T lymphocytes derived from skin lesions of patients with psoriasis vulgaris express a novel cytokine pattern that is distinct from that of T helper type 1 and T helper type 2 cells

Macrophage Functions in Psoriasis: Lessons from Mouse Models

Psoriasis is a systemic autoimmune/autoinflammatory disease that can be well studied in established mouse models. Skin-resident macrophages are classified into epidermal Langerhans cells and dermal macrophages and are involved in innate immunity, orchestration of adaptive immunity, and maintenance of tissue homeostasis due to their ability to constantly shift their phenotype and adapt to the current microenvironment. Consequently, both macrophage populations play dual roles in psoriasis. In some circumstances, pro-inflammatory activated macrophages and Langerhans cells trigger psoriatic inflammation, while in other cases their anti-inflammatory stimulation results in amelioration of the disease. These features make macrophages interesting candidates for modern therapeutic strategies. Owing to the significant progress in knowledge, our review article summarizes current achievements and indicates future research directions to better understand the function of macrophages in psoriasis.

Psoriasis immunometabolism: progress on metabolic biomarkers and targeted therapy

Psoriasis is a common inflammatory disease that affects mainly the skin. However, the moderate to severe forms have been associated with several comorbidities, such as psoriatic arthritis, Crohn's disease, metabolic syndrome and cardiovascular disease. Keratinocytes and T helper cells are the dominant cell types involved in psoriasis development via a complex crosstalk between epithelial cells, peripheral immune cells and immune cells residing in the skin. Immunometabolism has emerged as a potent mechanism elucidating the aetiopathogenesis of psoriasis, offering novel specific targets to diagnose and treat psoriasis early. The present article discusses the metabolic reprogramming of activated T cells, tissue-resident memory T cells and keratinocytes in psoriatic skin, presenting associated metabolic biomarkers and therapeutic targets. In psoriatic phenotype, keratinocytes and activated T cells are glycolysis dependent and are characterized by disruptions in the TCA cycle, the amino acid metabolism and the fatty acid metabolism. Upregulation of the mammalian target of rapamycin (mTOR) results in hyperproliferation and cytokine secretion by immune cells and keratinocytes. Metabolic reprogramming through the inhibition of affected metabolic pathways and the dietary restoration of metabolic imbalances may thus present a potent therapeutic opportunity to achieve long-term management of psoriasis and improved quality of life with minimum adverse effects.

Ultraviolet B irradiation decreases CXCL10 expression in keratinocytes through endoplasmic reticulum stress

Ultraviolet radiation is one of the standard treatment selections for psoriasis. interferon (IFN)-γ and IFN-γ-induced CXCL10, which are highly expressed by keratinocytes in psoriasis lesion, are therapeutic targets for psoriasis. In this study, we found that ultraviolet B (UVB) irradiation inhibited IFN-γ signaling events, including STAT1 phosphorylation and induction of CXCL10 messenger RNA (mRNA) expression in keratinocytes. IFN-γ-induced expression of CXCL10 mRNA in HaCaT cells, a human keratinocyte cell line, and human epithelial keratinocytes were also inhibited by H2 O2 or endoplasmic reticulum (ER) stress inducers. Conversely, a mixture of antioxidants, Trolox and ascorbic acid, and the ER stress inhibitor salubrinal partially counteracted the inhibitory effect of UVB on IFN-γ-induced CXCL10 mRNA expression in HaCaT cells. We also found that UVB and ER stress reduced IFN-γ receptor 1 protein levels in the plasma membrane fraction of keratinocytes. These observations suggested that ER stress and the generation of reactive oxygen species are essential for the inhibitory effect of UVB on IFN-γ-induced CXCL10 mRNA in keratinocytes.

Increased risk of psoriasis following scabies infection: A nationwide population-based matched-cohort study

Both scabies and psoriasis are pruritic inflammatory skin diseases. The clinical manifestations are similar and provocation of psoriasis by mite bite was reported. The association between scabies and psoriasis was not investigated before. We conducted this nationwide population-based matched-cohort study to describe if patients with a diagnosis of scabies have a different risk of developing new psoriasis. From the National Health Insurance Research Database of Taiwan, patients with scabies (n = 5137) were identified and matched for age and sex with non-scabies controls (n = 19 142). We tracked them for a 7-year period to identify the incidence of psoriasis. One hundred and ninety (0.8%) patients with newly diagnosed psoriasis were identified; 91 (1.8%) from the scabies group and 99 (0.5%) from the control group. Patients with scabies had a higher risk of subsequent psoriasis, with a crude hazard ratio of 3.45 and an adjusted hazard ratio (aHR) of 3.03 (95% confidence interval, 2.24-4.11). An increased risk for psoriasis among patients with scabies was observed (aHR, 3.03). Immunopathology involving the T-helper 17 cell-mediated inflammatory pathway may contribute to this association. Physicians may consider implementing assessments of psoriatic symptoms in patients with scabies.

Unopposed IL-36 Activity Promotes Clonal CD4+ T-Cell Responses with IL-17A Production in Generalized Pustular Psoriasis

Generalized pustular psoriasis (GPP) is the most severe psoriasis variant. Mutations in the IL-36 antagonist IL36RN, in CARD14 or AP1S3 provide genetic evidence for autoinflammatory etiology but cannot explain its pathogenesis completely. Here we demonstrate that unopposed IL-36 signaling promotes antigen-driven and likely pathogenic T-helper type 17 (Th17) responses in GPP. We observed that CD4⁺ T cells in blood and skin lesions of GPP patients were characterized by intense hyperproliferation, production of the GPP key mediator, IL-17A, and highly restricted TCR repertoires with identical T-cell clones in blood and skin lesions, indicating antigen-driven T-cell expansions. The clonally expanded CD4⁺ T cells were major producers of IL-17A. IL-36 signaling substantially enhanced TCR-mediated proliferation of CD4⁺ T cells. Moreover, GPP patients showed preferences for HLA-DRB1∗14, HLA-DQB1∗05, and HLA-DQB1∗03. We conclude that in GPP unopposed IL-36 signaling and certain HLA-class II alleles may cooperate in promoting antigen-driven Th17 responses, which in the obvious absence of exogenous triggers may reflect autoimmune reactions. This study reveals a pathogenic pathway where innate immune dysregulation promotes T-cell-mediated inflammation in GPP.

Hepatitis C may enhance key amplifiers of psoriasis

BACKGROUND

Multiple studies have noted an association between hepatitis C and psoriasis, but it is not known whether psoriasis is a result of treatment modalities for hepatitis C or a result of hepatitis C alone.

OBJECTIVE

To examine the relationship between psoriasis and hepatitis C by measuring the expression of cathelicidin, TLR9 and IFNγ in psoriatic lesional and non-lesional skin in HCV-positive and negative psoriatic patients.

