Biomedical subjects

K Kragballe

Publications and source records attributed to K Kragballe.

At least 73 records · Page 4Linked to original sources

PubMed1995

Efficacy, tolerability, and safety of calcipotriol ointment in disorders of keratinization. Results of a randomized, double-blind, vehicle-controlled, right/left comparative study.

BACKGROUND AND DESIGN: Disorders of keratinization are a heterogeneous group of diseases that have in common a defect in cornification. The bioactive form of vitamin D3 has been shown to modulate epidermal proliferation and differentiation. The purpose of the present study was to determine the effect of the synthetic vitamin D3 calcipotriol in a randomized, double-blind, placebo-controlled, right/left comparative study. The 67 patients included in the study were at least 12 years of age and had the following diseases: ichthyosis vulgaris (n = 9), X-linked ichthyosis (n = 8), congenital ichthyosis (n = 10), hereditary palmoplantar keratoderma (n = 20), keratosis pilaris (n = 9), and Darier's disease (n = 11). Calcipotriol ointment (50 micrograms/g) and placebo (vehicle of calcipotriol ointment) were applied to all patients twice daily for up to 12 weeks. The patients were allowed to use up to 120 g of calcipotriol ointment per week. RESULTS: At the end of the treatment regimen, calcipotriol ointment had an effect on the improvement of the ichthyoses, although to a variable degree. No therapeutic effect was detected in palmoplantar keratoderma or keratosis pilaris. Eight of 12 patients with Darier's disease had to be withdrawn because of skin irritation or a worsening of the disease. Skin irritation occurred in 18 cases (26%) only on the calcipotriol-treated side, and in one case (1%) only on the placebo-treated side. Nine cases (13%) had irritation on both sides. The amount of calcipotriol ointment used per week was lowest in palmoplantar keratoderma (mean, 11.8 g/wk; range, 2.1 to 25.6 g/wk) and highest in congenital ichthyosis (mean, 59.3 g/wk; range, 11.4 to 94.7 g/wk). There was no clinically significant change of serum calcium levels during the treatment period. CONCLUSION: Short-term treatment with calcipotriol ointment (50 micrograms/g) used in amounts up to about 100 g/wk is moderately efficacious, well-tolerated, and safe in adult patients with various ichthyoses.

Adolescent↗

PubMed1995

Vitamin D3 analogues.

The natural form of vitamin D3, 1,25-dihydroxyvitamin D3, modulates epidermal proliferation and differentiation and inhibits immune induction. Calcipotriol (calcipotriene) is a synthetic vitamin D analogue that partially separates the newly identified effects from the classic hypercalcemic effect. Topical treatment with calcipotriene has been shown to be effective, well tolerated, and safe for psoriasis.

Administration, Cutaneous↗

PubMed1994

Lysophosphatidylcholine: a chemoattractant to human T lymphocytes.

Various cell stimuli act through activation of phospholipase A2 resulting in the release of arachidonic acid, the precursor of eicosanoids, from the sn-2 position of cell membrane phospholipids. A byproduct of phospholipase A2 activity is the lysophospholipids which have been found to potentiate T-lymphocyte activation. The purpose of the present study was to determine whether the various lysophospholipids modulate the migration of peripheral normal human T lymphocytes in vitro. It was found that lysophosphatidylcholine (lysoPC) induced T-lymphocyte migration in the concentration range 10(-7) to 10(-4) M with a maximum at 10(-6) M (mean chemotactic index, 2.06). The migration was due to chemotaxis rather than chemokinesis. In contrast, lysophosphatidylethanolamine (lysoPE) and lysophosphatidylinositol (lysoPI) did not exhibit chemotactic properties towards T lymphocytes. Further studies showed that the length of the fatty acids in the sn-1 position as well as the presence of double bonds modulated the chemotactic ability. The lysoPC compound with the highest chemotactic activity was lysoPC;1-palmitoyl (C = 16:0). The results demonstrated that lysoPC, a phospholipase A2-generated hydrolysis product of phosphatidylcholine, induced T-lymphocyte chemotaxis in vitro. Because phosphatidylcholine is the major phospholipid in the epidermis, the activation of phospholipase A2 may result in the release of lysoPC in concentrations capable of inducing migration of T lymphocytes into the epidermis.

