Serum fatty acid levels, dietary style and coronary heart disease in three neighbouring areas in Japan: the Kumihama study

Assessing the Highest Level of Evidence from Randomized Controlled Trials in Omega-3 Research

Over the years, there has been heightened interest in the health benefits of n-3 polyunsaturated fatty acids (PUFA) in reducing chronic diseases such as, cardiovascular disease (CVD), cancer, type 2 diabetes, and acute macular degeneration (AMD). Due to inconsistent findings in the evidence, a review to critically examine the plethora of evidence from randomized controlled trials (RCTs) in n-3 PUFA research was undertaken. The aim of this review is to study the highest level of evidence and to identify gaps in n-3 PUFA research. RCTs were originally designed for pharmaceutical research and later adopted for nutrition and food-related research. RCTs with active diseases assume that n-3 PUFA will have "drug" like effects, and this high expectation may have led to the inconsistent evidence in the literature. The inconsistency in the literature may be related to varying doses of n-3 PUFA, sources of n-3 PUFA (food vs. supplement; plant vs. marine), type of n-3 PUFA (mixture vs. purified), trial duration, population characteristics, sample size, and genetic variation. For future research, there is a need to distinguish between primary and secondary prevention, and to focus RCTs on primary prevention of chronic diseases by n-3 PUFA which is lacking in the literature.

Hesperetin protects against palmitate-induced cellular toxicity via induction of GRP78 in hepatocytes

Lipotoxicity plays a critical role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Hesperetin, a flavonoid derivative, has anti-oxidant, anti-inflammatory and cytoprotective properties. In the present study, we aim to examine whether hesperetin protects against palmitate-induced lipotoxic cell death and to investigate the underlying mechanisms in hepatocytes. Primary rat hepatocytes and HepG2 cells were pretreated with hesperetin for 30 min and then exposed to palmitate (1.0 mmol/L in primary rat hepatocytes; 0.5 mmol/L in HepG2 cells) in the presence or absence of hesperetin. Necrotic cell death was measured via Sytox green nuclei staining and quantified by LDH release assay. Apoptotic cell death was determined by caspase 3/7 activity and the protein level of cleaved-PARP. The unfolded protein response (UPR) was assessed by measuring the expression of GRP78, sXBP1, ATF4 and CHOP. Results show that hesperetin (50 μmol/L and 100 μmol/L) protected against palmitate-induced cell death and inhibited palmitate-induced endoplasmic reticulum (ER) stress in both primary rat hepatocytes and HepG2 cells. Hesperetin (100 μmol/L) significantly activated sXBP1/GRP78 signaling, whereas a high concentration of hesperetin (200 μmol/L) activated p-eIF2α and caused hepatic cell death. Importantly, GRP78 knockdown via siRNA abolished the protective effects of hesperetin in HepG2 cells. In conclusion, hesperetin protected against palmitate-induced hepatic cell death via activation of the sXBP1/GRP78 signaling pathway, thus inhibiting palmitate-induced ER stress. Moreover, high concentrations of hesperetin induce ER stress and subsequently cause cell death in hepatocytes.

Increased Serum Dihomo-γ-linolenic Acid Levels Are Associated with Obesity, Body Fat Accumulation, and Insulin Resistance in Japanese Patients with Type 2 Diabetes

Objective To clarify the associations between serum omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acid (PUFA) levels and obesity-related metabolic abnormalities in patients with type 2 diabetes. Methods and Materials Data from 225 Japanese patients with type 2 diabetes were cross-sectionally analyzed. The serum levels of n-6 PUFAs [dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA)] and n-3 PUFAs (eicosapentaenoic acid and docosahexaenoic acid) were measured, and the estimated Δ-5 desaturase (D5D) activity was calculated based on the AA to DGLA ratio. The associations between the composition of PUFAs and obesity-related parameters, including the body mass index (BMI), waist circumference, alanine amino transferase (ALT) level, homeostatic model assessment of insulin resistance (HOMA-IR), and body fat percentage, as measured by a bioelectrical impedance analysis, were analyzed. Results Among the PUFAs, the DGLA level had the strongest correlations with BMI (p<0.001), waist circumference (p<0.001), ALT level (p<0.001), HOMA-IR (p<0.001), and body fat percentage (p<0.01). AA was positively correlated and D5D was negatively correlated with several obesity-related parameters, while n-3 PUFAs did not have a constant correlation. A multivariate regression analysis revealed that the DGLA level was an independent determinant for HOMA-IR (β=0.195, p=0.0066) after adjusting for sex, age, BMI, and the ALT, triglyceride, and HbA1c levels. Conclusion A high serum DGLA level was associated with obesity, body fat accumulation, a high ALT level, and insulin resistance in patients with type 2 diabetes. The measurement of the serum PUFA levels may be useful for evaluating metabolic abnormalities and estimating the dietary habits of patients.

Clinical Relevance of Type II Fatty Acid Synthesis Bypass in Staphylococcus aureus

The need for new antimicrobials to treat bacterial infections has led to the use of type II fatty acid synthesis (FASII) enzymes as front-line targets. However, recent studies suggest that FASII inhibitors may not work against the opportunist pathogen Staphylococcus aureus, as environmental fatty acids favor emergence of multi-anti-FASII resistance. As fatty acids are abundant in the host and one FASII inhibitor, triclosan, is widespread, we investigated whether fatty acid pools impact resistance in clinical and veterinary S. aureus isolates. Simple addition of fatty acids to the screening medium led to a 50% increase in triclosan resistance, as tested in 700 isolates. Moreover, nonculturable triclosan-resistant fatty acid auxotrophs, which escape detection under routine conditions, were uncovered in primary patient samples. FASII bypass in selected isolates correlated with polymorphisms in the acc and fabD loci. We conclude that fatty-acid-dependent strategies to escape FASII inhibition are common among S. aureus isolates and correlate with anti-FASII resistance and emergence of nonculturable variants.

