Oxidized omega-3 fatty acids inhibit NF-kappaB activation via a PPARalpha-dependent pathway

Omacor, n-3 polyunsaturated fatty acid, attenuated albuminuria and renal dysfunction with decrease of SREBP-1 expression and triglyceride amount in the kidney of type II diabetic animals

BACKGROUND

We assumed that n-3 polyunsaturated fatty acid (n-3 PUFA) would attenuate the tissue dyslipidemic condition through suppression of sterol regulatory element-binding protein (SREBP-1) in the kidney and would prevent renal progression in diabetic animals.

METHODS

We gavaged Omacor, composed of docosahexaenoic acid and eicosapentaenoic acid, to db/db mice for 2 weeks (0.2 g/100 g/day). We measured the markers of renal function, triglyceride amount and expressions of SREBP-1, liver X-activated receptor alpha (LXRalpha), collagen IV and TGFbeta-1 in kidney lysate, and performed immunohistochemical staining for SREBP-1, desmin and WT-1 in the renal sections. We measured collagen IV in primary mesangial cells cultured with high glucose media (25 mM), both with and without a transient transfection of small interfering RNA (siRNA) SREBP-1.

RESULTS

Omacor decreased the concentration of serum free fatty acid, and the amount of renal triglyceride, which was associated with decreased expression of SREBP-1 in the kidney, albuminuria and renal dysfunction in db/db mice. Omacor attenuated the expansion of mesangial matrix and the expression of desmin, preserved the WT-1 positive cells, and inhibited the phosphorylation of nuclear factor kappaB in renal tissue. In mesangial cells cultured in high glucose media, the suppression of SREBP-1 expression decreased the collagen IV in the cells.

CONCLUSIONS

Our study results demonstrated that n-3 PUFA prevented renal progression with attenuation of SREBP-1 and reduction of triglyceride in the diabetic kidney. This suggests that the regulation of dyslipidemic signals in the kidney could be a possible mechanism by which PUFA preserves renal function in the diabetic condition.

Omega-3 polyunsaturated fatty acids ameliorate the severity of ileitis in the senescence accelerated mice (SAM)P1/Yit mice model

Clinical studies using omega-3 polyunsaturated fatty acids (omega3-PUFA) to Crohn's disease (CD) are conflicting. Beneficial effects of dietary omega3-PUFA intake in various experimental inflammatory bowel disease (IBD) models have been reported. However, animal models of large intestinal inflammation have been used in all previous studies, and the effect of omega3 fat in an animal model of small intestinal inflammation has not been reported. We hypothesized that the effects of omega3 fat are different between large and small intestine. The aim of this study was to determine whether the direct effect of omega3 fat is beneficial for small intestinal inflammation. Senescence accelerated mice (SAM)P1/Yit mice showed remarkable inflammation of the terminal ileum spontaneously. The numbers of F4/80-positive monocyte-macrophage cells as well as beta7-integrin-positive lymphocytes in the intestinal mucosa were increased significantly compared with those in the control mice (AKR-J mice). The area of mucosal addressin cell adhesion molecule-1 (MAdCAM-1)-positive vessels was also increased. The degree of expression levels of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6 and interferon (IFN)-gamma mRNA were increased significantly compared with those in the control mice. The feeding of two different kinds of omega3 fat (fish-oil-rich and perilla-oil-rich diets) for 16 weeks to SAMP1/Yit mice ameliorated inflammation of the terminal ileum significantly. In both the omega3-fat-rich diet groups, enhanced infiltration of F4/80-positive monocytes/macrophages in intestinal mucosa of SAMP1/Yit mice cells and the increased levels of MCP-1, IL-6 and IFN-gamma mRNA expression were ameliorated significantly compared with those in the control diet group. The results suggest that omega3 fat is beneficial for small intestinal inflammation by inhibition of monocyte recruitment to inflamed intestinal mucosa.

PPARs and the cardiovascular system

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone-receptor superfamily. Originally cloned in 1990, PPARs were found to be mediators of pharmacologic agents that induce hepatocyte peroxisome proliferation. PPARs also are expressed in cells of the cardiovascular system. PPAR gamma appears to be highly expressed during atherosclerotic lesion formation, suggesting that increased PPAR gamma expression may be a vascular compensatory response. Also, ligand-activated PPAR gamma decreases the inflammatory response in cardiovascular cells, particularly in endothelial cells. PPAR alpha, similar to PPAR gamma, also has pleiotropic effects in the cardiovascular system, including antiinflammatory and antiatherosclerotic properties. PPAR alpha activation inhibits vascular smooth muscle proinflammatory responses, attenuating the development of atherosclerosis. However, PPAR delta overexpression may lead to elevated macrophage inflammation and atherosclerosis. Conversely, PPAR delta ligands are shown to attenuate the pathogenesis of atherosclerosis by improving endothelial cell proliferation and survival while decreasing endothelial cell inflammation and vascular smooth muscle cell proliferation. Furthermore, the administration of PPAR ligands in the form of TZDs and fibrates has been disappointing in terms of markedly reducing cardiovascular events in the clinical setting. Therefore, a better understanding of PPAR-dependent and -independent signaling will provide the foundation for future research on the role of PPARs in human cardiovascular biology.

Polyunsaturated fatty acids down-regulate in vitro expression of the key intestinal cholesterol absorption protein NPC1L1: no effect of monounsaturated nor saturated fatty acids

Several transporter proteins regulate intestinal cholesterol absorption. Of these proteins, NPC1L1 is a major contributor to this process. Fatty acids (FAs) modulate cholesterol absorption by a mechanism that remains unknown. We evaluate the effect of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) on the expression of NPC1L1 and others proteins associated with cholesterol absorption (SR-BI, ABCG5, ABCG8, ABCA1, CAV-1, ANX-2) in human enterocytes in vitro. The role of SREBPs, PPARs, LXR and RXR in this process was also investigated. Caco-2/TC-7 enterocytes were incubated for 24 h with a wide range of concentrations of FA-bovine serum albumin (50-300 microM). Gene expression was analyzed by quantitative real-time PCR. The NPC1L1 protein present in enterocyte membranes was analyzed using Western blot. NPC1L1 mRNA levels were reduced 35-58% by the n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (P<.05). Linoleic acid (n-6), palmitic acid and oleic acid did not affect NPC1L1 mRNA expression. ABCA1 mRNA levels were reduced 44-70% by n-6 arachidonic acid and 43-55% by n-3 EPA (P<.05). LXR and LXR+RXR agonists decreased NPC1L1 mRNA expression by 28% and 57%, respectively (P<.05). A concentration of 200 microM of EPA and DHA decreased NPC1L1 protein expression in enterocyte membranes by 58% and 59%, respectively. We have demonstrated that the PUFAs n-3 EPA and DHA down-regulate NPC1L1 mRNA expression. In addition, PUFAs also down-regulate NPC1L1 protein expression in enterocyte membranes. LXR and RXR activation induced a similar repression effect. The lipid-lowering effect of n-3 PUFAs could be mediated in part by their action at the NPC1L1 gene level.

The inhibition of TNF-alpha-induced NF-kappaB activation by marine natural products

The deregulated activation of NF-kappaB is associated with cancer development and inflammatory diseases. With an aim to find new NF-kappaB inhibitors, we purified and characterized compounds from extracts of the Fijian sponge Rhabdastrella globostellata, the crinoid Comanthus parvicirrus, the soft corals Sarcophyton sp. nov. and Sinularia sp., and the gorgonian Subergorgia sp. after an initial screening of 266 extracts from different marine origins. Results obtained show that selected purified compounds had a cytotoxic effect on the human leukaemia cell line K562, inhibited both TNF-alpha-induced NF-kappaB-DNA binding as well as TNF-alpha-induced IkappaBalpha degradation and nuclear translocation of p50/p65. Furthermore, we observed the inhibition of NF-kappaB activation induced by an overexpression of IKKbeta. Interestingly, natural products inhibited IKKbeta kinase as well as the 26S proteasome proteolytic activity.

