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Pustular psoriasis is a chronic inflammatory skin disease characterized by erythematous plaques with sterile pustules. It includes the distinct clinical entities generalized pustular psoriasis (GPP), acrodermatitis continua of Hallopeau (ACH) and palmoplantar pustular psoriasis (PPPP). Recently clarified pathomechanisms of pustular psoriasis indicate that hyperactivation of the skin innate immunity, including of the IL-1/IL-36 axis, plays an important role in the pathogenesis of pustular psoriasis. Autoinflammatory keratinization disease (AiKD) is the umbrella clinical entity for inflammatory keratinization disorders with genetic autoinflammatory pathomechanisms, and pustular psoriasis is a representative AiKD. To date, mutations/variants in five genes—IL36RN, CARD14, AP1S3, MPO and SERPINA3—have been reported to be genetic causative or predisposing factors for pustular psoriasis. The pathogenic mechanisms induced by the mutations/variants in these genes are all closely related to the excessive activation of skin innate immunity and autoinflammation. A number of biologics (e.g., tumor necrosis factor inhibitors, IL-17/IL-17 receptor inhibitors and IL-23 inhibitors) and granulocyte and monocyte adsorption apheresis are used to treat pustular psoriasis. Recently, based on novel information on the pathomechanisms of pustular psoriasis, which are mainly associated with autoinflammation, inhibitors of several pathogenic pathways, including of the IL-1, IL-36, IL-8 and granulocyte colony-stimulating factor signaling pathways, have been studied as emerging treatments.

Background. This article discusses issues of diagnosis and management of pustular psoriasis in a child associated with recurrent dermatomycosis, immunopathogenetic mechanisms of pustular psoriasis, its course and prognosis. Clinical Case Description. The clinical case of infiltrative-suppurative form of scalp microsporia in 11 years old child with long-term psoriasis vulgaris and its transformation to generalized pustular psoriasis (von Zumbusch) is described. The need of immunosuppressive therapy prescription for severe psoriasis was challenged with fungal skin infection as immune suppression would lead to its recurrent course. Conclusion. Combination treatment (systemic glucocorticosteroids, methotrexate, antibiotics, and griseofulvin) resulted in clinical and laboratory recovery for microsporia in a child with generalized pustular psoriasis.

Background: Psoriasis is a chronic inflammatory immune-mediated disease characterized by an increased rate of keratinocyte division. The results of recent studies have made it possible to establish that the cytokines of the IL-36 family occupy a significant place in the initiation and regulation of the inflammatory process in psoriasis. IL-36 is in an inactive form and proteolytic processing is required for its activation in the skin, which is possible with the participation of neutrophilic serine proteases. Localization of these enzymes in the upper layers of the epidermis suggests the clinical efficacy of a topical targeted drug that inhibits serine proteases, sivelestat. On the basis of this active substance, we have created a drug in an external dosage form and conducted an experimental study of its effectiveness on a laboratory model of psoriasis. Aims: to evaluate the therapeutic efficacy of sivelestat in a laboratory model of imiquimod-induced psoriasis. Materials and methods: In the experiment, 40 inbred BALB/c mice were used, which were randomized into 4 groups of 10 each. An imiquimod-induced model of psoriasis was used. Mice of group No. I - without therapy (control), No. II - ointment (vaseline) containing 1% sivelestat, No. III - cream (lanolin + olive oil + water in equal proportions) containing 1% sivelestat, No. IV - betamethasone cream dipropionate 0.05%. Clinical assessment of skin rashes was performed using the PASI-modified method (mPASI), as well as histological and immunohistochemical examination of the skin. Results: When evaluating clinical manifestations, it was found that the total mPASI index when using sivelestat cream decreased by 50%, and sivelestat ointment - by 36%. The histological examination showed that the thickness of the epidermis in the groups where the therapy was applied was 2.4-3.6 times less than in the control group. An immunohistochemical study of the skin found that after treatment with sivelestat, the number of CD3 + cells in the skin was 1.8-2.2 times less, and the level of proliferative activity (Ki-67 + cells) was 2.3-2.9 times less. lower than in the group without therapy Conclusions: On a laboratory model of imiquimod-induced psoriasis, it was found that a serine protease inhibitor (sivelestat) has a therapeutic efficacy comparable to a strong topical glucocorticosteroid drug (betamethasone dipropionate 0.05%). A pronounced resolution of the elements of the skin rash, a reduction in the thickness of the epidermis, a decrease in skin infiltration with T-lymphocytes and a normalization of the rate of cell division of the epidermis and dermis are shown. Suppression of the activity of IL-36-mediated inflammation in the skin by means of topical inhibitors of serine proteases is a promising new direction in the treatment of patients with psoriasis.