Growth-Environment Dependent Modulation of Staphylococcus aureus Branched-Chain to Straight-Chain Fatty Acid Ratio and Incorporation of Unsaturated Fatty Acids

The fatty acid composition of membrane glycerolipids is a major determinant of Staphylococcus aureus membrane biophysical properties that impacts key factors in cell physiology including susceptibility to membrane active antimicrobials, pathogenesis, and response to environmental stress. The fatty acids of S. aureus are considered to be a mixture of branched-chain fatty acids (BCFAs), which increase membrane fluidity, and straight-chain fatty acids (SCFAs) that decrease it. The balance of BCFAs and SCFAs in USA300 strain JE2 and strain SH1000 was affected considerably by differences in the conventional laboratory medium in which the strains were grown with media such as Mueller-Hinton broth and Luria broth resulting in high BCFAs and low SCFAs, whereas growth in Tryptic Soy Broth and Brain-Heart Infusion broth led to reduction in BCFAs and an increase in SCFAs. Straight-chain unsaturated fatty acids (SCUFAs) were not detected. However, when S. aureus was grown ex vivo in serum, the fatty acid composition was radically different with SCUFAs, which increase membrane fluidity, making up a substantial proportion of the total (<25%) with SCFAs (>37%) and BCFAs (>36%) making up the rest. Staphyloxanthin, an additional major membrane lipid component unique to S. aureus, tended to be greater in content in cells with high BCFAs or SCUFAs. Cells with high staphyloxanthin content had a lower membrane fluidity that was attributed to increased production of staphyloxanthin. S. aureus saves energy and carbon by utilizing host fatty acids for part of its total fatty acids when growing in serum, which may impact biophysical properties and pathogenesis given the role of SCUFAs in virulence. The nutritional environment in which S. aureus is grown in vitro or in vivo in an infection is likely to be a major determinant of membrane fatty acid composition.

Environmental fatty acids enable emergence of infectious Staphylococcus aureus resistant to FASII-targeted antimicrobials

The bacterial pathway for fatty acid biosynthesis, FASII, is a target for development of new anti-staphylococcal drugs. This strategy is based on previous reports indicating that self-synthesized fatty acids appear to be indispensable for Staphylococcus aureus growth and virulence, although other bacteria can use exogenous fatty acids to compensate FASII inhibition. Here we report that staphylococci can become resistant to the FASII-targeted inhibitor triclosan via high frequency mutations in fabD, one of the FASII genes. The fabD mutants can be conditional for FASII and not require exogenous fatty acids for normal growth, and can use diverse fatty acid combinations (including host fatty acids) when FASII is blocked. These mutants show cross-resistance to inhibitors of other FASII enzymes and are infectious in mice. Clinical isolates bearing fabD polymorphisms also bypass FASII inhibition. We propose that fatty acid-rich environments within the host, in the presence of FASII inhibitors, might favour the emergence of staphylococcal strains displaying resistance to multiple FASII inhibitors.

The bacterial pathway for fatty acid biosynthesis, FASII, is a target for development of new anti-staphylococcal drugs. Here, Morvan et al. show that exogenous fatty acids can favour the emergence of staphylococcal strains displaying resistance to multiple FASII inhibitors.

Marine omega-3 highly unsaturated fatty acids: From mechanisms to clinical implications in heart failure and arrhythmias

Therapeutic implications of marine omega-3 highly unsaturated fatty acids (HUFA) in cardiovascular disease are still discussed controversially. Several clinical trials report divergent findings and thus leave ambiguity on the meaning of oral omega-3 therapy. Potential prognostic indications of HUFA treatment have been predominantly studied in coronary artery disease, sudden cardiac death, ventricular arrhythmias, atrial fibrillation and heart failure of various origin. It is suspected that increased ventricular wall stress is crucially involved in the prognosis of heart failure. Increased wall stress and an unfavorable myocardial remodeling is associated with an increased risk of arrhythmias by stretch-activated membrane ion channels. Integration of HUFA into the microenvironment of cardiomyocyte ion channels lead to allosteric changes and increase the electrical stability. Increased ventricular wall stress appears to be involved in the local myocardial as well as in the hepatic fatty acid metabolism, i.e. a cardio-hepatic syndrome. Influences of an altered endogenous HUFA metabolism and an inverse shift of the fatty acid profile was underrated in the past. A better understanding of these interacting endogenous mechanisms appears to be required for interpreting the findings of recent experimental and clinical studies. The present article critically reviews major studies on basic pathophysiological mechanisms and treatment effects in clinical trials.

Deletion of fabN in Enterococcus faecalis results in unsaturated fatty acid auxotrophy and decreased release of inflammatory cytokines

The Gram-positive bacterium Enterococcus faecalis can cause life-threatening infections and is resistant to several commonly used antibiotics. The type II fatty acid pathway in bacteria is discussed as a potential target for antimicrobial therapy. However, it was shown that inhibition or deletion of its enzymes can be rescued in Gram-positive bacteria by supplementation with fatty acids. Here we show that by deletion of the fabN gene, which is essential for unsaturated fatty acid (UFA) synthesis in E. faecalis, growth is impaired but can be rescued by supplementation with oleic acid or human serum. Nonetheless, we demonstrate alterations of the UFA profile after supplementation with oleic acid in the ΔfabN mutant using a specific glycolipid. In addition, we demonstrate that cytokine release in vitro is almost abolished after stimulation of mouse macrophages by the mutant in comparison to the wild type. The results indicate that fabN is not a suitable target for antimicrobials as UFA auxotrophy can be overcome. However, deletion of fabN resulted in a decreased inflammatory response indicating that fabN and resulting UFA synthesis are relevant for virulence.

