Assini Julia M, Clark Justin R, Youssef Amer, Xing Chuce, Doerfler Alexandria M, Park So Hyun, Saxena Lavanya, Yaseen Adam B, Børen Jan, Gros Robert, Bao Gang, Lagor William R, Boffa Michael B, Koschinsky Marlys L
Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, London, Ontario, Canada.
Robarts Research Institute, Schulich School of Medicine & Dentistry, London, Ontario, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada.
Atherosclerosis. 2023 Nov;384:117150. doi: 10.1016/j.atherosclerosis.2023.05.019. Epub 2023 May 30.
Despite increased clinical interest in lipoprotein(a) (Lp(a)), many questions remain about the molecular mechanisms by which it contributes to atherosclerotic cardiovascular disease. Existing murine transgenic (Tg) Lp(a) models are limited by low plasma levels of Lp(a) and have not consistently shown a pro-atherosclerotic effect of Lp(a).
We generated Tg mice expressing both human apolipoprotein(a) (apo(a)) and human apoB-100, with pathogenic levels of plasma Lp(a) (range 87-250 mg/dL). Female and male Lp(a) Tg mice (Tg(LPA;APOB)) and human apoB-100-only controls (Tg(APOB)) (n = 10-13/group) were fed a high-fat, high-cholesterol diet for 12 weeks, with Ldlr knocked down using an antisense oligonucleotide. FPLC was used to characterize plasma lipoprotein profiles. Plaque area and necrotic core size were quantified and immunohistochemical assessment of lesions using a variety of cellular and protein markers was performed.
Male and female Tg(LPA;APOB) and Tg(APOB) mice exhibited proatherogenic lipoprotein profiles with increased cholesterol-rich VLDL and LDL-sized particles and no difference in plasma total cholesterol between genotypes. Complex lesions developed in the aortic sinus of all mice. Plaque area (+22%), necrotic core size (+25%), and calcified area (+65%) were all significantly increased in female Tg(LPA;APOB) mice compared to female Tg(APOB) mice. Immunohistochemistry of lesions demonstrated that apo(a) deposited in a similar pattern as apoB-100 in Tg(LPA;APOB) mice. Furthermore, female Tg(LPA;APOB) mice exhibited less organized collagen deposition as well as 42% higher staining for oxidized phospholipids (OxPL) compared to female Tg(APOB) mice. Tg(LPA;APOB) mice had dramatically higher levels of plasma OxPL-apo(a) and OxPL-apoB compared to Tg(APOB) mice, and female Tg(LPA;APOB) mice had higher plasma levels of the proinflammatory cytokine MCP-1 (+3.1-fold) compared to female Tg(APOB) mice.
These data suggest a pro-inflammatory phenotype exhibited by female Tg mice expressing Lp(a) that appears to contribute to the development of more severe lesions with greater vulnerable features.
尽管临床对脂蛋白(a)[Lp(a)]的关注度不断提高，但关于其促动脉粥样硬化性心血管疾病的分子机制仍存在诸多问题。现有的小鼠转基因（Tg）Lp(a)模型受限于血浆Lp(a)水平较低，且并未始终显示出Lp(a)的促动脉粥样硬化作用。
我们构建了同时表达人载脂蛋白(a)[apo(a)]和人apoB-100的Tg小鼠，其血浆Lp(a)水平处于致病范围（87 - 250mg/dL）。将雌性和雄性Lp(a)Tg小鼠[Tg(LPA;APOB)]和仅表达人apoB-100的对照小鼠[Tg(APOB)]（每组n = 10 - 13只）喂食高脂、高胆固醇饮食12周，同时使用反义寡核苷酸敲低Ldlr。采用快速蛋白液相色谱法（FPLC）来表征血浆脂蛋白谱。对斑块面积和坏死核心大小进行定量，并使用多种细胞和蛋白质标志物对病变进行免疫组织化学评估。
雄性和雌性Tg(LPA;APOB)小鼠和Tg(APOB)小鼠均呈现促动脉粥样硬化的脂蛋白谱，富含胆固醇的极低密度脂蛋白（VLDL）和低密度脂蛋白（LDL）大小的颗粒增加，且各基因型之间血浆总胆固醇无差异。所有小鼠的主动脉窦均出现复杂病变。与雌性Tg(APOB)小鼠相比，雌性Tg(LPA;APOB)小鼠的斑块面积（增加22%）、坏死核心大小（增加25%）和钙化面积（增加65%）均显著增加。病变的免疫组织化学显示，在Tg(LPA;APOB)小鼠中，apo(a)的沉积模式与apoB-100相似。此外，与雌性Tg(APOB)小鼠相比，雌性Tg(LPA;APOB)小鼠的胶原沉积组织化程度较低，氧化磷脂（OxPL）染色高42%。与Tg(APOB)小鼠相比，Tg(LPA;APOB)小鼠的血浆OxPL-apo(a)和OxPL-apoB水平显著更高，与雌性Tg(APOB)小鼠相比，雌性Tg(LPA;APOB)小鼠的促炎细胞因子单核细胞趋化蛋白-1（MCP-1）血浆水平更高（增加3.1倍）。
这些数据表明，表达Lp(a)的雌性Tg小鼠表现出促炎表型，这似乎有助于形成具有更高易损特征的更严重病变。
