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K Kragballe

Publications and source records attributed to K Kragballe.

At least 55 records · Page 3Linked to original sources
PubMed1997

The future of vitamin D in dermatology.

BACKGROUND: Vitamin D3 analogs have been found to be effective in treating psoriasis. OBJECTIVE: We attempted to identify the targets and actions of vitamin D3 in the skin and to explore the availability of synthetic vitamin D3 analogs with selective actions on particular cell types or cell functions. METHODS: A review of the literature focused on the cellular targets of vitamin D3 in the skin and within the immune system. Furthermore, the use of novel vitamin D3 analogs in skin diseases other than psoriasis was reviewed. RESULTS: The vitamin D receptor has been detected in most skin cells, which means that keratinization, hair growth, melanogenesis, fibrogenesis, angiogenesis, and immune-mediated processes are potential targets for vitamin D3. Vitamin D3 analogs have been synthesized with a higher therapeutic index or a higher degree of selectivity than the natural form of vitamin D3. CONCLUSION: Vitamin D3 analogs with wide-ranging clinical applications may become available for dermatology.

Adjuvants, Immunologic↗
PubMed1996

LTA4 hydrolase in human skin: decreased activity, but normal concentration in lesional psoriatic skin. Evidence for different LTA4 hydrolase activity in human lymphocytes and human skin.

Leukotriene A4 (LTA4) hydrolase which transforms LTA4 into the proinflammatory compound LTB4 has been identified in human epidermis. The purpose of this study was to investigate the potential role of this enzyme in psoriasis, in which LTB4 is present in biologically active concentrations. The concentration and activity of LTA4 hydrolase was determined in normal skin and in matched samples of involved and uninvolved psoriatic skin. The enzyme content was determined using an affinity-purified antibody. This antibody was also used for immunohistochemical staining of skin biopsies. Immunohistochemically LTA4 hydrolase was localized predominantly in the basal and spinous layers in normal skin and in involved and uninvolved psoriatic skin. The LTA4 hydrolase content varied between 2.8 and 3.1 micrograms enzyme/mg protein and was found to be similar in normal and psoriatic skin, involved as well as uninvolved. In contrast, the activity of the enzyme was decreased significantly in involved psoriatic skin (9.9 +/- 2.1 micrograms LTB4/mg enzyme per min) compared with matched uninvolved psoriatic skin (16.4 +/- 3.5 micrograms LTB4/mg enzyme per min), but was decreased only insignificantly compared with normal skin (12.4 +/- 1.8 micrograms LTB4/mg enzyme per min). It was found that the conversion of LTA4 to LTB4 results in inactivation of LTA4 hydrolase activity. This finding is compatible with the idea that the decreased LTA4 hydrolase activity in involved psoriatic skin reflects transcellular LTB4 formation in vivo. In peripheral lymphocytes the enzyme content was 1.3 +/- 0.3 microgram enzyme/mg protein in normal lymphocytes and 1.4 +/- 0.3 microgram enzyme/mg protein in psoriatic lymphocytes, which was significantly lower than in the skin. In contrast, the specific LTA4 hydrolase activities in normal and psoriatic lymphocytes (23.4 +/- 1.3 and 21.3 +/- 1.7 micrograms LTB4/mg enzyme per min) were significantly higher than in normal skin. These findings may indicate the existence of LTA4 hydrolase isoforms in human lymphocytes and human skin.

Animals↗
PubMed1996

Effects of psychologic intervention on psoriasis: a preliminary report.

BACKGROUND: Case reports have indicated that psychologic treatments may have a beneficial effect on psoriasis activity. OBJECTIVE: Our purpose was to further investigate the hypothesis that psychologic intervention has a beneficial effect on psoriasis activity in a blinded, controlled manner. METHODS: Fifty-one patients with psoriasis vulgaris were randomly assigned to a treatment or a control group. Patients in the treatment group participated in seven individual psychotherapy sessions in 12 weeks. Intervention techniques included stress management, guided imagery, and relaxation. The Psoriasis Area Severity Index (PASI), Total Sign Score (TSS), and Laser Doppler Skin Blood Flow (LDBF) of a selected reference plaque was measured in a blinded fashion at baseline (week 0), week 4, week 8, and after treatment (week 12). RESULTS: Slight, but significant, changes in TSS and LDBF were found in the treatment group but not in the control group. When analyses were performed for both groups separately, the treatment group displayed significant reductions for all three psoriasis activity measures, whereas no changes were seen in the control group. CONCLUSION: Our preliminary results suggest that psychologic intervention may have a moderate beneficial effect on psoriasis activity.

