Eicosapentaenoic Acid Prevents LPS-Induced TNF-α Expression by Preventing NF-κB Activation

Health implications of high dietary omega-6 polyunsaturated Fatty acids

Omega-6 (n-6) polyunsaturated fatty acids (PUFA) (e.g., arachidonic acid (AA)) and omega-3 (n-3) PUFA (e.g., eicosapentaenoic acid (EPA)) are precursors to potent lipid mediator signalling molecules, termed "eicosanoids," which have important roles in the regulation of inflammation. In general, eicosanoids derived from n-6 PUFA are proinflammatory while eicosanoids derived from n-3 PUFA are anti-inflammatory. Dietary changes over the past few decades in the intake of n-6 and n-3 PUFA show striking increases in the (n-6) to (n-3) ratio (~15 : 1), which are associated with greater metabolism of the n-6 PUFA compared with n-3 PUFA. Coinciding with this increase in the ratio of (n-6) : (n-3) PUFA are increases in chronic inflammatory diseases such as nonalcoholic fatty liver disease (NAFLD), cardiovascular disease, obesity, inflammatory bowel disease (IBD), rheumatoid arthritis, and Alzheimer's disease (AD). By increasing the ratio of (n-3) : (n-6) PUFA in the Western diet, reductions may be achieved in the incidence of these chronic inflammatory diseases.

Basic aspects of tumor cell fatty acid-regulated signaling and transcription factors

This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.

The effects of an oral supplement enriched with fish oil, prebiotics, and antioxidants on nutrition status in Crohn's disease patients

BACKGROUND

Research in the treatment of Crohn's disease (CD) supports anti-inflammatory benefits of n-3 fatty acids from fish oil, prebiotics, and antioxidants. A nutritionally balanced inflammatory bowel disease nutrition formula (IBDNF) enriched with these compounds has the potential to improve nutrition status and disease activity in CD.

METHODS

This is an open-label pilot study investigating the effects of IBDNF on nutrition status in CD patients. Twenty-eight patients with active CD on stable medication were asked to consume 16 oz of IBDNF/d for 4 months. Nutrition status was assessed with dual-energy X-ray absorptiometry scans and serum micronutrient levels. Disease activity and quality of life were measured using the Crohn's Disease Activity Index (CDAI) and the Inflammatory Bowel Disease Questionnaire (IBDQ).

RESULTS

Twenty patients completed the final visit. After 4 months, there was a significant decrease in plasma phospholipid levels of arachidonic acid with increases in eicosapentaenoic acid (EPA) and docosahexaenoic acid. Ten patients had a final EPA concentration of >2%. There was improvement in fat-free and fat mass in patients with final EPA >2% (P = .014 and P = .05). Vitamin D (25-OH) levels improved in all patients (18.5-25.9 ng/mL, P < .001). Those with EPA >2% had significantly lower CDAI (116 ± 94.5 vs 261.8 ± 86.5; P = .005) and higher IBDQ (179.1 ± 26.6 vs 114.6 ± 35.9, P < .001) compared to those with EPA <2%.

CONCLUSIONS

IBDNF has the potential to deposit fat-free and fat mass, improve vitamin D status, and improve quality of life in CD patients.

Enhanced anti-inflammatory effect of resveratrol and EPA in treated endotoxin-activated RAW 264.7 macrophages

Macrophages play an important role in immunogenic challenges by producing reactive oxygen species, NO and proinflammatory cytokines that can aggravate and propagate local inflammation. Multiple mechanisms regulate these inflammatory processes. NF-κB and activator protein 1 pathways are crucial in the expression of proinflammatory genes, such as TNF-α, IL-1 (α or β) and -6. Some polyphenols, which are present in beverages, vegetables and fruits, and PUFA, which are present in marine oils and fish food, possess anti-inflammatory effects in vivo and in vitro. Our aim in the present study was to assess whether polyphenols and PUFA have synergistic anti-inflammatory effects in murine macrophages in vitro. Inflammation in RAW 264.7 macrophages was induced by lipopolysaccharide at 100 ng/ml. The treatments with molecules were performed by co-incubation for 19 h. A NO production assay by Griess reaction, a phosphoprotein assay by Pathscan ELISA kit and gene expression analysis using the TaqMan® Low-density Array for ninety-one genes related to inflammation, oxidative stress and metabolism were performed to assess the synergistic anti-inflammatory effects of polyphenols, epigallocatechin gallate and resveratrol (Res; 2·5 μg/ml), and the PUFA, DHA and EPA (30 μm). Adding Res+EPA had an enhanced anti-inflammatory effect, in comparison with EPA and Res alone, leading to decreased NO levels; modulating the phospho-stress activated protein kinase/Jun N-terminal kinase (P-SAPK/JNK) level; down-regulating proinflammatory genes, such as IL, chemokines, transcription factors; and up-regulating several antioxidant genes. Therefore, this combination has a stronger anti-inflammatory effect than either of these molecules separately in RAW macrophages.

Health benefits of n-3 polyunsaturated fatty acids: eicosapentaenoic acid and docosahexaenoic acid

Marine-based fish and fish oil are the most popular and well-known sources of n-3 polyunsaturated fatty acids (PUFAs), namely, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These n-3 PUFAs are known to have variety of health benefits against cardiovascular diseases (CVDs) including well-established hypotriglyceridemic and anti-inflammatory effects. Also, various studies indicate promising antihypertensive, anticancer, antioxidant, antidepression, antiaging, and antiarthritis effects. Moreover, recent studies also indicate anti-inflammatory and insulin-sensitizing effects of these fatty acids in metabolic disorders. Classically, n-3 PUFAs mediate some of these effects by antagonizing n-6 PUFA (arachidonic acid)-induced proinflammatory prostaglandin E₂ (PGE₂) formation. Another well-known mechanism by which n-3 PUFAs impart their anti-inflammatory effects is via reduction of nuclear factor-κB activation. This transcription factor is a potent inducer of proinflammatory cytokine production, including interleukin 6 and tumor necrosis factor-α, both of which are decreased by EPA and DHA. Other evidence also demonstrates that n-3 PUFAs repress lipogenesis and increase resolvins and protectin generation, ultimately leading to reduced inflammation. Finally, beneficial effects of EPA and DHA in insulin resistance include their ability to increase secretion of adiponectin, an anti-inflammatory adipokine. In summary, n-3 PUFAs have multiple health benefits mediated at least in part by their anti-inflammatory actions; thus their consumption, especially from dietary sources, should be encouraged.

