Proliferating cells in psoriatic dermis are comprised primarily of T cells, endothelial cells, and factor XIIIa+ perivascular dendritic cells

Circulating Monocytes Are Predictive and Responsive in Moderate-to-Severe Plaque Psoriasis Subjects Treated with Apremilast

Monocytes play a critical role in the inflammation associated with psoriasis, and their abnormalities have been reported as biomarkers of cardiovascular event risk, a psoriasis comorbidity. Monocytic cells in chronic inflammatory disorders express elevated levels of cAMP phosphodiesterase. Restoring cAMP levels using the oral cAMP phosphodiesterase-4 inhibitor, apremilast, improves clinical outcomes for a subset of patients with psoriasis. We asked whether aberrant monocyte subsets or transcriptomic pathways can function as biomarkers of psoriasis endotypes that can predict enhanced clinical responses to cAMP phosphodiesterase inhibition. A 16-week open-label study of 22 patients with monocyte flow cytometric and transcriptomic analysis was performed. Subjects with elevated hyperadhesive monocyte doublets at baseline were more likely to be responders to apremilast (P < .0001); 82% of subjects with elevated hyperadhesive monocyte doublets achieved 50% reduction in PASI compared with 46% in those without elevated doublets. We observed a significant reduction in hyperadhesive monocyte-containing doublets and monocyte-platelet aggregates, suggesting an effect of apremilast on the adhesiveness of blood monocytes during chronic inflammation. Monocyte differentially expressed gene transcripts predictive of clinical response uncovered pharmacoendotypes with distinct patterns of nucleotide metabolism, energetics, and differentiation. Further study to understand the basis of drug responsiveness and to develop an apremilast psoriasis treatment algorithm using monocyte-refined gene expression is required to validate and become practical in clinical use, offering patients a test that personalizes their likelihood of clinical response.

High-throughput RNA sequencing from paired lesional- and non-lesional skin reveals major alterations in the psoriasis circRNAome

BACKGROUND

Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation and abnormal differentiation of keratinocytes. It is one of the most prevalent chronic inflammatory skin conditions in adults worldwide, with a considerable negative impact on quality of life. Circular RNAs (circRNAs) are a recently identified type of non-coding RNA with diverse cellular functions related to their exceptional stability. In particular, some circRNAs can bind and regulate microRNAs (miRNAs), a group of RNAs that play a role in the pathogenesis of psoriasis. The aim of this study was to characterize the circRNAome in psoriasis and to assess potential correlations to miRNA expression patterns.

METHODS

We used high-throughput RNA-sequencing (RNA-seq), NanoString nCounter technology and RNA chromogenic in situ hybridization (CISH) to profile the circRNA expression in paired lesional and non-lesional psoriatic skin from patients with psoriasis vulgaris. In addition, 799 miRNAs were profiled using NanoString nCounter technology and laser capture microdissection was used to study the dermis and epidermis separately.

RESULTS

We found a substantial down-regulation of circRNA expression in lesional skin compared to non-lesional skin. We observed that this mainly applies to the epidermis by analyzing laser capture microdissected tissues. We also found that the majority of the circRNAs were downregulated independently of their corresponding linear host genes. The observed downregulation of circRNAs in psoriasis was neither due to altered expression levels of factors known to affect circRNA biogenesis, nor because lesional skin contained an increased number of inflammatory cells such as lymphocytes. Finally, we observed that the overall differences in available miRNA binding sites on the circRNAs between lesional and non-lesional skin did not correlate with differences in miRNA expression patterns.

CONCLUSIONS

We have performed the first genome-wide circRNA profiling of paired lesional and non-lesional skin from patients with psoriasis and revealed that circRNAs are much less abundant in the lesional samples. Whether this is a cause or a consequence of the disease remains to be revealed, however, we found no evidence that the loss of miRNA binding sites on the circRNAs could explain differences in miRNA expression between lesional and non-lesional skin.

The anti-angiogenic effect of tryptanthrin is mediated by the inhibition of apelin promoter activity and shortened mRNA half-life in human vascular endothelial cells

BACKGROUND

Anti-angiogenesis is an important strategy of psoriasis treatment, but the side effects of systemic agents remain difficult to overcome. Topical use of indigo naturalis ointment has been proved to improve the skin lesion of psoriasis effectively and safely and one of its major components, tryptanthrin, has been demonstrated to have anti-angiogenic effect. Apelin, which has been reported to act as an angiogenic factor that could stimulate the proliferation and migration of vascular endothelial cells and proved to be elevated in psoriasis patients, is a potential target of anti-angiogenic therapy.

PURPOSE

We aim to find out if tryptanthrin works on the apelin pathway and study its anti-angiogenic mechanism.

STUDY DESIGN

Human umbilical vein endothelial cells (HUVECs) were used as the in vitro model.

METHODS

The effect of tryptanthrin on the expression of apelin and its receptor, APJ, was examined. The mRNA stability, promoter activity, and bioactivity of apelin, were also investigated. Migration and tube formation assay were used to evaluate the relationship between tryptanthrin and apelin. PD98059 and wortmannin were used to study the role of ERK1/2 MAPK and PI3K in apelin signaling pathway.

RESULTS

We demonstrated that tryptanthrin could inhibit the expression of apelin, attenuated the stability of apelin mRNA, and significantly inhibited the apelin promoter activity. The addition of apelin-13 restored the suppression of tube formation and migration by tryptanthrin. Both PD98059 and wortmannin could down-regulate the apelin mRNA expression suggesting the important signaling role of ERK1/2 MAPK and PI3K in the gene expression of apelin.

CONCLUSION

The anti-angiogenic effect of tryptanthrin was mediated by down-regulating apelin gene expression through suppression of promoter activity and decrease of mRNA stability in human vascular endothelial cells.

