Downregulation of TGFbeta isoforms and their receptors contributes to keratinocyte hyperproliferation in psoriasis vulgaris

Immunomodulatory potential of primary cilia in the skin

Primary cilia (PC) are essential signaling hubs for proper epithelial formation and the maintenance of skin homeostasis. Found on most cells in the human body, including skin cells, PC facilitate signal transduction that allows ciliated cells to interact with the immune system via multiple pathways, helping to maintain immune system homeostasis. PC can be altered by various microenvironmental stimuli to develop corresponding regulatory functions. Both PC and ciliary signaling pathways have been shown to be involved in the immune processes of various skin lesions. However, the mechanisms by which PC regulate cellular functions and maintain immune homeostasis in tissues are highly complex, and our understanding of them in the skin remains limited. In this paper, we discuss key ciliary signaling pathways and ciliated cells in the skin, with a focus on their immunomodulatory functions. We have compiled evidence from various cells, tissues and disease models to help explore the potential immunomodulatory effects of PC in the skin and their molecular mechanisms.

Cytokines in psoriasis: From pathogenesis to targeted therapy

Psoriasis is a multifactorial disease that affects 0.84% of the global population and it can be associated with disabling comorbidities. As patients present with thick scaly lesions, psoriasis was long believed to be a disorder of keratinocytes. Psoriasis is now understood to be the outcome of the interaction between immunological and environmental factors in individuals with genetic predisposition. While it was initially thought to be solely mediated by cytokines of type-1 immunity, namely interferon-γ, interleukin-2, and interleukin-12 because it responds very well to cyclosporine, a reversible IL-2 inhibitor; the discovery of Th-17 cells advanced the understanding of the disease and helped the development of biological therapy. This article aims to provide a comprehensive review of the role of cytokines in psoriasis, highlighting areas of controversy and identifying the connection between cytokine imbalance and disease manifestations. It also presents the approved targeted treatments for psoriasis and those currently under investigation.

Mesenchymal stem cell-derived exosomes decrease Hyperplasia in Psoriasis by inducing transforming growth factor β2 (TGF-β2)

BACKGROUND

Psoriasis, a chronic inflammatory skin disease, is increasingly effectively managed with the targeted immunotherapy; however, long-term immunotherapy carries health risks, and loss of response. Therefore, we need to develop the alternative treatment strategies. Mesenchymal stem/stromal cell (M.S.C.) exosomes stand out for their remarkable immunomodulatory properties, gaining widespread recognition. This study investigated whether M.S.C. exosomes can reduce psoriasis-induced hyperplasia by inducing Transforming Growth Factor beta 2 (TGF-beta2) signaling.

METHODOLOGY

Exosomes were isolated from M.S.C.s by ultracentrifugation. Then, scanning electron microscopy was used for the morphology of exosomes. To ascertain the exosome concentration, the Bradford test was used. To ascertain the cellular toxicity of exosomes in Human Umbilical Vein Endothelial Cells ( H.U.V.E.C), an MTT experiment was then conducted. Real-time PCR was used to quantify TGF beta2 expression levels, whereas an ELISA immunosorbent assay was used to determine the protein concentration of TGF beta2.

RESULTS

In this study, the exosomes of 15-30 nm in size that were uniform, and cup-shaped were isolated. Moreover, the IC50 value for this Treatment was calculated to be 181.750 µg/ml. The concentration of TGF-β2 gene in the target cells significantly increased following Treatment with the exosomes. Furthermore, the expression level of the studied gene significantly increased due to the Treatment.

CONCLUSION

Upregulating the expression of TGF-β2 in psoriatic cells via TGF-β2 signaling is one way exosomes can help reduce hyperplasia.

The link between autophagy and psoriasis

Autophagy is a lysosome-dependent, self-renewal mechanism that degrades and recycles cellular components in eukaryotic cells to maintain the homeostasis of the intracellular environment. Psoriasis is featured by increased inflammatory response, epidermal hyperproliferation and abnormal differentiation, infiltration of immune cells and increased expression levels of both endothelial adhesion molecules and angiogenic mediators. Evidence indicates that autophagy has important roles in many different types of cells, such as lymphocytes, keratinocytes, monocytes and mesenchymal stem cells (MSCs). This paper will review the role of autophagy in the pathogenesis of psoriasis and strategies for therapeutic modulation. Key Message Autophagy regulates the functions of cutaneous cells (MSCs, KCs, T cells and endothelial cells). Since reduced autophagy contributes in part to the pathogenesis of psoriasis, enhancement of autophagy can be an alternative approach to mitigate psoriasis.

Exploring the role of growth factors as potential regulators in psoriatic plaque formation

Psoriasis is a chronic inflammatory skin disease in which growth activity is more prominent than inflammatory activity at the centre of lesional skin (CE skin). This growth activity is partly influenced by growth factors (GFs) that play an important role in cell growth and inflammation during the plaque development. In this study, we identified potential GFs in CE skin and predicted their regulatory functions and biological activity in mediating transcripts in the plaques. Samples of uninvolved skin (UN skin) and CE skin were biopsied from patients with psoriasis vulgaris for RNA-sequencing analysis in order to identify differentially expressed genes (DEGs). Our finding revealed that epidermal growth factor (EGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF) and hepatocyte growth factor (HGF) signalling were enriched by CE/UN skin-derived DEGs. Additionally, several EGFR ligands, namely EGF, heparin-binding EGF like growth factor (HB-EGF), amphiregulin (AREG) and transforming growth factor (TGF)-α, as well as TGF-β1, TGF-β2, vascular endothelial growth factor-A, FGFs, PDGF-B and HGF, were predicted to be GF regulators. The regulatory pattern and biological activity of these GF regulators on mediating the CE/UN skin-derived DEGs was demonstrated. This study provides a novel hypothesis regarding the overall regulatory function of GFs, which appear to modulate the expression of the transcripts involved in inflammation and growth in the CE skin. In addition, some GFs may exert anti-inflammatory effects. Further investigations on the mechanisms underlying this regulation may contribute to a deeper understanding of psoriasis and the identification of potential therapeutic targets for patients with psoriasis.

The role and application of three IFN-related reactions in psoriasis

The pathophysiology of psoriasis is a highly complicated one. Due to the disease's specificity, it not only affects the patient's skin negatively but also manifests systemic pathological changes. These clinical symptoms seriously harm the patient's physical and mental health. IFN, a common immunomodulatory factor, has been increasingly demonstrated to have a significant role in the development of psoriatic skin disease. Psoriasis is connected with a variety of immunological responses. New targets for the therapy of autoimmune skin diseases may emerge from further research on the mechanics of the associated IFN upstream and downstream pathways. Different forms of IFNs do not behave in the same manner in psoriasis, and understanding how different types of IFNs are involved in psoriasis may provide a better notion for future research. This review focuses on the involvement of three types of IFNs in psoriasis and related therapeutic investigations, briefly describing the three IFNs' production and signaling, as well as the dual effects of IFNs on the skin. It is intended that it would serve as a model for future research.

Long noncoding RNA (taurine upregulated gene 1) and micro RNA-377: emerging players in the development of metabolic syndrome among psoriasis patients

Background

Psoriasis (PsO) is an immune-mediated dermatosis and systemic inflammatory condition that can affect the skin, joints, and other organs and tissues with a range of comorbidities. The activation of proinflammatory cytokines is the primary cause of the development of skin lesions in PsO. Patients with PsO have a higher risk of developing cardiovascular metabolic comorbidities; among these is the metabolic syndrome (MetS). Particularly, MetS is characterized by abdominal obesity, hypertension, hyperglycemia, and hyperlipidemia, has been linked to PsO. The connection between PsO and MetS is believed to be caused by PsO generating systemic inflammation, which then results in elevated inflammatory adipokines, endothelial dysfunction, and insulin resistance. Micro RNA-377 and long noncoding RNA taurine upregulated 1 (TUG1) are both involved in the control of a variety of inflammatory disorders in humans and can be employed as biomarkers for the diagnosis and prognosis of psoriasis. The aim of the present study is to establish a panel of biomarkers for the early diagnosis of MetS incidence in psoriasis and thereby, reducing its lethal consequences.

