Oral evening-primrose-seed oil improves atopic eczema

Dietary intake of concentrated gamma-linolenic acid (GLA)-enriched oil suppresses cutaneous level of dihomo-gamma-linolenic acid (DGLA): possible in vivo inhibition of microsomal elongation of GLA to DGLA

The dietary supplementation of normal guinea-pig diet with moderate levels of vegetable oils containing gamma-linolenic acid (GLA) is associated with elevation of epidermal levels of dihomo-gamma-linolenic acid (DGLA) and 15-hydroxyeicosatrienoic acid (15-lipoxygenase product of DGLA). However, supplementation of diet with higher level (70%) of GLA (GLA-70) resulted in marked decrease of epidermal level of DGLA. This nutritional observation prompted us to investigate in vitro the effects of varying concentrations of polyunsaturated fatty acids (PUFAs) on rat liver microsomal chain elongation of GLA into DGLA. Our data revealed that low concentrations of GLA (less than 100 microM) are stimulatory on the chain elongation while higher concentrations (greater than 100 microM) are inhibitory. The 18-carbon linoleic acid (precursor of GLA) was also markedly inhibitory at high concentrations. Interestingly, the longer chain 20-carbon n-3 PUFAs: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exerted negligible effect. The results suggest that increased systemic presence of free PUFAs, such as may occur in vivo after dietary intake of high n-6 PUFA-containing vegetable oils, may explain the decreased level of DGLA in the epidermal tissue.

Lipids of selected molds grown for production of n-3 and n-6 polyunsaturated fatty acids

The lipid classes and component fatty acids of seven fungi were examined. Three marine fungi, Thraustochytrium aureum, Thraustochytrium roseum and Schizochytrium aggregatum (grown at 30, 25 and 25 degrees C, respectively), produced less than 10% lipid but contained docosahexaenoic acid (DHA) up to 30% and eicosapentaenoic acid (EPA) up to 11% of the total fatty acids. Mortierella alpinapeyron produced 38% oil containing solely n-6 polyunsaturated fatty acids (PUFA) with arachidonic acid (AA) at 11% of the total fatty acids. Conidiobolus nanodes and Entomorphthora exitalis produced 25% oil and contained both n-3 and n-6 PUFA, with AA at 16% and 18%, respectively. Saprolegnia parasitica produced 10% oil and contained AA and EPA, respectively, at 19% and 18%. The triacylglycerol fraction always represented the major component at between 44% and 68% of the total lipid. Each fungus, except T. aureum, had the greatest degree of fatty acid unsaturation in the phospholipid fraction. The triacylglycerol fraction of T. aureum was the most unsaturated with DHA representing 29% (w/w) of all fatty acids present. The presence of the enzyme ATP:citrate lyase correlated with the ability of molds to accumulate more than 10% (w/w) lipid when the fungi were grown in nitrogen-limiting media. In those molds that failed to accumulate more than 10% lipid, the enzyme was absent.

Gamma linolenic acid (GLA) content of encapsulated evening primrose oil products

The fatty acid composition of 16 brands of evening primrose oil (EPO) capsules was determined by capillary gas chromatography. Fourteen of these EPO brands contained gamma-linolenic acid (GLA) levels between 7% and 10% (mean, 8.7; range, 1.9-10.5%) and there was generally good agreement between the level of GLA claimed by the manufacturer and the level determined by analysis. Low levels of the monoenes 22:1 and 24:1 found in some brands may indicate contamination of EPO with borage oil.

Cyclic adenosine monophosphate-phosphodiesterase activity in cultured keratinocytes from patients with atopic eczema

A number of previous studies have documented an increase in cyclic adenosine monophosphate-phosphodiesterase activity in patients with atopic dermatitis. We have studied the activity of this enzyme in keratinocytes cultured from patients with atopic dermatitis compared to keratinocytes from non-atopic controls. Results show that these pure preparations of keratinocytes express only one form of cyclic adenosine monophosphate phosphodiesterase with a Km of 1.9 microM, and a Vmax of 17 pmol/min/mg of substrate converted. We conclude that cyclic adenosine monophosphate-phosphodiesterase activity in cultured keratinocytes from patients with atopic eczema does not differ from controls.

