Gamze Piskin

In vitro and in situ expression of IL-23 by keratinocytes in healthy skin and psoriasis lesions: enhanced expression in psoriatic skin

Keratinocytes contribute to cutaneous immune responses through the expression of cytokines. We investigated whether human keratinocytes can express IL-23, a newly defined IFN-γ-inducing cytokine composed of a unique p19 subunit and a p40 subunit shared with IL-12. Cultured keratinocytes from normal and lesional psoriatic skin were found to express constitutively mRNA for both subunits of IL-23. Low but significant levels of the heterodimeric IL-23 protein could be detected in cell lysates and supernatants from stimulated keratinocytes by immunoblotting and ELISA. Functional analysis showed that these low levels of keratinocyte-derived IL-23 were sufficient to enhance the IFN-γ production by memory T cells. Immunostaining of skin sections confirmed expression of both subunits of IL-23 by keratinocytes in situ and also revealed expression of this cytokine in the dermal compartment. IL-23 expression was significantly higher in psoriatic lesional skin, compared with normal and psoriatic nonlesional skin. The immunostained preparations of cultured cells and IL-23 levels in culture supernatants did not show any difference between normal and psoriatic keratinocytes indicating no intrinsic aberration of IL-23 expression in keratinocytes from psoriatic skin. Double staining of cytospin preparations demonstrated that IL-23 p19 is also expressed by epidermal Langerhans cells, dermal dendritic cells, and macrophages. Psoriasis is a chronic inflammatory skin disease mediated by IFN-γ-expressing type 1 memory T cells. As IL-23 is important to activate memory T cells to produce IFN-γ, its augmented expression of IL-23 by keratinocytes and cutaneous APC may contribute to the perpetuation of the inflammation process in this disease.

Overrepresentation of IL-17A and IL-22 Producing CD8 T Cells in Lesional Skin Suggests Their Involvement in the Pathogenesis of Psoriasis

Background Although recent studies indicate a crucial role for IL-17A and IL-22 producing T cells in the pathogenesis of psoriasis, limited information is available on their frequency and heterogeneity and their distribution in skin in situ. Methodology/Principal Findings By spectral imaging analysis of double-stained skin sections we demonstrated that IL-17 was mainly expressed by mast cells and neutrophils and IL-22 by macrophages and dendritic cells. Only an occasional IL-17pos, but no IL-22pos T cell could be detected in psoriatic skin, whereas neither of these cytokines was expressed by T cells in normal skin. However, examination of in vitro-activated T cells by flow cytometry revealed that substantial percentages of skin-derived CD4 and CD8 T cells were able to produce IL-17A alone or together with IL-22 (i.e. Th17 and Tc17, respectively) or to produce IL-22 in absence of IL-17A and IFN-γ (i.e. Th22 and Tc22, respectively). Remarkably, a significant proportional rise in Tc17 and Tc22 cells, but not in Th17 and Th22 cells, was found in T cells isolated from psoriatic versus normal skin. Interestingly, we found IL-22 single-producers in many skin-derived IL-17Apos CD4 and CD8 T cell clones, suggesting that in vivo IL-22 single-producers may arise from IL-17Apos T cells as well. Conclusions/Significance The increased presence of Tc17 and Tc22 cells in lesional psoriatic skin suggests that these types of CD8 T cells play a significant role in the pathogenesis of psoriasis. As part of the skin-derived IL-17Apos CD4 and CD8 T clones developed into IL-22 single-producers, this demonstrates plasticity in their cytokine production profile and suggests a developmental relationship between Th17 and Th22 cells and between Tc17 and Tc22 cells.

Psoriasis: dysregulation of innate immunity.

The current understanding of the function of natural killer (NK) T cells in innate immunity and their potential to control acquired specific immunity, as well as the remarkable efficacy of antitumour necrosis factor‐α biological treatments in psoriasis, forces us to refine the current T‐cell hypothesis of psoriasis pathogenesis, and to give credit to the role of innate immunity. Psoriasis might be envisioned to be a genetically determined triggered state of otherwise dormant innate immunity. This aggravated state of innate immunity is represented by the activity of NK T cells, dendritic cells, neutrophils and keratinocytes, leading to the recruitment and activation of preferentially type 1 T cells, possibly in an antigen‐independent way. Keratinocytes in psoriasis then are sensitive to the effects of T‐cell activation and cytokine production, interferon (IFN)‐γ, by responding with psoriasiform hyperplasia. The chronic inflammation of psoriatic lesions suggests that this might be due to a deficiency in downregulation processes (e.g. a defect in the regulatory T‐cell repertoire) and/or the persistence of an unknown trigger resulting in an exaggerated innate immune response.

Clinical improvement in chronic plaque-type psoriasis lesions after narrow-band UVB therapy is accompanied by a decrease in the expression of IFN-gamma inducers -- IL-12, IL-18 and IL-23.

