Plasma polyunsaturated fatty acid profile and delta-5 desaturase activity are altered in patients with type 2 diabetes

Objective

The association between imbalance of polyunsaturated fatty acids (PUFAs), especially low plasma n-3 to n-6 PUFA ratio, and risk of cardiovascular diseases is well known. A balance of plasma PUFAs is determined not only by dietary fatty acid intake, but also by the endogenous fatty acid metabolism, which could be dysregulated by diabetes. In this study, we investigated the plasma n-3 and n-6 PUFA profile and fatty acid desaturase activity in patients with type 2 diabetes (T2D).

Materials/Methods

The subjects were 396 patients with T2D and 122 healthy controls. Plasma eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and dihomo-γ-linolenic acid (DGLA) levels were measured by capillary gas chromatography.

Results

Plasma DHA, AA, and DGLA levels were significantly higher, and EPA levels tended to be lower in patients with T2D than in the controls. Patients with T2D also exhibited significantly lower EPA/AA, DHA/AA, and (EPA + DHA)/AA ratios, and a higher AA/DGLA ratio than the controls. Multiple regression analyses, including age, sex, body mass index, and metabolic parameters in the total population, revealed that the presence of T2D was independently associated with elevated plasma DHA, AA, and DGLA levels and decreased EPA/AA, DHA/AA, and (EPA + DHA)/AA ratios. Furthermore, T2D was independently and positively related to the AA/DGLA ratio, which serves as an estimate of delta (Δ)-5 desaturase activity.

Conclusions

Elevated plasma AA levels and decreased n-3 PUFA/AA ratios in T2D are attributable, at least partly, to Δ5 desaturase activation.     

Interleukin-33 as a marker of disease activity in rheumatoid factor positive polyarticular juvenile idiopathic arthritis

Objective: To investigate clinical usefulness of serum interleukin (IL)-33 levels as an indicator of disease activity in juvenile idiopathic arthritis (JIA).

Methods: We measured serum levels of IL-33 in 39 patients with JIA, including 7 patients with rheumatoid factor positive poly-JIA (RF?+?poly-JIA), 8 patients with RF negative poly-JIA (RF-poly-JIA), 20 patients with oligoarticular JIA (Oligo-JIA), 4 patients with enthesitis-related arthritis (ERA) and 30 age-matched healthy controls. Furthermore, we determined their correlation with measures of disease activity.

Results: Serum IL-33 levels in patients with RF?+?poly-JIA were significantly elevated compared to those in patients with RF-poly-JIA, oligo-JIA and HC. Serum IL-33 levels in patients with RF-poly-JIA, oligo-JIA and ERA were not elevated compared to those in HC. Serum IL-33 levels in RF?+?poly-JIA patients normalized in remission phase. Serum IL-33 levels correlated positively with RF in patients with RF?+?poly-JIA.

Conclusions: These results indicate that serum IL-33 levels in RF?+?poly-JIA patients correlated with disease activity, suggesting a potential role of IL-33 as a promising indicator of disease activity.     

Relationship of plasma polyunsaturated fatty acids to circulating inflammatory markers

AIMS: Persons with high intake of polyunsaturated fatty acids (PUFAs) have lower cardiovascular morbidity and mortality. The protective effect of PUFAs is mediated by multiple mechanisms, including their antiinflammatory properties. The association of physiological PUFA levels with pro- and antiinflammatory markers has not been established. METHODS AND RESULTS: In 1123 persons (aged 20-98 yr), we examined the relationship between relative concentration of fatty acids in fasting plasma and level of inflammatory markers. Adjusting for age, sex, and major confounders, lower arachidonic and docosahexaenoic acids were associated with significantly higher IL-6 and IL-1ra and significantly lower TGFbeta. Lower alpha-linolenic acid was associated with higher C-reactive protein and IL-1ra, and lower eicosapentaenoic acid was associated with higher IL-6 and lower TGFbeta. Lower docosahexaenoic acid was strongly associated with lower IL-10. Total n-3 fatty acids were associated with lower IL-6 (P = 0.005), IL-1ra (P = 0.004), and TNFalpha (P = 0.040) and higher soluble IL-6r (P < 0.001), IL-10 (P = 0.024), and TGFbeta (P = 0.0012). Lower n-6 fatty acid levels were significantly associated with higher IL-1ra (P = 0.026) and lower TGFbeta (P = 0.014). The n-6 to n-3 ratio was a strong, negative correlate of IL-10. Findings were similar in participants free of cardiovascular diseases and after excluding lipids from covariates. CONCLUSIONS: In this community-based sample, PUFAs, and especially total n-3 fatty acids, were independently associated with lower levels of proinflammatory markers (IL-6, IL-1ra, TNFalpha, C-reactive protein) and higher levels of antiinflammatory markers (soluble IL-6r, IL-10, TGFbeta) independent of confounders. Our findings support the notion that n-3 fatty acids may be beneficial in patients affected by diseases characterized by active inflammation.     

