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

Polyunsaturated Fatty Acids Influence LPS-Induced Inflammation of Fish Macrophages Through Differential Modulation of Pathogen Recognition and p38 MAPK/NF-κB Signaling

Polyunsaturated fatty acids (PUFAs) not only serve as essential nutrients but also function as modulators of the immune response in marine fish. However, their immunomodulatory mechanism is poorly understood given that the underlying regulation of the innate immune response in fish has not been fully elucidated. Hence, study of the innate immunity of fish could help elucidate the mechanism by which PUFAs affect the fish immune response. Here, we used combined transcriptome analysis and in vitro experimentation to study the mechanism of LPS-induced inflammation. Transcriptome profiling indicated that LPS elicited strong pro-inflammatory responses featuring high expression levels of pathogen recognition receptors (PRRs) and cytokines along with the activation of NF-κB and MAPK signaling pathways. The transcription factor p65 alone could increase the transcription of IL1β by binding to the promoter of IL1β, and this promoting effect disappeared after mutation or deletion of its binding sites. We then examined the effects of PUFAs on the levels of gene expression and the abundance of proteins of critical kinases associated with LPS-induced inflammation. We found that LA exerts pro-inflammatory response while ALA, EPA, and DHA induced anti-inflammatory effects by modulating the expression of PRRs, phosphorylation of IKK and p38, and the nuclear translocation of p65. Overall, this study advances our understanding of the regulatory mechanisms by which PUFAs regulate LPS-induced inflammation in a non-model fish species.

Efficacy of ethyl-EPA as a treatment for Huntington disease: a systematic review and meta-analysis

OBJECTIVE

After MRI studies suggested the efficacy of ethyl-EPA in reducing the progressive brain atrophy in Huntington disease (HD), trials were conducted to test its efficacy as a treatment for HD. Trials that continued for 6 months did not find any significant improvement, urging discontinuation of the drug. However, trials that continued for 12 months indicated improvement of motor functions in these patients.

METHODS

We searched 12 electronic databases to find randomised clinical trials relevant to our inclusion criteria. After screening, only five papers were included. Continuous and binary variables were analysed to compute the pooled mean difference (MD) and risk ratio (RR), respectively. Quality effect model meta-analysis was used as a post hoc analysis for studies at 12 months.

FINDINGS

Meta-analysis indicated that ethyl-eicosapentaenoic acid (EPA) has no significant effect on any scale of HD at 6 months. At 12 months, two studies suggested significant improvements of the Total Motor Score and Total Motor Score-4 in both fixed and quality effect models [MD = -2.720, 95% CI (-4.76, -.68), p = 0.009; MD = -2.225, 95% CI (-3.842, -0.607), p = 0.007], respectively. Maximal chorea score showed significant results [MD = -1.013, 95% CI (-1.793, -0.233), p = 0.011] in only fixed-effect model, while no improvement was detected for Stroop colour naming test or symbol digit modality.

CONCLUSION

Meta-analysis indicated a significant improvement of motor scores only after 12 months. These results should be interpreted cautiously because only two studies had assessed the efficacy of ethyl-EPA after 12 months with one of them having a 6-month open-label phase.

Effects of omega-3 on matrix metalloproteinase-9, myoblast transplantation and satellite cell activation in dystrophin-deficient muscle fibers

In Duchenne muscular dystrophy (DMD), lack of dystrophin leads to progressive muscle degeneration, with DMD patients suffering from cardiorespiratory failure. Cell therapy is an alternative to life-long corticoid therapy. Satellite cells, the stem cells of skeletal muscles, do not completely compensate for the muscle damage in dystrophic muscles. Elevated levels of proinflammatory and profibrotic factors, such as metalloproteinase 9 (MMP-9), impair muscle regeneration, leading to extensive fibrosis and poor results with myoblast transplantation therapies. Omega-3 is an anti-inflammatory drug that protects against muscle degeneration in the mdx mouse model of DMD. In the present study, we test our hypothesis that omega-3 affects MMP-9 and thereby benefits muscle regeneration and myoblast transplantation in the mdx mouse. We observe that omega-3 reduces MMP-9 gene expression and improves myoblast engraftment, satellite cell activation, and muscle regeneration by mechanisms involving, at least in part, the regulation of macrophages, as shown here with the fluorescence-activated cell sorting technique. The present study demonstrates the benefits of omega-3 on satellite cell survival and muscle regeneration, further supporting its use in clinical trials and cell therapies in DMD.

