Effects of manipulation of dietary fatty acids on clinical manifestations of rheumatoid arthritis

[Procedures of complementary medicine in rheumatology]

Patients with diseases of the musculoskeletal system are confronted with a large quantity of treatment offers based on methods of complementary medicine. Despite a considerable number of publications on this topic, the scientific evidence is still poor. This article focuses on Ayurvedic medicine (AM), traditional Chinese medicine (TCM), mind-body medicine and homeopathy. These procedures have a longstanding tradition of practice and each claims to have its own theoretical concept; however, the application in the field of rheumatology can only be recommended either for specific entities or, in the case of homeopathy, not at all. In addition, this article summarizes the evidence for dietary recommendations, nutritional supplements and herbal medicine in rheumatology. The latter topics are frequently discussed in the popular press and are a much-debated issue between physicians and patients; however, clear-cut recommendations for the application on a scientific basis are the exception and mainly consist of the endorsement to adhere to the principles of a Mediterranean diet.

Effects of omega-3 supplementation on lipid metabolism, inflammation, and disease activity in rheumatoid arthritis: a meta-analysis of randomized controlled trials

INTRODUCTION

Omega-3 possesses anti-inflammatory and lipid metabolism modifying effects in rheumatoid arthritis (RA), but inconsistency exists among previous studies. This meta-analysis intended to explore the effects of omega-3 supplementation on fatty acid distribution, blood lipid profiles, inflammation, and disease activity in RA patients.

METHODS

This meta-analysis followed the Preferred Reporting Item for Systematic Reviews and Meta-Analyses (PRISMA) protocol. PubMed, Web of Science, and Embase databases were searched until August 31, 2023.

RESULTS

Eighteen randomized controlled trials with 1018 RA patients were included. Regarding fatty acid distribution, omega-3 supplementation increased eicosapentaenoic acid (EPA) [standardized mean difference (SMD): 0.74; 95% confidence interval (CI): 0.46, 1.01; P < 0.001] and docosahexanoic acid (DHA) (SMD: 0.62; 95% CI: 0.35, 0.89; P < 0.001), but reduced omega-6:omega-3 ratio (SMD: -1.06; 95% CI: -1.39, -0.73; P < 0.001) in RA patients. Regarding blood lipid, omega-3 supplementation decreased triglyceride (TG) in RA patients (SMD: -0.47; 95% CI: -0.78, -0.16; P = 0.003). Regarding clinical symptoms, omega-3 supplementation reduced tender joint count (TJC) in RA patients (SMD: -0.59; 95% CI: -0.79, -0.39; P < 0.001). Notably, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and disease activity score on 28 joints (DAS28) score were slightly decreased by omega-3 supplementation but without statistical significance (all P > 0.05). Publication bias was low, and stability assessed by sensitivity analysis was good.

CONCLUSION

Omega-3 supplementation increases EPA and DHA, but reduces the omega-6:omega-3 ratio, TG, and TJC in RA patients.

Free Fatty Acid 4 Receptor Activation Attenuates Collagen-Induced Arthritis by Rebalancing Th1/Th17 and Treg Cells

Dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) has been found to be beneficial in rodent rheumatoid arthritis models and human trials. However, the molecular targets of n-3 PUFAs and their beneficial effects on rheumatoid arthritis are under-researched. Free fatty acid receptor 4 (FFA4, also known as GPR120) is a receptor for n-3 PUFA. We aim to investigate whether FFA4 activation reduces collagen-induced rheumatoid arthritis (CIA) by using an FFA4 agonist, compound A (CpdA), in combination with DBA-1J Ffa4 gene wild-type (WT) and Ffa4 gene knock-out (KO) mice. CIA induced an increase in the arthritis score, foot edema, synovial hyperplasia, pannus formation, proteoglycan loss, cartilage damage, and bone erosion, whereas the administration of CpdA significantly suppressed those increases in Ffa4 WT mice but not Ffa4 gene KO mice. CIA increased mRNA expression levels of pro-inflammatory Th1/Th17 cytokines, whereas CpdA significantly suppressed those increases in Ffa4 WT mice but not Ffa4 gene KO mice. CIA induced an imbalance between Th1/Th17 and Treg cells, whereas CpdA rebalanced them in spleens from Ffa4 WT mice but not Ffa4 gene KO mice. In SW982 synovial cells, CpdA reduced the LPS-induced increase in pro-inflammatory cytokine levels. In summary, the present results suggest that the activation of FFA4 in immune and synovial cells could suppress the characteristics of rheumatoid arthritis and be an adjuvant therapy.

The Role of Marine n-3 Polyunsaturated Fatty Acids in Inflammatory-Based Disease: The Case of Rheumatoid Arthritis

Inflammation is a conserved process that involves the activation of immune and non-immune cells aimed at protecting the host from bacteria, viruses, toxins and injury. However, unresolved inflammation and the permanent release of pro-inflammatory mediators are responsible for the promotion of a condition called "low-grade systemic chronic inflammation", which is characterized by tissue and organ damage, metabolic changes and an increased susceptibility to non-communicable diseases. Several studies have demonstrated that different dietary components may influence modifiable risk factors for diverse chronic human pathologies. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), mainly eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), are well-recognized anti-inflammatory and immunomodulatory agents that are able to influence many aspects of the inflammatory process. The aim of this article is to review the recent literature that relates to the modulation of human disease, such as rheumatoid arthritis, by n-3 PUFAs.

Omega-3 long-chain polyunsaturated fatty acids: Metabolism and health implications

Recently, omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) have gained substantial interest due to their specific structure and biological functions. Humans cannot naturally produce these fatty acids (FAs), making it crucial to obtain them from our diet. This comprehensive review details n-3 LC-PUFAs and their role in promoting and maintaining optimal health. The article thoroughly analyses several sources of n-3 LC-PUFAs and their respective bioavailability, covering marine, microbial and plant-based sources. Furthermore, we provide an in-depth analysis of the biological impacts of n-3 LC-PUFAs on health conditions, with particular emphasis on cardiovascular disease (CVD), gastrointestinal (GI) cancer, diabetes, depression, arthritis, and cognition. In addition, we highlight the significance of fortification and supplementation of n-3 LC-PUFAs in both functional foods and dietary supplements. Additionally, we conducted a detailed analysis of the several kinds of n-3 LC-PUFAs supplements currently available in the market, including an assessment of their recommended intake, safety, and effectiveness. The dietary guidelines associated with n-3 LC-PUFAs are also highlighted, focusing on the significance of maintaining a well-balanced intake of n-3 PUFAs to enhance health benefits. Lastly, we highlight future directions for further research in this area and their potential implications for public health.