AMPA receptor-mediated cell death is reduced by docosahexaenoic acid but not by eicosapentaenoic acid in area CA1 of hippocampal slice cultures

Over the last decade, several studies have shown that high levels of polyunsaturated fatty acids (PUFAs) in the brain might limit neuronal damage in various pathological conditions. For example, in animal models of Alzheimer's disease, omega-3 type PUFAs such as docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids have been proposed to decrease both the cognitive and the cellular manifestations of premature ageing. The mechanisms by which they promote brain integrity remain to be established, and the experiments on cultured hippocampal slices described here examine the possibility that omega-3 fatty acids can modulate brain cell viability by interacting with glutamate receptors. We observed, by lactate dehydrogenase release and propidium iodide (PI) uptake, that excitotoxicity triggered by an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor agonist was markedly reduced in hippocampal slices treated with DHA. PI uptake experiments also revealed that neuroprotection by DHA was restricted to the hippocampal CA1 region and could not be reproduced by EPA or arachidonic acid, an omega-6 PUFA. Moreover, the beneficial effect of DHA was specific to AMPA receptor stimulation, insofar as the toxicity induced by N-methyl-D-aspartate or kainate receptor agonists was not diminished by DHA preincubation. Biotinylation experiments finally indicated that the neuroprotective actions of DHA could result from down-regulation of AMPA receptors in hippocampal membranes. This investigation thus provides the first indication that a beneficial outcome of DHA on the brain could derive from specific modulation of AMPA-mediated toxicity, reinforcing the notion that dietary DHA uptake might be useful in preventing neurodegenerative diseases.

Reduction in dietary omega-6 polyunsaturated fatty acids: eicosapentaenoic acid plus docosahexaenoic acid ratio minimizes atherosclerotic lesion formation and inflammatory response in the LDL receptor null mouse

Dietary very long chain omega (omega)-3 polyunsaturated fatty acids (PUFA) have been associated with reduced CVD risk, the mechanisms of which have yet to be fully elucidated. LDL receptor null mice (LDLr-/-) were used to assess the effect of different ratios of dietary omega-6 PUFA to eicosapentaenoic acid plus docosahexaenoic acid (omega-6:EPA+DHA) on atherogenesis and inflammatory response. Mice were fed high saturated fat diets without EPA and DHA (HSF omega-6), or with omega-6:EPA+DHA at ratios of 20:1 (HSF R=20:1), 4:1 (HSF R=4:1), and 1:1 (HSF R=1:1) for 32 weeks. Mice fed the lowest omega-6:EPA+DHA ratio diet had lower circulating concentrations of non-HDL cholesterol (25%, P<0.05) and interleukin-6 (IL-6) (44%, P<0.05) compared to mice fed the HSF omega-6 diet. Aortic and elicited peritoneal macrophage (Mphi) total cholesterol were 24% (P=0.07) and 25% (P<0.05) lower, respectively, in HSF R=1:1 compared to HSF omega-6 fed mice. MCP-1 mRNA levels and secretion were 37% (P<0.05) and 38% (P<0.05) lower, respectively, in elicited peritoneal Mphi isolated from HSF R=1:1 compared to HSF omega-6 fed mice. mRNA and protein levels of ATP-binding cassette A1, and mRNA levels of TNFalpha were significantly lower in elicited peritoneal Mphi isolated from HSF R=1:1 fed mice, whereas there was no significant effect of diets with different omega-6:EPA+DHA ratios on CD36, Mphi scavenger receptor 1, scavenger receptor B1 and IL-6 mRNA or protein levels. These data suggest that lower omega-6:EPA+DHA ratio diets lowered some measures of inflammation and Mphi cholesterol accumulation, which was associated with less aortic lesion formation in LDLr-/- mice.

Basic mechanisms behind the effects of n-3 fatty acids on cardiovascular disease

The epidemiological association between high intakes of n-3 fatty acids (FA) and decreased morbidity and mortality from cardiovascular disease (CVD) can be explained by two main basic mechanisms: (a) an effect on atherothrombosis, and (b) an effect on cardiac arrhythmias. These mechanisms probably reflect different beneficial influences of n-3 FA on cardiovascular biology. Effects on atherothrombosis include the modulation of the expression of pro-atherogenic genes (e.g., endothelial leukocyte adhesion molecules, inflammatory cytokines and cyclooxygenase (COX)-2) and the hepatic synthesis of very low density lipoproteins (VLDL), and are slow in onset, requiring incorporation into cell membrane phospholipids, and usually doses in humans in the order of 3g/day or higher. Effects on cardiac arrhythmias include complex interactions with ion channels (sodium, potassium and calcium channels), typically requiring the presence of free FA in extracellular fluids and usually occurring with lower doses (around 1g/day) of nutritional or pharmacological intake. We have focused most of our research effort in unraveling the pathophysiological background of protection by n-3 FA from atherothrombosis. As the result of incorporation of n-3 FA in the sn-2 position predominantly of the phosphatidyl ethanolamine pool in the inner leaflet of the plasma membrane, n-3 FA appear on the one hand to increase the production of bioactive lipid mediators (protectins and resolvins) affecting cytokine-induced signal transduction; and on the other hand to directly interfere with the generation of reactive oxygen species (mostly hydrogen peroxide), directly responsible for the activation of the transcription factor nuclear factor (NF)-kappaB, which controls the expression of a variety of pro-inflammatory and pro-atherogenic genes, including those encoding for interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor (TNF)alpha, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and COX-2. The upstream-direct or indirect-inhibition of cytokine- and other atherogenic trigger-induced signaling pathway may involve interference with the activation of protein kinase (PK) C isoforms and NADP(H) oxidase. Such interference may also explain the blunt anti-inflammatory effect of n-3 FA in many experimental models and clinical conditions of inflammation. All together, these mechanisms may provide an integrated view of how n-3 FA may affect CVD.

Nuclear factor-kappa B signaling in skeletal muscle atrophy

Skeletal muscle atrophy/wasting is a serious complication of a wide range of diseases and conditions such as aging, disuse, AIDS, chronic obstructive pulmonary disease, space travel, muscular dystrophy, chronic heart failure, sepsis, and cancer. Emerging evidence suggests that nuclear factor-kappa B (NF-kappaB) is one of the most important signaling pathways linked to the loss of skeletal muscle mass in various physiological and pathophysiological conditions. Activation of NF-kappaB in skeletal muscle leads to degradation of specific muscle proteins, induces inflammation and fibrosis, and blocks the regeneration of myofibers after injury/atrophy. Recent studies employing genetic mouse models have provided strong evidence that NF-kappaB can serve as an important molecular target for the prevention of skeletal muscle loss. In this article, we have outlined the current understanding regarding the role of NF-kappaB in skeletal muscle with particular reference to different models of muscle wasting and the development of novel therapy.

Fatty acid composition of serum lipid classes in mice following allergic sensitisation with or without dietary docosahexaenoic acid-enriched fish oil substitution

Dietary fatty acids have been shown to influence allergic sensitisation. Bothn-3 andn-6 PUFA are involved in targeted mediation of inflammatory responses during allergic sensitisation and manifestation of atopic diseases. In the present experiments we investigated whether supplementation of DHA-enriched fish oil partly substituting dietary sunflower-seed oil, in comparison with sunflower-seed oil, supplemented to mice influences fatty acid composition of serum lipid classes. The effects of the two different diets were also investigated depending on allergic sensitisation. Supplementation of DHA and EPA in doses of 2 and 0·12 % (w/w) to non-sensitised and sensitised mice resulted in significantly increased percentile contributions of DHA to all lipid classes. In contrast, serum values of then-6 PUFA arachidonic acid (AA) were significantly lower, both in non-sensitised and sensitised mice fed the DHA-enriched diet. The fatty acid composition of serum lipids also reflected allergic sensitisation: the EPA:AA ratio in TAG, cholesteryl esters and phospholipids in non-supplemented animals fell to 23, 29 and 29 % respectively of the original value after allergic sensitisation, whereas it decreased to 70, 80 and 76 % respectively only in the animals supplemented with DHA. In summary, allergic sensitisation alone decreased significantly the EPA:AA ratios in serum TAG, while concomitant supplementation of DHA-enriched fish oil ameliorated this decrease. We postulate from the present results that the amelioration of the severity of allergic sensitisation after DHA supplementation may be linked to altered ratios of the eicosanoid precursors EPA and AA as well as DHA needed for further metabolic activation to pro- or anti-inflammatory bioactive lipids.

