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K Kragballe

Publications and source records attributed to K Kragballe.

At least 19 recordsLinked to original sources
PubMed2006

A 52-week randomized safety study of a calcipotriol/betamethasone dipropionate two-compound product (Dovobet/Daivobet/Taclonex) in the treatment of psoriasis vulgaris.

BACKGROUND: The calcipotriol/betamethasone dipropionate two-compound product Dovobet/Daivobet/Taclonex(LEO Pharma A/S, Ballerup, Denmark) has been shown to be safe and effective in the treatment of psoriasis for up to 8 weeks. As psoriasis is a chronic disease, long-term treatment may be required, so there is a need to investigate the safety of its use over a longer period of time. OBJECTIVES: To investigate the safety of two treatment regimens involving use of the two-compound product over 52 weeks in the treatment of patients with psoriasis. METHODS: Patients (n = 634) were randomized double-blind to treatment with: (i) 52 weeks of the two-compound product (two-compound group); (ii) 52 weeks of alternating 4-week periods of the two-compound product and calcipotriol (alternating group); or (iii) 4 weeks of the two-compound product followed by 48 weeks of calcipotriol (calcipotriol group). Treatments in all groups were used once daily when required. RESULTS: Adverse drug reactions (ADRs) occurred in 45 (21.7%) patients in the two-compound group, 63 (29.6%) in the alternating group and 78 (37.9%) in the calcipotriol group. The odds ratio for an ADR in the two-compound group relative to the calcipotriol group was 0.46 (95% confidence interval 0.30-0.70; P < 0.001). ADRs of concern associated with long-term topical corticosteroid use occurred in 10 (4.8%) patients in the two-compound group, six (2.8%) in the alternating group and six (2.9%) in the calcipotriol group; those with the highest incidence were skin atrophy, occurring in four (1.9%), one (0.5%) and two (1.0%) patients, respectively, and folliculitis, in three (1.4%), one (0.5%) and no patients, respectively. CONCLUSIONS: Treatment with the two-compound product for up to 52 weeks appears to be safe and well tolerated whether used on its own or alternating every 4 weeks with calcipotriol treatment.

Adult↗
PubMed2006

Consistency of data in six phase III clinical studies of a two-compound product containing calcipotriol and betamethasone dipropionate ointment for the treatment of psoriasis.

BACKGROUND: Calcipotriol and betamethasone dipropionate are both proven products in the topical treatment of psoriasis. The efficacy and tolerability of a new ointment containing these two compounds has been assessed in six phase III clinical studies. OBJECTIVE: To compare the results obtained in the clinical studies of the new calcipotriol/betamethasone dipropionate ointment. METHODS: A total of 6050 patients with psoriasis took part in the six randomized, double-blind studies. The two-compound product was compared with each of the active constituents, either in the new ointment vehicle or in the marketed formulation. RESULTS: After 4 weeks of treatment the mean reduction in the Psoriasis Area and Severity Index (PASI) ranged from 65 to 74% with the two-compound product applied once or twice daily, from 46 to 59% with calcipotriol alone and from 57 to 63% with betamethasone dipropionate alone. The tolerability profile of the two-compound product was similar to betamethasone dipropionate monotherapy and better than calcipotriol alone. CONCLUSION: The new two-compound product containing calcipotriol and betamethasone dipropionate was found to consistently provide rapid, highly effective treatment of psoriasis vulgaris.

Adult↗
PubMed2006

Recommendations for the use of etanercept in psoriasis: a European dermatology expert group consensus.

BACKGROUND: Psoriasis is a chronic, inflammatory skin disorder that has a significant impact on quality of life and, particularly in moderate to severe cases, adversely affects the patient's overall health and well-being. Biological treatments, such as etanercept, are being widely adopted across Europe for treatment of moderate to severe psoriasis due to favourable safety and efficacy profiles. The increase in usage, combined with a growing body of clinical evidence, has identified a need to clarify the best use of etanercept within its current treatment label. OBJECTIVE: To prepare a series of recommendations agreed by an expert group of dermatologists, relating to the most effective use of etanercept for psoriasis in Europe, within the product license. METHODS: An expert panel of dermatologists from across Europe completed a Delphi survey to address the current use of etanercept in psoriasis in Europe. In June 2005 the results were presented to the expert panel at their nominal group meeting, and a consensus was agreed. RESULTS: It was recommended that, where possible, patients are initiated on the 50 mg twice-weekly (BIW) dose. Etanercept should be given until remission is achieved (maximum 24 weeks) and retreatment should be initiated according to the physician's judgement. Before commencing treatment, contraindications, such as infection or previous malignancy (within 5 years), should be ruled out. CONCLUSIONS: The consensus presented herein provides valuable clarification of use of etanercept according to the label, which may have wider implications relating to the use of all biological therapies in psoriasis.

