Polyunsaturated fatty acids and inflammatory bowel disease

Cannabigerol as an anti-inflammatory agent altering the level of arachidonic acid derivatives in the colon tissue of rats subjected to a high-fat high-sucrose diet

Fat and sugar overconsumption is the cause of increasing worldwide incidence of gastrointestinal tract in inflammatory conditions. The intestinal pre-inflammatory alterations are partially reversible, simultaneously inhibiting the predisposition to colitis. Searching for an effective pharmacotherapy for treating inflammatory conditions in the intestine is essential. This study aimed to investigate the effect of cannabigerol (CBG) on the inflammation state in the colon tissue of rats subjected to high-caloric diet. The experiment was conducted on male Wistar rats subjected to a standard or a high-fat high-sucrose diets for six weeks. For the last 14 days, half of rats from both groups received intragastrically cannabigerol solution (30 mg/kg of body mass). The ratio of n-6/n-3 PUFA, the activity of n-6 and n-3 PUFA, and arachidonic acid (AA) content in selected lipid fractions were determined by gas-liquid chromatography. Immunoblotting examined the expression of proteins involved in inflammation development. ELISA kits measured the content of arachidonic acid derivatives. CBG treatment reduced the n-6/n-3 PUFA ratio in TAG fraction and increased the n-3 PUFA pathway activity in almost all lipid fractions. Cannabigerol supplementation decreased AA concentration in PL and TAG. CBG also caused diminishments in the expression of cPLA2, COX-1, COX-2, and 12/15-LOX, which was indirectly correlated with a decreased LTB4 level and an increased LXA4 level. We concluded that cannabigerol has a protective influence on the development of inflammation in the colon tissue under lipid and sugar overload condition, thereby favoring cancer initiation and progression.

The Effects of a High-Fat Diet on Inflammatory Bowel Disease

The interactions among diet, intestinal immunity, and microbiota are complex and play contradictory roles in inflammatory bowel disease (IBD). An increasing number of studies has shed light on this field. The intestinal immune balance is disrupted by a high-fat diet (HFD) in several ways, such as impairing the intestinal barrier, influencing immune cells, and altering the gut microbiota. In contrast, a rational diet is thought to maintain intestinal immunity by regulating gut microbiota. In this review, we emphasize the crucial contributions made by an HFD to the gut immune system and microbiota.

New translational and experimental insights into the role of pro-resolving lipid mediators in inflammatory bowel disease

The resolution of inflammation is an active process, guided by specialized pro-resolution lipid mediators (SPMs). These mediators originate from polyunsaturated fatty acids, such as omega-3. Sufficient evidence suggests that the beneficial effects attributed to omega-3 are, at least in part, the result of the immunomodulatory action of the SPMs, which act systemically by overcoming inflammation and repairing tissue damage, without suppressing the immune response. Recent studies suggest that an imbalance in the synthesis and/or activity of these compounds may be associated with the pathogenesis of several inflammatory conditions, such as inflammatory bowel disease (IBD). Thus, this review highlights the advances made in recent years with regard to the endo-genous synthesis and the biological role of lipoxins, resolvins, protectins, and maresins, as well as their precursors, in the regulation of inflammation; and provides an update on the participation of these mediators in the development and evolution of IBD and the therapeutic approaches that these immunomodulating substances are involved in this context.

Short-Chain Fatty Acids Produced by Ruminococcaceae Mediate α-Linolenic Acid Promote Intestinal Stem Cells Proliferation

SCOPE

The proliferation and differentiation of intestinal stem cells (ISCs) are the basis of intestinal renewal and regeneration, and gut microbiota plays an important role in it. Dietary nutrition has the effect of regulating the activity of ISCs; however, the regulation effect of α-linolenic acid (ALA) has seldom been reported.

METHODS AND RESULTS

After intervening mice with different doses of ALA for 30 days, it is found that ALA (0.5 g kg^-1 ) promotes small intestinal and villus growth by activating the Wnt/β-catenin signaling pathway to stimulate the proliferation of ISCs. Furthermore, ALA administration increases the abundance of the Ruminococcaceae and Prevotellaceae, and promotes the production of short-chain fatty acids (SCFAs). Subsequent fecal transplantation and antibiotic experiments demonstrate that ALA on the proliferation of ISCs are gut microbiota dependent, among them, the functional microorganism may be derived from Ruminococcaceae. Administration of isobutyrate shows a similar effect to ALA in terms of promoting ISCs proliferation. Furthermore, ALA mitigates 5-fluorouracil-induced intestinal mucosal damage by promoting ISCs proliferation.

CONCLUSION

These results indicate that SCFAs produced by Ruminococcaceae mediate ALA promote ISCs proliferation by activating the Wnt/β-catenin signaling pathway, and suggest the possibility of ALA as a prebiotic agent for the prevention and treatment of intestinal mucositis.

How To Stabilize ω-3 Polyunsaturated Fatty Acids (PUFAs) in an Animal Feeding Study?-Effects of the Temperature, Oxygen Level, and Antioxidant on Oxidative Stability of ω-3 PUFAs in a Mouse Diet

Substantial studies have shown that ω-3 polyunsaturated fatty acids (PUFAs) have various health-promoting effects; however, there are inconsistent results from animal studies that showed that ω-3 PUFAs have no effects or even detrimental effects. Emerging research suggests that oxidized ω-3 PUFAs have different effects compared to unoxidized ω-3 PUFAs; therefore, lipid oxidation of dietary ω-3 PUFAs could contribute to the mixed results of ω-3 PUFAs in animal studies. Here, we prepared an AIN-93G-based, semi-purified, powder diet, which is one of the most commonly used rodent diets in animal studies, to study the oxidative stability of fortified ω-3 PUFAs in animal feed. We found that lowering the storage temperature or the addition of a certain antioxidant, notably tert-butylhydroquinone (TBHQ), helps to stabilize ω-3 PUFAs and suppress ω-3 oxidation in the animal diet, while reducing the level of oxygen in the storage atmosphere is not very effective. The addition of 50 ppm of TBHQ in the diet inhibited 99.5 ± 0.1% formation of primary oxidation products and inhibited 96.1 ± 0.7% formation of secondary oxidation products, after 10 days of storage of the prepared diet at a typical animal-feeding experiment condition. Overall, our results highlight that ω-3 PUFAs are highly prone to lipid oxidation in a typical animal-feeding experiment, emphasizing the critical importance to stabilize ω-3 PUFAs in animal studies.