Ratio of serum n-3 to n-6 polyunsaturated fatty acids and the incidence of major adverse cardiac events in patients undergoing percutaneous coronary intervention

BACKGROUND

The relationship between major adverse cardiac events (MACE) and serum polyunsaturated fatty acid (PUFA) parameters has not been well documented in patients who have undergone percutaneous coronary intervention (PCI). The aim of the present study was to investigate this relationship.

METHODS AND RESULTS

A total of 284 consecutive patients who underwent elective PCI were enrolled and stratified according to median serum levels of n-6 PUFAs (arachidonic acid [AA]), n-3 PUFAs (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]), and serum EPA/AA and DHA/AA ratios. The relationship between these PUFA parameters and the incidence of MACE including cardiac death, acute coronary syndrome, PCI for de novo lesions, and coronary artery bypass grafting, was analyzed. Multivariate analysis showed that among the PUFA parameters, only a high serum EPA/AA ratio was significantly associated with a low incidence of MACE in all the models tested (model A, without adjusted variables: hazard ratio [HR], 0.52; 95% confidence interval [CI]: 0.27-0.99, P = 0.048; model B, adjusted for age and diabetes: HR, 0.51; 95%CI: 0.26-0.98, P = 0.043; model C, adjusted for age, sex, diabetes, hypertension, smoking, and low-density lipoprotein cholesterol: HR, 0.49; 95%CI: 0.25-0.94, P = 0.033).

CONCLUSIONS

The incidence of MACE in patients who have undergone PCI is significantly associated with serum EPA/AA ratio.

Comparison of the effects of the n-3 polyunsaturated fatty acid eicosapentaenoic and fenofibrate on the inhibitory effect of arthritis on IGF1

Adjuvant-induced arthritis is a chronic inflammatory illness that induces muscle wasting and decreases circulating IGF1. Eicosapentaenoic acid (EPA) and fenofibrate, a peroxisome proliferator-activated receptors α agonist, have anti-inflammatory actions and ameliorate muscle wasting in arthritic rats. The aim of this work was to elucidate whether EPA and fenofibrate administration are able to prevent the effect of arthritis on the IGF1-IGFBP system. On day 4 after adjuvant injection control, arthritic rats were gavaged with EPA (1 g/kg) or fenofibrate (300 mg/kg) until day 15 when all rats were killed. Arthritis decreased body weight gain, serum IGF1, and liver Igf1 mRNA, whereas it increased gastrocnemius Igfbp3 mRNA. EPA, but not fenofibrate, administration prevented arthritis-induced decrease in serum IGF1 and liver Igf1 mRNA. In the rats treated with EPA arthritis increased Igfbp5 mRNA in the gastrocnemius. Fenofibrate treatment decreased IGF1 and Igf1 mRNA in the liver and gastrocnemius. In arthritic rats, fenofibrate increased body weight gain and decreased gastrocnemius Igfbp3 and Igfbp5 mRNA. These data suggest that the mechanisms through which EPA and fenofibrate act on the IGF1 system and ameliorate muscle wasting in arthritic rats are different. EPA administration increased circulating levels of IGF1, whereas fenofibrate decreased the Igfbp3 and Igfbp5 in the gastrocnemius muscle.

Obesity modifies the association between plasma phospholipid polyunsaturated fatty acids and markers of inflammation: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND OBJECTIVE

Systemic inflammation is a well-known risk factor for diseases such as atherosclerosis and is augmented by the presence of obesity. In addition, it has been shown that inflammation may be negatively influenced by certain macronutrients, specifically the omega-3 and omega-6 fatty acids. The primary aim of this study is to determine whether obesity modifies the association between plasma phospholipid polyunsaturated fatty acids (PUFAs) and markers of inflammation and endothelial activation in Multi-Ethnic Study of Atherosclerosis (MESA) participants.

SUBJECTS

A sample of 2848 adults (25% African American, Chinese, Hispanic, and White) randomly selected from the MESA cohort.

MEASUREMENTS

Relative plasma PUFA concentrations were determined using gas chromatography-flame ionization detection. Levels of three inflammatory markers (high-sensitivity C-reactive protein, interleukin (IL)-6 and tumor necrosis factor-receptor 1) and two endothelial activation markers (soluble intercellular adhesion molecule-1 (sICAM-1) and E-selectin) were determined with enzyme immunoassays. Linear regression analysis was used to evaluate the relationship between these markers and plasma PUFAs.

RESULTS

Obesity modified the associations of linoleic acid (P(int)=0.01), dihomo-γ-linolenic (P(int)=0.07) and eicosapentaenoic acid (EPA) (P(int)=0.04) with sICAM-1 concentrations; in addition, obesity modified the association of IL-6 with dihomo-γ-linolenic (P(int)=0.01). In obese individuals, sICAM-1 was inversely related to EPA levels (P=0.02), but directly related to linoleic acid levels (P<0.001). Conversely, sICAM-1 was inversely related to linoleic acid levels in normal weight individuals (P=0.04). IL-6 concentrations were significantly and directly related to dihomo-γ-linolenic acid (DGLA) in normal weight (P=0.01) and obese participants (P<0.001), but the scale of increase across tertiles was greater in obese adults. Main effects of fatty acid and inflammatory marker associations are also reported.

CONCLUSION

The modifying effect of obesity on the association of plasma PUFAs with IL-6 and sICAM-1 suggests differences in fatty acid metabolism and may also have implications in dietary fatty acid intake for obese individuals, particularly for linoleic and EPAs. Further study is warranted to confirm and explain the strong associations of DGLA with inflammatory and endothelial activation markers.

Marine omega-3 fatty acids and mood disorders--linking the sea and the soul. 'Food for Thought' I

OBJECTIVE

While there has long been interest in any nutritional contribution to the onset and treatment of mood disorders, there has been increasing scientific evaluation of several candidate nutritional and dietary factors in recent years. In this inaugural study of our 'Food for Thought' series, we will overview the evidence for any role of omega-3 fatty acids (FA) in regulating mood.

METHOD

Relevant literature was identified through online database searches and cross-referencing.

RESULTS

Plausible mechanisms exist by which omega-3 FA may influence neuronal function and mood. Cross-sectional studies demonstrate an association between omega-3 fatty acid deficiency and both depressive and bipolar disorders. Studies investigating the efficacy of omega-3 fatty acid supplementation for mood disorders have however provided inconsistent results. The proportion of treatment studies showing a significant advantage of omega-3 supplementation has dropped over the last 5 years. However, the vast heterogeneity of the trials in terms of constituent omega-3 FAs, dose and length of treatment makes comparisons of these studies difficult.

