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1.
In order to evaluate the effects of fatty acids on immune cell membrane structure and function, it is often necessary to maintain cells in culture. However, cell culture conditions typically reverse alterations in polyunsaturated fatty acid (PUFA) composition achieved by dietary lipid manipulation. Therefore, we hypothesized that T-cells from transgenic mice expressing the Caenorhabditis elegans n-3 desaturase (fat-1) gene would be resistant to the culture-induced loss of n-3 PUFA and, therefore, obviate the need to incorporate fatty acids or homologous serum into the medium. CD4+ T-cells were isolated from (i) control wild type (WT) mice fed a safflower oil-n-6 PUFA enriched diet (SAF) devoid of n-3 PUFA, (ii) fat-1 transgenic mice (enriched with endogenous n-3 PUFA) fed a SAF diet, or (iii) WT mice fed a fish oil (FO) based diet enriched in n-3 PUFA. T-cell phospholipids isolated from WT mice fed FO diet (enriched in n-3 PUFA) and fat-1 transgenic mice fed a SAF diet (enriched in n-6 PUFA) were both enriched in n-3 PUFA. As expected, the mol% levels of both n-3 and n-6 PUFA were decreased in cultures of CD4+ T-cells from FO-fed WT mice after 3 d in culture. In contrast, the expression of n-3 desaturase prevented the culture-induced decrease of n-3 PUFA in CD4+ T-cells from the transgenic mice. Carboxyfluorescein succinidyl ester (CFSE) -labeled CD4+ T-cells from fat-1/SAF vs. WT/SAF mice stimulated with anti-CD3 and anti-CD28 for 3 d, exhibited a reduced (P<0.05) number of cell divisions. We conclude that fat-1-containing CD4+ T-cells express a physiologically relevant, n-3 PUFA enriched, membrane fatty acid composition which is resistant to conventional cell culture-induced depletion.  相似文献   

2.
Newly determined crystal structures of the photosynthetic RC (reaction centre) from two substrains of the non-sulfur purple bacterium Blastochloris viridis strain DSM 133, together with analysis of their gene sequences, has revealed intraspecies evolutionary changes over a period of 14?years. Over 100 point mutations were identified between these two substrains in the four genes encoding the protein subunits of the RC, of which approximately one-fifth resulted in a total of 16 amino acid changes. The most interesting difference was in the M subunit where the change from a leucine residue to glycine in the carotenoid-binding pocket allowed NS5 (1,2-dihydroneurosporene) to adopt a more sterically favoured conformation, similar to the carotenoid conformation found in other related RCs. The results of the present study, together with a high rate of mutations in laboratory bacterial cultures described recently, suggest that bacteria evolve faster than has been generally recognized. The possibility that amino acid changes occur within protein sequences, without exhibiting any immediately observable phenotype, should be taken into account in studies that involve long-term continuous growth of pure bacterial cultures. The Blc. viridis RC is often studied with sophisticated biophysical techniques and changes such as those described here may well affect their outcome. In other words, there is a danger that laboratory-to-laboratory variation could well be due to different groups not realising that they are actually working with slightly different proteins. A way around this problem is suggested.  相似文献   

3.
We have demonstrated that downregulation of proliferation by CD4(+) T-cells in mice fed n-3 PUFA diets is dependent on the involvement of CD28. Therefore, we hypothesized that the balance of co-stimulatory and downregulatory properties of CD28 and CTLA-4, respectively, would be altered by diet. Mice were fed a control corn oil (CO)-enriched diet devoid of n-3 PUFA, or diets enriched with either docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) for 14d. The proliferation of splenic CD4(+) T-cells was suppressed by DHA and EPA following stimulation with anti-CD3 and anti-CD28. Surprisingly, the number of surface CD28 molecules was not reduced in activated CD4(+) T-cells from either group of n-3 PUFA-fed mice. However, in mice fed EPA, CTLA-4 protein levels were enhanced significantly 72 h post-activation (P<0.01). Therefore, we conclude that dietary EPA may suppress CD4(+) T-cell activation by enhancing the downregulatory co-receptor CTLA-4, while not altering the levels of CD28.  相似文献   