Efficacy of combined therapy with fish oil and phytocannabinoids in murine intestinal inflammation

Fish oil (FO) and phytocannabinoids have received considerable attention for their intestinal anti-inflammatory effects. We investigated whether the combination of FO with cannabigerol (CBG) and cannabidiol (CBD) or a combination of all three treatments results in a more pronounced intestinal antiinflammatory action compared to the effects achieved separately. Colitis was induced in mice by 2,4-dinitrobenzenesulfonic acid (DNBS). CBD and CBG levels were detected and quantified by liquid chromatography coupled with time of flight mass spectrometry and ion trap mass spectrometry (LC-MS-IT-TOF). Endocannabinoids and related mediators were assessed by LC-MS. DNBS increased colon weight/colon length ratio, myeloperoxidase activity, interleukin-1β, and intestinal permeability. CBG, but not CBD, given by oral gavage, ameliorated DNBS-induced colonic inflammation. FO pretreatment (at the inactive dose) increased the antiinflammatory action of CBG and rendered oral CBD effective while reducing endocannabinoid levels. Furthermore, the combination of FO, CBD, and a per se inactive dose of CBG resulted in intestinal anti-inflammatory effects. Finally, FO did not alter phytocannabinoid levels in the serum and in the colon. By highlighting the apparent additivity between phytocannabinoids and FO, our preclinical data support a novel strategy of combining these substances for the potential development of a treatment of inflammatory bowel disease.

Interventions of natural and synthetic agents in inflammatory bowel disease, modulation of nitric oxide pathways

Inflammatory bowel disease (IBD) refers to a group of disorders characterized by chronic inflammation of the gastrointestinal (GI) tract. The elevated levels of nitric oxide (NO) in serum and affected tissues; mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme; can exacerbate GI inflammation and is one of the major biomarkers of GI inflammation. Various natural and synthetic agents are able to ameliorate GI inflammation and decrease iNOS expression to the extent comparable with some IBD drugs. Thereby, the purpose of this study was to gather a list of natural or synthetic mediators capable of modulating IBD through the NO pathway. Electronic databases including Google Scholar and PubMed were searched from 1980 to May 2018. We found that polyphenols and particularly flavonoids are able to markedly attenuate NO production and iNOS expression through the nuclear factor κB (NF-κB) and JAK/STAT signaling pathways. Prebiotics and probiotics can also alter the GI microbiota and reduce NO expression in IBD models through a broad array of mechanisms. A number of synthetic molecules have been found to suppress NO expression either dependent on the NF-κB signaling pathway (i.e., dexamethasone, pioglitazone, tropisetron) or independent from this pathway (i.e., nicotine, prednisolone, celecoxib, β-adrenoceptor antagonists). Co-administration of natural and synthetic agents can affect the tissue level of NO and may improve IBD symptoms mainly by modulating the Toll like receptor-4 and NF-κB signaling pathways.

Extra-Virgin Olive Oil from Apulian Cultivars and Intestinal Inflammation

Inflammatory bowel disease (IBD) is a multifactorial intestinal disorder characterized by chronic intestinal inflammation. The etiology of IBD is still unclear, although genetic, environmental and host factors have been associated to the disease. Extra-virgin olive oil (EVO) is a central component of the Mediterranean diet and it decreases chronic inflammation by interfering with arachidonic acid and NF-κB signaling pathways. Specifically, the different components of EVO are able to confer advantages in terms of health in their site of action. For instance, oleic acid displays a protective effect in liver dysfunction and gut inflammation, whereas phenolic compounds protect colon cells against oxidative damage and improve the symptoms of chronic inflammation in IBD. Given the biological properties of EVO, we investigated whether its administration is able to confer protection in a mouse model of dextrane sodium sulfate (DSS)-induced colitis. Four EVO cultivars from the Apulian Region of Italy, namely Ogliarola (Cima di Bitonto), Coratina, Peranzana and Cima di Mola, respectively, were used. Administration of EVO resulted in reduced body weight loss in our colitis model. Furthermore, mice treated with Ogliarola, Coratina and Cima di Mola EVO displayed a reduction of rectal bleeding and IL-1β, TGFβ, IL-6 gene expression levels. Furthermore, Ogliarola, Coratina and Peranzana EVO administration ameliorated intestinal permeability and histopathological features of inflammation. Our data further validate the well-known positive effects of EVO supplementation in promoting human health and suggest the bona fide contribution of EVO in preventing onset and reducing progression of intestinal inflammation.

Randomized Study Design to Test Effects of Vitamin D and Omega-3 Fatty Acid Supplementation as Adjuvant Therapy in Colorectal Cancer Patients

This study examines the effects of vitamin D and omega-3 fatty acid co-supplementation on inflammation and nutritional status in colorectal cancer patients. Patients were randomly assigned into four groups: (1) controls, receiving placebos; (2) omega-3 fatty acid arm, receiving two 330 mg omega-3 fatty acid capsules daily and placebo (for vitamin D₃) weekly; (3) vitamin D arm, receiving a 50,000 IU vitamin D₃ soft gel weekly and two placebos (for omega-3 fatty acids) daily; and (4) co-supplementation arm, receiving a 50,000 IU vitamin D₃ soft gel weekly and two 330 mg omega-3 fatty acids capsules daily for 8 weeks. As outcomes, we measure height; weight; fat-free mass (FFM); serum levels of 25(OH)D, TNF-α, and IL-6; C-CRP; and albumin, before and after the intervention. The presented results show that vitamin D₃ plus omega-3 fatty acid co-supplementation in colorectal cancer patients has beneficial impacts on inflammation and nutritional status.