Adolescent↗
PubMed2006

Efficacy results of a 52-week, randomised, double-blind, safety study of a calcipotriol/betamethasone dipropionate two-compound product (Daivobet/Dovobet/Taclonex) in the treatment of psoriasis vulgaris.

BACKGROUND: The calcipotriol/betamethasone dipropionate two-compound product is safe and effective in the short-term treatment of psoriasis. OBJECTIVE: The primary objective was to investigate the safety of two treatment regimens involving use of the two-compound product over 52 weeks. The efficacy results are presented here. METHODS: Six hundred and thirty-four patients were randomised double-blind to treatment (once daily, when required) with either: 52 weeks of two-compound product (two-compound group), 52 weeks of alternating 4-week periods of two-compound product and calcipotriol (alternating group), or 4 weeks of two-compound product followed by 48 weeks of calcipotriol (calcipotriol group). RESULTS: There was a trend towards a difference between treatments from the overall treatment effect for the percentage of satisfactory responses for each patient during the study (p = 0.071). This appeared to be due to the comparison of the two-compound and calcipotriol groups (p = 0.025). CONCLUSION: There was a trend towards the efficacy of the two-compound product used for up to 52 weeks being better than that of 4 weeks of the two-compound product followed by 48 weeks of calcipotriol.

Anti-Inflammatory Agents↗
PubMed2005

The mitogen-activated protein kinases p38 and ERK1/2 are increased in lesional psoriatic skin.

BACKGROUND: Alterations in specific signal transduction pathways may explain the hyperproliferation and abnormal differentiation of the keratinocytes as well as the increased expression of inflammatory cytokines seen in psoriasis. Major signalling pathways used by eukaryotic cells to transduce extracellular signals into cellular responses impinge on the mitogen-activated protein kinases (MAPKs). OBJECTIVES: To investigate the expression of the MAPK p38, extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) in psoriatic skin. METHODS: Keratome biopsies were taken from patients with plaque-type psoriasis. Western blot analysis was used to determine p38, ERK and JNK activity and protein levels, whereas kinase assays were used to examine the kinase activity of p38. RESULTS: We demonstrated increased levels of the phosphorylated forms of p38 and ERK1/2 in lesional psoriatic skin compared with nonlesional psoriatic skin. No abnormality was found in the activation and expression of JNK1/2. Ex vivo kinase assays confirmed the increased activation of p38, and furthermore demonstrated increased kinase activity of the p38 isoforms p38alpha, p38beta and p38delta in lesional compared with nonlesional psoriatic skin. p38gamma was not detected in the psoriatic skin. Clearance of the psoriatic lesions, induced by climatotherapy at the Dead Sea for 4 weeks, led to a normalization in the activity of both p38 and ERK1/2. CONCLUSIONS: Taken together, our results demonstrate that the activity of the MAPKs p38alpha, p38beta and p38delta and ERK1/2 are increased in lesional psoriatic skin compared with nonlesional psoriatic skin, and that clearance of psoriasis normalizes the p38 and ERK1/2 activity. Thus, p38 and ERK1/2 might be potential targets in the treatment of psoriasis.

Adult↗
PubMed2005

The dynamics of gene expression of interleukin-19 and interleukin-20 and their receptors in psoriasis.

