Inflammation, high-density lipoprotein and cardiovascular dysfunction
Abstract
PURPOSE OF REVIEW: This review describes the evidence that supports the hypothesis that high-density lipoprotein (HDL) is atheroprotective due to its antiinflammatory effects and benefits on vascular health. RECENT FINDINGS: Recent investigations have shown that HDL may inhibit atherosclerosis by promoting healthy endothelial function and by limiting or inhibiting the activation of macrophage and other immune cells. Receptors for HDL clearly regulate immune system function as well as cellular stress. Recent studies also suggest that participation of HDL in the process of reverse cholesterol transport may inhibit growth factor and cytokine receptor signaling by depleting cholesterol from lipid rafts. However, inflammation can also be associated with circulating dysfunctional HDL, which often possesses both prooxidative and proinflammatory properties. SUMMARY: These studies suggest that HDL-based therapeutics have potential in treating both acute and chronic conditions associated with inflammation. These studies also reveal several other pathways that may be targeted for therapeutic drug development.
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HDL can protect against atherosclerosis by multiple mechanisms, including the ability to efflux cholesterol from endothelial macrophages (macrophage reverse cholesterol transport), or through anti-inflammatory, antioxidative and antiapoptotic pathways.
“HDL can protect against atherosclerosis by multiple mechanisms, including the ability to efflux cholesterol from endothelial macrophages (macrophage reverse cholesterol transport)43, or through anti-inflammatory44, antioxidative45 and antiapoptotic46 pathways.”
From Prolonged sleep restriction induces changes in pathways involved in cholesterol metabolism and inflammatory responses (2016) · cites this paper as [44]
Cites
Grundy, S. M., Cleeman, J. I., Daniels, S. R., Donato, K. A., Eckel, R. H., Franklin, B. A., Gordon, D. J., Krauss, R. M., Savage, P. J., Smith, S. C., et al. (2005) · Circulation · doi:10.1161/circulationaha.105.169404 · Cited by 11,961 · see citing works
Biological, clinical and population relevance of 95 loci for blood lipids
Teslovich, T. M., Musunuru, K., Smith, A. V., Edmondson, A. C., Stylianou, I. M., Koseki, M., Pirruccello, J. P., Ripatti, S., Chasman, D. I., Willer, C. J., et al. (2010) · Nature · doi:10.1038/nature09270 · Cited by 3,487 · see citing works
Identification of Scavenger Receptor SR-BI as a High Density Lipoprotein Receptor
Acton, S. L., Rigotti, A., Landschulz, K. T., Xu, S., Hobbs, H. H., & Krieger, M. (1996) · Science · doi:10.1126/science.271.5248.518 · Cited by 2,347 · see citing works
TLR4 mutations are associated with endotoxin hyporesponsiveness in humans
Arbour, N. C., Lorenz, E., Schutte, B. C., Zabner, J., Kline, J. N., Jones, M., Frees, K., Watt, J. L., & Schwartz, D. A. (2000) · Nature Genetics · doi:10.1038/76048 · Cited by 2,024 · see citing works
Tumor Necrosis Factor-α Signaling in Macrophages
Parameswaran, N., & Patial, S. (2010) · Critical Reviews in Eukaryotic Gene Expression · doi:10.1615/critreveukargeneexpr.v20.i2.10 · Cited by 1,451 · see citing works