Cross-sectional association between serum concentrations of n-3 long-chain PUFA and depressive symptoms: results in Japanese community dwellers

The effect of n-3 long-chain PUFA (n-3 LCPUFA) on depression in healthy subjects is unclear, and most of the previous studies have focused on populations eating Western diets with lower fish intake. The present study investigated the association between blood levels of n-3 LCPUFA and depressive symptoms in Japanese community dwellers with higher n-3 LCPUFA blood levels. A cross-sectional study was conducted from 2006 to 2008, including 1050 men and 1073 women aged 40 years or older from the National Institute for Longevity Sciences – the Longitudinal Study of Aging. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess depressive symptoms. Multiple logistic regression analysis was performed to estimate the OR and 95 % CI for a CES-D score ≥16. Serum concentrations of n-3 PUFA, but not n-6 PUFA, were inversely associated with depressive symptoms. Compared with the lowest quintile, the adjusted OR for serum EPA at the fourth and fifth quintiles were 0·55 (95 % CI 0·35, 0·85) and 0·64 (95 % CI 0·42, 0·98), respectively, and at the fifth quintile for DHA it was 0·58 (95 % CI 0·37, 0·92), for the presence of depressive symptoms (P_{for trend}=0·013 and 0·011, respectively). Serum levels of EPA and DHA were inversely associated with depressive symptoms in Japanese community dwellers with higher blood levels of n-3 LCPUFA, suggesting that n-3 LCPUFA intakes corresponding to higher levels in a Japanese population may have implications for a lower prevalence of depression.

Anti-Inflammatory Diet for Atherosclerosis and Coronary Artery Disease: Antioxidant Foods

Oxidative stress plays a role in atherosclerotic diseases such as coronary artery disease (CAD), and much attention has been paid to antioxidant foods. The relationships between the consumption of vegetables and fruits and atherosclerotic diseases have been reported in many epidemiological studies showing a reduced risk of such diseases. In addition to the antioxidant vitamins C and E, green and yellow vegetables contain abundant quantities of carotenoids and polyphenols. The consumption of carotenoids and vitamins C and E has been shown to be inversely associated with CAD. However, supplementation with beta-carotene and vitamins C and E shows no beneficial effect, but rather mortality is increased with beta-carotene and vitamin E supplements. Therefore, it is recommended to consume vegetables and fruits, but vitamin supplementation is not recommended. Many epidemiological studies also report that higher consumption of fish, rich in n-3 polyunsaturated fatty acids (PUFAs), is associated with a lower risk of CAD and stroke. Antiatherosclerotic effects of n-3 PUFAs include reduced platelet aggregation, triglyceride-lowering effect, anti-inflammatory effect, and plaque stabilization, but the anti-inflammatory effect is principally responsible for preventing atherosclerosis. It is recommended to consume fish at least twice a week in patients without CAD and to consider n-3 PUFA supplements in patients with documented CAD. Regarding soy products, soy protein consumption reduces low-density-lipoprotein cholesterol and triglyceride levels. Isoflavone, a polyphenol contained in soybeans, has antiatherosclerotic property because it has a structure similar to that of estrogen and bonds with estrogen receptors. High consumption of isoflavone has been reported to be associated with a reduced risk of CAD and stroke only in women, but the preventative effect of soy products in the general population has not yet been clarified. Thus, many epidemiological studies report the promising effects of antioxidant foods, but there are many unclear points remaining with regard to the contribution of the nutritional elements found in antioxidant foods to the prevention of atherosclerotic diseases.

Effect of caloric restriction with or without n-3 polyunsaturated fatty acids on insulin sensitivity in obese subjects: A randomized placebo controlled trial

Background

Caloric restriction and n-3 polyunsaturated fatty acid (PUFA) supplementation protect from some of the metabolic complications. The aim of this study was to assess the influence of a low calorie diet with or without n-3 PUFA supplementation on glucose dependent insulinotropic polypeptide (GIP) output and insulin sensitivity markers in obese subjects.

Methods

Obese, non-diabetic subjects (BMI 30–40 kg/m²) and aged 25–65 yr. were put on low calorie diet (1200–1500 kcal/day) supplemented with either 1.8 g/day n-3 PUFA (DHA/EPA, 5:1) (n = 24) or placebo capsules (n = 24) for three months in a randomized placebo controlled trial. Insulin resistance markers and GIP levels were analysed from samples obtained at fasting and during an oral glucose tolerance test (OGTT).

Results

Caloric restriction with n-3 PUFA led to a decrease of insulin resistance index (HOMA-IR) and a significant reduction of insulin output as well as decreased GIP secretion during the OGTT. These effects were not seen with caloric restriction alone. Changes in GIP output were inversely associated with changes in red blood cell EPA content whereas fasting GIP level positively correlated with HOMA-IR index. Blood triglyceride level was lowered by caloric restriction with a greater effect when n-3 PUFA were included and correlated positively with fasting GIP level.

Conclusions

Three months of caloric restriction with DHA + EPA supplementation exerts beneficial effects on insulin resistance, GIP and triglycerides.

General significance

Combining caloric restriction and n-3 PUFA improves insulin sensitivity, which may be related to a decrease of GIP levels.

•

Caloric restricted diet with n-3 PUFA improves insulin sensitivity in obese subjects

•

n-3 PUFA supplementation combined with low calorie diet decrease GIP output

•

Blood triglycerides level reduces after caloric restriction diet combined with n-3 PUFA

•

GIP level positively correlates with HOMA-IR index and triglycerides

Eicosapentaenoic Acid (EPA) Decreases the All-Cause Mortality in Hemodialysis Patients

OBJECTIVE

Atherosclerosis, which causes cardiovascular disease, is a major cause of death in hemodialysis (HD) patients. Eicosapentaenoic acid (EPA), an anti-hyperlipidemic agent, is known to have antioxidative or anti-inflammatory effects, resulting in improvements in atherosclerosis. In the present study, we examined whether EPA improves the all-cause mortality in patients receiving regular HD therapy.

METHODS

We enrolled 176 patients treated with maintenance HD therapy and performed a longitudinal observational cohort study for three years. We divided the patients into two groups based on whether or not the received EPA treatment [EPA(+) and EPA(-), respectively]. The primary end-point was all-cause death. We also matched the two groups using propensity score matching and examined the effect of EPA.

RESULTS

Before matching, the all-cause mortality rates were 24.0% in the EPA(+) and 11.8% in the EPA(-) groups, which were significantly different (p=0.044). After propensity score matching, the EPA(+) group still showed a significantly better prognosis than the EPA(-) group (p=0.038). A multivariate analysis showed that EPA treatment significantly reduced the risk of all-cause mortality both before and after propensity score matching.

