Session 3: Joint Nutrition Society and Irish Nutrition and Dietetic Institute Symposium on ‘Nutrition and autoimmune disease’ PUFA, inflammatory processes and rheumatoid arthritis: Symposium on ‘The challenge of translating nutrition research into public health nutrition’

Stearidonic acid improves eicosapentaenoic acid status: studies in humans and cultured hepatocytes

Background

Ahiflower oil from the seeds of Buglossoides arvensis is rich in α-linolenic acid (ALA) and stearidonic acid (SDA). ALA and SDA are potential precursor fatty acids for the endogenous synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are n3-long chain polyunsaturated fatty acids (n3-LC-PUFAS), in humans. Since taurine, an amino sulfonic acid, is often associated with tissues rich in n3-LC-PUFAS (e.g., in fatty fish, human retina), taurine may play a role in EPA- and DHA-metabolism.

Objective

To examine the capacity of the plant-derived precursor fatty acids (ALA and SDA) and of the potential fatty acid metabolism modulator taurine to increase n3-LC-PUFAS and their respective oxylipins in human plasma and cultivated hepatocytes (HepG2 cells).

Methods

In a monocentric, randomized crossover study 29 healthy male volunteers received three sequential interventions, namely ahiflower oil (9 g/day), taurine (1.5 g/day) and ahiflower oil (9 g/day) + taurine (1.5 g/day) for 20 days. In addition, cultivated HepG2 cells were treated with isolated fatty acids ALA, SDA, EPA, DHA as well as taurine alone or together with SDA.

Results

Oral ahiflower oil intake significantly improved plasma EPA levels (0.2 vs. 0.6% of total fatty acid methyl esters (FAMES)) in humans, whereas DHA levels were unaffected by treatments. EPA-levels in SDA-treated HepG2 cells were 65% higher (5.1 vs. 3.0% of total FAMES) than those in ALA-treated cells. Taurine did not affect fatty acid profiles in human plasma in vivo or in HepG2 cells in vitro. SDA-rich ahiflower oil and isolated SDA led to an increase in EPA-derived oxylipins in humans and in HepG2 cells, respectively.

Conclusion

The consumption of ahiflower oil improves the circulating levels of EPA and EPA-derived oxylipins in humans. In cultivated hepatocytes, EPA and EPA-derived oxylipins are more effectively increased by SDA than ALA.

Essential fatty acids in farmed tambaqui (Colossoma macropomum) from the Brazilian Amazon Area

The goal of this study was to determine the essential fatty acids of the total lipids of the fillet, head and orbital cavity tissue from farmed tambaqui (Colossoma macropomum) fish from a Brazilian Amazon area. The tambaqui were acquired from different fish farms in the Roraima state, located at Western Brazilian Amazon. The meat, the head and the fatty tissue from orbital cavity were dissected for lipid extraction and analysis of fatty acids by gas chromatography. The fatty acids were quantified in mg g-1 of total lipids using C23:0 as an internal standard. The nutritional quality of the lipids was determined by using the atherogenicity and thrombogenicity indices, and also by the ratio between hypocholesterolemic / hypercholesterolemic fatty acids. The orbital cavity tissue had the higher concentration amount of linoleic and α-linolenic acid, whereas the fillet had higher docosahexaenoic acid (DHA). The eicosapentaenoic acid (EPA) concentration was: 1.28, 0.97, 1.71 mg g-1 of total lipids, in the filet, in head, and in orbital cavity tissue, respectively. All essential fatty acids were detected in the three parts analyzed. The nutritional quality of the total lipids from the head and from the orbital cavity tissue was similar to the fillet.

Quality Evaluation Indices for Soybean Oil in Relation to Cultivar, Application of N Fertiliser and Seed Inoculation with Bradyrhizobium japonicum

Soybean ranks second in production and consumption of vegetable oils worldwide and these are expected to continue to increase. The suitability of soybean oil for specific uses is determined by the fatty acid composition from which a number of indices and indicators can be calculated. The aim of this study was to evaluate the indices of nutritional and health-promoting fat in seeds of soybean cultivars grown in 2016–2019 under the influence of varying doses of N and inoculation with Bradyrhizobium japonicum. Omega 3 and Omega 6, unsaturated fatty acids (UFA), saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA), index of desirable fatty acids (DFA), sum of hypercholesterolemic fatty acids (OFA), index of atherogenicity (AI), index of thrombogenicity (TI), oleic desaturation ratio (ODR), linoleic desaturation ratio (LDR), calculated oxidizability value (COX) and the hypocholesterolemic/hypercholesterolemic ratio (HH), saturation fat index (S/P) and ALA/LA, OL/(LA+ALA) ratios and the consumer index (CI) were included. Fat quality indices for soybean seeds were strongly determined by weather conditions. Seeds of the cv. Aldana contained higher amounts of Omega 6 and featured more favourable MUFA/PUFA and OL/(LA+ALA) ratios, while the seeds of the cv. Annushka had more favourable CI and higher ODR, COX and S/P indices. No important differences were observed regarding the effect of nitrogen dose and seed inoculation on the formation of the DFA, OFA, HH, AI, TI and CI indices. The value of the S/P index suggests that higher nitrogen rates (60 kg∙ha−1) and the lack of inoculation treatment produce seeds with a more favourable dietary fatty acid balance.

Dietary Fish Oil Increases the Number of CD11b+CD27− NK Cells at the Inflammatory Site and Enhances Key Hallmarks of Resolution of Murine Antigen-Induced Peritonitis

Purpose

To determine the effects of dietary omega-3 polyunsaturated fatty acids (PUFAs) on recruitment of natural killer (NK) cells and resolution responses in antigen-induced peritonitis in mice.

Methods

Mice were fed fish oil-enriched or control diets, immunized twice and challenged intraperitoneally with methylated bovine serum albumin. Prior to and at different time-points following inflammation induction, expression of surface molecules on peritoneal cells was determined by flow cytometry, concentration of soluble mediators in peritoneal fluid by ELISA or Luminex, and of lipid mediators by LC-MS/MS, and number of apoptotic cells in mesenteric lymph nodes by TUNEL staining.

Results

Mice fed the fish oil diet had higher number of CD11b⁺CD27⁻ NK cells as well as a higher proportion of CD107a⁺ NK cells in their peritoneum 6 h after inflammation induction than mice fed the control diet. They also had higher numbers of CCR5⁺ NK cells and higher concentrations of CCL5 and CXCL12. Additionally, a higher fraction of apoptotic neutrophils but lower fraction of CD47⁺ neutrophils were present in the peritoneum of mice fed the fish oil diet 6 h after inflammation induction and the fish oil fed mice had a shorter resolution interval. They also had lower concentrations of pro-inflammatory mediators but higher concentrations of the anti-inflammatory/pro-resolution mediators TGF-β, IGF-1, and soluble TNF RII, as well as higher ratios of hydroxyeicosapentaenoic acid (HEPE) to hydroxyeicosatetraenoic acid (HETE) than mice fed the control diet.

