Translating clinical activity and gene expression signatures of etanercept and ciclosporin to the psoriasis xenograft SCID mouse model

Background The psoriasis xenograft severe combined immunodeficiency (SCID) mouse model is used in drug discovery to obtain preclinical proof‐of‐principle of new antipsoriatic drug candidates. Validation of this model by antipsoriatic therapeutic agents in clinical use is important to understand its utility as well as its limitations. The effects of the clinically efficacious antitumour necrosis factor‐α biologics have not yet been demonstrated in the psoriasis xenograft SCID mouse model. Objectives To investigate the effect of etanercept and to explore the time‐dependent changes induced by ciclosporin on psoriatic biomarkers at the gene expression level in the psoriasis xenograft SCID mouse model. Methods Xenografted SCID mice were treated either with etanercept and vehicle for 2 weeks or with ciclosporin and vehicle for 2 and 4 weeks, respectively. Treatment‐induced changes in the psoriatic grafts were assessed by gene expression analysis and compared with published clinical microarray data. The grafts were further evaluated by histology and immunohistochemistry. Results Etanercept induced normalization of gene expression, which correlated with a significant reduction in epidermal thickness as well as a decrease in the number of proliferative cells. Anti‐inflammatory activity induced by ciclosporin preceded the reduction in epidermal hyperplasia. Comparison of the etanercept‐ and ciclosporin‐induced gene expression signatures with clinical microarray data showed significant correlations. Conclusions Efficacy of etanercept and ciclosporin could be translated to the psoriasis xenograft SCID mouse model.     

Resolution of psoriasis by a leukocyte-targeting bacterial protein in a humanized mouse model

Psoriasis is a very common chronic skin disease, affecting 2-3% of the world's population or more than 125 million individuals worldwide. The characteristic lesion of psoriasis is due to rapid proliferation and shortened transition of keratinocytes through the epidermis. Proinflammatory white blood cells (WBCs) migrate into the psoriatic plaques, and the pathogenic cytokine environment causes the changes in keratinocyte proliferation and differentiation. Enhanced migration of WBCs is due to the upregulation and activation of adhesion molecules such as leukocyte function antigen-1 (LFA-1), which binds intercellular adhesion molecule-1 (ICAM-1) on endothelial cells. Targeting LFA-1 and preventing interaction with ICAM-1 has proven an effective strategy for treating psoriasis. We show here that a natural leukocyte-targeting bacterial protein (leukotoxin (LtxA)) that binds LFA-1 can inhibit proliferation of activated WBCs from psoriasis patients and demonstrates significant therapeutic efficacy in a psoriasis xenograft transplantation model. In ex vivo studies, LtxA preferentially targeted proinflammatory WBC subtypes, including activated CD25(+) T cells and CD14(+)CD16(+) monocytes. LFA-1 has been shown to have a significant role in the pathogenesis of numerous autoimmune and inflammatory diseases, and we propose that LtxA may be a highly effective agent for treating these diseases.     

Anti-CD4 monoclonal antibody treatment of moderate to severe psoriasis vulgaris: results of a pilot, multicenter, multiple-dose, placebo-controlled study

BACKGROUND: OKTcdr4a (IMUCLONE) is a humanized anti-CD4 IgG4 monoclonal antibody that retains the binding and in vitro immunosuppressive properties of the parent murine antibody. Psoriasis is a chronic disease for which treatment with multiple doses of monoclonal antibodies is likely to be required for adequate control. OBJECTIVE: This study was performed to test the efficacy and safety of OKTcdr4a, given in sequential courses over a period of several weeks, in the treatment of moderate to severe psoriasis vulgaris. METHODS: Twenty-eight patients (45.6 +/- 10.1 years of age) were studied, with a mean pretreatment Psoriasis Area and Severity Index (PASI) score of 18.3. In the first double-blind phase of the study, patients were randomized to receive OKTcdr4a as a 225 mg/course (low dose), 750 mg/course (high dose), or placebo divided into 3 identical infusions over a 5-day period. After 42 days, patients who met the criteria for re-treatment with OKTcdr4a were re-treated with the 750 mg/course in an open phase of the study. RESULTS: After the double-blind course of treatment, the mean PASI decreased by 11% in the placebo group, by 4% in the low-dose group, and by 17% in the high-dose group at 15 days. Twenty patients met the criteria for re-treatment (ie, did not experience a decrease in PASI score of 50% at 42 days). They were re-treated with OKTcdr4a at 43 days with the 750 mg/course in the open phase of the study. By day 99, the mean PASI score decreased from 19.9 at baseline to 17 in those patients who had received either placebo or low-dose OKTcdr4a followed by high-dose OKTcdr4a. In contrast, the mean PASI score decreased from 17.4 at baseline to only 7.7 in those patients who had received high-dose OKTcdr4a for both courses. Sustained CD4 saturation was not necessary for sustained clinical response. No patients had significant changes in circulating CD4(+) T-cell counts. The infusions were well tolerated. CONCLUSION: Targeting CD4 using sequential treatments with a humanized monoclonal antibody (OKTcdr4a) may offer another therapeutic option for the treatment of moderate to severe psoriasis.     