Omega-3 polyunsaturated fatty acids mitigate blood-brain barrier disruption after hypoxic-ischemic brain injury

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been shown to protect the neonatal brain against hypoxic/ischemic (H/I) injury. However, the mechanism of n-3 PUFA-afforded neuroprotection is not well understood. One major determinant of H/I vulnerability is the permeability of the blood-brain barrier (BBB). Therefore, we examined the effects of n-3 PUFAs on BBB integrity after neonatal H/I. Female rats were fed a diet with or without n-3 PUFA enrichment from day 2 of pregnancy to 14days after parturition. H/I was introduced in 7day-old offspring. We observed relatively rapid BBB penetration of the small molecule cadaverine (640Da) at 4h post-H/I and a delayed penetration of larger dextrans (3kD-40kD) 24-48h after injury. Surprisingly, the neonatal BBB was impermeable to Evans Blue or 70kD dextran leakage for up to 48h post-H/I, despite evidence of IgG extravasation at this time. As expected, n-3 PUFAs ameliorated H/I-induced BBB damage, as shown by reductions in tracer efflux and IgG extravasation, preservation of BBB ultrastructure, and enhanced tight junction protein expression. Furthermore, n-3 PUFAs prevented the elevation in matrix metalloproteinase (MMP) activity in the brain and blood after H/I. Thus, n-3 PUFAs may protect neonates against BBB damage by blunting MMPs activation after H/I.

Transcriptional response of porcine skeletal muscle to feeding a linseed-enriched diet to growing pigs

BACKGROUND

To investigate the effect of feeding a linseed-enriched diet to growing-finishing pigs on gene expression in skeletal muscle, pigs were fed with a linseed-enriched diet for 0, 30, 60 and 90 d. Transcriptional profiles of longissimus dorsi muscle were measured using Affymetrix Genechip.

RESULTS

Results showed that 264 genes were identified as differentially expressed genes (DEGs). The strongest transcriptional response was clearly observed at 30 d. DEGs were assigned to several main functional terms, including transcription, apoptosis, intracellular receptor-mediated signaling, muscle organ development, fatty acid metabolic process, cell motion, regulation of glucose metabolic process, spermatogenesis and regulation of myeloid cell differentiation. We also found that transcriptional changs of several transcription cofactors might contribute to n-3 PUFAs regulated gene expression. In addition, the increased expression of IGF-1, insulin signaling pathway and the metabolism of amino acids might involve in the muscle growth induced by feeding a linseed-enriched diet. The results also provide the new evidence that the expression changes of PTPN1, HK2 and PGC-1α might contribute to the regulation of insulin sensitivity by n-3 PUFAs.

CONCLUSIONS

Our finding provided correlative evidence that feeding the linseed enriched diet affact expression of genes involved in insulin signaling pathway and the metabolism of amino acids.

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

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

Differences in lipopolysaccharide- and lipoteichoic acid-induced cytokine/chemokine expression

Purpose

To investigate differences in cytokine/chemokine release in response to lipoteichoic acid (LTA) or lipopolysaccharide (LPS) and contributing cellular mechanisms, in order to improve understanding of the pathogenesis of sepsis.

Methods

Levels of cytokines/chemokines were measured in plasma and peritoneal lavage fluid of 10-week-old male mice (C57/B16) following intraperitoneal injection of LTA or LPS (250 µg), and in supernatants of murine J774.2 cells, immortalised blood monocytes, or isolated human monocytes treated with LTA or LPS (0–10 µg/ml). The role of cytokine/chemokine messenger RNA (mRNA) stability versus nuclear factor-kappaB (NF-κB) and activator protein-1 (AP-1) in mediating cytokine/chemokine release in J774 cells was also assessed.