CONCLUSION

EPA treatment is independently associated with lower mortality in HD patients.

Novel therapeutic strategies for adult obese asthmatics

Asthma is a complex syndrome that affects an estimated 26 million people in the United States but gaps exist in the recognition and management of asthmatic subgroups. This article proposes alternative approaches for future treatments of adult obese asthmatics who do not respond to standard controller therapies, drawing parallels between seemingly disparate therapeutics through their common signaling pathways. How metformin and statins can potentially improve airway inflammation is described and supplements are suggested. A move toward more targeted therapies for asthma subgroups is needed. These therapies address asthma and the comorbidities that accompany obesity and metabolic syndrome to provide the greatest therapeutic potential.

The Effect of n-3 Fatty Acids on Glucose Homeostasis and Insulin Sensitivity

Type 2 diabetes (T2D) as well as cardiovascular disease (CVD) represent major complications of obesity and associated metabolic disorders (metabolic syndrome). This review focuses on the effects of long-chain n-3 polyunsaturated fatty acids (omega-3) on insulin sensitivity and glucose homeostasis, which are improved by omega-3 in many animal models of metabolic syndrome, but remain frequently unaffected in humans. Here we focus on: (i) mechanistic aspects of omega-3 action, reflecting also our experiments in dietary obese mice; and (ii) recent studies analysing omega-3’s effects in various categories of human subjects. Most animal experiments document beneficial effects of omega-3 on insulin sensitivity and glucose metabolism even under conditions of established obesity and insulin resistance. Besides positive results obtained in both cross-sectional and prospective cohort studies on healthy human populations, also some intervention studies in prediabetic subjects document amelioration of impaired glucose homeostasis by omega-3. However, the use of omega-3 to reduce a risk of new-onset diabetes in prediabetic subjects still remains to be further characterized. The results of a majority of clinical trials performed in T2D patients suggest that omega-3 have none or marginal effects on metabolic control, while effectively reducing hypertriglyceridemia in these patients. Despite most of the recent randomized clinical trials do not support the role of omega-3 in secondary prevention of CVD, this issue remains still controversial. Combined interventions using omega-3 and antidiabetic or hypolipidemic drugs should be further explored and considered for treatment of patients with T2D and other diseases.

An increase in the EPA/AA ratio is associated with improved arterial stiffness in obese patients with dyslipidemia

AIM

Previous epidemiological studies demonstrated that the ratio of n-6 to n-3 polyunsaturated fatty acids is associated with cardiovascular diseases. We herein investigated whether the beneficial effect of highly purified eicosapentaenoic acid(EPA) on arterial stiffness is associated with changes in the ratio of polyunsaturated fatty acids, such as EPA, docosahexaenoic acid(DHA) and dihomo-γ-linolenic acid(DGLA), relative to arachidonic acid(AA), in obese Japanese patients with dyslipidemia.

METHODS

The EPA/AA, DHA/AA and DGLA/AA ratios were compared between obese patients with(n=94) and without (n=31) dyslipidemia. Among the former group, 88 patients received either highly purified EPA treatment(1.8g daily, n=45) or treatment without EPA(control, n=43).

RESULTS

At baseline, the ratios of DHA/AA and DGLA/AA were significantly(P＜0.05) higher in obese patients with dyslipidemia than in those without, while the EPA/AA ratio was similar between patients with and without dyslipidemia. EPA significantly reduced the hemoglobin A1c, total cholesterol, triglycerides, CRP, cardio-ankle vascular index(CAVI)(an index of arterial stiffness) and the DGLA/AA ratio relative to the control at three months after the treatment. On the other hand, EPA significantly increased the adiponectin level and EPA/AA ratio(P＜0.05). A multivariate regression analysis revealed that only age, an increase in the EPA/AA ratio and a decrease in the CRP level were significant determinants of a reduction of the CAVI by EPA.

CONCLUSION

These findings suggest that EPA improves the arterial stiffness in association with an increase in the EPA/AA ratio and a decrease in inflammation in obese patients with dyslipidemia.

The two functional enoyl-acyl carrier protein reductases of Enterococcus faecalis do not mediate triclosan resistance

Enoyl-acyl carrier protein (enoyl-ACP) reductase catalyzes the last step of the elongation cycle in the synthesis of bacterial fatty acids. The Enterococcus faecalis genome contains two genes annotated as enoyl-ACP reductases, a FabI-type enoyl-ACP reductase and a FabK-type enoyl-ACP reductase. We report that expression of either of the two proteins restores growth of an Escherichia coli fabI temperature-sensitive mutant strain under nonpermissive conditions. In vitro assays demonstrated that both proteins support fatty acid synthesis and are active with substrates of all fatty acid chain lengths. Although expression of E. faecalis fabK confers to E. coli high levels of resistance to the antimicrobial triclosan, deletion of fabK from the E. faecalis genome showed that FabK does not play a detectable role in the inherent triclosan resistance of E. faecalis. Indeed, FabK seems to play only a minor role in modulating fatty acid composition. Strains carrying a deletion of fabK grow normally without fatty acid supplementation, whereas fabI deletion mutants make only traces of fatty acids and are unsaturated fatty acid auxotrophs.

The finding that exogenous fatty acids support growth of E. faecalis strains defective in fatty acid synthesis indicates that inhibitors of fatty acid synthesis are ineffective in countering E. faecalis infections because host serum fatty acids support growth of the bacterium.

Physical activity and blood lipids and lipoproteins in dialysis patients

The relationship between physical activity and blood lipids and lipoproteins in dialysis patients is reviewed in the context of the potentially confounding factors such as nutritional intake, cigarette smoking, obesity, alcohol intake, and physical activity levels in the general population and additional confounding factors such as mode of dialysis and diabetes in dialysis patients. The known associations in the general population of physical activity with high-density-lipoprotein cholesterol subfractions and apolipoprotein A-I are more pronounced in hemodialysis patients than in peritoneal dialysis patients even after adjusting for these confounding factors. Examining studies on the effects of physical activity on blood lipids and lipoproteins, the most consistent observation is the noted decrease in triglycerides and increase in high-density-lipoprotein cholesterol and insulin sensitivity in hemodialysis patients. The changes in lipids and lipoproteins in hemodialysis patients could be caused by changes in activity levels of lipoprotein lipase, insulin sensitivity, and/or glucose metabolism. Future research investigating the relationship between physical activity and blood lipids and lipoproteins in dialysis patients should direct research towards the underlying mechanisms for changes in blood lipids and lipoproteins.