Efficacy of n-3 fatty acid supplementation on rheumatoid arthritis' disease activity indicators: a systematic review and meta-analysis of randomized placebo-controlled trials

Theoretical evidence and previous studies suggest that oralnutrient supplementation (ONS) with n-3 fatty acids for rheumatoid arthritis (RA) has the potential to lower disease activity indicators and non-steroidal anti-inflammatory drug (NSAID) uptake. A systematic search was conducted on five databases/registries from inception until May 23, 2021 with the aim to identify randomized placebo-controlled trials comparing n-3 supplements to placebo on disease-specific outcomes. A total of 23 studies matched the criteria (PROSPERO: CRD42019137041). Pooled analyses revealed that n-3 ONS provided a small effect in reducing pain [standardized mean difference (SMD): -0.16, 95% confidence intervals (CI): -0.40 to 0.09], and tender (SMD: -0.20, 95% CI: -0.46 to 0.05) and swollen joint count (SMD: -0.10, 95% CI: -0.28 to 0.07). In sensitivity analyses, there was a small effect in the reduction of NSAIDs intake (SMD: -0.22, 95% CI: -0.90 to 0.46), and c-reactive protein was reduced only by 0.21 mg/dL (95% CI: -0.75 to 0.33). Similar findings were observed regarding other objective/subjective outcomes. The certainty of the evidence was mostly of "very low/low" quality. Overall, n-3 ONS in RA might have a limited clinical benefit. Previous findings suggesting a reduction in NSAID intake may have been biased from the inadequate blinding of interventions.

Impact of type and dose of oral polyunsaturated fatty acid supplementation on disease activity in inflammatory rheumatic diseases: a systematic literature review and meta-analysis

Background

Polyunsaturated fatty acid (PUFA) supplementation has been reported to improve disease activity in inflammatory rheumatic diseases (IRDs). However, data are often conflicting and studies insufficiently large to draw conclusions. This systematic literature review and meta-analysis aimed to better estimate the effect of oral supplementation with omega (n)-3 and n-6 PUFA on IRD activity in terms of duration, dose, type, and source.

Methods

The literature was searched in PubMed, EMBASE, and Cochrane Library databases up to October 2020. Studies were reviewed in accordance with PRISMA guidelines. The effect of PUFA supplementation on disease activity was expressed as the standardized mean difference (95% CI). Metaregression and subgroup analyses involved type of IRD, Jadad score, PUFA source (animal or vegetable), and doses.

Results

We obtained 42 references; 30 randomized controlled studies were included comparing the effects of PUFA versus control on disease activity (710 IRD patients receiving PUFA supplementation and 710 controls, most with rheumatoid arthritis). We found a significant improvement in pain, swollen and tender joint count, Disease Activity Score in 28 joints, and Health Assessment Questionnaire score in IRD patients receiving PUFA supplementation as compared with controls, with a significant decrease in erythrocyte sedimentation rate but not C-reactive protein level. Although meta-regression revealed no difference by IRD type or source or dose of PUFA supplementation, subgroup analysis revealed more parameters significantly improved with animal- than vegetable-derived PUFAs and 3- to 6-month supplementation. Most studies examined high-dose supplementation (>2 g/day).

Conclusion

PUFA consumption, especially omega-3 from animal source >2 g/day, may improve IRD activity and might be an adjuvant therapy in rheumatoid arthritis.

Trial registration

The protocol was registered at PROSPERO (CRD42021253685).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02781-2.

Omega-3 Fatty Acids and Balanced Gut Microbiota on Chronic Inflammatory Diseases: A Close Look at Ulcerative Colitis and Rheumatoid Arthritis Pathogenesis

The aim of this article was to review experimental and clinical studies regarding the use of omega-3 fatty acids on the prevention and control of chronic inflammatory diseases with autoimmune background through the gut microbiota modulation. For this, natural omega-3 sources are presented emphasizing the importance of a healthy diet for the body's homeostasis and the enzymatic processes that these fatty acids go through once inside the body. The pathogenesis of ulcerative colitis and rheumatoid arthritis are revisited under the light of the gut microbiota dysbiosis approach and how those fatty acids are able to prevent and control these two pathological conditions that are responsible for the global chronic burden and functional disability and life-threatening comorbidities if not treated properly. As a matter of reflection, as we are living a pandemic crisis owing to COVID-19 infection, we present the potential of omega-3 in preventing a poor prognosis once they contribute to balancing the immune system modulation the inflammatory process.

The Relationship between Fatty Acids and the Development, Course and Treatment of Rheumatoid Arthritis

For this systematic review, a search of the relevant literature was conducted in the EMBASE and PubMed databases. We used the following terms: ‘rheumatoid arthritis’ in conjunction with ‘fatty acid’. The following inclusion criteria had to be satisfied for the studies to be included in the analysis: an RCT/observational/cohort study published in English. A total of seventy-one studies were analysed. The presented systematic review of the available data indicates that increased consumption of omega-3 fatty acids (FAs) may have a beneficial effect on human health by decreasing pain and disease activity in patients with RA. The beneficial effect of unsaturated FA on the clinical parameters of RA was demonstrated in all 71 studies analysed. The content of omega-3 FAs in the diet and the consumption of fish, which are their main source, may contribute to a reduced incidence of RA. FAs are an essential component in the synthesis of eicosanoids that exhibit anti-inflammatory properties. Due to the documented positive influence of unsaturated FAs on treatment outcomes, the use of a diet rich in long-chain unsaturated FAs should be the standard of care, along with pharmacotherapy, in the treatment of RA patients. An important element in the control of the treatment process should be the routine assessment of the quality of life of RA patients.

Rheumatoid arthritis and dietary interventions: systematic review of clinical trials

CONTEXT

The impact of various dietary interventions on rheumatoid arthritis (RA), characterized by immune-inflammatory response, has been subject to increased attention.

OBJECTIVE

A systematic review was conducted to update the current knowledge on the effects of nutritional, dietary supplement, and fasting interventions on RA outcomes.

DATA SOURCES

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with prespecification of all methods, Medline and Embase were systematically searched for relevant articles.

DATA EXTRACTION

Data were extracted by 2 independent reviewers.

RESULTS

A total of 70 human studies were identified. Administration of omega-3 polyunsaturated fatty acids at high doses resulted in a reduction in RA disease activity and a lower failure rate of pharmacotherapy. Vitamin D supplementation and dietary sodium restriction were beneficial on some RA outcomes. Fasting resulted in significant but transient subjective improvements. While the Mediterranean diet demonstrated improvements in some RA disease activity measures, outcomes from vegetarian, elimination, peptide, or elemental diets suggested that responses are very individualized.

CONCLUSION

Some dietary approaches may improve RA symptoms and thus it is recommended that nutrition should be routinely addressed.