Anti-inflammatory properties of omega-3 fatty acids in critical illness: novel mechanisms and an integrative perspective

INTRODUCTION

Fish oil-based nutrition is protective in severe critical care conditions. Regulation of the activity of transcription factor NF-kappaB is an important therapeutic effect of the major omega-3 fatty acids in fish oil, eicosapentaenoic and docosahexaenoic acid (EPA and DHA).

METHODS AND RESULTS

Using the articles obtained by a Pubmed research, this article reviews three aspects of NF-kappaB/inflammatory inhibition by fish oil. (1) Inhibition of the NF-kappaB pathway at several subsequent steps: extracellular, free omega-3 inhibits the activation of the Toll-like receptor 4 by endotoxin and free saturated fatty acids. In addition, EPA/DHA blocks the signaling cascade between Toll-like/cytokine receptors and the activator of NF-kappaB, IKK. Oxidized omega-3 also interferes with the initiation of transcription by NF-kappaB. (2) The altered profile of lipid mediators generated during inflammation, with production of the newly identified, DHA-derived inflammation-resolving mediator classes (in addition to the formation of less pro-inflammatory eicosanoids from EPA). Resolvin D1 and Protectin D1 are potent, endogenous, DHA-derived lipid mediators that attenuate neutrophil migration and tissue injury in peritonitis and ischemia-reperfusion injury. Their production is increased in the later stages of an inflammatory response, at which time they enhance the removal of neutrophils. (3) Modulation of vagal tone with potential anti-inflammatory effects: vagal fibers innervating the viscera down-regulate inflammation by activating nicotinic receptors upon infiltrating and resident macrophages. Stimulation of the efferent vagus is therapeutic in experimental septic shock. Fish oil supplementation increases vagal tone following myocardial infarction and in experimental human endotoxinemia.

CONCLUSION

It remains to be shown whether these pleiotropic actions of EPA/DHA contribute to fish oil's therapeutic effect in sepsis.

Orally administered eicosapentaenoic acid reduces and stabilizes atherosclerotic lesions in ApoE-deficient mice

Accumulating evidence demonstrates that dietary intake of n-3 polyunsaturated fatty acids (PUFAs) is associated with reduced incidence of cardiovascular events. However, the molecular mechanisms by which n-3 PUFAs prevent atherosclerosis are not fully understood. Here, we examined the effect of eicosapentaenoic acid (EPA), a major n-3 PUFA, on the pathogenesis of atherosclerosis in ApoE-deficient mice. Five-week-old ApoE-deficient male mice were fed on western-type diet supplemented with 5% (w/w) EPA (EPA group, n=7) or not (control group, n=5) for 13 weeks. An analysis of the fatty acid composition of liver homogenates revealed a marked increase of the n-3 PUFA content in the EPA group (n-3/n-6 ratio: 0.20+/-0.01 vs. 2.5+/-0.2, p<0.01). En face Sudan IV staining of the aorta and oil red O-staining of the aortic sinus revealed that EPA significantly suppressed the development of atherosclerotic lesions. We also observed anti-atherosclerotic effects of EPA in LDL-receptor-deficient mice. The lesions of the EPA group contained more collagen (19.6+/-2.4% vs. 32.9+/-3.9%, p<0.05) and smooth muscle cells (1.3+/-0.2% vs. 3.6+/-0.8%, p<0.05) and less macrophages (32.7+/-4.1% vs. 14.7+/-2.0%, p<0.05). Pretreatment with EPA attenuated the up-regulation of VCAM-1, ICAM-1 and MCP-1 in HUVECs as well as the expression of MMP-2 and MMP-9 in macrophage-like cells induced by TNF-alpha. The anti-inflammatory effects of EPA were abrogated when the expression of peroxisome proliferator-activated receptor alpha (PPARalpha) was suppressed. EPA may potentially reduce and stabilize atherosclerotic lesions through its anti-inflammatory effects.

Impact of nutrition on PCB toxicity

Studies are evolving which suggest that nutritional intervention can modify pathologies of diseases associated with environmental toxic insults. The diet is a major route of exposure to environmental toxins, such as persistent organic pollutants and heavy metals. Many persistent organics, such as polychlorinated biphenyls (PCBs), bioaccumulate in our bodies and "bioremediation" is extremely difficult. Furthermore, many environmental toxins induce signaling pathways that are oxidative stress-sensitive and similar or the same as the ones associated with the etiology and early pathology of many chronic diseases. There is now increasing evidence that exposure to PCBs can contribute to the development of inflammatory diseases such as atherosclerosis. Activation, chronic inflammation, and dysfunction of the vascular endothelium are critical events in the initiation and acceleration of atherosclerotic lesion formation. Our studies indicate that an increase in cellular oxidative stress and an imbalance in antioxidant status are critical events in PCB-mediated induction of inflammatory genes and endothelial cell dysfunction. We also have evidence that the plasma membrane microdomains called caveolae play an important role in endothelial activation and toxicity mediated by coplanar PCBs. Caveolae are particularly abundant in endothelial cells and play a major role in endothelial trafficking and the regulation of signaling pathways associated with the pathology of vascular diseases. There is a great need to further explore this nutritional paradigm in environmental toxicology and to improve our understanding of the relationship between nutrition and lifestyle, exposure to environmental toxins and disease. Our studies suggest that certain dietary fats can increase the risk of environmental insult induced by PCBs, while other dietary factors may provide protection. Nutrition may provide the most sensible means to develop primary intervention and prevention strategies of diseases associated with many environmental toxic insults.

Formation of highly reactive cyclopentenone isoprostane compounds (A3/J3-isoprostanes) in vivo from eicosapentaenoic acid

Omega-3 (omega-3) polyunsaturated fatty acids (PUFAs) found in marine fish oils are known to suppress inflammation associated with a wide variety of diseases. Eicosapentaenoic acid (EPA) is one of the most abundant omega-3 fatty acids in fish oil, but the mechanism(s) by which EPA exerts its beneficial effects is unknown. Recent studies, however, have demonstrated that oxidized EPA, rather than native EPA, possesses anti-atherosclerotic, anti-inflammatory, and anti-proliferative effects. Very few studies to date have investigated which EPA oxidation products are responsible for this bioactivity. Our research group has previously reported that anti-inflammatory prostaglandin A(2)-like and prostaglandin J(2)-like compounds, termed A(2)/J(2)-isoprostanes (IsoPs), are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid and represent one of the major products resulting from the oxidation of this PUFA. Based on these observations, we questioned whether cyclopentenone-IsoP compounds are formed from the oxidation of EPA in vivo. Herein, we report the formation of cyclopentenone-IsoP molecules, termed A(3)/J(3)-IsoPs, formed in abundance in vitro and in vivo from EPA peroxidation. Chemical approaches coupled with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) were used to structurally characterize these compounds as A(3)/J(3)-IsoPs. We found that levels of these molecules increase approximately 200-fold with oxidation of EPA in vitro from a basal level of 0.8 +/- 0.4 ng/mg EPA to 196 +/- 23 ng/mg EPA after 36 h. We also detected these compounds in significant amounts in fresh liver tissue from EPA-fed rats at basal levels of 19 +/- 2 ng/g tissue. Amounts increased to 102 +/- 15 ng/g tissue in vivo in settings of oxidative stress. These studies have, for the first time, definitively characterized novel, highly reactive A/J-ring IsoP compounds that form in abundance from the oxidation of EPA in vivo.

Oral eicosapentaenoic acid supplementation as possible therapy for endometriosis

OBJECTIVE

To investigate the anti-inflammatory effect of n-3 eicosapentaenoic acid (EPA) compared with n-6 linoleic acid (LA) in an endometriosis rat model. We focused on the relationship between lipid metabolism and inflammatory reactions in endometriosis based on the hypothesis that a lipid intake imbalance is one of the factors responsible for the recent increase of endometriosis.

DESIGN

Prospective, randomized experimental study.

SETTING

Animal surgery laboratory in a university hospital.

ANIMAL(S)

Sprague-Dawley rats (female, 6 weeks old).