4.
The biochemistry of n-3 polyunsaturated fatty acids   总被引:27,自引:0,他引:27  
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5.
The consequences of a dietary n-3 PUFA supply was investigated on the blood pressure (BP) increase elicited by left renal artery stenosis in rats distributed in 3 groups (n = 8) fed for 8 weeks a semi-purified diet either as control diet or enriched diets (docosahexaenoic acid, DHA, or eicosapentaenoic acid, EPA). The PUFA intake induced large alterations in heart and kidney phospholipid fatty acid profile, but did not influence body weight, cardiac hypertrophy, renal left atrophy and right hypertrophy. Within 4 weeks, BP raised from 120-180 +/- 2 mm Hg in the control group, but only to 165 +/- 3 mm Hg in the n-3 PUFA groups. After stabilization of BP in the 3 groups, the rats received a short administration of increasing dose of perindopril. The lower dose (0.5 mg/kg) moderately decreased BP only in the control group. With higher doses (1, 5 and 10 mg/kg) BP was normalized in the 3 groups, with a higher amplitude of the BP lowering effect in the control group. A moderate n-3 PUFA intake can contribute to prevent the development of peripheral hypertension in rats by a mechanism that may involve angiotensin converting enzyme.  相似文献   

6.
Dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) is regarded as beneficial for the prevention and treatment of atherosclerosis and thrombosis and chronic inflammatory diseases like rheumatoid arthritis and psoriasis. It may be possible to treat some acute diseases like acute myocardial infarction or acute rejection of grafted organs if it is possible to make n-3 PUFA take effect quickly (in hours instead of days). Three sets of experiments were done. In Experiment 1, emulsion of trieicosapentaenoyl-glycerol (EPA-TG) and tridocosahexaenoyl-glycerol was infused through rabbit ear veins, and the leukotriene B4/B5 production from polymorphonuclear leukocytes was measured at different time points by high-performance liquid chromatography. In Experiment 2, delayed type hypersensitivity (DTH) of mice was measured with sheep red blood cells as an antigen. Pure n-3 PUFA emulsions or a control solution were infused through tail veins just before the second challenge of the antigen. DTH was measured 24 hr after the second challenge. In Experiment 3, human natural killer cell activity was measured using K562 target cells before and after the infusion of pure EPA-TG emulsion to an antecubital vein. Leukotriene B4 production by rabbit polymorphonuclear leukocytes was depressed by 40% by EPA-TG infusion. DTH was suppressed almost completely by n-3 PUFA infusion. Natural killer cell activity was suppressed almost completely by EPA-TG infusion in 8 hr. DTH, natural killer cell activity, and leukotriene B4 production are probably related to acute rejection of grafted organs.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
n-3 polyunsaturated fatty acids and the cardiovascular system   总被引:7,自引:0,他引:7  
n-3 Polyunsaturated fatty acids, mainly those contained in fish oils, are candidates for inclusion in secondary prevention programmes for coronary heart disease, based on the results of recent randomized trials in humans. Marine n-3 polyunsaturated fatty acids retard coronary atherosclerosis and appear to prevent fatal arrhythmias; and they decrease mortality subsequent to myocardial infarction.  相似文献   