Results

In this study, 120 patients: 40 psoriatic patients, 40 psoriatic patients with metabolic syndrome, and 40 healthy subjects were conducted. Expressions of Long noncoding RNA Taurine Upregulated Gene-1 (TUG1), miRNA-377 and Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ) were assessed in tissue lesion by real-time PCR. ELISA technique was carried out for the detection of serum levels of plasminogen activator inhibitor-1 (PAI-1) and transforming growth factor β (TGFβ). Moreover, miRNA-377 expression was significantly elevated with the simultaneous down-regulation of both TUG-1 and PPAR-γ in PsO-MetS group when compared to those of PsO and control groups. Furthermore, PAI-1 and TGFβ levels were higher in PsO-MetS than PsO.

Conclusions

The dysregulated levels of TUG-1, miRNA-377, PPAR-γ, PAI-1, and TGFβ, biomarkers may provide information about their potential role in the emergence of MetS in psoriasis patients.

Genetics of Generalized Pustular Psoriasis: Current Understanding and Implications for Future Therapeutics

Psoriasis is a chronic inflammatory skin disease characterized by the appearance of clearly demarcated erythematous and scaly plaques. It can be divided into various types, including plaque, nail, guttate, inverse, and pustular psoriasis. Plaque psoriasis is the most commonly occurring type, though there is another rare but severe pustular autoinflammatory skin disease called generalized pustular psoriasis (GPP), which manifests with acute episodes of pustulation and systemic symptoms. Though the etiopathogenesis of psoriasis is not yet fully understood, a growing body of literature has demonstrated that both genetic and environmental factors play a role. The discovery of genetic mutations associated with GPP has shed light on our comprehension of the mechanisms of the disease, promoting the development of targeted therapies. This review will summarize genetic determinants as known and provide an update on the current and potential treatments for GPP. The pathogenesis and clinical presentation of the disease are also included for a comprehensive discussion.

IL-6 and TGF-β-Secreting Adoptively-Transferred Murine Mesenchymal Stromal Cells Accelerate Healing of Psoriasis-like Skin Inflammation and Upregulate IL-17A and TGF-β

Mesenchymal stromal cells (MSC) show promise as cellular therapeutics. Psoriasis is a chronic inflammatory disease affecting the skin and the joints. Injury, trauma, infection and medications can trigger psoriasis by disrupting epidermal keratinocyte proliferation and differentiation, which activates the innate immune system. Pro-inflammatory cytokine secretion drives a T helper 17 response and an imbalance of regulatory T cells. We hypothesized that MSC adoptive cellular therapy could immunomodulate and suppress the effector T cell hyperactivation that underlies the disease. We used the imiquimod-induced psoriasis-like skin inflammation model to study the therapeutic potential of bone marrow and adipose tissue-derived MSC in vivo. We compared the secretome and the in vivo therapeutic potential of MSC with and without cytokine pre-challenge ("licensing"). The infusion of both unlicensed and licensed MSC accelerated the healing of psoriatic lesions, and reduced epidermal thickness and CD3+ T cell infiltration while promoting the upregulation of IL-17A and TGF-β. Concomitantly, the expression of keratinocyte differentiation markers in the skin was decreased. However, unlicensed MSC promoted the resolution of skin inflammation more efficiently. We show that MSC adoptive therapy upregulates the transcription and secretion of pro-regenerative and immunomodulatory molecules in the psoriatic lesion. Accelerated healing is associated with the secretion of TGF-β and IL-6 in the skin and MSC drives the production of IL-17A and restrains T-cell-mediated pathology.

The Experimental Animal Models in Psoriasis Research: A Comprehensive Review

Psoriasis is an autoimmune, chronic, inflammatory skin condition mediated by T cells. It differs from other inflammatory conditions by causing significant alterations in epidermal cell proliferation and differentiation that are both complicated and prominent. The lack of an appropriate animal model has significantly hindered studies into the pathogenic mechanisms of psoriasis since animals other than humans typically do not exhibit the complex phenotypic features of human psoriasis. A variety of methods, including spontaneous mutations, drug-induced mutations, genetically engineered animals, xenotransplantation models, and immunological reconstitution approaches, have all been employed to study specific characteristics in the pathogenesis of psoriasis. Although some of these approaches have been used for more than 50 years and far more models have been introduced recently, they have surprisingly not yet undergone detailed validation. Despite their limitations, these models have shown a connection between keratinocyte hyperplasia, vascular hyperplasia, and a cell-mediated immune response in the skin. The xenotransplantation of diseased or unaffected human skin onto immune-compromised recipients has also significantly aided psoriasis research. This technique has been used in a variety of ways to investigate the function of T lymphocytes and other cells, including preclinical therapeutic studies. The design of pertinent in vivo and in vitro psoriasis models is currently of utmost concern and a crucial step toward its cure. This article outlines the general approach in the development of psoriasis-related animal models, aspects of some specific models, along with their strengths and limitations.

Loss of Function TGFBR2 Variant as a Contributing Factor in Generalized Pustular Psoriasis and Adult-Onset Immunodeficiency

BACKGROUND

Generalized pustular psoriasis (GPP; MIM 614204) is a rare multisystemic autoinflammatory disease, characterized by episodes of acute generalized erythema and scaling developed with the spread of numerous sterile pustules. Adult-onset immunodeficiency syndrome (AOID) with anti-interferon-γ autoantibodies is an immunodeficiency disorder associated with disruptive IFN-γ signaling.

METHODS

Clinical examination and whole exome sequencing (WES) were performed on 32 patients with pustular psoriasis phenotypes and 21 patients with AOID with pustular skin reaction. Histopathological and immunohistochemical studies were performed.

RESULTS

WES identified four Thai patients presenting with similar pustular phenotypes-two with a diagnosis of GPP and the other two with AOID-who were found to carry the same rare TGFBR2 frameshift mutation c.458del; p.Lys153SerfsTer35, which is predicted to result in a marked loss of functional TGFBR2 protein. The immunohistochemical studied showed overexpression of IL1B, IL6, IL17, IL23, IFNG, and KRT17, a hallmark of psoriatic skin lesions. Abnormal TGFB1 expression was observed in the pustular skin lesion of an AOID patient, suggesting disruption to TGFβ signaling is associated with the hyperproliferation of the psoriatic epidermis.

CONCLUSIONS

This study implicates disruptive TGFBR2-mediated signaling, via a shared truncating variant, c.458del; p.Lys153SerfsTer35, as a "predisposing risk factor" for GPP and AOID.