BACKGROUND: Interleukin (IL)-20 and IL-19 are recently discovered members of the IL-10 family of cytokines. The skin of transgenic mice overexpressing IL-20 shows histological changes resembling some of those seen in psoriasis, i.e. thickened epidermis, hyperkeratosis and a compact stratum corneum. IL-19 and IL-20, as well as their receptor complexes, IL-20Ralpha/IL-20Rbeta and IL-22Ralpha/IL-20Rbeta, are expressed in human skin. OBJECTIVES: To study the dynamics of IL-19 and IL-20 gene expression as well as the expression of their receptor subunits in psoriatic skin lesions. METHODS: Punch biopsies from patients with plaque-type psoriasis were collected before, during and after 28 days of treatment with either calcipotriol or ciclosporin (CsA). IL-20, IL-19, IL-20Ralpha, IL-20Rbeta and IL-22Ralpha mRNA expression were determined by quantitative reverse transcriptase-polymerase chain reaction. RESULTS: We found IL-19 and IL-20 mRNA expression in lesional psoriatic skin to be strongly upregulated compared with nonlesional psoriatic skin by a factor of 65 and 22, respectively. In contrast to previous reports, IL-20Ralpha and IL-20Rbeta mRNA levels showed a modest but statistically significant decrease in lesional psoriatic skin compared with nonlesional psoriatic skin. During treatment with calcipotriol or CsA, IL-19 and IL-20 mRNA levels decrease in accordance with the clinical improvement of psoriasis. Neither IL-19, IL-20, nor receptor subunit mRNA expression in lesional psoriatic skin reaches the levels of nonlesional skin during this short-term treatment. These findings are in line with the residual disease activity observed at the end of treatment. CONCLUSIONS: The increased IL-19 and IL-20 mRNA expression levels in lesional psoriatic skin suggest that these two cytokines play a role in the pathogenesis of psoriasis. An imbalance in the receptor complexes for IL-19 and IL-20 might contribute to their suspected pathogenic effects.

Adult↗
PubMed2005

Recommendations for the topical treatment of psoriasis.

Several topical treatments are available for patients with psoriasis. Although individualization of the treatment remains important, there is a need for treatment recommendations to identify the best treatment out of the available treatments and to help with improvement in treatment compliance. In this communication we give our views on the assessment of severity of psoriasis. We provide recommendations for selection of treatments, reconciling the clearance phase and the long-term management. Finally, we provide recommendations for the treatment of particular localizations: the scalp and psoriasis at sensitive sites.

Administration, Cutaneous↗
PubMed2005

A two-compound product containing calcipotriol and betamethasone dipropionate provides rapid, effective treatment of psoriasis vulgaris regardless of baseline disease severity.

BACKGROUND: A two-compound product containing calcipotriol and betamethasone dipropionate (Daivobet/Dovobet) has been evaluated in a large clinical trial programme, providing a wealth of data on the treatment of psoriasis vulgaris. OBJECTIVE: To determine the effectiveness of the two-compound product in patients with mild, moderate and severe psoriasis vulgaris. METHODS: Data from over 1,534 patients with psoriasis vulgaris who received the two-compound product once daily for at least 4 weeks in four randomised, double-blind studies were pooled. A meta-analysis of the pooled data is presented. Severity of psoriasis at baseline was determined by investigator assessment and Psoriasis Area and Severity Index (PASI) score. RESULTS: For patients with severe disease defined by PASI score (PASI baseline > or = 17), the mean reduction in PASI after up to 4 weeks of treatment was 71.6% compared with 68.9 and 67.2% for those with moderate (PASI baseline 5.1-16.0) and mild disease (PASI baseline < or = 5). Corresponding reductions for investigator-assessed severity were 72.6, 69.1 and 68.7%, respectively. CONCLUSION: Although the meta-analysis of the data from these four studies was performed post hoc, we may conclude that the two-compound product provided highly effective treatment of psoriasis, regardless of the category of baseline disease severity.

Administration, Topical↗
PubMed2004

Efficacy of once-daily treatment regimens with calcipotriol/betamethasone dipropionate ointment and calcipotriol ointment in psoriasis vulgaris.