INTERVENTION(S)

Rats were fed a diet with EPA (n = 9) or with LA (n = 9) for 2 weeks. Two weeks after feeding, the uterus was autotransplanted to the peritoneum to construct an endometriosis model. Feeding was continued for a total of 6 weeks. Two and 4 weeks after autotransplantation, three rats of each group were killed and evaluated.

MAIN OUTCOME MEASURE(S)

Endometriotic lesions were morphologically evaluated and their fatty acid composition was examined. Gene expression in these tissues was evaluated by cDNA microarray analysis and quantative real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULT(S)

In the EPA group, the n-3:n-6 ratio in each tissue significantly increased and the thickening of the interstitium, an active site for inflammation in endometriosis, was significantly suppressed (0.30 +/- 0.09 mm [EPA group] vs. 0.77 +/- 0.23 mm [LA group]). The mRNA of metalloproteinases, interleukin-1beta, interleukin-1r, prostaglandin E synthase (Ptges), and nuclear factor (NF)-kappaB were reduced in the EPA group.

CONCLUSION(S)

EPA supplementation might be a valid strategy for the treatment of endometriosis.

Antioxidative and anti-inflammatory actions of docosahexaenoic acid and eicosapentaenoic acid in renal epithelial cells and macrophages

Oxidative stress due to excessive reactive species (RS) and weakened antioxidant defenses is causally associated with inflammation and inflammatory mediators. To investigate the effects of the major fish oil ingredients, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), on oxidative stress-related inflammatory status, we conducted in vitro experiments utilizing rat renal epithelial cells (NRK-52E) and murine macrophages (RAW 264.7) by assessing their effects on the generation of cyclooxygenase (COX)-2-derived and xanthine oxidase (XOD)-derived RS, reduced glutathione (GSH) levels, and antioxidative enzyme activities. Additionally, 6-keto-prostaglandin (PG) F1alpha, PGE2, and nitrite levels were measured in lipopolysaccharide-stimulated RAW 264.7 macrophages. Results showed that the generation of RS from arachidonic acid through the COX-2 and XOD pathways was effectively suppressed by DHA and EPA, while GSH levels and antioxidative enzyme activities were significantly enhanced by DHA and EPA. Furthermore, levels of inflammatory mediators (thromboxane B2, PGE2, and 6-keto-PGF1alpha) and nitrite were effectively down-regulated by DHA and EPA. These results strongly indicate that DHA and EPA exert antioxidative and anti-inflammatory actions by reducing the cellular levels of RS, pro-inflammatory mediators, and nitrite levels and by maintaining higher GSH levels and antioxidative enzyme activities.

Tetradecylthioacetic acid prevents the inflammatory response in two-kidney, one-clip hypertension

ANG II promotes inflammation through nuclear factor-kappaB (NF-kappaB)-mediated induction of cytokines and reactive oxygen species (ROS). The aim of the present study was to examine the effect of tetradecylthioacetic acid (TTA), a modified fatty acid, on NF-kappaB, proinflammatory markers, ROS, and nitric oxide (NO) production in two-kidney, one-clip (2K1C) hypertension. The 2K1C TTA-treated group had lower blood pressure (128 +/- 3 mmHg) compared with 2K1C nontreated (178 +/- 5 mmHg, P < 0.001). The p50 and p65 subunits of NF-kappaB were higher in the clipped kidney (0.44 +/- 0.01 and 0.22 +/- 0.01, respectively) compared with controls (0.25 +/- 0.03 and 0.12 +/- 0.02, respectively, P < 0.001). In the 2K1C TTA-treated group, these values were similar to control levels. The same pattern of response was seen in the nonclipped kidney. In 2K1C hypertension, cytokines plasma were higher than in control: TNF-alpha was 13.5 +/- 2 pg/ml (P < 0.03), IL-1beta was 58.8 +/- 10 pg/ml (P = 0.003), IL-6 was 210 +/- 33 pg/ml (P < 0.001), and monocyte chemoattractant protein-1 was 429 +/- 21 pg/ml (P = 0.04). In the 2K1C TTA-treated group, these values were similar to controls, and the same pattern was seen in the clipped kidney. Clipping increased 8-iso-PGF-2alpha (P < 0.01) and decreased NO production (P < 0.01 vs. control) in the urine. TTA treatment normalized these values. NO production was also lower in clipped and nonclipped kidney (P < 0.001). After TTA treatment, these values were similar to controls. The results indicate that TTA has a potent anti-inflammatory effect in 2K1C by inhibition of p50/p65 NF-kappaB subunit activation, reduction of cytokines production and ROS, and enhanced NO production.

Changing ratios of omega-6 to omega-3 fatty acids can differentially modulate polychlorinated biphenyl toxicity in endothelial cells

Exposure to persistent organic pollutants, such as polychlorinated biphenyls (PCBs) can cause endothelial cell (EC) activation by inducing pro-inflammatory signaling pathways. Our previous studies indicated that linoleic acid (LA, 18:2), a major omega-6 unsaturated fatty acid in the American diet, can potentiate PCB77-mediated inflammatory responses in EC. In addition, omega-3 fatty acids (such as alpha-linolenic acid, ALA and 18:3) are known for their anti-inflammatory properties. We tested the hypothesis that mechanisms of PCB-induced endothelial cell activation and inflammation can be modified by different ratios of omega-6 to omega-3 fatty acids. EC were pretreated with LA, ALA, or different ratios of these fatty acids, followed by exposure to PCB77. PCB77-induced oxidative stress and activation of the oxidative stress sensitive transcription factor nuclear factor kappaB (NF-kappaB) were markedly increased in the presence of LA and diminished by increasing the relative amount of ALA to LA. Similar protective effects by increasing ALA were observed by measuring NF-kappaB-responsive genes, such as vascular cell adhesion molecule-1 (VCAM-1) and cyclooxygenase-2 (COX-2). COX-2 catalyzes the rate limiting step of the biosynthesis of prostaglandin E(2) (PGE(2)). PCB77 exposure also increased PGE(2) levels, which were down-regulated with relative increasing amounts of ALA to LA. The present studies suggest that NF-kappaB is a critical player in the regulation of PCB-induced inflammatory markers as modulated by omega-6 and omega-3 fatty acids.

PPARalpha transcriptionally induces AhR expression in Caco-2, but represses AhR pro-inflammatory effects

In this work we demonstrate that Caco-2 cell treatment with WY-14643 (a potent PPARalpha agonist) causes an increase in AhR expression. Luciferase assays and directed mutagenesis experiments showed that induction mainly occurred at transcriptional level and involved a PPRE site located within the AhR promoter. These results were further confirmed by the use of PPARalpha knockout mice in which AhR induction by WY14643 was abrogated. In addition to CYP1 regulation, AhR has been described as being involved in inflammation, so we also studied the effect of AhR regulation by PPARalpha on the expression of some inflammation target genes. 3-Methylcholanthrene (a potent AhR agonist) increased the expression (mRNA) of the major inflammatory targets IL-1beta and MMP9. WY-14643 co-treatment abrogated the 3-methylcholanthrene pro-inflammatory effect. Hence the anti-inflammatory effect of PPARalpha overrides the pro-inflammatory effect of AhR.

PPARalpha ligands reduce PCB-induced endothelial activation: possible interactions in inflammation and atherosclerosis

Exposure to polychlorinated biphenyls (PCBs) can activate inflammatory responses in vascular endothelial cells. Activation of peroxisome proliferator-activated receptors (PPARs) by nutrients or synthetic agonists has been shown to block pro-inflammatory responses both in vitro and in vivo. Here we demonstrate that activation of PPARalpha by synthetic agonists can reduce 3,3'4,4'-tetrachlorobiphenyl (PCB77)-induced endothelial cell activation. Primary vascular endothelial cells were pretreated with the PPARalpha ligands fenofibrate or WY14643 followed by exposure to PCB77. PPARalpha activation protected endothelial cells against PCB77-induced expression of the pro-inflammatory proteins vascular cell adhesion molecule-1 (VCAM-1), cycloxygenase-2 (COX-2), and PCB77-induced expression and activity of the aryl hydrocarbon receptor (AHR) responsive cytochrome P450 1A1 (CYP1A1). Furthermore, basal AHR expression was downregulated by fenofibrate and WY14643. We also investigated the possible interactions between PCBs, and basal PPAR activity and protein expression. Treatment with PCB77 significantly reduced basal mRNA expression of PPARalpha and the PPAR responsive gene CYP4A1, as well as PPARalpha protein expression. Also, PCB77 exposure caused a significant decrease in basal PPAR-dependent reporter gene expression in MCF-7 cells. Overall, these findings suggest that PPARalpha agonists can reduce PCB77 induction of endothelial cell activation by inhibition of the AHR pathway, and that coplanar PCB induced pro-inflammatory effects could be mediated, in part, by inhibition of PPARalpha expression and function.