Antiinflammatory Properties of HDL
Barter, P. J., Nicholls, S., Rye, K.-A., Anantharamaiah, G. M., Navab, M., & Fogelman, A. M. (2004) · Circulation Research · doi:10.1161/01.res.0000146094.59640.13 · Cited by 1,394 · see citing works
Toll-like Receptor 4 Polymorphisms and Atherogenesis
Kiechl, S. J., Lorenz, E., Reindl, M., Wiedermann, C. J., Oberhollenzer, F., Bonora, E., Willeit, J., & Schwartz, D. A. (2002) · New England Journal of Medicine · doi:10.1056/nejmoa012673 · Cited by 1,024 · see citing works
High-Density Lipoproteins Inhibit Cytokine-Induced Expression of Endothelial Cell Adhesion Molecules
COCKERILL, G. W., Rye, K., Gamble, J. R., Vadas, M. A., & Barter, P. J. (1995) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/01.atv.15.11.1987 · Cited by 782 · see citing works
ATP-Binding Cassette Transporters and HDL Suppress Hematopoietic Stem Cell Proliferation
Yvan‐Charvet, L., Pagler, T. A., Gautier, E. L., Avagyan, S., Siry, R., Han, S., Welch, C. L., Wang, N., Randolph, G. J., Snoeck, H. W., et al. (2010) · Science · doi:10.1126/science.1189731 · Cited by 724 · see citing works
HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3
Nofer, J., van der Giet, M., Tölle, M., Wolinska, I., Lipinski, K. V. W., Baba, H. A., Tietge, U. J. F., Gödecke, A., Ishii, I., Kleuser, B., et al. (2004) · Journal of Clinical Investigation · doi:10.1172/jci18004 · Cited by 694 · see citing works
Role of HDL, ABCA1, and ABCG1 Transporters in Cholesterol Efflux and Immune Responses
Yvan‐Charvet, L., Wang, N., & Tall, A. R. (2009) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/atvbaha.108.179283 · Cited by 683 · see citing works
HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3
Nofer, J., van der Giet, M., Tölle, M., et al. (2004) · Journal of Clinical Investigation · doi:10.1172/jci200418004 · Cited by 607 · see citing works
Protective immunity against atherosclerosis carried by B cells of hypercholesterolemic mice
Caligiuri, G., Nicoletti, A., Poirier, B., & Hansson, G. K. (2002) · Journal of Clinical Investigation · doi:10.1172/jci7272 · Cited by 531 · see citing works
High-Density Lipoprotein Reduces the Human Monocyte Inflammatory Response
Murphy, A. J., Woollard, K. J., Hoang, A., Mukhamedova, N., Stirzaker, R. A., McCormick, S. P. A., Remaley, A. T., Sviridov, D., & Chin-Dusting, J. P. F. (2008) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/atvbaha.108.168690 · Cited by 511 · see citing works
In vivo protection against endotoxin by plasma high density lipoprotein.
Levine, D. M., Parker, T. S., Donnelly, T. M., Walsh, A., & Rubin, A. L. (1993) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.90.24.12040 · Cited by 485 · see citing works
TNF: A master switch for inflammation to cancer
Sethi, G. (2008) · Frontiers in Bioscience · doi:10.2741/3066 · Cited by 458 · see citing works
Shimpo, M., Morrow, D. A., Weinberg, E. O., Sabatine, M. S., Murphy, S. A., Antman, E. M., & Lee, R. T. (2004) · Circulation · doi:10.1161/01.cir.0000127958.21003.5a · Cited by 410 · see citing works
TNFα in atherosclerosis, myocardial ischemia/reperfusion and heart failure
Kleinbongard, P., Heusch, G., & Schulz, R. (2010) · Pharmacology & Therapeutics · doi:10.1016/j.pharmthera.2010.05.002 · Cited by 408 · see citing works
