Highlights
- •Berberine (BBR) improved serum capacity to reduce macrophage cholesterol (C) content.
- •BBR did not alter macrophage C efflux to serum.
- •BBR blocked serum-derived C uptake by inhibiting macropinocytosis
- •BBR inhibited free C-induced cell responses by reducing membrane cholesterol.
- •We highlighted novel potentially atheroprotective activities of BBR.
Abstract
Background and aims
We investigated the effect of berberine (BBR), an alkaloid showing antiatherogenic
properties beyond the cholesterol lowering capacity, on macrophage cholesterol handling
upon exposure to human serum and on macrophage responses to excess free cholesterol
(FC) loading.
Methods and results
Mouse and human macrophages were utilized as cellular models. Cholesterol content
was measured by a fluorimetric assay; cholesterol efflux, cytotoxicity and membrane
FC distribution were evaluated by radioisotopic assays. Monocyte chemotactic protein-1
(MCP-1) secretion was measured by ELISA; membrane ruffling and macropinocytosis were
visualized by confocal microscopy. Exposure of cholesterol-enriched MPM to serum in
the presence of 1 μM BBR resulted in a reduction of intracellular cholesterol content
twice greater than exposure to serum alone (−52%; p < 0.01 and −21%; p < 0.05), an effect not mediated by an increase of cholesterol efflux, but rather
by the inhibition of cholesterol uptake from serum. Consistently, BBR inhibited in
a dose-dependent manner cholesterol accumulation in human macrophages exposed to hypercholesterolemic
serum. Confocal microscope analysis revealed that BBR inhibited macropinocytosis,
an independent-receptor process involved in LDL internalization. Macrophage FC-enrichment
increased MCP-1 release by 1.5 folds, increased cytotoxicity by 2 fold, and induced
membrane ruffling; all these responses were markedly inhibited by BBR. FC-enrichment
led to an increase in plasma membrane cholesterol by 4.5 folds, an effect counteracted
by BBR.
Conclusion
We showed novel potentially atheroprotective activities of BBR in macrophages, consisting
in the inhibition of serum-induced cholesterol accumulation, occurring at least in
part through an impairment of macropinocytosis, and of FC-induced deleterious effects.
Keywords
Acronyms:
acLDL (acetylated LDL), ApoA-I (apolipoprotein A-I), ABCA1 (ATP-binding cassette transporter A1), ABCG1 (ATP-binding cassette transporter G1), BBR (berberine), BSA (bovine serum albumin), CE (esterified cholesterol), CH-E (cholesterol enriched), CH-N (cholesterol normal), FC (free cholesterol), FC-E (free cholesterol enriched), FC-N (free cholesterol normal), FCS (fetal cow serum), HDL (high density lipoproteins), IL-6 (interleukin-6), LDL (low density lipoproteins), LPS (lipopolisaccaride), LY (lucifer yellow), MCP-1 (monocyte chemotactic protein-1), MPM (mouse peritoneal macrophages), PC (1-palmitoyl-2-oleoyl phospatidilcholine), PMA (phorbol, 12-myristate, 13-acetate), TNF-α (tumour necrosis factor alpha)To read this article in full you will need to make a payment
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References
- Regulation of macrophage function in inflammation and atherosclerosis.J Lipid Res. 2009; : S277-S281https://doi.org/10.1194/jlr.R800063-JLR200
- Metabolism of cholesteryl ester lipid droplets in a J774 macrophage foam cell model.Biochim Biophys Acta. 1990; 1045: 291-298
- Free cholesterol-loaded macrophages are an abundant source of tumor necrosis factor-alpha and interleukin-6: model of NF-kappaB- and map kinase-dependent inflammation in advanced atherosclerosis.J Biol Chem. 2005; 280: 21763-21772https://doi.org/10.1074/jbc.M501759200
- Nrf2 is essential for cholesterol crystal-induced inflammasome activation and exacerbation of atherosclerosis.Eur J Immunol. 2011; 41: 2040-2051https://doi.org/10.1002/eji.201041316
- Elevated plasma membrane cholesterol content alters macrophage signaling and function.Arterioscler Thromb Vasc Biol. 2006; 26: 372-378https://doi.org/10.1161/01.ATV.0000197848.67999.e1
- Free cholesterol alters macrophage morphology and mobility by an ABCA1 dependent mechanism.Atherosclerosis. 2011; 215: 70-76https://doi.org/10.1016/j.atherosclerosis.2010.12.004
