Cholesterol Efflux Assay Kit ab196985 is a high-throughput, cell-based screening assay for measuring cholesterol efflux.
Individual kit components also available for purchase with a minimum order of 20 units. Contact us to discuss your needs.
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Cholesterol Efflux Assay Kit ab196985 is a high-throughput, cell-based screening assay for measuring cholesterol efflux.
Individual kit components also available for purchase with a minimum order of 20 units. Contact us to discuss your needs.
Cholesterol Efflux Assay Kit ab196985 is a high-throughput, cell-based screening assay for measuring cholesterol efflux capacity. The cholesterol efflux assay protocol uses fluorescently-labeled cholesterol (Ex/Em 485/523 nm).
It provides a safe, sensitive and reproducible method for measuring cholesterol efflux, avoiding the disadvantages of handling radioactive materials with the alternative commonly used triatiated cholesterol ([3H]cholesterol) efflux assay.
This cholesterol efflux assay can be used to:
- Screen small molecules for their effect on cholesterol efflux as a part of drug discovery program.
How the assay works
Cholesterol Efflux Assay ab196985 is an assay for measuring cholesterol efflux from cells and uptake by acceptor apoplipoproteins using a fluorescently-labeled cholesterol analogue.
Cells are incubated with a labeling reagent mix that inserts fluorescently-labelled cholesterol into the plasma membrane (exchanging unlabelled cholesterol for fluoresently-labelled cholesterol). The labelled cells are then treated with an equilibration reagent mix overnight. This prevents the esterification and breakdown of fluorophore-labeled cholesterol, allowing it to be recognized by ABC-family lipid transporters.
After washing, cholesterol efflux is initiated by the addition of sample containing cholesterol acceptor apoplipoproteins. Following 4 hours incubation, the supernatant (medium containing cholesterol acceptor) of each well is transferred to a white 96-well plate and the fluorescence (Ex/Em = 485/523 nm) is measured in endpoint mode. The the adherent cell monolayer is solubilized by adding lysis buffer and the lysate is transfered to another white 96-well microplate and fluorescence is measured.
Cholesterol efflux from the labeled macrophage cells to a particular cholesterol acceptor is calculated by dividing the fluorescence intensity (RFU) obtained for the supernatant by the sum of the fluorescence intensity of the supernatant and cell lysate of the same treatment.
The kit includes a reagent to remove apolipoprotein B-containing lipoprotein particles (LDL and VLDL) from serum samples, enabling quantification of the efflux/uptake capacity of serum HDL without potential interference from LDL.
Cholesterol efflux assay protocol summary
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Background information
Cholesterol efflux from the peripheral tissues and cells in atherosclerotic plaque is an initial and critical step in Reverse Cholesterol Transport (RCT). RCT is the process by which extrahepatic cells, including macrophage-derived foam cells in arterial atherosclerotic plaque, export cholesterol to plasma high-density lipoprotein (HDL) particles via the action of transmembrane lipid transporters such as ABCA1 and ABCG1, following interaction of HDL particles with extracellular matrix proteins. This sequestered cholesterol is eventually transported from HDL to the liver for bile acid synthesis and excretion, thus lowering the peripheral lipid burden.
Other notes
This product is manufactured by BioVision, an Abcam company and was previously called K582 Cholesterol Efflux Fluorometric Assay Kit (cell-based). K582-100 is the same size as the 100 test size of ab196985.
The Safety Datasheet for this product has been updated for certain countries. Please check the current version in the Support and downloads section.
Cholesterol efflux is a mechanical process where excess cholesterol is removed from cells and transported to extracellular acceptors. The process is managed by proteins like ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) which are sometimes referred to as key players in cholesterol efflux. These proteins have masses of about 220 kDa and 75 kDa respectively and are highly expressed in tissues such as the liver intestine and macrophages. They interact directly with lipid-poor apolipoproteins facilitating the removal of cellular cholesterol.
Cholesterol efflux plays a significant role in maintaining lipid homeostasis and preventing lipid accumulation in cells. It is part of a larger complex known as the reverse cholesterol transport pathway which involves several lipoprotein particles including high-density lipoprotein (HDL). This pathway assists in transporting cholesterol from peripheral tissues back to the liver for excretion. By doing so it is instrumental in maintaining optimal cellular function and contributes to cardiovascular health.
