Ultraviolet B radiation and reactive oxygen species modulate interleukin-31 expression in T lymphocytes, monocytes and dendritic cells

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

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

Effect of L-4-Thiazolylalanine (Protinol™) on skin barrier strength and skin protection

OBJECTIVES

Skin barrier properties are critical for maintaining epidermal water content, protecting from environmental factors and providing the first line of defense against pathogens. In this study, we investigated the non-proteinogenic amino acid L-4-Thiazolylalanine (L4) as a potential active ingredient in skin protection and barrier strength.

METHODS

L4 on wound healing, anti-inflammatory and anti-oxidant properties were evaluated using monolayers and 3D skin equivalents. The transepithelial electrical resistance (TEER) value was used in vitro as a strong indicator of barrier strength and integrity. Clinical L4 efficacy was assessed for the evaluation of the skin barrier integrity and soothing benefits.

RESULTS

In vitro treatments of L4 show beneficial effects in wound closure mechanism, and we demonstrate that L4 anti-oxidant benefits with markedly increased HSP70 and decreased reactive oxygen species production induced by UVs exposure. Barrier strength and integrity were significantly improved by L4, confirmed clinically by an increase in 12R-lipoxygenase enzymatic activity in the stratum corneum. In addition, soothing benefits of L4 have been shown clinically with the decrease in redness after methyl nicotinate application on the inner arm and the significant reduction of the erythema and the skin desquamation on the scalp.

CONCLUSION

L4 delivered multiple skin benefits by strengthening the skin barrier, accelerating the skin repair process as well as soothing the skin and the scalp with anti-inflammaging effects. The observed efficacy validates L4 as a desirable skincare ingredient for topical treatment.

Pruritogens in pemphigoid diseases: Possible therapeutic targets for a burdensome symptom

Pruritus is a hallmark feature in pemphigoid diseases, where it can be severe and greatly impact the quality of life of affected patients. Despite being a key symptom, the exact pathophysiological mechanisms involved in pruritus in pemphigoid are yet to be fully elucidated and effective therapies addressing them are limited. This review summarizes the present understanding of pruritus specific to pemphigoid diseases, especially the pruritogens that induce it, and the therapeutic options that have been explored so far. The majority of the available evidence is on bullous pemphigoid and epidermolysis bullosa acquisita. Histamine derived from basophils correlates with pruritus severity, with omalizumab demonstrating promising efficacy in pruritus for bullous pemphigoid. IL-4/-13 contribute to itch in bullous pemphigoid with dupilumab being evaluated in clinical trials. Other pruritogens of interest include substance P, tryptase, and thymic stromal lymphopoetin, with therapies targeting them requiring further investigation. Scratching behaviors contribute directly to blister formation through various mechanisms, such as pathological autoantibody recruitment, T helper cell type 1 polarization, and exposure of intracellular autoantigens. Treatments addressing these pathways may contribute to decreasing disease severity. Additional studies are needed to fully characterize how pruritus is regulated in pemphigoid diseases, to help pave the way to develop novel and effective therapeutics that will not only address pruritic symptoms but also decrease disease severity.

IL-31 expression in HIV-infected patients with different routes of disease transmission

Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV). AIDS is characterized by an impaired immune system and low cellular immunity. The main manifestation of AIDS is a reduction in the number of CD4+ T cells and alteration in cytokine concentration. The present work aimed to explore the expression of IL-31 in HIV infection and disease progression.Serum samples were collected from HIV-infected patients with different routes of disease transmission. The subjects included 24 patients who were infected with HIV upon blood transmission and 36 patients who had acquired the disease through sexual transmission (21 cases of homosexual transmission and 15 cases of heterosexual transmission). In addition, 20 normal healthy individuals were included to serve as the control group. The levels of IL-31 in the collected serum samples were estimated using the human IL-31 Platinum ELISA kit.The serum analysis results revealed that the concentration of IL-31 in the serum samples for the blood transmission, sexually transmission, and normal group patients was 4.07 ± 1.63 pg/L, 7.43 ± 1.15 pg/L, and 2.87 ± 1.04 pg/L, respectively. The statistical analysis revealed that the concentration of IL-31 in HIV-1 infection was higher than that in the normal control. In addition, the expression of IL-31 was significantly higher in the sexual transmission group compared to the blood transmission group (P < .05).IL-31 could have an important role in HIV infection, although the role of IL-31 in disease progression in HIV-infected individuals requires further research.

IL-31: State of the Art for an Inflammation-Oriented Interleukin

Interleukin 31 belongs to the IL-6 superfamily, and it is an itch mediator already studied in several diseases, comprising atopic dermatitis, allergic pathologies, and onco-hematological conditions. This research aims to assess the role of this cytokine in the pathogenesis of these conditions and its potential therapeutic role. The research has been conducted on articles, excluding reviews and meta-analysis, both on animals and humans. The results showed that IL-31 plays a crucial role in the pathogenesis of systemic skin manifestations, prognosis, and itch severity. Traditional therapies target this interleukin indirectly, but monoclonal antibodies (Mab) directed against it have shown efficacy and safety profiles comparable with biological drugs that are already available. Future perspectives could include the development of new antibodies against IL-31 both for humans and animals, thus adding a new approach to the therapy, which often has proven to be prolonged and specific for each patient.

Are TRPA1 and TRPV1 channel-mediated signalling cascades involved in UVB radiation-induced sunburn?

Burn injuries are underappreciated injuries associated with substantial morbidity and mortality. Overexposure to ultraviolet (UV) radiation has dramatic clinical effects in humans and is a significant public health concern. Although the mechanisms underlying UVB exposure are not fully understood, many studies have made substantial progress in the pathophysiology of sunburn in terms of its molecular aspects in the last few years. It is well established that the transient receptor potential ankyrin 1 (TRPA1), and vanilloid 1 (TRPV1) channels modulate the inflammatory, oxidative, and proliferative processes underlying UVB radiation exposure. However, it is still unknown which mechanisms underlying TRPV1/A1 channel activation are elicited in sunburn induced by UVB radiation. Therefore, in this review, we give an overview of the TRPV1/A1 channel-mediated signalling cascades that may be involved in the pathophysiology of sunburn induced by UVB radiation. These data will undoubtedly help to explain the various features of sunburn and contribute to the development of novel therapeutic approaches to better treat it.

