Cutting edge: A critical functional role for IL-23 in psoriasis

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.

Etiopathogenesis of Psoriasis: Integration of Proposed Theories

Psoriasis is a chronic inflammatory disease characterized by squamous and erythematous plaques on the skin and the involvement of the immune system. Global prevalence for psoriasis has been reported around 1-3% with a higher incidence in adults and similar proportions between men and women. The risk factors associated with psoriasis are both extrinsic and intrinsic, out of which a polygenic predisposition is a highlight out of the latter. Psoriasis etiology is not yet fully described, but several hypothesis have been proposed: 1) the autoimmunity hypothesis is based on the over-expression of antimicrobial peptides such as LL-37, the proteins ADAMTSL5, K17, and hsp27, or lipids synthesized by the PLA2G4D enzyme, all of which may serve as autoantigens to promote the differentiation of autoreactive lymphocytes T and unleash a chronic inflammatory response; 2) dysbiosis of skin microbiota hypothesis in psoriasis has gained relevance due to the observations of a loss of diversity and the participation of pathogenic bacteria such as Streptococcus spp. or Staphylococcus spp. the fungi Malassezia spp. or Candida spp. and the virus HPV, HCV, or HIV in psoriatic plaques; 3) the oxidative stress hypothesis, the most recent one, describes that the cell injury and the release of proinflammatory mediators and antimicrobial peptides that leads to activate of the Th1/Th17 axis observed in psoriasis is caused by a higher release of reactive oxygen species and the imbalance between oxidant and antioxidant mechanisms. This review aims to describe the mechanisms involved in the three hypotheses on the etiopathogeneses of psoriasis.

Interplay of cytokines in the pathophysiology of atopic dermatitis: insights from Murin models and human

The pathogenesis of atopic dermatitis (AD) is understood to be crucially influenced by three main factors: dysregulation of the immune response, barrier dysfunction, and pruritus. In the lesional skin of AD, various innate immune cells, including Th2 cells, type 2 innate lymphoid cells (ILC2s), and basophils, produce Th2 cytokines [interleukin (IL)-4, IL-5, IL-13, IL-31]. Alarmins such as TSLP, IL-25, and IL-33 are also produced by epidermal keratinocytes, amplifying type 2 inflammation. In the chronic phase, not only Th2 cells but also Th22 and Th17 cells increase in number, leading to suppression of filaggrin expression by IL-4, IL-13, and IL-22, which further deteriorates the epidermal barrier function. Dupilumab, which targets IL-4 and IL-13, has shown efficacy in treating moderate to severe AD. Nemolizumab, targeting IL-31RA, effectively reduces pruritus in AD patients. In addition, clinical trials with fezakinumab, targeting IL-22, have demonstrated promising results, particularly in severe AD cases. Conversely, in murine models of AD, several cytokines, initially regarded as promising therapeutic targets, have not demonstrated sufficient efficacy in clinical trials. IL-33 has been identified as a potent activator of immune cells, exacerbating AD in murine models and correlating with disease severity in human patients. However, treatments targeting IL-33 have not shown sufficient efficacy in clinical trials. Similarly, thymic stromal lymphopoietin (TSLP), integral to type 2 immune responses, induces dermatitis in animal models and is elevated in human AD, yet clinical treatments like tezepelumab exhibit limited efficacy. Therapies targeting IL-1α, IL-5, and IL-17 also failed to achieve sufficient efficacy in clinical trials. It has become clear that for treating AD, IL-4, IL-13, and IL-31 are relevant therapeutic targets during the acute phase, while IL-22 emerges as a target in more severe cases. This delineation underscores the necessity of considering distinct pathophysiological aspects and therapeutic targets in AD between mouse models and humans. Consequently, this review delineates the distinct roles of cytokines in the pathogenesis of AD, juxtaposing their significance in human AD from clinical trials against insights gleaned from AD mouse models. This approach will improve our understanding of interspecies variation and facilitate a deeper insight into the pathogenesis of AD in humans.

Paradoxical psoriasis: The flip side of idiopathic psoriasis or an autocephalous reversible drug reaction?

Psoriasis is a common, chronic skin disease that results mainly from the complex interplay between T cells, dendritic cells, and inflammatory cytokines including TNF-α, IL-17, IL-12, and IL-23. Successful therapy with anti-cytokine antibodies has proved the importance of these key cytokines, especially TNF-α. During the anti-TNF-α treatment of classical idiopathic psoriasis, a small portion of patients develop new psoriasiform lesions. This contradictory phenomenon was named paradoxical psoriasis which resembles idiopathic psoriasis clinically but presents overlapped histological patterns and distinct immunological processes. In this review, we discuss the differences between idiopathic psoriasis and paradoxical psoriasis with an emphasis on their innate immunity, as it is predominant in paradoxical psoriasis which exhibits type I IFN-mediated immunity without the activation of autoreactive T cells and memory T cells. We also put up an instructive algorithm for the management of paradoxical psoriasis. The decision on drug discontinuation or switching of biologics should be made based on the condition of underlying diseases and the severity of lesions.

Effect of Systemic Administration of CD4+ T cells and Local Administration of T-cell Stimulants on T-cell Activity in Psoriatic Skin Xenografts on NOG Mice

Immunodeficient mice engrafted with psoriatic human skin are widely used for the preclinical evaluation of new drug candidates. However, the T-cell activity, including the IL23/IL17 pathway, declines in the graft over time after engraftment, which likely affects the study data. Here, we investigated whether the T-cell activity could be sustained in xenografted psoriatic skin by local stimulation of T cells or systemic injection of autologous CD4 + T cells. We surgically transplanted human psoriatic skin from 5 untreated patients onto female NOG mice. Six days after surgery, mice received an intraperitoneal injection of autologous human CD4+ T cells, a subcutaneous injection under the grafts of a T-cell stimulation cocktail consisting of recombinant human IL2, human IL23, antihuman CD3, and antihuman CD28, or saline. Mice were euthanized 21 d after surgery and spleens and graft biopsies were collected for analysis. Human T cells were present in the grafts, and 60% of the grafts maintained the psoriatic phenotype. However, neither local T-cell stimulation nor systemic injection of autologous CD4+ T cells affected the protein levels of human IL17A, IL22, IFN γ, and TNF α in the grafts. In conclusion, NOG mice seem to accept psoriatic skin grafts, but the 2 approaches studied here did not affect human T-cell activity in the grafts. Therefore, NOG mice do not appear in this regard to be superior to other immunodeficient mice used for psoriasis xenografts.

The biological basis of disease recurrence in psoriasis

Despite the amazing advances produced in our understanding of the pathogenesis of psoriasis, which have led to a therapeutic revolution, our knowledge of the mechanisms of relapse and elicitation of lesions is just starting to unravel. This narrative review tours the different cell types and mechanisms involved in the priming, maintenance, and relapse of psoriasis vulgaris. Our discussion includes dendritic cells, T cells, tissue resident memory cells and mast cells, with a foray into the epigenetic mechanisms of inflammatory memory in keratinocytes. Increasing knowledge is providing a glimpse of a potential therapeutic window of opportunity in psoriasis, providing long term remission and eventual modification of the natural history of the disease.

