Novel immunotherapies for psoriasis

Immunotherapy in psoriasis

Over the past two decades, significant progress has been achieved in the treatment of psoriasis by targeting the human cytokine network. At present, 11 biologicals - antibodies, and a soluble receptor - are used to neutralize key inflammatory cytokines. Based on their targets, they can be grouped into the following four classes: TNF-α-, IL-12/23-, IL-17- and IL-23-inhibitors. The range of available substances, as well as their different modes of action can be challenging when selecting the right drug for an individual patient. In this article, we provide an overview of the approved biologicals for the treatment of psoriasis, including their advantages and limitations, and summarize criteria for therapy selection.

AIPpred: Sequence-Based Prediction of Anti-inflammatory Peptides Using Random Forest

The use of therapeutic peptides in various inflammatory diseases and autoimmune disorders has received considerable attention; however, the identification of anti-inflammatory peptides (AIPs) through wet-lab experimentation is expensive and often time consuming. Therefore, the development of novel computational methods is needed to identify potential AIP candidates prior to in vitro experimentation. In this study, we proposed a random forest (RF)-based method for predicting AIPs, called AIPpred (AIP predictor in primary amino acid sequences), which was trained with 354 optimal features. First, we systematically studied the contribution of individual composition [amino acid-, dipeptide composition (DPC), amino acid index, chain-transition-distribution, and physicochemical properties] in AIP prediction. Since the performance of the DPC-based model is significantly better than that of other composition-based models, we applied a feature selection protocol on this model and identified the optimal features. AIPpred achieved an area under the curve (AUC) value of 0.801 in a 5-fold cross-validation test, which was ∼2% higher than that of the control RF predictor trained with all DPC composition features, indicating the efficiency of the feature selection protocol. Furthermore, we evaluated the performance of AIPpred on an independent dataset, with results showing that our method outperformed an existing method, as well as 3 different machine learning methods developed in this study, with an AUC value of 0.814. These results indicated that AIPpred will be a useful tool for predicting AIPs and might efficiently assist the development of AIP therapeutics and biomedical research. AIPpred is freely accessible at www.thegleelab.org/AIPpred.

First-In-Human, Phase 1, Randomized, Dose-Escalation Trial with Recombinant Anti-IL-20 Monoclonal Antibody in Patients with Psoriasis

Background

The current trial was a first-in-human clinical trial evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of the recombinant monoclonal anti−interleukin-20 (IL-20) antibody, NNC0109-0012, which targets the inflammatory cytokine IL-20.

Methods

In total, 48 patients aged 18 to 75 years with moderate to severe stable chronic plaque psoriasis with affected body surface area ≥15% and physician global assessment score ≥3 were enrolled in this randomized, double-blind, multicenter, placebo-controlled, phase 1 dose-escalation trial. Patients were randomized within each single dose cohort (0.01, 0.05, 0.2, 0.6, 1.5, or 3.0 mg/kg) or multiple dose cohort (0.05, 0.2, 0.5, 1.0, or 2.0 mg/kg; 1 dose every other week for 7 weeks) of NNC0109-0012 or placebo in a 3:1 ratio. In the expansion phase, 7 patients were randomized to weekly doses of 2.0 mg/kg NNC0109-0012 or placebo for 7 weeks. The primary objective, safety and tolerability, was assessed by evaluating adverse events (AEs). Additional endpoints included pharmacokinetics, pharmacodynamics, and clinical response (assessed using the Psoriasis Area and Severity Index [PASI] score).

Results

AEs were reported in 85% of patients (n = 40) in the initial study phases (NNC0109-0012, 83%; placebo, 92%) and in 4 of 7 patients in the multiple-dose expansion phase. One serious AE was reported but was judged not to be causally related to NNC0109-0012. No dose-limiting toxicities were reported. NNC0109-0012 pharmacokinetics was similar to other monoclonal antibodies, with an average half-life of approximately 3 weeks. There was a dose-proportional increase in area under the curve and maximum concentration after single dosing. No substantial changes in pharmacodynamic parameters were observed. The expansion phase was terminated early due to apparent lack of PASI improvement.

Conclusion

Single and multiple doses of NNC0109-0012, ranging from 0.05 to 3.0 mg/kg, were well tolerated in patients with psoriasis and exhibited pharmacokinetics similar to that of other monoclonal antibodies.

Trial Registration

ClinicalTrials.gov NCT01261767

Protein kinase inhibitors in the treatment of inflammatory and autoimmune diseases

Protein kinases mediate protein phosphorylation, which is a fundamental component of cell signalling, with crucial roles in most signal transduction cascades: from controlling cell growth and proliferation to the initiation and regulation of immunological responses. Aberrant kinase activity is implicated in an increasing number of diseases, with more than 400 human diseases now linked either directly or indirectly to protein kinases. Protein kinases are therefore regarded as highly important drug targets, and are the subject of intensive research activity. The success of small molecule kinase inhibitors in the treatment of cancer, coupled with a greater understanding of inflammatory signalling cascades, has led to kinase inhibitors taking centre stage in the pursuit for new anti-inflammatory agents for the treatment of immune-mediated diseases. Herein we discuss the main classes of kinase inhibitors; namely Janus kinase (JAK), mitogen-activated protein kinase (MAPK) and spleen tyrosine kinase (Syk) inhibitors. We provide a mechanistic insight into how these inhibitors interfere with kinase signalling pathways and discuss the clinical successes and failures in the implementation of kinase-directed therapeutics in the context of inflammatory and autoimmune disorders.

