| Dietary modification has led to an imbalance in the n-6/n-3 polyunsaturated fatty acids(PUFAs)ratio with an increase in n-6 fatty acids along with a marked reduction in n-3 fatty acids in diets,resulting in a high n-6/n-3 PUFA ratio.The n-6/n-3 PUFAs ratio reached 20-30:1 in today’s typical Western diets.The incidence of inflammatory diseases such cardiovascular disease increased with the great changes in dietary patterns.It is well known that lipid metabolism,inflammation,oxidative stress,and endothelial function play important roles in the pathogenesis of cardiovascular diseases(CVD),which could be affected by the dietary n-6/n-3 PUFAs ratio.Postprandial hyperlipidemia is considered to be a substantial risk factor for atherosclerosis.The n-6 and n-3 PUFAs play an important role in organisms,and they compete each other on the function.Currently,the effects of the dietary n-6/n-3 PUFAs ratio on risk factors for CVD have not been well investigated,such as lipid metabolism,inflammation,oxidative stress,and endothelial function.We investigated the metabolic response to high fat meals only differing the ratio of n-6 and n-3 PUFAs in hypertriacylglycerolemia(HTG)subjects,and also studied the metabolic response to high fat meals only differing the ratio of n-6 and n-3 PUFAs in HTG and normal control(NC)rats.The intervention experiment in rats were also carried out in order to study the effect of different n-6/n-3 PUFAs ratio on lipid metabolism,inflammation,oxidative stress,and endothelial function.Endothelial cells were used to explore their possible mechanisms.The research includes the following five parts:Part I:Effects of the different n-6/n-3 PUFAs ratio on postprandial lipid metabolism,inflammation,oxidative stress,and endothelial function in hypertriacylglycerolemia patientsObjective:to study the effects of different n-6/n-3 PUFAs ratio on postprandial lipid metabolism,oxidative stress,and endothelial function in HTG subjects.Methods:45 times of the oral fat tolerance test were taken on 35 HTG subjects.According to the n-6/n-3 PUFAs ratio in test meals,the subjects were divided into three groups:1:1,5:1 and 10:1.Blood samples were collected for 8 hours after meals to measure triglyceride(TG),total cholesterol(TC),high-density lipoprotein cholesterol(HDL-C),glucose,insulin,vascular endothelial growth factor A(VEGF-A),oxidized low-density lipoprotein(ox-LDL),myeloperoxidase(MPO),and 8-Iso-prostaglandin 2a(8-iso-PGF2a).Results:According to repeated-measures ANO VA,the postprandial response of TG was not significantly different among groups.There were time change tendency on postprandial TG,TC,GLU,INS,VEGF-A,ox-LDL levels.However,there were no time change tendency on postprandial HDL-C,8-iso-PGF2αand MPO levels.The postprandial peak response of IL-6 in the 10:1 group was higher than the 5:1 group.The maximum changes of the postprandial ox-LDL levels in the 10:1 group were higher than the 5:1 group.The 10:1 group significantly increased the 1-hour postprandial ox-LDL levels compared to the 1:1 and 5:1 groups.The 2-hour postprandial VEGF-A levels in the 1:1 group were lower than the 5:1 and 10:1 groups and the 4-hour postprandial VEGF-A levels in the 1:1 group were lower than the 5:1 group.Conclusions:The postprandial response of lipid,glucose,and oxidative stress was not significantly different among groups,but the high-fat meals with high n-6/n-3 PUFAs ratio of 10:1 could increase postprandial oxidative stress at some time points after meals in HTG subjects.Part Ⅱ:Effects of the different n-6/n-3 PUFAs ratio on postprandial lipid and inflammatory cytokines metabolism in NC and HTG ratsObjective:to study the effects of different n-6/n-3 PUFAs ratio on postprandial lipid and inflammatory cytokines metabolism in NC and HTG rats.Methods:The HTG rat model was established by high fat diets.According to the n-6/n-3 PUFAs ratio in the diets,the two rats groups were divided into four subgroups:1:1,5:1,10:1 and 20:1.Blood samples were collected for 6 hours after meals to measure TG,TC,HDL,glucose and inflammatory cytokines including IL-6,malondialdehyde(MDA)and reactive oxygen species(ROS).Results:According to repeated-measures ANOVA,there were time change tendency on postprandial TG,TC,HDL-C,GLU,IL-6,MDA,ROS,von Willebrand factor(vWF)levels.The postprandial response of TNF-αwas not significantly different among subgroups in NC groups,but the postprandial response of TNF-αin the 5:1 subgroup was lower than the 1:1 and 10:1 subgroups in HTG groups.The postprandial response of TG,TC and HDL was not significantly different among subgroups in NC or HTG groups,but high n-6/n-3 PUFAs ratio increased the difference of postprandial lipid and endothelial function between HTG rats and NC rats.The postprandial IL-6,MDA,ROS,vWF levels was not significantly different between NC rats and HTG rats in all the same subgroups.The postprandial response of MDA in the 1:1 subgroup was higher than the 5:1 subgroup and 10:1 subgroup in NC rats.The postprandial response of MDA in the 1:1 subgroup and 20:1 subgroup were higher than the 5:1 subgroup and 10:1 subgroup in HTG rats.The