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The NOD-like receptor family, pyrin domain-containing protein 3 (NLRP3) inflammasome plays an important role in the development of atherosclerosis. The activated NLRP3 inflammasome has been reported to promote macrophage foam cell formation, but not all studies have obtained the same result, and how NLRP3 inflammasome is involved in the formation of foam cells remains elusive. We used selective NLRP3 inflammasome inhibitors and NLRP3-deficient THP-1 cells to assess the effect of NLRP3 inflammasome inhibition on macrophage foam cell formation, oxidized low-density lipoprotein (ox-LDL) uptake, esterification, and cholesterol efflux, as well as the expression of associated proteins. Inhibition of the NLRP3 inflammasome attenuated foam cell formation, diminished ox-LDL uptake, and promoted cholesterol efflux from THP-1 macrophages. Moreover, it downregulated CD36, acyl coenzyme A: cholesterol acyltransferase-1 and neutral cholesterol ester hydrolase expression; upregulated ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) expression; but had no effect on the expression of scavenger receptor class A and ATP-binding cassette transporter G1. Collectively, our findings show that inhibition of the NLRP3 inflammasome decreases foam cell formation of THP-1 macrophages via suppression of ox-LDL uptake and enhancement of cholesterol efflux, which may be due to downregulation of CD36 expression and upregulation of ABCA1 and SR-BI expression, respectively., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Examines the function of mesangial cells on low-density lipoprotein receptor paradigm. Details on the cellular interactions in atherogenesis; Aspects of chronic fibroproliferative diseases; Pathogenesis of the atherosclerotic arteries.

Atherosclerosis is a chronic inflammatory cardiovascular disease with high mortality worldwide. Tofacitinib (CP-690,550), an oral small-molecule Janus kinase inhibitor, has been shown to be effective in the treatment of rheumatoid arthritis, autoimmune encephalomyelitis and ulcerative colitis. However, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of Tofacitinib on atherogenic diet (ATD)-induced atherosclerosis using apolipoprotein E deficient (apoE-/-) mice. Atherosclerosis-prone apoE-/- mice were fed with ATD and treated with or without Tofacitinib through intragastrical administration (10 mg kg -1 day -1 ) for 8 weeks. Our results showed that Tofacitinib did not change plasma lipids, while significantly reduced the levels of plasma pro-inflammatory cytokines IL-6 and TNF-α. It also significantly attenuated atherosclerotic plaque lesion in the aortic root and macrophages contained in plaque as shown with Mac2 immuno-staining. Peritoneal macrophages (PMC) were separated from apoE-/- mice fed with 8-week ATD, and then subjected to inflammation tests. Flow cytometry analysis of F4/80 and CD206 and mRNA levels of M1 and M2 macrophages markers showed that M1 macrophages decreased while M2 macrophages increased in Tofacitinib treated group. Expressions of other inflammatory genes also indicated an anti-inflammatory status in mice treated with Tofacitinib. Ox-LDL was used to induce foam cell formation from PMC in wild type mice, and the results displayed a reduced formation of foam cells and decreased inflammation in mice with Tofacitinib administration (1 μM). The mRNA and protein levels of ATP binding cassette subfamily A member 1 (ABCA1), a key gene involved in cholesterol efflux, remarkably increased, while it was absence of alterations in scavenger receptors expression. Therefore, we demonstrated that Tofacitinib could attenuate atherosclerosis and foam cells formation by inhibiting inflammation and upregulating ABCA1 expression., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The findings of this study suggest that the phosphoinositide phosphatase Sac3 maintains the protein level of scavenger receptor A (SR-A) and regulates foam cell formation. RAW264.7 macrophages were transfected with short hairpin RNAs that target Sac3. The knockdown decreased the level of the cell surface SR-A and suppressed the acetylated low density lipoprotein-induced foam cell formation. The associated regulator of PIKfyve (ArPIKfyve) is a scaffold protein that protects Sac3 from proteasome-dependent degradation. The knockdown of ArPIKfyve decreased Sac3, cell surface SR-A, and foam cell formation. The knockdown of PIKfyve had no effect on SR-A protein levels. These results suggest that the ArPIKfyve-Sac3 complex regulates SR-A protein levels independently of its effect on PIKfyve activity., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background and Aims: The enzyme histidine decarboxylase (Hdc), which generates histamine, is highly expressed in CD11b + Gr-1 + myeloid cells that play a critical role in infection, inflammation and tumorigenesis. The aim of this study was to explore the role of Hdc-expressing CD11b + myeloid cells or histamine in atherogenesis., Methods: Hdc-EGFP bacterial artificial chromosome (BAC) transgenic reporter mice (Hdc-EGFP) were used to track Hdc expression during the development of atherosclerosis. The expression of EGFP fluorescence was examined by immunofluorescence staining in a variety of adult tissues. Wild-type (WT), Apoe knockout (Apoe -/- ), Hdc knockout (Hdc -/- ), and Stat6 knockout (Stat6 -/- ) mice were used. Serum concentration of histamine was determined with ELISA. Changes in subsets of immune cells were evaluated by flow cytometry (FACS). Non-invasive tracking of the expression of CD11b + myeloid cells was tested using 125 I-anti-CD11b SPECT/CT imaging in the early stages of