The tumour necrosis factor-alpha inhibitor adalimumab rapidly reverses the decrease in epidermal Langerhans cell density in psoriatic plaques

The Experimental Animal Models in Psoriasis Research: A Comprehensive Review

Psoriasis is an autoimmune, chronic, inflammatory skin condition mediated by T cells. It differs from other inflammatory conditions by causing significant alterations in epidermal cell proliferation and differentiation that are both complicated and prominent. The lack of an appropriate animal model has significantly hindered studies into the pathogenic mechanisms of psoriasis since animals other than humans typically do not exhibit the complex phenotypic features of human psoriasis. A variety of methods, including spontaneous mutations, drug-induced mutations, genetically engineered animals, xenotransplantation models, and immunological reconstitution approaches, have all been employed to study specific characteristics in the pathogenesis of psoriasis. Although some of these approaches have been used for more than 50 years and far more models have been introduced recently, they have surprisingly not yet undergone detailed validation. Despite their limitations, these models have shown a connection between keratinocyte hyperplasia, vascular hyperplasia, and a cell-mediated immune response in the skin. The xenotransplantation of diseased or unaffected human skin onto immune-compromised recipients has also significantly aided psoriasis research. This technique has been used in a variety of ways to investigate the function of T lymphocytes and other cells, including preclinical therapeutic studies. The design of pertinent in vivo and in vitro psoriasis models is currently of utmost concern and a crucial step toward its cure. This article outlines the general approach in the development of psoriasis-related animal models, aspects of some specific models, along with their strengths and limitations.

Climatotherapy at the Dead Sea for psoriasis is a highly effective anti-inflammatory treatment in the short term; an immunohistochemical study

Climatotherapy is a well‐described treatment of psoriasis. Dead Sea climatotherapy (DSC) in Israel consists of intensive sun and Dead Sea bathing and is very effective in improving clinical and patient‐reported outcomes. However, the effect of DSC has not been widely studied. We aimed to investigate the effect of DSC on psoriasis skin using quantitative immunohistochemistry techniques and analysis of blood samples. Skin punch biopsies from 18 psoriasis patients from a previous cohort study were used. Biopsies were obtained from non‐lesional skin and from a psoriasis target lesion at baseline. A biopsy was acquired from the target lesion after DSC. Among patients who achieved complete visual clearance, a biopsy was also obtained at relapse. Blood samples were obtained at the same time points. We performed haematoxylin and eosin staining and quantitative immunohistochemical analysis of CD3, CD4, CD8, CD11c, CD103, CD163, CD207, forkhead box P3, Ki67 and myeloperoxidase. We performed blood tests of cholesterol, c‐reactive protein, glucose, haemoglobin A1c and triglycerides. All skin biomarkers except for CD207 were decreased after DSC. At relapse, none of the biomarkers were significantly different from the baseline lesional measurements. Total CD207 staining correlated with psoriasis area and severity index at baseline while CD163 staining correlated with psoriasis area and severity index at EOT. No changes were observed in selected blood tests during the study. Consistent with clinical results, DSC is highly effective in the short term almost normalising all investigated biomarkers. However, at relapse, biomarkers were upregulated to the baseline level.

Human Langerhans Cells with Pro-inflammatory Features Relocate within Psoriasis Lesions

Psoriasis is a common skin disease that presents with well-demarcated patches of inflammation. Recurrent disease in fixed areas of the skin indicates a localized disease memory that is preserved in resolved lesions. In line with such concept, the involvement of tissue-resident immune cells in psoriasis pathology is increasingly appreciated. Langerhans cells (LCs) are perfectly placed to steer resident T cells and local tissue responses in psoriasis. Here, we present an overview of the current knowledge of LCs in human psoriasis, including findings that highlight pro-inflammatory features of LCs in psoriasis lesions. We also review the literature on conflicting data regarding LC localization and functionality in psoriasis. Our review highlights that further studies are needed to elucidate the molecular mechanisms that drive LCs functionality in inflammatory diseases.