Monocyte recruitment and foam cell formation in atherosclerosis
Bobryshev, Y. V. (2005) · Micron · doi:10.1016/j.micron.2005.10.007 · Cited by 370 · see citing works
Zhu, X., Lee, J., Timmins, J. M., Brown, J. M., Boudyguina, E. Y., Mulya, A., Gebre, A. K., Willingham, M. C., Hiltbold, E. M., Mishra, N., et al. (2008) · Journal of Biological Chemistry · doi:10.1074/jbc.m801408200 · Cited by 350 · see citing works
The Macrophage Cholesterol Exporter ABCA1 Functions as an Anti-inflammatory Receptor
Tang, C., Liu, Y., Kessler, P. S., Vaughan, A. M., & Oram, J. F. (2009) · Journal of Biological Chemistry · doi:10.1074/jbc.m109.047472 · Cited by 284 · see citing works
Brinton, E. A., Eisenberg, S., & Breslow, J. L. (1994) · Arteriosclerosis and Thrombosis: A Journal of Vascular Biology · doi:10.1161/01.atv.14.5.707 · Cited by 265 · see citing works
Association of the Toll-Like Receptor 4 Gene Asp299Gly Polymorphism With Acute Coronary Events
Ameziane, N., Beillat, T., Verpillat, P., Chollet‐Martin, S., Aumont, M.-C., Seknadji, P., Lamotte, M., Lebret, D., Ollivier, V., & de Prost, D. (2003) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/01.atv.0000101191.92392.1d · Cited by 241 · see citing works
Boekholdt, S. M., Agema, W. R. P., Peters, R. J. G., Zwinderman, A. H., van der Wall, E. E., Reitsma, P. H., Kastelein, J. J. P., & Jukema, J. W. (2003) · Circulation · doi:10.1161/01.cir.0000068311.40161.28 · Cited by 224 · see citing works
Toll-like receptor 4 deficiency causes pulmonary emphysema
Zhang, X., Shan, P., Jiang, G., Cohn, L. E., & Lee, P. J. (2006) · Journal of Clinical Investigation · doi:10.1172/jci28139 · Cited by 221 · see citing works
Role for circulating lipoproteins in protection from endotoxin toxicity
Feingold, K. R., Funk, J. L., Moser, A. H., Shigenaga, J. K., Rapp, J. H., & Grünfeld, C. (1995) · Infection and Immunity · doi:10.1128/iai.63.5.2041-2046.1995 · Cited by 210 · see citing works
Landry, Y. D., Denis, M., Nandi, S., Bell, S., Vaughan, A. M., & Zha, X. (2006) · Journal of Biological Chemistry · doi:10.1074/jbc.m602247200 · Cited by 206 · see citing works
Patel, S., Drew, B. G., Nakhla, S., Duffy, S. J., Murphy, A. J., Barter, P. J., Rye, K., Chin-Dusting, J. P. F., Hoang, A., Sviridov, D., et al. (2009) · Journal of the American College of Cardiology · doi:10.1016/j.jacc.2008.12.008 · Cited by 203 · see citing works
Kimura, T., Tomura, H., Mogi, C., Kuwabara, A., Damirin, A., Ishizuka, T., Sekiguchi, A., Ishiwara, M., Im, D., Sato, K., et al. (2006) · Journal of Biological Chemistry · doi:10.1074/jbc.m605823200 · Cited by 198 · see citing works
Kocher, O. N., Yesilaltay, A., Cirovic, C., Pal, R., Rigotti, A., & Krieger, M. (2003) · Journal of Biological Chemistry · doi:10.1074/jbc.m310482200 · Cited by 172 · see citing works
Cai, L., Ji, A., de Beer, F. C., Tannock, L. R., & van der Westhuyzen, D. R. (2008) · Journal of Clinical Investigation · doi:10.1172/jci31539 · Cited by 167 · see citing works
Association of hypo-responsive toll-like receptor 4 variants with risk of myocardial infarction*1
Edfeldt, K. (2004) · European Heart Journal · doi:10.1016/j.ehj.2004.05.004 · Cited by 164 · see citing works
HDL metabolism and activity in chronic kidney disease