Conclusion

The results demonstrate that dietary fish oil increases the number of mature NK cells at the inflamed site in antigen-induced peritonitis and enhances several key hallmarks of resolution of inflammation, casting light on the potential mechanisms involved.

New Insights on the Effects of Dietary Omega-3 Fatty Acids on Impaired Skin Healing in Diabetes and Chronic Venous Leg Ulcers

Long-chain Omega-3 polyunsaturated fatty acids (Omega-3 PUFAs) are widely recognized as powerful negative regulators of acute inflammation. However, the precise role exerted by these dietary compounds during the healing process is still largely unknown, and there is increasing interest in understanding their specific effects on the implicated cells/molecular factors. Particular attention is being focused also on their potential clinical application in chronic pathologies characterized by delayed and impaired healing, such as diabetes and vascular diseases in lower limbs. On these bases, we firstly summarized the current knowledge on wound healing (WH) in skin, both in normal conditions and in the setting of these two pathologies, with particular attention to the cellular and molecular mechanisms involved. Then, we critically reviewed the outcomes of recent research papers investigating the activity exerted by Omega-3 PUFAs and their bioactive metabolites in the regulation of WH in patients with diabetes or venous insufficiency and showing chronic recalcitrant ulcers. We especially focused on recent studies investigating the mechanisms through which these compounds may act. Considerations on the optimal dietary doses are also reported, and, finally, possible future perspectives in this area are suggested.

Elevated dietary ω-6 polyunsaturated fatty acids induce reversible peripheral nerve dysfunction that exacerbates comorbid pain conditions

Chronic pain is the leading cause of disability worldwide¹ and is commonly associated with comorbid disorders². However, the role of diet in chronic pain is poorly understood. Of particular interest is the Western-style diet, enriched with ω-6 polyunsaturated fatty acids (PUFAs) that accumulate in membrane phospholipids and oxidise into pronociceptive oxylipins^3,4. Here we report that mice administered an ω-6 PUFA-enriched diet develop persistent nociceptive hypersensitivities, spontaneously active and hyper-responsive glabrous afferent fibres and histologic markers of peripheral nerve damage reminiscent of a peripheral neuropathy. Linoleic and arachidonic acids accumulate in lumbar dorsal root ganglia, with increased liberation via elevated phospholipase (PLA)2 activity. Pharmacological and molecular inhibition of PLA2G7 or diet reversal with high levels of ω-3 PUFAs attenuate nociceptive behaviours, neurophysiologic abnormalities and afferent histopathology induced by high ω-6 intake. Additionally, ω-6 PUFA accumulation exacerbates allodynia observed in preclinical inflammatory and neuropathic pain models and is strongly correlated with multiple pain indices of clinical diabetic neuropathy. Collectively, these data reveal dietary enrichment with ω-6 PUFAs as a new aetiology of peripheral neuropathy and risk factor for chronic pain and implicate multiple therapeutic considerations for clinical pain management.

ω3 fatty acid metabolite, 12-hydroxyeicosapentaenoic acid, alleviates contact hypersensitivity by downregulation of CXCL1 and CXCL2 gene expression in keratinocytes via retinoid X receptor α

ω3 fatty acids show potent bioactivities via conversion into lipid mediators; therefore, metabolism of dietary lipids is a critical determinant in the properties of ω3 fatty acids in the control of allergic inflammatory diseases. However, metabolic progression of ω3 fatty acids in the skin and their roles in the regulation of skin inflammation remains to be clarified. In this study, we found that 12-hydroxyeicosapentaenoic acid (12-HEPE), which is a 12-lipoxygenase metabolite of eicosapentaenoic acid, was the prominent metabolite accumulated in the skin of mice fed ω3 fatty acid-rich linseed oil. Consistently, the gene expression levels of Alox12 and Alox12b, which encode proteins involved in the generation of 12-HEPE, were much higher in the skin than in the other tissues (eg, gut). We also found that the topical application of 12-HEPE inhibited the inflammation associated with contact hypersensitivity by inhibiting neutrophil infiltration into the skin. In human keratinocytes in vitro, 12-HEPE inhibited the expression of two genes encoding neutrophil chemoattractants, CXCL1 and CXCL2, via retinoid X receptor α. Together, the present results demonstrate that the metabolic progression of dietary ω3 fatty acids differs in different organs, and identify 12-HEPE as the dominant ω3 fatty acid metabolite in the skin.

Effect of Omega-3 on Recurrent Aphthous Stomatitis and Improvement Quality of Life

Objective

Recurrent aphthous stomatitis is one of the most common chronic inflammatory diseases in oral mucosa. Beneficial effects of omega-3 supplements on some inflammatory diseases have been proved. The aim of present study was to evaluate the effect of omega-3 supplements in recurrent aphthous stomatitis management and improve oral health-related quality of life.

Methods

In this double-blind clinical trial, 40 patients with minor recurrent aphthous stomatitis were randomly divided into case and control groups. The case group received 1000 mg capsules of omega-3, while the control group received placebo capsules for 6 months. The questionnaires of the ulcer severity score and the chronic oral mucosal disease questionnaire were filled by the patients in three steps, at the baseline session, after 3 months, and after 6 months. The data were analyzed by SPSS 22 software through ANOVA, Mann-Whitney, and chi-square tests. P < 0.05 was considered as significant.

Results

In the omega-3 group, the ulcer severity score showed significant reduction by three-month and six-month follow-ups (P < 0.0001, P < 0.0001, respectively). The mean score of the chronic oral mucosal disease questionnaire significantly improved by three-month and six-month follow-ups in the omega-3-receiving group.

Conclusion

Use of omega-3 oral supplements decreased the severity of aphthous ulcer and improved oral health-related quality of life.

Effect of omega-3 on painful symptoms of patients with osteoarthritis of the synovial joints: systematic review and meta-analysis

OBJECTIVES

The aim of this study was to determine the effect of omega-3 on the painful symptomatology of osteoarthritis (OA) in synovial joints.

STUDY DESIGN

An electronic/manual search was conducted (2004-2019). Using pain as a primary outcome and stiffness/function and swelling as secondary outcomes, based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria, Consolidated Standards of Reporting Trials (CONSORT) reporting quality, and Cochrane/RoB-2 risk of bias assessment. Data were processed using RevMan v5.2 (Cochrane Collaboration).

RESULTS

Six randomized controlled trials were selected. The study population included 454 patients with OA. In 4 studies the pain in the intervention group presented significant pain reduction compared with the control group (mean difference = 22.89; 95% confidence interval, 3.37-42.42). Studies did not stablish the effective anti-inflammatory dose. The number of studies on stiffness/function and inflammation was low (n = 2). The evidence and degree of recommendation was 2B. The randomized controlled trials presented high clinical and methodological variability.

