12-hydroxy-5-8-10-14-eicosatetraenoic-acid and Psoriasis

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Fatty Acids, Nonesterified; Fish Oils; Humans; Hydroxyeicosatetraenoic Acids; Lipids; Prostaglandin-Endoperoxide Synthases; Psoriasis

The epidermal layer of the skin is the site of active arachidonic acid metabolism. The main product of epidermal keratinocytes is the 12-lipoxygenase derivative 12(S)-hydroxy-eicosatetraenoic acid (12(S)-HETE). Its biological effects in skin are mediated via specific, high affinity binding sites present on both keratinocytes and epidermal antigen presenting Langerhans cells. The main biological effect is chemotaxis of keratinocytes suggesting a physiological role of 12-HETE in cutaneous wound healing. Analysis of 12-HETE receptors in various cutaneous disease states revealed a dramatic defect in lesional and uninvolved psoriatic skin which may represent a central molecular defect in the pathophysiology of the disease.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Cell Division; Chemotaxis; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Psoriasis; Receptors, Cell Surface; Receptors, Eicosanoid

The pharmacologic and clinical effects of the 5-lipoxygenase inhibitor, lonapalene, have been determined in a double-blind, placebo-controlled, topical study in ten volunteers with psoriasis. A statistically significant clinical improvement was seen in lesions treated with 2% lonapalene ointment as compared with vehicle-treated sites. Although there was a statistically significant reduction in the levels of material similar or identical to the chemoattractant arachidonate 5-lipoxygenase product, leukotriene B4, in skin chamber fluid samples from lonapalene versus vehicle treated lesions, no significant reduction in arachidonic acid or 12-hydroxy-5,8,10,14-eicosatetraenoic acid was seen. The reduction in leukotriene B4 equivalents occurred before significant clinical improvement in lesions was seen. This and the selectivity of the pharmacologic response suggest that the therapeutic effect of topical lonapalene in psoriasis might be related to inhibition of leukotriene B4 synthesis. These results support the view that 5-lipoxygenase inhibitors may be useful in the treatment of psoriasis, and that leukotriene B4 is a relevant mediator of the pathology of this disease.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonate Lipoxygenases; Arachidonic Acid; Arachidonic Acids; Chromatography, High Pressure Liquid; Clinical Trials as Topic; Double-Blind Method; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase Inhibitors; Male; Middle Aged; Naphthalenes; Psoriasis

Single topical application of the neutrophil chemoattractant arachidonic acid metabolites leukotriene B4 (LTB4) and 12-R,S-hydroxy-5,8,10,14-eicosatetraenoic acid [corrected] (12-HETE) to normal skin elicits a histological response similar to early psoriasis. This effect diminishes following repeated application indicating the development of local tolerance. In order to assess whether induction of tolerance could be exploited as a treatment for psoriasis we studied the clinical effects of topical application of LTB4 (n = 6) and 12-HETE (n = 3) under occlusion to small psoriatic lesions for 12 consecutive days. The area of the control lesions decreased significantly over the study period while the areas of lesions to which LTB4 and 12-HETE were applied remained unchanged. No other difference between responses of the three groups was detected. We have shown that, in the doses used, multiple applications of these substances to established stable psoriatic lesions do not produce a therapeutically useful response.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adolescent; Adult; Aged; Aged, 80 and over; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Middle Aged; Psoriasis

Clinical studies have shown that diets enriched with omega-3 (also know as n-3) polyunsaturated fatty acids could relieve the symptoms of patients with psoriasis. However, the mechanisms involved remain poorly understood. The aim of this study was to investigate the effects of α-linolenic acid (ALA) on the proliferation and differentiation of psoriatic keratinocytes in a three-dimensional skin model. Skin models featuring healthy (healthy substitute) or psoriatic (psoriatic substitute) cells were engineered by the self-assembly method of tissue engineering using a culture medium supplemented with 10 μM ALA in comparison with the regular unsupplemented medium. ALA decreased keratinocyte proliferation and improved psoriatic substitute epidermal differentiation, as measured by decreased Ki67 staining and increased protein expression of FLG and loricrin. The added ALA was notably incorporated into the epidermal phospholipids and metabolized into long-chain n-3 polyunsaturated fatty acids, mainly eicosapentaenoic acid and n-3 docosapentaenoic acid. ALA supplementation led to increased levels of eicosapentaenoic acid derivatives (15-hydroxyeicosapentaenoic acid and 18-hydroxyeicosapentaenoic acid) as well as a decrease in levels of omega-6 (also know as n-6) polyunsaturated fatty acid lipid mediators (9-hydroxyoctadecadienoic acid, 12-hydroxyeicosatetraenoic acid, and leukotriene B

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; alpha-Linolenic Acid; Cell Differentiation; Cell Proliferation; Dietary Supplements; Extracellular Signal-Regulated MAP Kinases; Humans; Keratinocytes; Leukotriene B4; Psoriasis; Tissue Engineering