Association of psoriasis severity with serum prolactin, thyroid hormones, and cortisol before and after treatment

Background. Prolactin (PRL) level is proposed to be associated with the severity of psoriasis although the previous studies reported different results. Objective. To find the association between PRL levels and severity of psoriasis before and after treatment. In addition, we aimed to find a difference in prolactin, thyroid stimulating hormone (TSH), thyroid hormones (T₃ and T₄), and cortisol levels between patients with psoriasis and normal controls. Methods. First, the levels of hormones were measured in 30 patients with psoriasis and 30 matched controls. The severity was assessed by psoriasis area and severity index (PASI). Then, patients were treated, and PASI was assessed every week until achieving PASI-75 response. At this time, the hormones were measured again and compared to the baseline. Results. No statistical significant difference was observed in the mean PRL, T₃, T₄, TSH, and cortisol levels between cases and controls. Comparing to the baseline, a significant decrease in PRL levels and a significant increase in T₃ and serum cortisol levels were observed after treatment (P < 0.05), while the changes in other hormones were not significant. Conclusion. After treatment, PRL significantly decreased, and T₃ and cortisol levels significantly increased. No correlation between hormone levels and improvement of PASI score existed.

Identification of binding specificity-determining features in protein families

We present a new approach for identifying features of ligand-protein binding interfaces that predict binding selectivity and demonstrate its effectiveness for predicting kinase inhibitor specificity. We analyzed a large set of human kinases and kinase inhibitors using clustering of experimentally determined inhibition constants (to define specificity classes of kinases and inhibitors) and virtual ligand docking (to extract structural and chemical features of the ligand-protein binding interfaces). We then used statistical methods to identify features characteristic of each class. Machine learning was employed to determine which combinations of characteristic features were predictive of class membership and to predict binding specificities and affinities of new compounds. Experiments showed predictions were 70% accurate. These results show that our method can automatically pinpoint on the three-dimensional binding interfaces pharmacophore-like features that act as "selectivity filters". The method is not restricted to kinases, requires no prior hypotheses about specific interactions, and can be applied to any protein families for which sets of structures and ligand binding data are available.

In vitro screening for putative psoriasis-specific antigens among wheat proteins and peptides

BACKGROUND

Patients with psoriasis who had raised IgG and/or IgA antigliadin antibodies showed clinical improvement in a trial with a gluten-free diet. The selection of patients for the diet treatment was based on the presence of specific antibodies, i.e. the result of humoral immunity.

OBJECTIVES

As psoriasis is now considered to be a T cell-mediated disease we decided to challenge peripheral blood mononuclear cells (PBMCs) in vitro from randomly selected patients with well-defined wheat proteins/peptides to explore the possibility of identifying a specific antigen with T cell activating properties in a subgroup of patients.

METHODS

PBMCs from 37 patients (20 female and 17 male; mean age 49years) and 37 healthy controls (12 female and 25 male; mean age 57years) were included. Not all patients participated in all experiments. The PBMCs were exposed in vitro with the following wheat proteins/peptides in various concentrations: total albumins, 0·28 α-amylase inhibitor and the synthetic peptides, p31-43, p57-68 and p62-75, based on coeliac-active sequences of α-gliadin. The proliferative response was measured as counts per minute after the cells had been pulsed with methyl-(3) H-thymidine.

RESULTS

Albumin, α-amylase inhibitor, p31-43 and p57-68 elicited a significant response in both patients and controls but showed no differences between the groups. The response induced by the α-amylase inhibitor was higher than that induced by the albumin fraction and the p31-43 and p57-68 peptides. At a concentration of 25μgmL(-1) , five of 36 patients with psoriasis responded positively to the p62-75 peptide and none of the 33 controls, using a stimulation index of 2·4 as the cut-off level (P<0·05). These five patients did not show clinical features that differed from the remaining patients. Among the responding patients the relative number of CD4+ cells increased in some but not all after in vitro challenge with the albumins, 0·28 α-amylase inhibitor, and p62-75. These antigens could also induce in vitro the expression of the homing antigen cutaneous lymphocyte antigen (CLA) in a few patients and controls.

CONCLUSIONS

The wheat protein antigens, especially the p62-75 peptide, might be of interest in a subgroup of patients with psoriasis.

Inhibition of the IL-2-inducible tyrosine kinase (Itk) activity: a new concept for the therapy of inflammatory skin diseases

T-cell-mediated processes play an essential role in the pathogenesis of several inflammatory skin diseases such as atopic dermatitis, allergic contact dermatitis and psoriasis. The aim of this study was to investigate the role of the IL-2-inducible tyrosine kinase (Itk), an enzyme acting downstream of the T-cell receptor (TCR), in T-cell-dependent skin inflammation using three approaches. Itk knockout mice display significantly reduced inflammatory symptoms in mouse models of acute and subacute contact hypersensitivity (CHS) reactions. Systemic administration of a novel small molecule Itk inhibitor, Compound 44, created by chemical optimization of an initial high-throughput screening hit, inhibited Itk's activity with an IC50 in the nanomolar range. Compound 44 substantially reduced proinflammatory immune responses in vitro and in vivo after systemic administration in two acute CHS models. In addition, our data reveal that human Itk, comparable to its murine homologue, is expressed mainly in T cells and is increased in lesional skin from patients with atopic dermatitis and allergic contact dermatitis. Finally, silencing of Itk by RNA interference in primary human T cells efficiently blocks TCR-induced lymphokine secretion. In conclusion, Itk represents an interesting new target for the therapy of T-cell-mediated inflammatory skin diseases.