Aging decreases rate of docosahexaenoic acid synthesis-secretion from circulating unesterified α-linolenic acid by rat liver

Docosahexaenoic acid (DHA, 22:6n-3), an n-3 polyunsaturated fatty acid (PUFA) found at high concentrations in brain and retina and critical to their function, can be obtained from fish products or be synthesized from circulating α-linolenic acid (α-LNA, 18:3n-3) mainly in the liver. With aging, liver synthetic enzymes are reported reduced or unchanged in the rat. To test whether liver synthesis-secretion of DHA from α-LNA changes with age, we measured whole-body DHA conversion coefficients and rates in unanesthetized adult male Fischer-344 rats aged 10, 20, or 30 months, fed an eicosapentaenoic acid (EPA, 20:5n-3)- and DHA-containing diet. Unesterified [U- ¹³?C]α-LNA bound to albumin was infused intravenously for 2 h, while [¹³?C]-esterified n-3 PUFAs were measured in arterial plasma, as were unlabeled unesterified and esterified PUFA concentrations. Plasma unesterified n-3 PUFA concentrations declined with age, but esterified n-3 PUFA concentrations did not change significantly. Calculated conversion coefficients were not changed significantly with age, whereas synthesis-secretion rates (product of conversion coefficient and unesterified plasma α-LNA concentration) of esterified DHA and n-3 DPA were reduced. Turnovers of esterified n-3 PUFAs in plasma decreased with age, whereas half-lives increased. The results suggest that hepatic capacity to synthesize DHA and other n-3 PUFAs from circulating α-LNA is maintained with age in the rat, but that reduced plasma α-LNA availability reduces net synthesis-secretion. As unesterified plasma DHA is the form that is incorporated preferentially into brain phospholipid, its reduced synthesis may be deleterious to brain function in aged rats.     

Relation of long chain n-3 polyunsaturated fatty acid intake to serum high density lipoprotein cholesterol among Japanese men in Japan and Japanese-American men in Hawaii: the INTERLIPID study

Epidemiologic evidence shows an inverse relationship between fish consumption and coronary heart disease (CHD) mortality. Associations between dietary intake of long chain n-3 polyunsaturated fatty acids (PUFA) and serum high density lipoprotein (HDL) cholesterol concentration are unknown. In this study, the association between n-3 PUFA (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA)) intake and serum HDL cholesterol among Japanese men and women in Japan and Hawaii was examined. The study population consisted of Japanese ancestries from five research centers of the International Study of Macronutrients and Blood Pressure (INTERMAP) study, in Japan and Hawaii (672 men and 676 women), surveyed between 1996 and 1998. Four 24-h dietary recalls and one set of serum lipid measurements were performed. For men, n-3 PUFA intake and HDL cholesterol were higher in Japan than in Hawaii (n-3 PUFA: 1.32 g/day versus 0.47 g/day, p<0.001). For women, n-3 PUFA intake was higher in Japan than in Hawaii (p<0.001) but HDL cholesterol was not significantly different (p=0.752). After adjustment for age, body mass index, physical activity, number of cigarettes per day, alcohol intake, and hormone replacement therapy (for women), n-3 PUFA intake was positively associated with serum HDL cholesterol in men (4.6 mg/dl higher HDL cholesterol with 1%kcal higher n-3 PUFA intake, p=0.011). This association was not observed in women. This positive association of dietary n-3 PUFA with serum HDL cholesterol may partially explain the low mortality from CHD among Japanese men.     