Granzyme B in Epithelial Barrier Dysfunction and Related Skin Diseases

The predominant function of the skin is to serve as a barrier - to protect against external insults and to prevent water loss. Junctional and structural proteins in the stratum corneum, the outermost layer of the epidermis, are critical to the integrity of the epidermal barrier as it balances ongoing outward migration, differentiation, and desquamation of keratinocytes in the epidermis. As such, epidermal barrier function is highly susceptible to upsurges of proteolytic activity in the stratum corneum and epidermis. Granzyme B is a serine protease scarce in healthy tissues but present at high levels in tissues encumbered by chronic inflammation. Discovered in the 1980s, Granzyme B is currently recognized for its intracellular roles in immune cell-mediated targeted apoptosis as well as extracellular roles in inflammation, chronic injuries, tissue remodeling, and processing of cytokines, matrix proteins, and autoantigens. Increasing evidence has emerged in recent years supporting a role for Granzyme B in promoting barrier dysfunction in the epidermis by direct cleavage of barrier proteins and eliciting immunoreactivity. Likewise, Granzyme B contributes to impaired epithelial function of the airways, retina, gut and vessels. In the present review, the role of Granzyme B in cutaneous epithelial dysfunction is discussed in the context of specific conditions with an overview of underlying mechanisms as well as utility of current experimental and therapeutic inhibitors.

Neuro-immune communication regulating pruritus in atopic dermatitis

Atopic dermatitis (AD) is a common, chronic-relapsing inflammatory skin disease with significant disease burden. Genetic and environmental trigger factors contribute to AD, activating two of our largest organs, the nervous and immune system. Dysregulation of neuro-immune circuits plays a key role in the pathophysiology of AD causing inflammation, pruritus, pain, and barrier dysfunction. Sensory nerves can be activated by environmental or endogenous trigger factors transmitting itch stimuli to the brain. Upon stimulation, sensory nerve endings also release neuromediators into the skin contributing again to inflammation, barrier dysfunction and itch. Additionally, dysfunctional peripheral and central neuronal structures contribute to neuroinflammation, sensitization, nerve elongation, neuropathic itch, thus chronification and therapy-resistance. Consequently, neuro-immune circuits in skin and central nervous system may be targets to treat pruritus in AD. Cytokines, chemokines, proteases, lipids, opioids, ions excite/sensitize sensory nerve endings not only induce itch but further aggravate/perpetuate inflammation, skin barrier disruption, and pruritus. Thus, targeted therapies for neuro-immune circuits as well as pathway inhibitors (e.g., kinase inhibitors) may be beneficial to control pruritus in AD either in systemic and/or topical form. Understanding neuro-immune circuits and neuronal signaling will optimize our approach to control all pathological mechanisms in AD, inflammation, barrier dysfunction and pruritus.

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.

Phototherapy for Generalized Pruritus of Unknown Origin: Single-Center Experience

OBJECTIVE

Phototherapy is a well-established therapy in dermatology. However, there is limited evidence regarding phototherapy for the treatment of generalized pruritus of unknown origin (GPUO). The objective of this study was to assess the efficacy and safety of narrowband ultraviolet B (NB-UVB) phototherapy in patients with GPUO.

METHODS

Researchers conducted a retrospective review of the treatment outcomes of patients with GPUO who were treated with NB-UVB between 2004 and 2019 at their facility.

RESULTS

Investigators included 67 patients diagnosed with GPUO treated with NB-UVB. Complete remission was achieved in more than 70% of the patients. No serious adverse events were documented.

CONCLUSIONS

For patients with GPUO, NB-UVB may be a safe and effective treatment option.

The interaction between the immune system and the peripheral sensory nerves in pruritus

Pruritus is a skin-specific sensation that is observed in various skin diseases, especially in inflammatory skin diseases such as atopic dermatitis, and is deeply involved in their pathogenesis. Pruritus also adversely affects patients' sleep and mental health, placing a heavy burden on daily life. As such, pruritus control is important to the maintenance of health. The mechanism of pruritus has recently been clarified and the discovery of various pruritus mediators, the identification of specific nerves that transmit pruritus and the accumulation of knowledge on pruritus perception have led to a better understanding of all aspects of pruritus generation, transmission and recognition. In the case of pruritus caused by dermatitis, immune cells infiltrating the skin secrete inflammatory cytokines, which also act on peripheral nerves as pruritus mediators and induce an inflammatory response. Interestingly, there has been accumulating evidence that peripheral nerves are also involved in the inflammation via neuropeptides. In this article, we summarize the findings on pruritus mediators secreted by immune cells and the roles of peripheral nerves in pruritus in terms of their interactions with immunity.

Significance of interleukin-31 (IL-31) gene polymorphisms and IL-31 serum level in psoriasis in correlation with pruritus

Introduction

Interleukin-31 (IL-31) impact on the development and clinical presentation of psoriasis as well as pruritus has not been widely investigated so far.

Aim

To analyse IL-31 -1066G/A and -2057G/A promoter gene polymorphisms as well as serum IL-31 level and their correlation with severity of psoriasis and pruritus in the population of northern Poland.

Material and methods

The study included 300 psoriasis patients and 186 healthy volunteers. The polymorphisms were analysed using amplified refractory mutation system - polymerase chain reaction (ARMS-PCR) method. Serum levels of IL-31 were measured using the enzyme-linked immunosorbent assay (ELISA) test.

Results

The -1066 AA genotype of the IL-31 gene was statistically more frequent in patients and it increased the risk of psoriasis (OR = 1.80; p = 0.04). The GG genotype as well as G allele of the IL-31 -2057 gene polymorphism were rarely observed in psoriasis and were associated with a decreased risk of the disease (OR = 0.6, p = 0.007 and OR = 0.7, p = 0.01, respectively). Serum levels of IL-31 were significantly elevated in psoriasis patients (p < 0.000001), however, they did not correlate with the studied polymorphic variants of the IL-31 gene, severity of psoriasis, disease onset, presence of psoriatic arthritis and pruritus intensity.

Conclusions

Distinct IL-31 promoter gene polymorphisms may be involved in psoriasis development. It seems that serum concentration of IL-31 may not be a reliable marker of psoriatic pruritus.

Production of IL-31 in CD45RO+CLA+H4R+ T Cells in Atopic Dermatitis

IL-31 is involved in pruritus in atopic dermatitis (AD) and the pathogenesis of AD. However, the mechanism of IL-31 production is not fully understood. We sought to investigate the association between CD45RO⁺CLA⁺H4R⁺ T cells and IL-31 production. Immunofluorescence studies were performed retrospectively on punch-biopsy specimens from five people with AD and three healthy controls. In addition, blood samples were collected prospectively from eight patients with AD and eight healthy controls for sorting CD45RO⁺CLA⁺H4R⁺ T cells. There was no overlap of patients between the biopsy group and the blood sampling group. Sorted cells were stimulated with 4-methylhistamine (4MH), and the level of IL-31 was measured by an enzyme-linked immunosorbent assay. Immunofluorescence showed co-localization of H4R and IL-31 in lesional AD skin but not in normal skin of healthy controls. The proportion of CLA⁺H4R⁺ T cells among CD3⁺CD45RO⁺ lymphocytes was 18.3 ± 6.2% in patients with AD and 11.2 ± 7.6% in healthy controls. In the AD group, production of IL-31 by CD45RO⁺CLA⁺H4R⁺ T cells increased from 32.4 ± 13.3 pg/mL to 47.5 ± 18.7 pg/mL by 4MH stimulation after 24 h (p < 0.001). However, in the control group, production of IL-31 was 20.1 ± 10.6 pg/mL without and 22.1 ± 9.3 pg/mL with 4MH stimulation (p > 0.05). According to our study, CD45RO⁺CLA⁺H4R⁺ T cells are an important source of IL-31 in AD, and may be a target for treatment of IL-31-induced pruritus.