MCAM+CD161- Th17 Subset Expressing CD83 Enhances Tc17 Response in Psoriasis

Recent studies have highlighted the pathogenic roles of IL-17-producing CD8+ T cells (T-cytotoxic 17 [Tc17]) in psoriasis. However, the underlying mechanisms of Tc17 induction remain unclear. In this study, we focused on the pathogenic subsets of Th17 and their mechanism of promotion of Tc17 responses. We determined that the pathogenic Th17-enriched fraction expressed melanoma cell adhesion molecule (MCAM) and CCR6, but not CD161, because this subset produced IL-17A abundantly and the presence of these cells in the peripheral blood of patients has been correlated with the severity of psoriasis. Intriguingly, the serial analysis of gene expression revealed that CCR6+MCAM+CD161-CD4+ T cells displayed the gene profile for adaptive immune responses, including CD83, which is an activator for CD8+ T cells. Coculture assay with or without intercellular contact between CD4+ and CD8+ T cells showed that CCR6+MCAM+CD161-CD4+ T cells induced the proliferation of CD8+ T cells in a CD83-dependent manner. However, the production of IL-17A by CD8+ T cells required exogenous IL-17A, suggesting that intercellular contact via CD83 and the production of IL-17A from activated CD4+ T cells elicit Tc17 responses. Intriguingly, the CD83 expression was enhanced in the presence of IL-15, and CD83+ cells stimulated with IL-1β, IL-23, IL-15, and IL-15Rα did not express FOXP3. Furthermore, CCR6+MCAM+CD161-CD4+ T cells expressing CD83 were increased in the peripheral blood of patients, and the CD83+ Th17-type cells accumulated in the lesional skin of psoriasis. In conclusion, pathogenic MCAM+CD161- Th17 cells may be involved in the Tc17 responses via IL-17A and CD83 in psoriasis.

Intestinal dysbiosis exacerbates the pathogenesis of psoriasis-like phenotype through changes in fatty acid metabolism

The intestinal microbiota has been associated with host immunity as well as psoriasis; however, the mechanism of intestinal microbiota regulating psoriasis needs to be demonstrated systematically. Here, we sought to examine its role and mechanism of action in the pathogenesis of psoriasis. We found that the severity of psoriasis-like skin phenotype was accompanied by changes in the composition of the intestinal microbiota. We performed co-housing and fecal microbial transplantation (FMT) experiments using the K14-VEGF transgenic mouse model of psoriasis and demonstrated that the transfer of intestinal microbiota from mice with severe psoriasis-like skin phenotype exacerbated psoriasiform skin inflammation in mice with mild symptoms, including increasing the infiltration and differentiation of Th17, and increased the abundance of Prevotella, while decreasing that of Parabacteroides distasonis, in the colon. These alterations affected fatty acid metabolism, increasing the abundance of oleic and stearic acids. Meanwhile, gentamicin treatment significantly reduced the abundance of Prevotella and alleviated the psoriasis-like symptoms in both K14-VEGF mice and imiquimod (IMQ)-induced psoriasis-like mice. Indeed, administration of oleic and stearic acids exacerbated psoriasis-like symptoms and increased Th17 and monocyte-derived dendritic cell infiltration in the skin lesion areas in vivo, as well as increased the secretion of IL-23 by stimulating DCs in vitro. At last, we found that, treatment of PDE-4 inhibitor alleviated psoriasis-like phenotype of K14-VEGF mice accompanied by the recovery of intestinal microbiota, including the decrease of Prevotella and increase of Parabacteroides distasonis. Overall, our findings reveal that the intestinal microbiota modulates host metabolism and psoriasis-like skin inflammation in mice, suggesting a new target for the clinical diagnosis and treatment of psoriasis.

Intravenous As2O3 as a promising treatment for psoriasis - an experimental study in psoriasis-like mouse model

OBJECTIVE

To evaluate the efficacy and mechanistic bases of the intravenous injection of arsenic trioxide at clinical-relevant doses for treating an imiquimod-induced psoriasis-like mouse model.

METHODS

After inducing psoriasis-like skin lesions on the back of mice with imiquimod, mice in each group were injected with a clinical dose of arsenic trioxide through the tail vein. The changes in the gene expression, protein expression and distribution of relevant inflammatory factors were evaluated in the inflicted skin area, for mechanisms underlying the efficacy of intravenous As₂O₃ intervention. HaCaT cells were used to establish an in vitro psoriasis model and pcDNA3.1-NF-κB overexpression plasmid was transfected into cells to overexpress P65, which further confirmed the role of the NF-κB signaling pathway in the effectiveness of As₂O₃.

RESULTS

Clinical dose of As₂O₃ can significantly improve abnormal symptoms and pathological changes in psoriasis-like skin lesions induced by IMQ in mice. While IMQ induced abnormal expression and distribution of inflammatory factors in the RIG-I pathway and the microRNA-31 (miR-31) pathway in psoriatic skin tissues, intravenous As₂O₃ can effectively regulate and restore the normality. The leading role of NF-κB signaling was evidenced in vivo and validated in vitro using the NF-κB-overexpressed HaCaT cell model.

CONCLUSION

Clinical dosage of As₂O₃ may achieve effective treatment of IMQ-induced psoriatic skin lesions by modulating the NF-κB signaling pathway which regulates both the RIG-I and the miR-31 lines of action. Our data provided strong evidence supporting the claim that systemic As₂O₃ administration of clinical doses can be a promising treatment for psoriasis patients.

Decoupling the role of RORγt in the differentiation and effector function of TH17 cells

RORγt is known to instruct the differentiation of T helper 17 (T_H17) cells that mediate the pathogenesis of autoimmune diseases. However, it remains unknown whether RORγt plays a distinct role in the differentiation and effector function of T_H17 cells. Here, we show that mutation of RORγt lysine-256, a ubiquitination site, to arginine (K256R) separates the RORγt role in these two functions. Preventing ubiquitination at K256 via arginine substitution does not affect RORγt-dependent thymocyte development, and T_H17 differentiation in vitro and in vivo, however, greatly impaired the pathogenesis of T_H17 cell-mediated experimental autoimmune encephalomyelitis (EAE). Mechanistically, K256R mutation impairs RORγt to bind to and activate Runx1 expression critical for T_H17-mediated EAE. Thus, RORγt regulates the effector function of T_H17 cells in addition to T_H17 differentiation. This work informs the development of RORγt-based therapies that specifically target the effector function of T_H17 cells responsible for autoimmunity.

Etiopathogenesis of Psoriasis from Genetic Perspective: An updated Review

Psoriasis is an organ-specific autoimmune disease characterized by the aberrant proliferation and differentiation of keratinocytes, leading to skin lesions. Abnormal immune responses mediated by T cells and dendritic cells and increased production of inflammatory cytokines have been suggested as underlying mechanisms in the pathogenesis of psoriasis. Emerging evidence suggests that there is a heritable basis for psoriatic disorders. Moreover, numerous gene variations have been associated with the disease risk, particularly those in innate and adaptive immune responses and antigen presentation pathways. Herein, this article discusses the genetic implications of psoriatic diseases' etiopathogenesis to develop novel investigative and management options.

