PUVA bath therapy strongly suppresses immunological and epidermal activation in psoriasis: a possible cellular basis for remittive therapy

Does molecular scarring in psoriasis exist? A review of the literature

Plaque psoriasis is a chronic inflammatory dermatosis characterized by a tendency to recur in the same locations after discontinuation of treatment. The implementation of therapy with drugs targeting cytokines like interleukin (IL) 17A (IL-17A) and IL-23 has revolutionized the treatment of psoriasis and enabled the achievement of skin without lesions. However, despite the clinical resolution of psoriatic eruptions, cells that maintain the local memory of the disease remain in the dermis and epidermis, constituting a kind of molecular scar. The cells responsible for maintaining memory in the skin of patients and influencing the rapid relapse of the disease after the triggering factor are primarily tissue resident memory T cells (TRM), but it seems that regulatory T lymphocytes (Treg), dendritic cells (DC), and Langerhans cells (LC) may also play an important role in this process. We reviewed the literature to explain the concept of molecular scarring in psoriasis, and to assess the effect of various therapies on immune memory.

Development of Topical Nanoemulgel Using Combined Therapy for Treating Psoriasis

This study focuses on the development of topical formulation of methoxsalen using Babchi oil as formulation component that can be applied at body surfaces providing sustained delivery and enhanced penetration of methoxsalen leading to significant epidermal localization and better anti-psoriatic activity. The combination of psoralens, that is, methoxsalen (synthetic) and Babchi oil (natural) has been developed into nanoemulgel formulations. A total of four nanoemulsion formulations was developed using Babchi oil as oil phase and Tween 80 as surfactant by high-pressure homogenization method. The prepared nanoemulsions were characterized for entrapment efficiency, mean droplet size, and zeta potential. Based on characterization results, the optimized nanoemulsion formulation(s) were incorporated into the carbopol gel base to make a nanoemulgel. The prepared nanoemulgel formulations were analyzed for pH, drug content determination, spreadability, viscosity, ex vivo skin permeation, and in vivo studies. The nanoemulsions showed droplet size between 51.3 and 146.7 nm, entrapment efficiency of 92.76%-98.10%, and zeta potential of -28.1 to -54.89 mev. The nanoemulsions showed varied in vitro drug release. In ex vivo skin permeation, nanoemulgel (NG2) showed increased penetration and localized accumulation of methoxsalen across the skin compared with plain gel. Ex vivo results were substantiated by in vivo results showing significant amelioration of hyperproliferative skin symptoms. The promising results suggested that nanoemulgel system is a suitable carrier for the topical delivery of methoxsalen-Babchi oil.

Imperatorin Alleviates Psoriasiform Dermatitis by Blocking Neutrophil Respiratory Burst, Adhesion, and Chemotaxis Through Selective Phosphodiesterase 4 Inhibition

Aim: Neutrophil infiltration and increased oxidative stress are involved in the pathogenesis and severity of psoriasis. Although the therapy of psoriasis remains elusive, targeting treatment to reduce oxidative stress is considered a potential option. Our study demonstrates the anti-inflammatory effects of a natural furocoumarin, imperatorin, on activated human neutrophils and psoriasiform dermatitis in mice. Results: Imperatorin inhibited superoxide anion generation, neutrophil adhesion, and migration in N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-stimulated human neutrophils. Further studies showed that imperatorin induced a decrease in cAMP-specific phosphodiesterase (PDE) activity, and increased intracellular cAMP levels and protein kinase A (PKA) activity in human neutrophils. The enzyme activities of PDE4 subtypes, but not PDE3 and PDE7, were inhibited by imperatorin. Furthermore, imperatorin inhibited the phosphorylation of protein kinase B (Akt), extracellular regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), as well as Ca²⁺ mobilization in fMLF-stimulated neutrophils. These suppressive effects of imperatorin on cell responses and signaling were reversed by PKA inhibitor, suggesting that cAMP/PKA is involved in the anti-inflammatory effects of imperatorin. In vivo studies of imiquimod- and interleukin-23-induced mouse psoriasiform dermatitis demonstrated that imperatorin alleviated skin desquamation, epidermal thickening, keratinocyte hyperproliferation, and neutrophil infiltration. Innovation and Conclusion: Our results demonstrate that imperatorin inhibits human neutrophil respiratory burst, adhesion, and migration through the elevation of cAMP/PKA to inhibit Akt, ERK, JNK, and Ca²⁺ mobilization. Imperatorin is a natural inhibitor of PDE4A/B/C and may serve as a lead for developing new therapeutics to treat neutrophilic psoriasis. Antioxid. Redox Signal. 35, 885-903.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Angelicin-A Furocoumarin Compound With Vast Biological Potential

Angelicin, a member of the furocoumarin group, is related to psoralen which is well known for its effectiveness in phototherapy. The furocoumarins as a group have been studied since the 1950s but only recently has angelicin begun to come into its own as the subject of several biological studies. Angelicin has demonstrated anti-cancer properties against multiple cell lines, exerting effects via both the intrinsic and extrinsic apoptotic pathways, and also demonstrated an ability to inhibit tubulin polymerization to a higher degree than psoralen. Besides that, angelicin too demonstrated anti-inflammatory activity in inflammatory-related respiratory and neurodegenerative ailments via the activation of NF-κB pathway. Angelicin also showed pro-osteogenesis and pro-chondrogenic effects on osteoblasts and pre-chondrocytes respectively. The elevated expression of pro-osteogenic and chondrogenic markers and activation of TGF-β/BMP, Wnt/β-catenin pathway confirms the positive effect of angelicin bone remodeling. Angelicin also increased the expression of estrogen receptor alpha (ERα) in osteogenesis. Other bioactivities, such as anti-viral and erythroid differentiating properties of angelicin, were also reported by several researchers with the latter even displaying an even greater aptitude as compared to the commonly prescribed drug, hydroxyurea, which is currently on the market. Apart from that, recently, a new application for angelicin against periodontitis had been studied, where reduction of bone loss was indirectly caused by its anti-microbial properties. All in all, angelicin appears to be a promising compound for further studies especially on its mechanism and application in therapies for a multitude of common and debilitating ailments such as sickle cell anaemia, osteoporosis, cancer, and neurodegeneration. Future research on the drug delivery of angelicin in cancer, inflammation and erythroid differentiation models would aid in improving the bioproperties of angelicin and efficacy of delivery to the targeted site. More in-depth studies of angelicin on bone remodeling, the pro-osteogenic effect of angelicin in various bone disease models and the anti-viral implications of angelicin in periodontitis should be researched. Finally, studies on the binding of angelicin toward regulatory genes, transcription factors, and receptors can be done through experimental research supplemented with molecular docking and molecular dynamics simulation.