Docosahexaenoic acid ameliorates palmitate-induced lipid accumulation and inflammation through repressing NLRC4 inflammasome activation in HepG2 cells

Background

N-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA; 22:6n-3), has clinical significance in the prevention and reversal of nonalcoholic steatohepatitis (NASH). However, the precious mechanism underlying remains unclear. The inflammasome, a multiprotein complex formed by NOD-like receptor (NLR) family members, has been recently shown to be activated in NASH and promote the cleavage of the pro-inflammatory cytokines to their maturation forms.

Methods

HepG2 cells were exposed to different dose of PA for 24 h with or without the preincubation of 50 μM DHA for another 24 h and then lipid deposition was assessed with Oil red O staining and intracellular triglyceride (TG) determination. Secretory levels of inflammatory cytokines and Caspase-1 activity were determined by ELISA assays. Gene expression and protein levels were determined by quantitative RCR and western blotting, respectively.

Results

Palmitate (PA) dose-dependently increased lipid accumulation, TG content and induced the secretion of interleukin-1β (IL-1β), IL-18, TNF-α and MCP-1 from HepG2 cells. Preincubation with DHA significantly alleviated PA-induced lipid accumulation and inflammatory agents. DHA was also found to attenuate PA-induced NOD-like receptor protein 4 (NLRC4) mRNA expression. Furthermore, PA induced caspase-1 activation in a dose-dependent manner, resulting in exacerbating of procaspase-1 and pro-IL-1β processing. Knockdown of NLRC4 partially abrogated PA-induced caspase-1 activation and IL-1β maturation and completely abolished these events in the presence of DHA.

Conclusions

Our findings indicate DHA attenuates PA-induced lipid accumulation and inflammation through suppressing NLRC4 inflammasome activation, caspase-1 activation and IL-1β cleavage.

Invariant natural killer T cells recognize glycolipids from pathogenic Gram-positive bacteria

Natural killer T cells (NKT cells) recognize glycolipid antigens presented by CD1d. These cells express an evolutionarily conserved, invariant T cell antigen receptor (TCR), but the forces that drive TCR conservation have remained uncertain. Here we show that NKT cells recognized diacylglycerol-containing glycolipids from Streptococcus pneumoniae, the leading cause of community-acquired pneumonia, and group B Streptococcus, which causes neonatal sepsis and meningitis. Furthermore, CD1d-dependent responses by NKT cells were required for activation and host protection. The glycolipid response was dependent on vaccenic acid, which is present in low concentrations in mammalian cells. Our results show how microbial lipids position the sugar for recognition by the invariant TCR and, most notably, extend the range of microbes recognized by this conserved TCR to several clinically important bacteria.

Relationship between coronary plaque vulnerability and serum n-3/n-6 polyunsaturated fatty acid ratio

BACKGROUND

A low ratio of serum eicosapentaenoic acid to arachidonic acid (EPA/AA) has been associated with cardiovascular events. Higher-grade yellow color coronary plaques are associated with higher plaque vulnerability and higher thrombogenic potential. Therefore, the association between EPA/AA ratio and yellow color grade of coronary plaques was examined.

METHODS AND RESULTS

Consecutive patients (n=54) who underwent percutaneous coronary intervention were enrolled in this study. The serum EPA/AA ratio was examined on admission. All patients underwent an angioscopic examination of the culprit vessel to examine the color grade of yellow plaques (0, white; 1, slight yellow; 2, yellow; and 3, intense yellow) and the presence of thrombus. Excluding 16 patients with acute coronary syndrome (ACS), 38 patients with stable angina were divided into 2 groups according to their EPA/AA ratio: the low EPA/AA group (n=19, EPA/AA ratio <0.37 [median]) and the high EPA/AA group (n=19, EPA/AA ratio ≥0.37). The maximum color grade (2.5 ± 0.5 vs. 1.9 ± 0.9; P=0.01) of yellow plaques was significantly higher and the number of non-culprit yellow plaques with thrombus (1.7 ± 0.8 vs. 1.2 ± 1.1; P=0.06) tended to be higher in low EPA/AA than in high EPA/AA stable angina patients. Multivariate analysis revealed that the serum EPA level (odds ratio=0.98, 95% confidence interval=0.96-0.99, P=0.03) was associated with the presence of grade-3 yellow plaques.

CONCLUSIONS

A low serum EPA level and a low EPA/AA ratio was associated with high vulnerability of coronary plaques.

Relationships among the serum omega fatty acid levels, serum C-reactive protein levels and arterial stiffness/wave reflection in Japanese men

OBJECTIVE

We examined the relationship among the serum omega-3 and omega-6 fatty acid (O3FA and O6FA) levels, serum C-reactive protein (CRP) levels, and arterial stiffness/wave reflection (AS/WR) in healthy Japanese men.

METHODS

In 2206 Japanese healthy men, parameters related to the AS/WR (i.e., brachial-ankle pulse wave velocity and radial arterial pulse wave analysis) were measured.

RESULTS

No significant inverse relationships were observed between the serum O3FA levels and the AS/WR-related parameters. Adjusted values of the AS/WR-related parameters and serum CRP levels were higher in the subjects with serum O6FA levels in the highest tertile than in those with serum O6FA levels in the lowest tertile.

CONCLUSIONS

In healthy Japanese men with known high dietary intakes of O3FAs, the serum O3FA levels may not reflect the pathophysiological abnormalities related to AS/WR. Increased serum O6FA levels appeared to be independently associated with the unfavorable conditions related to AS/WR and inflammation.