Evaluation of Pathway Activation for a Single Sample Toward Inflammatory Bowel Disease Classification

Since similar complex diseases are much alike in clinical symptoms, patients are easily misdiagnosed and mistreated. It is crucial to accurately predict the disease status and identify markers with high sensitivity and specificity for classifying similar complex diseases. Many approaches incorporating network information have been put forward to predict outcomes, but they are not robust because of their low reproducibility. Several pathway-based methods are robust and functionally interpretable. However, few methods characterize the disease-specific states of single samples from the perspective of pathways. In this study, we propose a novel framework, Pathway Activation for Single Sample (PASS), which utilizes the pathway information in a single sample way to better recognize the differences between two similar complex diseases. PASS can mainly be divided into two parts: for each pathway, the extent of perturbation of edges and the statistic difference of genes caused by a single disease sample are quantified; then, a novel method, named as an AUCpath, is applied to evaluate the pathway activation for single samples from the perspective of genes and their interactions. We have applied PASS to two main types of inflammatory bowel disease (IBD) and widely verified the characteristics of PASS. For a new patient, PASS features can be used as the indicators or potential pathway biomarkers to precisely diagnose complex diseases, discover significant features with interpretability and explore changes in the biological mechanisms of diseases.

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.

Effects of Vitamin D and Omega-3 Fatty Acids Co-Supplementation on Inflammatory Factors and Tumor Marker CEA in Colorectal Cancer Patients Undergoing Chemotherapy: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objectives: This study aimed to investigate the effects of vitamin D and omega-3 fatty acids co-supplementation on inflammatory factors and tumor marker CEA in colorectal cancer patients undergoing chemotherapy.Methods: In this study, 81 patients with stage ӀӀ or ӀӀӀ colorectal cancer were randomly assigned into four groups: (1) control: receiving a vitamin D placebo, weekly + two omega-3 fatty acid placebo capsules, daily; (2) omega-3 fatty acid, receiving two omega-3 fatty acid capsules (each capsule containing 330 mg of omega-3 fatty acids), daily + a vitamin D placebo, weekly; (3) vitamin D, receiving a 50,000 IU vitamin D soft gel, weekly + two omega-3 fatty acid placebo capsules, daily; (4) co-supplementation, receiving a 50,000 IU vitamin D soft gel, weekly + two omega-3 fatty acids capsules, for 8 weeks. Before and after the intervention, serum levels of 25(OH)D, TNF-α, IL-1β, IL-6, IL-8, NF-kB activity, and tumor marker CEA, were measured.Results: After 8 weeks of intervention, patients who received combined vitamin D and omega-3 fatty acids supplements compared with omega-3, vitamin D, and placebo had significantly decreased TNF-α, and IL-1β (P < .05). In addition, serum levels of TNF-α, IL-1β, IL-6, IL-8, and tumor marker CEA were decreased significantly in omega-3, vitamin D, and co-supplementation of them, compared with baseline. NF-kB activity was decreased significantly in vitamin D and co-supplementation groups, compared with baseline. Regarding CEA, there was no significant difference between the four groups at the end of intervention (P > .05).Conclusion: Results show that co-supplementation of vitamin D and omega-3 fatty acids co-supplementation, in colorectal cancer patients have beneficial impacts on inflammation and tumor marker CEA.

Effects of Fish n-3 PUFAs on Intestinal Microbiota and Immune System

Studies over several decades have documented the beneficial actions of n-3 polyunsaturated fatty acids (PUFAs), which are plentiful in fish oil, in different disease states. Mechanisms responsible for the efficacy of n-3 PUFAs include: (1) Reduction of triglyceride levels; (2) anti-arrhythmic and antithrombotic effects, and (3) resolution of inflammatory processes. The human microbiota project and subsequent studies using next-generation sequencing technology have highlighted that thousands of different microbial species are present in the human gut, and that there has been a significant variability of taxa in the microbiota composition among people. Several factors (gestational age, mode of delivery, diet, sanitation and antibiotic treatment) influence the bacterial community in the human gastrointestinal tract, and among these diet habits play a crucial role. The disturbances in the gut microbiota composition, i.e., gut dysbiosis, have been associated with diseases ranging from localized gastrointestinal disorders to neurologic, respiratory, metabolic, ocular, and cardiovascular illnesses. Many studies have been published about the effects of probiotics and prebiotics on the gut microbiota/microbioma. On the contrary, PUFAs in the gut microbiota have been less well defined. However, experimental studies suggested that gut microbiota, n-3 PUFAs, and host immune cells work together to ensure the intestinal wall integrity. This review discussed current evidence concerning the links among gut microbiota, n-3 PUFAs intake, and human inflammatory disease.

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.

ω-3 Polyunsaturated fatty acids and their cytochrome P450-derived metabolites suppress colorectal tumor development in mice

Many studies have shown that dietary intake of ω-3 polyunsaturated fatty acids (PUFAs) reduces the risks of colorectal cancer; however, the underlying mechanisms are not well understood. Here we used a LC-MS/MS-based lipidomics to explore the role of eicosanoid signaling in the anti-colorectal cancer effects of ω-3 PUFAs. Our results showed that dietary feeding of ω-3 PUFAs-rich diets suppressed growth of MC38 colorectal tumor, and modulated profiles of fatty acids and eicosanoid metabolites in C57BL/6 mice. Notably, we found that dietary feeding of ω-3 PUFAs significantly increased levels of epoxydocosapentaenoic acids (EDPs, metabolites of ω-3 PUFA produced by cytochrome P450 enzymes) in plasma and tumor tissue of the treated mice. We further showed that systematic treatment with EDPs (dose=0.5 mg/kg per day) suppressed MC38 tumor growth in mice, with reduced expressions of pro-oncogenic genes such as C-myc, Axin2, and C-jun in tumor tissues. Together, these results support that formation of EDPs might contribute to the anti-colorectal cancer effects of ω-3 PUFAs.

Epoxy fatty acids mediate analgesia in murine diabetic neuropathy

BACKGROUND

Neuropathic pain is a debilitating condition with no adequate therapy. The health benefits of omega-3 fatty acids are established, however, the role of docosahexaenoic acid (DHA) in limiting pain has only recently been described and the mechanisms of this action remain unknown. DHA is metabolized into epoxydocosapentanoic acids (EDPs) via cytochrome P450 (CYP450) enzymes which are substrates for the soluble epoxide hydrolase (sEH) enzyme. Here, we tested several hypotheses; first, that the antinociceptive action of DHA is mediated by the EDPs. Second, based on evidence that DHA and CYP450 metabolites elicit analgesia through opioid signalling, we investigated this as a possible mechanism of action. Third, we tested whether the analgesia mediated by epoxy fatty acids had similar rewarding effects as opioid analgesics.