Supplementation with evening primrose oil in atopic dermatitis: effect on fatty acids in neutrophils and epidermis

We investigated the effect of oral supplementation with evening primrose oil, containing 72% linoleic acid (18:2n-6) and 10% gamma-linolenic acid (18:3n-6), on the epidermal and neutrophil phospholipid fatty acid composition in 15 patients with atopic dermatitis (AD). Three different dose levels, 4, 8 and 12 capsules per day containing 0.5 g oil, were given to three groups of patients. The only n-6 fatty acid showing a significant (p less than 0.05) dose-related increase was dihomo-gamma-linolenic acid (20:3n-6) in neutrophil phospholipids. The highest dose increased dihomo-gamma-linolenic acid by 45% in neutrophil phospholipids, by 46% in lesion-free epidermal phosphatidylcholine, and by 15% in lesion-free epidermal phosphatidylethanolamine. In both lesional and lesion-free epidermis, supplementation resulted in a rise in the ratio between n-6 and monounsaturated fatty acids, reaching significance (p less than 0.05) in lesional epidermis. This study shows that moderate and favorable fatty acid changes can be obtained in the epidermis of AD patients, when given 6 g per day of oil rich in n-6 fatty acids. The abnormal lipid and fatty acid pattern of the atopic epidermis may be involved in the pathogenesis of the disease, and should therefore be the target for future therapeutic approaches with fatty acid supplements.

The effects of evening primrose oil, safflower oil and paraffin on plasma fatty acid levels in humans: choice of an appropriate placebo for clinical studies on primrose oil

In a number of diseases, plasma levels of linoleic acid are normal or elevated while those of gamma-linolenic acid (18:3n-6, GLA) and further metabolites are below normal. Evening primrose oil (EPO), similar to safflower oil (SFO) except that it contains 8-9% of 18:3n-6, has been proposed as a therapeutic agent in these diseases, such as atopic eczema. There is argument as to whether an appropriate placebo for clinical studies on EPO should be an inert material such as paraffin, or a linoleic acid--containing oil such as SFO. We have therefore compared in normal humans the effects on plasma fatty acids of administering EPO, SFO and paraffin for 10 days. Paraffin had no effect on any fatty acid in any fraction. EPO raised the level of 20:3n-6 (dihomo-gamma-linolenic acid, DGLA) the immediate metabolite of GLA but had no significant effect on arachidonic acid. In surprising contrast, SFO raised the levels of linoleic and of arachidonic acids, without raising those of DGLA. This suggests that linoleic acid may be rapidly converted to arachidonic acid by a tightly linked enzyme sequence: GLA, in contrast, may be rapidly converted to DGLA but then only slowly on to arachidonic acid. These results are consistent with recent in vitro observations by others on rat hepatocytes and human fibroblasts.

Disturbances of essential fatty acid- and prostaglandin E-mediated immunoregulation in atopy

Impaired suppressor T lymphocyte maturation and function in atopic individuals are explained by an insufficient transmission of prostaglandin E (PGE) signals during thymic lymphocyte differentiation as well as an impaired ability of the atopic immune system to activate suppressor T-cells by PGE-mediated feed back mechanisms. We demonstrate that spontaneous in vitro immunoglobulin E synthesis of atopic peripheral blood mononuclear cells could be suppressed by the addition of 10(-6) M to 10(-5) M PGE1 or PGE2. Decreased plasma and breast milk levels of PGE-precursor fatty acids and reduced numbers of PGE2-receptors on atopic lymphocytes have been observed in atopic individuals. These insights might offer a novel approach for the prevention of atopic disease by substitution of the atopic pregnant and nursing woman and her newborn infant with long chain omega-6-fatty acids.