Chemotactic Factors↗

PubMed1994

Human epidermis transforms exogenous leukotriene A4 into peptide leukotrienes: possible role in transcellular metabolism.

Leukotriene B4 formation can take place by cell interaction between keratinocytes and neutrophils. Thus, keratinocytes without proven 5-lipoxygenase activity can transform neutrophil-derived leukotriene A4 into leukotriene B4. The purpose of the present study was to investigate whether human epidermis is able to transform leukotriene A4 sequentially into the peptide leukotrienes (LTC4, LTD4 and LTE4). Epidermis isolated using the suction blister technique or keratomed skin specimens were incubated with either neutrophils or exogenously added leukotriene A4. Peptide leukotrienes were determined by integrated optical density after RP-HPLC separation, and the identity of leukotrine C4 was confirmed by (1) the retention time similarity with authentic leukotriene C4; (2) the UV spectrum determined with an on-line diode array detector; and (3) conversion by gamma-glutamyl transpeptidase of the peak coeluting with authentic leukotriene C4 into a new peak coeluting with authentic leukotriene D4. The results of this study showed that while human epidermis cannot form detectable amounts of peptide leukotrienes by itself, it can transform exogenous leukotriene A4 into peptide leukotrienes. Furthermore, coincubation of human epidermis and neutrophils resulted in a marked increase (90%) in peptide leukotriene formation when compared with neutrophils alone, indicating that human epidermis can transform neutrophil-derived leukotriene A4 into peptide leukotrienes. These results indicate that human skin contains leukotriene C4 synthase activity capable of producing significant amounts of leukotriene C4 from leukotriene A4, and that the keratinocytes may play a more active role in peptide leukotriene formation in the skin than previously thought.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation↗

PubMed1994

Identification and subcellular localization of leukotriene A4-hydrolase activity in human epidermis.

The purpose of this study was to determine whether normal human epidermis could produce leukotriene B4 (LTB4) from leukotriene A4 (LTA4) ex vivo, and to localize this LTA4-hydrolase activity. Epidermis obtained by suction blister technique incubated with human polymorphonuclear cells, resulted in a 54% increase in LTB4 formation when compared to polymorphonuclear cells incubated alone. Furthermore, human epidermis transformed exogenous LTA4 into LTB4, and this reaction obeyed Michaelis-Menten kinetics with an apparent Km of 6 microM. Subcellular fractionation of homogenized epidermis localized the LTA4-hydrolase activity mainly in the 105,000 x g supernatant fraction (cytoplasmic fraction). This activity was inhibited by two inhibitors of LTA4-hydrolase (bestatin and captopril). Western blot analysis of the 105,000 x g fraction of homogenized epidermis and cultured keratinocytes supported the presence of a LTA4-hydrolase. Thus, normal human epidermis possesses LTA4-hydrolase activity which can transform exogenous LTA4 and polymorphonuclear cell-derived LTA4 into LTB4. The identification of LTA4-hydrolase in the cytoplasmic fraction of human epidermis indicates that epidermal cells may play a more active role in the enzymatic process leading to formation of the proinflammatory compound LTB4 than previously expected.

Blotting, Western↗

PubMed1994

Interleukin-8 secretion and 15-lipoxygenase activity in rheumatoid arthritis: in vitro anti-inflammatory effects by interleukin-4 and interleukin-10, but not by interleukin-1 receptor antagonist protein.