Vaziri, N. D., Navab, M., & Fogelman, A. M. (2010) · Nature Reviews Nephrology · doi:10.1038/nrneph.2010.36 · Cited by 160 · see citing works
Ikemoto, M., Arai, H., Feng, D., Tanaka, K., Aoki, J., Dohmae, N., Takio, K., Adachi, H., Tsujimoto, M., & Inoue, K. (2000) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.100114397 · Cited by 156 · see citing works
Gong, M. C., Wilson, M. E., Kelly, T. H., Su, W., Dressman, J. L., Kincer, J. F., Matveev, S. V., Guo, L., Guerin, T. M., Li, X., et al. (2003) · Journal of Clinical Investigation · doi:10.1172/jci16777 · Cited by 152 · see citing works
Charakida, M. (2009) · JAMA · doi:10.1001/jama.2009.1346 · Cited by 152 · see citing works
High-Density Lipoproteins Suppress Chemokines and Chemokine Receptors In Vitro and In Vivo
Bursill, C. A., Castro, M. L., Beattie, D. T., Nakhla, S., van der Vorst, E. P. C., Heather, A. K., Barter, P. J., & Rye, K.-A. (2010) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/atvbaha.110.211342 · Cited by 148 · see citing works
Shao, B., Pennathur, S., Pagani, I., Oda, M. N., Witztum, J. L., Oram, J. F., & Heinecke, J. W. (2010) · Journal of Biological Chemistry · doi:10.1074/jbc.m110.118182 · Cited by 136 · see citing works
Birjmohun, R. S., van Leuven, S. I., Levels, J. H. M., Veer, C. V. ′., Kuivenhoven, J. A., Meijers, J. C. M., Levi, M. M., Kastelein, J. J. P., van der Poll, T., & Stroes, E. S. G. (2007) · Arteriosclerosis Thrombosis and Vascular Biology · doi:10.1161/atvbaha.106.136325 · Cited by 118 · see citing works
Silver, D. L. (2002) · Journal of Biological Chemistry · doi:10.1074/jbc.m206584200 · Cited by 115 · see citing works
TNFα induces ABCA1 through NF-κB in macrophages and in phagocytes ingesting apoptotic cells
Gerbod-Giannone, M.-C., Li, Y., Holleboom, A. G., Han, S., Hsu, L.-C., Tabas, I. A., & Tall, A. R. (2006) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0510345103 · Cited by 115 · see citing works
5A Apolipoprotein Mimetic Peptide Promotes Cholesterol Efflux and Reduces Atherosclerosis in Mice
Amar, M. J., D’Souza, W., Turner, S., Demosky, S. J., Sviridov, D. O., Stonik, J. A., Luchoomun, J., Voogt, J. N., Hellerstein, M. K., Sviridov, D., et al. (2010) · Journal of Pharmacology and Experimental Therapeutics · doi:10.1124/jpet.110.167890 · Cited by 114 · see citing works
Vaziri, N. D., Moradi, H., Pahl, M. V., Fogelman, A. M., & Navab, M. (2009) · Kidney International · doi:10.1038/ki.2009.177 · Cited by 113 · see citing works
Atherosclerotic plaque development and instability: A dual role for VEGF
Holm, P. W., Slart, R. H. J. A., Zeebregts, C. J., Hillebrands, J., & Tio, R. A. (2008) · Annals of Medicine · doi:10.1080/07853890802516507 · Cited by 106 · see citing works
Shao, B., Tang, C., Heinecke, J. W., & Oram, J. F. (2010) · Journal of Lipid Research · doi:10.1194/jlr.m004085 · Cited by 94 · see citing works
Harðardóttir, I., Moser, A. H., Memon, R. A., Grünfeld, C., & Feingold, K. R. (1994) · PubMed · Cited by 86 · see citing works
Ap, H., At, C., & Doran, J. E. (1995) · PubMed · Cited by 81 · see citing works
Good, D. W., George, T., & Watts, B. A. (2009) · American Journal of Physiology-Renal Physiology · doi:10.1152/ajprenal.00335.2009 · Cited by 72 · see citing works