Intended Ranges and Correlations between Percentages of Variables Like Oleic Acid, Eicosapentaenoic Acid, and Arachidonic Acid

In chicken muscle, we previously showed that ranges of oleic acid (OA), arachidonic acid (AA), and eicosapentaenoic acid (EPA) might explain why %OA was inversely related to %AA, and that %EPA correlated positively with %AA. We here try to clarify further how ranges of the fatty acids could make strong associations between their relative amounts, utilizing published data from chicken muscle and human sera. We generated random number variables (OA’, AA’, EPA’) in lieu of the true variables, and we studied effects of altering their ranges upon scatterplots of %OA’ vs. %AA’ (%EPA’), and %AA’ vs. %EPA’. To explain the results, we first applied the equation OA’ + AA’ + EPA’ = S, i.e., %OA’ + %AA’ + %EPA’ = 100. Next, we considered how the OA’ (AA’, EPA’) fractions of S related to S. Increasing the OA’ range towards higher values improved the positive association between %AA’ and %EPA’. Thus, increased intake of OA could improve the positive correlations between percentages of eicosanoid precursors, raising the question of whether “intended ranges” of some fatty acids represent a case of evolutionary selection to, e.g., achieve balance between eicosanoids.

Lipid Metabolism Profiles in Rheumatic Diseases

Rheumatic diseases are a group of chronic autoimmune disorders that involve multiple organs or systems and have high mortality. The mechanisms of these diseases are still ill-defined, and targeted therapeutic strategies are still challenging for physicians. Recent research indicates that cell metabolism plays important roles in the pathogenesis of rheumatic diseases. In this review, we mainly focus on lipid metabolism profiles (dyslipidaemia, fatty acid metabolism) and mechanisms in rheumatic diseases and discuss potential clinical applications based on lipid metabolism profiles.

Insights in the Role of Lipids, Oxidative Stress and Inflammation in Rheumatoid Arthritis Unveiled by New Trends in Lipidomic Investigations

Rheumatoid arthritis (RA) is a highly debilitating chronic inflammatory autoimmune disease most prevalent in women. The true etiology of this disease is complex, multifactorial, and is yet to be completely elucidated. However, oxidative stress and lipid peroxidation are associated with the development and pathogenesis of RA. In this case, oxidative damage biomarkers have been found to be significantly higher in RA patients, associated with the oxidation of biomolecules and the stimulation of inflammatory responses. Lipid peroxidation is one of the major consequences of oxidative stress, with the formation of deleterious lipid hydroperoxides and electrophilic reactive lipid species. Additionally, changes in the lipoprotein profile seem to be common in RA, contributing to cardiovascular diseases and a chronic inflammatory environment. Nevertheless, changes in the lipid profile at a molecular level in RA are still poorly understood. Therefore, the goal of this review was to gather all the information regarding lipid alterations in RA analyzed by mass spectrometry. Studies on the variation of lipid profile in RA using lipidomics showed that fatty acid and phospholipid metabolisms, especially in phosphatidylcholine and phosphatidylethanolamine, are affected in this disease. These promising results could lead to the discovery of new diagnostic lipid biomarkers for early diagnosis of RA and targets for personalized medicine.

Dietary Interventions Are Beneficial for Patients with Chronic Pain: A Systematic Review with Meta-Analysis

Background

The standard Western diet is high in processed hyperpalatable foods that displace nutrient-dense whole foods, leading to inflammation and oxidative stress. There is limited research on how these adverse metabolic drivers may be associated with maladaptive neuroplasticity seen in chronic pain and whether this could be attenuated by a targeted nutritional approach. The aim of this study was to review the evidence for whole-food dietary interventions in chronic pain management.

Method

A structured search of eight databases was performed up to December 2019. Two independent reviewers screened studies and evaluated risk of bias by using the National Institutes of Health assessment tool for controlled or pre–post studies and the Joanna Briggs checklist for case reports. A meta-analysis was performed in Review Manager.

Results

Forty-three studies reporting on 48 chronic pain groups receiving a whole-food dietary intervention were identified. These included elimination protocols (n = 11), vegetarian/vegan diets (n = 11), single-food changes (n = 11), calorie/macronutrient restriction (n = 8), an omega-3 focus (n = 5), and Mediterranean diets (n = 2). A visual analog scale was the most commonly reported pain outcome measure, with 17 groups reporting a clinically objective improvement (a two-point or 33% reduction on the visual analog scale). Twenty-seven studies reported significant improvement on secondary metabolic measures. Twenty-five groups were included in a meta-analysis that showed a significant finding for the effect of diet on pain reduction when grouped by diet type or chronic pain type.

Conclusion

There is an overall positive effect of whole-food diets on pain, with no single diet standing out in effectiveness. This suggests that commonalities among approaches (e.g., diet quality, nutrient density, weight loss) may all be involved in modulating pain physiology. Further research linking how diet can modulate physiology related to pain (such as inflammation, oxidative stress, and nervous system excitability) is required.

RT, Copland C, Giaquinto A, Juliano RA, Bhatt DL. Mineral oil: safety and use as placebo in REDUCE-IT and other clinical studies

Mineral oil is often used as a clinical trial placebo. Pharmaceutical-grade mineral oil consists of a mixture of saturated hydrocarbons, with a purity and chemical structure that differs substantially from food-grade or technical-/industrial-grade mineral oils. Interest in mineral oil was piqued by suggestions that a portion of the substantially positive results of the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) might be attributable to the theoretical negative effects of mineral oil rather than being due to the clinical benefits of icosapent ethyl. The objective of this review was to explore possible mineral oil safety and efficacy effects and contextualize these findings in light of the REDUCE-IT conclusions. A literature search identified studies employing mineral oil placebos. Eighty studies were identified and relevant data extracted. Adverse events associated with mineral oil were generally gastrointestinal and consistent with use as a lubricant laxative. Changes in triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and other biomarkers were inconsistent and generally not statistically significant, or clinically meaningful with mineral oil, as were changes in blood pressure. There was no consistent evidence that mineral oil in the amounts used in the REDUCE-IT or Effect of Vascepa on Progression of Coronary Atherosclerosis in Patients With Elevated Triglycerides on Statin Therapy (EVAPORATE) trials affects absorption of essential nutrients or drugs, including statins. These results were then considered alongside publicly available data from REDUCE-IT. Based on available evidence, mineral oil does not appear to impact medication absorption or efficacy, or related clinical outcomes, and, therefore, does not meaningfully affect study conclusions when used as a placebo at the quantities used in clinical trials.

Ideal food pyramid for patients with rheumatoid arthritis: A narrative review

Emerging literature suggests that diet plays an important modulatory role in rheumatoid arthritis (RA) because diet is an environmental factor that affects inflammation, antigen presentation, antioxidant defense mechanisms and gut microbiota. Patients with RA frequently ask their doctors about which diets to follow, and even in the absence of advice from their physicians, many patients are undertaking various dietary interventions. Given this background, the aim of this review is to evaluate the evidence to date regarding the ideal dietary approach for management of RA in order to reduce the counteracting inflammation, and to construct a food pyramid for patients with RA. The pyramid shows that carbohydrates should be consumed every day (3 portions of whole grains, preferably gluten free), together with fruits and vegetables (5 portions; among which fruit, berries and citrus fruit are to be preferred, and among the vegetables, green leafy ones.), light yogurt (125 ml), skim milk (200 ml), 1 glass (125 ml) of wine and extra virgin olive oil; weekly, fish (3 portions), white meat (3 portions), legumes (2 portions) eggs (2 portions), seasoned cheeses (2 portions), and red or processed meats (once a week). At the top of the pyramid, there are two pennants: one green means that subjects with RA need some personalized supplementation (vitamin D and omega 3) and one red means that there are some foods that are banned (salt and sugar). The food pyramid allows patients to easily figure out what to eat.