Introduction Palmoplantar pustulosis (PPP) is a chronic, inflammatory skin disease, with high disease burden, that is often refractory to treatment. There is a high unmet clinical need for the treatment of patients with PPP. The objectives of this study were to evaluate the safety and efficacy of spesolimab, a novel anti-interleukin-36 receptor antibody, in patients with PPP. Methods This was a phase IIa, multicenter, double-blind, randomized, placebo-controlled pilot study comparing 900 mg spesolimab (n = 19), 300 mg spesolimab (n = 19), and placebo (n = 21) administered intravenously every 4 weeks until week 12 in patients with PPP. The primary efficacy endpoint was the achievement of Palmoplantar Pustulosis Area and Severity Index 50 (PPP ASI50) at week 16, defined as achieving an ≥ 50% decrease from baseline PPP ASI. Results At week 16, 31.6% of patients in both spesolimab dose groups achieved PPP ASI50 versus 23.8% receiving placebo (risk difference 0.078; 95% confidence interval –0.190, 0.338). Thus, the primary endpoint was not met. Spesolimab was well tolerated with no clinically relevant treatment-emergent safety signals observed. Conclusions PPP severity declined over time in all treatment groups after the start of treatment, with a faster decline in the spesolimab arms than in the placebo arm, indicating a potential treatment effect for spesolimab. Limitations to the study included a small sample size and lower overall disease severity than expected at baseline. It is possible that the primary efficacy endpoint may have coincided with natural disease resolution in some patients. Further effects of the efficacy of spesolimab in PPP are being explored in a phase IIb trial. Supplementary Information The online version contains supplementary material available at 10.1007/s13555-021-00504-0.

Interleukin (IL)-36 is a recently described cytokine with well-known functions in the regulation of multiple inflammatory diseases. Since no data exists on how this cytokine regulates adipose tissue (AT) homeostasis, we aimed to explore the function of a specific isoform, IL-36γ, an agonist, in human obesity and obesity-associated type 2 diabetes as well as in AT inflammation and fibrosis. Plasma IL-36γ was measured in 91 participants in a case-control study and the effect of weight loss was evaluated in 31 patients with severe obesity undergoing bariatric surgery. Gene expression levels of IL36G and its receptor were analyzed in relevant human metabolic tissues. The effect of inflammatory factors and IL-36γ was determined in vitro in human adipocytes and macrophages. We found, for the first time, that the increased (PPIL36G were upregulated in the visceral AT (PPPIl36g in the epididymal AT from diet-induced obese mice. IL36G was significantly enhanced (PPPPCTSG) in monocyte-derived macrophages. These findings provide, for the first time, evidence about the properties of IL-36γ in the regulation of AT-chronic inflammation, emerging as a link between AT biology and the obesity-associated comorbidities.

The interleukin-1 (IL-1) family is involved in the correct functioning and regulation of the innate immune system, linking innate and adaptative immune responses. This complex family is composed by several cytokines, receptors, and co-receptors, all working in a balanced way to maintain homeostasis. Dysregulation of these processes results in tissue inflammation and is involved in the pathogenesis of common inflammatory dermatoses such as psoriasis, hidradenitis suppurativa, and atopic dermatitis. Therefore, therapeutic targeting of IL-1 pathways has been studied, and several monoclonal antibodies are currently being assessed in clinical trials. So far, promising results have been obtained with anti-IL-36R spesolimab and imsidolimab in pustular psoriasis, and their efficacy is being tested in other conditions.