Thermally oxidized oil increases the expression of insulin-induced genes and inhibits activation of sterol regulatory element-binding protein-2 in rat liver

Administration of oxidized oils to rats or pigs causes a reduction of their cholesterol concentrations in liver and plasma. The reason for this effect is unknown. We tested the hypothesis that oxidized oils lower cholesterol concentrations by inhibiting the proteolytic activation of sterol regulatory element-binding protein (SREBP)-2 in the liver and transcription of its target genes involved in cholesterol synthesis and uptake through an upregulation of gene expression of insulin-induced genes (Insig). For 6 d, 18 rats were orally administered either sunflower oil (control group) or an oxidized oil prepared by heating sunflower oil. Rats administered the oxidized oil had higher messenger RNA (mRNA) concentrations of acyl-CoA oxidase and cytochrome P450 4A1 in the liver than control rats (P < 0.05), indicative of activation of PPARalpha. Furthermore, rats administered the oxidized oil had higher mRNA concentrations of Insig-1 and Insig-2a, a lower concentration of the mature SREBP-2 in the nucleus, lower mRNA concentrations of the SREBP-2 target genes 3-hydroxy-3-methylglutaryl CoA reductase and LDL receptor in their livers, and a lower concentration of cholesterol in liver, plasma, VLDL, and HDL than control rats (P < 0.05). In conclusion, this study shows that reduced cholesterol concentrations in liver and plasma of rats administered an oxidized oil were due to an inhibition of the activation of SREBP-2 by an upregulation of Insig, which in turn inhibited transcription of proteins involved in hepatic cholesterol synthesis and uptake.

Oxidized fat reduces milk triacylglycerol concentrations by inhibiting gene expression of lipoprotein lipase and fatty acid transporters in the mammary gland of rats

Feeding oxidized fats to lactating rats causes a strong reduction of triacylglycerol concentration in the milk. The reason for this, however, has not yet been elucidated. Pregnant Sprague-Dawley rats were assigned to 2 groups of 11 rats each and fed diets containing either fresh fat (FF group) or an oxidized fat (OF group) from d 1 to d 20 of lactation. Concentrations of triacylglycerols and long-chain fatty acids in the milk and weight gain of suckling pups were lower in the OF group than in the FF group (P < 0.05). Concentrations of medium-chain fatty acids in the milk and messenger RNA (mRNA) abundance of lipogenic enzymes in the mammary gland did not differ between the 2 groups of rats. However, the OF group had a lower concentration of triacylglycerols and nonesterified fatty acids (NEFA) in plasma and lower mRNA concentrations of lipoprotein lipase and fatty acid transporters in the mammary gland than the FF group (P < 0.05). Moreover, the OF group had higher mRNA concentrations of hepatic lipase, fatty acid transporters, and several genes involved in fatty acid oxidation in the liver than the FF group (P < 0.05). The present findings suggest that a dietary oxidized fat lowers the concentration of triacylglycerols in the milk by a reduced uptake of fatty acids from triacylglycerol rich-lipoproteins and NEFA into the mammary gland. The study, moreover, indicates that an oxidized fat impairs normal metabolic adaptations during lactation, which promote the utilization of metabolic substrates by the mammary gland for the synthesis of milk.

Pharmacological Treatment of Geriatric Cachexia: Evidence and Safety in Perspective

Anticachexic or antisarcopenic medications are prescribed worldwide for geriatric patients with poor appetite and associated weight loss. They represent a valuable treatment option for managing cachexia. However, the well-publicized adverse reports about these medications in acquired immunodeficiency syndrome (AIDS) and in the cancer population has led to some concern and much subsequent discussion over the safety of these medications being used in geriatric population. This review looks at the evidence in relation to the benefits and risks of these medications and discusses what we know about their use in the geriatric population.

Evidences of the cardioprotective potential of fruits: The case of cranberries

Eating a healthy balanced diet, is one of the most important and relevant ways to delay and prevent various health complications including cardiovascular disease (CVD). Among the nutritional factors that have been investigated in recent years, dietary fat intake may be the one that has been most targeted. However, there is also clear epidemiological evidence that increased fruits and vegetables intake can significantly reduce the risk of CVD, an effect that has been suggested to be resulting to a significant extent, from the high polyphenol content of these foods. Numerous polyphenolic compounds such as flavonoids have been identified as having strong antioxidant properties. Most interesting is the fact that, in addition to being one of the largest groups of antioxidant phytochemicals, flavonoids are also an integral part of the human diet as they are found in most fruits and vegetables. Cranberries are one of the most important sources of flavonoids that have a strong antioxidant and anti-inflammatory capacities. Thus, consumption of cranberries or their related products could be of importance not only in the maintenance of health but also in preventing CVD. The following review will present evidences supported for the most part by clinical observations that cranberries can exert potentially healthy effects for your heart.

Dietary oxidised fat up regulates the expression of organic cation transporters in liver and small intestine and alters carnitine concentrations in liver, muscle and plasma of rats

It has been shown that treatment of rats with clofibrate, a synthetic agonist of PPARalpha, increases mRNA concentration of organic cation transporters (OCTN)-1 and -2 and concentration of carnitine in the liver. Since oxidised fats have been demonstrated in rats to activate hepatic PPARalpha, we tested the hypothesis that they also up regulate OCTN. Eighteen rats were orally administered either sunflower-seed oil (control group) or an oxidised fat prepared by heating sunflower-seed oil, for 6 d. Rats administered the oxidised fat had higher mRNA concentrations of typical PPARalpha target genes such as acyl-CoA oxidase, cytochrome P450 4A1 and carnitine palmitoyltransferases-1A and -2 in liver and small intestine than control rats (P < 0.05). Furthermore, rats treated with oxidised fat had higher hepatic mRNA concentrations of OCTN1 (1.5-fold) and OCTN2 (3.1-fold), a higher carnitine concentration in the liver and lower carnitine concentrations in plasma, gastrocnemius and heart muscle than control rats (P < 0.05). Moreover, rats administered oxidised fat had a higher mRNA concentration of OCTN2 in small intestine (2.4-fold; P < 0.05) than control rats. In conclusion, the present study shows that an oxidised fat causes an up regulation of OCTN in the liver and small intestine. An increased hepatic carnitine concentration in rats treated with the oxidised fat is probably at least in part due to an increased uptake of carnitine into the liver which in turn leads to reduced plasma and muscle carnitine concentrations. The present study supports the hypothesis that nutrients acting as PPARalpha agonists influence whole-body carnitine homeostasis.

Antiadhesion effects of docosahexaenoic acid on normal human peritoneal and adhesion fibroblasts

OBJECTIVE

To determine whether docosahexaenoic acid (DHA) reduces adhesion marker mRNA levels in normal peritoneal and adhesion fibroblasts.

DESIGN

Prospective experimental study.

SETTING

University Medical Center.

PATIENT(S)

Three patients undergoing laparotomy with excision of adhesions and normal peritoneum.

INTERVENTION(S)

DHA treatment (100 muM) of cell cultures for 24 hours.

MAIN OUTCOME MEASURE(S)

Real-time reverse transcriptase polymerase chain reaction (RT-PCR) quantification of relative changes (mRNA copies/mug mRNA) in mRNA levels of type I collagen, vascular endothelial growth factor (VEGF), and transforming growth factor-beta1 (TGF-beta1).

RESULT(S)

The DHA treatment significantly reduced type I collagen and VEGF, but not TGF-beta1 mRNA levels in normal peritoneal fibroblasts compared to normal controls. The DHA treatment of adhesion fibroblasts reduced type I collagen mRNAs to those of normal peritoneal fibroblasts, decreasing mRNAs by 35% compared to untreated adhesion fibroblasts. The VEGF mRNA levels were 50% lower in DHA-treated adhesion fibroblasts versus untreated adhesion fibroblasts. Docasahexaenoic acid reduced TGF- beta1 mRNA to normal levels in treated adhesion fibroblasts compared to untreated normal peritoneal fibroblasts.