Interleukin-31 and Pruritic Skin

Skin inflammation often evokes pruritus, which is the major subjective symptom in many inflammatory skin diseases such as atopic dermatitis and prurigo nodularis. Pruritus or itch is a specific sensation found only in the skin. Recent studies have stressed the pivotal role played by interleukin-31 (IL-31) in the sensation of pruritus. IL-31 is produced by various cells including T helper 2 cells, macrophages, dendritic cells and eosinophils. IL-31 signals via a heterodimeric receptor composed of IL-31 receptor A (IL-31RA) and oncostatin M receptor β. Recent clinical trials have shown that the anti-IL-31RA antibody nemolizumab can successfully decrease pruritus in patients with atopic dermatitis and prurigo nodularis. The IL-31 pathway and pruritic skin are highlighted in this review article.

Interleukin-31, a Potent Pruritus-Inducing Cytokine and Its Role in Inflammatory Disease and in the Tumor Microenvironment

Substantial new information has emerged supporting the fundamental role of the cytokine interleukin-31 (IL-31) in the genesis of chronic pruritus in a broad array of clinical conditions. These include inflammatory conditions, such as atopic dermatitis and chronic urticaria, to autoimmune conditions such as dermatomyositis and bullous pemphigoid, to the lymphoproliferative disorders of Hodgkin's disease and cutaneous T-cell lymphoma. IL-31 is produced in greatest quantity by T-helper type 2 (Th2) cells and upon release, interacts with a cascade of other cytokines and chemokines to lead to pruritus and to a proinflammatory environment, particularly within the skin. Antibodies which neutralize IL-31 or which block the IL-31 receptor may reduce or eliminate pruritus and may diminish the manifestations of chronic cutaneous conditions associated with elevated IL-31. The role of IL-31 in these various conditions will be reviewed.

Keratinocytes-Derived Reactive Oxygen Species Play an Active Role to Induce Type 2 Inflammation of the Skin: A Pathogenic Role of Reactive Oxygen Species at the Early Phase of Atopic Dermatitis

Background

Atopic dermatitis (AD) is characterized by chronic, relapsing skin inflammation (eczema) with itchy sensation. Keratinocytes, which are located at the outermost part of our body, are supposed to play important roles at the early phase of type 2 inflammation including AD pathogenesis.

Objective

The purpose of this study was to evaluate whether keratinocytes-derived reactive oxygen species (ROS) could be produced by the allergens or non-allergens, and the keratinocytes-derived ROS could modulate a set of biomarkers for type 2 inflammation of the skin.

Methods

Normal human epidermal keratinocytes (NHEKs) were treated with an allergen of house dust mites (HDM) or a non-allergen of compound 48/80 (C48/80). Then, biomarkers for type 2 inflammation of the skin including those for neurogenic inflammation were checked by reverse transcriptase-polymerase chain reaction and western immunoblot experiments.

Results

HDM or C48/80 was found to upregulate expression levels of our tested biomarkers, including type 2 T helper-driving pathway (KLK5, PAR2, and NFκB), epithelial-cell-derived cytokines (thymic stromal lymphopoietin, interleukin [IL]-25, IL-33), and neurogenic inflammation (NGF, CGRP). The HDM- or C-48/80-induced expression levels of the biomarkers could be blocked by an antioxidant treatment with 5 mM N-acetyl-cysteine. In contrast, pro-oxidant treatment with 1 mM H₂O₂ could upregulate expression levels of the tested biomarkers in NHEKs.

Conclusion

Our results reveal that keratinocytes-derived ROS, irrespective to their origins from allergens or non-allergens, have a potential to induce type 2 inflammation of AD skin.

IL-33/IL-31 Axis in Osteoporosis

The study of the immunoskeletal interface has led to the discovery of numerous cytokines involved in the regulation of bone remodeling, providing valuable information on the pathogenesis of osteoporosis. The role of inflammatory cytokines of the Th1 and Th17 profile in osteoporosis is well known. Here we focus on two newly discovered Th2 cytokines, IL-31 and IL-33, whose implications in osteoporosis are recently emerging. Clinical and experimental observations suggest an important role of the IL-33/IL-31 axis in osteoporosis. IL-33 induces IL-31 secretion by Th2 cells and inhibits RANKL-dependent osteoclastogenesis, thus counteracting bone loss. IL-31 influences Th1/Th17 osteoclastogenetic inflammation and limits Th2 osteoprotective processes, thus favoring osteoporosis. Better knowledge of the role of IL-31 and IL-33 and their receptor complexes in osteoporosis could provide an interesting perspective for the development of new and more effective therapies, possibly with less side effects.

Bifonazole Exerts Anti-Inflammatory Effects in Human Three-Dimensional Skin Equivalents after UVB or Histamine Challenge

BACKGROUND

In addition to its role as a broad-spectrum imidazole antifungal drug, data from animal models as well as human clinical trials also demonstrated an anti-inflammatory efficacy of bifonazole (BFZ). In the histamine wheal test and after UV radiation, BFZ showed antiphlogistic effects that were comparable to those of hydrocortisone. However, the underlying molecular mechanisms of the anti-inflam-matory properties of BFZ are poorly understood.

METHODS

Performing an in vitro study we used full-thickness three-dimensional (3D) skin models containing macrophages as mediators of inflammation. We conducted two sets of experiments. In a first set we exposed our models to UVB irradiation to provoke an inflammation. A second approach used the addition of histamine into the culture medium. In both approaches, models were treated topically with a BFZ-containing ointment or a placebo ointment for 24 h, and then the effects were examined histologically as well as with microarray and quantitative real-time PCR analyses.

