IL-17 and IL-22 mediate IL-20 subfamily cytokine production in cultured keratinocytes via increased IL-22 receptor expression

"Input/output cytokines" in epidermal keratinocytes and the involvement in inflammatory skin diseases

Considering the role of epidermal keratinocytes, they occupy more than 90% of the epidermis, form a physical barrier, and also function as innate immune barrier. For example, epidermal keratinocytes are capable of recognizing various cytokines and pathogen-associated molecular pattern, and producing a wide variety of inflammatory cytokines, chemokines, and antimicrobial peptides. Previous basic studies have shown that the immune response of epidermal keratinocytes has a significant impact on inflammatory skin diseases. The purpose of this review is to provide foundation of knowledge on the cytokines which are recognized or produced by epidermal keratinocytes. Since a number of biologics for skin diseases have appeared, it is necessary to fully understand the relationship between epidermal keratinocytes and the cytokines. In this review, the cytokines recognized by epidermal keratinocytes are specifically introduced as "input cytokines", and the produced cytokines as "output cytokines". Furthermore, we also refer to the existence of biologics against those input and output cytokines, and the target skin diseases. These use results demonstrate how important targeted cytokines are in real skin diseases, and enhance our understanding of the cytokines.

IL-22 as a target for therapeutic intervention: Current knowledge on its role in various diseases

IL-22 has emerged as a crucial cytokine mediating protective response against pathogens and tissue regeneration. Dysregulated production of IL-22 has been shown to play a pivotal role in the pathogenesis of various diseases like malignant tumours, viral, cardiovascular, allergic and autoimmune disorders. Interleukin 22 belongs to IFN-IL-10 cytokine family. It is a major proinflammatory cytokine secreted by activated Th1 cells (Th22), though can also be secreted by many other immune cells like group 3 innate lymphocytes, γδ T cells, NK cells, NK T cells, and mucosal associated invariant T cells. Th22 cells exclusively release IL-22 but not IL-17 or IFN-γ (as Th1 cells releases IFN-γ along with IL-22 and Th17 cells releases IL-17 along with IL-22) and also express aryl hydrocarbon receptor as the key transcription factor. Th22 cells also exhibit expression of chemokine receptor CCR6 and skin-homing receptors CCR4 and CCR10 indicating the involvement of this subset in bolstering epithelial barrier immunity and promoting secretion of antimicrobial peptides (AMPs) from intestinal epithelial cells. The function of IL-22 is modulated by IL-22 binding protein (binds to IL-22 and inhibits it binding to its cell surface receptor); which serves as a competitor for IL-22R1 chain of IL-22 receptor. The pathogenic and protective nature of the Th22 cells is modulated both by the site of infected tissue and the type of disease pathology. This review aims to discuss key features of IL-22 biology, comparisons between IL and 22 and IFN-γ and its role as a potential immune therapy target in different maladies.

Recent advances in understanding inflammatory acne: Deciphering the relationship between Cutibacterium acnes and Th17 inflammatory pathway

Acne vulgaris is a common chronic inflammatory skin disease of the pilosebaceous units. Four factors contribute to acne: hyperseborrhea and dysseborrhea, follicular hyperkeratinisation, skin microbiome dysbiosis and local immuno-inflammation. Recent key studies have highlighted a better understanding of the important role of Cutibacterium acnes (C. acnes) in the development of acne. Three major findings in the last decade include: (1) the ability of C. acnes to self-organize in a biofilm associated with a more virulent activity, (2) the loss of the C. acnes phylotype diversity and (3) the central role of the Th17 pathway in acne inflammation. Indeed, there is a close link between C. acnes and the activation of the Th17 immuno-inflammatory pathway at the initiation of acne development. These mechanisms are directly linked to the loss of C. acnes phylotype diversity during acne, with a predominance of the pro-pathogenic phylotype IA1. This specifically contributes to the induction of the Th17-mediated immuno-inflammatory response involving skin cells, such as keratinocytes, monocytes and sebocytes. These advancements have led to new insights into the underlying mechanisms which can be harnessed to develop novel treatments and diagnostic biomarkers. A major disadvantage of traditional treatment with topical antibiotics is that they induce cutaneous dysbiosis and antimicrobial resistance. Thus, future treatments would no longer aim to 'kill' C. acnes, but to maintain the skin microbiota balance allowing for tissue homeostasis, specifically, the restoration of C. acnes phylotype diversity. Here, we provide an overview of some of the key processes involved in the pathogenesis of acne, with a focus on the prominent role of C. acnes and the Th17-inflammatory pathways involved.

Combined application of dinitrofluorobenzene and ovalbumin induced AD-like dermatitis with an increase in helper T-cell cytokines and a prolonged Th2 response

BACKGROUND

The progression of acute-to-chronic atopic dermatitis is accompanied by multiple helper T-cell cytokine responses, but the mechanisms and relative importance of these changes remain unclear. There is no animal model for atopic dermatitis that recapitulates these cytokine responses.

OBJECTIVE

We sought to build a novel mouse model for atopic dermatitis (AD) that recapitulates these helper T-cell responses and some dynamic changes in cytokine responses in the progression of AD.

METHODS

Female BALB/c mice were subjected to the application of dinitrofluorobenzene (DNFB) and ovalbumin (OVA) to induce AD-like dermatitis. Skin lesions and serum were collected from mice in the acute and chronic phases to detect changes in cytokine responses and other features of AD.

RESULTS

Combined application of DNFB and OVA successfully induced AD-like dermatitis and histological changes as well as epidermal barrier dysfunction. In the acute phase of AD-like dermatitis, Th2-associated cytokines were mainly increased in serum and skin lesions. In the chronic phase of AD-like dermatitis, Th2-associated cytokines were still highly expressed, while Th1- and Th17-associated cytokines were also gradually increased. Compared with the acute phase, the JAK-STAT signaling pathway was highly expressed in the chronic phase of AD-like dermatitis.

CONCLUSION

The combined application of DNFB and OVA could be used to build a new mouse model for atopic dermatitis. This mouse model recapitulates the helper T-cell responses and some dynamic changes in cytokine responses in the progression of acute-to-chronic in human AD. The JAK-STAT signaling pathway plays a pivotal role in the chronicity of AD.