CONCLUSION(S)

Docasahexaenoic acid substantially reduces levels of adhesion-related markers in normal peritoneal and adhesion fibroblasts. This study provides the molecular basis for an easily administered and potentially, highly efficacious, antiadhesion adjuvant.

Feeding of a deep-fried fat causes PPARα activation in the liver of pigs as a non-proliferating species

Recent studies have shown that dietary oxidised fats influence the lipid metabolism in rats by activation of PPARα. In this study, we investigated whether a mildly oxidised fat causes activation of PPARα in pigs which are non-proliferators like man. Eighteen pigs were assigned to two groups and received either a diet containing 90 g/kg of a fresh fat or the same diet with 90 g/kg of an oxidised fat prepared by heating for 24 h at 180°C in a deep fryer. Pigs fed the oxidised fat had a higher peroxisome count, a higher activity of catalase and a higher mRNA concentration of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in the liver and a higher concentration of 3-hydroxybutyrate in plasma than pigs fed the fresh fat (P < 0·05). Hepatic mRNA concentrations of acyl-CoA oxidase and carnitine palmitoyltransferase-1 tended to be increased in pigs fed the oxidised fat compared to pigs fed the fresh fat (P < 0·10). Pigs fed the oxidised fat, moreover, had higher mRNA concentrations of sterol regulatory element-binding protein (SREBP)-1 and its target genes acetyl-CoA carboxylase and stearoyl-CoA desaturase in the liver and higher mRNA concentrations of SREBP-2 and its target genes 3-hydroxy-3-methylglutary-CoA reductase and LDL receptor in liver and small intestine. In conclusion, this study shows that even a mildly oxidised fat causes activation of PPARα in the liver of pigs. Up-regulation of SREBP and its target genes in liver and small intestine suggests that the oxidised fat could stimulate synthesis of cholesterol and TAG in these tissues.

Fatty acids isolated from Toxoplasma gondii reduce glycosylphosphatidylinositol-induced tumor necrosis factor alpha production through inhibition of the NF-kappaB signaling pathway

Glycosylphosphatidylinositols (GPIs) are involved in the pathogenicity of protozoan parasites and are known to induce inflammatory cytokines. However, we have previously shown that the family of six GPIs of Toxoplasma gondii extracted together from tachyzoites could not induce tumor necrosis factor alpha (TNF-alpha) secretion by macrophages, whereas GPIs individually separated from this extract by thin-layer chromatography (TLC) were able to stimulate the cells. In the present study we show that the TLC step makes it possible to eliminate inhibitors extracted together with the T. gondii GPIs. Among the non-GPI molecules we have isolated fatty acids able to inhibit the secretion of TNF-alpha induced by the T. gondii GPIs. Myristic and palmitic acids reduce the production of TNF-alpha through the inhibition of tyrosine phosphorylation of cytoplasmic proteins and the inhibition of NF-kappaB activation in a peroxisome proliferator-activated receptor-independent pathway and after a rapid entry into the cytoplasm of macrophages. GPIs are considered toxins inducing irreversible damage in the host, and fatty acids produced in parallel by the parasite could reduce the immune response, thus favoring the persistence of parasite infection.

Feeding oxidized fat during pregnancy up-regulates expression of PPARalpha-responsive genes in the liver of rat fetuses

Background

Feeding oxidized fats causes activation of peroxisome proliferator-activated receptor α (PPARα) in the liver of rats. However, whether feeding oxidized fat during pregnancy also results in activation of PPARα in fetal liver is unknown. Thus, this study aimed to explore whether feeding oxidized fat during pregnancy causes a PPARα response in fetal liver. Two experiments with pregnant rats which were administered three different diets (control; oxidized fat; clofibrate as positive control) in a controlled feeding regimen during either late pregnancy (first experiment) or whole pregnancy (second experiment) were performed.

Results

In both experiments pregnant rats treated with oxidized fat or clofibrate had higher relative mRNA concentrations of the PPARα-responsive genes acyl-CoA oxidase (ACO), cytochrome P₄₅₀ 4A1 (CYP4A1), L-type carnitin-palmitoyl transferase I (L-CPT I), medium-chain acyl-CoA dehydrogenase (MCAD), and long-chain acyl-CoA dehydrogenase (LCAD) in the liver than control rats (P < 0.05). In addition, in both experiments fetuses of the oxidized fat group and the clofibrate group also had markedly higher relative mRNA concentrations of ACO, CYP4A1, CPT I, MCAD, and LCAD in the liver than those of the control group (P < 0.05), whereas the relative mRNA concentrations of PPARα, SREBP-1c, and FAS did not differ between treatment groups. In the second experiment treatment with oxidized fat also reduced triacylglycerol concentrations in the livers of pregnant rats and fetuses (P < 0.05).

Conclusion

The present study demonstrates for the first time that components of oxidized fat with PPARα activating potential are able to induce a PPARα response in the liver of fetuses. Moreover, the present study shows that feeding oxidized fat during whole pregnancy, but not during late pregnancy, lowers triacylglycerol concentrations in fetal livers.

Inhibition of cytokine signaling in human retinal endothelial cells through modification of caveolae/lipid rafts by docosahexaenoic acid

PURPOSE

Docosahexaenoic acid (DHA(22:6,n3)) is the principal n3 polyunsaturated fatty acid (PUFA) in the retina. The authors previously demonstrated that DHA(22:6,n3) inhibited cytokine-induced adhesion molecule expression in primary human retinal vascular endothelial (hRVE) cells, the target tissue affected by diabetic retinopathy. Despite the importance of vascular inflammation in diabetic retinopathy, the mechanisms underlying anti-inflammatory effects of DHA(22:6,n3) in vascular endothelial cells are not understood. In this study the authors address the hypothesis that DHA(22:6,n3) acts through modifying lipid composition of caveolae/lipid rafts, thereby changing the outcome of important signaling events in these specialized plasma membrane microdomains.

METHODS

hRVE cells were cultured in the presence or absence of DHA(22:6,n3). Isolated caveolae/lipid raft-enriched detergent-resistant membrane domains were prepared using sucrose gradient ultracentrifugation. Fatty acid composition and cholesterol content of caveolae/lipid rafts before and after treatment were measured by HPLC. The expression of Src family kinases was assayed by Western blotting and immunohistochemistry.

RESULTS

Disruption of the caveolae/lipid raft structure with a cholesterol-depleting agent, methyl-cyclodextrin (MCD), diminished cytokine-induced signaling in hRVE cells. Growth of hRVE cells in media enriched in DHA(22:6,n3) resulted in significant incorporation of DHA(22:6,n3) into the major phospholipids of caveolae/lipid rafts, causing an increase in the unsaturation index in the membrane microdomain. DHA(22:6,n3) enrichment in the caveolae/raft was accompanied by a 70% depletion of cholesterol from caveolae/lipid rafts and displacement of the SFK, Fyn, and c-Yes from caveolae/lipid rafts. Adding water-soluble cholesterol to DHA(22:6,n3)-treated cells replenished cholesterol in caveolae/lipid rafts and reversed the effect of DHA(22:6,n3) on cytokine-induced signaling.

CONCLUSIONS

Incorporation of DHA(22:6,n3) into fatty acyl chains of phospholipids in caveolae/lipid rafts, followed by cholesterol depletion and displacement of important signaling molecules, provides a potential mechanism for anti-inflammatory effect of DHA(22:6,n3) in hRVE cells.