8.
A voltage-gated, small, persistent Na+ current (INa) has been shown in mammalian cardiomyocytes. Hypoxia potentiates the persistent INa that may cause arrhythmias. In the present study, we investigated the effects of n-3 polyunsaturated fatty acids (PUFAs) on INa in HEK-293t cells transfected with an inactivation-deficient mutant (L409C/A410W) of the -subunit (hH1) of human cardiac Na+ channels (hNav1.5) plus 1-subunits. Extracellular application of 5 µM eicosapentaenoic acid (EPA; C20:5n-3) significantly inhibited INa. The late portion of INa (INa late, measured near the end of each pulse) was almost completely suppressed. INa returned to the pretreated level after washout of EPA. The inhibitory effect of EPA on INa was concentration dependent, with IC50 values of 4.0 ± 0.4 µM for INa peak (INa peak) and 0.9 ± 0.1 µM for INa late. EPA shifted the steady-state inactivation of INa peak by –19 mV in the hyperpolarizing direction. EPA accelerated the process of resting inactivation of the mutant channel and delayed the recovery of the mutated Na+ channel from resting inactivation. Other polyunsaturated fatty acids, docosahexaenoic acid, linolenic acid, arachidonic acid, and linoleic acid, all at 5 µM concentration, also significantly inhibited INa. In contrast, the monounsaturated fatty acid oleic acid or the saturated fatty acids stearic acid and palmitic acid at 5 µM concentration had no effect on INa. Our data demonstrate that the double mutations at the 409 and 410 sites in the D1–S6 region of hH1 induce inactivation-deficient INa and that n-3 PUFAs inhibit mutant INa. human cardiac sodium channel  相似文献   

9.
The molecular properties of immunosuppressive n-3 polyunsaturated fatty acids (PUFA) have not been fully elucidated. Using CD4(+) T cells from wild-type control and fat-1 transgenic mice (enriched in n-3 PUFA), we show that membrane raft accumulation assessed by Laurdan (6-dodecanoyl-2-dimethyl aminonaphthalene) labeling was enhanced in fat-1 cells following immunological synapse (IS) formation by CD3-specific Ab expressing hybridoma cells. However, the localization of protein kinase Ctheta, phospholipase Cgamma-1, and F-actin into the IS was suppressed. In addition, both the phosphorylation status of phospholipase Cgamma-1 at the IS and cell proliferation as assessed by CFSE labeling and [(3)H]thymidine incorporation were suppressed in fat-1 cells. These data imply that lipid rafts may be targets for the development of dietary agents for the treatment of autoimmune and chronic inflammatory diseases.  相似文献   

10.
The fatty acid profile of hepatocytes and adipocytes is determined by the composition of the dietary lipids. It remains unclear which fatty acid components contribute to the development or reduction of insulin resistance. The present work examined the fatty acid composition of both tissues in sucrose-induced obese rats receiving fish oil to determine whether the effect of dietary (n-3) polyunsaturated fatty acids (PUFAs) on the reversion of metabolic syndrome in these rats is associated to changes in the fatty acid composition of hepatocyte and adipocyte membrane lipids. Animals with metabolic syndrome were divided into a corn–canola oil diet group and a fish oil diet group, and tissues fatty acids composition were analyzed after 6 weeks of dietary treatment. Fatty acid profiles of the total membrane lipids were modified by the fatty acid composition of the diets fed to rats. N-3 PUFAs levels in animals receiving the fish oil diet plus sucrose in drinking water were significantly higher than in animals under corn–canola oil diets. It is concluded that in sucrose-induced obese rats, consumption of dietary fish oil had beneficial effects on the metabolic syndrome and that such effects would be conditioned by the changes in the n-3 PUFAs composition in hepatic and adipose tissues because they alter membrane properties and modify the type of substrates available for the production of active lipid metabolites acting on insulin resistance and obesity.  相似文献   

