The immunologic basis for the treatment of psoriasis with new biologic agents

Fumaric acid esters in the treatment of psoriasis: an Italian experience

BACKGROUND

Psoriasis is a common, chronic, cell-mediated, inflammatory skin disease. Treatment limitations and a developing understanding of its pathogenesis on a molecular level have encouraged much interest in the field of immunomodulatory therapy.

OBJECTIVE

To evaluate the efficacy and safety of fumaric acid esters, in particular dimethylfumarate (DMF), in the treatment of moderate to severe plaque psoriasis intolerant and/or resistant to other conventional systemic therapies.

METHODS

A total of 40 patients were enrolled in this study. DMF was orally administered at the daily dose of 30 mg up to 360 mg for a minimum of 6 months treatment. Patients were followed-up with psoriasis area and severity index (PASI) score assessment, and clinical and photographic documentation.

RESULTS

A total of 33 (82.5%) patients achieved complete clinical remission with DMF treatment: eight after 3 months and 25 after 6 months. Adverse events, such as intolerable abdominal cramps and incoercible diarrhoea, occurred in four patients who, for this reason, interrupted therapy.

CONCLUSION

The findings suggest that DMF is a safe, effective and well-tolerated long-term oral treatment worthy of consideration for selective patients.

The effect of the combination of calcipotriol and betamethasone dipropionate versus both monotherapies on epidermal proliferation, keratinization and T-cell subsets in chronic plaque psoriasis

Several reports have indicated that the combination of calcipotriol ointment and potent or ultrapotent corticosteroids are more effective and better tolerated, as compared to the monotherapies. The aim of the present study was to find out the effect of combination of calcipotriol ointment once daily and betamethasone dipropionate ointment once daily vs. the effect of twice-daily applications of each of the two treatments as monotherapy during a four-week treatment period. Seven patients with chronic plaque psoriasis were included for treatment with the three treatment schedules. Biopsies were taken before treatment and after four weeks of treatment, and markers for epidermal proliferation (Ki-67) and epidermal differentiation (keratin-10) were studied using a quantitative image analysis, and T-cell subsets in epidermis and dermis (CD4, CD8, CD25, CD45RO, CD45RA, CD94, CD161, and CD2) were studied using immunohistochemical scoring. The most impressive clinical result was reached with the combination. Calcipotriol proved to have a major effect on the proliferation marker Ki-67 and differentiation marker keratin-10, whereas the effect on T-cell subsets was more selective with major reductions of CD45RO(+) and CD8(+) T cells. In contrast, the effect of betamethasone dipropionate on the epidermis was restricted to a normalization of differentiation with a highly significant increase of keratin-10 positive epidermal surface without a significant effect on Ki-67 positive nuclei, and the effect on T-cell subsets was restricted to a reduction of natural killer T-cell receptors designated by CD94 and CD161 in the epidermis. The combination of the two treatments did not affect the proliferation marker Ki-67 and keratinization marker keratin-10, beyond the effect of calcipotriol monotherapy. However, the combination had a profound effect on, virtually, all T-cell subsets, beyond the effect of the monotherapies. It is concluded that the action spectra of calcipotriol and betamethasone on the psoriatic plaque are different and that the combination has effects on T-cell subsets, beyond the addition of the effects of monotherapies.

Psoriasis genomics: analysis of proinflammatory (type 1) gene expression in large plaque (Western) and small plaque (Asian) psoriasis vulgaris

BACKGROUND

Type 1 T cells are hypothesized to be central in the immunopathogenesis of psoriasis. Through elaboration of interferon (IFN)-gamma, type 1 T cells regulate the expression of many 'downstream' inflammatory genes, including an array of chemokines that regulate leucocyte trafficking and activation in skin lesions. Accordingly, disease progression and/or severity might be controlled by the degree to which differing cytokines and chemokines are overexpressed in focal skin regions. To examine this possibility, we studied two forms of chronic psoriasis vulgaris that differ significantly in overall severity and progression: small plaque (SP) psoriasis occurring in Korean patients, and large plaque (LP) psoriasis occurring in North American patients.