Therapeutic efficacy and immunological response of CCL5 antagonists in models of contact skin reaction

Skin-infiltrating T-cells play a predominant role in allergic and inflammatory skin diseases such as atopic dermatitis, psoriasis and allergic contact dermatitis. These T-cells are attracted by several chemotactic factors including the chemokine CCL5/RANTES, a CC chemokine inducing both the migration and activation of specific leukocyte subsets. CCL5 has been found to be associated with various cell-mediated hypersensitive disorders such as psoriasis, atopic dermatitis and irritant contact dermatitis. We have used two antagonists, the first, Met-CCL5, a dual CCR1/CCR5 antagonist and the second, a variant in which GAG binding is abrogated, ⁴⁴AANA⁴⁷-CCL5, which acts as a dominant negative inhibitor of CCL5. The antagonists were tested in two models of contact skin reaction. The first, irritant contact dermatitis (ICD) is a pathological non-specific inflammatory skin condition arising from the release of pro-inflammatory cytokines by keratinocytes in response to haptens, usually chemicals. The second, contact hypersensitivity (CHS) is a T-cell dependent model, mimicking in part the T-cell-mediated skin diseases such as psoriasis. In both models, the CCL5 antagonists showed therapeutic efficacy by reducing swelling by 50% as well as the reduction of soluble mediators in homogenates derived from challenged ears. These results demonstrate that blocking the receptor or the ligand are both effective strategies to inhibit skin inflammation.

A global gene expression analysis of the peripheral blood mononuclear cells reveals the gene expression signature in psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory skin disease that affects approximately 1~3% of the general population.

OBJECTIVE

We performed cDNA microarray analysis with using the dendrimer labelling method to investigate the gene expression profile in the peripheral blood mononuclear cells (PBMCs) of psoriatic patients.

METHODS

The peripheral blood mononuclear cells of 5 patients with psoriasis and 8 control subjects were used in the gene expression analyses of psoriasis.

RESULTS

We identified 212 differentially expressed genes that showed at least a two-fold induction and/or reduction in psoriatic patients. Among those, 63 genes, including CD44, CD56 and IL7R, were induced, while 139 genes, including the sphingosine kinase 1 and p16-INK genes, were reduced in the psoriatic patients.

CONCLUSION

We can speculate that these genes may have a role for the pathogenesis of psoriasis via their affecting different cellular functions. Our results suggest a possible mechanism by which activated immune cells migrate from the blood to the skin in psoriatic patients, and we provide novel putative targets for developing drugs to treat psoriasis.

Antipsoriatic effects of avarol-3'-thiosalicylate are mediated by inhibition of TNF-alpha generation and NF-kappaB activation in mouse skin

BACKGROUND AND PURPOSE

Avarol is a marine sesquiterpenoid hydroquinone with anti-inflammatory and antipsoriatic properties. The aim of this study was to evaluate the in vitro and in vivo pharmacological behaviour of the derivative avarol-3'-thiosalicylate (TA) on some inflammatory parameters related to the pathogenesis of psoriasis.

EXPERIMENTAL APPROACH

Human neutrophils and monocytes as well as the human keratinocyte cell line HaCaT were used to study the effect of TA on oxidative stress, the arachidonic acid pathway, tumour necrosis factor-alpha (TNF-alpha) release and nuclear factor-kappaB (NF-kappaB) activation. All these parameters were also determined in vivo using the zymosan induced mouse air pouch model and the 12-O-tetradecanoylphorbol-13-acetate (TPA) induced mouse epidermal hyperplasia model.

KEY RESULTS

TA showed antioxidant properties in human neutrophils and in the hypoxanthine/xanthine oxidase assay. This compound reduced, in a concentration-dependent manner, leukotriene B(4), prostaglandin E(2) and TNF-alpha production in activated leukocytes. Oral and intrapouch administration of TA in the mouse air pouch model produced a dose-dependent reduction of all these inflammatory mediators. TA also inhibited secretory phospholipase A(2) activity and NF-kappaB DNA-binding in HaCaT keratinocytes. In TPA-induced mouse epidermal hyperplasia, topical administration of TA reduced oedema, leukocyte infiltration, eicosanoid levels and TNF-alpha in skin. In addition, interleukin (IL)-1beta and IL-2 production were also inhibited. Finally, TA was also capable of suppressing NF-kappaB nuclear translocation in vivo.

CONCLUSIONS AND IMPLICATIONS

TA inhibited several key biomarkers up-regulated in the inflammatory response of psoriatic skin and this compound could be a promising antipsoriatic agent.

Chemical Warfare Agents Chemical Warfare Agents: Their Past and Continuing Threat and Evolving Therapies Part II of II

Chemical warfare agents are ideal weapons for terrorists and for use in military operations against both civilian populations and troops. Thus, there have been efforts by the United States in cooperation with other concerned nations to develop animal models to understand the pathophysiology of the injuries induced by these agents, and to develop suitable animal models for testing of pre-and post-exposure protectants and therapies. Sulfur mustard remains the most significant chemical warfare agent that produces cutaneous injuries. Institution of standard recommendations prior to threatened exposure or after exposure are something that we need to be aware of in the world we live in. In addition, pre-and post-exposure therapies now being studied offer hope for moderating the mortality and morbidity that can result from chemical exposure.

