IL-10 is a key cytokine in psoriasis. Proof of principle by IL-10 therapy: a new therapeutic approach

Subclinical activation of latent cytomegalovirus (CMV) infection and anti-CMV immune response in patients with atopic dermatitis

BACKGROUND

Microbiological infections are considered to be of pathophysiological importance in atopic dermatitis (AD). As yet, no information is available regarding cytomegalovirus (CMV) infection in this disease. This, however, is of interest because of the high prevalence of latent infections in the general population, the frequent reactivation in inflammatory diseases, and the immunomodulating capacity of CMV.

OBJECTIVES

To investigate the prevalence of latent CMV infection, the frequency of active CMV infection, and the immune response to CMV in patients with moderate to severe AD. Methods To detect active infection we analysed CMV antigen expression by peripheral blood mononuclear cells (PBMC) from 27 patients with moderate to severe AD in comparison with 53 healthy volunteers. We used three monoclonal antibodies recognizing different CMV-encoded antigens and immunocytological staining (alkaline phosphatase-antialkaline phosphatase technique).

RESULTS

Patients with AD had a higher mean frequency of CMV-positive PBMC: 2.25 per 10 000 vs. 0.74 per 10 000 in controls (P = 0.001) as well as a higher incidence of CMV antigenaemia: 29.6% vs. 7.5% (P < 0.01). Seropositivity for anti-CMV IgG antibodies indicated subclinical activation of latent infection. Remarkably, a clearance of CMV antigenaemia was observed during anti-eczematous treatment. Significantly higher plasma levels of tumour necrosis factor-alpha, which is involved in CMV reactivation, and interleukin-12, which is crucial for an antiviral cellular immune response, were observed in AD patients in comparison with healthy volunteers. Furthermore, a significantly enhanced frequency of circulating activated HLA-DR+ T cells especially in CMV-seropositive AD patients (19.3% vs. 13.5% in seronegative AD patients vs. 10.2% in controls) suggested that the active CMV infection triggers a cellular immune response. This was also supported by a high frequency of CMV-specific interferon-gamma-producing T cells in CMV-seropositive patients with AD.

CONCLUSIONS

Our data suggest that active, subclinical CMV infection is more frequent in patients with moderate to severe AD and may have immunopathophysiological relevance.

Psoriasis

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

Cytokine network in autoimmune haemolytic anaemia: new probable targets for therapy

AIMS

Several immunological mechanisms seems to be similar in cancer and autoimmune disease. Studying interleukins production and proliferative response in autoimmune haemolytic anaemia (AIHA), it is possible to observe that manipulation of IL-10/IL-12 balance can have profound effect on the incidence of autoimmune diseases and this might be useful for the control of AIHA.

METHODS

Respective role of IL-2, IL-4, IFN-gamma, IL-10 and IL-12 in non-cancer associated AIHA were investigated by examining the spontaneous and mitogen-induced (OKT3 or LPS) synthesis of these cytokines in PBMC cultures by ELISA methods.

RESULTS

Our results affirmed that AIHA is a disease which exhibited an increased basal synthesis of IL-4 and decreased levels of IFN-gamma by AIHA PBMC compared with controls and then there is a basal increase of Th2 cytokines. Th1-type cytokine decrease in basal state occurred in parallel with an increase of constitutive IL-10 production and a IL-12 decrease.

CONCLUSIONS

Decreased production of Th1-type cytokines and the production of autoantibodies in AIHA may be secondary to the imbalance between IL-10 and IL-12 and then the neutralisation of IL-10 may be efficacious in diminishing the clinical pathology associated with Th2 subset prevalence. In the same way, the treatment with IL-12 could offer a second and independent level of blockade against the consequences of the over B cell activation associated with AIHA and sometimes with cancer.

Ultraviolet-B irradiation decreases IFN-gamma and increases IL-4 expression in psoriatic lesional skin in situ and in cultured dermal T cells derived from these lesions

Type 1 cytokine producing T cells play an important role in the pathogenesis of psoriasis. Ultraviolet-B (UVB) irradiation is effective in the treatment of this disease. In normal skin, UVB causes a change in dermal microenvironment, leading to a decrease of IFN-gamma expressing type 1 T cells and a concurrent increase of IL-4 expressing type 2 T cells. The aim of this study was to show whether UVB irradiation causes a like-wise shift of type 1 and type 2 responses in psoriatic skin. For this purpose, biopsies were obtained from the lesional skin of psoriatic patients before, 2 days and 14 days after a single exposure to 4 MED UVB. Sections from these biopsies were immunostained (CD3, IFN-gamma and IL-4) or RNA was extracted and analyzed for the expressions of IFN-gamma and IL-4 by PCR. In addition, primary cultures of T cells from dermal cell suspensions were stained intracellularly for IFN-gamma and IL-4 expression and CD4+ and CD8+ T subsets were analyzed by flow cytometry. IFN-gamma was abundantly expressed in situ before irradiation and decreased in all patients after UVB irradiation, whereas IL-4 expression was variably expressed before irradiation and increased in different degrees after irradiation. Cytokine mRNA expressions determined by PCR showed a clear decrease of IFN-gamma and increase of IL-4 following UVB irradiation. Both CD4+ and CD8+ dermal T cells were found to produce less IFN-gamma and more IL-4 following UVB irradiation as determined by flow cytometry. Decrease in IFN-gamma expression and increase in IL-4 expression of dermal T cells in psoriatic lesions after UVB irradiation may lead to decrease in local immunoreactivity. These changes could be part of the therapeutic effects of UVB on psoriasis.

Keratinocyte unresponsiveness towards interleukin-10: lack of specific binding due to deficient IL-10 receptor 1 expression

Whereas the effects of interleukin (IL)-10 on several epithelial cell types are well established the capability of IL-10 to target keratinocytes (KC) is still a matter of debate. This, however, is of considerable importance, as IL-10 is a major anti-inflammatory, immunosuppressive cytokine with impact on the cutaneous homeostasis. Recently, IL-10 therapy has been proven to be clinically effective in psoriasis. Response to therapy is associated with normalization of typical parameters of keratinocyte pathology, but it is unclear whether this results from direct or indirect (secondary) effects. The purpose of the present study was to further investigate direct effects of IL-10 on keratinocytes and to address the reason for potential IL-10 unresponsiveness using keratinocytes such as the cell line HaCaT as well as primary foreskin keratinocytes. Using real time RT-PCR we demonstrated that IL-10 is neither able to induce its typical early gene product suppressor of cytokine signalling (SOCS) 3 nor to modulate the interferone (IFN)-gamma-induced expression of SOCS 1 and 3. Although flow cytometric analyses showed binding of biotin labelled IL-10 to HaCaT cells, blocking experiments indicated that this resulted from unspecific binding. Moreover, scatchard plot analyses excluded specific binding to primary KC and HaCaT cells. Finally, real time mRNA analyses and Western blot experiments demonstrated that the absence of any specific binding results from the absence of clear IL-10R1 (alpha chain) expression, whereas the IL-10R2 (beta chain) is strongly expressed. Our data indicates that IL-10 unresponsiveness of keratinocytes could be explained by the lacking of functional IL-10 receptor expression and suggest that any IL-10 effects on these cells observed are indirectly mediated.