BMPR1a Is Required for the Optimal TGFβ1-Dependent CD207+ Langerhans Cell Differentiation and Limits Skin Inflammation through CD11c+ Cells

The cytokine TGFβ1 induces epidermal Langerhans cell (LC) differentiation from human precursors, an effect mediated through BMPR1a/ALK3 signaling, as revealed from ectopic expression and receptor inhibition studies. Whether TGFβ1‒BMPR1a signaling is required for LC differentiation in vivo remained incompletely understood. We found that TGFβ1-deficient mice show defective perinatal expansion and differentiation of LCs. LCs can be identified within the normal healthy human epidermis by anti-BMPR1a immunohistology staining. Deletion of BMPR1a in all (vav+) hematopoietic cells revealed that BMPR1a is required for the efficient TGFβ1-dependent generation of CD207+ LC-like cells from CD11c+ intermediates in vitro. Similarly, BMPR1a was required for the optimal induction of CD207 by preformed major histocompatibility complex II‒positive epidermal resident LC precursors in the steady state. BMPR1a expression is strongly upregulated in epidermal cells in psoriatic lesions, and BMPR1aΔCD11c mice showed a defect in the resolution phase of allergic and psoriatic skin inflammation. Moreover, whereas LCs from these mice expressed CD207, BMPR1a counteracted LC activation and migration from skin explant cultures. Therefore, TGFβ1‒BMPR1a signaling seems to be required for the efficient induction of CD207 during LC differentiation in the steady state, and bone marrow‒derived lesional CD11c+ cells may limit established skin inflammation through enhanced BMPR1a signaling.

Normal mesenchymal stem cells can improve the abnormal function of T cells in psoriasis via upregulating transforming growth factor-β receptor

Psoriasis, a chronic inflammatory skin disease, is a refractory disorder. Previous studies have shown that the imbalance of the T-helper (Th)17/regulatory T cells (Treg) results in the immune imbalance of T cells in psoriatic patients, and that mesenchymal stem cells display an immunosuppressive role by promoting the differentiation of T cells into Treg, leading to a reduction in the proportion of Th17/Treg. Utility of mesenchymal stem cells is becoming a new approach for the treatment of immune disorders. Following co-culture of dermal mesenchymal stromal cells (DMSC) and CD3⁺ T cells with or without transforming growth factor (TGF)-β receptor inhibitor, the biological function and relative signal pathway of CD3⁺ T cells were assessed by flow cytometry, transwell, real-time polymerase chain reaction and western blotting, respectively. Normal DMSC were more potent than psoriatic DMSC in inhibition of CD3⁺ T-cell proliferation, and stimulation of CD3⁺ T-cell apoptosis than psoriasis DMSC. Moreover, normal DMSC decreased the ratio of Th17/Treg, while enhancing the immunosuppressive effect of Tregs on effector T cells. However, TGF-β receptor (TGF-βR) inhibitor attenuated the effect of normal DMSC on CD3⁺ T cells and Th17/Treg ratio. Additionally, the normal DMSC were more potent than the psoriatic DMSC in increasing TGF-β receptors and activation of TGF-β/SMAD pathway in psoriatic CD3⁺ T cells. In conclusion, normal DMSC can partially improve the biological function and immunosuppressive ability of psoriatic CD3⁺ T cells, possibly via upregulating the TGF-β receptors.

MicroRNA-378a-3p is overexpressed in psoriasis and modulates cell cycle arrest in keratinocytes via targeting BMP2 gene

Psoriasis is a chronic autoimmune skin disease driven by dysregulations at the cellular, genomic and genetic levels. MicroRNAs are key mediators of gene expression regulation. However, how microRNAs control the pathogenesis of psoriasis is still unclear. Here, we reported a significant up-regulation of miR-378a-3p (miR-378a) in skin biopsies from active psoriatic lesions while it was down-regulated after treatment with methotrexate or narrow-band ultraviolet B phototherapy. Using the keratinocyte in vitro model, we showed that miR-378a disturbed the cell cycle progression, causing cell cycle arrest at G1 phase. Transcriptomic analysis of keratinocytes with miR-378a overexpression and depletion revealed several important biological mechanisms related to inflammation and tight junction. Target mRNA transcript assessed by luciferase assay identified bone morphogenetic protein 2 as a novel target gene of miR-378a. These findings offer a mechanistic model where miR-378a contributes to the pathogenesis of psoriasis.

Bone morphogenetic protein signaling regulates skin inflammation via modulating dendritic cell function

BACKGROUND

Bone morphogenetic proteins (BMPs) are members of the TGF-β family that signal via the BMP receptor (BMPR) signaling cascade, distinct from canonical TGF-β signaling. BMP downstream signaling is strongly induced within epidermal keratinocytes in cutaneous psoriatic lesions, and BMP7 instructs monocytic cells to acquire characteristics of psoriasis-associated Langerhans dendritic cells (DCs). Regulatory T (Treg)-cell numbers strongly increase during psoriatic skin inflammation and were recently shown to limit psoriatic skin inflammation. However, the factors mediating Treg-cell accumulation in psoriatic skin currently remain unknown.

OBJECTIVE

We sought to investigate the role of BMP signaling in Treg-cell accumulation in psoriasis.

METHODS

The following methods were used: immunohistology of patients and healthy controls; ex vivo models of Treg-cell generation in the presence or absence of Langerhans cells; analysis of BMP versus canonical TGF-β signaling in DCs and Treg cells; and modeling of psoriatic skin inflammation in mice lacking the BMPR type 1a in CD11c+ cells.

RESULTS

We here demonstrated a positive correlation between Treg-cell numbers and epidermal BMP7 expression in cutaneous psoriatic lesions and show that unlike Treg cells from healthy skin, a portion of inflammation-associated Treg cells exhibit constitutive-active BMP signaling. We further found that BMPR signaling licenses inflammation-associated Langerhans cell/DC to gain an enhanced capacity to promote Treg cells via BMPR-mediated CD25 induction and that this effect is associated with reduced skin inflammation.

CONCLUSIONS

Psoriatic lesions are marked by constitutive high BMP7/BMPR signaling in keratinocytes, which instructs inflammatory DCs to gain enhanced Treg-cell-stimulatory activity. Locally secreted BMP7 can directly promote Treg-cell generation through the BMP signaling cascade.

TGF-β1 Gene Polymorphism and Its Correlation with Serum Level of TGF-β1 in Psoriasis Vulgaris Among Iraqi People

PURPOSE

Many cytokines have been implicated in the pathogenesis of psoriasis, among these the transforming growth factor-beta 1 (TGF-β1) can be endorsed by different mechanisms besides inhibiting keratinocytes proliferation. The role of genetic polymorphisms of TGF-β1 has been studied in various inflammatory diseases. Our aim is to study the correlation of TGF-β1 gene polymorphism at codon 10 and 25 with the expression of serum level of TGF-β1 in a sample of Iraqi psoriatic patients compared to the control group.

MATERIALS AND METHODS

A cross-sectional study involved 100 patients with psoriasis vulgaris and 50 sex- and age-matched healthy volunteers as control group. Serum and genomic DNA were prepared from peripheral blood samples. Amplification refractory mutation system-polymerase chain reaction technique (ARMS-PCR) had been applied for genotyping TGF-β1 codon 10 [rs1982073] and codon 25 [rs1800471] genetic polymorphisms. Enzyme-linked immunosorbent assay technique (ELISA) based on the sandwich principle was used for quantification of serum TGF-β1 level. Psoriasis Area and Severity Index (PASI) scoring was applied for determining the severity in psoriatic patients and classified accordingly to mild (PASI<7), moderate (PASI 7-12), severe (PASI>12) groups.

RESULTS

Statistically significant difference was found in TGF-β1 gene polymorphism between psoriatic patients and control group at codon 10 (T869C) polymorphism (p=0.021) and codon 25 (G915C) polymorphism (p=0.040). No significant association was detected with the mean serum TGF-β1 level, severity of the disease, disease onset, gender, history of psoriatic arthritis, and smoking in both codons. Significant lower mean serum TGF-β1 level was found among psoriatic group (192.17 ± 531.12 ng/L) compared with controls (565.89 ± 1372.30 ng/L) (p = 0.018). Relation of mean serum TGF-β1 level with the onset of the disease was statistically significant (p = 0.004), early-onset disease group was lower (105.92 ± 68.02 ng/L) compared with the late-onset disease group (450.92 ±1027.79 ng/L). The mean serum TGF-β1 level showed no significant differences with the severity of psoriasis, gender, history of psoriatic arthritis, and smoking.

