Fish oil suppressed cytokines and nuclear factor-kappaB induced by murine AIDS virus infection

Hematological parameters, antioxidant status, and gene expression of γ-INF and IL-1β in vaccinated lambs fed different type of lipids

This study was aimed to evaluate the effects of vegetable oils as calcium salt on immune responses and the expression of immune-related genes in vaccinated lambs. Twenty-four lambs (35 kg body weight, 6 months old) were assigned to four treatments with six replicates in a completely randomized design for 40 days. Four concentrates were formulated in which the calcium salts of palm oil, canola oil, corn oil, and flaxseed oil were used. On day 30 of the experiment, lambs were vaccinated by a dose of foot-and-mouth disease virus. The blood samples were collected from jugular vein 10 days after vaccination. The level of malondialdehyde and the activity of liver enzymes were the highest in lambs receiving corn oil and the lowest in lambs receiving flaxseed oil. The highest lymphocytes and the lowest neutrophil percentages were observed in lambs receiving flaxseed oil. There was a significant difference among treatments for the relative genes expression. Flaxseed oil significantly upregulated interferon-γ and corn oil upregulated interleukin-1β. The highest titer against foot-and-mouth disease virus was related to lambs receiving flaxseed oil, and the lowest titer was related to lambs that received corn oil. Flaxseed oil had more beneficial effects on immune response than other oils.

N-3 Polyunsaturated Fatty Acids and Their Lipid Mediators as A Potential Immune-Nutritional Intervention: A Molecular and Clinical View in Hepatic Disease and Other Non-Communicable Illnesses

In recent years, the beneficial effect of n-3 polyunsaturated fatty acids (n-3 PUFAs) intake on human health has been widely accepted in the field of immunonutrition. Today, we find a diversity of supplements based on n-3 PUFAs and/or minerals, vitamins and other substances. The main objective of this review is to discuss the importance of n-3 PUFAs and their derivatives on immunity and inflammatory status related to liver disease and other non-communicable illnesses. Based on the burden of liver diseases in 2019, more than two million people die from liver pathologies per year worldwide, because it is the organ most exposed to agents such as viruses, toxins and medications. Consequently, research conducted on n-3 PUFAs for liver disease has been gaining prominence with encouraging results, given that these fatty acids have anti-inflammatory and cytoprotective effects. In addition, it has been described that n-3 PUFAs are converted into a novel species of lipid intermediaries, specialized pro-resolving mediators (SPMs). At specific levels, SPMs improve the termination of inflammation as well as the repairing and regeneration of tissues, but they are deregulated in liver disease. Since evidence is still insufficient to carry out pharmacological trials to benefit the resolution of acute inflammation in non-communicable diseases, there remains a call for continuing preclinical and clinical research to better understand SPM actions and outcomes.

Inflammation and intestinal leakiness in older HIV+ individuals with fish oil treatment

Fish oil is a natural product that has shown efficacy for managing inflammatory conditions with few side effects. There is emerging evidence that crosstalks between gut epithelial cells and immune cells contribute to chronic infectious diseases. HIV-infected (HIV+) older adults show age-related co-morbidities at a younger age than their uninfected counterparts. Persistent inflammation related to the chronic viral infection and its sequelae is thought to contribute to this disparity. However, little is known about whether fish oil reduces intestinal inflammation in HIV + patients. We measure inflammation and gut barrier function in HIV + older adults (median age = 52, N = 33), following 12 weeks of fish oil supplementation (a total daily dose of 1.6 g of omega-3 fatty acids). We showed a reduction in inflammation and gut permeability as measured by CD14, inflammatory cytokines, lipopolysaccharide, and lipopolysaccharide binding protein. The results indicate that older HIV + adults may benefit from a diet supplemented with the omega-3 fatty acids found in fish oil.