Resolution of plaque-type psoriasis: what is left behind (and reinitiates the disease)

Psoriasis is a chronic inflammatory skin disease that involves numerous types of immune cells and cytokines resulting in an inflammatory feedback loop and hyperproliferation of the epidermis. A more detailed understanding of the underlying pathophysiology has revolutionized anti-psoriatic treatment and led to the development of various new drugs targeting key inflammatory cytokines such as IL-17A and IL-23. Successfully treated psoriatic lesions often resolve completely, leaving nothing visible to the naked eye. However, such lesions tend to recur within months at the exact same body sites. What is left behind at the cellular and molecular levels that potentially reinitiates psoriasis? Here, we elucidate the cellular and molecular “scar” and its imprints left after clinical resolution of psoriasis treated with anti-TNFα, anti-IL-17, or anti-IL-23 antibodies or phototherapy. Hidden cytokine stores and remaining tissue-resident memory T cells (TRMs) might hold the clue for disease recurrence.

From Early Immunomodulatory Triggers to Immunosuppressive Outcome: Therapeutic Implications of the Complex Interplay Between the Wavebands of Sunlight and the Skin

Phototherapy is an efficient treatment for many cutaneous diseases that involve the activation of inflammatory pathways or the overgrowth of cells with aberrant phenotype. In this review, we discuss recent advances in photoimmunology, focusing on the effects of UV-based therapies currently used in dermatology. We describe the molecular responses to the main forms of photo(chemo)therapy such as UVB, UVA-1, and PUVA that include the triggering of apoptotic or immunosuppressive pathways and help to clear diseased skin. The early molecular response to UV involves DNA photoproducts, the isomerization of urocanic acid, the secretion of biophospholipids such as platelet activating factor (PAF), the activation of aryl hydrocarbon receptor and inflammasome, and vitamin D synthesis. The simultaneous and complex interaction of these events regulates the activity of the immune system both locally and systemically, resulting in apoptosis of neoplastic and/or benign cells, reduction of cellular infiltrate, and regulation of cytokines and chemokines. Regulatory T-cells and Langerhans cells, among other skin-resident cellular populations, are deeply affected by UV exposure and are therefore important players in the mechanisms of immunomodulation and the therapeutic value of UV in all its forms. We weigh the contribution of these cells to the therapeutic application of UV and how they may participate in transferring the direct impact of UV on the skin into local and systemic immunomodulation. Moreover, we review the therapeutic mechanisms revealed by clinical and laboratory animal investigations in the most common cutaneous diseases treated with phototherapy such as psoriasis, atopic dermatitis, vitiligo, and cutaneous T-cell lymphoma. Better understanding of phototherapeutic mechanisms in these diseases will help advance treatment in general and make future therapeutic strategies more precise, targeted, personalized, safe, and efficient.

A Perspective on the Interplay of Ultraviolet-Radiation, Skin Microbiome and Skin Resident Memory TCRαβ+ Cells

The human skin is known to be inhabited by diverse microbes, including bacteria, fungi, viruses, archaea, and mites. This microbiome exerts a protective role against infections by promoting immune development and inhibiting pathogenic microbes to colonize skin. One of the factors having an intense effect on the skin and its resident microbes is ultraviolet-radiation (UV-R). UV-R can promote or inhibit the growth of microbes on the skin and modulate the immune system which can be either favorable or harmful. Among potential UV-R targets, skin resident memory T cells (T_RM) stand as well positioned immune cells at the forefront within the skin. Both CD4⁺ or CD8⁺ αβ T_RM cells residing permanently in peripheral tissues have been shown to play prominent roles in providing accelerated and long-lived specific immunity, tissue homeostasis, wound repair. Nevertheless, their response upon UV-R exposure or signals from microbiome are poorly understood compared to resident TCRγδ cells. Skin T_RM survive for long periods of time and are exposed to innumerable antigens during lifetime. The interplay of T_RM with skin residing microbes may be crucial in pathophysiology of various diseases including psoriasis, atopic dermatitis and polymorphic light eruption. In this article, we share our perspective about how UV-R may directly shape the persistence, phenotype, specificity, and function of skin T_RM; and moreover, whether UV-R alters barrier function, leading to microbial-specific skin T_RM, disrupting the healthy balance between skin microbiome and skin immune cells, and resulting in chronic inflammation and diseased skin.

Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?

Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis.

Treatment of chronic spontaneous urticaria: Immunomodulatory approaches

This paper summarizes and reviews the mechanisms of action and data concerning efficacy of recommended treatments as well as other treatments that have been tested, independently of the outcomes, in the management of chronic spontaneous urticaria. Due to the central role of mast cells, basophils and histamine in the pathophysiology of this disease, H₁-antihistamines remain the first-line treatment. However, current knowledge about this complex disease, also recognizes an important role for T lymphocytes, B lymphocytes, and autoantibodies. Implications of these others mediators thus provide further targets for treatment. Indeed, agents previously used to treat other autoimmune and inflammatory diseases, have demonstrated efficacy in chronic spontaneous urticaria and are therefore potential therapeutic alternatives for antihistamine unresponsive patients.

The Remittive Effects of Alefacept

The duration of response to treatment with alefacept has been assessed in patients with moderate to severe chronic plaque psoriasis who responded to alefacept therapy in phase 2 and phase 3 clinical studies. In a phase 2 trial, duration of response was based on time to retreatment with alefacept. In two phase 3 studies, the more objective measure of maintenance of a ≥50% reduction from baseline Psoriasis Area and Severity Index (PASI 50) was used. Two patient subsets were analyzed: (1) those who achieved a PASI 75 at any time during the trials and (2) those who achieved a Physician Global Assessment of “clear” or “almost clear” at any time during the trials. Regardless of the criterion used or the route of alefacept administration (intravenous or intramuscular), the median duration of response to alefacept therapy ranged from 7 to 10 months across the three studies. Alefacept is a remittive therapy for psoriasis.

