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

A mathematical insight to control the disease psoriasis using mesenchymal stem cell transplantation with a biologic inhibitor

Psoriasis is a chronic, non-contagious, immune-mediated skin disorder. Inflammation of the skin's surface is characterised by scaly white, red, or silvery spots that occur due to the hyper-proliferation of keratinocytes in the epidermal layer. Primarily, pharmaceutical drugs or immune therapy are used to treat psoriasis. We are all aware that, certain therapeutic strategies can have some adverse effects, and over time, that hidden inflammation may manifest. This article introduces a mathematical model for psoriasis, formulated by employing a set of nonlinear ordinary differential equations (ODEs) that describe the densities of T-cells, dendritic cells (DCs), keratinocytes, and mesenchymal stromal cells (MSCs) as basic cell populations. A tumor necrosis factor- α ( T N F - α ) inhibitor has been imposed from the initial stage of the treatment regime, using the optimal control theoretic approach, and the numerical results have been observed. After 80 days of monitoring using only biologic T N F - α inhibitors, if this approach did not provide the intended outcomes (when severity arises), stem cells are administered a few times in a pulsed manner as a cell replacement technique in addition to this anti T N F - α medicine. We have observed the combined therapeutic benefit of stem cell replacement with a T N F - α inhibitor from a mathematical point of view. The theoretical analysis and the numerical results revealed that stem cell transplantation, along with a T N F - α inhibitor, is a promising psoriasis treatment option moving forward.

Dysbiosis of pro-inflammatory and anti-inflammatory salivary cytokines during psoriasis providing a therapeutic window and a valuable diagnostic aid in future

The objective of this article is to evaluate the salivary levels of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-2 (IL-2), and IL-10 in patients with active psoriasis and compare them with those in healthy control subjects. This study included 60 subjects who were clinically diagnosed cases with active psoriasis (categorized further into 33 mild to moderate and 27 severe cases based on the Psoriasis Area Severity Index score) and 60 age- and gender-matched healthy control subjects. Levels of TNF-α, IFN-γ, IL-2, and IL-10 in the unstimulated saliva of subjects were determined via enzyme-linked immunosorbent assay (BT Lab). The salivary levels of TNF-α, IFN-γ, and IL-2 were significantly higher, whereas IL-10 concentration was significantly reduced in psoriatic patients in comparison to controls, and the difference increased with the progressing severity of the disease. Assessment of cytokine profiles in psoriasis patients is significant for diagnostic validation and monitoring the disease severity. Saliva offers an alternate, noninvasive, and readily available biological sample for evaluating cytokine levels. Extensive research in this field has been recommended for better scientifically proven conclusions.

Phototherapy for Psoriasis in the Age of Biologics

Phototherapy has utility as a psoriatic therapy, given its relatively high clinical efficacy, low side effect profile, and lower cost compared to newer effective treatments like biologics and small molecules. Phototherapy has shown Psoriasis Area and Severity Index (PASI)-75 and PASI-90 rates comparable to those of biologics and small molecules, with similarly rapid onsets of action, rates of remission, and quality of life scores. Certain patients may particularly benefit from phototherapy, such as those with localized disease or contraindications to systemic immunomodulatory medication. Phototherapy can be more cost-effective than biologics and conveniently administered at home, making it a valuable therapeutic option for the right patient.

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.

Review: A Contemporary, Multifaced Insight into Psoriasis Pathogenesis

Psoriasis is a chronic recurrent inflammatory autoimmune pathology with a significant genetic component and several interferences of immunological cells and their cytokines. The complex orchestration of psoriasis pathogenesis is related to the synergic effect of immune cells, polygenic alterations, autoantigens, and several other external factors. The major act of the IL-23/IL-17 axis, strongly influencing the inflammatory pattern established during the disease activity, is visible as a continuous perpetuation of the pro-inflammatory response and keratinocyte activation and proliferation, leading to the development of psoriatic lesions. Genome-wide association studies (GWASs) offer a better view of psoriasis pathogenic pathways, with approximately one-third of psoriasis's genetic impact on psoriasis development associated with the MHC region, with genetic loci located on chromosome 6. The most eloquent genetic factor of psoriasis, PSORS1, was identified in the MHC I site. Among the several factors involved in its complex etiology, dysbiosis, due to genetic or external stimulus, induces a burst of pro-inflammatory consequences; both the cutaneous and gut microbiome get involved in the psoriasis pathogenic process. Cutting-edge research studies and comprehensive insights into psoriasis pathogenesis, fostering novel genetic, epigenetic, and immunological factors, have generated a spectacular improvement over the past decades, securing the path toward a specific and targeted immunotherapeutic approach and delayed progression to inflammatory arthritis. This review aimed to offer insight into various domains that underline the pathogenesis of psoriasis and how they influence disease development and evolution. The pathogenesis mechanism of psoriasis is multifaceted and involves an interplay of cellular and humoral immunity, which affects susceptible microbiota and the genetic background. An in-depth understanding of the role of pathogenic factors forms the basis for developing novel and individualized therapeutic targets that can improve disease management.

Interleukins and Psoriasis

Psoriasis is an immune-mediated chronic inflammatory skin disease that affects 2% to 3% of the world's population. It is widely assumed that immune cells and cytokines acting together play a crucial part in the pathophysiology of psoriasis by promoting the excessive proliferation of skin keratinocytes and inflammatory infiltration. Interleukins (ILs), as a critical component of cytokines, have been closely associated with the pathogenesis and progression of psoriasis. This review summarizes the current contribution of ILs to psoriasis and describes the role each IL performs in psoriasis. Furthermore, the paper presents the therapeutic effects and application prospects of biologics developed for ILs in clinical treatment and experiments. The study aims to further the research on ILs in the treatment of psoriasis.