atherogenesis. Microarray analysis and RT-PCR were applied to detect gene expressions while Western blot was used to assess protein levels., Results: Using Hdc-EGFP transgenic mice, we demonstrated that Hdc + CD11b + myeloid cells increase in the circulation in response to hypercholesterolemia and contribute to foam cell formation in atherosclerosis. Histamine deficiency in Hdc knockout (Hdc -/- ) mice repressed the differentiation of CD11b + Ly6C high classically activated M1-type macrophages and CD11b + CD11c + dendritic cells (DCs), which was associated with downregulation of signal transducer and activator of transcription 6 (Stat6) expression. Furthermore, the results of in vivo and in vitro studies demonstrated that histamine could promote macrophage differentiation and foam cell formation via the Stat6 signal., Conclusions: Modulation of histamine and Stat6-signaling may represent an attractive therapeutic strategy for the prevention or treatment of atherosclerosis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In atherosclerosis, serum lipoproteins undergo various chemical modifications that impair their normal function. Modification of low density lipoprotein (LDL) such as oxidation, glycation, carbamylation, glucooxidation, etc. makes LDL particles more proatherogenic. Macrophages are responsible for clearance of modified LDL to prevent cytotoxicity, tissue injury, inflammation, and metabolic disturbances. They develop an advanced sensing arsenal composed of various pattern recognition receptors (PRRs) capable of recognizing and binding foreign or altered-self targets for further inactivation and degradation. Modified LDL can be sensed and taken up by macrophages with a battery of scavenger receptors (SRs), of which SR-A1, CD36, and LOX1 play a major role. However, in atherosclerosis, lipid balance is deregulated that induces inability of macrophages to completely recycle modified LDL and leads to lipid deposition and transformation of macrophages to foam cells. SRs also mediate various pathogenic effects of modified LDL on macrophages through activation of the intracellular signaling network. Other PRRs such Toll-like receptors can also interact with modified LDL and mediate their effects independently or in cooperation with SRs., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Pine (Pinus morrisonicola Hay, PM) needles have been used as folk medicine for their antihypertension and lipid-lowering effects. As supercritical fluid extraction (SFE) is considered an ideal technique for the extraction of essential oil from plant materials, the present work investigated the optimal SFE conditions and the protective effects of different resulting fractions of PM needles on lipid peroxidation and foam cell production in macrophages. Nine PM needle extracts (PME1-9) were obtained in 1%-4% yields using different SFE conditions, of which PME1 had the lowest yield (1.1%) and PME3 the highest (3.9%). PME3 exhibited lower cytotoxic effects and stronger inhibition of lipid peroxidation and formation of foam cell in RAW 264.7 macrophages than those of other PME extracts. PME3-1 purified from PME3 by column and thin layer chromatography inhibited LDL oxidation more effectively than did PME3 in a cell-free system oxidized by Cu(2+). PME3-1 dose-dependently (25-100 μg/mL) decreased conjugated diene levels and foam cell formation induced by ox-LDL. GC/MS analyses revealed that 1-docosene, neophytadiene, and methyl abietate were increased 5.2-, 1.7- and 4.3-fold in PME3-1 relative to PME3. A new hydrocarbon compound, cedrane-8,13-diol, was identified in PME3-1. Overall, the present study demonstrates the optimal extraction conditions of SFE of PM and identifies the most potent antioxidant fractions and possible active compounds in PM.

Atherosclerosis is the primary cause for cardiovascular disease. Here we identified a novel mechanism underlying atherosclerosis, which is provided by ARIA (apoptosis regulator through modulating IAP expression), the transmembrane protein that we recently identified. ARIA is expressed in macrophages present in human atherosclerotic plaque as well as in mouse peritoneal macrophages. When challenged with acetylated LDL, peritoneal macrophages isolated from ARIA-deficient mice showed substantially reduced foam cell formation, whereas the uptake did not differ from that in wild-type macrophages. Mechanistically, loss of ARIA enhanced PI3K/Akt signaling and consequently reduced the expression of acyl coenzyme A:cholesterol acyltransferase-1 (ACAT-1), an enzyme that esterifies cholesterol and promotes its storage, in macrophages. Inhibition of PI3K abolished the reduction in ACAT-1 expression and foam cell formation in ARIA-deficient macrophages. In contrast, overexpression of ARIA reduced Akt activity and enhanced foam cell formation in RAW264.7 macrophages, which was abrogated by treatment with ACAT inhibitor. Of note, genetic deletion of ARIA significantly reduced the atherosclerosis in ApoE-deficient mice. Oil red-O-positive lipid-rich lesion was reduced, which was accompanied by an increase of collagen fiber and decrease of necrotic core lesion in atherosclerotic plaque in ARIA/ApoE double-deficient mice. Analysis of bone marrow chimeric mice revealed that loss of ARIA in bone marrow cells was sufficient to reduce the atherosclerogenesis in ApoE-deficient mice. Together, we identified a unique role of ARIA in the pathogenesis of atherosclerosis at least partly by modulating macrophage foam cell formation. Our results indicate that ARIA could serve as a novel pharmacotherapeutic target for the treatment of atherosclerotic diseases., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)