BACKGROUND: A two-compound ointment containing calcipotriol 50 micro g g-1 and betamethasone dipropionate 0.5 mg g-1 has recently been shown to be an effective treatment for psoriasis. OBJECTIVES: This study was designed to investigate efficacy and safety of different treatment regimens with the two-compound product (Daivobet/Dovobet; LEO Pharma, Ballerup, Denmark) and calcipotriol 50 micro g g-1 ointment (Daivonex/Dovonex; LEO Pharma). METHODS: In total, 972 patients with psoriasis vulgaris were randomized to one of three treatment regimens: group 1, the two-compound product once daily for 8 weeks followed by calcipotriol ointment once daily for 4 weeks; group 2, the two-compound product once daily for 4 weeks followed by 8 weeks of treatment with calcipotriol ointment once daily on weekdays and the two-compound product once daily at weekends; and group 3, calcipotriol ointment twice daily for 12 weeks. The efficacy was evaluated by Psoriasis Area and Severity Index (PASI) and investigators' global assessments of disease severity. The primary response criteria were percentage reduction in PASI and proportion of patients with absent/very mild disease according to the investigators' global assessments after 8 weeks of treatment. RESULTS: The mean reduction in PASI from baseline to the end of 8 weeks of treatment was 73.3% for group 1, 68.2% for group 2 and 64.1% for group 3. The proportion of patients with absent/very mild disease at the end of 8 weeks of treatment was 55.3% for group 1, 47.7% for group 2 and 40.7% for group 3. For both primary response criteria, group 1 was statistically superior to group 3 (P < 0.001), whereas group 2 did not differ significantly from group 3. The difference between group 1 and group 2 was statistically significant with regard to PASI but not regarding the proportion of patients with absent/very mild disease. Patients receiving initial therapy with the two-compound product achieved the fastest treatment response, and the maximum treatment effect for these patients was seen after 5 weeks. This effect was maintained with continued treatment with the two-compound product for up to 8 weeks. After 12 weeks of treatment, no significant differences were seen between the three groups with regard to reduction in PASI, whereas the proportion of patients with absent/very mild disease in group 2 was superior to that in group 3. Patients receiving therapy with the two-compound product experienced fewer lesional/perilesional adverse drug reactions than the calcipotriol-treated patients (P < 0.001): 10.9% in group 1, 11.5% in group 2 and 22.3% in group 3. CONCLUSIONS: Two different short-term treatment regimens employing a recently developed two-compound product (calcipotriol/betamethasone dipropionate) provided rapid and marked clinical efficacy and were shown to be safe therapies for psoriasis vulgaris.

Adolescent↗
PubMed2004

Biological therapies in the systemic management of psoriasis: International Consensus Conference.

Psoriasis is a chronic, immune-mediated disorder that usually requires long-term treatment for control. Approximately 25% of patients have moderate to severe disease and require phototherapy, systemic therapy or both. Despite the availability of numerous therapeutic options, the long-term management of psoriasis can be complicated by treatment-related limitations. With advances in molecular research and technology, several biological therapies are in various stages of development and approval for psoriasis. Biological therapies are designed to modulate key steps in the pathogenesis of psoriasis. Collectively, biologicals have been evaluated in thousands of patients with psoriasis and have demonstrated significant benefit with favourable safety and tolerability profiles. The limitations of current psoriasis therapies, the value of biological therapies for psoriasis, and guidance regarding the incorporation of biological therapies into clinical practice are discussed.

Age Factors↗
PubMed2004

Activator protein 1 DNA binding activity is decreased in lesional psoriatic skin compared with nonlesional psoriatic skin.

BACKGROUND: Psoriasis is a common benign skin disease characterized by hyperproliferation and abnormal differentiation of keratinocytes. The transcription factor activator protein 1 (AP-1) is known to play an important role in cell proliferation and differentiation. OBJECTIVES: To investigate AP-1 DNA binding activity in psoriatic skin. METHODS: Keratome biopsies were taken from patients with plaque-type psoriasis. Electrophoretic mobility shift assays were used to determine the AP-1 DNA binding activity, whereas Western and Northern blotting was used to determine Jun and Fos protein and mRNA expression. RESULTS: We found that AP-1 DNA binding activity was almost completely abolished in lesional psoriatic skin compared with nonlesional psoriatic skin. Furthermore, experiments revealed that the protein and mRNA expression of the AP-1 subunits c-Fos, Fra-1 and c-Jun was reduced in lesional psoriatic skin compared with nonlesional psoriatic skin, whereas the protein and mRNA expression of the subunit JunB was increased. Topical application of the vitamin D analogue calcipotriol under occlusion to involved psoriatic skin for 4 days resulted in an increase in AP-1 DNA binding activity, and an increase in the protein and mRNA expression of c-Fos, Fra-1 and c-Jun, together with a decrease in JunB protein and mRNA expression. CONCLUSIONS: Together, these results suggest that the activity of the transcription factor AP-1 is impaired in lesional psoriatic skin and that this impairment may be important for the disturbed epidermal growth observed in psoriasis.

Adult↗
PubMed2002

Efficacy and safety of a new combination of calcipotriol and betamethasone dipropionate (once or twice daily) compared to calcipotriol (twice daily) in the treatment of psoriasis vulgaris: a randomized, double-blind, vehicle-controlled clinical trial.