Serotonin signalling is crucial in the induction of PUVA-induced systemic suppression of delayed-type hypersensitivity but not local apoptosis or inflammation of the skin

Psoralen and UVA (PUVA) has immunosuppressive and proapoptotic effects, which are thought to be responsible alone or in combination for its therapeutic efficacy. However, the molecular mechanism by which PUVA mediates its effects is not well understood. Activation of the serotonin (5-hydroxytryptamine, 5-HT) pathway has been suggested to be involved in the modulation of T-cell responses and found to mediate UVB-induced immune suppression. In particular, the activation of the 5-HT2A receptor has been proposed as one mechanism responsible for UV-induced immune suppression. We therefore hypothesized that 5-HT may play a role in PUVA-induced effects. The model of systemic suppression of delayed-type hypersensitivity (DTH) to Candida albicans was used to study immune function after exposure of C3H and KIT(W) (-Sh/W-Sh) mice to a minimal inflammatory dose of topical PUVA. The intra-peritoneal injection of the 5-HT2 receptor antagonist ketanserin or cyproheptadine or an anti-5-HT antibody immediately before PUVA exposure entirely abrogated suppression of DTH but had no significant effect on inflammation, as measured by swelling and cellular infiltration of the skin, and apoptosis as determined by the number of sunburn cells in C3H mice. Importantly, the systemic injection of 5-HT recapitulated PUVA immune suppression of DTH but did not induce inflammation or apoptosis in the skin. KIT(W) (-Sh/W-Sh) mice (exhibiting myelopoietic abnormalities, including lack of 5-HT-containing mast cells) were resistant to PUVA-induced suppression of DTH but not local skin swelling. Thus, this points towards a crucial role of 5-HT signalling in PUVA-induced immune suppression but not inflammation or apoptosis in situ in the skin.

The effect of phototherapy on systemic inflammatory process in patients with plaque psoriasis

Psoriasis is a common, chronic immune-mediated inflammatory disease. The inflammatory process in psoriasis has systemic effects and may influence the development of psoriatic comorbidities. The systemic action of phototherapy in patients with psoriasis has been so far poorly elucidated. We aimed to investigate the expression of genes encoding selected psoriasis-related cytokines in peripheral blood mononuclear cells (PBMCs) isolated from patients with psoriasis before and after treatment with phototherapy. 17 patients with mild to moderate plaque psoriasis were treated with narrow band-UVB (NB-UVB), 8 patients with moderate to severe plaque psoriasis with bath-psoralen-ultraviolet A therapy (PUVA). PBMCs were isolated by Ficoll gradient density centrifugation. Expression of genes encoding TNF-α, IL-17A, IL-6, IL-1 β, INF-γ, and IL-10 in PBMCs of patients with psoriasis before and after phototherapy was analyzed with quantitative RT-PCR. Treatment with NB-UVB therapy led to a significant decrease in IL-17A, TNF-α, and IL-6 mRNA levels in PBMCs (p=0.003; p=0.042; p=0.019, respectively). Following treatment with bath-PUVA therapy, we observed a significant decrease in TNF-α and IL-6 mRNA levels in PBMCs (p=0.031, p=0.035, respectively). Treatment with phototherapy in patients with psoriasis may affect systemic inflammation by downregulation of the expression of genes encoding proinflammatory cytokines in PBMCs, implicated in the development of psoriasis and psoriatic comorbidities.

STAT3/5-Dependent IL9 Overexpression Contributes to Neoplastic Cell Survival in Mycosis Fungoides

PURPOSE

Sustained inflammation is a key feature of mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL). Resident IL9-producing T cells have been found in skin infections and certain inflammatory skin diseases, but their role in MF is currently unknown.

EXPERIMENTAL DESIGN

We analyzed lesional skin from patients with MF for the expression of IL9 and its regulators. To determine which cells were producing IL9, high-throughput sequencing was used to identify malignant clones and Vb-specific antibodies were employed to visualize malignant cells in histologic preparations. To explore the mechanism of IL9 secretion, we knocked down STAT3/5 and IRF4 by siRNA transfection in CTCL cell lines receiving psoralen+UVA (PUVA) ± anti-IL9 antibody. To further examine the role of IL9 in tumor development, the EL-4 T-cell lymphoma model was used in C57BL/6 mice.

RESULTS

Malignant and reactive T cells produce IL9 in lesional skin. Expression of the Th9 transcription factor IRF4 in malignant cells was heterogeneous, whereas reactive T cells expressed it uniformly. PUVA or UVB phototherapy diminished the frequencies of IL9- and IL9r-positive cells, as well as STAT3/5a and IRF4 expression in lesional skin. IL9 production was regulated by STAT3/5 and silencing of STAT5 or blockade of IL9 with neutralizing antibodies potentiated cell death after PUVA treatment in vitro IL9-depleted mice exhibited a reduction of tumor growth, higher frequencies of regulatory T cells, and activated CD4 and CD8 T lymphocytes.

CONCLUSIONS

Our results suggest that IL9 and its regulators are promising new targets for therapy development in mycosis fungoides. Clin Cancer Res; 22(13); 3328-39. ©2016 AACR.

The translational revolution and use of biologics in patients with inflammatory skin diseases

Psoriasis and atopic dermatitis (AD) are common inflammatory skin diseases characterized by immune-mediated inflammation and abnormal keratinocyte differentiation. Although T-cell infiltration characterizes both diseases, T-cell polarization differs. Psoriasis is currently the best model for translational medicine because many targeted therapeutics have been developed and testing of targeted therapeutics has cemented psoriasis as IL-23/TH17 polarized. In patients with AD, although therapeutic development is approximately a decade behind that in patients with psoriasis, there is now active development and testing of targeted therapeutics against various immune axes (TH2, TH22, and IL-23/TH17). These clinical trials and subsequent molecular analyses using human samples will be able to clarify the relative roles of polar cytokines in patients with AD.

A comparative study of histopathological findings in skin biopsies from patients with psoriasis before and after treatment with acitretin, methotrexate and phototherapy

INTRODUCTION

Psoriasis is a chronic and inflammatory skin disease. Few studies in the literature evaluate the responses to the treatment histopathologically.