RESULTS

Histological examination showed that the BFZ-containing ointment reconstituted UVB- and histamine-mediated disorders within the skin models. Performing gene expression profiling in models that were treated with the BFZ-containing ointment after UVB irradiation, we detected an upregu-lation of differentiation markers (fillagrin, loricrin, and keratin 1), antimicrobial peptides (DEFB103A), and members of the cytochrome P450 family (CYP1A1 and CYP1B1) as well as a downregulation of genes that are involved in immune response (CCL22, CXCL12, CCL7, IRF1, ICAM1, TLR3, and RARRES3) and matrix metalloproteinases (MMP12 and MMP7). Models that were treated with the BFZ-containing ointment after histamine application showed an upregulation of members of the cytochrome P450 family (CAP1A1, CYP1B1, and CYP24A1) and a downregulation of immune response-associated genes (CXCL6, CXCL12, CCL8, IL6, and IL32).

CONCLUSION

We present the first in vitro study showing anti-inflammatory effects of BFZ in human 3D skin models. To our knowledge, this is the first time that these effects could be translated from human clinical trials into an in vitro test system, allowing a more detailed examination of molecular mechanisms that were regulated by BFZ.

Pruritus in ordinary scabies: IL-31 from macrophages induced by overexpression of thymic stromal lymphopoietin and periostin

BACKGROUND

Scabies is a common contagious skin disease caused by an infestation of the skin by Sarcoptes scabiei var. hominis. A hallmark symptom of scabies is severe itch.

METHODS

We sought to determine the generation of a pruritogenic cytokine, interleukin (IL)-31, together with immune profiles in skin lesions of ordinary scabies through immunohistochemical and immunofluorescent studies. To elucidate the pathological mechanisms of IL-31 generation, murine peritoneal macrophages were stimulated with various T helper 2 (Th2) cytokines and proteins ex vivo.

RESULTS

A large number of CCR4(+) Th2 cells, eosinophils, and basophils infiltrated in scabies lesions. Increased generation of IL-31, thymic stromal lymphopoietin (TSLP), and periostin was also observed. A major population of IL-31(+) cells were Arginase-1(+)/CD163(+) M2 macrophages. Murine peritoneal macrophages showed an M2 phenotype and generated IL-31 when stimulated with TSLP and periostin.

CONCLUSION

IL-31 appeared to be largely generated by M2 macrophages in ordinary scabies lesions. This IL-31 induction was mediated by TSLP and periostin.

Is there still a role for UV therapy in itch treatment?

Itching is a frequent and greatly distressing symptom related to many skin and systemic diseases. New insights into the pathophysiology of itchy skin and potentially involved mediators have increased the interest in and development of new treatments that specifically act on targets involved in the transmission and perception of itching. Phototherapy has long been known and used as an effective treatment for various kinds of chronic itching. However, despite its well-known beneficial effects, the mechanisms behind the antipruritic effect of phototherapy are less well-known. In addition, phototherapy requires the use of expensive equipment in dermatology offices, patients must undergo repeated treatments and no large, randomized, controlled trials have yet supported the antipruritic effect of UV. Therefore, phototherapy is rarely recommended as a treatment method for chronic pruritic diseases or only used as a last recourse. However, the wide range of pruritic conditions that can be successfully treated with phototherapy, together with its low acute side effects, extremely low frequency of interactions with other medications, possibilities to combine phototherapy with other treatment modalities and the fact that patients of almost all ages-from childhood to old age, including women during pregnancy or lactation-can be treated make UV therapy advantageous over other treatments of chronic pruritus. Thus, despite the development of new targeted therapies against pruritus, UV therapy is neither outdated nor the 'last recourse', but should be considered early on in the treatment of chronic pruritus.

Altered Gene Expression in Dioxin-Like and Non-Dioxin-Like PCB Exposed Peripheral Blood Mononuclear Cells

Polychlorinated biphenyls (PCBs) are well known carcinogenic persistent environmental pollutants and endocrine disruptors. Our aim was to identify the possible dysregulation of genes in PCB exposed peripheral blood mononuclear cells (PBMCs) in order to give more insight into the differential pathophysiological effects of PCB congeners and mixtures, with an emphasis on immunological effects and oxidative stress. The PBMCs of a healthy volunteer (male, 56 years old) were exposed to a mixture of dioxin-like (DL)-PCBs (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189, 250 µg/L resp.) or non-dioxin-like (NDL)-PCBs (PCB 28, 52, 101, 138, 153, 180, 250 µg/L resp.) or single PCB congener (no.28, 138, 153, 180, 250 µg/L resp.). After an incubation period of 24 h, a microarray gene expression screening was performed, and the results were compared to gene expression in control samples (PBMCs treated with the vehicle iso-octane). Treatment of PBMCs with the DL-PCB mixture resulted in the largest number of differentially regulated genes (181 upregulated genes >2-fold, 173 downregulated >2-fold). Treatment with the NDL-PCB mix resulted in 32 upregulated genes >2-fold and 12 downregulated genes >2-fold. A gene set enrichment analysis (GSEA) on DL-PCB treated PBMCs resulted in an upregulation of 125 gene sets and a downregulation of 76 gene sets. Predominantly downregulated gene sets were involved in immunological pathways (such as response to virus, innate immune response, defense response). An upregulation of pathways related to oxidative stress could be observed for all PCB congeners except PCB-28; the latter congener dysregulated the least number of genes. Our experiment augments the information known about immunological and cellular stress responses following DL- as well as NDL-PCB exposure and provides new information on PCB 28. Further studies should be performed to evaluate how disruption of these pathways contributes to the development of autoimmune diseases and cancer.

Interleukin-31 and interleukin-31 receptor: New therapeutic targets for atopic dermatitis

Atopic dermatitis (AD) is characterized by chronic, eczematous, severe pruritic skin lesions caused by skin barrier dysfunction and T helper (Th)2 cell-mediated immunity. Interleukin (IL)-31 is a potent pruritogenic cytokine primarily produced by Th2 cells. Both IL-31 transgenic mice and wild-type mice treated with IL-31 exhibit AD-like skin lesions and scratching behaviour. IL-31 receptor α-chain (IL-31RA) is also expressed in peripheral nerves and epidermal keratinocytes, and the roles of IL-31 on pruritus and skin barrier have been investigated. Recently, an anti-IL-31 receptor antibody was shown to significantly improve pruritus in AD patients. This review focuses on IL-31 and IL-31RA in AD.