Dietary supplementation with ethyl ester concentrates of fish oil (n-3) and borage oil (n-6) polyunsaturated fatty acids induces epidermal generation of local putative anti-inflammatory metabolites

Clinical reports have attributed the amelioration of chronic inflammatory skin disorders to the presence of certain polyunsaturated fatty acids (PUFA) in dietary oils. To test the hypothesis of a local modulatory effect of these PUFA in the epidermis, the basal diet of normal guinea pigs was supplemented with ethyl esters of either fish oil [rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] or borage oil [rich in gamma-linolenic acid (GLA)]. Our data demonstrated that dietary oils influence the distribution of PUFA in epidermal phospholipids and the epidermal levels of PUFA-derived hydroxy fatty acids. Specifically, animals supplemented with ethyl esters of fish oil markedly incorporated EPA and DHA into epidermal phospholipids, which paralleled the epidermal accumulation of 15-hydroxyeicosapentaenoic acid (15-HEPE) and 17-hydroxydocosahexaenoic acid (17-HDoHE). Similarly, animals supplemented with esters of borage oil preferentially incorporated dihomogammalinolenic acid (DGLA), the epidermal elongase product of GLA, into the epidermal phospholipids, which also was accompanied by epidermal accumulation of 15-hydroxyeicosatrienoic acid (15-HETrE). By factoring the epidermal levels of the 15-lipoxygenase products and their relative inhibitory potencies, we evolved a measure of the overall potential of dietary oils to exert local anti-inflammatory effect. For example, the leukotriene inhibition potentials (LIP) of both fish oil and borage oil were greatly enhanced when compared to controls. Thus, the altered profiles of epidermal 15-lipoxygenase products generated from particular dietary oils may be responsible, at least in part, for reported ameliorative effects of oils on chronic inflammatory skin disorders.

Effects of dietary supplementation with eicosapentaenoic acid or gamma-linolenic acid on neutrophil phospholipid fatty acid composition and activation responses

Previous data that alimentation with fish oil rich in eicosapentaenoic acid (EPA; 20:n-3) or vegetable oil rich in gamma-linolenic acid (GLA; 18:3n-6) can reduce symptoms of inflammatory skin disorders lead us to determine the effects of dietary supplements of oils rich in EPA or GLA on guinea pig (GP) neutrophil (PMN) membrane potential (delta gamma), secretion, and superoxide (O2-) responses. Weanling GPs were initially fed diets supplemented with olive oil (less than 0.1% EPA; less than 0.1% GLA) for 2 weeks, followed by a crossover by two sets of animals to diets supplemented with fish oil (19% EPA) or borage oil (25% GLA). At 4-week intervals, 12% sterile casein-elicited peritoneal neutrophils (PMN) were assessed for membrane polyunsaturated fatty acid (PUFA) profiles and FMLP-, LTB4-, and PMA-stimulated delta gamma changes, changes in flow cytometrically measured forward scatter (FWD-SC) (shape change), 90 degrees scatter (90 degrees -SC) in cytochalasin B-pretreated-PMN (secretion response), and superoxide responses, GP incorporated EPA and GLA (as the elongation product, dihomo-GLA or DGLA) into their PMN phospholipids by 4 weeks. The peritoneal PMN of all groups demonstrated broad resting FWD-SC and poor activation-related FWD-SC increases, suggesting in vivo activation. While secretion was comparable in the three groups in response to FMLP, there was a trend toward inhibition of LTB4-stimulated 90 degrees -SC loss in both fish and borage oil groups. This was significant only with borage oil (21.7 +/- 2.1 vs 15.3 +/- 1.2% loss of baseline 90 degrees -SC, olive vs borage: P = 0.03). PMN from borage- and fish oil-fed GPs showed a progressively lower O2- response to FMLP than the olive oil group (73.9 +/- 3.9 and 42.9 +/- 6.8% of olive oil response for borage and fish oils, respectively; P less than 0.005 and P less than 0.01, respectively, at 12 weeks), while PMA-stimulated O2- was inhibited only in the fish oil-fed group and only at 12 weeks (62.0 +/- 2.7% of control; P less than 0.025). We conclude that dietary supplementation with oils rich in PUFAs can modify PMN activation responses.