OBJECTIVES

In this study, we evaluated and compared skin biopsies taken from patients with psoriasis before and after phototherapy and therapy with acitretin and methotrexate.

MATERIAL AND METHODS

We included 64 patients with a diagnosis of psoriasis vulgaris in our study. We performed phototherapy on 33 patients (51.6%), while 19 patients (29.7%) were treated with methotrexate and 12 patients (18.8%) were treated with acitretin.

RESULTS

All of the patients had chronic plaque psoriasis, and they had skin lesions on more than 10% of their total body surface area and a score of PASI of 7.2-21.8 (average: 12.2). The histopathological parameter scores were similar in the initial evaluations of the pre-treatment treatment groups. When the biopsy specimens of all cases were evaluated together, a significant decrease was observed in terms of parakeratosis, Munro's microabscesses, regular acanthosis, pustules of Kogoj, lymphocyte infiltration in the papillary dermis, loss of the granular layer, spongiosis, suprapapillary thinning, vascularity in the papillary dermis and neutrophile infiltration in the papillary dermis.

CONCLUSION

We found in our study that conventional treatment modalities provided histopathologically significant recovery in psoriasis, but they did not have an effect on some histopathological findings. To our knowledge, it is one of the few studies to assess these parameters in psoriasis under the continuous effect of acitretin, methotrexate and phototherapy for three months. There is a need for studies with larger series to examine the histopathological effects of these treatment modalities in terms of immunopathology.

Tight junctions and differentiation--a chicken or the egg question?

Skin barrier function is indispensable to prevent the uncontrolled loss of water and solutes and to protect the body from external assaults. To fulfil this function, keratinocytes undergo a complex pathway of differentiation that terminates in the formation of the stratum corneum. Additionally, tight junctions (TJs), which are cell-cell junctions localized in the stratum granulosum, are involved in the barrier function of the skin. Important biological and clinical roles of TJs are strongly suggested by altered TJ protein levels and distribution in skin diseases like psoriasis, ichthyosis and atopic dermatitis. Because these skin diseases show alterations in differentiation and TJs, it was suggested that changes in TJs might simply be a consequence of altered differentiation. However, in this viewpoint, we like to argue that the situation is not as simple and depends on the specific microenvironment. We discuss three hypotheses regarding the interplay between TJs/TJ proteins and differentiation: (1) TJs/TJ proteins are influenced by differentiation, (2) differentiation is influenced by TJs/TJ proteins, and (3) TJs/TJ proteins and differentiation are independent of each other. In addition, the concept is introduced that both processes are going on at the same time, which means that while one specific TJ protein/barrier component might be influenced by differentiation, the other may influence differentiation.

Insulin-like growth factor-1 in psoriatic plaques treated with PUVA and methotrexate

BACKGROUND

The pathogenesis of psoriasis is thought to depend on the activation of immune cells and their secreted cytokines, chemokines and growth factors like IGF-1 which may contribute to the epidermal hyperplasia of psoriasis. Treatment of psoriasis with PUVA and methotrexate are associated with clinical improvement and decrease in epidermal hyperplasia.

OBJECTIVE

To examine the effects of PUVA and methotrexate therapy on IGF-1 expression in psoriatic plaques and whether this change correlates with clinical response.

METHODS

For 24 psoriatic patients, the PASI score and levels of lesional IGF-1 and its mRNA were determined by RT-PCR before and after treatment with either methotrexate or PUVA. Skin biopsies from 12 healthy volunteers served as control for IGF-1 levels in normal skin.

RESULTS

Lesional skin of psoriatic patients showed a statistically significant elevation in IGF-1 and its mRNA levels in comparison to control (P = 0.0001). Both methotrexate and PUVA treatment were associated with a significant decrease in both PASI scores and lesional IGF-1 after 10 month treatment.

CONCLUSION

Both methotrexate and PUVA therapy for psoriasis are associated with a decrease in PASI score and IGF-1. The IGF-1 down-regulation may possibly be a consequence of the decrease in cytokines and inflammatory cellular infiltrate that occur following treatment with either modalities or due to their effect on local fibroblast activity and proliferation.

Psoriasis: from pathogenesis to novel therapeutic approaches

Psoriasis is one of the commonest chronic inflammatory disorders. Its cause is unknown, but a wealth of studies indicate that the disease results from a complex and dynamic interplay between genetic and environmental factors that trigger an excessive inflammatory response in the skin. Dendritic cells and effector T-cells are central in the development of the psoriastic lesion, and cytokines produced by these cells stimulate keratinocytes to proliferate and increase the migration of inflammatory cells into the skin, promoting epidermal hyperplasia and inflammation. Understanding the immunology of the psoriatic plaque has led to new therapeutic options and novel candidates for immunomodulation, and has changed the ways psoriatic patients are managed.

Up-regulation of Id1 in peripheral blood of psoriatic patients

Although the precise causes of psoriasis are unclear, it is widely accepted that psoriasis is a disorder in which factors in the immune system, enzymes, and other biochemical substances that regulate skin cell division are impaired, leading to rapid proliferation of keratinocytes and incomplete keratinization. Expression of the helix-loop-helix transcription factor Id1 (inhibitor of differentiation/DNA binding), functioning as an inhibitor of differentiation, is known to increase in psoriatic skin. However, the molecular involvement of this particular biomarker in the psoriatic immune system remains to be elucidated. We measured Id1 mRNA expression in peripheral blood mononuclear cells (PBMCs) of psoriatic patients and healthy controls using semi-quantitative reverse transcriptase-PCR. The normalized level of Id1 transcripts in psoriatic patients was about 2-fold higher than that in controls (P < 0.05). When we examined the proliferation rate of PBMCs, the stimulation index obtained from the phytohemagglutinin stimulation assay was not significantly different in psoriatic patients. In patients with psoriasis, there was no correlation between the stimulation index and the psoriasis area severity index. We suggest that Id1 has a role in causing psoriatic immune cell symptoms.

Currentaspects of psoriasis phototherapy

The review covers current aspects of ultraviolet therapy for patients suffering from psoriasis. It describes mechanisms of action as well as early and remote side effects of the current phototherapy methods. The review also presents data from literature about the risk of their cancerogenicity. It also discusses approaches to the optimization of phototherapy in view of risks and benefits for the patient.

