Background-Atherosclerosis is a chronic inflammatory vascular disease driven by the subendothelial accumulation of macrophages. The mechanism regulating the inflammatory response in macrophages during atherogenesis remains unclear. Because microRNAs (miRNAs) play a crucial role in cellular signaling by posttranscriptional regulation of gene expression, we studied the miRNA expression profiles during the progression of atherosclerosis. Methods and Results-Using an miRNA real-time polymerase chain reaction array, we found that macrophage-derived miR-342-5p and miR-155 are selectively upregulated in early atherosclerotic lesions in Apoe −/− mice. miR-342-5p directly targets Akt1 through its 3ʹ-untranslated region. Akt1 suppression by miR-342-5p induces proinflammatory mediators such as Nos2 and II6 in macrophages via the upregulation of miR-155. The local application of an miR-342-5p antagomir inhibits the development of atherosclerosis in partially ligated carotid arteries. In atherosclerotic lesions, the miR-342-5p antagomir upregulated Akt1 expression and suppressed the expression of miR-155 and Nos2. This reduced Nos2 expression was associated with a diminished generation of nitrotyrosine in the plaques. Furthermore, systemic treatment with an inhibitor of miR-342-5p reduced the progression of atherosclerosis in the aorta of Apoe −/− mice. miR-223, miR-155, and miR-146a govern the proinflamma tory activation of macrophages by regulating the nuclear factor-κB signaling pathway. 9,15 The atherogenic stimulation of monocytes and macrophages by oxidized low-density lipoprotein also alters the miRNA expression profile, including the expression of miR-155 and miR-146a; this, in turn, affects lipid uptake and inflammatory cytokine secretion. 16 Moreover, inhibition of miR-33 causes an increase in reverse cholesterol transport, thereby reducing atherosclerosis and inflammatory gene expression. Conclusions-Macrophage-derived miR-342-5p 17Thus, miRNAs may be crucial for the regulation of inflammatory and lipid-handling functions in lesional macrophages. However, the miRNAs that control the inflammatory response during atherosclerosis have not been identified.In this study, we generated stage-specific miRNA expression profiles in atherosclerotic lesions from Apoe −/− mice. During early atherosclerosis, the most prominently upregulated miRNA was miR-342-5p, which is expressed in lesional macrophages. On proinflammatory activation in macrophages in vitro, miR-342-5p promoted Nos2 expression in an miR-155-dependent manner by targeting Akt1, an inhibitor of miR-155 expression. Accordingly, the inhibition of miR-342-5p reduced atherosclerotic lesion formation and suppressed Akt1-dependent Nos2 expression in lesional macrophages. Taken together, these data demonstrate a crucial role for miR-342-5p in the early inflammatory response in lesional macrophages. Methods Animal ModelsApoe −/− mice (age, 6-8 weeks; The Jackson Laboratory, Bar Harbor, ME) were fed a high-cholesterol diet (HCD; Altromin, Germany) comprising 21% crude ...

Meniere’s disease (MD), a syndromal inner ear disease, is commonly associated with a pathological accumulation of endolymphatic fluid in the inner ear, termed “idiopathic” endolymphatic hydrops (iEH). Although numerous precipitating/exacerbating factors have been proposed for MD, its etiology remains elusive. Here, using immunohistochemistry and in situ protein–protein interaction detection assays, we demonstrate mineralocorticoid-controlled sodium transport mechanisms in the epithelium of the extraosseous portion of the endolymphatic sac (eES) in the murine and human inner ears. Histological analysis of the eES in an extensive series of human temporal bones consistently revealed pathological changes in the eES in cases with iEH and a clinical history of MD, but no such changes were found in cases with “secondary” EH due to other otological diseases or in healthy controls. Notably, two etiologically different pathologies—degeneration and developmental hypoplasia—that selectively affect the eES in MD were distinguished. Clinical records from MD cases with degenerative and hypoplastic eES pathology revealed distinct intergroup differences in clinical disease presentation. Overall, we have identified for the first time two inner ear pathologies that are consistently present in MD and can be directly linked to the pathogenesis of EH, and which potentially affect the phenotypical presentation of MD. Electronic supplementary material The online version of this article (10.1007/s00401-018-1927-7) contains supplementary material, which is available to authorized users.

Objective— The function of microRNAs is highly context and cell type dependent because of their highly dynamic expression pattern and the regulation of multiple mRNA targets. MicroRNA-155 (miR-155) plays an important role in the innate immune response by regulating macrophage function; however, the effects of miR-155 in macrophages on atherosclerosis are controversial. We hypothesized that the stage-dependent target selection of miR-155 in macrophages determines its effects on atherosclerosis. Approach and Results— The expression of miR-155 increased in lesional macrophages of apolipoprotein E–deficient mice between 12 and 24 weeks of a high-cholesterol diet. Mir155 knockout in apolipoprotein E–deficient mice enhanced lesion formation, increased the lesional macrophage content, and promoted macrophage proliferation after 12 weeks of the high-cholesterol diet. In vitro, miR-155 inhibited macrophage proliferation by suppressing colony-stimulating factor-1 receptor, which was upregulated in lesional macrophages of Mir155 –/– apolipoprotein E–deficient mice. By contrast, Mir155 deficiency reduced necrotic core formation and the deposition of apoptotic cell debris, thereby preventing the progression of atherosclerosis between 12 and 24 weeks of the high-cholesterol diet. miR-155 inhibited efferocytosis in vitro by targeting B-cell leukemia/lymphoma 6 and thus activating RhoA (ras homolog gene family, member A). Accordingly, B-cell leukemia/lymphoma 6 was upregulated in lesional macrophages of Mir155 –/– apolipoprotein E–deficient mice after 24 weeks, but not after 12 weeks of the high-cholesterol diet. Conclusions— Our findings demonstrate a stage-specific role of miR-155 in lesion formation. miR-155 suppressed macrophage proliferation by targeting colony-stimulating factor-1 receptor in early and impaired efferocytosis by downregulating B-cell leukemia/lymphoma 6 in advanced atherosclerosis. Therefore, targeting the interaction between miR-155 and B-cell leukemia/lymphoma 6 may be a promising approach to inhibit the progression of atherosclerosis.

MicroRNAs regulate the maladaptation of endothelial cells (ECs) to naturally occurring disturbed blood flow at arterial bifurcations resulting in arterial inflammation and atherosclerosis in response to hyperlipidemic stress. Here, we show that reduced endothelial expression of the RNAse Dicer, which generates almost all mature miRNAs, decreases monocyte adhesion, endothelial C–X–C motif chemokine 1 (CXCL1) expression, atherosclerosis and the lesional macrophage content in apolipoprotein E knockout mice (Apoe−/−) after exposure to a high-fat diet. Endothelial Dicer deficiency reduces the expression of unstable miRNAs, such as miR-103, and promotes Krüppel-like factor 4 (KLF4)-dependent gene expression in murine atherosclerotic arteries. MiR-103 mediated suppression of KLF4 increases monocyte adhesion to ECs by enhancing nuclear factor-κB-dependent CXCL1 expression. Inhibiting the interaction between miR-103 and KLF4 reduces atherosclerosis, lesional macrophage accumulation and endothelial CXCL1 expression. Overall, our study suggests that Dicer promotes endothelial maladaptation and atherosclerosis in part by miR-103-mediated suppression of KLF4.