Pro- and anti-inflammatory metabolites of arachidonic acid - eicosanoids - participate in skin homeostasis, affecting the growth and differentiation of keratinocytes. Alterations of 12-lipoxygenase (LOX) and 15-LOX and their metabolites have been described in the epidermis of patients with psoriasis, but systemic production of 12-LOX and 15-LOX eicosanoids has not been studied in the disease.. To ascertain the frequencies of the genetic variants ALOX12 rs1126667 and ALOX15 rs11568070 in cases and controls, and to compare urinary metabolites of 12(S)-hydroxyeicosatetraenoic acid (HETE) between patients with psoriasis and healthy controls.. Patients with psoriasis (n = 200) were stratified depending on the severity of their dermal lesions. Genotyping was performed using a 5'-nuclease real-time assay. The concentrations of 12(S)-HETE, its metabolites and 15(S)-HETE were determined in urine samples using high-performance liquid chromatography-tandem mass spectrometry.. Tetranor-12(S)-HETE metabolite excretion was significantly higher in urine of patients with psoriasis, while excretion of 12(S)-HETE was decreased. Neither 12(S)-HETE nor tetranor-12(S)-HETE correlated with the type of disease or severity score. No difference in urinary 15(S)-HETE was found between the study groups. Genotype distribution of the ALOX12 rs1126667 or ALOX15 rs11568070 polymorphisms did not discriminate for the disease or its severity.. Systemic metabolism of 12(S)-HETE is accelerated in psoriasis because excretion of the tetranor-12(S)-HETE inactivation product is elevated. No correlation with the severity or extent of psoriasis is detectable. We propose that in patients with psoriasis, 12(S)-HETE to tetranor-12(S)-HETE conversion could be at least a marker for this disease, in which inflammation of the skin can induce microsomal beta-oxidation of this eicosanoid.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Biomarkers; Case-Control Studies; Female; Genotype; Humans; Lipoxygenase; Male; Polymorphism, Single Nucleotide; Psoriasis; ROC Curve

A recognized feature of psoriasis and other proliferative dermatoses is accumulation in the skin of the unusual arachidonic acid metabolite, 12R-hydroxyeicosatetraenoic acid (12R-HETE). This hydroxy fatty acid is opposite in chirality to the product of the well-known 12S-lipoxygenase and heretofore in mammals is known only as a product of cytochrome P450s. Here we provide mechanistic evidence for a lipoxygenase route to 12R-HETE in human psoriatic tissue and describe a 12R-lipoxygenase that can account for the biosynthesis. Initially we demonstrated retention of the C-12 deuterium of octadeuterated arachidonic acid in its conversion to 12R-HETE in incubations of psoriatic scales, indicating the end product is not formed by isomerization from 12S-H(P)ETE via the 12-keto derivative. Secondly, analysis of product formed from [10R-3H] and [10S-3H]-labeled arachidonic acids revealed that 12R-HETE synthesis is associated with stereospecific removal of the pro-R hydrogen from the 10-carbon of arachidonate. This result is compatible with 12R-lipoxygenase-catalyzed formation of 12R-HETE and not with a P450-catalyzed route to 12R-HETE in psoriatic scales. We cloned a lipoxygenase from human keratinocytes; the cDNA and deduced amino acid sequences share 98% 12R in configuration. The 12R-lipoxygenase cDNA is detectable by PCR in psoriatic scales and as a 2.5-kilobase mRNA by Northern analysis of keratinocytes. Identification of this enzyme extends the known distribution of R-lipoxygenases to humans and presents an additional target for potential therapeutic interventions in psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Amino Acid Sequence; Arachidonate 12-Lipoxygenase; Base Sequence; Cloning, Molecular; DNA, Complementary; Gene Expression Regulation; Gene Transfer Techniques; HeLa Cells; Humans; Molecular Sequence Data; Psoriasis; Sequence Analysis; Skin

The synthesis of a series of 1,8-dihydroxy-9(10H)-anthracenones bearing sulfur-linked substituents in the 10-position is described. These compounds were evaluated for their ability to inhibit the growth of the human keratinocyte cell line HaCaT and the 5- and 12-lipoxygenase enzymes in bovine polymorphonuclear leukocytes and mouse epidermal homogenate, respectively. In addition, the following redox properties of the compounds were determined: reactivity against 2,2-diphenyl-1-picrylhydrazyl, generation of hydroxyl radicals as measured by deoxyribose degradation, and inhibition of lipid peroxidation in model membranes. Compounds 4e and 4h of this series compare favorably in the cellular assays with the antipsoriatic anthralin. They have the combined inhibitory action against leukotriene B4 and 12(S)-HETE formation and are highly potent antiproliferative agents against keratinocyte growth. In contrast to anthralin, 4h, 1,8-dihydroxy-10-[(4-hydroxyphenyl)thio]-9(10H)-anthracenone, is not cytotoxic as documented by the LDH activity released from cytoplasm of keratinocytes and does not enhance lipid peroxidation in model membranes.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Anthralin; Antioxidants; Cattle; Cell Division; Cells, Cultured; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Keratinocytes; Lipoxygenase Inhibitors; Mice; Molecular Structure; Neutrophils; Psoriasis