IL-23 Inhibits Trophoblast Proliferation, Migration, and EMT via Activating p38 MAPK Signaling Pathway to Promote Recurrent Spontaneous Abortion

As a vital problem in reproductive health, recurrent spontaneous abortion (RSA) affects about 1% of women. We performed this study with an aim to explore the molecular mechanism of interleukin-23 (IL-23) and find optimal or effective methods to improve RSA. First, ELISA was applied to evaluate the expressions of IL-23 and its receptor in HTR-8/SVneo cells after IL-23 treatment. CCK-8, TUNEL, wound healing and transwell assays were employed to assess the proliferation, apoptosis, migration and invasion of HTR-8/SVneo cells, respectively. Additionally, the expressions of apoptosis-, migration-, epithelial-mesenchymal transition- (EMT-) and p38 MAPK signaling pathway-related proteins were measured by western blotting. To further investigate the relationship between IL-23 and p38 MAPK signaling pathway, HTR-8/SVneo cells were treated for 1 h with p38 MAPK inhibitor SB239063, followed by a series of cellular experiments on proliferation, apoptosis, migration and invasion, as aforementioned. The results showed that IL-23 and its receptors were greatly elevated in IL-23-treated HTR-8/SVneo cells. Additionally, IL-23 demonstrated suppressive effects on the proliferation, apoptosis, migration, invasion and EMT of IL-23-treated HTR-8/SVneo cells. More importantly, the molecular mechanism of IL-23 was revealed in this study; that is to say, IL-23 inhibited the proliferation, apoptosis, migration, invasion and EMT of IL-23-treated HTR-8/SVneo cells via activating p38 MAPK signaling pathway. In conclusion, IL-23 inhibits trophoblast proliferation, migration, and EMT via activating p38 MAPK signaling pathway, suggesting that IL-23 might be a novel target for the improvement of RSA.

The relapse of psoriasis: what’s the veil of mystery?

Over the past decades, tremendous success in the treatment of psoriasis has been achieved using biologics, such as neutralizing antibodies against TNF/TNFR, IL-23, and IL-17A/IL-17RA. Although psoriatic skin lesions appear to resolve after treatment with these biologics, lesions often recur after therapy is discontinued or during therapy. Memory T cells residing in the skin have been considered as the major driver of psoriasis relapse. However, whether structural cells in the skin such as keratinocytes and fibroblasts are involved in the relapse of psoriasis is unknown. In this review, we outline the therapeutic rationale of biologics used in the treatment of psoriasis, summarize different clinical features of psoriasis relapse on the basis of preclinical and clinical data, and specifically discuss how memory T cells and structural cells in the skin are involved in psoriasis relapse. Finally, we discuss the future challenges in the basic or clinical research on psoriasis.

The Role of Interleukins in the Pathogenesis of Dermatological Immune-Mediated Diseases

Autoimmune inflammatory diseases are primarily characterized by deregulated expression of cytokines, which drive pathogenesis of these diseases. A number of approved and experimental therapies utilize monoclonal antibodies against cytokine proteins. Cytokines can be classified into different families including the interleukins, which are secreted and act on leukocytes, the tumor necrosis factor (TNF) family, as well as chemokine proteins. In this review article, we focus on the interleukin family of cytokines, of which 39 members have been identified to this date. We outline the role of each of these interleukins in the immune system, and various dermatological inflammatory diseases with a focused discussion on the pathogenesis of psoriasis and atopic dermatitis. In addition, we describe the roles of various interleukins in psychiatric, cardiovascular, and gastrointestinal comorbidities. Finally, we review clinical efficacy and safety data from emerging late-phase anti-interleukin therapies under development for psoriasis and atopic dermatitis. Collectively, additional fundamental and clinical research remains necessary to fully elucidate the roles of various interleukin proteins in the pathogenesis of inflammatory dermatologic diseases, and treatment outcomes in patients.

The biological basis of disease recurrence in psoriasis: a historical perspective and current models

A key challenge in psoriasis therapy is the tendency for lesions to recur in previously affected anatomical locations after treatment discontinuation following lesion resolution. Available evidence supports the concept of a localized immunological ‘memory’ that persists in resolved skin after complete disappearance of visible inflammation, as well as the role of a specific subpopulation of T cells characterized by the dermotropic CCR4⁺ phenotype and forming a local memory. Increasing knowledge of the interleukin (IL)‐23/T helper 17 (Th17) cell pathway in psoriasis immunopathology is pointing away from the historical classification of psoriasis as primarily a Th1‐type disease. Research undertaken from the 1990s to the mid‐2000s provided evidence for the existence of a large population of CD8⁺ and CD4⁺ tissue‐resident memory T cells in resolved skin, which can initiate and perpetuate immune responses of psoriasis in the absence of T‐cell recruitment from the blood. Dendritic cells (DCs) are antigen‐presenting cells that contribute to psoriasis pathology via the secretion of IL‐23, the upstream regulator of Th17 cells, while plasmacytoid DCs are involved via IL‐36 signalling and type I interferon activation. Overall, the evidence discussed in this review indicates that IL‐23‐driven/IL‐17‐producing T cells play a critical role in psoriasis pathology and recurrence, making these cytokines logical therapeutic targets. The review also explains the clinical efficacy of IL‐17 and IL‐23 receptor blockers in the treatment of psoriasis.

Exploring the Diverse Immune and Genetic Landscape of Psoriatic Arthritis

Psoriatic arthritis (PsA) is characterized by delays in diagnosis and modest effect of treatment in terms of joint response. An understanding of molecular pathomechanisms may aid in developing diagnostic and prognostic models. Genetic susceptibility (e.g., HLA class I genes, IL-23-related genes) can be responsible for the pattern of psoriatic manifestations and affinity for tissue involvement. Gene expression analysis indicates an inflammatory profile that is distinct for PsA, but disparate across tissues. This has clinical implications, as for example, dual blockade of IL-17A and IL-17F can lead to superior clinical effects if there is differential expression of IL-17 receptors in tissues. Structural and functional impairment of barrier tissue, including host-microbiome interactions, may be the source of immune activation. Interplay between different cell populations of innate and adaptive immunity is emerging, potentially providing a link between the transition of skin-to-joint disease. Th17 subsets, IL-17A, IL-17F and IL-23 are crucial in PsA pathogenesis, with both clinical and experimental evidence suggesting a differential molecular landscape in cutaneous and articular compartments.

An Analysis of IL-10, IL-17A, IL-17RA, IL-23A and IL-23R Expression and Their Correlation with Clinical Course in Patients with Psoriasis

Being one of the most common dermatological inflammatory disorders, psoriasis is a frequent subject of research. It is considered to be a T cell-dependent immune disease whose pathogenesis is influenced by cytokines, such as IL-10, IL-17A, IL-17RA, IL-23A and IL-23R. The present study examines whether the expression of selected genes is correlated with the clinical course of psoriasis, assessed by the PASI, BSA and DLQI scales. Skin biopsies and blood from 60 patients with psoriasis and 24 healthy controls were obtained for RNA isolation. These were subjected to RT-PCR for IL-10, IL-17A, IL-17RA, IL-23A and IL-23R genes. The results were presented as an RQ value. IL-17A and IL-23R expression levels were higher in psoriatic skin compared to controls, while IL-10 expression was lower. A positive correlation was also found between RQ for IL-23A and PASI index. Psoriatic skin is characterised by elevated expression of IL-17A and IL-23R and decreased expression of IL-10. This indicates that the selected cytokines may be one of the factors involved in the pathogenesis and pathomechanism of psoriasis, but more studies need to be made before we can elucidate the exact reason for the unbalance in cytokine expression levels.