Responses of growth performance and proinflammatory cytokines expression to fish oil supplementation in lactation sows' and/or weaned piglets' diets

The study was conducted to investigate whether dietary fish oil could influence growth of piglets via regulating the expression of proinflammatory cytokines. A split-plot experimental design was used with sow diet effect in the main plots and differing piglet diet effect in the subplot. The results showed that suckling piglets from fish oil fed dams grew rapidly (P < 0.05) than control. It was also observed that these piglets had higher ADG, feed intake, and final body weight (P < 0.05) during postweaning than those piglets from lard fed dams. Furthermore, there was a significant decrease (P < 0.01) in the expression of interleukin 6 and tumor necrosis factor- α in longissimus dorsi muscle. In contrast, there was a tendency (P < 0.10) towards lower ADG and higher feed:gain in weaned piglets receiving fish oil compared with those receiving lard. Meanwhile, splenic proinflammatory cytokines expression was increased (P < 0.01) in piglets receiving fish oil during postweaning period. The results suggested that 7% fish oil addition to sows' diets alleviated inflammatory response via decreasing the proinflammatory cytokines expression in skeletal muscle and accelerated piglet growth. However, 7% fish oil addition to weaned piglets' diets might decrease piglet growth via increasing splenic proinflammatory cytokines expression.

Mechanisms of action of (n-3) fatty acids

(n-3) PUFA are a family of biologically active fatty acids. The simplest member of this family, α-linolenic acid, can be converted to the more biologically active very long-chain (n-3) PUFA EPA and DHA; this process occurs by a series of desaturation and elongation reactions, with stearidonic acid being an intermediate in the pathway. Biological activity of α-linolenic and stearidonic acids most likely relates to their conversion to EPA. The very long-chain (n-3) PUFA have a range of physiological roles that relate to optimal cell membrane structure and optimal cell function and responses. Thus, (n-3) PUFA play a key role in preventing, and perhaps treating, many conditions of poor health and well-being. The multiple actions of (n-3) PUFA appear to involve multiple mechanisms that connect the cell membrane, the cytosol, and the nucleus. For some actions, (n-3) PUFA appear to act via receptors or sensors, so regulating signaling processes that influence patterns of gene expression. Some effects of (n-3) PUFA seem to involve changes in cell membrane fatty acid composition. Changing membrane composition can in turn affect membrane order, formation of lipid rafts, intracellular signaling processes, gene expression, and the production of both lipid and peptide mediators. Under typical Western dietary conditions, human cells tend to have a fairly high content of the (n-6) fatty acid arachidonic acid. Increased oral intake of EPA and DHA modifies the content of arachidonic acid as well as of EPA and DHA. Arachidonic acid is the substrate for eicosanoids involved in physiology and pathophysiology. The eicosanoids produced from EPA frequently have properties that are different from those that are produced from arachidonic acid. EPA and DHA are also substrates for production of resolvins and protectins, which seem to be biologically extremely potent. Increasing the contents of EPA and DHA in membranes modifies the pattern of production of these different lipid mediators.

Omega-3 fatty acids and inflammatory processes

Long chain fatty acids influence inflammation through a variety of mechanisms; many of these are mediated by, or at least associated with, changes in fatty acid composition of cell membranes. Changes in these compositions can modify membrane fluidity, cell signaling leading to altered gene expression, and the pattern of lipid mediator production. Cell involved in the inflammatory response are typically rich in the n-6 fatty acid arachidonic acid, but the contents of arachidonic acid and of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered through oral administration of EPA and DHA. Eicosanoids produced from arachidonic acid have roles in inflammation. EPA also gives rise to eicosanoids and these often have differing properties from those of arachidonic acid-derived eicosanoids. EPA and DHA give rise to newly discovered resolvins which are anti-inflammatory and inflammation resolving. Increased membrane content of EPA and DHA (and decreased arachidonic acid content) results in a changed pattern of production of eicosanoids and resolvins. Changing the fatty acid composition of cells involved in the inflammatory response also affects production of peptide mediators of inflammation (adhesion molecules, cytokines etc.). Thus, the fatty acid composition of cells involved in the inflammatory response influences their function; the contents of arachidonic acid, EPA and DHA appear to be especially important. The anti-inflammatory effects of marine n-3 PUFAs suggest that they may be useful as therapeutic agents in disorders with an inflammatory component.