Langerhans cell markers CD1a and CD207 are the most rapidly responding genes in lesional psoriatic skin following adalimumab treatment

TNFα-, IL-23- and IL-17-targeting drugs are highly effective in the treatment of psoriasis. However, the precise molecular mechanism remains unknown. In psoriatic skin, the presence of Langerhans cells (LCs) is reduced, but the role of LC is poorly understood. The purpose of this study was to investigate the impact of TNFα and IL-23/IL-17 on the presence of LC in the skin during treatment. Therefore, psoriatic skin was investigated before and after 4 days of adalimumab or ustekinumab treatment. Furthermore, TNFα and IL-17A stimulation was investigated in an ex vivo model of epidermis and dermis from healthy normal skin kept in cultures at an air-liquid interphase for 4 days. In a gene array analysis, we found that the two LC markers, CD1a and CD207, were among the most up- or downregulated genes in psoriatic skin after anti-TNFα therapy. Validation showed that both mRNA expression and protein level followed the same pattern and became significantly upregulated after 4 days of treatment. No changes were seen after ustekinumab treatment. In the ex vivo skin model, a decrease in the CD1a level was seen after TNFα stimulation and it was caused by LC migration from epidermis. No response in LC migration was seen after IL-17A stimulation. Taken together, we demonstrated that changes in the LC level in epidermis precede the histological and clinical changes during adalimumab treatment in psoriatic skin. Furthermore, TNFα plays a prominent role in orchestrating LC migration in the skin. This seems not to be the true for the IL-23/IL-17A pathway.

Psoriasis and inflammatory bowel disease: links and risks

Psoriasis and the spectrum of inflammatory bowel diseases (IBD) are chronic, inflammatory, organotropic conditions. The epidemiologic coexistence of these diseases is corroborated by findings at the level of disease, biogeography, and intrafamilial and intrapatient coincidence. The identification of shared susceptibility loci and DNA polymorphisms has confirmed this correlation at a genetic level. The pathogenesis of both diseases implicates the innate and adaptive segments of the immune system. Increased permeability of the epidermal barrier in skin and intestine underlies the augmented interaction of allergens and pathogens with inflammatory receptors of immune cells. The immune response between psoriasis and IBD is similar and comprises phagocytic, dendritic, and natural killer cell, along with a milieu of cytokines and antimicrobial peptides that stimulate T-cells. The interplay between dendritic cells and Th17 cells appears to be the core dysregulated immune pathway in all these conditions. The distinct similarities in the pathogenesis are also reflected in the wide overlapping of their therapeutic approaches. Small-molecule pharmacologic immunomodulators have been applied, and more recently, biologic treatments that target proinflammatory interleukins have been introduced or are currently being evaluated. However, the fact that some treatments are quite selective for either skin or gut conditions also highlights their crucial pathophysiologic differences. In the present review, a comprehensive comparison of risk factors, pathogenesis links, and therapeutic strategies for psoriasis and IBD is presented. Specific emphasis is placed on the role of the immune cell species and inflammatory mediators participating in the pathogenesis of these diseases.

Anti-TNF-α monoclonal antibody reverses psoriasis through dual inhibition of inflammation and angiogenesis

Tumor necrosis factor-alpha (TNF-α) antagonists have shown remarkable efficacy in psoriasis; however, the precise mechanisms of action of TNF-α blocking agents mainly focus on their neutralizing TNF-α and its anti-inflammatory effects. In this study, we generated a humanized anti-TNF-α monoclonal antibody (IBI303) and suggested a potential mechanism of anti-TNF-α therapy for psoriasis. The results of SPR and ELISA indicated that IBI303 has a good affinity to TNF-α. In vitro, it could suppress TNF-α-induced cytotoxicity in WEHI164 cells. In vivo, administration of IBI303 to K14-VEGF transgenic mice led to a significant treatment efficiency in psoriasis in a dose-dependent manner. IHC staining and cytokines-ELISA indicated that TNF-α inhibition strongly reduced inflammatory cells infiltration and pro-inflammatory cytokines release, accompanied by suppression of inflamed dermal blood vessels. Mechanistically, in order to explain the anti-angiogenesis effect of anti-TNF-α antibody, the production of cytokine in macrophage conditional medium was measured by ELISA. The result indicated that the massive secretion of TNF-α stimulated by LPS in RAW264.7 cell supernatant was markedly neutralized in a dose-response manner by IBI303, moreover, the expression of NF-κB p65 was down-regulated. Mouse endothelial cell tube formation assay showed that anti-TNF-α could inhibit blood vessels formation directly and indirectly. Collectively, our study suggested a kind of antipsoriatic mechanism of TNF-α inhibitors that is the dual inhibition of inflammation and angiogenesis.