CONCLUSION

More research is required before omega-3 supplementation can be firmly recommended as an effective treatment for mood disorders. Whereas increased omega-3 FA intake may alleviate depressive symptoms, there is little evidence of any benefit for mania.

The PLIN4 variant rs8887 modulates obesity related phenotypes in humans through creation of a novel miR-522 seed site

PLIN4 is a member of the PAT family of lipid storage droplet (LSD) proteins. Associations between seven single nucleotide polymorphisms (SNPs) at human PLIN4 with obesity related phenotypes were investigated using meta-analysis followed by a determination if these phenotypes are modulated by interactions between PLIN4 SNPs and dietary PUFA. Samples consisted of subjects from two populations of European ancestry. We demonstrated association of rs8887 with anthropometrics. Meta-analysis demonstrated significant interactions between the rs8887 minor allele with PUFA n3 modulating anthropometrics. rs884164 showed interaction with both n3 and n6 PUFA modulating anthropometric and lipid phenotypes. In silico analysis of the PLIN4 3'UTR sequence surrounding the rs8887 minor A allele predicted a seed site for the human microRNA-522 (miR-522), suggesting a functional mechanism. Our data showed that a PLIN4 3'UTR luciferase reporter carrying the A allele of rs8887 was reduced in response to miR-522 mimics compared to the G allele. These results suggest variation at the PLIN4 locus, and its interaction with PUFA as a modulator of obesity related phenotypes, acts in part through creation of a miR-522 regulatory site.

n-3 Fatty acids block TNF-α-stimulated MCP-1 expression in rat mesangial cells

Monocyte chemoattractant protein 1 (MCP-1) is a CC cytokine that fundamentally contributes to the pathogenesis of inflammatory renal disease. MCP-1 is highly expressed in cytokine-stimulated mesangial cells in vitro and following glomerular injury in vivo. Interventions to limit MCP-1 expression are commonly effective in assorted experimental models. Fish oil, an abundant source of n-3 fatty acids, has anti-inflammatory properties, the basis of which remains incompletely defined. We examined potential mechanisms whereby fish oil reduces MCP-1 expression and thereby suppresses inflammatory responses to tissue injury. Cultured mesangial cells were treated with TNF-α in the presence of the n-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA); equimolar concentrations of the n-6 fatty acids LA and OA served as controls. MCP-1 mRNA expression was assessed by Northern blotting, and transcriptional activity of the MCP-1 promoter was assessed by transient transfection. The involvement of the ERK and NF-κB pathways was evaluated through transfection analysis and the use of the MEK inhibitor U0126. DHA and EPA decreased TNF-α-stimulated MCP-1 mRNA expression by decreasing transcription of the MCP-1 gene. DHA and EPA decreased p-ERK expression and nuclear translocation of NF-κB, both of which are necessary for TNF-α-stimulated MCP-1 expression. Both NF-κB and AP-1 sites were involved in transcriptional regulation of the MCP-1 gene by DHA and EPA. We conclude that DHA and EPA inhibit TNF-α-stimulated transcription of the MCP-1 gene through interaction of signaling pathways involving ERK and NF-κB. We speculate that such effects may contribute to the salutary effect of fish oil in renal and vascular disease.

Innate immunity signaling pathways: links between immunonutrition and responses to sepsis

Septic infections in patients treated in intensive care units show the highest mortality rates. Despite advances in treatment methods, there is still no therapy available to efficiently reduce the excessive inflammatory response, which can increase the risk of multiple organ failure. One of the ways to discover new, more efficient treatment methods involves regulating the mechanisms of inflammatory response to a massive infection. Toll-like receptors (TLRs) that recognize pathogen-associated molecular patterns play a significant role in innate antibacterial and inflammatory responses. The regulatory impact of immunonutrition on TLR expression in septic patients seems to be a promising research direction. This paper presents the main mechanisms for the innate immune response to lipopolysaccharide, based on the research results for both TLR-dependent and independent signaling pathways. Special emphasis was put on the research results for the TLR-dependent immune response and the anti-bacterial/anti-inflammatory response after applying immunonutrition with increased concentrations of glutamine and unsaturated fatty acids.

ω-3 fatty acids suppress inflammatory cytokine production by macrophages and hepatocytes

OBJECTIVE

Long-term total parenteral nutrition (TPN) in children is often complicated by parental nutrition-associated liver disease and may even lead to liver failure. Recently, the addition of ω-3 fatty acids to TPN has been shown to reduce the risk of parental nutrition-associated liver disease. The purpose of this study was to explore the anti-inflammatory effects of ω-3 fatty acids (eicosapentaenoic acid [EPA]) to demonstrate the protection of the liver against hepatic steatosis and damage.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) and prostaglandin E(2) (PGE(2)) were used to stimulate human macrophages and hepatocytes (THLE-3) to induce in vitro inflammatory condition. The cells were then incubated with either ω-3 (EPA) or ω-6 (arachidonic acid) fatty acids. Supernatants were collected at different time points for the measurement of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and interleukin 10 (IL-10) using enzyme-linked immunosorbent assay. Furthermore, pretreated macrophages by LPS stimulation and after incubation with EPA were added to prestimulated hepatocytes for the subsequent measurement of cytokine response.

RESULTS

Eicosapentaenoic acid effectively reduced LPS-induced or PGE(2)-induced TNF-α and IL-6 expression, and increased IL-10 expression significantly when compared with arachidonic acid. Furthermore, supernatant collected after co-culturing EPA with macrophages also suppressed the levels of TNF-α and IL-6 in hepatocytes. This would suggest that EPA not only had an anti-inflammatory effect on macrophages and hepatocytes directly, it could indirectly reduce hepatocyte inflammation through activated macrophages.

CONCLUSIONS

The addition of ω-3 fatty acids in TPN suppresses the inflammatory response via direct and indirect routes. The findings may help explain the clinical benefits of EPA in pediatric patients receiving long-term TPN.

Relationships between plasma fatty acid composition and coronary artery disease

AIM

The Japan EPA Lipid Intervention Study (JELIS) was the first prospective randomized clinical trial to demonstrate prevention of coronary events by pure eicosapentaenoic acid (EPA). The aim of this study was to examine the relationships between various plasma fatty acid concentrations and the risk of coronary events in JELIS participants.

METHODS

In 15,534 participants, we calculated the hazard ratio for major coronary events (sudden cardiac death, fatal or nonfatal myocardial infarction, unstable angina pectoris, and angioplasty/stenting or coronary artery bypass grafting) relative to the on-treatment average level of plasma fatty acids with the Cox proportional hazard model.

