Lai Jenn-Haung, Hung Li-Feng, Huang Chuan-Yueh, Wu De-Wei, Wu Chien-Hsiang, Ho Ling-Jun
Department of Rheumatology, Allergy and Immunology, Chang Gung Memorial Hospital, Lin-Kou, Tao-Yuan, Taiwan, Republic of China.
Graduate Institute of Clinical Research, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Arthritis Res Ther. 2021 Apr 19;23(1):120. doi: 10.1186/s13075-021-02470-6.
Premature atherosclerosis occurs in patients with SLE; however, the mechanisms remain unclear. Both mitochondrial machinery and proinflammatory cytokine interferon alpha (IFN-α) potentially contribute to atherogenic processes in SLE. Here, we explore the roles of the mitochondrial protein cytidine/uridine monophosphate kinase 2 (CMPK2) in IFN-α-mediated pro-atherogenic events.
Foam cell measurements were performed by oil red O staining, Dil-oxLDL uptake and the BODIPY approach. The mRNA and protein levels were measured by qPCR and Western blotting, respectively. Isolation of CD4+ T cells and monocytes was performed with monoclonal antibodies conjugated with microbeads. Manipulation of protein expression was conducted by either small interference RNA (siRNA) knockdown or CRISPR/Cas9 knockout. The expression of mitochondrial reactive oxygen species (mtROS) was determined by flow cytometry and confocal microscopy.
IFN-α enhanced oxLDL-induced foam cell formation and Dil-oxLDL uptake by macrophages. In addition to IFN-α, several triggers of atherosclerosis, including thrombin and IFN-γ, can induce CMPK2 expression, which was elevated in CD4+ T cells and CD14+ monocytes isolated from SLE patients compared to those isolated from controls. The analysis of cellular subfractions revealed that CMPK2 was present in both mitochondrial and cytosolic fractions. IFN-α-induced CMPK2 expression was inhibited by Janus kinase (JAK)1/2 and tyrosine kinase 2 (Tyk2) inhibitors. Both the knockdown and knockout of CMPK2 attenuated IFN-α-mediated foam cell formation, which involved the reduction of scavenger receptor class A (SR-A) expression. CMPK2 also regulated IFN-α-enhanced mtROS production and inflammasome activation.
The study suggests that CMPK2 plays contributing roles in the pro-atherogenic effects of IFN-α.
系统性红斑狼疮（SLE）患者会出现过早动脉粥样硬化，但机制尚不清楚。线粒体机制和促炎细胞因子干扰素α（IFN-α）都可能在SLE的动脉粥样硬化过程中发挥作用。在此，我们探讨线粒体蛋白胞苷/尿苷单磷酸激酶2（CMPK2）在IFN-α介导的促动脉粥样硬化事件中的作用。
通过油红O染色、Dil-oxLDL摄取和BODIPY方法进行泡沫细胞测量。分别通过qPCR和蛋白质印迹法测量mRNA和蛋白质水平。使用与微珠偶联的单克隆抗体分离CD4+T细胞和单核细胞。通过小干扰RNA（siRNA）敲低或CRISPR/Cas9敲除来操纵蛋白质表达。通过流式细胞术和共聚焦显微镜测定线粒体活性氧（mtROS）的表达。
IFN-α增强了氧化型低密度脂蛋白（oxLDL）诱导的巨噬细胞泡沫细胞形成和Dil-oxLDL摄取。除IFN-α外，动脉粥样硬化的几种触发因素，包括凝血酶和IFN-γ，均可诱导CMPK2表达，与从对照中分离的细胞相比，从SLE患者中分离的CD4+T细胞和CD14+单核细胞中CMPK2表达升高。细胞亚组分分析显示CMPK2存在于线粒体和细胞质组分中。IFN-α诱导的CMPK2表达受到Janus激酶（JAK）1/2和酪氨酸激酶2（Tyk2）抑制剂的抑制。CMPK2的敲低和敲除均减弱了IFN-α介导的泡沫细胞形成，这涉及清道夫受体A类（SR-A）表达的降低。CMPK2还调节IFN-α增强的mtROS产生和炎性小体激活。
该研究表明CMPK2在IFN-α的促动脉粥样硬化作用中起作用。