11.
The study was carried out on 42 breeder couples (42 males and 42 females) of European brown hare (Lepus europaeus), divided into three groups fed three different experimental diets (14 couples/treatment). Two diets were supplemented with n-3 and n-6 polyunsaturated fatty acids (PUFAs; 2% of linseed oil and soybean oil, respectively) and were compared with a control diet supplemented with a monounsaturated fatty acids (2% of olive oil). During the experimental period (from 15 April to 30 September), the following parameters were recorded: days from the beginning of trial to the first parturition, parturition interval, number of parturitions, number of leverets born (alive and dead), dead during suckling, the total number of leverets weaned and feed intake per cage (of males, females and leverets until weaning). Feed intake was not influenced by treatments. In hares fed n-3 and n-6 diets, the days from the beginning of the trial to the first parturition and the parturition interval were similar and were lower compared with control group (63.1 v. 70.6 days, and 37.8 v. 40.9 days, respectively; P < 0.05). Hares from n-6 group had a higher (P < 0.05) number of parturitions per cage during the experimental period than the n-3 and control group that showed a similar value (3.00 v. 2.36, respectively). The total number of leverets born per cage and parturition in n-6 and n-3 groups increased with respect to those fed control diet (P < 0.05). The leverets' mortality rate at birth was higher in n-6 than in n-3 and control group (3.50 v. 2.17, respectively; P < 0.05). In control group, leverets' mortality rate during suckling was lower with respect to n-3 (P < 0.05) and n-6 (P < 0.05), showing the highest value for the latter (P < 0.05). In spite of this higher mortality, the number of leverets weaned per cage and parturition was higher (P < 0.05) in n-6 compared with n-3 group, being the latter higher than the control group (3.12, 2.79 and 2.43, respectively). Our results show that the dietary PUFAs, particularly n-6 supplementation, have a positive influence on the reproductive performances of the European brown hare.  相似文献   

12.
We investigated the mechanisms whereby omega‐3 and ‐6 polyunsaturated fatty acids (PUFAs) cause cell death of mouse thymocytes using flow cytometry, focusing on the respective roles of intracellular calcium concentration, [Ca2+]i and reactive oxygen species (ROS). We applied the C‐22, 20, and 18 carbon omega‐3 (DHA, EPA, ALA) and omega‐6 (DTA, ARA, and LNA) fatty acids to isolated thymocytes and monitored cell death using the DNA‐binding dye, propidium iodide. When applied at 20 µM concentration, omega‐3 fatty acids killed thymocytes over a period of 1 h with a potency of DHA > EPA > ALA. The omega‐6 PUFAs were more potent. The C18 omega‐6 fatty acid, LNA, was the most potent, followed by DHA and ARA. Cell death was always accompanied by an increase in the levels of [Ca2+]i and ROS. Both increases were in proportion to the potency of the PUFAs in inducing cell death. Removing extracellular calcium did not prevent the elevation in [Ca2+]i nor cell death. However, the intracellular calcium chelator, BAPTA, almost totally reduced both the elevation in [Ca2+]i and cell death, while vitamin E reduced the elevation in ROS and cell death. BAPTA also prevented the elevation in ROS, but vitamin E did not prevent the elevation in [Ca2+]i. Thapsigargin, which depletes endoplasmic reticulum calcium, blocked the elevation in [Ca2+]i, but CCCP, a mitochondrial calcium uptake inhibitor, did not. These results suggest that the six PUFAs we studied kill thymocytes by causing release of calcium from endoplasmic reticulum, which causes release of ROS from mitochondria which leads to cell death. J. Cell. Physiol. 225: 829–836, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

13.
Regulation of polyunsaturated fatty acid (PUFA) biosynthesis in proliferating and NGF-differentiated PC12 pheochromocytoma cells deficient in n-3 docosahexaenoic acid (DHA 22:6n-3) was studied. A dose- and time-dependent increase in eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5n-3) and DHA in phosphatidylethanolamine (PtdEtn) and phosphatidylserine (PtdSer) glycerophospholipids (GPL) via the elongation/desaturation pathway following alpha-linolenic acid (ALA, 18:3n-3) supplements was observed. That was accompanied by a marked reduction of eicosatrienoic acid (Mead acid 20:3n-9), an index of PUFA deficiency. EPA supplements were equally effective converted to 22:5n-3 and 22:6n-3. On the other hand, supplements of linoleic acid (LNA, 18:2n-6) were not effectively converted into higher n-6 PUFA intermediates nor did they impair elongation/desaturation of ALA. Co-supplements of DHA along with ALA did not interfere with 20:5n-3 biosynthesis but reduced further elongation to 22-hydrocarbon PUFA intermediates. A marked decrease in the newly synthesized 22:5n-3 and 22:6n-3 following ALA or EPA supplements was observed after nerve growth factor (NGF)-induced differentiation. NGF also inhibited the last step in 22:5n-6 formation from LNA. These results emphasize the importance of overcoming n-3 PUFA deficiency and raise the possibility that growth factor regulation of the last step in PUFA biosynthesis may constitute an important feature of neuronal phenotype acquisition.  相似文献   