OBJECTIVES

To characterize LP and SP psoriasis vulgaris with respect to expression of proinflammatory genes that define the type 1 T-cell axis in skin lesions [genes encoding interleukin (IL)-12, IFN-gamma, and IFN-gamma-regulated chemokines or inflammatory mediators].

METHODS

Total cellular RNA of skin samples from groups of patients with LP or SP psoriasis was analysed by quantitative reverse transcription-polymerase chain reaction (TaqMan analysis) to compare the differences in mRNA expression of genes related to the IFN-gamma pathway.

RESULTS

The mRNA expression of keratin 16, CD25, IFN-gamma, IL-12 p40, signal transducer and activator of transcription-1, inducible nitric oxide synthase, IL-8, macrophage inflammatory protein-3alpha, monocyte chemoattractant protein-1, S100A12, IFN-gamma-inducible protein of 10 kDa, IFN-inducible T-cell alpha-chemoattractant and monokine induced by IFN-gamma was increased in the lesions of both LP psoriasis and SP psoriasis. However, IL-18 mRNA expression was significantly different in the lesions of LP psoriasis in comparison with those of SP psoriasis.

CONCLUSIONS

The results indicate that proinflammatory type 1 genes regulated by IFN-gamma are similarly increased in both SP and LP psoriasis, but a potential difference in IL-18 exists between these disease forms. The consistent activation of this set of genes argues for a central role of IFN-gamma as a molecular regulator of inflammation in these distinct subtypes of psoriasis vulgaris. In contrast, disease extent/severity must be controlled by yet other factors.

Micellar paclitaxel improves severe psoriasis in a prospective phase II pilot study

BACKGROUND

Taxanes (eg, paclitaxel) are chemotherapeutic agents that have antiproliferative, antiangiogenic, and antiinflammatory properties.

OBJECTIVE

We sought to explore the safety and efficacy of paclitaxel in individuals with severe psoriasis.

METHODS

An open-label, prospective, phase II pilot study was conducted at the National Institutes of Health Clinical Center, a federal government medical research facility, in Bethesda, Maryland. Twelve patients with severe psoriasis, as defined by a baseline Psoriasis Area and Severity Index (PASI) score of >or= 20), were studied. Initially, patients received 6 intravenous infusions of micellar paclitaxel, 75 mg/m(2), at 4-week intervals (stage I). Later patients received 9 intravenous infusions of micellar paclitaxel at 2-week intervals (37.5 mg/m(2) for 3 doses followed by 50 mg/m(2) for six additional doses) (stage II). The primary end point was the percent change in the PASI from week 0 to week 24 in stage I and from week 0 to week 20 in stage II.

RESULTS

In stage I, all 5 patients improved (mean = 59.7% decrease in PASI, median = 59.6%, range: 40.3%-79.2%). Four of the 7 patients completed stage II and all of these patients improved (mean = 45.9% decrease in PASI, median = 45.0%, range: 14.6%-79.1%). Micellar paclitaxel was well tolerated by most patients.

CONCLUSIONS

Micellar paclitaxel demonstrates therapeutic activity in patients with severe psoriasis.

The efficacy of topical tazarotene monotherapy and combination therapies in psoriasis

Tazarotene (Tazorac, Allergan, Inc.) is the first topical retinoid approved for the treatment of plaque psoriasis. It has a similar onset of action compared to potent topical steroids and has the advantage of a longer remission. The common side effects associated with the drug include skin irritation (including pruritus), erythema and a burning sensation. To overcome some of these shortcomings, it has been used in combination with steroids, calcipotriene and phototherapy. Combination therapy not only results in a decrease in adverse side effects, but also enhanced efficacy. Clinical study data have shown that combination therapy is just as important as tazarotene monotherapy, if not more.

