T cells involved in psoriasis vulgaris belong to the Th1 subset

The roles of cells and cytokines in the pathogenesis of psoriasis

Psoriasis is considered an immune chronic disease in which T cells are accepted as important. Nowadays, it is believed that psoriasis is most likely a T helper (Th)1/Th17 induced inflammatory disease. However, some other cells, such as endothelial cells, dendritic cells, monocytic cells, neutrophils, keratinocytes, and several cytokines, appear to have, at different stages of the disease, an important role in its pathogenesis. For instance, the response to psoriasis therapy is dependent not only on the inactivation of Th1 and Th17 immune responses but also on the inactivation of dendritic cell products. Moreover, interleukin (IL)-23 deregulation appears to be an independent factor in the pathogenesis of psoriasis. Indeed, currently, the IL-23/Th17 axis is believed to be crucial in psoriasis pathogenesis, and its inhibition appears to be important for therapeutic achievement. This review presents the roles and interactions of cells and cytokines that are related to psoriasis pathogenesis.

New insights of T cells in the pathogenesis of psoriasis

Psoriasis is one of the most common immune-mediated chronic, inflammatory skin diseases characterized by hyperproliferative keratinocytes and infiltration of T cells, dendritic cells, macrophages and neutrophils. Although the pathogenesis of psoriasis is not fully understood, there is ample evidence suggesting that the dysregulation of immune cells in the skin, particularly T cells, plays a critical role in psoriasis development. In this review, we mainly focus on the pathogenic T cells and discuss how these T cells are activated and involved in the disease pathogenesis. Newly identified 'professional' IL-17-producing dermal γδ T cells and their potential role in psoriasis will also be included. Finally, we will briefly summarize the recent progress on the T cell and its related cytokine-targeted therapy for psoriasis treatment.

Selective hyper-responsiveness of the interferon system in major depressive disorders and depression induced by interferon therapy

BACKGROUND

Though an important percentage of patients with chronic hepatitis C virus (HCV) undergoing interferon (IFN) therapy develop depressive symptoms, the role of the IFN system in the pathogenesis of depressive disorders is not well understood.

METHODS

50 patients with HCV infection were treated with standard combination therapy (pegylated IFN-α2a/ribavirin). IFN-induced gene expression was analyzed to identify genes which are differentially regulated in patients with or without IFN-induced depression. For validation, PBMC from 22 psychiatric patients with a severe depressive episode (SDE) and 11 controls were cultivated in vitro with pegylated IFN-α2a and gene expression was analyzed.

RESULTS

IFN-induced depression in HCV patients was associated with selective upregulation of 15 genes, including 6 genes that were previously described to be relevant for major depressive disorders or neuronal development. In addition, increased endogenous IFN-production and selective hyper-responsiveness of these genes to IFN stimulation were observed in SDE patients.

CONCLUSIONS

Our data suggest that selective hyper-responsiveness to exogenous (IFN therapy) or endogenous (depressive disorders) type I IFNs may lead to the development of depressive symptoms. These data could lead to the discovery of novel therapeutic approaches to treat IFN-induced and major depressive disorders.

Development of transgenic cloned pig models of skin inflammation by DNA transposon-directed ectopic expression of human β1 and α2 integrin

Integrins constitute a superfamily of transmembrane signaling receptors that play pivotal roles in cutaneous homeostasis by modulating cell growth and differentiation as well as inflammatory responses in the skin. Subrabasal expression of integrins α2 and/or β1 entails hyperproliferation and aberrant differentiation of keratinocytes and leads to dermal and epidermal influx of activated T-cells. The anatomical and physiological similarities between porcine and human skin make the pig a suitable model for human skin diseases. In efforts to generate a porcine model of cutaneous inflammation, we employed the Sleeping Beauty DNA transposon system for production of transgenic cloned Göttingen minipigs expressing human β1 or α2 integrin under the control of a promoter specific for subrabasal keratinocytes. Using pools of transgenic donor fibroblasts, cloning by somatic cell nuclear transfer was utilized to produce reconstructed embryos that were subsequently transferred to surrogate sows. The resulting pigs were all transgenic and harbored from one to six transgene integrants. Molecular analyses on skin biopsies and cultured keratinocytes showed ectopic expression of the human integrins and localization within the keratinocyte plasma membrane. Markers of perturbed skin homeostasis, including activation of the MAPK pathway, increased expression of the pro-inflammatory cytokine IL-1α, and enhanced expression of the transcription factor c-Fos, were identified in keratinocytes from β1 and α2 integrin-transgenic minipigs, suggesting the induction of a chronic inflammatory phenotype in the skin. Notably, cellular dysregulation obtained by overexpression of either β1 or α2 integrin occurred through different cellular signaling pathways. Our findings mark the creation of the first cloned pig models with molecular markers of skin inflammation. Despite the absence of an overt psoriatic phenotype, these animals may possess increased susceptibility to severe skin damage-induced inflammation and should be of great potential in studies aiming at the development and refinement of topical therapies for cutaneous inflammation including psoriasis.

Effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis

BACKGROUND

Systemic and focal infections caused by microorganisms have been known to induce or exacerbate psoriasis. Although the role of yeast species of the genus Malassezia in the pathogenesis of psoriasis is not fully understood, it is thought that these lipophilic yeasts may represent a triggering factor in the exacerbation of psoriatic lesions.

OBJECTIVES

This study investigated the effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis (GP) in order to define their role in the pathogenesis of psoriasis.

METHODS

Fifty patients with GP and 29 clinically healthy individuals were included in the study. All samples consisted of scales and scrapings taken from the scalps, trunks, and upper limbs of both psoriasis patients and healthy subjects. Psoriasis patients and healthy subjects were grouped according to their positivity or negativity for Malassezia yeasts as ascertained by direct microscopy and/or culture. An enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of Th1 and Th2 cytokines in these groups.

RESULTS

No significant differences in positivity for Malassezia yeasts were found between psoriatic skin and healthy skin in samples taken from different body sites. Serum interleukin-13 (IL-13) levels were significantly lower in the psoriasis group compared with the control group (P = 0.04). Levels of other cytokines did not differ significantly between the psoriasis and control groups. Mean levels of Th2 cytokines (IL-4, IL-10, IL-13), but not of Th1 cytokines (IL-2 and IFN-γ), were significantly lower in psoriasis patients positive for Malassezia yeasts compared with those negative for Malassezia yeasts and control subjects (P = 0.04, P < 0.001 and P = 0.01, respectively).

CONCLUSIONS

The isolation of Malassezia yeasts from GP lesions does not necessarily mean that these species are pathogenic, but their downregulating effects on anti-inflammatory Th2 cytokines may contribute to the occurrence of GP.

Extended DNFB-induced contact hypersensitivity models display characteristics of chronic inflammatory dermatoses

Despite recent developments, there is a high medical need for new treatment options for chronic inflammatory dermatoses like allergic contact dermatitis (ACD) and psoriasis. Particularly, more predictive skin inflammation models are required to facilitate the process of drug discovery. Murine contact hypersensitivity (CHS) models adequately reflect ACD and are also used to characterize therapeutic approaches for psoriasis. Using the hapten 2,4-dinitrofluorobenzene (DNFB), we established new subacute and subchronic DNFB-induced CHS models in C57BL/6 mice, which more closely reflect the characteristics of chronic T-cell-dependent inflammatory dermatoses as pronounced keratinocyte proliferation, strong hypervascularization, immune cell infiltration and overexpression of T cell and inflammatory cytokines. For the subacute DNFB model, we demonstrated anti-inflammatory activity of the glucocorticoid, prednisolone, as well as of neutralization of TNFα, IL-12/IL-23 or IL-18. In the subchronic DNFB-induced CHS model, deficiency for MyD88 and IL-12/IL-35 p35 chain but not IL-12/IL-23 p40 chain led to decreased skin inflammation. Furthermore, as exemplified by the dose-dependently effective therapeutic prednisolone treatment, the subchronic model allows the continuous therapy of a pre-established stable contact dermatitis. Altogether, prolonged DNFB-induced mouse CHS models closely reflect ACD sensitive to glucocorticoids as standard therapy, reveal a more chronic skin inflammation and are responsive to cytokine antagonization.

Deficiency of serum concentration of 25-hydroxyvitamin D in psoriatic patients: a case-control study

BACKGROUND

Some autoimmune conditions have been associated with reduced vitamin D levels, including systemic lupus erythematosus, rheumatoid arthritis, diabetes mellitus, and multiple sclerosis.

OBJECTIVE

The main objective of this study was to analyze the 25-hydroxyvitamin D (OHD) status of patients with psoriasis in comparison with control subjects without this disease.

METHODS

This case-control study included 86 patients (43 with psoriasis and 43 age- and sex-matched control subjects) from the outpatient clinic of our hospital dermatology department in Granada, Spain. All patients and control subjects were studied during one 4-week period to avoid seasonal variations in vitamin D levels.

RESULTS

Serum 25-OHD levels were significantly lower in psoriatic patients than in control subjects even after adjusting for confounding factors in a multivariate analysis (odds ratio 2.89, 95% confidence interval 1.02-7.64, P < .03 for vitamin D insufficiency). Low 25-OHD levels were negatively associated with C-reactive protein (inflammatory activation marker) and body mass index in multiple linear regression analysis. Psoriatic patients with body mass index greater than or equal to 27 kg/m(2) had a higher risk of 25-OHD insufficiency (sensitivity of 82.3% and specificity of 51.7%).

LIMITATIONS

Further studies with larger numbers of patients are required to analyze the pathogenic mechanisms underlying the relationship between 25-OHD deficiency and psoriasis.

CONCLUSIONS

The 25-OHD values are significantly lower in psoriatic patients than in control subjects. Low 25-OHD levels are negatively associated with C-reactive protein, an inflammatory activation marker, and with obesity. Psoriatic patients with a body mass index of 27 or more are likely to have vitamin D insufficiency.