Factor XIII Subunit A in the Skin: Applications in Diagnosis and Treatment

The role of factor XIII subunit A (FXIII-A) is not restricted to hemostasis. FXIII-A is also present intracellularly in several human cells and serves as a diagnostic marker in a wide range of dermatological diseases from inflammatory conditions to malignancies. In this review, we provide a guide on the still controversial interpretation of dermal cell types expressing FXIII-A and assess the previously described mechanisms behind their accumulation under physiological and pathological conditions of the human skin. We summarize the intracellular functions of FXIII-A as well as its possible sources in the extracellular space of the dermis with a focus on its relevance to skin homeostasis and disease pathogenesis. Finally, the potential role of FXIII-A in wound healing, as a field with long-term therapeutic implications, is also discussed.

Expression of Angiogenic Factors in Psoriasis Vulgaris

INTRODUCTION

Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperproliferation, abnormal differentiation and inflammatory infiltration in the dermis. The dermal microvascular expansion associated with abnormal orientation and dilatation of capillaries in the biopsies of the psoriatic skin suggest that the disease is dependent on angiogenesis.

AIM

To analyze and compare the immunohistochemical expression of angiogenic factors - Vascular Endothelial Growth Factor (VEGF), von Willebrand Factor (vWF) and CD 34 in skin biopsies of psoriasis cases with control skin samples; and to correlate the expression of angiogenic factors with Psoriasis Area and Severity Clinical Index (PASI SCORE).

MATERIALS AND METHODS

This was a prospective case control study conducted over a period of 15 months. Thirty-two psoriasis cases and thirty control skin samples were included in the study. Skin biopsy specimen was taken from clinically diagnosed psoriasis cases who did not receive any treatment. The diagnosis of psoriasis vulgaris was confirmed after microscopic examination. Immunohistochemical expression for VEGF, vWF and CD 34 was studied.

RESULTS

VEGF expression in epidermis was significantly higher in cases when compared to control skin (p <0.01). CD 34 expression was significantly upregulated in cases when compared to controls (p<0.01). Von Willebrand factor expression was weak in both the cases and the controls. Significant correlation between the expression of VEGF and PASI score (r=0.944; p<0.01), and expression of CD 34 and PASI score was observed (r=0.942; p<0.01).

CONCLUSION

In the present study, significant overexpression of VEGF and CD 34 was noted in cases when compared to controls. The keratinocytes in the psoriatic skin lesions were recognized as a source of pro-angiogenic cytokines namely the VEGF and other growth factors which promotes angiogenesis in psoriatic plaque. Angiogenesis plays an important role in genesis and development of psoriasis vulgaris. Therefore, development of targeted anti-angiogenic therapy might be beneficial for this chronic disabling dermatological disease.

Can We Repurpose FDA-Approved Alefacept to Diminish the HIV Reservoir?

Current anti-retroviral treatment (ART) for HIV is effective in maintaining HIV at undetectable levels. However, cessation of ART results in immediate and brisk rebound of viremia to high levels. This rebound is driven by an HIV reservoir mainly enriched in memory CD4+ T cells. In order to provide any form of functional HIV Cure, elimination of this viral reservoir has become the focus of current HIV cure strategies. Alefacept was initially developed for the treatment of chronic plaque psoriasis. Alefacept is a chimeric fusion protein consisting of the CD2-binding portion of human leukocyte function antigen-3 (LFA3) linked to the Fc region of human IgG1 (LFA3-Fc). Alefacept was designed to inhibit memory T cell activation that contributes to the chronic autoimmune disease psoriasis by blocking the CD2 coreceptor. However, it was found to deplete memory T cells that express high levels of CD2 via NK cell-mediated antibody dependent cell cytotoxicity (ADCC) in vivo. Phase II and phase III clinical trials of alefacept with psoriasis patients demonstrated promising results and an excellent safety profile. Subsequently, alefacept has been successfully repurposed for other memory T cell-mediated autoimmune diseases including skin diseases other than psoriasis, organ transplantation and type I diabetes (T1D). Herein, we review our specific strategy to repurpose the FDA approved biologic alefacept to decrease and hopefully someday eliminate the HIV reservoir, for which CD2hi memory CD4+ T cells are a significant contributor.

The pathophysiological role of dendritic cell subsets in psoriasis

Psoriasis is a chronic inflammatory disorder characterized by an erythematous scaly plaque of the skin and is occasionally accompanied by systemic complications. In the psoriatic lesions, an increased number of cytokine-producing dendritic cells and activated T cells are observed, which indicate that psoriasis is a prototype of an immune-mediated dermatosis. During the last decade, emerging studies demonstrate novel roles for the dendritic cell subsets in the process of disease initiation and maintenance of psoriasis. In addition, recently discovered anti-psoriatic therapies, which specifically target inflammatory cytokines produced by lesional dendritic cells, bring much better clinical improvement compared to conventional treatments. These new therapies implicate the crucial importance of dendritic cells in psoriasis pathogenesis. This review will summarize and discuss the dendritic cell subsets of the human skin and their pathophysiological involvement in psoriasis based on mouse- and patient-oriented studies. [BMB Reports 2014; 47(2): 60-68]

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.

IL-6 signaling in psoriasis prevents immune suppression by regulatory T cells

T memory/effector cells (Tmem/eff) isolated from psoriatic patients are chronically activated and poorly suppressed by regulatory T cells (Treg). The proinflammatory cytokine IL-6, which signals through Stat3, allows escape of Tmem/eff cells from Treg-mediated suppression in a murine system. We show here that IL-6 protein is markedly elevated and most highly expressed by CD31(+) endothelial cells and CD11c(+) dermal dendritic cells (DCs) in lesional psoriatic skin. We hypothesized that exposure to high IL-6 in lesional tissue may lead to the dampened Treg function observed in psoriasis patients. Indeed, we found that IL-6, but not other Stat3-activating cytokines, was necessary and sufficient to reverse human T cell suppression by Treg in an in vitro model using activated DCs as a source of IL-6. IL-6Ralpha and gp130 expression was significantly elevated in psoriatic effector T cells compared with normal controls. Overall, IL-6Ralpha expression on Treg exceeded that of effector T cells, and both populations phosphorylated Stat3 in response to IL-6. Phosphorylation of Stat3 in T cells contributes to Th17 differentiation and we identify cells within lesional tissue that coexpress CD3, IL-17, and IL-6, indicating that Th17 cells are present in vivo within the psoriatic Tmem/eff population and contribute to IL-6-mediated resistance to Treg suppression. Taken together, T lymphocytes trafficking into lesional psoriatic skin encounter high IL-6 from endothelial cells, DCs, and Th17 cells, enabling cutaneous T cell escape from Treg suppression and Th17 participation in inflammation. Targeting IL-6 signaling pathways in psoriasis may rebalance Treg/T effector activity and ameliorate disease.

