Early disease intervention with guselkumab in psoriasis leads to a higher rate of stable complete skin clearance ('clinical super response'): Week 28 results from the ongoing phase IIIb randomized, double-blind, parallel-group, GUIDE study

BACKGROUND

Guselkumab is an interleukin (IL)-23 inhibitor with demonstrated efficacy in patients with psoriasis.

OBJECTIVES

Evaluate the impact of early disease intervention on clinical responses following 28 weeks of guselkumab treatment in patients with moderate-to-severe plaque psoriasis. Correlate clinical response and disease duration data with serum biomarker data.

METHODS

GUIDE is a phase IIIb randomized, double-blind, parallel-group, multicentre study of adults with moderate-to-severe plaque psoriasis. In study part 1, patients with a short disease duration (SDD [≤2 years]) or a long disease duration (LDD [>2 years]) received guselkumab 100 mg at Week (W) 0, 4, 12, and 20. Those achieving complete skin clearance at W20 and W28 were defined as a super responder (SRe). A multivariable logistic regression analysed the association between baseline factors and the likelihood of becoming an SRe. The relationship between clinical response, disease duration and serum biomarker data was assessed at W0 and 4.

RESULTS

In total, 880 patients were enrolled (SDD/LDD = 40.6%/59.4% of patients). More SDD than LDD patients achieved absolute Psoriasis Area and Severity Index (PASI) = 0 at W28 (51.8% vs. 39.4%) and were SRes (43.7% vs. 28.1% [overall 34.4%]). SDD patients also achieved PASI = 0 quicker than LDD patients (median 141 vs. 200 days). Disease duration and prior biologic use had the greatest impact on becoming an SRe, with no strong association among these independent variables. At baseline, there were no significant differences in the serum biomarker levels of IL-17A, IL-17F, IL-22 and β-defensin 2 between SDD and LDD patients, or between SRe and non-SRe patients. Guselkumab rapidly decreased these markers of systemic inflammation across all patient groups analysed at W4. Guselkumab was well tolerated.

CONCLUSIONS

Guselkumab efficacy was consistent across subpopulations, on the skin and systemically. The proportion of SRes was higher in SDD than LDD patients, indicating early treatment intervention may improve clinical outcomes.

Effectiveness, safety and quality-of-life effects of guselkumab and ustekinumab in patients with psoriasis: Week 104 results from the non-interventional, prospective, German multicentre PERSIST study

BACKGROUND

PERSIST was a prospective, non-interventional, real-world study of guselkumab and ustekinumab in adult patients with moderate-to-severe plaque psoriasis in Germany.

OBJECTIVES

To examine effectiveness, safety and quality-of-life (QoL) outcomes to Week (W) 104 of treatment with guselkumab and ustekinumab in patients with moderate-to-severe plaque psoriasis.

METHODS

Patients (≥18 years of age) received guselkumab or ustekinumab as per routine clinical practice. Outcomes to W104 were examined separately in guselkumab and ustekinumab recipients. An ad hoc exploratory analysis of outcomes with guselkumab versus ustekinumab was also performed following propensity score matching.

RESULTS

Overall, 302 and 313 patients received guselkumab and ustekinumab, respectively. Patients in both cohorts experienced improvements in disease activity and QoL that were maintained to W104, with 64.7% and 63.6% of guselkumab- and 54.6% and 64.4% of ustekinumab-treated patients achieving a Psoriasis Area and Severity Index (PASI) 90 response and a Dermatology Life Quality Index (DLQI) 0/1 score, respectively. Propensity score matching yielded well-balanced baseline characteristics except for prior biologic use, which was higher in guselkumab versus ustekinumab recipients (51.7% vs. 32.0%). Achievement of PASI ≤1 at W104 was more common in guselkumab versus ustekinumab recipients (58.7% vs. 49.7%). The W104 PASI90 response rate was 65.6% with guselkumab and 56.0% with ustekinumab; corresponding rates for PASI100 were 44.3% and 28.5%. In guselkumab recipients, response rates were higher in biologic-naïve versus biologic-experienced patients (PASI90, 77.1% vs. 53.4%; PASI100, 55.0% vs. 33.0%). A high level of response for QoL outcomes was observed for both treatments.

CONCLUSIONS

Ustekinumab and guselkumab led to improvements in physician-assessed and patient-reported outcomes that were sustained for up to 2 years, with no new safety signals identified. Following propensity score matching, greater improvements in PASI outcomes were observed with guselkumab versus ustekinumab. Improvements with guselkumab were highest in biologic-naïve patients, highlighting the value of early treatment.

Real-world evidence from the non-interventional, prospective, German multicentre PERSIST study of patients with psoriasis after 1 year of treatment with guselkumab

BACKGROUND

PERSIST was a prospective, non-interventional, long-term, German multicentre study of patients with moderate-to-severe psoriasis receiving guselkumab, an approved monoclonal antibody that binds to the p19 subunit of interleukin (IL)-23, in a real-world setting.

OBJECTIVES

Evaluation of the efficacy and safety of guselkumab, and its effect on health-related quality of life (HRQoL), in patients with moderate-to-severe psoriasis who have received 52 weeks of treatment.

METHODS

Patients (≥18 years old) were prescribed guselkumab as per routine clinical practice. End points assessed include Psoriasis Area and Severity Index (PASI), Physician's Global Assessment (PGA), target Nail Psoriasis Severity Index (NAPSI), and the Dermatology Life Quality Index (DLQI).

