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Conjugated Linoleic Acids Have Anti-Inflammatory Effects in Cultured Endothelial Cells. Int J Mol Sci 2023; 24:ijms24010874. [PMID: 36614314 PMCID: PMC9821047 DOI: 10.3390/ijms24010874] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/28/2022] [Accepted: 12/31/2022] [Indexed: 01/05/2023] Open
Abstract
Conjugated linoleic acid (CLA) isomers may have a role in preventing atherosclerosis through the modulation of inflammation, particularly of the endothelium. However, whether low concentrations of CLAs are able to affect basal unstimulated endothelial cell (EC) responses is not clear. The aim of this study was to evaluate the effects of two CLAs (cis-9, trans-11 (CLA9,11) and trans-10, cis-12 (CLA10,12)) on the basal inflammatory responses by ECs. EA.hy926 cells (HUVEC lineage) were cultured under standard conditions and exposed to individual CLAs for 48 h. Both CLAs were incorporated into ECs in a dose-dependent manner. CLA9,11 (1 μM) significantly decreased concentrations of MCP-1 (p < 0.05), IL-6 (p < 0.05), IL-8 (p < 0.01) and RANTES (p < 0.05) in the culture medium. CLA10,12 (10 μM) decreased the concentrations of MCP-1 (p < 0.05) and RANTES (p < 0.05) but increased the concentration of IL-6 (p < 0.001). At 10 μM both CLAs increased the relative expression of the NFκβ subunit 1 gene (p < 0.01 and p < 0.05, respectively), while decreasing the relative expression of PPARα (p < 0.0001), COX-2 (p < 0.0001) and IL-6 (p < 0.0001) genes. CLA10,12 increased the relative expression of the gene encoding IκK-β at 10 μM compared with CLA9,11 (p < 0.05) and increased the relative expression of the gene encoding IκBα at 1 and 10 μM compared with linoleic acid (both p < 0.05). Neither CLA affected the adhesion of monocytes to ECs. These results suggest that low concentrations of both CLA9,11 and CLA10,12 have modest anti-inflammatory effects in ECs. Thus, CLAs may influence endothelial function and the risk of vascular disease. Nevertheless, at these low CLA concentrations some pro-inflammatory genes are upregulated while others are downregulated, suggesting complex effects of CLAs on inflammatory pathways.
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Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives. Nutrients 2019; 11:nu11020370. [PMID: 30754681 PMCID: PMC6413010 DOI: 10.3390/nu11020370] [Citation(s) in RCA: 158] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 02/03/2019] [Accepted: 02/08/2019] [Indexed: 02/07/2023] Open
Abstract
Obesity and its comorbidities, including type 2 diabetes and cardiovascular disease, are straining our healthcare system, necessitating the development of novel strategies for weight loss. Lifestyle modifications, such as exercise and caloric restriction, have proven effective against obesity in the short term, yet obesity persists because of the high predilection for weight regain. Therefore, alternative approaches to achieve long term sustainable weight loss are urgently needed. Conjugated linoleic acid (CLA), a fatty acid found naturally in ruminant animal food products, has been identified as a potential anti-obesogenic agent, with substantial efficacy in mice, and modest efficacy in obese human populations. Originally described as an anti-carcinogenic fatty acid, in addition to its anti-obesogenic effects, CLA has now been shown to possess anti-atherosclerotic properties. This review summarizes the pre-clinical and human studies conducted using CLA to date, which collectively suggest that CLA has efficacy against cancer, obesity, and atherosclerosis. In addition, the potential mechanisms for the many integrative physiological effects of CLA supplementation will be discussed in detail, including an introduction to the gut microbiota as a potential mediator of CLA effects on obesity and atherosclerosis.