Aldo-keto reductase 1C3 is expressed in differentiated human epidermis, affects keratinocyte differentiation, and is upregulated in atopic dermatitis

Aldo-keto reductase 1C3 (AKR1C3) has been shown to mediate the metabolism of sex hormones and prostaglandin D(2) (PGD(2)), a lipid mediator that promotes skin inflammation in atopic dermatitis (AD). As both have a role in skin function and pathology, we first sought to investigate the expression pattern of AKR1C3 in normal human epidermis. Immunofluorescence revealed a strong expression of AKR1C3 in the differentiated suprabasal layers compared with the basal layer. Western blot analysis and quantitative PCR confirmed that AKR1C3 expression was also upregulated in differentiation-induced primary human keratinocytes (PHKs). To investigate the functional role of AKR1C3 during PHK differentiation, its expression and activity (measured as PGD(2) reduction to 9α,11β-PGF(2) by ELISA) were impaired by small interfering RNA or 2'-hydroxyflavanone, respectively. Cytokeratin 10 (K10) and loricrin expression were then examined by western blot analysis, thus revealing altered expression of these differentiation markers. Finally, following an observation that the AD-associated mediator, PGD(2), upregulated AKR1C3 expression in PHKs, we used immunofluorescence to examine AKR1C3 expression in AD and psoriasis lesions. AKR1C3 was found to be upregulated in AD but not in psoriasis lesions compared with non-lesional skin. Our work demonstrates a function for AKR1C3 in differentiation-associated gene regulation and also suggests a role in supporting inflammation in AD.

Psoriasis and metabolic syndrome

Psoriasis is a chronic inflammatory and immune-mediated disease associated with several comorbidities, such as obesity, hypertension, diabetes mellitus, dyslipidemia and cardiovascular disorder. These comorbidities are components of metabolic syndrome. The pathogenesis of metabolic syndrome is supposed to be related to increased levels of adipocytokines, such as tumor necrosis factor-α (TNF-α) and adiponectin. Recent study has revealed a high prevalence of metabolic syndrome in psoriatics compared with other skin diseases. Biologic agents, including anti-TNF-α antibodies, are recommended as the first-line treatment for psoriatics with metabolic syndrome. This article reviews the association of psoriasis and metabolic syndrome in terms of adipocytokines and evaluates the role of biologic agents in the treatment of psoriasis.

Targeting IL-23: insights into the pathogenesis and the treatment of psoriasis

Therapeutic experience strongly supports the use of TNF antagonists as important modalities in the treatment of psoriatic arthritis and plaque psoriasis. Studies with anti-IL-12/23 therapeutic agents, which act in different steps of the psoriatic inflammatory cascade, have also shown demonstrable efficacy. Here, we discuss this approach and its potential within the armamentarium for the treatment of psoriasis. Evidences that the selective blocking of IL-23 may be effective and safe therapy are also addressed.

Regulation of caspase 14 expression in keratinocytes by inflammatory cytokines--a possible link between reduced skin barrier function and inflammation?

Caspase 14 is a unique member of the cysteinyl aspartate-specific proteinase family. Its expression is confined primarily to cornified epithelium such as the skin. Caspase 14 has been associated with the processing of filaggrin monomers and the development of natural moisturising factors of the skin, and thus, it could be speculated that caspase 14 dysregulation is implicated in the development of an impaired skin barrier function. We have investigated the regulation of caspase 14 transcription in cultured primary keratinocytes following stimulation with a number of factors present in inflamed skin, including T(H)1- and T(H)2-associated cytokines in addition to LPS and peptidoglycan. In particular, we found that T(H)2-associated cytokines reduced the caspase 14 mRNA level significantly. Furthermore, we found that the expression of caspase 14 was reduced in skin biopsies from patients with atopic dermatitis (AD), psoriasis and contact dermatitis, further supporting a role for this kinase in inflammatory skin conditions. Hence, the regulation of caspase 14 levels provides a possible link between impaired skin barrier function and inflammatory reactions in skin diseases such as AD and may offer an explanation to the skin barrier dysfunction in inflamed skin lesions.

The role of etanercept on the expression of markers of T helper 17 cells and their precursors in skin lesions of patients with psoriasis vulgaris

Very recently, it has been demonstrated that CD161, retinoic acid-related orphan receptor gamma-t (RORgamma-t) and CC-chemokin receptor 6 (CCR6) can be considered good surface markers to detect T helper 17 cells and their precursors, T cell populations that are considered to play an important role in the pathogenesis of psoriasis. In the present study, we evaluate the clinical involvement by calculating the PASI score and the number of CD4+, CD161+, RORgammat+ and CCR6+ cells before and after a 12-week course with etanercept or acitretin in patients with moderate-to-severe, plaque-type psoriasis vulgaris. Ten patients were given etanercept 50 mg twice weekly and 10 patients acitretin 0.4 mg/kg per day, both for 12 weeks. At the baseline and at the end of the treatment PASI was calculated, and skin biopsies were taken to evaluate the expression of CD4, CD161, RORgammat and CCR6 by immunohistochemistry. As controls, 10 patients with atopic dermatitis (AD) were included in the study. After 12 weeks, PASI was significantly lower than at the baseline for both groups. However, etanercept-treated patients showed lower PASI than acitretin-treated ones. While CD4+ cell numbers were similar in both diseases, all the other markers, that are considered more specific for Th17 cells and their precursors, were more expressed in psoriasis than in AD. Furthermore, only etanercept, but not acitretin, was able to significantly reduce CD161+, RORgammat+ and CCR6+ cells in skin lesions of patients with psoriasis. Our study provides further evidence of the role of Th17 pathway in the pathogenesis of psoriasis. Furthermore, our findings suggest that etanercept is able to downregulate the expression of the recently recognized markers of Th17 cells and their precursors CD161, RORgammat and CCR6, while acitretin is not. This activity on the Th17 lineage may contribute to the efficacy of etanercept in the treatment of psoriasis.