CD4+ T cell-associated pathophysiology critically depends on CD18 gene dose effects in a murine model of psoriasis

In a CD18 hypomorphic polygenic PL/J mouse model, the severe reduction of CD18 (beta(2) integrin) to 2-16% of wild-type levels leads to the development of a psoriasiform skin disease. In this study, we analyzed the influence of reduced CD18 gene expression on T cell function, and its contribution to the pathogenesis of this disease. Both CD4(+) and CD8(+) T cells were significantly increased in the skin of affected CD18 hypomorphic mice. But only depletion of CD4(+) T cells, and not the removal of CD8(+) T cells, resulted in a complete clearance of the psoriasiform dermatitis. This indicates a central role of CD4(+) T cells in the pathogenesis of this disorder, further supported by the detection of several Th1-like cytokines released predominantly by CD4(+) T cells. In contrast to the CD18 hypomorphic mice, CD18 null mutants of the same strain did not develop the psoriasiform dermatitis. This is in part due to a lack of T cell emigration from dermal blood vessels, as experimental allergic contact dermatitis could be induced in CD18 hypomorphic and wild-type mice, but not in CD18 null mutants. Hence, 2-16% of CD18 gene expression is obviously sufficient for T cell emigration driving the inflammatory phenotype in CD18 hypomorphic mice. Our data suggest that the pathogenic involvement of CD4(+) T cells depends on a gene dose effect with a reduced expression of the CD18 protein in PL/J mice. This murine inflammatory skin model may also have relevance for human polygenic inflammatory diseases.

Spontaneous development of psoriasis in a new animal model shows an essential role for resident T cells and tumor necrosis factor-alpha

Psoriasis is a common T cell-mediated autoimmune disorder where primary onset of skin lesions is followed by chronic relapses. Progress in defining the mechanism for initiation of pathological events has been hampered by the lack of a relevant experimental model in which psoriasis develops spontaneously. We present a new animal model in which skin lesions spontaneously developed when symptomless prepsoriatic human skin was engrafted onto AGR129 mice, deficient in type I and type II interferon receptors and for the recombination activating gene 2. Upon engraftment, resident human T cells in prepsoriatic skin underwent local proliferation. T cell proliferation was crucial for development of a psoriatic phenotype because blocking of T cells led to inhibition of psoriasis development. Tumor necrosis factor-alpha was a key regulator of local T cell proliferation and subsequent disease development. Our observations highlight the importance of resident T cells in the context of lesional tumor necrosis factor-alpha production during development of a psoriatic lesion. These findings underline the importance of resident immune cells in psoriasis and will have implications for new therapeutic strategies for psoriasis and other T cell-mediated diseases.

A novel targeted T-cell modulator, efalizumab, for plaque psoriasis

BACKGROUND

Interactions between leukocyte-function-associated antigen type 1 (LFA-1) and intercellular adhesion molecules are important in the pathogenesis of psoriasis. Efalizumab, a humanized monoclonal antibody, binds to the alpha subunit (CD11a) of LFA-1 and inhibits the activation of T cells.

METHODS

In a phase 3, multicenter, randomized, placebo-controlled, double-blind study, we assign 597 subjects with psoriasis to receive subcutaneous efalizumab (1 or 2 mg per kilogram of body weight per week) or placebo for 12 weeks. Depending on the response after 12 weeks, subjects received an additional 12 weeks of treatment with efalizumab or placebo. Study treatments were discontinued at week 24, and subjects were followed for an additional 12 weeks.

RESULTS

At week 12, there was an improvement of 75 percent or more in the psoriasis area-and-severity index in 22 percent of the subjects who had received 1 mg of efalizumab per kilogram per week and 28 percent of those who had received 2 mg of efalizumab per kilogram per week, as compared with 5 percent of the subjects in the placebo group (P<0.001 for both comparisons). Efalizumab-treated subjects had greater improvement than those in the placebo group as early as week 4 (P<0.001). Among the efalizumab-treated subjects who had an improvement of 75 percent or more at week 12, improvement was maintained through week 24 in 77 percent of those who continued to receive efalizumab, as compared with 20 percent of those who were switched to placebo (P<0.001 for both comparisons). After the discontinuation of efalizumab at week 24, an improvement of 50 percent or more in the psoriasis area-and-severity index was maintained in approximately 30 percent of subjects during the 12 weeks of follow-up. Efalizumab was well tolerated, and adverse events were generally mild to moderate.

CONCLUSIONS

Efalizumab therapy resulted in significant improvements in plaque psoriasis in subjects with moderate-to-severe disease. Extending treatment from 12 to 24 weeks resulted in both maintenance and improvement of responses.