Tildrakizumab for treatment of moderate to severe psoriasis: an expert opinion of efficacy, safety, and use in special populations

INTRODUCTION

Tildrakizumab is a monoclonal antibody that targets the p19 subunit of IL-23, a crucial cytokine for Th17 cells. Tildrakizumab has been assessed in several Phase I, II, and III clinical trials and is approved for treatment of adults with moderate to severe plaque psoriasis who are indicated for systemic therapy.

AREAS COVERED

The available evidence on the efficacy, safety, and use of tildrakizumab in special populations was evaluated by 14 experts who critically reviewed the current literature.

EXPERT OPINION

Tildrakizumab has good efficacy that lasts for at least 5 years in patients with moderate to severe psoriasis, and appears to be safe and well tolerated in the long-term with no apparent dose-related differences in adverse events, a low incidence of discontinuation due to adverse events, and no evidence of increased risk of malignancies. The safety and the efficacy of tildrakizumab has also been confirmed in special populations such as those with inflammatory bowel disease, cardiovascular disease, metabolic syndrome, and advanced age. Early intervention with IL-23-inhibitors, such as tildrakizumab, may help to control symptoms and change the long-term course of the disease in patients affected by plaque psoriasis, while improving the quality of life and potentially minimizing the risk of developing comorbidities.

Targeting cytokines and immune checkpoints in atherosclerosis with monoclonal antibodies

Over the past fifteen years, treatments using monoclonal antibodies specifically targeting cytokines have been developed to treat chronic inflammatory diseases, including rheumatoid arthritis or psoriasis, both associated with increased cardiovascular risk. The cardiovascular impact of these therapies allows us to validate the clinical relevance of the knowledge acquired from experimental studies about the role of cytokines in atherosclerosis. Several clinical studies have confirmed the protective effects of anti-TNFα and anti-IL-6R monoclonal antibodies against athero-thrombotic cardiovascular risk in patients with chronic inflammatory diseases. Yet, caution is needed since anti-TNFα treatment can aggravate chronic heart failure. More recently, the CANTOS study showed for the first time that an anti-inflammatory treatment using anti-IL-1β monoclonal antibody in coronary artery disease patients significantly reduced cardiovascular events. The effects of IL-23/IL-17 axis blockade on cardiovascular risk in patients with psoriasis or arthritis remain controversial. Several monoclonal antibodies targeting costimulatory molecules have also been developed, a direct way to confirm their involvement in atherothrombotic cardiovascular diseases. Blocking the CD28^-CD80/86 axis with Abatacept has been shown to reduce cardiovascular risk. In contrast, the treatment of cancer patients with antibodies blocking immune checkpoint inhibitory receptors, such as CTLA-4, PD1, or PDL1, could worsen the risk of atherothrombotic events. In the future, cardiologists will be increasingly solicited to assess the cardiovascular risk of patients suffering from chronic inflammatory diseases or cancer and participate in choosing the most appropriate treatment. At the same time, immunomodulatory approaches directly targeting cardiovascular diseases will be developed as a complement to the usual treatment strategies.

Use of Biologics in the Treatment of Moderate-to-Severe Plantar Psoriasis

Psoriasis is a common inflammatory disorder with potentially severe systemic and dermatologic consequences. As traditional treatments for this condition fail, biologics are emerging as the next promising therapy for moderate-to-severe cases, especially for the lower extremity. This review examines current research on monoclonal antibodies that target specific cytokines including interleukin-23 (IL-23), IL-12, tumor necrosis factor alpha, and IL-17 involved in pathologic inflammatory processes.

RNA-seq reveal RNA binding protein GNL3 as a key mediator in the development of psoriasis vulgaris by regulating the IL23/IL17 axis

BACKGROUND

Psoriasis is a systemic chronic inflammatory skin disorder that was prone to recurrence. The RNA binding protein GNL3 has an important function in maintaining the proliferative ability of stem cells, and its overexpression leads to apoptosis. GNL3 is expressed in the epidermis, however, its regulatory mechanism in psoriasis vulgaris is still poorly understood.

OBJECTIVE

To identify the role of GNL3 in the pathogenesis of psoriasis vulgaris.

MATERIALS AND METHODS

RNA-seq was performed to obtain the data of genes' expression and splicing events in Hela cells after shGNL3 and shCtrl was transferred. High quality results of differentially expressed genes (DEGs) and alternative splicing events (ASEs) were further attained by quality control and analysis. Through the functional enrichment analysis of DEGs and ASEs, the regulating effect of GNL3 was discussed, and the hypothesis was further confirmed in HaCat cells and psoriasis lesions.

RESULTS

The mRNA expression of IL23A in Hela cells was upregulated in GNL3 knockdown, and the ratio of ASE occurred in TNFAIP3 was increased. However, in HaCaT cells, the mRNA expression level of IL23A was downregulated in GNL3 knockdown, and the ratio of ASE of TNFAIP3 was decreased. Additionally, the results obtained in HaCaT cells was further validated in the lesional psoriatic skin.

CONCLUSION

GNL3 takes an important part in the development of psoriasis vulgaris by regulating the IL23/IL17 axis, which may serve as the basis of effective targeted treatment in future.

A Review of the Efficacy and Safety for Biologic Agents Targeting IL-23 in Treating Psoriasis With the Focus on Tildrakizumab

Psoriasis is a chronic and debilitating inflammatory immune-mediated skin disorder. Several cytokines including interleukin (IL)-23 were demonstrated to play a central role in the pathogenesis of this disease. Treatment options for psoriasis range from topical to systemic modalities, depending on the extent, anatomical locations involved and functional impairment level. Targeting cytokines or their cognate receptors that are involved in disease pathogenesis such as IL-12/23 (i.e., targeting the IL-12p40 subunit shared by these cytokines), IL-17A, IL-17F, IL-17RA, and TNF-α using biologic agents emerged in recent years as a highly effective therapeutic option for patients with moderate-to-severe disease. This review provides an overview of the important role of IL-23 signaling in the pathogenesis of psoriasis. We describe in detail the available IL-23 inhibitors for chronic plaque psoriasis. The efficacy, pharmacokinetic properties, and the safety profile of one of the most recent IL-23 biologic agents (tildrakizumab) are evaluated and reviewed in depth.

Dendritic Cells and CCR7 Expression: An Important Factor for Autoimmune Diseases, Chronic Inflammation, and Cancer

Chemotactic cytokines-chemokines-control immune cell migration in the process of initiation and resolution of inflammatory conditions as part of the body's defense system. Many chemokines also participate in pathological processes leading up to and exacerbating the inflammatory state characterizing chronic inflammatory diseases. In this review, we discuss the role of dendritic cells (DCs) and the central chemokine receptor CCR7 in the initiation and sustainment of selected chronic inflammatory diseases: multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. We revisit the binary role that CCR7 plays in combatting and progressing cancer, and we discuss how CCR7 and DCs can be harnessed for the treatment of cancer. To provide the necessary background, we review the differential roles of the natural ligands of CCR7, CCL19, and CCL21 and how they direct the mobilization of activated DCs to lymphoid organs and control the formation of associated lymphoid tissues (ALTs). We provide an overview of DC subsets and, briefly, elaborate on the different T-cell effector types generated upon DC-T cell priming. In the conclusion, we promote CCR7 as a possible target of future drugs with an antagonistic effect to reduce inflammation in chronic inflammatory diseases and an agonistic effect for boosting the reactivation of the immune system against cancer in cell-based and/or immune checkpoint inhibitor (ICI)-based anti-cancer therapy.