BACKGROUND: Calcipotriol and betamethasone dipropionate are both widely used, effective treatments for psoriasis. Vitamin D analogues and topical corticosteroids have different mechanisms of action in the treatment of psoriasis. A new vehicle has been developed in order to contain both calcipotriol (50 micro g g-1) and betamethasone dipropionate (0.5 mg g-1) in an ointment form. By using calcipotriol and a corticosteroid together, greater efficacy may be achieved than by using either compound alone. OBJECTIVES: The present study was conducted in order to compare the clinical efficacy and safety of the combined ointment formulation used once daily with the vehicle ointment used twice daily, calcipotriol ointment used twice daily and the combined formulation used twice daily in psoriasis vulgaris. METHODS: This was an international, multicentre, prospective, randomized, double-blind, vehicle-controlled, parallel group, 4-week study in patients with psoriasis vulgaris amenable to topical treatment. Patients were randomized to one of four treatment groups: combined formulation once daily, combined formulation twice daily, calcipotriol twice daily or vehicle twice daily. Efficacy and safety were assessed. RESULTS: There was no statistically significant difference in the mean percentage change in the Psoriasis Area and Severity Index (PASI) from baseline to end of treatment between the two combined formulation groups, but the difference in PASI reduction was significantly higher in the combined formulation groups (68.6% once daily, 73.8% twice daily) than in both the twice daily calcipotriol group (58.8%) and the vehicle group (26.6%). Safety data showed the frequency of adverse events to be less in the combined formulation groups than in both the calcipotriol group and the vehicle group. The proportion of patients with lesional/perilesional adverse reactions was less in the combined formulation groups and vehicle group than in the calcipotriol group (9.9% combined formulation once daily, 10.6% combined formulation twice daily, 19.8% calcipotriol, 12.5% vehicle). CONCLUSIONS: No statistically significant nor clinically relevant difference in efficacy was seen between the combined formulation used once daily and twice daily. When compared to vehicle ointment or calcipotriol ointment alone, the combined formulation was shown to be clearly more efficacious.

Adolescent↗
PubMed2002

Safety and efficacy of combined high-dose treatment with calcipotriol ointment and solution in patients with psoriasis.

BACKGROUND: In the vast majority of psoriatic patients, psoriatic lesions are localised on the body as well as on the scalp. Therefore, safety data on the combined use of calcipotriol in lotion and calcipotriol in ointment are needed. OBJECTIVE: This study investigated the effect of high-dose treatment with a combination of calcipotriol ointment and scalp solution on calcium metabolism, indices of bone turnover and PASI in patients with extensive psoriasis. METHODS: Following a 2-week wash-out period, 88 patients were randomised to 4 weeks of treatment with either calcipotriol ointment/scalp solution (80-100 g/week and 30-50 ml/week, respectively; n = 41) or with a dithranol/tar regimen (n = 47). Patients were seen at weeks 1, 2 and 4 during treatment and 1 week following cessation of treatment. RESULTS: No significant differences at the end of treatment were found between the 2 groups with respect to 24-hour urinary excretion of calcium (expressed as calcium/creatinine ratio), phosphate or pyridinoline, serum concentrations of calcium (albumin corrected), creatinine, phosphate, parathyroid hormone, 25-hydroxyvitamin D(3), 1,25-dihydroxyvitamin D(3), osteocalcin, alkaline phosphatase (total and bone-specific iso-enzymes) or 1-collagen telopeptide. At the end of treatment, the psoriasis area and severity index had decreased by 57.4% in the calcipotriol group and by 36.1% in the dithranol/tar group (p = 0.004). Investigators' and patients' assessments of overall efficacy also favoured treatment with calcipotriol (p < 0.001). CONCLUSION: The combined use of calcipotriol ointment/scalp solution did not affect the indices of calcium metabolism or bone turnover and was significantly more effective than dithranol/tar in reducing disease severity and extent in patients with extensive psoriasis.

Administration, Topical↗
PubMed2001

Modulation of keratinocyte gene expression and differentiation by PPAR-selective ligands and tetradecylthioacetic acid.