Alefacept in the treatment of psoriasis

Alefacept is the first biologic agent approved by the US Food and Drug Administration for the treatment of psoriasis. To date, more than 1000 patients with moderate to severe psoriasis have been enrolled in phase III clinical trials of alefacept. More than 30% of patients treated with 2 courses of alefacept reached a Physician's Global Assessment of clear to almost clear, and approximately 40% and 70% of patients achieved a Psoriasis Area Severity Index score of 75 and 50 after the same regimen. Alefacept is well tolerated, and there have been no reports of significant systemic toxicity or serious treatment-related adverse events.

A phase 1, double-blind, placebo-controlled study evaluating single subcutaneous administrations of a human interleukin-12/23 monoclonal antibody in subjects with plaque psoriasis

OBJECTIVE

To evaluate safety, pharmacokinetics, pharmacodynamics, and clinical response of single subcutaneous (s.c.) administrations of a human monoclonal antibody against the p40 subunit of IL-12/23 (IL-12/23 mAb) in subjects with moderate-to-severe psoriasis.

METHODS

Twenty-one subjects were enrolled sequentially into 4 dose cohorts (0.27, 0.675, 1.35, and 2.7 mg/kg) and randomized to IL-12/23 mAb or placebo in a 4:1 ratio. Laboratory/clinical parameters and pharmacokinetics were evaluated through Week 24; mRNA cytokine expression was measured in psoriatic plaques at Week 1.

RESULTS

Mostly mild adverse events and no serious adverse events were reported. The pharmacokinetics (Cmax and AUC) of IL-12/23 mAb increased in an approximately dose-proportional manner. Of the 17 subjects who received IL-12/23 mAb, 13 achieved PASI 75 (compared with no placebo subjects). mRNA expression of IL-8, IL-18, and IFN-gamma in psoriatic plaques decreased in subjects with sustained Psoriasis Area and Severity Index (PASI) improvement.

LIMITATIONS

Interpretation of results is limited due to the small sample size in each dose cohort.

CONCLUSION

A single s.c. administration of IL-12/23 mAb was well tolerated and showed clinical response in subjects with moderate-to-severe psoriasis.

Clinical and immunohistochemical assessment of the effect of cyclosporin in keratinocytes and dermal dendrocytes in psoriasis

BACKGROUND

Cyclosporine is a potent immunosupressor, which induces cytokeratin expression pattern changes and dermal dendrocytes number increase.

OBJECTIVES

To evaluate its clinical effect in psoriasis, on keratinocytic proliferation and differentiation, and on dermal dendrocytes proliferation.

METHODS

Thirty patients with psoriasis were treated and evaluated for 8 weeks. Clinical improvement was evaluated by Psoriasis Area and Severity Index (PASI). Biopsies were performed initially and after 8 weeks. Immunohistochemistry [CK markers 10, 14, and 16, and factor XIIIa+ (FXIIIa+)] was performed.

RESULTS

Mean PASI before treatment was 26.32 and 3.71 after. Mean initial and final PASI difference was 22.61 (p < 0.001). Two patients had serum creatinine and six uric acid increase. Before and after treatment, mean numbers per field of dermal dendrocytes were 7.07 and 3.68, respectively. Mean difference was 3.39, with p < 0.001. CK10 immunohistochemical pattern demonstrated recovery of normal expression pattern in 26 patients, while CK14 pattern demonstrated improvement in 21 patients.

CONCLUSIONS

Cyclosporine was effective and safe for psoriasis in low doses, with significant decrease of PASI and dermal dendrocytes number after 8 weeks of therapy. CK10 and 14 pattern changed and, less prominently, CK16 expression. These modifications occur later than the PASI and dermal dendrocytes variation.

Regulatory T cells in psoriasis

Psoriasis is a chronic autoimmune disease in which T lymphocytes are thought to be central in the pathogenesis. Recently, a T cell subset population was identified, whose role is to suppress inflammatory responses triggered by T effector cells. T cells in this new population are referred to as T regulatory cells. We studied their number and activity in psoriatic lesions and found that they are both numerically and functionally deficient in their ability to suppress the abnormally persistent psoriatic immune response. This deficiency may shed more light on the complex pathophysiology of psoriasis.