Post-viral fatigue syndrome, viral infections in atopic eczema, and essential fatty acids

Three clinical observations relating to viral infections are well-known but poorly understood. These are: the susceptibility of people with atopic eczema to viral infections; the occasional precipitation of an atopic syndrome by viral infections; the occurrence of a fatigue syndrome following viral infections. A unifying hypothesis is presented which explains these observations in terms of the interactions between viral infections and essential fatty acid (EFA) metabolism. Key elements of the hypothesis are the facts that interferon requires 6-desaturated EFAs in order to exert its anti-viral effects, that people with atopic eczema have low levels of 6-desaturated EFAs, and that viruses, as part of their attack strategy, may reduce the ability of cells to make 6-desaturated EFAs. The hypothesis has practical implications for the treatment of patients with viral infections.

Conversion of dihomo-gamma-linolenic acid to mono- and dihydroxy acids by potato lipoxygenase: evidence for the formation of 8,9-leukotriene A3

Evidence for the formation of a positional isomer of leukotriene (LT) C3 (8,9-LTC3) from dihomo-gamma-linolenic acid has been published (Hammarström, S. J. Biol. Chem. 256, 7712-7714, 1981). This report describes the conversion of dihomo-gamma-linolenic acid to a postulated intermediate in former reaction, 8,9-LTA3, by purified lipoxygenase from potato tubers. 8(S)-Hydroperoxyeicosatrienoic acid (8(S)-HPETrE) was the most abundant dioxygenation product formed followed by 11-, 15-, and 12-HPETrEs (in decreasing order of abundance). In addition, 8(S),15(S)- plus 8(S), 15(R)-dihydroperoxyeicosatetraenoic acid (DiHPE-TrE) (EZE), and 8(S),15(S)- plus 8(S),15(R)-dihydroxy-eicosatetraenoic acid (DiHETrE) (EEE) were generated. Under anaerobic conditions only the latter two isomers of 8,15-DiHETrE (EEE) were obtained from 8-HPETrE. The results suggest that 8,9-LTA3 is synthesized by the sequential action of 8- and 11-lipoxygenase activities associated with the potato enzyme.

Essential-fatty-acid metabolites in plasma phospholipids in patients with ichthyosis vulgaris, acne vulgaris and psoriasis

The concentration of essential fatty acids (EFAs) and their metabolites in plasma phospholipids were measured by gas chromatography in normal individuals, and in patients with ichthyosis vulgaris, acne vulgaris or psoriasis. In all three patient groups, concentrations of arachidonic acid (20:4 omega 6) and docosapentaenoic acid (22:5 omega 6) were significantly below those in controls, suggesting that these abnormalities may occur in many skin diseases. Concentrations of dihomogammalinolenic acid (20:3 omega 6) were low in ichthyosis, normal in acne and elevated in psoriasis. Thus ichthyosis, acne and psoriasis each had a characteristic pattern of EFA metabolites.

Effect of n-3 fatty acid supplement to patients with atopic dermatitis

The effects of dietary supplement with n-3 fatty acids to patients with atopic dermatitis were investigated in a 12-week, prospective, double-blind study. The experimental group received daily 10 g of fish oil, containing 3 g n-3 fatty acids, of which eicosapentaenoic acid represented about 1.8 g. The controls received an isoenergetic placebo supplement containing olive oil. Compliance was monitored by gas chromatographic analysis of fatty acid pattern in serum phospholipids. Results favoured the experimental group with regard to scale (P less than 0.05), itch (P less than 0.05) and overall subjective severity (P less than 0.02) as compared to the controls.