8-methoxypsoralen plus ultraviolet A therapy acts via inhibition of the IL-23/Th17 axis and induction of Foxp3+ regulatory T cells involving CTLA4 signaling in a psoriasis-like skin disorder

To elucidate the molecular action of 8-methoxypsoralen plus UVA (PUVA), a standard dermatological therapy, we used K5.hTGF-beta1 transgenic mice exhibiting a skin phenotype and cytokine abnormalities with strong similarities to human psoriasis. We observed that impaired function of CD4+CD25+ regulatory T cells (Tregs) and increased cytokine levels of the IL-23/Th17 pathway were responsible for the psoriatic phenotype in this mouse model. Treatment of K5.hTGF-beta1 transgenic mice with PUVA suppressed the IL-23/Th17 pathway, Th1 milieu, as well as transcription factors STAT3 and orphan nuclear receptor RORgammat. PUVA induced the Th2 pathway and IL-10-producing CD4+CD25+Foxp3+Tregs with disease-suppressive activity that was abolished by anti-CTLA4 mAb treatment. These findings were paralleled by macroscopic and microscopic clearance of the diseased murine skin. Anti-IL-17 mAb treatment also diminished the psoriatic phenotype of the mice. This indicated that both induced Tregs involving CTLA4 signaling and inhibition of the IL-23/Th17 axis are central for the therapeutic action of PUVA.

Photodynamic therapy in immune (non-oncological) disorders: focus on benzoporphyrin derivatives

This review examines the efficacy of photodynamic therapy in the treatment of immunological disorders. Photodynamic therapy (PDT) is a 2-step procedure. Firstly, a photosensitiser is introduced into the body, where it accumulates selectively in cells with elevated metabolism, such as cancer cells or activated cells of the immune system. Second, light is applied at a wavelength that excites the photosensitiser, producing a variety of short-lived oxygen-derived species. The effect is dependent on the doses of both photosensitiser and activating light. The mechanisms of action of PDT are multifactorial. Induction of high levels of oxidative stress results in necrotic cell death, while lower intensity oxidative stress initiates apoptosis. Sublethal doses may result in the modification of cell surface receptor expression levels and cytokine release and consequently influence cell behaviour. Immunomodulatory PDT (IPDT) utilises mainly apoptotic and sublethal doses. The studies reported here utilise verteporfin, a benzoporphyrin-derived chlorin-like photosensitiser. Veteporfin is a second generation photosensitiser, displaying rapid clearance and consequently a reduced period of skin photosensitivity compared with the first generation photosensitiser, porfimer sodium. In vivo studies showed that IPDT was effective in alleviating immunopathology in murine models of arthritis, contact hypersensitivity, experimental allergic encephalomyelitis and retention of allogeneic skin grafts. Based on these findings, early stage clinical trials with IPDT were initiated recently for the treatment of psoriasis, psoriatic arthritis and rheumatoid arthritis. While verteporfin has been the photosensitiser which pioneered IPDT, a new benzoporphyrin derivative photosensitiser, QLT0074, is under development. This has demonstrated an enhanced avidity for target cells as well as improved clearance characteristics.

Transgenic expression of S100A2 in hairless mouse skin enhances Cxcl13 mRNA in response to solar-simulated radiation

S100A2 is a homodimeric protein that undergoes oxidative cross-linking and translocation from the nucleus to the cytosol in the context of oxidative stress. Suggestive of a role for S100A2 in the cutaneous response to ultraviolet light, we found altered S100A2 immunostaining in photodamaged human skin, and crosslinking of S100A2 after ultraviolet A (UVA) irradiation of normal human keratinocytes (NHK). Skin from mice, rats, and rabbits did not contain S100A2 protein, whereas skin samples from pigs, frogs and humans were strongly positive. Survival after UVA irradiation was significantly greater in NHK compared to mouse keratinocytes, suggesting a protective role for S100A2. To test this hypothesis in vivo, we expressed S100A2 in SKH2/J hairless mice under the control of a bovine keratin 5 promoter, and compared responses of TG and WT mice from 1 to 7 days after a single dose (0.5-1 MED) of solar-simulated radiation (SSR) from UVA-340 bulbs. WT and TG mice manifested a similarly robust response to SSR, characterized by epidermal hyperplasia, marked induction of p21(WAF), and a twofold increase in p53. Thymine dimers (TD) were markedly increased in the epidermis and the dermis, but while over 95% of the epidermal TD were removed by 5-6 days, elevated dermal TD persisted nearly unchanged for 7 days. Global transcriptional profiling of WT and TG mice revealed strong induction of multiple transcripts, including keratins K6 and K16, defensin beta 3, S100A8, S100A9, Sprr2i and Sprr2f. However, the only S100A2-dependent difference we observed was an induction of Cxcl13 transcripts in TG, but not WT mice (4.4-fold vs. 0.7-fold, n = 3, P = 0.022). This finding was confirmed in an independent set of mice analyzed by quantitative RT-PCR (8.8-fold vs. 1.2-fold, n = 4, P = 0.001). The finding of persistent dermal DNA damage after suberythemal doses of SSR merits further study.

Effects of narrowband UV-B on pharmacodynamic markers of response to therapy: an immunohistochemical study over sequential samples

BACKGROUND

To evaluate the effects of narrow-band UV-B (NBUVB) on the immunohistochemical markers of cellular and cytokine activation as well as of abnormal epidermal differentiation and proliferation--pharmacodynamic markers of response to therapy (PMT)--in psoriatic lesions.

METHODS

Clinical assessments and immunohistological staining of formalin-fixed paraffin sections of biopsies from psoriatic skin were done at baseline and at the end of the treatment period.

RESULTS

Ten patients with chronic plaque-type psoriasis were included. After treatment with NBUVB, the total number of CD3+, CD4+ and CD8+ T cells was reduced by an average of 86.6%, 86% and 85% in the epidermis and 70.3%, 70% and 62% in the dermis, respectively. Only the decrease in the number of epidermal CD4+ cells was statistically related with long-lasting remissions. The mean reduction in the expression of keratinocyte proliferation markers after NBUVB was 62%, 68% and 81% for Ki-67, cyclin A and cyclin B, respectively. Expression of suprabasal keratin 16 and filaggrin was almost normalized in most cases. All patients in whom expression of keratin16 remained after finishing UV-B therapy had an early relapse.