- Antiatherogenic properties of flavonoids: implications for cardiovascular health.Can J Cardiol. 2010; (A:17A–21A)
- Berberine is a novel cholesterol-lowering drug working through a unique mechanism distinct from statins.Nat Med. 2004; 10: 1344-1351https://doi.org/10.1038/nm1135
- The effects of berberine on blood lipids: a systemic review and meta-analysis of randomized controlled trials.Planta Med. 2013; 79: 437-446https://doi.org/10.1055/s-0032-1328321
- Nutraceutical approach to moderate cardiometabolic risk: results of a randomized, double-blind and crossover study with armolipid plus.J Clin Lipidol. 2014; 8: 61-68https://doi.org/10.1016/j.jacl.2013.11.003
- Berberine-induced inhibition of adipocyte enhancer-binding protein 1 attenuates oxidized low-density lipoprotein accumulation and foam cell formation in phorbol 12-myristate 13-acetate-induced macrophages.Eur J Pharmacol. 2012; 690: 164-169https://doi.org/10.1016/j.ejphar.2012.07.009
- Effects of berberine on expression of LOX-1 and SR-BI in human macrophage-derived foam cells induced by ox-LDL.Am J Chin Med. 2010; 38: 1161-1169https://doi.org/10.1142/S0192415X10008548
- Suppression of oxLDL-induced MMP-9 and EMMPRIN expression by berberine via inhibition of NF-kappaB activation in human THP-1 macrophages.Anat Rec Hob. 2012; 295: 78-86https://doi.org/10.1002/ar.21489
- Berberine reduces both MMP-9 and EMMPRIN expression through prevention of p38 pathway activation in PMA-induced macrophages.Int J Cardiol. 2011; 146: 153-158https://doi.org/10.1016/j.ijcard.2009.06.023
- Berberine inhibits the expression of TNFalpha, MCP-1, and IL-6 in AcLDL-stimulated macrophages through PPARgamma pathway.Endocrine. 2008; 33: 331-337https://doi.org/10.1007/s12020-008-9089-3
- A modification of the Lowry procedure to simplify protein determination in membrane and lipoprotein samples.Anal Biochem. 1978; 87 (doi:0003-2697(78)90586-9): 206-210
- Probucol inhibits ABCA1-mediated cellular lipid efflux.Arterioscler Thromb Vasc Biol. 2004; 24: 2345-2350https://doi.org/10.1161/01.ATV.0000148706.15947.8a
- Cytotoxic cellular cholesterol is selectively removed by apoA-I via ABCA1.Atherosclerosis. 2003; 171 (doi:S0021915003003642): 235-243
- Impaired ATP-binding cassette transporter A1-mediated sterol efflux from oxidized LDL-loaded macrophages.FEBS Lett. 2005; 579: 6537-6542https://doi.org/10.1016/j.febslet.2005.10.042
- Measurement of cholesterol bidirectional flux between cells and lipoproteins.J Lipid Res. 2006; 47: 605-613https://doi.org/10.1194/jlr.M500466-JLR200
- The roles of different pathways in the release of cholesterol from macrophages.J Lipid Res. 2007; 48: 2453-2462https://doi.org/10.1194/jlr.M700274-JLR200
- Fluid-phase pinocytosis of LDL by macrophages: a novel target to reduce macrophage cholesterol accumulation in atherosclerotic lesions.Curr Pharm Des. 2013; 19 (doi:CPD-EPUB-20130215-4): 5865-5872
- Eicosapentaenoic acid and docosahexaenoic acid regulate modified LDL uptake and macropinocytosis in human macrophages.Lipids. 2011; 46: 1053-1061https://doi.org/10.1007/s11745-011-3598-1
- Cytotoxic cholesterol is generated by the hydrolysis of cytoplasmic cholesteryl ester and transported to the plasma membrane.Atherosclerosis. 1999; 146 (doi:S0021915099001550): 309-319
- The LDL pathway in human fibroblasts: a receptor-mediated mechanism for the regulation of cholesterol metabolism.Curr Top Cell Regul. 1976; 11: 147-181
- The LDL receptor and the regulation of cellular cholesterol metabolism.J Cell Sci Suppl. 1985; 3: 131-137
- Mechanisms of endocytosis.Annu Rev Biochem. 2009; 78: 857-902https://doi.org/10.1146/annurev.biochem.78.081307.110540
- Anti-atherogenic effect of berberine on LXRalpha-ABCA1-dependent cholesterol efflux in macrophages.J Cell Biochem. 2011; 111: 104-110https://doi.org/10.1002/jcb.22667
- HMG-CoA reductase inhibitors reduce acetyl LDL endocytosis in mouse peritoneal macrophages.Arterioscler Thromb Vasc Biol. 1995; 15: 1352-1358
Article info
Publication history
Published online: August 29, 2014
Accepted:
August 12,
2014
Received in revised form:
August 1,
2014
Received:
April 17,
2014
Identification
Copyright
© 2014 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