Effects of TNF-alpha inhibitors on the number of epidermal Langerhans cells in uninvolved skin of psoriatic patients: a pilot study

Only limited data are available on the effects of TNF-alpha inhibitors on dendritic cells. However, TNF-alpha plays a central role in the biology of dendritic cells, both with regard to their maturity process and mobilization to secondary lymphoid organs. In particular, the effects of TNF-alpha inhibitors on Langerhans cells in healthy skin have never been investigated. In this pilot study, we aimed to assess the change of the density of Langerhans cells within the normal, not photo-exposed, skin of 17 psoriatic patients, before and after 16 weeks of treatment with TNF-alpha inhibitors. Most of the patients (88%) showed an increase or a similar density of Langerhans cells after 16 weeks of therapy with TNF-alpha inhibitors compared with baseline values. Only 2 patients (12%) showed a reduction of these cells following therapy with TNF-alpha inhibitors.

Efficacy of systemic therapies for moderate-to-severe psoriasis: a systematic review and meta-analysis of long-term treatment

BACKGROUND

Despite the chronicity of psoriasis, most systematic reviews focus on short-term treatment.

METHODS

The systematic search strategy and results from the German Psoriasis Guidelines were adapted. To update the data a literature search in Medline, Embase and the Cochrane Library was conducted. The proportion of participants achieving ≥75% decrease in Psoriasis Area and Severity Index (PASI) as well as Dermatology Life Quality Index (DLQI) reduction at different time points were assessed. Trials were summarized with respect to time periods and study designs. Suitable trials were included in a meta-analysis. Particular attention was paid to statistical approaches of handling dropouts.

RESULTS

A total of 33 articles including 27 trials totaling 6575 patients with active treatment were included in the systematic review. Seven randomized controlled trials were eligible for the meta-analysis. Over a 24 week treatment period infliximab [risk difference (RD) 78%, 95% confidence interval (CI) 72-83%] and ustekinumab 90 mg every 12 weeks (RD 77%, 95% CI 71-83%) were the most efficacious treatments. Adalimumab (RD: 60%, 95% CI 45-74%) showed results within the range of different etanercept dosages (etanercept 50 mg once weekly: RD 62%, 95% CI, 52-72%), (etanercept 25 mg twice weekly: RD 45%, 95% CI 34-56%), (etanercept 50 mg twice weekly: RD 56%, 95% CI 49-62%) and (etanercept 50 mg twice weekly until week 12, then 25 mg twice weekly: RD 50%, 95% CI 42-57%). After 24 weeks a decrease in efficacy for inflximab, adalimumab and etanercept was observed.

CONCLUSIONS

More sufficient data is required to draw reliable conclusions in extended long-term treatment and head-to-head comparisons are necessary.

Psoriasis

Psoriasis is a common relapsing and remitting immune-mediated inflammatory disease that affects the skin and joints. This review focuses on current immunogenetic concepts, key cellular players, and axes of cytokines that are thought to contribute to disease pathogenesis. We highlight potential therapeutic targets and give an overview of the currently used immune-targeted therapies.

A pharmacoeconomic analysis of severe psoriasis therapy: a review of treatment choices and cost efficiency

INTRODUCTION

Psoriasis is a chronic, inflammatory disease afflicting 2% of the US population; it results in significant morbidity. The annual healthcare costs related to psoriasis are an estimated $11.3 billion and, with an expanding biologic market, an updated costs analysis is needed.