METHODS

Two 2 mm punch biopsies of lesional and non-lesional skin in 10 patients who were HCV-negative psoriatics and seven HCV-positive psoriatics were used to measure cathelicidin, TLR9 and IFNγ mRNA expression by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR).

RESULTS

The mRNA levels of cathelicidin, TLR9 and IFNγ were significantly higher in both non-lesional and lesional skin of HCV-positive patients with psoriasis as compared to HCV-negative psoriatic patients. Additionally, the IFNγ level in lesional skin of HCV-positive psoriatic patients was higher than the IFNγ level seen in non-lesional skin of those same patients.

CONCLUSION

These findings suggest that HCV infection upregulates these inflammatory cytokines, possibly increasing susceptibility to developing psoriasis.

Cytokines in psoriasis

Psoriasis is a common inflammatory skin disease with an incompletely understood etiology. The disease is characterized by red, scaly and well-demarcated skin lesions formed by the hyperproliferation of epidermal keratinocytes. This hyperproliferation is driven by cytokines secreted by activated resident immune cells, an infiltrate of T cells, dendritic cells and cells of the innate immune system, as well as the keratinocytes themselves. Psoriasis has a strong hereditary character and has a complex genetic background. Genome-wide association studies have identified polymorphisms within or near a number of genes encoding cytokines, cytokine receptors or elements of their signal transduction pathways, further implicating these cytokines in the psoriasis pathomechanism. A considerable number of inflammatory cytokines have been shown to be elevated in lesional psoriasis skin, and the serum concentrations of a subset of these also correlate with psoriasis disease severity. The combined effects of the cytokines found in psoriasis lesions likely explain most of the clinical features of psoriasis, such as the hyperproliferation of keratinocytes, increased neovascularization and skin inflammation. Thus, understanding which cytokines play a pivotal role in the disease process can suggest potential therapeutic targets. A number of cytokines have been therapeutically targeted with success, revolutionizing treatment of this disease. Here we review a number of key cytokines implicated in the pathogenesis of psoriasis.

Target tissue ectoenzyme CD39/CD73-expressing Foxp3+ regulatory T cells in patients with psoriasis

BACKGROUND

Psoriasis is a chronic, relapsing, inflammatory skin disease, in which regulatory T cells (Tregs) play an important role. Recently, human Treg ectoenzymes (CD39/CD73) have been reported to mediate the suppressive activity of Tregs.

AIM

To investigate the proportions of CD39/CD73 expressing Foxp3(+) regulatory T cells in different types of psoriatic lesions.

METHODS

Immunohistochemical staining was used to analyse expression of Foxp3, CD39 and CD73 in biopsy tissue from healthy controls and from patients with different types of psoriasis.

RESULTS

In normal control biopsies, CD39(+) cells were scattered throughout the epidermis and dermis, while CD73(+) cells were localized predominantly in the dermis. The proportion of cells that were both CD39(+) and Foxp3(+) was significantly lower in pustular psoriasis (PP) and erythrodermic psoriasis (EP) than in psoriasis vulgaris (PV) (25.0 ± 2.6%, 26.5 ± 2.0% and 45.1 ± 3.5%, respectively; P < 0.001). Likewise, CD73(+) Foxp3(+) cells were lower in PP and EP than in PV (6.2 ± 1.9%, 11.6 ± 2.8% and 17.7 ± 2.3% respectively, P < 0.001). There were no significant differences in the population size of double-staining cells in EP compared with PP.

CONCLUSION

The relative reduced expressions of CD39 and CD73 within Foxp3(+) Tregs may imply a different immunopathogenesis for different psoriatic lesions.

Association of disease severity with IL-1 levels in methotrexate-treated psoriasis patients

Interleukin-1 plays a key role in inflammation and keratinocyte activation. It is an important mediator in the initiation and maintenance of psoriatic plaques and may represent an attractive therapeutic target. The aim of this study is to evaluate the effect of Methotrexate (MTX) on IL-1 α and IL-1 β levels in both plasma and skin biopsy of patients with psoriasis and to investigate their association with clinical disease activity. Forty-five control subjects and 58 patients with psoriasis were recruited for this study. The patients were treated with 7.5 mg of MTX per week for 12 weeks. Folic acid was given at 5 mg once daily except on the day of MTX for 12 weeks. Blood samples and lesional skin biopsy were taken. Disease severity was assessed by Psoriasis Area Severity Index (PASI) score. IL-1 levels in plasma and skin biopsy were analysed using ELISA. PASI score declined significantly (P < 0.001) from day 0 to 12 weeks of MTX treatment. IL-1 α level in plasma and skin biopsy was reduced at day 0 sample and elevated significantly (P < 0.001) after MTX treatment. IL-1β level in plasma and skin biopsy was higher at day 0 sample and reduced significantly (P < 0.001) after MTX treatment. IL-1α levels and PASI score showed inverse correlation score before and after treatment with MTX. Whereas IL-1β levels showed positive correlation before and after treatment with MTX. Decreasing IL-1β levels by MTXs in psoriasis may block the Th17 differentiation. This shows the therapeutic effect of MTX in controlling the immunopathogenesis of psoriasis.

Expression patterns of Th1/Th2 transcription factors in patients with guttate psoriasis

Many lines of evidence propose that psoriasis is a T cell-mediated disease where T cell activation is followed by secretion of inflammatory cytokines. To elucidate the functional state of T cells in guttate psoriasis, we analysed mRNA expression levels of T-bet and GATA-3 for Th1 and Th2 differentiation, respectively together with Th1 (IFN-γ) and Th2 (IL-4) cytokine mRNA expression. Relative quantification of T-bet, GATA-3, IFN-γ and Th2, and IL-4 transcripts in peripheral blood leukocytes (PBL) was conducted by real-time reverse transcriptase PCR (RT-PCR). Serum levels of IFN-γ and Th2 and IL-4 were also determined by ELISA. GATA-3 and IL-4 mRNA expression levels were lower in psoriatic patients as compared to normal healthy controls. The expression levels of T-bet and IFN-γ and Th2 genes were relatively similar in the patients and controls. In addition, a marked decrease in plasma IL-4 levels was observed in the psoriasis group, while no differences were observed with regard to levels of IFN-γ and Th2 between patients and normal subjects. Furthermore, a clear correlation between decreased IL-4 mRNA expression and IL-4 (P < 0.05) was revealed. These results suggested that altered balance between Th1 and Th2 cells transcription factor genes and they products may be implicated in the pathogenesis of psoriasis.