RESULTS

As a result of EPA intervention, the plasma EPA concentration increased, but the docosahexaenoic acid (DHA) concentration did not. The other fatty acids measured decreased slightly. The higher plasma level of EPA (hazard ratio=0.83, p=0.049, in all participants and hazard ratio=0.71, p=0.018, in the EPA intervention group), but not of DHA, was inversely associated with the risk of major coronary events. The associations between other fatty acids and the risk of major coronary events were not significant. In all JELIS participants, the risk of major coronary events was significantly decreased (20%) in the group with high (150 µg/mL or more) on-treatment plasma EPA concentration compared with that in the low (less than 87 µg/mL) group.

CONCLUSION

The risk of coronary artery disease is influenced by variations in plasma fatty acid composition. Among n-3 polyunsaturated fatty acids, EPA and DHA exhibited differences in the correlation with the risk of major coronary events.

Omega-3 fatty acids in critical illness

Supplementation of enteral nutritional formulas and parenteral nutrition lipid emulsions with omega-3 fatty acids is a recent area of research in patients with critical illness. It is hypothesized that omega-3 fatty acids may help reduce inflammation in critically ill patients, particularly those with sepsis and acute lung injury. The objective of this article is to review the data on supplementing omega-3 fatty acids during critical illness; enteral and parenteral supplemental nutrition are reviewed separately. The results of the research available to date are contradictory for both enteral and parenteral omega-3 fatty acid administration. Supplementation with omega-3 fatty acids may influence the acute inflammatory response in critically ill patients, but more research is needed before definitive recommendations about the routine use of omega-3 fatty acids in caring for critically ill patients can be made.

Eicosapentaenoic acid prevents and reverses insulin resistance in high-fat diet-induced obese mice via modulation of adipose tissue inflammation

We investigated the effects of eicosapentaenoic acid (EPA) on prevention (P) and reversal (R) of high saturated-fat (HF) diet-induced obesity and glucose-insulin homeostasis. Male C57BL/6J mice were fed low-fat (LF; 10% energy from fat), HF (45% energy from fat), or a HF-EPA-P (45% energy from fat; 36 g/kg EPA) diet for 11 wk. A 4th group was initially fed HF for 6 wk followed by the HF-EPA-R diet for 5 wk. As expected, mice fed the HF diet developed obesity and glucose intolerance. In contrast, mice fed the HF-EPA-P diet maintained normal glucose tolerance despite weight gain compared with the LF group. Whereas the HF group developed hyperglycemia and hyperinsulinemia, both HF-EPA groups (P and R) exhibited normal glycemia and insulinemia. Further, plasma adiponectin concentration was lower in the HF group but was comparable in the LF and HF-EPA groups, suggesting a role of EPA in preventing and improving insulin resistance induced by HF feeding. Further analysis of adipose tissue adipokine levels and proteomic studies in cultured adipocytes indicated that dietary EPA supplementation of HF diets was associated with reduced adipose inflammation and lipogenesis and elevated markers of fatty acid oxidation. In C57BL/6J mice, EPA minimized saturated fat-induced insulin resistance and this is in part mediated by its effects on fatty acid oxidation and inflammation.

The acute administration of eicosapentaenoic acid is neuroprotective after spinal cord compression injury in rats

The aim of the present study was to investigate the effects of treatment with eicosapentaenoic acid (EPA) after spinal cord compression injury in adult rats. Saline or EPA (250 nmol/kg) was administered intravenously 30 min after compression injury. Locomotor recovery was assessed daily using the BBB open-field locomotor score. One week after injury, animals were sacrificed and the spinal cord tissue containing the compression epicenter, and the adjacent rostral and caudal segments, was immunostained using specific markers for neurons, oligodendrocytes, axonal injury, and macrophages/microglia. Administration of EPA resulted in decreased axonal injury and increased neuronal and oligodendrocyte survival, in the lesion epicenter and adjacent tissue. The behavioural assessment mirrored the neuroprotective effects and showed a significantly improved functional recovery in animals treated with EPA compared to the saline-treated controls over the 7-day period. These observations suggest that EPA has neuroprotective properties when administered after spinal cord trauma.

The beneficial effect of n-3 polyunsaturated fatty acids on doxorubicin-induced chronic heart failure in rats

This study was designed to assess the effects of dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) from fish oil on the response of doxorubicin-induced chronic heart failure in rats. Male Sprague-Dawley rats were treated daily for 8 weeks with normal saline or n-3 PUFA intragastrically after induction of myocardial injury by intraperitoneal injection of doxorubicin 2 mg/kg once weekly for 8 weeks. Cardiac function was assessed by echocardiography. The cytoprotective role of n-3 PUFA against doxorubicin-induced myocardial injury was demonstrated by light microscopy, and serum cytokines (tumour necrosis factor-alpha and interleukin-10) were analysed by enzyme-linked immunosorbent assay. Doxorubicin induced death, alterations in echocardiography parameters and histological damage, all of which are features that characterize heart failure. There were significant differences between the doxorubicin-induced heart failure group and the n-3 PUFA-treated group in terms of echocardiography parameters and cytokine changes. Thus, dietary supplementation with n-3 PUFA attenuated doxorubicin-induced cardiac dysfunction, an effect that might be associated with recovery from an imbalance of the cytokine network.

Supplementation with EPA or fish oil for 11 months lowers circulating lipids, but does not delay the onset of diabetes in UC Davis-type 2 diabetes mellitus rats

EPA or fish oil supplementation has been suggested as treatments for the prevention of type 2 diabetes mellitus (T2DM) due to their lipid-lowering and potential insulin-sensitising effects. We investigated the effects of supplementation with EPA (1 g/kg body weight per d) or fish oil (3 g/kg body weight per d) on the age of onset of T2DM and circulating glucose, insulin, lipids, leptin and adiponectin in UC Davis (UCD)-T2DM rats. Animals were divided into three groups starting at 1 month of age: control, EPA and fish oil. All the animals were followed until diabetes onset or for up to 12 months of age. Monthly fasting blood samples were collected for the measurement of glucose, lipids, hormones and C-reactive protein (CRP). Neither EPA nor fish oil delayed the onset of T2DM or altered fasting plasma glucose, insulin, CRP, adiponectin or leptin concentrations. The groups did not differ in energy intake or body weight. Fish oil treatment lowered fasting plasma TAG concentrations by 39 (sd 7) % (P < 0.001) and EPA lowered fasting plasma NEFA concentrations by 23 (sd 5) % (P < 0.05) at 4 months of age compared with the control group. EPA and fish oil lowered fasting plasma cholesterol concentrations at 4 months of age by 19 (sd 4) and 22 (sd 4) % compared with the control group, respectively (both P < 0.01). In conclusion, EPA and fish oil supplementation lowers circulating lipid concentrations, but does not delay the onset of T2DM in UCD-T2DM rats.

Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids

Omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) are precursors of potent lipid mediators, termed eicosanoids, which play an important role in the regulation of inflammation. Eicosanoids derived from n-6 PUFAs (e.g., arachidonic acid) have proinflammatory and immunoactive functions, whereas eicosanoids derived from n-3 PUFAs [e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] have anti-inflammatory properties, traditionally attributed to their ability to inhibit the formation of n-6 PUFA-derived eicosanoids. While the typical Western diet has a much greater ratio of n-6 PUFAs compared with n-3 PUFAs, research has shown that by increasing the ratio of n-3 to n-6 fatty acids in the diet, and consequently favoring the production of EPA in the body, or by increasing the dietary intake of EPA and DHA through consumption of fatty fish or fish-oil supplements, reductions may be achieved in the incidence of many chronic diseases that involve inflammatory processes; most notably, these include cardiovascular diseases, inflammatory bowel disease (IBD), cancer, and rheumatoid arthritis, but psychiatric and neurodegenerative illnesses are other examples.

EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials

BACKGROUND

Epidemiologic and case-control data suggest that increased dietary intake of omega-3 long-chain polyunsaturated fatty acids (omega3 LC-PUFAs) may be of benefit in depression. However, the results of randomized controlled trials are mixed and controversy exists as to whether either eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) or both are responsible for the reported benefits.

OBJECTIVE

The aim of the current study was to provide an updated meta-analysis of all double-blind, placebo-controlled, randomized controlled trials examining the effect of omega3 LC-PUFA supplementation in which depressive symptoms were a reported outcome. The study also aimed to specifically test the differential effectiveness of EPA versus DHA through meta-regression and subgroup analyses.

DESIGN

Studies were selected using the PubMed database on the basis of the following criteria: (1) randomized design; (2) placebo controlled; (3) use of an omega3 LC-PUFA preparation containing DHA, EPA, or both where the relative amounts of each fatty acid could be quantified; and (4) reporting sufficient statistics on scores of a recognizable measure of depressive symptoms.

RESULTS

Two hundred forty-one studies were identified, of which 28 met the above inclusion criteria and were therefore included in the subsequent meta-analysis. Using a random effects model, overall standardized mean depression scores were reduced in response to omega3 LC-PUFA supplementation as compared with placebo (standardized mean difference = -0.291, 95% CI = -0.463 to -0.120, z = -3.327, p = 0.001). However, significant heterogeneity and evidence of publication bias were present. Meta-regression studies showed a significant effect of higher levels of baseline depression and lower supplement DHAEPA ratio on therapeutic efficacy. Subgroup analyses showed significant effects for: (1) diagnostic category (bipolar disorder and major depression showing significant improvement with omega3 LC-PUFA supplementation versus mild-to-moderate depression, chronic fatigue and non-clinical populations not showing significant improvement); (2) therapeutic as opposed to preventive intervention; (3) adjunctive treatment as opposed to monotherapy; and (4) supplement type. Symptoms of depression were not significantly reduced in 3 studies using pure DHA (standardized mean difference 0.001, 95% CI -0.330 to 0.332, z = 0.004, p = 0.997) or in 4 studies using supplements containing greater than 50% DHA (standardized mean difference = 0.141, 95% CI = -0.195 to 0.477, z = 0.821, p = 0.417). In contrast, symptoms of depression were significantly reduced in 13 studies using supplements containing greater than 50% EPA (standardized mean difference = -0.446, 95% CI = -0.753 to -0.138, z = -2.843, p = 0.005) and in 8 studies using pure ethyl-EPA (standardized mean difference = -0.396, 95% CI = -0.650 to -0.141, z = -3.051, p = 0.002). However, further meta-regression studies showed significant inverse associations between efficacy and study methodological quality, study sample size, and duration, thus limiting the confidence of these findings.

CONCLUSIONS

The current meta-analysis provides evidence that EPA may be more efficacious than DHA in treating depression. However, owing to the identified limitations of the included studies, larger, well-designed, randomized controlled trials of sufficient duration are needed to confirm these findings.

Endogenous n-3 fatty acids protect ovariectomy induced bone loss by attenuating osteoclastogenesis

Beneficial effects of n-3 fatty acids (FA) on bone mineral density (BMD) have been reported in mice, rats and human beings, but the precise mechanisms involved have not been described. This study used the Fat-1 mouse, a transgenic model that synthesizes n-3 FA from n-6 FA to directly determine if outcome of bone health were correlated with n-3 FA. Ovariectomized (Ovx) and sham operated wild-type (WT) and Fat-1 mice were fed an AIN-93M diet containing 10% corn oil for 24 weeks. BMD was analysed by dual energy x-ray absorptiometry. Fat-1 Ovx mice exhibited significantly lower level of osteotropic factors like receptor activator of NF-kappaB ligand and tartrate-resistant acid phosphatase (TRAP)5b in serum and higher BMD in distal femoral metaphysis, proximal tibial metaphysis, femoral diaphysis and lumbar vertebra as compared to WT Ovx mice. LPS-stimulated bone marrow (BM) cells from Fat-1 Ovx mice produced significantly lower level of pro-inflammatory cytokines like tumour necrosis factor-alpha, interleukin (IL)-1-beta, IL-6 and higher level of anti-inflammatory cytokines like IL-10, IFN-gamma and higher level of nitric oxide as compared to BM cells from WT Ovx mice. LPS-stimulated COX-II activity as well as NF-kappaB activation in BM cells from Fat-1 Ovx mice was significantly less as compared to BM cells from WT Ovx mice. Furthermore, Fat-1 BM cells generated significantly less number of TRAP osteoclast-like cells as compared to WT BM cells. In conclusion, we offer further insight into the mechanisms involved in preventing the BMD loss in Ovx mice by n-3 FA using a Fat-1 transgenic mouse model.