AREAS COVERED

Current treatments, including systemic agents (acitretin, cyclosporine, methotrexate), phototherapies and all available biologics (adalimumab, etanercept, infliximab, alefacept, ustekinumab) appropriate for severe psoriasis are described mechanistically and with regard to their efficacy, quality-of-life improvements and side effects. A cost-efficacy model considering US health-system-based annual costs, clinical and quality-of-life improvements was created. Reported Psoriasis Area and Severity Index improvement of 75% from baseline (PASI-75) scores, Dermatology Life Quality Index (DLQI) improvements and estimated costs of medications are described. Annual costs ranged from $1330 for methotrexate to $48,731 for high-dose etanercept. The lowest cost per achieving DLQI minimally important difference was from phototherapy; the highest was from alefacept. The lowest costs per patient achieving PASI-75 was from methotrexate and the highest was from alefacept.

EXPERT OPINION

Phototherapies and methotrexate offer high efficacy for their costs. Therapeutic approaches must be individualized for each patient given all considerations described.

Sun exposure induces rapid immunological changes in skin and peripheral blood in patients with psoriasis

BACKGROUND

Ultraviolet (UV) radiation has immunosuppressive effects and heliotherapy is a well-described treatment modality for psoriasis.

OBJECTIVES

To characterize early sun-induced immunological changes both local and systemic in patients with psoriasis.

METHODS

Twenty patients with moderate to severe psoriasis were subjected to controlled sun exposure on Gran Canaria, Canary Islands, Spain. Psoriasis Area and Severity Index (PASI) scores were evaluated. Skin biopsies were obtained from lesional and nonlesional skin in 10 patients at baseline and on day 16 and from five additional patients on day 2. Specimens were examined with immunohistochemistry and polymerase chain reaction. Blood samples were obtained from all patients at the same time points and were examined for T-cell subsets and cytokine production.

RESULTS

Significant clinical improvement was achieved during the study period. CD4+ and CD8+ T cells in lesional skin were significantly reduced in both the epidermis and dermis. In contrast, dermal FOXP3+ T cells were relatively increased. In the peripheral blood skin homing cutaneous lymphocyte-associated antigen (CLA)+ T cells were significantly decreased after only 1 day in the sun and in vitro stimulated peripheral blood mononuclear cells demonstrated reduced capacity to secrete cytokines after 16 days.

CONCLUSIONS

Our data show that clinical improvement of psoriasis following sun exposure is preceded by a rapid reduction in local and systemic inflammatory markers, strongly suggesting that immune modulation mediated the observed clinical effect. We cannot completely rule out that other mechanisms, such as stress reduction, may contribute, but it is extensively documented that UV irradiation is a potent inducer of immunosuppression and we therefore conclude that the observed effect was primarily due to sun exposure.

Cutaneous side effects of anti-tumor necrosis factor biologic therapy: a clinical review

BACKGROUND

Anti-tumor necrosis factor (anti-TNF) biologic agents have been associated with a number of adverse events.

OBJECTIVE

To review the cutaneous reactions that have been reported in patients receiving anti-TNF therapy.

METHODS

We performed a systematic MEDLINE search of relevant publications, including case reports and case series.

RESULTS

Reported cutaneous events included infusion and injection site reactions, psoriasiform eruptions, lupus-like disorders, vasculitis, granulomatous reactions, cutaneous infections, and cutaneous neoplasms. Infusion reactions and injection site reactions were definitely associated with anti-TNF administration, whereas all other events had a varying strength of association and severity, not necessarily requiring drug discontinuation.

LIMITATIONS

Most information was derived from spontaneous case reports, where ascertainment biases and frequency of reporting may impair detection methodology and causal relationships.

CONCLUSIONS

As anti-TNF biologic agents are progressively being used in clinical practice, cutaneous adverse events will be encountered more frequently. Until more data are accumulated with respect to their pathogenesis and potential association with anti-TNF therapy, dermatologists should become more familiar with the clinical presentation and management of such events.