CONCLUSION

Omega-3 can significantly reduce painful symptoms in patients suffering from OA in synovial joints. However, the limited number of studies, range of doses, intervention periods, baseline characteristics of patients, and asymmetry in reporting bias, combined with the heterogeneity in the combined effect of the studies, offer low-quality evidence on which clinical guidance cannot be based.

n-3 PUFA and inflammation: from membrane to nucleus and from bench to bedside

Inflammation is a normal part of the immune response and should be self-limiting. Excessive or unresolved inflammation is linked to tissue damage, pathology and ill health. Prostaglandins and leukotrienes produced from the n-6 fatty acid arachidonic acid are involved in inflammation. Fatty acids may also influence inflammatory processes through mechanisms not necessarily involving lipid mediators. The n-3 fatty acids EPA and DHA possess a range of anti-inflammatory actions. Increased content of EPA and DHA in the membranes of cells involved in inflammation has effects on the physical nature of the membranes and on the formation of signalling platforms called lipid rafts. EPA and DHA interfere with arachidonic acid metabolism which yields prostaglandins and leukotrienes involved in inflammation. EPA gives rise to weak (e.g. less inflammatory) analogues and both EPA and DHA are substrates for the synthesis of specialised pro-resolving mediators. Through their effects on early signalling events in membranes and on the profile of lipid mediators produced, EPA and DHA alter both intracellular and intercellular signals. Within cells, this leads to altered patterns of gene expression and of protein production. The net result is decreased production of inflammatory cytokines, chemokines, adhesion molecules, proteases and enzymes. The anti-inflammatory and inflammation-resolving effects of EPA and DHA are relevant to both prevention and treatment of human diseases that have an inflammatory component. This has been widely studied in rheumatoid arthritis where there is good evidence that high doses of EPA + DHA reduce pain and other symptoms.

l-Serine and EPA Relieve Chronic Low-Back and Knee Pain in Adults: A Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Multisite pain, including low-back and knee pain, is a major health issue that greatly decreases quality of life.

OBJECTIVES

This study analyzed the effects of l-serine, which provides necessary components for nerve function, and EPA, which exerts anti-inflammatory properties, on pain scores of adults with pain in at least the low back and knee for ≥3 mo.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group study. The Japan Low Back Pain Evaluation Questionnaire (JLEQ) and Japanese Knee Osteoarthritis Measure (JKOM) were applied as primary outcomes. The Brief Pain Inventory (BPI) and safety evaluation were secondary outcomes. We enrolled 120 participants aged ≥20 y (36 men and 84 women: mean ± SD age = 40.8 ± 10.9 y). The participants were randomly allocated to either the active group (daily ingestion of 594 mg l-serine and 149 mg EPA) or placebo group. The study period consisted of 8-wk dosing and 4-wk posttreatment observation. ANCOVA between groups for each time point was conducted using the baseline scores as covariates.

RESULTS

The JLEQ scores (active compared with placebo: 14.2 ± 11.2 compared with 19.0 ± 10.2) at week 8 were lower in the active group (P < 0.001). The JKOM scores at week 4 (11.7 ± 9.0 compared with 13.9 ± 7.9), week 8 (10.4 ± 7.9 compared with 13.1 ± 7.1), and week 12 (10.3 ± 7.4 compared with 13.8 ± 7.5) were lower in the active group (P ≤ 0.04). Additionally, the active group had 11-27% better scores compared with the placebo group for BPI1 (worst pain), BPI3 (average pain), and BPI5D (pain during moving) at week 4 (P ≤ 0.028) and week 8 (P ≤ 0.019), respectively, and BPI5D was 23% better in the active group at week 12 (P = 0.007). No adverse events were observed.

CONCLUSIONS

l-Serine and EPA were effective for pain relief in adults with low-back and knee pain after multiplicity adjustment.This trial was registered at the University Hospital Medical Information Network Clinical Trials Registry as UMIN000035056.

5-oxoETE triggers nociception in constipation-predominant irritable bowel syndrome through MAS-related G protein-coupled receptor D

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that is characterized by chronic abdominal pain concurrent with altered bowel habit. Polyunsaturated fatty acid (PUFA) metabolites are increased in abundance in IBS and are implicated in the alteration of sensation to mechanical stimuli, which is defined as visceral hypersensitivity. We sought to quantify PUFA metabolites in patients with IBS and evaluate their role in pain. Quantification of PUFA metabolites by mass spectrometry in colonic biopsies showed an increased abundance of 5-oxoeicosatetraenoic acid (5-oxoETE) only in biopsies taken from patients with IBS with predominant constipation (IBS-C). Local administration of 5-oxoETE to mice induced somatic and visceral hypersensitivity to mechanical stimuli without causing tissue inflammation. We found that 5-oxoETE directly acted on both human and mouse sensory neurons as shown by lumbar splanchnic nerve recordings and Ca2+ imaging of dorsal root ganglion (DRG) neurons. We showed that 5-oxoETE selectively stimulated nonpeptidergic, isolectin B4 (IB4)-positive DRG neurons through a phospholipase C (PLC)- and pertussis toxin-dependent mechanism, suggesting that the effect was mediated by a G protein-coupled receptor (GPCR). The MAS-related GPCR D (Mrgprd) was found in mouse colonic DRG afferents and was identified as being implicated in the noxious effects of 5-oxoETE. Together, these data suggest that 5-oxoETE, a potential biomarker of IBS-C, induces somatic and visceral hyperalgesia without inflammation in an Mrgprd-dependent manner. Thus, 5-oxoETE may play a pivotal role in the abdominal pain associated with IBS-C.

Dietary Long-Chain n-3 Fatty Acid Intake and Arthritis Risk in the Women's Health Initiative

BACKGROUND

The prevalence of arthritis in the United States is substantial and on the rise. Long-chain n-3 polyunsaturated fatty acids, which have anti-inflammatory properties, have been shown to provide therapeutic benefit to arthritis patients; however, to date few have examined these associations with arthritis risk.

OBJECTIVE

The study objective was to examine the associations of long-chain n-3 polyunsaturated fatty acids intake with osteoarthritis (OA) and rheumatoid arthritis (RA) risk among postmenopausal women.

DESIGN

This was a prospective cohort study.

PARTICIPANTS

The sample for this analysis consisted of 80,551 postmenopausal women, aged 55 to 79 years and with no history of arthritis, recruited into the Women's Health Initiative Observational Study and Clinical Trials cohort between 1993 and 1998. Women completed a 120-item food frequency questionnaire at baseline.

MAIN OUTCOME MEASURES

After a median follow-up of 8 years, 22,306 incident OA and 3,348 RA cases were identified.