We have examined the ability of interleukin-4 (IL-4), interleukin-10 (IL-10) and interleukin-1 receptor antagonist protein (IL-1ra) to regulate spontaneous interleukin-8 (IL-8) production in cultured SF mononuclear cells (SFMC) from RA. Furthermore, we examined whether IL-4, IL-10, or IL-1ra could influence the production of the arachidonic acid products leukotriene B4 (LTB4), 12-hydroxy-eicosatetraenoic acid (12-HETE) and 15-hydroxy-eicosatetraenoic acid (15-HETE). IL-4 induced a maximal suppression of 75% in the IL-8 secretion in SFMC from 10.0 ng/ml down to 2.5 ng/ml after 24 h and from 17.2 ng/ml to 4.2 ng/ml after 72 h of culture. IL-10 induced a 55% inhibition of the IL-8 secretion at 24 h and a 40% inhibition at 72 h. IL-1ra did not change the spontaneous IL-8 secretion from rheumatoid SFMC. We also examined, whether addition of IL-4, IL-10 or IL-1ra was able to modulate formation of the arachidonic acid products LTB4, 12-HETE and 15-HETE in cultured SF cells, stimulated with the calcium ionophore A23187. 15-HETE was not detected in untreated cultures, nor in IL-10 or IL-1ra treated cultures. IL-4, however, stimulated the formation of the anti-inflammatory mediator; 15-HETE (23 ng/10(6) cells). These results suggest that IL-4 or IL-10, could have beneficial anti-inflammatory effects in RA.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1994

Comparative effects of calcipotriol solution (50 micrograms/ml) and betamethasone 17-valerate solution (1 mg/ml) in the treatment of scalp psoriasis.

The efficacy, tolerability and safety of calcipotriol solution and betamethasone 17-valerate solution were compared in a multicentre, prospective, randomized, double-blind, parallel group study. Four hundred and seventy-four patients with scalp psoriasis were recruited from six European countries and Canada. Following a 2-week washout period, either calcipotriol solution (50 micrograms/ml) or betamethasone 17-valerate solution (1 mg/ml) was applied twice daily for 4 weeks. After this time, patients who required no further active treatment were observed for relapse. Retreatment with calcipotriol was offered to those patients who relapsed, and who were originally in the calcipotriol-treated group. The two treatment groups were well matched at baseline. At the end of treatment, the proportion of patients who had 'cleared' or 'markedly improved' was statistically significantly greater in the betamethasone group (75%) than in the calcipotriol group (58%) (P < 0.001) (95% confidence interval of difference 25.3-->8.6). The decrease in total sign score (sum of scores for erythema, thickness and scaliness) at the end of treatment was also statistically significantly greater in the betamethasone group (61%) than the calcipotriol group (45%) (P < 0.001) (95% confidence interval of difference 9.7-->23.1). Adverse events were reported by 87 patients in the calcipotriol group, and 31 patients in the betamethasone group; the most common was lesional or perilesional irritation, which occurred significantly more frequently with calcipotriol (26%) than with betamethasone (8%) (P < 0.001). Fifteen patients (6%) in the calcipotriol group and four (1%) in the betamethasone group withdrew from the study because of adverse events or unacceptable treatment response (P = 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Efficacy and safety of the 20-epi-vitamin D3 analogue KH 1060 in the topical therapy of psoriasis: results of a dose-ranging study.

KH 1060 is a 20-epi-vitamin D3 analogue, structurally related to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). In vitro, KH 1060 is much more potent than 1,25(OH)2D3 in regulating cell growth and T lymphocyte mediated immune responses, despite a similar calcemic activity in vivo. Therefore, KH 1060 is of potential interest in the treatment of psoriasis and other diseases characterized by accelerated cell growth and T lymphocyte activation. In a multicenter, prospective, randomized, double-blind, vehicle-controlled right/left comparative study, patients with plaque-type psoriasis vulgaris were randomly assigned to one of the following treatment groups: (I) KH 1060 ointment 0.2 microgram/g versus placebo ointment, (II) KH 1060 ointment 0.2 microgram/g versus KH 1060 ointment 0.04 microgram/g, and (III) KH 1060 ointment 0.2 microgram/g versus KH 1060 ointment 1 microgram/g. All treatments were given twice daily for 6 weeks. Sixty-four of the 70 randomized patients completed the study. At the end of treatment, no difference was demonstrated between KH 1060 0.04 microgram/g and vehicle, whereas significantly increasing improvement was found for the doses KH 1060 0.2 microgram/g and KH 1060 1 microgram/g. According to the investigator's overall assessments at the end of treatment, KH 1060 1.0 microgram/g and KH 1060 0.2 microgram/g produced a marked or moderate improvement in most patients. Mild lesional irritation was observed after treatment with KH 1060 as well as with placebo. One patient was withdrawn because of an eczematous reaction, where KH 1060 1.0 microgram/g was applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Monohydroxy fatty acids esterified to phospholipids are decreased in lesional psoriatic skin.