The IL-20RB receptor and the IL-20 signaling pathway in regulating host defense in oral mucosal candidiasis

Pseudomembranous candidiasis (thrush), erythematous candidiasis, and fungal esophagitis are infections of the barrier mucosa of the upper gastrointestinal tract. The majority of these infections are caused by Candida albicans, an opportunistic fungal pathogen that frequently exists as a harmless commensal on mucosal surfaces lining the gastrointestinal tract. Oral infections are initiated in the superficial stratified squamous epithelium, in which keratinocytes are the most abundant host cells and are the initial points of contact with C. albicans present in saliva. Intrinsic features of oral keratinocytes are likely to play important roles in host defense and tissue homeostasis in oral candidiasis. One understudied pathway that may be important for modulating oral candidiasis is the IL-20 cytokine signaling pathway that employs keratinocyte IL-20RB receptors as ligands for IL-19, IL-20, and IL-24. We report that production of human oral keratinocyte il24 mRNA and protein are stimulated during co-culture with C. albicans. To test the role of the IL-20 family signaling pathway in oral candidiasis, Il20rb^-/- mice (lacking the IL-20RB receptor) were compared to wild-type mice in a murine model of oropharyngeal candidiasis. Fungal burdens and percent loss in body weight were determined. Despite comparable fungal burdens, the Il20rb^-/- mice exhibited less weight loss over the course of their infection compared to the B6 mice, suggestive of reduced overall disease consequences in the mutant mice. Interference with IL-20 family cytokine signaling may be useful for augmenting the ability of the host to defend itself against pathogens.

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-20 promotes cutaneous inflammation and peripheral itch sensation in atopic dermatitis

Atopic dermatitis (AD) is a chronic skin disease, which is associated with intense itch, skin barrier dysfunction and eczematous lesions. Aberrant IL‐20 expression has been implicated in numerous inflammatory diseases, including psoriasis. However, the role of IL‐20 in AD remains unknown. Here, RNA‐seq, Q‐PCR, and immunocytochemistry were utilized to examine disease‐driven changes of IL‐20 and its cognate receptor subunits in skin from healthy human subjects, AD patients and murine AD‐models. Calcium imaging, knockdown and cytokine array were used to investigate IL‐20‐evoked responses in keratinocytes and sensory neurons. The murine cheek model and behavioral scoring were employed to evaluate IL‐20‐elicited sensations in vivo. We found that transcripts and protein of IL‐20 were upregulated in skin from human AD and murine AD‐like models. Topical MC903 treatment in mice ear enhanced IL‐20R1 expression in the trigeminal sensory ganglia, suggesting a lesion‐associated and epidermal‐driven mechanism for sensitization of sensory IL‐20 signaling. IL‐20 triggered calcium influx in both keratinocytes and sensory neurons, and promoted their AD‐related molecule release and transcription of itch‐related genes. In sensory neurons, IL‐20 application increased TLR2 transcripts, implicating a link between innate immune response and IL‐20. In a murine cheek model of acute itch, intradermal injection IL‐20 and IL‐13 elicited significant itch‐like behavior, though only when co‐injected. Our findings provide novel insights into IL‐20 function in peripheral (skin‐derived) itch and clinically relevant intercellular neuron‐epidermal communication, highlighting a role of IL‐20 signaling in the pathophysiology of AD, thus forming a new basis for the development of a novel antipruritic strategy via interrupting IL‐20 epidermal pathways.

IL-22 Downregulates Peptidylarginine Deiminase-1 in Human Keratinocytes: Adding Another Piece to the IL-22 Puzzle in Epidermal Barrier Formation

Increased presence of IL-22+ cells in the skin is a characteristic finding in skin barrier defects, such as psoriasis and atopic dermatitis. However, mechanistic insight into effects of IL-22 on epidermal functioning is yet to be elucidated. One crucial step during epidermal differentiation is deimination or citrullination. Here, we show reduced levels of peptidylarginine deiminase 1, an enzyme that converts peptidylarginine into citrulline in lesional psoriatic skin. IL-22 signaling through the IL-22 receptor complex was found to suppress expression of peptidylarginine deiminase 1 in epidermal keratinocytes. Subsequently, total peptidylarginine deiminase activity and extent of protein deimination in keratinocytes treated with IL-22 were reduced together with a significant decrease in deimination of keratin 1 and FLG, both important for epidermal differentiation. Vitamin D and acitretin partly restored the peptidylarginine deiminase 1 defect caused by IL-22. Collectively, we show that IL-22 downregulates deimination, thus identifying a potential target for treatment of skin barrier defects.

Current Concepts of Psoriasis Immunopathogenesis

Psoriasis is a recurrent, chronic, immune-mediated, systemic inflammatory disease of the skin, joints, and other organic systems. After atopic dermatitis, chronic stationary psoriasis is the most common inflammatory skin disease, affecting an average of 2-4% of the world's population. The disease carries a significant burden due to its numerous comorbidities and the major impact on patients' social and emotional aspects of life. According to current knowledge, psoriasis is a multifactorial disease that occurs in genetically predisposed individuals under various environmental factors, which trigger an immune response disorder with a series of complex inflammatory cascades. The disease is initiated and maintained by mutual interaction of the innate and adaptive immune cells, primarily dendritic cells, T lymphocytes, and keratinocytes, whose leading role alternates at different stages of the disease, consisting mainly in the IL-23/Th17 pathway. Inflammatory events result in consequent epidermal and dermal changes and evolution of the characteristic psoriatic phenotype, respectively. This paper aims to present a comprehensive overview of current knowledge on psoriasis genetic and environmental etiological factors, immunopathogenesis, and the leading cellular and cytokine participants in the inflammatory pathways of this disease.

Role of oncostatin M in the pathogenesis of vernal keratoconjunctivitis: focus on tissue remodeling

PURPOSE

Vernal keratoconjunctivitis (VKC) is a severe and recurrent allergic conjunctivitis, the mechanism of which is not well understood. In this study, we investigated the role of oncostatin M (OSM) in the pathogenesis of VKC, with a focus on tissue remodeling.

STUDY DESIGN

Clinical and experimental.

PATIENTS AND METHODS

The OSM concentrations in tear fluid samples obtained from VKC patients and healthy controls were measured using ELISA, and the expression of OSM mRNA and protein in giant papillae resected from VKC patients was investigated using RT-PCR and immunohistochemistry, respectively. In cultured human conjunctival epithelial cells (HconEpiCs), expression of OSM receptor β (OSMRβ) was detected using immunocytochemical and FACS analyses. Finally, we investigated whether recombinant OSM activated STAT1 and STAT3 to induce the expression of various genes related to tissue remodeling in HconEpiCs, by using Western blot analysis, microarray analysis, and RT-PCR.

RESULTS

The OSM concentration was higher in the tear fluid of VKC patients than in that of the healthy controls, and strong expression of OSM mRNA was found in the giant papillae. We also detected T cells expressing OSM in the giant papillae. In addition, HconEpiCs showed surface expression of OSMRβ. Recombinant human OSM strongly activated both STAT1 and STAT3 in HconEpiCs and induced various tissue remodeling-related genes, including MMP-1, MMP-3, IL-24, IL-20, serpinB3, S100A7, tenascin C, and SOCS3.