RESULTS

Overall, 303 patients were enrolled and treated with guselkumab. Mean disease duration was 21.0 years, and 77.2% and 51.2% of patients had received ≥1 prior conventional systemic or ≥1 prior biologic therapy, respectively. Mean PASI score decreased from 16.4 at baseline to 3.0 by Week (W) 28, and further decreased to 2.4 by W52, while the proportion of patients achieving an absolute PASI score of ≤1 increased from 1.3% at baseline, to 50.8% at W28 and to 58.4% by W52. PASI90 and PASI100 responses also showed marked improvements between W28 and W52, regardless of biologic treatment history. Clearance of psoriatic skin was observed in difficult-to-treat areas, with the percentage of patients achieving a PGA score ≤1 increasing between W28 and W52. Guselkumab improved HRQoL; mean DLQI score decreased from 13.7 at baseline to 2.8 by W28, and further decreased to 2.4 by W52. At W52, 64.6% of patients achieved a DLQI score ≤1. The cumulative probability of drug survival was 92.4% at W52.

CONCLUSIONS

Guselkumab is efficacious and well tolerated regardless of previous biologic therapies, comorbidities or psoriasis manifestation in difficult-to-treat areas. No new safety signals were observed.

Identification of novel in vitro test systems for the determination of glucocorticoid receptor ligand-induced skin atrophy

Topical glucocorticoids (GCs) demonstrate good anti-inflammatory effects but are limited by their side effect potential, with skin atrophy being the most prominent one. Thus, determining the atrophogenic potential of novel compounds is important. The aim of this study was to establish an in vitro skin atrophy model. A screening cascade was applied and GCs with a known atrophogenic potential were used as tool compounds. Five rodent and human cutaneous cell types/cell lines and 2 human skin equivalents were tested. Known and suspected atrophy markers related to collagen metabolism and epidermal thickness were measured. Altogether, a combination of 7 different cellular assays with up to 16 markers each were investigated. A reproducible, more than 2-fold, regulation of the candidate markers by dexamethasone or clobetasol was found for: (a) matrix metalloproteinase (MMP) 1, 2, 3 and 9 expression in human keratinocytes, (b) COL1A1 and COL3A1 expression in 3T3 fibroblasts, and (c) epidermal thickness, collagen and MMP synthesis in the full-thickness skin model (FTSM). These 3 models were further investigated with a panel of 4-5 GCs, demonstrating dose dependency and correlation with the atrophogenic potential of the tool compounds, qualifying them as potentially suitable. Finally, the predictability of these models for the in vivo situation was analyzed, testing a novel selective GC receptor agonist (SEGRA) in comparison to clobetasol. The results from the in vitro models suggested less atrophogenic effects for the SEGRA compound, which indeed was confirmed in the hr/hr rat skin atrophy model. In conclusion, a combination of 3 in vitro models based on 3T3 cells, human keratinocytes and FTSM with several readouts is recommended to determine atrophogenicity of GC receptor ligands. Further experiments are necessary to eventually reduce this panel and to demonstrate the true predictability for the clinic.

Characterization of ZK 245186, a novel, selective glucocorticoid receptor agonist for the topical treatment of inflammatory skin diseases

BACKGROUND AND PURPOSE

Glucocorticoids are highly effective in the therapy of inflammatory diseases. Their value, however, is limited by side effects. The discovery of the molecular mechanisms of the glucocorticoid receptor and the recognition that activation and repression of gene expression could be addressed separately opened the possibility of achieving improved safety profiles by the identification of ligands that predominantly induce repression. Here we report on ZK 245186, a novel, non-steroidal, low-molecular-weight, glucocorticoid receptor-selective agonist for the topical treatment of inflammatory dermatoses.

EXPERIMENTAL APPROACH

Pharmacological properties of ZK 245186 and reference compounds were studied in terms of their potential anti-inflammatory and side effects in functional bioassays in vitro and in rodent models in vivo.

KEY RESULTS

Anti-inflammatory activity of ZK 245186 was demonstrated in in vitro assays for inhibition of cytokine secretion and T cell proliferation. In vivo, using irritant contact dermatitis and T cell-mediated contact allergy models in mice and rats, ZK 245186 showed anti-inflammatory efficacy after topical application similar to the classical glucocorticoids, mometasone furoate and methylprednisolone aceponate. ZK 245186, however, exhibits a better safety profile with regard to growth inhibition and induction of skin atrophy after long-term topical application, thymocyte apoptosis, hyperglycaemia and hepatic tyrosine aminotransferase activity.

CONCLUSIONS AND IMPLICATIONS

ZK 245186 is a potent anti-inflammatory compound with a lower potential for side effects, compared with classical glucocorticoids. It represents a promising drug candidate and is currently in clinical trials.