Results

In mice, plasma levels of keratinocyte-derived chemokine (KC), macrophage inflammatory protein (MIP)-2, interleukin (IL)-10, interferon (IFN)-γ and tumour necrosis factor-alpha (TNF-α) and peritoneal lavage fluid levels of KC, MIP-2 and TNF-α increased significantly 1 h after LPS. Only KC and MIP-2 levels increased 1 h after LTA. LPS-treated (10 μg/ml) J774 cells released MIP-2, IL-10, IFN-γ and TNF-α but not KC (24 h), whereas cells treated with 10 μg/ml LTA released only MIP-2. LPS-stimulated human monocytes released IL-10 and IL-8 (24 h); by contrast, LTA-treated cells released only IL-8. LPS and LTA activated NF-κB and AP-1 in J774 cells. The protein synthesis inhibitor cycloheximide abolished LPS-induced IL-10 mRNA expression and increased LTA- and LPS-induced mRNA for MIP-2 in J774 cells.

Conclusion

LTA and LPS, at clinically relevant concentrations, induced differential cytokine/chemokine release in vitro and in vivo, via effects distal to activation of NF-κB/AP-1 that might include chromatin remodelling or mRNA stability.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-011-2444-5) contains supplementary material, which is available to authorized users.

n-3 Fatty acids block TNF-α-stimulated MCP-1 expression in rat mesangial cells

Monocyte chemoattractant protein 1 (MCP-1) is a CC cytokine that fundamentally contributes to the pathogenesis of inflammatory renal disease. MCP-1 is highly expressed in cytokine-stimulated mesangial cells in vitro and following glomerular injury in vivo. Interventions to limit MCP-1 expression are commonly effective in assorted experimental models. Fish oil, an abundant source of n-3 fatty acids, has anti-inflammatory properties, the basis of which remains incompletely defined. We examined potential mechanisms whereby fish oil reduces MCP-1 expression and thereby suppresses inflammatory responses to tissue injury. Cultured mesangial cells were treated with TNF-α in the presence of the n-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA); equimolar concentrations of the n-6 fatty acids LA and OA served as controls. MCP-1 mRNA expression was assessed by Northern blotting, and transcriptional activity of the MCP-1 promoter was assessed by transient transfection. The involvement of the ERK and NF-κB pathways was evaluated through transfection analysis and the use of the MEK inhibitor U0126. DHA and EPA decreased TNF-α-stimulated MCP-1 mRNA expression by decreasing transcription of the MCP-1 gene. DHA and EPA decreased p-ERK expression and nuclear translocation of NF-κB, both of which are necessary for TNF-α-stimulated MCP-1 expression. Both NF-κB and AP-1 sites were involved in transcriptional regulation of the MCP-1 gene by DHA and EPA. We conclude that DHA and EPA inhibit TNF-α-stimulated transcription of the MCP-1 gene through interaction of signaling pathways involving ERK and NF-κB. We speculate that such effects may contribute to the salutary effect of fish oil in renal and vascular disease.

Complementary and alternative medicine for the treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic disabling disease of the CNS that affects people during early adulthood. Despite several US FDA-approved medications, the treatment options in MS are limited. Many people with MS explore complementary and alternative medicine (CAM) treatments to help control their MS and treat their symptoms. Surveys suggest that up to 70% of people with MS have tried one or more CAM treatment for their MS. People with MS using CAM generally report deriving some benefit from the therapies. The CAM therapies most frequently used include diet, omega-3 fatty acids and antioxidants. There is very limited research evaluating the safety and effectiveness of CAM in MS. The most promising among CAM therapies that warrant further investigation are a low-fat diet, omega-3 fatty acids, lipoic acid and vitamin D supplementation as potential anti-inflammatory and neuroprotective agents in both relapsing and progressive forms of MS. There is very limited research evaluating the safety and effectiveness of CAM in MS. However, in recent years, the NIH and the National MS Society have been actively supporting the research in this very important area.

