BACKGROUND:Oxidized phospholipids play a key role in the atherogenic potential of lipoprotein(a) (Lp[a]); however, Lp(a) is a complex particle that warrants research into additional proinflammatory mediators. We hypothesized that additional Lp(a)-associated lipids contribute to the atherogenicity of Lp(a).METHODS:Untargeted lipidomics was performed on plasma and isolated lipoprotein fractions. The atherogenicity of the observed Lp(a)-associated lipids was tested ex vivo in primary human monocytes by RNA sequencing, ELISA, Western blot, and transendothelial migratory assays. Using immunofluorescence staining and single-cell RNA sequencing, the phenotype of macrophages was investigated in human atherosclerotic lesions.RESULTS:Compared with healthy individuals with low/normal Lp(a) levels (median, 7 mg/dL [18 nmol/L]; n=13), individuals with elevated Lp(a) levels (median, 87 mg/dL [218 nmol/L]; n=12) demonstrated an increase in lipid species, particularly diacylglycerols (DGs) and lysophosphatidic acid (LPA). DG and the LPA precursor lysophosphatidylcholine were enriched in the Lp(a) fraction. Ex vivo stimulation with DG(40:6) demonstrated a significant upregulation in proinflammatory pathways related to leukocyte migration, chemotaxis, NF-κB (nuclear factor kappa B) signaling, and cytokine production. Functional assessment showed a dose-dependent increase in the secretion of IL (interleukin)-6, IL-8, and IL-1β after DG(40:6) and DG(38:4) stimulation, which was, in part, mediated via the NLRP3 (NOD [nucleotide-binding oligomerization domain]-like receptor family pyrin domain containing 3) inflammasome. Conversely, LPA-stimulated monocytes did not exhibit an inflammatory phenotype. Furthermore, activation of monocytes by DGs and LPA increased their transendothelial migratory capacity. Human atherosclerotic plaques from patients with high Lp(a) levels demonstrated colocalization of Lp(a) with M1 macrophages, and an enrichment of CD68⁺IL-18⁺TLR4⁺ (toll-like receptor) TREM2⁺ (triggering receptor expressed on myeloid cells) resident macrophages and CD68⁺CASP1⁺ (caspase) IL-1B⁺SELL⁺ (selectin L) inflammatory macrophages compared with patients with low Lp(a). Finally, potent Lp(a)-lowering treatment (pelacarsen) resulted in a reduction in specific circulating DG lipid subspecies in patients with cardiovascular disease with elevated Lp(a) levels (median, 82 mg/dL [205 nmol/L]).CONCLUSIONS:Lp(a)-associated DGs and LPA have a potential role in Lp(a)-induced monocyte inflammation by increasing cytokine secretion and monocyte transendothelial migration. This DG-induced inflammation is, in part, NLRP3 inflammasome dependent.

中文翻译：

---

富含脂蛋白 (a) 的二酰甘油和溶血磷脂酸会导致单核细胞炎症

背景：氧化磷脂在脂蛋白(a) (Lp[a]) 的致动脉粥样硬化潜力中发挥关键作用；然而，Lp(a) 是一种复杂的颗粒，值得研究其他促炎介质。我们假设额外的 Lp(a) 相关脂质会导致 Lp(a) 的致动脉粥样硬化性。方法：对血浆和分离的脂蛋白组分进行非靶向脂质组学。通过 RNA 测序、ELISA、Western blot 和跨内皮迁移测定，在原代人单核细胞中离体测试了观察到的 Lp(a) 相关脂质的致动脉粥样硬化性。使用免疫荧光染色和单细胞 RNA 测序，研究了人类动脉粥样硬化病变中巨噬细胞的表型。 结果：与 Lp(a) 水平低/正常的健康个体相比（中位数为 7 mg/dL [18 nmol/L]； n=13)，Lp(a) 水平升高（中位值 87 mg/dL [218 nmol/L]；n=12）的个体表现出脂质种类增加，特别是二酰甘油 (DG) 和溶血磷脂酸 (LPA)。DG 和 LPA 前体溶血磷脂酰胆碱在 Lp(a) 组分中富集。DG(40:6) 的离体刺激表明与白细胞迁移、趋化性、NF-κB（核因子 kappa B）信号传导和细胞因子产生相关的促炎途径显着上调。功能评估显示，DG(40:6) 和 DG(38:4) 刺激后，IL（白细胞介素）-6、IL-8 和 IL-1β 的分泌呈剂量依赖性增加，这在一定程度上是由通过 NLRP3（NOD [核苷酸结合寡聚化结构域]样受体家族，含有 3 个吡啶结构域）炎症小体。相反，LPA刺激的单核细胞没有表现出炎症表型。此外，DG 和 LPA 对单核细胞的激活增加了它们的跨内皮迁移能力。来自 Lp(a) 水平高的患者的人动脉粥样硬化斑块显示 Lp(a) 与 M1 巨噬细胞共定位，并且 CD68 ⁺ IL-18 ⁺ TLR4 ⁺（Toll 样受体）TREM2 ⁺（骨髓细胞上表达的触发受体）富集)与低 Lp(a) 患者相比，常驻巨噬细胞和 CD68 ⁺ CASP1 ⁺ (半胱天冬酶) IL-1B ⁺ SELL ^{+ (选择素 L) 炎症巨噬细胞。}最后，有效的 Lp(a) 降低治疗 (pelacarsen) 导致 Lp(a) 水平升高（中位值 82 mg/dL [205 nmol/L]）的心血管疾病患者的特定循环 DG 脂质亚种减少。结论：Lp(a) 相关的 DG 和 LPA 通过增加细胞因子分泌和单核细胞跨内皮迁移，在 Lp(a) 诱导的单核细胞炎症中发挥潜在作用。这种 DG 诱导的炎症部分依赖于 NLRP3 炎性体。