An Anti-IL-12p40 Antibody Down-Regulates Type 1 Cytokines, Chemokines, and IL-12/IL-23 in Psoriasis

Psoriasis is characterized by activation of T cells with a type 1 cytokine profile. IL-12 and IL-23 produced by APCs are essential for inducing Th1 effector cells. Promising clinical results of administration of an Ab specific for the p40 subunit of IL-12 and IL-23 (anti-IL-12p40) have been reported recently. This study evaluated histological changes and mRNA expression of relevant cytokines and chemokines in psoriatic skin lesions following a single administration of anti-IL-12p40, using immunohistochemistry and real-time RT-PCR. Expression levels of type 1 cytokine (IFN-gamma) and chemokines (IL-8, IFN-gamma-inducible protein-10, and MCP-1) were significantly reduced at 2 wk posttreatment. The rapid decrease of these expression levels preceded clinical response and histologic changes. Interestingly, the level of an anti-inflammatory cytokine, IL-10, was also significantly reduced. Significant reductions in TNF-alpha levels and infiltrating T cells were observed in high responders (improvement in clinical score, > or =75% at 16 wk), but not in low responders. Of importance, the levels of APC cytokines, IL-12p40 and IL-23p19, were significantly decreased in both responder populations, with larger decreases in high responders. In addition, baseline levels of TNF-alpha significantly correlated with the clinical improvement at 16 wk, suggesting that these levels may predict therapeutic responsiveness to anti-IL-12p40. Thus, in a human Th1-mediated disease, blockade of APC cytokines by anti-IL-12p40 down-regulates expression of type 1 cytokines and chemokines that are downstream of IL-12/IL-23, and also IL-12/IL-23 themselves, with a pattern indicative of coordinated deactivation of APCs and Th1 cells.

In Vitro and In Situ Expression of IL-23 by Keratinocytes in Healthy Skin and Psoriasis Lesions: Enhanced Expression in Psoriatic Skin

Keratinocytes contribute to cutaneous immune responses through the expression of cytokines. We investigated whether human keratinocytes can express IL-23, a newly defined IFN-gamma-inducing cytokine composed of a unique p19 subunit and a p40 subunit shared with IL-12. Cultured keratinocytes from normal and lesional psoriatic skin were found to express constitutively mRNA for both subunits of IL-23. Low but significant levels of the heterodimeric IL-23 protein could be detected in cell lysates and supernatants from stimulated keratinocytes by immunoblotting and ELISA. Functional analysis showed that these low levels of keratinocyte-derived IL-23 were sufficient to enhance the IFN-gamma production by memory T cells. Immunostaining of skin sections confirmed expression of both subunits of IL-23 by keratinocytes in situ and also revealed expression of this cytokine in the dermal compartment. IL-23 expression was significantly higher in psoriatic lesional skin, compared with normal and psoriatic nonlesional skin. The immunostained preparations of cultured cells and IL-23 levels in culture supernatants did not show any difference between normal and psoriatic keratinocytes indicating no intrinsic aberration of IL-23 expression in keratinocytes from psoriatic skin. Double staining of cytospin preparations demonstrated that IL-23 p19 is also expressed by epidermal Langerhans cells, dermal dendritic cells, and macrophages. Psoriasis is a chronic inflammatory skin disease mediated by IFN-gamma-expressing type 1 memory T cells. As IL-23 is important to activate memory T cells to produce IFN-gamma, its augmented expression of IL-23 by keratinocytes and cutaneous APC may contribute to the perpetuation of the inflammation process in this disease.

Ação da pentoxifilina nos dendrócitos dérmicos FXIIIa de placas de psoríase

FUNDAMENTOS: Não há consenso sobre o papel dos dendrócitos dérmicos (DD) nos eventos fisiopatológicos nos períodos de exacerbação e de acalmia da doença. A pentoxifilina (PTX) é uma metilxantina que inibe vários mecanismos inflamatórios. OBJETIVO: Estudar os efeitos da PTX sobre os dendróticos dérmicos de placas de psoríase com técnicas imuno-histoquímicas. MATERIAL E MÉTODOS: Trinta biópsias de placas de psoríase antes e após oito semanas de uso oral diário de 1.200mg de PTX foram incubadas com anticorpo primário de coelho antiFator XIIIa e anticorpo de ligação conjugado com fosfatase alcalina. RESULTADOS: As células imunomarcadas Fator XIIIa+ foram proeminentes com morfologia dendrítica arborescente na derme papilar formando linha celular logo abaixo da epiderme e exibindo arranjo nodular ao redor dos vasos. Após tratamento, as células apresentaram-se com morfologia dendrítica e fusiforme, distribuídas ao redor dos vasos da derme papilar e predominantemente fusiformes dispostas paralelamente à junção dermoepidérmica retificada. CONCLUSÕES: A PTX promove aumento do fluxo sangüíneo e diminuição da adesividade endotelial, com aumento dos mastócitos e DD FXIIIa. A PTX inibe o TNF-alfa, que implica a diminuição da expressão de receptores pelos DDs, como CCR7 e a manutenção do estímulo tecidual para sinalização e migração dos precursores, uma vez que os processos etiopatogenéticos não são afetados pela droga.

Alefacept for the treatment of psoriasis: A review of the current literature and practical suggestions for everyday clinical use

Alefacept is the first biologic therapy approved by the United States Food and Drug Administration for the management of patients with moderate-to-severe chronic plaque psoriasis. Alefacept is a fully human fusion protein with a dual mechanism of action inhibiting T-cell activation as well as selectively reducing memory T cells. More than 2000 psoriasis patients have been treated with alefacept in clinical trials. These studies reveal an excellent clinical response, with 33% of patients achieving a Psoriasis Area Severity Index (PASI) score of 75 and 57% of patients achieving a PASI 50 after one course of alefacept. Patients achieving both PASI 75 and PASI 50 have significant improvements in their quality of life. The best responders can have long remissions, and there is a tendency toward continued improvement with subsequent courses of alefacept. The safety profile over the short and intermediate term is excellent. Preliminary data regarding alternate dosing regimens, transitioning patients from conventional systemics to alefacept, and combining alefacept with ultraviolet light therapy will be highlighted. We also will discuss our practical approach to patient selection, CD4 monitoring, management of infections while on alefacept, as well as decisions regarding retreatment and combination therapy.