METHODS

We tested diabetic neuropathic wild-type and sEH null mice in a conditioned place preference assay for their response to EDPs, sEHI and antagonism of these treatments with naloxone, a mu-opioid receptor antagonist.

RESULTS

The EDPs and sEH inhibitors were efficacious against chronic pain, and naloxone antagonized the action of both EDPs and sEH inhibitors. Despite this antagonism, the sEH inhibitors lacked reward side effects differing from opioids.

CONCLUSIONS

The EpFA are analgesic against chronic pain differing from opioids which have limited efficacy in chronic conditions.

SIGNIFICANCE

EDPs and sEHI mediate analgesia in modelled chronic pain and this analgesia is blocked by naloxone. However, unlike opioids, sEHI are highly effective in neuropathic pain models and importantly lack rewarding side effects.

Food, nutrients and nutraceuticals affecting the course of inflammatory bowel disease

Inflammatory bowel diseases (ulcerative colitis; Crohn's disease) are debilitating relapsing inflammatory disorders affecting the gastrointestinal tract, with deleterious effect on quality of life, and increasing incidence and prevalence. Mucosal inflammation, due to altered microbiota, increased intestinal permeability and immune system dysfunction underlies the symptoms and may be caused in susceptible individuals by different factors (or a combination of them), including dietary habits and components. In this review we describe the influence of the Western diet, obesity, and different nutraceuticals/functional foods (bioactive peptides, phytochemicals, omega 3-polyunsaturated fatty acids, vitamin D, probiotics and prebiotics) on the course of IBD, and provide some hints that could be useful for nutritional guidance. Hopefully, research will soon offer enough reliable data to slow down the spread of the disease and to make diet a cornerstone in IBD therapy.

Serum Fatty Acids Are Correlated with Inflammatory Cytokines in Ulcerative Colitis

Background and Aims

Ulcerative colitis (UC) is associated with increased dietary intake of fat and n-6 polyunsaturated fatty acids (PUFA). Modification of fat metabolism may alter inflammation and disease severity. Our aim was to assess differences in dietary and serum fatty acid levels between control and UC subjects and associations with disease activity and inflammatory cytokines.

Methods

Dietary histories, serum, and colonic tissue samples were prospectively collected from 137 UC subjects and 38 controls. Both histologic injury and the Mayo Disease Activity Index were assessed. Serum and tissue cytokines were measured by Luminex assay. Serum fatty acids were obtained by gas chromatography.

Results

UC subjects had increased total fat and oleic acid (OA) intake, but decreased arachidonic acid (AA) intake vs controls. In serum, there was less percent saturated fatty acid (SFA) and AA, with higher monounsaturated fatty acids (MUFA), linoleic acid, OA, eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA) in UC. Tissue cytokine levels were directly correlated with SFA and inversely correlated with PUFA, EPA, and DPA in UC subjects, but not controls. 5-aminosalicylic acid therapy blunted these associations.

Conclusions

In summary, we found differences in serum fatty acids in UC subjects that correlated with pro-inflammatory tissue cytokines. We propose that fatty acids may affect cytokine production and thus be immunomodulatory in UC.

Dietary n-3 PUFA Protects Mice from Con A Induced Liver Injury by Modulating Regulatory T Cells and PPAR-γ Expression

Background

Dietary n-3 polyunsaturated fatty acids (PUFA) exert anti-inflammatory and immunoregulatory effects through down-regulating the innate and adoptive immune response. However, the effect of dietary n-3 PUFA on CD4⁺CD25⁺ regulatory T cells (Tregs) is unclear.

Aims

The current study was to examine the relationship between n-3 PUFA and Tregs as well as their immunoregulatory effect in immune-mediated liver injury.

Methods

The mice model feeding with n-3 PUFA-enriched diet was established and Tregs were analyzed. Effect of docosahexaenoic acid (DHA) on Tregs proliferation and induction was determined in vitro. The potential immunotherapeutic effect of dietary n-3 PUFA was investigated through Con A-induced hepatitis model.

Results

Long-term administration of dietary n-3 PUFA significantly increased hepatic Tregs and modulated their phenotype. n-3 PUFA or DHA directly increased natural Tregs (nTreg) proliferation but didn’t increase inducible Tregs (iTreg). In addition, the expression of peroxisome proliferator activated receptor gamma (PPAR-γ), transforming growth factor β (TGF-β) and interleukin (IL)-10 were significantly up-regulated in n-3 PUFA-enriched diet-fed mice. Finally, n-3 PUFA-enriched diet alleviated liver injury induced by Con A and down-regulated pro-inflammatory cytokines expression, accompanied by increased PPAR-γ expression.

Conclusion

Dietary n-3 PUFA enhanced Tregs generation through up-regulating PPAR-γ and TGF-β expression, and protected mice from Con A-induced liver injury. This finding provides a promising potential therapeutic method in treating inflammatory and autoimmune disease.

Dietary fish oil inhibits mechanical allodynia and thermal hyperalgesia in diabetic rats by blocking nuclear factor-κB-mediated inflammatory pathways

One of the most common complications of early-onset diabetes mellitus is peripheral diabetic neuropathy, which is manifested either by loss of nociception or by allodynia and hyperalgesia. Diabetes mellitus is a common metabolic disease in human beings with characteristic symptoms of hyperglycemia, chronic inflammation and insulin resistance. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown anti-inflammatory role in various experimental conditions. The present study investigated the effects of fish oil supplementation on the inflammation in the dorsal root ganglion (DRG) of streptozotocin (STZ)-induced diabetes rats. The effects of diabetes and fish oil treatment on the allodynia and hyperalgesia were also evaluated. Dietary fish oil effectively attenuated both allodynia and hyperalgesia induce by STZ injection. Along with the behavioral findings, DRG from fish oil-treated diabetic rats displayed a decrease in inflammatory cytokines and the expression of nuclear factor-κB (NF-κB) compared with untreated diabetic rats. Fish oil supplementation also increased the phosphorylation of AKT in DRG of diabetic rats. These results suggested that dietary fish oil-inhibited allodynia and hyperalgesia in diabetic rats may stem from its anti-inflammatory potential by regulating NF-κB and AKT. Fish oil might be useful as an adjuvant therapy for the prevention and treatment of diabetic complications.