Targeting IL-17 in psoriasis: from cutaneous immunobiology to clinical application

Psoriasis vulgaris is a chronic, immune-mediated inflammatory skin disease associated with complex genetic susceptibility. Although the hallmark of psoriasis is characterized by cutaneous inflammation and keratinocyte hyperproliferation, recent studies show that the pathologic features observed in psoriasis arises as a result of innate and adaptive immune activation in genetically prone individuals. Studies focused on the microenvironment in the skin of psoriasis lesions have revealed novel cellular and cytokine abnormalities of the immune system. One pathway important is the role of the T(H)17/IL-17 dysregulation. The recent development of biologics that target the IL-17 cytokine pathway has confirmed the importance of T(H)17 and IL-17 homeostasis in the skin and yielded potent therapies in the treatment of psoriasis, and potentially other autoimmune diseases.

Tumor necrosis factor-alpha and the cytokine network in psoriasis

New molecular methods of research have greatly expanded the knowledge about the role of cytokines in several diseases, including psoriasis. The work orchestrated by these peptides is essential for the communication between resident inflammatory cells (keratinocytes and endothelial cells) and infiltrating cells (neutrophils, lymphocytes, Langerhans cells). This is a complex network due to redundancy, synergism and, sometimes, the antagonism of cytokines, which prevents full understanding of the pathogenesis of the disease. Currently, it seems premature to try to establish a main actor, but TNFalpha participates in all stages of psoriatic plaque development, as we shall see.

Effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis

BACKGROUND

Systemic and focal infections caused by microorganisms have been known to induce or exacerbate psoriasis. Although the role of yeast species of the genus Malassezia in the pathogenesis of psoriasis is not fully understood, it is thought that these lipophilic yeasts may represent a triggering factor in the exacerbation of psoriatic lesions.

OBJECTIVES

This study investigated the effects of Malassezia yeasts on serum Th1 and Th2 cytokines in patients with guttate psoriasis (GP) in order to define their role in the pathogenesis of psoriasis.

METHODS

Fifty patients with GP and 29 clinically healthy individuals were included in the study. All samples consisted of scales and scrapings taken from the scalps, trunks, and upper limbs of both psoriasis patients and healthy subjects. Psoriasis patients and healthy subjects were grouped according to their positivity or negativity for Malassezia yeasts as ascertained by direct microscopy and/or culture. An enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of Th1 and Th2 cytokines in these groups.

RESULTS

No significant differences in positivity for Malassezia yeasts were found between psoriatic skin and healthy skin in samples taken from different body sites. Serum interleukin-13 (IL-13) levels were significantly lower in the psoriasis group compared with the control group (P = 0.04). Levels of other cytokines did not differ significantly between the psoriasis and control groups. Mean levels of Th2 cytokines (IL-4, IL-10, IL-13), but not of Th1 cytokines (IL-2 and IFN-γ), were significantly lower in psoriasis patients positive for Malassezia yeasts compared with those negative for Malassezia yeasts and control subjects (P = 0.04, P < 0.001 and P = 0.01, respectively).

CONCLUSIONS

The isolation of Malassezia yeasts from GP lesions does not necessarily mean that these species are pathogenic, but their downregulating effects on anti-inflammatory Th2 cytokines may contribute to the occurrence of GP.

Up-regulation of Id1 in peripheral blood of psoriatic patients

Although the precise causes of psoriasis are unclear, it is widely accepted that psoriasis is a disorder in which factors in the immune system, enzymes, and other biochemical substances that regulate skin cell division are impaired, leading to rapid proliferation of keratinocytes and incomplete keratinization. Expression of the helix-loop-helix transcription factor Id1 (inhibitor of differentiation/DNA binding), functioning as an inhibitor of differentiation, is known to increase in psoriatic skin. However, the molecular involvement of this particular biomarker in the psoriatic immune system remains to be elucidated. We measured Id1 mRNA expression in peripheral blood mononuclear cells (PBMCs) of psoriatic patients and healthy controls using semi-quantitative reverse transcriptase-PCR. The normalized level of Id1 transcripts in psoriatic patients was about 2-fold higher than that in controls (P < 0.05). When we examined the proliferation rate of PBMCs, the stimulation index obtained from the phytohemagglutinin stimulation assay was not significantly different in psoriatic patients. In patients with psoriasis, there was no correlation between the stimulation index and the psoriasis area severity index. We suggest that Id1 has a role in causing psoriatic immune cell symptoms.

Ezrin, maspin, peroxiredoxin 2, and heat shock protein 27: potential targets of a streptococcal-induced autoimmune response in psoriasis

Psoriasis is an HLA-Cw6-associated T cell-mediated autoimmune disease of the skin that is often triggered by streptococcal angina. To identify keratinocyte proteins, which may become psoriatic autoantigens as the result of an immune response against streptococci, rabbits were immunized with heat-killed Streptococcus pyogenes. Streptococcal immunization induced Ab formation against various human keratinocyte proteins. Sera from psoriasis patients reacted against several of these proteins as well. Common serologic reactivities of rabbits and patients included the proteins ezrin, maspin, peroxiredoxin 2 (PRDX2), heat shock protein (hsp)27, and keratin 6. When used for stimulation of blood lymphocytes, ezrin, maspin, PRDX2, and hsp27 induced increased T cell activation in psoriasis patients, which was particularly evident for HLA-Cw6(+) individuals. Ag-specific T cell lines generated with these proteins consisted predominantly of CD8(+) T cells and used TCR beta-chain rearrangements, which were highly homologous to those expanded within the corresponding skin lesion. Several immunodominant epitopes on the different proteins could be defined according to sequence alignments with the whole genome of S. pyogenes. Our data indicate that maspin, ezrin, PRDX2, hsp27, and potentially keratin 6 could act as autoantigens of a streptococcal-induced autoimmune response and represent targets of the exaggerated T cell response in psoriasis. Additionally, ezrin and hsp27 might constitute antigenic links between psoriasis and inflammatory bowel disease, uveitis, or arteriosclerosis, which are clinically associated.

Decreased colony formation of high proliferative potential colony-forming cells and granulocyte-macrophage colony-forming units and increased Hes-1 expression in bone marrow mononuclear cells from patients with psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory disease of the skin. The dysfunctional immunity experienced by patients with psoriasis is believed to influence the bone marrow haematopoietic cells and their surrounding microenvironment. Phagocytes derived from the bone marrow of patients with active psoriasis exhibit enhanced monocytopoietic activity and hyperplasia in vitro. However, direct evidence supporting the hypothesis that bone marrow is involved in the pathogenesis of psoriasis has yet to be established.

OBJECTIVES

To investigate the involvement of bone marrow in the pathogenesis of psoriasis.

METHODS

Bone marrow mononuclear cells (BMMNCs) were isolated from patients with psoriasis and healthy individuals. The high proliferative potential colony-forming cells (HPP-CFCs), granulocyte-macrophage colony-forming units (CFU-GM) and erythroid colony-forming units (CFU-E) were cultured in the presence of defined cytokines, and the effects of secreted factors from psoriatic peripheral blood mononuclear cells (PBMCs) on colony formation of normal haematopoietic cells were analysed. Furthermore, the telomere activity of psoriatic and normal BMMNCs was determined using the polymerase chain reaction (PCR)-based telomeric repeat amplification protocol, while the expression of human telomerase reverse transcriptase (hTERT) and HES1 mRNA was detected by reverse transcription-PCR assay.