CONCLUSION

Our results suggest that OSM is one of the key molecules involved in remodeling of giant papillae in VKC.

Regulation of Filaggrin, Loricrin, and Involucrin by IL-4, IL-13, IL-17A, IL-22, AHR, and NRF2: Pathogenic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is an eczematous, pruritic skin disorder with extensive barrier dysfunction and elevated interleukin (IL)-4 and IL-13 signatures. The barrier dysfunction correlates with the downregulation of barrier-related molecules such as filaggrin (FLG), loricrin (LOR), and involucrin (IVL). IL-4 and IL-13 potently inhibit the expression of these molecules by activating signal transducer and activator of transcription (STAT)6 and STAT3. In addition to IL-4 and IL-13, IL-22 and IL-17A are probably involved in the barrier dysfunction by inhibiting the expression of these barrier-related molecules. In contrast, natural or medicinal ligands for aryl hydrocarbon receptor (AHR) are potent upregulators of FLG, LOR, and IVL expression. As IL-4, IL-13, IL-22, and IL-17A are all capable of inducing oxidative stress, antioxidative AHR agonists such as coal tar, glyteer, and tapinarof exert particular therapeutic efficacy for AD. These antioxidative AHR ligands are known to activate an antioxidative transcription factor, nuclear factor E2-related factor 2 (NRF2). This article focuses on the mechanisms by which FLG, LOR, and IVL expression is regulated by IL-4, IL-13, IL-22, and IL-17A. The author also summarizes how AHR and NRF2 dual activators exert their beneficial effects in the treatment of AD.

The EGFR-ERK/JNK-CCL20 Pathway in Scratched Keratinocytes May Underpin Koebnerization in Psoriasis Patients

Epidermal keratinocytes represent a rich source of C-C motif chemokine 20 (CCL20) and recruit CCR6⁺ interleukin (IL)-17A–producing T cells that are known to be pathogenic for psoriasis. A previous study revealed that scratch injury on keratinocytes upregulates CCL20 production, which is implicated in the Koebner phenomenon characteristically seen in psoriasis patients. However, the molecular mechanisms leading to scratch-induced CCL20 production remain elusive. In this study, we demonstrate that scratch injury upregulates the phosphorylation of epidermal growth factor receptor (EGFR) and that the specific EGFR inhibitor PD153035 attenuates scratch-induced CCL20 upregulation in an extracellular signal-related kinase (ERK)-dependent, and to a lesser extent, a c-Jun N-terminal kinase (JNK)-dependent but p38 mitogen-activated protein kinase (MAPK)–independent manner. Immunoreactive CCL20 was visualized in the keratinocytes that lined the scratched wound. IL-17A also induced the phosphorylation of EGFR and further augmented scratch-induced CCL20 upregulation. The EGFR-ERK/JNK-CCL20 pathway in scratched keratinocytes may explain why Koebnerization is frequently seen in psoriasis patients.

IL-6 Negatively Regulates IL-22Rα Expression on Epidermal Keratinocytes: Implications for Irritant Contact Dermatitis

Irritant Contact Dermatitis (ICD) is characterized by epidermal hyperplasia and inflammatory cytokine release. IL-6 has been shown to be involved in the pathogenesis of ICD; however, the involvement of the IL-22/IL-22Rα axis and its relation to IL-6 in the inflammatory response following irritant exposure are unknown. Using a chemical model of ICD, it was observed that mice with a keratinocyte-specific knockout of IL-6Rα (IL-6Rα^Δker) presented with increased inflammation and IL-22Rα and IL-22 protein expression relative to WT following irritant exposure, indicating that IL-6Rα deficiency in epidermal keratinocytes leads to the upregulation of IL-22Rα and its ligand during ICD. Furthermore, it was shown that IL-6 negatively regulates the expression of IL-22Rα on epidermal keratinocytes. This effect is functional as the effects of IL-22 on keratinocyte proliferation and differentiation were markedly reduced when keratinocytes were pretreated with IL-6 prior to IL-22 treatment. These results show that IL-6 modulates the IL-22/IL-22Rα axis in the skin and suggest that this occurrence may be associated with the increased epidermal hyperplasia and exacerbated inflammatory response observed in IL-6Rα^Δker mice during ICD.

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.

Inactivation of the interleukin-22 pathway in the airways of cystic fibrosis patients

Interleukin (IL)-22 plays a critical role in regulating the maintenance of the mucosal barrier. As airway epithelial regeneration is abnormal in cystic fibrosis (CF), we investigated IL-22 integrity in CF. We first demonstrated, using Il-22-/- mice, that IL-22 is important to prevent lung damage induced by the CF pathogen Pseudomonas aeruginosa. Next, IL-22 receptor was found normally expressed at the airway epithelial surfaces of CF patients. In wound-healing assays, IL-22-treated CF cultures had higher wound-closure rate than controls, suggesting that IL-22 signaling per se could be functional in a CF context. However, persistence of neutrophil-derived serine-proteases is a major feature of CF airways. Remarkably, IL-22 was found altered in this protease-rich inflammatory microenvironment; the serine protease-3 being the most prone to fully degrade IL-22. Consequently, we suspect an acquired deficiency of the IL-22 pathway in the lungs of CF patients due to IL-22 cleavage by the surrounding neutrophil serine-proteases.

RNAI-MEDIATED SILENCING OF MATRIX METALLOPROTEINASE 1 IN EPIDERMAL KERATINOCYTES INFLUENCES THE BIOLOGICAL EFFECTS OF INTERLEUKIN 17A

Matrix metalloproteinases (MMPs) are important for the pathogenesis of psoriasis and other autoimmune disorders. In the extracellular matrix, accumulation of proinflammatory cytokines, such as interleukin 17A (IL-17A), leads to induction of several MMPs, including MMP1. MMPs change the composition and other properties of the extracellular matrix. These changes facilitate tissue remodeling and promote the development of psoriatic plaques. The aim of this study was to explore how MMP1 silencing might influence the biological effects of IL-17A on migration and proliferation of human epidermal keratinocytes and the expression of genes involved in their division and differentiation. The experiments were performed with MMP1-deficient and control epidermal keratinocytes, HaCaT-MMP1 and HaCaT-KTR, respectively. Cell proliferation and migration were assessed by comparative analysis of the growth curves and scratch assay, respectively. To quantify cell migration, representative areas of cell cultures were photographed at the indicated time points and compared to each other. Changes in gene expression were analyzed by real-time PCR. The obtained results demonstrated that MMP1 silencing in the cells treated with IL-17A resulted in downregulation of MMP9 and -12, FOSL1, CCNA2, IVL, KRT14 and -17 as well as upregulation of MMP2, CCND1 and LOR. Moreover, MMP1 silencing led to a decrease in cell proliferation and an impairment of cell migration. Thus, MMP1-deficiency in epidermal keratinocytes can be beneficial for psoriasis patients that experience an accumulation of IL-17 in lesional skin. Knocking MMP1 down could influence migration and proliferation of epidermal keratinocytes in vivo, as well as help to control the expression of MMP1, -2, -9 и -12, CCNA2, CCND1, KRT14 and -17 that are crucial for the pathogenesis of 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.