Human epidermal cells exhibited none of the cytosolic lipoxygenase activity that is prominent in mucosal epithelial cells, but instead contained a microsomal activity that converted arachidonic acid to 12-hydroxyeicosatetraenoic acid (12-HETE). Identification of the extractable 12-HETE-forming activity as a 12-lipoxygenase (distinct from cytochrome P-450) included (S)-12-stereospecificity of product formation, trapping of 12-hydroperoxyeicosatetraenoic acid as an intermediate reaction product, and lack of NADPH dependence for activity. Epidermal cell poly(A)+ RNA contained high levels of a 2.3-kb mRNA that selectively hybridized with human platelet 12-lipoxygenase cDNA, and partial cDNA sequence of this mRNA indicated identity to platelet 12-lipoxygenase. The epidermal 12-lipoxygenase was not recognized by antibodies against the leukocyte-type 12- and 15-lipoxygenases (found in leukocytes, reticulocytes, and mucosal epithelial cells) but was detected by an antiplatelet 12-lipoxygenase antibody. The epidermal 12-lipoxygenase antigen was selectively expressed in germinal layer keratinocytes in healthy and psoriatic skin, and these layers exhibited hyperplasia and increased immunostaining in inflamed psoriatic skin. Together with previous results, these observations indicate that 1) epidermis generates 12-HETE by either cytochrome P-450 or lipoxygenase-based mechanisms depending on reaction conditions, and 2) 12-lipoxygenases (originally described in hematopoietic cell types) may be expressed in at least two distinct isoforms in epithelial barriers in humans, and in the case of the skin, a microsomal (platelet-type) 12-lipoxygenase is selectively overexpressed in germinal layer keratinocytes during psoriatic inflammation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonate 12-Lipoxygenase; Arachidonic Acid; Base Sequence; Blood Platelets; Detergents; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Immunohistochemistry; Keratinocytes; Molecular Sequence Data; Oxygen; Precipitin Tests; Psoriasis; RNA, Messenger; Subcellular Fractions

The purpose of the present study was to develop an ex vivo skin model to determine the capacity of lesional skin of psoriasis to form leukotriene B4 and other eicosanoids. Keratomed skin samples were incubated in the presence of the calcium ionophore A23187 and arachidonic acid for 45 min at 37 degrees C. After extraction of lipids, eicosanoids were determined by quantitative reversed-phase high-performance liquid chromatography in combination with specific radioimmunoassays. We found that stimulation of skin samples with A23187 and arachidonic acid increased the amount of leukotriene B4 4.0-fold. The 12-lipoxygenase product, 12-hydroxy-eicosatetraenoic acid, and the 15-lipoxygenase product, 15-hydroxy-eicosatetraenoic acid, were both increased 2.7-fold. The cyclooxygenase product, prostaglandin E2, was increased 8.0-fold. Similar incubations using psoriatic scales did not result in formation of eicosanoids. Incubations with the 5-lipoxygenase inhibitor RS43179 inhibited the formation of leukotriene B4 and prostaglandin E2 without significantly affecting the formation of 12-hydroxy-eicosatetraenoic acid and 15-hydroxy-eicosatetraenoic acid. These results reveal that lesional psoriatic skin ex vivo has the enzymatic capacity to increase the levels of eicosanoids. This provides an ex vivo skin model to determine whether putative lipoxygenase inhibitors are able to modulate the formation of eicosanoids in psoriatic skin.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Calcimycin; Chromatography, High Pressure Liquid; Dinoprostone; Eicosanoids; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukotriene B4; Lipoxygenase Inhibitors; Naphthalenes; Psoriasis; Radioimmunoassay; Skin

12-hydroxyeicosatetraenoic acid (12-HETE) is assumed to play a central role in the pathophysiology of psoriasis. Since its effects in skin are mediated by specific high-affinity receptors, we studied the receptor characteristics in cultured epidermal cells from involved and apparently healthy skin of psoriasis patients by radioligand binding assay. Involved and uninvolved psoriatic epidermal cells showed a fourfold decrease in the number of 12-HETE binding sites as compared with normal healthy individuals and patients with atopic dermatitis, while receptor affinity remained unchanged. The decrease in receptor number was evident in psoriatic cells even in long-term culture and was not due to receptor down-regulation, defective response to interferon gamma or to protease degradation of receptor protein. The decrease in the number of 12-HETE receptors detectable even in clinically normal psoriatic skin functionally leads to diminished 12-HETE uptake and may thus represent a primary central molecular defect in the pathophysiology of the disease.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Cells, Cultured; Dermatitis, Atopic; Down-Regulation; Humans; Hydroxyeicosatetraenoic Acids; Interferon-gamma; Keratinocytes; Psoriasis; Receptors, Cell Surface; Receptors, Eicosanoid; Trypsin

The effects of dithranol and its therapeutically inactive oxidation product, danthrone, on 12(S)-HETE binding to the human epidermal cell line SCL-II were studied. Dithranol (0.25-1 microgram/ml), in contrast to danthrone, induced a substantial decrease in 12(S)-HETE binding in a dose-dependent manner. The inhibition occurred after a latency period of 6 h, reached its maximum at 18-24 h and slowly declined thereafter. At a concentration of 1 microgram/ml, the drug led to an approximately 50% decrease in the number of specific high-affinity 12(S)-HEFE receptors (Bmax), whereas receptor affinity (Kd) showed no change. The down-regulation of 12(S)-HETE receptors on epidermal cells by dithranol may contribute to its antipsoriatic action.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Anthralin; Anthraquinones; Cell Line; Down-Regulation; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Psoriasis; Receptors, Cell Surface; Receptors, Eicosanoid