Sitagliptin, a dipeptidyl peptidase-IV inhibitor, improves psoriasis

A patient with a 17-year history of plaque psoriasis accompanied by type 2 diabetes mellitus discontinued cyclosporine and steroid ointment given for treatment of psoriasis because she was dissatisfied with the effects of the drugs. After sitagliptin, a dipeptidyl peptidase-IV (DPP-IV) inhibitor, was administered for control of blood glucose, psoriatic skin lesions were gradually diminished, although HbA1c did not improve. Three months after the administration of sitagliptin, infiltration, scales and erythema on all psoriatic plaques disappeared, leaving pigmentation on flat skin. DPP-IV in serum degrades the incretin hormones which stimulate β-cell insulin secretion. DPP-IV inhibitors, as incretin enhancers, cause an increase in glucose-dependent insulin secretion, and are applied for the treatment of diabetes mellitus. DPP-IV is also expressed on T cells as CD26, a surface antigen which plays an important role in activating T cells. As helper T cells are involved in the pathogenesis of psoriasis, it is possible that DPP-IV inhibitors improve psoriatic skin lesions by inhibiting T cell activation, independently of glycemic control. DPP-IV inhibitors could be an alternative for the treatment of psoriasis.     

Characterization of lymphocyte-dependent angiogenesis using a SCID mouse: human skin model of psoriasis

From a clinical perspective, angiogenesis is an important component of acute and chronic psoriatic skin lesions as they are erythematous and display a tendency to bleed after superficial removal of scale. By routine histology, numerous microscopic vascular abnormalities are also present. The structural expansion of capillaries and distinctive activated phenotype of lesional endothelial cells are believed not only to be clinical and pathologic hallmarks of the disease, but to play a central role in the pathogenesis of psoriatic plaques. Despite over 20 years of research by leading angiogenesis experts and numerous studies, many details regarding the cellular and molecular basis for angiogenesis in psoriasis remain unknown. In this review, 10 different sections are presented to update recent progress in this active field of investigative skin biology. Highlights of this review include the phenotypic characterization of endothelial cells in acute and chronic psoriatic plaques, and a review of a novel animal model of psoriasis using human skin engrafted onto severe combined immunodeficient mice followed by injection of activated immunocytes. This new experimental model represents a reproducible and pharmacologically validated method to trigger neovascularization and bona fide psoriatic plaque formation. In addition, the potential contribution of epidermal keratinocytes and dermal macrophages to the angiogenic tissue reaction is presented, and a series of questions are then posed that can be answered using the severe combined immunodeficient mouse model of psoriasis. Finally, a model is proposed integrating all available data into a coherent multistep reaction schema that includes active participation by multiple cell types including natural killer T cells, keratinocytes, macrophages, and microvascular endothelial cells.     

Paclitaxel encapsulated in cationic liposomes diminishes tumor angiogenesis and melanoma growth in a "humanized" SCID mouse model

Paclitaxel is an alkaloid that inhibits endothelial cell proliferation, motility, and tube formation at nanomolar concentrations. Cationic liposome preparations have been shown to target blood vessels. We wished to explore the possibility that paclitaxel encapsulated in cationic liposomes carries paclitaxel to blood vessels and thereby provides an antiangiogenic effect. We used a humanized SCID mouse melanoma model, which allowed us to analyze tumor growth and tumor angiogenesis in an orthotopic tumor model. Here, human melanoma cells grow on human dermis and are in part nourished by human vessels. We show that paclitaxel encapsulated in liposomes prevents melanoma growth and invasiveness and improves survival of mice. Moreover, liposome-encapsulated paclitaxel reduces vessel density at the interface between the tumor and the human dermis and reduces endothelial cell mitosis to background levels. In contrast, equimolar concentrations of paclitaxel solubilized in Cremophor EL(R) had only insignificant effects on tumor growth and did not reduce the mitotic index of endothelium in vivo, although the antiproliferative effect of solubilized paclitaxel in Cremophor EL(R)in vitro was identical to that seen with liposome-coupled paclitaxel. In conclusion, we present a model of how to exploit cytotoxic effects of compounds to prevent tumor growth by using cationic liposomes for targeting an antiproliferative drug to blood vessels.     