Fatty acids and immune function: relevance to inflammatory bowel diseases

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

Therapeutic potential of n-3 polyunsaturated fatty acids in disease

PURPOSE

The potential therapeutic benefits of supplementation with n-3 polyunsaturated fatty acids (PUFAs) in various diseases are reviewed, and the antiinflammatory actions, activity, and potential drug interactions and adverse effects of n-3 PUFAs are discussed.

SUMMARY

Fish oils are an excellent source of long-chain n-3 PUFAs, such as eicosapentaenoic acid and docosahexaenoic acid. After consumption, n-3 PUFAs can be incorporated into cell membranes and reduce the amount of arachidonic acid available for the synthesis of proinflammatory eicosanoids (e.g., prostaglandins, leukotrienes). Likewise, n-3 PUFAs can also reduce the production of inflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1, and interleukin-6. Considerable research has been conducted to evaluate the potential therapeutic effects of fish oils in numerous conditions, including arthritis, coronary artery disease, inflammatory bowel disease, asthma, and sepsis, all of which have inflammation as a key component of their pathology. Additional investigations into the use of supplementation with fish oils in patients with neural injury, cancer, ocular diseases, and critical illness have recently been conducted. The most commonly reported adverse effects of fish oil supplements are a fishy aftertaste and gastrointestinal upset. When recommending an n-3 PUFA, clinicians should be aware of any possible adverse effect or drug interaction that, although not necessarily clinically significant, may occur, especially for patients who may be susceptible to increased bleeding (e.g., patients taking warfarin).

CONCLUSION

The n-3 PUFAs have been shown to be efficacious in treating and preventing various diseases. The wide variation in dosages and formulations used in studies makes it difficult to recommend dosages for specific treatment goals.

Duration of feeding linseed diet influences expression of inflammation-related genes and growth performance of growing-finishing barrows

The aim of the study was to investigate the effects of dietary linseed (rich in n-3 PUFA) on expression of inflammation-related genes and on growth performance of growing-finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, one as the basal diet and the other containing 10% linseed. Twenty-four Landrace x Yorkshire barrows weighing 35 +/- 3.7 kg were randomly assigned to 1 of 4 treatment groups, with 6 pigs per group. During the entire experimental period of 90 d, these 4 groups of pigs were first fed the basal diet and then fed the linseed diet for 0, 30, 60, and 90 d before slaughter, respectively. Pig growth; messenger RNA (mRNA) expression of peroxisome proliferator-activated receptor-gamma (PPARgamma), IL-1beta0, IL-6, and tumor necrosis factor-alpha (TNF-alpha); and plasma concentrations of the 3 proinflammatory cytokines were measured and analyzed. Average daily feed intake did not differ among treatment groups (P > 0.05), but ADG (P < 0.05) and G:F (P < 0.01) responded quadratically to the duration of linseed diet feeding, and pigs in the 60-d treatment group had the greatest ADG and G:F. The mRNA expression of PPARgamma in loin muscle and spleen increased linearly (P < 0.01) with the duration of linseed diet feeding, whereas its expression in adipose tissue was not affected (P = 0.095). Tumor necrosis factor-alpha and IL-6 mRNA expression in muscle, adipose, and spleen, as well as serum concentration of TNF-alpha, decreased linearly (P < 0.01) with the duration of linseed diet feeding. Peroxisome proliferator-activated receptor-gamma mRNA abundance was negatively correlated with IL-1beta, IL-6, and TNF-alpha mRNA abundance both in muscle (R(2) = 0.63, P < 0.001) and in spleen (R(2) = 0.69, P < 0.001), and PPARgamma mRNA expression in spleen (R(2) = 0.59, P < 0.01) and muscle (R(2) = 0.52, P < 0.05) was negatively correlated with serum TNF-alpha concentration. There were also significant quadratic relations between ADG and expression of PPARgamma (P < 0.05) and splenic TNF-alpha (P < 0.05). These data suggest that intake of n-3 PUFA from the linseed diet led to significant decreases in the expression of proinflammatory cytokine genes, which may stimulate growth in growing-finishing barrows, at least in part, through a PPARgamma-dependent mechanism.