Because of the increasing number of reports of the important roles of monohydroxy derivatives of poly-unsaturated fatty acids in the regulation of cell function, we determined the pools of unesterified and esterified monohydroxy fatty acids (MHFAs) in keratomed epidermal slices, taken from lesional and non-lesional psoriatic skin. Extracted phospholipids were separated by thin-layer chromatography. The isolated fractions of phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidyl-ethanolamine (PE) were treated with phospholipase A2 to release fatty acids in the sn-2 position. Released MHFAs were separated by reversed-phase and straight-phase high-performance liquid chromatography and identified as the linoleic acid derivatives 9-hydroxy-octadecadienoic acid (9-HODE) and 13-hydroxy-octadecadienoic acid (13-HODE) and as the arachidonic acid derivative 15-hydroxy-eicosatetraenoic acid (15-HETE). These findings are consistent with the presence of unesterified 9-HODE, 13-HODE and 15-HETE. In contrast, 12-hydroxy-eicosatetraenoic acid (12-HETE), although found to be present in high amounts as unesterified 12-HETE, was not detectable in the phospholipids. When compared with non-lesional psoriatic skin, the levels of 9-HODE, 13-HODE and 15-HETE esterified to the sn-2 position of PC, PI and PE in lesional psoriatic skin were significantly decreased (to 28-78% of those in non-lesional skin). This depletion of MHFAs in specific phospholipids may be due to an imbalance between phospholipase and acyltransferase activities. Because the levels of esterified MHFAs may influence signal transduction and eicosanoid metabolism the described changes may be relevant for the inflammatory processes occurring in psoriasis.

Esters↗

PubMed1993

Leukotriene B4 formation during human neutrophil keratinocyte interactions: evidence for transformation of leukotriene A4 by putative keratinocyte leukotriene A4 hydrolase.

In the present study, keratinocytes were coincubated with human neutrophils to determine whether or not an increase in leukotriene B4 formation can occur. Human keratinocytes used were cultured in serum-free, low-calcium medium, whereas neutrophils were purified from heparinized venous blood. After coincubations, formation of leukotriene B4 was determined by reversed-phase high-performance liquid chromatography, coupled with its characteristic UV scan. Confirmation and quantification was by radioimmunoassay. Our data revealed that incubations of keratinocytes (1.5 x 10(6)) alone stimulated with calcium ionophore resulted in no detectable amounts of leukotriene B4. In contrast, incubations of neutrophils (5 x 10(6)) alone resulted in the generation of 62.2 +/- 8.5 ng of LTB4. Coincubations of the neutrophils with keratinocytes (ratio 3:1) resulted in a 56-163% increase in leukotriene B4 formation. To delineate the source of the newly formed leukotriene B4, incubations of keratinocytes with leukotriene A4 revealed that keratinocytes can transform leukotriene A4 into leukotriene B4. These latter findings indicate that although keratinocytes cannot directly metabolize arachidonic acid into leukotriene B4 via the 5-lipoxygenase enzyme, they can transform neutrophil-derived leukotriene A4 into leukotriene B4, thus indicating the possible existence of a putative keratinocyte-leukotriene A4 hydrolase. It is therefore reasonable to speculate that the keratinocytes possess the capacity to generate leukotriene B4 in the epidermis when provided leukotriene A4 and thereby can amplify the inflammatory processes occurring during neutrophil exocytosis. These findings indicate that transcellular metabolism of arachidonic acid metabolites in the epidermis by keratinocytes and neutrophils may contribute to the high levels of leukotriene B4 in lesional skin of inflammatory skin diseases.

Arachidonic Acid↗

PubMed1993

Conversion of acitretin to etretinate in psoriatic patients is influenced by ethanol.