Guinea pig epidermis generates putative anti-inflammatory metabolites from fish oil polyunsaturated fatty acids

Clinical studies have indicated that dietary fish oil may have therapeutic value in the treatment of psoriasis, a hyperproliferative, inflammatory skin disorder characterized by elevated LTB4. To evolve a possible mechanism for these beneficial effects, we determined the metabolic fate of fish oil derived n-3 fatty acids in the skin. Specifically, we incubated guinea pig epidermal enzyme preparations with [3H]eicosapentaenoic acid (20:5 n-3) and [14C]docosahexaenoic acid (22:6 n-3). Analyses of the radiometabolites revealed the transformation of these n-3 fatty acids into n-6 lipoxygenase (arachidonate 15-lipoxygenase) products: 15-hydroxyeicosapentaenoic acid (15-HEPE) and 17-hydroxydocosahexaenoic acid (17-HDHE), respectively. Since 15-lipoxygenase products have been suggested as possible endogenous inhibitors of 5-lipoxygenase (an enzyme which catalyzes the formation of LTB4) we tested the ability of 15-HEPE and 17-HDHE in vitro to inhibit the activity of the 5-lipoxygenase. Incubations of these metabolites with enzyme preparations from rat basophilic leukemia (RBL-1) cells demonstrated that 15-HEPE (IC50 = 28 microM) and 17-HDHE (IC50 = 25 microM) are respectively potent inhibitors of RBL-I-5-lipoxygenase. The inhibitory potential of these fish oil metabolites provides a possible mechanism by which fish oil might act to decrease local cutaneous levels of LTB4, and thereby alleviate psoriatic symptoms.

Breast milk fatty acids in mothers of children with atopic eczema

The total lipid fatty acid composition of mature breast milk has been analysed in a group of twenty-five mothers of children with atopic eczema, and compared with breast milk from twenty-two controls. Total lipids were extracted into chloroform-methanol (2:1, v/v) and the methyl esters prepared by alkalicatalysed trans-esterification were separated by gas-liquid chromatography and identified by comparison with standard fatty acid methyl esters. Results show that mothers of children with atopic eczema have a significantly greater proportion of linoleic acid, and a smaller proportion of dihomo-gamma-linolenic acid in their total breast milk lipid than the controls. Proportions of total derived fatty acids were similar between groups and there were no differences in the principal saturated and monounsaturated fats. It was concluded that mothers of children with atopic eczema have an abnormal breast-milk fatty acid composition. This supports previous evidence of a defect of conversion of linoleic acid into its long-chain polyunsaturated metabolites in the condition.

Is the origin of atopy linked to deficient conversion of omega-6-fatty acids to prostaglandin E1?

Our hypothesis on the origin of atopy links alterations in omega-6-fatty acid metabolism in atopic persons (i.e., reduced formation of delta-6-desaturase products) to deficient T cell differentiation and function. We suggest that a relative deficiency in dihomo-gamma-linolenic acid-derived prostaglandin E1 is the major etiologic factor for diminished T cell maturation postpartum. Its precursors, gamma-linolenic acid and dihomo-gamma-linolenic acid, are physiologically provided in colostrum and mature breast milk of healthy mothers. Depressed cell-mediated immunity and uncontrolled B-cell response with increased IgE synthesis are explained as prostaglandin E1-dependent defects of T cell differentiation caused by insufficient supply of prostaglandin E1 precursors during early infancy. Thus, in our opinion atopy is a metabolic disorder and the associated immunologic disturbances are epiphenomena.

Meta-analysis of placebo-controlled studies of the efficacy of Epogam in the treatment of atopic eczema. Relationship between plasma essential fatty acid changes and clinical response

Gamma-linolenic acid in the form of a particular variety of evening primrose oil (Epogam) has been reported of value in the treatment of atopic eczema. Nine controlled trials of evening primrose oil were performed in eight centres. Four of the trials were parallel and five cross-over. Doctors and patients assessed the severity of eczema by scoring measures of inflammation, dryness, scaliness, pruritus and overall skin involvement. Individual symptom scores were combined to give a single global score at each assessment point. In the analysis of the parallel studies, both patient and doctor scores showed a highly significant improvement over baseline (P less than 0.0001) due to Epogam: for both scores the effect of Epogam was significantly better than placebo. Similar results were obtained on analysis of the cross-over trials, but in this case the difference between Epogam and placebo in the doctors' global score, although in favour of Epogam, failed to reach significance. The effects on itch were particularly striking. There was no placebo response to this symptom, whereas there was a substantial and highly significant response to Epogam (P less than 0.0001). When the improvements, or otherwise, in clinical condition were related to changes in plasma levels of dihomogammalinolenic and arachidoni acids, it was found that there was a positive correlation between an improvement in clinical score and a rise in the fatty acid levels.