Adult↗
PubMed1996

All-trans retinoic acid inhibits binding of 1,25-dihydroxy-vitamin D3 to the vitamin D receptor in cultured human keratinocytes.

Psoriasis is characterized by hyperproliferation and impared differentiation of epidermal keratinocytes (KCs). Psoriasis can be treated with derivatives of retinoic acid (RA) and vitamin D3. Analogues of vitamin D3 are able to inhibit proliferation and stimulate differentiation of KCs. In contrast, RA inhibits terminal differentiation of KCs. Interactions are known to occur between RA and vitamin D3 signalling pathways. The purpose of the present study was to determine the effect of all-trans RA on the binding of 1,25-dihydroxy-vitamin D3 (1,25 (OH)2D3) to the vitamin D3 receptor (VDR) of cultured human KCs. Cultured KCs from normal adults were incubated with or without RA (10-9-10-7M) for 4-24 h. Cells were then harvested, homogenized and ultrasonicated. The extracted protein was incubated with 3H-1,25 (OH)2D3 (0.015-1.0 nM) with or without 250-fold excess nonradioactive 1,25 (OH)2D3 for 24 h and specific binding was determined by use of the dextran coated charcoal binding assay. Western blot analysis utilizing the monoclonal antibody 9A7 gamma to VDR was performed on protein extracted from the KCs. The bands resulting from Western blot analysis were visualized by enhanced chemiluminescence. From Scatchard analysis it was found that KCs bind 1,25 (OH)2D3 with high affinity (Kd = 0.175 nM). This binding was dose and time dependently inhibited by RA (60% inhibition at 10-7 M after 24 h of incubation). By Western blot analysis, RA had no effect on the amount of protein extracted from KCs at any of the RA concentrations tested. In conclusion, these results show that binding of vitamin D3 to its receptor of human KCs can be inhibited markedly by RA without effecting the amount of protein. These results are in contrast to results with other cell types in which RA upregulates binding of 1,25 (OH)2D3 to the VDR. Because interaction between retinoids and vitamin D3 may occur at different levels during signal transduction, it is not possible to predict from our results whether RA will inhibit the effects of vitamin D3 in vivo.

Calcitriol↗
PubMed1996

Cyclosporin A down-regulates the LTA4 hydrolase level in human keratinocyte cultures.

Leukotriene A4 hydrolase is a key enzyme in the biosynthesis of leukotriene B4, a potent pro-inflammatory compound. The purpose of this study was to determine the capacity of antiinflammatory and anti-proliferative compounds to regulate the levels and activity of leukotriene A4 hydrolase in cultured human keratinocytes. The content of leukotriene A4 hydrolase was determined by Western blot analysis, and the activity of leukotriene A4 hydrolase was expressed as the leukotriene B4 formation after incubation of keratinocyte cultures with leukotriene A4. Leukotriene B4 was measured by revered-phase high performance liquid chromatography. Preincubation for 10 min of the cultured keratinocytes with the leukotriene A4 hydrolase inhibitor RP 64699 (0.1-10 microM) caused a significant dose-dependent inhibition of leukotriene B4 formation (IC50 = 0.7 microM). Cyclosporin A (0.1 micrograms/ml and 1.0 micrograms/ml) had no direct effect on leukotriene A4 hydrolase activity, but after incubation for 72 h there was a decrease in the mean leukotriene B4 formation per culture dish (35% and 48%, respectively). The decreased leukotriene B4 formation was caused mainly by a decrease in the mean leukotriene A4 hydrolase content per mg protein (30.1% at 0.1 micrograms/ml cyclosporin A and 40.0% at 1.0 micrograms/ml cyclosporin A), although keratinocyte proliferation was also slightly decreased. Incubations with 1.25-dihydroxyvitamin D3 (10(-7)-10(-10) M), all-trans retinoic acid (10(-6)-10(-10) M), eicosartienoic acid (10(-6)-10(-8) M), dexamethasone (10(-5)-10(-7) M), interferon-gamma (10 and 100 units/ml) or methotrexate (0.1-10 micrograms/ml) had no effect on either the leukotriene B4 formation or the amount of leukotriene A4 hydrolase in keratinocyte cultures. These results show that cyclosporin A, in contrast to other anti-inflammatory and anti-proliferative compounds, inhibits the level of leukotriene A4 hydrolase in keratinocyte cultures. Since similar cyclosporin A concentrations are obtained during treatment of psoriasis with cyclosporin A, the effect on leukotriene A4 hydrolase may play a role in the anti-inflammatory action of cyclosporin A.