STATISTICAL ANALYSES PERFORMED

Adjusted Cox regression models were used to estimate hazard ratios and 95% CI for the associations between dietary LCn-3PUFA intake and OA and RA risk.

RESULTS

Individual and total long-chain n-3 polyunsaturated fatty acids (Quintile 5 vs Quintile 1: hazard ratio 1.04, 95% CI 0.99 to 1.09 for OA; hazard ratio 1.01, 95% CI 0.90 to 1.13 for RA) were not associated with OA and RA risk. Further, no associations were observed between n-6 polyunsaturated fatty acids intake and either arthritis outcome.

CONCLUSIONS

This study is the first to examine associations of long-chain n-3 polyunsaturated fatty acids intake with OA risk and the largest to examine associations with RA risk. Despite their therapeutic potential, the study provides no evidence of benefit of these nutrients in relation to arthritis risk.

The effects of dietary supplementation with rumen-protected amino acids on the expression of several genes involved in the immune system of dairy sheep

Amino acids might be a tool to transform animals from a pro- to an anti-inflammatory phenotype through the downregulation of several genes (TLR-4, NF-κB, TNFa, IL-1β, IL-2, IL-6, IL-8, CCL-5 and CXCL-16) whose expression increases during inflammation. To examine this possibility, each of sixty Chios dairy sheep was assigned to one of the following five dietary treatments: A: basal diet (control group); B: basal diet +6.0 g/head rumen-protected methionine (MetaSmart^™ ); C: basal diet +5.0 g/head rumen-protected lysine (LysiGEM^™ ); D: basal diet +6.0 g/head MetaSmart^™  + 5.0 g/head LysiGEM^™ ; and E: basal diet +12.0 g/head MetaSmart^™  + 5.0 g/head LysiGEM. The results showed a significant downregulation in the expression of the TLR-4 gene in both the macrophages and the neutrophils of ewes fed rumen-protected amino acids. Significantly lower mRNA transcript accumulation was also observed for the TNFa, IL-1β and CXCL-16 genes in the macrophages and for the IL-1β gene in the neutrophils of ewes supplemented with amino acids. The ewes that received dietary supplementation with rumen-protected lysine alone (C) had significantly lower CCL-5 transcript levels in their macrophages than the ewes fed the other supplemented diets. Diet D enhanced the mRNA expression of the IL-2 gene in ewe neutrophils. Negative correlations were found between: a. TLR-4, TNFa, IL-1β and CXCL-16 gene expression in macrophages and the milk fat and total solids content; b. CCL-5 gene expression in neutrophils and the milk yield and FCM_(6%) ; and c. CXCL-16 gene expression and the milk protein content. Moreover, positive correlations were found between the BHBA concentration and the expression of the TLR-4 and CXCL-16 genes in macrophages. In conclusion, the rumen-protected amino acids improved sheep metabolism (as indicated by reduced blood BHBA and urea concentrations), milk chemical composition and immune system function.

Resolvin E1 Inhibits Osteoclastogenesis and Bone Resorption by Suppressing IL-17-induced RANKL Expression in Osteoblasts and RANKL-induced Osteoclast Differentiation

Background

Resolvin E1 (RvE1) derived from the ω-3 polyunsaturated fatty acid eicosapentaenoic acid is known to be a potent pro-resolving lipid mediator that prevents chronic inflammation and osteoclastogenesis. We investigated the inhibitory effects of RvE1 on osteoclastogenesis and bone resorption to clarify its therapeutic potential for rheumatoid arthritis (RA).

Methods

Receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation was assessed with tartrate-resistant acid phosphatase staining. RANKL-induced bone resorption was assessed by the measurement of pit formation using calcium phosphate-labeled fluorescent polyanionic molecules in RAW264.7 cells as osteoclast precursors. The effects of RvE1 on the RANKL-induced mRNA expression of osteoclast-specific genes and transcriptional factors such as c-fos and nuclear factor of activated T cells c1 (NFATc1) in RAW264.7 cells were measured by quantitative real-time PCR. The distribution of NFATc1 induced by RANKL was evaluated by immunofluorescence staining in RAW264.7 cells. To analyze the mechanism of the inhibitory effect of RvE1 on osteoclastogenesis, we measured IL-17-induced RANKL mRNA expression in MC3T3-E1 osteoblast cells treated with RvE1 using quantitative real-time PCR and determined the level of prostaglandin E₂ (PGE₂) production by enzyme-linked immunosorbent assay.

Results

RvE1 significantly suppressed RANKL-induced osteoclast differentiation and bone resorption. RvE1 inhibited the RANKL-induced mRNA expression of osteoclast-specific genes along with the transcription factors NFATc1 and c-fos. Moreover, NFATc1 translocation from the cytoplasm to the nucleus of RAW264.7 cells was suppressed following RvE1 treatment. RvE1 also inhibited IL-17-induced RANKL mRNA expression and PGE₂ production in MC3T3-E1 cells.

Conclusion

RvE1 inhibited osteoclastogenesis and bone resorption by suppressing RANKL-induced NFATc1 and c-fos expression in osteoclasts and IL-17-induced RANKL expression through the autocrine action of PGE₂ in osteoblasts. Our data suggest RvE1 as a new therapeutic target of RA.

A systematic review on the role of eicosanoid pathways in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis is characterized by the production of eicosanoids, cytokines, adhesion molecules, infiltration of T and B lymphocytes in the synovium and oxygen reduction accompanied by the cartilage degradation. Eicosanoids are responsible for the progressive destruction of cartilage and bone, however neither steroids, nor the non steroidal anti-inflammatory drugs (NSAIDs), cannot slow down cartilage and bone destruction providing only symptomatic improvement. The current rheumatoid arthritis treatment options include mainly the use of disease-modifying anti-rheumatic drugs, the corticosteroids, the NSAIDs and biological agents.

METHODS

PubMed, Cochrane, and Embase electronic database were used as the main sources for extracting several articles, reviews, original papers in English for further review and analysis on the implication of arachidonic acid metabolites with rheumatoid arthritis and different strategies of targeting arachidonic acid metabolites, different enzymes or receptors for improving the treatment of rheumatoid arthritis patients.

RESULTS

We first focused on the role of individual prostaglandins and leukotrienes, in the inflammatory process of arthritis, concluding with an outline of the current clinical situation of rheumatoid arthritis and novel treatment strategies targeting the arachidonic acid pathway.

CONCLUSIONS

Extended research is necessary for the development of these novel compounds targeting the eicosanoid pathway, by increasing the levels of anti-inflammatory eicosanoids (PGD₂,15dPGJ₂), by inhibiting the production of pro-inflammatory eicosanoids (PGE₂, LTB₄, PGI₂) involved in rheumatoid arthritis or also by developing dual compounds displaying both the COX-2 inhibitor/TP antagonist activity within a single compound.