Use of fish oil in parenteral nutrition: Rationale and reality

Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury and infection in some individuals and can lead, progressively, to sepsis and septic shock. The hyperinflammation is characterised by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids and other inflammatory mediators, while the immunosuppression is characterised by impairment of antigen presentation and of T-helper lymphocyte type-1 responses. Long-chain n-3 fatty acids from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid substrate and by inhibiting arachidonic acid metabolism) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, long-chain n-3 fatty acids are potentially useful anti-inflammatory agents and may be of benefit in patients at risk of hyperinflammation and sepsis. As a consequence, an emerging application for n-3 fatty acids, in which they may be added to parenteral (or enteral) formulas, is in surgical or critically-ill patients. Parenteral nutrition that includes n-3 fatty acids appears to preserve immune function better than standard formulas and appears to diminish the extent of the inflammatory response. Studies to date are suggestive of clinical benefits from these approaches, especially in patients post surgery, although evidence of clinical benefit in patients with sepsis is emerging.

n-3 fatty acids, inflammation, and immunity--relevance to postsurgical and critically ill patients

Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury, and infection in some individuals and these can lead, progressively, to sepsis and septic shock. The hyperinflammation is characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids, and other inflammatory mediators, while the immunosuppression is characterized by impairment of antigen presentation and of T helper cell type-1 responses. Long-chain n−3 FA from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid substrate and by inhibiting arachidonic acid metabolism) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, long-chain n−3 FA are potentially useful anti-inflammatory agents and may be of benefit in patients at risk of developing sepsis. As such, an emerging application of n−3 FA is in surgical or critically ill patients where they may be added to parenteral or enteral formulas. Parenteral or enteral nutrition including n−3 FA appears to preserve immune function better than standard formulas and appears to partly prevent some aspects of the inflammatory response. Studies to date are suggestive of clinical benefits from these approaches, especially in postsurgical patients.

Eicosapentaenoic acid prevents lipopolysaccharide-stimulated DNA binding of activator protein-1 and c-Jun N-terminal kinase activity

Activator protein-1 (AP-1) is a transcription factor that plays an important role in regulating the expression of proinflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha). Many studies have shown that fish oil supplementation inhibits TNF-alpha production in mice and humans; however, the mechanisms remain unclear. In this study, the effects of eicosapentaenoic acid (EPA), a major n-3 fatty acid in fish oil, on lipopolysaccharide (LPS)-stimulated activation of AP-1 were investigated in human monocytic THP-1 cells. The results demonstrated that AP-1 DNA binding activity stimulated by LPS was suppressed by preincubating cells with EPA. Lipopolysaccharide-stimulated increase of c-Jun and c-Fos protein levels was also attenuated by EPA pretreatment. In addition, EPA pretreatment decreased LPS-induced c-Jun phosphorylation and c-Jun N-terminal kinase (JNK) activation. The results suggest that suppression of TNF-alpha expression by EPA may be partly mediated by its inhibitory effect on AP-1 activation.

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

BACKGROUND

Many studies have shown that fish oil supplementation inhibits tumor necrosis factor-alpha (TNF-alpha) production in mice and human subjects; however, the mechanisms remain unclear. Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an important role in controlling the expression of pro-inflammatory genes including TNF-alpha. Activation of NF-kappaB has been shown to mediate the maximal expression of TNF-alpha in human monocytes. NF-kappaB is kept in an inactive form in the cytoplasm by IkappaB, the inhibitory subunit of NF-kappaB complex. Phosphorylation and subsequent degradation of IkappaB lead to NF-kappaB activation.

OBJECTIVES

The effect of eicosapentaenoic acid (EPA), a major n-3 fatty acid in fish oil, on the lipopolysaccharide (LPS)-induced expression of TNF-alpha and activation of NF-kappaB were investigated. The mechanism underlying EPA modulation of NF-kappaB activation was also studied.