Peroxisome proliferator-activated receptors: Bridging metabolic syndrome with molecular nutrition

Over recent years, obesity rates and the onset of obesity-induced chronic diseases have risen dramatically. The more we learn about the physiological and morphological changes that occur during obesity, the more it is becoming clear that obesity-related disorders can be traced back to adipocyte hypertrophy and inflammation at white adipose tissue (WAT). To combat this problem, the body has developed a regulatory system specifically designed at mediating the systemic response to obesity, utilizing free fatty acids (FFAs) and their metabolites as nutrient messengers to signal adaptations from peripheral tissues. These messages are predominantly interceded through the peroxisome proliferator-activated receptors (PPARs), a family of ligand-induced transcription factors that serve as a net of lipid sensors throughout the body. Understanding how and why nutrients, nutrient derivatives and metabolites exert their physiological effects are the key goals in the study of molecular nutrition. By learning about the mechanisms and tissue-specific effects of endogenous PPAR ligands and expanding our knowledge of the body's integrated homeostatic system, we will significantly increase our odds of designing safe and effective preventive and therapeutic interventions that keep us one step ahead of obesity-related diseases.

Fatty acids from Plasmodium falciparum down-regulate the toxic activity of malaria glycosylphosphatidylinositols

Plasmodium falciparum malaria kills roughly 2.5 million people, mainly children, annually. Much of this mortality is thought to arise from the actions of a malarial toxin. This toxin, identified as glycosylphosphatidylinositol (GPI), is a major pathogenicity determinant in malaria. A malarial molecule, Pfj, labeled by [3H]glucosamine like the GPIs, was identified as a non-GPI molecule. Here we show that Pfj is able to down-regulate tumor necrosis factor alpha (TNF-alpha) production induced by the GPI of P. falciparum. Mass spectrometry analysis showed that Pfj was not a single molecule but represented a number of molecules. Separation methods, such as cation-exchange chromatography and thin-layer chromatography, were used to isolate and identify the following four main fatty acids responsible for the inhibitory effect on TNF-alpha production: myristic, pentadecanoic, palmitic, and palmitoleic acids. This regulatory effect on cytokine production suggests that there is balanced bioactivity for the different categories of malarial lipids.

Essential fatty acids: biochemistry, physiology and pathology

Essential fatty acids (EFAs), linoleic acid (LA), and alpha-linolenic acid (ALA) are essential for humans, and are freely available in the diet. Hence, EFA deficiency is extremely rare in humans. To derive the full benefits of EFAs, they need to be metabolized to their respective long-chain metabolites, i.e., dihomo-gamma-linolenic acid (DGLA), and arachidonic acid (AA) from LA; and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from ALA. Some of these long-chain metabolites not only form precursors to respective prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), but also give rise to lipoxins (LXs) and resolvins that have potent anti-inflammatory actions. Furthermore, EFAs and their metabolites may function as endogenous angiotensin-converting enzyme and 3-hdroxy-3-methylglutaryl coenzyme A reductase inhibitors, nitric oxide (NO) enhancers, anti-hypertensives, and anti-atherosclerotic molecules. Recent studies revealed that EFAs react with NO to yield respective nitroalkene derivatives that exert cell-signaling actions via ligation and activation of peroxisome proliferator-activated receptors. The metabolism of EFAs is altered in several diseases such as obesity, hypertension, diabetes mellitus, coronary heart disease, schizophrenia, Alzheimer's disease, atherosclerosis, and cancer. Thus, EFAs and their derivatives have varied biological actions and seem to be involved in several physiological and pathological processes.

The Effect of Smoking on the Transcriptional Regulation of Lung Inflammation in Patients with Chronic Obstructive Pulmonary Disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is believed to result from an abnormal inflammatory response in the lungs to noxious particles and gases usually found in cigarette smoke.

OBJECTIVES

In this study, the molecular mechanisms for the enhanced proinflammatory cytokine gene transcription in COPD were investigated.

METHODS

Lung tissue was examined from 56 subjects undergoing resection for peripheral lung tumors as follows: current smokers with (n = 14) and without COPD (n = 17), ex-smokers with COPD (n = 13), and nonsmokers (n = 12). The levels of inhibitor kappaB-alpha (IkappaB-alpha), histone deacetylase 2 (HDAC2), acetylated (ac-) histone H3 and H4, the transcription factor nuclear factor-kappaB (NF-kappaB), proinflammatory cytokine messenger RNA, and 8-isoprostane were measured.

MEASUREMENTS AND MAIN RESULTS

IkappaB-alpha levels were significantly decreased in healthy smokers and current and ex-smoking patients with COPD when compared with nonsmokers (p < 0.001), with an associated increase in NF-kappaB DNA binding in current smokers (p < 0.05). An increase in acetylated histone 4 (ac-H4; p < 0.01) was found in current smokers. Conversely, ex-smokers with COPD showed an increase in ac-H3 (p < 0.05). Decreased levels of cytoplasmic, but not nuclear, HDAC2 protein levels were detected. From the cytokine profiles, no significant differences were detected; however, interleukin-12p40 expression correlated with ac-H4 in current smokers with COPD (p < 0.01).

CONCLUSION

These data propose a role for modification of nucleosomal structure in inflammatory cytokine gene transcription in response to smoking. The imbalance between histone deacetylation and acetylation in favor of acetylation may contribute to the enhanced inflammation in smokers susceptible to the development of COPD.

A novel beta-oxa polyunsaturated fatty acid downregulates the activation of the IkappaB kinase/nuclear factor kappaB pathway, inhibits expression of endothelial cell adhesion molecules, and depresses inflammation

Several novel polyunsaturated fatty acids (PUFAs) that contain either an oxygen or sulfur atom in the beta-position were found to exhibit more selective antiinflammatory properties than their natural PUFA counterparts. One of these, beta-oxa-23:4n-6, unlike natural PUFAs, lacked ability to stimulate oxygen radical production in neutrophils but caused marked inhibition of agonist-induced upregulation of leukocyte adhesion to cultured human umbilical vein endothelial cells (HUVEC) and E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 expression. In addition, beta-oxa-23:4n-6 inhibited acute and chronic inflammatory responses in mice as well as the upregulation of adhesion molecule expression in arterial endothelium. This action of beta-oxa-23:4n-6 required a functional 12- but not 5-lipoxygenase or cyclooxygenases, consistent with its metabolism via the 12-lipoxygenase pathway. Whereas beta-oxa-23:4n-6 did not affect the activation of mitogen-activated protein kinases by tumor necrosis factor, activation of the IkappaB kinase/nuclear factor kappaB pathway was selectively inhibited. These novel PUFAs could form the basis for a potential new class of pharmaceuticals for treating inflammatory diseases, including atherosclerosis.

n-3 fatty acids and gene expression

Accumulating evidence in both humans and animal models clearly indicates that a group of very-long-chain polyunsaturated fatty acids, the n-3 fatty acids (or omega-3), have distinct and important bioactive properties compared with other groups of fatty acids. n-3 Fatty acids are known to reduce many risk factors associated with several diseases, such as cardiovascular diseases, diabetes, and cancer. The mechanisms whereby n-3 fatty acids affect gene expression are complex and involve multiple processes. As examples, n-3 fatty acids regulate 2 groups of transcription factors, such as sterol-regulatory-element binding proteins and peroxisome proliferator-activated receptors, that are critical for modulating the expression of genes controlling both systemic and tissue-specific lipid homeostasis. Modulation of specific genes by n-3 fatty acids and cross-talk between these genes are responsible for many effects of n-3 fatty acids.

Decreased peroxisome proliferator activated receptor alpha is associated with bile duct injury in cystic fibrosis transmembrane conductance regulator-/- mice

BACKGROUND

Primary sclerosing cholangitis (PSC) is associated with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. As proof of concept that CFTR dysfunction plays a role in PSC, induction of colitis in cftr mice results in bile duct injury that can be prevented by pretreatment with docosahexaenoic acid (DHA).

OBJECTIVES

Determine whether 1) CFTR dysfunction in cftr mice through a reduction in peroxisome proliferator activated receptor (PPAR)alpha or gamma leads to bile duct injury and 2) whether DHA prevents bile duct injury through an increase in PPAR.

METHODS

Cftr and wild-type (WT) mice were treated with dextran sodium sulfate (DSS) to induce colitis with or without pretreatment with oral DHA. PPARalpha and gamma as well as tumor necrosis factor (TNF)alpha were analyzed in liver tissue. PPARalpha mice were also treated with DSS and histology examined.