Development of a bioengineered skin-humanized mouse model for psoriasis: dissecting epidermal-lymphocyte interacting pathways

Over the past few years, whole skin xenotransplantation models that mimic different aspects of psoriasis have become available. However, these models are strongly constrained by the lack of skin donor availability and homogeneity. We present in this study a bioengineering-based skin-humanized mouse model for psoriasis, either in an autologous version using samples derived from psoriatic patients or, more importantly, in an allogeneic context, starting from skin biopsies and blood samples from unrelated healthy donors. After engraftment, the regenerated human skin presents the typical architecture of normal human skin but, in both cases, immunological reconstitution through intradermal injection in the regenerated skin using in vitro-differentiated T1 subpopulations as well as recombinant IL-17 and IL-22 Th17 cytokines, together with removal of the stratum corneum barrier by a mild abrasive treatment, leads to the rapid conversion of the skin into a bona fide psoriatic phenotype. Major hallmarks of psoriasis were confirmed by the evaluation of specific epidermal differentiation and proliferation markers as well as the mesenchymal milieu, including angiogenesis and infiltrate. Our bioengineered skin-based system represents a robust platform to reliably assess the molecular and cellular mechanisms underlying the complex interdependence between epidermal cells and the immune system. The system may also prove suitable to assess preclinical studies that test the efficacy of novel therapeutic treatments and to predict individual patient response to therapy.

Replication of association between interleukin-23 receptor (IL-23R) and its ligand (IL-12B) polymorphisms and psoriasis in the Chinese Han population

Psoriasis is an inflammatory skin disease with a multifactorial genetic basis. A recent genome-wide association study identified several psoriasis-predisposing loci, including IL-12B, which encodes the common p40 subunit of interleukin (IL)-12 and IL-23 and the IL-23 receptor gene (IL-23R). To investigate the relationships of these predisposing polymorphisms with psoriasis in the Chinese Han population, we genotyped three representative variants (rs6887695, rs11465817, and rs1343152) in 217 unrelated patients and 288 control subjects using direct sequencing, We further replicated the positive polymorphism, rs6887695, in a larger combined sample that included 578 patients and 1422 controls. We found the single nucleotide polymorphism, rs6887695 (odds ratio = 1.33, 95% confidence interval 1.03-1.73, p = 0.028) of IL-2B to be significantly associated with psoriasis, and a novel halotype A-A of rs11465817-rs1343152 also showed a positive association. Our study confirms the effects of IL-12B and IL-23R variants on psoriasis in East Asian populations, and provides a reference point for further investigation of the role of the IL-12/IL-23 pathway in chronic epithelial inflammation in Asian and other ethnic populations.

Immune mechanisms of psoriasis. New strategies of biotherapy

Psoriasis is a chronic skin disease - according to numerous studies, about 2% of the population suffer from it. Psoriasis degrades the life quality, and such concomitant pathologies as metabolic disorders, cardiovascular diseases and depression shorten the life expectancy of psoriasis patients. Substantial progress has been achieved today in understanding the mechanisms of the disease, searching for new treatment techniques and standardizing the disease severity According to the recent studies, psoriasis belongs to immune-dependent diseases with genetic predisposition to its development. Dendritic cells and T lymphocytes play an important part in psoriasis development. Their interaction launches a number of mechanisms ultimately leading to the inflammatory process development and formation of psoriatic skin affections. Such cytokines as IL-12, IL-23, IFN-y and TNF-a secreted by immunocompetent cells serve as mediators during such processes. An advanced therapeutic approach to the treatment of psoriasis means creating pathogenetically important cytokine specific monoclonal antibodies and placing them into the body Today there are drugs successfully blocking the development of psoriatic skin affections by means of specific binding of IL-12, IL-23 and TNF-a cytokines. Drugs called ustekinumab and ABT-874 confirmed their therapeutic activity with regard to psoriasis at Phases 2 and 3 of clinical trials. In the course of further trials, ustekinumab also demonstrated a safety profile comparable to that of placebo.