The apolipoprotein A-I mimetic peptide 4F prevents defects in vascular function in endotoxemic rats
Dai, L., Datta, G., Zhang, Z., Gupta, H., Patel, R. P., Honavar, J., Modi, S., Wyss, J. M., Palgunachari, M. N., Anantharamaiah, G. M., et al. (2010) · Journal of Lipid Research · doi:10.1194/jlr.m008086 · Cited by 70 · see citing works
Lee, Y., Lee, S., Jung, E. S., Kim, J., Shim, C. Y., Ko, Y., Choi, D., Jang, Y., Chung, N., & Ha, J. (2010) · Atherosclerosis · doi:10.1016/j.atherosclerosis.2010.09.012 · Cited by 65 · see citing works
Anti-inflammatory and recycling properties of an apolipoprotein mimetic peptide, Ac-hE18A-NH2
Datta, G., White, C. R., Dashti, N., Chaddha, M., Palgunachari, M. N., Gupta, H., Handattu, S. P., Garber, D. W., & Anantharamaiah, G. M. (2009) · Atherosclerosis · doi:10.1016/j.atherosclerosis.2009.07.019 · Cited by 60 · see citing works
Escolá‐Gil, J. C., Rotllán, N., Julve, J., & Blanco‐Vaca, F. (2009) · Atherosclerosis · doi:10.1016/j.atherosclerosis.2008.12.044 · Cited by 58 · see citing works
Toll Receptor Polymorphisms and Carotid Artery Intima-Media Thickness
Labrum, R. W., Bevan, S., Sitzer, M., Lorenz, M., & Markus, H. S. (2007) · Stroke · doi:10.1161/01.str.0000260184.85257.2b · Cited by 54 · see citing works
Toll-like Receptor Polymorphisms and Carotid Artery Intima-Media Thickness
Lepper, P. M., von Eynatten, M., Humpert, P. M., Triantafilou, M., & Triantafilou, K. (2007) · Stroke · doi:10.1161/strokeaha.107.487058 · Cited by 53 · see citing works
Wang, Y., Yang, X., Cheng, B., Mei, C., Li, Q., Xiao, H., Zeng, Q., Liao, Y., & Liu, K. (2009) · Phytotherapy Research · doi:10.1002/ptr.2958 · Cited by 48 · see citing works
Heiskanen, M., Kähönen, M. A. P., Hurme, M., Lehtimäki, T. J., Mononen, N., Juonala, M., Hutri‐Kähönen, N., Viikari, J. S. A., Raitakari, O. T., & Hulkkonen, J. (2009) · Atherosclerosis · doi:10.1016/j.atherosclerosis.2009.06.032 · Cited by 48 · see citing works
HDLs activate ADAM17‐dependent shedding
Tellier, E., Canault, M., Poggi, M., Bonardo, B., Nicolay, A., Alessi, M., Nalbone, G., & Peiretti, F. (2007) · Journal of Cellular Physiology · doi:10.1002/jcp.21265 · Cited by 44 · see citing works
Biogenesis of HDL by SAA is dependent on ABCA1 in the liver in vivo
Hu, W., Abe-Dohmae, S., Tsujita, M., Iwamoto, N., Ogikubo, O., Otsuka, T., Kumon, Y., & Yokoyama, S. (2007) · Journal of Lipid Research · doi:10.1194/jlr.m700402-jlr200 · Cited by 42 · see citing works
Brussel, I. V., Vré, E. A. V., Meyer, G. R. Y. D., Vrints, C. J., Bosmans, J. M., & Bult, H. (2011) · Clinical Science · doi:10.1042/cs20100440 · Cited by 39 · see citing works
Skaggs, B. J., Hahn, B. H., Sahakian, L., Grossman, J. M., & McMahon, M. A. (2010) · Clinical Immunology · doi:10.1016/j.clim.2010.06.014 · Cited by 38 · see citing works
Yeh, C., Li, H., Malhotra, D. K., et al. (2009) · American Journal of Physiology-Heart and Circulatory Physiology · doi:10.1152/ajpheart.01032.2008 · Cited by 37 · see citing works
Surra, J. C., Guillén, N., Arbonés-Mainar, J. M., et al. (2010) · Journal of Atherosclerosis and Thrombosis · doi:10.5551/jat.3541 · Cited by 36 · see citing works
Coronary artery calcification and cardiovascular risk: the role of RANKL/OPG signalling