Abstract:  Type‐1 cytokine‐producing T cells are important in the pathogenesis of psoriasis vulgaris, for which efficient therapy is provided by means of narrow‐band ultraviolet‐B (NB‐UVB). The expression of the type‐1 cytokine interferon‐γ (IFN‐γ) is regulated by interleukin‐12 (IL‐12), IL‐15, IL‐18 and IL‐23; however, not much is known about the effect of this therapy on the levels of these cytokines in lesional psoriatic skin in situ. In this study, we investigated the effects of NB‐UVB therapy on the expression of IFN‐γ‐inducing cytokines. Ten patients with chronic plaque‐type psoriasis selected to be treated with NB‐UVB therapy were recruited for these experiments and the expression of cytokines IL‐12, IL‐15, IL‐18, IL‐23 and IFN‐γ in lesional psoriatic skin before, during and after therapy was determined with the help of immunohistochemistry. Double staining was performed in order to determine the cell types expressing these cytokines. The decrease in the psoriasis area and severity index was accompanied by a significant decrease in the expression of IFN‐γ, and concomitantly, significant reduction of IFN‐γinducers – IL‐12, IL‐18 and IL‐23. Thus, we concluded that the decrease of IFN‐γ expression in psoriasis lesions after NB‐UVB therapy could be a result of diminished expression of IL‐12, IL‐18 and IL‐23 in lesional skin. Therapies targeting these three cytokines should, therefore, be considered in the treatment of psoriasis.

Review and expert opinion on prevention and treatment of infliximab-related infusion reactions

Infliximab (Remicade®; Schering‐Plough, Kenilworth, NJ, U.S.A.) is a chimeric monoclonal antibody that acts as a tumour necrosis factor‐α inhibitor. Infliximab is registered for the treatment of rheumatoid arthritis, psoriatic arthritis, Crohn disease, ulcerative colitis, ankylosing spondylitis and plaque‐type psoriasis. Like other foreign protein‐derived agents, infliximab may lead to infusion reactions during and after infusion. Infusion reactions occur in 3–22% of patients with psoriasis treated with infliximab. Most of these reactions are mild or moderate and only few are severe. Nevertheless, they may lead to discontinuation of treatment. As infliximab for psoriasis is prescribed as a last resort and is in most cases very effective, discontinuation of treatment is undesirable. With proper care and prevention of the infusion reactions the need to discontinue treatment with infliximab can be diminished. The objective of this article is to present a guideline for the management of infliximab‐related infusion reactions, based on the best available evidence. This guideline can be used in patients with psoriasis as well as in dermatology patients receiving infliximab for off‐label indications such as hidradenitis suppurativa or pyoderma gangrenosum.

Ultraviolet B Radiation Induces a Transient Appearance of IL-4+ Neutrophils, Which Support the Development of Th2 Responses

UVB irradiation can cause considerable changes in the composition of cells in the skin and in cutaneous cytokine levels. We found that a single exposure of normal human skin to UVB induced an infiltration of numerous IL-4+ cells. This recruitment was detectable in the papillary dermis already 5 h after irradiation, reaching a peak at 24 h and declining gradually thereafter. The IL-4+ cells appeared in the epidermis at 24 h postradiation and reached a plateau at days 2 and 3. The number of IL-4+ cells was markedly decreased in both dermis and epidermis at day 4, and at later time points, the IL-4 expression was absent. The IL-4+ cells did not coexpress CD3 (T cells), tryptase (mast cells), CD56 (NK cells), and CD36 (macrophages). They did coexpress CD15 and CD11b, showed a clear association with elastase, and had a multilobed nucleus, indicating that UVB-induced infiltrating IL-4+ cells are neutrophils. Blister fluid from irradiated skin, but not from control skin, contained IL-4 protein as well as increased levels of IL-6, IL-8, and TNF-α. In contrast to control cultures derived from nonirradiated skin, a predominant type 2 T cell response was detected in T cells present in primary dermal cell cultures derived from UVB-exposed skin. This type 2 shift was abolished when CD15+ cells (i.e., neutrophils) were depleted from the dermal cell suspension before culturing, suggesting that neutrophils favor type 2 T cell responses in UVB-exposed skin.

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.

Abstract: 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‐γ 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‐γ and IL‐4) or RNA was extracted and analyzed for the expressions of IFN‐γ and IL‐4 by PCR. In addition, primary cultures of T cells from dermal cell suspensions were stained intracellularly for IFN‐γ and IL‐4 expression and CD4+ and CD8+ T subsets were analyzed by flow cytometry. IFN‐γ 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‐γ and increase of IL‐4 following UVB irradiation. Both CD4+ and CD8+ dermal T cells were found to produce less IFN‐γ and more IL‐4 following UVB irradiation as determined by flow cytometry. Decrease in IFN‐γ 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.

IL-4 Expression by Neutrophils in Psoriasis Lesional Skin upon High-Dose UVB Exposure

Background: Upon a single high dose of UVB irradiation of psoriatic lesional skin, IFN-γ expression is decreased, whereas IL-4 expression is enhanced. A similar type 1 to type 2 shift was found in dermal T cells derived from irradiated lesional skin as compared to unexposed lesional psoriatic skin. We have found recently that the IL-4 protein detected in situ upon UVB exposure of normal skin was not associated with T cells but with infiltrating neutrophils. Objective: To determine which cell types express IL-4 in psoriatic skin after UVB irradiation. Methods: Skin biopsies were obtained from healthy controls and psoriasis patients before and after local UVB exposure. Double immunohistochemical stainings were performed to determine the identity of IL-4-expressing cells. Results: In the irradiated skin of both healthy controls and patients, IL-4-positive cells coexpressed elastase and CD15, but not CD3. Conclusion: IL-4-expressing cells found in psoriatic skin after a single high-dose UVB exposure appeared to be neutrophils.