Correlation of IL-31 gene polymorphisms with susceptibility and clinical recurrence of bladder cancer

Interleukin-31 is a crucial cytokine triggering inflammation which could be one of the risk factors of tumors. However, data for correlation between IL-31 and tumors are limited. The purpose of our study was to discuss whether genetic polymorphisms of IL-31 were associated with the susceptibility and clinical outcomes of bladder cancer. Our study enrolled 478 controls, 156 non-muscle-invasive bladder cancer (NMIBC) and 138 muscle-invasive bladder cancer (MIBC) patients. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used for genotyping two single nucleotide polymorphisms (SNPs) of IL-31 gene including rs7977932 and rs4758680. Our results showed that A allele and CA/AA genotypes of rs4758680 were associated with susceptibility to bladder cancer (P = 0.04, OR 1.32, 95% CI 1.01-1.72, and P = 0.02, OR 1.43, 95% CI 1.05-1.96, respectively), and G allele of rs7977932 might be a protect factor for tobacco smoking patients compared with non-smoking patients (P = 0.005, OR 0.42, 95% CI 0.23-0.76). Furthermore, CA/AA genotypes of rs4758680 might be the independent risk factors for the decreased recurrence-free survival of the patients with MIBC (P = 0.03, OR 2.02, 95% CI 1.06-3.85. Our data indicated that polymorphisms of IL-31 are associated with bladder cancer, and rs4758680 could be an independent prediction for MIBC patients with a high risk of recurrence.

IL-31 plays dual roles in lung inflammation in an OVA-induced murine asthma model

Interleukin 31 (IL-31) is a four-helix cytokine made predominantly by Th2 CD4⁺ T cells. It was initially identified as being associated with the promotion of atopic dermatitis, where increased levels of IL-31 levels have been found and IL-31 induced the expression of proinflammatory cytokines and chemokines in a human bronchial epithelial cell line. However, subsequent study has shown that IL-31RA knockout mice developed exacerbated type 2 inflammation in the lung following infection with Schistosoma mansoni eggs. In this study, we investigated the dynamic expression of IL-31 and IL-31RA during eight consecutive ovalbumin (OVA) challenges and measured the chemokines from lung alveolar epithelial cells induced by IL-31. In addition, we examined the effect deletion of IL-31RA has on lung inflammation and the differentiation of CD4⁺ T cells. Our results demonstrate that the expression of IL-31 and IL-31RA was elevated after each weekly OVA challenge, although slightly less of both observed after the first week of OVA challenge. IL-31 also promoted the expression of inflammatory chemokines CCL5, CCL6, CCL11, CCL16, CCL22, CCL28, CX3CL1, CXCL3, CXCL14 and CXCL16 in alveolar epithelial cells. Migration of macrophages and T cells was enhanced by culture supernatants of IL-31-stimulated alveolar epithelial cells. Lastly, and in contrast to the IL-31 results, mice deficient in IL-31RA developed exacerbated lung inflammation, increased IL-4-positive cell infiltrates and elevated Th2 cytokine responses in draining lymph nodes. The proliferation of IL-31RA^-/- CD4⁺ T cells was enhanced in vitro after anti-CD3/anti-CD28 antibody stimulation. These data indicate that IL-31/IL-31RA may play dual roles, first as an early inflammatory mediator promoting the secretion of chemokines to recruit inflammatory cells, and subsequently as a late inflammatory suppressor, limiting Th2 cytokine responses in allergic asthma.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.

Expression of CYP1A1, CYP1B1 and IL-1β in PBMCs and skin samples of PCB exposed individuals

Polychlorinated biphenyls (PCBs) are well- known man-made persistent environmental pollutants and endocrine disruptors. As a result of mass production in the past, background levels of these compounds can be measured in human blood worldwide. In 2010 high internal levels of PCBs were discovered in workers of a transformer-recycling company in Germany. Our aim was to measure, whether the expression of CYP1A1, CYP1B1, and IL-1β is dysregulated in peripheral blood mononuclear cells (PBMCs) of the exposed individuals (n = max 308). Further, we measured the regulation of CYP1A1, CYP1B1, AHRR (aromatic hydrocarbon receptor repressor) and IL-1β in skin samples of 25 workers with elevated plasma PCB levels using quantitative PCR (q-RT-PCR). We found a significant correlation between the regulation of IL-1β in skin samples and lipid adjusted PCB levels. In the PBMCs, the expression levels of CYP1A1, CYP1B1 and IL-1β decreased over time with decreasing PCB plasma levels. The upregulation of the cytokine IL-1β in exposed individuals with higher PCB plasma levels warrants further investigation in order to examine its role in the pathophysiology of autoimmune disorders and tumor promotion.

Itch in dermatomyositis: the role of increased skin interleukin-31

BACKGROUND

Interleukin (IL)-31 is implicated in pruritus associated with pruritic skin diseases like atopic dermatitis. Although pruritus is a prominent feature in dermatomyositis (DM), few studies have evaluated the pathogenesis of DM-associated itch.

OBJECTIVES

To establish the prevalence of itch in DM, and to investigate the role of IL-31 in DM-related itch.

METHODS

Pruritus and disease activity of DM were evaluated by a visual analogue scale (VAS) and the Cutaneous Disease and Activity Severity Index (CDASI), respectively. Expression of IL-31 and IL-31 receptor alpha (IL-31RA) in lesional DM, nonlesional DM and healthy control skin was evaluated by quantitative reverse-transcriptase polymerase chain reaction and immunofluorescence. Flow cytometry was performed on skin cells isolated from lesional DM skin to identify cellular sources of IL-31 in DM.

RESULTS

Among 191 patients with DM, 50·8% had moderate-to-severe itch, and itch was correlated with increased cutaneous severity (r = 0·34). In patients with itchy DM, gene expression of IL31 and IL31RA in lesional skin was upregulated compared with nonlesional skin and healthy control skin. IL31 mRNA expression positively correlated with VAS itch score (r = 0·67). On immunofluorescence, immunoreactivity for IL-31 and IL-31RA was stronger in lesional skin. Flow cytometry showed that lesional DM skin contained significantly more IL-31-producing cells, and CD4⁺ cells were the most common cell type. Lenabasum, an emerging treatment for DM, significantly downregulated IL-31 from CpG-stimulated peripheral blood mononuclear cells.

CONCLUSIONS

Increased skin IL-31 may play a role in DM-associated itch, and ongoing trials will evaluate the effects of systemic treatment on IL-31 and itch in DM.

IL-31 is crucial for induction of pruritus, but not inflammation, in contact hypersensitivity

IL-31, which is a member of the IL-6 family of cytokines, is produced mainly by activated CD4⁺ T cells, in particular activated Th2 cells, suggesting a contribution to development of type-2 immune responses. IL-31 was reported to be increased in specimens from patients with atopic dermatitis, and IL-31-transgenic mice develop atopic dermatitis-like skin inflammation, which is involved in the pathogenesis of atopic dermatitis. However, the role of IL-31 in development of contact dermatitis/contact hypersensitivity (CHS), which is mediated by hapten-specific T cells, including Th2 cells, is not fully understood. Therefore, we investigated this using IL-31-deficient (Il31^−/−) mice, which we newly generated. We demonstrated that the mice showed normal migration and maturation of skin dendritic cells and induction of hapten-specific T cells in the sensitization phase of FITC-induced CHS, and normal induction of local inflammation in the elicitation phase of FITC- and DNFB-induced CHS. On the other hand, those mice showed reduced scratching frequency and duration during FITC- and/or DNFB-induced CHS. Our findings suggest that IL-31 is responsible for pruritus, but not induction of local skin inflammation, during CHS induced by FITC and DNFB.