The principal in vivo oxygenase products of arachidonic acid and linoleic acid in psoriatic skin scales are 12-hydroxyeicosatetraenoic acid (R/S ratio = 5.7), 13-hydroxyoctadecadienoic acid (S/R = 1.9), and 9-hydroxyoctadecadienoic acid (R/S = 2.4). Definition of the enzymatic origin of these fatty acid derivatives is an important step in assessing their possible role in the pathogenesis of psoriasis. Psoriatic skin scales were incubated with radiolabeled arachidonic acid and linoleic acid and the monohydroxylated derivatives produced in vitro were characterized. The products of incubation with [3H]arachidonic acid were an enantiopure 15(S)-[3H]hydroxyeicosatetraenoic acid and a nonracemic mixture of the 12-[3H]hydroxyeicosatetraenoic acid steroisomers (R/S ratio = 4.5). An enantiopure 13(S)-[14C]hydroxyoctadecadienoic acid was produced from [14C]linoleic acid. No radiolabeled products were derived from incubations with heat-denatured scales. These results provide evidence for two distinct oxygenase activities that are preserved in psoriatic skin scales. One is that of an omega-6 oxygenase with strict (S) stereospecificity, consistent with the activity of a lipoxygenase. This enzyme activity appears to be similar to that of the 15-lipoxygenase which has been described in cultured human keratinocytes. The second activity is that of an arachidonic acid 12(R)-oxygenase that has not been observed in normal human epidermis but which appears to be expressed in psoriatic epidermis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; Linoleic Acid; Linoleic Acids; Oxidation-Reduction; Oxygenases; Psoriasis; Skin; Stereoisomerism

Homogenates of normal human epidermis synthesized 12-hydroxyeicosatetraenoic acid (12-HETE) when incubated in vitro with arachidonic acid. The stereoconfigurations of the C-12 hydroxyl isomers were determined by incubation with potato 5-lipoxygenase. The synthesized substrate-specific diHETEs; 5S, 12R and 5S, 12S, were readily separated by high performance liquid chromatography. Using this novel methodology, the normal epidermis was found to synthesize predominantly 12-S-HETE while, in contrast, psoriatic scale was found to contain 12-R-HETE. The 5-lipoxygenase inhibitors, Merck L-651, 896, Takeda AA86I, and the active metabolite of Syntex lonapalene were found to inhibit 12-HETE formation in normal epidermal homogenates.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Chromatography, High Pressure Liquid; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Lipoxygenase; Lipoxygenase Inhibitors; Methods; NADP; Phenothiazines; Psoriasis; Pyridines; Stereoisomerism

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonate 12-Lipoxygenase; Cytochrome P-450 Enzyme System; Humans; Hydroxyeicosatetraenoic Acids; Isomerism; Oxidation-Reduction; Psoriasis; Skin

The concentrations of arachidonic acid and its lipoxygenase metabolites were measured in exudates from lesional psoriatic skin during treatment with 0.25% dithranol (anthralin) applied topically for 10 days. Dithranol caused a reduction in the concentration of arachidonic acid at 10 days (167 +/- 42 and 358 +/- 55 ng ml-1 treated and control sites respectively, p less than 0.05) concurrent with clinical improvement of the lesions. Neither 12-hydroxyeicosatetraenoic acid nor leukotriene B4 concentrations were significantly affected. These results do not support the view that lipoxygenase products are of major importance in the pathogenesis of psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Administration, Cutaneous; Adult; Anthralin; Arachidonic Acid; Arachidonic Acids; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase; Male; Middle Aged; Psoriasis

The biochemical changes underlying the clinical manifestations of psoriasis are unknown. Certain chemotactic eicosanoids derived from arachidonic acid metabolism have been suggested to play important roles in psoriasis, because of their presence in lesional psoriatic skin and their ability to elicit skin inflammation and to stimulate epidermal proliferation. The purpose of the present study was to elucidate which eicosanoids might be involved in the early phases of the inflammatory processes of psoriasis. Eicosanoids were analyzed in scale and in lesional skin without scale both in acute guttate and chronic plaque psoriatic lesions. Methods for identification of eicosanoids included reversed-phase high-performance liquid chromatography combined with radioimmunoassay. Leukotriene B4 was present in both acute guttate and chronic plaque skin lesions in biologically active amounts (acute guttate lesions: 18.7 +/- 7.1 ng/g wet tissue in scale and 3.2 +/- 1.5 ng/g wet tissue in lesional skin without scale; chronic plaque lesions: 33.1 +/- 9.7 ng/g wet tissue in scale and 5.3 +/- 2.0 ng/g wet tissue in lesional skin without scale). 12- and 15-hydroxy-eicosatetraenoic acid (HETE) reached biologically active concentrations only in scale of chronic plaque lesions (1,512 +/- 282 and 1,441 +/- 411 ng/g wet tissue, respectively). The level of prostaglandin E2 in chronic plaque lesions was similar to the level in normal skin, while the level in acute guttate lesions was increased twofold (71.0 +/- 14.8 ng/g wet tissue). These results demonstrate that leukotriene B4, but not 12-HETE, is present in acute guttate psoriatic skin lesions in concentrations able to exert biologic effects. Leukotriene B4 may therefore participate in inflammatory changes of acute psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Acute Disease; Chromatography, High Pressure Liquid; Chronic Disease; Dinoprostone; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Psoriasis; Radioimmunoassay; Skin