Pathological and Immunological Developments in Behcet's Disease

Behcets disease is a rare form of vasculitis that may have systemic multiorgan involvement. Behcets disease was first defined by Hulusi Behcet, a Turkish Professor of Dermatology, in 1937 as a triad of recurrent aphthous stomatitis, genital aphthae, and relapsing uveitis. As this disease can be fatal, an immediate medical treatment is mandatory. So far there is no specific pathological testing or technique available for the diagnosis of the disease, although the International Study Group criteria for the disease are of good sensitivity and specificity. However, quite a portion of patients are misdiagnosed or have been delayed diagnosis. During the ensuing 65 years, multiple systemic associations of the disease including articular, vascular, gastrointestinal, cardiopulmonary, and neurologic involvement have become increasingly apparent. Although the etiology and pathogenesis is not clearly defined, genetic predisposition, infections, and immunological dysfunctions have been implicated. Behcets disease has been reported worldwide but has a distinct geographic distribution, with highest prevalences in countries along with the ancient silk route. Although much has been learned during recent years on the pathogenesis and treatment of the disease, it is still an important cause of morbidity and mortality in areas where it is prevalent. The entitled “Musculoskeletal findings in Behcets disease” addresses the musculoskeletal findings of Behcets disease, the relationship between Behcets disease and spondyloarthropathy disease complex, and the status of bone metabolism in patients with Behcets disease. Professor Fereydoun Davatchi presents us the new diagnosis/classification criteria for Behcets disease. The author finds that ICBD criteria have better sensitivity and accuracy than ISG. In the paper is entitled “Pathophysiology of Behcets disease”, and we think that there is some clinical evidence suggesting that emotional stress and hormonal alterations can influence the course and disease activity of BD. Professor Erkan Alpsoy presents that the new evidence-based treatment is mainly based on the suppression of inflammatory attacks of the disease using immunomodulatory and immunosuppressive agents. In this paper, current state of knowledge regarding the therapeutic approaches is outlined. To provide a rational framework for selecting the appropriate therapy along with the various treatment choices, a stepwise, symptom-based, evidence-based algorithmic approach was developed. The fifth paper entitled “Genetics of Behcets disease” describes HLA and non-HLA genetic association studies in BD. In recent years, several genomewide association studies and genetic polymorphism studies have also found new genetic associations with BD, which may have a supplementary role in disease susceptibility and/or severity. The paper entitled “Histopathological evaluation of Behcets disease and identification of new different skin lesions” proposes that there has been an increase in the studies focusing on the histopathological aspects of Behcets disease diagnostic mucocutaneous lesions. Their results emphasize the value of histopathology and direct immunofluorescence (DIF) in the differential diagnosis of Behcets disease. Tuba Kara and Duygu Dusmez Apa discuss the pathologic features of BD in the tubuler gut. Professor Aysin Kokturk describes that the differential diagnosis depends on a careful evaluation of the medical history and meticulous physical examination to detect concomitant systemic manifestations. Sometimes, some laboratory test may help establish the diagnosis. Subspecialty referral to ophthalmology, rheumatology, neurology, and gastroenterology should be considered when indicated. The paper about BD and endocrine system shows that the avaliable data suggest that there is an increased susceptibility to insulin resistance in patients with BD. And also the authors indicate that not only anterior hypophysis functions but also posterior hypophysis functions can be affected. As BD is a disease of autoimmune process, it may be possible that adrenal insufficiency or alterations in the cortisol levels could be expected. The article entitled “Potential infectious etiology of Behcets disease” indicates that an infectious agent could operate through molecular mimicry, and subsequently the disease could be perpetuated by an abnormal immune response to an autoantigen in the absence of ongoing infection. Potentia bacteria are Saccharomyces cerevisiae, mycobacteria, Borrelia burgdorferi, Helicobacter pylori, Escherichia coli, Staphylococcus aureus, and Mycoplasma fermentans, but the most commonly investigated microorganism is Streptococcus sanguinis. The relationship between streptococcal infections and Behcets disease is suggested by clinical observations that an unhygienic oral condition is frequently noted in the oral cavity of Behcets disease patients. Several viral agents, including herpes simplex virus-1, hepatitis C virus, parvovirus B19, cytomegalovirus, Epstein-Barr virus, and varicella zoster virus, may also have some role. Professor Ozlem Yildirim shows that animal models allow for a more effective investigations into BD. The paper entitled “Development of immunopathogenesis strategies to treat Behcets disease” finds that understanding of the new pathogenic mechanisms based on molecular structure of the disease helps us in improving the novel therapeutic modalities. Umit Tursen Gamze Piskin Torello Lotti Fereydoum Davatchi