Mechanisms controlling cholesterol efflux are integrated into the broader framework of lipid metabolism and inflammation pathways. The first is the reverse cholesterol transport pathway as already mentioned which uses HDL to ferry cholesterol back to the liver. Proteins such as lecithin–cholesterol acyltransferase (LCAT) and lipid transfer proteins are also involved in these pathways facilitating the conversion of cholesterol to cholesteryl esters and subsequent transport. Cholesterol efflux also interacts with the inflammatory pathway where it connects with proteins like nuclear receptors that regulate inflammatory responses.
Imbalances in cholesterol efflux are linked to conditions such as atherosclerosis and Tangier disease. A deficiency in cholesterol efflux can lead tangibly to cholesterol buildup in blood vessels contributing to plaque formation and atherosclerosis. The transporter proteins ABCA1 and ABCG1 are connected to these conditions; for instance mutations in ABCA1 are directly related to Tangier disease which results in extremely low levels of HDL cholesterol. Understanding cholesterol efflux and its related mechanisms is essential for developing strategies to manage and treat related disorders.
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Alice et al used Cholesterol Efflux Assay Kit ab196985 and Cholesterol/Cholesteryl ester Assay Kit Cholesterol/ Cholesteryl Ester Assay Kit - Quantitation ab65359 with Listeria monocytogenes (Lm) infected human monocyte-derived dendritic cells (Mo-DC) .
Changes in cholesterol metabolism in Lm-infected Mo-DC. (B) Cholesterol content and (C) cholesterol efflux from uninfected or Lm-infected Mo-DC were quantified at 6 hpi as described in “Methods ” section. Results shown are representative of 2 biologically independent experiments. Data represents the mean +/- SEM of each group (n = 3).
Cholesterol was quantified in Lm-infected or uninfected Mo-DC using the Choelsterol/Cholesteryl ester assay kit as described by the manufacturer (#Cholesterol/ Cholesteryl Ester Assay Kit - Quantitation ab65359 Abcam, Cambridge, MA). In general infected cells were processed after 6 h post-infection. Cholesterol efflux was determined using the Cholesterol efflux assay kit (ab196985, Abcam, Cambridge, MA) following manufacturer’s instructions and the recommended positive control.
Diagram showing the principles of the Cholesterol Efflux assay method.
Cholesterol Efflux Assay Kit ab196985 and Cholesterol/Cholesteryl ester Assay Kit Cholesterol/ Cholesteryl Ester Assay Kit - Quantitation ab65359 used with mouse bone marrow-derived macrophages.
Wang et al used Cholesterol Efflux Assay Kit ab196985 and Cholesterol/Cholesteryl ester Assay Kit Cholesterol/ Cholesteryl Ester Assay Kit - Quantitation ab65359 to investigate the impact of SULT2B1, the key enzyme of sterol sulfonation, deficiency in Bone marrow-derived macrophages (BMDMs) on cholesterol metabolism in mice.
Intracellular cholesterol content in WT and Sult2b1-/- M2 BMDMs (n = 5 per group). Cholesterol efflux in WT and Sult2b1-/- M2 BMDMs (n = 5 per group). Data are presented as the mean ± SD.
The free-cholesterol content of M2 BMDMs was measured using the cholesterol/cholesteryl ester quantitation assay kit (Cholesterol/ Cholesteryl Ester Assay Kit - Quantitation ab65359; Abcam). In brief, the dried lipids (extracted from 1 Ч 106 M2 BMDMs) were dissolved in 200 µl assay buffer (supplied in the kit), and then incubated with a cholesterol probe/cholesterol enzyme mix solution (supplied in the kit) at 37°C for 1 h protected from light. Finally, the fluorescence was detected by a fluorescent microplate reader (Ex/Em = 535/587 nm). The free-cholesterol content was quantified using a cholesterol standard curve.