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Liu X, Joseph SV, Wakefield AP, Aukema HM, Jones PJH. High Dose trans-10,cis-12 CLA Increases Lean Body Mass in Hamsters, but Elevates Levels of Plasma Lipids and Liver Enzyme Biomarkers. Lipids 2011; 47:39-46. [DOI: 10.1007/s11745-011-3616-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 09/16/2011] [Indexed: 10/16/2022]
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Belda BJ, Lee Y, Vanden Heuvel JP. Conjugated linoleic acids and inflammation: isomer- and tissue-specific responses. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.10.54] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Jeon SM, Kim HJ, Woo MN, Lee MK, Shin YC, Park YB, Choi MS. Fucoxanthin-rich seaweed extract suppresses body weight gain and improves lipid metabolism in high-fat-fed C57BL/6J mice. Biotechnol J 2010; 5:961-9. [DOI: 10.1002/biot.201000215] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Trans-8,cis-10+cis-9,trans-11-conjugated linoleic acid mixture alters body composition in Syrian golden hamsters fed a hypercholesterolaemic diet. Br J Nutr 2010; 104:1443-9. [DOI: 10.1017/s0007114510002345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer,trans-8,cis-10 (t8,c10)-CLA, in the form of an equimolar mixture with thecis-9,trans-11 (c9,t11) isomer, on body weight and body composition, circulating glucose and lipid concentrations, and liver weights were studied in sixty male Syrian golden hamsters. Animals were randomised to receive for 28 d a semi-purified, hypercholesterolaemic diet (5 % dietary fat and 0·25 % cholesterol) supplemented at the 2 % level with either thet8,c10+c9,t11-CLA mixture,c9,t11-CLA ortrans-10,cis-12 (t10,c12)-CLA replacing lard and safflower-seed oil (control). Results show that compared with control, thet8,c10+c9,t11-CLA mixture andt10,c12-CLA-fed animals had lower (P < 0·0001) fat mass following supplementation. Animals consumingt10,c12-CLA also possessed higher lean mass compared with control andc9,t11-CLA groups (P < 0·001). However, the livers of these animals were larger (P < 0·0001) compared with those in the control and other CLA groups. Body weights of the hamsters did not differ across the experimental groups. CLA treatments had no effect on serum glucose or lipid profile, except for inducing higher (P < 0·05) non-HDL-cholesterol concentration witht10,c12-CLA compared with thec9,t11 isomer. Overall, these results indicate that in male hamsters fed a hypercholesterolaemic diet, thet8,c10+c9,t11-CLA mixture does not have an impact on blood lipid profile, but is able to effectively reduce fat mass, without incurring an accompanying liver enlargement.
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Park Y, Albright KJ, Storkson JM, Liu W, Pariza MW. Effects of dietary conjugated linoleic acid (CLA) on spontaneously hypertensive rats. J Funct Foods 2010. [DOI: 10.1016/j.jff.2010.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Subbaiah PV, Sircar D, Aizezi B, Mintzer E. Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:506-14. [PMID: 20004173 DOI: 10.1016/j.bbamem.2009.11.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 11/12/2009] [Accepted: 11/30/2009] [Indexed: 01/19/2023]
Abstract
Conjugated linoleic acids (CLA) are known to exert several isomer-specific biological effects, but their mechanisms of action are unclear. In order to determine whether the physicochemical effects of CLA on membranes play a role in their isomer-specific effects, we synthesized phosphatidylcholines (PCs) with 16:0 at sn-1 position and one of four CLA isomers (trans 10 cis 12 (A), trans 9 trans 11 (B), cis 9 trans 11 (C), and cis 9 cis 11 (D)) at sn-2, and determined their biophysical properties in monolayers and bilayers. The surface areas of the PCs with the two natural CLA (A and C) were similar at all pressures, but they differed significantly in the presence of cholesterol, with PC-A condensing more than PC-C. Liposomes of PC-A similarly showed increased binding of cholesterol compared to PC-C liposomes. PC-A liposomes were less permeable to carboxyfluorescein compared to PC-C liposomes. The PC with two trans double bonds (B) showed the highest affinity to cholesterol and lowest permeability. The two natural CLA-PCs (A and C) stimulated lecithin-cholesterol acyltransferase activity by 2-fold, whereas the unnatural CLA-PCs (B and D) were inhibitory. These results suggest that the differences in the biophysical properties of CLA isomers A and C may partly contribute to the known differences in their biological effects.
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Affiliation(s)
- Papasani V Subbaiah
- Department of Medicine, University of Illinois at Chicago, 1819 West Polk, Chicago, IL 60612, USA.