METHODS

Human monocytic THP-1 cells were pre-incubated with EPA and stimulated with LPS. The levels of secreted TNF-alpha were determined by ELISA. The DNA binding activity of NF-kappaB was analyzed by EMSA. The degradation and phosphorylation of IkappaB-alpha were examined by Western blot analysis.

RESULTS

TNF-alpha production and expression induced by LPS were significantly decreased in cells pre-incubated with EPA. LPS-induced NF-kappaB activation, translocation of p65 subunit to the nucleus, phosphorylation and degradation of IkappaB-alpha were partially prevented by EPA.

CONCLUSIONS

The results suggest that suppression of the TNF-alpha expression by EPA is partly attributed to its inhibitory effect on NF-kappaB activation. EPA appears to prevent NF-kappaB activation by preventing the phosphorylation of IkappaB-alpha.

N-3 polyunsaturated fatty acids and inflammation: from molecular biology to the clinic

The immune system is involved in host defense against infectious agents, tumor cells, and environmental insults. Inflammation is an important component of the early immunologic response. Inappropriate or dysfunctional immune responses underlie acute and chronic inflammatory diseases. The n-6 PUFA arachidonic acid (AA) is the precursor of prostaglandins, leukotrienes, and related compounds that have important roles in inflammation and in the regulation of immunity. Feeding fish oil results in partial replacement of AA in cell membranes by EPA. This leads to decreased production of AA-derived mediators, through several mechanisms, including decreased availability of AA, competition for cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, and decreased expression of COX-2 and 5-LOX. This alone is a potentially beneficial anti-inflammatory effect of n-3 FA. However, n-3 FA have a number of other effects that might occur downstream of altered eicosanoid production or might be independent of this effect. For example, dietary fish oil results in suppressed production of proinflammatory cytokines and can modulate adhesion molecule expression. These effects occur at the level of altered gene expression. Fish oil feeding has been shown to ameliorate the symptoms of some animal models of autoimmune disease and to protect against the effects of endotoxin. Clinical studies have reported that oral fish oil supplementation has beneficial effects in rheumatoid arthritis and among some asthmatics, supporting the idea that the n-3 FA in fish oil are anti-inflammatory. There are indications that the inclusion of fish oil in enteral and parenteral formulae is beneficial to patients.

Dietary modification of inflammation with lipids

The n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in high proportions in oily fish and fish oils. The n-3 PUFA are structurally and functionally distinct from the n-6 PUFA. Typically, human inflammatory cells contain high proportions of the n-6 PUFA arachidonic acid and low proportions of n-3 PUFA. The significance of this difference is that arachidonic acid is the precursor of 2-series prostaglandins and 4-series leukotrienes, which are highly-active mediators of inflammation. Feeding fish oil results in partial replacement of arachidonic acid in inflammatory cell membranes by EPA. This change leads to decreased production of arachidonic acid-derived mediators. This response alone is a potentially beneficial anti-inflammatory effect of n-3 PUFA. However, n-3 PUFA have a number of other effects which might occur downstream of altered eicosanoid production or might be independent of this activity. For example, animal and human studies have shown that dietary fish oil results in suppressed production of pro-inflammatory cytokines and can decrease adhesion molecule expression. These effects occur at the level of altered gene expression. This action might come about through antagonism of the effects of arachidonic acid-derived mediators or through more direct actions on the intracellular signalling pathways which lead to activation of transcription factors such as nuclear factor kappa B (NFB). Recent studies have shown that n-3 PUFA can down regulate the activity of the nuclear transcription factor NFB. Fish oil feeding has been shown to ameliorate the symptoms in some animal models of chronic inflammatory disease and to protect against the effects of endotoxin and similar inflammatory challenges. Clinical studies have reported that oral fish oil supplementation has beneficial effects in rheumatoid arthritis and among some patients with asthma, supporting the idea that the n-3 PUFA in fish oil are anti-inflammatory. There are indications that inclusion of n-3 PUFA in enteral and parenteral formulas might be beneficial to patients in intensive care or post-surgery.