Omega 3: a novel treatment agent in oral submucous fibrosis: a pilot study

BACKGROUND

Oral submucous fibrosis (OSF) is a chronic debilitating disease and a premalignant condition of the oral cavity. It is well known for its impervious nature to medical therapy. Omega-3 polyunsaturated fatty acids have been reported to have anti-inflammatory properties. However, its role in OSF is still not known. This preliminary study assessed the efficacy of systemic omega 3 in this disease.

METHODS

A randomized single-blinded controlled trial was designed, and a total of 10 clinically confirmed adult patients with OSF were included in the study. Group A was given biweekly intralesional injections of dexamethasone 1.5 ml and hyaluronidase 1500 IU mixed with lignocaine for 6 weeks and a placebo for 3 months. Group B was also given similar intralesional injections but with 1 gm of omega 3 three times daily continuously for 3 months. Patients were followed every month for 3 months and then after 6 months.

RESULTS

Significant improvement was noted among all clinical parameters (interincisal distance, tongue protrusion, cheek flexibility, and visual analogue scale) in both the groups. Intergroup comparison showed significant reduction in burning sensation in group B; that is, P value was 0.005, while improvement in rest of the three clinical features was not statistically significant.

CONCLUSION

Omega 3 can be used as an adjunctive treatment option in patients with OSF to reduce subjective symptoms. More studies should be conducted with a larger sample size to study the effect of omega 3 in patients with OSF.

Effect of ω-3 polyunsaturated fatty acids on arthritic pain: A systematic review

OBJECTIVES

Pain is a significant problem in rheumatoid arthritis (RA) and is associated with prostaglandins derived from the ω-6 polyunsaturated fatty acid (PUFA) arachidonic acid. The ω-3 PUFAs eicosapentaenoic acid and docosahexaenoic acid have been shown to reduce inflammation, with some studies showing clinical improvements in RA. The aim of this systematic review was to investigate the effect of ω-3 PUFAs on arthritic pain.

METHOD

A systematic literature review of ω-3 PUFAs and pain associated with RA was performed up to December 2015. Randomized controlled trials (RCTs) investigating the effect of ω-3 PUFAs (>2 g/d) on patient or physician assessment of pain, or assessment by both patient and physician, were included. The Cochrane Collaboration's tool for assessing risk for bias was employed. Data for outcomes of interest were extracted and collated for interpretation.

RESULTS

Eighteen RCTs published between 1985 and 2013 involving 1143 patients were included. Dosage of ω-3 PUFAs used was 2.1 to 9.1 g/d, with study durations of 12 to 52 wk. Ten studies supported the hypothesis that there is a reduction in patient or physician assessment of pain associated with RA after intake of ω-3 PUFAs. Eight studies found no statistically significant effect of ω-3 PUFAs on arthritic pain.

CONCLUSIONS

ω-3 PUFAs may have a therapeutic role in decreasing pain associated with RA, with doses of 3 to 6 g/d appearing to have a greater effect. Due to the limitations identified in the RCTs included in this review, more research is needed to investigate ω-3 PUFAs in larger populations and over extended periods of time.

Omega 3 Fatty Acids: Novel Neurotherapeutic Targets for Cognitive Dysfunction in Mood Disorders and Schizophrenia?

An increasing body of evidences from preclinical as well as epidemiological and clinical studies suggest a potential beneficial role of dietary intake of omega-3 fatty acids for cognitive functioning. In this narrative review, we will summarize and discuss recent findings from epidemiological, interventional and experimental studies linking dietary consumption of omega-3 fatty acids to cognitive function in healthy adults. Furthermore, affective disorders and schizophrenia (SZ) are characterized by cognitive dysfunction encompassing several domains. Cognitive dysfunction is closely related to impaired functioning and quality of life across these conditions. Therefore, the current review focues on the potential influence of omega-3 fatty acids on cognition in SZ and affective disorders. In sum, current data predominantly from mechanistic models and animal studies suggest that adjunctive omega-3 fatty acid supplementation could lead to improved cognitive functioning in SZ and affective disorders. However, besides its translational promise, evidence for clinical benefits in humans has been mixed. Notwithstanding evidences indicate that adjunctive omega-3 fatty acids may have benefit for affective symptoms in both unipolar and bipolar depression, to date no randomized controlled trial had evaluated omega-3 as cognitive enhancer for mood disorders, while a single published controlled trial suggested no therapeutic benefit for cognitive improvement in SZ. Considering the pleiotropic mechanisms of action of omega-3 fatty acids, the design of well-designed controlled trials of omega-3 supplementation as a novel, domain-specific, target for cognitive impairment in SZ and affective disorders is warranted.

Neutrophils and arthritis: Role in disease and pharmacological perspectives

The inflammatory response in the joint can induce an intense accumulation of leukocytes in the tissue that frequently results in severe local damage and loss of function. Neutrophils are essential cells to combat many pathogens, but their arsenal can contribute or aggravate articular inflammation. Here we summarized some aspects of neutrophil biology, their role in inflammation and indicated how the modulation of neutrophil functions could be useful for the treatment of different forms of arthritis.

Have complementary therapies demonstrated effectiveness in rheumatoid arthritis?

In recent decades the treatment of rheumatoid arthritis (RA) has improved thanks to the use of highly effective drugs. However, patients usually require long term therapy, which is not free of side effects. Therefore RA patients often demand complementary medicine, they seek additional sources of relief and/or less side effects. In fact 30-60% of rheumatic patients use some form of complementary medicine. Therefore, from conventional medicine, if we want to optimally treat our patients facilitating communication with them we must know the most commonly used complementary medicines. The aim of this review is to assess, based on published scientific research, what complementary therapies commonly used by patients with RA are effective and safe.

Effect of omega-3 supplementation on inflammatory parameters in patients on chronic ambulatory peritoneal dialysis

Background:

End stage renal disease (ESRD) is a state of micro inflammation that attenuates patient's life span and quality of life. Inflammatory markers like interlukin 6 (IL-6) and C- reactive protein (CRP) can predict inflammatory state in ESRD patients. Dietary limitations are risk factors for omega-3 deficiency in these patients. Omega-3 supplementation is an attractive material that proposed in inflammation modulation. The aim of this study is evaluation of effect of omega-3 supplementation on IL-6 and CRP level in chronic ambulatory peritoneal dialysis (CAPD) patients.

Materials and Methods:

This randomized controlled double-blind clinical trial is performed in 40 CAPD patients in two academic hospitals in Isfahan, Iran. One group received 1000 mg omega-3 capsule (each capsule contains 180 mg Eicosapentanoic and 120 mg Dosahexanoic acid) three times a day orally for 8 weeks (n = 20) and the other matched group by placebo (n = 20). Serum level of IL-6 and quantitative CRP (Q-CRP) were measured in beginning and the end of the study. Finally all data were analyzed by SPSS version 18.