Bcl-3 induced by IL-22 via STAT3 activation acts as a potentiator of psoriasis-related gene expression in epidermal keratinocytes

IL-22 induces STAT3 phosphorylation and mediates psoriasis-related gene expression. However, the signaling mechanism leading from pSTAT3 to the expression of these genes remains unclear. We focused on Bcl-3, which is induced by STAT3 activation and mediates gene expression. In cultured human epidermal keratinocytes, IL-22 increased Bcl-3, which was translocated to the nucleus with p50 via STAT3 activation. The increases in CXCL8, S100As and human β-defensin 2 mRNA expression caused by IL-22 were abolished by siRNA against Bcl-3. Although CCL20 expression was also augmented by IL-22, the knockdown of Bcl-3 increased its level. Moreover, the combination of IL-22 and IL-17A enhanced Bcl-3 production, IL-22-induced gene expression, and the expression of other psoriasis-related genes, including those encoding IL-17C, IL-19, and IL-36γ. The expression of these genes (except for CCL20) was also suppressed by the knockdown of Bcl-3. Bcl-3 overexpression induced CXCL8 and HBD2 expression but not S100As expression. We also compared Bcl-3 expression between psoriatic skin lesions and normal skin. Immunostaining revealed strong signals for Bcl-3 and p50 in the nucleus of epidermal keratinocytes from psoriatic skin. The IL-22-STAT3-Bcl-3 pathway may be important in the pathogenesis of psoriasis.

Preferential CD8 rather than CD4 T-cell response to wear particles of polyether-ether-ketone and highly cross-linked polyethylene

The efficacy of polyether-ether-ketone (PEEK) as a bearing material in knee components, a potential alternative to the currently used highly cross-linked polyethylene (HXLPE), has attracted a lot of attention recently. This study aimed to systematically assess the effect of particulate wear debris on CD4 and CD8 T-cell responses. HXLPE and PEEK particles (96% less than 5 μm) were generated by custom cryo-milling and pulverization in liquid nitrogen, and then incubated with blood collected from 25 donors. The phenotypes of the T-cells were systematically analyzed by immunostaining and flow cytometry. For the in vivo study, 0.1 mL of each particle suspension (about 1.0 × 10⁸ wear particles) was injected into murine knee joints; the synovium and spleen were collected one week later for histological examination and immunofluorescence staining. PEEK and HXLPE particles did not induce CD4+ T-cell responses; however, CD8+ T-cells might be involved in mediating particle-induced reactions. The T-cell and inflammatory responses induced by PEEK and HXLPE particles were comparable. Further investigations into the frictional properties of materials should be performed to expand on our results.

Enriching the understanding of the effects of the particles on the adaptive immune response.

Therapeutic Effects of Methanol Extract from Euphorbia kansui Radix on Imiquimod-Induced Psoriasis

The roots of Euphorbia kansui, which belong to the family Euphorbiaceae, have been used as a traditional medicine for the treatment of various diseases such as diabetes, ascites, and leukemia. Recently, it was reported that the methylene chloride fraction of E. kansui radix (EKC) regulated the differentiation of Th17 cells and alleviated the symptoms of Th17-related inflammatory bowel disease. Imiquimod (IMQ), a TLR7/8 agonist, has been used to induce psoriasis in a mouse model. In this study, we evaluated the effect of EKC in an IMQ-induced psoriasis model. EKC effectively inhibited the production of interleukin-17A and interferon-γ in vitro. On this basis, EKC was administered to an animal model of psoriasis. Acanthosis and the infiltration of inflammatory cells into the dermis were significantly reduced by EKC. EKC also inhibited the expression of IL-17A, IL-22, IL-23, IL-12, and RAR-related orphan receptor gamma t (RORγt) in the spleen, skin-draining lymph nodes, and the skin. Additionally, EKC inhibited the activity of dendritic cells but not that of keratinocytes. In conclusion, EKC ameliorated the symptoms of psoriasis through inhibition of Th17 differentiation and activation of dendritic cells. These effects are expected to be beneficial in the treatment and prevention of psoriasis.

Characterization of linear mimetic peptides of Interleukin-22 from dissection of protein interfaces

Interleukin-22 (IL-22) belongs to the family of IL-10 cytokines and is involved in a wide number of human diseases, including inflammatory disorders and cancer pathology. The ligand-receptor complex IL-22/IL-22R plays a key role in several pathways especially in the regulation and resolution of immune responses. The identification of novel compounds able to modulate IL-22/IL-22R complex could open the route to new therapeutic strategies in multiple human diseases. In this study, we designed and characterized IL-22 derived peptides at protein interface regions: several sequences revealed able to interfere with the protein complex with IC50 in the micromolar range as evaluated through Surface Plasmon Resonance (SPR) experiments. Their conformational characterization was carried out through Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) spectroscopies, shedding new light into the features of IL-22 fragments and on structural determinants of IL-22/IL-22R1 recognition. Finally, several peptides were tested on human keratinocyte cultures for evaluating their ability to mimic the activation of molecular pathways downstream to IL-22R in response to IL-22 binding.

Immune cell-derived cytokines contribute to obesity-related inflammation, fibrogenesis and metabolic deregulation in human adipose tissue

Adipose tissue contains a variety of immune cells, which vary in abundance and phenotype with obesity. The contribution of immune cell-derived factors to inflammatory, fibrotic and metabolic alterations in adipose tissue is not well established in human obesity. Human primary adipose tissue cells, including pre-adipocytes, endothelial cells and mature adipocytes, were used to investigate deregulation of cell- and pathway-specific gene profiles. Among factors known to alter adipose tissue biology, we focus on inflammatory (IL-1β and IL-17) and pro-fibrotic (TGF-β1) factors. rIL-1β and rIL-17 induced concordant pro-inflammatory transcriptional programs in pre-adipocytes and endothelial cells, with a markedly more potent effect of IL-1β than IL-17. None of these cytokines had significant effect on fibrogenesis-related gene expression, contrasting with rTGF-β1-induced up-regulation of extracellular matrix components and pro-fibrotic factors. In mature adipocytes, all three factors promoted down-regulation of genes functionally involved in lipid storage and release. IL-1β and IL-17 impacted adipocyte metabolic genes in relation with their respective pro-inflammatory capacity, while the effect of TGF-β1 occurred in face of an anti-inflammatory signature. These data revealed that IL-1β and IL-17 had virtually no effect on pro-fibrotic alterations but promote inflammation and metabolic dysfunction in human adipose tissue, with a prominent role for IL-1β.