Eicosapentaenoic acid reduces the proportion of IL-17A-producing T cells in a 3D psoriatic skin model

Psoriasis is a skin disease presenting as erythematous lesions with accentuated proliferation of epidermal keratinocytes, infiltration of leukocytes, and dysregulated lipid metabolism. T cells play essential roles in the disease. n-3 polyunsaturated fatty acids are anti-inflammatory metabolites, which exert an immunosuppressive effect on healthy T cells. However, the precise mechanistic processes of n-3 polyunsaturated fatty acids on T cells in psoriasis are still unrevealed. In this study, we aimed to evaluate the action of eicosapentaenoic acid (EPA) on T cells in a psoriatic skin model produced with T cells. A coculture of psoriatic keratinocytes and polarized T cells was prepared using culture media, which was either supplemented with 10 μM EPA or left unsupplemented. Healthy and psoriatic skin substitutes were produced according to the self-assembly method. In the coculture model, EPA reduced the proportion of IL-17A-positive cells, while increasing that of FOXP3-positive cells, suggesting an increase in the polarization of regulatory T cells. In the 3D psoriatic skin model, EPA normalized the proliferation of psoriatic keratinocytes and diminished the levels of IL-17A. The expression of the proteins of the signal transducer and activator of transcription was influenced following EPA supplementation with downregulation of the phosphorylation levels of signal transducer and activator of transcription 3 in the dermis. Finally, the NFκB signaling pathway was modified in the EPA-supplemented substitutes with an increase in Fas amounts. Ultimately, our results suggest that in this psoriatic model, EPA exerts its anti-inflammatory action by decreasing the proportion of IL-17A-producing T cells.

Obesity-induced dysregulation of skin-resident PPARγ+ Treg cells promotes IL-17A-mediated psoriatic inflammation

Obesity is a major risk factor for psoriasis, but how obesity disrupts the regulatory mechanisms that keep skin inflammation in check is unclear. Here, we found that skin was enriched with a unique population of CD4+Foxp3+ regulatory T (Treg) cells expressing the nuclear receptor peroxisome proliferation-activated receptor gamma (PPARγ). PPARγ drove a distinctive transcriptional program and functional suppression of IL-17A+ γδ T cell-mediated psoriatic inflammation. Diet-induced obesity, however, resulted in a reduction of PPARγ+ skin Treg cells and a corresponding loss of control over IL-17A+ γδ T cell-mediated inflammation. Mechanistically, PPARγ+ skin Treg cells preferentially took up elevated levels of long-chain free fatty acids in obese mice, which led to cellular lipotoxicity, oxidative stress, and mitochondrial dysfunction. Harnessing the anti-inflammatory properties of these PPARγ+ skin Treg cells could have therapeutic potential for obesity-associated inflammatory skin diseases.

Low-Intensity Physical Exercise Decreases Inflammation and Joint Damage in the Preclinical Phase of a Rheumatoid Arthritis Murine Model

Lifestyle modifications in preclinical Rheumatoid Arthritis (RA) could delay the ongoing pathogenic immune processes and potentially prevent its onset. Physical exercise (PE) benefits RA patients; however, its impact in reducing the risk of developing RA has scarcely been studied. The objective was to describe the effects of low-intensity PE applied at the disease’s preclinical phase on the joints of DBA/1 mice with collagen-induced arthritis (CIA). Twelve mice with CIA were randomly distributed into two groups: the CIA-Ex group, which undertook treadmill PE, and the CIA-NoEx, which was not exercised. The effects of PE were evaluated through clinical, histological, transcriptomics, and immunodetection analyses in the mice’s hind paws. The CIA-Ex group showed lower joint inflammation and damage and a decreased expression of RA-related genes (Tnf Il2, Il10, Il12a, IL23a, and Tgfb1) and signaling pathways (Cytokines, Chemokines, JAK-STAT, MAPK, NF-kappa B, TNF, and TGF-beta). TNF-α expression was decreased by PE in the inflamed joints. Low-intensity PE in pre-arthritic CIA reduced the severity through joint down-expression of proinflammatory genes and proteins. Knowledge on the underlying mechanisms of PE in preclinical arthritis and its impact on reducing the risk of developing RA is still needed.

Development and function of tissue-resident memory B cells

Barrier tissues are the primary site of infection for pathogens likely to cause future pandemics. Tissue-resident lymphocytes can rapidly detect pathogens upon infection of barrier tissues and are critical in preventing viral spread. However, most vaccines fail to induce tissue-resident lymphocytes and are instead reliant on circulating antibodies to mediate protective immunity. Circulating antibody titers wane over time following vaccination leaving individuals susceptible to breakthrough infections by variant viral strains that evade antibody neutralization. Memory B cells were recently found to establish tissue residence following infection of barrier tissues. Here, we summarize emerging evidence for the importance of tissue-resident memory B cells in the establishment of protective immunity against viral and bacterial challenge. We also discuss the role of tissue-resident memory B cells in regulating the progression of non-infectious diseases. Finally, we examine new approaches to develop vaccines capable of eliciting barrier immunity.

Differential genotypes of TNF-α and IL-10 for immunological diagnosis in discoid lupus erythematosus and oral lichen planus: A narrative review

Discoid lupus erythematosus and oral lichen planus are chronic systemic immune system-mediated diseases with unclear etiology and pathogenesis. The oral mucosa is the common primary site of pathogenesis in both, whereby innate and adaptive immunity and inflammation play crucial roles. The clinical manifestations of discoid lupus erythematosus on the oral mucosa are very similar to those of oral lichen planus; therefore, its oral lesion is classified under oral lichenoid lesions. In practice, the differential diagnosis of discoid lupus erythematosus and oral lichen planus has always relied on the clinical manifestations, with histopathological examination as an auxiliary diagnostic tool. However, the close resemblance of the clinical manifestations and histopathology proves challenging for accurate differential diagnosis and further treatment. In most cases, dentists and pathologists fail to distinguish between the conditions during the early stages of the lesions. It should be noted that both are considered to be precancerous conditions, highlighting the significance of early diagnosis and treatment. In the context of unknown etiology and pathogenesis, we suggest a serological and genetic diagnostic method based on TNF-α and IL-10. These are the two most common cytokines produced by the innate and adaptive immune systems and they play a fundamental role in maintaining immune homeostasis and modulating inflammation. The prominent variability in their expression levels and gene polymorphism typing in different lesions compensates for the low specificity of current conventional diagnostic protocols. This new diagnostic scheme, starting from the immunity and inflammation of the oral mucosa, enables simultaneous comparison of discoid lupus erythematosus and oral lichen planus. With relevant supportive evidence, this information can enhance physicians’ understanding of the two diseases, contribute to precision medicine, and aid in prevention of precancerous conditions.