Maternal plasma polyunsaturated fatty acid levels during pregnancy and childhood lipid and insulin levels

Background and aims

Maternal polyunsaturated fatty acid (PUFA) levels are associated with cord blood lipid and insulin levels. Not much is known about the influence of maternal PUFAs during pregnancy on long-term offspring lipid and insulin metabolism. We examined the associations of maternal plasma n-3 and n-6 PUFA levels during pregnancy with childhood lipid and insulin levels.

Changes in phospholipid fatty acid composition of mouse cardiac organelles after feeding graded amounts of docosahexaenoate in presence of high levels of linoleate. Effect on cardiac ATPase activities

Mice were fed diets containing a constant supply of linoleic acid (18:2n-6, LA) as ethyl ester representing 5% by weight of the total fat (5 wt%), in combination with graded amounts of purified docosahexaenoate (22:6n-3, DHA). Cardiac sarcoplasmic reticulum (SR) and mitochondrial phospholipids (PL) from mice fed the diet without DHA contained higher levels of n-6 long chain polyunsaturated fatty acids (PUFA) (22:4n-6 and 22:5n-6) compared to total PL of liver. In the cardiac mitochondrial PL, the level of LA, DHA, the total content of PUFA and the P/S ratio were significantly higher than in SR. A small increase in dietary DHA from 0 to 0.43 wt% induced a 3.6-fold increase in PL DHA content from both cardiac organelles, with a concurrent reduction of n-6 PUFA. The changes in fatty acid PL composition were much more moderate when dietary DHA level was increased to 0.85 and 3.74 wt%. Feeding the lowest amount of DHA resulted in a 6-fold decrease in the value of n-6/n-3 PUFA ratio and a 3.5-fold decrease in the value of 20 carbon chain/22 carbon chain PUFA ratio. DHA was readily depleted from cardiac PL, and only arachidonic acid was retained in the PL from both organelles, after feeding a fat-deficient diet. Despite these drastic modifications in PL fatty acid composition, the maximum velocity (Vm) of SR Ca2+, Mg2+-ATPase was not affected, which indicates that SR cardiac membrane adapts to changes in fatty acid composition to prevent important modifications of its functional properties. However, the Vm of mitochondrial oligomycin-sensitive ATPase was slightly increased in mice fed the lowest amount of DHA. This might be due to an increase in P/S ratio and/or to a modification of cardiolipin fatty acid composition, since this PL is required for optimum function of this enzyme. It is concluded that DHA is strongly taken up by mouse cardiac PL, even in the presence of high dietary LA levels, but its acylation into PL has only little effect on the cardiac ATPase activities.     

A case-control pilot study on n-3 polyunsaturated fatty acid as a negative risk factor for myocardial infarction

The relation between n-3 polyunsaturated fatty acid (PUFA) and nonfatal myocardial infarction is still controversial. A multicenter case-control pilot study on n-3 PUFA as a negative risk factor for myocardial infarction was performed in Niigata prefecture. Seventy-three patients with acute myocardial infarction (AMI) and age and gender matched controls (n = 84) were recruited. Serum leptin levels were significantly higher in patients with AMI than the controls (8.1 +/- 6.7 ng/mL versus 5.8 +/- 3.7 ng/mL, P < 0.01), and serum high-density lipoprotein cholesterol (HDLc) levels were significantly lower in patients with AMI than the controls (46 +/- 10.5 mg/dL versus 60 +/- 15 mg/dL, P < 0.00001). Statistically significant differences were preserved in leptin and HDLc when the data were analyzed separately by gender. Serum levels (%weight) of linolenic acid (C18:3:n3), eicosapentaenoic acid (C20:5:n3), docosapentaenoic acid (C22:5:n3), and total n-3 PUFA were significantly lower in patients with AMI than the control group (P < 0.000001, < 0.05, < 0.05, < 0.05, respectively). The serum n-3 PUFA/saturated fatty acid (SF) ratio and n-3 PUFA/n-9 monounsaturated fatty acid (MUFA) ratio were significantly lower in patients with AMI than the controls (P < 0.05 and < 0.01, respectively). When the subjects were separated into two categories according to an n-3/n-6 PUFA ratio below 0.3 or above 0.3, patients with AMI were more frequently in the former while the controls were more frequently in the latter (P < 0.05). N-3 PUFA may be a negative risk factor for AMI. The results suggest leptin is a risk factor for AMI irrespective of ethnicity and gender.     