Long-term interleukin-10 presence induces the development of a novel, monocyte-derived cell type

Interleukin (IL)-10 is one of the most crucial immunoregulatory cytokines. Its short-term effects have been analysed extensively, but little is known about its long-term effects. This is of considerable importance, as high systemic IL-10 levels are present for long periods in patients with persistent viral infections, certain cancers and in critical care patients. Our study investigated the effects of the long-term presence of IL-10 on human peripheral blood monocytes. In vitro, IL-10 treatment of these cells for 7 days induced the development of a novel cell type characterized by unique phenotypical and functional characteristics. These cells showed high HLA-DR expression and low expression of CD86 and other co-stimulatory molecules on their surface. The mRNA levels of both HLA-DR and CD86 were high, but no intracellular accumulation of CD86 protein was observed. With respect to its function, these cells showed strongly diminished tumour necrosis factor-alpha production following lipopolysaccharide stimulation, strongly diminished allogenic CD4(+) T cell stimulatory capacity, and even induced a hyporesponsive state in CD4(+) T cells. The phenotype remained stable despite the removal of IL-10. In vivo, we found monocytic cells from patients exhibiting this phenotype after long-term IL-10 exposure. These results complement our knowledge further about the biological effects of IL-10 and may provide an explanation for the sustained immunodeficiency in cases of the persistent presence of systemic IL-10.

Protein kinases as small molecule inhibitor targets in inflammation

The human kinome describes a major group of intracellular signalling molecules. In the last few years, many molecules in the group have become targets for therapeutic interventions. Due to the conserved reaction mechanism of catalysis, protein kinases seem well "drugable" by small molecular weight inhibitors, thus opening the chance to novel oral bioavailable drug development. A large number of small molecule weight inhibitors for protein kinases have already been introduced into research and these molecules are extensively analysed in regard to their efficiency, potency and selectivity. Here we summarise the use of small molecule protein kinase inhibitors relevant for acute and chronic inflammation based on their essential role in cellular signaling mechanisms in immune cells such as macrophages, lymphoytes and granulocytes. We describe the progress made to develop inhibitors against Toll-like receptor associated kinases (IRAKs), against the MAPK kinase kinases Cot/Tpl-2 and TAK1, against Inhibitor-kappaB kinases (IKKs), against MAPK kinases (MEKs, MKKs), against MAPKs (ERK2, p38, JNKs) and against their downstream kinases MNK1 and MK2/3. This overview should help to keep up with the fast developing field and the continuously growing number of protein kinase inhibitors.

Is there an interaction between interleukin-10 and interleukin-22?

Interleukin(IL)-10 and IL-22 are structurally related cytokines. Their heterodimeric receptors consist of the cytokine-specific chains IL-10R1 and IL-22R1, respectively, and the common chain IL-10R2. This study focused on the question of whether IL-10 modulates IL-22 effects and vice versa. This question is important because IL-10 and IL-22 exert anti- and proinflammatory effects, respectively, and, as we show here, are simultaneously present in both systemic and local inflammation. The revealed lacking concomitance of IL-10R1 and IL-22R1 on identical cells excluded any possible interaction between IL-10 and IL-22 apart from the competition for IL-10R2. To study this competition, monocytes and hepatocytes were chosen. The dependence of the cytokine action on IL-10R2 was verified. Interestingly, no influence of IL-22 on IL-10 effects was observed. The same was true when IL-22 was used in complex with IL-22-binding protein. Similarly, no influence of IL-10 was found on IL-22 action. This missing competition seemed to be due to a lack of binding between IL-10R2 and the native cytokines in the absence of their corresponding R1 chain. However, IL-10R2 interacted with defined IL-10- and IL-22-derived peptides supporting the hypothesis that cytokine binding to its corresponding R1 chain creates a binding site on this cytokine for IL-10R2.

Cloning of murine IL-22 receptor alpha 2 and comparison with its human counterpart

We have identified the mouse and rat homologs of human interleukin-22 receptor alpha 2 (IL-22R alpha 2) and compared the localization, structure, and expression of the encoding murine and human genes. The mouse IL-22R alpha 2-encoding gene is located on chromosome 10A3 between, like in human, the genes for interferon-gamma R1 and IL-20R1. It spans a region of approximately 10 kb therefore being three times shorter than the human gene. Although the overall gene structure in both species is similar, the mouse gene lacks a counterpart to the third coding exon of the human gene known to be alternatively spliced. Like in human, mouse and rat IL-22R alpha 2 exist only as soluble receptors as deduced from the lack of transmembrane and intracellular domains encoding sequences. Quantitative expression analyses showed, analogically to the human system, a limited tissue distribution of mouse IL-22R alpha 2 mRNA. Differential modulation of IL-22R alpha 2 mRNA expression was observed upon systemic inflammation in mice in spleen, thymus, and lymph node.

Molecular mechanisms of interleukin-10-mediated inhibition of NF-kappaB activity: a role for p50

Nuclear factor kappa B (NF-kappaB) is a transcription factor pivotal for the development of inflammation. A dysregulation of NF-kappaB has been shown to play an important role in many chronic inflammatory diseases including rheumatoid arthritis, inflammatory bowel disease and psoriasis. Although classical NF-kappaB, a heterodimer composed of the p50 and p65 subunits, has been well studied, little is known about gene regulation by other hetero- and homodimeric forms of NF-kappaB. While p65 possesses a transactivation domain, p50 does not. Indeed, p50/p50 homodimers have been shown to inhibit transcriptional activity. We have recently shown that Interleukin-10 exerts its anti-inflammatory activity in part through the inhibition of NF-kappaB by blocking IkappaB kinase activity and by inhibiting NF-kappaB already found in the nucleus. Since the inhibition of nuclear NF-kappaB could not be explained by an increase of nuclear IkappaB, we sought to further investigate the mechanisms involved in the inhibition of NF-kappaB by IL-10. We show here that IL-10 selectively induced nuclear translocation and DNA-binding of p50/p50 homodimers in human monocytic cells. TNF-alpha treatment led to a strong translocation of p65 and p50, whereas pretreatment with IL-10 followed by TNF-alpha blocked p65 translocation but did not alter the strong translocation of p50. Furthermore, macrophages of p105/p50-deficient mice exhibited a significantly decreased constitutive production of MIP-2alpha and IL-6 in comparison to wild type controls. Surprisingly, IL-10 inhibited high constitutive levels of these cytokines in wt macrophages but not in p105/p50 deficient cells. Our findings suggest that the selective induction of nuclear translocation and DNA-binding of the repressive p50/p50 homodimer is an important anti-inflammatory mechanism utilized by IL-10 to repress inflammatory gene transcription.