Etanercept as monotherapy in patients with psoriasis

BACKGROUND

Inflammatory cytokines such as tumor necrosis factor (TNF) have been implicated in the pathogenesis of psoriasis. We evaluated the safety and efficacy of etanercept, a TNF antagonist, for the treatment of plaque psoriasis.

METHODS

In this 24-week, double-blind study, 672 patients underwent randomization and 652 either received placebo or received etanercept subcutaneously at a low dose (25 mg once weekly), a medium dose (25 mg twice weekly), or a high dose (50 mg twice weekly). After 12 weeks, patients in the placebo group began twice-weekly treatment with 25 mg of etanercept. The primary measure of clinical response was the psoriasis area-and-severity index.

RESULTS

At week 12, there was an improvement from base line of 75 percent or more in the psoriasis area-and-severity index in 4 percent of the patients in the placebo group, as compared with 14 percent of those in the low-dose--etanercept group, 34 percent in the medium-dose--etanercept group, and 49 percent in the high-dose-etanercept group (P<0.001 for all three comparisons with the placebo group). The clinical responses continued to improve with longer treatment. At week 24, there was at least a 75 percent improvement in the psoriasis area-and-severity index in 25 percent of the patients in the low-dose group, 44 percent of those in the medium-dose group, and 59 percent in the high-dose group. The responses as measured by improvements in the psoriasis area-and-severity index were paralleled by improvements in global assessments by physicians and the patients and in quality-of-life measures. Etanercept was generally well tolerated.

CONCLUSIONS

The treatment of psoriasis with etanercept led to a significant reduction in the severity of disease over a period of 24 weeks.

Therapy of alopecia areata: on the cusp and in the future

Over the past decade, basic research has established alopecia areata as a T cell-mediated autoimmune disease and has clarified many of its genetic, cellular, and molecular aspects. Perifollicular and intrafollicular mononuclear cell infiltrates directed at anagen hair bulbs are characteristic and striking histologic features in early alopecia areata. The inflammatory infiltrate is composed predominantly of activated CD4+ and CD8+ T cells, together with macrophages and Langerhans cells. The initiation phase of alopecia areata is mediated by type 1 cytokines, including interleukin-2, interferon-gamma, and tumor necrosis factor-alpha. Like other diseases with a strong autoimmune component, alopecia areata has associated with it specific human leukocyte antigens, which determine susceptibility, severity, chronicity, and resistance. New topical immunomodulating drugs and biologic therapies that have been developed, or that are in development, for the treatment of other immune-mediated inflammatory skin diseases will likely be effective in alopecia areata as well. The present discussion addresses the treatment of alopecia areata within the framework of these new modalities.

Systemic therapies for psoriasis: understanding current and newly emerging therapies

The treatment of moderate to severe psoriasis is a rapidly expanding area. Recent insights into the pathogenesis of this disease as a T-cell mediated process has led to a greater understanding of the mechanisms of action of conventional FDA-approved systemic therapies such as methotrexate, cyclosporine, acitretin, and psoralen with ultraviolet A phototherapy. It has also led to the development of rationally targeted therapies against key components of the immune process critical in the generation of the psoriatic plaque. Safety and efficacy data from clinical studies of 4 biologic agents furthest along in their development are reviewed. These results are promising, adding to the armamentarium for treating this disease.

Nicotinamide: a potential addition to the anti-psoriatic weaponry

Psoriasis is an inflammatory disorder characterized by a T helper type 1 cell cytokine pattern. Increased expression of adhesion molecules, prominent neutrophil accumulation, and increased production of nitric oxide are characteristics of this disorder. Moreover, histamine and proteases are supposed to participate in the pathogenesis of psoriasis. Nicotinamide is an inhibitor of poly (ADP-ribose) polymerase-1 (PARP-1) that, through enhancement of nuclear kappa B-mediated transcription, plays a pivotal role in the expression of inflammatory cytokines, chemokines, adhesion molecules, and inflammatory mediators. Through interaction with CD38 and inhibition of IL-1, IL-12, and TNF-alpha production, nicotinamide produces a mild TH2 bias. Nicotinamide is a potent phosphodiesterase inhibitor and suppresses neutrophil chemotaxis and mast cell histamine release. It inhibits nitric oxide synthase mRNA induction and suppresses antigen-induced lymphocyte transformation. Nicotinamide increases the biosynthesis of ceramides, which upon degradation produce sphingosine. Sphingosine inhibits protein kinase C (PKC) and decreases basal cell proliferation dependent on PKC. Taken together, it can be reasoned that nicotinamide could be a useful addition to anti-psoriatic armamentarium. The combination of nicotinamide and thalidomide or methotrexate provided a powerful synergistic inhibition of murine collagen-induced arthritis. Nicotinamide decreased the methotrexate-induced hepatotoxicity. The above combinations may prove to have a powerful anti-psoriatic effect as well. As PARP inhibitors could exert anti-retroviral effect, nicotinamide could also be of special value in the treatment of HIV-infected psoriatics.