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Humans; Hydroxyeicosatetraenoic Acids; Psoriasis; Radiochemistry; Skin; Stereoisomerism

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonate 12-Lipoxygenase; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Psoriasis; Skin

Two different lipoxygenases have been identified in human and rat epidermis. One lipoxygenase has a (n-9)-specificity, converts arachidonic acid into 12-hydroxyeicosatetraenoic acid (12-HETE), and has been described by several investigators. Linoleic acid is not a substrate for this enzyme. The other lipoxygenase, with (n-6)-specificity, converts arachidonic acid into 15-HETE and linoleic acid into 13-hydroxyoctadecadienoic acid (13-HOD). Especially the latter lipoxygenase is thought to be involved in the regulation of the differentiation of the skin cells into a proper water-barrier layer. Linoleate is supposed to be the physiological substrate; this fatty acid is especially present in characteristic sphingolipids with unique structures.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Chromatography, High Pressure Liquid; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Lipoxygenase; Psoriasis; Skin

Increased amounts of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) are found in the lesional skin of patients with the skin disease psoriasis when compared to clinically normal skin. Stereochemical analysis has recently shown that the 12-HETE present in lesional psoriatic scale is the (R), and not the (S) hydroxyl enantiomer, produced by platelets. Since the chemoattractant activity of 12(R)-HETE has not previously been described, the (R) and (S) hydroxyl enantiomers of 12-HETE have now been synthesised and their chemokinetic activity compared in vitro. 12(R)-HETE, was more potent than 12(S)-HETE as a chemokinetic agent for human polymorphonuclear leucocytes but 2000 times less potent than leukotriene B4. In contrast to results obtained with the 12-HETE enantiomers, the chemoattractant compound 5(S)-HETE was found to be more potent than the 5(R) hydroxyl enantiomer. Thus, the configuration of the hydroxyl group appears to be of importance to the chemokinetic activity of the HETEs, and the increased potency of the 12(R) enantiomer may enhance its significance as a mediator of inflammation in psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Chemotactic Factors; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Interleukin-8; Kinetics; Neutrophils; Psoriasis; Stereoisomerism

Purified serum samples from asthmatic and psoriatic patients and healthy controls were analysed by high-pressure liquid chromatography (HPLC) and the amounts of leukotrienes were measured from the corresponding HPLC fractions by specific radioimmunoassays. In the serum of healthy controls the amounts of leukotrienes B4, C4 and D4 were very small or negligible. Rather great amount of leukotriene B4 was, however, detected in the serum of many asthmatic and psoriatic patients. The amount of leukotriene B4 was in the serum of asthmatic patients 120 +/- 20 pmol/ml (n = 11, mean +/- SEM) and in that of psoriatic patients 100 +/- 10 pmol/ml (n = 10). The amounts of leukotrienes C4 and D4 were rather small in the serum of most patients. The amount of leukotriene C4 was, however, very high (250 pmol/ml) in the serum of a psoriatic patient. Significant amount of leukotriene D4 was also detected in the serum of this patient. The present study indicated that leukotrienes are formed during blood clotting in the leukocytes of asthmatic and psoriatic patients and that the rate of formation is so high that leukotrienes may have a role in these diseases.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adolescent; Adult; Aged; Asthma; Chromatography, High Pressure Liquid; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Male; Middle Aged; Psoriasis; SRS-A

Certain arachidonic metabolites may play a pathogenic role in psoriasis. Platelets are rich sources of 12-hydroxy-eicosatetraenoic acid (12-HETE) and thromboxane A2, mediators of skin inflammation and platelet aggregation, respectively. We have studied untreated psoriatic patients without a history of diabetes mellitus and smoking. In psoriatics, platelet aggregation elicited by thrombin, ADP, and ristocetin was significantly enhanced as compared with healthy adult volunteers. Enhancement of platelet aggregation was detected in patients with both minimal and widespread disease. The formation of 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT), a cyclooxygenase product, and 12-HETE, a 12-lipoxygenase product, was increased in psoriatics with widespread disease but not in those with minimal disease. Formation of 12-HETE was stimulated to a higher degree (125%) than HHT (98%) in psoriasis (P less than 0.05). Addition of platelet-derived 12-HETE to cultured human epidermal keratinocytes resulted in a stimulation of the DNA synthesis (68% at 10(-7) M). These data suggest that platelet activation occurs in psoriasis, and that release of inflammatory and mitogenic compounds by activated platelets may play a role in the pathophysiology of psoriasis. Whether enhanced platelet aggregation in psoriasis is associated with occlusive vascular disease needs further investigation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Blood Platelets; DNA; Epidermal Cells; Female; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Keratins; Male; Platelet Aggregation; Psoriasis; Stimulation, Chemical