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

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

The PKC inhibitor AEB071 may be a therapeutic option for psoriasis

PKC isoforms tau, alpha, and beta play fundamental roles in the activation of T cells and other immune cell functions. Here we show that the PKC inhibitor AEB071 both abolishes the production of several cytokines by activated human T cells, keratinocytes, and macrophages in vitro and inhibits an acute allergic contact dermatitis response in rats. To translate these findings into humans, single and multiple ascending oral doses of AEB071 were administered to healthy volunteers and patients with psoriasis, respectively. AEB071 was well tolerated with no clinically relevant laboratory abnormalities. Ex vivo stimulation of lymphocytes from subjects exposed to single doses of AEB071 resulted in a dose-dependent inhibition of both lymphocyte proliferation and IL2 mRNA expression. Clinical severity of psoriasis was reduced up to 69% compared with baseline after 2 weeks of treatment, as measured by the Psoriasis Area Severity Index (PASI) score. The improvement in psoriasis patients was accompanied by histological improvement of skin lesions and may be partially explained by a substantial reduction of p40+ dermal cells, which are known to mediate psoriasis. These data suggest that AEB071 could be an effective novel treatment regimen for psoriasis and other autoimmune diseases, and that AEB071 warrants long-term studies to establish safety and efficacy.

Novel immunobiologics for psoriasis

Psoriasis is one of the most common human skin diseases and is considered to have key genetic contributions. It is characterized by excessive growth and aberrant differentiation of keratinocytes, but is reversible with appropriate therapy with the possibilities of recurrence. The trigger of the keratinocyte response is thought to be the activation of the cellular immune system with T cells, dendritic cells and various immune related cytokines and chemokines being implicated in pathogenesis. Immunosuppressants like cyclosporine and methotrexate were used earlier in the treatment of psoriasis, however their use was associated with severe adverse effects due to down regulation of immune system. The most recent advances in therapies for psoriasis target specific immune components of psoriasis and promise to have high therapeutic efficacy with low adverse effects. This review focuses on the novel therapies aimed to specifically modulate the dysregulated immune system with minimal adverse effects.

Immunopathogenesis of psoriasis

Investigations into the cause and treatment of psoriasis remain at the forefront of basic and applied clinical research efforts around the world. The purpose for this review is to provide an up-to-date synopsis of recent progress in ten sections exploring the immunological and inflammatory basis for psoriasis. Given the breadth of this topic in investigative skin biology and frequent paradigm shifts, it should not be surprising that the bibliography contains more than 150 references; many of which have been published in the last 5 years. Whereas considerable progress has been made into the immunopathogenesis of psoriasis, many fundamentally important questions remain regarding the role of cells located in both epidermal and dermal compartments. Attempts to characterize various animal models of psoriasis, delineation of the mechanism of action for biological agents, and consideration of molecular links between skin inflammation and various extracutaneous comorbidities are likely to continue challenging investigators and clinicians for many years to come.

Tumor necrosis factor antagonist mechanisms of action: a comprehensive review

During the past 30 years, elucidation of the pathogenesis of rheumatoid arthritis, Crohn's disease, psoriasis, psoriatic arthritis and ankylosing spondylitis at the cellular and molecular levels has revealed that these diseases share common mechanisms and are more closely related than was previously recognized. Research on the complex biology of tumor necrosis factor (TNF) has uncovered many mechanisms and pathways by which TNF may be involved in the pathogenesis of these diseases. There are 3 TNF antagonists currently available: adalimumab, a fully human monoclonal antibody; etanercept, a soluble receptor construct; and infliximab, a chimeric monoclonal antibody. Two other TNF antagonists, certolizumab and golimumab, are in clinical development. The remarkable efficacy of TNF antagonists in these diseases places TNF in the center of our understanding of the pathogenesis of many immune-mediated inflammatory diseases. The purpose of this review is to discuss the biology of TNF and related family members in the context of the potential mechanisms of action of TNF antagonists in a variety of immune-mediated inflammatory diseases. Possible mechanistic differences between TNF antagonists are addressed with regard to their efficacy and safety profiles.

Targeting TNFalpha rapidly reduces density of dendritic cells and macrophages in psoriatic plaques with restoration of epidermal keratinocyte differentiation

BACKGROUND

The cytokine network theory for psoriasis postulates a key role for TNFalpha in mediating inflammation and altered epidermal differentiation.

OBJECTIVE

This study defines responses following administration of adalimumab, a TNFalpha inhibitor, in pre-psoriatic skin (PN) and lesional psoriatic plaques (PP) skin.

METHODS

PN and PP skin before and after treatment were biopsied at days 2, 7, 28 and 84 (n=6 different patients). Cryosections were immunohistochemically stained to detect TNFalpha and other relevant markers in epidermal and dermal compartments. Detection of apoptosis utilized antibody specific for activated caspase 3. Semiquantitative assessments and statistical analysis was performed for each staining profile.