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.

The Effect of Omega-3 Fatty Acids on Rheumatoid Arthritis

Omega-3 fatty acids are unsaturated fatty acids thought to play a role in health and disease. They are known as essential fatty acids, as they cannot be synthesized in mammals. Omega-3 fatty acids have a beneficial effect on the secondary prevention of coronary artery disease and stroke and are essential for the development and function of the nervous system and the retina in man. Omega-3 fatty acids are thought to have immunomodulatory properties as they act as precursors to lipid mediators of inflammation which may limit or modulate the inflammatory response. Omega-3 fatty acids seem to prevent or attenuate experimental arthritis. They may have a beneficial effect in the treatment of rheumatoid arthritis. Clinical studies have shown that omega-3 fatty acids may have a modulatory effect on disease activity, namely on the number of swollen and tender joints. It appears that omega-3 fatty acids may modulate disease activity in rheumatoid arthritis.

Beneficial effects of fish oil enriched in omega-3 fatty acids on the development and maintenance of neuropathic pain

OBJECTIVE

The aim of this work was to assess the preventive effect of an eicosapentaenoic acid/docosahexaenoic acid-concentrate fish oil on neuropathic pain development and regenerative features of sciatic nerve in rats.

METHODS

In the present study, rats with chronic constriction injury (CCI) of the sciatic nerve and sham-operated ones received fish oil enriched in omega-3 fatty acids (0.36 or 0.72 g/kg per day, oral) or saline solution for 21 days, with thermal hyperalgesia and mechanical allodynia being assessed before and 3, 7, 14 and 21 days after injury.

KEY FINDINGS

Fish oil enriched in omega-3 fatty acids (0.72 g/kg) reversed thermal hyperalgesia and significantly reduced mechanical allodynia. In addition, ω-3 treatment (0.72 g/kg) promoted the recovery of the Sciatic Functional Index as well as restored axonal density and morphology, without the formation of neuroma in the injured sciatic nerves after 21 days.

CONCLUSION

We conclude that the fish oil enriched in omega-3 fatty acids administration relieves thermal hyperalgesia and mechanical allodynia effectively and also enhances the recovery process in rats with CCI of the sciatic nerve. These findings might contribute to new therapeutic approaches including omega-3 fatty acids in neuropathic pain treatment.

The Role of Dietary Fiber in Rheumatoid Arthritis Patients: A Feasibility Study

Short-chain fatty acids are microbial metabolites that have been shown to be key regulators of the gut-joint axis in animal models. In humans, microbial dysbiosis was observed in rheumatoid arthritis (RA) patients as well as in those at-risk to develop RA, and is thought to be an environmental trigger for the development of clinical disease. At the same time, diet has a proven impact on maintaining intestinal microbial homeostasis. Given this association, we performed a feasibility study in RA patients using high-fiber dietary supplementation with the objective to restore microbial homeostasis and promote the secretion of beneficial immunomodulatory microbial metabolites. RA patients (n = 36) under routine care received daily high-fiber bars or cereals for 28 days. Clinical assessments and laboratory analysis of immune parameters in blood and stool samples from RA patients were done before and after the high-fiber dietary supplementation. We observed an increase in circulating regulatory T cell numbers, favorable Th1/Th17 ratios, as well as decreased markers of bone erosion in RA patients after 28 days of dietary intervention. Furthermore, patient-related outcomes of RA improved. Based on these results, we conclude that controlled clinical studies of high-fiber dietary interventions could be a viable approach to supplement or complement current pharmacological treatment strategies.

Therapeutic Potential of ω-3 Polyunsaturated Fatty Acids in Human Autoimmune Diseases

The recognition of ω-3 polyunsaturated acids (PUFAs) as essential fatty acids to normal growth and health was realized more than 80 years ago. However, the awareness of the long-term nutritional intake of ω-3 PUFAs in lowering the risk of a variety of chronic human diseases has grown exponentially only since the 1980s (1, 2). Despite the overwhelming epidemiological evidence, many attempts of using fish-oil supplementation to intervene human diseases have generated conflicting and often ambiguous outcomes; null or weak supporting conclusions were sometimes derived in the subsequent META analysis. Different dosages, as well as the sources of fish-oil, may have contributed to the conflicting outcomes of intervention carried out at different clinics. However, over the past decade, mounting evidence generated from genetic mouse models and clinical studies has shed new light on the functions and the underlying mechanisms of ω-3 PUFAs and their metabolites in the prevention and treatment of rheumatoid arthritis, systemic lupus erythematosus (SLE), multiple sclerosis, and type 1 diabetes. In this review, we have summarized the current understanding of the effects as well as the underlying mechanisms of ω-3 PUFAs on autoimmune diseases.

The Mediterranean diet, fish oil supplements and Rheumatoid arthritis outcomes: evidence from clinical trials

The impact of dietary interventions such as specific types of diet or nutritional supplements in rheumatoid arthritis (RA) has been subject to increased attention in recent years. The recognition of the unmet need to better understand the effects of specific dietary interventions on disease outcomes in RA, along with the growing patient interest on lifestyle interventions beyond pharmacotherapy, have informed the undertaking of this narrative literature review. The benefits of the Mediterranean Diet (MD) have been shown in various studies, although only a limited number of trials focus specifically on RA. Based on the studies reviewed, the MD may provide benefits in reducing pain and swollen and tender joints in RA patients. There is more and better evidence that n-3 polyunsaturated fat (PUFA) supplementation has the potential to reduce inflammation and provide clinical benefit, possibly slowing progression to pharmacotherapy. Yet, many of these studies to date are limited in their methodology; this being partly a reflection of the complexity of the research questions being addressed. Consequently, the conclusions that can be robustly drawn from their results are restricted. With a focus on clinical trials on the MD and fish oil supplementation, this review critically appraises the evidence, discussing the findings of studies in the wider context of impact on RA outcomes, methodological challenges, and practical points to consider as part of the routine care of RA patients.

Risk factor assessment of rheumatoid arthritis in North Kerala

OBJECTIVE

Rheumatoid arthritis (RA) is a multifactorial disease; it leads to disabling and painful chronic inflammatory arthritis. Its onset may be delayed or even prevented by modifying the risk factors involved. Many genetic, epigenetic, and environmental factors are implicated in the pathogenesis of RA. The objectives of this case-control study were to assess various risk factors in our population and to compare the same with age- and sex-matched controls.