Thermography in psoriasis vulgaris evaluation

Psoriasis vulgaris is a chronic inflammatory skin disease with a strong genetic component, characterized by hyperkeratosis, dermal inflammatory infiltrate and increased angiogenesis. The aim of the present study was to employ thermography in evaluation of psoriatic lesions localized in different parts of the body. A series of in-patients with stable plaque type psoriasis vulgaris were included. ThermaCam INFRAMETRICS 290E thermocamera with temperature resolution of 0.1 &#176;C was used in the study. Both visual and thermal images of 84 areas of lesional and lesion-free skin in patients were taken and analyzed. All the skin lesions were divided into 4 groups, according to their location i.e. found on the upper limbs, lower limbs, chest and back. Increased temperature was observed over psoriatic lesions located in the chest and upper limbs. To the contrary, skin lesions located on the back and lower limbs presented lower temperature. It is conceivable to speculate that lower temperature revealed within the lower parts of the body may explain to some extend slower regression of the lesions located in this region in comparison to skin lesions located over the upper parts of the body.

Qualitative thermograhic analysis of psoriatic skin lesions

Psoriasis vulgaris affects about 2% of the human population all over the world. The aim of this study was to evaluate usefulness of thermography in estimation of psoriatic lesion activity. A series of patients with plaque type psoriasis vulgaris were included. ThermaCam INFRAMETRICS 290E thermocamera with temperature resolution of 0.1 degrees C was employed. Both visual and thermal images of the patients were taken. Clinical severity of the lesions was evaluated by Plaque Severity Score (PSS, scale 0-4). We discovered higher temperature over psoriatic plaques and further vastly expanding beyond the visually documented borders of the lesions thus not corresponding to the individual shapes of the lesions, suggested that those lesions presented an active phase of the disease (developing over the last 2-3 weeks). To the contrary, areas of the increased temperature over chronic psoriatic plaques (already developed at least 8 weeks before without signs of visible progression) corresponded quite well to the shapes of clinically visible lesions i.e. single lesions could be differentiated within the area of the increased temperature. The above observations would allow to introduce more aggressive local treatment only to the selected lesions thus as much as possible sparing the rest of them from probable side-effects.

Dimethylfumarate induces immunosuppression via glutathione depletion and subsequent induction of heme oxygenase 1

A mixture of different fumaric acid esters (FAE) is established for systemic therapy of psoriasis, a frequent inflammatory skin disease. The main active compound of FAE, however, has not been identified so far, and the mechanisms of activity are only partially understood. We analyzed the impact of FAE on in vitro immune function and aimed to gain knowledge about the mode of action. Dimethylfumarate (DMF) and diethylfumarate (DEF), but not fumaric acid, methylhydrogenfumarate and ethylhydrogenfumarate, exhibited potent depression of inflammatory cytokine secretion (e.g., tumor necrosis factoralpha, IL-12, and IFNgamma) in activated human peripheral blood mononuclear cells. Moreover, solely DMF and DEF inhibited alloreactive T-cell proliferation in mixed leukocyte reaction. Interestingly, these immunosuppressive effects were accompanied by the strong induction of the anti-inflammatory stress protein heme oxygenase 1 (HO-1). Supplementation with exogenous glutathione (GSH), which is known to bind DMF, prevented both HO-1 induction as well as the anti-inflammatory effects of DMF. Moreover, inhibition of HO-1 activity restored the diminished IL-12 and IFNgamma production after FAE treatment. These results suggest that DMF acts as active compound within the FAE mixture and at least partially mediates its immunomodulatory activity by the induction of the anti-inflammatory stress protein HO-1 ascribed to the functional depletion of reduced GSH.

Targeting leukocyte trafficking to inflamed skin - still an attractive therapeutic approach?

Research into leukocyte trafficking and its therapeutic exploitation appears to be a multistep process, just like the trafficking cascade itself. The initial euphoria evoked by an early understanding of the trafficking steps was followed by considerable disappointment following the clinical failure of the first selectin antagonist Cylexin (CY-1503), a sialyl Lewis(X) mimetic. The research area recovered and identified additional attractive pharmacological targets such as chemokine receptors and integrins. However, after lack of efficacy in anti-chemokine trials and the fatalities associated with anti VLA-4 therapy (Tysabri), the question arose again whether targeting leukocyte trafficking is really promising or whether such a complex, multistep process with many redundant and/or functionally overlapping molecules is simply too challenging to deal with. In this article, we delineate some pros and cons of this approach followed by a brief update on where we stand in the field and where we might move in the future.

Identification and characterization of noncalcemic, tissue-selective, nonsecosteroidal vitamin D receptor modulators

Vitamin D receptor (VDR) ligands are therapeutic agents for the treatment of psoriasis, osteoporosis, and secondary hyperparathyroidism. VDR ligands also show immense potential as therapeutic agents for autoimmune diseases and cancers of skin, prostate, colon, and breast as well as leukemia. However, the major side effect of VDR ligands that limits their expanded use and clinical development is hypercalcemia that develops as a result of the action of these compounds mainly on intestine. In order to discover VDR ligands with less hypercalcemia liability, we sought to identify tissue-selective VDR modulators (VDRMs) that act as agonists in some cell types and lack activity in others. Here, we describe LY2108491 and LY2109866 as nonsecosteroidal VDRMs that function as potent agonists in keratinocytes, osteoblasts, and peripheral blood mononuclear cells but show poor activity in intestinal cells. Finally, these nonsecosteroidal VDRMs were less calcemic in vivo, and LY2108491 exhibited more than 270-fold improved therapeutic index over the naturally occurring VDR ligand 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] in an in vivo preclinical surrogate model of psoriasis.

Altered Morphology and Distribution of Cellular Junction Proteins in Non-Lesional Psoriatic Epidermis: An Insight into Disease Severity

BACKGROUND

Psoriasis affects 2.7% of the world's population. Keratinocyte proliferation outside the basal layer suggests alterations in cell-cell interactions in affected epidermis. Anomalous expression of proteins forming intercellular junctions has been reported in lesional skin of psoriatic patients. In contrast, little is known about possible alterations in psoriatic non-lesional skin.