Einsatz von Biologicals bei Psoriasis in der Dermatologie

With a prevalence of 2-3 percent, psoriasis is one of the most common diseases in dermatology. Most patients can be treated sufficiently with topical emollients, but approximately 20 percent of all patients suffering from psoriasis need photo- and/or systemic therapies. Side effects, contraindications, insufficient clinical responses, and lack of long-term efficacy underline the need for novel and improved antipsoriatic therapies. Several biologics interfering with key steps in the immunopathogenesis of psoriasis bear the potential to meet this need with regard to treating moderate to severe psoriasis. Progress made in the understanding of the pathophysiology of psoriasis as T-cell mediated dermatosis does provide options for new, more precise therapeutic approaches. These immunological therapeutic strategies are targeted at the inhibition of T-cell activation, the depletion of activated T-lymphocytes, the inhibition of adhesion of inflammatory cells, the inhibition of effects of proinflammatory cytokines and the application of antiinflammatory cytokines. This article gives a summary of new biologicals used in the treatment of psoriasis. Clinical results received from first applications are inconclusive. Further results of the studies from phase II and phase III can be expected in the next few years, which should make it possible to achieve better assessments of the potential of these types of treatments. Some of these approaches could lead to the approval of new drugs to treat psoriasis and to enhance or replace already existing therapeutic options.

Interleukin-10 promoter polymorphism IL10.G and familial early onset psoriasis

BACKGROUND

The anti-inflammatory cytokine interleukin (IL)-10 is considered to play a major role in the pathophysiology of psoriasis, which is characterized by an IL-10 deficiency. Systemic administration of IL-10 has been shown to be an effective therapy for psoriasis. The IL-10 promoter region contains a highly polymorphic microsatellite (IL10.G) and in a recent case-control study the IL10.G13 (144 bp) allele was found to be associated with familial early onset psoriasis (type 1 psoriasis) having a susceptible effect.

OBJECTIVES

As it is essential in multifactorial diseases to replicate findings before definite conclusions can be drawn, we decided to perform a follow-up study and to follow a genetic approach analysing allele transmission in families with a positive family history of psoriasis.

METHODS

We studied 137 nuclear families (trio-design) comprising 456 individuals and genotyped the IL10.G marker. For comparison we also genotyped the microsatellite tn62 as a reference marker of the major psoriasis susceptibility locus on chromosome 6p21 (PSORS1). In the present study allele transmission was evaluated using the family-based association test (FBAT) and GENEHUNTER 2.0 based on the transmission/disequilibrium test.

RESULTS

The G13 allele (144 bp) had a frequency of 24%, was present in 88 families and clearly showed an even transmission (FBAT, P = 0.753). In contrast, allele 3 (IL10.G9) (136 bp) had a frequency of 39%, was present in 110 families and was transmitted in 43 trios and remained untransmitted in 67 trios (FBAT, P = 0.026), thus showing preferential nontransmission. For the HLA-linked tn62-marker we obtained a P-value of 0.00027 for allele 4 in the same study group.

CONCLUSIONS

In conclusion, we failed to confirm the susceptible effect of the G13 allele, but provide the first data for a protective effect of allele 3 (IL10.G9) for familial psoriasis. Our results suggest that the IL10.G polymorphism is not a major locus, but acts as a minor locus.

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.

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.

SEGRAs: a novel class of anti-inflammatory compounds

Dissociated GCs show a separation between anti-inflammatory effects and certain side effects. This renders them as attractive compounds with better effect/side-effect profile as promising drug candidates and tool compounds for analyzing the molecular mechanisms of single side effects. A number of the GC-mediated side effects (e.g., osteoporosis, skin atrophy) are regulated in a very complex manner and use more than one molecular mechanism of the GR. Thus, theoretical predictions about the behavior of selective GR agonists regarding these effects are very difficult to make. Investigations of SEGRA compounds in relevant animal models will be the only way to get this important information. By availability of these tool compounds we now are in the advantageous situation to test them in vivo and to learn more about the possibilities and even the limitations of the selective GR agonists. Considering that the compounds have a non-steroidal structure, i.e., totally unrelated to steroids or other hormones at all, displaying only partially the molecular effects of GCs and are dissociated in their clinical profile, they should not be considered as GCs. Therefore, we introduced the term selective glucocorticoid receptor agonists (SEGRAs). These SEGRAs seem to represent a useful novel therapeutic modality which may complement existing therapeutic principles for the topical and especially the systemic treatment of inflammatory diseases. In summary, we and others are convinced that dissociated GCs are therapeutic compounds that exert many of the anti-inflammatory and immunosuppressive effects of standard GCs, while their potential to induce side effects is reduced. Whereas the in vitro dissociated profile of other compound classes (Belvisi et al. 2001) was not translated into a separation between anti-inflammatory activity and the induction of side effects in in vivo models, we could demonstrate this for the SEGRA compounds. Regarding the diversity of molecular mechanisms involved in mediating the complex side effects of GCs, it might be that only some of these unwanted effects can be reduced. However, as GCs are one of the most important anti-inflammatory therapeutics in the treatment of severe and chronic inflammatory diseases, even a partial reduction of side effect induction would be a great advantage for many patients.