[Psoriasis therapy with biologicals]

"Biologicals" represent a new group of compounds which are produced by using methods of biotechnology. They mainly include monoclonal antibodies, fusion proteins and recombinant proteins. The development of biologicals is based on the knowledge derived from pathogenetic studies in psoriasis which have focussed on targeting cell- or mediator-systems relevant for the disease. In this regard, the inactivation of soluble mediators such as tumor-necrosis-factor alpha, the blockade of receptors for cytokines such as interleukin 2, and the interference with T cell activation by antigen presenting cells are all of increasing importance. Recombinant cytokines such as interleukins 4 or 10 are able to modulate the immunological balance. Blockade of adhesion molecules to prevent extravasation of inflammatory cells is a new strategy under development. This article reviews about the current knowledge of psoriasis therapy with biologicals.

[Latest aspects in psoriasis pathogenesis]

During recent years the understanding of psoriasis pathogenesis has changed essentially. Psoriasis is now considered as a T cell mediated inflammation of the skin. Genetic predisposition and microbial environment cooperate in the induction of an antigen-specific T cell mediated immune response which may persist lifelong. The phenotype of the psoriatic inflammation is determined by the particular functional differentiation of the pathogenic T cells. The progress in understanding the pathogenesis of psoriasis has identified T cells and T cell-derived cytokines as targets for causal treatment approaches that in the near future will change psoriasis therapy considerably.

Beneficial effects of fumarate therapy in psoriasis vulgaris patients coincide with downregulation of type 1 cytokines

BACKGROUND

Fumarates have been shown to be effective in psoriasis vulgaris.

OBJECTIVES

To find out whether successful therapy is associated with modulation of cytokines.

METHODS

We determined interferon (IFN)-gamma, interleukin (IL)-4 and IL-10 secretion capacities of peripheral blood mononuclear cells (PBMC) after phytohaemagglutinin stimulation, and IL-12p70 and IL-10 secretion capacities of PBMC after endotoxin stimulation in psoriasis vulgaris patients during treatment with fumarates. In a cohort study, 12 patients (five men, median age 50 years; seven women, median age 46 years) with psoriasis vulgaris were followed during 24 months of fumarate treatment. In addition, we followed 14 healthy controls (six men, median age 31 years; eight women, median age 29 years) without skin diseases during 12 months to investigate possible changes in the cytokine secretion capacity of PBMC as a result of seasonal changes. Disease activity in patients was determined by Psoriasis Area and Severity Index (PASI) score. Blood was collected for measurement by enzyme-linked immunosorbent assay of cytokine levels after stimulation of PBMC.

RESULTS

Within 6 months of fumarate treatment, the mean +/- SD PASI score had decreased to 22 +/- 9% of its initial value. These beneficial effects coincided with lymphocytopenia and a significant (P < 0.05) downregulation of IFN-gamma expression by circulating blood cells, followed by a significant downregulation of IL-4 expression. Notably, production of the cytokine synthesis inhibitor IL-10 by PBMC was unchanged.

CONCLUSIONS

The beneficial effects of fumarates may be attributed to their downregulatory action on type 1 cytokines.

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

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

11. Allergic and immunologic diseases of the skin

Many skin diseases have an inflammatory or immune component, and anti-inflammatory drugs comprise a major portion of a dermatologist's therapeutic armamentarium. Although causes of most of these diseases remain obscure, mechanisms of lesion formation and explanations for symptoms are increasingly well documented. These developments, coupled with the expected availability of novel selective immunomodulatory agents, herald a new era for immunodermatology. Patients with psoriasis, allergic contact dermatitis, atopic dermatitis, urticaria, and autoantibody-mediated blistering diseases are among those who are likely to benefit from advances in the understanding of disease pathogenesis and the emergence of immunotherapeutics.

Neue Entwicklungen in der systemischen Psoriasistherapie

The current standard systemic therapeutic modalities for psoriasis have many potential side effects. Progress made in the understanding of the pathophysiology of psoriasis as a T-cell-mediated dermatosis provide options for new more precise therapeutic approaches. These immunological therapeutic strategies involve the inhibition/depletion of activated T-lymphocytes, the inhibition of antigen presentation and thus the regulation of T-cell activation, the inhibition of adhesion of inflammatory cells, the inhibition of effects of proinflammatory mediators and the administration of antiinflammatory cytokines. This article summarizes these new systemic therapeutic approaches. Clinical results in the early studies have been mixed. In the next years further results of phase II- and phase Ill-studies may be expected, which should allow better assessment of the potential of those particular approaches. Some of these approaches could lead to the approval of new drugs to treat psoriasis and to enhance or replace already existing therapeutic options. Furthermore results of therapeutic experiments should contribute to a better understanding of the disease. As we learn which mechanisms are more or less important for the disease, we will be better able to plan intervention strategies.

Cytokines: interleukin and interferon therapy in dermatology

Cytokines are highly potent biologically active proteins that play an essential role in intercellular communication. They are vital to the mediation and regulation of inflammatory and specific immune reactions as well as to nonimmunological processes. Several cytokines are already used for the treatment of malignant, inflammatory and infectious skin diseases. This in particular includes certain interleukins (ILs) and interferons (IFNs). Whereas some cytokine therapies are already approved and well established, such as IFN-alpha and IL-2 (approved in the USA) for melanoma, others are in the early stages of development and are used in explorative trials (e.g. IL-4 and IL-10 in the treatment of psoriasis). It is likely that some of the new approaches currently under investigation will actually lead to both the registration of new drugs for dermatological treatment, and to supplementation of existing therapeutic options. The aim of this review is to give an overview on the current state of cytokine therapy in dermatology.

Human leukocyte antigen-DR expression on peripheral monocytes as a predictive marker of sepsis during acute pancreatitis

INTRODUCTION

The mortality associated with severe acute pancreatitis is still high, and death in the later stage of the disease is chiefly due to bacterial infection and sepsis. However, objective parameters for the risk of sepsis in acute pancreatitis have not been established.

AIM

To investigate the value of human leukocyte antigen-DR (HLA-DR) on peripheral monocytes for predicting the development of sepsis during acute pancreatitis.