Dysfunctional blood and target tissue CD4+CD25high regulatory T cells in psoriasis: mechanism underlying unrestrained pathogenic effector T cell proliferation

The balance between regulatory and effector functions is important for maintaining efficient immune responses, while avoiding autoimmunity. The inflammatory skin disease psoriasis is sustained by the ongoing activation of pathogenic effector T cells. We found that a CD4(+) T lymphocyte subpopulation in peripheral blood, phenotypically CD25(high), CTLA-4(+), Foxp3(high) (regulatory T (Treg) cells), is deficient in its suppressor activity in psoriasis. This was associated with accelerated proliferation of CD4(+) responder T cells in psoriasis, the majority of which expressed CXCR3. Nevertheless, criss-cross experiments isolated the defect to psoriatic Treg cells. To examine Treg cells in a nonlymphoid tissue of a human T cell-mediated disease, Treg cells were also analyzed and isolated from the site of inflammation, psoriatic lesional skin. At the regulatory vs effector T cells ratios calculated to be present in skin, however, the psoriatic Treg cell population demonstrated decreased suppression of effector T cells. Thus, dysfunctional blood and target tissue CD4(+)CD25(high) Treg cell activity may lead to reduced restraint and consequent hyperproliferation of psoriatic pathogenic T cells in vivo. These findings represent a critical component of human organ-specific autoimmune disease and may have important implications with regard to the possible therapeutic manipulation of Treg cells in vivo.

Overview of psoriasis

Psoriasis is a chronic disease that affects the skin and joints. Clinical hallmarks comprise erythematous plaques covered by silvery scaling and a chronic recurrent course. Histologically, psoriasis is characterized by the hyperproliferation of the epidermis, elongated and prominent blood vessels and a thick perivascular lymphocytic infiltrate. Psoriasis is now considered an auto-immune disease. Although many different therapies are available, there is clearly a need for new treatments. Our improvement of understanding of the pathogenesis of psoriasis together with the possibility to develop bioactive proteins ("biologicals") targeted at specific steps in the pathogenesis of psoriasis, have opened a new field of promising future treatments. In the development and assessment of new therapeutical modalities for psoriasis, a clear definition of a patient's psoriasis severity is essential. The impact of a given therapy can only then be evaluated, based on the changes in the severity score during and after application of the treatment.

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.

Photochemotherapy inhibits angiogenesis and induces apoptosis of endothelial cells in vitro

BACKGROUND

Photochemotherapy has long been used in the treatment of psoriasis; however, its mechanism has not been completely elucidated. Psoriasis is now regarded as an angiogenesis-related disease. Recent studies indicated that the inhibition of angiogenesis by photochemotherapy could be an underlying mechanism. It was found that photochemotherapy can downregulate the expression of angiogenic factors in keratinocytes. However, the direct effect of photochemotherapy on endothelial cells has not been studied.

METHODS

In this study, we determined the effect of photochemotherapy on the proliferation of human microvascular endothelial cells through MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and cell cycle analysis. The migration assay and in vitro tube formation assay were used to investigate the migration properties and tube formation ability of human microvascular endothelial cells after psoralen plus UVA (PUVA) treatment. The apoptosis of endothelial cells elicited by photochemotherapy was also analyzed with fluorescence-activated cell sorting analysis (FACS).

RESULTS

UVA (0.8-5.0 J/cm(2)) irradiation with the presence of 8-methoxypsoralen (8-MOP) (300 ng/ml) resulted in a dose-dependent reduction in the cell viabilities of endothelial cells. FACS data showed an accumulation of cells in G0/G1 phase of cell cycle and apoptotic features of cell death after UVA irradiation with psoralen. The migration properties and tube formation ability of endothelial cells were dramatically inhibited by photochemotherapy.

CONCLUSION

Our results showed that photochemotherapy inhibits angiogenesis and induces apoptosis of human microvascular endothelial cells in vitro, which may be a possible mechanism of photochemotherapy in the treatment of psoriasis.

Improved health-related quality of life following a randomized controlled trial of alefacept treatment in patients with chronic plaque psoriasis

BACKGROUND

Psoriasis has a negative impact on patients' quality of life. Treatment strategies should address both the cutaneous manifestations of the disease and their impact on quality of life.

OBJECTIVES

To evaluate the effect of alefacept on quality of life in 553 patients with chronic plaque psoriasis.

METHODS

In this multicentre, double-blind, parallel-groups study, patients were randomized to receive alefacept for two courses, alefacept in course 1 and placebo in course 2, or placebo in course 1 and alefacept in course 2. In each course, alefacept 7.5 mg or placebo was administered once weekly by 30-s intravenous injection for 12 weeks followed by 12 weeks of observation. The Dermatology Life Quality Index (DLQI), Dermatology Quality of Life Scales (DQOLS) and Short Form-36 Health Survey (SF-36) were administered at baseline, 2 weeks after the last dose in both courses, at the beginning of course 2, and at the end of the observation period in both courses.

RESULTS

In course 1, alefacept significantly reduced (improved) mean DLQI scores compared with placebo: 4.4 vs. 1.8 at 2 weeks after the last dose (P<0.0001) and 3.4 vs. 1.4 at 12 weeks after the last dose (P<0.001). Patients who received two courses of alefacept experienced additional enhancement of quality of life measures during the second course. Similar results were observed for the DQOLS. The SF-36 survey confirmed that alefacept had no negative impact on general quality of life.

CONCLUSIONS

Alefacept improved quality of life in patients with chronic plaque psoriasis and maintained this benefit for at least 12 weeks following cessation of treatment. A second course of alefacept provided additional quality of life benefit.

CD4+ T-cell–directed antibody responses are maintained in patients with psoriasis receiving alefacept: results of a randomized study

BACKGROUND

Alefacept, human LFA-3/IgG(1) fusion protein, selectively reduces memory-effector (CD45RO(+)) T cells, a source of the pathogenic mediators of psoriasis.

OBJECTIVE

To evaluate the effect of alefacept on immune function, T-cell-dependent humoral responses to a neoantigen (PhiX174) and recall antigen (tetanus toxoid) were assessed.

METHODS

Patients with psoriasis were randomized to the control group or to receive alefacept (7.5 mg intravenously weekly for 12 weeks). The alefacept group received PhiX174 immunizations at weeks 6, 12, 20, and 26 and tetanus toxoid at week 21; control subjects received PhiX174 at weeks 6 and 12 and tetanus at week 10.