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.

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.

A novel, soluble homologue of the human IL-10 receptor with preferential expression in placenta

The cytokine receptor family type 2 (CRF2) comprises receptors for important immunomediators like interferons and interleukin-10 (IL-10). We identified a novel member of this family which represents the first exclusively soluble receptor in this group and was therefore designated as CRF2-soluble 1 (CRF2-s1). The CRF2-s1 gene covers about 28 kb and is located on chromosome 6 in close proximity to the CRF2 members interferon (IFN)-gamma receptor 1 and IL-20 receptor 1. It comprises seven exons and generates two different mRNA splice variants, CRF2-s1-long and CRF2-s1-short. CRF2-s1-long and CRF2-s1-short encode proteins of 263 and 231 amino acids, respectively. A comparison of predicted protein structures led to the postulation that each receptor variants binds a different ligand. Quantitative analysis of human mRNA expression revealed a very restricted pattern for both splice forms. CRF2-s1 turned out to be the first member of this receptor family which was expressed neither in resting nor in stimulated leucocyte populations. CRF2-s1-long was only expressed in placenta, whereas CRF2-s1-short was additionally expressed in human mammary gland and, at a lower level, in skin, spleen, thymus and stomach. The preferential expression of CRF2-s1 in placenta suggests a role for this receptor in establishing and maintaining successful pregnancy.

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.

Inhibition of keratinocyte apoptosis by IL-15: a new parameter in the pathogenesis of psoriasis?

Keratinocytes (KC) are important source of and targets for several cytokines. Although KC express IL-15 mRNA, the functional effects of IL-15 on these epithelial cells remain to be dissected. Investigating primary human foreskin KC and HaCaT cells, we show here by semiquantitative RT-PCR and flow cytometric analysis that both translate IL-15 and IL-15R mRNA and express IL-15 and IL-15Ralpha protein on the cell surface, suggesting that human KC can employ IL-15 for juxtacrine signaling. While IL-15 exerted no significant effect on KC proliferation and IL-6 or IL-8 secretion, IL-15 inhibited both anti-Fas and methylcellulose-induced KC apoptosis in vitro. This is in line with the recognized potent anti-apoptotic effects of IL-15. IL-2, whose receptor shares two components with the IL-15R, failed to inhibit KC apoptosis. Together with the role of IL-15 in sustaining chronic immune reactions, this invited the question of whether a reduction of KC apoptosis by IL-15 may be involved in the pathogenesis of psoriasis, a chronic hyperproliferative inflammatory skin disease characterized by abnormally low KC apoptosis in the epidermis. Remarkably, compared with nonlesional psoriatic skin and skin of healthy volunteers, lesional psoriatic epidermis showed high IL-15 protein expression in the epidermis and enhanced binding activity for IL-15. Therefore, antagonizing the inhibitory effects of IL-15 on KC apoptosis deserves exploration as a novel therapeutic strategy in psoriasis management.

IL-15 and IL-16 overexpression in cutaneous T-cell lymphomas: stage-dependent increase in mycosis fungoides progression

Cytokines are of major importance for the pathogenesis of cutaneous T-cell lymphomas (CTCL). Recent data suggested that IL-15 and IL-16 are survival/growth factors for the malignant T cells in these entities. To investigate the expression of IL-15 and IL-16 in mycosis fungoides (MF) and CD30+ pleomorphic T-cell lymphoma in vivo, we established a competitive RT-PCR technique. Analyzing skin biopsies from CTCL patients at different stages in comparison to psoriatic and healthy skin, we found IL-15 and IL-16 mRNA overexpression in both CTCL entities. Remarkably, there was some evidence for a stage-dependent increase during MF progression. We found only slight overexpression in early stage MF, when only few tumor cells are detectable within the infiltrates, whereas marked overexpression was found in more advanced lesions, which are characterized by a higher density of malignant cells. These results suggested that CTCL cells themselves might produce the cytokines. To further elucidate this hypothesis, two CTCL cell lines were analyzed but gave conflicting results. Therefore, the cellular origin of the IL-15 and IL-16 overexpression in CTCL remains unclear. Considering the significant overexpression of IL-15 and IL-16 and their biological capacities it is likely that these cytokines contribute to the tumor development. So, they might be involved in growth and skin homing of CTCL cells.