RESULTS

The numbers of HPP-CFCs and CFU-GM, but not CFU-E, were significantly reduced in cultured haematopoietic cells from patients with psoriasis. The culture supernatant of PBMCs from patients with psoriasis was found to inhibit the colony formation capacity of HPP-CFCs, CFU-GM and CFU-E of normal haematopoietic cells. We also detected low levels of telomerase activity and hTERT gene expression in psoriatic and control BMMNCs that was statistically similar between the two groups. In contrast, the HES1 gene expression appeared to be significantly elevated in psoriatic BMMNCs (P < 0.05).

CONCLUSIONS

Together, our results indicate the involvement of bone marrow in the immunopathogenesis of psoriasis, and suggest a mechanism mediated by certain inflammatory or haematopoietic cytokines present in the bone marrow microenvironment. Elevated expression levels of HES1 mRNA suggest a potential role for the Notch signalling pathway in this process.

Psoriasis and extra domain A fibronectin loops

We have previously postulated that as well as T-helper (Th) 1 and Th17 cells, the transforming growth factor (TGF)-beta/fibronectin (FN)/alpha5beta1 pathway is central to psoriasis pathogenesis. EDA+ FN refers to an alternatively spliced isoform of FN with an additional domain known as extra domain A. EDA+ FN has two important properties pertinent to psoriasis lesions: it stimulates keratinocyte hyperproliferation, and, through stimulation of Toll-like receptor (TLR) 4, stimulates production of proinflammatory cytokines. EDA+ FN production induced by TGF-beta stimulation can be maintained in psoriasis lesions via two main feedback loops. Firstly, EDA+ FN stimulates proliferation of keratinocytes, which, in an autocrine fashion, will release more EDA+ FN. Secondly, EDA+ FN stimulates TLR4 expressed by antigen-presenting cells resulting in the production of proinflammatory cytokines such as tumour necrosis factor-alpha, interleukin (IL)-1, IL-6 and IL-12. The resultant promotion of cutaneous inflammation results in the recruitment of Th1 cells, which also produce EDA+ FN. We propose that these 'FN loops' contribute to the maintenance and progression of psoriatic lesions. Finally, although the association between psoriasis and heart/thrombotic disease remains unclear one plausible link may be the promotion of atherosclerosis and thrombotic heart disease by EDA+ FN.

New treatments for psoriasis: Which biologic is best?

Psoriasis is a chronic, debilitating disease affecting not only the skin, but also having a significant impact on a patient's quality of life. The treatment of severe psoriasis is quite challenging due to the chronic, relapsing nature of the disease and the difficulties inherent in treatment planning. Though the biologics are perhaps the most promising of available psoriasis treatments, the decision to institute a given therapy may be fraught with complexity for the clinician. Patients now hear of these promising new treatments for psoriasis via print, television and radio advertising; they frequently come to their physician asking if they are eligible for any of these agents and, if so, 'which biologic is best?'. This paper attempts to determine the ideal biologic agent based upon several parameters: FDA- and EU-approved indications, therapeutic efficacy, impact on quality of life, cost-effectiveness, and safety profile. Certainly the physician is central to medical decision-making, though ultimately patient preference may play the largest role in determining the 'best' biologic agent. There is no single ideal biologic for all patients and a physician's job is to educate patients on the relative advantages and disadvantages of each agent. Through informed discussion, the clinician can help each individual patient decide which biologic agent is ideal for them.

Cytokines and anticytokines in psoriasis

BACKGROUND

Psoriasis is a chronic autoimmune hyperproliferative skin disease of varying severity affecting approximately 2-3% of the general population in the USA and Europe. Although the pathogenesis of psoriasis has not been fully elucidated, an immunologic-genetic relationship is likely. Cutaneous and systemic overexpression of various proinflammatory cytokines (TNF, interleukins, interferon-gamma) has been demonstrated in psoriatic patients.

METHODS

We reviewed the current database literature and summarized the involvement of cytokines and their receptors in the pathogenesis and treatment of psoriasis.

RESULTS

Although many cytokine/anti-cytokine therapies have been conducted, TNF antagonists in the treatment of both psoriasis arthropatica and vulgaris appear to be the most widely used clinically. Interestingly, the efficacy and tolerability of some cytokines (rhIL-11 or ABX-IL-8,) were found to be much lower than expected.

CONCLUSIONS

Preliminary results obtained with cytokine and anti-cytokine therapies appear promising and as such continued research is clearly indicated.

Genes and structure of selected cytokines involved in pathogenesis of psoriasis

Psoriasis is a common skin disease involving 1-4% of human population worldwide, of strong genetic background. The following cytokines are directly involved in psoriasis: TNF, IL-1, IL-2, IL-6, IL-7, IL-8, IL-15, IL-18, IL-19, IL-20, IL-23 whereas IL-4, IL-10, IL-12 as well as IL-11, IL-17 and IFN-gamma are rather indirectly engaged. This work is a review of some genetic factors and structure of selected cytokines and receptors and their genes location.

Functional characterization of CD4+CD25+ regulatory T cells differentiated in vitro from bone marrow-derived haematopoietic cells of psoriasis patients with a family history of the disorder

BACKGROUND

In psoriasis CD4+CD25+ regulatory T cells are functionally deficient. The imbalance between regulatory and effector T-cell functions is important for inducing psoriasis. It is reasonable to speculate that the dysfunctional activity of CD4+CD25+ regulatory cells may originate partly from the abnormal haematopoietic cells determined mainly by genetic background.

OBJECTIVES

To test the hypothesis that haematopoietic stem cells are responsible for dysfunctional CD4+CD25+ regulatory cells in psoriasis.

METHODS

Bone marrow-derived CD34+ haematopoietic cells from patients with psoriasis (with a family history of psoriasis) and from normal controls were differentiated into T cells in vitro. CD4+CD25+ T cells were isolated by an immunomagnetic bead method, and proliferation activity and capacity for cytokine secretion were determined. Furthermore, the ability of CD4+CD25+ T cells to suppress the proliferative responses of allogeneous peripheral blood CD4+CD25- effector T cells was assessed in vitro.

RESULTS

The differentiated CD4+CD25+ T cells of psoriatic origin showed similar characteristics to those of normal volunteers, including proliferation activity and secretion profile of the cytokines interleukin (IL)-2, IL-4, IL-8, IL-10 and interferon (IFN)-gamma. However, proliferation and secretion levels of the cytokines IL-2 and IL-10 for CD4+CD25+ cells of psoriatic CD34+ cell origin were significantly lower than those of normal controls in response to streptococcal superantigen (Strep-A). In particular, CD4+CD25+ T cells differentiated from psoriatic CD34+ cells were functionally insufficient to restrain effector T-cell proliferation.