Results:

Mean age of patients was 53 years old in omega-3 group patients and 54 years old in placebo group. There were not any differences in CRP and IL-6 level in the beginning and the end of study between two groups (P: 0.81 and 0.10 for CRP and 0.26 and 0.23 for IL-6, respectively).

Conclusion:

Omega-3 supplementation did not effect on inflammatory markers (Q-CRP and IL-6) in CAPD patients after 8 weeks.

Implications for eicosapentaenoic acid- and docosahexaenoic acid-derived resolvins as therapeutics for arthritis

Omega-3 polyunsaturated fatty acids are essential for health and are known to possess anti-inflammatory properties, improving cardiovascular health as well as benefiting inflammatory diseases. Indeed, dietary supplementation with omega-3 polyunsaturated fatty acids has proved efficacious in reducing joint pain, morning stiffness and nonsteroidal anti-inflammatory drugs usage in rheumatoid arthritis patients. However, the mechanisms by which omega-3 polyunsaturated fatty acids exert their beneficial effects have not been fully explored. Seminal discoveries by Serhan and colleagues have unveiled a novel class of bioactive lipid mediators that are enzymatically biosynthesized in vivo from omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), termed resolvins, protectins and maresins. These bioactive pro-resolving lipid mediators provide further rationale for the beneficial effects of fish-oil enriched diets. These endogenous lipid mediators are spatiotemporally biosynthesized to actively regulate resolution by acting on specific G protein-coupled receptors (GPCRs) to initiate anti-inflammatory and pro-resolving signals that terminate inflammation. In this review, we will discuss the mechanism of actions of these molecules, including their analgesic and bone-sparing properties making them ideal therapeutic agonists for the treatment of inflammatory diseases such as rheumatoid arthritis.

Immune system, inflammation and nutrition in dairy cattle

Good health is essential for good performance and the welfare of dairy cows, and nutrition is an important component of good health. Health is influenced by the interaction between the innate adaptive components of the immune system and other factors, such as the local and systemic inflammatory response, which can sometimes be more harmful than useful. Therefore, for dairy cows, particularly those in the periparturient period, it is important to avoid, or reduce as much as possible, any kind of infectious, parasitic or metabolic disease and the associated inflammation. Such inflammation can impair cow performance by lowering milk yield, dry matter intake, fertility and energy efficiency, and can reduce liver function. Good nutrition is essential in maintaining a functional immune system, while also avoiding other causes of inflammation, such as tissue damage, and digestive and metabolic syndrome-related disorders. Provision of appropriate nutrients, such as antioxidants, omega-3 polyunsaturated fatty acids, conjugated linoleic acid and vitamin D can have anti-inflammatory effects. In the future, ways to reduce inflammation while maintaining a good immune defence must be developed and the susceptibility of the cow to diseases and inflammation evaluated. Ideally, we would be able to selectively breed for cows with a lower susceptibility to both diseases and inflammation.

Sugarcane bagasse lignin, and silica gel and magneto-silica as drug vehicles for development of innocuous methotrexate drug against rheumatoid arthritis disease in albino rats

The present study clarifies co-therapy action of deliveries from their textural changes point of view. Methotrexate (MTX) was immobilized onto biodegradable lignin, silica gel and iron/silica nanocomposite. Loaded-MTX was i.p. injected into albino rats at doses of 0.25 and 0.5mg/kg/week for 2.5months, after which spleen, liver, testes and knee joint tissues were collected for tests. IFN-γ and IL-17A mRNA gene expressions in spleen in all biological samples were determined by RT-PCR. Physicochemical features of drug carriers were monitored by XRD, BET-PSD, SEM and TEM. Drug inflammatory-site targeting was found to be closely related to the physico-features of deliverers. The interlayered lignin of micro- and meso-pore channels directed MTX toward concealed infected cells in liver and testes tissues, while meso-structured silica flacks satisfied by gathering MTX around knee joints. The magneto-silica nanocomposite targeted MTX toward spleen tissue, which is considered as a lively factory for the production of electron rich compounds.

Effect of eicosapentaenoic acid on cholesterol gallstone formation in C57BL/6J mice

The present study investigated the preventive effect of ω-3 fatty acids against cholesterol gallstone (CG) formation. CG formation was induced in C57BL/6J mice using a lithogenic diet (LD). The mice were divided into four treatment groups: i) LD, ii) LD plus eicosapentaenoic acid (EPA), iii) LD plus docosahexaenoic acid (DHA) and iv) LD plus EPA plus DHA. Subsequent to feeding the mice the LD for four weeks, EPA and/or DHA (70 mg/kg/day) were orally administered for eight weeks. The mice in the EPA treatment groups exhibited significantly less gallstone formation than those in the LD group. By contrast, DHA treatment only slightly suppressed gallstone formation. The expression of mucin 2, 5AC, 5B and 6 was significantly decreased in the gallbladders of mice in the EPA groups (70-90%) and the LD plus DHA group (30-50%), compared with that in the mice in the LD group. In addition, the mRNA expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase was significantly decreased in the livers of mice in the EPA treatment group compared with that in the livers of mice in the LD group. In conclusion, EPA was found to have a dominant anti-lithogenic effect in C57BL/6J mice.

Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance

Inflammation is a condition which contributes to a range of human diseases. It involves a multitude of cell types, chemical mediators, and interactions. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are omega-3 (n-3) fatty acids found in oily fish and fish oil supplements. These fatty acids are able to partly inhibit a number of aspects of inflammation including leukocyte chemotaxis, adhesion molecule expression and leukocyte-endothelial adhesive interactions, production of eicosanoids like prostaglandins and leukotrienes from the n-6 fatty acid arachidonic acid, production of inflammatory cytokines, and T-helper 1 lymphocyte reactivity. In addition, EPA gives rise to eicosanoids that often have lower biological potency than those produced from arachidonic acid and EPA and DHA give rise to anti-inflammatory and inflammation resolving mediators called resolvins, protectins and maresins. Mechanisms underlying the anti-inflammatory actions of marine n-3 fatty acids include altered cell membrane phospholipid fatty acid composition, disruption of lipid rafts, inhibition of activation of the pro-inflammatory transcription factor nuclear factor kappa B so reducing expression of inflammatory genes, activation of the anti-inflammatory transcription factor peroxisome proliferator activated receptor γ and binding to the G protein coupled receptor GPR120. These mechanisms are interlinked, although the full extent of this is not yet elucidated. Animal experiments demonstrate benefit from marine n-3 fatty acids in models of rheumatoid arthritis (RA), inflammatory bowel disease (IBD) and asthma. Clinical trials of fish oil in RA demonstrate benefit, but clinical trials of fish oil in IBD and asthma are inconsistent with no overall clear evidence of efficacy. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".