RESULTS

TNFalpha+ cells were increased in PP skin. PP skin was also characterized by a four-fold increase in number of CD68+ macrophages as well as eight-fold increase in CD11c+ dermal dendritic cells (DCs) compared to PN skin. By two-color immunofluorescence staining, both CD68+ cells as well as CD11c+ cells expressed TNFalpha. Following initiation of adalimumab therapy, CD11c+ cells, significantly decreased in PP skin at days 7, 28, and 84, while CD68+ and CD14+ cells decreased at days 28 and 84. Other markers for DCs (CD83, CD86) showed decreases at days 7, 28, and 84. Reduction in DCs, macrophages or T cells was not accompanied by increased activated caspase 3-positive cells. When a keratinocyte terminal differentiation marker was examined, adalimumab triggered rapid restoration of loricrin expression (beginning on day 2), with loss of aberrant differentiation marker, keratin 17 (K17).

CONCLUSION

Adalimumab impacts dermal-based immunocytes, and the epidermal compartment also responds by restoration of normal differentiation without detectable apoptosis.

Early inflammatory changes in the "perilesional skin" of psoriatic plaques: is there interaction between dendritic cells and keratinocytes?

Early inflammatory changes in psoriatic plaques were investigated immunohistochemically by studying the normal-appearing skin adjacent to the plaques (perilesional skin), lesional skin, and distant uninvolved skin from psoriasis patients. Perilesional epidermis contained numerous CD1a-positive Langerhans cells, some of which expressed HLA-DR, CD83, CD80, and CD86, at the same time expressing Langerin. There were also numerous CD83-positive, CD11c-positive, Langerin-negative dendritic cells (DCs) in the epidermal-dermal junction of perilesional skin. CD3-positive T lymphocytes were sparse in the perilesional skin. Perilesional epidermis expressed keratin K6 and K16, inflammatory keratins, and C/EBPbeta, a transcription factor related to inflammatory cytokines. Our results demonstrated the abundant distribution of activated DCs in the perilesional skin of psoriatic plaques, where early inflammatory changes occur in the epidermal keratinocytes, which suggests their involvement in the provocation of epidermal inflammation in the perilesional epidermis and further pathogenic roles in the formation of psoriatic plaques.

Antitumour necrosis factor-? chimeric antibody (infliximab) inhibits activation of skin-homing CD4+ and CD8+ T lymphocytes and impairs dendritic cell function

BACKGROUND

Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation and altered differentiation of keratinocytes in reply to cytokines such as interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha, provided by infiltrating CD4+ and CD8+ T cells and natural killer cells. Infliximab is a chimeric monoclonal antibody that neutralizes both soluble and membrane-bound TNF-alpha, and that may give a long-term disease remission.

OBJECTIVES

To determine the in vitro effects of infliximab on CD4+ and CD8+ T cells derived from lesional skin, and on dendritic cells (DCs).

METHODS

Psoriatic T-cell lines were isolated from lesional skin of four patients with psoriasis and assayed for their proliferation, cytokine release and susceptibility to apoptotic stimuli in the presence of graded (1-100 microg mL(-1)) concentrations of infliximab. DCs were differentiated in the presence of infliximab from peripheral blood monocytes. Phenotype was assessed by fluorescence-activated cell sorting and antigen-presenting capacity in functional assays.

RESULTS

In vitro activation of psoriatic as well as antigen (nickel)-specific skin-homing T cells was strongly and dose-dependently impaired by infliximab, in terms both of proliferation and of IFN-gamma release. Despite the significant reduction of IFN-gamma secretion, infliximab only marginally affected the release of interleukin (IL)-10 by skin T cells, thus determining a reduction of the IFN-gamma/IL-10 ratio at the site of inflammation. The effects were maximal when T-cell activation occurred in the absence of costimulation, or when T cells were activated by immature compared with mature DCs. In addition, skin-homing CD8+ T cells were more prominently affected by infliximab compared with CD4+ T lymphocytes, both in terms of inhibition of activation and in their susceptibility to apoptosis. Finally, infliximab directly affected the differentiation of monocyte-derived DCs, by inhibiting the expression of CD1a and CD86, and strongly impaired the antigen-presenting capacity of immature and, to a lesser extent, mature DCs.