8,11,14-Eicosatrienoic Acid↗
PubMed1996

Flow-cytometric investigation of epidermal cell characteristics in monogenic disorders of keratinization and their modulation by topical calcipotriol treatment.

A flow-cytometric study was performed in monogenic disorders of keratinization, to assess DNA distribution as well as the expression of keratins and involucrin. In addition, the changes in expression of these markers under influence of calcipotriol treatment were investigated. Proliferation, measured by the percentage of epidermal cells in SG2M-phase of the cell cycle, was increased in Darier's disease, lamellar ichthyosis, congenital bullous ichthyotic erythroderma of Brocq and the Comel-Netherton syndrome, whereas normal proliferation was found in autosomal dominant ichthyosis vulgaris, X-linked recessive ichthyosis, keratosis pilaris, ichthyosis bullosa of Siemens and the Sjögren-Larsson syndrome. Keratin 6 was enhanced in erythrodermic lamellar ichthyosis, congenital bullous ichthyotic erythroderma of Brocq and the Comel-Netherton syndrome, showing also reduction of keratin 10. Involucrin was only slightly reduced in erythrodermic lamellar ichthyosis, congenital bullous ichthyotic erythroderma of Brocq and the Comel-Netherton syndrome, compared to the pronounced reduction in all other skin disorders studied. Calcipotriol was found to enhance differentiation in Darier's disease, erythrodermic lamellar ichthyosis, and congenital bullous ichthyotic erythroderma of Brocq. Only Darier's disease did not show clinical improvement. In conclusion, flow cytometry provides a useful method for quantification of epidermal cell characteristics in monogenic disorders of keratinization. Further studies need to be performed to establish its usefulness as a diagnostic and prognostic tool.

Administration, Topical↗
PubMed1996

Normal levels of the vitamin D receptor and its message in psoriatic skin.

Treatment with vitamin D3 analogs improves psoriasis. The vitamin D receptor (VDR) mediates most, if not all, the effects of vitamin D3. The purpose of this study was to determine the levels of the VDR mRNA and VDR protein in normal and in involved and uninvolved psoriatic skin. Although VDR mRNA was not detected by Northern analysis of human skin samples, it was readily detectable by use of the more sensitive ribonuclease protection assay. The VDR mRNA levels were normal in acute guttate as well as in chronic plaque lesions. There was also no difference in VDR mRNA levels between normal and uninvolved psoriatic skin. The VDR protein was detected by Western analysis using the monoclonal 9A7 gamma anti-VDR antibody and a polyclonal rabbit anti-VDR antibody. For comparison, VDR levels were analyzed in cultures of normal human keratinocytes and the epithelial cell line MCF-7. Studies of the extraction procedures for VDR showed that at least 60% of Escherichia coli-expressed VDR added to the skin biopsy specimens was recovered. The VDR concentration in normal human adult skin was approximately 50 pg/microgram protein, and the concentrations of VDR in involved and uninvolved psoriatic skin were of the same order of magnitude. Using the 9A7 gamma anti-VDR antibody, the VDR (M(r) 53,000) was constantly present in lower amounts than a band of M(r) 80,000 in both skin specimens and keratinocyte cultures. This high-molecular-weight band is most likely a cross-reacting protein not related to VDR, because it was absent when using the polyclonal anti-VDR antibody.

