Cyclosporin A, FK506 and dithranol after tyrosine-specific protein phosphorylation in HaCaT keratinocytes

Dithranol: An Insight into its Novel Delivery Cargos for Psoriasis Management

OBJECTIVE

Dithranol (DTH) is a well-known moiety that has long been used promisingly to impede and treat skin disorders, particularly psoriasis. Nowadays, a rekindled interest in the use of DTH for this disorder has been observed. Side effects associated with conventional topical formulations of this moiety have aroused the interest of the scientific community in investigating novel cargos of DTH for psoriasis management.

RESULTS

Previous research has evidenced the anti-inflammatory and anti-proliferating potential of DTH. Numerous studies have indicated that DTH inhibits polymorphonuclear (PMN) leucocyte, modulates epidermal cell receptors and promotes anti-psoriatic action. However, some deterrent factors like poor solubility, stability, toxicity, staining and skin irritation hamper its use as a potential therapeutic agent. With the adoption of novel drug delivery technologies, the above mentioned inherent limitations of DTH have been compensated to reestablish this drug moiety.

CONCLUSION

This article reviews novel drug delivery aspects, safety concerns, clinical evidence, current status, and future opportunities of DTH in the management of psoriasis. Further, it will update researchers on this promising drug moiety, which is free from systemic adverse responses in comparison to other therapeutic molecules like steroids, for psoriasis treatment.

S3 - Guidelines on the treatment of psoriasis vulgaris (English version). Update

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1.5% to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, surveys have shown that patients still do not received optimal treatments. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologi sche Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) have initiated a project to develop evidence-based guidelines for the management of psoriasis. They were first published in 2006 and updated in 2011. The Guidelines focus on induction therapy in cases of mild, moderate and severe plaque-type psoriasis in adults including systemic therapy, UV therapy and topical therapies. The therapeutic recommendations were developed based on the results of a systematic literature search and were finalized during a consensus meeting using structured consensus methods (nominal group process).

Evidence-based (S3) guidelines for the treatment of psoriasis vulgaris

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1 to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, patient surveys have revealed lack of satisfaction with the efficacy of available treatments and a high rate of non-compliance. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologische Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) initiated a project to develop evidence-based guidelines for the management of psoriasis. These resulting Guidelines focus on induction therapy in cases of mild, moderate, and severe plaquetype psoriasis in adults. The Guidelines include evidence-based evaluation of the efficacy of all currently available therapeutic options in Germany. In addition, they offer detailed information on how best to administer the various treatments and give information on contraindications, adverse drug reactions, and drug interactions as well as estimates of practicability and cost. The Guidelines were developed following the recommendations of the Arbeitsgemeinschaft wissenschaftlicher medizinischer Fachgesellschaften (AWMF). The therapeutic recommendations were developed by an expert group and finalized during interdisciplinary consensus conferences.

Klassische Therapien der topischen Psoriasisbehandlung

In most cases mild to moderate forms of psoriasis can be treated with topical therapy. In addition, topical agents are also routinely combined with UV or systemic therapy to treat severe forms of psoriasis. A variety of standard products are available. The oldest topical treatment is anthralin. Since 1952 the development of topical corticosteroids has revolutionized not only dermatological treatment in general but the treatment of psoriasis in particular. Through the continuous development of these compounds, a better risk-benefit profile has been achieved. Corticosteroids are the most frequently employed topical agent for psoriasis treatment worldwide.

Cornified envelope formation by anthralin, simple analogues, and related anthracenones

The ability of the antipsoriatic anthralin to induce HaCaT keratinocyte differentiation was investigated and correlated with its potency to inhibit proliferation of keratinocytes. To determine the structural requirements for this effect, anthralin and seventeen simple analogues or related anthracenones were examined for their ability to induce the formation of cornified envelope as a marker of terminal differentiation. Covalently cross-linked protein was measured as a key feature of this process. Induction of keratinocyte differentiation was significant at a concentration of 0.5 microM anthralin after 48 h exposure. The presence of the 1,8-dihydroxy groups is a critical determinant of cross-linking activity, since removing or exchanging these groups prevented the induction of keratinocyte differentiation. Furthermore, at least one hydrogen atom at the 10-position of anthralin is required. Moreover, anthralin, anthralin dimer, and anthralin triacetate exhibited antiproliferative and antirespiratory activity at concentrations required to induce keratinocyte differentiation, suggesting a causality between these effects. In addition, cornified envelope formation was observed for a number of related anthracenones at concentrations as low as 1-5 microM. In general, compounds containing benzoyl substituents, independent of the position in the anthralin nucleus, were more potent than those having benzyl substituents. Only marginal differences in cross-linking potency were observed within a number of phenylpropionyl substituted analogues, suggesting that the ability to induce keratinocyte differentiation is independent of the nature of substituents at the side chain.