Trained immunity is the process of long-term functional reprogramming (a de facto innate immune memory) of innate immune cells such as monocytes and macrophages after an exposure to pathogens, vaccines, or their ligands. The induction of trained immunity is mediated through epigenetic and metabolic mechanisms. Apart from exogenous stimuli, trained immunity can be induced by endogenous compounds such as oxidized LDL, urate, fumarate, but also cytokines including IL-1α and IL-1β. Here, we show that also recombinant IL-36γ, a pro-inflammatory cytokine of the IL-1-family, is able to induce trained immunity in primary human monocytes, demonstrated by higher cytokine responses and an increase in cellular metabolic pathways both regulated by epigenetic histone modifications. These effects could be inhibited by the IL-36 receptor antagonist as well as by IL-38, an anti-inflammatory cytokine of the IL-1 family which shares its main receptor with IL-36 (IL-1R6). Further, we demonstrated that trained immunity induced by IL-36γ is mediated by NF-κB and mTOR signaling. The inhibitory effect of IL-38 on IL-36γ-induced trained immunity was confirmed in experiments using bone marrow of IL-38KO and WT mice. These results indicate that exposure to IL-36γ results in long-term pro-inflammatory changes in monocytes which can be inhibited by IL-38. Recombinant IL-38 could therefore potentially be used as a therapeutic intervention for diseases characterized by exacerbated trained immunity.

Background: CAR-T cells are chimeric antigen receptor (CAR)-T cells; they are target-specific engineered cells on tumor cells and produce T cell-mediated antitumor responses. CAR-T cell therapy is the “first-line” therapy in immunotherapy for the treatment of highly clonal neoplasms such as lymphoma and leukemia. This adoptive therapy is currently being studied and tested even in the case of solid tumors such as osteosarcoma since, precisely for this type of tumor, the use of immune checkpoint inhibitors remained disappointing. Although CAR-T is a promising therapeutic technique, there are therapeutic limits linked to the persistence of these cells and to the tumor’s immune escape. CAR-T cell engineering techniques are allowed to express interleukin IL-36, and seem to be much more efficient in antitumoral action. IL-36 is involved in the long-term antitumor action, allowing CAR-T cells to be more efficient in their antitumor action due to a “cross-talk” action between the “IL-36/dendritic cells” axis and the adaptive immunity. Methods: This analysis makes the model useful for evaluating cell dynamics in the case of tumor relapses or specific understanding of the action of CAR-T cells in certain types of tumor. The model proposed here seeks to quantify the action and interaction between the three fundamental elements of this antitumor activity induced by this type of adoptive immunotherapy: IL-36, “armored” CAR-T cells (i.e., engineered to produce IL-36) and the tumor cell population, focusing exclusively on the action of this interleukin and on the antitumor consequences of the so modified CAR-T cells. Mathematical model was developed and numerical simulations were carried out during this research. The development of the model with stability analysis by conditions of Routh–Hurwitz shows how IL-36 makes CAR-T cells more efficient and persistent over time and more effective in the antitumoral treatment, making therapy more effective against the “solid tumor”. Findings: Primary malignant bone tumors are quite rare (about 3% of all tumors) and the vast majority consist of osteosarcomas and Ewing’s sarcoma and, approximately, the 20% of patients undergo metastasis situations that is the most likely cause of death. Interpretation: In bone tumor like osteosarcoma, there is a variation of the cellular mechanical characteristics that can influence the efficacy of chemotherapy and increase the metastatic capacity; an approach related to adoptive immunotherapy with CAR-T cells may be a possible solution because this type of therapy is not influenced by the biomechanics of cancer cells which show peculiar characteristics.