Resolution of inflammation: targeting GPCRs that interact with lipids and peptides

There is a growing appreciation of the important role of resolution mediators in the successful termination of the inflammatory response. Here, we discuss the potential importance of the lipid and peptide proresolving mediators, in particular the resolvins and chemerin-derived peptides, which mediate their effects through specific G protein-coupled receptors (GPCRs).

The effect of omega-3 fatty acid supplementation on oxidative stress in continuous ambulatory peritoneal dialysis patients

BACKGROUND

End stage renal disease (ESRD) is a condition that inflammation and oxidative stress plays an important role in damaging to tissues, especially, in the vascular system. The effect of omega-3 fatty acids is well-documented in some inflammatory diseases via eicosapentanoic acid and docosahexanoic acid components of fish oil. The aim of this study was to investigate the effects of dietary omega-3 fatty acid supplementation on levels of lipid peroxidation and oxidative sttress in ESRD patients.

MATERIALS AND METHODS

This randomized controlled double-blind clinical trial consisted of 90 patients on chronic ambulatory peritoneal dialysis (CAPD). One group was treated orally with 3000 mg omega-3, per day for 8 weeks (n = 45) and the other matched group by placebo (n = 45). Serum levels of lipids, iron, ferritin, Protrombin Time, Partial thromboplastin time, superoxide dismutase (SOD), and reduced glutathione (GH) were measured at the beginning and at 8 weeks.

RESULTS

Our results showed that SOD and reduced GH were not significantly changed in omega-3 group where lipid profile showed no significant changes too. Erythropoietin requirements also had no significant differences.

CONCLUSION

Incorporation of omega-3 fatty acids to CAPD patients had no beneficial effects on oxidative stress but should evaluate more.

[Antinociceptive effect of docosahexaenoic acid (DHA) through long fatty acid receptor G protein-coupled receptor 40 (GPR40)]

Fatty acids, one class of essential nutrients for humans, are an important source of energy and an essential component of cell membranes. They also function as signal transduction molecules in a variety of biological phenomena. The important functional role of fatty acids in both onset and suppression of pain has become increasingly apparent in recent years. Recently, we have also demonstrated that the release of an endogenous opioid peptide, β-endorphin, plays an important role in the induction of docosahexaenoic acid (DHA)-induced antinociception. It is well known that fatty acids affect intracellular and intercellular signaling as well as the membrane fluidity of neurons. In addition to intracellular actions, unbound free fatty acids (FFAs) can also carry out extracellular signaling by stimulating the G protein-coupled receptor (GPCR). Among these receptors, G protein-coupled receptor 40 (GPR40) has been reported to be activated by long-chain fatty acids such as DHA, eicosapentaenoic acid (EPA) and arachidonic acid. In the peripheral area, GPR40 is preferentially expressed in pancreatic β-cells and is known to relate to the secretion of hormone and peptides. On the other hand, even though this receptor is widely distributed in the central nervous system, reports studying the role and functions of GPR40 in the brain have not been found. In this review, we summarize the findings of our recent study about the long-chain fatty acid receptor GPR40 as a novel pain regulatory system.

Transgenic expression of delta-6 and delta-15 fatty acid desaturases enhances omega-3 polyunsaturated fatty acid accumulation in Synechocystis sp. PCC6803

BACKGROUND

Polyunsaturated fatty acids (PUFAs), which contain two or more double bonds in their backbone, are the focus of intensive global research, because of their nutritional value, medicinal applications, and potential use as biofuel. However, the ability to produce these economically important compounds is limited, because it is both expensive and technically challenging to separate omega-3 polyunsaturated fatty acids (ω-3 PUFAs) from natural oils. Although the biosynthetic pathways of some plant and microalgal ω-3 PUFAs have been deciphered, current understanding of the correlation between fatty acid desaturase content and fatty acid synthesis in Synechocystis sp. PCC6803 is incomplete.

RESULTS

We constructed a series of homologous vectors for the endogenous and exogenous expression of Δ6 and Δ15 fatty acid desaturases under the control of the photosynthesis psbA2 promoter in transgenic Synechocystis sp. PCC6803. We generated six homologous recombinants, harboring various fatty acid desaturase genes from Synechocystis sp. PCC6803, Gibberella fujikuroi and Mortierella alpina. These lines produced up to 8.9 mg/l of α-linolenic acid (ALA) and 4.1 mg/l of stearidonic acid (SDA), which are more than six times the corresponding wild-type levels, at 20°C and 30°C. Thus, transgenic expression of Δ6 and Δ15 fatty acid desaturases enhances the accumulation of specific ω-3 PUFAs in Synechocystis sp. PCC6803.

CONCLUSIONS

In the blue-green alga Synechocystis sp. PCC6803, overexpression of endogenous and exogenous genes encoding PUFA desaturases markedly increased accumulation of ALA and SDA and decreased accumulation of linoleic acid and γ-linolenic acid. This study lays the foundation for increasing the fatty acid content of cyanobacteria and, ultimately, for producing nutritional and medicinal products with high levels of essential ω-3 PUFAs.

Efficacy of omega-3 in treatment of recurrent aphthous stomatitis and improvement of quality of life: a randomized, double-blind, placebo-controlled study

OBJECTIVE

This study assessed the effects of systemic omega-3 on the treatment of recurrent aphthous stomatitis and on the improvement of quality of life.

STUDY DESIGN

Fifty participants were randomly assigned to receive either omega-3 (1 g, 3 times daily) or placebo for 6 months. Assessment of outcome measures including monthly number of new ulcers, average duration of ulcer episodes, and pain level of ulcers was carried out at baseline and monthly for 6 months. Analysis of potential impact on quality of life using the Oral Health Impact Profile 14 was carried out at baseline and 6 months.

RESULTS

Daily omega-3 treatment achieved a significant reduction in number of ulcers, duration of ulcers, and level of pain by 3 months that persisted for 6 months. Mean score on Oral Health Impact Profile 14 also significantly improved by 6 months.

CONCLUSIONS

A daily omega-3 regimen shows promise as therapy for treatment and management of patients with recurrent aphthous stomatitis.