Adult↗
PubMed1996

The vitamin D3 analog calcipotriol suppresses the number and antigen-presenting function of Langerhans cells in normal human skin.

Local activation of T lymphocytes appears to play an important role in psoriasis and autoimmune skin disease. 1 alpha,25-dihydroxyvitamin D3 and the vitamin D3 analog calcipotriol have been shown to inhibit immune induction in vitro. The purpose of the present study was to investigate the in vivo effect of calcipotriol on Langerhans cells in normal human skin and to determine the effect of 1,25-dihydroxyvitamin D3 and calcipotriol on isolated Langerhans cells to induce autologous T-cell proliferation. Using confocal laser scanning microscopy of epidermal suction blister roofs, it was found that application of calcipotriol cream to normal human skin for 4 d resulted in a dose-dependent decrease in the number of CD1a+ cells with a dendritic morphology and in the number of dendrites per cell. The suppressive effect of calcipotriol on Langerhans cells was as strong as that of the potent corticosteroid mometasonfuroate. In Langerhans cell-enriched cell suspensions (60-97% pure) isolated from normal human skin, 1,25-dihydroxyvitamin D3 and calcipotriol (10(-8)-10(-7) M) significantly suppressed their ability to stimulate antigen-dependent T-cell proliferation. Furthermore, the vitamin D receptor was detected by Western blot analysis in the isolated Langerhans cells. Neither immunohistochemical studies nor flow cytometry of Langerhans cells showed any change in the human leukocyte antigen-DR expression after 48 h culture with antigen with or without calcipotriol. It is proposed that the inhibitory effects of the vitamin D3 on Langerhans cells may induce immunosuppression in the skin.

Adult↗
PubMed1995

Purification and characterization of leukotriene A4 hydrolase from human epidermis.

The leukotriene A4 hydrolase is a central enzyme in leukotriene B4 formation. Unlike 5-lipoxygenase, leukotriene A4 hydrolase activity is present in normal human epidermis, where it is likely to be involved in transcellular leukotriene formation. In this study the leukotriene A4 hydrolase was purified from human epidermis and human cultured keratinocytes and compared with leukotriene A4 hydrolase from human neutrophils. To purify leukotriene A4 hydrolase from human epidermis a new non-specific affinity chromatography column, with the leukotriene A4 hydrolase inhibitor bestatin coupled to AH-Sepharose, was introduced. The epidermal leukotriene A4 hydrolase was purified to apparent homogeneity and the molecular weight was determined to be approximately 70,000 Da by SDS-PAGE. The pI was 5.1-5.4 for the epidermal as well as the keratinocyte and neutrophil leukotriene A4 hydrolase, as determined by chromatofocusing. Only minor differences in the amino acid composition were seen between the three enzyme sources. The optimal pH for the hydrolase activity was 7.5-8.5 for the epidermal and neutrophil leukotriene A4 hydrolases. Finally, it was also shown that the epidermal leukotriene A4 hydrolase undergoes suicide inactivation when transforming leukotriene A4 into leukotriene B4. It was concluded that there is a close resemblance between the epidermal leukotriene A4 hydrolase and the hydrolase found in other cell types. Therefore, the human epidermis may be a good model for the in vivo study of transcellular leukotriene formation.

Cells, Cultured↗
PubMed1995

Interleukin 13 suppresses cytokine production and stimulates the production of 15-HETE in PBMC. A comparison between IL-4 and IL-13.