Interleukin-20 plays a critical role in maintenance and development of psoriasis in the human xenograft transplantation model

Background  Interleukin (IL)-20 is a recently discovered cytokine displaying increased levels in psoriatic lesions. Interestingly, IL-20 levels decrease with antipsoriatic treatment, correlating with clinical improvement. However, the role of IL-20 in the aetiology of psoriasis is unknown.
Objectives  In this study, we investigate the effects both of blocking IL-20 signalling in psoriatic plaques and of adding IL-20 to nonlesional psoriasis skin.
Methods  We employed the human skin xenograft transplantation model in which psoriatic plaques and nonlesional keratome skin biopsies obtained from donors with moderate to severe plaque psoriasis were transplanted on to immuno-deficient mice. The transplanted mice were treated with anti-IL-20 antibodies or recombinant human IL-20.
Results  We demonstrate that blocking IL-20 signalling with anti-IL-20 antibodies induces psoriasis resolution and inhibits psoriasis induction. We also demonstrate that continuous IL-20 infusion, together with injection of additional nonactivated leucocytes, promotes induction of psoriasis in nonlesional skin from patients with psoriasis.
Conclusions  The results suggest that IL-20 plays a critical role in the induction and maintenance of psoriasis, and IL-20 is suggested as a new possible specific target in psoriasis treatment.     

The humanized SCID mouse model to study HLA class II-linked autoimmunity to desmoglein 3 in pemphigus vulgaris

BACKGROUND: Pemphigus vulgaris (PV) is a severe autoimmmune skin disorder induced by antibodies against desmoglein (Dsg) 3 on epidermal keratinocytes. OBJECTIVES: To establish an active animal model of PV to analyse the T-cell-regulated production of pathogenic antibodies in vivo. METHODS: Immunodeficient SCID mice were injected with peripheral blood lymphocytes (PBL) from an HLA-DRB1*0402/DQ8+ patient with PV or a DRB1*0402/DQ8+ healthy donor, with or without subsequent injections of human Dsg3 or preincubation of PBL with Dsg3. RESULTS: Human immunoglobulins (2.7-18.5 mg mL-1) were detected in all the mice after 8 weeks. Only one of 30 PBL-treated mice developed IgM against Dsg3 and showed intercellular IgM deposits in skin, nostrils and tongue. In contrast, in a previous study, 41% of SCID mice injected with PBL from patients with PV developed anti-Dsg3 antibodies in vivo. CONCLUSIONS: Our inability to reproduce these findings may be due to the transfer of slightly lower numbers of PBL (20 x 10(6) vs. 25-30 x 10(6)).     

Statistical evaluation and experimental design of a psoriasis xenograft transplantation model treated with cyclosporin A

Psoriasis xenograft transplantation models where human skin is transplanted onto immune-deficient mice are generally accepted in psoriasis research. Over the last decade, they have been widely employed to screen for new therapeutics with a potential anti-psoriatic effect. However, experimental designs differ in several parameters. Especially, the number of donors and grafts per experimental design varies greatly; numbers that are directly related to the probability of detecting statistically significant drug effects. In this study, we performed a statistical evaluation of the effect of cyclosporine A, a recognized anti-psoriatic drug, to generate a statistical model employable to simulate different scenarios of experimental designs and to calculate the associated statistical study power, defined as the probability of detecting a statistically significant anti-psoriatic drug treatment effect. Results showed that to achieve a study power of 0.8, at least 20 grafts per treatment group and a minimum of five donors should be included in the chosen experimental setting. To our knowledge, this is the first time that study power calculations have been performed to evaluate treatment effects in a psoriasis xenograft transplantation model. This study was based on a defined experimental protocol, thus other parameters such as drug potency, treatment protocol, mouse strain and graft size should, also, be taken into account when designing an experiment. We propose that the results obtained in this study may lend a more quantitative support to the validity of results obtained when exploring new potential anti-psoriatic drug effects.     