METHODOLOGY

The expression of HLA-DR on peripheral monocytes was measured in 64 patients by flow cytometry at admission and 7 and 14 days after the onset of acute pancreatitis. Twenty-eight patients with severe acute pancreatitis and 36 with mild acute pancreatitis, as determined by the Atlanta classification, were enrolled.

RESULTS

Six patients had sepsis, and two of them died during the hospital stay. At admission, the percentage of HLA-DR-expressing cells in the monocyte population was significantly lower in the patients who had sepsis in the later course than in the patients who did not have sepsis. A percentage lower than 80% at admission was observed in 17 patients, and the patients who had persistently low percentages of HLA-DR-expressing monocytes throughout the observation period had sepsis in the later clinical course, whereas the patients in whom expression recovered to the normal range were spared the development of sepsis.

CONCLUSION

In acute pancreatitis, the low percentage of HLA-DR-expressing cells in the monocyte population is a reliable predictor of the development of sepsis. Monitoring of monocyte HLA-DR expression may be a useful marker for identifying the patients who are at high risk of sepsis in acute pancreatitis.

Cytokines in multiple sclerosis: methodological aspects and pathogenic implications

Multiple sclerosis (MS) is one of the leading causes of disability among young adults of Caucasian origin. One hundred and fifty years after the first description of the disease, the cause of MS remains unknown. Ironically, the few hypotheses concerning MS pathogenesis that are valid today were first proposed over a hundred years ago. However, equipped with the advanced technology of molecular biology and imaging systems, we are at present progressively uncovering dues to understanding the pathogenesis of the disease. It is dearly evident that aberrant immune responses occur in MS, and it is likely that the spectrum of cytokines produced decisively influences disease outcome. The detrimental consequences of IFN-gamma and the beneficial effects of IFN-beta treatment in MS support this hypothesis. However, there are still major gaps in our knowledge of the involvement of cytokines in MS. Numerous studies have addressed the question of cytokine levels in MS, often with conflicting results; elevated, normal and decreased levels of almost all cytokines have been reported. This scenario most probably reflects methodological dilemmas as well as the complex biology of cytokines. Here we focus on possible reasons for the discrepancies of results reported on cytokines in MS and summarize findings obtained in particular by the application of enzyme-linked immunospot (ELISPOT) assays to cytokine studies in MS.

Cytokines, apoptosis and cachexia: the potential for TNF antagonism

The cachexia syndrome is characterised by progressive weight loss and depletion of lean body mass and has long been recognised as a poor prognostic sign. Whilst the clinical features of the wasting process are readily apparent, its pathogenesis is complex and poorly understood. There is increasing evidence that the immune system, in particular inflammatory cytokines, may play an important role in the development of cachexia. The cytokine considered to be the most relevant to this process is tumor necrosis factor alpha (TNF), although other mediators such as interleukin (IL) 1, IL-6 and interferon gamma have also been implicated. Apoptosis represents a potential pathway by which wasting can occur in chronic diseases. Cytokines and their corresponding receptors are known to be important regulators of cell death. Apoptosis has been demonstrated in the skeletal muscle of patients with chronic heart failure (CHF) and is thought to be partly responsible for the significant impairment of functional work capacity associated with this condition. An understanding of the mechanisms that regulate muscle protein breakdown is essential for the development of strategies for treating or even preventing muscle cachexia in patients. It is the aim of this article to review the role of inflammatory cytokines, particularly TNF, in the pathogenesis of wasting and also the potential for anti-cytokine therapy. Although this review will concentrate predominantly on the syndrome of CHF, other chronic illnesses such as liver disease, cancer, and sepsis will also be discussed.

Role of immunomodulation in diseases responsive to phototherapy

Within the last two decades phototherapy has turned out to be a major therapeutic strategy in dermatology and thus has significantly influenced the treatment of many dermatoses. The goals of therapeutic photomedicine are the suppression of ongoing disease processes and, more importantly, the prevention, modulation, or abrogation of pathogenic mechanisms causing the disease. Therapeutic photomedicine has been largely empirical and most of it is still empirical today. However, parts of it are already based on the advances in photoimmunology and molecular biology. Although, we are far from a detailed understanding of the mechanisms underlying phototherapy, there is increasing evidence that phototherapy acts via modulation of the immune system. Most of the effects of both ambient and therapeutic ultraviolet radiation are immunosuppressive in nature.

Effect of interleukin-10 on the production of tumor necrosis factor-alpha by peripheral blood mononuclear cells from patients with chronic heart failure

Chronic heart failure (HF) is a state of inflammatory immune activation characterized by elevated circulating levels of tumor necrosis factor-alpha (TNF-alpha). Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that inhibits TNF-alpha production and lessens endotoxin bioactivity. It is not known whether IL-10 reduces lipopolysaccharide (LPS) stimulated TNF-alpha production of peripheral blood mononuclear cells (PBMCs) from patients with chronic HF. PBMCs were isolated from 15 patients with chronic HF (New York Heart Association functional class 3.0 +/- 0.2, left ventricular ejection fraction 30 +/- 2%, peak oxygen consumption 18.1 +/- 0.8 ml/kg/min) and 15 healthy control subjects and stimulated with 1 and 10 ng/ml LPS for 24 hours with or without prior addition of IL-10 (10 ng/ml). TNF-alpha was quantified in cell-free supernatants by an enzyme-linked immunosorbent assay. TNF-alpha, soluble TNF receptors, IL-10, and LPS were quantified in plasma. LPS stimulated TNF-alpha production was highest in those patients in New York Heart Association class II (p <0.01 vs New York Heart Association class III and IV, p <0.001 vs control subjects). IL-10 reduced PBMC TNF-alpha production in all stimulated samples at 1 and 10 ng/ml LPS (mean reduction 43% at 1 ng/ml, p <0.01 and 55% at 10 ng/ml, p <0.0001). The percentage reduction in TNF-alpha release did not differ significantly between patients and control subjects or with respect to severity of chronic HF or baseline immune parameters. Independently of clinical severity, IL-10 profoundly inhibits TNF-alpha release from PBMCs isolated from patients with chronic HF. IL-10 is, therefore, a potential therapy for use in chronic HF associated with inflammatory immune activation.