METHODS

We studied 118 cases with RA diagnosed using the EULAR criteria. In total, 581 age- and sex-matched controls were selected. Each individual was administered a separate questionnaire regarding their risk factors (known risk factors were studied). The implicated dietary factors were incorporated in a food frequency questionnaire (FFQ) and administered to both cases and controls. Comparison was made between those who consume an item at a particular frequency, who consume less, and who consume nothing at all. Among those who consume, each group was re-compared. Statistical analysis was conducted using Statistical Package for Social Sciences (IBM Corp.; Armonk, NY, USA).

RESULTS

There was significant relationship for family history, periodontitis, history of chikungunya, and sun exposure (p<0.05). Association with various food items was studied using the FFQ, but the relationship was inconsistent, probably due to consumption of modified diet by the persons with RA. Also, a majority of cases were females and nonsmokers for assessing an association with smoking habits.

CONCLUSION

In our population, previous infections (e.g., chikungunya and poor oral hygiene with periodontitis) were the prominently observed risk factors. Also, smoking was less common among women, and probably contributed less, as majority of cases were females. For dietary pattern association, a prospective cohort study may be needed.

Long-Term Dietary Changes after Diagnosis of Rheumatoid Arthritis in Swedish Women: Data from a Population-Based Cohort

Objective

To investigate long-term dietary changes after rheumatoid arthritis (RA) diagnosis in Swedish women, compared to women without RA.

Methods

This study included 21,602 women from the Swedish Mammography Cohort (SMC), who completed dietary questionnaires in 1997 and 2009. Between 1997 and 2009, 191 women were diagnosed with RA. Dietary changes after RA diagnosis were analyzed based on intake of 82 food items. Statistical analysis included linear mixed models.

Results

Women with RA, compared to women without RA, had significantly lower intake (mean servings per week) of animal products such as black pudding, egg, kidney, and liver paste (2.94±2.73 versus 2.45±1.82, p=0.010) and dairy products (35.14±20.02 versus 28.42±16.10, p=0.040) in 1997 and of cereals and grains (31.01±15.54 versus 28.00±14.98, p=0.009) in 2009. However, multivariable adjusted changes in dietary intake from 1997 to 2009 did not show any significant difference in intake. Nevertheless, women without RA increased their intake of whole wheat bread, wheat/oat bran, and rice more than women with RA.

Conclusion

Women who had been diagnosed with RA had similar dietary patterns over time as the general population; these women did not remarkably change their diet over time due to their disease. Dietary recommendations for RA patients are needed.

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.

Relationship Between Fish Consumption and Disease Activity in Rheumatoid Arthritis

OBJECTIVE

To assess whether more frequent fish consumption is associated with lower rheumatoid arthritis (RA) disease activity scores among participants in an RA cohort.

METHODS

We conducted a cross-sectional analysis using baseline data from participants in the Evaluation of Subclinical Cardiovascular Disease and Predictors of Events in Rheumatoid Arthritis cohort study. Frequency of fish consumption was assessed by a baseline food frequency questionnaire assessing usual diet in the past year. Multivariable, total energy-adjusted linear regression models provided effect estimates and 95% confidence intervals (95% CIs) for frequency of fish consumption (i.e., never to <1 time/month, 1 time/month to <1 time/week, 1 time/week, and ≥2 times/week) on baseline Disease Activity Score in 28 joints (DAS28) using the C-reactive protein (CRP) level. We also estimated the difference in DAS28-CRP associated with increasing fish consumption by 1 serving per week.

RESULTS

Among 176 participants, the median DAS28-CRP score was 3.5 (interquartile range 2.9-4.3). In an adjusted linear regression model, subjects consuming fish ≥2 times/week had a significantly lower DAS28-CRP compared with subjects who ate fish never to <1 time/month (difference -0.49 [95% CI -0.97, -0.02]). For each additional serving of fish per week, DAS28-CRP was significantly reduced by 0.18 (95% CI -0.35, -0.004).

CONCLUSION

Our findings suggest that higher intake of fish may be associated with lower disease activity in RA patients.

Managing Rheumatoid Arthritis with Dietary Interventions

Self-help by means of dietary interventions can help in management of various disorders including rheumatoid arthritis (RA), a debilitating autoimmune disease. Dietary interventions necessitate a widespread appeal for both patients as well as clinicians due to factors including affordability, accessibility, and presence of scientific evidences that demonstrate substantial benefits in reducing disease symptoms such as pain, joint stiffness, swelling, tenderness and associated disability with disease progression. However, there is still an uncertainty among the community about the therapeutic benefits of dietary manipulations for RA. In the present review, we provide an account of different diets and their possible molecular mechanism of actions inducing observed therapeutic benefits for remission and management of RA. We further indicate food that can be a potential aggravating factor for the disease or may help in symptomatic relief. We thereafter summarize and thereby discuss various diets and food which help in reducing levels of inflammatory cytokines in RA patients that may play an effective role in management of RA following proper patient awareness. We thus would like to promote diet management as a tool that can both supplement and complement present treatment strategies for a better patient health and recovery.

Polyunsaturated fatty acids: any role in rheumatoid arthritis?

Background

Polyunsaturated fatty acids (PUFAs) are members of the family of fatty acids and are included in the diet. Particularly, western diet is usually low in n-3 PUFAs and high in n-6 PUFAs. PUFAs play a central role in the homeostasis of immune system: n-6 PUFAs have predominantly pro-inflammatory features, while n-3 PUFAs seem to exert anti-inflammatory and pro-resolving properties. Rheumatoid arthritis (RA) is a chronic inflammatory arthritis in which many inflammatory pathways contribute to joint and systemic inflammation, disease activity, and structural damage. Research on PUFAs could represent an important opportunity to better understand the pathogenesis and to improve the management of RA patients.

Methods

We searched PubMed, Embase, EBSCO-Medline, Cochrane Central Register of Controlled Trials (CENTRAL), CNKI and Wanfang to identify primary research reporting the role of n-3 PUFAs in rheumatoid arthritis both in humans and in animal models up to the end of March 2017.

Results

Data from animal models allows to hypothesize that n-3 PUFAs supplementation may represent an interesting perspective in future research as much in prevention as in treating RA. In humans, several case-control and prospective cohort studies suggest that a high content of n-3 PUFAs in the diet could have a protective role for incident RA in subjects at risk. Moreover, n-3 PUFAs supplementation has been assessed as a valuable therapeutic option also for patients with RA, particularly in order to improve the pain symptoms, the tender joint count, the duration of morning stiffness and the frequency of NSAIDs assumption.

Conclusions

n-3 PUFAs supplementation could represent a promising therapeutic option to better control many features of RA. The impact of n-3 PUFAs on radiographic progression and synovial histopathology has not been yet evaluated, as well as their role in early arthritis and the combination with biologics.