CONCLUSION

Iraqi population showed a significant association between TGF-β1 gene polymorphism at codon 10 and 25 were with psoriasis susceptibility, and a significantly lower mean serum TGF-β1 level was detected in psoriatic patients.

Therapeutic Effects of Anti-Bone Morphogenetic Protein and Activin Membrane-Bound Inhibitor Treatment in Psoriasis and Arthritis

OBJECTIVE

The transforming growth factor β (TGFβ) inhibitor BAMBI (bone morphogenetic protein and activin membrane-bound inhibitor) has been shown to control differentiation of CD4+ T lymphocytes into either tolerogenic Treg cells or pathogenic Th17 cells, through the regulation of TGFβ and interleukin-2 (IL-2) signaling strength. The present study was undertaken to explore the potential beneficial effects of this strategy of pharmacologic inhibition using novel anti-BAMBI monoclonal antibodies (mAb) in different experimental murine models of chronic skin and joint inflammatory/autoimmune disease.

METHODS

Development of Saccharomyces cerevisiae mannan-induced psoriatic arthritis (MIP) (n = 18-30 mice per group), imiquimod-induced skin psoriasis (n = 20-30 mice per group), or type II collagen-induced arthritis (CIA) (n = 13-16 mice per group) was analyzed in a total of 2-5 different experiments with either wild-type (WT) or BAMBI-deficient B10.RIII mice that were left untreated or treated with mAb B101.37 (mouse IgG1 anti-BAMBI), a mouse IgG1 anti-TNP isotype control, anti-CD25, or anti-TGFβ mAb.

RESULTS

Treatment of normal mice with IgG1 anti-BAMBI mAb clone B101.37 led to expansion of Treg cells in vivo, and had both preventive and therapeutic effects in mice with MIP (each P < 0.05 versus controls). The conferred protection against disease progression was found to be mediated by Treg cells, which controlled the activation and expansion of pathogenic IL-17-producing cells, and was dependent on the level of TGFβ activity. Furthermore, treatment with B101.37 mAb blocked both the development of skin psoriasis induced by imiquimod and the development of CIA in mice (each P < 0.05 versus controls). Finally, pharmacologic inhibition of BAMBI with the IgM anti-BAMBI mAb B143.14 also potentiated the suppressive activity of Treg cells in vitro (P < 0.001 versus controls).

CONCLUSION

These results in murine models identify BAMBI as a promising new therapeutic target for chronic inflammatory diseases and other pathologic conditions modulated by Treg cells.

Cytokines in psoriasis

Psoriasis is chronic, immune-mediated, inflammatory disease with a multifactorial etiology that affects the skin tissue and causes the appearance of dry and scaly lesions of anywhere on the body. The study of the pathophysiology of psoriasis reveals a network of immune cells that, together with their cytokines, initiates a chronic inflammatory response. Previously attributed to T helper (Th)1 cytokines, currently the Th17 cytokine family is the major effector in the pathogenesis of psoriatic disease and strongly influences the inflammatory pattern established during the disease activity. In addition, the vast network of cells that orchestrates the pathophysiology makes psoriasis complex to study. Along with this, variations in genes that code the cytokines make psoriasis more clinically heterogeneous and present a challenge for the development of drugs that can be used in the treatment of the patients with this disease. Therefore, it is important to clarify the mechanisms by which the cytokines are involved in the pathophysiology of psoriasis and how this knowledge is translated to the medical practice.

Smad7 in psoriasis vulgaris patients: A clinical and immunohistochemical study

BACKGROUND

Psoriasis is an inflammatory disease that is mostly immune-derived. It causes proliferation of skin cells, forming plaques. Psoriasis etiology is unknown. It might be multifactorial.

AIMS

This work aimed to study Smad7 expression in psoriasis vulgaris patients in comparison with normal skin.

PATIENTS/METHODS

Thirty patients with psoriasis vulgaris in comparison with 20 age- and sex-matched seemingly healthy individuals were selected. We used psoriasis area and severity index (PASI) to evaluate psoriasis severity. Skin biopsies were prepared from skin lesions (30), perilesions (30) and control (20) groups for histopathological and immunostaining evaluation of Smad7.

RESULTS

Smad7 was progressively upregulated in proliferating keratinocytes from controls (58.18 ± 30.93) to perilesional (106 ± 38.93) and lesional (156.33 ± 62.01) skin (P < .001). Also, dermal inflammatory cells showed upregulation of Smad7 expression from control skin (40 ± 28.28) to skin lesions (137.33 ± 73.86) (P < .010). Smad7 expression showed a positive significant correlation with psoriasis severity (r = .452; P < .012).

CONCLUSION

Smad7 may be involved in increased keratinocyte proliferation as well as skin inflammation in psoriasis vulgaris patients.

BMP7 aberrantly induced in the psoriatic epidermis instructs inflammation-associated Langerhans cells

BACKGROUND

Epidermal hyperplasia represents a morphologic hallmark of psoriatic skin lesions. Langerhans cells (LCs) in the psoriatic epidermis engage with keratinocytes (KCs) in tight physical interactions; moreover, they induce T-cell-mediated immune responses critical to psoriasis.

OBJECTIVE

This study sought to improve the understanding of epidermal factors in psoriasis pathogenesis.

METHODS

BMP7-LCs versus TGF-β1-LCs were phenotypically characterized and their functional properties were analyzed using flow cytometry, cell kinetic studies, co-culture with CD4 T cells, and cytokine measurements. Furthermore, immunohistology of healthy and psoriatic skin was performed. Additionally, in vivo experiments with Jun^f/fJunB^f/fK5cre-ER^T mice were carried out to assess the role of bone morphogenetic protein (BMP) signaling in psoriatic skin inflammation.

RESULTS

This study identified a KC-derived signal (ie, BMP signaling) to promote epidermal changes in psoriasis. Whereas BMP7 is strictly confined to the basal KC layer in the healthy skin, it is expressed at high levels throughout the lesional psoriatic epidermis. BMP7 instructs precursor cells to differentiate into LCs that phenotypically resemble psoriatic LCs. These BMP7-LCs exhibit proliferative activity and increased sensitivity to bacterial stimulation. Moreover, aberrant high BMP signaling in the lesional epidermis is mediated by a KC intrinsic mechanism, as suggested from murine data and clinical outcome after topical antipsoriatic treatment in human patients.

CONCLUSIONS

These data indicate that available TGF-β family members within the lesional psoriatic epidermis preferentially signal through the canonical BMP signaling cascade to instruct inflammatory-type LCs and to promote psoriatic epidermal changes. Targeting BMP signaling might allow to therapeutically interfere with cutaneous psoriatic manifestations.

Hypotonic, Acidic Oxidizing Solution Containing Hypochlorous Acid (HClO) as a Potential Treatment of Hailey-Hailey Disease

Hailey–Hailey disease (HHD) is a rare, chronic and recurrent blistering disorder, characterized by erosions occurring primarily in intertriginous regions and histologically by suprabasal acantholysis. Mutation of the Golgi Ca²⁺-ATPase ATP2C1 has been identified as having a causative role in Hailey–Hailey disease. HHD-derived keratinocytes have increased oxidative-stress that is associated with impaired proliferation and differentiation. Additionally, HHD is characterized by skin lesions that do not heal and by recurrent skin infections, indicating that HHD keratinocytes might not respond well to challenges such as wounding or infection. Hypochlorous acid has been demonstrated in vitro and in vivo to possess properties that rescue both oxidative stress and altered wound repair process. Thus, we investigated the potential effects of a stabilized form of hypochlorous acid (APR-TD012) in an in vitro model of HHD. We found that treatment of ATP2C1-defective keratinocytes with APR-TD012 contributed to upregulation of Nrf2 (nuclear factor (erythroid-derived 2)-like 2). Additionally, APR TD012-treatment restored the defective proliferative capability of siATP2C1-treated keratinocytes. We also found that the APR-TD012 treatment might support wound healing process, due to its ability to modulate the expression of wound healing associated cytokines. These observations suggested that the APR-TD012 might be a potential therapeutic agent for HHD-lesions.