METHODS

Ten clinically diagnosed psoriasis vulgaris patients and ten controls were studied. All patients were diagnosed with active but controlled psoriatic plates (PASI 3 to 5) and had not received any systemic treatment. The mean age was 43 years for patients and 43.5 years for controls. Four-mm2 skin samples were taken from lesional and non-lesional zones in patients and from abdomen in controls. Five-mum sections were examined for integrity and structural organization by fluorescent labeling of actin filaments and nuclei. Specific antibodies were utilized to localize occludin, E-cadherin, beta-catenin, and proliferation-specific keratins in sections and epidermal sheets. Samples were also processed for immunoblotting with occludin antibody.

RESULTS

Lesional and non-lesional psoriatic epidermis from all patients showed keratinocyte hyperproliferation, lack of rete ridges and dermal papillae in the dermal-epidermal junction in some areas. Proteins forming tight and adherens junctions in non-lesional skin keratinocytes from two patients who during the course of the study evolved to uncontrolled disease, showed similar alterations to those observed in lesional skin of all the patients. However, the occludin isoforms expressed were apparently the same in all samples.

CONCLUSIONS

Analysis of non-lesional skin in psoriatic patients diagnosed with controlled disease may provide clues about incipient structural abnormalities in the pathogenesis of psoriasis, providing an early diagnostic indicator for evolution to a generalized form of the disease.

Fulfilling an Unmet Need in Psoriasis

Psoriasis is a chronic inflammatory disease of the skin affecting approximately 2% of the world's population. Traditional systemic treatments, including methotrexate, ciclosporin, psoralen plus UVA (PUVA), oral retinoids and fumaric acid esters, are widely used for severe disease and are effective in the short term. Severe psoriasis is a chronic disease and patients and physicians have expressed concerns about possible harm from organ toxicity, such as skin cancer (PUVA), hyperlipidaemia (retinoids), renal (ciclosporin) or hepatotoxicity (methotrexate). Long-term monitoring is required and may not detect early organ damage. The pathophysiology of psoriasis remains to be clarified, but advances toward the understanding of the immunological basis of psoriasis have uncovered the involvement of immunological pathways; for example, the role of tumour necrosis factor (TNF)-alpha, T cell proliferation and T cell activation, and migration to the epidermis. This advancement in knowledge combined with developments in recombinant technologies has led to the development of target-specific therapies. Biological agents are defined as proteins that can be extracted from animal tissue or produced via recombinant DNA technologies and possess pharmacological activity. Adalimumab, alefacept, infliximab, efalizumab and etanercept are examples of biological agents currently used for the treatment of psoriasis. Some of these are also therapy for other autoimmune conditions, such as rheumatoid arthritis and Crohn's disease. These biological agents are effective in psoriasis but raise new safety concerns. Information on the safety of biological agents in conditions such as rheumatoid arthritis and Crohn's disease can not be directly extrapolated to psoriasis. An increased incidence of lymphomas has been postulated to be associated with etanercept, infliximab and adalimumab; serious infections, such as tuberculosis, have also been reported with these three biologicals, all of which target TNF-alpha. Demyelinating disorders, such as multiple sclerosis, have been reported with some biologicals as has congestive heart failure. Alefacept, because of its mechanism of action of lowering the number of active T cells, is associated with low T cell counts. Efalizumab has been associated with thrombocytopenia and haemolytic anaemia. Data on the safety of >2.5 years' continuous treatment with efalizumab are reassuring and a valuable beginning to understanding the role and risk of harm of long-term therapy for a chronic disease. Longer follow-up studies and safety databases, for each of the biologicals used in psoriasis, are needed to ensure both prolonged efficacy and minimal risk of harm.

Plaque psoriasis vs. atopic dermatitis and lichen planus: a comparison for lesional T-cell subsets, epidermal proliferation and differentiation

BACKGROUND

T-cell infiltration in plaque psoriasis has recently been an important subject of investigation. Interestingly, comparative analyses of the disease-specific composition of the lesional T-cell infiltrate in plaque psoriasis and other inflammatory dermatoses have only sparsely been performed.

OBJECTIVES

To compare plaque psoriasis vs. atopic dermatitis and lichen ruber planus with respect to T-cell subsets, epidermal proliferation and keratinization.

PATIENTS AND METHODS

Biopsies were taken from untreated lesional skin of patients, six with psoriasis, six with atopic dermatitis and six with lichen planus. T-cell subsets (CD4+, CD8+, CD45RO+, CD45RA+, CD2+, CD25+), an epidermal proliferation (Ki-67) and a keratinization marker (K10) were stained immunohistochemically and quantified using image analysis.

RESULTS

The high number of CD8+ T cells (52 +/- 13 cells mm(-1)) found in the psoriatic epidermis was not found in the epidermis of atopic dermatitis (9 +/- 4), nor in the epidermis of lichen planus (34 +/- 10). The other T-cell subsets in the epidermis and dermis showed no statistically significant differences between psoriasis and atopic dermatitis. In contrast to the limited presence of CD4+, CD8+ and CD2+ in the psoriatic dermis (110 +/- 19, 27 +/- 9, 127 +/- 41, cells mm(-1), respectively), more impressive numbers of these cells were observed in the dermis of lichen planus (300 +/- 53, 144 +/- 38, 272 +/- 48, respectively). CD45RO+ memory effector T-cell counts were significantly higher in the epidermis of lichen planus (39 +/- 10) than in psoriasis (19 +/- 5). Psoriatic epidermis proved to have major keratinocyte hyperproliferation (247 +/- 26 cells mm(-1) lamina basalis), as compared with atopic dermatitis (134 +/- 15) and lichen planus (128 +/- 20). Furthermore, a marked decreased expression of keratin 10 was observed in psoriasis (41% of epidermal area) contrary to atopic dermatitis (70%).