A member of the interleukin (IL)-1 superfamily was IL-36, which contained IL-36α, IL-36β, IL-36γ, and IL-36Ra. Heterotrimer complexes, consisting of heterodimeric receptor complexes and IL-36 agonist, gave signals through intracellular functional domains, so as to bind to downstream proteins and induce inflammatory response. IL-36 agonists upregulated mature-associated CD80, CD86, MHCII, and inductively produced several pro-inflammatory cytokines through the IL-36R-dependent manner in dendritic cells (DCs). Besides, DCs had the ability to initiate the differentiation of helper T (Th) cells. Up to date, the role of IL-36 in immunity, inflammation and other diseases is of great importance. Additionally, autoimmune diseases were characterized by excessive immune response, resulting in damage and dysfunction of specific or multiple organs and tissues. Most autoimmune diseases were related to inflammatory response. In this review, we will conclude the recent research advances of IL-36 in the occurrence and development of autoimmune diseases, which may provide new insight for the future research and the treatment of these diseases.

International audience; Background: Netherton syndrome (NS) is a rare recessive skin disorder caused by loss-of-function mutations in SPINK5 encoding the protease inhibitor LEKTI (lymphoepithelial Kazal-type–related inhibitor). NS patients experience severe skin barrier defects, display inflammatory skin lesions, and have superficial scaling with atopic manifestations. They present with typical ichthyosis linearis circumflexa (NS-ILC) or scaly erythroderma (NS-SE). Objective: We used a combination of several molecular profiling methods to comprehensively characterize the skin, immune cells, and allergic phenotypes of NS-ILC and NS-SE patients. Methods: We studied a cohort of 13 patients comprising 9 NS-ILC and 4 NS-SE. Results: Integrated multiomics revealed abnormal epidermal proliferation and differentiation and IL-17/IL-36 signatures in lesion skin and in blood in both NS endotypes. Although the molecular profiles of NS-ILC and NS-SE lesion skin were very similar, nonlesion skin of each disease subtype displayed distinctive molecular features. Nonlesion and lesion NS-SE epidermis showed activation of the type I IFN signaling pathway, while lesion NS-ILC skin differed from nonlesion NS-ILC skin by increased complement activation and neutrophil infiltration. Serum cytokine profiling and immunophenotyping of circulating lymphocytes showed a TH2-driven allergic response in NS-ILC, whereas NS-SE patients displayed mainly a TH9 axis with increased CCL22/MDC and CCL17/TARC serum levels. Conclusions: This study confirms IL-17/IL-36 as the predominant signaling axes in both NS endotypes and unveils molecular features distinguishing NS-ILC and NS-SE. These results identify new therapeutic targets and could pave the way for precision medicine of NS.

Generalized pustular psoriasis (GPP) is a severe, relapsing, immune-mediated disease characterized by the presence of multiple sterile pustules all over the body. The exact pathomechanisms behind GPP remain elusive, although increased interest in the genetic basis and immunological disturbances have provided some revealing insights into the underlying signaling pathways and their mutual interaction. The genetic background of GPP has been thoroughly investigated over the past few years. The conducted studies have identified genetic variants that predispose to pustular forms of psoriasis. The loss-of-function mutation of the interleukin 36 receptor antagonist gene, along with rare gain-of-function mutations in the gene that encodes the keratinocyte signaling molecule (CARD14), are examples of the uncovered abnormalities. Interleukin 36 (IL-36), along with neutrophils, is now considered a central cytokine in GPP pathogenesis, with IL-36 signaling providing a link between innate and adaptive immune responses. More recently, a new concept of inflammation, caused by a predominantly genetically determined abnormal activation of innate immune response and leading to inflammatory keratinization, has arisen. GPP is currently considered a representative of this novel group of skin conditions, called autoinflammatory keratinization diseases. As no therapeutic agents have been approved for GPP to date in the United States and Europe, the novel anti-IL-36R antibodies are particularly promising and may revolutionize management of the disease.