Effects of polyunsaturated fatty acids on factors related to cardiovascular disease

Dietary fats play a critical role in atherogenesis and thrombosis. Both the amount of fat consumed and its composition affect various events associated with coronary artery disease. Dietary unsaturated fatty acids appear to reduce the incidence of these events, in particular polyunsaturated fatty acids (PUFAs), which exert markedly different effects on risk factors related to heart disease. The omega-3 (n-3) PUFAs, at high levels of dietary intake, significantly reduce hyperlipidemia and the production of the prothrombotic substance thromboxane, and they enhance the production of the platelet-antiaggregatory substance prostacyclin. Data from clinical trials indicate a significant reduction of levels of very low density lipoprotein (VLDL). The n-3 PUFAs also depress hepatic fatty acid and triglyceride synthesis and VLDL secretion. The n-3 PUFAs of fish oils displace arachidonic acid from tissue phospholipids and concomitantly increase n-3 PUFA levels, which inhibit thromboxane synthesis. Most significantly, in human subjects the antiaggregatory prostacyclin PGI3 is also synthesized and the net effect is enhanced antiaggregatory/antiadhesive activity. In addition, the chemotactic platelet adhesion-promoting substance leukotriene B4 is suppressed. These composite effects reduce atherogenesis and thrombosis. Fish oil n-3 PUFAs may also reduce blood pressure and blood viscosity. Through the combined vasodilatory effects via prostacyclin (PGI2 and PGI3), fish oils may improve peripheral circulation and thereby facilitate VLDL removal. The n-3 PUFAs of fish oils, by altering membrane fluidity in a specific manner, alter the activities of membrane-bound enzymes and may change receptor activity, specificity and signal transduction. Overall, these data indicate a beneficial role for n-3 PUFAs as part of a dietary approach to minimizing coronary artery disease.     

The amount of dietary cholesterol changes the mode of effects of (n-3) polyunsaturated fatty acid on lipoprotein cholesterol in hamsters

This study was designed to investigate the effects of the interaction between dietary (n-3) polyunsaturated fatty acids (PUFA) and different dietary cholesterol content on plasma and liver cholesterol in hamsters. Male Syrian hamsters consumed diets containing an incremental increase in dietary cholesterol content (0, 0.025, 0.05, 0.1 and 0.2%, w/w) with either (n-3) PUFA (21 g/100 g fatty acids) or (n-6) PUFA (37.4 g/100 g fatty acids) fat for 6 weeks. In hamsters fed the nonatherogenic diet (0 or 0.025% dietary cholesterol), very low density lipoprotein (VLDL)-cholesterol levels in the (n-3) PUFA group were not significantly different from those in the (n-6) PUFA group, and low density lipoprotein (LDL)-cholesterol levels in the (n-3) PUFA group were significantly lower than those in the (n-6) PUFA group. In contrast, in hamsters fed the atherogenic diet (0.1 or 0.2% dietary cholesterol), VLDL- and LDL-cholesterol levels in the (n-3) PUFA group were significantly higher than those in the (n-6) PUFA group, in a dose-dependent manner. When the hamsters were fed with 0, 0.025, 0.05, 0.1 or 0.2% (w/w) dietary cholesterol, high density lipoprotein (HDL) cholesterol concentration was significantly lower in the (n-3) PUFA group than those in the (n-6) PUFA group. Hepatic cholesteryl esters were significantly lower, while hepatic microsomal acyl-coenzyme A:cholesterol acyltransferase activity and VLDL-cholesteryl esters were significantly higher in hamsters fed (n-3) PUFA with the atherogenic diet (0.1 or 0.2% dietary cholesterol) than in those fed (n-6) PUFA with the atherogenic diet. Our results demonstrate that the amount of dietary cholesterol is an important factor in determining the mode and extent of effects of dietary (n-3) PUFA, especially on VLDL- and LDL-cholesterol levels. When dietary cholesterol intake was above 0.1% (w/w), the plasma cholesterol-lowering effect of (n-3) PUFA disappeared, and instead, it showed a cholesterol-increasing effect. However, the effects of dietary (n-3) PUFA on HDL-cholesterol are independent of dietary cholesterol content.     