Polymorphonuclear leukocytes (PMN) from ten patients with chronic stable plaque psoriasis, five of whom had more than 40% skin involvement and five with less than 20% involvement, responded in a dose-related fashion to stimulation with the arachidonic acid lipoxygenase products 5- and 12-hydroxyeicosatetraenoic acid (5- and 12-HETE) and leukotriene B4 (LTB4) in an in vitro chemokinesis assay. There was no significant difference in either the random migration or the chemokinetic response of psoriatic PMN to LTB4 when compared to the responses of PMN from a group of age- and sex-matched healthy controls. Psoriatic PMN migrated further in response to low doses of 5- and 12-HETE although the distance moved after maximal stimulation was no different to that observed in controls. No significant difference was observed in the responses of PMN obtained from patients with less than 20% skin involvement when compared to those with more extensive psoriasis. The small differences measured between the chemokinetic responses of psoriatic and control PMN to the lipoxygenase products tested are unlikely to be of pathogenetic significance.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adolescent; Adult; Aged; Arachidonate Lipoxygenases; Chemotaxis, Leukocyte; Female; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukotriene B4; Lipoxygenase; Male; Middle Aged; Neutrophils; Psoriasis; Skin

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase Inhibitors; Naphthalenes; Psoriasis; Skin

Topical clobetasol propionate or vehicle ointment was applied daily for 3 days to psoriatic plaques on eight patients. Skin chamber exudates from untreated, steroid and vehicle treated lesions were assayed for arachidonic acid (AA), leukotriene B4 (LTB4), prostaglandin E2 (PGE2) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) before, and at 24 h and 72 h after treatment. Significant reductions in AA and LTB4 were observed at 72 h in steroid treated lesions. The reduction in 12-HETE levels observed after steroid treatment was not statistically significant. PGE2 levels in lesional psoriatic skin were unaltered. The reduction of AA, and LTB4 was associated with clinical improvement of psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonic Acid; Arachidonic Acids; Betamethasone; Clobetasol; Dinoprostone; Exudates and Transudates; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Male; Middle Aged; Prostaglandins E; Psoriasis; Skin

The metabolism of arachidonic acid by mixed suspensions of leukocytes and platelets prepared from peripheral blood has been studied in 20 patients with psoriasis and 21 healthy controls. A lipoxygenase-derived product, identified as 12,20-dihydroxy-5,8,10,14-eicosatetraenoic acid was formed in increased amounts by the cell suspension from the psoriatic patients. This product results from the metabolism of platelet-derived 12-hydroxy-5,8,10,14-eicosatetraenoic acid by the polymorphonuclear leukocyte 20-hydroxylase enzyme. By contrast, synthesis of the cyclo-oxygenase products 12-hydroxy-5,8,10-heptadecatrienoic acid and thromboxane B2 was diminished. Benoxaprofen, which is known to be beneficial in psoriasis, diminished the levels of 12,20-dihydroxy-5,8,10,14-eicosatetraenoic acid formed in vitro.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Cells, Cultured; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukocytes; Male; Platelet Count; Propionates; Psoriasis

Certain arachidonic acid (AA) metabolites have been detected in psoriatic skin lesions. In this study the capacity of normal epidermis and clinically uninvolved psoriatic epidermis to transform AA into lipoxygenase products was determined in vitro. After incubating homogenized epidermis with exogenous AA, the extracted lipids were isolated by reverse-phase high-performance liquid chromatography. Each chromatographic peak was characterized by its UV absorption spectrum and identified by its coelution with the appropriate authentic standard and by radioimmunoassay of its eluate fraction. Identified compounds were quantitated by integrated UV absorbance. Leukotriene B4 (LTB4) was also identified by neutrophil chemokinesis. Normal epidermis generated 15-hydroxy-eicosatetraenoic acid (15-HETE) and 12-HETE, the latter being more abundant. 5-Lipoxygenase products (LTB4, LTC4, and 5-HETE) were not detected. However, an unknown compound exhibiting a triplet UV absorbtion spectrum with maximum at 274 mm was formed. Its formation was inhibited by 5,8,11,14-eicosatetraynoic acid, but not by indomethacin or a specific 5-lipoxygenase inhibitor (REV 5901). These data suggest that a di-HETE with a triene structure is one possible candidate for the unknown compound. Compared with normal epidermis, the formation of 12-HETE and the unknown di-HETE by uninvolved psoriatic epidermis was increased by 54% and 63%, respectively. The formation of 12-HETE and the unknown di-HETE in uninvolved psoriatic epidermis was stimulated to the same degree in the presence of the phospholipase inhibitor quinacrine. These results indicate that uninvolved psoriatic epidermis has an increased capacity to metabolize free AA into 12-lipoxygenase products.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonate Lipoxygenases; Arachidonic Acid; Arachidonic Acids; Chemotaxis, Leukocyte; Chromatography, High Pressure Liquid; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Lipoxygenase; Neutrophils; Psoriasis; Radioimmunoassay

Epidermis of psoriatic skin lesions is characterized by elevated 5-lipoxygenase and 12-lipoxygenase products. 15-hydroxyeicosatetraenoic acid (15-HETE), the predominant lipoxygenase product in normal dermis, has the potential to inhibit 5-lipoxygenase and 12-lipoxygenase. The purpose of the present study was to determine the capacity of homogenized dermis from uninvolved psoriatic skin to form 15-HETE in vitro. Extracted lipids were separated by reversed-phase high-performance liquid chromatography. Each chromatographic peak was identified by its coelution with authentic standards, by ultraviolet spectrometry, and by radioimmunoassay. Dermis from uninvolved psoriatic skin generated on average 48% less 15-HETE than normal dermis (P less than .01). In contrast, the formation of 12-hydroxyeicosatetraenoic acid was increased by 56% in psoriatic dermis (P less than .01). Prostaglandin E2 formation was similar in normal and psoriatic dermis. Since 15-HETE can inhibit the synthesis of 5-lipoxygenase and 12-lipoxygenase products that possess inflammatory and proliferative capacities, a defective 15-HETE generation in dermis may be of importance for the development of psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Chromatography, High Pressure Liquid; Dinoprostone; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Prostaglandins E; Psoriasis; Radioimmunoassay; Skin