CONCLUSIONS

Psoriatic epidermis exhibits a pronounced CD8+ epidermotropism with accompanying epidermal hyperproliferation and abnormal keratinization, which changes are only minimally expressed in atopic dermatitis and lichen planus. In plaque psoriasis, substantially fewer activated CD4+ and CD8+ T cells in the dermis and less CD45RO+ T cells in the epidermis are present in comparison with lichen ruber planus.

Efficacy of the fully human monoclonal antibody MOR102 (#5) against intercellular adhesion molecule 1 in the psoriasis-severe combined immunodeficient mouse model

BACKGROUND

Psoriasis is considered as a chronic immune-mediated disease characterized by inflammation and proliferation of the epidermis.

OBJECTIVES

Targeting intercellular adhesion molecule 1 (ICAM-1) is an attractive therapeutic option as this molecule is critically involved in leucocyte adhesion and extravasation as well as in lymphocyte activation.

METHODS

We have selected the fully human monoclonal antibody MOR102 (#5) against ICAM-1 from the Human Combinatorial Antibody Library (HuCAL). This antibody, as human IgG4 [corrected] was tested for its ability to interfere with lymphocyte activation and adhesion in vitro as well as for its antipsoriatic efficacy in vivo using the psoriasis-severe combined immunodeficient (SCID) mouse model.

RESULTS

The antibody demonstrated efficient inhibition of lymphocyte adhesion to ICAM-1 in vitro, with an IC(50) of approximately 0.4 microg mL(-1) (3 nmol L(-1)). In addition, MOR102 (#5) reduced lymphocyte proliferation in mixed lymphocyte cultures by approximately 50%. The in vivo efficacy of MOR102 (#5) was tested on grafts derived from lesional skin of patients with chronic plaque-stage psoriasis transplanted on to SCID mice. Intraperitoneal injection of 10 mg kg(-1) of MOR102 (#5) antibody every alternate day over a period of 4 weeks resulted in reconstitution of orthokeratotic differentiation and a significant (P < 0.05) reduction in epidermal thickness as well as marked reduction in the inflammatory infiltrate. Therapeutic activity may be related to the targeting of ICAM-1 on keratinocytes and thus preventing efficient activation of local T cells.

CONCLUSIONS

Based on the efficacy of the fully human monoclonal antibody MOR102 (#5) shown in vitro as well as in vivo in the psoriasis-SCID mouse model, initiation of clinical studies is indicated.

Differential expression of phosphorylated NF-kappaB/RelA in normal and psoriatic epidermis and downregulation of NF-kappaB in response to treatment with etanercept

Etanercept, a recombinant human tumor necrosis factor (TNF) receptor fusion protein, is FDA approved for psoriasis and psoriatic arthritis. TNFalpha increases the synthesis of proinflammatory cytokines and leads to the activation of multiple signaling pathways, including nuclear factor kappa B (NF-kappaB). The Rel/NF-kappaB transcription factors play a central role in numerous cellular processes, including the stress response and keratinocyte proliferation and differentiation. Utilizing a phosphorylation-specific antibody, we examined the expression of active nuclear NF-kappaB/RelA via immunohistochemistry in normal skin, non-lesional psoriatic skin, lesional psoriatic skin, and lesional skin from patients treated with etanercept. There was no expression of active nuclear NF-kappaB in the normal epidermis, whereas a basal level of constitutive active phosphorylated NF-kappaB/RelA was present in uninvolved epidermis from psoriasis patients. There was also significant upregulation of active phosphorylated NF-kappaB/RelA in the epidermis from psoriatic plaques. Serial biopsies from psoriasis patients treated with etanercept at 1, 3, and 6 mo demonstrated a significant downregulation of phosphorylated NF-kappaB/RelA, which correlated with decreases in epidermal thickness, restoration of normal markers of keratinocyte differentiation, and clinical outcomes. These data suggest that activation of NF-kappaB plays a significant role in the pathogenesis of psoriasis and that a potential mechanism of action for TNF-targeting agents is downregulation of NF-kappaB transcriptional activity.

Emerging drugs in psoriasis

Psoriasis is a relatively common, chronic skin disease affecting 1-2% of the population in the developed countries. It is an inflammatory, autoimmune skin disorder characterised by an accelerated rate of epidermal proliferation and disordered differentiation. Since our last review in 1999, considerable progress has been made in understanding the immunopathogenesis of this disease, and new drugs have become available for its treatment. Recent clinical trials showed the efficacy of novel biotechnology approaches, such as blocking tumour necrosis factor-alpha or T-cell-mediated immune response by the anti-CD2, anti-CD11a, anti-B7, anti-CD4 or anti-CD25 approaches. Agents which block type 1 cytokines or skew immune reactions into type 2 are other promising approaches. Other possible targets are chemokines and their receptors, the cytokines and receptors involved in T cell trafficking into the skin, and peroxisome proliferator-activated receptors. Relatively little development is reported of the drugs targeting the keratinocyte or the classical antipsoriatic compounds which include glucocorticoids, vitamin D derivatives and cytostatic agents.