Omega-3 fatty acid supplementation decreases matrix metalloproteinase-9 production in relapsing-remitting multiple sclerosis

OBJECTIVES

The primary objective was to evaluate the effect of omega-3 fatty acids (omega-3 FA) on matrix metalloproteinase-9 (MMP-9) production by immune cells in multiple sclerosis (MS). Quality of life, fatty acid levels, and safety were also evaluated.

MATERIALS AND METHODS

Ten participants with relapsing-remitting MS (RRMS) received omega-3 FA supplementation (9.6g/day fish oil) in an open-label study. Participants were evaluated at four time points, baseline, after 1 month of omega-3 FA supplementation, after 3 months of omega-3 FA supplementation, and after a 3-month wash out.

RESULTS

Immune cell secretion of MMP-9 decreased by 58% after 3 months of omega-3 FA supplementation when compared with baseline levels (p<0.01). This effect was coupled with a significant increase in omega-3 FA levels in red blood cell membranes.

CONCLUSIONS

Omega-3 FA significantly decreased MMP-9 levels in RRMS and may act as an immune-modulator that has potential therapeutic benefit in MS patients.

Eicosapentaenoic acid is more effective than docosahexaenoic acid in inhibiting proinflammatory mediator production and transcription from LPS-induced human asthmatic alveolar macrophage cells

BACKGROUND & AIMS

The purpose of the study was to determine which of the active constituents of fish oil, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), is most effective in suppressing proinflammatory mediator generation and cytokine expression from LPS-stimulated human asthmatic alveolar macrophages (AMphi).

METHODS

The AMphi were obtained from twenty-one asthmatic adults using fiberoptic bronchoscopy. Cells were pretreated with DMEM, pure EPA, an EPA-rich media (45% EPA/10% DHA), pure DHA, a DHA-rich media (10% EPA/50% DHA) or Lipovenos (n-6 PUFA), and then exposed to Dulbecco's Modified Eagle's Medium (DMEM) (-) or LPS (+). Supernatants were analyzed for leukotriene (LT)B(4), prostaglandin (PG)D(2), tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta production. Detection of TNF-alpha and IL-1beta mRNA expression levels was quantified by reverse transcriptase polymerase chain reaction.

RESULTS

120 microM pure EPA and EPA-rich media significantly (p<0.05) suppressed TNF-alpha and IL-1beta mRNA expression and the production of LTB(4), PGD(2) and TNF-alpha and IL-1beta in LPS-stimulated primary AMphi cells obtained from asthmatic patients to a much greater extent than 120 microM pure DHA and DHA-rich media respectively.

CONCLUSIONS

This study has shown for the first time that EPA is a more potent inhibitor than DHA of inflammatory responses in human asthmatic AMphi cells.

Inhibition of inflammatory response in transgenic fat-1 mice on a calorie-restricted diet

Both n-3 fatty acids (n-3 FA) and calorie-restriction (CR) exert anti-inflammatory effects in animal models of autoimmunity and inflammation. In the present study we investigated the synergistic anti-inflammatory effects of n-3 FA and CR on LPS-mediated inflammatory responses using fat-1 transgenic mice that generate n-3 FA endogenously. Wild-type (WT) and fat-1 mice were maintained on ad libitum (AL) or CR (40% less than AL) diet for 5 mo; splenocytes were cultured in vitro with/without LPS. Our results show: (i) no difference in body weights between WT and fat-1 mice on AL or CR diets, (ii) lower n-6/n-3 FA ratio in splenocytes from fat-1 mice on both AL and CR diets, (iii) significant reduction in NF-kappaB (p65/p50) and AP-1 (c-Fos/c-Jun) DNA-binding activities in splenocytes from fat-1/CR mice following LPS treatment, and (iv) significant reduction in kappaB- and AP-1-responsive IL-6 and TNF-alpha secretion following LPS treatment in splenocytes from fat-1/CR mice. The inhibition of LPS-mediated effects was more pronounced in fat-1/CR mice when compared to fat-1/AL or WT/CR mice. These data show that transgenic expression of fat-1 results in decreased pro-inflammatory n-6 FA, and demonstrate for the first time that splenocytes from fat-1 mice on CR diet exhibit reduced pro-inflammatory response when challenged with LPS. These results suggest that n-3 lipids with moderate CR may confer protection in autoimmune and inflammatory diseases.