Beyond the Mediterranean diet: the role of omega-3 Fatty acids in the prevention of coronary heart disease

Evidence from epidemiologic and clinical secondary prevention trials suggest that the omega-3 polyunsaturated fatty acids (n-3 PUFAs) may have a significant role in the prevention of coronary heart disease. Dietary sources of n-3 PUFAs include fish oils, rich in eicosapentaenoic acid and docosahexaenoic acid, along with plants rich in a-linolenic acid. Randomized secondary prevention clinical trials with fish oils (eicosapentaenoic acid, docosahexaenoic acid) and a-linolenic acid have demonstrated reductions in risk that compare favorably to those seen in landmark secondary prevention trials with lipid-lowering drugs. Several mechanisms explaining the cardioprotective effect of the n-3 PUFA have been suggested including antiarrhythmic and antithrombotic roles. Although official US guidelines for the dietary intake of n-3 PUFA are not available, several international guidelines have been published. Fish is an important source of the n-3 PUFA in the US diet; however, vegetable sources including grains and oils offer an alternative source for those who are unable to regularly consume fish.     

A high-cholesterol, n-3 polyunsaturated fatty acid diet causes different responses in rats and hamsters

This study was designed to investigate the response to a high-cholesterol, n-3 polyunsaturated fatty acid (PUFA) or n-6 PUFA diet in rats and hamsters. Animals were fed n-3 or n-6 PUFA with a cholesterol-free diet, or with a diet enriched with cholesterol (0.5%, w/w) for 2 weeks. In rats and hamsters fed a cholesterol-free diet, plasma cholesterol, triglycerides and very-low-density lipoprotein (VLDL)-triglyceride levels in n-3 PUFA group were significantly lower than those in n-6 PUFA group. In contrast, when diets were supplemented with 0.5% cholesterol, the plasma cholesterol- and triglyceride-lowering effect of dietary n-3 PUFA disappeared. In hamsters fed with the atherogenic diet (0.5% dietary cholesterol) for 2 weeks, n-3 PUFA induced hypercholesterolemia more than n-6 PUFA, the increase being in the VLDL and low-density lipoprotein (LDL) fractions. Our data thus indicate that elevation of VLDL- and LDL-cholesterol in hamsters by n-3 PUFA, compared with n-6 PUFA, is dependent on 0.5% dietary cholesterol supplementation. In rats, on the other hand, dietary n-3 PUFA did not induce hypercholesterolemia more than n-6 PUFA when 0.5% cholesterol was supplemented. Although the effects of n-3 PUFA on plasma cholesterol, triglycerides and VLDL-triglycerides were similar in hamsters and rats, the interactive effects of n-3 PUFA and cholesterol on plasma and lipoprotein cholesterol levels differed in the two species. It was also found that plasma triglycerides, cholesterol and lipoprotein cholesterol levels in hamsters are higher than in rats in the presence and absence of dietary cholesterol. In addition, cholesterol feeding induces hypertriglyceridemia and hypercholesterolemia only in hamsters. Moreover, liver triglyceride concentrations increased in rats fed a cholesterol-rich diet and hepatic triglyceride levels of the n-3 PUFA-fed rats were significantly lower than those in the n-6 PUFA-fed rats in the presence and absence of dietary cholesterol. However, triglycerides did not accumulate in the liver in hamsters fed a cholesterol-rich diet and hepatic triglyceride levels of the n-3 PUFA-fed hamsters were not significantly different from those in the n-6 PUFA-fed hamsters in the presence and absence of dietary cholesterol. Therefore, these studies confirm marked species differences in response to the interactive effects of dietary n-3 PUFA and cholesterol.     