Biological roles of APP in the epidermis

The amyloid precursor protein (APP) was initially detected in cells of the central nervous system where it is considered to be involved in the pathogenesis of Alzheimer's disease. However, APP is also found in peripheral organs with exceptionally strong expression in the mammalian epidermis where it fulfils a variety of distinct biological roles. Full length APP appears to facilitate keratinocyte adhesion due to its ability to interact with the extracellular matrix. The C-terminus of APP also serves as adapter protein for binding the motor protein kinesin thereby mediating the centripetal transport of melanosomes in epidermal melanocytes. By the action of alpha-secretase sAPPalpha, the soluble N-terminal portion of APP, is released. sAPPalpha has been shown to be a potent epidermal growth factor thus stimulating proliferation and migration of keratinocytes as well as the exocytic release of melanin by melanocytes. The release of sAPPalpha can be almost completely blocked by inhibiting alpha-secretase with hydroxamic acid-based zinc metalloproteinase inhibitors. In hyperproliferative keratinocytes from psoriatic skin this inhibition results in normalized growth.

Infliximab induction therapy for patients with severe plaque-type psoriasis: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Tumor necrosis factor-alpha is a key mediator in the pathogenesis of psoriasis. Infliximab is a monoclonal antibody that specifically binds to tumor necrosis factor-alpha, blocking its biologic activity.

OBJECTIVE

The purpose of this study was to access the efficacy and safety of infliximab induction therapy for patients with severe plaque psoriasis.

METHODS

In this multicenter, double-blind, placebo-controlled trial, 249 patients with severe plaque psoriasis were randomly assigned to receive intravenous infusions of either 3 or 5 mg/kg of infliximab or placebo given at weeks 0, 2, and 6. The primary end point was the proportion of patients who achieved at least 75% improvement in Psoriasis Area and Severity Index score from baseline at week 10. At week 26, patients whose Physician Global Assessment indicated moderate or severe disease were eligible for a single intravenous infusion of their assigned treatment to assess the safety of retreatment after a 20-week, treatment-free interval.

RESULTS

At week 10, 72% of patients treated with infliximab (3 mg/kg) and 88% of patients treated with infliximab (5 mg/kg) achieved a 75% or greater improvement from baseline in Psoriasis Area and Severity Index score compared with 6% of patients treated with placebo (P <.001). Improvement was observed in both infliximab groups as early as 2 weeks. Overall, 63%, 78%, and 79% of patients in the placebo, 3-, and 5-mg/kg groups, respectively, reported one or more adverse events.

CONCLUSIONS

Infliximab treatment resulted in a rapid and significant improvement in the signs and symptoms of psoriasis. Infliximab was generally well tolerated.

Selective Persistence of Dermal CD8+ T Cells in Lesional Plaque Psoriasis after Clobetasol‐17 Propionate Treatment

In psoriasis, T-cell infiltration and epidermal hyperproliferation are key phenomena which are closely related. Our aim was to investigate the dynamics among T-cell subsets in relation to epidermal proliferation and clinical severity in psoriasis during treatment with an ultra-potent corticosteroid. Seven psoriasis patients were treated twice daily for 14 days with clobetasol-17 propionate ointment. Punch biopsies were taken at day 0, 3, 7 and 14. Epidermal proliferation marker Ki-67 and CD4+, CD8+, CD45RO+, CD2+ T cells were quantified by immunohistochemical techniques and image analysis. The clinical score declined significantly (60%; p<0.01) and a 47% reduction of Ki-67+ nuclei was observed after only 3 days (p<0.01). In the epidermis all investigated T-cell subsets were significantly reduced at day 14 (p<0.05). In the dermis, treatment resulted in a significant decrease of CD4+, CD45RO+ and CD2+ T cells, but dermal CD8+ T cells persisted. In psoriasis, reduction of clinical severity and epidermal proliferation during the early phase of topical corticosteroid therapy cannot primarily be the result of decreased T-cell subsets. Furthermore, selective persistence of dermal CD8+ T cells was observed, which might be associated with disease relapse.

Functional regulation of T lymphocytes by modulatory extracellular matrix proteins

In addition to the major structural molecules, which are constitutively present in extracellular matrices, several proteins appear in the extracellular matrix only at specific stages in development or in association with specific pathological conditions. These proteins include thrombospondin-1 and -2, tenascin C, osteopontin, members of the cysteine-rich 61/connective tissue growth factor/nephroblastoma overexpressed family, and secreted protein acidic and rich in cysteine (osteonectin). These proteins play important roles in regulating cell fate during development and in the pathogenesis of several diseases in adult animals. We will review the interactions of T cells with this class of molecules and their resulting effects on T cell behavior. Receptors and signal transduction pathways that mediate the actions of matricellular proteins on T cells are beginning to be defined. Transgenic mice are providing new insights into the functions of these proteins in vivo and are yielding insights into the significance of their reported dysregulation in several human diseases.

Biology of tumor necrosis factor-alpha- implications for psoriasis

Numerous recent investigations have pointed to a key role of the proinflammatory, pleiotropic cytokine tumor necrosis factor-alpha (TNF-alpha) in host defense and inflammatory processes. TNF overexpression has been found in lesional skin and in the circulation of psoriatic patients, and it was suggested that TNF-alpha is crucial in this and other immune diseases. Several approaches to inhibit TNF-alpha activity have been developed. These include three different neutralizing antibodies to TNF-alpha as well as three different soluble TNF-alpha receptors with characteristic properties designed to bind the 17-KDa soluble trimeric TNF-alpha and the 26-KDa membrane-bound form of TNF-alpha. Clinical trials have demonstrated significant antipsoriatic effects, and it is likely that blocking TNF-alpha will become an important therapeutic option. The data available from these trials contribute to further understanding of the disease by demonstrating the major role of TNF-alpha. An in-depth understanding of the regulation of TNF gene expression, protein production, receptor expression, and signaling pathways may lead to further, potentially important novel therapeutic strategies and antipsoriatic active small molecules, suitable for oral application in the future. Here we review the current knowledge of TNF biology, the approaches to inhibit TNF activity, and their clinical and immunological effects in psoriasis. In addition, the host-defense effects and chronic TNF-blocking activity are discussed.