Contribution of polyunsaturated fatty acids to Shiga toxin cytotoxicity in human renal tubular epithelium-derived cells

Shiga toxin (Stx) produced by enterohemorrhagic Escherichia coli is a critical factor in the onset of hemolytic uremic syndrome. The current study was designed to assess whether n-3 and (or) n-6 polyunsaturated fatty acids (PUFA) act as a valuable adjunct to prevent the cell injury of renal tubule cells in the emergence of HUS. The target cells, ACHN cells derived from human tubule epithelium, were cultured with each PUFA, then exposed to Stx-1 or Stx-2. The rank order of potency of PUFA to inhibit the cell death caused by each toxin was as follows: EPA > AA = DHA >> LNA. There were dose-response relations in the efficacy of each PUFA. No prophylactic effect was found in the cultures with LA. Immunofluorescence assays revealed that both the expression of the toxin receptor on ACHN cells and binding between the toxin and cells were unaffected by the PUFA. These results suggest that EPA is the most efficacious PUFA against the renal tubule cell injury caused by Stx, which may be assigned to an alteration in the intracellular pathway leading to cell death.

How dietary arachidonic- and docosahexaenoic- acid rich oils differentially affect the murine hepatic transcriptome

Introduction

Herein, we expand our previous work on the effects of long chain polyunsaturated fatty acids (LC-PUFA) on the murine hepatic transcriptome using novel statistical and bioinformatic approaches for evaluating microarray data. The analyses focuses on key differences in the transcriptomic response that will influence metabolism following consumption of FUNG (rich in 20:4n6), FISH (rich in 20:5n3, 22:5n3, and 22:6n3) and COMB, the combination of the two.

Results

Using a variance-stabilized F-statistic, 371 probe sets (out of 13 K probe sets in the Affymetrix Mu11K chip set) were changed by dietary treatment (P < 0.001). Relative to other groups, COMB had unique affects on murine hepatic transcripts involved in cytoskeletal and carbohydrate metabolism; whereas FUNG affected amino acid metabolism via CTNB1 signaling. All three diets affected transcripts linked to apoptosis and cell proliferation, with evidence FISH may have increased apoptosis and decreased cell proliferation via various transcription factors, kinases, and phosphatases. The three diets affected lipid transport, lipoprotein metabolism, and bile acid metabolism through diverse pathways. Relative to other groups, FISH activated cyps that form hydroxylated fatty acids known to affect vascular tone and ion channel activity. FA synthesis and delta 9 desaturation were down regulated by COMB relative to other groups, implying that a FA mixture of 20:4n6, 20:5n3, and 22:6n3 is most effective at down regulating synthesis, via INS1, SREBP, PPAR alpha, and TNF signaling. Heme synthesis and the utilization of heme for hemoglobin production were likely affected by FUNG and FISH. Finally, relative to other groups, FISH increased numerous transcripts linked to combating oxidative such as peroxidases, an aldehyde dehydrogenase, and heat shock proteins, consistent with the major LC-PUFA in FISH (20:5n3, 22:5n3, 22:6n3) being more oxidizable than the major fatty acids in FUNG (20:4n6).