Decreased IL-10 production by psoriatic peripheral blood mononuclear cells stimulated with streptococcal superantigen

The strong association of acute guttate psoriasis and streptococcal throat infection has suggested a role for streptococcal antigens in the pathogenesis of psoriasis. We have reported that psoriatic peripheral blood mononuclear cells (PBMCs) showed significantly lower responses to cytoplasmic membrane-associated protein (CAP) isolated from group A beta-hemolytic streptococci, a kind of streptococcal superantigen. The objectives were to evaluate the abnormal cytokine production by psoriatic PBMCs to streptococcal superantigen, CAP. We compared the production of four different cytokines, i.e. IL-4, IL-5, IL-10, and IFN-gamma, by PBMCs between psoriatic patients and healthy controls after stimulation with CAP or two different staphylococcal superantigens, staphylococcal enterotoxin A (SEA) or E (SEE). When PBMCs were stimulated with CAP, the production of IL-10 was significantly lower by psoriatic PBMCs than by those from healthy controls, whereas those of IL-4, IL-5, or IFN-gamma were not different between the two groups. Such a significant decrease in IL-10 production by psoriatic PBMCs was not observed when they were stimulated with staphylococcal superantigens. Flow cytometric analysis of intracytoplasmic IL-10 demonstrated defective IL-10 production by psoriatic PBMCs in both CD3+ T cells and CD14+ monocytes. There was a significant positive correlation between IFN-gamma production by PBMCs and the proliferation of Vbeta8+ T cells preferentially stimulated by CAP. These data demonstrating the defective IL-10 production by psoriatic PBMCs stimulated with streptococcal superantigen seem to explain why only psoriatic patients evolve sustained and Th-1 deviated skin lesions after streptococcal upper respiratory infection.

Novel therapies for psoriasis

The T cell-driven immunopathogenesis of psoriasis has been well recognized since cyclosporine first revolutionized the treatment of psoriasis 20 years ago. Almost all investigative and clinical research subsequently, has concentrated on elucidating the specifics of antigen presentation, T cell interaction and the production of specific cytokines. The role of the keratinocyte, previously thought to be the primary target cell in psoriasis pathogenesis, has been relegated to a secondary role and the mechanism of action of systemic methotrexate in psoriasis has been challenged, the primary role of the T lymphocyte is now well known. While psoriasis has traditionally been treated "ab initio" with topical medications (corticosteroids, vitamin D(3), and retinoid derivatives), either singly, in combination, or with ultraviolet B (UVB) or psoralens and ultraviolet A (PUVA) therapy, the role of systemic medications has assumed greater prominence. Thus, three systemic medications currently are approved worldwide for the treatment of moderate to severe forms of psoriasis, namely cyclosporine, methotrexate and acitretin. The first two are likely to give significant clearing (greater than 75%) in the majority of cases, whereas acitretin is significantly less effective as monotherapy, but may approach methotrexate and cyclosporine in efficacy, if combined with PUVA or UVB phototherapy. The main limitations of these three drugs remain organ toxicity, especially hepatic toxicity with methotrexate, hypertension and nephrotoxicity with cyclosporine, and teratogenicity and mucocutaneous toxicity with acitretin. Thus, the need for more specific systemic therapy, targeting the T lymphocyte. This has become the major area of clinical research interest over the past 5 years, with the promise of longer-term disease control (improved remissions) and less organ toxicities. Currently, there are over 15 of these "biologic" drugs in various stages of development and clinical trials, either by the subcutaneous, intramuscular or intravenous route. The three main variables are the rapidity of onset, percentages of improvement and remission rates. Without exception, these new systemic agents appear to be remarkably free of systemic organ toxicities (liver, renal, bone-marrow, etc.), with adverse effects being limited to mild flu-like symptoms with the anticipated increase in infections (e.g., herpes simplex) being either equal to placebo or only marginally increased. Not all these agents under evaluation give clinical responses equal to methotrexate or cyclosporine (75% or greater clearing in 75% of cases). In addition, response rates may be slower with some therapies versus others. However, the need for intermittent administration even by the injectable route, longer remissions, lack of systemic organ toxicities and the potential for safer usage in females of child-bearing age, make a compelling argument for widespread acceptance by both patients and the dermatological community. Other modalities under clinical evaluation include vitamin D and retinoid drugs, topically and systemically, with effects on nuclear receptors, as well as more specific wavelengths (308 to 311 nm) of UVB phototherapy with application for more localized forms of psoriasis. For the 2 to 3% of the worldwide population of patients with psoriasis the future has never looked brighter.

Cytokine therapy in dermatology

Cytokines have been in the focus of scientific interest for some years now. Analysing their expression permitted a better understanding of the pathogenesis of various diseases, including in dermatology. Moreover, they are now far beyond the stage when they were of interest only to the pathophysiological research sector: some cytokine therapies are already being employed as part of the clinical practice. In fact, several cytokines are used for the treatment of malignant, inflammatory and infectious skin diseases. Their stage of development ranges from advanced, already approved and well established therapies (e.g. IFN-alpha and IL-2 for melanoma) to early explorative trials (e.g. IL-4 and IL-10 for psoriasis). Some of the new approaches currently under investigation will actually lead to registration of new drugs for dermatological treatment and to supplement existing therapeutic options. Beside this, the results of clinical trials with cytokines are significantly contributing to our understanding of the pathophysiology of diseases. They will give a better insight into which mechanisms play a greater or lesser part in their development and may generate momentum for still better targeted pharmacological approaches. Here we would like to give an overview about the current stage of cytokine therapy and the prospects for dermatological indications. The terminology and immunobiology of cytokines are also briefly discussed, since for a sensible interpretation of the relevant findings a basic knowledge of these biologically highly active messenger substances is essential.

Immunomodulation by interleukin-10 therapy decreases the incidence of relapse and prolongs the relapse-free interval in Psoriasis

The ability of interleukin-10 therapy to reduce the severity of exacerbated psoriasis has been demonstrated recently. Considering the immunobiologic properties of this cytokine we investigated the effects of long-term interleukin-10 application on the immune system and duration of psoriasis remission. We performed a placebo-controlled, double-blind, phase II trial using interleukin-10 in patients with chronic plaque psoriasis in remission. Patients received subcutaneous injections with either interleukin-10 (10 microg per kg body weight; n = 7) or placebo (n = 10) three times per week until relapse or study termination after 4 months. The treatment was well tolerated. In the placebo group almost all patients (90%) showed a relapse during the observation period. In contrast to this, only two of seven patients (28.6%) relapsed in the interleukin-10-treated group. Kaplan-Meier analysis revealed a significantly lower relapse incidence in the interleukin-10 than in the placebo group (p = 0.02). The mean relapse-free interval time was 101.6 +/- 12.6 d in the interleukin-10 group in comparison with 66.4 +/- 10.4 d in the placebo group. Immunologic activity of interleukin-10 application was indicated by an increase in soluble interleukin-2 receptor plasma levels and higher ex vivo interleukin-4 secretion capacities. Remarkably, a significant negative correlation was demonstrated between the interleukin-4 secretion capacity and Psoriasis Area and Severity Index score (r = -0.36, p < 0.01). Our data suggest that interleukin-10 therapy is immunologic effective, decreases the incidence of relapse and prolongs the disease-free interval in psoriasis. Its value should be further determined in larger trials and for the prevention of re-exacerbation of other inflammatory disorders with a similar immunologic profile.