CONCLUSIONS

Infliximab directly affects psoriatic T cells and impairs the antigen-presenting capacity of DCs. These effects may help to explain the long-term disease remission obtained with the drug.

Systemische Psoriasistherapie – der nächste Schritt

Adalimumab is the first fully human monoclonal antibody against TNFalpha and has been approved for treatment of rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis. Its efficacy for both joint and skin involvement has been confirmed in clinical trials. The recommended dose is 40 mg administered every other week subcutaneously. It may be combined with methotrexate and all topical psoriasis treatment modalities. User-friendly administration devices make self-injection possible. Patients should be evaluated for active/latent tuberculosis and serious infections prior to initiation of therapy. Adalimumab rapidly reduces joint symptoms within a few days. Adalimumab is used for the management of adult psoriatic arthritis patients who have had an inadequate response to disease-modifying antirheumatic drugs. Adalimumab is yet another biological for the treatment of psoriasis. Since the TNFalpha antagonists can be switched if one is ineffective, this agent broadens the therapeutic spectrum.

Mouse models of psoriasis

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

Immunobiologics in the treatment of psoriasis

The pathogenesis of various inflammatory cutaneous diseases such as psoriasis, atopic dermatitis and mycosis fungoides relies greatly on the abnormal function of T cells. Fundamental knowledge of the role of T cells in the cutaneous immune response has led to the development and production of biologic molecules designed to block T cell function at various steps, specifically activation (i.e. alefacept, efalizumab), trafficking into inflamed skin (i.e. efalizumab) and effector function under cytokine control (i.e. etanercept, infliximab, adalimumab, and anti-IL-12 antibody). We review the immune abnormalities and the role of T cells in psoriasis, and the recent biologic therapies, which share the common mission to hinder T cell activity in inflammatory diseases. An advantage from the preciseness of these biologic therapies is the potential limit of non-specific and potentially devastating organ toxicity, which commonly plagues other systemic therapies.

Adalimumab for maintenance of clinical response and remission in patients with Crohn's disease: the CHARM trial

BACKGROUND & AIMS

This study evaluated the efficacy and safety of adalimumab, a fully human, anti-tumor necrosis factor monoclonal antibody administered subcutaneously, in the maintenance of response and remission in patients with moderate to severe Crohn's disease (CD).

METHODS

Patients received open-label induction therapy with adalimumab 80 mg (week 0) followed by 40 mg (week 2). At week 4, patients were stratified by response (decrease in Crohn's Disease Activity Index > or =70 points from baseline) and randomized to double-blind treatment with placebo, adalimumab 40 mg every other week (eow), or adalimumab 40 mg weekly through week 56. Co-primary end points were the percentages of randomized responders who achieved clinical remission (Crohn's Disease Activity Index score <150) at weeks 26 and 56.

RESULTS

The percentage of randomized responders in remission was significantly greater in the adalimumab 40-mg eow and 40-mg weekly groups versus placebo at week 26 (40%, 47%, and 17%, respectively; P < .001) and week 56 (36%, 41%, and 12%, respectively; P < .001). No significant differences in efficacy between adalimumab eow and weekly were observed. More patients receiving placebo discontinued treatment because of an adverse event (13.4%) than those receiving adalimumab (6.9% and 4.7% in the 40-mg eow and 40-mg weekly groups, respectively).

CONCLUSIONS

Among patients who responded to adalimumab, both adalimumab eow and weekly were significantly more effective than placebo in maintaining remission in moderate to severe CD through 56 weeks. Adalimumab was well-tolerated, with a safety profile consistent with previous experience with the drug.

The skin as a site of initiation of systemic autoimmune disease: new opportunities for treatment

Dendritic cells are the coordinators of the adaptive immune response. Chronic activation of skin dendritic cells by keratinocyte expression of CD40 ligand (CD40L; CD154) leads to autoimmunity. In this issue, systemic administration of tacrolimus is shown by Loser et al. to effectively treat autoimmunity in a murine model involving transgenic keratinocyte expression of CD40L.