Elevated Serum Interleukin-23 Levels in Patients with Oral and Cutaneous Lichen Planus

Lichen planus is considered a chronic inflammatory disease which affects different sites, such as the skin, mucous membranes, hair, and nails. Based on the evidence, a complex cytokine network plays a crucial role in lichen planus pathogenesis. The study was aimed at assessing the serum IL-23 levels in the patients with cutaneous and oral lichen planus compared to healthy controls. Method. The study included 30 cutaneous lichen planus patients, 20 oral lichen planus patients, and 33 control subjects. Five milliliters of peripheral blood was obtained from each patient, and the serum was separated. IL-23 levels were determined using the ELISA kit, and the data were analyzed using the Mann–Whitney test. Results. IL-23 levels in the patient serum with oral lichen planus (P value ≤ 0.001) were significantly higher than in controls. Furthermore, there were significant differences in IL-23 serum levels in the patients with cutaneous lichen planus compared to the healthy controls (P value ≤ 0.001). Moreover, IL-23 serum levels were statistically different between patients with cutaneous lichen planus and patients with oral lichen planus (P value ≤ 0.001). Based on the mean concentration of interleukin-23, IL-23 levels were higher in the patients with oral lichen planus than in the patients with cutaneous lichen planus. Conclusions. Elevated serum IL-23 levels in the patients with oral lichen planus may indicate that IL-23 plays a crucial role in the pathogenesis of oral lichen planus. However, more research is needed with a larger sample size.

Persistent expression of interleukin-17 and downstream effector cytokines in recalcitrant psoriatic lesions after ustekinumab treatment

The interleukin (IL)-23/T-helper (Th)17 axis is considered central to the pathogenesis of psoriasis, with IL-36γ considered a marker for histological differential diagnosis. However, expression data regarding key cytokines in the pathogenesis of psoriasis, as well as data on the effects of IL-23 inhibition on downstream cytokines in human psoriatic skin, are limited. We investigated the expression profile of key cytokines and the effect of ustekinumab (UST) on cytokine expression in human psoriatic tissue. Tumor necrosis factor (TNF)-α, IL-23, IL-17A, and IL-22 were highly expressed in the epidermis, dermal papillae, and upper dermis in patients with psoriasis compared with controls; IL-36γ was strongly expressed in the upper epidermis. Compared with the untreated group, expression intensity and area of IL-23 were significantly decreased in the UST group; expression areas of TNF-α, IL-17A, IL-22, and IL-36γ did not differ. This study identified the distribution and quantitative expression levels of key cytokines in psoriatic lesions and demonstrated that only IL-23 was downregulated without blocking downstream effector cytokines in recalcitrant psoriatic lesions during UST treatment. Our results suggest that, although IL-23 is inhibited, the persistent expression of IL-17 through an alternative pathway maintains the vicious cycle of the TNF-α/IL-23/IL-17 axis with IL-36γ, inducing refractory psoriatic lesions in patients with well-controlled psoriasis.

Polymers in topical delivery of anti-psoriatic medications and other topical agents in overcoming the barriers of conventional treatment strategies

In recent decades, topical treatments to dermal disorders have shown ineffectiveness in delivering the medication at a particular location without a suitable drug carrier. Psoriasis treatment is hindered because of the ineffective delivery and efficacy of conventional pharmaceutical treatment. In conventional medication formulation approach, it is difficult to breach the transdermal layer of a skin membrane for topical drugs, i.e. cyclosporine, methotrexate. This problem is further complicated by extreme disease-associated conditions such as hyperkeratosis and irritation. Intending to assure better drug delivery carriers, this review emphasizes the therapeutic efficacy of polymers and their potential to deliver the drug into the deeper layer of the skin membrane. The polymers are essential in structural and physiochemical perspectives as it works as a carrier for the medication. A vast variety of delivery carriers is available nowadays but their applicability in such dermal cases like psoriasis is still lacking due to less knowledge on an appropriate polymer. The current investigation of suitable polymer would assist in brushing our expertise to optimize the advantages of a wide spectrum of polymers to fulfill the topical targeting of psoriasis.

Granulomatous mastitis, erythema nodosum and arthritis syndrome: case-based review

Granulomatous mastitis (GM) is a rare form of inflammatory breast condition associated with unilateral or bilateral breast pain, swelling and mass formation. Although the disease pathogenesis remains unknown, several reports have associated GM with manifestations such as erythema nodosum and occasionally with arthritis, suggesting that GM might have an autoimmune disease component. We aim to describe two cases of coexistence of GM, erythema nodosum, and arthritis. We also conducted a literature review to comprehensively assess and describe the characteristics of patients with GM, erythema nodosum, and arthritis, and identify effective treatment options. A literature review was conducted using PubMed and EMBASE, and 14 case reports/series were retrieved, with a total number of 29 patients. All patients are women and unilateral breast involvement was evident in the majority of patients. Nine patients (31%) presented with arthritis, 6 patients (20.7%) had a fever, and 6 patients (20.7%) developed the symptoms during pregnancy. All patients had normal chest radiograph and tissue cultures were negative. In most of the cases (n = 25, 86.2%), symptom improvement was observed with glucocorticoids and four patients (13.8%) underwent surgical treatment for the GM. Given the clinical characteristics of patients with GM, with erythema nodosum, with or without arthritis, and the positive response to glucocorticoids, we propose that the described phenotype represents an underrecognized systemic autoimmune disease that could be designated by the acronym "GMENA" (granulomatous mastitis, erythema nodosum, arthritis) syndrome. Further studies are needed to elucidate the pathogenesis of the syndrome.

Synergistic induction of IL-23 by TNFα, IL-17A, and EGF in keratinocytes

IL-23 is an inflammatory cytokine that plays an essential role in Th17 immunity by enhancing Th17 cell proliferation and survival, and Th17 cytokine production. IL-23 has pathogenic roles in the development of Th17-mediated inflammatory diseases including psoriasis. Despite successful treatment of psoriasis by blocking IL-23, the regulation of IL-23 expression in psoriasis patients is largely unknown. Dendritic cells are generally considered to be the primary source of IL-23 in psoriasis. While high levels of IL-23 are found in psoriatic epidermis, IL-23 expression in psoriatic keratinoctyes remains a controversial issue. In this study, we demonstrated that IL-23 production is induced by a combination of TNFα and IL-17A in human keratinocytes. Additionally, this IL-23 induction by TNFα and IL-17A is further increased in psoriatic keratinocytes and is enhanced by EGFR signaling. Although IL-23 is also robustly induced by toll-like receptor agonists in dendritic cells and macrophages, IL-23 expression in these cell types is not regulated by TNFα, IL-17A, and EGFR signaling. Given that IL-23 is essential for maintaining Th17 activation, IL-23 induction by TNFα, IL-17A, and EGF in keratinocytes could play an important pathological role in psoriasis pathogenesis as well as the cutaneous rash associated with EGFR inhibition therapy.