Promoter region polymorphism of the CD14 gene (C-159T) is not associated with psoriasis vulgaris

Keratinocytes of psoriatic skin show aberrant expression of membrane-bound CD14 (mCD14). In addition, soluble CD14 (sCD14) is elevated in the sera of psoriatic patients. The mechanisms leading to increased CD14 expression and secretion in psoriasis are poorly understood. A bi-allelic polymorphism in the promoter region of the CD14 gene controls CD14 expression on monocytes and sCD14 levels in the sera of healthy subjects. In this context, we explored the CD14 promoter region genotypes of 63 Finnish patients with psoriasis and 126 non-psoriatic controls using a new ARMS-PCR method. No differences in the CD14 genotype frequencies were found between the groups. Thus, our results suggest that the enhanced CD14 expression in psoriasis is not attributable to functional variants of CD14 (-159C/T).

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

Psoriasis vulgaris is the most prevalent T-cell-mediated inflammatory disease in humans. The pathogenesis of psoriasis is linked to activation of several types of leukocytes that control cellular immunity and to a T-cell-dependent inflammatory process in skin that accelerates the growth of epidermal and vascular cells in psoriasis lesions. Critical steps in immunologic activation include Langerhans cell maturation (activation), T-cell activation, differentiation and expansion of type 1 T cells, selective trafficking of activated T cells to skin, and induction of an inflammatory cytokine and chemokine cascade in skin lesions. In turn, each of these steps offers an opportunity for intervention with engineered biologic therapeutics.

CD3+CD56+ NK T cells are significantly decreased in the peripheral blood of patients with psoriasis

Psoriasis is a chronic, inflammatory, hyperproliferative skin disease, in which autoimmunity plays a great role. Natural killer T cells (NK T cells), are suggested to be involved in the pathogenesis of different autoimmune diseases. To examine the involvement of CD3+CD56+ NK T cells in the pathogenesis of psoriasis, we investigated the lymphocyte subpopulations obtained from blood samples of psoriatic patients before and after treatment, and of healthy controls, using two-colour flow cytometry. We found no significant differences between total T cells, total B cells, T helper cells, T cytotoxic cells and NK cells in patients with psoriasis before and after treatment and in controls. Increased percentage of memory T cells and decreased percentage of naive T cells was detected in psoriatic patients compared to controls, but these changes were not statistically significant. The CD3+CD56+ cells of psoriatic patients were significantly decreased relative to controls. The percentage of CD3+CD56+ cells increased after different antipsoriatic therapies, but remained significantly lower than those found in controls. CD3+CD56+ cells of healthy controls were capable of rapid activation, while in psoriatic patients activated NK T cells were almost absent. The decrease in the number of CD3+CD56+ cells may represent an intrinsic characteristic feature of patients with psoriasis, which is supported by the fact that after treatment NK T cells do not reach the values found in controls. In conclusion our results suggest that CD3+CD56+ NK T cells could be actively involved in the development of Th1 mediated autoimmune diseases.

Novel immunotherapies for psoriasis

New insights into the pathophysiology of psoriasis have suggested possibilities for targeted therapeutic intervention. Several novel, systemic immunomodulatory therapies are currently in clinical development and results of recent clinical trials are remarkable. These include approaches targeting antigen presentation and costimulation, T-cell activation and leukocyte adhesion, the action of proinflammatory mediators and the administration of anti-inflammatory cytokines. These trials contribute to our further understanding of the disease, indicating which mechanisms play a greater or lesser part in its development. Moreover, they will lead to new therapeutic options. If psoriasis is considered as a visible model disease for T-cell-mediated disorders characterized by a type-1 cytokine pattern these recent findings might have a more general impact on the treatment of autoimmune disorders.

Promoter polymorphisms of the genes encoding tumor necrosis factor-alpha and interleukin-1beta are associated with different subtypes of psoriasis characterized by early and late disease onset

The psoriatic inflammatory process is characterized by an overexpression of pro-inflammatory cytokines such as tumor necrosis factor-alpha and interleukin-1beta compared with a relative deficiency of anti-inflammatory factors such as interleukin-10 and the interleukin-1 receptor antagonist (interleukin-1Ra). Gene polymorphisms that affect cytokine production may contribute to the disease-associated cytokine imbalance and influence susceptibility to psoriasis. Here, we investigated the relationship between polymorphisms in the genes encoding for tumor necrosis factor-alpha (G-238A, G-308A), interleukin-1beta (C-511T, T+3953C), and interleukin-1Ra (intron 2), and cytokine production in peripheral blood mononuclear cells of healthy donors, and analyzed the distribution of these polymorphisms in patients with psoriasis vulgaris (n = 231) and healthy controls (n = 345). Carriage of tumor necrosis factor A-238 allele 2 (-238*A) was associated with increased production of tumor necrosis factor-alpha in response to lipopolysaccharide in vitro, and with early onset disease (< 40 y), especially in male patients with psoriasis [32% vs 7% in male controls; odds ratio = 6.78, 95% confidence interval = (3.18-15.15), p(adjusted) = 2 x 10(-7)]. Carriage of the interleukin-1B-511*1 (-511*C) homozygous genotype was associated with increased production of interleukin-1Ra in response to lipopolysaccharide and interleukin-10, and with late onset psoriasis [> or = 40 y; 61% vs 44% in controls; odds ratio = 2.04, 95% confidence interval = (1.19-3.53), p(adjusted) = 0.0419]. These findings indicate that gene polymorphisms associated with altered cytokine responses in vitro may modify age of onset of psoriasis. They also provide further evidence that patients with early and late onset psoriasis differ in their genetic background.

Interleukin-10 inhibits ischemic and cisplatin-induced acute renal injury

BACKGROUND

Acute renal failure (ARF) is caused by ischemic and nephrotoxic insults acting alone or in combination. Anti-inflammatory agents have been shown to decrease renal ischemia-reperfusion and cisplatin-induced injury and leukocyte infiltration. Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that inhibits inflammatory and cytotoxic pathways implicated in acute renal injury. Therefore, we sought to determine if IL-10 inhibits acute renal injury.

METHODS

The effects of IL-10 were studied in mice following cisplatin administration and bilateral renal ischemia-reperfusion, in a rat model of renal transplantation, and in cultured mouse cortical tubule cells.

RESULTS

IL-10 significantly decreased renal injury following cisplatin administration and following renal ischemia/reperfusion. Delay of IL-10 treatment for one hour after cisplatin also significantly inhibited renal damage. IL-10 and alpha-melanocyte stimulating hormone (alpha-MSH) increased recovery following transplantation of a kidney subjected to warm ischemia. To explore the mechanism of action of IL-10, its effects were measured on mediators of leukocyte trafficking and inducible nitric oxide synthase (NOS-II). IL-10 inhibited cisplatin and ischemia-induced increases in mRNA for tumor necrosis factor-alpha (TNF-alpha), intercellular adhesion molecule-1 (ICAM-1), and NOS-II. IL-10 also inhibited staining for markers of apoptosis and cell cycle activity following cisplatin administration, and nitric oxide production in cultured mouse cortical tubules.