Endogenous n-3 fatty acids protect ovariectomy induced bone loss by attenuating osteoclastogenesis

Beneficial effects of n-3 fatty acids (FA) on bone mineral density (BMD) have been reported in mice, rats and human beings, but the precise mechanisms involved have not been described. This study used the Fat-1 mouse, a transgenic model that synthesizes n-3 FA from n-6 FA to directly determine if outcome of bone health were correlated with n-3 FA. Ovariectomized (Ovx) and sham operated wild-type (WT) and Fat-1 mice were fed an AIN-93M diet containing 10% corn oil for 24 weeks. BMD was analysed by dual energy x-ray absorptiometry. Fat-1 Ovx mice exhibited significantly lower level of osteotropic factors like receptor activator of NF-kappaB ligand and tartrate-resistant acid phosphatase (TRAP)5b in serum and higher BMD in distal femoral metaphysis, proximal tibial metaphysis, femoral diaphysis and lumbar vertebra as compared to WT Ovx mice. LPS-stimulated bone marrow (BM) cells from Fat-1 Ovx mice produced significantly lower level of pro-inflammatory cytokines like tumour necrosis factor-alpha, interleukin (IL)-1-beta, IL-6 and higher level of anti-inflammatory cytokines like IL-10, IFN-gamma and higher level of nitric oxide as compared to BM cells from WT Ovx mice. LPS-stimulated COX-II activity as well as NF-kappaB activation in BM cells from Fat-1 Ovx mice was significantly less as compared to BM cells from WT Ovx mice. Furthermore, Fat-1 BM cells generated significantly less number of TRAP osteoclast-like cells as compared to WT BM cells. In conclusion, we offer further insight into the mechanisms involved in preventing the BMD loss in Ovx mice by n-3 FA using a Fat-1 transgenic mouse model.

Acne e dieta: verdade ou mito?

Nos últimos 50 anos, foram publicados inúmeros estudos com a finalidade de comprovar se a dieta está relacionada à etiologia da acne. Embora existam estudos antigos, que são bem difundidos entre os dermatologistas e negam a associação entre acne e dieta, seu delineamento científico é pobre. Recentemente, novos artigos demonstraram evidências contrárias às publicações anteriores. Sendo assim, os autores realizaram esta revisão bibliográfica com o intuito de averiguar se a dieta influencia direta ou indiretamente um ou mais dos quatro pilares etiopatogênicos fundamentais da acne: (1) hiperproliferação dos queratinócitos basais, (2) aumento da produção sebácea, (3) colonização pelo Propionibacterium acnes e (4) inflamação.

Omega-3 polyunsaturated fatty acids in the treatment of kidney disease

After more than 25 years of published investigation, including randomized controlled trials, the role of omega-3 polyunsaturated fatty acids in the treatment of kidney disease remains unclear. In vitro and in vivo experimental studies support the efficacy of omega-3 polyunsaturated fatty acids on inflammatory pathways involved with the progression of kidney disease. Clinical investigations have focused predominantly on immunoglobulin A (IgA) nephropathy. More recently, lupus nephritis, polycystic kidney disease, and other glomerular diseases have been investigated. Clinical trials have shown conflicting results for the efficacy of omega-3 polyunsaturated fatty acids in IgA nephropathy, which may relate to varying doses, proportions of eicosapentaenoic acid and docosahexaenoic acid, duration of therapy, and sample size of the study populations. Meta-analyses of clinical trials using omega-3 polyunsaturated fatty acids in IgA nephropathy have been limited by the quality of available studies. However, guidelines suggest that omega-3 polyunsaturated fatty acids should be considered in progressive IgA nephropathy. Omega-3 polyunsaturated fatty acids decrease blood pressure, a known accelerant of kidney disease progression. Well-designed, adequately powered, randomized, controlled clinical trials are required to further investigate the potential benefits of omega-3 polyunsaturated fatty acids on the progression of kidney disease and patient survival.

Preventive effects of eicosapentaenoic acid on coronary artery disease in patients with peripheral artery disease

BACKGROUND

The JELIS trial examined the preventive effects of eicosapentaenoic acid (EPA) on coronary artery disease (CAD) in hypercholesterolemia. Previous investigators have reported that patients with peripheral artery disease (PAD) have a poor prognosis due to the potential risk for CAD. We conducted a subanalysis to examine whether the incidence of CAD was high in patients with PAD and whether EPA prevented the occurrence of CAD.

METHODS AND RESULTS

Of 18,645 the Japan EPA lipid intervention study (JELIS) patients, 223 had PAD (control group; complicated (n=77), newly diagnosed (n=29), EPA group; complicated (n=96), newly diagnosed (n=21)). We analyzed the incidence of major coronary events (MCE) in the 2 groups. Cox proportional hazard ratio adjusted for baseline risk factor levels was used to test differences between the 2 groups. The incidence of MCE in the control group was significantly higher in patients complicated with PAD and in those newly diagnosed with PAD than in patients without PAD (complicated: hazard ratio 1.97, P=0.039; newly diagnosed: hazard ratio 2.88, P=0.030). As for patients with PAD, the EPA group had a significantly lower MCE hazard ratio than the control group (hazard ratio 0.44, 95% confidence interval 0.19-0.97, P=0.041).

CONCLUSIONS

Subanalysis of the JELIS trial demonstrated that in patients with PAD the incidence of CAD was higher than in controls, and that EPA markedly reduced the occurrence of CAD in those patients.

The 2008 ESPEN Sir David Cuthbertson Lecture: Fatty acids and inflammation--from the membrane to the nucleus and from the laboratory bench to the clinic

Many chronic conditions involve excessive inflammation that is damaging to host tissues. Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury and infection in some individuals and these can lead, progressively, to sepsis and septic shock. Hyperinflammation is characterised by the production of inflammatory cytokines, eicosanoids and other inflammatory mediators, while the immunosuppression is characterised by impairment of antigen presentation and of certain T cell responses. N-6 fatty acids may contribute to the hyperinflamed and immunosuppressed states. N-3 fatty acids from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid precursor) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, these fatty acids are potentially useful anti-inflammatory agents and may be of benefit in patients with chronic inflammatory diseases or at risk of hyperinflammation and sepsis. An emerging application of n-3 fatty acids is in surgical or critically ill patients where they may be added to parenteral or enteral formulas. Studies to date are suggestive of clinical benefits from these approaches, although more robust data are needed especially in critically ill patients.

Stress, food, and inflammation: psychoneuroimmunology and nutrition at the cutting edge

Inflammation is the common link among the leading causes of death. Mechanistic studies have shown how various dietary components can modulate key pathways to inflammation, including sympathetic activity, oxidative stress, transcription factor nuclear factor-kappaB activation, and proinflammatory cytokine production. Behavioral studies have demonstrated that stressful events and depression can also influence inflammation through these same processes. If the joint contributions of diet and behavior to inflammation were simply additive, they would be important. However, several far more intriguing interactive possibilities are discussed: stress influences food choices; stress can enhance maladaptive metabolic responses to unhealthy meals; and diet can affect mood as well as proinflammatory responses to stressors. Furthermore, because the vagus nerve innervates tissues involved in the digestion, absorption, and metabolism of nutrients, vagal activation can directly and profoundly influence metabolic responses to food, as well as inflammation; in turn, both depression and stress have well-documented negative effects on vagal activation, contributing to the lively interplay between the brain and the gut. As one example, omega-3 fatty acid intake can boost mood and vagal tone, dampen nuclear factor-kappaB activation and responses to endotoxin, and modulate the magnitude of inflammatory responses to stressors. A better understanding of how stressors, negative emotions, and unhealthy meals work together to enhance inflammation will benefit behavioral and nutritional research, as well as the broader biomedical community.