Stereochemical analysis of 12-hydroxy-5,8,10,14-eicosatetraenoic acid derived from the lesional scale of patients with psoriasis is reported. Resolution of the C-12 hydroxyl enantiomers was carried out by high pressure liquid chromatography of their diastereomeric methyl ester dehydroabietyl urethane derivatives. The 'psoriasis derived" compound was shown to be stereochemically distinct from the platelet 12(S)-enantiomer as its derivative co-chromatographed with the 12(R)-diastereomer.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Blood Platelets; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; Psoriasis; Stereoisomerism

The pros and cons concerning the involvement of arachidonic acid metabolism in the pathogenesis of psoriasis are presented. The isolation of arachidonic acid metabolites from psoriatic lesions, their extraordinary biological activity, and the therapeutic efficiency in psoriasis of inhibitors of arachidonic acid metabolism all argue in favor of leukotrienes and monohydroxy fatty acids playing an important role in the development of psoriasis plaques. On the other hand, the lack of specificity of the biochemical findings, the failure to reproduce psoriatic lesions by arachidonic acid metabolites, and the therapeutic activity of drugs that have no effect on arachidonic acid metabolism show that the role of arachidonic acid metabolism in the pathogenesis of psoriasis is still controversial. The availability of selective inhibitors of arachidonic acid-metabolizing enzymes for clinical testing is a prerequisite before pathophysiological conclusions can be made, as the present status of knowledge makes any conclusions premature.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Anthralin; Anti-Inflammatory Agents; Arachidonate Lipoxygenases; Arachidonic Acid; Arachidonic Acids; Glucocorticoids; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase; Propionates; Psoriasis; Retinoids; Skin

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Chemotactic Factors; Chronic Disease; Epidermis; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase; Psoriasis; Skin

Monohydroxy acids (HETEs) and leukotriene B4 (LTB4) metabolites of arachidonic acid were measured in skin of healthy volunteers after ultraviolet B irradiation, and in the uninvolved skin of psoriatics after topical dithranol application. Exudate was collected from suction bullae on control and inflamed abdominal skin, and analysed for 12-HETE and PGE2 by GC-MS and LTB4 by bioassay. 12-HETE and PGE2 were raised at 24 h but not at 72 h after u.v.B irradiation: control and 24 h values were 13.7 and 41.5 ng ml-1 (P less than 0.05, n = 6) for 12-HETE respectively, and 4.5 and 30.2 ng ml-1 (P less than 0.01, n = 6) for PGE2. Dithranol application raised PGE2 levels from 23.1 ng ml-1 in control exudate to 62 ng ml-1 (P less than 0.01, n = 6) at 24 h before declining to base levels at 72 h. However, 12-HETE was raised at 72 h (200 ng ml-1, P less than 0.01, n = 5) but not at 24 h (104 ng ml-1) compared to control levels (50 ng ml-1, n = 5). The levels of the LTB4 were low (less than 100 pg ml-1), and no significant increases were observed. Arachidonic acid in inflamed skin can be metabolised by the cyclo-oxygenase and lipoxygenase pathway. It is probable that the lipoxygenase product 12-HETE is involved in these inflammatory reactions.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Anthralin; Arachidonic Acid; Arachidonic Acids; Dinoprostone; Humans; Hydroxyeicosatetraenoic Acids; Inflammation; Leukotriene B4; Lipoxygenase; Male; Prostaglandins E; Psoriasis; Radiation Injuries; Skin; Time Factors; Ultraviolet Rays

AA and its derivatives are a family of potent mediators and regulators of inflammation. There are several pieces of evidence to suggest a pathophysiologic role of certain AA derivatives in psoriasis. The complexity of the pathways in the generation of LTs and other LO products suggests that carefully designed systems will be needed to establish the exact role of these compounds in the pathogenesis of diseases such as psoriasis, and to test the effects of pharmacological inhibitors.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Fish Oils; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Leukotrienes; Lipoxygenase; Lipoxygenase Inhibitors; Psoriasis; Skin; SRS-A

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Dermatitis; Drug Tolerance; Forearm; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase; Psoriasis; Skin; Skin Tests; SRS-A; Time Factors