RESULTS

Mean anti-PhiX174 titers were comparable in both groups. There was no difference in the percentage of responders (anti-PhiX174 IgG >/=30% of the total anti-PhiX174) between the alefacept group and the control group (86% and 82%, respectively; P =.73). The percentage of patients with anti-tetanus toxoid titer increases >/=2 times baseline also was similar (alefacept, 89%; control 91%).

CONCLUSION

A single 12-week course of alefacept did not impair primary or secondary antibody responses to a neoantigen or memory responses to a recall antigen. The selective immunomodulatory effect of alefacept against a potentially pathogenic T-cell subset is associated with maintenance of a significant aspect of immune function (antibody response) to fight infection and respond to vaccinations.

The role of T cells in psoriasis

Evidence for a key role of T cells in the pathogenesis of psoriasis has come from both experimental and clinical data. Initially, generalized immunosuppressants, intended for use in transplant settings, were found to improve clinical signs and symptoms of psoriasis. Their efficacy attracted attention to the activated T cells that are a major component of the inflammatory infiltrate of psoriatic lesions. Further research determined that T cells from patients with psoriasis could transmit disease in animal models. These findings laid the groundwork for characterizing the pathogenesis of psoriasis as immune mediated with skin-directed T cells playing a central role. Once these pathogenic T cells have entered the skin, they become activated and release cytokines and chemokines to attract other immune cells to perpetuate the inflammatory cascade. As the role of the T cell in psoriasis has evolved and understanding of immunopathology has increased, a multitude of biologic targets have been revealed. Newer strategies for the treatment of psoriasis have therefore focused on modifying T cells in this disease through direct elimination of activated T cells, inhibition of T-cell activation, or inhibition of cytokine secretion or activity. The mechanisms by which these new biologic agents act on psoriasis will affect their profile of efficacy and safety. Important selection criteria for optimal antipsoriatic therapies include long-term safety and tolerability, ability to produce long-lasting remissions, and convenient dosing regimens.

Biological response modifiers and their potential use in the treatment of inflammatory skin diseases

In recent years, a more detailed understanding of the pathogenesis of several inflammatory skin diseases, combined with the developments within biotechnology, has made it possible to design more selective response modifiers. Biological response modifiers hold the potential for greater effectiveness and fewer side-effects than the current systemic therapies now used for severe psoriasis, contact dermatitis and atopic dermatitis. In the pathogenesis of inflammatory skin diseases, the immune system plays a pivotal role, and this is where biological response modifiers such as monoclonal antibodies, recombinant cytokines, or fusion proteins may be effective. Several biological response modifiers have already shown positive results in phase II/III clinical trials in skin diseases, and many new biological response modifiers are in progress.

Pharmacokinetics, biologic activity, and tolerability of alefacept by intravenous and intramuscular administration

Alefacept, human LFA-3/IgG1 fusion protein, is currently under clinical development for the treatment of chronic plaque psoriasis and other T cell mediated disorders. This recombinant protein binds CD2 on T cells and Fc gamma RIII on accessory cells (e.g., natural killer cells, macrophages), inhibiting T cell activation/proliferation and inducing selective T cell apoptosis. These effects are associated with selective reductions in memory-effector (CD4+ CD45RO+ and CD8+ CD45RO+) T cells. Two open-label studies were conducted in healthy male volunteers to evaluate the pharmacokinetics, biologic activity, and tolerability of a single dose of alefacept when administered as a 0.15 mg/kg 30-sec i.v. bolus (n = 12), 0.04 mg/kg intramuscular (i.m.) injection (n = 8), or 0.04 mg/kg 30-min intravenous (i.v.) infusion (n = 8). i.v. infusion produced a higher Cmax (0.96 +/- 0.26 mcg/ml vs. 0.36 +/- 0.19 mcg/ml) and a shorter Tmax (2.8 +/- 1.9 hr vs. 86 +/- 60 hr) when compared to i.m. injection. Based on AUC0-last and AUC0-infenity values, the relative bioavailability of i.m. to i.v. infusion was approximately 60%. After absorption from the i.m. injection was complete, the rate of alefacept elimination from the serum appeared consistent with the i.v. infusion half-life (approximately 12 days). Biologic activity was demonstrated by transient reductions in absolute number of CD2+ lymphocytes, with notable specificity for memory T-cell subsets. Alefacept was well tolerated; the most common adverse effects were headache, pharyngitis, rash, and myalgia. IM administration was not associated with significant local reactions. Results of these studies support i.v. bolus or i.m. administration of alefacept. An i.m. dose of approximately 150 to 200% of the i.v. dose is an appropriate and convenient alternative to i.v. administration.

Severe periorbital edema secondary to STI571 (Gleevec)

STI571 (imatinib mesylate; Gleevec) is a selective inhibitor of the bcr-abl, c-kit, and platelet-derived growth factor receptor tyrosine kinases. Mild periorbital edema has been noted as a common side effect in Phase I and II trials of this drug for the treatment of patients with chronic myelogenous leukemia and gastrointestinal stromal tumors. The authors report the case of male patient age 63 years who developed severe periorbital edema after treatment with STI571 for chronic myelogenous leukemia. His edema was severe enough to cause visual obstruction due to lower eyelid festoons that ultimately required surgical debulking. Histopathologic analysis of specimens of the excised upper and lower eyelid tissue revealed dermal dendrocytes that expressed the platelet-derived growth factor receptor and c-kit tyrosine kinases, suggesting a possible role for dermal dendrocytes in the development of this toxic effect.

Treatment of chronic plaque psoriasis by selective targeting of memory effector T lymphocytes

BACKGROUND

Psoriatic plaques are characterized by infiltration with CD4+ CD45RO+ and CD8+ CD45RO+ memory effector T lymphocytes. The recombinant protein alefacept binds to CD2 on memory effector T lymphocytes, inhibiting their activation.