Dietary fats and health: dietary recommendations in the context of scientific evidence

Although early studies showed that saturated fat diets with very low levels of PUFAs increase serum cholesterol, whereas other studies showed high serum cholesterol increased the risk of coronary artery disease (CAD), the evidence of dietary saturated fats increasing CAD or causing premature death was weak. Over the years, data revealed that dietary saturated fatty acids (SFAs) are not associated with CAD and other adverse health effects or at worst are weakly associated in some analyses when other contributing factors may be overlooked. Several recent analyses indicate that SFAs, particularly in dairy products and coconut oil, can improve health. The evidence of ω6 polyunsaturated fatty acids (PUFAs) promoting inflammation and augmenting many diseases continues to grow, whereas ω3 PUFAs seem to counter these adverse effects. The replacement of saturated fats in the diet with carbohydrates, especially sugars, has resulted in increased obesity and its associated health complications. Well-established mechanisms have been proposed for the adverse health effects of some alternative or replacement nutrients, such as simple carbohydrates and PUFAs. The focus on dietary manipulation of serum cholesterol may be moot in view of numerous other factors that increase the risk of heart disease. The adverse health effects that have been associated with saturated fats in the past are most likely due to factors other than SFAs, which are discussed here. This review calls for a rational reevaluation of existing dietary recommendations that focus on minimizing dietary SFAs, for which mechanisms for adverse health effects are lacking.

Gastric conditions control both the evolution of the organization of protein-stabilized emulsions and the kinetic of lipolysis during in vitro digestion

During digestion, lipids undergo modifications of their colloidal and molecular structures, which depend on the digestive conditions and the composition of the digestive juices. The aim of this work was to evaluate whether gastric pH and pepsin modulate the colloidal evolution and the bioacessibility of fatty acids of an oil-in-water emulsion stabilized by a protein during in vitro digestion. The fate of BSA-stabilized rapeseed oil-in-water emulsion during gastric phase at pH 2.5 or 4.0 with or without pepsin and its consequences on intestinal lipolysis was measured in the simulated gastric and duodenal conditions. The pH had limited impact but pepsin favoured flocculation and coalescence of the droplets, modulating the early stage of lipolysis but not its final extent.

Omega-3 polyunsaturated fatty acids and inflammatory processes: nutrition or pharmacology?

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are n-3 fatty acids found in oily fish and fish oil supplements. These fatty acids are able to inhibit partly a number of aspects of inflammation including leucocyte chemotaxis, adhesion molecule expression and leucocyte-endothelial adhesive interactions, production of eicosanoids like prostaglandins and leukotrienes from the n-6 fatty acid arachidonic acid, production of inflammatory cytokines and T cell reactivity. In parallel, EPA gives rise to eicosanoids that often have lower biological potency than those produced from arachidonioc acid and EPA and DHA give rise to anti-inflammatory and inflammation resolving resolvins and protectins. Mechanisms underlying the anti-inflammatory actions of n-3 fatty acids include altered cell membrane phospholipid fatty acid composition, disruption of lipid rafts, inhibition of activation of the pro-inflammatory transcription factor nuclear factor kappa B so reducing expression of inflammatory genes, activation of the anti-inflammatory transcription factor NR1C3 (i.e. peroxisome proliferator activated receptor γ) and binding to the G protein coupled receptor GPR120. These mechanisms are interlinked. In adult humans, an EPA plus DHA intake greater than 2 g day⁻¹ seems to be required to elicit anti-inflammatory actions, but few dose finding studies have been performed. Animal models demonstrate benefit from n-3 fatty acids in rheumatoid arthritis (RA), inflammatory bowel disease (IBD) and asthma. Clinical trials of fish oil in patients with RA demonstrate benefit supported by meta-analyses of the data. Clinical trails of fish oil in patients with IBD and asthma are inconsistent with no overall clear evidence of efficacy.

The role of omega-3 derived resolvins in arthritis

Omega-3 polyunsaturated fatty acids (PUFAs) are known to alleviate joint stiffness and pain in rheumatoid arthritis patients. However, the mechanisms by which omega-3s exert their beneficial effects has not been fully explored. Herein we discuss a novel class of bioactive lipid mediators, which are enzymatically biosynthesized in vivo from omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), termed resolvins. These lipid mediators exert anti-inflammatory and pro-resolving properties and are log-orders more potent than their precursors. We also highlight that formation of pro-resolving mediators can be enhanced by widely used anti-inflammatory and cardioprotective drugs (aspirin and statins) via the modification of cyclooxygenase-2 enzymatic activity. These bioactive pro-resolving lipid mediators provide further rationale for the beneficial effects of dietary supplementation with fish oils, and offer new avenues for developing therapeutics for inflammatory conditions such as rheumatoid arthritis.

Stearidonic acid as a supplemental source of ω-3 polyunsaturated fatty acids to enhance status for improved human health

There is substantial evidence to show that consumption and increased blood levels of the very long-chain (VLC) ω-3 polyunsaturated fatty acids (ω-3 PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are associated with health benefits. The consumption of oily fish is an effective way of increasing EPA and DHA intake and status, but intake in most Western countries remains below the levels recommended for optimal health. The reasons for this include not liking the taste, a concern about sustainability of fish supplies, or potential chemical and heavy metal contamination. Alternative dietary sources of ω-3 fatty acids to enhance EPA and DHA status in the body would therefore be beneficial. There are many non-fish food sources of the essential plant-derived ω-3 fatty acid α-linolenic acid, but conversion from this to longer-chain EPA and especially to DHA is poor. Stearidonic acid (SDA) is an intermediate fatty acid in the biosynthetic pathway from α-linolenic acid to VLC ω-3 PUFAs and the conversion from SDA is more efficient than from α-linolenic acid. However, there are few food sources rich in SDA. Oil crops naturally rich in SDA or enriched through genetic modification may offer an alternative supplemental oil to boost the population status of VLC ω-3 PUFAs. This review discusses the currently available evidence that increased SDA consumption can increase red blood cell EPA content, although this is less than the effect of supplementation directly with EPA. There is now a need for trials specifically designed to assess whether an increased SDA consumption would translate into improved human health outcomes.

Influence of marine n-3 polyunsaturated fatty acids on immune function and a systematic review of their effects on clinical outcomes in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease of the joints and bones. The n-6 polyunsaturated fatty acid (PUFA) arachidonic acid (ARA) is the precursor of inflammatory eicosanoids which are involved in RA. Some therapies used in RA target ARA metabolism. Marine n-3 PUFAs (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) found in oily fish and fish oils decrease the ARA content of cells involved in immune responses and decrease the production of inflammatory eicosanoids from ARA. EPA gives rise to eicosanoid mediators that are less inflammatory than those produced from ARA and both EPA and DHA give rise to resolvins that are anti-inflammatory and inflammation resolving, although little is known about these latter mediators in RA. Marine n-3 PUFAs can affect other aspects of immunity and inflammation relevant to RA, including dendritic cell and T cell function and production of inflammatory cytokines and reactive oxygen species, although findings for these outcomes are not consistent. Fish oil has been shown to slow the development of arthritis in animal models and to reduce disease severity. A number of randomised controlled trials of marine n-3 PUFAs have been performed in patients with RA. A systematic review included 23 studies. Evidence is seen for a fairly consistent, but modest, benefit of marine n-3 PUFAs on joint swelling and pain, duration of morning stiffness, global assessments of pain and disease activity, and use of non-steroidal anti-inflammatory drugs.