Jing Guo,1,* Jie Tu,1,* YingYing Hu,1,2,* GuoXin Song,3 ZhiQiang Yin1 1Department of Dermatology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China; 2Department of Medical Cosmetology, Wuqing People’s Hospital, Wuqing, Tianjin, China; 3Department of Pathology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China *These authors contributed equally to this work Background: IL-36γ is considered to be a valuable biomarker in psoriatic patients, which is expressed as an inactive precursor that needs to be proteolytically processed and activated, and neutrophil-derived proteases seemed to be potent activating enzymes of IL-36γ. Objectives: This study aims to investigate the activation of IL-36γ by cathepsin G (CG) and neutrophil elastase (NE). Materials and methods: We used inactive recombinant full-length (FL)-IL-36γ with different doses of NE or CG to stimulate HaCaT cells; neutrophil extracellular traps (NETs) were prepared to act on FL-IL-36γ and then stimulate HaCaT cells. Real-time quantitative PCR and ELISA were performed to detect CXCL-1 and CXCL-8 expression. We developed imiquimod-induced psoriasis-like mouse model to evaluate the effect of hypodermic injection of neutrophil-derived protease or its inhibitor. Histopathology and Western blotting were conducted for effect assessment. Results: Purified CG cleaved and activated recombinant human FL-IL-36γ to promote CXCL-1 and CXCL-8 expression by human keratinocytes, and NETs activated FL-IL-36γ and the activation was inhibited by serpin A3. CG induced expression of a more truncated IL-36γ in psoriasiform lesion of mice and aggravated the psoriasis-like lesion induced by imiquimod, whereas recombinant serpin A3 alleviated the severity of the psoriasis-like mouse mode. Conclusion: CG has the ability to cleave and activate IL-36γ and aggravate imiquimod-induced mouse psoriasiform lesion. Thus, CG-specific inhibitors might be promising therapeutic drugs for psoriasis. Keywords: psoriasis, IL-36, neutrophil, cathepsin, elastase

IL-36 is a member of the interleukin 1 cytokine family, which is currently experiencing a renaissance due to the growing understanding of its context-dependent roles and advances in our understanding of the inflammatory response. The immunological role of IL-36 has revealed its profound and indispensable functional roles in psoriasis, as well as in several inflammatory diseases, including inflammatory bowel disease (IBD), systemic lupus erythematosus, rheumatoid arthritis (RA) and cancer. More recently, an increasing body of evidence suggests that IL-36 plays a crucial role in viral, bacterial and fungal infections. There is a growing interest as to whether IL-36 contributes to host protective immune responses against infection as well as the potential implications of IL-36 for the development of new therapeutic strategies. In this review, we summarize the recent progress in understanding cellular expression, regulatory mechanisms and biological roles of IL-36 in infectious diseases, which suggest more specific strategies to maneuver IL-36 as a diagnostic or therapeutic target, especially in COVID-19.

The interleukin (IL)-36 cytokine family plays an essential role in inflammatory processes in the skin and is implicated in the pathogenesis of psoriasis. This study explored the role of IL-36 in psoriasis and investigated the molecular mechanism involved in tumour necrosis factor-α (TNFα)/IL-17A-mediated IL-36 induction. In human keratinocytes IL-36 expression was strongly upregulated by combined TNFα and IL-17A stimulation. Moreover, IκBζ, encoded by NFKBIZ, was identified as a key regulator required for TNFα/IL-17A-induced IL-36γ expression. TNFα/IL-17A-induced IL-36γ expression also involved the nuclear factor κB (NF-κB), p38 mitogen-activated protein kinase and ERK1/2 signalling pathways. Furthermore, a specific NF-κB DNA-binding site in the promoter region of IL36G responsible for the TNFα/IL-17A-induced IL36G gene expression was identified. Finally, in a cohort of patients with psoriasis receiving anti-IL-17A treatment, a positive correlation was found between the expression of NFKBIZ and IL36G. In conclusion, these data reveal a novel crucial regulatory mechanism by which TNFα and IL-17A regulate IL-36γ expression.

Psoriasis is a chronic inflammatory skin condition that has a fairly wide range of clinical presentations. Plaque psoriasis, which is the most common manifestation of psoriasis, is located on one end of the spectrum, dominated by adaptive immune responses, whereas the rarer pustular psoriasis lies on the opposite end, dominated by innate and autoinflammatory immune responses. In recent years, genetic studies have identified six genetic variants that predispose to pustular psoriasis, and these have highlighted the role of IL-36 cytokines as central to pustular psoriasis pathogenesis. In this review, we discuss the presentation and clinical subtypes of pustular psoriasis, contribution of genetic predisposing variants, critical role of the IL-36 family of cytokines in disease pathophysiology, and treatment perspectives for pustular psoriasis. We further outline the application of appropriate mouse models for the study of pustular psoriasis and address the outstanding questions and issues related to our understanding of the mechanisms involved in pustular psoriasis.

