Cellular damage in mouse peritoneal macrophages exposed to cholesteryl linoleate

Reid, V.C.; Brabbs, Christine E.; Mitchinson, M. J.

doi:10.1016/0021-9150(92)90285-o

Cited by 29 publications

(10 citation statements)

References 20 publications

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“…Cells residing in the atheroma microenvironment encounter a myriad of stressors, putting them at increased risk of cell death. Stressors in the atheroma milieu include extracellular cholesterol and oxidized fatty acids, hypoxic conditions, rising ROS levels, and an array of inflammatory cytokines released by both activated ECs and macrophages 35–39 . The critical role VSMCs play in synthesis and subsequent maintenance of the barrier between these atheroma components and the circulation makes them an indispensible part of a stable plaque.…”

Section: Discussionmentioning

confidence: 99%

Identification of Small Proline-Rich Repeat Protein 3 as a Novel Atheroprotective Factor That Promotes Adaptive Akt Signaling in Vascular Smooth Muscle Cells

Segedy

Pyle

et al. 2014

ATVB

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Objective Atherosclerosis is the primary driver of cardiovascular disease, the leading cause of death worldwide. Identification of naturally occurring atheroprotective genes has become a major goal for development of interventions that will limit atheroma progression and associated adverse events. To this end, we have identified SPRR3 (small proline-rich repeat protein 3) as selectively upregulated in vascular smooth muscle cells (VSMCs) of atheroma-bearing arterial tissue versus healthy arterial tissue. In this study, we sought to determine the role of SPRR3 in atheroma pathophysiology. Approach and Results We found that atheroprone ApoE-null mice lacking SPRR3 developed significantly greater atheroma burden. To determine the cellular driver(s) of this increase, we evaluated SPRR3-dependent changes in bone-marrow-derived cells, endothelial cells (ECs), and VSMCs. Bone marrow transplant of SPRR3-expressing cells into SPRR3−/− ApoE−/− recipients failed to rescue atheroma burden. Similarly, ECs did not exhibit a response to SPRR3 loss. However, atheromas from SPRR3-deficient mice exhibited increased TUNEL-positive VSMCs compared with control. Cell death in SPRR3-deficient VSMCs was significantly increased in vitro. Conversely, SPRR3-overexpressing VSMCs exhibited reduced apoptosis compared with control. We also observed a PI3K/Akt-dependent positive association between SPRR3 expression and levels of active Akt in VSMCs. The survival advantage seen in SPRR3-overexpressing VSMCs was abrogated following the addition of a PI3K/Akt pathway inhibitor. Conclusions These results indicate that SPRR3 protects the lesion from VSMC loss by promoting survival signaling in plaque VSMCs, thereby significantly decreasing atherosclerosis progression. As the first identified atheroma-specific VSMC pro-survival factor, SPRR3 represents a potential target for lesion-specific modulation of VSMC survival.

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Section: Discussionmentioning

confidence: 99%

Identification of Small Proline-Rich Repeat Protein 3 as a Novel Atheroprotective Factor That Promotes Adaptive Akt Signaling in Vascular Smooth Muscle Cells

Segedy

Pyle

et al. 2014

ATVB

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“…The relative contributions of these components to the toxicity of LDL remain to be determined, but we already know that cholesteryl linoleate is toxic to MPM in vitro, whereas cholesteryl oleate is This is presumably because the former is oxidized by MPM, but the latter is not. 27 Cell-mediated oxidation of cholesteryl linoleate and copper and cell-mediated oxidation of LDL has been shown to produce 7~-hydroxycholesterol, which is also present in human atherosclerotic lesions. 28 We have recently shown that several different oxysterols, including 7~-hydroxycholesterol, are indeed toxic to HMM,2y but other potentially contributory components have not yet been tested.…”

Section: Discussionmentioning

confidence: 99%

Apoptosis in Human Monocyte-Macrophages Exposed to Oxidized Low Density Lipoprotein

et al. 1996

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This study has demonstrated the toxicity to human monocyte‐macrophages of low‐density lipoprotein (LDL) which had been artificially oxidized using copper sulphate. The assays of cell damage used were tritiated adenine release, neutral red staining, lactate dehydrogenase leakage, and MTT dye reduction. Toxicity was concentration‐ and time‐dependent. Exposure to native LDL under the same conditions did not result in toxicity. Transmission electron microscopy of cells exposed to oxidized LDL showed characteristic changes of apoptosis, including chromatin condensation and a decrease in cell volume. There was extensive loss of cell surface protrusions and evidence of the phagocytosis of apoptotic cells by neighbouring monocyte‐macrophages. Apoptotic features preceded the increased membrane permeability revealed by the release of radioactivity from cells preloaded with tritiated adenine and by lactate dehydrogenase leakage. DNA fragmentation was indicated by nick end‐labelling using the terminal transferase enzyme (TUNEL). The number of TUNEL‐positive cells was markedly greater in cells exposed to oxidized LDL, compared with those incubated as no‐additions controls. Inhibition of de novo protein synthesis with cycloheximide and of Ca2+/Mg2+‐activated endonuclease activity with aurintricarboxylic acid or zinc ion did not inhibit the toxicity produced by oxidized LDL.