METHODS

In a multicenter, randomized, placebo-controlled, double-blind study, we evaluated alefacept as a treatment for psoriasis. Two hundred twenty-nine patients with chronic psoriasis received intravenous alefacept (0.025, 0.075, or 0.150 mg per kilogram of body weight) or placebo weekly for 12 weeks, with follow-up for 12 additional weeks. Before treatment, the median scores on the psoriasis area-and-severity index were between 14 and 20 in all groups (0 denotes no psoriasis and 72 the most severe disease possible).

RESULTS

Alefacept was well tolerated and nonimmunogenic. The mean reduction in the score on the psoriasis area-and-severity index two weeks after treatment was greater in the alefacept groups (38, 53, and 53 percent in the groups receiving 0.025, 0.075, and 0.150 mg per kilogram, respectively) than in the placebo group (21 percent, P<0.001). Twelve weeks after treatment, 28 patients who had received alefacept alone were clear or almost clear of psoriasis. Three patients in the placebo group were clear or almost clear; all three had received additional systemic therapy for psoriasis. Alefacept reduced peripheral-blood memory effector T-lymphocyte (CD45RO+) counts, and the reduction in the number of memory-effector T lymphocytes was correlated with the improvement in psoriasis.

CONCLUSIONS

Treatment with alefacept for 12 weeks is associated with improvement in chronic plaque psoriasis; some patients have a sustained clinical response after the cessation of treatment. Alefacept selectively targets CD45RO+ memory effector T lymphocytes, suggesting that they have a role in the pathogenesis of psoriasis.

Altered Expression of Angiopoietins and Tie2 Endothelium Receptor in Psoriasis

Psoriasis is a chronic inflammatory skin disease in which epidermal proliferation is closely associated with excessive microvascular expansion within the papillary dermis. Angiopoietins have recently been identified as the major ligands of the endothelial- specific receptor Tie2. Angiopoietin 1 induces Tie2 signaling as a receptor activator and maintains blood vessel formation, whereas angiopoietin 2 destabilizes vessels by blocking Tie2 signaling as an antagonist of angiopoietin 1 and acts with vascular endothelial growth factor to initiate angiogenesis. In this study we examined the potential role of angiopoietins and the Tie2 receptor in vascular changes of psoriasis. Angiopoietin 1, angiopoietin 2, and Tie2 were upregulated in involved psoriasis skin compared to uninvolved psoriasis skin, healthy skin, and chronic spongiotic dermatitis skin. Angiopoietin 1 was expressed by stromal cells in the highly vascularized papillary dermis of involved psoriasis skin. Angiopoietin 2 was expressed by endothelial cells in the vicinity of the proliferating epidermis that abundantly expressed vascular endothelial growth factor. Vascular endothelial growth factor and basic fibroblast growth factor, which were overexpressed in involved psoriasis skin, enhanced angiopoietin 2 and Tie2 expression in dermal microvascular endothelial cell cultures. Thus, our findings suggest that upregulation of angiopoietin 1, angiopoietin 2, and Tie2 is closely associated with the development of microvascular proliferation in psoriasis, and that the angiopoietin-Tie2 system may act coordinately with vascular endothelial growth factor and basic fibroblast growth factor to promote neovascularization in psoriasis. Moreover, successful antipsoriatic treatment was accompanied by noticeable reduction of angiopoietin 2 expression, suggesting that alteration of angiopoietin 2 expression may be particularly important in controlling vascular proliferation in the treatment of psoriasis.

Cytological alterations in dermal dendrocytes in vitro: evidence for transformation to a non-dendritic phenotype

Dermal dendrocytes (DDs) are bone marrow-derived cells which are abundant in normal human and murine dermis, where they are closely associated with mast cells in the perivascular space. The biological role of DDs remains enigmatic. DDs express coagulation factor XIIIa and the recently described von Willebrand factor receptor, GPIb alpha, potentially indicating a function in tissue repair and haemostasis, although participation in antigen presentation is also speculated. In healing wounds and 'fibrohistiocytic' tumours, such as dermatofibromas, DDs are often associated with non-dendritic histiocytes, some of which also express factor XIIIa (FXIIIa). We have utilized human skin organ culture to examine the effects of various biological mediators on cytological characteristics of DDs. It was found that by 24 h in organ culture, immunoreactive DDs begin to lose their dendritic shape, assuming more rounded contours. This phenomenon was accentuated by mast cell degranulation; was independent of the nature of mast cell secretagogue; and could not be reproduced by recombinant tumour necrosis factor-alpha, a cytokine known to increase FXIIIa expression in DDs. Like their dendritic precursors, non-dendritic cells expressed variable FXIIIa, CD34 and CD68 and did not express CD1a or CD45. By ultrastructure, non-dendritic cells that develop in vitro resembled non-degenerating monocytes containing occasional primary lysosomes and lipid inclusions, and like DDs, expressed fibronexus-like plaques on the cell membrane. Transition of DDs from dendritic to non-dendritic cells as a consequence of specific microenvironmental influences may provide insight into the frequent concurrence of these two cytological types in fibrohistiocytic tissue reactions and neoplasia.

T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response

Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiology of psoriasis. In order to gain insight into the nature of the antigen (superantigen or nominal protein antigen) involved in psoriatic lesions, we have used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chronic plaque-type psoriasis. Semi-quantitative analysis showed that no significant difference in V beta subfamily usage could be detected in T lymphocytes infiltrating lesional skin as compared to blood lymphocytes. Alternatively, determination of the size distribution of the CDR3 of all the V beta subfamilies revealed only in psoriatic skin a marked TCR oligoclonality defined by the presence in 3 to 5 V beta subfamilies of a single predominant CDR3 size which was associated with a unique V beta-J beta combination. Identical patterns of CDR3 length and V beta-J beta combination profiles were found in symetrical lesional sites from two psoriatic patients. This type of skewed CDR3 size profile is reminiscent of a local stimulation of T lymphocytes by nominal protein antigens. These data suggest that T lymphocytes infiltrating plaque-type psoriatic skin comprise expansions of oligoclonal T cells in response to stimulation by an antigen present in the skin.