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.

Eicosapentaenoic acid free fatty acid prevents and suppresses colonic neoplasia in colitis-associated colorectal cancer acting on Notch signaling and gut microbiota

Inflammatory bowel diseases are associated with increased risk of developing colitis-associated colorectal cancer (CAC). Epidemiological data show that the consumption of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) decreases the risk of sporadic colorectal cancer (CRC). Importantly, recent data have shown that eicosapentaenoic acid-free fatty acid (EPA-FFA) reduces polyp formation and growth in models of familial adenomatous polyposis. However, the effects of dietary EPA-FFA are unknown in CAC. We tested the effectiveness of substituting EPA-FFA, for other dietary fats, in preventing inflammation and cancer in the AOM-DSS model of CAC. The AOM-DSS protocols were designed to evaluate the effect of EPA-FFA on both initiation and promotion of carcinogenesis. We found that EPA-FFA diet strongly decreased tumor multiplicity, incidence and maximum tumor size in the promotion and initiation arms. Moreover EPA-FFA, in particular in the initiation arm, led to reduced cell proliferation and nuclear β-catenin expression, whilst it increased apoptosis. In both arms, EPA-FFA treatment led to increased membrane switch from ω-6 to ω-3 PUFAs and a concomitant reduction in PGE2 production. We observed no significant changes in intestinal inflammation between EPA-FFA treated arms and AOM-DSS controls. Importantly, we found that EPA-FFA treatment restored the loss of Notch signaling found in the AOM-DSS control and resulted in the enrichment of Lactobacillus species in the gut microbiota. Taken together, our data suggest that EPA-FFA is an excellent candidate for CRC chemoprevention in CAC.

[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.

Effect of dietary fat on intestinal inflammatory diseases

Dietary fat has multiple roles on human health, and some dietary fat is used to treat organic diseases because of its anti-inflammatory effect. It is commonly accepted that omega-3 polyunsaturated fatty acid (PUFA) is beneficial on ischemic heart disease or rheumatic arthritis. On the contrary, effect of omega-3-PUFA on Crohn's disease remained controversial. That effect of omega-3 PUFA differs according to the location of inflamed intestine was hypothesized. To elucidate this hypothesis, to investigate the role of dietary fat on disease activity in different kind of murine models of intestinal inflammatory diseases was planned. The effect of omega-3 PUFA on small intestinal Crohn's disease model and large intestinal Crohn's disease model of mice. Chronic colitis model C57BL/6 mice received two cycles of dextran sodium sulfate solution treatment to induce chronic colitis. Feeding of omega-3 fat-rich diets exacerbated colitis with decrease in adiponectin expression. Chronic small intestinal inflammation model: SAMP1/Yit mice showed remarkable inflammation of the terminal ileum spontaneously. Feeding of omega-3 fat-rich diets for 16 weeks significantly ameliorated the inflammation of the terminal ileum. Enhanced infiltration of leukocytes and expression of mucosal addressin cell adhesion molecule-1 in intestinal mucosa was significantly decreased by omega-3 fat-rich diets treatment. Omega-3 PUFA has dual role, pro-/anti-inflammatory, on intestinal inflammatory diseases. The role of omega-3 fat and the potential for immunonutrition in inflammatory conditions of the gastrointestinal tract will be discussed.

Dietary omega-3 polyunsaturated fatty acids alter the fatty acid composition of hepatic and plasma bioactive lipids in C57BL/6 mice: a lipidomic approach

Background

Omega (n)-3 polyunsaturated fatty acids (PUFA) are converted to bioactive lipid components that are important mediators in metabolic and physiological pathways; however, which bioactive compounds are metabolically active, and their mechanisms of action are still not clear. We investigated using lipidomic techniques, the effects of diets high in n-3 PUFA on the fatty acid composition of various bioactive lipids in plasma and liver.

Methodology and Principal Findings

Female C57BL/6 mice were fed semi-purified diets (20% w/w fat) containing varying amounts of n-3 PUFA before mating, during gestation and lactation, and until weaning. Male offspring were continued on their mothers’ diets for 16 weeks. Hepatic and plasma lipids were extracted in the presence of non-naturally occurring internal standards, and tandem electrospray ionization mass spectrometry methods were used to measure the fatty acyl compositions. There was no significant difference in total concentrations of phospholipids in both groups. However, there was a significantly higher concentration of eicosapentaenoic acid containing phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and cholesteryl esters (CE) (p < 0.01) in the high n-3 PUFA group compared to the low n-3 PUFA group in both liver and plasma. Plasma and liver from the high n-3 PUFA group also had a higher concentration of free n-3 PUFA (p < 0.05). There were no significant differences in plasma concentrations of different fatty acyl species of phosphatidylethanolamine, triglycerides, sphingomyelin and ceramides.

Conclusions/Significance

Our findings reveal for the first time that a diet high in n-3 PUFA caused enrichment of n-3 PUFA in PC, LPC, CE and free fatty acids in the plasma and liver of C57BL/6 mice. PC, LPC, and unesterified free n-3 PUFA are important bioactive lipids, thus altering their fatty acyl composition will have important metabolic and physiological roles.

The essentials of essential fatty acids

All fats, including saturated fatty acids, have important roles in the body. However, the most important fats are those that the body cannot make and thus must come from the food we eat. These essential fatty acids (EFAs) are based on linoleic acid (omega-6 group) and alpha-linolenic acid (omega-3 group). We need both groups of essential fatty acids to survive. For various reasons EFA deficiency is common in the general population, as is a disproportionate intake of omega-6 fatty acids over omega-3 fatty acids. As such, it is important to eat the right foods to make sure that you're taking in enough and the right kinds of the essential fatty acids. However, there is much more to the story. Studies have shown that increasing the intake of certain essential fatty acids, either alone or in combination with other fats and compounds, can increase health, help in treating certain diseases, and even improve body composition, mental and physical performance.