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Kurban S, Erkoç F, Erkoç Ş. Quantum‐chemical treatment of the linoleic acid molecule and two of its conjugated isomers. EUR J LIPID SCI TECH 2009. [DOI: 10.1002/ejlt.200900046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Sevil Kurban
- Department of Biochemistry, Meram Faculty of Medicine, Selçuk University, Konya, Turkey
| | - Figen Erkoç
- Department of Biology Education, Gazi University, Ankara, Turkey
| | - Şakir Erkoç
- Department of Physics, Middle East Technical University, Ankara, Turkey
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Mitchell PL, McLeod RS. Conjugated linoleic acid and atherosclerosis: studies in animal models. Biochem Cell Biol 2008; 86:293-301. [PMID: 18756324 DOI: 10.1139/o08-070] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Conjugated linoleic acids (CLA) are isomeric forms of linoleic acid (LA) containing two conjugated sites of unsaturation. The most abundant dietary form of CLA is the cis-9,trans-11 (c-9,t-11) isomer that is found in the fatty tissues and milk of ruminant animals. CLA can also be acquired by ingestion of supplements, which are usually equimolar mixtures of the c-9,t-11 and t-10,c-12 CLA. For more than a decade, the potential for CLA to modify atherosclerosis in animal models has been examined. However, to date, the studies have failed to reach consensus on whether CLA can be effective in reducing the incidence or severity of atherosclerotic lesions, or whether or not plasma lipid and lipoprotein levels can be improved with CLA supplementation. This review will examine the evidence for and against a role for CLA in atherosclerosis, with a focus on the rabbit, the hamster, and the apoE-deficient mouse.
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Affiliation(s)
- Patricia L Mitchell
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada
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McClements DJ, Decker EA, Park Y. Controlling Lipid Bioavailability through Physicochemical and Structural Approaches. Crit Rev Food Sci Nutr 2008; 49:48-67. [DOI: 10.1080/10408390701764245] [Citation(s) in RCA: 282] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tiwari R, Singh V, Barthwal M. Macrophages: An elusive yet emerging therapeutic target of atherosclerosis. Med Res Rev 2008; 28:483-544. [DOI: 10.1002/med.20118] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Lam CK, Chen J, Cao Y, Yang L, Wong YM, Yeung SYV, Yao X, Huang Y, Chen ZY. Conjugated and non-conjugated octadecaenoic acids affect differently intestinal acyl coenzyme A: cholesterol acyltransferase activity. Atherosclerosis 2007; 198:85-93. [PMID: 18078940 DOI: 10.1016/j.atherosclerosis.2007.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 10/26/2007] [Accepted: 11/02/2007] [Indexed: 10/22/2022]
Abstract
We investigated the relative hypocholesterolemic activity of linoleic acid (LA), conjugated linoleic acid (CLA), alpha-linolenic acid (LN) and conjugated linolenic acid (CLN) in hamsters. Five groups of hamsters (n=10 each) were fed either the control diet or one of the four fatty acids-supplemented diets for 6 weeks. Results demonstrated that the four octadecaenoic acids decreased plasma cholesterol differently, with CLA being the most effective. Western blotting and RT-PCR analysis demonstrated that the four octadecaenoic acids had no effect on sterol regulatory element binding protein-2 (SREBP-2), liver X receptor (LXR), 3-hydroxy-3-methylglutary-CoA reductase (HMGR), LDL receptor (LDLR), and cholesterol-7alpha-hydroxylase (CYP7A1). However, the four octadecaenoic acids increased the excretion of fecal neutral sterols with CLA being most effective followed by LN, LA and CLN, suggesting they all differentially affect cholesterol absorption. Dietary CLA was associated with the least intestinal acyl coenzyme A: cholesterol acyltransferase (ACAT) activity followed by LN, LA and CLN in a decreasing trend. Since esterification of cholesterol is catalyzed by intestinal ACAT, and is a rate-limiting step in cholesterol absorption, it was concluded that the varying effects of CLA, LN, LA and CLN on blood cholesterol were mediated, at least in part, by their inhibition on intestinal ACAT activity.
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Affiliation(s)
- Cheuk Kai Lam
- Food & Nutritional Sciences Programme of Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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