CONCLUSIONS

NBUVB is associated with changes in PMT close to those seen after remittive therapies. The normalization of immunohistochemical parameters of differentiation and the reduction/depletion in epidermal CD4+ cells was the most important markers of long-lasting remissions.

Central role of mitochondria and p53 in PUVA-induced apoptosis in human keratinocytes cell line NCTC-2544

Despite strong evidence concerning the high efficiency of PUVA therapy (psoralen plus UVA light), its mechanism of action has not yet been fully elucidated. In this study, we have evaluated in a cell line of human keratinocytes (NCTC-2544) the effects of two linear psoralen derivatives, 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP), that are widely used in PUVA therapy and two angular derivatives, Angelicin (ANG) and 4,6,4'-trymetyl angelicin (TMA). All derivatives photoinduce cellular death, TMA being the most active compound. The cell cycle analysis showed that the four derivatives induce, 24 h after irradiation, a cell cycle arrest in G1 phase later followed by massive apoptosis. The G1 arrest is correlated to an increase in the expression of p21(Waf1/Cip1), a protein associated with the cell cycle block and apoptosis. Furthermore, treatment of NCTC-2544 resulted in p53 activation by 5-MOP, 8-MOP, and ANG but not TMA and its phosphorylation at serine-15. The levels of p21(Waf1/Cip1) paralleled p53 protein staining pattern suggesting that p53 activation correlated with p21(Waf1/Cip1) induction. Simultaneous to p53 activation, psoralens induced mitochondrial depolarization, cytochrome c release, mitochondrial production of reactive oxygen species, as well as caspase-3 and -9 activation. Thus these results strongly indicate the necessity of p53 activation and the induction of the apoptotic machinery downstream of mitochondria.

T helper type 1 cytokines and keratinocyte growth factor play a critical role in pseudoepitheliomatous hyperplasia initiation during cutaneous leishmaniasis

Pseudoepitheliomatous hyperplasia (PEH) is an exuberant proliferation of the epidermis. The underlying mechanism(s) that lead to PEH have not been completely elucidated. Here, we characterize PEH during the healing stages of cutaneous leishmanial ulcers in mice. During experimental cutaneous leishmaniasis (CL) C57BL/6 mice produce PEH, and BALB/c do not. A series of immunohistochemical and immunological studies were performed to identify the secretory products of PEH regulation. We observed that the distribution of TNF-alpha and IFN-gamma under PEH had a stripe-like diffuse pattern and localized in the upper part of the papillary dermis directly under the proliferating epidermis. Macrophages were identified as the major source of TNF-alpha (56.3%). The importance of IFN-gamma and TNF-alpha in PEH development was proven by the initiation of PEH after three intralesional injections of TNF-alpha and IFN-gamma every three days in infected BALB/c mice. In C57BL/6 mice, keratinocyte growth factor (KGF) expressing cells were found immediately under the basal membrane of the hyperplastic epidermis in comparison with sporadic KGF positive cells deep in the dermis of BALB/c mice. Quantitative RT-PCR analysis demonstrated increased KGF and KGF receptor expression in uninfected C57BL/6 mice as compared to BALB/c mice. These data indicate that Th1 cytokines and KGF play a critical role in PEH initiation during CL.

Differential ErbB1 signaling in squamous cell versus basal cell carcinoma of the skin

In this study, we examined ErbB1 signaling in human basal and squamous cell carcinomas (BCC and SCC) of the skin in vivo. We used enzyme-linked immunosorbent assay, laser capture microdissection-coupled real-time reverse transcriptase-polymerase chain reaction, and immunohistochemistry to assess expression and activation levels of ErbB1 protein, ligands, and potential downstream effectors, in BCC and SCC tumors, stroma, and adjacent epidermis. Although total ErbB1 protein and mRNA were similar in cancerous and normal skin, we found that ErbB1 activation (phospho-Tyr(1068)) was greater in bulk SCC versus BCC or normal skin. In addition, three ErbB1 ligand transcripts (amphiregulin, heparin-binding epidermal growth factor-like growth factor, and transforming growth factor-alpha) were up-regulated in tumor cells of SCC but not BCC. Expression of these ligands was also increased in asymptomatic epidermis adjacent to both SCC and BCC, relative to normal skin. Interestingly, betacellulin transcript levels were inversely regulated compared with the other ligands. Consistently, downstream ErbB1 effectors (Erk1/2 and Akt) were activated in tumor cells of SCC but not of BCC and in adjacent epidermis of both BCC and SCC. These results demonstrate that ErbB1 signaling is hyperactive in tumor cells of SCC but not of BCC and in nearby asymptomatic epidermis of both tumor types. Our results suggest that targeting ErbB1 signaling might be of benefit in the treatment of SCC.

Mouse models of psoriasis

Psoriasis is a T-cell-mediated chronic inflammatory skin disease believed to be of autoimmune nature that can be triggered or worsened by streptococcal throat infections. In addition to conventional chronic inflammatory changes, psoriasis is characterized by complex and striking alterations in epidermal growth and differentiation. Psoriasis is generally not observed in animals other than man, and this lack of a suitable animal model has greatly hindered research into the pathogenesis of psoriasis. Multiple transgenic, knockout, and reconstituted models of psoriasis have been developed over the past two decades. Despite their limitations, these models have demonstrated that keratinocyte hyperplasia, vascular hyperplasia, and cell-mediated immunity in the skin are closely interrelated. Xenograft models, in which involved and uninvolved psoriatic skin are transplanted onto immunodeficient mice, are the only models that come close to incorporating the complete genetic, immunologic, and phenotypic changes of the disease. They have shown conclusively that psoriasis is a T-cell-mediated disease, and have been used to elucidate novel pathogenic pathways. In this review, we describe various animal models, detail the immunologic and intracellular pathways that mediate these phenotypes and assess the utility of these models to better understand this disease.