SOCS3 transactivation by PPARγ prevents IL-17-driven cancer growth

Activation of the transcription factor PPARγ by the n-3 fatty acid docosahexaenoic acid (DHA) is implicated in controlling proinflammatory cytokine secretion, but the intracellular signaling pathways engaged by PPARγ are incompletely characterized. Here, we identify the adapter-encoding gene SOCS3 as a critical transcriptional target of PPARγ. SOCS3 promoter binding and gene transactivation by PPARγ was associated with a repression in differentiation of proinflammatory T-helper (TH)17 cells. Accordingly, TH17 cells induced in vitro displayed increased SOCS3 expression and diminished capacity to produce interleukin (IL)-17 following activation of PPARγ by DHA. Furthermore, naïve CD4 T cells derived from mice fed a DHA-enriched diet displayed less capability to differentiate into TH17 cells. In two different mouse models of cancer, DHA prevented tumor outgrowth and angiogenesis in an IL-17-dependent manner. Altogether, our results uncover a novel molecular pathway by which PPARγ-induced SOCS3 expression prevents IL-17-mediated cancer growth.

Long-chain PUFA supplementation in rural African infants: a randomized controlled trial of effects on gut integrity, growth, and cognitive development

BACKGROUND

Intestinal damage and malabsorption caused by chronic environmental enteropathy are associated with growth faltering seen in infants in less-developed countries. Evidence has suggested that supplementary omega-3 (n-3) long-chain PUFAs (LC-PUFAs) might ameliorate this damage by reducing gastrointestinal inflammation. LC-PUFA supplementation may also benefit cognitive development.

OBJECTIVE

We tested whether early n-3 LC-PUFA supplementation improves infant intestinal integrity, growth, and cognitive function.

DESIGN

A randomized, double-blind, controlled trial [200 mg DHA and 300 mg EPA or 2 mL olive oil/d for 6 mo] was conducted in a population of 172 rural Gambian infants aged 3-9 mo. The primary endpoints were anthropometric measures and gut integrity [assessed by using urinary lactulose:mannitol ratios (LMRs)]. Plasma fatty acid status, intestinal mucosal inflammation (fecal calprotectin), daily morbidity, and cognitive development (2-step means-end test and an attention assessment) were secondary endpoints.

RESULTS

PUFA supplementation resulted in a significant increase in plasma n-3 LC-PUFA concentrations (P < 0.001 for both DHA and EPA) and midupper arm circumference (MUAC) (effect size: 0.31 z scores; 95% CI: 0.06, 0.56; P = 0.017) at 9 mo of age. At 12 mo, MUAC remained greater in the intervention group, and we observed significant increases in skinfold thicknesses (P ≤ 0.022 for all). No other significant differences between treatment groups were detected for growth or LMRs at 9 mo or for secondary outcomes.

CONCLUSIONS

Fish-oil supplementation successfully increased plasma n-3 fatty acid status. However, in young, breastfed Gambian infants, the intervention failed to improve linear growth, intestinal integrity, morbidity, or selected measures of cognitive development. The trial was registered at www.isrctn.org as ISRCTN66645725.

Eicosapentenoic Acid Attenuates Allograft Rejection in an HLA-B27/EGFP Transgenic Rat Cardiac Transplantation Model

The development of an animal model bearing definite antigens is important to facilitate the evaluation and modulation of specific allo-antigen responses after transplantation. In the present study, heterotopic cardiac transplantation was performed from F344/EGFPTg and F344/HLA-B27Tg rats to F344 rats. The F344 recipients accepted the F344/EGFPTg transplants, whereas they rejected the cardiac tissue from the F344/HLA-B27Tg rats by 39.4 ± 6.5 days, due to high production of anti-HLA-B27 IgM- and IgG-specific antibodies. In addition, immunization of F344 rats with skin grafts from F344/HLA-B27Tg rats resulted in robust production of anti- HLA-B27 IgM and IgG antibodies and accelerated the rejection of a secondary cardiac allograft (7.4 ± 1.9 days). Of interest, the F344 recipients rejected cardiac grafts from double transgenic F344/HLA-B27&EGFPTg rats within 9.0 ± 3.2 days, and this was associated with a significant increase in the infiltration of lymphocytes by day 7, suggesting a role for cellular immune rejection. Eicosapentenoic acid (EPA), one of the ω-3 polyunsaturated fatty acids in fish oil, could attenuate the production of anti-HLA IgG antibodies and B-cell proliferation, significantly prolonging double transgenic F344HLA-B27&EGFPTg to F344 rat cardiac allograft survival (36.1 ± 13.6 days). Moreover, the mRNA expression in the grafts was assessed by quantitative reverse transcription polymerase chain reaction (qRT-PCR), revealing an increase in the expression of the HO-1, IL-10, TGF-β, IDO, and Foxp3 genes in the EPA-treated group. Hence, our data indicate that HLA-B27 and/or GFP transgenic proteins are useful for establishing a unique animal transplantation model to clarify the mechanism underlying the allogeneic cellular and humoral immune response, in which the transplant antigens are specifically presented. Furthermore, we also demonstrated that EPA was effective in the treatment of rat cardiac allograft rejection and may allow the development of novel immunomodulatory strategies for organ transplantation.

Alternative medicines as emerging therapies for inflammatory bowel diseases

Inflammatory bowel disease (IBD) can be divided into two major categories, ulcerative colitis (UC) and Crohn disease (CD). While the main cause(s) of IBD remain unknown, a number of interventional and preventive strategies have been proposed for use against CD and UC. Many reports have focused on the use of alternative natural medicines as potential therapeutic interventions in IBD patients with minimal side effects. While the use of alternative medicines may be effective in IBD patients that are refractory to corticosteroids or thiopurins, alternative treatment strategies are limited and require extensive clinical testing before being optimized for use in patients.

Partial replacement of ω-6 fatty acids with medium-chain triglycerides, but not olive oil, improves colon cytokine response and damage in experimental colitis

BACKGROUND

Soybean oil is rich in ω-6 fatty acids, which are associated with higher incidence and more severe cases of inflammatory bowel diseases. The authors evaluated whether partial replacement of soybean oil by medium-chain triglycerides (MCTs) or olive oil influenced the incidence and severity of experimental ulcerative colitis by using different parenteral lipid emulsions (LEs).