The pathogenic role of interleukin-22 and its receptor during UVB-induced skin inflammation

Recent studies show that IL-22, a cytokine produced by activated CD4+ T cells and NK cells, plays a pathogenic role in acute and chronic skin diseases. While IL-22 is produced by immune cells, the expression of IL-22Rα, the functional subunit of IL-22R, is mostly restricted to non-hematopoietic cells in organs such as the skin and pancreas. Although it is well known that ultraviolet B (UVB) radiation induces skin inflammation, there have been no reports regarding the effect of UVB on the expression of IL-22Rα. This study investigated IL-22Rα expression and IL-22-mediated proliferation and pro-inflammatory cytokine production by UVB-irradiated keratinocytes. IL-22Rα was increased in HaCaT and primary human keratinocytes after UVB irradiation through the translocation of IL-22Rα from the cytosol to the membrane. This increase in the expression of IL-22Rα was mediated by the PI3K/Akt pathway. Moreover, the suppression of keratinocyte proliferation by UVB irradiation was inhibited by treatment with IL-22. At the same time, IL-22 increased the production of IL-1α, IL-6, and IL-18 in UVB-irradiated HaCaT cells and primary human keratinocytes. Finally, IL-22Rα expression was increased in UVB-irradiated human and mouse skin by immunohistochemistry. The increased expression of IL-22Rα therefore promotes keratinocyte proliferation and pro-inflammatory cytokine production during UVB-induced skin inflammation, suggesting that UVB facilitates skin inflammation by increasing the responsiveness of keratinocytes to IL-22. This study provides a new insight into UVB-induced skin inflammation and the regulation of related inflammatory skin diseases.

Limited Presence of IL-22 Binding Protein, a Natural IL-22 Inhibitor, Strengthens Psoriatic Skin Inflammation

Psoriasis is a chronic inflammatory disease resulting from dysregulated immune activation associated with a large local secretion of cytokines. Among them, IL-22 largely contributes to epithelial remodeling and inflammation through inhibiting the terminal differentiation of keratinocytes and inducing antimicrobial peptides and selected chemokines. The activity of IL-22 is regulated by IL-22 binding protein (IL-22BP); however, the expression and role of IL-22BP in psoriatic skin has remained unknown so far. Here we showed that nonaffected skin of psoriasis patients displayed lower expression of IL-22BP than skin of healthy controls. Furthermore, the strong IL-22 increase in lesional psoriatic skin was accompanied by a moderate induction of IL-22BP. To investigate the role of IL-22BP in controlling IL-22 during skin inflammation, we used imiquimod-induced skin disease in rodents and showed that rats with genetic IL-22BP deficiency (Il22ra2-/-) displayed exacerbated disease that associated with enhanced expression of IL-22-inducible antimicrobial peptides. We further recapitulated these findings in mice injected with an anti-IL-22BP neutralizing Ab. Hypothesizing that the IL-22/IL-22BP expression ratio reflects the level of bioactive IL-22 in psoriasis skin, we found positive correlations with the expression of IL-22-inducible molecules (IL-20, IL-24, IL-36γ, CXCL1, and BD2) in keratinocytes. Finally, we observed that serum IL-22/IL-22BP protein ratio strongly correlated with psoriasis severity. In conclusion, we propose that although IL-22BP can control deleterious actions of IL-22 in the skin, its limited production prevents a sufficient neutralization of IL-22 and contributes to the development and maintenance of epidermal alterations in psoriasis.

Epidermal CD147 expression plays a key role in IL-22-induced psoriatic dermatitis

Psoriasis is a chronic inflammatory skin disease characterized by abnormal keratinocyte proliferation and terminal differentiation. Interleukin-22 (IL-22) and the transcription factor Stat3 play pivotal roles in the pathogenesis of psoriasis. CD147 is a transmembrane glycosylation protein that belongs to the immunoglobulin superfamily. Our previous studies have shown that CD147 is a marker of high keratinocyte proliferation and poor keratinocyte differentiation as well as a psoriasis susceptibility gene. The current study demonstrates that CD147 is highly expressed in psoriatic skin lesions. Specific CD147 over-expression in the epidermis of K5-promoter transgenic mice promotes imiquimod (IMQ)-induced psoriasis-like inflammation characterized by acanthosis, granular layer loss and inflammatory cell infiltration. We also found that IL-22 increases CD147 transcription in vitro and in vivo and that Stat3 binds directly to the CD147 promoter between positions -854 and -440, suggesting that CD147 expression is up-regulated in patients with psoriasis through Stat3 activation. In addition, CD147 knockdown dramatically blocks IL-22-mediated Stat3 activation as well as IL-22-induced cytokine, chemokine and antimicrobial factor expression. Together, these findings show that CD147 is a novel and key mediator of IL-22-induced psoriatic alterations in the epidermis and might be a therapeutic target in patients with psoriasis.

Cooperation between the bacterial-derived short-chain fatty acid butyrate and interleukin-22 detected in human Caco2 colon epithelial/carcinoma cells

By generating biologically active factors luminal microbiota shape the intestinal micro-milieu thereby regulating pathological processes such as inflammation and carcinogenesis. Preclinical data suggest that bacterial-derived butyrate and the signal transducer and activator of transcription (STAT)-3 activating cytokine interleukin (IL)-22 display concordant protective properties at the inflamed colonic epithelium. Herein, biochemical cooperation between the short-chain fatty acid butyrate and IL-22 was investigated by focusing on human Caco2 colon epithelial/carcinoma cells. We report that physiological levels of butyrate enhance IL-22 signaling thereby enforcing expression of the prototypic STAT3-downstrean target genes α1-antichymotrypsin and suppressor of cytokine signaling (SOCS)-3. A dual mode of butyrate action on the IL-22/STAT3 axis was identified. Butyrate acted by upregulating IL-22R1, the decisive chain of the heterodimeric IL-22 receptor, and, independent from that, has the potential to directly amplify STAT3-mediated gene activation as detected by chromatin immunoprecipitation analysis of STAT3 binding to the SOCS3 promoter. Since trichostatin A acted similarly, inhibition of histone deacetylases is likely at the root of these butyrate biological properties. The mutual benefit gained from interactions between the host and commensal intestinal bacteria-derived factors is an expanding field of research beginning to affect clinical practice. Data presented herein propose a supportive and fine-tuning role for butyrate in IL-22 signaling that might be therapeutically exploited by local butyrate administration or by increasing its bacterial production in the context of a fiber-rich diet. © 2016 BioFactors, 43(2):283-292, 2017.