We examined the ability of rIL-13 to regulate rIL-l alpha induced IL-1 beta, IL-1 receptor antagonist (IL-1ra) and IL-8 production in cultured peripheral blood mononuclear cells (PBMC), endothelial cells and fibroblasts. Furthermore we examined whether rIL-13 could influence the production of the arachidonic acid products LTB4, 12-HETE and 15-HETE by PBMC. rIL-1 alpha-stimulated PBMC cultures secreted high levels of IL-1 beta and IL-8; this could be inhibited to the level of unstimulated control cells by co-incubation with rIL-13 (10 ng/ml). IL-13 induced a 3-fold increase of the IL-1ra secretion which was inhibited by rIFN-gamma. In the presence of both rIL-1 alpha and rIL-13, endothelial cells increased IL-8 secretion, whereas dermal fibroblasts remained unchanged. Of the arachidonic acid metabolites examined, the greatest change was observed in the formation of 15-HETE. In unstimulated PBMC cultures the amount of 15-HETE was less than 4 ng/10(6) cells, whereas after addition of rIL-13 we measured a formation of 139 +/- 6.2 ng/10(6) cells. The effect of rIL-13 on the 15-HETE formation in PBMC was abolished by addition of 100 U/ml rIFN-gamma. rIL-13 only induced minor changes in the LTB4 and 12-HETE formation. Compared to IL-4, IL-13 induced a similar alteration of the cytokine cascade and arachidonic acid metabolism, supporting the hypothesis that the two cytokines use a common receptor complex or signal pathway.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Increased lysophosphatidylcholine content in lesional psoriatic skin.

Various cell stimuli occur via activation of phospholipase A2, which hydrolyses polyunsaturated fatty acids from the sn-2 position of membrane phospholipids, resulting in the formation of polyunsaturated fatty acids and lysophospholipids. The level of lysophospholipids is determined by the balance between phospholipase A2 activity and the rate of catabolism of the lysophospholipids. One of the lysophospholipid classes, lysophosphatidylcholine, has been shown to stimulate certain leucocyte activities which are of importance for the induction and maintenance of inflammation. In addition, it has been demonstrated that phospholipase A2 activity is increased in psoriatic skin. In the present study, we analysed the levels of lysophosphatidylcholine, by thin layer chromatography, in lesional psoriatic skin, uninvolved psoriatic skin and normal skin. The lysophosphatidylcholine content, expressed as mumol lysophosphatidylcholine/mumol phosphatidylcholine, was 1.55, 0.21 and 0.12% in lesional psoriatic skin, uninvolved psoriatic skin and normal skin, respectively. The level of lysophosphatidylcholine was significantly elevated in lesional compared with uninvolved psoriatic skin (P = 0.004) and normal skin (P = 0.002). The increased lysophosphatidylcholine levels in psoriatic skin indicate that the phospholipase A2 activation is not accompanied by a corresponding increase in the activity of enzymes catabolizing lysoPC. If present in biologically active concentrations, lysophosphatidylcholine may contribute to the induction and maintenance of the inflammatory and immunological processes occurring in lesional psoriatic skin.

Humans↗
PubMed1995

Characterization of the aminopeptidase activity of epidermal leukotriene A4 hydrolase against the opioid dynorphin fragment 1-7.

Leukotriene A4 hydrolase is a bifunctional cytosolic enzyme, which both hydrolyses leukotriene A4 (LTA4) into leukotriene B4 (LTB4) and exerts aminopeptidase activity against opioid peptides. In the present study we have investigated whether the peptides angiotensin I and II, bradykinin, kallidine, histamine, dynorphin fragment 1-7 and substance P can act as substrates for epidermal and neutrophil LTA4 hydrolase. Among the tested substrates, dynorphin fragment 1-7 was found to be the best substrate for the enzyme. The aminopeptidase activity of epidermal and neutrophil LTA4 hydrolase against dynorphin fragment 1-7 was further characterized. The enzyme was purified from human epidermis and human neutrophils by anion exchange chromatography (Q-Sepharose) and affinity chromatography on a column with the LTA4 hydrolase inhibitor bestatin coupled to AH-Sepharose. The incubation of the dynorphin fragment 1-7 with LTA4 hydrolase resulted in the formation of tyrosine. The presence of the N-terminal amino acid tyrosine is essential for the interaction of opioids with their receptors, and this finding indicates that the LTA4 hydrolase can inactivate dynorphin fragment 1-7. After the two purification steps no other aminopeptidases acting at the N-terminal tyrosine of dynorphin fragment 1-7 was present in the preparation. This was demonstrated by the abolishment of the degradation at the N-terminal end of dynorphin fragment 1-7 when preincubating the enzyme preparation with LTA4 before the incubation with the dynorphin fragment 1-7. The abolishment of the aminopeptidase activity shows that activation of the hydrolase part of the enzyme, with conversion of LTA4 into the potent proinflammatory compound LTB4, results in an inhibition of the aminopeptidase activity of the enzyme. As a result, the catabolism of dynorphin fragment 1-7 and probably of other opioid peptides is inhibited, resulting in sustained biological effects of these opioids. This phenomenon may be important for the maintenance of inflammation in skin conditions, such as psoriasis and atopic dermatitis, in which LTB4 is formed.