Cardiovascular Involvement in Psoriasis, Diagnosing Subclinical Atherosclerosis, Effects of Biological and Non-Biological Therapy: A Literature Review

Psoriasis is a long-lasting, noncontagious chronic inflammatory disease of skin and joints. Previous epidemiological studies have demonstrated that psoriatic patients have a shorter life expectancy, mainly due to cardiovascular (CV) events with a higher prevalence of cardiovascular risk factors like dyslipidemia, diabetes mellitus, insulin resistance, obesity, and hypertension. Besides these risk factors, psoriasis likely plays an independent role in increasing CV events probably due to the chronic inflammatory state. This literature review aims to summarize the mechanism of atherosclerosis formation, CV risk factors, tools to diagnose subclinical atherosclerosis, and the effects of various therapies in psoriatic patients to prevent cardiovascular-related deaths in psoriasis. This review was performed by searching the relevant articles in PubMed and Google Scholar databases without including any exclusion criteria and time limitations. Our review documented that psoriatic patients are at increased risk of CV events due to chronic inflammatory profile and the associated CV risk factors. Also, anti-inflammatory therapies may prevent early subclinical atherosclerotic vascular changes reducing cardiovascular events. However, the available studies lack to establish the exact targets for CV risk factors, to assess the clinical importance of screening for subclinical vascular changes and the impact of anti-inflammatory therapies on CV risk profile in psoriatic patients. This heightened awareness about the CV involvement in psoriasis should encourage conducting large, well planned comprehensive studies to address these issues that can reduce cardiovascular morbidity and mortality.

Targeting interleukin-17 in chronic inflammatory disease: A clinical perspective

Although many chronic inflammatory diseases share the feature of elevated IL-17 production, therapeutic targeting of IL-17 has vastly different clinical outcomes. Here the authors summarize the recent progress in understanding the protective and pathogenic role of the IL-23/IL-17 axis in preclinical models and human inflammatory diseases.

Chronic inflammatory diseases like psoriasis, Crohn’s disease (CD), multiple sclerosis (MS), rheumatoid arthritis (RA), and others are increasingly recognized as disease entities, where dysregulated cytokines contribute substantially to tissue-specific inflammation. A dysregulation in the IL-23/IL-17 axis can lead to inflammation of barrier tissues, whereas its role in internal organ inflammation remains less clear. Here we discuss the most recent developments in targeting IL-17 for the treatment of chronic inflammation in preclinical models and in patients afflicted with chronic inflammatory diseases.

Nonclinical safety of tildrakizumab, a humanized anti-IL-23p19 monoclonal antibody, in nonhuman primates

Tildrakizumab (also known as MK-3222), is a high-affinity, humanized, immunoglobin G1κ monoclonal antibody targeting the p19 subunit of interleukin-23 recently approved for the treatment of moderate to severe plaque psoriasis in the US, Europe, and Australia. The safety profile of tildrakizumab was characterized in nonclinical studies using a pharmacologically relevant cynomolgus monkey model. In repeat-dose toxicity studies, cynomolgus monkeys were chronically treated with subcutaneous (SC) injections of 100 mg/kg of tildrakizumab every 2 weeks up to 9 months. Tildrakizumab was well tolerated, with no toxicological findings (including assessment of reproductive organs; hormonal effects; and cardiovascular, respiratory, and central nervous system function) at systemic exposures approximately 90 times higher than the recommended human dose of 100 mg. An embryofetal developmental study conducted in pregnant monkeys revealed no treatment-related effects to the developing fetus following SC administration of tildrakizumab 100 mg/kg. In a pre- and postnatal development study, 2 neonatal deaths due to potential viral infection at 100 mg/kg were considered of uncertain relationship to the treatment based on a lack of historical data on the occurrence of viral infection in neonate cynomolgus monkeys. The results of this comprehensive nonclinical safety program support the safe use of tildrakizumab.

Adenoviral gene transfer of a single-chain IL-23 induces psoriatic arthritis-like symptoms in NOD mice

Previously, we demonstrated that intratumoral delivery of adenoviral vector encoding single-chain (sc)IL-23 (Ad.scIL-23) was able to induce systemic antitumor immunity. Here, we examined the role of IL-23 in diabetes in nonobese diabetic mice. Intravenous delivery of Ad.scIL-23 did not accelerate the onset of hyperglycemia but instead resulted in the development of psoriatic arthritis. Ad.scIL-23-treated mice developed erythema, scales, and thickening of the skin, as well as intervertebral disc degeneration and extensive synovial hypertrophy and loss of articular cartilage in the knees. Immunological analysis revealed activation of conventional T helper type 17 cells and IL-17-producing γδ T cells along with a significant depletion and suppression of T cells in the pancreatic lymph nodes. Furthermore, treatment with anti-IL-17 antibody reduced joint and skin psoriatic arthritis pathologies. Thus, these Ad.scIL-23-treated mice represent a physiologically relevant model of psoriatic arthritis for understanding disease progression and for testing therapeutic approaches.-Flores, R. R., Carbo, L., Kim, E., Van Meter, M., De Padilla, C. M. L., Zhao, J., Colangelo, D., Yousefzadeh, M. J., Angelini, L. A., Zhang, L., Pola, E., Vo, N., Evans, C. H., Gambotto, A., Niedernhofer, L. J., Robbins, P. D. Adenoviral gene transfer of a single-chain IL-23 induces psoriatic arthritis-like symptoms in NOD mice.

Anticytokine Immune Therapy and Atherothrombotic Cardiovascular Risk

Accumulating observations in humans and animals indicate that inflammation plays a key role in atherosclerosis development and subsequent complications. Moreover, the use of loss- or gain-of-function genetically modified, atherosclerosis-prone mice has provided strong experimental evidence for a causal role of innate and adaptive immunity in atherosclerosis and has revealed the pathogenic activity of proinflammatory cytokines, including TNF (tumor necrosis factor)-α, IL (interleukin)-1β, IL-6, and IL-18, and the atheroprotective effect of anti-inflammatory cytokines, including IL-10 and TGF-β. For the past 15 years, treatments using monoclonal antibodies specifically targeting cytokines, commonly referred as biological therapies, have transformed the treatment of chronic inflammatory diseases, such as rheumatoid arthritis or psoriasis, both conditions associated with increased cardiovascular risk. Analyzing the impact of anticytokine therapies on the cardiovascular outcomes of patients with chronic inflammatory diseases provides insight into the clinical relevance of experimental data on the role of inflammation in atherothrombotic cardiovascular diseases. CANTOS (Canakinumab Antiinflammatory Thrombosis Outcome Study) provided the first evidence that targeting inflammation in humans with atherosclerosis could improve clinical outcomes. Treatment with the anti-IL-1β antibody canakinumab significantly reduced recurrent cardiovascular events in individuals with stable coronary artery disease well-treated with standard-of-care measures. Other clinical studies support the protective effects of treatment with anti-TNF-α and anti-IL-6 receptor monoclonal antibodies on cardiovascular risk. Blockade of the IL-23/IL-17 axis, however, warrants caution as a cardiovascular intervention. Targeting this pathway has improved psoriasis but may augment cardiovascular risk in certain patients. Thus, careful consideration of the cardiovascular risk profile may influence the choice of the most appropriate treatment for patients with chronic inflammatory diseases.Visual Overview: An online visual overview is available for this article.