Etanercept: An overview

Etanercept, a competitive inhibitor of TNF-alpha, is currently FDA approved for psoriatic arthritis and rheumatoid arthritis. The molecular structure of etanercept, its mechanism of action, and results of clinical trials involving patients with psoriasis will be reviewed.

Efalizumab: an overview

Efalizumab (anti-CD11a), a targeted T cell modulator, is a humanized monoclonal antibody being studied for plaque psoriasis. Phase I and II studies demonstrated that efalizumab treatment results in histologic improvement and clinical benefit in patients with moderate to severe disease. Phase III clinical trials confirmed the clinical activity and safety of weekly efalizumab. Efalizumab is associated with a rapid onset of clinical benefit, with significant improvements observed as early as 4 weeks. Extending treatment from 12 to 24 weeks both maintains and improves the initial responses achieved at 12 weeks. Both 12 and 24 weeks of efalizumab therapy were generally well tolerated. Ongoing studies are being conducted to further define the optimal dosing and administration schedules for efalizumab in patients with moderate to severe plaque psoriasis.

Aberrant signalling and transcription factor activation as an explanation for the defective growth control and differentiation of keratinocytes in psoriasis: a hypothesis

Psoriasis is a chronic inflammatory skin disease characterized by the accumulation of red, scaly plaques on the skin. The plaques result from hyperproliferation and incomplete differentiation of keratinocytes (KC) in a process that seems to be driven, in part by skin-infiltrating leucocytes. We believe that the KC have inherent defects in intracellular signalling which could be usefully targeted to allow the development of more effective therapies. We suggest that there are defects in the regulation of the transcription factors: signal transducer and activator of transcription (STAT-1alpha), interferon regulated factor-1 (IRF-1) and NFkappaB which lead to loss of growth and differentiation control when the cells are subjected to physico-chemical and immunological stress. We also highlight recent studies that suggest that peroxisome proliferator-activated receptors, the notch receptor and defects in calcium and other ion transporting proteins may contribute to impairment in the ability of psoriatic KC to differentiate. The role of these systems in the development of the psoriatic phenotype and tests of these hypotheses are proposed.

Clinical response to alefacept: results of a phase 3 study of intravenous administration of alefacept in patients with chronic plaque psoriasis

BACKGROUND

There is a current lack of safe and effective psoriasis therapies that provide patients with lasting remissions after treatment is discontinued. Alefacept, a novel and selective biological agent, has demonstrated durable efficacy in patients with chronic plaque psoriasis, and its efficacy has been correlated with reductions in memory-effector T cells.

OBJECTIVE

To demonstrate the efficacy and safety of both one and two 12-week courses of alefacept 7.5 mg given once weekly as an intravenous (IV) bolus injection in patients with chronic plaque psoriasis.

METHODS

Multicentre (51 centres in the USA and Canada), randomized, double-blind, parallel-group study comparing once-weekly alefacept 7.5 mg IV or placebo for two 12-week treatment courses. Each course had a 12-week follow-up phase. Patients were eligible for enrollment if they were > or =16 years of age, had chronic plaque psoriasis for > or =12 months involving > or =10% body surface area, and had CD4+ T-cell counts at or above the lower limit of normal.