Non-invasive determination of cardiac output: comparison of a novel CW Doppler ultrasonic technique and inert gas rebreathing

Marine n-3 polyunsaturated fatty acids (n-3 PUFAs) in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may reduce the risk of coronary heart disease (CHD) and have anti-inflammatory effects. We examined whether levels of serum adiponectin were related to the occurrence and extent of CHD, and whether intake of n-3 PUFAs was associated to high levels of adiponectin. Serum adiponectin and the content of n-3 PUFAs in subcutaneous adipose tissue, platelets and granulocytes were measured in 291 patients referred to elective coronary angiography. Significantly lower levels of serum adiponectin were observed in patients with coronary stenoses compared to patients without stenoses (7336+/-3598 ng/ml vs 10,203+/-8396 ng/ml; p=0.003), but no significant correlation was seen between serum adiponectin and the extent of CHD. In men, serum adiponectin correlated to levels of the content of EPA in platelets (r=0.26; p<0.01) and in granulocytes (r=0.23; p<0.01) and to the content of DHA in subcutaneous adipose tissue (r=0.15; p<0.05) and granulocytes (r=0.17; p<0.05). After regression analysis EPA in platelets (p=0.017) and granulocytes (p=0.030) remained an independent correlate of adiponectin levels, while DHA was no longer an independent correlate. In conclusion, serum levels of adiponectin were lower in patients with angiographically documented coronary artery disease. Also, intake of EPA may increase serum adiponectin and through this exert a protective effect on CHD.     

Omega-3 polyunsaturated fatty acids

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are naturally occurring omega (ω)-3 long-chain polyunsaturated fatty acids (PUFAs), which are found in highest quantities in oily fish such as sardines and mackerel. Epidemiological studies of the association between fish intake, ω-3 PUFA intake or blood ω-3 PUFA levels and colorectal cancer (CRC) risk have not consistently suggested beneficial effects of ω-3 PUFAs on CRC (and other gastrointestinal cancer) risk. However, dietary administration of one or both of the main ω-3 PUFAs in rodent models of colorectal carcinogenesis has been demonstrated to reduce colorectal tumour size and multiplicity, compatible with CRC chemopreventative activity. EPA has now been demonstrated to reduce rectal polyp number and size in patients with familial adenomatous polyposis. A randomized polyp prevention trial of EPA is underway in order to test chemopreventative efficacy against 'sporadic' colorectal neoplasia.     

Abnormal fatty acid distribution of the serum phospholipids of patients with non-Hodgkin lymphoma

The data about the fatty acid (FA) status of non-Hodgkin lymphoma (NHL) patients are poor. Therefore, the aim of this study was to investigate the FA profile of serum phospholipids in NHL patients related to the aggressiveness and clinical stage of NHL. We analyzed the FA profile of serum phospholipids in 47 newly diagnosed, untreated NHL patients and in 29 healthy subjects. Significantly higher (p?<?0.001) levels of palmitic (16:0), oleic (18:1 n-9) and arachidonic acids (20:4 n-6), saturated and monounsaturated FA were found in NHL patients, while linoleic acid (18:2 n-6) and the levels of total polyunsaturated FA (PUFA), n-3 PUFA, eicosapentaenoic (20:5 n-3) and docosahexaenoic (DHA, 22:6 n-3) were significantly reduced (p?<?0.01). The level of oleic acid in patients with indolent NHL was significantly lower (p?<?0.05) than in more aggressive types of disease. Contents of palmitoleic acid, docosatetraenoic (22:4 n-6), and PUFA was lower in very aggressive NHL. According to clinical stage (CS), patients with CS I had significantly higher SFA and lower n-6 FA than other three groups, and group with CS IV showed significantly decreased DHA and n-3 PUFA. Our results showed an abnormal FA profile in serum phospholipids in NHL patients.     