IL-31: A new key player in dermatology and beyond

IL-31 is a novel cytokine expressed in many human tissues and involved mainly in T_H2-weighted inflammation. IL-31 signals through a receptor complex consisting of IL-31 receptor α and oncostatin M receptor β. The available data show that IL-31 is strongly linked with chronic pruritic skin disorders, such as atopic eczema, and represents a novel target for directed drug therapy. Regulation of immune responses and cellular differentiation and proliferation are recently elucidated effects of IL-31, suggesting a more complex and diverse area of effect for this novel cytokine. This review summarizes the current knowledge on IL-31 and its receptors and the involvement of IL-31 in diseases both in human subjects and mouse models.

Interleukin-31 and thymic stromal lymphopoietin expression in plasma and lymph node from Hodgkin lymphoma patients

Hodgkin Lymphoma (HL) is a tumor of B-cell origin characterized by Hodgkin and Reed-Stenberg (H/RS) cells embedded in an inflammatory tissue where numerous cytokines/chemokines contribute to shape the microenvironment, leading to the typical clinical symptoms.

We investigated: i) the expression of Interleukin-IL-31 (IL-31) and Thymic Stromal Lymphopoietin (TSLP), two Th2-related cytokines with tumor-promoting and pruritogenic functions, and of the respective receptors in HL invaded lymph nodes by flow cytometry, and ii) the potential association of IL-31/TSLP plasma concentrations with clinical characteristics by ELISA.

H/RS cells and the major immune cell types infiltrating HL lymph nodes expressed intracytoplasmic and surface IL-31/TSLP, and their receptors. A subgroup of patients showing at diagnosis elevated IL-31 and TSLP plasma levels had an International Prognostic Score>2, indicative of high risk of relapse, and a subsequent positive interim PET-scan, indicative of insufficient response to chemotherapy. No correlation was found between IL-31/TSLP plasma levels and overall or event-free survival.

In conclusion, IL-31/TSLP and their receptors are expressed in HL cells and in immune cells infiltrating affected lymph nodes, where both cytokines may contribute to local immune suppression. The clinical impact of IL-31 and TSLP plasma levels has to be further defined in larger patient cohorts.

The IL-31/IL-31 receptor axis: general features and role in tumor microenvironment

IL-31 is a recently identified cytokine with a well-defined role in the pathogenesis of pruritus. IL-31, whose production is induced by IL-4 and IL-33, binds a heterodimeric receptor (R) composed of the exclusive IL-31RA chain and the shared oncostatin M R. Signaling through the IL-31R involves the MAPK, PI3K/AKT and Jak/STAT pathways. Different variants and isoforms of IL-31RA with different signaling activities have been identified. IL-31 is produced predominantly by circulating Th2 lymphocytes and skin-homing CLA⁺CD45RO⁺ T cells. Studies in humans have demonstrated a pathogenic role for IL-31 in atopic dermatitis and allergic asthma. The first demonstration of the involvement of the IL-31/IL-31R axis in cancer came from studies in patients with mycosis fungoides/Sézary syndrome, the most frequent, cutaneous T cell lymphoma. Tumor cells were shown to produce IL-31, whose serum levels correlated with pruritus intensity. Follicular lymphoma (FL) B cells and their counterparts-germinal center B cells-produced IL-31 and expressed IL-31R, which signaled in the former, but not the latter, cells. IL-31 released in association with microvesicles promoted tumor growth through autocrine/paracrine loops. Malignant mast cells from patients with mastocytosis or Philadelphia-negative myeloproliferative disorder produced IL-31, which contributed to pruritus pathogenesis. Finally, patients with endometrial carcinoma displayed high serum levels of IL-31 and IL-33, which may represent promising disease biomarkers. Targeting strategies for the IL-31/IL-31R axis have been developed, including the CIMM331 humanized anti-human IL-31RA antibody recently tested in a phase I/Ib study.

Interleukin-31 pathway and its role in atopic dermatitis: a systematic review

BACKGROUND

Atopic dermatitis, a chronic inflammatory disease, has a lifetime prevalence of 10-20%. Atopic dermatitis reduces quality of life, primarily due to pruritus. Interleukin-31 and its target receptor are newly discovered entities that are involved in pruritus.

PURPOSE

To summarize the current understanding of interleukin-31 and its role in atopic dermatitis, potential therapeutic interventions and future prospects.

METHODS

A systematic review was designed to identify articles related to interleukin-31 and its role in pruritus. Predefined queries containing interleukin-31 and related key terms were searched with no past date restriction, through 31 August 2016, using MEDLINE, Cochrane Controlled Trials Register, ClinicalTrials.gov and the International Clinical Trials Registry Platform Search Portal database.

RESULTS

Of 151 identified articles, 61 met eligibility criteria. Interleukin-31 receptors are expressed constitutively on the surface of keratinocytes, eosinophils and small diameter neurons. Overexpression of interleukin-31, independent of mast cells and lymphocytes, induces clinical and histological features consistent with atopic dermatitis. In addition, overexpression of interleukin-31 causes reversible alopecia. Human monoclonal interleukin-31 antagonist, CIM331, decreased pruritus in phase-I and phase-II clinical trials.

CONCLUSIONS

Interleukin-31 plays an important role in atopic dermatitis and alopecia. Inhibiting this pathway may provide an alternative to antihistamines for the pruritus of atopic dermatitis.

Zinc Oxide Nanoparticle-Poly I:C RNA Complexes: Implication as Therapeutics against Experimental Melanoma

There is current interest in harnessing the combined anticancer and immunological effect of nanoparticles (NPs) and RNA. Here, we evaluate the bioactivity of poly I:C (pIC) RNA, bound to anticancer zinc oxide NP (ZnO-NP) against melanoma. Direct RNA association to unfunctionalized ZnO-NP is shown by observing change in size, zeta potential, and absorption/fluorescence spectra upon complexation. RNA corona was visualized by transmission electron microscopy (TEM) for the first time. Binding constant (K_b = 1.6-2.8 g^-1 L) was determined by modified Stern-Volmer, absorption, and biological surface activity index analysis. The pIC-ZnO-NP complex increased cell death for both human (A375) and mouse (B16F10) cell lines and suppressed tumor cell growth in BALB/C-B16F10 mouse melanoma model. Ex vivo tumor analysis indicated significant molecular activity such as changes in the level of phosphoproteins JNK, Akt, and inflammation markers IL-6 and IFN-γ. High throughput proteomics analysis revealed zinc oxide and poly I:C-specific and combinational patterns that suggested possible utility as an anticancer and immunotherapeutic strategy against melanoma.