Normalized proliferation of normal and psoriatic keratinocytes by suppression of sAPPalpha-release

The soluble form of the beta-amyloid precursor protein (sAPPalpha) is known to function in the autocrine regulation of epidermal growth and repair. Here we show that its proteolytic release by alpha-secretase in normal human keratinocytes is susceptible to hydroxamic-acid-based zinc metalloproteinase inhibitors and suppressed by these inhibitors by 80%-90%. As various other growth factors participate in regulating epidermal growth we investigated whether the inhibitor-induced sAPPalpha-deficiency would affect keratinocyte proliferation. At optimal inhibitor concentrations the suppression of sAPPalpha-release was followed by a decline in proliferation by 50%-60%, indicating that sAPPalpha is a major growth factor that cannot be compensated for by other growth factors. This finding was the basis for the treatment of human lesional psoriatic keratinocytes with these inhibitors, which resulted in the normalization of their increased proliferation rates. The reversibility of these effects and the lack of toxicity underline the value of these inhibitors and suggest their therapeutic application in psoriatic skin diseases.

The molecular basis of lymphocyte recruitment to the skin: clues for pathogenesis and selective therapies of inflammatory disorders

Spatial compartmentalization and tissue-selective localization of T lymphocytes to the skin are crucial for immune surveillance and the pathogenesis of various disorders including common inflammatory diseases such as atopic dermatitis or psoriasis, but also malignancies such as cutaneous T cell lymphomas. Cutaneous recruitment of lymphocytes is a highly complex process that involves extravasation, migration through the dermal connective tissue, and eventually, localization to the epidermis. An intertwined network of cytokines and chemokines provides the road signs for leukocyte migration, while various adhesion receptors orchestrate the dynamic events of cell-cell and cell-substrate interactions resulting in cutaneous localization of T cells. Selectively targeting the functions of molecules involved in this interplay promises exciting new therapeutic options for treating inflammatory skin disorders.

Interleukin 4 treatment of psoriasis: are pleiotropic cytokines suitable therapies for autoimmune diseases?

Many human autoimmune diseases are still treated by a combination of corticosteroids and general immunosuppression. A better understanding of the pathogenesis of these diseases has led to therapies that are more specific than current therapies of some of these disorders. In psoriasis, T helper (Th) cells with a pro-inflammatory phenotype (Th1) are considered essential to the disease process. A recent clinical trial of interleukin 4 in psoriasis has demonstrated that such pleiotropic cytokines can be used safely and effectively to correct imbalances in immune function.

Cytokine and anticytokine therapy in dermatology

Cytokines play a pivotal role in the initiation, propagation and regulation of immunologic responses. They are of utmost importance in the pathogenesis of several diseases, including skin diseases. Using cytokines or cytokine antagonists as immunomodulators exhibiting either immunosuppressive or immunostimulatory effects is a rapidly emerging field and is already adding or is about to add significantly to the therapeutic arsenal for malignant and inflammatory dermatoses. Whereas some cytokine therapies, such as IFN-alpha or IL-2, are well-established in melanoma therapy, there are others in early stages of clinical development. The fascinating aspect is the ongoing transition of the work in basic immunobiology of skin diseases into clinical application. Vice versa, observations in clinical trials are also instrumental in further promoting our knowledge of the pathophysiology of skin diseases. In this review, the current status of cytokine and anticytokine therapy for skin diseases is discussed.

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.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Elevated rate of Thelper1 (T(H)1) lymphocytes and serum IFN-gamma levels in psoriatic patients

Several disorders are known to be associated with altered Thelper1/Thelper2 (T(H)1/T(H)2) cytokine balance. Psoriasis is characterized by increased systemic and local production of T(H)1 and pro-inflammatory cytokines. Furthermore recent data indicate the dominant presence of T(H)1 lymphocytes in the circulation and T(H)1 and Tcytotoxic1 (T(C)1) cells in lesional skin of psoriatic patients. In order to assess the systemic T(H)1/T(H)2 imbalance in psoriasis most of the studies so far tested isolated peripheral mononuclear cells. As a new approach we applied a whole blood flow cytometric assay to determine the rate of circulating T(H)1/T(H)2 and T(C)1/Tcytotoxic2 (T(C)2) lymphocytes based on their intracellular IFN-gamma, IL-4 and IL-10 expression. Besides, serum levels of these cytokines were determined in healthy controls and psoriatic patients by commercial ELISAs. In psoriatic patients we found significantly (P<0.02) increased rates of CD4(+)/IFN-gamma(+) lymphocytes (30.3+/-8.8%) while the percent of CD4(+)/IL-4(+) cells (0.37+/-0.31%) were significantly (P<0.03) lower compared to healthy controls (CD4(+)/IFN-gamma(+): 20.1+/-7.3% and CD4(+)/IL-4(+): 0.78+/-0.44%). The IL-10-positive CD4(+) and CD8(+) cells also had higher rate in psoriasis, but the difference between patients and controls was not significant, similarly to the rate of CD8(+)/IFN-gamma(+) and CD8(+)/IL-4(+) lymphocytes. Beside cellular expression, serum IFN-gamma levels were also significantly higher (control: 4.9+/-6.4 pg/ml; psoriatic patients: 35.9+/-47.0 pg/ml; P<0.05). Our results provide further evidence for an altered T(H)1/T(H)2 balance in psoriasis measured in non-separated whole blood T cells.