高血压患者血清磷酯脂肪酸谱与血脂的相关性研究

目的研究高血压患者血清磷酯脂肪酸谱与血脂的相关性。方法采用高效气相色谱法测定高血压患者和健康对照者的血清磷酯脂肪酸谱,酶法测定血脂。结果高血压组的14:0、16:0、18:0和饱和脂肪酸(SFA)较对照组显著升高,16:1、18:1、18:2n-6、20:5n-3、单不饱和脂肪酸(MUFA)、n-6多不饱和脂肪酸(n-6 PUFA)、n-3多不饱和脂肪酸(n-3 PUFA)和多不饱和脂肪酸(PUFA)较对照组显著降低。总胆固醇(TC)与18:0正相关,而与16:1和18:1负相关;甘油三酯(TG)与18:2n-6、20:5n-3、和PUFA负相关;高密度脂蛋白胆固醇(HDL-C)与)18:2n-6、20:4n-6和n-6PUFA正相关;低密度脂蛋白胆固醇(LDL-C)与14:0和16:0正相关,而与n-3PUFA负相关。结论高血压血清磷酯脂肪酸谱中SFA高于健康对照,MUFA和PU-FA低于健康对照。而与血脂的相关分析显示SFA与高血压的血脂升高有关,而MUFA和PUFA对高血压患者的血脂具有保护作用。     

Non-alcoholic fatty liver disease in HIV infection associated with altered hepatic fatty acid composition

Hepatic fatty acid (FA) composition, especially a reduction in n-3 polyunsaturated FA (PUFA) may contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD), which is common in HIV-infection.. In a cross-sectional study we compared hepatic FA composition between 20 HIV-infected men with NAFLD (HIV/NAFLD), 21 HIV-negative men with NAFLD (NAFLD), and 7 healthy controls. Within HIV/NAFLD we compared simple steatosis (HIV/SS) to steatohepatitis (HIV/NASH). FA composition in liver and erythrocytes, oxidative stress, diet, and exercise were assessed. Major findings (P<0.05) were: 1) higher hepatic n-6/n-3 ratio in HIV/NAFLD [median (range)] [8.08 (1.08-21.52)] compared to controls [5.83 (3.58-6.93)] and NAFLD [5.97 (1.46-10.40)], with higher n-6 PUFA in HIV/NAFLD compared to NAFLD; 2) lower n-3 PUFA in erythrocytes (mol%), a marker for dietary intake, in HIV/NAFLD [5.26 (1.04-11.75)] compared to controls [8.92 (4.79-12.67)]; 3) the ratios of long-chain PUFA products to essential FA precursors of the n-6 and n-3 series were lower in HIV/NAFLD and NAFLD compared to controls. In contrast, the ratio of oleic/stearic acid was higher in HIV/NAFLD compared to the other groups. These ratios are indirect markers of enzymatic FA desaturation and elongation. Hepatic PUFA, especially biologically active long-chain PUFA, were also lower in HIV/NASH compared to HIV/SS. Oxidative stress was not different among the groups. We conclude that HIV/NAFLD is associated with altered hepatic FA composition. Changes may be due to impaired FA metabolism or suboptimal n-3 PUFA intake. The potential role of n-3 PUFA (e.g. fish oil) to treat or prevent HIV/NAFLD warrants further investigation.     

C-reactive protein, dietary n-3 fatty acids, and the extent of coronary artery disease.

The acute-phase reactant C-reactive protein (CRP) has emerged as an independent risk factor for coronary artery disease. Experimental and clinical studies provide evidence of anti-inflammatory effects of n-3 polyunsaturated fatty acids (PUFA) derived from fish. We have studied the effect of marine n-3 PUFA on CRP levels in 269 patients referred for coronary angiography because of clinical suspicion of coronary artery disease. All patients filled out a food questionnaire regarding fish intake. The n-3 PUFA content of granulocyte membranes was determined and the concentration of CRP in serum was measured using a highly sensitive assay. The results were related to angiographic findings. CRP was significantly higher in patients with significant coronary stenoses than in those with no significant angiographic changes (p <0.001), but the CRP levels were not associated with the number of diseased vessels. Subjects with CRP levels in the lower quartile had a significantly higher content of docosahexaenoic acid (DHA) in granulocytes than subjects with CRP levels in the upper quartile (p = 0.02), and in a multivariate linear regression analysis, DHA was independently correlated to CRP (R(2) = 0.179; p = 0.003). The inverse correlation between CRP and DHA may reflect an anti-inflammatory effect of DHA in patients with stable coronary artery disease and suggest a novel mechanism by which fish consumption may decrease the risk of coronary artery disease.     