Xanthohumol inhibits IL-12 production and reduces chronic allergic contact dermatitis

Xanthohumol (XN) and its related compounds were evaluated for their effects on modulating the production of interleukin (IL)-12, the most important factor driving T helper 1 immune responses. XN showed the strongest inhibitory effect on IL-12 production in macrophages stimulated by lipopolysaccharide (LPS) or LPS/interferon-gamma. Xanthohumol 4'-O-beta-D-glucopyranoside (XNG) inhibited IL-12 production less effectively than XN. Isoxanthohumol and 8-prenylnaringenin showed comparatively lower inhibitory effects on IL-12 production than XNG. (2S)-5-methoxy-8-prenylnaringenin 7-O-beta-D-glucopyranoside did not exert any effect on IL-12 production. We then tested how these compounds affected NF-kappaB binding activity to the kappaB site in the nucleus. The compounds inhibited kappaB binding in macrophages with the same potency order as IL-12 inhibition. Furthermore, we investigated whether XN, which showed the most effective reduction of IL-12 production, attenuated skin inflammation. Chronic allergic contact dermatitis, an experimental model for psoriasis, was used to determine the anti-inflammatory effects of XN in vivo. XN treatment reduced the degree of ear thickening induced by oxazolone. Taken together, XN might be effective as an anti-inflammatory agent to reduce skin inflammation by inhibiting IL-12 production.

Polymorphisms in the FOXP3 gene in Han Chinese psoriasis patients

BACKGROUND

Psoriasis is a common dermatological disorder, in which autoimmunity plays an important role. CD4(+)CD25(+) regulatory T cells (T-regs) have been suggested to be involved in the pathogenesis of some autoimmune diseases. T-regs express the fork head/winged helix transcription factor, FOXP3, which appears to be of key importance in the development and function of T-regs. Studies have found that single-nucleotide polymorphisms (SNPs) in the FOXP3 gene contribute to susceptibility to some autoimmune disorders. However, information about FOXP3 gene in psoriasis is limited.

OBJECTIVE

This study evaluated the association between FOXP3 gene SNPs and susceptibility to psoriasis in a Han Chinese population.

METHODS

In a hospital-based case-control study, 524 patients with psoriasis and 549 psoriasis-free controls were recruited according to age and gender. We investigated four SNPs in the FOXP3 gene (-6054, deletion/ATT; -3279, A/C; -924, A/G; IVS9+459, A/G) in psoriatic patients, and assessed allele and genotype frequencies in psoriatic patients (237 females, 287 males) and normal controls (272 females, 277 males). The polymorphisms were genotyped using the PCR sequence-specific primer (PCR-SSP) technique and PCR-restriction fragment length polymorphism (RFLP) analysis.

RESULTS

We found that increased risk of psoriasis was associated with the FOXP3 -3279 AC genotype (adjusted OR, 1.32; 95% CI, 1.01-1.74) and the combined AC+AA genotype (adjusted OR, 1.38; 95% CI, 1.07-1.78), compared with the -3279 CC genotype. We also found that an increased risk of psoriasis was associated with the FOXP3 IVS9+459 GG genotype (adjusted OR, 2.24; 95% CI, 1.41-3.58). However, the combined GA+GG genotype showed no such tendency (adjusted OR=1.28; 95% CI, 1.00-1.64), compared with the IVS9+459 AA genotype. There was no evidence of an increased risk associated with the FOXP3-6054 deletion/ATT or FOXP3-924 A/G genotype. In combined genotype analyses, the FOXP3-3279 AC+AA genotype was more obviously associated in males (adjusted OR=1.60, 95% CI=1.11-2.31) and severe psoriasis patients (PASI score >20; adjusted OR=1.97, 95% CI=1.41-2.75). Meanwhile, the FOXP3 IVS9+459 GA+GG genotype was also associated with severe psoriasis patients (adjusted OR=1.69, 95% CI=1.21-2.36).

CONCLUSIONS

FOXP3 polymorphisms appear to contribute to the risk of psoriasis in a Han Chinese population. Larger studies are needed to confirm these findings.

Melanocyte as a possible key cell in the pathogenesis of psoriasis vulgaris

Current research in pathogenesis of psoriasis vulgaris suggests that the inflammatory mechanisms are immune based and most likely initiated and maintained by T cells. However, the question of lymphocyte being an initiator of psoriatic events remains open so far. Clinical observations such as plaque symmetry, stress-induced onset or exacerbations, pruritus, and possibility of generalization, suggest a role of the nervous system and neurogenic inflammation in pathogenesis. A key to understanding the role of melanocyte in psoriasis is their ability to act as regulatory cell in maintaining epidermal homeostasis. In suggested hypothetic event, melanocyte, acting as a local "stress sensor", provide communicatory link between CNS and skin. The disease probably begins with so far unknown signal directed through neuronal network to the melanocyte, placed in the center of epidermal unit. That signal governs keratinocyte cellular activities and lead to reactive abnormal epidermal differentiation and hyperproliferation. Increased proliferation of basal keratinocytes and high metabolic demands creates angiogenesis in papillary dermis and elongation of dermal papillae. Stimulated melanocytes and basal keratinocytes become an important source of proinflammatory cytokines that attract lymphocytes in dermis. In conclusion, according to our hypothesis, lymphocyte infiltrate in psoriasis is secondary event rather than vice versa as presented in the literature.