RESULTS

553 patients received treatment in Course 1, and 449 were treated in Course 2. The cohorts were well balanced for demographic and baseline disease characteristics. During the treatment and follow-up period of Course 1, 28% of patients treated with alefacept achieved > or =75% reduction in Psoriasis Area and Severity Index (PASI), compared with 8% of placebo-treated patients (P < 0.001). Patients achieving > or =75% reduction in PASI following a single 12-week course of alefacept maintained > or =50% reduction in PASI for a median of over 7 months. Among patients who received a second course of alefacept therapy, 71% achieved > or =50% reduction in PASI, and 40% achieved > or =75% reduction in PASI over two treatment courses. One or two 12-week courses of alefacept were similarly well tolerated.

CONCLUSIONS

Treatment with alefacept 7.5 mg IV provided highly significant improvements in all measures of psoriasis disease activity compared with placebo. A second course of alefacept provided additional benefit.

Novel biological immunotherapies for psoriasis

Psoriasis is a common skin disease affecting 1 - 3% of the white population. Although its physiopathogenesis still remains poorly understood, recent data suggest a key role played by memory T cells in the genesis of skin and joint lesions. Recent developments in the understanding of cellular mechanisms underlying psoriasis and in biotechnologies have given rise to a generation of biological agents that have shown clinical efficacy in treating psoriasis. These agents, including chimeric antibodies, fusion proteins and recombinant interleukins, specifically target the activated memory T cells directly involved in the development of psoriasis lesions and inhibit their action either directly or through inhibition of pro-inflammatory cytokines. Compared with conventional systemic treatments, they show a better safety profile and allow durable remissions. Some of these agents were very recently marketed for the treatment of psoriasis and hopefully others will follow. These biologicals have opened a new era for the management of this disease; they are reviewed in this article, based on data available in the literature.

Clinical response to alefacept: results of a phase 3 study of intramuscular administration of alefacept in patients with chronic plaque psoriasis

BACKGROUND

Recognition of psoriasis as a T-cell-mediated immune disease has led to the development of various therapeutic approaches directed against the pathogenic T cells. Alefacept, a novel and selective biological recombinant protein, binds CD2 on T cells to block T-cell activation and proliferation and interacts with FcgammaRIII receptors on accessory cells to produce selective T-cell apoptosis.

OBJECTIVE

To demonstrate the efficacy and safety of once-weekly alefacept IM compared with placebo given for 12 weeks to patients with chronic plaque psoriasis.

METHODS

Multicentre (63 sites in Europe, the USA, and Canada), randomized, double-blind, parallel-group study comparing 10 mg and 15 mg of alefacept and placebo administered IM once weekly for 12 weeks. Patients were followed for an additional 12 weeks after cessation of therapy. Patients were eligible for enrollment if they were > or = 18 years of age, had chronic plaque psoriasis for > or = 12 months involving > or = 10% body surface area, and had CD4+ T-cell counts at or above the lower limit of normal.

RESULTS

507 patients were enrolled into three treatment groups, which were well balanced for demographic, baseline disease characteristics, and treatment history. A significantly greater percentage of patients treated with alefacept 15 mg IM achieved > or = 75% PASI reduction from baseline 2 weeks after the last dose compared with placebo (21% vs. 5%, P < 0.001); 12% of patients treated with alefacept 10 mg IM reached this level of improvement (P = NS vs. placebo). Alefacept was well tolerated, with adverse events similar to that of placebo.

CONCLUSIONS

Treatment with alefacept 15 mg IM provided highly significant improvements in all measures of psoriasis disease activity compared with placebo. Pharmacodynamic data confirmed that alefacept is a selective biological agent that reduces memory-effector T cells (CD4+CD45RO+ and CD8+CD45RO+), the source of the pathogenic mediators of psoriasis, while having relatively no effect on naive T-cell populations.