Incubations of [14C]arachidonic acid [( 14C]AA) with cell-free preparations from normal, clinically involved and uninvolved epidermis from psoriatic subjects resulted in the formation of several radiolabeled metabolites of the lipoxygenase pathway. The identities of the monohydroxy-ETEs and dihydroxy-ETEs (products of the 12-lipoxygenase and 5-lipoxygenase pathways) were determined by comparison with authentic standards of 12L-hydroxy-5,8,10,14-eicotetraenoic acid (12-HETE) and authentic 5S,12R-dihydroxy-6,8,10,14-eicosatetraenoic acid (LTB4) by thin-layer chromatography in two solvent systems; by silicic acid column chromatography and by normal phase and straight phase high-pressure liquid chromatography. Activity of the enzymes which catalyze this transformation are localized in the soluble (105,000 g supernatant) fraction of the epidermal preparations. The activity of enzymes of both pathways were inhibited by 5,8,11,13-eicosatetraynoic acid (ETYA) and nor-dihydroguaretic acid (NDGA), known inhibitors of the lipoxygenase and cyclooxygenase pathways. Transformation of [14C]AA into [14C]LTB4-like metabolite by the soluble preparations from clinically involved psoriatic epidermis was significantly higher (p less than 0.001) than from paired uninvolved soluble preparations or from soluble preparations from normal subjects. Furthermore, biosynthesis of LTB4-like metabolite by the uninvolved soluble preparation was significantly higher (p less than 0.05) than preparations from normal epidermis. These results imply that the [14C]LTB4-like metabolite biosynthesized by the clinically involved soluble preparation was due at least in part to the increased activity of the lesional enzymes and not entirely due to possible intraepidermal infiltrating neutrophils. Human epidermal preparations, therefore, contain enzymes which catalzye the transformation of labeled AA into labeled LTB4-like metabolite as well as into other yet unidentified dihydroxy-ETEs. Localization of a soluble 5-lipoxygenase-like activity in the epidermis implies a possible role of the lipoxygenase products in the proliferative and inflammatory processes in this tissue.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 5,8,11,14-Eicosatetraynoic Acid; Arachidonate Lipoxygenases; Arachidonic Acid; Arachidonic Acids; Catechols; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipoxygenase; Lipoxygenase Inhibitors; Masoprocol; Psoriasis; Reference Standards; Skin

Collection of exudate from suction bullae is a commonly used method for sampling human skin for mediator analysis. It is satisfactory on skin of normal structure but is unreliable on lesional psoriatic skin in which there are major structural changes and excessive scaling. Collection of exudates from abraded sites was found to be a suitable alternative method for psoriatic skin. Arachidonic acid and 12-HETE, but not PGE2, were significantly higher in exudate from abraded lesional psoriatic skin (494 +/- 88, 45.9 +/- 4.2 and 9.6 +/- 1.8 ng/ml respectively, mean +/- sem, n = 5) compared to uninvolved skin (154 + 38, 18.5 + 5.1 and 7.7 + 1.9 ng/ml) or skin of normal volunteers (119 +/- 37, 14.5 +/- 6.7 and 4.5 +/- 1.6 ng/ml, n = 7) which were similar. The coefficient of variation for exudate collection and mediator analysis was usually less than 55%. The analysis of lipoxygenase and cyclooxygenase products was simplified by the use of chlorobutane to extract preferentially arachidonic acid and HETEs from neutral aqueous solutions.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Aged; Arachidonic Acid; Arachidonic Acids; Dinoprostone; Exudates and Transudates; Female; Humans; Hydroxyeicosatetraenoic Acids; Lipoxygenase; Male; Methods; Middle Aged; Prostaglandin-Endoperoxide Synthases; Prostaglandins E; Psoriasis; Skin

The relevance of arachidonic acid metabolites in inflammatory skin diseases has been expanded by recent developments in analytical chemistry. The metabolites include prostaglandins, leukotrienes and monohydroxy fatty acids. In ultraviolet light-induced inflammation the concentrations of arachidonic acid, prostaglandin E2, prostaglandin F2 alpha and 6-oxo-prostaglandin F1 alpha are elevated. Indomethacin totally suppresses the evoked prostaglandin increase, but erythema is only partially suppressed. This indicates that prostaglandins are partially involved in erythema production. In psoriasis the first histological change is an infiltration into the epidermis by neutrophilic leucocytes. It has been suggested that chemotactic factors, such as complement derived factors or leukotriene B4 play a role in the pathogenesis of psoriasis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acids; Cyclic AMP; Humans; Leukotriene B4; Leukotrienes; Mast Cells; Prostaglandins; Psoriasis; Skin; Skin Diseases; SRS-A; Ultraviolet Rays

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Arachidonic Acids; Humans; Leukotriene B4; Lipoxygenase; Lipoxygenase Inhibitors; Phospholipases A; Propionates; Prostaglandins; Psoriasis; Skin; Skin Diseases; Thromboxanes

Soluble guanylate cyclase activity was measured in normal and psoriatic human epidermis. The specific activity of guanylate cyclase was determined to be increased 10-fold and 3-fold in involved and uninvolved epidermis of psoriatics, respectively, compared with normal epidermis. Arachidonic acid or HETE (5 to 50 microM) stimulated guanylate cyclase activity from involved epidermis 2 to 3-fold and from uninvolved epidermis up to 2-fold, but these fatty acids had no effect on the activity of this cyclase from normal epidermis. These results indicate that the biosynthetic capacity to generate cGMP is markedly increased in involved epidermis from psoriatics because of a markedly increased specific activity of guanylate cyclase and an alteration in a property of this enzyme activity which renders it stimulable by fatty acids reported to accumulate in this lesion.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acids; Cytosol; Enzyme Activation; Guanylate Cyclase; Humans; Kinetics; Psoriasis; Skin