Possible Role of Interleukin-31/33 Axis in Imatinib Mesylate-Associated Skin Toxicity

Imatinib mesylate is a small-molecule tyrosine kinase inhibitor (TKi) designed to target c-ABL and BCR-ABL, approved for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. Adverse cutaneous reactions induced by imatinib are frequent, generally moderate, and dose-dependent. The aim of this work was to investigate the possible contribution of interleukin (IL)-33 and IL-31, cytokines involved in disorders associated with itching, in the pathogenesis of pruritus in a patient undergoing imatinib mesylate treatment. His IL-31 and IL-33 serum levels were significantly higher than in the control group (respectively 96.6 pg/mL vs. 7.623±7.681 pg/mL and 27.566 pg/mL vs. 6.170±7.060 pg/mL). In light of these findings, imatinib mesylate-related symptoms of dermatologic toxicities might be related to the release of IL-31 and IL-33. In particular, it is supposable that TKi usage could cause keratinocyte injury, the release of IL-33, and the consequent interaction with its receptor on mast cells that induces the secretion of several factors capable of causing skin manifestations, including IL-31, a known pruritus-inducing cytokine. This report, to the best of our knowledge, is the first work describing the possible involvement of the IL-31/IL-33 axis in the pathogenesis of skin side effects related to imatinib mesylate treatment.

Macrophage migration inhibitory factor protects from nonmelanoma epidermal tumors by regulating the number of antigen-presenting cells in skin

The response of the skin to harmful environmental agents is shaped decisively by the status of the immune system. Keratinocytes constitutively express and secrete the chemokine-like mediator, macrophage migration inhibitory factor (MIF), more strongly than dermal fibroblasts, thereby creating a MIF gradient in skin. By using global and epidermis-restricted Mif-knockout (Mif^-/- and K14-Cre^+/tg; Mif^fl/fl) mice, we found that MIF both recruits and maintains antigen-presenting cells in the dermis/epidermis. The reduced presence of antigen-presenting cells in the absence of MIF was associated with accelerated and increased formation of nonmelanoma skin tumors during chemical carcinogenesis. Our results demonstrate that MIF is essential for maintaining innate immunity in skin. Loss of keratinocyte-derived MIF leads to a loss of control of epithelial skin tumor formation in chemical skin carcinogenesis, which highlights an unexpected tumor-suppressive activity of MIF in murine skin.-Brocks, T., Fedorchenko, O., Schliermann, N., Stein, A., Moll, U. M., Seegobin, S., Dewor, M., Hallek, M., Marquardt, Y., Fietkau, K., Heise, R., Huth, S., Pfister, H., Bernhagen, J., Bucala, R., Baron, J. M., Fingerle-Rowson, G. Macrophage migration inhibitory factor protects from nonmelanoma epidermal tumors by regulating the number of antigen-presenting cells in skin.

Reactive Oxygen Species Regulate T Cell Immune Response in the Tumor Microenvironment

Reactive oxygen species (ROS) produced by cellular metabolism play an important role as signaling messengers in immune system. ROS elevated in the tumor microenvironment are associated with tumor-induced immunosuppression. T cell-based therapy has been recently approved to be effective for cancer treatment. However, T cells often become dysfunctional after reaching the tumor site. It has been reported that ROS participate extensively in T cells activation, apoptosis, and hyporesponsiveness. The sensitivity of T cells to ROS varies among different subsets. ROS can be regulated by cytokines, amino acid metabolism, and enzymatic activity. Immunosuppressive cells accumulate in the tumor microenvironment and induce apoptosis and functional suppression of T cells by producing ROS. Thus, modulating the level of ROS may be important to prolong survival of T cells and enhance their antitumor function. Combining T cell-based therapy with antioxidant treatment such as administration of ROS scavenger should be considered as a promising strategy in cancer treatment, aiming to improve antitumor T cells immunity.

Increased levels of interleukin 31 (IL-31) in osteoporosis

Background

Several inflammatory cytokines play a key part in the induction of osteoporosis. Until now, involvement of the Th2 cytokine interleukin-31 (IL-31) in osteoporosis hadn’t yet been studied. IL-31 is a proinflammatory cytokine mediating multiple immune functions, whose involvement in a wide range of diseases, such as atopic dermatitis, inflammatory bowel diseases and cutaneous lymphomas, is now emerging. Given the important role of IL-31 in inflammation, we measured its serum levels in postmenopausal osteoporotic patients.

Methods and results

In fifty-six postmenopausal females with osteoporosis and 26 healthy controls, bone mineral density (BMD) measurements were performed by using calcaneal quantitative ultrasound (QUS) technique, confirmed at the lumbar spine and hip by dual energy X-ray absorptiometry (DXA). Both patients and controls were divided according to age (less or more than 65 years) and disease severity (T-score levels and presence of fractures). Serum IL-31 levels were measured by ELISA technique. Osteoporotic patients exhibited elevated levels of serum IL-31 compared with healthy controls (43.12 ± 6.97 vs 29.58 ± 6.09 pg/ml; p < 0.049). IL-31 expression was higher in over 65 years old patients compared to age-matched controls (45 ± 11.05 vs. 17.92 ± 5.92; p < 0.01), whereas in younger subjects no statistically significant differences were detected between patients and controls (37.91 ± 6.9 vs 32.08 ± 8.2). No statistically significant differences were found between IL-31 levels in patients affected by mild (T-score > -3) compared to severe (T-score < -3) osteoporosis (59.17 ± 9.22 vs 37.91 ± 10.52), neither between fractured and unfractured osteoporotic women (33.75 ± 9.16 vs 51.25 ± 8.9).

Conclusions

We showed for the first time an increase of IL-31 serum levels in postmenopausal women with decreased BMD. Although they did not reflect the severity of osteoporosis and/or the presence of fractures, they clearly correlated with age, as reflected by the higher levels of this cytokine in aged patients.

The frequencies of haplotypes defined by three polymorphisms of the IL-31 gene: -1066, -2057, and IVS2+12 in Polish patients with atopic dermatitis

BACKGROUND

Severe pruritus is one of the cardinal symptoms of atopic dermatitis (AD). Recently, the interleukin (IL)-31 cytokine has been implicated in the induction and maintenance of severe pruritus and chronic skin inflammation in several pruritic skin diseases, including AD.

OBJECTIVE

We aimed to investigate the association of the IL-31 gene haplotypes with pruritus and severity of AD, as well as their correlation to the serum IL-31 levels.