CONCLUSIONS

CD4+CD25+ T cells differentiated in vitro from haematopoietic cells of patients with psoriasis are impaired in regulatory function. The dysfunction of psoriatic CD4+CD25+ T cells may be due to inherent genetic programming passed down from bone marrow-derived haematopoietic cells.

A phase 1, double-blind, placebo-controlled study evaluating single subcutaneous administrations of a human interleukin-12/23 monoclonal antibody in subjects with plaque psoriasis

OBJECTIVE

To evaluate safety, pharmacokinetics, pharmacodynamics, and clinical response of single subcutaneous (s.c.) administrations of a human monoclonal antibody against the p40 subunit of IL-12/23 (IL-12/23 mAb) in subjects with moderate-to-severe psoriasis.

METHODS

Twenty-one subjects were enrolled sequentially into 4 dose cohorts (0.27, 0.675, 1.35, and 2.7 mg/kg) and randomized to IL-12/23 mAb or placebo in a 4:1 ratio. Laboratory/clinical parameters and pharmacokinetics were evaluated through Week 24; mRNA cytokine expression was measured in psoriatic plaques at Week 1.

RESULTS

Mostly mild adverse events and no serious adverse events were reported. The pharmacokinetics (Cmax and AUC) of IL-12/23 mAb increased in an approximately dose-proportional manner. Of the 17 subjects who received IL-12/23 mAb, 13 achieved PASI 75 (compared with no placebo subjects). mRNA expression of IL-8, IL-18, and IFN-gamma in psoriatic plaques decreased in subjects with sustained Psoriasis Area and Severity Index (PASI) improvement.

LIMITATIONS

Interpretation of results is limited due to the small sample size in each dose cohort.

CONCLUSION

A single s.c. administration of IL-12/23 mAb was well tolerated and showed clinical response in subjects with moderate-to-severe psoriasis.

Echinococcosis: A Possible Etiology in Psoriatic Disease

We aimed to investigate seroprevalence of Echinococcus granulosus in patients with psoriasis to determine a possible etiologic role, since both echinococcosis and psoriasis are defined as T cell-mediated diseases. Forty psoriatic patients and 50 age- and sex-matched control subjects were included in the study. IgG-specific ELISA was used to determine seropositivity. E. granulosus-specific IgG antibodies were found to be positive in 17/40 (42.5%) of the patients with psoriasis and in 11/50 (22%) of the control subjects (p = 0.008). Our results suggest that echinococcosis might be one of the causative pathogens in the etiopathogenesis of psoriasis in highly endemic regions.

Regulatory T cells, a potent immunoregulatory target for CAM researchers: modulating tumor immunity, autoimmunity and alloreactive immunity (III)

Regulatory T (T(reg)) cells are the major arbiter of immune responses, mediating actions through the suppression of inflammatory and destructive immune reactions. Inappropriate T(reg) cell frequency or functionality potentiates the pathogenesis of myriad diseases with ranging magnitudes of severity. Lack of suppressive capability hinders restraint on immune responses involved in autoimmunity and alloreactivity, while excessive suppressive capacity effectively blocks processes necessary for tumor destruction. Although the etiology of dysfunctional T(reg) cell populations is under debate, the ramifications, and their mechanisms, are increasingly brought to light in the medical community. Methods that compensate for aberrant immune regulation may not address the underlying complications; however, they hold promise for the alleviation of debilitating immune system-related disorders. The dominant immunoregulatory nature of T(reg) cells, coupled with recent mechanistic knowledge of natural immunomodulatory compounds, highlights the importance of T(reg) cells to practitioners and researchers of complementary and alternative medicine (CAM).

Peptidoglycan and peptidoglycan-specific Th1 cells in psoriatic skin lesions

We have previously demonstrated, in psoriatic skin lesions, the presence of a subset of dermal CD4+ T cells that produce interferon-gamma (IFN-gamma) in response to a mixture of cell wall proteins extracted from group A streptococci. However, the identity of the antigen(s) involved is unknown. To investigate the hypothesis that peptidoglycan (PG), the major constituent of the streptococcal cell wall, acts as a T cell activator in psoriasis, we performed in situ analysis to detect antigen-presenting cells containing PG in lesional versus non-lesional skin, and determined proliferation and IFN-gamma responses of lesional skin T cells. Increased numbers of PG-containing cells were detected in the dermal papillae and cellular infiltrates of guttate and chronic plaque skin lesions compared with normal and non-lesional psoriatic skin. A varying proportion of these were CD68+ macrophages, but the remaining cells did not double stain for either Langerhans' or dendritic cell markers. Psoriatic dermal streptococcal-specific CD4+ T cell lines proliferated and produced IFN-gamma in a self HLA-DR allele-restricted manner in response to streptococcal PG, excluding mitogenic or superantigenic stimulation, but were unresponsive to staphylococcal PG. Similarly, psoriatic staphylococcus-specific T cell lines recognized staphylococcal, but not streptococcal, PG by IFN-gamma production. The presence of PG-containing macrophages in close association with PG-specific CD4+ T cells in lesional skin suggests that PG may be responsible, at least in part, for T cell activation in psoriasis.

Tumour necrosis factor alpha as a therapeutic target for immune-mediated inflammatory diseases

Preclinical studies have identified and validated tumour necrosis factor alpha (TNFalpha) as a key disease molecule and therapeutic target for immunotherapeutic intervention in many immune-mediated inflammatory diseases. Clinical indications include rheumatoid arthritis, Crohn's disease, ankylosing spondylitis and psoriasis. Recent clinical findings indicate that many chronic inflammatory disorders share certain pathogenic pathways, whereas others are limited to particular disease phenotypes. Better understanding of these pathogenic pathways will inform the development of new therapeutic approaches leading to more complete and sustained disease remissions.