Peroxisome proliferator-activated receptors (PPARs) are pleiotropic regulators of growth and differentiation of many cell types. We have performed a comprehensive analysis of the expression of PPARs, transcriptional cofactors, and marker genes during differentiation of normal human keratinocytes using a combination of reverse transcriptase polymerase chain reaction, Northern and Western blotting, and immunohistochemistry. PPARdelta was the predominant PPAR subtype in human keratinocytes and highly expressed in basal cells and suprabasal cells. Induction of PPARalpha and PPARgamma expression was linked to differentiation, and accordingly, expression of PPARalpha and PPARgamma was in essence confined to suprabasal cells. Differentiation was not accompanied by significant changes in the expression of the coactivators CREB-binding protein, p300, steroid receptor coactivator 1, or the corepressors nuclear receptor corepressor and silence mediator for retinoid and thyroid hormone receptors. We critically evaluated the effects of selective PPAR ligands and a synthetic fatty acid analog, tetradecylthioacetic acid. Tetradecylthioacetic acid activated all human PPAR subtypes in the ranking order PPARdelta >> PPARalpha > PPARgamma. All selective PPAR ligands marginally induced transglutaminase-1 expression with the PPARdelta-selective ligand L165041 being the most potent. The PPARalpha- and PPARgamma-selective ligands Wy14643 and BRL49653 had negligible effect on involucrin expression, whereas a dose-dependent induction was observed with L165041. Simultaneous addition of L165041 and BRL49653 synergistically induced strong involucrin expression. Additionally, L165041 potently induced CD36 mRNA expression. Administration of tetradecylthioacetic acid resulted in a dramatic decrease in proliferation and a robust upregulation of the expression of involucrin and transglutaminase. Our results indicate that tetradecylthioacetic acid may affect keratinocyte gene expression and differentiation via PPAR-dependent and PPAR-independent pathways, and that the latter play an important role.

Adult↗
PubMed2001

Remission and relapse of chronic plaque psoriasis treated once a week with clobetasol propionate occluded with a hydrocolloid dressing versus twice daily treatment with clobetasol propionate alone.

BACKGROUND: Many studies have shown the clinical efficiency of occlusion therapy for psoriasis, particularly corticosteroids used under hydrocolloid dressings. However, there are no data from comparative clinical studies evaluating the remission and relapse characteristics of such occlusion therapy compared with orthodox topical steroid monotherapy. METHODS: In a randomised, open-label, parallel group study from three centres, the remission and relapse characteristics were investigated for the use of a hydrocolloid dressing (HCD) over clobetasol propionate 0.05% lotion once a week compared with the same steroid in ointment formulation used unoccluded twice a day in 61 patients with stable chronic plaque psoriasis. RESULTS: There was a pronounced treatment difference in favour of the HCD + clobetasol propionate lotion group with respect to time to clearance, but there was little evidence for a difference with respect to time to relapse. CONCLUSION: The combination of the HCD + clobetasol propionate lotion provides a fast and highly effective remission induction.

Administration, Topical↗
PubMed2000

1alpha,25-dihydroxyvitamin D3 induced differentiation of cultured human keratinocytes is accompanied by a PKC-independent regulation of AP-1 DNA binding activity.

1alpha,25(OH)2D3 and its analogs are potent mediators of keratinocyte differentiation in vitro. The precise mechanism of this action is still unknown. The nuclear transcription factor activator protein 1 seems to play an important role in keratinocyte differentiation. The purpose of this study was to investigate the effect of 1alpha,25(OH)2D3 on activator protein 1 DNA binding activity in cultured human keratinocytes. In a time-course study of human keratinocytes incubated with 1alpha,25(OH)2D3 (10-7-10-11 M) a significant dose-dependent increase in activator protein 1 DNA binding activity as determined by electrophoretic mobility shift assay was seen after 36 h. This increase was followed by a significant dose-dependent decrease in activator protein 1 DNA binding activity after 72 h. When differentiation was induced by raising the calcium concentration in the culture medium from 0.09 to 0.3 mM a similar increase in activator protein 1 DNA binding activity was observed after incubation for 48 h. Pharmacologic down-modulation of the protein kinase C activity with GF 109203X reversed the calcium-induced increase in activator protein 1 DNA binding activity and abolished keratinocyte differentiation as determined by a transglutaminase assay. In contrast, activator protein 1 DNA binding activity and keratinocyte differentiation were not affected when protein kinase C activity was down-modulated in the experiments with 1alpha,25(OH)2D3. The activator protein 1 complex in human keratinocytes consists of dimers of Fra-1, Fra-2, c-Jun, JunD, and c-Fos. Our results demonstrate that 1alpha, 25(OH)2D3- and calcium-induced keratinocyte differentiation are accompanied by changes in activator protein 1 DNA binding activity. Protein kinase C activation appears to be essential for the calcium-dependent induction of keratinocyte differentiation, whereas a protein-kinase-C-independent activation of activator protein 1 DNA binding and keratinocyte differentiation is responsible for the 1alpha,25(OH)2D3-induced effects.

Calcitriol↗