CONCLUSIONS

IL-10 protects against renal ischemic and cisplatin-induced injury. IL-10 may act, in part, by inhibiting the maladaptive activation of genes that cause leukocyte activation and adhesion, and induction of iNOS.

Psoriasis. Immunopathology and immunomodulation

Biologics in development for the treatment of moderate to severe plaque-type psoriasis are discussed in this article. Immunomodulators used as therapeutic, pathogenic probes will continue to identify targets that play primary roles in the pathogenesis of psoriasis.

HLA-G: a shield against inflammatory aggression

Recent developments in the field of HLA-G research have revealed that, besides its involvement during pregnancy, HLA-G is expressed in peripheral tissues during pathological processes, such as viral infections, malignancies and organ transplantation. Here, we discuss recent findings regarding the influence of HLA-G on the T helper (Th) cytokine balance (favoring Th2-type responses), and the expression of HLA-G during chronic, cutaneous inflammatory diseases, such as psoriasis and atopic dermatitis. We propose a novel role for HLA-G as a tissue-protective molecule in inflammatory responses.

IL-10 improves skin disease and modulates endothelial activation and leukocyte effector function in patients with psoriatic arthritis

Psoriatic arthritis (PsA) provides an ideal disease model in which to investigate the bioactivities of potentially therapeutic cytokines at multiple sites of tissue inflammation. We investigated the effects of IL-10, an antiinflammatory cytokine, given s.c. for 28 days in a double-blind, placebo-controlled study in PsA patients. Synovial/skin biopsies, peripheral blood leukocytes, articular magnetic resonance images, and clinical disease activity scores were obtained sequentially. Modest, but significant clinical improvement in skin, but not articular disease activity scores with only minor adverse effects was observed. Type 1, but not type 2 T cell cytokine production in vitro was suppressed in human rIL-10 compared with placebo recipients. Similarly, monokine production in vitro was reduced, whereas serum soluble TNFRII levels were elevated, indicating suppression of monocyte function. Decreased T cell and macrophage infiltration in synovial tissues was accompanied by reduced P-selectin expression. Moreover, suppressed synovial enhancement on magnetic resonance imaging and reduced alpha(v)beta(3) integrin expression on von Willebrand factor(+) vessels were observed. Together these data demonstrate that a short course of IL-10 modulates immune responses in vivo via diverse effects on endothelial activation, and leukocyte recruitment and effector function. Such biological changes may result in clinically meaningful improvement in disease activity.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Efficacy and safety of infliximab monotherapy for plaque-type psoriasis: a randomised trial

BACKGROUND

Currently available treatments for moderate to severe psoriasis are either incompletely effective in some patients, or are associated with toxic effects. Since tumour necrosis factor alpha (TNF-alpha) is thought to have a role in the pathogenesis of psoriasis, we did a double-blind, randomised trial to assess the clinical benefit and safety of infliximab-a monoclonal antibody against TNF-alpha.

METHODS

33 patients with moderate to severe plaque psoriasis were randomly assigned intravenous placebo (n=11), infliximab 5 mg/kg (n=11), or infliximab 10 mg/kg (n=11) at weeks 0, 2, and 6. Patients were assessed at week 10 for the primary endpoint (score on the physician's global assessment [PGA]). Analysis was by intention to treat.

FINDINGS

Of the 33 patients enrolled, three dropped out. Nine of 11 (82%) patients in the infliximab 5 mg/kg group were responders (good, excellent, or clear rating on PGA), compared with two of 11 (18%) in the placebo group (difference 64% [95% CI 20-89], p=0.0089), and ten of 11 (91%) patients in the infliximab 10 mg/kg group were responders (difference from placebo 73% [30-94], p=0.0019). The median time to response was 4 weeks for patients in both infliximab groups. There were no serious adverse events, and infliximab was well tolerated.

INTERPRETATION

In this controlled trial, patients receiving the anti-TNF-alpha agent infliximab as monotherapy experienced a high degree of clinical benefit and rapid time to response in the treatment of moderate to severe plaque psoriasis compared with patients who received placebo. These findings suggest that TNF-alpha has a pivotal role in the pathogenesis of psoriasis.

Advances in systemic therapy for psoriasis

Severe cases of psoriasis and psoriasis arthritis require systemic treatment. Although a number of established drugs are in clinical use, there is a need for new compounds with an improved risk-benefit ratio with a major emphasis on long-term safety. Furthermore, patients with moderate psoriasis ask for systemic drugs to make therapy easier and to avoid excessive local treatments. This article aims to give a brief overview about new drugs or groups of compounds together with an evaluation of their present status in the treatment of psoriasis and their future role with particular respect to efficacy, tolerability, safety and usability.

Interleukin-10 promoter polymorphism in psoriasis

Beneficial effects of interleukin-10 therapy and lower endogenous interleukin-10 formation compared with atopic dermatitis and cutaneous T cell lymphomas indicated that interleukin-10 is a key cytokine in psoriasis. The interleukin-10 promoter is highly polymorphic, with two informative microsatellites, interleukin-10.G and interleukin-10.R. In order to understand whether interleukin-10 itself is a predisposing gene for the psoriasis susceptibility we analyzed interleukin-10 promotor polymorphism in patients. The distribution of interleukin-10.G and interleukin10.R microsatellite alleles did not vary between patients (n = 78) and healthy controls (n = 80). In addition, when the psoriasis patients were stratified according to age of onset (younger than 40 y of age, or age 40 and older), no difference in allele distribution was observed; however, a clear differential distribution was revealed at the interleukin10.G locus when patients were stratified according to whether they had a positive family history of psoriasis (p = 0.04). This difference was due to an over-representation of the interleukin10.G13 allele in those patients with familial disease (40.4% vs 19.6%, Chi-square = 7.292, p = 0.007). The positive association of allele interleukin10.G13 with familial psoriasis was especially true when patients with an early onset (< 40 y of age) of the disease were compared with those patients with early onset against a nonfamilial background (39.6% vs 14.5%, Chi-square = 8.959, p = 0.003). Patients with age-of-onset of less than 40 were 4-fold [odds ratio = 3.85 (1.55--9.62)] more likely to have a psoriatic family background if they carried this interleukin10.G13 allele. These data suggest that the interleukin-10 locus contributes to the heritability of psoriasis susceptibility.