Immune Inhibitory Properties and Therapeutic Prospects of Transforming Growth Factor-Beta and Interleukin 10 in Autoimmune Hepatitis

Transforming growth factor-beta and interleukin 10 have diverse immune inhibitory properties that have restored homeostatic defense mechanisms in experimental models of autoimmune disease. The goals of this review are to describe the actions of each cytokine, review their investigational use in animal models and patients, and indicate their prospects as interventions in autoimmune hepatitis. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Transforming growth factor-beta expands the natural and inducible populations of regulatory T cells, limits the proliferation of natural killer cells, suppresses the activation of naïve CD8⁺ T cells, decreases the production of interferon-gamma, and stimulates fibrotic repair. Interleukin 10 selectively inhibits the CD28 co-stimulatory signal for antigen recognition and impairs antigen-specific activation of uncommitted CD4⁺ and CD8⁺ T cells. It also inhibits maturation of dendritic cells, suppresses Th17 cells, supports regulatory T cells, and limits production of diverse pro-inflammatory cytokines. Contradictory immune stimulatory effects have been associated with each cytokine and may relate to the dose and accompanying cytokine milieu. Experimental findings have not translated into successful early clinical trials. The recombinant preparation of each agent in low dosage has been safe in human studies. In conclusion, transforming growth factor-beta and interleukin 10 have powerful immune inhibitory actions of potential therapeutic value in autoimmune hepatitis. The keys to their therapeutic application will be to match their predominant non-redundant function with the pivotal pathogenic mechanism or cytokine deficiency and to avoid contradictory immune stimulatory actions.

CD4+ T-cell-derived IL-10 promotes CNS inflammation in mice by sustaining effector T cell survival

Interleukin (IL)-10 is considered a prototypical anti-inflammatory cytokine, significantly contributing to the maintenance and reestablishment of immune homeostasis. Accordingly, it has been shown in the intestine that IL-10 produced by Tregs can act on effector T cells, thereby limiting inflammation. Herein, we investigate whether this role also applies to IL-10 produced by T cells during central nervous system (CNS) inflammation. During neuroinflammation, both CNS-resident and -infiltrating cells produce IL-10; yet, as IL-10 has a pleotropic function, the exact contribution of the different cellular sources is not fully understood. We find that T-cell-derived IL-10, but not other relevant IL-10 sources, can promote inflammation in experimental autoimmune encephalomyelitis. Furthermore, in the CNS, T-cell-derived IL-10 acts on effector T cells, promoting their survival and thereby enhancing inflammation and CNS autoimmunity. Our data indicate a pro-inflammatory role of T-cell-derived IL-10 in the CNS.

Genetic variants affecting chemical mediated skin immunotoxicity

The skin is an immune-competent organ and this function may be impaired by exposure to chemicals, which may ultimately result in immune-mediated dermal disorders. Interindividual variability to chemical-induced skin immune reactions is associated with intrinsic individual characteristics and their genomes. In the last 30-40 years, several genes influencing susceptibility to skin immune reactions were identified. The aim of this review is to provide information regarding common genetic variations affecting skin immunotoxicity. The polymorphisms selected for this review are related to xenobiotic-metabolizing enzymes (CYPA1 and CYPB1 genes), antioxidant defense (GSTM1, GSTT1, and GSTP1 genes), aryl hydrocarbon receptor signaling pathway (AHR and ARNT genes), skin barrier function transepidermal water loss (FLG, CASP14, and SPINK5 genes), inflammation (TNF, IL10, IL6, IL18, IL31, and TSLP genes), major histocompatibility complex (MHC) and neuroendocrine system peptides (CALCA, TRPV1, ACE genes). These genes present variants associated with skin immune responses and diseases, as well as variants associated with protecting skin immune homeostasis following chemical exposure. The molecular and association studies focusing on these genetic variants may elucidate their functional consequences and contribution in the susceptibility to skin immunotoxicity. Providing information on how genetic variations affect the skin immune system may reduce uncertainties in estimating chemical hazards/risks for human health in the future.

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.

Gut and Cutaneous Microbiome Featuring Abundance of Lactobacillus reuteri Protected Against Psoriasis-Like Inflammation in Mice

Background

Psoriasis is a chronic autoinflammatory skin disease, and its aetiology remains incompletely understood. Recently, gut microbial dysbiosis is found to be tightly associated with psoriasis.

Objective

We sought to reveal the causal role of gut microbiota dysbiosis in psoriasis pathogenesis and investigate the protective effect of healthy commensal bacteria against imiquimod -induced psoriasis-like skin response.

Methods

By using fecal microbial transplantation (FMT), 16S rRNA gene-based taxonomic profiling and Lactobacillus supplement, we have assessed the effect of FMT from healthy individuals on psoriasis-like skin inflammation and associated immune disorders in imiquimod-induced psoriasis mice.

Results

Here, by using psoriasis mice humanized with the stools from healthy donors and psoriasis patients, the imiquimod-induced psoriasis in mice with psoriasis patient stool was found to be significantly aggravated as compared to the mice with healthy donor stools. Further analysis showed fecal microbiota of healthy individuals protected against Treg/Th17 imbalance in psoriasis. Moreover, we found the gut and skin microbiome in mice receipted with gut microbiota of healthy individuals (HD) differed from those of mice receipted with gut microbiota of psoriasis patients (PSD). 16S rRNA sequencing revealed that Lactobacillus reuteri was greatly enriched in fecal and cutaneous microbiome of HD mice as compared to PSD mice. Intriguingly, supplement with Lactobacillus reuteri was sufficient to increase the expression of anti-inflammatory gene IL-10, reduce Th17 cells counts and confer resistance to imiquimod-induced inflammation on the mice with gut microbiota dysbiosis.

Conclusion

Our results suggested that the gut microbiota dysbiosis is the potential causal factor for psoriasis and the gut microbiota may serve as promising therapy target for psoriasis patients.

Inflammation: A Mediator Between Hypertension and Neurodegenerative Diseases

Hypertension is the most prevalent and modifiable risk factor for stroke, vascular cognitive impairment, and Alzheimer's disease. However, the mechanistic link between hypertension and neurodegenerative diseases remains to be understood. Recent evidence indicates that inflammation is a common pathophysiological trait for both hypertension and neurodegenerative diseases. Low-grade chronic inflammation at the systemic and central nervous system levels is now recognized to contribute to the physiopathology of hypertension. This review speculates that inflammation represents a mediator between hypertension and neurodegenerative diseases, either by a decrease in cerebral blood flow or a disruption of the blood-brain barrier which will, in turn, let inflammatory cells and neurotoxic molecules enter the brain parenchyma. This may impact brain functions including cognition and contribute to neurodegenerative diseases. This review will thus discuss the relationship between hypertension, systemic inflammation, cerebrovascular functions, neuroinflammation, and brain dysfunctions. The potential clinical future of immunotherapies against hypertension and associated cerebrovascular risks will also be presented.