Do antioxidants and polyunsaturated fatty acids have a combined association with coronary atherosclerosis?

To evaluate the antioxidant hypothesis with regard to atherosclerosis, we compared plasma selenium, serum alpha-tocopherol, serum polyunsaturated fatty acids (PUFA), and the ratios of selenium and alpha-tocopherol to PUFAs in subjects with varying degrees of coronary atherosclerosis. Cases had more than 85% stenosis in at least one coronary vessel and controls had less than 50% stenosis in all three vessels. Plasma selenium was significantly lower in cases than controls (95.1 +/- 21.0 micrograms/l and 108.8 +/- 29.3 micrograms/l, respectively). Though alpha-tocopherol and PUFA levels were similar in both groups, the ratios Se/linoleic acid, Se/total PUFA and Se/total n-6 acids were significantly lower in cases. In particular, these differences were observed in subjects with low serum alpha-tocopherol level (below the median; 1452 micrograms/dl). Moreover, in this subgroup the ratio Se/PUFA was significantly lower in cases than in controls for all PUFAs except eicosapentaenoic and docosahexaenoic acid. Though definitive conclusions cannot be drawn from our data, it is hypothesized that high PUFA levels, when insufficiently protected by antioxidants against peroxidation, may indicate a higher risk of atherosclerosis.     

Enhanced level of n-3 fatty acid in membrane phospholipids induces lipid peroxidation in rats fed dietary docosahexaenoic acid oil

The effect of dietary docosahexaenoic acid (DHA, 22:6n-3) oil with different lipid types on lipid peroxidation was studied in rats. Each group of male Sprague-Dawley rats was pair fed 15% (w/w) of either DHA-triglycerides (DHA-TG), DHA-ethyl esters (DHA-EE) or DHA-phospholipids (DHA-PL) for up to 3 weeks. The palm oil (supplemented with 20% soybean oil) diet without DHA was fed as the control. Dietary DHA oils lowered plasma triglyceride concentrations in rats fed DHA-TG (by 30%), DHA-EE (by 45%) and DHA-PL (by 27%), compared to control. The incorporation of dietary DHA into plasma and liver phospholipids was more pronounced in the DHA-TG and DHA-EE group than in the DHA-PL group. However, DHA oil intake negatively influenced lipid peroxidation in both plasma and liver. Phospholipid peroxidation in plasma and liver was significantly higher than control in rats fed DHA-TG or DHA-EE, but not DHA-PL. These results are consistent with increased thiobarbituric acid reactive substances (TBARS) and decreased alpha-tocopherol levels in plasma and liver. In addition, liver microsomes from rats of each group were exposed to a mixture of chelated iron (Fe(3+)/ADP) and NADPH to determine the rate of peroxidative damage. During NADPH-dependent peroxidation of microsomes, the accumulation of phospholipid hydroperoxides, as well as TBARS, were elevated and alpha-tocopherol levels were significantly exhausted in DHA-TG and DHA-EE groups. During microsomal lipid peroxidation, there was a greater loss of n-3 fatty acids (mainly DHA) than of n-6 fatty acids, including arachidonic acid (20:4n-6). These results indicate that polyunsaturation of n-3 fatty acids is the most important target for lipid peroxidation. This suggests that the ingestion of large amounts of DHA oil enhances lipid peroxidation in the target membranes where greater amounts of n-3 fatty acids are incorporated, thereby increasing the peroxidizability and possibly accelerating the atherosclerotic process.