Intake of ω-3 polyunsaturated fatty acids in patients with rheumatoid arthritis: A systematic review and meta-analysis

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic, autoimmune inflammatory disease of multiple joints that puts the patient at high risk for developing cardiovascular diseases (CVDs). The aim of the present study was to conduct an up-to-date systematic review and meta-analysis of published randomized controlled trials (RCTs) to assess potential changes in RA disease activity, inflammation, and CVD risk after oral intake of ω-3 polyunsaturated fatty acids.

METHODS

Publications up to July 31, 2016 were examined using the PubMed, SCOPUS, and EMBASE databases.

INCLUSION CRITERIA

English language; human subjects; both sexes; RCTs; oral intake of ω-3 fatty acids; minimum duration of 3 mo; and no medication change throughout intervention. The Cochrane Risk of Bias tool was used to assess quality of trials. We included 20 RCTs, involving 717 patients with RA in the intervention group and 535 RA patients in the control group.

RESULTS

Despite the evidence of overall low quality of trials, consumption of ω-3 fatty acids was found to significantly improve eight disease-activity-related markers. Regarding inflammation, only leukotriene B4 was reduced (five trials, standardized mean difference [SMD], -0.440; 95% confidence interval [CI], -0.676 to -0.205; I² = 46.5%; P < 0.001). A significant amelioration was found for blood triacylglycerol levels (three trials, SMD, -0.316; 95% CI, -0.561 to -0.070; I² = 0.0%; P = 0.012).

CONCLUSION

The beneficial properties of ω-3 polyunsaturated fatty acids on RA disease activity confirm the results of previous meta-analyses. Among five proinflammatory markers evaluated, only leukotriene B4 was found to be reduced. However, a positive effect on blood lipid profile of patients with RA was evident, perhaps for the first time.

The ratio of serum eicosapentaenoic acid to arachidonic acid and risk of cancer death in a Japanese community: The Hisayama Study

Background

Whether the intake of eicosapentaenoic acid (EPA) or arachidonic acid (AA) affects the risk of cancer remains unclear, and the association between the serum EPA:AA ratio and cancer risk has not been fully evaluated in general populations.

Methods

A total of 3098 community-dwelling subjects aged ≥40 years were followed up for 9.6 years (2002–2012). The levels of the serum EPA:AA ratio were categorized into quartiles (<0.29, 0.29–0.41, 0.42–0.60, and >0.60). The risk estimates were computed using a Cox proportional hazards model. The same analyses were conducted for the serum docosahexaenoic acid to arachidonic acid (DHA:AA) ratio and individual fatty acid concentrations.

Results

During the follow-up period, 121 subjects died of cancer. Age- and sex-adjusted cancer mortality increased with lower serum EPA:AA ratio levels (P trend<0.05). In the multivariable-adjusted analysis, the subjects in the first quartile of the serum EPA:AA ratio had a 1.93-fold (95% confidence interval, 1.15–3.22) greater risk of cancer death than those in the fourth quartile. Lower serum EPA concentrations were marginally associated with higher cancer mortality (P trend<0.11), but the serum DHA or AA concentrations and the serum DHA:AA ratio were not (all P trend>0.37). With regard to site-specific cancers, lower serum EPA:AA ratio was associated with a higher risk of death from liver cancer. However, no such associations were detected for deaths from other cancers.

Conclusions

These findings suggest that decreased level of the serum EPA:AA ratio is a significant risk factor for cancer death in the general Japanese population.

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Lower serum EPA:AA ratio was significantly associated with higher cancer mortality.

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The risk of death from liver cancer increased with lower serum EPA:AA ratio.

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No significant association was found between serum DHA:AA ratio and cancer death.

Plasma Levels of Eicosapentaenoic Acid Are Associated with Anti-TNF Responsiveness in Rheumatoid Arthritis and Inhibit the Etanercept-driven Rise in Th17 Cell Differentiation in Vitro

OBJECTIVE

To determine whether levels of plasma n-3 polyunsaturated fatty acids are associated with response to antitumor necrosis factor (anti-TNF) agents in rheumatoid arthritis (RA), and whether this putative effect may have its basis in altering anti-TNF-driven Th17 cell differentiation.

METHODS

Plasma was collected at baseline and after 3 months of anti-TNF treatment in 22 patients with established RA, and fatty acid composition of the phosphatidylcholine (PC) component was measured. CD4+CD25- T cells and monocytes were purified from the blood of healthy donors and cocultured in the presence of anti-CD3, with or without etanercept (ETN), eicosapentaenoic acid (EPA), or the control fatty acid, linoleic acid (LA). Expression of interleukin 17 and interferon-γ was measured by intracellular staining and flow cytometry.

RESULTS

Plasma PC EPA levels and the EPA/arachidonic acid ratio correlated inversely with change in the Disease Activity Score at 28 joints (DAS28) at 3 months (-0.51, p = 0.007 and -0.48, p = 0.01, respectively), indicating that higher plasma EPA was associated with a greater reduction in DAS28. Plasma PC EPA was positively associated with European League Against Rheumatism response (p = 0.02). An increase in Th17 cells post-therapy has been associated with nonresponse to anti-TNF. ETN increased Th17 frequencies in vitro. Physiological concentrations of EPA, but not LA, prevented this.

CONCLUSION

EPA status was associated with clinical improvements to anti-TNF therapy in vivo and prevented the effect of ETN on Th17 cells in vitro. EPA supplementation might be a simple way to improve anti-TNF outcomes in patients with RA by suppressing Th17 frequencies.

Investigation of the effect of phlomisoside F on complete Freund's adjuvant-induced arthritis

Phlomis younghusbandii Mukerjee (Labiatae) has been reported to be effective in the treatment of rheumatoid arthritis (RA). In the present study, the anti-inflammatory and anti-arthritic effects of phlomisoside F (PF), isolated from P. younghusbandii Mukerjee (Labiatae), were investigated in male Wistar rats subjected to carrageen-induced paw edema and complete Freund's adjuvant (CFA)-induced arthritis. Arthritis scores were evaluated by a 5-point ordinal scale (scores 0-4). Expression levels of TNF-α, IL-1β, IL-6, IL-10, COX-2 and 5-LOX were determined via ELISA and western blot assays. Subsequent to establishing the edema and arthritis models, oral administration of PF (5, 10 and 20 mg/kg) significantly inhibited mean edema rate, compared with the control group in carrageenan-induced paw edema assay. In addition, administration of PF (5, 10 and 20 mg/kg/day) for 28 days markedly exhibited an anti-arthritic activity by offsetting the body weight loss, inhibiting the paw edema, reducing the arthritis scores and the indices of thymus and spleen, inhibiting the expression levels of TNF-α, IL-1β, IL-6, COX-2 and 5-LOX, and increasing the expression of IL-10, when compared with the respective control group in CFA-induced arthritis assay. In conclusion, PF is a valuable anti-arthritic constituent of P. younghusbandii, and the present study results suggest that this herb may be used in the treatment of RA.

