Cardiovascular Biochemistry. Biomedical Research Institute Sant Pau (IIB-Sant Pau), Barcelona, Spain. C/Sant Quinti 77-79, 08041 Barcelona, Spain.
Molecular Biology and Biochemistry Department, Universitat Autònoma de Barcelona (UAB) Faculty of Medicine. Building M. Cerdanyola del Vallès, 08193 Barcelona, Spain.
Biomolecules. 2019 Jul 24;9(8):300. doi: 10.3390/biom9080300.
Electronegative low-density lipoprotein (LDL(-)) is a minor LDL subfraction that is present in blood with inflammatory and apoptotic effects. We aimed to evaluate the role of sphingolipids ceramide (Cer), sphingosine (Sph), and sphingosine-1-phosphate (S1P) in the LDL(-)-induced effect on monocytes. Total LDL was subfractioned into native LDL and LDL(-) by anion-exchange chromatography and their sphingolipid content evaluated by mass spectrometry. LDL subfractions were incubated with monocytes in the presence or absence of enzyme inhibitors: chlorpromazine (CPZ), d-erythro-2-(-myristoyl amino)-1-phenyl-1-propanol (MAPP), and ,-dimethylsphingosine (DMS), which inhibit Cer, Sph, and S1P generation, respectively. After incubation, we evaluated cytokine release by enzyme-linked immunosorbent assay (ELISA) and apoptosis by flow cytometry. LDL(-) had an increased content in Cer and Sph compared to LDL(+). LDL(-)-induced cytokine release from cultured monocytes was inhibited by CPZ and MAPP, whereas DMS had no effect. LDL(-) promoted monocyte apoptosis, which was inhibited by CPZ, but increased with the addition of DMS. LDL enriched with Sph increased cytokine release in monocytes, and when enriched with Cer, reproduced both the apoptotic and inflammatory effects of LDL(-). These observations indicate that Cer content contributes to the inflammatory and apoptotic effects of LDL(-) on monocytes, whereas Sph plays a more important role in LDL(-)-induced inflammation, and S1P counteracts apoptosis.
电负性低密度脂蛋白（LDL(-)）是一种存在于血液中的 LDL 亚组份，具有炎症和凋亡作用。我们旨在评估神经酰胺（Cer）、鞘氨醇（Sph）和鞘氨醇-1-磷酸（S1P）等鞘脂在 LDL(-)诱导单核细胞作用中的作用。通过阴离子交换色谱将总 LDL 分为天然 LDL 和 LDL(-)，并用质谱法评估其鞘脂含量。将 LDL 亚组份与单核细胞在酶抑制剂氯丙嗪（CPZ）、d-erythro-2-(-myristoyl amino)-1-phenyl-1-propanol（MAPP）和,-dimethylsphingosine（DMS）存在或不存在的情况下孵育，分别抑制 Cer、Sph 和 S1P 的生成。孵育后，通过酶联免疫吸附试验（ELISA）评估细胞因子释放，通过流式细胞术评估细胞凋亡。与 LDL(+)相比，LDL(-)中的 Cer 和 Sph 含量增加。CPZ 和 MAPP 抑制 LDL(-)诱导的培养单核细胞细胞因子释放，但 DMS 无影响。LDL(-)促进单核细胞凋亡，CPZ 抑制凋亡，但添加 DMS 则促进凋亡。富含 Sph 的 LDL 增加单核细胞细胞因子释放，富含 Cer 则重现 LDL(-)的促凋亡和促炎作用。这些观察结果表明，Cer 含量有助于 LDL(-)对单核细胞的炎症和凋亡作用，而 Sph 在 LDL(-)诱导的炎症中起更重要的作用，S1P 则拮抗凋亡。