Association of serum levels of arachidonic acid and eicosapentaenoic acid with prevalence of major adverse cardiac events after acute myocardial infarction

We studied the association of serum levels of arachidonic acid (AA) and eicosapentaenoic acid (EPA) with the prevalence of major adverse cardiac events (MACE) after acute myocardial infarction (AMI). We measured serum AA and EPA on admission in 146 consecutive AMI patients. The primary clinical endpoint was occurrence of MACE, defined as cardiac death, occurrence of heart failure, reinfarction, recurrent angina pectoris, and requirement of coronary intervention. Common logarithmic transformed serum levels of AA (logAA) and EPA (logEPA) were used in the analyses. The optimum cutoff point of each fatty acid used to distribute patients into two groups for Kaplan-Meier analysis was determined by receiver operating characteristic curves analysis. MACE occurred in 40 patients (27.4%). Kaplan-Meier analysis disclosed that the group with a logAA above the cutoff point [145.3 μg/mL (logAA 2.162)] showed a higher prevalence of MACE than those with a logAA below the cutoff point (P < 0.01). Conversely, the prevalence of MACE was significantly higher in the group with a logEPA below the cutoff point [52.3 μg/mL (logEPA 1.719)] compared to the group with a logEPA above it (P < 0.01). Similar to logAA, logAA/logEPA showed significant differences in the MACE-free curve between the two groups (cutoff 1.301, P < 0.001). Cox proportional hazards regression analysis suggested that logAA, logEPA, and logAA/logEPA were independently associated with the prevalence of MACE. Although the present study included a limited number of patients with single-time point measurement, the results suggested an association of logAA, logEPA, and logAA/logEPA with the prevalence of MACE after AMI. The present study warrants further studies involving a large number of patients to confirm that the serum levels of these fatty acids and their ratios are predictors of MACE after AMI.

Fatty acid synthase impacts the pathobiology of Candida parapsilosis in vitro and during mammalian infection

Cytosolic fungal fatty acid synthase is composed of two subunits α and β, which are encoded by Fas1 and Fas2 genes. In this study, the Fas2 genes of the human pathogen Candida parapsilosis were deleted using a modified SAT1 flipper technique. CpFas2 was essential in media lacking exogenous fatty acids and the growth of Fas2 disruptants (Fas2 KO) was regulated by the supplementation of different long chain fatty acids, such as myristic acid (14∶0), palmitic acid (16∶0), and Tween 80, in a dose-specific manner. Lipidomic analysis revealed that Fas2 KO cells were severely restricted in production of unsaturated fatty acids. The Fas2 KO strains were unable to form normal biofilms and were more efficiently killed by murine-like macrophages, J774.16, than the wild type, heterozygous and reconstituted strains. Furthermore, Fas2 KO yeast were significantly less virulent in a systemic murine infection model. The Fas2 KO cells were also hypersensitive to human serum, and inhibition of CpFas2 in WT C. parapsilosis by cerulenin significantly decreased fungal growth in human serum. This study demonstrates that CpFas2 is essential for C. parapsilosis growth in the absence of exogenous fatty acids, is involved in unsaturated fatty acid production, influences fungal virulence, and represents a promising antifungal drug target.

Systolic dysfunction in urban Japan

BACKGROUND

Heart failure (HF), which can be caused by left ventricular systolic dysfunction (LVSD), is a growing problem in developed countries with a large aging population. The aim of the present study was to characterize outpatients with LVSD in the adult population (45-84 years) in an urban Japanese community (Niigata City), and delineate their characteristics in comparison with those in a rural one (Sado).

METHODS AND RESULTS

Over a 5-year period, 1,297 patients (67% males) with LVSD (defined as ejection fraction < or =50%) were extracted from 87,953 echocardiography records available in 15 hospitals in Niigata City. The proportion of LVSD increased progressively with age (p-for-trend <0.0001), reaching 1-2% in those aged > or =75 years. The prevalence of comorbidities was noticeable (47% had hypertension, 41% myocardial ischemia, 34% atrial fibrillation, 33% previous hospitalization because of congestive HF, 27% cerebral stroke). In comparison with Sado, Niigata patients were younger, with a higher prevalence of comorbidities (hypertension, diabetes, dyslipidemia, and cerebral stroke).

CONCLUSIONS

As the proportion of LVSD cases increases progressively with age, it is expected to simulate a future epidemic. The differences between patients' characteristics and disease patterns in urban and rural communities may favor individually tailoring preventive strategies for HF in these areas.

Palmitic acid induces production of proinflammatory cytokine interleukin-8 from hepatocytes

Obesity and the metabolic syndrome are closely correlated with hepatic steatosis. Simple hepatic steatosis in nonalcoholic fatty liver disease can progress to nonalcoholic steatohepatitis (NASH), which can be a precursor to more serious liver diseases, such as cirrhosis and hepatocellular carcinoma. The pathogenic mechanisms underlying progression of steatosis to NASH remain unclear; however, inflammation, proinflammatory cytokines, and oxidative stress have been postulated to play key roles. We previously reported that patients with NASH have elevated serum levels of proinflammatory cytokines, such as interleukin-8 (IL-8), which are likely to contribute to hepatic injury. This study specifically examines the effect of hepatic steatosis on IL-8 production. We induced lipid accumulation in hepatocytes (HepG2, rat primary hepatocytes, and human primary hepatocytes) by exposing them to pathophysiologically relevant concentrations of palmitic acid to simulate the excessive influx of fatty acids into hepatocytes. Significant fat accumulation was documented morphologically by Oil Red O staining in cells exposed to palmitic acid, and it was accompanied by an increase in intracellular triglyceride levels. Importantly, palmitic acid was found to induce significantly elevated levels of biologically active neutrophil chemoattractant, IL-8, from steatotic hepatocytes. Incubation of the cells with palmitate led to increased IL-8 gene expression and secretion (both mRNA and protein) through mechanisms involving activation of nuclear factor kappaB (NF-kappaB) and c-Jun N-terminal kinase/activator protein-1.

CONCLUSION

These data demonstrate for the first time that lipid accumulation in hepatocytes can stimulate IL-8 production, thereby potentially contributing to hepatic inflammation and consequent liver injury.