14.
Ras proteins are critical regulators of cell function, including growth, differentiation, and apoptosis, with membrane localization of the protein being a prerequisite for malignant transformation. We have recently demonstrated that feeding fish oil, compared with corn oil, decreases colonic Ras membrane localization and reduces tumor formation in rats injected with a colon carcinogen. Because the biological activity of Ras is regulated by posttranslational lipid attachment and its interaction with stimulatory lipids, we investigated whether docosahexaenoic acid (DHA), found in fish oil, compared with linoleic acid (LA), found in corn oil, alters Ras posttranslational processing, activation, and effector protein function in young adult mouse colon cells overexpressing H-ras (YAMC-ras). We show here that the major n-3 polyunsaturated fatty acid (PUFA) constituent of fish oil, DHA, compared with LA (an n-6 PUFA), reduces Ras localization to the plasma membrane without affecting posttranslational lipidation and lowers GTP binding and downstream p42/44(ERK)-dependent signaling. In view of the central role of oncogenic Ras in the development of colon cancer, the finding that n-3 and n-6 PUFA differentially modulate Ras activation may partly explain why dietary fish oil protects against colon cancer development.  相似文献   

15.
Studies on the metabolic fate of n-3 polyunsaturated fatty acids   总被引:3,自引:0,他引:3  
Several different processes involved in the metabolic fate of docosahexaenoic acid (DHA, C22:6n-3) and its precursor in the biosynthesis route, C24:6n-3, were studied. In cultured skin fibroblasts, the oxidation rate of [1-14C] 24:6n-3 was 2.7 times higher than for [1-14C]22:6n-3, whereas [1-14C]22:6n-3 was incorporated 7 times faster into different lipid classes than was [1-14C]24:6n-3. When determining the peroxisomal acyl-CoA oxidase activity, similar specific activities for C22:6(n-3)-CoA and C24:6(n-3)-CoA were found in mouse kidney peroxisomes. Thioesterase activity was measured for both substrates in mouse kidney peroxisomes as well as mitochondria, and C22:6(n-3)-CoA was hydrolyzed 1.7 times faster than C24:6(n-3)-CoA. These results imply that the preferred metabolic fate of C24:6(n-3)-CoA, after its synthesis in the endoplasmic reticulum (ER), is to move to the peroxisome, where it is beta-oxidized, producing C22:6(n-3)-CoA. This DHA-CoA then preferentially moves back, probably as free fatty acid, to the ER, where it is incorporated into membrane lipids.  相似文献   

16.
Bordetella pertussis adenylate cyclase (CyaA) is an invasive bacterial toxin that delivers its N-terminal catalytic domain into the cytosol of eukaryotic cells bearing the alpha(M)beta(2) integrin (CD11b/CD18), such as myeloid dendritic cells. This allows use of engineered CyaA for targeted delivery of CD8(+) T cell epitopes into the MHC class I pathway of APC and induction of robust and protective cytotoxic responses. In this study, we demonstrate that CyaA can efficiently codeliver both a CD8(+) T cell epitope (OVA(257-264)) and a CD4(+) T cell epitope (MalE(100-114)) into, respectively, the conventional cytosolic or endocytic routes of processing of murine bone marrow-derived dendritic cells. Upon CyaA delivery, a strong potentiation of the MalE(100-114) CD4(+) T cell epitope presentation is observed as compared with the MalE protein, which depends on CyaA interaction with its CD11b receptor and its subsequent clathrin-mediated endocytosis. In vivo, CyaA induces strong and specific Th1 CD4(+) and CD8(+) T cell responses against, respectively, the MalE(100-114) and OVA(257-264) epitopes. These results underscore the potency of CyaA for design of new vaccines.  相似文献   