Proinflammatory and anti-inflammatory cytokine profiles in psoriasis: use as laboratory biomarkers and disease predictors

OBJECTIVE

The objectives of this study were to delineate the pro and anti-inflammatory cytokine profiles of psoriasis and cytokine profile models that externally validate the diagnosis.

SUBJECTS AND METHODS

This study recruited 70 patients with psoriasis and 76 healthy controls. Cytokine profiles were evaluated, including pro-inflammatory M1 (IL-1 + IL-6 + TNF-α), Th1 (IL-2 + IL-12 + IFN-γ), Th17 (IL-6 + IL-17), and immune-inflammatory response system (IRS = M1 + Th1 + Th17) profiles. Moreover, the anti-inflammatory potential included Th2 (IL-4), Th2 + T regulatory (Th2 + Treg, namely IL-4 + IL-10 + TGF-β), anti-inflammatory (Th2 + Treg + adiponectin), and the pro-inflammatory/anti-inflammatory index.

RESULTS

There was a highly significant association between psoriasis and cytokine levels with an effect size of 0.829 and a particularly strong impact on IL-2 (0.463), IL-12 (0.451), IL-10 (0.532) and adiponectin (0.401). TGF-β and adiponectin were significantly lower while all other cytokines (except IFN-γ) were significantly higher in psoriasis than in controls. In addition, M1, Th1, Th17, Th2 + Treg, and IRS/Anti-inflammatory index were significantly higher in psoriasis patients than in controls. The IRS index, Th2 + Treg, and adiponectin predicted psoriasis with 97.1% sensitivity and 94% specificity.

CONCLUSION

In conclusion, psoriasis is characterized by increased M1, Th1, Th2 and Th17 profiles together with lowered TGF-β and adiponectin. In addition, we propose a model based on a higher IRS and Th2 + Treg index coupled with lower adiponectin values, which may be used to externally validate the diagnosis of psoriasis. The most important single biomarker of psoriasis is adiponectin. Because the latter may play a role in the modulation of the chronic inflammatory response in psoriasis, adiponectin could be a new drug target to treat psoriasis.

Coacervate-mediated exogenous growth factor delivery for scarless skin regeneration

Although there are numerous medical applications to recover damaged skin tissue, scarless wound healing is being extensively investigated to provide a better therapeutic outcome. The exogenous delivery of therapeutic growth factors (GFs) is one of the engineering strategies for skin regeneration. This study presents an exogenous GF delivery platform developed using coacervates (Coa), a tertiary complex of poly(ethylene argininyl aspartate diglyceride) (PEAD) polycation, heparin, and cargo GFs (i.e., transforming growth factor beta 3 (TGF-β3) and interleukin 10 (IL-10)). Coa encompasses the advantage of high biocompatibility, facile preparation, protection of cargo GFs, and sustained GF release. We therefore speculated that coacervate-mediated dual delivery of TGF-β3/IL-10 would exhibit synergistic effects for the reduction of scar formation during physiological wound healing. Our results indicate that the exogenous administration of dual GF via Coa enhances the proliferation and migration of skin-related cells. Gene expression profiles using RT-PCR revealed up-regulation of ECM formation at early stage of wound healing and down-regulation of scar-related genes at later stages. Furthermore, direct injection of the dual GF Coa into the edges of damaged skin in a rat skin wound defect model demonstrated accelerated wound closure and skin regeneration after 3 weeks. Histological evaluation and immunohistochemical staining also revealed enhanced formation of the epidermal layer along with facilitated angiogenesis following dual GF Coa delivery. Based on these results, we conclude that polycation-mediated Coa fabrication and exogenous dual GF delivery via the Coa platform effectively augments both the quantity and quality of regenerated skin tissues without scar formation. STATEMENT OF SIGNIFICANCE: This study was conducted to develop a simple administration platform for scarless skin regeneration using polycation-based coacervates with dual GFs. Both in vitro and in vivo studies were performed to confirm the therapeutic efficacy of this platform toward scarless wound healing. Our results demonstrate that the platform developed by us enhances the proliferation and migration of skin-related cells. Sequential modulation in various gene expression profiles suggests a balanced collagen-remodeling process by dual GFs. Furthermore, in vivo histological evaluation demonstrates that our technique enhances clear epidermis formation with less scab and thicker woven structure of collagen bundle, similar to that of a normal tissue. We propose that simple administration of dual GFs with Coa has the potential to be applied as a clinical approach for fundamental scarless skin regeneration.

The loss of ATP2C1 impairs the DNA damage response and induces altered skin homeostasis: Consequences for epidermal biology in Hailey-Hailey disease

Mutation of the Golgi Ca(2+)-ATPase ATP2C1 is associated with deregulated calcium homeostasis and altered skin function. ATP2C1 mutations have been identified as having a causative role in Hailey-Hailey disease, an autosomal-dominant skin disorder. Here, we identified ATP2C1 as a crucial regulator of epidermal homeostasis through the regulation of oxidative stress. Upon ATP2C1 inactivation, oxidative stress and Notch1 activation were increased in cultured human keratinocytes. Using RNA-seq experiments, we found that the DNA damage response (DDR) was consistently down-regulated in keratinocytes derived from the lesions of patients with Hailey-Hailey disease. Although oxidative stress activates the DDR, ATP2C1 inactivation down-regulates DDR gene expression. We showed that the DDR response was a major target of oxidative stress-induced Notch1 activation. Here, we show that this activation is functionally important because early Notch1 activation in keratinocytes induces keratinocyte differentiation and represses the DDR. These results indicate that an ATP2C1/NOTCH1 axis might be critical for keratinocyte function and cutaneous homeostasis, suggesting a plausible model for the pathological features of Hailey-Hailey disease.

Association of down-regulation of CD109 expression with up-expression of Smad7 in pathogenesis of psoriasis

Transforming growth factor (TGF)-β signaling plays an important role in the pathogenesis of psoriasis. CD109, a novel TGF-β co-receptor, which inhibits TGF-β signaling by enhancing Smad7-dependent degradation of TGF-β type I receptor (TGF-β RI), is abnormally expressed in psoriasis. To date, the expression of Smad7 and the correlation between CD109 and Smad7 expression in psoriasis have not been fully elucidated. This study was designed to investigate the expression and the correlation of CD109 and TGF-β signaling associated proteins in psoriasis and their roles in the pathogenesis of psoriasis. Thirty-two psoriasis specimens were subjected to immunohistochemical staining for CD109, Smad7, TGF-β RI and Ki67. Ten normal skin (NS) specimens served as controls. The positive expression rate (% positive cells) of Smad7 and Ki67 in psoriasis was significantly higher than in NS (62.6%±19.9% vs. 17.2%±4.4%, and 50.7%±14.3% vs. 19.5%±3.2%, respectively, P<0.001), and the expression levels of CD109 and TGF-β RI were reduced significantly in psoriasis as compared with NS (8.1%±6.7% vs. 35.8%±6.7% and 27.3%±3.4% vs. 3.0%±3.4%, respectively, P<0.001). There were significantly negative correlations between CD109 and Smad7 (r=-0.831, P<0.01). These findings indicated that CD109 might play a certain role in the pathogenesis of psoriasis. Lower expression of CD109 and TGF-β RI was highly correlated with higher expression of Smad7 and Ki67, suggesting that CD109 may induce the pathogenesis of psoriasis through Smad7-mediated degradation of TGF-β RI, and lead to the termination of TGF-β signaling.