Effects of an open-label pilot study with high-dose EPA/DHA concentrates on plasma phospholipids and behavior in children with attention deficit hyperactivity disorder

Background

Attention deficit hyperactivity disorder (ADHD) is the most common neurological condition in children. This pilot study evaluated the effects of high-dose eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on the isolated plasma phospholipids and behavior in children with ADHD (primarily inattentive subtype and combined subtype).

Methods

Nine children were initially supplemented with 16.2 g EPA/DHA concentrates per day. The dosage was adjusted dependent on the ratio of arachidonic acid (AA) to EPA in the isolated plasma phospholipids at four weeks to reach a level normally found in the Japanese population.

Results

At the end of the eight-week study, supplementation resulted in significant increases in EPA and DHA, as well as a significant reduction in the AA:EPA ratio (20.78 ± 5.26 to 5.95 ± 7.35, p < 0.01). A psychiatrist (blind to supplement compliance or dosage modifications) reported significant improvements in behavior (inattention, hyperactivity, oppositional/defiant behavior, and conduct disorder). There was also a significant correlation between the reduction in the AA:EPA ratio and global severity of illness scores.

Conclusion

The findings of this small pilot study suggest supplementation with high-dose EPA/DHA concentrates may improve behavior in children with ADHD.

Tissue n-3 and n-6 fatty acids and risk for coronary heart disease events

BACKGROUND

Tissue proportions of long chain n-6 [especially arachidonic acid (AA)] and n-3 fatty acids [FA; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) acids], or some ratio of these may be markers of risk for coronary heart disease (CHD). The purpose of this paper is to evaluate the published associations between risk for CHD events and tissue n-3 and n-6 FA composition.

METHODS

Case-control or prospective cohort data sets examining the risk for CHD endpoints as a function of tissue FA composition were identified. Effect sizes were computed for case versus control comparisons using standard meta-analytic methods.

RESULTS

Twenty-five studies were included, 18 examining the FA composition of phospholipid-rich and 7 of triglyceride-rich samples. DHA, with or without EPA, was significantly lower in cases than controls in all studies combined, in those with fatal endpoints, in those with prospective designs, and in both tissue types. The only setting where increased AA was associated with case status was in adipose tissue. The AA/EPA ratio in phospholipid-rich samples did not distinguish cases from controls. Lower linoleic acid content was associated with increased risk for non-fatal events.

CONCLUSIONS

The long-chain n-3 FA, especially DHA, were consistently and significantly reduced in patients experiencing CHD events. These findings add further support to the view that long-chain n-3 FA are cardioprotective.

Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis

BACKGROUND

Epidemiological and clinical evidence suggests that an increased intake of long-chain n-3 fatty acids protects against mortality from coronary artery disease. We aimed to test the hypothesis that long-term use of eicosapentaenoic acid (EPA) is effective for prevention of major coronary events in hypercholesterolaemic patients in Japan who consume a large amount of fish.

METHODS

18 645 patients with a total cholesterol of 6.5 mmol/L or greater were recruited from local physicians throughout Japan between 1996 and 1999. Patients were randomly assigned to receive either 1800 mg of EPA daily with statin (EPA group; n=9326) or statin only (controls; n=9319) with a 5-year follow-up. The primary endpoint was any major coronary event, including sudden cardiac death, fatal and non-fatal myocardial infarction, and other non-fatal events including unstable angina pectoris, angioplasty, stenting, or coronary artery bypass grafting. Analysis was by intention-to-treat. The study was registered at ClinicalTrials.gov, number NCT00231738.

FINDINGS

At mean follow-up of 4.6 years, we detected the primary endpoint in 262 (2.8%) patients in the EPA group and 324 (3.5%) in controls-a 19% relative reduction in major coronary events (p=0.011). Post-treatment LDL cholesterol concentrations decreased 25%, from 4.7 mmol/L in both groups. Serum LDL cholesterol was not a significant factor in a reduction of risk for major coronary events. Unstable angina and non-fatal coronary events were also significantly reduced in the EPA group. Sudden cardiac death and coronary death did not differ between groups. In patients with a history of coronary artery disease who were given EPA treatment, major coronary events were reduced by 19% (secondary prevention subgroup: 158 [8.7%] in the EPA group vs 197 [10.7%] in the control group; p=0.048). In patients with no history of coronary artery disease, EPA treatment reduced major coronary events by 18%, but this finding was not significant (104 [1.4%] in the EPA group vs 127 [1.7%] in the control group; p=0.132).

INTERPRETATION

EPA is a promising treatment for prevention of major coronary events, and especially non-fatal coronary events, in Japanese hypercholesterolaemic patients.

The Group B Streptococcus NADH oxidase Nox-2 is involved in fatty acid biosynthesis during aerobic growth and contributes to virulence

Numerous Streptococcaceae produce an H2O-forming NADH oxidase, Nox-2, which has been generally implicated in aerobic survival. We examined the roles of Nox-2 in Group B Streptococcus (GBS), a leading agent of neonatal infections. While nox2 inactivation caused an aerobic growth arrest, no improvement was seen by addition of antioxidants to cultures, suggesting that this defect was not due to accumulation of toxic oxygen species. Using several approaches, we show that the observed inability of the nox2 mutant to grow aerobically is mainly due to an underlying defect in fatty acid (FA) biosynthesis: (i) the nox2 aerobic growth defect is fully and rapidly complemented by adding oleic acid to culture medium, and (ii) direct assimilation of this unsaturated FA in both wild type (WT) and nox2 GBS membranes is demonstrated and correlated with mutant growth rescue. We propose that NAD+ depletion in the nox2 mutant results in reduced acetyl-CoA production, which perturbs FA biosynthesis and hence blocks growth in aerobiosis. The nox2 aerobic growth defect was also complemented when GBS respiration metabolism was activated by exogenous haem and menaquinone. The membrane NADH oxidase activity generated by the functional respiratory chain thus compensates the cytoplasmic NADH oxidase deficiency. The nox2 mutant was attenuated for virulence, as assessed in lung, intraperitoneal and intravenous murine infection models. As the nox2 defect seems only to affect aerobic growth of GBS, its reduced virulence supports the suggestion that aerobic conditions and NADH oxidase activities are relevant to the GBS infection process.