Essential fatty acids in clinical dermatology

A deficiency of essential fatty acid intake can produce severe cutaneous abnormalities but is exceedingly rare in clinical practice. Recent research has shown that abnormalities in essential fatty acid metabolism may play a role in atopic eczema, acne, and psoriasis. Therapeutic innovations have already resulted from this knowledge, and more are likely to emerge.

Evening primrose oil and olive oil in treatment of rheumatoid arthritis

The effects of 10 ml of evening primrose oil or olive oil, administered twice daily for 12 weeks, on clinical and laboratory signs and on plasma prostaglandins were studied in 18 patients with rheumatoid arthritis. The plasma concentration of PGE2 decreased and that of TxB2 increased in both treatment groups, but no significant improvement could be seen in either group.

A study of evening primrose seed oil in atopic asthma

It has shown recently that Evening Primrose Oil (Efamol) produces a significant clinical improvement in atopic eczema. Efamol contains gamma-linolenic acid which is a precursor to PGE1 a more consistent bronchodilator than PGE2. We have conducted a double blind placebo controlled study in atopic asthmatics given Efamol for an eight week period looking at the control of asthma, including histamine challenge tests. We have found no effect on the asthma or challenge tests although Efamol produced an alteration in fatty acid profile. The patients showed an abnormal fatty acid profile. We speculate that such fatty acid abnormalities could be important in the aetiology of asthma.

Evening primrose oil in rheumatoid arthritis: changes in serum lipids and fatty acids

The serum concentration of lipids and composition of fatty acids after overnight fasting were studied in 18 patients with rheumatoid arthritis treated for 12 weeks with either 20 ml of evening primrose oil containing 9% of gamma-linolenic acid or olive oil. The serum concentrations of oleic acid, eicosapentaenoic acid, and apolipoprotein B decreased and those of linoleic acid, gamma-linolenic acid, dihomo-gamma-linolenic acid, and arachidonic acid increased during treatment with evening primrose oil. During olive oil treatment the serum concentration of eicosapentaenoic acid decreased and those of high density lipoprotein-cholesterol and apolipoprotein A-I increased slightly. The decrease in serum eicosapentaenoic acid and the increase in arachidonic acid concentrations induced by evening primrose oil may not be favourable effects in patients with rheumatoid arthritis in the light of the roles of these fatty acids as precursors of eicosanoids.

Role of diet in treating atopic eczema: elimination diets can be beneficial

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Effects of dietary linoleic acid on beta-adrenergic responsiveness of the guinea pig respiratory system

Respiratory autonomic beta-adrenergic receptor function was investigated in isolated tracheal spirals of guinea pigs receiving different diets. Comparison was made between control and Haemophilus influenzae treated animals; this latter group serving as animal model for atopy. The different semi-synthetic diets (35 energy%) varying in their linoleic acid contents (5.85, 11.25 and 22.05 en%), exerted profound effects on membrane fatty acid composition. No influence of these diets on either food intake or growth could be detected. Isoprenaline induced relaxation of guinea pig tracheal spirals was maximal in the dietary group receiving moderate linoleic acid (11.25 en%). Both the addition and the withdrawal of linoleic acid to this diet resulted in a significant impairment of beta-adrenergic receptor function, to the same extent as can be induced by Haemophilus influenzae. The results are discussed in view of current concepts for atopy.