Interleukin-17A Drives IL-19 and IL-24 Expression in Skin Stromal Cells Regulating Keratinocyte Proliferation

IL-17A has been shown to be up-regulated in psoriasis lesions and is central to psoriasis pathogenesis. IL-19, along with other IL-20 subfamily cytokines such as IL-20 and IL-24, is induced by IL-17A and contributes especially to epidermal hyperplasia in psoriasis. However, the regulation, cellular sources of IL-19 and whether targeting of IL-17A by biologics influence IL-19 expression is not completely understood. To investigate the regulation of IL-19 by IL-17A in psoriasis, the imiquimod-induced psoriasis mouse (IMQ) model was used. Enhanced expression of IL-17A in the IMQ model was achieved by anti-IL-10 antibody treatment. Assessments of skin inflammation macroscopically, by histology and flow cytometry, all confirmed increased psoriatic symptoms. Interestingly, depletion of IL-10 markedly upregulated IL-23/IL-17 pathway related cytokines followed by a significant increase in IL-19 and IL-24. The up-regulation of IL-19 and IL-24, but not IL-17A, coincided with increased keratinocyte proliferation. To investigate the cellular source and effects of biologics on IL-19, human skin fibroblasts from healthy controls and psoriasis patients were cultured alone or co-cultured with activated memory CD4+ T cells. Besides IL-1β, IL-17A induced direct expression of IL-19 and IL-24 in skin fibroblasts and keratinocytes. Importantly, intrinsic higher expression of IL-19 in psoriatic skin fibroblasts was observed in comparison to healthy skin fibroblasts. Neutralization of IL-17A in the human skin fibroblast-T cell co-culture system significantly suppressed IL-19 and IL-24 expression. Together, our data show that IL-17A-induced IL-19 and IL-24 expression in skin stromal cells contribute to keratinocyte proliferation.

Immunotherapy in psoriasis

Over the past two decades, significant progress has been achieved in the treatment of psoriasis by targeting the human cytokine network. At present, 11 biologicals - antibodies, and a soluble receptor - are used to neutralize key inflammatory cytokines. Based on their targets, they can be grouped into the following four classes: TNF-α-, IL-12/23-, IL-17- and IL-23-inhibitors. The range of available substances, as well as their different modes of action can be challenging when selecting the right drug for an individual patient. In this article, we provide an overview of the approved biologicals for the treatment of psoriasis, including their advantages and limitations, and summarize criteria for therapy selection.

Indoleamine 2,3-Dioxygenase 2 Deficiency Exacerbates Imiquimod-Induced Psoriasis-Like Skin Inflammation

Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme known to suppress immune responses, and several reports have showed that it is associated with psoriasis. IDO2 is an isoform of IDO1, recently identified as a catalytic enzyme in the tryptophan-kynurenine pathway, which is expressed in dendritic cells and monocytes. The expression of IDO2 in immune cells suggests that IDO2 may contribute to immune functions. However, the role of IDO2 in the pathogenesis of psoriasis remains unclear. In this study, to elucidate the role of IDO2 in psoriasis, we assessed imiquimod (IMQ)-induced psoriasis-like dermatitis in IDO2 knockout (KO) mice. Skin inflammation, evaluated by scoring erythema, scaling, and ear thickness, was significantly worse in the IDO2 KO mice than in the wild-type (WT) mice. The mRNA expression levels of TNF-α, IL-23p19, and IL-17A, key cytokines involved in the development of psoriasis, were also increased in the IDO2 KO mice. Furthermore, immunohistochemistry revealed that the number of Ki67-positive cells in the epidermis and CD4-, CD8-, and IL-17-positive lymphocytes infiltrating the dermis were significantly increased in the IDO2 KO mice. These results suggest that IDO2 might decrease IL-17 expression, thereby resulting in the suppression of skin inflammation in IMQ-induced psoriasis-like dermatitis.

How It Works: The Immunology Underlying Phototherapy

Phototherapeutic modalities induce apoptosis of keratinocytes and immune cells, impact cytokine production, downregulate the IL-23/Th17 axis, and induce regulatory T cells. As in anti-IL-17 or anti-IL-23 antibody treatment, the dual action of phototherapy on skin and the immune system is likely responsible for sustained resolution of lesions in diseases such as psoriasis. In cutaneous T cell lymphoma, phototherapy may function by causing tumor cell apoptosis and eliminating the neoplastic and inflammatory infiltrate. Further research on phototherapeutic mechanisms will help advance, optimize, and refine dermatologic treatments and may open up novel avenues for treatment strategies in dermatology and beyond.

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.

Resident Memory B Cells

In mammals, adaptive immunity is mediated by a broadly diverse repertoire of naive B and T lymphocytes that recirculate between secondary lymphoid organs. Initial antigen exposure promotes lymphocyte clonal expansion and differentiation, including the formation of memory cells. Antigen-specific memory cells are maintained at higher frequencies than their naive counterparts and have different functional and homing abilities. Importantly, a subset of memory cells, known as tissue-resident memory cells, is maintained without recirculating in nonlymphoid tissues, often at barrier surfaces, where they can be reactivated by antigen and rapidly perform effector functions that help protect the tissue in which they reside. Although antigen-experienced B cells are abundant at many barrier surfaces, their characterization as tissue-resident memory B (BRM) cells is not well developed. In this study, we describe the characteristics of memory B cells in various locations and discuss their possible contributions to immunity and homeostasis as bona fide BRM cells.

Current Developments in the Immunology of Psoriasis

Psoriasis is a frequent inflammatory skin disease. Fundamental research on the pathogenesis of psoriasis has substantially increased our understanding of skin immunology, which has helped to introduce innovative and highly effective therapies. Psoriasis is a largely T lymphocyte-mediated disease in which activation of innate immune cells and pathogenic T cells result in skin inflammation and hyperproliferation of keratinocytes. B cells have thus far largely been neglected regarding their role for the pathogenesis of psoriasis. However, recent data shed light on their role in inflammatory skin diseases. Interestingly, interleukin (IL)-10-producing regulatory B cells have been assumed to ameliorate psoriasis. In this review, we will discuss the development of disease, pathogenicity, and current developments in therapeutic options. We describe different roles of T cells, B cells, and cytokines for the immunopathology and disease course of psoriasis.