Dysfunctional blood and target tissue CD4+CD25high regulatory T cells in psoriasis: mechanism underlying unrestrained pathogenic effector T cell proliferation

The balance between regulatory and effector functions is important for maintaining efficient immune responses, while avoiding autoimmunity. The inflammatory skin disease psoriasis is sustained by the ongoing activation of pathogenic effector T cells. We found that a CD4(+) T lymphocyte subpopulation in peripheral blood, phenotypically CD25(high), CTLA-4(+), Foxp3(high) (regulatory T (Treg) cells), is deficient in its suppressor activity in psoriasis. This was associated with accelerated proliferation of CD4(+) responder T cells in psoriasis, the majority of which expressed CXCR3. Nevertheless, criss-cross experiments isolated the defect to psoriatic Treg cells. To examine Treg cells in a nonlymphoid tissue of a human T cell-mediated disease, Treg cells were also analyzed and isolated from the site of inflammation, psoriatic lesional skin. At the regulatory vs effector T cells ratios calculated to be present in skin, however, the psoriatic Treg cell population demonstrated decreased suppression of effector T cells. Thus, dysfunctional blood and target tissue CD4(+)CD25(high) Treg cell activity may lead to reduced restraint and consequent hyperproliferation of psoriatic pathogenic T cells in vivo. These findings represent a critical component of human organ-specific autoimmune disease and may have important implications with regard to the possible therapeutic manipulation of Treg cells in vivo.

p16 expression in psoriatic lesions following therapy with propylthiouracil, an antithyroid thioureylene

Plaque formation is a characteristic finding in patients with psoriasis and reflects cytokine-induced keratinocyte proliferation and/or impaired apoptosis of keratinocytes. Antithyroid thioureylenes such as propylthiouracil (PTU) and methimazole (MMI) are effective in the treatment of plaque psoriasis. Following PTU and MMI treatment, proliferative cell nuclear antigen (PCNA) expression is significantly reduced, suggesting that these medications have an antiproliferative effect. p16 is an antiapoptotic protein that is present in relative abundance in psoriatic plaques and is believed to play a potential role in the persistent senescence and impaired apoptosis of the keratinocytes in the plaque. This study examined p16 expression in biopsy samples of eight patients with plaque psoriasis given 300 mg of propylthiouracil in divided doses for 3 months. Despite significant clinical and histological improvement with PTU treatment, p16 expression was essentially unchanged, suggesting that the beneficial effect of PTU in psoriasis is not mediated through a decrease in p16 expression. The effect of PTU on other antiapoptotic proteins such as bcl-xL remains to be determined.

Disease mimicry--a pathogenetic concept for T cell-mediated autoimmune disorders triggered by molecular mimicry?

Molecular mimicry is considered as a mechanism by which infectious pathogens may break immunological tolerance and cause autoimmune disease. It implicates that peptides shared between pathogen and host may induce cross-reactive immune reactions. According to this hypothesis, the resulting autoimmune response actually represents a secondary immune response. It is mediated by cross-reactive T cells that have been educated in a primary immune response against a particular pathogen. Using psoriasis vulgaris as a model, this article discusses the potential functional consequences molecular mimicry should have for the resulting autoimmune disease. It proposes that due to the functional memory of T cells, which is an integral feature of adaptive immunity, the phenotype of an autoimmune disease induced by molecular mimicry should reflect the immune mechanisms raised in the primary immune response. This process might be called 'disease mimicry'.

Current concepts in the immunopathogenesis of psoriasis

There is much evidence to support the concept that psoriasis is a type 1 autoimmune disease, primarily mediated by interferon gamma and other inflammatory cytokines. There has been renewed interest in the role of components of the innate immune system, however,and it may be that overlap between the innate and acquired arms of the immune system can better explain immunopathogenesis in psoriasis. Relevant cell types, receptors, and immune mediators within these traditional boundaries of the immune system are discussed.Finally, pathogenic contributions from important psoriatic mouse models and recent genomic data using the new gene chip technology are elaborated.

Correlation of psoriasis activity with abundance of CD25+CD8+ T cells: conditions for cloning T cells from psoriatic plaques

The role of T cells in the pathogenesis of psoriasis is widely acknowledged. However, key aspects of their precise function in the disease as well as the relative pathogenic contribution of T-cell subsets are still unknown. T-cell clones have been isolated from psoriatic plaques but a study of conditions affecting the isolation and expansion of T-cell clones from psoriatic skin has not been reported to date. Here, we observe a correlation of disease activity with the frequency of the CD3(+)CD8(+)CD25(+) subset. We show that prolonged in vitro culture changes the phenotypic subset distribution of T-cell lines derived from psoriatic skin and that T-cell clones can be isolated by sorting of CD25(+) cells emigrated from skin fragments after 7 days. We evaluate various conditions affecting expansion of psoriatic T-cell clones in vitro and show that blocking apoptosis can facilitate proliferation of activated T-cell clones in vitro. Our results indicate a prominent role of the CD8(+)CD25(+) T-cell subset in disease pathogenesis and should be useful in the design of experiments aiming at a systematic analysis of the specificity of clones present in psoriatic plaques.

Reduced IFN-gamma responses associated with HLA-DR15 presentation of streptococcal cell wall proteins to dermal Th-1 cells in psoriasis

We have recently described a group A streptococcal (GAS)-reactive Th-1 subset specifically present in skin lesions of chronic plaque psoriasis. To investigate MHC presentation of GAS cell wall proteins, dermal T cell lines (TCL) cultured from the lesional skin of 39 HLA-typed psoriasis patients were stimulated with a cell wall extract, stained for intracellular IFN-gamma expression, and analyzed by flow cytometry. TCL from a further seven psoriasis patients were also tested with S. mutans extract. Eight TCL were tested in the presence of anti-Class II antibodies or allogeneic antigen-presenting cells. The dermal T cell IFN-gamma responses to the cell wall extract, which ranged from < 1 to 28%, were significantly higher than that to S. mutans extract (p = 0.0052) and were self-HLA-DR allele restricted. A significantly decreased response was observed in TCL from DR15+ (n = 13) versus DR15- (n = 26) patients (p = 0.0377). In addition, DR15+ patients had a later age of onset of disease and a decreased history of sore throats. In contrast, TCL from HLA-DR7+ (n = 23) patients responded similarly to those from individuals lacking the DR7 allele. However, DR7+ patients who coexpressed the MHC Class I antigen, Cw6 (n = 14) had a significantly higher IFN-gamma response than Cw6-, DR7+ patients (n = 7; p = 0.0288) whose responses were also significantly lower than those of patients expressing non-DR7 alleles (n = 16; p = 0.0302). This study has shown that HLA-DR15 expression is associated with a reduced dermal Th-1 response to GAS cell wall proteins in patients with psoriasis. It is proposed that HLA-DR allelic variation may contribute to disease phenotype via effects on the immune response to group A streptococci.