Angiogenesis drives psoriasis pathogenesis

Psoriasis pathogenesis is closely associated with disease-inducing Th1 and Th17 cells. Yet, several studies suggest that aberrant keratinocyte or endothelial cell signalling significantly contributes to disease manifestation. Histological hallmarks of psoriatic skin include the infiltration of multiple immune cells, keratinocyte proliferation and increased dermal vascularity. Formation of new blood vessels starts with early psoriatic changes and disappears with disease clearance. Several angiogenic mediators like vascular endothelial growth factor, hypoxia-inducible factors, angiopoietins and pro-angiogenic cytokines, such as tumour necrosis factor (TNF), interleukin (IL)-8 and IL-17, are up-regulated in psoriasis development. Contact- and mediator-dependent factors derived from keratinocytes, mast cells and immune cells may contribute to the strong blood vessel formation of psoriasis. New technologies and experimental models provide new insights into the role of angiogenesis in psoriasis pathogenesis. Interestingly, many therapies target not only immune cells, but also protein structures of endothelial cells. Here we summarize the role of pro-angiogenic factors in psoriasis development and discuss angiogenesis as a potential target of novel therapies.

Upregulation of Fas and downregulation of CD94/NKG2A inhibitory receptors on circulating natural killer cells in patients with new-onset psoriasis

BACKGROUND

Psoriasis has been considered as a T-helper 1 cell-mediated autoimmune disease driven by collaboration with multiple components of innate and acquired immune cells. Natural killer (NK) cells have been shown to bridge innate and acquired immunity, and thus could potentially contribute to the pathophysiology of psoriasis.

OBJECTIVES

To investigate the phenotypic changes of circulating NK cells in patients with new-onset psoriasis.

METHODS

Fifteen patients with plaque psoriasis (eight women and seven men) who visited our clinic after their first episode of psoriasis and did not have a history of previous systemic therapy or phototherapy participated in this study. Peripheral blood mononuclear cells were isolated and stained with a panel of antibodies against cell surface receptors expressed on T and/or NK cells and analysed by flow cytometry.

RESULTS

As compared with normal healthy volunteers, patients with new-onset psoriasis showed no significant changes in numbers of peripheral NK, NK-T or T cells. NK activating receptors 2B4, CD48, NKG2D, CD16 and CD56 were found to be unchanged in new-onset psoriasis. However, the expression of Fas (activation-induced death receptor) was upregulated, whereas the expression of the NK inhibitory receptors CD94 and NKG2A was dramatically reduced on NK cells of new-onset psoriasis. These changes occurred at the level of mean fluorescent intensity, but minimally affected percentages of cells expressing Fas, CD94 and NKG2A.

CONCLUSIONS

Our findings demonstrate that changes in the expression of Fas and CD94/NKG2A receptors on NK cells may occur during new-onset psoriasis, and are likely to contribute to the pathogenesis of psoriasis.

The IL-23/Th17 axis in the immunopathogenesis of psoriasis

Abnormal production of inflammatory mediators is believed to play an important role in the pathogenesis of psoriasis. Emerging data, both in mice and in humans, put the spotlight on a new subset of T helper (Th) cells, in part characterized by their production of IL-17 and accordingly named Th17 cells. Here, we review the development, characterization, and function of human Th17 cells as well as the crucial role of IL-23 in the context of Th17-cell-dependent chronic inflammation in psoriasis. We further discuss recent clinical trials targeting the IL-23/Th17 axis in psoriasis.

Serum levels of IL-17 and IL-22 are reduced by etanercept, but not by acitretin, in patients with psoriasis: a randomized-controlled trial

INTRODUCTION

There are no controlled trials comparing etanercept and acitretin efficacy and therapeutic mechanisms in psoriasis.

MATERIALS AND METHODS

In the present study, 30 patients were given etanercept 50 mg twice weekly and 30 patients acitretin 0.4 mg/kg per day, both for 12 weeks. Before and after treatment, psoriasis area and severity index was calculated, and serum levels of interleukin (IL)-17, IL-22, and IL-23 were investigated.

RESULTS

After treatment, psoriasis area and severity index was significantly lower for both groups. However, etanercept-treated patients showed lower psoriasis area and severity index than acitretin-treated ones. Psoriasis patients showed higher IL-17 and IL-22 levels than controls, while no IL-23 was found in any serum. Furthermore, a correlation between IL-17 levels and psoriasis severity was found. Only etanercept was able to reduce IL-17 and IL-22 levels.

CONCLUSIONS

Our findings suggest that etanercept is more effective than acitretin in the treatment of psoriasis and that it is able to affect Th17 system.