Documento de consenso sobre la modalidad terapéutica del baño-PUVA

Bath PUVA is a variant of phototherapy as efficacious as oral PUVA therapy that avoids many of the adverse effects associated to this treatment. Nevertheless, the special features and the specialized equipment required for its employment have limited its application in the dermatologic clinics of our country. Following the trend initiated after the publication of the consensus document on oral PUVA therapy and narrow band (NB) UVB therapy, the Spanish Photobiology Group from the Spanish Academy of Dermatology and Venereology has developed a therapeutic guideline for bath PUVA therapy based on the literature review and the experience of its members. The document aims to be a practical reference guide for those dermatological centres that include phototherapy among their services. It reviews the concept and indications of this type of treatment and proposes recommendations concerning therapeutic procedures, drug associations of interest and prophylaxis and management of adverse effects.

Platelet-activating factor is crucial in psoralen and ultraviolet A-induced immune suppression, inflammation, and apoptosis

Psoralen plus UVA (PUVA) is used as a very effective treatment modality for various diseases, including psoriasis and cutaneous T-cell lymphoma. PUVA-induced immune suppression and/or apoptosis are thought to be responsible for the therapeutic action. However, the molecular mechanisms by which PUVA acts are not well understood. We have previously identified platelet-activating factor (PAF), a potent phospholipid mediator, as a crucial substance triggering ultraviolet B radiation-induced immune suppression. In this study, we used PAF receptor knockout mice, a selective PAF receptor antagonist, a COX-2 inhibitor (presumably blocking downstream effects of PAF), and PAF-like molecules to test the role of PAF receptor binding in PUVA treatment. We found that activation of the PAF pathway is crucial for PUVA-induced immune suppression (as measured by suppression of delayed type hypersensitivity to Candida albicans) and that it plays a role in skin inflammation and apoptosis. Downstream of PAF, interleukin-10 was involved in PUVA-induced immune suppression but not inflammation. Better understanding of PUVA's mechanisms may offer the opportunity to dissect the therapeutic from the detrimental (ie, carcinogenic) effects and/or to develop new drugs (eg, using the PAF pathway) that act like PUVA but have fewer side effects.

The effect of various methods of psoriasis treatment on somatotrophin axis hormones in serum

OBJECTIVE

To investigate the effect of pharmacotherapy and phototherapy on the concentration of hormones of the somatotrophin axis [growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3)] in the serum of patients with psoriasis in exacerbation and remission.

METHODS

GH and IGFBP-3 in serum were determined by immunoradiometric assay (IRMA), and IGF-I concentrations - by radioimmunological assay (RIA). The dermatological state was assessed by the psoriasis area and severity index (PASI).

RESULTS

There was no significant difference in the GH concentrations in patients both in exacerbation and remission, irrespective of therapy applied. However, in the group treated by phototherapy a significant increase in IGFBP-3 secretion was observed, whereas in the group treated with cyclosporin A - a significant increase in IGF-I secretion was observed in remission.

CONCLUSION

Different methods of treatment have different effects on the secretion of somatotrophin axis hormones, but generally the hormone concentrations do not return to the values observed in healthy people. The therapeutic actions of the drugs concerned are not fully known and require further investigations.

Programmed cell death of keratinocytes in infliximab-treated plaque-type psoriasis

BACKGROUND

Tumour necrosis factor (TNF)-alpha blockade using infliximab, a chimeric anti-TNF-alpha antibody, is an effective treatment for plaque-type psoriasis, inducing remission in about 80% of patients.

OBJECTIVES

To examine infliximab-induced programmed cell death (PCD) of keratinocytes in psoriatic plaques on serial skin biopsy samples.

METHODS

Five patients with moderate to severe plaque-type psoriasis received infliximab infusions intravenously (5 mg kg(-1)) at weeks 0, 2 and 6. Biopsies of nonlesional and lesional skin (days 0, 5, 14 and 21) were obtained. Conventional microscopy was used to examine the morphology of the psoriatic keratinocytes. In situ detection of apoptosis was performed by electron microscopy and by immunohistochemical staining with anti-p53 and anti-caspase-3 antibodies. Results Infusion of infliximab induced a clinical response in all five patients with psoriasis, with a mean Psoriasis Area and Severity Index improvement of 24.8% already at day 5. This was accompanied by significant histopathological changes in the skin biopsy samples after infliximab treatment. Light and electron microscopic evaluation revealed apoptosis-like morphological changes in lesional keratinocytes, i.e. nuclear condensation, chromatin fragmentation and cytoplasmic vesiculation, visible already after the first infusion. These damaged keratinocytes stained positively for p53, but not for active caspase-3.

CONCLUSIONS

The effects of infliximab in psoriasis extend beyond merely anti-inflammatory actions, and may include caspase-independent PCD of lesional keratinocytes. The PCD of keratinocytes may be an important mechanism that could explain at least in part the rapid and sustained therapeutic effect of infliximab in psoriasis.

Increase in TNF-alpha and inducible nitric oxide synthase-expressing dendritic cells in psoriasis and reduction with efalizumab (anti-CD11a)

We find that CD11c(+) cells with many markers of dendritic cells (DCs) are a major cell type in the skin lesions of psoriasis. These CD11c(+) cells, which are evident in both epidermis and dermis, are the sites for the expression of two mediators of inflammation, inducible nitric oxide synthase (iNOS) and TNF-alpha in diseased skin. These cells express HLA-DR, CD40, and CD86, lack the Langerin and CD14 markers of Langerhans cells and monocytes, respectively, and to a significant extent express the DC maturation markers DC-LAMP and CD83. Treatment of psoriasis with efalizumab (anti-CD11a, Raptiva) strongly reduces infiltration by these DCs in patients responding to this agent. Disease activity after therapy was more related to DC infiltrates and iNOS mRNA levels than T cell infiltrates, and CD11c(+) cells responded more quickly to therapy than epidermal keratinocytes. Our results suggest that a type of DC, which resembles murine "Tip-DCs" that can accumulate during infection, has proinflammatory effects in psoriasis through nitric oxide and TNF-alpha production, and can be an important target for suppressive therapies.