Amino Acid Sequence↗
PubMed1995

Incorporation of 15-hydroxyeicosatrienoic acid in specific phospholipids of cultured human keratinocytes and psoriatic plaques.

15-hydroxyeicosatrienoic acid, 15-HETrE, the 15-lipoxygenase product of dihomogammalinolenic acid (DGLA), can inhibit the biosynthesis of the proinflammatory eicosanoids leukotriene B4 (LTB4) and 12-hydroxyeicosatetraenoic acid (12-HETE). The purpose of the present study was to investigate the incorporation of [14C]15-HETrE in specific membrane phospholipids of cultured human keratinocytes in vitro. [14C]15-HETrE was rapidly incorporated into keratinocytes. When a plateau was reached after 3 hours, 15% of the added radioactivity was incorporated into lipids; 96.5% into phospholipids (PL) and 3.5% into neutral lipids (NL). Within the phospholipid classes, [14C]15-HETrE showed selectivity for incorporation into phosphatidylinositol (PI). The mean proportion of [14C]15-HETrE in the PI, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was 83.2%, 8.5% and 8.3%, respectively. We then investigated the incorporation of 15-HETrE in epidermal phospholipids of psoriatic skin intralesionally injected with 15-HETrE. Four patients took part in the study. In each patient four identical plaques were injected with 0.65 ml of 2.0 microM, 6.2 microM, 18.6 microM of 15-HETrE (0.4 micrograms, 1, 2 micrograms and 3.6 micrograms respectively) or 0.65 ml of 0.88% NaCl twice a week. After 3 wk keratome biopsies were obtained from the treated plaques. Phospholipids extracted from the skin biopsies were separated into major classes by two-dimensional thin layer chromatography. 15-HETrE was then released from specific phospholipids after treatment with phospholipase A2 and identified by reverse phase and straight phase high performance liquid chromatography. There was a dose-dependent incorporation of 15-HETrE into the specific phospholipids PI and PC. When expressed as ng 15-HETrE/micrograms phospholipid phosphate, 15-HETrE accumulated preferentially in PI.(ABSTRACT TRUNCATED AT 250 WORDS)

8,11,14-Eicosatrienoic Acid↗
PubMed1995

Calcipotriol: a new drug for topical psoriasis treatment.

Vitamin D is best known for its role in the regulation of calcium and bone metabolism. The effects of the biologically active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25 (OH)2D3), are mediated by binding to a specific intracellular vitamin D receptor, which is present in most tissues including the skin where it regulates the growth of epidermal cells. Calcipotriol is a synthetic analogue of 1,25(OH)2D3. In vitro the activity of calcipotriol is comparable to that of 1,25(OH)2D3. In vivo, however, the risk of calcipotriol changing calcium metabolism is greatly reduced. Animal studies have established that calcipotriol is 100-200 times less calcaemic than 1,25(OH)2-D3. This low calcaemic activity is mainly due to the rapid metabolism of calcipotriol. This pharmacological profile makes calcipotriol an ideal candidate for topical treatment of hyperproliferative skin disorders, such as psoriasis. This paper reviews the clinical experience with calcipotriol in psoriasis patients.

Administration, Topical↗