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“…Thereafter, 100 μL of cold Trisbuffered saline was added to each column, and repeated cycles of centrifugation and addition of buffer were performed for a total of three buffer washes. Preliminary studies indicated that this procedure of three buffer application and centrifugation cycles did not elute HDL from the columns, and indeed no detectable radioactivity was found in the eluant obtained from media after an 8- Viability of Cells-The extent of adenine release as described by Reid et al 32 was used to assess membrane integrity. Radiolabeled adenine was incorporated into cellular pools by adding 0.5 μCi [ 3 H]adenine in MEM supplemented with 1% BSA and 1 μg compound 58035 per mL to Fu5AH cells 24 hours before efflux experiments (adenine release was monitored in plates run in parallel to cholesterol efflux experiments).…”

Section: Cholesterol Flux Studiesmentioning

confidence: 99%

Remodeling and Shuttling

Rodrigueza

Williams

Rothblat

et al. 1997

ATVB

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In normal physiology, cells are exposed to cholesterol acceptors of different sizes simultaneously. The current study examined the possible interactions between two different classes of acceptors, one large (large unilamellar phospholipid vesicles, LUVs) and one small (HDL or other small acceptors), added separately or in combination to Fu5AH rat hepatoma cells. During a 24-hour incubation, LUVs of palmitoyl-oleoyl phosphatidylcholine at 1 mg phospholipid (PL) per milliliter extracted ≈20% of cellular unesterified cholesterol (UC) label and mass in a slow, continuous fashion (half-time [t½] for UC efflux was ≈50 hours) and human HDL 3 at 25 μg PL per milliliter extracted ≈15% cellular UC label with no change in cellular cholesterol mass (t½ of ≈8 hours). In contrast, the combination of LUVs and HDL 3 extracted over 90% of UC label (t½ of ≈4 hours) and ≈50% of the UC mass, indicating synergy. To explain this synergy, specific particle interactions were examined, namely, remodeling, in which the two acceptors alter each other's composition and thus the ability to mobilize cellular cholesterol, and shuttling, in which the small acceptor ferries cholesterol from cells to the large acceptor. To examine remodeling, LUVs and HDL were coincubated and reisolated before application to cells. This HDL became UC depleted, PL enriched, and lost a small amount of apolipoprotein A-I. Compared with equivalent numbers of control HDL particles, remodeled HDL caused faster efflux (t½ ≈4 hours) and exhibited a greater capacity to sequester cellular cholesterol over 24 hours (≈38% versus ≈15% for control HDL), consistent with their enrichment in PL. Remodeled LUVs still extracted ≈20% of cellular UC. Thus, remodeling accounted for some but not all of the synergy between LUVs and HDL. To examine shuttling, several approaches were used. First, reisolation of particles after an 8-hour exposure to cells revealed that HDL contained very little of the cellular UC label. The label was found almost entirely with the LUVs, suggesting that LUVs continuously stripped the HDL of cellular UC. Second, bidirectional flux studies demonstrated that LUVs blocked the influx of HDL UC label into cells, while the rate of efflux of cellular UC was maintained. These kinetic effects explained the massive net loss of cellular UC to LUVs with HDL. Third, cyclodextrin, an artificial small acceptor that does not acquire PL and hence does not become remodeled, exhibitedCorrespondence to Dr Michael C. Phillips, Department of Biochemistry, Medical College of Pennsylvania and Hahnemann University, 2900 Queen Ln, Philadelphia, PA 19129. Portions of this work were published in abstract form in Abstracts Submitted to the Council on Arteriosclerosis for the 68th Scientific Sesssions of the American Heart Association. 1995:54. HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript substantial synergy with LUVs, supporting shuttling. Thus, the presence of large and small acceptors together can overcome intrinsic deficiencies in...

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Cellular damage in mouse peritoneal macrophages exposed to cholesteryl linoleate

Cited by 29 publications

References 20 publications

Identification of Small Proline-Rich Repeat Protein 3 as a Novel Atheroprotective Factor That Promotes Adaptive Akt Signaling in Vascular Smooth Muscle Cells

Identification of Small Proline-Rich Repeat Protein 3 as a Novel Atheroprotective Factor That Promotes Adaptive Akt Signaling in Vascular Smooth Muscle Cells

Apoptosis in Human Monocyte-Macrophages Exposed to Oxidized Low Density Lipoprotein

Remodeling and Shuttling

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