Master regulators of infiltrate recruitment in autoimmune disease identified through network-based molecular deconvolution

Network-based molecular modeling of physiological behaviors has proven invaluable in the study of complex diseases such as cancer, but these approaches remain largely untested in contexts involving interacting tissues such as autoimmunity. Here, using Alopecia Areata (AA) as a model, we have adapted regulatory network analysis to specifically isolate physiological behaviors in the skin that contribute to the recruitment of immune cells in autoimmune disease. We use context-specific regulatory networks to deconvolve and identify skin-specific regulatory modules with IKZF1 and DLX4 as master regulators (MRs). These MRs are sufficient to induce AA-like molecular states in vitro in three cultured cell lines, resulting in induced NKG2D-dependent cytotoxicity. This work demonstrates the feasibility of a network-based approach for compartmentalizing and targeting molecular behaviors contributing to interactions between tissues in autoimmune disease.

Diagnostic utility of Ki-67 and Cyclin D1 immunostaining in differentiation of psoriasis vs. other psoriasiform dermatitis

Background:

Differentiation of psoriasis from non-psoriasis psoriasiform dermatitis (NPPD) may be difficult for dermatopathologists, as lack of distinctive histopathological features in a subset of cases may cause confusion in diagnosis.

Objective:

As the prototype of psoriasiform dermatitis, psoriasis is a hyperproliferative skin disorder with increased epidermal turnover compared with NPPD, we investigated the role of proliferation markers, Ki-67 and Cyclin D1 as diagnostic tools to differentiate psoriasis from other psoriasiform dermatitis.

Methods:

Histopathological specimens of psoriasis (n = 35) and NPPD (n = 36, 14 pityriasis rubra pilaris, 12 pityriasis rosea and 10 lichen simplex) cases were reviewed and immunohistochemically stained for Ki-67 and Cyclin D1. Ki-67 and Cyclin D1 positive cells were counted for suprabasal, and total epidermal immunostaining per mm².

Results:

Suprabasal and total epidermal cell counts for Ki-67 were found to be significantly higher in the psoriasis group compared with the NPPD group (p < 0.05). An important and interesting feature was the presence of a cut-off value for the suprabasal/total epidermal cell count ratio of 75% for Ki-67 immunostaining, which was higher in all patients having psoriasis (range, 77.1% – 92.4%) and lower in all NPPD cases (range, 21.0% – 73.3%). However, suprabasal Cyclin D1 cell counts were higher in the psoriasis group compared with the NPPD group (p < 0.05), total epidermal Cyclin D1 cell counts were not statistically significant in either group (p = 0.167), and a cut-off value for suprabasal/total epidermal cell count ratio to distinguish these two entities was not detected using this immunostain.

Conclusions:

We suggest that Ki-67 is a more sensitive marker than Cyclin D1 in terms of having a cutoff value of 75% for the suprabasal/total epidermal immunoreactive cell count ratio, which we believe could be useful for dermatopathologists in differentiating psoriasis from other psoriasiform dermatitis.

Expression of USP15, TβR-I and Smad7 in psoriasis

The deubiquitinating enzyme ubiquitin specific peptidase 15 (USP15) is regarded as a regulator of TGFβ signaling pathway. This process depends on Smad7, the inhibitory factor of the TGFβ signal, and type I TGFβ receptor (TβR-I), one of the receptors of TGFβ. The expression level of USP15 seems to play vital roles in the pathogenesis of many neoplasms, but so far there has been no report about USP15 in psoriasis. In this study, immunohistochemical staining of USP15, TβR-I and Smad7 was performed in 30 paraffin-embedded psoriasis specimens and 10 normal specimens to investigate the expression of USP15, TβR-I and Smad7 in psoriasis and to explore the relevance among them. And USP15 small interfering RNA (USP15 siRNA) was used to transfect Hacat cells to detect the mRNA expression of TβR-I and Smad7. Of 30 cases of psoriasis in active stage, 28, 24 and 26 cases were positive for USP15, TβR-I and Smad7 staining, respectively. The positive rates of USP15 and Smad7 were significantly higher in psoriasis specimens than in normal skin specimens (44.1%±26.0% vs. 6.1%±6.6%, 47.2%±27.1% vs. 6.6%±7.1%), and positive rate of TβR-I (20.3%±22.2%) in psoriasis was lower than that in normal skin specimens (46.7%±18.2%). There was a significant positive correlation between USP15 and Smad7 expression, and significant negative correlations between USP15 and TβR-expression, an I d between TβR- and Smad7 expression I in psoriasis. After transfection of USP15 siRNA in Hacat cells, the expression of TβR-mRNA was up I -regulated and that of Smad7 was down-regulated. It is concluded that USP15 may play a role in the pathogenesis of psoriasis through regulating the TβR-I/Smad7 pathway and there may be other cell signaling pathways interacting with USP15 to take part in the development of psoriasis.

TGFβ (transforming growth factor β) and keratocyte motility in 24 h zebrafish explant cultures

Fish keratocytes are used as a model system for the study of the mechanics of cell motility because of their characteristic rapid, smooth gliding motion, but little work has been done on the regulation of fish keratocyte movement. As TGFβ (transforming growth factor β) plays multiple roles in primary human keratinocyte cell migration, we investigated the possible involvement of TGFβ in fish keratocyte migration. Studying the involvement of TGFβ1 in 24 h keratocyte explant allows the examination of the cells before alterations in cellular physiology occur due to extended culture times. During this initial period, TGFβ levels increase 6.2-fold in SFM (serum-free medium) and 2.4-fold in SFM+2% FBS (fetal bovine serum), while TGFβ1 and TGFβRII (TGFβ receptor II) mRNA levels increase ∼3- and ∼5-fold respectively in each culture condition. Two measures of motility, cell sheet area and migration distance, vary with the amount of exogenous TGFβ1 and culture media. The addition of 100 ng/ml exogenous TGFβ1 in SFM increases both measures [3.3-fold (P = 4.5×10-5) and 26% (P = 2.1×10-2) respectively]. In contrast, 100 ng/ml of exogenous TGFβ1 in medium containing 2% FBS decreases migration distance by 2.1-fold (P = 1.7×10-7), but does not affect sheet area. TGFβ1 (10 ng/ml) has little effect on cell sheet area in SFM cultures, but leads to a 1.8-fold increase (P = 1.5×10-2) with 2% FBS. The variable response to TGFβ1 may be, at least in part, explained by the effect of 2% FBS on cell morphology, mode of motility and expression of endogenous TGFβ1 and TGFβRII. Together, these results suggest that expression of TGFβ and its receptor are up-regulated during zebrafish keratocyte explant culture and that TGFβ promotes fish keratocyte migration.

Psoriasis: what we have learned from mouse models

Psoriasis is a common inflammatory skin disease of unknown etiology, for which there is no cure. This heterogeneous, cutaneous, inflammatory disorder is clinically characterized by prominent epidermal hyperplasia and a distinct inflammatory infiltrate. Crosstalk between immunocytes and keratinocytes, which results in the production of cytokines, chemokines and growth factors, is thought to mediate the disease. Given that psoriasis is only observed in humans, numerous genetic approaches to model the disease in mice have been undertaken. In this Review, we describe and critically assess the mouse models and transplantation experiments that have contributed to the discovery of novel disease-relevant pathways in psoriasis. Research performed using improved mouse models, combined with studies employing human cells, xenografts and patient material, will be key to our understanding of why such distinctive patterns of inflammation develop in patients with psoriasis. Indeed, a combination of genetic and immunological investigations will be necessary to develop both improved drugs for the treatment of psoriasis and novel curative strategies.