METHODS

Wistar rats (n = 40) were randomized to receive parenteral infusion of the following LE: 100% soybean oil (SO), 50% MCT mixed with 50% soybean oil (MCT/SO), 80% olive oil mixed with 20% soybean oil (OO/SO), or saline (CC). After 72 hours of infusion, acetic acid experimental colitis was induced. After 24 hours, colon histology and cytokine expression were analyzed.

RESULTS

SO was not significantly associated with overall tissue damage. MCT/SO was not associated with necrosis (P < .005), whereas OO/SO had higher frequencies of ulcer and necrosis (P < .005). SO was associated with increased expression of interferon-γ (P = .005) and OO/SO with increased interleukin (IL)-6 and decreased tumor necrosis factor-α expression (P < .05). MCT/SO appeared to decrease IL-1 (P < .05) and increase IL-4 (P < .001) expression.

CONCLUSIONS

Parenteral SO with high concentration of ω-6 fatty acids was not associated with greater tissue damage in experimental colitis. SO partial replacement with MCT/SO decreased the frequency of histological necrosis and favorably modulated cytokine expression in the colon; however, replacement with OO/SO had unfavorable effects.

Attenuation of colonic inflammation by partial replacement of dietary linoleic acid with α-linolenic acid in a rat model of inflammatory bowel disease

Increasing prevalence of inflammatory bowel disease may be due to imbalance in the intake of n-6 and n-3 PUFA in the diet. This study investigates the impact of varying ratios of dietary linoleic acid (LA, 18 : 2n-6) to α-linolenic acid (ALA, 18 : 3n-3) on the inflammatory response in dextran sulphate sodium (DSS)-induced colitis. Weanling male Sprague-Dawley rats were divided into five groups: a non-colitic group with a LA:ALA ratio of 215 (CON-215), and colitic groups with LA:ALA ratios of 215 (DSS-215), 50 (DSS-50), 10 (DSS-10) and 2 (DSS-2). Blends of groundnut, palmolein and linseed oils were used to provide varying LA:ALA ratios. All the rats were fed the respective experimental isoenergetic diets containing 10 % fat for 90 d and DSS was administered during the last 11 d. Colonic inflammation was evaluated by clinical, biochemical and histological parameters. The results showed attenuation of colitis in the DSS-2 group as evidenced by significant reductions in disease activity index, mucosal myeloperoxidase activity (P < 0·05), alkaline phosphatase activity (P < 0·01) and increase in colon length (P < 0·01) compared to the groups fed with higher ratios (DSS-215). This was accompanied by significant reductions in mucosal proinflammatory cytokines TNF-α (P < 0·01) and IL-1β (P < 0·01) and improvement in the histological score. Further, ALA supplementation increased long-chain (LC) n-3 PUFA and decreased LC n-6 PUFA in colon structural lipids. These data suggest that substitution of one-third of LA with ALA (LA:ALA ratio 2) mitigates experimental colitis by down-regulating proinflammatory mediators.

Immunomodulatory action of dietary fish oil and targeted deletion of intestinal epithelial cell PPARδ in inflammation-induced colon carcinogenesis

The ligand-activated transcription factor peroxisome proliferator-activated receptor (PPAR)-δ is highly expressed in colonic epithelial cells; however, the role of PPARδ ligands, such as fatty acids, in mucosal inflammation and malignant transformation has not been clarified. Recent evidence suggests that the anti-inflammatory/chemoprotective properties of fish oil (FO)-derived n-3 polyunsaturated fatty acids (PUFAs) may be partly mediated by PPARδ. Therefore, we assessed the role of PPARδ in modulating the effects of dietary n-3 PUFAs by targeted deletion of intestinal epithelial cell PPARδ (PPARδ(ΔIEpC)). Subsequently, we documented changes in colon tumorigenesis and the inflammatory microenvironment, i.e., local [mesenteric lymph node (MLN)] and systemic (spleen) T cell activation. Animals were fed chemopromotive [corn oil (CO)] or chemoprotective (FO) diets during the induction of chronic inflammation/carcinogenesis. Tumor incidence was similar in control and PPARδ(ΔIEpC) mice. FO reduced mucosal injury, tumor incidence, colonic STAT3 activation, and inflammatory cytokine gene expression, independent of PPARδ genotype. CD8(+) T cell recruitment into MLNs was suppressed in PPARδ(ΔIEpC) mice. Similarly, FO reduced CD8(+) T cell numbers in the MLN. Dietary FO independently modulated MLN CD4(+) T cell activation status by decreasing CD44 expression. CD11a expression by MLN CD4(+) T cells was downregulated in PPARδ(ΔIEpC) mice. Lastly, splenic CD62L expression was downregulated in PPARδ(ΔIEpC) CD4(+) and CD8(+) T cells. These data demonstrate that expression of intestinal epithelial cell PPARδ does not influence azoxymethane/dextran sodium sulfate-induced colon tumor incidence. Moreover, we provide new evidence that dietary n-3 PUFAs attenuate intestinal inflammation in an intestinal epithelial cell PPARδ-independent manner.

Clinical activity of patupilone in patients with pretreated advanced/metastatic colon cancer: results of a phase I dose escalation trial

Background:

New agents that are active in patients with metastatic colorectal cancer are needed. Patupilone (EPO906; epothilone B) is a novel microtubule-stabilising agent.

Methods:

Patients with advanced colon cancer who progressed after prior treatment regimens received intravenous patupilone (6.5–10.0 mg m^–2) once every 3 weeks by a 20-min infusion (20MI), 24-h continuous infusion (CI-1D) or 5-day intermittent 16-h infusion (16HI-5D). Adverse events (AEs), dose-limiting toxicities (DLTs), pharmacokinetics and anti-tumour activity were assessed.

Results:

Sixty patients were enrolled. The maximum tolerated dose (MTD) was not reached in the 20MI arm (n=31), as no DLTs were observed. Three patients in the CI-1D arm (n=26) experienced 1 DLT each at 7.5, 8.0 and 9.0 mg m^–2, but MTD was not reached. However, the prolonged 16HI-5D arm was terminated at 6.5 mg m^–2 after two of the three patients developed a DLT. Diarrhoea was the most common AE and DLT, with increased severity at the higher doses (9.0 and 10.0 mg m^–2). Grade 3 or 4 diarrhoea was observed in 11 (35%) of the patients in the 20MI arm, 4 (15%) of the patients in the CI-1D arm and 2 (67%) of the patients in the 16HI-5D arm. Patupilone activity was observed in the 20MI arm with a disease control rate of 58%, including four confirmed partial responses. The disease control rate in CI-1D arm was 39%.