Skin-Associated B Cells in Health and Inflammation

Traditionally, the skin was believed to be devoid of B cells, and studies of the skin immune system have largely focused on other types of leukocytes. Exciting recent data show that B cells localize to the healthy skin of humans and other mammalian species with likely homeostatic functions in host defense, regulation of microbial communities, and wound healing. Distinct skin-associated B cell subsets drive or suppress cutaneous inflammatory responses with important clinical implications. Localized functions of skin-associated B cell subsets during inflammation comprise Ab production, interactions with skin T cells, tertiary lymphoid tissue formation, and production of proinflammatory cytokines but also include immunosuppression by providing IL-10. In this review, we delve into the intriguing new roles of skin-associated B cells in homeostasis and inflammation.

Title: IL-10-producing T cells and their dual functions

Interleukin (IL)-10 is considered a prototypical anti-inflammatory cytokine, which significantly contributes to the maintenance and reestablishment of immune homeostasis. However, this classical view fails to fully describe the pleiotropic roles of IL-10. Indeed, IL-10 can also promote immune responses, e.g. by supporting B-cell and CD8⁺ T-cell activation. The reasons for these seemingly opposing functions are unclear to a large extent. Recent and previous studies suggest that the cellular source and the microenvironment impact the function of IL-10. However, studies addressing the mechanisms which determine whether IL-10 promotes inflammation or controls it have just begun. This review first summarizes the recent findings on the heterogeneity of IL-10 producing T cells and their impact on the target cells. Finally, we will propose two possible explanations for the dual functions of IL-10.

Adaptive and Innate Immunity in Psoriasis and Other Inflammatory Disorders

Over the past three decades, a considerable body of evidence has highlighted T cells as pivotal culprits in the pathogenesis of psoriasis. This includes the association of psoriasis with certain MHC (HLA) alleles, oligoclonal expansion of T cells in some cases, therapeutic response to T cell-directed immunomodulation, the onset of psoriasis following bone marrow transplantation, or induction of psoriasis-like inflammation by T cells in experimental animals. There is accumulating clinical and experimental evidence suggesting that both autoimmune and autoinflammatory mechanisms lie at the core of the disease. Indeed, some studies suggested antigenic functions of structural proteins, and complexes of self-DNA with cathelicidin (LL37) or melanocytic ADAMTSL5 have been proposed more recently as actual auto-antigens in some cases of psoriasis. These findings are accompanied by various immunoregulatory mechanisms, which we increasingly understand and which connect innate and adaptive immunity. Specific adaptive autoimmune responses, together with our current view of psoriasis as a systemic inflammatory disorder, raise the question of whether psoriasis may have connections to autoimmune or autoinflammatory disorders elsewhere in the body. While such associations have been suspected for many years, compelling mechanistic evidence in support of this notion is still scant. This review sets into context the current knowledge about innate and adaptive immunological processes in psoriasis and other autoimmune or autoinflammatory diseases.

Prolonged Release and Functionality of Interleukin-10 Encapsulated within PLA-PEG Nanoparticles

Inflammation, as induced by the presence of cytokines and chemokines, is an integral part of chlamydial infections. The anti-inflammatory cytokine, interleukin (IL)-10, has been reported to efficiently suppress the secretion of inflammatory cytokines triggered by Chlamydia in mouse macrophages. Though IL-10 is employed in clinical applications, its therapeutic usage is limited due to its short half-life. Here, we document the successful encapsulation of IL-10 within the biodegradable polymeric nanoparticles of PLA-PEG (Poly (lactic acid)-Poly (ethylene glycol), to prolong its half-life. Our results show the encapsulated-IL-10 size (~238 nm), zeta potential (−14.2 mV), polydispersity index (0.256), encapsulation efficiency (~77%), and a prolonged slow release pattern up to 60 days. Temperature stability of encapsulated-IL-10 was favorable, demonstrating a heat capacity of up to 89 °C as shown by differential scanning calorimetry analysis. Encapsulated-IL-10 modulated the release of IL-6 and IL-12p40 in stimulated macrophages in a time- and concentration-dependent fashion, and differentially induced SOCS1 and SOCS3 as induced by chlamydial stimulants in macrophages. Our finding offers the tremendous potential for encapsulated-IL-10 not only for chlamydial inflammatory diseases but also biomedical therapeutic applications.

Betulinic acid suppresses Th17 response and ameliorates psoriasis-like murine skin inflammation

Psoriasis is a common inflammatory skin disease. Current treatment for psoriasis relies on conventional immunosuppressive agents. However, long-term treatment with global immunosuppression may cause various side effects. Thus, it is compelling to seek alternative drugs for treating psoriasis with potentially less side effects. Betulinic acid (BA) is a naturally occurring pentacyclic triterpene, an ingredient that originally exists in natural plants and lacks systemic toxicity. BA can regulate immunity with anti-fibrotic, anti-inflammatory and antioxidant properties. However, it's unknown whether BA has a therapeutic effect on psoriasis. The objectives of this study were to investigate whether BA attenuates psoriatic skin inflammation and to identify its mechanisms of action. A murine model of imiquimod-induced psoriasis was utilized to evaluate skin lesion while flow cytometry, immunohistochemistry, quantitative RT-PCR and Western blotting analyses were performed for immunoassays. We found that BA treatment alleviated psoriatic symptoms and inflammatory skin lesion. BA lowered the PASI scores, decreased epidermal thickness and reduced T cell infiltration in the skin lesion. Moreover, BA reduced the frequency of IL-17A-expressing CD4⁺ and γδ T cells in psoriatic mice, but did not alter CD4⁺FoxP3⁺ Treg frequency. BA also reduced IL-17A production but increased anti-inflammatory cytokine IL-10 level in serum of the psoriatic mice. Furthermore, BA inhibited gene expression of pro-inflammatory mediators in skin lesions, including RORγt, IL-17A, IL-6 and TNFα. Importantly, it suppressed NFκB signaling in the skin lesion. Finally, BA inhibited T cell proliferation and IL-17A production by CD4⁺ T-Cells in vitro. Thus, BA attenuates psoriasis and inhibits Th17 development.

How lifestyle factors and their associated pathogenetic mechanisms impact psoriasis

BACKGROUNDS AND AIMS

Psoriasis is a skin disorder affecting approximately 2-3% of the global population. While research has revealed a strong genetic component, there are few studies exploring the extent to which lifestyle factors influence psoriasis pathogenesis. The aim of this review was to describe the role of lifestyle factors as both a potential cause and treatment for psoriasis. The review also examines the underlying mechanisms through which these lifestyle factors may operate.

METHODS

This narrative review aims to incorporate current knowledge relating to both lifestyle and pathogenetic factors that contribute to and alleviate psoriasis presentation. Studies reporting the effect of an inflammatory diet and potential dietary benefits are reported, as well as insights into the effects of stress, smoking and alcohol, insulin resistance and exercise.