Tacrolimus ointment improves psoriasis in a microplaque assay

Tacrolimus (FK506) is an effective and well tolerated immunosuppressant used to prevent allograft rejection. We describe the evaluation of two tacrolimus ointment formulations for treatment of chronic plaque-type psoriasis. This was a microplaque assay with randomized, double-blind design. Sixteen patients (15 men, one woman, all white and 28-69 years old) with chronic plaque-type psoriasis participated. Six different ointments were applied to discrete microplaques, 17 mm in diameter, on a descaled psoriasis lesion: these were tacrolimus ointment with diisopropyl adipate as penetration enhancer, tacrolimus ointment without diisopropyl adipate, 0.1% betamethasone 17alpha-valerate ointment, 0.005% calcipotriol ointment and, as controls, the ointment bases for tacrolimus and betamethasone. Ointments were reapplied and the area was sealed every 2-3 days during the 14-day treatment period. After 7 and 14 days, erythema and infiltration were graded on a scale of 0-4, and superficial blood flow was measured with a laser Doppler flowmeter. Epidermal thickness was measured histologically at the end of treatment. Compared with the vehicle controls, sites treated with tacrolimus ointment (with or without penetration enhancer) showed a significant reduction in erythema and infiltration (P < 0. 001), a significant reduction in superficial blood flow (P < 0.01) and a significant decrease in epidermal thickness (P < or = 0.001). Results for betamethasone and calcipotriol, when compared with the vehicle controls, were similar. These results suggest that, under conditions of descaling and occlusion, tacrolimus ointment is effective in the treatment of psoriasis.     

Effects of administration of a single dose of a humanized monoclonal antibody to CD11a on the immunobiology and clinical activity of psoriasis

BACKGROUND: CD11a/CD18 comprise subunits of leukocyte function associated antigen (LFA-1), a T-cell surface molecule important in T-cell activation, T-cell emigration into skin, and cytotoxic T-cell function. OBJECTIVE: We explored the immunobiologic and clinical effects of treating moderate to severe psoriasis vulgaris with a single dose of humanized monoclonal antibody against CD11a (hu1124). METHODS: This was an open label study with a single dose of hu1124 at doses of 0.03 to 10 mg/kg. Clinical (Psoriasis Area and Severity Index [PASI]) and immunohistologic parameters (epidermal thickness, epidermal and dermal T-cell numbers, and keratinocyte intercellular adhesion molecule 1 [ICAM-1] expression) were followed. RESULTS: Treatment with hu1124, at doses higher than 1.0 mg/kg (group III), completely blocks CD11a staining for at least 14 days in both blood and psoriatic plaques. At 0.3 to 1.0 mg/kg, T-cell CD11a staining was completely blocked; however, blockade lasted less than 2 weeks (group II). Only partial saturation of either blood or plaque cellular CD11a was observed at doses of hu1124 between 0.01 and 0.1 mg/kg (group I). This pharmacodynamic response was accompanied by decreased numbers of epidermal and dermal CD3(+) T cells, decreased keratinocyte and blood vessel expression of ICAM-1, and epidermal thinning. Statistically significant drops in PASI compared with baseline were observed in group II patients at weeks 3 and 4 and in group III patients at weeks 2 through 10. No significant drop in PASI score was observed in group 1. Adverse events were mild at doses of 0.3 mg/kg or less and included mild chills, abdominal discomfort, headache, and fever. At a single dose of 0.6 mg/kg or higher, headache was the most common dose-limiting toxicity observed. CONCLUSION: Targeting CD11a may improve psoriasis by inhibiting T-cell activation, T-cell emigration into the skin, and cytotoxic T-cell function.     

抗CD20单克隆抗体治疗寻常型天疱疮研究进展

寻常型天疱疮是一种累及皮肤、黏膜,以泛发性水疱为特征的自身免疫性皮肤病,药物治疗寻常型天疱疮主要是通过抑制免疫系统,减少相关特异性抗体的产生,从而控制疾病的发展.目前糖皮质激素仍作为常规治疗的首选,而利妥昔单抗作为辅助治疗的一种抗CD20单克隆抗体,近年来已在寻常型天疱疮治疗中获得满意疗效.由于利妥昔单抗治疗可出现严重输液相关反应,增加感染风险,且价格昂贵、治疗累积时间长、易复发及耐药等缺点,临床上已减少了利妥昔单抗在寻常型天疱疮中的应用.新一代抗CD20单克隆抗体,克服了利妥昔单抗治疗的不良反应,有改善用药方式、减少治疗时间等优点,逐渐用于寻常型天疱疮治疗,新的研究成果给患者提供更多治疗选择.     