Identification and quantitation of interferon-gamma producing T cells in psoriatic lesions: localization to both CD4+ and CD8+ subsets

Interferon-gamma (IFN-gamma) produced by lesional T cell clones is critical for the induction into G1 of the cell cycle by psoriatic keratinocyte stem cells; however, direct data demonstrating psoriatic lesional T cell subset IFN-gamma expression, and quantitation at a single cell level to calculate in vivo proportions, are lacking. In this study, using flow cytometry of freshly isolated normal and psoriatic lesional T cells from keratome biopsies, we found elevated CD3+, CD4+, and CD8+ T cells in all compartments of psoriatic skin, compared with normals. Using Brefeldin A to induce short-term intracellular accumulation of IFN-gamma in T cells capable of IFN-gamma production, we found that 90% of psoriatic patients have IFN-gamma-producing T cells at a greater proportion of their CD3+ cells than normals, with a mean of 16%+/-3%, as compared with 4%+/-2% in normal epidermis (p = 0.01). Expressed as density in the tissue, the IFN-gamma+ CD3+ cell number in psoriatic epidermis was 97+/-22 per mm2 surface area, as compared with 4.4+/-1.8 per mm2 of normal epidermis (p = 0.002). Thus, the total number of IFN-gamma+CD3+ T cells in the skin of a patient with 20% involvement is estimated to be 3.9 x 10(8). CD4+ and CD8+ IFN-gamma+ T cells were both elevated in psoriatic epidermis (p = 0.04 and p = 0.008, respectively) relative to normal skin. In the dermis, only 44% of patients demonstrated a higher percentage of IFN-gamma-producing T cells than did normals (p = 0.1), possibly indicating dilution, in some patients, by fresh infiltrating T cells. Interleukin-4 was not found by a combination of flow cytometry, reverse transcriptase-polymerase chain reaction, western blot, and immunoprecipitation. In conclusion, a significant portion of lesional T cells in psoriasis are IFN-gamma producing, without interleukin-4. The increased numbers of both IFN-gamma+CD4+ and IFN-gamma+CD8+ T cells indicate that both CD4+ and CD8+ IFN-gamma+ T cells are present in appropriate anatomic locations to sustain the lesional pathology.

Factor XIII insufficiency in a patient with severe psoriasis vulgaris, arthritis, and infirmity

Factor XIII (FXIII) links soluble fibrin monomers and collagen fibres to stable fibrin connections. Deficiency of FXIII, caused by dyspoiesis or increased consumption, results in a bleeding tendency and wound healing complications. Although the decrease of FXIII and successful replacement in patients with wound healing complications after surgery have been described by several authors, it is rarely considered that patients with autoimmune diseases, bleeding or healing complications may suffer from FXIII deficiency. We report a patient with severe psoriasis vulgaris generalisata with large, painful erythemas, bleeding tendency, joint contractions and infirmity, whose FXIII activity was 19%. After successful replacement the bleeding tendency vanished, and a marked improvement of skin and joint mobility allowed mobilisation and administration of physical therapy, whereby some independence and mobility were restored to the patient.

Linkage analysis of human leukocyte antigen (HLA) markers in familial psoriasis: strong disequilibrium effects provide evidence for a major determinant in the HLA-B/-C region

Although psoriasis is strongly associated with certain human leukocyte antigens (HLAs), evidence for linkage to HLA markers has been limited. The objectives of this study were (1) to provide more definitive evidence for linkage of psoriasis to HLA markers in multiplex families; (2) to compare the major HLA risk alleles in these families with those determined by previous case-control studies; and (3) to localize the gene more precisely. By applying the transmission/disequilibrium test (TDT) and parametric linkage analysis, we found evidence for linkage of psoriasis to HLA-C, -B, -DR, and -DQ, with HLA-B and -C yielding the most-significant results. Linkage was detectable by parametric methods only when marker-trait disequilibrium was considered. Case-control association tests and the TDT identified alleles belonging to the EH57.1 ancestral haplotype as the major risk alleles in our sample. Among individuals carrying recombinant ancestral haplotypes involving EH57. 1, the class I markers were retained selectively among affecteds four times more often than among unaffecteds; among the few affected individuals carrying only the class II alleles from the ancestral haplotype, all but one also carried Cw6. These data show that familial and "sporadic" psoriasis share the same risk alleles. They also illustrate that substantial parametric linkage information can be extracted by accounting for linkage disequilibrium. Finally, they strongly suggest that a major susceptibility gene resides near HLA-C.

Epitope spreading: lessons from autoimmune skin diseases

Autoimmune diseases are initiated when patients develop aberrant T and/or B cell responses against self proteins. These responses presumably are directed to single immunogenic epitopes on these proteins. Recent data in animal models of autoimmune diseases suggest that the targets of immune responses in autoimmunity do not remain fixed, but can be extended to include other epitopes on the same protein or other proteins in the same tissue, a phenomenon termed "epitope spreading." The "epitope spreading" phenomenon also applies to situations in which tissue damage from a primary inflammatory process causes the release and exposure of a previously "sequestered" antigen, leading to a secondary autoimmune response against the newly released antigen. In experimental autoimmune animal diseases, "epitope spreading" seems to have significant physiologic importance in determining the course and duration of disease. In this paper, we review the current concepts in animal models of autoimmune diseases in order to define the "epitope spreading" phenomenon, and we then propose how this phenomenon might play a significant role in the development and the course of autoimmune skin diseases. Hopefully, an understanding of "epitope spreading" will help the dermatology community to better understand the pathogenesis of autoimmune skin diseases and to rationally fashion disease-specific immune therapy in the future.