Department of Cardiology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, Germany.
Institute for Pharmacology, Universitätsmedizin Greifswald, Felix-Hausdorff-Strasse 3, Greifswald, Germany.
Cardiovasc Res. 2019 Feb 1;115(2):302-314. doi: 10.1093/cvr/cvy202.
The immune system is considered a key driver of atherosclerosis, and beyond proteins and microRNAs (miRs), long non-coding RNAs (lncRNAs) are implicated in immune control. We previously described that lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in cardiac innate immunity in a myocarditis model. Here, we investigated the impact of MALAT1 deficiency upon atherosclerosis development.
Heterozygous MALAT1-deficient ApoE-/- mice displayed massive immune system dysregulation and atherosclerosis within 2 months even when kept on normal diet. Aortic plaque area (P < 0.05) and aortic root plaque size (P < 0.001) were increased in MALAT1-deficient vs. MALAT1-wildtype ApoE-/- mice. Serum levels of interferon-γ (IFN-γ), tumour necrosis factor (TNF), and interleukin 6 (IL6) were elevated (P < 0.001) in MALAT1-deficient animals. MALAT1-deficient bone marrow-derived macrophages showed enhanced expression of TNF (P = 0.001) and inducible NO synthase (NOS2) (P = 0.002), suppressed MMP9 (P < 0.001), and impaired phagocytic activity (P < 0.001) upon lipopolysaccharide stimulation. RNA-sequencing revealed grossly altered transcriptomes of MALAT1-deficient splenocytes already at baseline, with massive induction of IFN- γ, TNF, NOS2, and granzyme B; CC and CXC chemokines and CCR8; and innate immunity genes interferon-induced protein with tetratricopeptide repeats (IFIT)1/3, interferon-induced transmembrane protein (IFITM)1/3, ISG15. Multiple miRs were up to 45-fold upregulated. Further, selective ablation of the cytosolic part of the MALAT1 system only, the enzymatically MALAT1-derived mascRNA, resulted in massive induction of TNF (P = 0.004) and IL6 (P = 0.028) in macrophages. Northern analysis of post-myocardial infarction patient vs. control peripheral blood mononuclear cells showed reduced (P = 0.005) mascRNA in the patients. CHART-enriched RNA-sequencing reads at the genomic loci of MALAT1 and neighbouring nuclear enriched abundant transcript (NEAT1) documented direct interaction between these lncRNA transcripts.
The data suggest a molecular circuit involving the MALAT1-mascRNA system, interactions between MALAT1 and NEAT1, and key immune effector molecules, cumulatively impacting upon the development of atherosclerosis. It appears reasonable to look for therapeutic targets in this circuit and to screen for anomalies in the NEAT1-MALAT1 region in humans, too, as possible novel disease risk factors.
免疫系统被认为是动脉粥样硬化的关键驱动因素，除了蛋白质和 microRNAs（miRs），长链非编码 RNA（lncRNAs）也与免疫控制有关。我们之前描述过，lncRNA 转移相关肺腺癌转录本 1（MALAT1）在心肌炎模型中的心脏先天免疫中发挥作用。在这里，我们研究了 MALAT1 缺乏对动脉粥样硬化发展的影响。
杂合子 MALAT1 缺陷型 ApoE-/- 小鼠即使在正常饮食下，也在 2 个月内出现严重的免疫系统失调和动脉粥样硬化。与 MALAT1 野生型 ApoE-/- 小鼠相比，MALAT1 缺陷型 ApoE-/- 小鼠的主动脉斑块面积（P<0.05）和主动脉根部斑块大小（P<0.001）增加。MALAT1 缺陷型动物的血清干扰素-γ（IFN-γ）、肿瘤坏死因子（TNF）和白细胞介素 6（IL6）水平升高（P<0.001）。MALAT1 缺陷型骨髓来源的巨噬细胞在脂多糖刺激下表现出 TNF（P=0.001）和诱导型一氧化氮合酶（NOS2）（P=0.002）的表达增强，基质金属蛋白酶 9（MMP9）（P<0.001）的表达抑制和吞噬活性受损（P<0.001）。RNA 测序显示 MALAT1 缺陷型脾细胞的转录组已经在基线时发生了明显改变，IFN-γ、TNF、NOS2 和颗粒酶 B；CC 和 CXC 趋化因子和 CCR8；以及先天免疫基因干扰素诱导的具有四肽重复的蛋白（IFIT）1/3、干扰素诱导的跨膜蛋白（IFITM）1/3、ISG15 大量诱导。多个 miRs 的表达上调了 45 倍以上。此外，仅选择性地消除 MALAT1 系统的细胞质部分，即酶衍生的 mascRNA，也会导致巨噬细胞中 TNF（P=0.004）和 IL6（P=0.028）的大量诱导。对心肌梗死后患者和对照组外周血单核细胞的 Northern 分析显示，患者的 mascRNA 减少（P=0.005）。MALAT1 和邻近核富集丰富转录物（NEAT1）基因组位点的 CHART 富集 RNA 测序读数记录了这些 lncRNA 转录本之间的直接相互作用。
数据表明，涉及 MALAT1-mascRNA 系统、MALAT1 和 NEAT1 之间相互作用以及关键免疫效应分子的分子回路，共同影响动脉粥样硬化的发展。在该回路中寻找治疗靶点，并在人类中筛选 NEAT1-MALAT1 区域的异常作为可能的新疾病风险因素，似乎是合理的。