Selective response of dermal Th-1 cells to 20-50 kDa streptococcal cell-wall proteins in chronic plaque psoriasis

We have recently described a dermal Th-1 subset in skin lesions of psoriasis which recognizes cell-wall extract isolated from group A streptococci (GAS). As a first step in the identification of the streptococcal proteins involved, dermal T-cell lines (TCL) cultured from the lesional skin of 12 human leucocyte antigen (HLA)-typed psoriasis patients were stimulated with GAS cell-wall extract and 14 fractions (MWt approximately 20-100 kDa) separated from the cell-wall extract by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution, stained for intracellular interferon-gamma(IFN-gamma) expression and analysed by flow cytometry. All the TCL responded to GAS cell-wall extract to varying extents (3.5-27.6% IFN-gamma+). This response was consistently directed against 20-50 kDa cell-wall fractions and inhibited by anti-HLA-DR antibody. TCL with higher responses to GAS cell-wall extract recognized a larger number of fractions within this range than the lower responder TCL. No difference between the level and pattern of response to the fractions was observed for TCL from HLA-DR7+ (n = 6) and HLA-DR7- (n = 6) individuals. This preliminary study has shown a selective response to lower MWt proteins expressed on GAS cell wall by skin Th-1 cells in psoriasis. Further studies are required to identify the proteins involved.

Cytokine and anticytokine therapy in dermatology

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

The role of T cells in psoriasis

Evidence for a key role of T cells in the pathogenesis of psoriasis has come from both experimental and clinical data. Initially, generalized immunosuppressants, intended for use in transplant settings, were found to improve clinical signs and symptoms of psoriasis. Their efficacy attracted attention to the activated T cells that are a major component of the inflammatory infiltrate of psoriatic lesions. Further research determined that T cells from patients with psoriasis could transmit disease in animal models. These findings laid the groundwork for characterizing the pathogenesis of psoriasis as immune mediated with skin-directed T cells playing a central role. Once these pathogenic T cells have entered the skin, they become activated and release cytokines and chemokines to attract other immune cells to perpetuate the inflammatory cascade. As the role of the T cell in psoriasis has evolved and understanding of immunopathology has increased, a multitude of biologic targets have been revealed. Newer strategies for the treatment of psoriasis have therefore focused on modifying T cells in this disease through direct elimination of activated T cells, inhibition of T-cell activation, or inhibition of cytokine secretion or activity. The mechanisms by which these new biologic agents act on psoriasis will affect their profile of efficacy and safety. Important selection criteria for optimal antipsoriatic therapies include long-term safety and tolerability, ability to produce long-lasting remissions, and convenient dosing regimens.

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.

Reactivity of resident immunocytes in normal and prepsoriatic skin using an ex vivo skin-explant model system

CONTEXT

While it is well known that both exogenous and endogenous stimuli can trigger appearance of psoriatic lesions, the initial cellular and molecular events mediated by immunocompetent cells normally resident in prepsoriatic (PN) skin are not well understood. Moreover, it is unclear whether there are any fundamentally important differences in the innate immune response of normal healthy skin (NN skin) versus PN skin. Since acute tissue responses to stimuli involve both resident cells and immunocytes recruited rapidly from circulation, it is difficult to discern the contribution of endogenous cells normally present in skin.

OBJECTIVE

To solely characterize the reactivity of resident immunocytes using an experimental system.

DESIGN

To probe the activation potential of resident immunocytes in NN (n = 18) and PN skin (n = 10), a short-term ex vivo organ culture system containing interleukin (IL)-2 was established and characterized. To mimic exogenous or environmental trigger factors, bacteria-derived superantigens and lipopolysaccharide were added to the skin-explant assays, whereas endogenous trigger factors were investigated using heat shock proteins.

RESULTS

Using this skin-explant assay, both NN and PN skin gave rise to an expansion of various T-cell subsets, which could differentially produce various cytokines and a growth factor (keratinocyte growth factor), depending on the stimulus and source of skin. Bacterial superantigens were relatively potent inducers of interferon-gamma, and natural killer-T cells were observed proliferating from PN skin.

CONCLUSIONS

Despite relatively few T cells normally residing in either NN or PN skin, initiation of skin explants from both sets of individuals in the presence of IL-2 triggered vigorous T-cell proliferation and cytokine/growth factor release. These results demonstrate the utility of this skin-explant assay system to further investigate quantitative and qualitative immune responses of NN and PN skin.

[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.

NKT cell subsets in infection and inflammation

We recently identified two stably expressed cell surface markers, IL-18R and ST2L, which are selectively expressed on T1/NK1 and T2/NK2 cells, respectively. Here we use these molecules in direct ex vivo analysis of PBMCs from patients with AIDS, psoriasis (PS) atherosclerosis and to show the importance of these markers as determinants of the functional dichotomy of lymphocyte subsets, in particular NKT. In a cohort of 22 HIV patients made up of a mixture of long term non-progressors, seroconvertors, progressors and asymptomatics, we found a clear NKT1 to NKT2 shift (P=0.001) in the HIV-infected individuals. We also show a predominance of NKT2 cells over NKT1 cells in the PBMCs of patients with mild to moderate PS (N=13, P=0.005) but not in atopic dermatitis or healthy controls. However, in patients (N=6) requiring surgery for aneurysm, a predominance of Type 1 (IL-18R(+)) NKT lymphocytes over NKT2 was detected among infiltrating lymphocytes isolated from atherosclerotic plaques. Our data therefore demonstrate that ST2L and IL-18R could serve as important determinants of the immune status of human diseases.

CD4+ T-cells from peripheral blood of a patient with psoriasis recognize keratin 14 peptide but not 'homologous' streptococcal M-protein epitope

Psoriasis has been recognized as an immunologically mediated inflammatory skin disease that has been associated with group A, beta-haemolytic streptococcal infections. Notably cross-reactive autoimmune mechanism, which is mediated by T cells reacting to epitopes that are common to streptococcal M-protein and keratin, has been proposed in psoriasis. In order to investigate this possibility, peptides corresponding to M-protein and human epidermal keratin, which share some amino acid sequence between them, were synthesized and tested for their ability to stimulate T-cells of patients with psoriasis. Among five cases examined, we isolated a CD4(+) T-cell line that recognized the type I keratin (K14)(p168-181) when it was presented by the patient's HLA-DR molecules from a single psoriatic patient, whose MHC allele was HLA-A2/A26, -B27/B16, -DR4/DR8, -DQ8. Further analysis disclosed that the critical peptide recognized by the T-cell line was 10-mer keratin(p171-180) (DLRNKILTAT). However, corresponding M6 protein with homology to K14 did not stimulate the T-cell response and no evidence for cross-reactivity was obtained. The K14-responsive T cell line produced IFN-gamma, but little IL-4 when stimulated with irradiated autologous PBMC pulsed with this peptide. Thus, the finding that human epidermal keratin peptide is immunogenic in a psoriasis patient may provide the evidence that T lymphocytes play an important role in the pathogenesis of psoriasis as an autoimmune disorder participated with Th1 like cells. However, the keratin-responsive T cell line was detected in only one of five cases of psoriasis examined, suggesting that such T cell line appears to be not so popular in psoriatic patients. No evidence for cross-reactivity to streptococcal M protein also suggests that the contribution of streptococci may simply be inducing proliferation of various repertoire of T cells (including K14-responsive T cells) possibly through a superantigen-dependent process.