Drug-induced suppression of phosphorylase kinase activity correlates with resolution of psoriasis as assessed by clinical, histological and immunohistochemical parameters

BACKGROUND

Phosphorylase kinase (PhK), also known as adenosine triphosphate (ATP)-phosphorylase b phosphotransferase, integrates multiple calcium/calmodulin-dependent signalling pathways, including those involved in cell migration and cell proliferation, while coupling these pathways to glycogenolysis and ATP-dependent phosphorylation, thus ensuring continuing energy supply for these activities.

OBJECTIVES

Our laboratory recently reported correlation of elevated PhK activity with psoriatic activity. This study further evaluates the significance of drug-induced suppression of PhK activity on psoriatic activity.

PATIENTS AND METHODS

PhK activity was assayed in four groups, each with 10 patients: (i) active untreated psoriasis; (ii) resolving psoriasis treated by calcipotriol (Dovonex(R), Bristol Myers Squibb, Princeton, NJ, U.S.A. ), a vitamin D3 analogue and an indirect inhibitor of PhK; (iii) curcumin (diferuloylmethane), a selective PhK inhibitor; and (iv) 10 normal non-psoriatic subjects.

RESULTS

PhK activity in units mg-1 protein was highest in active untreated psoriasis (1204 +/- 804.3; mean +/- SD), lower in the calcipotriol-treated group (550.7 +/- 192. 9), lower in curcumin-treated group (207.2 +/- 97.6), and lowest in normal skin (105.4 +/- 44.6). One-way analysis of variance performed on log-transformed PhK activity measure showed significant differences among the four groups, F3,36 = 48.79, P < 0.0001. Decreased PhK activity in curcumin-and calcipotriol-treated psoriasis was associated with corresponding decreases in keratinocyte transferrin receptor (TRR) expression, severity of parakeratosis and density of epidermal CD8+ T cells.

CONCLUSIONS

Our results demonstrate that drug-induced suppression of PhK activity is associated with resolution of psoriatic activity as assessed by clinical, histological and immunohistochemical criteria, and support the hypothesis that effective antipsoriatic activity may be achieved through modulation of PhK activity.

Inhibition of keratinocyte apoptosis by IL-15: a new parameter in the pathogenesis of psoriasis?

Keratinocytes (KC) are important source of and targets for several cytokines. Although KC express IL-15 mRNA, the functional effects of IL-15 on these epithelial cells remain to be dissected. Investigating primary human foreskin KC and HaCaT cells, we show here by semiquantitative RT-PCR and flow cytometric analysis that both translate IL-15 and IL-15R mRNA and express IL-15 and IL-15Ralpha protein on the cell surface, suggesting that human KC can employ IL-15 for juxtacrine signaling. While IL-15 exerted no significant effect on KC proliferation and IL-6 or IL-8 secretion, IL-15 inhibited both anti-Fas and methylcellulose-induced KC apoptosis in vitro. This is in line with the recognized potent anti-apoptotic effects of IL-15. IL-2, whose receptor shares two components with the IL-15R, failed to inhibit KC apoptosis. Together with the role of IL-15 in sustaining chronic immune reactions, this invited the question of whether a reduction of KC apoptosis by IL-15 may be involved in the pathogenesis of psoriasis, a chronic hyperproliferative inflammatory skin disease characterized by abnormally low KC apoptosis in the epidermis. Remarkably, compared with nonlesional psoriatic skin and skin of healthy volunteers, lesional psoriatic epidermis showed high IL-15 protein expression in the epidermis and enhanced binding activity for IL-15. Therefore, antagonizing the inhibitory effects of IL-15 on KC apoptosis deserves exploration as a novel therapeutic strategy in psoriasis management.

HaCaT cell line as a model system for vitamin D3 metabolism in human skin

Synthesis and catabolism of calcitriol (1,25(OH)2D3) were studied using HaCaT cell line as a cell culture model. Our results indicate that stimulation of HaCaT cells with epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha) within 16 h just prior to reaching confluence amplified the production of calcitriol when calcidiol (3H-25OHD3) was used as a substrate. EGF- and TGF-alpha-induced (0.1-10 nM) 1-hydroxylation of 3H-25OHD3 was concentration-dependent but showed different kinetics. Synthesis of calcitriol induced by EGF was inversely related to the degree of cellular confluence. Stimulation by EGF was an actinomycin D- and cycloheximide-sensitive process. Independently of the growth factor used, the production of 3H-24R,25(OH)2D3 and the catabolism of 3H-1,25(OH)2D3 to 3H-1,24,25(OH)3D3 were unexpectedly low (< or = 5% and < or = 2%/), as compared to the amount of calcitriol generated. Exogenous addition of unlabeled 1,25(OH)2D3, 1,24R(OH)2D3, calcipotriol, or 24R,25(OH)2D3 at concentrations as low as 10(-11) M, potently inhibited the 3H-1,25(OH)2D3 production. These results suggest that EGF-treated HaCaT keratinocytes could serve for further studies of the vitamin D3 pathway and its relationship to proliferation and differentiation, but differences in calcitriol synthesis and catabolism from those in cultured primary keratinocytes or other cell lines must be considered.