Key role of macrophages in the pathogenesis of CD18 hypomorphic murine model of psoriasis

Psoriasis is a chronic skin disorder of unsolved pathogenesis affecting skin in 2-3% of the general population. Research into the pathogenesis of psoriasis has profited from suitable animal models. Previously, we reported on the CD18 hypomorphic (CD18(hypo)) PL/J mouse model clinically resembling human psoriasis, which is characterized by reduced expression of the common chain of beta(2)-integrins (CD11/CD18) to only 2-16% of wild-type levels. Aside from common clinical and pathophysiological features shared with human psoriasis, the psoriasiform skin disease in CD18(hypo) PL/J mice also depends on the presence of CD4(+) T-cells. This review focuses on the role of activated macrophages in the pathogenesis of CD18(hypo) T-cell-mediated mouse model of psoriasis, and extends our understanding in unrestrained pathogenic T-cells whose activation may be crucial for the recruitment and activation of macrophages within skin. The findings in the CD18(hypo) PL/J model are discussed in the context of current literatures of human and other autoimmune disorders.

The Increased Expression of Matrix Metalloproteinase-9 Messenger RNA in the Non-lesional Skin of Patients with Large Plaque Psoriasis Vulgaris

BACKGROUND

A difference of the interleukin-18 (IL-18) mRNA expression among several proinflammatory genes was previously observed between large plaque (LP) psoriasis patients (more than 5 cm lesions are typical) and small plaque (SP) psoriasis patients (1~2 cm lesions are typical). Therefore, it is necessary to test whether there is any difference in the expression of the genes that activate IL-18 or the expression of genes that are induced by IL-18.

OBJECTIVE

To test the differential mRNA expressions of caspase-1, STAT-6, MMP-1, MMP-2, MMP-9 and TIMP-1 according to the clinical types of psoriasis vulgaris lesions in Korean patients, we have analyzed the skin samples of psoriasis vulgaris patients.

METHODS

The total cellular RNA of skin samples from groups of patient with LP and SP psoriasis was analyzed by performing real-time PCR (the Taqman method) to compare the differences in the mRNA expressions.

RESULTS

The caspase-1 and STAT-6 mRNA expression levels from the SP lesional skin of the patients were increased compared with the caspase-1 and STAT-6 mRNA expression levels from SP non-lesional skin or normal skin, but these expression levels from the SP non-lesional skin were not significantly different from those of the LP non-lesional skin. Among MMP-1, MMP-2, MMP-9 and TIMP-1, the expressions of MMP-1, MMP-2 and MMP-9 mRNA were increased in the SP lesional skin compared with those of the SP non-lesional skin. The MMP-1 mRNA expressions in both the LP and SP lesional skin were increased compared with those in the normal skin (p=0.028 and p=0.007 respectively). The MMP-9 mRNA expression in the LP non-lesional skin was elevated compared with the MMP-9 mRNA expression in the SP non-lesional skin (p=0.047). The TIMP-1 mRNA expression levels from the non-lesional skin and the lesional skin of the psoriasis patients and the normal skin samples were not significantly different.

CONCLUSION

The increased expression of MMP-9 mRNA in the LP non-lesional skin compared to that of the SP non-lesional skin in the psoriatic skin suggests that the increased MMP-9 mRNA expression is related to the large size type of lesion.

Polymorphism of the catechol-O-methyltransferase gene in Han Chinese patients with psoriasis vulgaris

Psoriasis vulgaris is defined by a series of linked cellular changes in the skin: hyperplasia of epidermal keratinocytes, vascular hyperplasia and ectasia, and infiltration of T lymphocytes, neutrophils and other types of leukocytes in the affected skin. Catechol-O-methyltransferase (COMT) 158 polymorphism can reduce the activity of the COMT enzyme that may trigger defective differentiation of keratinocytes in psoriasis. Immunocytes can degrade and inactivate catecholamines via monamine oxidase (MAO) and COMT in the cells. We hypothesized that the COMT-158G > A polymorphism was associated with the risk of psoriasis vulgaris in Han Chinese people. In a hospital-based case-control study, 524 patients with psoriasis vulgaris and 549 psoriasis-free controls were studied. COMT-158 G > A polymorphism was genotyped using the PCR sequence-specific primer (PCR-SSP) technique. We found no statistically significant association between the COMT-158 allele A and the risk of psoriasis vulgaris (p = 0.739 adjusted OR = 1.03; 95% CI = 0.81-1.31). This suggests that the COMT-158 G > A polymorphism may not contribute to the etiology of psoriasis vulgaris in the Han Chinese population.

FLT3 inhibitors for the treatment of autoimmune disease

BACKGROUND

Autoimmune diseases encompass a broad range of illnesses with a variety of underlying causes, some of which are known and some of which remain elusive.

OBJECTIVE

The focus of this review will be on describing the development of a new type of therapy that could potentially treat T cell-mediated autoimmune diseases. Unlike traditional therapies, which have primarily focused on suppressing T cells directly, targeting the step of antigen presentation may allow a less toxic therapy in which autoimmunity is lessened without compromising the entire immune system. This review will outline the science behind the development of the therapy, the roles of dendritic cells in generating autoimmune disease, and the function of the FLT3 receptor in this process.