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.

Dietary intake and risk of rheumatoid arthritis-a cross section multicenter study

Environmental factors play an important role in the development of rheumatoid arthritis (RA). Among these factors, smoking is generally considered to be an established risk factor for RA. Data regarding the impact of diet on risk of RA development is limited. This study assessed the impact of dietary patterns on RA susceptibility in Chinese populations. This was a large scale, case-control study composed of 968 patients with RA and 1037 matched healthy controls. Subjects were recruited from 18 teaching hospitals. Socio-demographic characteristics and dietary intakes 5 years prior to the onset of RA were reported by a self-administered questionnaire. Differences in quantity of consumption between cases and controls were analyzed by Student's t test. Multiple logistic regression analysis was applied to identify independent dietary risk factor(s) responsible for RA susceptibility. Compared to healthy individuals, RA patients had decreased consumption of mushrooms (P = 0.000), beans (P = 0.006), citrus (P = 0.000), poultry (P = 0.000), fish (P = 0.000), edible viscera (P = 0.018), and dairy products (P = 0.005). Multivariate analyses revealed that several dietary items may have protective effects on RA development, such as mushrooms (aOR = 0.669; 95%CI = 0.518-0.864, P = 0.002), citrus fruits (aOR = 0.990; 95%CI = 0.981-0.999, P = 0.04), and dairy products (aOR = 0.921; 95%CI 0.867-0.977, P = 0.006). Several dietary factors had independent effects on RA susceptibility. Dietary interventions may reduce the risk of RA.

Anti-inflammatory effects of docosahexaenoic acid: Implications for its cancer chemopreventive potential

The implication of inflammatory tissue damage in pathophysiology of human cancer as well as some metabolic disorders has been under intense investigation. Numerous studies have identified a series of critical signaling molecules involved in cellular responses to inflammatory stimuli. These include nuclear factor κB, peroxisome proliferator-activated receptor γ, nuclear factor erythroid 2 p45-related factor 2 and sterol regulatory element-binding protein 1. The proper regulation of these transcription factors mediating pro- and anti-inflammatory signaling hence provides an important strategy for the chemoprevention of inflammation-associated cancer. There is compelling evidence supporting that dietary supplementation with fish oil-derived ω-3 polyunsaturated fatty acids including docosahexaenoic acid (DHA) ameliorates symptomatic inflammation associated with cancer as well as other divergent human disorders. Acute or physiologic inflammation is an essential body's first line of defence to microbial infection and tissue injuries, but it must be properly completed by a process termed 'resolution'. Failure of resolution mechanisms can result in persistence of inflammation, leading to chronic inflammatory conditions and related malignancies. The phagocytic engulfment of apoptotic neutrophils and clearance of their potentially histotoxic contents by macrophages, called efferocytosis is an essential component in resolving inflammation. Of note, DHA is a precursor of endogenous proresolving lipid mediators which regulate the leukocyte trafficking and recruitment and thereby facilitate efferocytosis. Therefore, DHA and its metabolites may have a preventive potential in the management of human cancer which arises as a consequence of impaired resolution of inflammation as well as chronic inflammation.

Role of Omega-3 Fatty Acid Supplementation in Inflammation and Malignancy

Omega-3 fatty acids (FAs), which include eicosapentaenoic acid (EPA) and docosahexaenoic acid, are found in fish oils and have long been investigated as components of therapy for various disease states. Population studies initially revealed the cardioprotective and anti-inflammatory effects of omega-3 FAs and EPA, with subsequent clinical studies supporting the therapeutic role of omega-3 FAs in cardiovascular and chronic inflammatory conditions. Prospective randomized placebo-controlled trials have also demonstrated the utility of omega-3 FA supplementation in malignancy and cancer cachexia. In recent years, in vitro and animal studies have elucidated some of the mechanistic explanations underlying the wide range of biological effects produced by omega-3 FAs and EPA, including their antiproliferative and anticachectic actions in malignancy. In this review, the authors discuss the recent progress made with omega-3 FAs, focusing on the advances in mechanistic understanding and the results of clinical trials.

Effect of n-3 fatty acids on the expression of inflammatory genes in THP-1 macrophages

Background

Uncontrolled inflammation participates in the development of inflammatory diseases. Beneficial effects of polyunsaturated fatty acids belonging to the n-3 family such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on inflammation have been reported.

The present study investigates the basal effects of EPA, DHA and a mixture EPA + DHA on the expression of 10 genes (AKT1, MAPK, NFKB, TNFA, IL1Β, MCP1, ALOX5, PTGS2, MGST1and NOS2) related to inflammation in unstimulated cultured THP1 macrophages. Cells were incubated for 24 h with n-3 PUFAs (50 μM and 10 μM EPA, DHA, EPA + DHA). Expression levels of inflammatory genes were analyzed by real-time PCR.

Results

50 μM, 10 μM EPA and 50 μM EPA + DHA decreased the expression of genes involved in the NF-κB pathway (MAPK, AKT1, and NFKB). Treatment with 50 μM, 10 μM EPA, 50 μM DHA and EPA + DHA decreased expression levels of cytokines genes IL1Β and MCP1. TNFA expression was decreased by 50 μM, 10 μM of EPA, DHA and with 50 μM EPA + DHA. Two genes involved in the fatty acid metabolism (PTGS2 and ALOX5) were also modulated by the n-3 FAs. 50 μM of DHA and EPA + DHA inhibited PTGS2 expression when the two concentrations of EPA, 50 μM DHA and EPA + DHA inhibited ALOX5 expression. Finally, the effects of n-3 FAs were studied among genes involved in the oxidative stress. 50 μM of each fatty acid increased MGST1 expression. Both concentration of EPA and 50 μM DHA decreased NOS2 expression.

Conclusion

EPA seems to be more effective than DHA and EPA + DHA in modulating expression levels of selected inflammatory genes. The concentration of 50 μM was globally more effective than 10 μM.

