Long non-coding RNAs (lncRNAs) are emerging regulators of pathophysiological processes including atherosclerosis. Using RNA-seq profiling of the intima of lesions, here we identify a macrophage-specific lncRNA MAARS (Macrophage-Associated Atherosclerosis lncRNA Sequence). Aortic intima expression of MAARS increases by 270-fold with atherosclerotic progression and decreases with regression by 60%. MAARS knockdown reduces atherosclerotic lesion formation by 52% in LDLR−/− mice, largely independent of effects on lipid profile and inflammation, but rather by decreasing macrophage apoptosis and increasing efferocytosis in the vessel wall. MAARS interacts with HuR/ELAVL1, an RNA-binding protein and important regulator of apoptosis. Overexpression and knockdown studies verified MAARS as a critical regulator of macrophage apoptosis and efferocytosis in vitro, in an HuR-dependent manner. Mechanistically, MAARS knockdown alters HuR cytosolic shuttling, regulating HuR targets such as p53, p27, Caspase-9, and BCL2. These findings establish a mechanism by which a macrophage-specific lncRNA interacting with HuR regulates apoptosis, with implications for a broad range of vascular disease states.
Objectives The marked cardiovascular risk in autoimmune diseases is only partly explained. The capacity of high-density lipoproteins (HDL) to promote cell cholesterol efflux is a property with a well-known anti-atherogenic significance, but is also involved in functional modulation of endothelial and immune cells. The aim of this work was to evaluate HDL functionality with respect to cell cholesterol efflux in rheumatoid arthritis (RA) and systemic lupus erythemathosus (SLE) patients. Methods We evaluated serum cholesterol efflux capacity (CEC) of apoB-depleted serum, which mainly reflects HDL activity, from 30 RA and 30 SLE patients, and from 30 healthy controls by radioisotopic ex-vivo systems discriminating between the specific pathways of cholesterol efflux. Results RA patients presented impairment of ATP-binding cassette G1-mediated CEC that correlated with disease activity. SLE patients showed a more complex pattern of modifications unrelated to disease activity, with marked reduction of ATP-binding cassette G1-mediated CEC and impairment of ATP-binding cassette A1-mediated CEC. The relationship between specific pathways of CEC values and serum total HDL differed between groups and there was no relationship with autoantibody profile or current therapy. Conclusions CEC is impaired in RA and SLE, with a specific mechanism pattern in each disease not depending on serum HDL levels. These findings provide a new mechanism for the increased atherosclerotic risk in RA and SLE patients.
1 December 2004 in Arteriosclerosis, Thrombosis, and Vascular Biology
Objective— ATP-binding cassette transporter A1 (ABCA1) mediates the efflux of lipids from cells to lipid-poor apolipoproteins. In this article, we characterize the effect of probucol on cellular ABCA1-mediated lipid efflux. Methods and Results— Probucol inhibited cholesterol efflux up to 80% in J774 macrophages expressing ABCA1. In Fu5AH hepatoma cells that contain scavenger receptor class B, type I, but not functional ABCA1, we observed no effect of probucol on cholesterol efflux. Probucol inhibited cholesterol efflux from normal human skin fibroblasts but not from fibroblasts from a Tangier patient. Fluorescent confocal microscopy and biotinylation assay demonstrated that in J774 cells probucol impaired the translocation of ABCA1 from intracellular compartments to the plasma membrane. Probucol also inhibited the formation of an ABCA1-linked cholesterol oxidase sensitive plasma membrane domain. Consistent with the inhibitory effect on ABCA1 translocation to the plasma membrane, probucol reduced cell surface–specific [ 125 I]-labeled apolipoprotein-AI binding. Conclusions— We conclude that probucol is an effective inhibitor of ABCA1-mediated cholesterol efflux without influencing scavenger receptor class B type I–mediated efflux. The inhibition of ABCA1 translocation to the plasma membrane may in part explain the reported in vivo high-density lipoprotein–lowering action of probucol.
Ear, nose and throat (ENT) involvement is common in Churg-Strauss syndrome (CSS), usually manifesting as allergic rhinitis and chronic rhinosinusitis with or without polyps. Otolaryngologists may play a pivotal role in making an early diagnosis of this disease. CSS is a systemic vasculitic disorder that affects small to medium-sized blood vessels. Although the cause of CSS remains unknown, tissue damage seems more likely to be mediated by activated eosinophils. Patients affected by CSS frequently have ENT manifestations, which are often present at the time of disease onset and may represent relevant clues for the diagnosis. Thus, our objective was to present the ENT manifestations at the onset, at the diagnosis and at some point during the course of the disease in a series of patients with CSS collected at a single center. Twenty-eight patients with CSS, as defined according to the 1990 American College of Rheumatology classification criteria, were identified. Twenty-one (75%) of these patients had ENT involvement. We evaluated the clinical course, laboratory data, histologic findings, treatment and outcomes. Of the 21 patients, 13 (61.9%) had ENT involvement at asthma onset and 8 (38%) at diagnosis or during follow-up. The most common ENT manifestations were allergic rhinitis in 9 (42.8%) patients and nasal polyposis in 16 (76.1%). Three (14.2%) patients developed chronic rhinosinusitis without polyps, three (14.2%) had nasal crusting, one (4.7%) serous otitis media, one (4.7%) purulent otitis media, two (9.5%) progressive sensorineural hearing loss, and one (4.7%) unilateral facial palsy. Corticosteroid therapy associated with immunosuppressive drugs usually yielded improvement or stabilization.