Gammalinolenic acid-enriched diet alters cutaneous eicosanoids

There are reports that vegetable oils containing gammalinolenic acid (GLA) may exert beneficial effects on inflammatory skin disorders. To determine whether or not dietary GLA exerts any modulatory role on cutaneous eicosanoids, guinea pigs were fed either a control diet containing safflower oil (less than 0.5% GLA) or borage oil, a GLA-rich diet containing 25% GLA. After an 8-week feeding period, epidermal samples from both animal groups were analyzed for fatty acid composition and tissue eicosanoids. Analysis of epidermal neutral lipids and phospholipids in borage oil-fed animals showed a marked increase in GLA and its elongase product, dihomogammalinolenic acid (DGLA). Similarly, analysis of epidermal eicosanoids in the borage oil-fed animals revealed significant increases in the amounts of the 15-hydroxy fatty acid (15-OH-20:3n-6) and prostaglandin PGE1, both metabolites of DGLA. Since these metabolites have anti-inflammatory potential, our results suggest that increased dietary GLA could result in the generation of local anti-inflammatory metabolites thus providing a non-toxic approach to suppression of cutaneous inflammatory skin disorders.

Oxidative metabolism of dihomogammalinolenic acid by guinea pig epidermis: evidence of generation of anti-inflammatory products

Reports that vegetable oils which contain gamma-linolenic acid (18:3n-6) may exert beneficial effects on cutaneous disorders prompted us to investigate whether epidermis possesses the ability to transform dihomogammalinolenic acid (20:3n-6), the epidermal elongase product of 18:3n-6, into oxidative metabolites with anti-inflammatory potential. Incubations of [1-14C]20:3n-6 with the 105,000 g particulate (microsomal) fraction from guinea pig epidermal homogenate resulted in the formation of the 1-series prostaglandin PGE1. The identity of this product was confirmed by argentation thin-layer chromatography (TLC), reverse phase-HPLC, and conversion with alkali treatment to PGB1. Incubations of [1-14C]20:3n-6 with the 105,000 g supernatant (cytosolic) fraction from guinea pig epidermal homogenate resulted in the formation of the 15-lipoxygenase product 15-hydroxy-8, 11, 13-eicosatrienoic acid (15-OH-20:3n6). The identity of this product was confirmed by normal phase-HPLC and gas chromatography/mass spectrometry (GC/MS). Thus, data from these studies indicate the capacity of enzymes in the microsomal and cytosolic fractions of guinea pig epidermal homogenates to transform 20:3n-6 to the eicosanoids PGE1 and 15-OH 20:3n-6, products which reportedly have anti-inflammatory properties. The in vivo significance of these findings remains to be explored.

Effects of altering dietary essential fatty acids on requirements for non-steroidal anti-inflammatory drugs in patients with rheumatoid arthritis: a double blind placebo controlled study

In rheumatoid arthritis (RA) benefit from non-steroidal anti-inflammatory drugs (NSAIDs) is mediated through inhibition of the cyclo-oxygenase enzyme, thereby decreasing production of the 2 series prostaglandins (PGs). The lipoxygenase enzyme is intact, however, allowing leucotriene (LT) production, e.g., LTB4 (an inflammatory mediator). Treatment with evening primrose oil (EPO) which contains gamma-linolenic acid (GLA) leads to production of the 1 series PGs, e.g., PGE1, which has less inflammatory effects. Also LT production is inhibited. Eicosapentaenoic acid (EPA, fish oil) treatment provides a substrate for PGs and LTs, which are also less inflammatory. In this study 16 patients with RA were given 540 mg GLA/day (EPO), 15 patients 240 mg EPA and 450 mg GLA/day (EPO/fish oil), and 18 patients an inert oil (placebo). The aim of this study was to determine if EPO or EPO/fish oil could replace NSAID treatment in RA. The initial 12 month treatment period was followed by three months of placebo for all groups. Results at 12 months showed a significant subjective improvement for EPO and EPO/fish oil compared with placebo. In addition, by 12 months the patients receiving EPO and EPO/fish oil had significantly reduced their NSAIDs. After 3 months of placebo those receiving active treatment had relapsed. Despite the decrease in NSAIDs, measures of disease activity did not worsen. It is suggested that EPO and EPO/fish oil produce a subjective improvement and allow some patients to reduce or stop treatment with NSAIDs. There is, however, no evidence that they act as disease modifying agents.