Nukleäre Hormonrezeptoren: Interventionsmöglichkeiten jenseits von Glukokortikoiden, Retinoiden und Vitamin D

Nuclear hormone receptors are ligand-dependent transcription factors. The class of nuclear hormone receptors that form heterodimers with retinoid X receptor includes members that are well established targets of current dermatological therapeutics such as the retinoic acid receptor (RAR) and the vitamin D receptor (VDR) as well as more recently discovered receptors including the peroxisome proliferator-activated receptors (PPAR) and the liver X receptor (LXR). After ligand activation (often lipid metabolites), these intracellular receptors exert their functions by binding to specific response elements in regulatory sequences of target genes, preferentially those involved in differentiation, energy expenditure and lipid metabolism. A number of selective activators has been developed by combinational chemistry, initially for their anti-diabetic and lipid lowering properties as well as their ability to regulate bile acid and drug metabolism. However, these activators also have marked effects on cutaneous homeostasis. Therefore, these compounds have important implications for dermatological therapy. In this review, the clinical implications of the more recently discovered members of the nuclear hormone receptor family are discussed.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Genetic basis of psoriasis vulgaris and its pharmacogenetic potential

Psoriasis vulgaris is one of the most prevalent T cell-mediated inflammatory diseases in humans. It is multifactorial in origin and shows polygenic inheritance. Systemic immunosuppressive therapies play an important role in management of severe disease cases but are associated with variable response and toxicity. Within the last decade there have been significant advances in our understanding of the genetic basis of this complex disease and polymorphic candidate genes have been proposed. Susceptibility gene characterization together with an explosion in knowledge of its primary immune basis will further define disease pathways involved in psoriasis pathogenesis. This holds the promise of rational design of new therapeutic agents and pharmacogenetic testing to predict responders from non-responders and those at risk of toxicity.

Psoriasis

Recent breakthroughs in the treatment of psoriasis have led to improved understanding of the pathogenesis of this disease. Activation of T lymphocytes leading to release of cytokines results in proliferation of keratinocytes. Several new biological therapies have been developed, which target specific steps in the pathogenesis of psoriasis. With these new treatments, variable degrees of clearing occur. Initial data suggest improved safety over older agents such as methotrexate and ciclosporin, but long-term data are necessary. Enhancements in topical therapy and phototherapy have also increased the armamentarium of treatments available for this disorder.

Modulating T cell responses for the treatment of psoriasis: a focus on efalizumab

An improved understanding regarding the pathophysiology of psoriasis, coupled with advances in molecular research, has prompted the development of targeted biologic treatments for patients with plaque psoriasis. T lymphocytes play an important role in initiating the immune system and the inflammatory responses that result in the development and maintenance of psoriatic plaques. Efalizumab (anti-CD11a, Raptiva; Genentech, Inc.) is a mAb that targets the T cell adhesion molecule, leukocyte function-associated antigen-1 (LFA-1). By binding to CD11a - the alpha-subunit of LFA-1 - LFA-1 is prevented from binding with its ligand, intercellular adhesion molecule-1 (ICAM-1). This inhibits various T cell processes believed to be important in the pathogenesis of psoriasis, including T cell activation, T cell adhesion to endothelial cells and T cell migration. Clinical trials demonstrate that efalizumab, given subcutaneously once-weekly, provides clinical benefit, including improved quality of life, in patients with moderate-to-severe plaque psoriasis. Efalizumab is associated with an early onset of action, with improvement noted as early as 14 days. Studies with extended treatment suggest that continuing efalizumab therapy is more beneficial in maintaining and improving responses. Relapse of psoriasis is usually seen within 60 - 70 days after discontinuation of therapy, and rebound in approximately 5% of patients (i.e., flare to > 125% of baseline) is noted. Efalizumab is associated with acute adverse events during the first and second injections, which decrease in incidence with each subsequent injection. Data indicate that efalizumab can be safely administered for extended periods of time. Given the efficacy, early onset of clinical benefit, the safety profile and the convenience of once-weekly subcutaneous home dosing, efalizumab offers an interesting new therapeutic option for the treatment of psoriasis and the potential for improved and potentially safer long-term, continuous 'maintenance' therapy.

Novel mechanisms of T-cell and dendritic cell activation revealed by profiling of psoriasis on the 63,100-element oligonucleotide array

A global picture of gene expression in the common immune-mediated skin disease, psoriasis, was obtained by interrogating the full set of Affymetrix GeneChips with psoriatic and control skin samples. We identified 1,338 genes with potential roles in psoriasis pathogenesis/maintenance and revealed many perturbed biological processes. A novel method for identifying transcription factor binding sites was also developed and applied to this dataset. Many of the identified sites are known to be involved in immune response and proliferation. An in-depth study of immune system genes revealed the presence of many regulating cytokines and chemokines within involved skin, and markers of dendritic cell (DC) activation in uninvolved skin. The combination of many CCR7+ T cells, DCs, and regulating chemokines in psoriatic lesions, together with the detection of DC activation markers in nonlesional skin, strongly suggests that the spatial organization of T cells and DCs could sustain chronic T-cell activation and persistence within focal skin regions.