The antipsoriatic activity of IL-10 is rather caused by effects on peripheral blood cells than by a direct effect on human keratinocytes

IL-10 is a promising candidate for the treatment of cutaneous disorders. Antipsoriatic efficacy of systemic IL-10 treatment has been already demonstrated. This includes histomorphological changes in the epidermis, suggesting effects on keratinocytes. However, less is known about direct effects of IL-10 on this cell population, although effects are likely since IL-10 receptor expression on keratinocytes has been demonstrated recently. Therefore we analysed the effects of IL-10 on keratinocytes in vitro, using concentrations of human recombinant IL-10 corresponding to those detectable in plasma during therapy. Proliferation, cytokine formation (IL-6, IL-8, IL-1ra), and expression of surface molecules (MHC class I and II, costimulatory molecules CD80 and CD86, CD29, CD54, CD95) were measured in stimulated and unstimulated cells. Although stimulation influenced the expression levels of certain surface markers, no or only slight effects of IL-10 were found. In contrast considerable inhibitory effects of IL-10 on surface molecule expression and cytokine secretion by peripheral blood human monocytes were observed. Our results suggest that the antipsoriatic activity of IL-10 is rather caused by modulatory effects on circulating immune cells, which subsequently might infiltrate the skin, than by direct effects on human keratinocytes. Considering the remarkable antipsoriatic activity of IL-10 and the observation that IL-10 seem to act on peripheral blood mononuclear cells but not on keratinocytes provide further evidence that circulating immune cells play a key role in the pathology of psoriasis. Finally, our results argue against the value of IL-10 therapy in dermatoses strictly limited to keratinocyte involvement.

Cytokine expression in primary cutaneous germinal center cell lymphomas

Physiologically, B-lymphocytes are not present in the skin. Even in pathological situations they rarely occur. In contrast, primary cutaneous B-cell lymphomas (CBCL) are characterized by proliferation of B lymphocytes within the skin. This suggests the existence of a certain microenvironment supporting homing and expansion of clonal B cells. Cytokines were demonstrated to be involved in the pathogenesis of cutaneous lymphomas of T-cell origin. Cytokine expression in cutaneous B-cell lymphoma lesions, however, has not been investigated so far. Therefore, the mRNA level of several cytokines was analyzed in biopsies from 7 patients with CBCL and compared to pleomorphic T-cell lymphoma (n = 6), psoriasis (n = 9), and healthy skin (n = 7), using a competitive RT-PCR approach. An overexpression of TNF-alpha, IL-10, and IL-6 was found. Enhanced IL-8 mRNA expression was detected in 2/7 cases. The overexpression of IL-6 and IL-10 in CBCL might be of particular importance, since these cytokines are considered to support B-cell growth. Additionally, the overexpression of IL-10 may contribute to tumor progression since this immunosuppressive cytokine might be involved in downregulation of immunological tumor surveillance, in part by inhibiting type 1 cytokine formation. In fact, we did not detect IFN-gamma and IL-2 expression. Taken together, we found a cytokine pattern in CBCL lesions which might contribute to tumor B-cell growth.

The treatment of psoriasis with IL-10: rationale and review of the first clinical trials

By virtue of its anti-inflammatory and immunosuppressive properties, IL-10 plays a crucial role in several immune reactions, including regulatory mechanisms in the skin. In psoriasis, a common cutaneous immune disease, a relative deficiency in cutaneous IL-10 expression is observed. Several lines of evidence suggest that IL-10 could have antipsoriatic abilities. One pilot and two Phase II trials with sc. IL-10 administration over 3 - 7 weeks in patients with moderate to severe psoriasis have supported this hypothesis. The therapy was well-tolerated and clinical efficiency was found in the majority of patients. Immunosuppressive effects (depressed monocytic HLA-DR expression, TNF-alpha and IL-12 secretion capacity, IL-12 plasma levels and responsiveness to recall antigens) as well as a shift towards a Type 2 cytokine pattern (increasing proportion of IL-4, IL-5, and IL-10 producing T-cells, selective increase in IgE serum levels) were observed. These investigations suggest that IL-10 is of major importance in psoriasis and show that IL-10 administration represents a new therapeutic approach. However, long-term administration of large recombinant protein limits the value of this novel therapeutic approach. As such, neither oral nor topical applications are possible; there is a risk of the development of neutralising antibodies.

The pathophysiological role of cytokines in psoriasis

Psoriasis is a chronic inflammatory cutaneous disorder. Recent data indicate that T cells and cytokines are of major importance in the pathophysiology of this frequent immune disease. The cutaneous and systemic overexpression of several proinflammatory cytokines, particularly type-1 cytokines such as IL-2, IL-6, IL-8, IL-12, IFN-gamma and TNF-alpha, has been demonstrated. The overexpression of these proinflammatory cytokines is considered to be responsible for initiation, maintenance and recurrence of skin lesions. The cellular composition of the inflammatory infiltrate within the plaques as well as the keratinocyte hyperproliferation appears to be directed by cytokines as well. Thus, the overexpression of the chemoattractant IL-8 contributes to the accumulation of granulocytes, a characteristic finding in psoriatic lesions. In contrast to the overexpression of proinflammatory cytokines, a relatively low level of expression of the antiinflammatory cytokines IL-1RA and IL-10 has been found, suggesting an insufficient counterregulatory capacity in psoriasis which might have a genetic background. The new pathophysiologic understanding of psoriasis offers the opportunity for well-targeted therapeutic interventions which should be more effective and better tolerated than the approaches used thus far. In fact, the cytokine imbalance represents an interesting target. This is supported by the therapeutic effects of IL-10, a type-2 cytokine with major influence on immunoregulation, since it inhibits type-1/proinflammatory cytokine formation.