Cytokine signaling regulating adipose stromal cell trafficking

Adipocyte progenitors, known as adipose stromal cells (ASC), can become mobilized, recruited by tumors, and contribute to cancer progression. Mechanisms underlying ASC trafficking have remained obscure. We recently reported that CXCL1 expressed by cancer cells chemoattracts ASC expressing CXCR1 in obesity. As a candidate mechanism of CXCL1 activation, we identified interleukin (IL)-22, systemic circulation of which is increased in obesity. It has been reported that IL-22 signaling through IL-22R is upstream of CXCL1. Here, we provide evidence that IL-22 expression by leukocytes infiltrating WAT and IL-22R expression by tumors is obesity-dependent. We propose that obesity-associated adipocyte death and the resulting recruitment of leukocytes triggers the IL-22 signaling cascade that induces CXCL1 secretion by cancer cells responsible for ASC trafficking to tumors.

IL-22 promoted CD3+ T cell infiltration by IL-22R induced STAT3 phosphorylation in murine acute graft versus host disease target organs after allogeneic bone marrow transplantation

Graft versus host disease (GVHD) is a life threatening complication of bone marrow stem cell transplantation, in which considerable numbers of proinflammatory cytokines secreted by allo-reactive donor T cells are involved. We and other previous studies have found that interleukin-22 (IL-22) was able to aggravate the target organs damage of GVHD. However, the mechanism and the signal pathway of IL-22 in murine acute GVHD was not clear. Here, we observed that compared with GVHD group, more serious pathological damage and more CD3(+) T cells infiltrated in GVHD target organs were detected in the mice injected with IL-22. Meanwhile, transcription factor T-bet, RORγt and AhR respectively associated with Th1, Th17 and Th22 cells changed in varying degrees in different GVHD target organs. Furthermore, the increased expression of IL-22R and its downstream protein P-STAT3 were detected in GVHD mice with IL-22 treated. These results suggested that the pathological role of IL-22 in GVHD target organs contribute to exogenous injected IL-22 as well as secreted IL-22 from the infiltrated allo-reactive effector T cells. In addition, the IL-22R-STAT3 pathway may play important role in GVHD tissue injury and target this way may yield new approaches for reduction of GVHD.

Interleukin 20 regulates dendritic cell migration and expression of co-stimulatory molecules

Background

Psoriasis is an inflammatory disease characterized by leukocyte skin infiltration. Interestingly, recent works suggest that the migration of dendritic cells (DCs) is abnormal in psoriatic skin. DCs have significant role in regulating the function of T lymphocytes, at least in part influenced by the local environment of cytokines. In psoriatic skin lesions the expression of IL-20 is highly up-regulated. It is unclear if this cytokine has any influence on DCs.

Methods

Here, we investigated the influence of IL-20 in monocyte-derived dendritic cell (MDDCs) in vitro. This work addressed IL-20 effects on DC maturation, receptor expression and signaling. By use of extra cellular matrix components mimicking the skin environment, we also studied the functional effects of IL-20 on the chemotactic migration of DCs. Based on the recent finding that CD18 integrin are shed during migration of myeloid leukocytes, the concentration of these adhesion molecules was measured in MDDCs culture supernatants post migration.

Results

Following stimulation with IL-20, immature human MDDCs enhanced the expression of the co-stimulatory molecule CD86, further enabling activation of the p38 MAPK, but not the STAT3, pathway. IL-20 increased the migration of MDDCs in a biphasic response narrowly controlled by the interleukin concentration. A concomitant change in the shedding of CD18 integrins suggested that these adhesion molecules play a role in the migration of the MDDCs through the extracellular matrix layer.

Conclusion

Taken together, our findings points to a possible, yet subtle, role of IL-20 in DCs migration. The biphasic response suggests that the aberrant IL-20 expression in psoriasis impedes DC migration, which could be a part of the processes that precipitates the dysregulated inflammatory response associated with this disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s40591-016-0046-x) contains supplementary material, which is available to authorized users.

Transcriptome profiling unveils the role of cholesterol in IL-17A signaling in psoriasis

Psoriasis is a chronic inflammatory skin disease characterized by altered proliferation and differentiation of keratinocytes as well as infiltration of immune cells. Increased expression of Th17 cells and cytokines secreted by them provides evidence for its central role in the pathogenesis of psoriasis. IL-17A, signature cytokine of Th17 cells was found to be highly differentially expressed in psoriatic lesional skin. However, cellular and molecular mechanism by which IL-17A exerts its function on keratinocyte is incompletely understood. To understand IL-17A mediated signal transduction pathways, gene expression profiling was done and differentially expressed genes were analysed by IPA software. Here, we demonstrate that during IL-17A signaling total cholesterol levels were elevated, which in turn resulted in the suppression of genes of cholesterol and fatty acid biosynthesis. We found that accumulation of cholesterol was essential for IL-17A signaling as reduced total cholesterol levels by methyl β cyclodextrin (MBCD), significantly decreased IL-17A induced secretion of CCL20, IL-8 and S100A7 from the keratinocytes. To our knowledge this study for the first time unveils that high level of intracellular cholesterol plays a crucial role in IL-17A signaling in keratinocytes and may explain the strong association between psoriasis and dyslipidemia.

Targeting IL-10 in auto-immune diseases

IL-10 is a multifunctional cytokine secreted by a variety of cells. It not only inhibits activation of monocyte/macrophage system and synthesis of monocyte cytokine and inflammatory cytokine but also promotes the proliferation and maturation of non-monocyte-dependent T cell, stimulating proliferation of antigen-specific B cell. Increasing evidence indicates that IL-10 plays an important role in both the onset and development of auto-immune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS), multiple sclerosis (MS), Crohn's disease (CD), and psoriasis. However, the exact mechanisms of IL-10 in auto-immune diseases remain unclear. In the present review, we will summarize the biological effects of IL-10, as well as its role and therapeutic potential in auto-immune diseases.

Genetic, Epigenetic and Pharmacogenetic Aspects of Psoriasis and Psoriatic Arthritis

There is a strong familial component to psoriatic disease as well as a complex array of genetic, immunologic, and environmental factors. The dominant genetic effect is located on chromosome 6p21.3 within the major histocompatibility complex region, accounting for one-third of genetic contribution. Genome-wide association studies (GWAS) identified additional genes, including skin barrier function, innate immune response, and adaptive immune response genes. To better understand disease susceptibility and progression requires replication in larger cohorts, fine-mapping efforts, new technologies, and functional studies of genetic variants, gene-gene interactions and gene-environmental interactions. New technologies available include next-generation sequencing, copy number variation analysis, and epigenetics.