Prostaglandin transporter (OATP2A1/SLCO2A1) contributes to local disposition of eicosapentaenoic acid-derived PGE3

Eicosapentaenoic acid (EPA)-derived prostaglandin E3 (PGE3) possesses an anti-inflammatory effect; however, information for transporters that regulate its peri-cellular concentration is limited. The present study, therefore, aimed to clarify transporters involved in local disposition of PGE3. PGE3 uptake was assessed in HEK293 cells transfected with OATP2A1/SLCO2A1, OATP1B1/SLCO1B1, OATP2B1/SLCO2B1, OAT1/SLC22A6, OCT1/SLC22A1 or OCT2/SLC22A2 genes, compared with HEK293 cells transfected with plasmid vector alone (Mock). PGE3 uptake by OATP2A1-expressing HEK293 cells (HEK/2A1) was the highest and followed by HEK/1B1, while no significantly higher uptake of PGE3 than Mock cells was detected by other transporters. Saturation kinetics in PGE3 uptake by HEK/2A1 estimated the Km as 7.202 ± 0.595 μM, which was 22 times higher than that of PGE2 (Km=0.331 ± 0.131 μM). Furthermore, tissue disposition of PGE3 was examined in wild-type (WT) and Slco2a1-deficient (Slco2a1(-/-)) mice after oral administration of EPA ethyl ester (EPA-E) when they underwent intraperitoneal injection of endotoxin (e.g., lipopolysaccharide). PGE3 concentration was significantly higher in the lung, and tended to increase in the colon, stomach, and kidney of Slco2a1(-/-), compared to WT mice. Ratio of PGE2 metabolite 15-keto PGE2 over PGE2 concentration was significantly lower in the lung and colon of Slco2a1(-/-) than that of WT mice, suggesting that PGE3 metabolism is downregulated in Slco2a1(-/-) mice. In conclusion, PGE3 was found to be a substrate of OATP2A1, and local disposition of PGE3 could be regulated by OATP2A1 at least in the lung.

Analgesia enhancement and prevention of tolerance to morphine: beneficial effects of combined therapy with omega-3 fatty acids

Objectives

Recent evidence associates omega-3 fatty acids (O3) with pain reduction. The aim of this work was to evaluate the antinociceptive effect of O3, either alone or in combination with morphine after acute and chronic administration in rats. As well, a new pharmaceutical mixture that allows the concomitant administration of O3 and morphine as an oral solution was developed.

Methods

Animals were fed on a control or an experimental diet supplemented with O3. They were subjected to the hot-plate test to assess analgesic effect and tolerance to the analgesic effect of morphine. The open-field test was carried out to determine if the differences in the response latency can be related to non-specific sedative effects.

Key findings

O3 dietary supplementation increased the response latency compared with the control group. Acute treatment with morphine in these groups resulted in an additive antinociceptive effect not related to locomotor activity. Chronic coadministration of morphine with O3 attenuated the development of tolerance. Oral administration of the new pharmaceutical mixture showed analgesic activity with a subtherapeutic dose of morphine.

Conclusion

This finding suggests a role for O3 as adjuncts to opioids in pain therapy and might contribute to the reduction of the occurrence of morphine side-effects.

Randomized Multicenter Placebo-Controlled Trial of Omega-3 Fatty Acids for the Control of Aromatase Inhibitor-Induced Musculoskeletal Pain: SWOG S0927

PURPOSE

Musculoskeletal symptoms are the most common adverse effects of aromatase inhibitors (AIs) and can result in decreased quality of life and discontinuation of therapy. Omega-3 fatty acids (O3-FAs) can be effective in decreasing arthralgia resulting from rheumatologic conditions and reducing serum triglycerides.

PATIENTS AND METHODS

Women with early-stage breast cancer receiving an AI who had a worst joint pain/stiffness score ≥ 5 of 10 using the Brief Pain Inventory-Short Form (BPI-SF) were randomly assigned to receive either O3-FAs 3.3 g or placebo (soybean/corn oil) daily for 24 weeks. Clinically significant change was defined as ≥ 2-point drop from baseline. Patients also completed quality-of-life (Functional Assessment of Cancer Therapy-Endocrine Symptoms) and additional pain/stiffness assessments at baseline and weeks 6, 12, and 24. Serial fasting blood was collected for lipid analysis.

RESULTS

Among 262 patients registered, 249 were evaluable, with 122 women in the O3-FA arm and 127 in the placebo arm. Compared with baseline, the mean observed BPI-SF score decreased by 1.74 points at 12 weeks and 2.22 points at 24 weeks with O3-FAs and by 1.49 and 1.81 points, respectively, with placebo. In a linear regression adjusting for the baseline score, osteoarthritis, and taxane use, adjusted 12-week BPI-SF scores did not differ by arm (P = .58). Triglyceride levels decreased in patients receiving O3-FA treatment and remained the same for those receiving placebo (P = .01). No between-group differences were seen for HDL, LDL, or C-reactive protein.

CONCLUSION

We found a substantial (> 50%) and sustained improvement in AI arthralgia for both O3-FAs and placebo but found no meaningful difference between the groups.

An update on the role of omega-3 fatty acids on inflammatory and degenerative diseases

Inflammation is involved in the pathophysiology of many chronic diseases, such as rheumatoid arthritis and neurodegenerative diseases. Several studies have evidenced important anti-inflammatory and immunomodulatory properties of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). This review illustrates current knowledge about the efficacy of n-3 LC-PUFAs (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), particularly) in preventing and/or treating several chronic inflammatory conditions (inflammatory bowel diseases and rheumatoid arthritis) as well as their potential benefits on neurodegenerative diseases. It is well established that n-3 LC-PUFAs are substrates for synthesis of novel series of lipid mediators (e.g., resolvins, protectins, and maresins) with potent anti-inflammatory and pro-resolving properties, which have been proposed to partly mediate the protective and beneficial actions of n-3 LC-PUFAs. Here, we briefly summarize current knowledge from preclinical studies analyzing the actions of EPA- and DHA-derived resolvins and protectins on pathophysiological models of rheumatoid arthritis, Alzheimer, and irritable bowel syndrome.

Fatty acid-binding protein 7 regulates function of caveolae in astrocytes through expression of caveolin-1

Fatty acid-binding proteins (FABPs) bind and solubilize long-chain fatty acids, controlling intracellular lipid dynamics. FABP7 is expressed by astrocytes in the developing brain, and suggested to be involved in the control of astrocyte lipid homeostasis. In this study, we sought to examine the role of FABP7 in astrocytes, focusing on plasma membrane lipid raft function, which is important for receptor-mediated signal transduction in response to extracellular stimuli. In FABP7-knockout (KO) astrocytes, the ligand-dependent accumulation of Toll-like receptor 4 (TLR4) and glial cell-line-derived neurotrophic factor receptor alpha 1 into lipid raft was decreased, and the activation of mitogen-activated protein kinases and nuclear factor-κB was impaired after lipopolysaccharide (LPS) stimulation when compared with wild-type astrocytes. In addition, the expression of caveolin-1, not cavin-1, 2, 3, caveolin-2, and flotillin-1, was found to be decreased at the protein and transcriptional levels. FABP7 re-expression in FABP7-KO astrocytes rescued the decreased level of caveolin-1. Furthermore, caveolin-1-transfection into FABP7-KO astrocytes significantly increased TLR4 recruitment into lipid raft and tumor necrosis factor-α production after LPS stimulation. Taken together, these data suggest that FABP7 controls lipid raft function through the regulation of caveolin-1 expression and is involved in the response of astrocytes to the external stimuli. GLIA 2015;63:780-794.

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".