Interleukin-10 in cutaneous disorders: implications for its pathophysiological importance and therapeutic use

With its antiinflammatory and immunosuppressive properties interleukin-10 (IL-10) plays a dominant role in several immune reactions including regulatory mechanisms in the skin. The overexpression of this mediator has been reported in some inflammatory dermatoses as well as in various skin tumors. These observations are of importance since they may explain the limitation of hyperinflammatory conditions as in eczemas and erythemas on the one hand and the suppression of an adequate antitumor response and thereby the progression of malignant tumors on the other hand. Moreover, elevated IL-10 expression might contribute to an enhanced risk of development of microbacterial superinfections, a frequent finding in several dermatoses, and might also be involved in the pathogenesis of connective tissue diseases. In contrast, recent studies indicate a relative IL-10 deficiency in psoriasis. Early clinical data from psoriatic patients treated with recombinant human IL-10 suggest the therapeutic potential of this cytokine and underline its impact on the regulation of the skin immune system.

A high prevalence of cytomegalovirus antigenaemia in patients with moderate to severe chronic plaque psoriasis: an association with systemic tumour necrosis factor alpha overexpression

Microbiological aspects are considered to be of pathophysiological importance in psoriasis, but there has so far been no information regarding cytomegalovirus (CMV) infection. This is of interest due to the high prevalence of latent infection in the general population, the frequent reactivation in inflammatory diseases, and the immunomodulating capacity of CMV. To detect active infection we analysed CMV antigen expression of peripheral blood mononuclear cells (PBMC) from psoriatic patients (n = 30) in comparison with healthy volunteers (n = 65). Using three monoclonal antibodies and immunocytological staining (alkaline phosphatase-antialkaline phosphatase technique), we frequently found CMV antigenaemia in psoriasis (43%) compared with healthy laboratory staff (12%, P < 0. 01) and blood donors (6%, P < 0.001). Clearance of CMV antigenaemia was observed with antipsoriatic treatment. CMV antigenaemia was symptomless, and was associated with seropositivity for anti-CMV IgG but not IgM antibodies, indicating subclinical activation of latent infection. Serological investigations in 85 psoriatic patients gave no evidence for a higher prevalence of latent CMV infection. In psoriatic lesions, CMV DNA was only rarely detected by polymerase chain reaction. As it has been shown that tumour necrosis factor (TNF)-alpha can induce CMV reactivation, we determined TNF-alpha plasma concentrations and mRNA expression in PBMC from psoriatic patients. Elevated TNF-alpha levels were found and correlated with the frequency of CMV antigen-expressing PBMC, suggesting a critical role of TNF-alpha in CMV activation. We speculate that active, subclinical CMV infection may be of pathophysiological importance in psoriasis.

Crosstalk between keratinocytes and T lymphocytes via Fas/Fas ligand interaction: modulation by cytokines

Apoptosis mediated by Fas/FasL interaction plays an important role during many inflammatory skin disorders. To estimate whether the expression of FasL, the ligand for Fas, might be regulated by cytokines we stimulated primary human keratinocytes with several pro- and anti-inflammatory cytokines. Keratinocytes cultured to subconfluence expressed FasL constitutively. Cells stimulated with the proinflammatory cytokines IL-1beta, TNF-alpha, IFN-gamma, and IL-15, respectively, increased significantly their intracellular as well as cell surface-bound FasL expression in a time- and dose-dependent manner. This cytokine-induced FasL expression was dependent on new protein synthesis. Despite enhanced expression of cell surface-bound FasL, no release of soluble FasL was measured in the cell supernatants determined by ELISA. Stimulation of the cells with IL-6, IL-10, IL-12, TGF-beta1, and GM-CSF did not modulate the constitutive FasL expression, but IFN-gamma-mediated FasL up-regulation was significantly diminished by IL-10 and TGF-beta1, respectively. Up-regulation of FasL on IFN-gamma-stimulated keratinocytes led to increased apoptosis within monolayers cultured for 48 h. Moreover, coculture experiments performed with Fas+ Jurkat T cells revealed that enhanced FasL expression on IFN-gamma-stimulated keratinocytes induced apoptosis in cocultured T cells, demonstrating that up-regulated FasL was functionally active. In summary, our data suggest the important regulatory role of cytokine-controlled Fas/FasL interaction in the cross-talk between keratinocytes and skin-infiltrating T cells for maintenance of homeostasis in inflammatory skin processes.

Interleukin 10 treatment of psoriasis: clinical results of a phase 2 trial

OBJECTIVE

To determine the safety and clinical effects of interleukin 10 (IL-10) treatment of psoriasis.

DESIGN AND METHODS

In an open-label phase 2 trial, 10 patients with psoriasis subcutaneously received recombinant human IL-10 over a 7-week period in a dosage of 8 microg/kg daily (n=5) or 20 microg/kg 3 times per week (n=5). Patients were followed up for an additional 5 weeks.

RESULTS

The treatment was well tolerated. Antipsoriatic effects were found in all but 1 patient. A significant decrease of the psoriasis area and severity index by 55.3% +/- 11.5% (mean +/- SEM) was observed (P<.02). The antipsoriatic efficiency was confirmed by histological examination. Heterogeneity in the effectiveness was found among the patients, but seems to be independent of the dosage regimen. However, a tendency to a better response was found in the patients who received 20-microg/kg IL-10 3 times per week. Decreasing response in the delayed-type hypersensitivity reaction against recall antigens indicated immunosuppressive effects. Moderate effects on hematopoietic cells were observed.

CONCLUSIONS

Our data suggest that IL-10 therapy for psoriasis is safe and possibly clinically effective. Consequently, its value in psoriasis and similar immune diseases should be further determined. Dose-finding, placebo-controlled, double-blind trials are necessary now.