Effects of Systemic Interleukin-10 Therapy on Psoriatic Skin Lesions: Histologic, Immunohistologic, and Molecular Biology Findings

Interleukin-10 is an important anti-inflammatory and immunosuppressive cytokine with major impact on several immune reactions, including regulatory mechanisms in the skin. Recently, we performed a phase II trial in psoriatic patients receiving subcutaneously interleukin-10 over 7 wk. The clinical response suggested that interleukin-10 might represent a novel anti-psoriatic drug. In order to understand better the mode of action and to elucidate the effects of systemic interleukin-10 treatment on the skin immune system, skin punch biopsies from sites different from interleukin-10 injection were analyzed. Biopsies were obtained from the patients before, at the end, and 3 wk after interleukin-10 therapy. The results are reported here. Histologic examination showed a decrease of several parameters reflecting the psoriatic disease activity as acanthosis and extension of the horny layer. Immunohistologic examination demonstrated decreasing numbers of infiltrating T cells, dermal CD1a+ cells, and a diminished proliferation of epidermal cells. Using a novel, quantitative reverse transcriptase-polymerase chain reaction approach a significant shift within the cytokine pattern was found. Interleukin-10 therapy led to a decrease of cutaneous interleukin-8 and interleukin-10 mRNA expression. Whereas no significant changes of interleukin-6, tumor necrosis factor-alpha, and interferon-gamma expression were found, interleukin-4 was strongly upregulated suggesting a shift from a type 1 towards a type 2 cytokine pattern. The changes within the local cytokine pattern seem to be disease-related, as an inverse course was found in a single interleukin-10 nonresponding patient. Our findings demonstrate considerable effects of systemic interleukin-10 application on the skin immune systems, which might contribute to the anti-psoriatic activity of interleukin-10.

IL-10 augments the IFN-gamma and TNF-alpha induced TARC production in HaCaT cells: a possible mechanism in the inflammatory reaction of atopic dermatitis

The CC-chemokine TARC is known to be a ligand for the CCR4 receptor which in turn is known to be expressed selectively on the Th(2)-subset of lymphocytes. Atopic dermatitis is generally believed to be a Th(2)-type disease, and TARC has been shown to be expressed in the skin lesions of a murine model of AD. IL-10 is an interleukine generally known for its ability to inhibit cytokine production, however it has been found to be highly expressed in the skin from AD patients. We show in this report that IL-10 is able to augment the TARC inducing effects of TNFalpha and IFNgamma in HaCaT cells, a property that may be important in the determination of the composition of the cells of the inflammation in the skin of AD patients. In addition, we show that the IL10 agonist IT 9302, a nona-peptide from the carboxylic end of IL-10, has the same effect on TARC production from HaCaT cells.

Improvement in psoriasis after intradermal administration of delipidated, deglycolipidated Mycobacterium vaccae (PVAC): results of an open-label trial

The aim of new treatments for psoriasis is to induce extended remissions with fewer side-effects. Previous studies suggest that Mycobacterium vaccae, a harmless organism prepared as a heat-killed suspension, may induce periods of remission in some psoriasis patients after intradermal administration. To assess a more potent derivative of M. vaccae, we conducted an open-label study in which 20 patients with moderate to severe psoriasis (Psoriasis Area and Severity Index of 12-35) received two intradermal inoculations of heat-killed, delipidated, deglycolipidated M. vaccae (DD-MVAC or 'PVAC') in lesion-free deltoid skin, separated by a period of 3 weeks. Twelve weeks after the injections, 13 out of 20 patients (65%) showed marked improvement in the PASI score (> 50% reduction), three were unchanged (< 25% reduction), three had worsened (> 5% increase), and one was withdrawn from the trial because of an exfoliative flare. At 24 weeks, 13 out of 19 patients continued to show > 50% improvement that, in some, lasted for 6 months or longer. Patients classified as good responders at 12 or 24 weeks were then offered additional PVAC injections after 24 weeks if the PASI reached 8 or higher. Intra-dermal administration of PVAC was safe, well tolerated, and induced clinically significant improvement in many psoriasis patients. A randomized, double-blind, controlled study is warranted.

Rheumatoid arthritis. From bench to bedside

In the last decade, basic science has unraveled in considerable detail the inflammatory and related processes ongoing in RA synovial membrane. This has translated to cytokine targeting therapies with some effect. How much more can be achieved? It may be argued that the order of improvement obtained thus far obviates further study. This ignores the potential to achieve a far greater magnitude of disease suppression. Our objective in innovating biologic therapies should now be routine achievement of American College of Rheumatology "70% responses" or disease remission and design of patient-specific therapy based on individual disease characteristics. We have not yet explored the potential contained in combination biologic approaches, particularly when different processes within the disease are targeted. Cocktails might target T cells, cytokines, and angiogenic factors, for example. These developments must also be seen in the context of the information soon to be available from the Human Genome Project. The impact of gene array analysis and similar techniques that facilitate simultaneous evaluation of thousands of gene activation events is also awaited. This, in turn, is likely to require considerable development in our use of information technology, because the volume of information will soon (or may already) be prohibitive. Finally, encompassing genomic and bioinformatic approaches should certainly challenge our basic diagnostic criteria such that it ultimately may be necessary to consider our clinical diagnoses on the basis not only of clinical phenotype but of genotype and biologic response profile. Through this rapid evolution, close communication between physician and scientist is essential.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Viral IL-10-induced immunosuppression requires Th2 cytokines and impairs APC function within the allograft

Previous reports demonstrated that retroviral mediated gene transfer of viral IL-10 (vIL-10) prolongs allograft survival by decreasing donor-specific cytotoxic T lymphocyte precursor (CTLp) and IL-2-secreting helper T lymphocyte precursor (HTLp) frequency within graft-infiltrating cells (GIC). This report now shows that vIL-10 efficacy is dependent on CD4(+) T cells, suggesting that immunosuppression may involve a switch from a Th1 to a Th2 alloresponse. In support of this, anti-IL-4 or anti-murine IL-10 (anti-mIL-10) mAbs, but not anti-IFN-gamma mAb, administered at the time of vIL-10 gene transfer prevents enhanced graft survival. Because Th switching involves APC function, GIC were examined for their ability to present alloantigen. GIC from vIL-10-treated grafts were shown to be mostly of recipient (CBA) origin, yet were unable to elicit alloproliferative responses from donor type (C57BL/6) or third party (BALB/c) responders. The inability of vIL-10-treated GIC to stimulate the MLR was not due to the generation of negative regulatory cells or the production of immunosuppressive cytokines such as IL-4, mIL-10, or TGFbeta. Using fractionated GIC subpopulations, the number of recipient type cells in the allografts was modestly reduced by vIL-10 gene transfer, while maintaining both APC phenotype and alloantigen presenting function. Conversely, after vIL-10 gene transfer, donor type GIC were unable to participate in direct alloantigen presentation. Therefore, local immunosuppression induced by vIL-10 gene transfer is CD4 T cell and IL-4 and mIL-10 dependent, and impairs direct alloantigen presentation through an alteration of donor type APC function.