RESULTS

Poor nutrition and low Omega 3 fatty acid intake, likely combined with fat malabsorption caused by gut dysbiosis and systemic inflammation, are associated with psoriasis. The data strongly suggest that improvements to disease severity can be made through dietary and lifestyle interventions and increased physical activity. Less conclusive, although worthy of mention, is the beneficial effect of bile acid supplementation.

CONCLUSIONS

Lifestyle interventions are a promising treatment for psoriasis and its associated co-morbidities. However, gaps and inadequacies exist within the literature, e.g. methodology, absence of a unified scoring system, lack of controlled clinical data and lack of studies without simultaneous usage of biologics or alternative therapies. Future directions should focus on high quality cohort studies and clinical trials.

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.

Probiotic Potential and Safety Evaluation of Enterococcus faecalis OB14 and OB15, Isolated From Traditional Tunisian Testouri Cheese and Rigouta, Using Physiological and Genomic Analysis

Lactic acid bacteria (LAB) strains OB14 and OB15 were isolated from traditional Tunisian fermented dairy products, Testouri cheese and Rigouta, respectively. They were identified as Enterococcus faecalis by the MALDI TOF-MS (matrix assisted laser desorption-ionization time of flight mass spectrometry) biotyper system and molecular assays (species-specific PCR). These new isolates were evaluated for probiotic properties, compared to E. faecalis Symbioflor 1 clone DSM 16431, as reference. The bacteria were found to be tolerant to the harsh conditions of the gastrointestinal tract (acidity and bile salt). They were low to moderate biofilm producers, can adhere to Caco-2/TC7 intestinal cells and strengthen the intestinal barrier through the increase of the transepithelial electrical resistance (TER). Susceptibility to ampicillin, vancomycin, gentamicin and erythromycin has been tested using the broth microdilutions method. The results demonstrated that E. faecalis OB14 and OB15 were sensitive to the clinically important ampicillin (MIC = 1 μg/mL) and vancomycin (MIC = 2 μg/mL) antibiotics. However, Whole Genome Sequencing (WGS) showed the presence of tetracycline resistance and cytolysin genes in E. faecalis OB14, and this led to high mortality of Galleria Mellonella larvae in the virulence test. Hierarchical cluster analysis by MALDI TOF-MS biotyper showed that E. faecalis OB15 was closely related to the E. faecalis Symbioflor 1 probiotic strain than to OB14, and this has been confirmed by WGS using the average nucleotide identity (ANI) and Genome-to-Genome Hybridization similarity methods. According to these results, E. faecalis OB15 seems to be reliable for future development as probiotic, in food or feed industry.

Ghrelin protects against contact dermatitis and psoriasiform skin inflammation by antagonizing TNF-α/NF-κB signaling pathways

Contact dermatitis and psoriasis are skin disorders caused by immune dysregulation, yet much remains unknown about their underlying mechanisms. Ghrelin, a recently discovered novel peptide and potential endogenous anti-inflammatory factor expressed in the epidermis, is involved in skin repair and disease. In this study, we investigated the expression pattern and therapeutic effect of ghrelin in both contact dermatitis and psoriasis mouse models induced by oxazolone (OXA) and imiquimod (IMQ), respectively, and in TNF-α-stimulated RAW264.7 macrophages, NHEKs and skin fibroblasts. Ghrelin expression was reduced in both the OXA-induced contact dermatitis and IMQ-induced psoriasis mouse models. Furthermore, treatment with ghrelin attenuated skin inflammation in both the contact dermatitis and psoriasis mouse models. Mice administered PBS after OXA- or IMQ-induced model generation exhibited typical skin inflammation, whereas ghrelin treatment in these mouse models substantially decreased the dermatitis phenotype. In addition, exogenous ghrelin attenuated the inflammatory reaction induced by TNF-α in RAW264.7 cells. Moreover, ghrelin administration limited activation of NF-κB signaling. In summary, ghrelin may represent a potential molecular target for the prevention and treatment of inflammatory skin diseases, including contact dermatitis and psoriasis.

Targeting IL-10 Family Cytokines for the Treatment of Human Diseases

Members of the interleukin (IL)-10 family of cytokines play important roles in regulating immune responses during host defense but also in autoimmune disorders, inflammatory diseases, and cancer. Although IL-10 itself primarily acts on leukocytes and has potent immunosuppressive functions, other family members preferentially target nonimmune compartments, such as tissue epithelial cells, where they elicit innate defense mechanisms to control viral, bacterial, and fungal infections, protect tissue integrity, and promote tissue repair and regeneration. As cytokines are prime drug targets, IL-10 family cytokines provide great opportunities for the treatment of autoimmune diseases, tissue damage, and cancer. Yet no therapy in this space has been approved to date. Here, we summarize the diverse biology of the IL-10 family as it relates to human disease and review past and current strategies and challenges to target IL-10 family cytokines for clinical use.

Introduction to the Immune System

The immune system in a broad sense is a mechanism that allows a living organism to discriminate between "self" and "nonself." Examples of immune systems occur in multicellular organisms as simple and ancient as sea sponges. In fact, complex multicellular life would be impossible without the ability to exclude external life from the internal environment. This introduction to the immune system will explore the cell types and soluble factors involved in immune reactions, as well as their location in the body during development and maintenance. Additionally, a description of the immunological events during an innate and adaptive immune reaction to an infection will be discussed, as well as a brief introduction to autoimmunity, cancer immunity, vaccines, and immunotherapies.

Splenectomy may have more complications than currently proven

The spleen has been one of the least understood major organs for centuries. Its significance is relatively well-known today but it seems that all aspects of its activities are not fully understood. Persian medicine (PM) has special views on the function of spleen; many side effects were reported in PM due to spleen dysfunction. On the other hand nowadays splenectomy as a treatment strategy is recommended for some disorders and increasing risk of infections is considered as the most important long term side effect of that. In this study, we hypothesize that splenectomy may have more side effects than currently proven. According to PM, spleen is in close connection with liver, cardiovascular system, stomach, bone, brain and skin, and that is why any kind of spleen dysfunction leads to change in blood viscosity, appetite and bone strength, liver dysfunction, mood and skin disorders, cancer formation and fever. Considering this viewpoint it can be hypothesized such side effects may also occur after splenectomy. Proven complications of splenectomy include hypercoagulated state, cardiovascular events and infectious diseases but there is also some evidence about increased risk of cancer, skin disease like systemic lupus erythematosus, mood disorder such as depression, defective bone formation and impairment of immunity which can be considered as different levels of evidence to confirm the hypothesis. But for some others such as changes in appetite, there are no studies let alone convincing evidence. Future research about theses possible complications may lead to novel results.