First-In-Human, Phase 1, Randomized, Dose-Escalation Trial with Recombinant Anti-IL-20 Monoclonal Antibody in Patients with Psoriasis

Background

The current trial was a first-in-human clinical trial evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of the recombinant monoclonal anti−interleukin-20 (IL-20) antibody, NNC0109-0012, which targets the inflammatory cytokine IL-20.

Methods

In total, 48 patients aged 18 to 75 years with moderate to severe stable chronic plaque psoriasis with affected body surface area ≥15% and physician global assessment score ≥3 were enrolled in this randomized, double-blind, multicenter, placebo-controlled, phase 1 dose-escalation trial. Patients were randomized within each single dose cohort (0.01, 0.05, 0.2, 0.6, 1.5, or 3.0 mg/kg) or multiple dose cohort (0.05, 0.2, 0.5, 1.0, or 2.0 mg/kg; 1 dose every other week for 7 weeks) of NNC0109-0012 or placebo in a 3:1 ratio. In the expansion phase, 7 patients were randomized to weekly doses of 2.0 mg/kg NNC0109-0012 or placebo for 7 weeks. The primary objective, safety and tolerability, was assessed by evaluating adverse events (AEs). Additional endpoints included pharmacokinetics, pharmacodynamics, and clinical response (assessed using the Psoriasis Area and Severity Index [PASI] score).

Results

AEs were reported in 85% of patients (n = 40) in the initial study phases (NNC0109-0012, 83%; placebo, 92%) and in 4 of 7 patients in the multiple-dose expansion phase. One serious AE was reported but was judged not to be causally related to NNC0109-0012. No dose-limiting toxicities were reported. NNC0109-0012 pharmacokinetics was similar to other monoclonal antibodies, with an average half-life of approximately 3 weeks. There was a dose-proportional increase in area under the curve and maximum concentration after single dosing. No substantial changes in pharmacodynamic parameters were observed. The expansion phase was terminated early due to apparent lack of PASI improvement.

Conclusion

Single and multiple doses of NNC0109-0012, ranging from 0.05 to 3.0 mg/kg, were well tolerated in patients with psoriasis and exhibited pharmacokinetics similar to that of other monoclonal antibodies.

Trial Registration

ClinicalTrials.gov NCT01261767

Interaction of Salmonella enterica Serovar Typhimurium with Intestinal Organoids Derived from Human Induced Pluripotent Stem Cells

The intestinal mucosa forms the first line of defense against infections mediated by enteric pathogens such as salmonellae. Here we exploited intestinal "organoids" (iHOs) generated from human induced pluripotent stem cells (hIPSCs) to explore the interaction of Salmonella enterica serovar Typhimurium with iHOs. Imaging and RNA sequencing were used to analyze these interactions, and clear changes in transcriptional signatures were detected, including altered patterns of cytokine expression after the exposure of iHOs to bacteria. S. Typhimurium microinjected into the lumen of iHOs was able to invade the epithelial barrier, with many bacteria residing within Salmonella-containing vacuoles. An S. Typhimurium invA mutant defective in the Salmonella pathogenicity island 1 invasion apparatus was less capable of invading the iHO epithelium. Hence, we provide evidence that hIPSC-derived organoids are a promising model of the intestinal epithelium for assessing interactions with enteric pathogens.

An inflammatory triangle in psoriasis: TNF, type I IFNs and IL-17

Psoriasis is a skin disease where various cytokines play a detrimental role, yet our understanding of the disease is still limited. TNF is a validated drug target in psoriasis and other autoimmune diseases, but its use is associated with side effects. Some paradoxical side effects of anti-TNF treatment are supposedly associated with type I IFNs, which are also implicated in the pathogenesis of psoriasis. Recently, the IL-23/IL-17 axis has been associated with psoriasis as well, and new drugs targeting this axis have already been developed. Findings suggest that these cytokines are interwoven. We discuss recent findings reinforcing the role of TNF, Type I IFNs and IL-17 in the pathogenesis of psoriasis and the apparent inflammatory interplay between these three cytokines.

Inhibition of inflammatory and proliferative responses of human keratinocytes exposed to the sesquiterpene lactones dehydrocostuslactone and costunolide

The imbalance of the intracellular redox state and, in particular, of the glutathione (GSH)/GSH disulfide couple homeostasis, is involved in the pathogenesis of a number of diseases. In many skin diseases, including psoriasis, oxidative stress plays an important role, as demonstrated by the observation that treatments leading to increase of the local levels of oxidant species ameliorate the disease. Recently, dehydrocostuslactone (DCE) and costunolide (CS), two terpenes naturally occurring in many plants, have been found to exert various anti-inflammatory and pro-apoptotic effects on different human cell types. These compounds decrease the level of the intracellular GSH by direct interaction with it, and, therefore, can alter cellular redox state. DCE and CS can trigger S-glutathionylation of various substrates, including the transcription factor STAT3 and JAK1/2 proteins. In the present study, we investigated on the potential role of DCE and CS in regulating inflammatory and proliferative responses of human keratinocytes to cytokines. We demonstrated that DCE and CS decreased intracellular GSH levels in human keratinocytes, as well as inhibited STAT3 and STAT1 phosphorylation and activation triggered by IL-22 or IFN-γ, respectively. Consequently, DCE and CS decreased the IL-22- and IFN-γ-induced expression of inflammatory and regulatory genes in keratinocytes, including CCL2, CXCL10, ICAM-1 and SOCS3. DCE and CS also inhibited proliferation and cell-cycle progression-related gene expression, as well as they promoted cell cycle arrest and apoptosis. In parallel, DCE and CS activated the anti-inflammatory EGFR and ERK1/2 molecules in keratinocytes, and, thus, wound healing in an in vitro injury model. In light of our findings, we can hypothesize that the employment of DCE and CS in psoriasis could efficiently counteract the pro-inflammatory effects of IFN-γ and IL-22 on keratinocytes, revert the apoptosis-resistant phenotype, as well as inhibit hyperproliferation in the psoriatic epidermis.