Discovery of the IL-23/IL-17 Signaling Pathway and the Treatment of Psoriasis

Psoriasis vulgaris is a common, heterogeneous, chronic inflammatory skin disease characterized by thickened, red, scaly plaques and systemic inflammation. Psoriasis is also associated with multiple comorbid conditions, such as joint destruction, cardiovascular disease, stroke, hypertension, metabolic syndrome, and chronic kidney disease. The discovery of IL-17-producing T cells in a mouse model of autoimmunity transformed our understanding of inflammation driven by T lymphocytes and associations with human inflammatory diseases, such as psoriasis. Under the regulation of IL-23, T cells that produce high levels of IL-17 create a self-amplifying, feed-forward inflammatory response in keratinocytes that drives the development of thickened skin lesions infiltrated with a mixture of inflammatory cell populations. Recently, the Food and Drug Administration approved multiple highly effective psoriasis therapies that disrupt IL-17 (secukinumab, ixekizumab, and brodalumab) and IL-23 (guselkumab and tildrakizumab) signaling in the skin, thus leading to a major paradigm shift in the way that psoriatic disease is managed.

The IL-12 Cytokine and Receptor Family in Graft-vs.-Host Disease

Allogeneic hematopoietic cell transplantation (allo-HCT) is performed with curative intent for high- risk blood cancers and bone marrow failure syndromes; yet the development of acute and chronic graft-vs.-host disease (GVHD) remain preeminent causes of death and morbidity. The IL-12 family of cytokines is comprised of IL-12, IL-23, IL-27, IL-35, and IL-39. This family of cytokines is biologically distinct in that they are composed of functional heterodimers, which bind to cognate heterodimeric receptor chains expressed on T cells. Of these, IL-12 and IL-23 share a common β cytokine subunit, p40, as well as a receptor chain: IL-12Rβ1. IL-12 and IL-23 have been documented as proinflammatory mediators of GVHD, responsible for T helper 1 (Th1) differentiation and T helper 17 (Th17) stabilization, respectively. The role of IL-27 is less defined, seemingly immune suppressive via IL-10 secretion by Type 1 regulatory (Tr1) cells yet promoting inflammation through impairing CD4⁺ T regulatory (Treg) development and/or enhancing Th1 differentiation. More recently, IL-35 was described as a potent anti-inflammatory agent produced by regulatory B and T cells. The role of the newest member, IL-39, has been implicated in proinflammatory B cell responses but has not been explored in the context of allo-HCT. This review is directed at discussing the current literature relevant to each IL-12-family cytokine and cognate receptor engagement, as well as the consequential downstream signaling implications, during GVHD pathogenesis. Additionally, we will provide an overview of translational strategies targeting the IL-12 family cytokines, their receptors, and subsequent signal transduction to control GVHD.

Monocytes/Macrophages play a pathogenic role in IL-23 mediated psoriasis-like skin inflammation

Psoriasis is an immune-mediated inflammatory skin disease that affects millions worldwide. Studying immune cells involved in psoriasis pathogenesis is essential to identify effective and safe therapeutics for the disease. Using human psoriasis skin, activated macrophages were observed in both lesional and non-lesional skin, but were elevated in lesional skin. Activation of the IL-23/IL-17 pathway is integral to the development of psoriasis. To further characterize the monocyte/macrophage (Mon/Mac) population when the IL-23 pathway is activated, a murine model of intradermal injection of IL-23 was used. Flow cytometry revealed that Mon/Mac cells were the dominant immune population, particularly late in the model, highlighted by strong presence of Ly6C^hiMHC II^hi cells. The Mon/Mac cells were also shown to have high expression for TNFα but not IL-17A. Prophylactic dosing of a CSF-1R inhibitor to deplete Mon/Mac cells significantly reduced several inflammatory mediators from the skin tissue suggesting a pathogenic role for Mon/Mac. Treatment dosing of the inhibitor produced a less robust effect. Mon/Mac cells were also differentiated by levels of Ki67 and TNFα expression. These data point to an important contribution of Mon/Mac cells in IL-23 related skin inflammation and suggest that these cells are a significant player in the underlying pathophysiology of psoriasis.

Antagonizing Retinoic Acid-Related-Orphan Receptor Gamma Activity Blocks the T Helper 17/Interleukin-17 Pathway Leading to Attenuated Pro-inflammatory Human Keratinocyte and Skin Responses

The nuclear hormone receptor retinoic acid receptor-related-orphan-receptor-gamma t (RORγt) is the key transcription factor required for Th17 cell differentiation and for production of IL-17 family cytokines by innate and adaptive immune cells. Dysregulated Th17 immune responses have been associated with the pathogenesis of several inflammatory and autoimmune diseases such as psoriasis, psoriatic arthritis, and ankylosing spondylitis. In this article, we describe the in vitro pharmacology of a potent and selective low molecular weight RORγt inhibitor identified after a structure-based hit-to-lead optimization effort. The compound interfered with co-activator binding to the RORγt ligand binding domain and impaired the transcriptional activity of RORγt as evidenced by blocked IL-17A secretion and RORE-mediated transactivation of a luciferase reporter gene. The inhibitor effectively reduced IL-17A production by human naive and memory T-cells and attenuated transcription of pro-inflammatory Th17 signature genes, such as IL17F, IL22, IL26, IL23R, and CCR6. The compound selectively suppressed the Th17/IL-17 pathway and did not interfere with polarization of other T helper cell lineages. Furthermore, the inhibitor was selective for RORγt and did not modify the transcriptional activity of the closely related family members RORα and RORβ. Using human keratinocytes cultured with supernatants from compound treated Th17 cells we showed that pharmacological inhibition of RORγt translated to suppressed IL-17-regulated gene expression in keratinocyte cell cultures. Furthermore, in ex vivo immersion skin cultures our RORγt inhibitor suppressed IL-17A production by Th17-skewed skin resident cells which correlated with reduced human β defensin 2 expression in the skin. Our data suggests that inhibiting RORγt transcriptional activity by a low molecular weight inhibitor may hold utility for the treatment of Th17/IL-17-mediated skin pathologies.