Needs to Change the Direction of Cholesterol-related Medication—A Problem of Great Urgency

The cholesterol hypothesis implies that reducing the intake of saturated fatty acids and cholesterol and increasing that of polyunsaturated fatty acid are effective in lowering serum total cholesterol (TC), and thereby reducing the incidence of coronary heart disease (CHD). However, these dietary recommendations are essentially ineffective in reducing TC in the long run, but rather increase mortality rates from CHD and all causes. The reported "apparent relative risk of high TC in CHD mortality" (the ratio of mortality at the highest/lowest TC levels) varied several-fold among populations studied. The incidence of familial hypercholesterolemia (FH) in a population was proposed to be a critical factor in the observed variability, which could be accounted for by assuming that 1) the high CHD mortality rate in high-TC groups is mainly a reflection of the incidence and severity of FH, and 2) high TC is not a causative factor of CHD in non-FH cases. This interpretation is supported by recent observations that high TC is not positively associated with high CHD mortality rates among general populations more than 40-50 years of age. More importantly, higher TC values are associated with lower cancer and all-cause mortality rates among these populations, in which relative proportions of FH are likely to be low (circa 0.2%). Although the effectiveness of statins in preventing CHD has been accepted in Western countries, little benefit seems to result from efforts to limit dietary cholesterol intake or to TC values to less than approximately 260 mg/dl among the general population and the elderly. Instead, an unbalanced intake of omega6 over omega3 polyunsaturated fats favors the production of eicosanoids, the actions of which lead to the production of inflammatory and thrombotic lipid mediators and altered cellular signaling and gene expression, which are major risk factors for CHD, cancers, and shorter longevity. Based on the data reviewed here, it is urgent to change the direction of current cholesterol-related medication for the prevention of CHD, cancer, and all-cause mortality.

A study on the causes for the elevated n-3 fatty acids in cows' milk of alpine origin

The influence of grass-only diets either from rye-grass-dominated lowland pastures (400 m above sea level) or botanically diverse alpine pastures (2000 m) on the FA profile of milk was investigated using three groups of six Brown Swiss cows each. Two groups were fed grass-only on pasture (P) or freshly harvested in barn (B), both for two experimental periods in the lowlands and, consecutively, two periods on the alp. Group C served as the control, receiving a silage-concentrate diet and permanently staying in the lowlands. Effects of vegetation stage or pasture vs. barn feeding on milk fat composition were negligible. Compared with the control, alpha-linolenic acid (18:3n-3) consumption was elevated in groups P and B (79%; P< 0.001) during the lowland periods but decreased on the alp to the level of C owing to feed intake depression and lower 18:3n-3 concentration in the alpine forage. Average 18:3n-3 contents of milk fat were higher in groups P and B than in C by 33% (P< 0.01) at low and by 96% (P < 0.001) at high altitude, indicating that 18:3n-3 levels in milk were to some extent independent of 18:3n-3 consumption. The cis-9, trans-11 CLA content in milk of grass-fed cows was higher compared with C but lower for the alpine vs. lowland periods whereas the trans-11, cis-13 isomer further increased with altitude. Long-chain n-3 FA and phytanic acid increased while arachidonic acid decreased with grass-only feeding, but none of them responded to altitude. Grass-only feeding increased milk alpha-tocopherol concentration by 86 and 134% at low and high altitude (P < 0.001), respectively. Changes in the ruminal ecosystem due to energy shortage or specific secondary plant metabolites are discussed as possible causes for the high 18:3n-3 concentrations in alpine milk.

Statin treatment alters serum n-3 and n-6 fatty acids in hypercholesterolemic patients

Statins are highly effective cholesterol-lowering drugs but may have broader effects on metabolism. This investigation examined effects of simvastatin on serum levels of n-6 and n-3 polyunsaturated fatty acids (PUFAs). Subjects were 106 healthy adults with hypercholesterolemia randomly assigned to receive placebo or 40 mg simvastatin daily for 24 weeks. Serum fatty acids were analyzed by gas chromatography. Total fatty acid concentration fell 22% in subjects receiving simvastatin (P<.001), with similar declines across most fatty acids. However, concentrations of arachidonic acid (AA, 20:4n-6), eicosapentanoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) were unchanged. Relative percentages of linoleic acid (LA, 18:2n-6) and alpha-linolenic acid (LNA, 18:3n-3), decreased while AA and DHA increased (P's < or = .007). In addition, simvastatin increased the AA:EPA ratio from 15.5 to 18.8 (P<.01), and tended to increase the AA:DHA ratio (P=.053). Thus, simvastatin lowered serum fatty acid concentrations while also altering the relative percentages of important PUFAs.

Dietary habits and plasma fatty acids levels in a population of Italian children: is there any relationship?

The relationships between dietary habits and the blood fatty acid (FA) profile have been poorly explored, particularly in children. Aim of the present investigation was to look at the associations between dietary habits and the plasma pattern of FA in a school-age population. In 105 healthy 8-years old children, the nutritional habits have been evaluated by means of a Food Frequency Questionnaire and a 24-h recall. FA analyses (expressed as FA%) were performed by means of capillary gas chromatography.

STATISTICS

non-parametric tests. The children with high pasta and low red meat consumption (n = 9), compared to those with either medium or low pasta and either high or medium red meat consumption (n = 96), showed lower levels of total saturated (29% vs. 35%, P = 0.001) and higher levels of total monounsaturated (30% vs. 24%, P = 0.04) FA in plasma. They also showed lower levels of LDL cholesterol (90 vs. 109 mg/dl, P = 0.08) and fasting insulin (4.0 vs. 6.3 microU/ml, P = 0.04) in blood. A high consumption of pasta coupled with a low intake of red meat may be marker of a food behaviour and/or lifestyle associated with a more favourable pattern of circulating FA and hematochemical metabolic markers.