Cytokine blocking agents in dermatology

Cytokines are intercellular messengers that have an important role in the development and maintenance of cutaneous inflammation. The primacy of cytokines in eliciting cutaneous immune responses makes them a highly attractive target for new biological response modifiers. Targeting of cytokines is still in its infancy for therapy of skin disease. However, blocking tumour necrosis factor alpha by infliximab or etanercept has shown particular promise, especially in the management of psoriasis. Anecdotally, this approach is also effective for a variety of dermatological conditions including pyoderma gangrenosum and Behçet's syndrome. We review the current and prospective roles of cytokine blocking agents in the treatment of skin disease.

Increased microorganisms DNA levels in peripheral blood monocytes from psoriatic patients using PCR with universal ribosomal RNA primers

It has long been suspected that systemic and focal infections cause or exacerbate psoriatic lesions. We previously showed that peripheral blood monocytes in psoriatic patients are activated and overproduce inflammatory cytokines. In addition, it has been reported that macrophages activated by ingesting microorganisms release tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. Therefore we hypothesized that the monocytes in psoriatic patients may be activated by ingesting microorganisms and overproduce inflammatory cytokines. We examined the detection of microorganism DNA in monocytes from 15 patients with psoriasis vulgaris and from 12 healthy controls. DNA was extracted from monocytes, and a polymerase chain reaction (PCR) assay was performed for the detection using universal primers from conserved regions of the bacterial 16S ribosomal RNA gene or the fungal 18S rRNA gene. At the same time, we calculated the psoriasis area and severity index (PASI) scores and analyzed their correlations with the microorganisms DNA levels. The results showed that bacterial 16S DNA levels in monocytes were significantly higher in psoriatic patients than in controls. The fungal 18S DNA levels were also higher in psoriatic patients than in controls, but the differences were not significant. Although the microorganisms DNA levels in monocytes of psoriatic patients were high, there was no correlation between the bacterial DNA levels in monocytes of the psoriatics and PASI scores. Our study suggests that monocytes in psoriatic patients engulf more bacteria than there in controls, causing an activation of monocytes and triggering the formation of new lesions in the initial stages of psoriasis.

Induction of skewed Th1/Th2 T-cell differentiation via subcutaneous immunization with Freund's adjuvant

CD4+ T cells differentiate into at least two distinct subsets, Th1 and Th2, that are characterized by their cytokine-producing profiles. In this study, we attempted to delineate whether and how CD4+ T-cell responses could be skewed in one direction or another. BALB/c mice were immunized with chicken ovalbumin (OVA) emulsified with either incomplete or complete Freund's adjuvant (IFA or CFA). When lymph node cells were assessed on day 7, antigen specific proliferation was similarly observed both in the mice immunized with IFA and CFA. In contrast, on day 28 there was a less significant response in the mice primed with IFA than in those primed with CFA. ELISA analyses revealed more Th1 predominant cytokine production by T cells immunized with OVA+CFA rather than in IFA, which resulted in balanced IFN-gamma and IL-4 production. Flow cytometric analyses of intracellular cytokines confirmed that T cells from mice primed with CFA produced Th1 cytokines more predominantly. When lymph node dendritic cells (DC) were compared for their co-stimulatory molecule expression, priming with CFA and IFA similarly upregulated CD80 and CD86 expression by lymph node DC, and no significant differences were observed in CD40, 54, 80 and 86 expression between the DC harvested from IFA and CFA immunized mice. In addition, both priming with IFA and CFA similarly induced IL-12 production by DC. Thus, although the reason(s) for the preferential induction of a Th1/Th2 response remains unknown, these results indicate that a relatively Th1/Th2 skewed response is differentially induced by different types of adjuvants, and induction of a Th1 skewed response may be responsible for long lasting cellular immunity.

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.

Polymorphisms in angiotensinogen gene (M235T and G(-6)A) in multifactorial diseases

The aim of the study is to compare results of three association (case-control) studies in three multifactorial disorders (essential hypertension, atopic diseases and psoriasis) with two polymorphisms of angiotensinogen gene (M235T and A(-6)G). The diseases were chosen for their multigenic base and different immunological characteristic (Th1, Th2 and Thps) and angiotensinogen gene for its pleiotropic functional effects in general adaptive reactions. In all (control as well as case) groups, tight linkage disequilibrium between the polymorphisms was found. The strength of linkage (%) differed among the group. The direction of the linkage is identical in all groups (T is combined with A, M is combined with G). In hypertensive-normotensive study, only Hardy-Weinberg disequilibria were found, especially in men. No case-control differences were found for either single alleles or for allelic concurrence of both polymorphisms. In atopy-control study, marginal case-control differences in single allele distribution of both polymorphisms were found, but only in women. In psoriasis-control study, the only significant case-control difference was found,when genotypes MTAA and MTGG were present in 2/136 psoriatic patients vs. 20/142 control subjects (OR 0.1, 95% confidence interval 0.02-0.42, P=0.00015). The frequent polymorphisms in pleiotropic genes can form different formulae of genotype distribution in different multigenic diseases according to their contribution to the onset and/or progression of the disease in some evolutionary consequences.

Dominant lesional T cell receptor rearrangements persist in relapsing psoriasis but are absent from nonlesional skin: evidence for a stable antigen-specific pathogenic T cell response in psoriasis vulgaris

In a previous study we reported that clonally expanded T cell receptor beta-chain rearrangements characterized the T cell receptor usage in skin lesions of psoriasis vulgaris and indicated antigen-specific T cell selection. To assess the relevance of clonal T cell expansion for disease progression, we now determined if select clonal T cell receptor rearrangements persisted over time and were present in nonlesional skin. Sequential biopsies were taken from psoriatic skin lesions of two patients. V-D-J junctional regions of T cell receptor beta-chain variable region gene families 2, 3, 6, 13S1, and BV17 were cloned and sequenced, as these particular BV gene families are preferentially selected in psoriatic skin lesions. The lesional T cell receptor rearrangements were compared with the T cell receptor usage in nonlesional skin and in blood. Several T cell receptor beta-chain rearrangements with high transcript frequency in the first lesional biopsy were again found in sequential lesional biopsies taken as much as 3 y later from psoriasis relapses. Only T cell receptor beta-chain rearrangements with low transcript abundance showed variability in that several clones appeared for the first time or disappeared. Although nonlesional skin also exhibited a restricted T cell receptor usage with clonal T cell receptor rearrangements, the T cell receptor usage in lesional and nonlesional skin differed nearly completely. The select lesional recurrence of identical T cell receptor rearrangements reveals that inflammation in psoriasis involves the same clonally expanded T cell populations and the same antigens over prolonged periods of time. It hereby suggests that specifically recruited and locally expanded T cell clones are permanently involved in psoriatic inflammation and may play a crucial part in disease perpetuation.