postprandial response of TNF-α in the 5:1 subgroup was lower than the 1:1 subgroup and 10:1 subgroup in HTG rats.The 6-hour postprandial vWF level was higher in HTG rats than NC rats in 20:1 subgroups.Conclusions:High-fat diet increased postprandial inflammation and oxidative stress,and high n-6/n-3 PUFAs ratio of 20:1 or low n-6/n-3 PUFAs ratio of 1:1 increased postprandial response and oxidative stress.High n-6/n-3 PUFAs ratio strengthened the difference of postprandial lipid and endothelial function between HTG rats and NC rats.PartⅢ:Effects of Diets with Different n-6/n-3 PUFAs Ratio on Serum Lipid Metabolism,Inflammation,Oxidative stress and endothelial function in Rats Fed High-Fat DietObjective:To investigate effects of diets with different n-6/n-3 PUFAs ratio on serum lipid profiles,inflammation,oxidative stress and endothelial function in rats fed high-fat diets.Methods:Male SD rats were randomly divided into seven groups and were fed normal control diet,high-fat lard diet,high-fat group,high-fat diets with n-6/n-3 PUFAs ratio of 1:1,5:1,10:1 and 20:1 for 12weeks.The levels of serum TG.TC,HDL-C,LDL-C,IL-6,GLU,FFA,hypersensitive C-reactive protein(CRP),TNF-α,8-iso-PGF2α,Ox-LDL,E-selectin(ES)and vWF were measured.Results:The levels of serum non-HDL-C in the high-fat group were significantly higher than those in the 1:1,5:1 and 10:1 groups.Compared with the 20:1 group,the 1:1 and 5:1 groups displayed lower IL-6,ox-LDL and NOX4 levels.The levels of serum TNF-a in the 10:1 and 20:1 groups were significantly higher than those in the 1:1 and 5:1 groups.The 1:1 group significantly decreased the level of serum CRP,8-iso-PGF2a and lipid peroxide(LPO)compared to the 20:1 group.The levels of serum vWF in the 20:1 group were significantly higher than those in the 1:1,5:1 and 10:1 groups.The levels of serum ES in the 20:1 group were significantly higher than those in other groups.Conclusions:Low n-6/n-3 PUFAs ratio(1:1 and 5:1)had a beneficial effect on cardiovascular risk factors by enhancing favorable lipid profiles,having anti-inflammatory and anti-oxidative stress effects,and improving endothelial function.High n-6/n-3 PUFAs ratio(20:1 and 10:1)had adverse effects.Our results indicated that low n-6/n-3 PUFAs ratio exerted beneficial cardiovascular effects.Part iv:Effects of Different n-6/n-3 PUFAs ratio on inflammation,oxidative stress,endothelial function and their mechanism in endothelial cellObjective:To investigate effects of different n-6/n-3 PUFAs ratio on inflammation,oxidative stress,endothelial function and their mechanism in endothelial cell.Methods:EA.hy926 cells were used to study the effects of different n-6/n-3 PUFAs ratio on inflammation,oxidative stress,endothelial function and the related gene expression.Results:In the concentration of 20μmol/L,the expression levels of NOX4 in the 1:1 and 10:1 groups were significantly lower than the 10:1 and 20:1 groups;The expression levels of Toll-like-receptors 4(TLR4),nitric oxide synthase(iNOS),endothelial nitric oxide synthase(eNOS)and protein kinase C(PKC)increased and the expression levels of NOX4 decreased in the 1:1 group compared with high n-6/n-3 PUFAs ratio;The expression levels of PKC,iNOS and eNOS decreased and the expression levels of TLR4 increased in the 20:1 group compared with low n-6/n-3 PUFAs ratio.In the concentration of 100μmol/L,the expression levels of nuclear transcription factor-kappa B(NF-κB),iNOS,eNOS and PKC increased in the 1:1 group compared with high n-6/n-3 PUFAs ratio;The expression levels of TLR4 increased in the 20:1 group compared with low n-6/n-3 PUFAs ratio.In the concentration of 20μmol/L,the 8-iso-PG levels in the 1:1 group were significantly lower than the control and 10:1 groups;The vWF levels in the 20:1 group were significantly higher than other groups and the vWF levels in the 5:1 group were significantly lower than the other groups except the 1:1 group.In the concentration of 100μmol/L,the IL-6,TNF-a and 8-iso-PG levels were higher in the 1:1 group than the 10:1 group,the 5:1 and 1:1 groups displayed lower vWF levels than the 20:1 and 10:1 groups:The NO and NO/ET-1 levels were higher in the 5:1 and 10:1 groups than the 1:1 and 20:1 groups.Conclusion:Under the low concentration of fatty acids,low n-6/n-3 PUFAs ratio(1:1 and 5:1)decreased the oxidative stress and improved vascular endothelial function;high n-6/n-3 PUFAs ratio(10:1 and 20:1)increased inflammation and oxidative stress and damaged vascular indothelial function.Under the high concentration of fatty acids,n-6/n-3 PUFAs ratio(5:1 and 10:1)reduced inflammation and oxidative stress,increased NO level and improved vascular endothelial function compared with low n-6/n-3 PUFAs ratio of 1:1 or high n-6/n-3 PUFAs ratio of 20:1.The effects of n-3PUFAs and n-6PUFAs on inflammation,oxidative stress,endothelial function and the related gene expression were affected both by n-6/n-3 PUFAs ratio and the concentration of PUFAs,and the mechanism may be through adjusting the TLRs/NF-κB inflammatory signaling pathways and NOX signaling pathways. |
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