Inflammatory skin disease in K5.hTGF-beta1 transgenic mice is not dependent on the IL-23/Th17 inflammatory pathway

In the presence of IL-6, transforming growth factor (TGF)-beta1 induces differentiation of T helper (Th) 17 cells in mice. Interleukin (IL)-23, a heterodimeric cytokine composed of IL-23p19 and IL-12/23p40 subunits, stimulates the growth and expansion of Th17 cells, and has been implicated in psoriasis pathogenesis. To study the associations between TGF-beta1, the IL-23/Th17 inflammatory pathway, and psoriasis, we investigated inflammatory skin disease in transgenic mice that constitutively overexpress human TGF-beta1 in basal keratinocytes (K5.hTGF-beta1 transgenic mice); these mice had previously been reported as having a psoriasis-like disease. K5.hTGF-beta1 transgenic mice had high levels of TGF-beta1 mRNA and protein in both skin and serum. Levels of cytokines involved in IL-23/Th17-mediated inflammation were not elevated in lesional skin compared with those in non-lesional and wild-type skin. It is noteworthy that IL-4 and IgE were markedly elevated in inflamed skin and serum, respectively, of transgenic mice. Monoclonal antibodies (mAbs) specifically directed against IL-23p19 or IL-12/23p40 had no clinical effect on established inflammatory skin disease in K5.hTGF-beta1 transgenic mice, whereas the same mAbs were able to block the development of murine experimental autoimmune encephalomyelitis, an IL-23/Th17-mediated disease. In summary, the IL-23/Th17 inflammatory pathway is not responsible for the maintenance of inflammatory skin disease in K5.hTGF-beta1 transgenic mice.

A role for TGFbeta signaling in the pathogenesis of psoriasis

Deregulation of transforming growth factor-beta (TGFbeta) signaling has been reported in human psoriasis. Our recent study using a keratin 5 promoter (K5.TGFbeta1(wt)) showed that transgenic mice expressing wild-type TGFbeta1 in the epidermis developed severe skin inflammation. Additional experimental data further support a direct role for TGFbeta1 overexpression in skin inflammation. First, we temporally induced TGFbeta1 expression in keratinocytes in our gene-switch TGFbeta1(wt) transgenic mice and found inflammation severity correlated with TGFbeta1(wt) transgene expression. Second, deletion of T cells in K5.TGFbeta1(wt) mice significantly delayed skin inflammation and associated epidermal hyperplasia/hyperkeratosis. Third, therapeutic approaches effective for human psoriasis, that is, Etanercept and Rosiglitazone, are effective in alleviating the symptoms observed in K5.TGFbeta1(wt) mice. Future studies will analyze specific mechanisms and identify key factors in TGFbeta1-induced skin inflammation. Our mouse models will provide a useful tool for understanding the molecular mechanisms of inflammatory skin disorders in which TGFbeta1 is overexpressed.

Role of forkhead L2 in transforming growth factor-beta /Smad signaling pathway-mediated activation of hepatic stellate cells

Hepatic fibrosis is characterized by an abnormal hepatic deposition of extracellular matrix (especially collagen). As hepatic fibrosis progresses, cirrhosis will develop. Hepatic stellate cells are the major source of the extracellular matrix (ECM). The activation of hepatic stellate cells is the central event in the development of hepatic fibrosis. The transforming growth factor-beta (TGF-β)/Smad signaling pathway plays an important role in regulating the synthesis of ECM in stellate cells. Recent studies found that forkhead L2 (Fox L2), belonging to the forkhead family, was able to act as a molecular chaperone for Smad complex. Thus, it may enhance the stability between Smad complex and target genes.

Serum and tissue expression of transforming growth factor beta 1 in psoriasis

BACKGROUND

In psoriasis, keratinocyte hyperplasia may be explained by imbalance of growth factors responsible for epidermal proliferation and altered metabolism of their receptors. Transforming growth factor-beta 1 (TGF-beta1) implications in the pathogenesis of psoriasis can be attributed to several mechanisms besides keratinocyte cell cycle inhibition.

OBJECTIVES

To evaluate the relation between serum and tissue levels of TGF-beta1 in psoriasis and their correlation with disease parameters.

PATIENTS AND METHODS

Serum and punch biopsy of involved and non-involved skin of 22 patients with psoriasis vulgaris and 10 controls were collected for quantification of TGF-beta1 by enzyme-linked immunosorbent assay kit.

RESULTS

Serum level of TGF-beta1 in psoriatic patients was higher than controls in a statistically non-significant manner. Correlations between serum level of TGF-beta1 and extent of the disease (P = 0.007) and Psoriasis Area and Severity Index (PASI) score (P = 0.005) were observed. Mean tissue levels of TGF-beta1 were highest in psoriatic lesions in contrast to normal skin of psoriatic patients and healthy controls, but not statistically significant. Correlation between tissue levels of TGF-beta1 in non-involved skin and extent of the disease (P = 0.007) and PASI score (P = 0.013) was detected. Correlation was detected between levels of TGF-beta1 in psoriatic plaques and serum of patients (P = 0.035), but not between levels of TGF-beta1 in non-involved skin and serum.

CONCLUSIONS

Tissue expression of TGF-beta1 in psoriasis may be affected by the stage of development of the lesion. The direct relation between TGF-beta1 in psoriatic plaques and serum imply that the mechanisms for TGF-beta1 production and release in both these compartments may be related.

Hydrogen peroxide-induced cellular apoptosis is mediated by TGF-beta2 signaling pathway in cultured human lens epithelial cells

The objective of this study was to investigate the signaling characteristics of transforming growth factor-beta2 (TGF-beta2) and the Smads (Caenorhabditis elegans, Sma; Drosophila mothers against dpp, Mad) signal pathway of cellular apoptosis induced by hydrogen peroxide with human lens epithelial cells (HLECs). HLECs were starved for 24 h before exposure to 0.1 mumol/ml of hydrogen peroxide in the presence and in the absence of 0.01 mug/ml of AF-302-NA, a monoclonal anti-TGF-beta2 neutralization antibody. Non-stimulated cells served as controls. Cell apoptosis was examined by in situ immunocytochemistry using terminal deoxynucleotidyl transferase dUTP-mediated biotin nick end labeling (TUNEL) and by flow cytometry (FCM) using Annexin V-FITC apoptosis detection. Gene expression was assessed using the reverse transcription-polymerase chain reaction (RT-PCR). Smad-4 localization was observed by immunocytochemistry. Hydrogen peroxide induced the accumulation of Smad-4 in the nucleus of HLECs, and upregulated the expression of TGF-beta receptors (TbetaRs) mRNA in HLECs, as well as upregulated the expression of the apoptotic gene bax, which leads HLECs to apoptosis. AF-302-NA decreased cellular apoptosis induced by hydrogen peroxide in HLECs and inhibited the translocation of Smad-4 from the cytoplasm to the cell nucleus. Moreover, AF-302-NA upregulated the expression of TbetaRs mRNA and downregulated the expression of bax mRNA in HLECs incubated with hydrogen peroxide. Our study demonstrated that the TGF-beta2 signal pathway participated in the apoptotic signal transfer and might be an initiator of cellular apoptosis of HLECs after incubation with hydrogen peroxide. Interruption of the TGF-beta2 signal pathway could partially protect HLECs from apoptosis induced by incubation with hydrogen peroxide.