Fatty acids and immune function: relevance to inflammatory bowel diseases

Fatty acids may influence immune function through a variety of mechanisms; many of these are associated with changes in fatty acid composition of immune cell membranes. Eicosanoids produced from arachidonic acid have roles in inflammation and immunity. Increased membrane content of n-3 fatty acids results in a changed pattern of production of eicosanoids, resolvins, and cytokines. Changing the fatty acid composition of immune cells also affects T cell reactivity and antigen presentation. Little attention has been paid to the influence of fatty acids on the gut-associated lymphoid tissue. However, there has been considerable interest in fatty acids and gut inflammation.

Highly purified eicosapentaenoic acid ethyl ester prevents development of steatosis and hepatic fibrosis in rats

BACKGROUND AND AIMS

Pathogenesis of nonalcoholic steatohepatitis (NASH) is considered to be involved in fat accumulation, oxidative stress, inflammation, and fibrosis in liver, but no drug therapy has been established as yet. Eicosapentaenoic acid (EPA) is an agent used clinically to treat hypertriglyceridemia, and has been reported to suppress reactive oxygen species and inflammation. Here, we aimed to assess the effect of EPA on progression of hepatic fibrosis in an animal model of NASH.

METHODS

Wistar rats were fed a methionine- and choline-deficient (MCD) diet and given EPA ethyl ester (EPA-E) (1,000 mg/kg/day) or vehicle by gavage for 8 or 20 weeks.

RESULTS

The MCD diet caused development of hepatic fibrosis and nodule formation at 20 weeks. EPA-E treatment significantly suppressed MCD-induced increase in fibrosis and hepatic hydroxyproline, and inhibited nodule formation. EPA-E treatment also decreased hepatic transforming growth factor (TGF)-beta1, and messenger RNA (mRNA) levels of connective tissue growth factor. EPA-E suppressed MCD-induced elevation of serum levels of ferritin, 8-isoprostane, soluble tumor necrosis factor receptor 1 (sTNFR1), and sTNFR2 at 20 weeks, and hepatic triglyceride accumulation at 8 weeks.

CONCLUSIONS

EPA-E prevents progression of hepatic fibrosis in an MCD-induced NASH model with reduction of oxidative stress, inflammation, and initial hepatic steatosis. Thus, EPA-E treatment may be a potential therapy to treat NASH.

N-3 polyunsaturated fatty acids regulate lipid metabolism through several inflammation mediators: mechanisms and implications for obesity prevention

Obesity is a growing problem that threatens the health and welfare of a large proportion of the human population. The n-3 polyunsaturated fatty acids (PUFA) are dietary factors that have potential to facilitate reduction in body fat deposition and improve obesity-induced metabolic syndromes. The n-3 PUFA up-regulate several inflammation molecules including serum amyloid A (SAA), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in hepatocytes and adipocytes. Actions of these inflammation mediators resemble those of n-3 PUFA in the modulation of many lipid metabolism-related genes. For instance, they both suppress expressions of perilipin, sterol regulatory element binding protein-1 (SREBP-1) and lipoprotein lipase (LPL) to induce lipolysis and reduce lipogenesis. This review will connect these direct or indirect regulating pathways between n-3 PUFA, inflammation mediators, lipid metabolism-related genes and body fat reduction. A thorough knowledge of these regulatory mechanisms will lead us to better utilization of n-3 PUFA to reduce lipid deposition in the liver and other tissues, therefore presenting an opportunity for developing new strategies to treat obesity.

Fish nutrients decrease expression levels of tumor necrosis factor-α in cultured human macrophages

Numerous studies have demonstrated the beneficial effects of fish consumption on inflammatory markers. Until now, these beneficial effects of fish consumption have been mostly linked to the omega-3 fatty acids (FA). The objective of the present study was to examine, in vitro, whether expression levels of genes involved in the inflammatory response differ in human macrophages incubated with casein hydrolysates (CH) or fish protein hydrolysates (FPH) in the presence or absence of omega-3 FA compared with omega-3 FA alone. Peripheral blood monocytes differentiated into macrophages from 10 men were incubated in the presence of omega-3 FA (10 μM eicosapentaenoic acid and 5 μM docosahexaenoic acid) or CH or FPH (10, 100, 1,000 μg) with or without omega-3 FA for 48 h. Results demonstrate that expression levels of tumor necrosis factorα ( TNFα) had a tendency to be lower after the addition of FPH alone or CH with omega-3 FA compared with omega-3 FA treatment. Furthermore, the combination of FPH and omega-3 FA synergistically decreased expression levels of TNFα compared to treatment with omega-3 FA or FPH alone. No difference on gene expression levels of interleukin-6 was observed between treatments. In conclusion, these preliminary results suggest that the anti-inflammatory effects of fish consumption can be explained by a synergistic effect of the omega-3 FA with the protein components of fish on TNFα expression and therefore contribute to the beneficial effects of fish consumption. Hence, follow-up studies should be performed to confirm the effects of a diet rich in FPH and omega-3 FA on serum proinflammatory cytokine concentrations.

Amyloid-Beta Peptide, Oxidative Stress and Inflammation in Alzheimer's Disease: Potential Neuroprotective Effects of Omega-3 Polyunsaturated Fatty Acids

Alzheimer's disease is the most common form of dementia in the elderly and is a progressive neurodegenerative disorder characterised by a decline in cognitive function and also profound alterations in mood and behaviour. The pathology of the disease is characterised by the presence of extracellular amyloid peptide deposits and intracellular neurofibrillary tangles in the brain. Although many hypotheses have been put forward for the aetiology of the disease, increased inflammation and oxidative stress appear key to be features contributing to the pathology. The omega-3 polyunsaturated fats, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have well-characterised effects on inflammation and may have neuroprotective effects in a number of neurodegenerative conditions including Alzheimer's disease. The aims of this paper are to review the neuroprotective effects of EPA and DHA in Alzheimer's disease, with special emphasis on their role in modulating oxidative stress and inflammation and also examine their potential as therapeutic agents.

n-3 and n-6 Polyunsaturated fatty acids suppress sterol regulatory element binding protein activity and increase flow of non-esterified cholesterol in HepG2 cells