Therapeutic options in the treatment of psoriasis and atopic dermatitis

A variety of therapeutic options are available to treat psoriasis and atopic dermatitis (AD). Local agents typically are used to treat localized and milder forms of disease, whereas phototherapy and systemic agents are used for more generalized and severe disease. Various combinations and sequences of topical or systemic therapies, or both, have been utilized in the treatment of psoriasis and, less frequently, of AD. Conventional systemic therapies for psoriasis, such as corticosteroids, oral calcineurin inhibitors, antimetabolites, and retinoids, are limited by their propensity to cause serious side effects. More recently, a number of immunobiologic agents, such as monoclonal antibodies, recombinant cytokines, and fusion proteins, have been approved by the Food and Drug Administration or are undergoing development as systemic antipsoriatic treatments. In many of these categories, a number of exciting new therapies are in development that may augment the existing armamentarium available to clinicians for the treatment of inflammatory skin diseases.

A reappraisal of the concept of suppressive versus remittive psoriasis treatments

Among the ways to characterize the many treatments for psoriasis is to distinguish suppressive from remittive therapies. Remittive therapies are thought to be treatments that result in a prolonged period of disease remission even after stopping the drug, while suppressive treatments are thought to work only during the treatment period. However, apparent differences in remittive and suppressive properties may be due to the remitting and relapsing nature of psoriasis and the order in which treatments are used in patients. Few clinical trials have compared the suppressive versus remittive properties of different treatments. Given the adverse events and expense associated with many psoriasis therapies, a major implication is that psoriasis patients who have cleared on therapy should probably be tested at intervals to see if they can be tapered off their medication without loss of control of their disease.

The remittive effects of alefacept

The duration of response to treatment with alefacept has been assessed in patients with moderate to severe chronic plaque psoriasis who responded to alefacept therapy in phase 2 and phase 3 clinical studies. In a phase 2 trial, duration of response was based on time to retreatment with alefacept. In two phase 3 studies, the more objective measure of maintenance of a > or =50% reduction from baseline Psoriasis Area and Severity Index (PASI 50) was used. Two patient subsets were analyzed: (1) those who achieved a PASI 75 at any time during the trials and (2) those who achieved a Physician Global Assessment of "clear" or "almost clear" at any time during the trials. Regardless of the criterion used or the route of alefacept administration (intravenous or intramuscular), the median duration of response to alefacept therapy ranged from 7 to 10 months across the three studies. Alefacept is a remittive therapy for psoriasis.

Bath‐water PUVA Therapy with 8‐Methoxypsoralen in Mycosis Fungoides

PUVA therapy is widely used for early stage mycosis fungoides. While the efficacy of PUVA with oral 8-methoxypsoralen (8-MOP) is well documented, the use of its topical variation, bath-water PUVA therapy with 8-MOP has not been studied. The purpose of this study was to assess the effect of 8-MOP bath-water PUVA therapy in adult patients with early stage mycosis fungoides. We retrospectively evaluated the outcomes of bath-water delivery of 8-MOP (1 mg l(-1)) in 16 patients with early stage mycosis fungoides. In all patients complete response was achieved after a mean duration of 63 days requiring 29 treatments and a mean cumulative UVA dose of 33 J cm(-2). The time to relapse after complete clinical clearance was 45.6 (+/-9.2) weeks. In comparison, oral PUVA therapy with 8-MOP resulted in complete response after 64.5 days (25.8 treatments) with a mean relapse-free period of 30 (+/-3.5) weeks. We conclude that bath-water PUVA therapy with 8-MOP is a valuable photo-therapeutic alternative, which should be considered for patients in whom systemic psoralen cannot be used.

Comparison of the efficacy and safety of the 308 nm excimer laser for the treatment of localized psoriasis in adults and in children: a pilot study

The 308-nm excimer laser has been shown to be safe and efficacious in the treatment of localized mild-to-moderate plaque-type psoriasis in adults. However, the laser's safety and efficacy has not yet been demonstrated in children. Four of seven children with a mean age of 11.0 years and 12 of 18 adults with a mean age of 48.8 years completed the full protocol. The most common reason for incompletion was noncompliance unrelated to side effects. Both the children (p=0.0200) and the adult groups (p=0.0009) yielded a significant decrease in psoriatic severity scores of their respective target lesions. The children group had a greater reduction (p=0.008) from a mean baseline target (PSS) of 5.75+/-1.71 to final of 0.50+/-0.58 (91.3% reduction) as compared to the adult treatment group from a mean baseline psoriatic severity score of 5.00+/-1.15 to final of 1.92+/-1.11 (61.6% reduction). However, there was no statistical difference between the mean total treatments required to achieve this result (p=0.112). Side effects were common, albeit minor and well tolerated. In conclusion, the 308 nm excimer laser appears to be a safe and effective treatment for localized psoriasis in children as well as in adults.

Novel pharmacological approaches in the treatment of psoriasis

Progress in the understanding of psoriasis as a T-cell mediated inflammatory disease has led to the development of new immunomodulatory therapies. Currently the main focus is on the so-called biologics (or biological agents), including fusion proteins, monoclonal antibodies, cytokines and selective receptors. They mainly target single steps in the complex cascade of humoral and cellular inflammatory immuno-mechanisms that finally lead to the accelerated growth of epidermal and vascular cells in the psoriatic lesions. The most promising and advanced biological agents are discussed along with their influence on the critical pathophysiological steps in psoriasis, including depletion of T cells, blockade of initial T-cell activation and T-cell receptor (TCR) stimulation, blockade of costimulatory signals and T-cell proliferative signals as well as restoration of the T helper type 1 (Th1)/Th2 balance by diminishing type 1 cytokines and administration of type 2 cytokines. In addition to the biological agents, further development of 'classical' dermatological therapies, such as retinoids, or the discovery of new indications for non-dermatological agents contribute to the novel pharmacological approaches in the treatment of psoriasis.

Psoriasis: emerging therapeutic strategies

Psoriasis is a chronic inflammatory skin disorder that is characterized by thickened, scaly plaques, and is estimated to affect approximately 1-3% of the Caucasian population. Traditional treatments, although effective in patients with limited disease, have numerous shortcomings, including inconvenience and toxicity. These drawbacks mean that many patients experience cycles of disease clearance, in which normal quality of life alternates with active disease and poor quality of life. However, as this review discusses, recent advances have highlighted the key role of the immune system in the pathogenesis of psoriasis, and have provided new defined targets for therapeutic intervention, offering hope for safe and effective psoriasis treatment.