Mouse models of psoriasis

Psoriasis is a T-cell-mediated chronic inflammatory skin disease believed to be of autoimmune nature that can be triggered or worsened by streptococcal throat infections. In addition to conventional chronic inflammatory changes, psoriasis is characterized by complex and striking alterations in epidermal growth and differentiation. Psoriasis is generally not observed in animals other than man, and this lack of a suitable animal model has greatly hindered research into the pathogenesis of psoriasis. Multiple transgenic, knockout, and reconstituted models of psoriasis have been developed over the past two decades. Despite their limitations, these models have demonstrated that keratinocyte hyperplasia, vascular hyperplasia, and cell-mediated immunity in the skin are closely interrelated. Xenograft models, in which involved and uninvolved psoriatic skin are transplanted onto immunodeficient mice, are the only models that come close to incorporating the complete genetic, immunologic, and phenotypic changes of the disease. They have shown conclusively that psoriasis is a T-cell-mediated disease, and have been used to elucidate novel pathogenic pathways. In this review, we describe various animal models, detail the immunologic and intracellular pathways that mediate these phenotypes and assess the utility of these models to better understand this disease.

Lessons learned from psoriatic plaques concerning mechanisms of tissue repair, remodeling, and inflammation

Following injury, skin establishes a balance between too little inflammation increasing risk of infection, and excessive inflammation contributing to delayed wound healing and scarring. Mounting evidence indicates both initiation and termination of inflammation involve active mechanisms. Not only does inflammation itself seem to be a paradox because inflammatory responses are both essential and potentially detrimental, but one chronic inflammatory skin disease (e.g. psoriasis) presents additional paradoxes. While plaques share several factors with wound healing, two understudied and puzzling aspects include why do not inflamed plaques more frequently transform?; and why do not plaques result in scarring? To get at these questions, we review responses involved in wound repair. Oral mucosa was probed because, like fetal skin, wound repair is characterized by its rapidity, low inflammation, and scarless resolution. Active roles for macrophages as both initiators and terminators of inflammation are highlighted. Therapeutic implications are discussed regarding psoriasis and pyoderma gangrenosum. Based on biochemical and immunohistochemical considerations linking psoriatic plaques to hard palate, a novel metaplastic model is presented. We hypothesize saliva and chronic trauma contribute to a constitutive epithelial program where keratinocyte proliferation is more intense prior to differentiation, accompanied by keratin 16 expression in hard palate, thereby resembling plaques. Rather than viewing psoriasis as a nonspecific response to inflammation, we postulate a metaplastic switch by which prepsoriatic skin is converted to a distinct adult tissue type resembling hard palate. In summary, many lessons can be learned by focusing on complex processes involved in regulation of inflammation, tissue repair, and remodeling.

Emerging drugs for psoriasis

Psoriasis is a chronic immune-mediated inflammatory skin disease characterised by abnormal keratinocyte differentiation and proliferation. The immunopathogenesis is complex and novel evidence shows the involvement of both innate and adaptive immune response. Type 1 T cells and their effector cytokines play a pivotal role. Several drugs under preclinical and clinical development for psoriasis are directed against the immune response, targeting activation or proliferation of T cells, their trafficking and skin-homing, or effector cytokines. Among these, great attention has been given to TNF-alpha, following the demonstration of effectiveness of anti-TNF-alpha biologicals, and to IFN-gamma inducers. Another appealing approach concerns drugs capable of inducing immunological tolerance. Progress made in the recognition of intracellular events has prompted the development of small molecules and oligonucleotides that can inhibit specific molecular targets. There is, however, a plethora of other emerging drugs, clearly suggestive of the current interest for psoriasis, which are briefly described in this paper.

Altered keratin 17 peptide ligands inhibit in vitro proliferation of keratinocytes and T cells isolated from patients with psoriasis

BACKGROUND

Identification of critical autoantigenic T-cell epitopes is key to developing antigen-based therapies for autoimmune diseases, including psoriasis. Our previous work demonstrated that 3 peptides on keratin 17 are able to stimulate peripheral blood lymphocytes of HLA-DRB1*07-positive patients with psoriasis and to serve as immunodominant T-cell epitopes.

OBJECTIVE

We sought to determine antagonistic altered peptide ligands to psoriatic T cells with a down-modulatory effect in inhibiting keratinocyte proliferation.

METHODS

Psoriatic altered peptide ligands were generated by single alanine residue substitutions at a critical T-cell receptor contact residue position. Antagonistic altered peptide ligands were identified by suppression screening of psoriatic T-cell activation and keratinocyte proliferation.

RESULTS

Altered peptide ligands 119R and 355L can inhibit psoriatic T-cell activation more effectively than other altered peptide ligands, especially 355L, with inhibition of T-cell proliferation and the secretion of interferon gamma and interleukin 2 in parallel with the up-regulation of interleukins 4 and 10 as well as transforming growth factor-beta. In coincubation assay, altered peptide ligands 119R and 355L can down-regulate the function of psoriatic T cells more effectively than wild-type epitopes solely, but less effectively than altered peptide ligands solely. In prepulse assay altered peptide ligand 119R can down-regulate the activation of psoriatic T cells more effectively than in coincubation but less effectively as compared with altered peptide ligand 119R only. Altered peptide ligand 355L was also shown to have a similar presentation. T-cell culture supernatants (1:100) from the concentrations (10 microg.mL(-1) and 100 microg.mL(-1) with 119R, 100 microg.mL(-1) with 355L) were more effective than the other ratios in inhibiting keratinocyte proliferation.

LIMITATIONS

This study had a relatively small sample size (52 patients and 48 healthy controls).

CONCLUSION

Our findings show that the altered peptide ligands 119R (VAALEEANTELEVKI) and 355L (ENRYCVQASQIQGLI) are capable of inhibiting proliferative responses of psoriatic T cells and keratinocyte proliferation in vitro, at least, with enhanced helper T cell type 2 polarization. Thus, to our knowledge, this article is the first report of the demonstration of therapeutic activity of altered peptide ligands derived from keratin 17.

Evaluation of cell death and proliferation in psoriatic epidermis

BACKGROUND

Previous studies of psoriatic epidermis using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method, a type of apoptotic detection method, showed that TUNEL-positive keratinocytes were abundantly distributed in all layers of the psoriatic epidermis, although psoriasis is a hyperproliferative disorder.

OBJECTIVE

We sought to clarify the nature of cell kinetics in a psoriatic epidermis on the basis of differences in the reactivities in TUNEL and formamide-induced DNA denaturation assay combined with the detection of denatured DNA with a monoclonal antibody (MAb) against single-stranded DNA (formamide-MAb assay) between the normal and psoriatic epidermides.

METHODS

The kinetics of keratinocytes was evaluated by the immunohistochemistry of Ki-67 for proliferation activity and by TUNEL, TUNEL combined with transmission electron microscopy (TUNEL/TEM), and formamide-MAb assay for apoptosis.

RESULTS

The number of Ki-67-positive cells in the psoriatic epidermis was significantly higher than that in the normal epidermis. In the normal epidermis, both TUNEL and formamide-MAb assay showed a similar distribution pattern, that is, both TUNEL and formamide-MAb assay-positive keratinocytes were present only in the upper granular layer. In the psoriatic epidermis, most keratinocytes were negative for the formamide-MAb assay, while TUNEL-positive cells were abundantly distributed in all layers of the psoriatic epidermis. TUNEL/TEM method clearly demonstrated that many immunogold particles that stain the sites of 3'-OH DNA ends were evenly distributed on the euchromatin in psoriatic keratinocyte nuclei, in contrast to their presence on the peripheral condensed chromatin in normal keratinocyte nuclei.

CONCLUSION

The increased TUNEL reactivity in psoriatic lesions is due to the increase in the number of DNA nicks resulting from active DNA replication but not due to DNA double-strand breaks produced during the apoptotic process, and the formamide-MAb assay is a reliable method for the detection of apoptosis, particularly in the epidermis.