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.

Practical management of psoriasis in the elderly: epidemiology, clinical aspects, quality of life, patient education and treatment options

Psoriasis in the elderly will constitute a significant challenge for the practising physician in this new millennium. Special considerations for the elderly include drug-induced or drug-aggravated psoriasis, especially for patients receiving polypharmacy or with recent worsening or poor response to conventional therapy. Other frequently encountered forms of psoriasis in the elderly include psoriatic arthritis and its complications, inverse psoriasis and potentially life-threatening complications such as erythrodermic or acute pustular psoriasis, where early recognition and systemic therapy is critical. Faced with an array of topical and systemic drug therapy options, it is of paramount importance that the physician remains focused on the holistic management of the patient, in order to achieve optimal compliance and benefit. This can be achieved through careful attention to quality-of-life issues, especially since many elderly patients may have other medical, social and economic comorbidities that can further negatively affect their overall quality of life. It is also essential that the severity of psoriasis be assessed on a more balanced, holistic scale that incorporates both physical and psychological parameters, such as the Salford Psoriasis Index. The patient and caregiver education should be multi-faceted, regularly conducted and practically orientated. Treatment goals should be kept simple and individualised for each patient, based on concomitant comorbidities, potential adverse effects, existing quality of life, self-care capability, drug history, caregiver situation, financial needs, feasibility for follow-up and patient's preferences. Topically applied medications, such as topical corticosteroids, salicylic acid, tar and dithranol preparations, calcipotriol and tazarotene, are the favoured first-line therapeutic options in the elderly. Narrowband ultraviolet B phototherapy is also well established as a standard therapy for psoriasis. Systemic therapy with agents such as methotrexate, acitretin and cyclosporin should be judiciously reserved for severe, extensive cases in view of their lower therapeutic index in the elderly. The ambulatory psoriasis treatment centre is an integral part of the overall cost-effective management of patients with psoriasis that can function as a 'one-stop' treatment and resource centre for the elderly patient.

Serum levels of interleukin-18 and s-ICAM-1 in patients affected by psoriasis: preliminary considerations

OBJECTIVE

To find new aspects of the systemic involvement of the Immune System in psoriasis, we determined serum levels of interleukin-18 (IL-18) (Th1-inducing factor cytokine), CD30 (Th2 marker) and sICAM-1 (adhesion molecule). In addition we evaluated the correlation between these molecules and psoriasis area and severity index (PASI).

BACKGROUND

Psoriasis is associated to an overexpression of Th1 cytokines and a relative underexpression of Th2 cytokines. IL-18 plays an important role in inducing Th1 response because it is a potent inductor of synthesis of IFN-gamma, TNF and other mediators. The two major sources of IL-18 are monocytes and macrophages but also human keratinocytes constitutively synthesized IL-18.

SUBJECTS AND METHODS

We selected two groups of subjects: 16 healthy donors (HD) and 16 patients affected by psoriasis, matched for sex and age. Serum IL-18, CD30 and sICAM-1 levels were assayed by immunoenzymatic method with commercial kits.

RESULTS

IL-18 and sICAM-1 levels in the patients were significantly higher than in the HDs (385.94 +/- 193.89 vs. 227.38 +/- 92.76 pg/mL, P = 0.005 and 445.00 +/- 152.67 vs. 317.88 +/- 107.20 ng/mL, P = 0.02, respectively). On the contrary, no significant difference was found between serum sCD30 levels of patients in respect to those of HDs. A significant correlation was found between serum IL-18 and PASI (Rho = 0.695, P = 0.0071), serum IL-18 and sICAM-1 (Rho = 0.543, P = 0.0356) and between sICAM-1 and PASI (Rho = 0.659, P = 0.0107).