Quercioli, A., Montecucco, F., Bertolotto, M. B., Ottonello, L. C., Pende, A., Mach, F., & Dallegri, F. (2010) · European Journal of Clinical Investigation · doi:10.1111/j.1365-2362.2010.02308.x · Cited by 26 · see citing works
Szkodziński, J., Błażelonis, A., Wilczek, K. L., et al. (2009) · International Journal of Immunopathology and Pharmacology · doi:10.1177/039463200902200226 · Cited by 24 · see citing works
IL‐18 gene polymorphism, cardiovascular mortality and coronary artery disease
Hernesniemi, J. A., Anttila, K., Nieminen, T. V. M., Kähönen, M. A. P., Mononen, N., Nikus, K. C., Turjanmaa, V., Viik, J., Lehtinen, R., & Lehtimäki, T. J. (2010) · European Journal of Clinical Investigation · doi:10.1111/j.1365-2362.2010.02356.x · Cited by 20 · see citing works
Effect of TNFα on activities of different promoters of human apolipoprotein A-I gene
Orlov, S., Mogilenko, D. A., Shavva, V. S., Dizhe, E. B., Ignatovich, I. A., & Ap, P. (2010) · Biochemical and Biophysical Research Communications · doi:10.1016/j.bbrc.2010.06.064 · Cited by 20 · see citing works
Jandt, E., Mutschke, O., Mahboobi, S., et al. (2009) · Vascular Pharmacology · doi:10.1016/j.vph.2009.11.001 · Cited by 18 · see citing works
Homeostatic Role of Toll-like Receptor 4 in the Endothelium and Heart
Mackenzie, L. S., Belcher, E., Moreno, L., et al. (2007) · Journal of Cardiovascular Pharmacology and Therapeutics · doi:10.1177/1074248407306217 · Cited by 18 · see citing works
Toll-Like Receptors: Link between “Danger” Ligands and Plaque Instability
Balogh, S., Kiss, I., & Császár, A. (2009) · Current Drug Targets · doi:10.2174/138945009788488387 · Cited by 16 · see citing works
Cimmino, G., Chen, W., Speidl, W. S., et al. (2009) · Journal of Cardiovascular Pharmacology · doi:10.1097/fjc.0b013e3181bad264 · Cited by 9 · see citing works
The interleukin-1 cluster, dyslipidaemia and risk of myocardial infarction
Keavney, B. D. (2010) · BMC Medicine · doi:10.1186/1741-7015-8-6 · Cited by 6 · see citing works
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- Authors
- Haas, M. J., & Mooradian, A. D.
- Affiliations
- University of Florida (US)
- Corresponding author
- Haas, Michael J
- Venue
- Current Opinion in Infectious Diseases
- Published
- 2011-06
- Volume
- 24
- Issue
- 3
- Pages
- 265-272
- ISSN
- 0951-7375 (ISSN-L)
- OpenAlex
- W2327064388
- Cited by
- 38
- References
- 71
- Citations by year
- 2025: 2 · 2020: 2 · 2019: 1 · 2017: 1 · 2016: 1 · 2015: 1 · 2014: 6 · 2013: 8 · 2012: 13
- FWCI
- 0.86
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Current Opinion in Infectious Diseases (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Immunology and Microbiology › Immunology › Atherosclerosis and Cardiovascular Diseases
- Health Sciences › Medicine › Surgery › Cholesterol and Lipid Metabolism
- Health Sciences › Medicine › Surgery › Lipoproteins and Cardiovascular Health
- Keywords
- high-density lipoprotein, inflammation, atherosclerosis, endothelial function, macrophage activation, HDL receptor, reverse cholesterol transport, lipid rafts, HDL dysfunction, cardiovascular dysfunction
- MeSH terms
- Anti-Inflammatory Agents, Cardiovascular Diseases, Coronary Artery Disease, Humans, Inflammation, Lipoproteins, HDL
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