Acitretin has recently been introduced to replace etretinate in the treatment of severe psoriasis due to a considerable shorter terminal half-life. The previously recommended 2-month anticonceptive period after acitretin treatment has been extended to 2 years after the detection of etretinate in certain acitretin recipients. In the present study, 10 patients with severe psoriasis were treated with 30 mg acitretin daily for 3 months. Seven patients had detectable mean steady-state plasma etretinate concentrations in the range of 2.5 to 56.7 ng/ml. Four of the patients showed teratogenic levels of plasma etretinate. Consumption of alcohol appeared to be an important contributing factor for the formation of etretinate. As judged from the dose- and body-weight-normalized AUC values (AUCcor) there was a great inter-individual variation (sixfold) in the systemic availability of acitretin. After discontinuation of therapy, the rate of elimination of both acitretin (t1/2 range 1.0 to 25.4 d) and 13-cis-acitretin (t1/2 range 1.5 to 25.7 d) was found to be related to the observed mean steady-state level of etretinate as evidenced by a longer terminal t1/2 of patients with high levels of etretinate in plasma. A mean terminal elimination half-life of etretinate was found to be 45.7 d +/- 10.6 (mean +/- SD; range 27.0 to 59.3 d). The risk of metabolic formation of etretinate in acitretin recipients makes it impossible to draw any definite conclusion with regard to recommendation of length of anticonceptive period following acitretin therapy in psoriatics. Monitoring of plasma etretinate levels in acitretin-treated fertile women is advisable.

Acitretin↗

PubMed1993

Distribution of monohydroxy fatty acids in specific human epidermal phospholipids.

Monohydroxy derivatives of polyunsaturated fatty acids such as arachidonic acid (AA) and linoleic acid (LA) can modulate inflammation and epidermal proliferation. The purpose of this study was to determine the in vivo distribution of the AA derivatives; 12- and 15-hydroxyeicosatetraenoic acid (12-HETE and 15-HETE) and the LA derivatives; 9- and 13-hydroxyotadecadienoic acid (9-HODE and 13-HODE) in specific phospholipids of normal human skin. Lipids were extracted from 6 normal keratome skin biopsies and phospholipids were separated into the major classes by two-dimensional thin layer chromatography. Monohydroxy fatty acids (MHFAs) released from specific phospholipids after treatment with phospholipase A2 were identified by reversed phase and straight phase high-performance liquid chromatography and UV-absorption spectra. Unesterified MHFAs were determined in a similar way. 9-HODE, 13-HODE and 15-HETE were detectable in phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidylethanolamine (PE). Interestingly, 12-HETE was not detectable in these phospholipids, although the unesterified 12-HETE was detectable in amounts similar to unesterified 15-HETE. Esterified 15-HETE was equally distributed between PI and PC, in which 15-HETE was predominant, accounting for 60% and 69% of the total MHFAs, respectively (p < 0.05). These results demonstrate that the LA derivatives 9-HODE and 13-HODE, as well as the AA derivative 15-HETE, are esterified to PC, PI and PE of normal human epidermis in vivo. The possibility remains that 9-HODE, 13-HODE and 15-HETE, may mediate their biological effects by being incorporated into specific phospholipids.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1993

Treatment of psoriasis vulgaris with topical calcipotriol has no short-term effect on calcium or bone metabolism. A randomized, double-blind, placebo-controlled study.

The purpose of this double-blind, placebo-controlled study was to examine whether the vitamin D analogue calcipotriol, topically applied to psoriatic skin lesions, had any effect on calcium or bone metabolism. Thirty-four outpatients with psoriasis vulgaris were randomized to treatment with either calcipotriol ointment (50 micrograms/g) or vehicle ointment twice daily for 3 weeks. The patients were put on a calcium energy fixed diet and examined once weekly. The mean amount of calcipotriol ointment used was 40.3 g/week (range 8.2-95.4 g/week). The results of biochemical markers on calcium and bone metabolism showed no significant differences between the two groups. No correlation was found between the amount of ointment used and changes in parameters on calcium and bone metabolism during the 3-week treatment. It is concluded that calcipotriol ointment (50 micrograms/g), applied in doses of 8.2-95.4 g/week for 3 weeks to psoriatic skin lesions, has no effect on calcium or bone metabolism.

Administration, Cutaneous↗

PubMed1993

Modulation of eicosanoid formation by lesional skin of psoriasis: an ex vivo skin model.

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.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1993

[Treatment of psoriasis].