METHODS

A total of 127 patients with AD and 96 healthy controls were analyzed for polymorphic variants of the IL-31 gene using an amplification refractory mutation system-polymerase chain reaction method. IL-31 haplotype frequencies were estimated with the use of tagging single nucleotide polymorphisms, expectation-maximization, and Excoffier-Laval-Balding algorithms. Serum IL-31 levels were measured using a standard enzyme-linked immunosorbent assay kit.

RESULTS

The frequency of AAG, AGA, AGG, and GAA haplotypes of the IL-31 gene was higher in patients with AD than in controls. The mean IL-31 levels in serum were lower in controls than in the patients (P < 0.00001) and were higher in those with severe vs. mild AD (P = 0.008). No correlation was found between IL-31 and the severity of pruritus. The haplotype AAA was associated with a high IL-31 serum level (P = 0.008) and with severe AD (high SCORing Atopic Dermatitis index) (P = 0.013). The haplotype GAA was associated with a severe form of pruritus (P = 0.016) and the haplotype GGG with the mild one (P = 0.07).

CONCLUSION

The results of this study suggest that the severity of AD in a Polish population is associated with some specific haplotypes of the IL-31 gene, which can indicate their prognostic role also renews the questions concerning the role of IL-31 in pruritus in AD.

NFAT1 and JunB Cooperatively Regulate IL-31 Gene Expression in CD4+ T Cells in Health and Disease

IL-31 is a key mediator of itching in atopic dermatitis (AD) and is preferentially produced by activated CD4+ T cells and Th2 cells. Although pathophysiological functions of IL-31 have been suggested in diverse immune disorders, the molecular events underlying IL-31 gene regulation are still unclear. In this study we identified the transcription start site and functional promoter involved in IL-31 gene regulation in mouse CD4+ T cells. TCR stimulation–dependent IL-31 expression was found to be closely linked with in vivo binding of NFAT1 and JunB to the IL-31 promoter. Although NFAT1 alone enhanced IL-31 promoter activity, it was further enhanced in the presence of JunB. Conversely, knockdown of either NFAT1 or JunB resulted in reduced IL-31 expression. NFAT1-deficient CD4+ T cells showed a significant defect in IL-31 expression compared with wild-type CD4+ T cells. In agreement with these findings, mice subjected to atopic conditions showed much higher levels of IL-31, which were closely correlated with a significant increase in the number of infiltrated NFAT1+CD4+ T cells into the AD ears. Amelioration of AD progression by cyclosporin A treatment was well correlated with downregulation of IL-31 expressions in CD4+ T cells and total ear residual cells. In summary, our results suggest a functional cooperation between NFAT1 and JunB in mediating IL-31 gene expression in CD4+ T cells and indicate that interference with this interaction or their activity has the potential of reducing IL-31–mediated AD symptoms.

The interleukin (IL)-31/IL-31R axis contributes to tumor growth in human follicular lymphoma

Interleukin (IL)-31A binds to an heterodimer composed of IL-31 receptor A (IL-31RA) and Oncostatin M Receptor (OSMR). The IL-31/IL-31R complex is involved in the pathogenesis of various skin diseases, including cutaneous T-cell lymphoma. No information is available on the relations between the IL-31/IL-31R complex and B-cell lymphoma. Here we have addressed this issue in follicular lymphoma (FL), a prototypic germinal center(GC)-derived B-cell malignancy. IL-31 enhanced primary FL cell proliferation through IL-31R-driven signal transducer and activator of transcription factor 1/3 (STAT1/3), extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation. In contrast, GC B cells did not signal to IL-31 in spite of IL-31R expression. GC B cells expressed predominantly the inhibitory short IL-31RA isoform, whereas FL cells expressed predominantly the long signaling isoform. Moreover, GC B cells lacked expression of other IL-31RA isoforms potentially involved in the signaling pathway. IL-31 protein expression was significantly higher in surface membrane than in cytosol of both FL and GC B cells. IL-31 was detected in plasma membrane microvesicles from both cell types but not released in soluble form in culture supernatants. IL-31 and IL-31RA expression was higher in lymph nodes from FL patients with grade IIIa compared with grade I/II, suggesting a paracrine and/or autocrine role of IL-31/IL-31RA complex in tumor progression through microvesicle shedding.

IL-33/IL-31 axis: a new pathological mechanisms for EGFR tyrosine kinase inhibitors-associated skin toxicity

The dermatologic side effects are the most common adverse effects associated with Epidermal Growth Factor Receptor tyrosine kinase inhibitors. Although the mechanisms underlying the development of the skin toxicity remain unclear, immunological mechanisms are considered to be involved. A possible correlation between plasma levels of certain cytokines and development of skin toxicity has been reported. The aim of this work was to investigate the possible contribution of IL-31 and IL-33, cytokines involved in disorders associated with itching, in the pathogenesis of pruritus in patients undergoing EGFR-TK inhibitors. We report a significant increase of IL-31 and IL-33 serum levels in a patient with a bronchioalveolar carcinoma, who had showed previous skin rash, xerosis, and pruritus during treatment with different EGFR-TK inhibitors. She developed intense iching during gefitinib therapy. Therefore, we had collected patient blood sample to evaluate IL-31 and IL-33 serum levels compared to controls, reporting a significant increase in serum of patient. In the light of these findings, EGFR-TK inhibitors-related symptoms of dermatologic toxicities might be related to the release of IL-31 and IL-33. In particular, it is supposable that EGFR-TK inhibitors could cause keratinocytes injury, the release of IL-33 and the consequent interaction with its receptor on mast cells, that induces the secretion of several factors capable to cause skin manifestations, included IL-31, a known pruritus-inducing cytokine. This report, to the best of our knowledge, is the first work describing a possible involvement of IL-31/IL-33 axis in the pathogenesis of skin side effects related to EGFR-TK inhibitors treatment.

Interleukin-31: a novel diagnostic marker of allergic diseases

Interleukin-31 (IL-31) is a newly discovered cytokine associated with chronic skin inflammation and pruritus. Patients with atopic dermatitis, chronic spontaneous urticaria, allergic contact dermatitis, prurigo nodularis, primary cutaneous lymphoma and mastocytosis exhibit increased serum levels of IL-31 protein and elevated IL-31 mRNA in the skin. Interestingly, in some of these diseases, IL-31 serum levels correlate with disease activity. In the present review, we particularly focus on studies investigating IL-31 as a novel diagnostic biomarker indicating the severity of allergic diseases. We highlight a recent study on IL-31 in mastocytosis, which reports on elevated serum levels of IL-31 in adults correlating with the severity of disease categories, tryptase levels and percentage of bone marrow infiltration. We conclude that growing knowledge about IL-31, its receptors and signaling pathways serves to better understand the pathogenesis of allergic diseases and may lead to the development of novel treatment approaches.