A comprehensive review of the genetics of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy of childhood which is believed to be influenced by both genetic and environmental factors. The progress in identifying genes underlying JIA susceptibility using candidate gene association studies has been slow. Several associations between JIA and variants in the genes encoding the human leukocyte antigens (HLA) have been confirmed and replicated in independent cohorts. However it is clear that genetic variants outside the HLA also influence susceptibility to JIA. While a large number of non-HLA candidate genes have been tested for associations, only a handful of reported associations such as PTPN22 have been validated. In this review we discuss the principles behind genetic studies of complex traits like JIA, and comprehensively catalogue non-HLA candidate-gene association studies performed in JIA to date and review several validated associations. Most candidate gene studies are underpowered and do not detect associations, and those that do are often not replicated. We also discuss the principles behind genome-wide association studies and discuss possible implications for identifying genes underlying JIA. Finally we discuss several genetic variants underlying multiple clinically distinct autoimmune phenotypes.

Vitiligo and melanoma-associated hypopigmentation (MAH): shared and discriminative features

BACKGROUND

It is unclear if differences between melanoma-associated hypopigmentation (MAH) and classical vitiligo exist.

PATIENTS AND METHODS

Hypopigmented areas and associated lesions (halo nevi, hypopigmented scars) in 15 melanoma patients and 31 patients with classical vitiligo were analyzed by digital photography. The activity of the respective lesions was assessed by the vitiligo disease activity (VIDA) score. Associated diseases were recorded by history and serological tests;genotyping of HLA class I antigens as well as histology/immunohistology were performed.

RESULTS

MAH were diagnosed in 12 of 15 melanoma patients; mean onset was 4.8 years after the primary diagnosis of the melanoma. Three melanoma patients reported hypopigmentation more than 15 years before diagnosis of melanoma. In the history and family history of vitiligo patients, autoimmune diseases were much more frequent and haplotype HLA-A2 was twice as common compared to MAH patients. MAH lesions were most often distributed in a bilateral symmetrical pattern, corresponding to vitiligo. MAH was less progressive compared to classical vitiligo; however, it was more often associated with other acquired leukodermas. In both groups hypopigmentation spread centripetally to the trunk. Histological and immunohistological differences were not found.

CONCLUSIONS

Whereas differences exist concerning associated autoimmune diseases, MAH and vitiligo shared many common clinical and histological features. Further studies are needed to assess the clinical relevance of vitiligo-like alterations in melanoma patients.

Cytokines and anticytokines in psoriasis

BACKGROUND

Psoriasis is a chronic autoimmune hyperproliferative skin disease of varying severity affecting approximately 2-3% of the general population in the USA and Europe. Although the pathogenesis of psoriasis has not been fully elucidated, an immunologic-genetic relationship is likely. Cutaneous and systemic overexpression of various proinflammatory cytokines (TNF, interleukins, interferon-gamma) has been demonstrated in psoriatic patients.

METHODS

We reviewed the current database literature and summarized the involvement of cytokines and their receptors in the pathogenesis and treatment of psoriasis.

RESULTS

Although many cytokine/anti-cytokine therapies have been conducted, TNF antagonists in the treatment of both psoriasis arthropatica and vulgaris appear to be the most widely used clinically. Interestingly, the efficacy and tolerability of some cytokines (rhIL-11 or ABX-IL-8,) were found to be much lower than expected.

CONCLUSIONS

Preliminary results obtained with cytokine and anti-cytokine therapies appear promising and as such continued research is clearly indicated.

Genes and structure of selected cytokines involved in pathogenesis of psoriasis

Psoriasis is a common skin disease involving 1-4% of human population worldwide, of strong genetic background. The following cytokines are directly involved in psoriasis: TNF, IL-1, IL-2, IL-6, IL-7, IL-8, IL-15, IL-18, IL-19, IL-20, IL-23 whereas IL-4, IL-10, IL-12 as well as IL-11, IL-17 and IFN-gamma are rather indirectly engaged. This work is a review of some genetic factors and structure of selected cytokines and receptors and their genes location.

The lipid profile in psoriasis: a controlled study

BACKGROUND

Psoriasis is an inflammatory dermatosis that is characterized with hyperproliferation of keratinocytes and inflammatory infiltration in the epidermis and dermis. The high prevalence of atherosclerosis has been reported in psoriatic patients. High serum lipid level has been suggested in the pathogenesis of this phenomenon. In this study, our purpose was to compare the lipid profile in psoriatic patients with non-affected persons.

METHODS

This study was designed and conducted as a case-control assay with 50 cases in the patient and control groups, respectively. The lipid profile, including serum level of triglyceride, cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL), were assessed in both groups.

RESULTS

The patient and control groups each consisted of 50 cases (39 male and 11 female). The serum triglyceride, cholesterol, and LDL was significantly higher in psoriatic patients (P < 0.05) but not for HDL (P = 0.29).

CONCLUSION

This study, like previous assays, shows that high serum lipid level is significantly more common in psoriasis. This fact may be responsible for higher prevalence of cardiovascular accident in psoriatic patients. It may be useful to do early screening and treatment of hyperlipidaemia in psoriasis to prevent the atherosclerosis and its complications.