About two per cent of the Scandinavian population have manifest psoriasis, which may vary in distribution and duration. With a chronic progressive disease such as psoriasis, it is especially important to weigh the effect of treatment against its tolerance by the patient and the risk of side effects. Recent advances in pharmacology have markedly increased the range of treatment available in severe cases of psoriasis, and the recent introduction of local treatment with vitamin D has resulted in a broader range of treatment for patients with mild or moderate psoriasis. However, no curative treatment is yet within sight.

Adrenal Cortex Hormones↗

PubMed1993

Calcipotriol. A new topical antipsoriatic.

Calcipotriol is a synthetic vitamin D analogue. In vitro it can regulate cell differentiation and proliferation and suppress lymphocyte activities. These actions of calcipotriol at the cellular level are very similar to those of the natural hormone 1,25-(OH)2-D3. In contrast, the systemic effects on calcium and bone metabolism are at least 100 to 200 times less than those of 1,25-(OH)2-D3. Because of this unique pharmacologic profile, calcipotriol has been evaluated for the topical treatment of psoriasis. In well-designed and properly conducted studies involving more than 3000 patients, calcipotriol ointment, 50 micrograms/g, has been shown to be effective and safe for the short- and long-term treatment of psoriasis vulgaris. Calcipotriol ointment should be applied twice daily in amounts up to 100 g/week (Table 1). Used according to these guidelines, calcipotriol treatment does not affect calcium or bone metabolism. Calcipotriol is indicated for the treatment of plaque-type psoriasis vulgaris and has already been approved in several countries. It should be considered a first-line drug for the topical treatment of psoriasis.

Administration, Cutaneous↗

PubMed1992

Vitamin D analogues in the treatment of psoriasis.

Psoriasis is a chronic hyperproliferative skin disease in which inflammatory and immunologic processes may play important pathophysiologic roles. Recently the skin has been identified as a target tissue for vitamin D. Because 1,25-dihydroxy vitamin D3 inhibits epidermal proliferation and promotes epidermal differentiation, it has been introduced for the treatment of psoriasis vulgaris. In addition to 1,25-(OH)2-D3, synthetic vitamin D3 analogues have undergone clinical evaluation. Calcipotriol (INN) (calcipotriene [USAN]) has been studied most extensively. Compared with 1,25-(OH)2-D3, calcipotriol is about 200 times less potent in its effects on calcium metabolism, although similar in receptor affinity. Topical calcipotriol 50 micrograms/g applied twice daily is efficacious and safe for the treatment of psoriasis. Because topical calcipotriol is slightly more efficacious than betamethasone 17-valerate and dithranol, calcipotriol should be considered a first line drug in the management of psoriasis. These results illustrate that it is possible to separate the vitamin D effects on the cellular level from those on calcium metabolism not only in vitro, but also in a clinical setting.

Humans↗

PubMed1992

Effect of dihomogammalinolenic acid and its 15-lipoxygenase metabolite on eicosanoid metabolism by human mononuclear leukocytes in vitro: selective inhibition of the 5-lipoxygenase pathway.

The purpose of the present study was to determine the effect of the n-6 fatty acid, dihomogammalinolenic acid (DGLA, 20: 3, n-6) on arachidonic acid (AA) (C20: 4) metabolism by human peripheral mononuclear leukocytes (HPML). After incubation of HPML with A23187 (5 microM) and DGLA, the cyclooxygenase (CO) and lipoxygenase (LO) products were separated and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with radioimmunoassay. DGLA led to no change in PGE2 formation, but at similar concentrations there was a dose-dependent decrease in LTB4 formation (IC50 = 45.0 microM). The inhibition of LTB4 formation by DGLA was associated with a dose-dependent increase in its 15-LO metabolite 15-hydroxyeicosatraenoic acid (15-HETrE) and its CO metabolite prostaglandin E1 (PGE1). Incubation of HPLM with 15-HETrE (0-1.5 microM) alone did not result in a change in PGE2 formation, whereas 15-HETrE was a much more potent inhibitor of LTB4 formation (IC50 = 0.5 microM) than DGLA. These results show that the addition of DGLA to HPML results in a selective inhibition of LTB4 formation, presumably via its metabolite (15-HETrE).

8,11,14-Eicosatrienoic Acid↗