Conclusion:

Patupilone given once every 3 weeks as a 20-min infusion had promising anti-tumour activity and manageable safety profile at doses that demonstrated therapeutic efficacy.

The role of nutrition in the etiology of inflammatory bowel disease

Many foods have been implicated in theories about the etiology of inflammatory bowel disease. While evidence has accumulated that nutritional factors as part of overall lifestyle changes may play a role in the growing incidence, no specific dietary recommendations except the promotion of breastfeeding can currently be given to decrease the risk of developing Crohn's disease or ulcerative colitis. For the treatment of Crohn's disease in children and adolescents, however, enteral feeding with a semi-elemental diet seems to be as effective as corticosteroids in inducing and maintaining remission. In the meta-analyses, advantages of one formula over the other are evened out, and more research is warranted into the anti-inflammatory properties of different nutrients, such as polyunsaturated fatty acids, butyrate, glutamine, and cytokines, such as transforming growth factors-beta. Unfortunately, for practical reasons, nutritional therapy remains underutilized, even though pediatric patients are most vulnerable to the harmful effects of nutrient deficiencies on growth, pubertal development, and bone health. There is hope that in the future the new field of nutrigenomics may enable physicians to more accurately tailor a specific diet to the patient genotype.

n-3 Fatty acids uniquely affect anti-microbial resistance and immune cell plasma membrane organization

It is now well established that dietary lipids are incorporated into macrophage and T-cell membrane microdomains, altering their structure and function. Within cell membranes, there are specific detergent-resistant domains in which key signal transduction proteins are localized. These regions are classified as "lipid rafts". Rafts are composed mostly of cholesterol and sphingolipids and therefore do not integrate well into the fluid phospholipid bilayers causing them to form microdomains. Upon cell activation, rafts compartmentalize signal-transducing molecules, thus providing an environment conducive to signal transduction. In this review, we discuss recent novel data describing the effects of n-3 PUFA on alterations in the activation and functions of macrophages and T-cells. We believe that the modifications in these two disparate immune cell types are linked by fundamentally similar changes in membrane lipid composition and transmembrane signaling functions. We conclude that the outcomes of n-3 PUFA-mediated immune cell alterations may be beneficial (e.g., anti-inflammatory) or detrimental (e.g., loss of microbial immunity) depending upon the cell type interrogated.

Possible involvement of β-endorphin in docosahexaenoic acid-induced antinociception

We have previously demonstrated that the n-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) has an antinociceptive effect on various pain stimuli in a naloxone-reversible manner. In the present study, the role of the endogenous opioid peptide β-endorphin in DHA-induced antinociception was examined. DHA-induced antinociception was abolished when mice were pretreated with the μ-opioid receptor antagonist β-funaltrexamine (β-FNA) and the δ-opioid receptor antagonist naltrindole, but not by the κ-opioid receptor antagonist nor-binaltorphimine (nor-BNI) in the acetic acid-induced writhing test. In the radioligand binding assay, DHA itself did not have affinity for μ- , δ- or κ-opioid receptors. On the other hand, the pretreatment of anti-β-endorphin antiserum inhibited DHA-induced antinociception. Furthermore, the intracerebroventricular injection of DHA dose-dependently reduced writhing behavior, and this effect was inhibited by d-Phe-Cys-Tyr-Orn-Thr-Pen-Thr-NH(2) (CTOP) and naltrindole, but not nor-BNI. β-endorphin-induced antinociception was inhibited by the pretreatment of β-FNA, but not naltrindole or nor-BNI, and its levels in plasma were increased by DHA treatment. These findings suggest that the induction of antinociception by DHA may partially involve the μ-opioid receptor via the release of β-endorphin.

Fish oil concentrate delays sensitivity to thermal nociception in mice

Fish oil has been used to alleviate pain associated with inflammatory conditions such as rheumatoid arthritis. The anti-inflammatory property of fish oil is attributed to the n-3 fatty acids docosahexaenoic acid and eicosapentaenoic acid. Contrarily, vegetable oils such as safflower oil are rich in n-6 fatty acids which are considered to be mediators of inflammation. This study investigates the effect of n-3 and n-6 fatty acids rich oils as dietary supplements on the thermally induced pain sensitivity in healthy mice. C57Bl/6J mice were fed diet containing regular fish oil, concentrated fish oil formulation (CFO) and safflower oil (SO) for 6 months. Pain sensitivity was measured by Plantar test and was correlated to the expression of acid sensing ion channels (ASICs), transient receptor potential vanilloid 1 (TRPV1) and c-fos in dorsal root ganglion cells. Significant delay in sensitivity to thermal nociception was observed in mice fed CFO compared to mice fed SO (p<0.05). A significant diminution in expression of ion channels such as ASIC1a (64%), ASIC13 (37%) and TRPV1 (56%) coupled with reduced expression of c-fos, a marker of neuronal activation, was observed in the dorsal root ganglion cells of mice fed CFO compared to that fed SO. In conclusion, we describe here the potential of fish oil supplement in reducing sensitivity to thermal nociception in normal mice.

Antinociceptive effects of docosahexaenoic acid against various pain stimuli in mice

Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid (n-3 PUFAs), is an essential polyunsaturated fatty acid in the central nervous system, and possesses many physiological functions in neurodegenerative diseases. Previously, there are some reports that n-3 PUFAs contribute to pain relief. As the antinociceptive effect of DHA alone has not been reported, this study examined the antinociceptive effect of DHA on various pain stimuli. To evaluate the antinociceptive effect of DHA on thermal and chemical nociception, we employed the tail flick test, acetic acid writhing test and formalin test in mice. DHA was orally administrated at 5, 15 and 25 mmol/kg at 30 min before measurement. DHA administration dose-dependently exerted an antinociceptive effect against thermal and chemical stimulation in comparison to the control olive oil administration. These effects of DHA were abolished when mice were pretreated with naloxone, an opioid receptor antagonist. These findings suggest that DHA has opiod receptor-mediated pain control activities, and may provide valuable information towards an advanced therapeutic approach for pain control.