Metabolism and function of skin lipids

It is apparent from this review that the skin is an organ displaying a highly active metabolism of PUFA's. It possesses the capacity to biosynthesize, metabolize and interconvert a variety of lipids as outlined in the review. Its inability to desaturate the essential fatty acids underscores the significance of these PUFAs in cutaneous biology. For instance, increases in the concentrations of 20:4n6 as well as certain autacoids are associated with many inflammatory-hyperproliferative dermatoses. However, the origin of 20:4n6, which is found complexed to skin phospholipids, has until recently remained a mystery. Studies undertaken in our laboratory designed to delineate the origin of epidermal 20:4n6, and to elucidate the effects of EFA deficiency and crossover replenishment with dietary oils on epidermal lipid metabolism have demonstrated: (i) that microsomal preparations from rat and guinea pig epidermis lack the capacity to transform 18:2n6 into 18:3n6 (catalyzed by the enzyme delta 6 desaturase) and 20:3n6 into 20:4n6 (catalyzed by the enzyme delta 5 desaturase). This observation implies that 20:4n6, a component of epidermal phospholipids, is biosynthesized elsewhere endogenously and transported to the epidermis for esterification into the phospholipids. In an extension of this work, epidermal microsomal preparations from normal human and diseased human epidermis (clinically uninvolved and involved psoriatic epidermis) were examined in order to determine the activities of the delta 6 and the delta 5 desaturases as well as the elongase, respectively. Our data revealed that normal, uninvolved and involved human epidermal preparations lack the capacity to desaturate 18:2n6 to 18:3n6 and 20:3n6 to 20:4n6. These results are interesting in view of the fact that 20:4n6 metabolites participate in the phlogistic and hyperproliferative processes in psoriasis. It is likely that the increases in the 20:4n6-derived eicosanoids, which are prominent in uninvolved and involved psoriatic skin, are the result of an enhanced epidermal phospholipase A2 activity. The heightened lipase activity would lead to an elevated concentration of free 20:4n6 which, in turn, would result in the reported increase of epidermal eicosanoid levels. (ii) Incubation of 18:3n6 with microsomal preparations from skin specimens from normal, uninvolved and involved psoriatic epidermis revealed the presence of elongase activity capable of converting 18:3n6 into 20:3n6. This activity was markedly elevated (5-fold) in involved hyperproliferative psoriatic preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary supplementation with eicosapentaenoic acid in the treatment of atopic dermatitis

The effects of a dietary supplement of n-3 fatty acids in patients with atopic dermatitis were investigated in a 12-week, double-blind study. The experimental group received 10 g of fish oil daily, of which about 1.8 g was eicosapentaenoic acid. This amount of eicosapentaenoic acid can be obtained from a daily intake of fat fish. The controls received an iso-energetic placebo supplement containing olive oil. Compliance was monitored by gas-chromatographic analysis of the fatty acid pattern in serum phospholipids. Results favoured the experimental group with regard to scale (P less than 0.05), itch (P less than 0.05) and overall subjective severity (P less than 0.02) as compared to the controls.

Evening primrose oil in the treatment of atopic eczema: effect on clinical status, plasma phospholipid fatty acids and circulating blood prostaglandins

In a double-blind trial patients with atopic eczema received either oral evening primrose oil (EPO) (n = 14) or placebo (n = 11) for 12 weeks. In the EPO group a statistically significant improvement was observed in the overall severity and grade of inflammation and in the percentage of the body surface involved by eczema as well as in dryness and itch. Patients in the placebo group showed a significant reduction in inflammation. The patients receiving EPO showed a significantly greater reduction in inflammation than those receiving placebo. Evening primrose oil caused a significant rise in the amount of dihomogammalinolenic acid in the plasma phospholipid fatty acids. Plasma levels of TXB2, 6-keto-PGF1 alpha and PGE1, and the amount of TXB2 released into serum during clotting were not altered by evening primrose oil.