprotein (LpA-I) generated by incubation of lipid-free apolipoprotein A-I (apoA-I) with NPD-B fibroblasts. Interestingly, both LpA-I and HDL isolated from patient plasma had a significant increase in sphingomyelin (SM) mass (similar to 50-100%). Analysis of LCAT kinetics parameters (V-max and Km) revealed that either LpA-I or plasma HDL from NPD-B, as well as reconstituted HDL enriched with SM, exhibited severely decreased LCAT-mediated cholesterol esterification. Importantly, we documented that SM enrichment of NPD-B LpA-I was not attributable to increased cellular mass transfer of SM or unesterified cholesterol to lipid-free apoA-I. Finally, we obtained evidence that the conditioned medium from HUVEC, THP-1, and normal fibroblasts, but not NPD-B fibroblasts, contained active secretory sphingomyelinase (S-SMase) that mediated the hydrolysis of [H-3] SM-labeled LpA-I and HDL3. Furthermore, expression of mutant SMase (Delta R608) in CHO cells revealed that DR608 was synthesized normally but had defective secretion and activity. Our data suggest that defective S-SMase in NPD leads to SM enrichment of HDL that impairs LCAT-mediated nascent HDL maturation and contributes to HDL deficiency. Thus, S-SMase and LCAT may act in concert and play a crucial role in the biogenesis and maturation of nascent HDL particles.