17.
In the present study, to investigate the contribution of n-3 PUFAs in the oxidative modification of protein in vivo, we characterize the covalent binding of 4-hydroxy-2-hexenal (HHE), a potent cytotoxic aldehyde originating from the peroxidation of n-3 PUFAs, to protein and describe the production of this aldehyde in oxidatively modified LDL and in human atherosclerotic lesions. Upon incubation with BSA, HHE was rapidly incorporated into the protein and generated the protein-linked carbonyl derivative, a potential marker of oxidatively modified proteins under oxidative stress. To detect the protein-bound HHE in vivo, we raised monoclonal antibody HHE53 (MAb HHE53) directed to the HHE-modified protein and identified the Michael addition-type HHE-histidine adduct as the major epitope. This antibody reacted with copper-oxidized LDL, suggesting that HHE was produced during the oxidative modification of LDL. In addition, we demonstrated that the materials immunoreactive to MAb HHE53 indeed constituted the atherosclerotic lesions, in which intense positivity was associated primarily with macrophage-derived foam cells. The results of this study suggest that the reaction between oxidized n-3 PUFAs and protein might represent a process common to the formation of degenerative proteins during aging and its related diseases.  相似文献   

18.
The longitudinal relationship between dietary n-6 to n-3 PUFAs ratio and periodontal disease in 235 Japanese subjects for whom data were available for the years 2003-2006 was investigated. PUFAs intake was assessed at baseline with a brief-type self-administered diet history questionnaire. Full-mouth periodontal status, measured as the clinical attachment level (CAL), was recorded at baseline and once a year for 3 years. The number of teeth with a change in the loss of CAL ≥3 mm at any site over a year was calculated as ‘periodontal disease events’. Poisson regression analysis was conducted, with dietary n-6 to n-3 PUFAs ratio as the main predictor, to estimate its influence on periodontal disease events.A high dietary n-6 to n-3 PUFAs ratio was significantly associated with greater number of periodontal disease events. The findings suggest the dietary n-6 to n-3 PUFAs ratio is associated with periodontal disease among older Japanese.  相似文献   

19.
20.
Adipocyte–macrophage cross-talk propagates immune responses in obese adipose tissue (AT). Long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) mitigate inflammation, partly through up-regulation of adiponectin; however, specific mechanisms are unclear. We determined if adipocyte–macrophage cross-talk could be mitigated by dietary LC n-3 PUFA and if this was dependent on adiponectin-mediated signaling. We utilized an in vitro co-culture model mimicking the ratio of adipocytes:macrophages in obese AT, whereby 3T3-L1 adipocytes were co-cultured with splenic CD11b+ macrophages from C57BL/6 mice fed high-fat control (HF-CON; 34% w/w fat) or fish oil diets (HF-FO; 34% w/w fat containing 7.6% w/w FO), as well as mice fed low-fat control (LF-CON; 10% w/w fat) or FO diets (LF-FO; 10% w/w fat containing 3% w/w FO). Co-culture conditions tested effects of soluble mediator-driven mechanisms (trans-well system), cell contact and low-dose lipopolysaccharide (LPS) mimicking acute or chronic inflammatory conditions. HF-FO macrophages from acute LPS-stimulated trans-well co-cultures had decreased mRNA expression of Casp1, Il1β and Il18, as well as cellular caspase-1 activity compared to HF-CON macrophages (P  .05). Moreover, adipocytes from acute LPS-stimulated HF-FO co-cultures had decreased caspase-1 activity and decreased IL-1β/IL-18 levels following chronic LPS pretreatment compared to HF-CON co-cultures (P  .05). Additionally, in contact co-cultures with adiponectin-neutralizing antibody, the FO-mediated modulation of NFκB activity and decrease in phosphorylated p65 NFκB, expression of NLRP3 inflammasome genes, M1 macrophage marker genes and inflammatory cytokine/chemokine secretion were controlled partly through adiponectin, while cellular caspase-1 activity and IL-1β/1L-18 levels were decreased independently of adiponectin (P  .05). LC n-3 PUFA may decrease the intensity of adipocyte–macrophage cross-talk to mitigate obesity-associated pathologies.  相似文献   

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