Characterization of a T cell line bearing natural killer receptors and capable of creating psoriasis in a SCID mouse model system

T cells bearing natural killer receptors (NKRs) such as CD94 and CD161 are present in psoriasis. These immunocytes express several receptors for both classical and non-classical class I MHC molecules. Whether T cells bearing NKRs in psoriatic lesions represent immunoregulatory versus pathogenic immunocytes or are just bystander cells is unclear. To address this issue, a CD94+/CD161+ T cell line was established from a psoriatic patient using IL-2/superantigens, and the interaction between NK-T cells and keratinocytes was characterized using in-vitro and in-vivo assays. Upon incubation between NK-T cells and CD1d positive keratinocytes, high levels of IFN-gamma and IL-13 were produced. Cytokine production was inhibited by a mAb against CD1d, implicating recognition of this surface molecule in the T cell response. Furthermore when this line was injected into pre-psoriatic skin engrafted onto a SCID mouse, a psoriatic plaque was created. The hyperplastic epidermal keratinocytes diffusely expressed CD1d, and were infiltrated by CD161+ T cells. RNase protection assay revealed predominantly IFN-gamma and IL-15 mRNAs, with barely detectable IL-13 mRNA in the acute lesion. These in-vivo findings demonstrated that this T cell line was pathogenic by creating a psoriatic plaque. The in-vitro results support a pathophysiologic role for interaction between T cells expressing NKRs and CD1d positive keratinocytes, with subsequent production of IFN-gamma. Upon injection in-vivo, the cytokine network produced was characterized by an immunological response polarized towards Th1 rather than Th2 cytokines. Thus, this pathogenic cell line provides evidence that T cells bearing NKRs can directly provoke a Th1 disease such as psoriasis.     

K252a, a high-affinity nerve growth factor receptor blocker, improves psoriasis: an in vivo study using the severe combined immunodeficient mouse-human skin model

The peripheral nervous system, in addition to its sensory and motor functions, can induce a local inflammatory response known as neurogenic inflammation. This phenomenon plays a critical role in several inflammatory diseases, e.g., asthma, atopy, rheumatoid arthritis, psoriasis, and ulcerative colitis. Neurogenic inflammation and the role of nerve growth factor (NGF) have been extensively studied in psoriasis. There are increased levels of NGF in the keratinocytes and upregulation of NGF receptor (NGF-R) in the cutaneous nerves of psoriatic plaques. NGF can influence all the salient pathologic events noticed in psoriasis such as proliferation of keratinocytes, angiogenesis, T cell activation, expression of adhesion molecules, proliferation of cutaneous nerves, and upregulation of neuropeptides. In this double-blinded, placebo-controlled study, we addressed the role of NGF/NGF-R in psoriasis in an in vivo system using the severe combined immunodeficient (SCID) mouse-human skin model of psoriasis. The transplanted psoriatic plaques on the SCID mice (n=12) were treated with K252a, a high-affinity NGF receptor blocker. Psoriasis significantly improved following 2 wk of therapy. The length of the rete pegs changed from 308.57+/-98.72 to 164.64+/-46.78 microm (p<0.01, Student's t test). A similar improvement of psoriasis was observed by directly inhibiting NGF with NGF-neutralizing antibody. NGF-neutralizing antibody in normal saline at 10 ng (n=4) and 20 ng (n=4) per kilogram of body weight doses were used. Both doses of NGF-neutralizing antibody reduced rete peg lengths significantly, e.g., from 298.5+/-42.69 to 150.52+/-32.93 microm (p<0.05, Student's t test). This study provides evidence for the role of NGF and its high-affinity receptor in the pathogenesis of psoriasis and insights to develop novel therapeutic modalities.     

Anti-CD20 monoclonal antibody (rituximab) in the treatment of pemphigus

BACKGROUND: Pemphigus is a severe autoimmune blistering disorder caused by autoantibodies to desmoglein 1 and 3. The disease course is typically severe, thus requiring multiple immunosuppressive agents. The treatment is still challenging and in some patients with recalcitrant disease, therapies fail and therapeutic options are limited. OBJECTIVES: To investigate whether depletion of B lymphocytes that are thought to produce disease-causing autoantibodies shows a long-term benefit in pemphigus. METHODS: Five patients diagnosed as having pemphigus vulgaris and pemphigus foliaceus were treated with the monoclonal antibody rituximab. Rituximab was administered intravenously at a dosage of 375 mg m(-2) once weekly for 4 weeks. RESULTS: The treatment was well tolerated and all patients showed a good response over a follow-up period of up to 3 years, allowing immunosuppressive treatment to be reduced or terminated. B-cell depletion persisted for 6-12 months, and in one patient for almost 3 years. CONCLUSIONS: This study highlights the prolonged effect and disease control after one single course of rituximab and further extends the spectrum of treatments of bullous autoimmune disorders.     

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.