[Interleukin-10 in dermatology]

In recent years the investigation of cytokines has been a focus of scientific interest in order to understand the pathogenesis of a variety of diseases. In additions cytokines are increasingly being used for therapeutic purposes, including dermatologic disorders. IL-10 is a recently described cytokine with anti-inflammatory and immunosuppressive qualities which plays an important role in immunoregulation. The overexpression of this mediator has been proven in some inflammatory dermatoses as well as in various skin tumors. These observations help to understand down regulatory events in hyper-inflammatory conditions such as allergic or toxic dermatitis on the one hand and the suppression of an adequate anti-tumor response and thereby the progression of malignant tumors on the other hand. Recent investigations indicate a relative IL-10 deficiency in psoriasis. Initial therapeutic applications of IL-10 in psoriasis underline the pathophysiological importance of this cytokine.

Cytokines and cutaneous T-cell lymphomas

Cytokines are considered to be of major importance for the pathogenesis of cutaneous T-cell lymphomas (CTCL). Their impact may result from autocrine, paracrine or endocrine effects. Several investigations demonstrated the overexpression of different cytokines in different CTCL entities. Interestingly, stage-dependent shifts in the cytokine pattern have been observed in mycosis fungoides (MF). There is evidence that the abnormal cytokine expression in CTCL might be responsible for tumor progression, resulting from an enhanced proliferation of the malignant cells and/or the depression of the anti-tumor immune response. Moreover, cytokine loops might explain phenomena like the epidermotropism of malignant cells or eosinophilia and increased plasma levels of IgE, which are present in advanced stages of CTCL. Analysis of the cytokine pattern in CTCL might give the basis for direct therapeutic intervention into the cytokine network as a new therapeutic approach. In this review, the current knowledge regarding cytokines in CTCL is summarized.

Sympathetic activation triggers systemic interleukin-10 release in immunodepression induced by brain injury

The mechanism of immunodepression after brain injury is not yet clear. Here we demonstrate rapid systemic release of the immunoinhibitory cytokine interleukin-10, monocytic deactivation and a high incidence of infection in patients with 'sympathetic storm' due to acute accidental or iatrogenic brain trauma. In vitro studies showed that within minutes catecholamines trigger the secretion of interleukin-10 from unstimulated monocytes through a beta-adrenoreceptor-mediated, cAMP/protein kinase A-dependent pathway. We found that in a rat model of acute brain injury, the beta-receptor antagonist propranolol prevented the increase of interleukin-10 plasma levels. Rapid monocytic interleukin-10 release after sympathetic activation may represent a common pathway for immunodepression induced by stress and injury.

Diminished monocytic HLA-DR expression and ex vivo cytokine secretion capacity in patients with glioblastoma: effect of tumor extirpation

Severe immunodysregulation on lymphocyte level has been described in patients with glioblastoma and is likely involved into its unfavorable prognosis. Although the major importance of monocytic cells for immunoregulation is well established, only very limited data exist regarding the monocyte status in glioblastoma patients. Here we demonstrate a markedly diminished monocytic HLA-DR expression and ex vivo cytokine secretion capacity (TNF-alpha, IL-1beta, IL-10) as signs for monocyte deactivation in glioblastoma patients but not in patients with astrocytoma. As known in immunocompromised patients from other reasons, monocyte deactivation indicate global immunodepression associated with an enhanced risk of infectious complications. Interestingly, tumor resection resulted in partial recovery from the monocytic deactivation. This suggests that the glioblastoma itself contributed to this phenomenon. However, IL-10 and the active forms of transforming growth factor-beta2 and -beta1, which are produced by glioblastoma cells and known to inhibit monocyte function, were not detectable in plasma in our patients. Moreover, low levels of the adrenocorticotropic hormone and cortisol excluded hypothalamo-pituitary-adrenal axis involvement. So, further investigations are necessary to clarify the mechanism. The demonstrated severe glioblastoma-associated monocytic deactivation may contribute to its unfavorable prognosis. Therefore, monocytes may represent target cells for new adjuvant immunotherapies in glioblastoma.

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

Overexpression of proinflammatory, type 1 cytokines has been demonstrated in psoriasis and is believed to be of pathophysiological importance. IL-10 is a type 2 cytokine with major impact on immunoregulation, since it inhibits type 1/proinflammatory cytokine formation. Therefore, we investigated its role in psoriasis. We found a relative deficiency in cutaneous IL-10 mRNA expression compared with other inflammatory dermatoses. Interestingly, patients during established antipsoriatic therapy showed higher IL-10 mRNA expression of peripheral blood mononuclear cells than patients before therapy. This suggested that IL-10 may have antipsoriatic capacity. Therefore, we performed a phase 2 pilot trial with subcutaneous IL-10 administration (8 microg/kg/d) over 24 d in three patients. Clinical efficiency measured by objective and subjective parameters was found. Immunosuppressive effects (depressed monocytic HLA-DR expression, TNF-alpha and IL-12 secretion capacity, IL-12 plasma levels, and responsiveness to recall antigens) as well as a shift toward a type 2 cytokine pattern (increasing proportion of IL-4, IL-5, and IL-10 producing T cells, selective increase in IgE serum levels) were observed. Remarkably, IL-10 administration also enhanced the intracutaneous IL-10 mRNA expression. Our investigations demonstrate the major importance of IL-10 in psoriasis and show that IL-10 administration represents a new therapeutic approach. This is the first report on IL-10 therapy for cutaneous disorders.