Studies using leukemia inhibitory factor (LIF) knockout mice and a LIF adenoviral vector demonstrate a key anti-inflammatory role for this cytokine in cutaneous inflammation

Previous work has implicated the cytokine leukemia inhibitory factor (LIF) in cutaneous inflammation, although results have differed as to whether LIF is pro- or anti-inflammatory in this setting. We examined edema, inflammatory cell infiltration, and cytokine responses following CFA injection in the adult mouse footpad. Inflammatory cell infiltration and edema are significantly enhanced when CFA is injected in LIF knockout mice as compared with injection of wild-type littermates. Moreover, local injection of an adenoviral vector encoding LIF suppresses both measures of inflammation. In contrast, injection of an adenoviral vector encoding beta-galactosidase has no discernable effect on inflammation. In addition, comparison of the CFA responses in LIF knockout vs wild-type skin reveals that LIF is an important regulator of IL-1beta, IL-6, IL-7, IL-2Ralpha, and IFN-gamma in cutaneous inflammation. These and our previous data indicate that both endogenous and exogenous LIF are anti-inflammatory in the CFA model and that LIF is a key regulator of the cytokine cascade. The results also indicate that adenoviral gene delivery can be an effective therapeutic approach in this paradigm.

Activation of the IL-10 gene promoter following photodynamic therapy of murine keratinocytes

Photodynamic therapy (PDT), an anticancer treatment modality, has recently been shown to be an effective treatment for several autoimmune disease models including antigen-induced arthritis. PDT was found to induce the expression of IL-10 messenger RNA (mRNA) and protein in the skin, and this expression has similar kinetics to the appearance of PDT-induced suppression of skin-mediated immune responses such as the contract hypersensitivity (CHS) response. Some aspects of the UVB-induced suppression of the immune response have been linked to the induction of IL-10. IL-10 has been shown to inhibit the development and activation of Th1 cells, which are critical for many cell-mediated immune responses, including CHS. We have examined the effect of PDT and UVB irradiation on the activity of the IL-10 gene promoter and on IL-10 mRNA stability using the murine keratinocyte line, PAM 212. In vitro PDT induces IL-10 mRNA and protein expression from PAM 212 cells, which can be correlated with an increase in AP-1 DNA binding activity and activation of the IL-10 gene promoter by PDT. Deletion of an AP-1 response element from the IL-10 gene promoter was shown to abrogate the PDT-induced promoter activity indicating that the AP-1 response element is critical to IL-10 induction by PDT. In addition, PDT results in an increase in IL-10 mRNA stability, which may also contribute to the increased IL-10 expression in PAM 212 cells following PDT. In vitro UVB irradiation also results in activation of the IL-10 promoter. However, in contrast to PDT, UVB-induced activation of the IL-10 promoter is not AP-1 dependent and did not increase IL-10 mRNA stability.

Inhibition of dendritic cell differentiation by fumaric acid esters

Fumaric acid esters have proved to be effective for the systemic treatment of severe psoriasis vulgaris. These compounds have been shown to induce a Th2-like cytokine secretion pattern in T cells and to reduce keratinocyte proliferation in vitro. Dendritic cells seem to be of major importance as regulatory cells driving the psoriatic tissue reaction. Monocytes or CD34-positive myeloid progenitor cells are precursors of dendritic cells that can be generated in vitro by culture with granulocyte-macrophage colony-stimulating factor and interleukin-4. Using this model the effect of fumaric acid esters on granulocyte-macrophage colony-stimulating factor/interleukin-4-induced differentiation of monocyte-derived dendritic cells was investigated. The results of this study show that dimethylfumarate as well as methylhydrogenfumarate-calcium-salt (0.01-100 microg per ml) concentration-dependently inhibit monocyte-derived dendritic cell differentiation. This was reflected by an inhibition of CD1a, CD40, CD80, CD86, and HLA-DR expression as well as by a reduced capacity of dimethylfumarate-treated monocyte-derived dendritic cells to stimulate lymphocytes in the allogeneic mixed lymphocyte reaction. Other fumaric acid esters showed no effect on monocyte-derived dendritic cell-differentiation. At higher concentrations (30-100 microg per ml) dimethylfumarate, but not methylhydrogenfumarate calcium-salt induced apoptosis in monocyte-derived dendritic cells as measured by expression of Apo 2.7 and DNA fragmentation (TUNEL assay). These data point to a high susceptibility of the monocyte/dendritic cell system to dimethylfumarate and its main metabolite methylhydrogenfumarate. Other fumaric acid esters investigated were without effect. As the effects of fumarates on monocyte-derived dendritic cells observed occur at concentrations 20-fold lower compared with lymphocytes, our data seem to be of relevance in explaining the possible mode of action of these compounds in psoriasis.

Response of psoriasis to interleukin-10 is associated with suppression of cutaneous type 1 inflammation, downregulation of the epidermal interleukin-8/CXCR2 pathway and normalization of keratinocyte maturation

Psoriasis is a chronic inflammatory skin disease in which epidermal hyperplasia results from the release of cytokines by infiltrating type 1 T cells. Up- regulation of endogenous interleukin-10 controls type 1 skin responses in animal models; however, interleukin-10 production is low in psoriatic lesions. Consistent with an important role of interleukin-10 in psoriasis, we and colleagues have recently demonstrated clinical efficacy of subcutaneous administration of recombinant interleukin-10 to affected patients. Here, we studied the effects of interleukin-10 on disease-related inflammatory pathways. Patients were treated with recombinant interleukin-10 over 6 wk in an open-label phase II clinical trial. Tissue was obtained before and after therapy and examined by histology/immunohistochemistry, in situ hybridization, and quantitative real-time reverse transcription-polymerase chain reaction. Ten of 14 patients showed a marked reduction of the clinical disease activity. The clinical response was associated with a significant decrease of cutaneous T cell infiltration and the lesional expression of type 1 cytokines interferon-gamma and tumor necrosis factor-alpha. Interleukin-10 inhibited the epidermal interleukin-8 pathway by downregulating the expression of interleukin-8, its receptor CXCR2, and its inducer interleukin-17, and partially reversed the aberrant keratinocyte maturation defining psoriatic epidermal pathology. Remarkably, there was evidence that genetic factors are involved in the response to interleukin-10 as individual variations in the downregulation of tumor necrosis factor-alpha were related to the presence of polymorphisms in the tumor necrosis factor-alpha promoter. These data suggest that excessive production of type 1 cytokines in human skin disease can be counter-regulated by the administration of recombinant interleukin-10. Genotypic analysis may help to identify patients that will preferentially respond to interleukin-10 therapy.