AS2762900-00, a potent anti-human IL-23 receptor monoclonal antibody, prevents epidermal hyperplasia in a psoriatic human skin xenograft model

Interleukin (IL)-23 is thought to be critical in the pathogenesis of psoriasis, and anti-IL-23 monoclonal antibodies (mAbs) have been approved for the treatment of psoriasis. We speculated that an anti-IL-23 receptor mAb might have greater efficacy than an anti-IL-23 mAb in the treatment of local inflamed lesions with high IL-23 levels. We previously generated an anti-human IL-23 receptor mAb, AS2762900-00, which potently blocked IL-23-induced cell proliferation, regardless of the concentration of IL-23. Here, we evaluated the therapeutic potential of AS2762900-00 in the treatment of psoriasis. Compared with untreated control, AS2762900-00 significantly reduced the epidermal thickness of lesions in a clinically relevant psoriatic human skin xenograft model. The expression of inflammatory genes including genes downstream of IL-23 signaling in the lesion tended to be lower in the AS2762900-00 group than the untreated group, suggesting that the inhibitory effects of AS2762900-00 in the psoriatic human skin xenograft model might occur via blockade of IL-23 signaling pathways. Further, AS2762900-00 showed an inhibitory effect on signal transducer and activator of transcription 3 (STAT3) phosphorylation as a downstream signal of IL-23 receptor activation in whole blood from patients with psoriasis. We also confirmed that AS2762900-00 inhibited IL-23-induced STAT3 phosphorylation in a concentration-dependent manner using whole blood from healthy donors. These data suggest that AS2762900-00 is a promising drug candidate for the treatment of psoriasis. In addition, STAT3 phosphorylation in whole blood may be a useful biomarker for the evaluation of the pharmacodynamic effects of AS2762900-00 in healthy volunteers in clinical development.

SRC3 Is a Cofactor for RORγt in Th17 Differentiation but Not Thymocyte Development

SRC3, a highly conserved member of the steroid receptor coactivator (SRC) family, is recruited by transcription factors to regulate cellular function. Previously, we demonstrated that SRC1, another highly conserved member of the SRC family, interacts with RORγt to regulate Th17 differentiation. However, the relationship between SRC1 and SRC3 in the regulation of Th17 cell function remains unknown. In this study, we demonstrate that mouse SRC3 interacts with RORγt in Th17 cells but not in thymocytes. In addition, Src3^-/- mice exhibited defective Th17 differentiation and induction of experimental autoimmune encephalomyelitis but normal thymocyte development. Furthermore, a K313 to arginine mutation of RORγt (RORγt-K313R), which disrupts the interaction of RORγt with SRC3 but not with SRC1, impairs Th17 differentiation but not thymocyte development. These data suggest that SRC3 works with SRC1 to regulate RORγt-dependent Th17 differentiation but is not essential for RORγt-dependent thymocyte development.

IL-23-induced macrophage polarization and its pathological roles in mice with imiquimod-induced psoriasis

Macrophages acquire distinct phenotypes during tissue stress and inflammatory responses. Macrophages are roughly categorized into two different subsets named inflammatory M1 and anti-inflammatory M2 macrophages. We herein identified a unique pathogenic macrophage subpopulation driven by IL-23 with a distinct gene expression profile including defined types of cytokines. The freshly isolated resting mouse peritoneal macrophages were stimulated with different cytokines in vitro, the expression of cytokines and chemokines were detected by microarray, real-time PCR, ELISA and multiple colors flow cytometry. Adoptive transfer of macrophages and imiquimod-induced psoriasis mice were used. In contrast to M1- and M2-polarized macrophages, IL-23-treated macrophages produce large amounts of IL-17A, IL-22 and IFN-γ. Biochemical and molecular studies showed that IL-23 induces IL-17A expression in macrophages through the signal transducer and activator of transcription 3 (STAT3)-retinoid related orphan receptor-γ T (RORγT) pathway. T-bet mediates the IFN-γ production in IL-23-treated macrophages. Importantly, IL-23-treated macrophages significantly promote the dermatitis pathogenesis in a psoriasis-like mouse model. IL-23-treated resting macrophages express a distinctive gene expression prolife compared with M1 and M2 macrophages. The identification of IL-23-induced macrophage polarization may help us to understand the contribution of macrophage subpopulation in Th17-cytokines-related pathogenesis.

Psoriasis: Classical vs. Paradoxical. The Yin-Yang of TNF and Type I Interferon

Chronic plaque psoriasis is a common debilitating skin disease. The identification of the pathogenic role of the TNF/IL-23/T_H17 pathway has enabled the development of targeted therapies used in the clinic today. Particularly, TNF inhibitors have become a benchmark for the treatment of numerous chronic inflammatory diseases such as psoriasis. Although being highly effective in psoriasis treatment, anti-TNFs can themselves induce psoriasis-like skin lesions, a side effect called paradoxical psoriasis. In this review, we provide a comprehensive look at the different cellular and molecular players involved in classical plaque psoriasis and contrast its pathogenesis to paradoxical psoriasis, which is clinically similar but immunologically distinct. Classical psoriasis is a T-cell mediated autoimmune disease driven by TNF, characterised by T-cells memory, and a relapsing disease course. In contrast, paradoxical psoriasis is caused by the absence of TNF and represents an ongoing type-I interferon-driven innate inflammation that fails to elicit T-cell autoimmunity and lacks memory T cell-mediated relapses.

Sumoylation of RORγt regulates TH17 differentiation and thymocyte development

RORγt controls the differentiation of T_H17 cells, which are mediators of autoimmune conditions such as experimental autoimmune encephalomyelitis (EAE). RORγt also regulates thymocyte development and lymph node genesis. Here we show that the function of RORγt is regulated by its sumoylation. Loss of Sumo3, but not Sumo1, dampens T_H17 differentiation and delays the progression of thymic CD8⁺ immature single-positive cells (ISPs). RORγt is SUMO3-modified by E3 ligase PIAS4 at lysine 31 (K31), and the mutation of K31 to arginine in mice prevents RORγt sumoylation, leading to impaired T_H17 differentiation, resistance to T_H17-mediated EAE, accumulation of thymic ISPs, and a lack of Peyer’s patches. Mechanistically, sumoylation of RORγt-K31 recruits histone acetyltransferase KAT2A, which stabilizes the binding of SRC1 to enhance RORγt transcription factor activity. This study thus demonstrates that sumoylation is a critical mechanism for regulating RORγt function, and reveals new drug targets for preventing T_H17-mediated autoimmunity.

The transcription factor RORγt is essential for the differentiation of T_H17 cells, thymocyte development and lymphoid organogenesis. Here the authors show that the function of RORγt is regulated by PIAS4-mediated sumoylation that stabilize the interaction with SRC1 and KAT2A, to enhance the transcriptional activity of RORγt.

Tildrakizumab for the treatment of psoriasis

Psoriasis is a chronic skin disorder driven by IL-23 and the downstream T-helper cell 17 (Th17) pathway. Tildrakizumab is a humanized monoclonal antibody selectively targeting the p19 subunit of IL-23, a key cytokine for Th17 cells. Here, we provide an overview of IL-23 in the context of psoriasis pathogenesis and review the results of the Phase I, II and III clinical trials for tildrakizumab in patients with moderate-to-severe chronic plaque psoriasis in order to assess its efficacy, safety and clinical usefulness. In all clinical trials, tildrakizumab demonstrated significant clinical improvement and a favorable safety profile. In Phase III trials, 75% of tildrakizumab-treated patients reached a Psoriasis Area and Severity Index 75 at week 28 demonstrating superior efficacy as compared with etanercept treatment. The tildrakizumab-induced reduction in skin inflammation proves the important pathogenic role of IL-23 in psoriasis and further supports the utility of drugs targeting the IL-23/Th17 pathway. Targeting IL-23p19 with tildrakizumab augments the therapeutic repertoire for patients with moderate-to-severe chronic plaque psoriasis.