The cholesterol efflux was measured using the commercial cholesterol efflux assay kit (cell-based) (ab196985; Abcam). In brief, M2 BMDMs (1 Ч 105) were incubated with a labelling reagent for 1 h and then with the Equilibration Buffer overnight. The cells were treated with the desired cholesterol acceptor (serum) for 6 h in an incubator (37°C, 5% CO2). The fluorescence intensity of the media and cell lysates was measured via a fluorescent microplate reader (Ex/Em = 482/515 nm). The cholesterol efflux was calculated by dividing the fluorescence intensity of the media by the total fluorescence intensity of the cell lysate and media.
Cholesterol Efflux Assay Kit ab196985 used with THP-1 macrophages.
Nyandwi et al used Cholesterol Efflux Assay Kit ab196985 to investigate the effect of Rosmarinic acid (RA) on macrophage cholesterol efflux.
THP-1 macrophages were labeled with cholesterol and equilibrated for 24 h in the presence or absence of RA (1, 10, 50 and 100 µM). Cholesterol efflux was evaluated in THP-1 macrophages after 6 h of incubation with ApoA1 (C) or HDL (D) as described in the Methods section. The data are presented as the mean ± SD of five independent experiments.
Macrophage-specific cholesterol efflux capacity was measured using a commercially available Cholesterol Efflux Assay Kit (Abcam, ab196985, Cambridge, MA, USA). Briefly, THP-1-derived macrophages (1 Ч 105) were labeled with a labeling reagent which includes a fluorescent labelled cholesterol and equilibrated for 24 h in a humidified incubator at 37 °C and 5% CO2. Then, the media was removed, and cells were washed with fresh media and treated with RA (1, 10, 50 and 100 µM) for 24 h. Cells were added with HDL or ApoA1 cholesterol acceptors and incubated for 6 h more. Thereafter, the cholesterol contents in media and cell lysis were measured and cholesterol efflux to HDL or ApoA1 was calculated as follows:
% cholesterol efflux
=100*
fluorescence intensity of medium /
fluorescence intensity of cell lysate+medium
Cholesterol Efflux Assay Kit ab196985 used with peritoneal macrophage cell cultures.
Hong et al used Cholesterol Efflux Assay Kit ab196985 to investigate the potential mechanism of lncRNA AI662270 on macrophage cholesterol transport in atherosclerosis.
To assess the physiological significance of Abca1 regulation by AI662270, we performed cholesterol efflux assays in peritoneal macrophages. Peritoneal macrophages were transfected with AI662270-P or siAI662270 for 48 h, and treated with either HDL (50 µg/mL) or apolipoprotein A-I (ApoA-I, 25 µg/mL) for 6 h. As shown in Fig. A, the macrophage-specific cholesterol efflux to lipid-poor HDL or ApoA-I capacity was significantly decreased by forced expression of AI662270 in vitro. In contrast, knockdown of AI662270 enhanced cholesterol efflux to lipid-poor HDL or ApoA-I (B).
AI662270 initiates cholesterol efflux and promotes foam cell formation. A, B Cholesterol efflux assay kit was used to measure cholesterol efflux to HDL or ApoA-I in peritoneal macrophages isolated from + AI662270-P (A) or + siAI662270 (B) (n = 5).
Cholesterol efflux was measured using a cholesterol efflux assay kit (ab196985; Abcam). Peritoneal macrophages were incubated with or without the plasmid vector AI662270-P) and AI662270 specific siRNA (siAI662270) as required. The cells were treated with either HDL (50 µg/mL) or ApoA-I (10 µg/mL). The percentage of cholesterol efflux was that the value assessed with fluorescence intensity of media was divided by the value calculated with fluorescence intensity of cell lysate plus fluorescence intensity of media × 100%.
Percentage (%) Labeled Cholesterol Efflux. J774.1 cells were labeled with the fluorescent cholesterol Labeling Media and treated with various cholesterol acceptors such as 2% LDL/VLDL-depleted Human Serum (2 µl/well), purified human HDL (25 µg/ml, 2.5 µg/well) or Positive Control reagent. Cholesterol efflux is expressed as percentage of fluorescently-labeled cholesterol transferred from labeled adherent macrophages to designated cholesterol acceptor present in supernatant over a 4 hour time period, with no treatment control (efflux to medium containing no acceptor) percentage subtracted (mean ± SD of N = 5-6 wells).
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