Conclusion

Distinct transcriptomic, signaling cascades, and predicted affects on murine liver metabolism have been elucidated for 20:4n6-rich dietary oils, 22:6n3-rich oils, and a surprisingly distinct set of genes were affected by the combination of the two. Our results emphasize that the balance of dietary n6 and n3 LC-PUFA provided for infants and in nutritional and neutraceutical applications could have profoundly different affects on metabolism and cell signaling, beyond that previously recognized.

Eicosapentaenoic acid prevents endothelin-1-induced cardiomyocyte hypertrophy in vitro through the suppression of TGF-beta 1 and phosphorylated JNK

The cardiovascular benefit of fish oil in humans and experimental animals has been reported. Endothelin (ET)-1 is a well-known cardiac hypertrophic factor. However, although many studies link a fish oil extract, eicosapentaenoic acid (EPA), to cardiac protection, the effects of EPA on cardiac hypertrophy and underlying mechanism(s) are unclear. The present study investigated whether EPA prevents ET-1-induced cardiomyocyte hypertrophy; the potential pathways likely to underlie such an effect were also investigated. Cardiomyocytes were isolated from neonatal rat heart, cultured for 3 days, and then treated for 24 h with vehicle only (control), treated with 0.1 nM ET-1 only, or pretreated with 10 microM EPA and then treated with 0.1 nM ET-1. The cells were harvested, and changes in cell surface area, protein synthesis, expression of a cytoskeletal (alpha-actinin) protein, and cell signaling were analyzed. ET-1 induced a 97% increase in cardiomyocyte surface area, a 72% increase in protein synthesis rate, and an increase in expression of alpha-actinin and signaling molecule [transforming growth factor-beta 1 (TGF-beta 1), c-Jun NH2-terminal kinase (JNK), and c-Jun]. Development of these ET-1-induced cellular changes was attenuated by EPA. Moreover, the hypertrophied cardiomyocytes showed a 1.5- and a 1.7-fold increase in mRNA expression of atrial and brain natriuretic peptides, the classical molecular markers of cardiac hypertrophy, respectively; these changes were also suppressed by EPA. Here we show that ET-1 induces cardiomyocyte hypertrophy and expression of hypertrophic markers, possibly mediated by JNK and TGF-beta 1 signaling pathways. These ET-1-induced effects were blocked by EPA, a major fish oil ingredient, suggesting that fish oil may have beneficial protective effects on cardiac hypertrophy.

Eicosapentaenoic acid inhibits UV-induced MMP-1 expression in human dermal fibroblasts

Ultraviolet (UV) irradiation regulates UV-responsive genes, including matrix metalloproteinases (MMPs). Moreover, UV-induced MMPs cause connective tissue damage and the skin to become wrinkled and aged. Here, we investigated the effect of eicosapentaenoic acid (EPA), a dietary omega-3 fatty acid, on UV-induced MMP-1 expression in human dermal fibroblasts (HDFs). We found that UV radiation increases MMP-1 expression and that this is mediated by p44 and p42 MAP kinase (ERK) and Jun-N-terminal kinase (JNK) activation but not by p38 activation. Pretreatment of HDFs with EPA inhibited UV-induced MMP-1 expression in a dose-dependent manner and also inhibited the UV-induced activation of ERK and JNK by inhibiting ERK kinase (MEK1) and SAPK/ERK kinase 1 (SEK1) activation, respectively. Moreover, inhibition of ERK and JNK by EPA resulted in the decrease of c-Fos expression and c-Jun phosphorylation/expression induced by UV, respectively, which led to the inhibition of UV-induced activator protein-1 DNA binding activity. This inhibitory effect of EPA on MMP-1 was not mediated by an antioxidant effect. We also found that EPA inhibited 12-O-tetradecanoylphorbol-13-acetate- or tumor necrosis factor-alpha-induced MMP-1 expression in HDFs and UV-induced MMP-1 expression in HaCaT cells. In conclusion, our results demonstrate that EPA can inhibit UV-induced MMP-1 expression by inhibiting the MEK1/ERK/c-Fos and SEK1/JNK/c-Jun pathways. Therefore, EPA is a potential agent for the prevention and treatment of skin aging.