The crosstalk between IL-22 signaling and miR-197 in human keratinocytes

The interaction between the immune system and epithelial cells is tightly regulated. Aberrations of this balance may result in inflammatory diseases such as psoriasis, inflammatory bowel disease and rheumatoid arthritis. IL-22 is produced by Th17, Th22 and Th1 cells. Putative targets for IL-22 are cells in the skin, kidney, digestive and respiratory systems. The highest expression of IL-22 receptor is found in the skin. IL-22 plays an important role in the pathogenesis of T cell-mediated inflammatory diseases such as psoriasis, inflammatory bowel disease and rheumatoid arthritis. Recently, we found that miR-197 is down regulated in psoriatic lesions. In the present work we show that miR-197 over expression inhibits keratinocytes proliferation induced by IL-22 and keratinocytes migration. In addition, we found that IL-22 activates miR-197 expression through the binding of phosphorylated STAT3 to sequences in the putative promoter of miR-197. Finally we found that IL-22 receptor subunit IL22RA1 is a direct target of miR-197. Hence, we identified a novel feedback loop controlling IL-22 signaling, in which IL-22 induces miR-197, which in turn, negatively regulates IL-22 receptor and attenuates the biological outcome of such signaling. Regulation of this pathway may be important in inflammatory skin disorders such a psoriasis and in wound healing.

Amygdalin analogues inhibit IFN-γ signalling and reduce the inflammatory response in human epidermal keratinocytes

Peptide T (PT), an octapeptide fragment located in the V2 region of the HIV-1 gp120-coating protein, appears to be beneficial in the treatment of psoriasis. Our previous investigations suggest that keratinocytes play a key role in conditioning the therapeutic effects of PT in psoriasis. The aim of this study was to explore the effects of PT and the peptidomimetic natural products, Dhurrin and Prunasin, on the expression of the IL-6, IL-8, IL-23, HSP70 and ICAM-1 on IFN-γ and TNF-α-NHEK activated cells. Moreover, we analysed the interference of PT and its analogues through STAT-3 activation. Our results show that the analogues tested exhibit the beneficial biological effects of PT, suggesting the primary role of keratinocytes upon which PT and the peptidomimetics act directly, by reducing proinflammatory responses. Its reduction appears to be important for therapeutic approach in psoriasis pathogenesis.

Cytokine effects induced by the human autoallergen α-NAC

Autoallergy is a phenomenon found in a subgroup of patients with atopic dermatitis (AD). These patients exhibit serum IgE reactivity toward autoantigens like the alpha-chain of the nascent polypeptide-associated complex (α-NAC; Hom s 2). α-NAC has been shown before to induce T-cell proliferation and secretion of IFN-γ. To elucidate the immune modulating functions α-NAC may exert, we analyzed its effects on cytokine transcription and secretion in peripheral blood mononuclear cells (PBMCs), monocytes, and CD4+ T cells. Transcription and secretion of IFN-γ, IL-17, and IL-22 were increased in α-NAC-stimulated PBMCs. As IL-17 was significantly upregulated by α-NAC, we assessed signal transduction in PBMCs and found signal transducer and activator of transcription 3 phosphorylation in α-NAC-stimulated cells. Furthermore, we could show the importance of monocyte activation by α-NAC, as isolated T cells reacted only weakly toward the stimulation. Inhibition of IL-23 p19 led to lower amounts of IL-17 in the PBMC supernatants after α-NAC stimulation. α-NAC stimulation of PBMCs from non-allergic donors resulted in secretion of IL-10, which was greatly reduced in PBMCs from α-NAC-sensitized AD patients. Our findings provide insights into the mechanisms of autoallergy, investigating the interplay of immune cells, signaling events, and cytokines, which are known to be relevant in atopic skin inflammation.

The role of the IL-22/IL-22R1 axis in cancer

Interleukin-22 (IL-22) is an IL-10 family cytokine produced by T cells and innate lymphoid cells. The IL-22 signaling pathway orchestrates mucosal immune defense and tissue regeneration through pleiotropic effects including pro-survival signaling, cell migration, dysplasia and angiogenesis. While these functions can prevent initial establishment of tumors, they can also be hijacked by aggressive cancers to enhance tumor growth and metastasis. Thus, the role of the IL-22/IL-22R1 axis in cancer is complex and context-specific. Evidence of IL-22 involvement manifests as dysregulation of IL-22 expression and signaling in patients with many common cancers including those of the gut, skin, lung and liver. Unlike other cancer-associated cytokines, IL-22 has restricted tissue specificity as its unique receptor IL-22R1 is exclusively expressed on epithelial and tissue cells, but not immune cells. This makes it an attractive target for therapy as there is potential achieve anti-tumor immunity with fewer side effects. This review summarizes current findings on functions of IL-22 in association with general mechanisms for tumorigenesis as well as specific contributions to particular cancers, and ponders how best to approach further research in the field.

IL-17 induces an expanded range of downstream genes in reconstituted human epidermis model

Background

IL-17 is the defining cytokine of the Th17, Tc17, and γδ T cell populations that plays a critical role in mediating inflammation and autoimmunity. Psoriasis vulgaris is an inflammatory skin disease mediated by Th1 and Th17 cytokines with relevant contributions of IFN-γ, TNF-α, and IL-17. Despite the pivotal role IL-17 plays in psoriasis, and in contrast to the other key mediators involved in the psoriasis cytokine cascade that are capable of inducing broad effects on keratinocytes, IL-17 was demonstrated to regulate the expression of a limited number of genes in monolayer keratinocytes cultured in vitro.

Methodology/Principal Findings

Given the clinical efficacy of anti-IL-17 agents is associated with an impressive reduction in a large set of inflammatory genes, we sought a full-thickness skin model that more closely resemble in vivo epidermal architecture. Using a reconstructed human epidermis (RHE), IL-17 was able to upregulate 419 gene probes and downregulate 216 gene probes. As possible explanation for the increased gene induction in the RHE model is that C/CAAT-enhancer-binding proteins (C/EBP) -β, the transcription factor regulating IL-17-responsive genes, is expressed preferentially in differentiated keratinocytes.

Conclusions/Significance

The genes identified in IL-17-treated RHE are likely relevant to the IL-17 effects in psoriasis, since ixekizumab (anti-IL-17A agent) strongly suppressed the “RHE” genes in psoriasis patients treated in vivo with this IL-17 antagonist.

S100A8-S100A9 protein complex mediates psoriasis by regulating the expression of complement factor C3

Psoriasis is a common heterogeneous inflammatory skin disease with a complex pathophysiology and limited treatment options. Here we performed proteomic analyses of human psoriatic epidermis and found S100A8-S100A9, also called calprotectin, as the most upregulated proteins, followed by the complement component C3. Both S100A8-S100A9 and C3 are specifically expressed in lesional psoriatic skin. S100A9 is shown here to function as a chromatin component modulating C3 expression in mouse and human cells by binding to a region upstream of the C3 start site. When S100A9 was genetically deleted in mouse models of skin inflammation, the psoriasis-like skin disease and inflammation were strongly attenuated, with a mild immune infiltrate and decreased amounts of C3. In addition, inhibition of C3 in the mouse model strongly reduced the inflammatory skin disease. Thus, S100A8-S100A9 can regulate C3 at the nuclear level and present potential new therapeutic targets for psoriasis.