Variation at Interleukin-10 Locus Represents Susceptibility to Psoriasis in North Indian Population

BACKGROUND

IL-10 is an important pleiotropic, immunoregulatory and anti-inflammatory cytokine which plays a significant role in the pathogenesis of psoriasis.

OBJECTIVE

The aim of the present study was to determine whether the three polymorphic sites of the IL-10 gene, haplotype and serum level confer susceptibility to psoriasis.

METHOD

200 psoriatic patients and 200 controls were genotyped for three IL-10 polymorphic sites by ARMS polymerase chain reaction. Serum levels of IL -10 were measured by ELISA.

RESULTS

Our results demonstrated that polymorphism of IL-10 -592 C/A (adjusted* OR = 9.25; 95% CI =3.16- 27.06) and IL-10 1082 A/G (adjusted* OR = 4.28; (95% CI =1.46- 12.56) was found to be in association with increased risk of psoriasis while as IL- 10 819 C/T (adjusted* OR= 1.60; (95% CI = 0.65-3.95) polymorphism does not show any significant association with the risk of psoriasis. HT7 GTC haplotype is associated with increased risk of psoriasis. Serum levels of IL-10 were found to be significantly low in patients, as compared to controls with a non-significant correlation between serum IL-10 level and psoriasis severity.

CONCLUSION

IL-10 polymorphism imparted significant risk towards the development of psoriasis in North Indian population. Highlighting the role of IL-10 cytokine in the pathogenesis of psoriasis will help in the development of psoriasis management.

The Interleukin-23/Interleukin-17 Axis Links Adaptive and Innate Immunity in Psoriasis

Research into the pathophysiology of psoriasis has shed light onto many fascinating immunological interactions and underlying genetic constellations. Most prominent among these is the crosstalk between components of the innate and the adaptive immune system and the crucial role of interleukins (IL)-23 and -17 within this network. While it is clear that IL-23 drives and maintains the differentiation of Th17 lymphocytes, many aspects of the regulation of IL-23 and IL-17 are not quite as straightforward and have been unraveled only recently. For example, we know now that Th17 cells are not the only source of IL-17 but that cells of the innate immune system also produce considerable amounts of this central effector cytokine. In addition, there is IL-23-independent production of IL-17. Besides other innate immune cells, neutrophilic granulocytes prominently contribute to IL-17-related immune regulations in psoriasis, and it appears that they employ several mechanisms including the formation of neutrophil extracellular traps. Here, we strive to put the central role of the IL-23/IL-17 axis into perspective within the crosstalk between components of the innate and the adaptive immune system. Our aim is to better understand the complex immune regulation in psoriasis, a disorder that has become a model disease for chronic inflammation.

APVO210: A Bispecific Anti-CD86-IL-10 Fusion Protein (ADAPTIR™) to Induce Antigen-Specific T Regulatory Type 1 Cells

IL-10 is a potent immunosuppressive cytokine that promotes the differentiation of tolerogenic dendritic cells (DC-10), and the subsequent induction of antigen-specific T regulatory type 1 (Tr1) cells, which suppress immune responses. However, IL-10 acts on multiple cell types and its effects are not solely inhibitory, therefore, limiting its use as immunomodulant. APVO210 is a bispecific fusion protein composed of an anti-CD86 antibody fused with monomeric IL-10 (ADAPTIR™ from Aptevo Therapeutics). APVO210 specifically induces IL-10R signaling in CD86⁺ antigen-presenting cells, but not in T and B cells. In this study, we tested whether APVO210 promotes the differentiation of tolerogenic DC-10 and the differentiation of antigen-specific CD4⁺ Tr1 cells in vitro. We compared the effect of APVO210 with that of recombinant human (rh) IL-10 on the in vitro differentiation of DC-10, induction of alloantigen-specific anergic CD4⁺ T cells, enrichment in CD49b⁺LAG3⁺ Tr1 cells mediating antigen-specific suppression, and stability upon exposure to inflammatory cytokines. APVO210 induced the differentiation of tolerogenic DC (DC-A210) that produced high levels of IL-10, expressed CD86, HLA-G, and intermediate levels of CD14 and CD16. These DC-A210 induced alloantigen-specific anergic T-cell cultures (T-alloA210) that were enriched in CD49b⁺ LAG3⁺ Tr1 cells, produced high levels of IL-10, and had suppressive properties. The phenotype and high IL-10 production by DC-A210, and the alloantigen-specific anergy of T-alloA210 were preserved upon exposure to the inflammatory cytokines IL-1β, IL-6, and TNF-α. The effects of APVO210 were comparable to that of dimeric rh IL-10. In conclusion, our data demonstrate that APVO210 drives the differentiation of tolerogenic DC and functional alloantigen-specific Tr1 cells in vitro. Since APVO210 specifically targets CD86⁺ cells, we hypothesize that it will specifically target CD86⁺ DC to induce Tr1 cells in vivo, and mediate antigen-specific immunological tolerance by induction of tolerogenic DC and Tr1 cells.

Elevated Gene Expression of Interleukin-32 Isoforms Alpha, Beta, Gamma, and Delta in the Peripheral Blood of Chronic Psoriatic Patients

Inflammatory-mediated reactions have been implicated as contributors in a number of dermatological disorders, including psoriasis. However, the potential of interleukin (IL)-32 and its isoforms to contribute to the pathogenesis of psoriasis remains unexplored. This study was undertaken to investigate the role of IL-32 and its isoforms IL-32α, IL-32β, IL-32γ, and IL-32δ in the peripheral blood of psoriatic patients. The majority of chronic plaque psoriatic patients showed elevated IL-32 mRNA levels in the peripheral blood mononuclear cells (PBMCs) as compared with the levels of IL-32 mRNA in PBMCs of healthy controls (p = 0.001). To further investigate the role of elevated levels of IL-32 in psoriatic patients, IL-32 isoforms mRNAs were determined. All tested isoforms IL-32α, IL-32β, IL-32γ, and IL-32δ were overexpressed in psoriatic patients PBMCs as compared with healthy controls’ PBMCs (p < 0.05). IL-32α mRNA expression was also significantly higher as compared with all other isoforms of IL-32 in PBMCs of psoriatic patients (p < 0.001). In short, this is the first study that shows the role of IL-32 and its isoforms in the peripheral blood of psoriatic patients. Our novel findings support an association between elevated levels of IL-32 and psoriasis. The data also suggest that a major proinflammatory response of IL-32 may derive from IL-32α isoform in psoriasis.

Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?

Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis.

Scanning the Immunopathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease, the immunologic model of which has been profoundly revised following recent advances in the understanding of its pathophysiology. In the current model, a crosstalk between keratinocytes, neutrophils, mast cells, T cells, and dendritic cells is thought to create inflammatory and pro-proliferative circuits mediated by chemokines and cytokines. Various triggers, including recently identified autoantigens, Toll-like receptor agonists, chemerin, and thymic stromal lymphopoietin may activate the pathogenic cascade resulting in enhanced production of pro-inflammatory and proliferation-inducing mediators such as interleukin (IL)-17, tumor necrosis factor (TNF)-α, IL-23, IL-22, interferon (IFN)-α, and IFN-γ by immune cells. Among these key cytokines lie therapeutic targets for currently approved antipsoriatic therapies. This review aims to provide a comprehensive overview on the immune-mediated mechanisms characterizing the current pathogenic model of psoriasis.

Prevalence of antigliadin IgA antibodies in psoriasis vulgaris and response of seropositive patients to a gluten-free diet

Introduction

The course of psoriasis relies on a variety of metabolic and immunological parameters. Identification of underlying pro-inflammatory conditions and their control is desired for optimal management.

Background

Increased prevalence of serum markers for celiac disease has been reported among patients with psoriasis. The likelihood of occult celiac disease in a subpopulation of patients has been postulated and gluten-free diets have been reported to be effective.

Patients and methods

The prevalence of gliadin IgA antibodies was assessed among patients with psoriasis in an urban population. The clinical effects of a strict gluten-free diet were followed.

Results

Over a 2-year period, 97 patients with Psoriasis Area and Severity Index greater than 2.4 were recruited from a population followed in a dermatology clinic. Gliadin IgA antibodies were assessed in all participants and in 91 controls. Elevated gliadin IgA antibodies were found in 13 patients (14%) and two controls (2%). Values in five patients were assessed as greater than 30.0 U/mL or “strong positive” according to the manufacturer of the assay. All 13 patients were placed on a strict gluten-free diet without any other modifications in their ongoing treatment of psoriasis. Improvement of psoriatic lesions was observed in all patients with positive gliadin IgA antibodies but the decline in the Psoriasis Area and Severity Index score and the scaling down of pharmaceutical treatment was more pronounced in the five patients with strong positive gliadin IgA indicating an immune aberration amenable to diet changes.

Conclusion

Prevalence of antigliadin IgA antibody is significant among patients with psoriasis not diagnosed with celiac disease or non-celiac gluten sensitivity. For all its limitations, antigliadin IgA testing can identify patients likely to benefit from gluten-free diets.

Anti-interleukin and interleukin therapies for psoriasis: current evidence and clinical usefulness

Anti-interleukin (IL) therapies have emerged as a major treatment for patients with moderate-to-severe psoriasis. This article reviews the up-to-date results of pivotal clinical trials targeting the interleukins used for the treatment of psoriasis, including IL-1, IL-2, IL-6, IL-8, IL-10, IL-12, IL-17, IL-20, IL-22, IL-23, IL-36 and bispecific biologics IL-17A/tumor necrosis factor alpha (TNF-α). Cytokines involved in the circuits of psoriasis inflammation without ongoing clinical trials are also mentioned (IL-9, IL-13, IL-15, IL-16, IL-18, IL-19, IL-21, IL-24, IL-27, IL-33, IL-35, IL-37, and IL-38).

Imiquimod-applied Interleukin-10 deficient mice better reflects severe and persistent psoriasis with systemic inflammatory state

Previous studies have shown that imiquimod-induced psoriasis-like skin inflammation in mice resembles phenotypic changes and cytokine profiles of human psoriasis. However, a psoriasis animal model reflecting the chronic inflammatory course and comorbidities has not yet been established. We aimed to evaluate the imiquimod-applied interleukin (IL)-10 deficient mouse model in comparison with previous models. IL-10 deficient and wild-type (WT) mice received either imiquimod or vehicle cream for 12 days and were sacrificed on day 15. For earlier time point data, either imiquimod or vehicle cream was applied for 2 days, and the mice were sacrificed on day 3. Imiquimod-applied IL-10 deficient mice showed more persistent psoriasis-like inflammation and higher severity index than did WT between day 8 and 15. Histopathologically, they demonstrated significantly thicker epidermis and larger number of CD45+, myeloperoxidase+ and IL-17+ cell counts on day 15. Quantitative reverse transcription-polymerase chain reaction with skin tissue revealed significantly higher imiquimod-induced IL-23p19 expression in imiquimod-applied IL-10 deficient mice on day 15. IL-10 deficient mice also showed significantly higher serum levels of imiquimod-induced IL-17A and tumor necrosis factor-α by enzyme-linked immunosorbent assay on day 15. Furthermore, IL-10 deficient mice showed more prominent increase of spleen weight and decrease of body weight in response to imiquimod application on day 3 and 15. In conclusion, IL-10 deficient mice model with imiquimod application may better reflect severe and persistent psoriasis with systemic inflammatory state.

Immune modulation by curcumin: The role of interleukin-10

Cytokines are small secreted proteins released by different types of cells with specific effects on cellular signaling and communication via binding to their receptors on the cell surface. IL-10 is known to be a pleiotropic and potent anti-inflammatory and immunosuppressive cytokine that is produced by both innate and adaptive immunity cells including dendritic cells, macrophages, mast cells, natural killer cells, eosinophils, neutrophils, B cells, CD8⁺ T cells, and T_H1, T_H2, and T_H17 and regulatory T cells. Both direct and indirect activation of the stress axis promotes IL-10 secretion. IL-10 deregulation plays a role in the development of a large number of inflammatory diseases such as neuropathic pain, Parkinson's disease, Alzheimer's disease, osteoarthritis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus, type 1 diabetes, inflammatory bowel disease, and allergy. Curcumin is a natural anti-inflammatory compound able to induce the expression and production of IL-10 and enhancing its action on a large number of tissues. In vitro and in pre-clinical models curcumin is able to modulate the disease pathophysiology of conditions such as pain and neurodegenerative diseases, bowel inflammation, and allergy, but also of infections and cancer through its effect on IL-10 secretion. In humans, at least one part of the positive effects of curcumin on health could be related to its ability to enhance IL-10 -mediated effects.