RESULTS

PPARgamma mRNA levels were low, with DSS suppressing mRNA levels equally in WT and cftr mice. PPARalpha levels were no different between cftr and WT litter mates by reverse-transcription polymerase chain reaction. After DSS, WT mice showed a 9.3-fold increase in PPARalpha mRNA levels and increased nuclear localization compared with no DSS (P < 0.05), with no increase seen in cftr mice. This was not caused by changes in TNFalpha. DHA treatment led to 7.0-fold increase in PPARalpha mRNA levels in cftr mice (P < 0.01). PPARalpha mice treated with DSS did not develop bile duct injury, indicating that PPARalpha alone is not sufficient to cause bile duct inflammation.

CONCLUSION

DSS induced bile duct injury in cftr mice is associated with a defect in PPARalpha expression, which is reversed by DHA.

Effect of docosahexaenoic acid administration on plasma lipid profile and metabolic parameters of children with methylmalonic acidaemia

AIM

To evaluate the effect of administration of docosahexaenoic acid (DHA) on dyslipidaemia, plasma fatty acid composition and metabolic parameters of children with isolated methylmalonic acidaemia (MMA) (McKusick 25100).

METHODS

Four children (3 male, 1 female) with MMA (mut(0)), participated in a crossover, randomized study of DHA administration (25 mg/kg per day, divided into three daily doses). The control group comprised 56 healthy children, aged 10+/- 2.7 years, (51 male, 5 female), who were followed in our clinic owing to possible familial risk of cardiovascular disease.

RESULTS

The comparison of plasma fatty acid composition of children with MMA versus control children demonstrated that the patients had significantly higher values for oleic acid (p = 0.004) and linolenic acid (p = 0.008). No differences were observed in the levels of DHA and arachidonic acid. Plasma concentrations of insulin, glycine, ammonia, total cholesterol and cholesterol fractions did not change with DHA administration. No significant changes were observed in urinary excretion of methylmalonic acid. As expected, the percentage of DHA and n-3 fatty acids in plasma increased significantly after therapy (p = 0.005 and 0.014, respectively). The most remarkable result was a decrease of plasma levels of triglycerides after DHA therapy (p = 0.014).

CONCLUSION

As previously found in normal children, dietary supplementation with DHA decreases the triglyceride levels, normalizing the hypertriglyceridaemia of these children without any evidence of short-term adverse effects.

Anti-inflammatory effect of docosahexaenoic acid on cytokine-induced adhesion molecule expression in human retinal vascular endothelial cells

PURPOSE

Docosahexaenoic acid (DHA(22:6n3)), the principal n3-polyunsaturated fatty acid (PUFA) in the retina, has been shown to have a pronounced anti-inflammatory effect in numerous in vivo and in vitro studies. Despite the importance of vascular inflammation in diabetic retinopathy, the anti-inflammatory role of DHA(22:6n3) in cytokine-stimulated human retinal vascular endothelial cells (hRVECs) has not been addressed.

METHODS

Cytokine-induced expression of cell adhesion molecules (CAMs) was assessed by Western blot. The effect of DHA(22:6n3) on cytokine-induced nuclear factor (NF)-kappaB signaling was analyzed by Western blot analysis and electrophoretic mobility shift assay (EMSA).

RESULTS

Stimulation of hRVECs with VEGF(165), TNFalpha, or IL-1beta for 6 to 24 hours caused significant induction of intracellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression. Pretreatment of the cells with 100 microM of BSA-bound DHA(22:6n3) for 24 hours remarkably inhibited cytokine-induced CAM expression. IL-1beta, TNFalpha, and VEGF(165) induced nuclear translocation and binding of p65 and p50 NF-kappaB isoforms to the VCAM-1 promoter. DHA(22:6n3) pretreatment inhibited cytokine-induced NF-kappaB binding by 25% to 40%. Moreover, DHA(22:6n3) diminished IL-1beta induced phosphorylation of the inhibitor of nuclear factor (NF)-kappaB (I-kappaBalpha), thus preventing its degradation.

CONCLUSIONS

IL-1beta, TNFalpha, and VEGF(165) induced CAM expression in hRVECs through activation of the NF-kappaB pathway. DHA(22:6n3) inhibited cytokine induced CAM expression through suppression of NF-kappaB nuclear translocation and upstream I-kappaBalpha phosphorylation and degradation. DHA(22:6n3) could be an important anti-inflammatory agent in the face of increased cytokine production and CAM expression in the diabetic retina.

Is atrial fibrillation an inflammatory disorder?

There is mounting evidence to support the influence of inflammation in the pathogenesis of atrial fibrillation (AF). Indeed, AF is associated with increased levels of known inflammatory markers, even after adjustment for confounding factors. The renin-angiotensin-aldosterone system (RAAS) appears to play a key role in this process. Atrial biopsies from patients with AF have also confirmed the presence of inflammation. Furthermore, there is preliminary evidence to support a number of drug therapies that have the potential to reduce the clinical burden of AF. In this review, we present an overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies, such as the angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, steroids, fish oils, and vitamin C, that might be efficacious in the prevention of AF by modulating inflammatory pathways.

Differential effects of eicosapentaenoic and docosahexaenoic acids upon oxidant-stimulated release and uptake of arachidonic acid in human lymphoma U937 cells

The use of n-3 polyunsaturated fatty acids, as found in fish-oil derived dietary supplements, as anti-inflammatory agents is supported by a variety of biochemical and physiological data. Recent studies investigating the therapeutic potential of long chain (>C20) n-3 fatty acids in mental illness have lead to the conclusion, however, that not all n-3 fatty acid types are equally efficacious. In particular eicosapentaeoic acid (EPA) appears to possess antidepressant and antipsychotic activity, while docosahexaenoic acid (DHA) does not, an effect suggested to be due to a differential ability to antagonize arachidonic acid (AA)-dependent cell signalling. In this study, we examine the effect of EPA and DHA supplementation upon uptake and release of arachidonic acid stimulated by tert-butyl hydroperoxide/Fe2+ in U937 cells. Oxidant-stimulated 3H-AA release from cells was enhanced by pre-treatment with EPA, DHA and AA, but not stearic or oleic acids for 18 days, with the order of effect magnitude being EPA > DHA = AA. Supplementation of cells for 1 day gave qualitatively similar results, although the effect magnitude was smaller. To determine whether enhanced release was due to decreased reuptake of AA, cells were cultured in the presence of 10 microM fatty acids. Pre-treatment of cells with EPA, and to a lesser extent AA, but not DHA, inhibited uptake of 3H-AA measured subsequent to the removal of unesterified fatty acids. This study suggests that, in U937 cells, EPA can alter the rate of uptake and release of AA from phospholipids in an exposure time-dependent manner, whereas DHA has no or little effect. Our results predict that EPA will have a more pronounced effect upon AA-dependent processes compared to DHA, and suggests that the relative amounts of EPA and DHA in fish oil supplements may modify their biochemical, and potentially, behavioural effects.

Food components and immune function

PURPOSE OF REVIEW

Enhancing immune function or alternatively dampening inflammatory processes by specific food components has received a lot of interest. The purpose of this review is to summarize recent findings with the emphasis on underlying mechanisms.

RECENT FINDINGS

Dietary beta-glucans are relatively new candidates in the field of immune modulation by diet. In-vitro and animal studies suggest that beta-glucans shift inflammatory profiles to a Th1 type, which may enhance resistance against bacterial and parasitic infections. Regarding polyunsaturated fatty acids, there is evidence that n-3 fatty acids from fish oils (eicosapentaenoic acid and docosahexaenoic acid) dampen inflammatory responses. Whether eicosapentaenoic acid or docosahexaenoic acid is responsible for this phenomenon remains controversial. It is also inconclusive whether the plant-derived n-3 fatty acid alpha-linolenic acid has the same antiinflammatory effects as observed for fish oils. Saturated fatty acids may activate toll-like receptors and consequently the inflammatory pathway. The effect of total fat intake is controversial, since high-fat diets have been found to suppress immune function, while also improving intestinal barrier function. Finally, Gingko biloba was found to lower nuclear factor kappaB and activator protein 1 activation, possibly due to its high content of polyphenols.

SUMMARY

In this review we discuss the nutritional components able to enhance immune function or show antiinflammatory effects. It can be concluded that diet certainly has the potential to direct immune responses. Apart from studies on fish oils, however, evidence from human studies is limited.