The plasma lipid-lowering effect of PUFA, one of their main beneficial effects, is considered to be related to the regulation of lipid biosynthesis through transcription factors including sterol regulatory element binding proteins (SREBP). In the present study, we compared the effect of different PUFA on SREBP activity in HepG2 cells, using a sterol regulatory element–luciferase reporter construct as a probe. Supplementation with different fatty acids reduced SREBP activity in the order 20 : 5n-3 = 18 : 2n-6 = 20 : 4n-6≫18 : 3n-3 = 22 : 6n-3 = 22 : 5n-6≫18 : 1n-9. The suppression of SREBP activity greatly depended on the degree of incorporation of the supplemented PUFA into cellular lipids, and correlated positively with the unsaturation index (r 0·831; P < 0·01) of total cell lipids. Supplemented PUFA were also metabolised to longer and more unsaturated species. These processing activities were higher for n-3 than n-6 PUFA (P < 0·01). We studied the effect of PUFA on the intracellular distribution of non-esterified cholesterol, using filipin staining and fluorescence microscopy with or without the cholesterol traffic blocker U18666A. The data show that the incorporation of PUFA increases non-esterified cholesterol flow from the plasma membrane to intracellular membranes. We conclude that suppression of SREBP activity by PUFA depends on the degree of incorporation into cellular lipids, and is associated with increased flow of non-esterified cholesterol between the plasma membrane and intracellular membranes.

Fatty acids as metabolic mediators in innate immunity

BACKGROUND

Increasing data support the hypothesis of a local and systemic crosstalk between adipocytes and monocytes mediated by fatty acids. The aim of this study was to characterize the immunomodulatory effects of a large panel of fatty acids on cytokines and chemokines in monocytic THP-1 cells and primary human monocytes. We tested whether anti-inflammatory fatty acids are able to inhibit the binding of lipopolysaccharide (LPS) to its receptor, toll-like receptor/MD-2 (TLR4/MD-2).

MATERIALS AND METHODS

Resistin, monocyte chemoattractant protein-1 (MCP-1) and tumour necrosis factor (TNF) were measured by enzyme-linked immunosorbent assay. Proteins were analysed by Western blot. A designed Flag-tagged TLR4/MD-2 fusion protein (LPS trap) was used to investigate the effect of fatty acids on binding of LPS to its receptor. In 30 patients with type 2 diabetes mellitus (T2D), the correlation of serum triglyceride levels with LPS-induced monocyte activation was analysed.

RESULTS

Eleven fatty acids investigated exerted differential effects on the monocytic release of cytokines and chemokines. Eicosapentaenoic acid had potent anti-inflammatory effects on human primary monocytes and THP-1 cells; 100 and 200 microM eicosapentaenoic acid dose-dependently inhibited LPS binding to the LPS trap. LPS-induced release of monocytic MCP-1 and TNF was significantly and positively correlated with serum triglyceride levels in 30 patients with T2D.

CONCLUSIONS

Monocytic activation is differentially regulated by fatty acids and depends on triglyceride levels in T2D. The main finding of the present study shows that eicosapentaenoic acid inhibits the specific binding of LPS to TLR4/MD-2. Eicosapentaenoic acid represents a new anti-inflammatory LPS-antagonist.

Polyunsaturated fatty acids and inflammatory processes: New twists in an old tale

The n-6 fatty acid arachidonic acid (AA; 20:4n-6) gives rise to eicosanoid mediators that have established roles in inflammation and AA metabolism is a long recognised target for commonly used anti-inflammatory therapies. It has generally been assumed that all AA-derived eicosanoids are pro-inflammatory. However this is an over-simplification since some actions of eicosanoids are anti-inflammatory (e.g. prostaglandin (PG) E(2) inhibits production of some inflammatory cytokines) and it has been discovered quite recently that PGE(2) inhibits production of inflammatory leukotrienes and induces production of inflammation resolving lipoxin A(4). The n-3 fatty acids from oily fish and "fish oils", eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), are incorporated into inflammatory cell phospholipids in a time- and dose-dependent manner. They are incorporated partly at the expense of AA, but also of other n-6 fatty acids. EPA and DHA inhibit AA metabolism. Thus production of AA-derived eicosanoids is decreased by these n-3 fatty acids; this occurs in a dose-dependent manner. EPA gives rise to an alternative family of eicosanoids (e.g. PGE(3)), which frequently, but not always, have lower potency than those produced from AA. Recently a new family of EPA- and DHA-derived lipid mediators called resolvins (E- and D-series) has been described. These have potent anti-inflammatory and inflammation resolving properties in model systems. It seems likely that these mediators will explain many of the antiinflammatory actions of n-3 fatty acids that have been described. In addition to modifying the profile of lipid-derived mediators, fatty acids can also influence peptide mediator (i.e. cytokine) production. To a certain extent this action may be due to the altered profile of regulatory eicosanoids, but it seems likely that eicosanoid-independent actions are a more important mechanism. Indeed effects on transcription factors that regulate inflammatory gene expression (e.g. nuclear factor kappaB) seem to be important.

Eicosapentaenoic acid attenuates arthritis-induced muscle wasting acting on atrogin-1 and on myogenic regulatory factors

Eicosapentaenoic acid (EPA) is an omega-3 polyunsaturated fatty acid that has anti-inflammatory and anticachectic actions. The aim of this work was to elucidate whether EPA administration is able to prevent an arthritis-induced decrease in body weight and muscle wasting in rats. Arthritis was induced by intradermal injection of Freund's adjuvant; 3 days later, nine rats received 1 g/kg EPA or coconut oil daily. All rats were killed 15 days after adjuvant injection. EPA administration decreased the external signs of arthritis and paw volume as well as liver TNF-alpha mRNA. EPA did not modify arthritis-induced decrease in food intake or body weight gain. However, EPA treatment prevented arthritis-induced increase in muscle TNF-alpha and atrogin-1, whereas it attenuated the decrease in gastrocnemius weight and the increase in MuRF1 mRNA. Arthritis not only decreased myogenic regulatory factors but also increased PCNA, MyoD, and myogenin mRNA in the gastrocnemius. Western blot analysis showed that changes in protein content followed the pattern seen with mRNA. In the control rats, EPA administration increased PCNA and MyoD mRNA and protein. In arthritic rats, EPA did not modify the stimulatory effect of arthritis on these myogenic regulatory factors. The results suggest that in experimental arthritis, in addition to its anti-inflammatory effect, EPA treatment attenuates muscle wasting by decreasing atrogin-1 and MuRF1 gene expression and increasing the transcription factors that regulate myogenesis.