Unmet needs in the treatment of psoriasis call for novel therapeutic strategies. Pustular psoriasis and psoriatic arthritis often represent a therapeutic challenge. Focus on IL-36 cytokines offers an interesting approach, as the IL-36 axis has been appointed a critical driver of the autoinflammatory responses involved in pustular psoriasis. Two IL-36R blocking antibodies, imsidolimab and spesolimab, are currently undergoing phase II and III clinical trials, with promising results.

As a severe complication of influenza infection, acute respiratory distress syndrome (ARDS) has higher morbidity and mortality. Although IL-36γ has been proven to promote inflammation at epithelial sites and protect against specific pathogen infection, the detailed roles in severe influenza infection remain poorly understood. In this study, we have found that the expression of IL-36γ is higher in influenza-induced ARDS patients than healthy individuals. IL-36γ was induced in human lung epithelial cells and peripheral blood mononuclear cells by Influenza A virus (IAV) infection, and its induction was synergistically correlated with initiation of the cyclooxygenase-2 (COX-2)/Prostaglandin E2 (PGE2) axis. We also have found that expression of superficial IL-36R was elevated in severe influenza patients and in IAV-stimulated cells. Furthermore, although IL-36γ enhanced the induction of type I and III interferons (IFNs), which promoted IAV-mediated IFN-stimulated STAT1 and STAT2 phosphorylated inhibition in lung epithelial cells, the downstream interferon-stimulated genes (ISGs) were not affected. Finally, we have revealed that IL-36γ treatment could promote apoptosis and inhibit autophagy in the early stages of IAV infection. Overall, these findings demonstrated IL-36γ is a critical host immune factor in response to IAV infection. It has potential activity in the regulation of the interferon signaling pathway and was involved in different types of programmed cell death in human airway epithelial cells as well.

Tissue fibrosis is a major unresolved medical problem, which impairs the function of various systems. The molecular mechanisms involved are poorly understood, which hinders the development of effective therapeutic strategies. Emerging evidence from recent studies indicates that interleukin 36 (IL-36) and the corresponding receptor (IL-36R), a newly-characterized cytokine/receptor signaling complex involved in immune-inflammation, play an important role in the pathogenesis of fibrosis in multiple tissues. This review focuses on recent experimental findings, which implicate IL-36R and its associated cytokines in different forms of organ fibrosis. Specifically, it outlines the molecular basis and biological function of IL-36R in normal cells and sums up the pathological role in the development of fibrosis in the lung, kidney, heart, intestine, and pancreas. We also summarize the new progress in the IL-36/IL-36R-related mechanisms involved in tissue fibrosis and enclose the potential of IL-36R inhibition as a therapeutic strategy to combat pro-fibrotic pathologies. Given its high association with disease, gaining new insight into the immuno-mechanisms that contribute to tissue fibrosis could have a significant impact on human health.

Summary Epithelial tissues represent vital interfaces between organisms and their environment. As they are constantly exposed to harmful pathogens, innocuous commensals, and environmental microbes, it is essential they sense and elicit appropriate responses toward these different types of microbes. Here, we demonstrate that the epithelial cytokine interleukin-36γ (IL-36γ) acts as a global discriminator of pathogenic and harmless microbes via cell damage and proteolytic activation. We show that intracellular pro-IL-36γ is upregulated by both fungal and bacterial epithelial microbes; yet, it is only liberated from cells, and subsequently processed to its mature, potent, proinflammatory form, by pathogen-mediated cell damage and pathogen-derived proteases. This work demonstrates that IL-36γ senses pathogen-induced cell damage and proteolytic activity and is a key initiator of immune responses and pathological inflammation within epithelial tissues. As an apically located epithelial proinflammatory cytokine, we therefore propose that IL-36γ is critical as the initial discriminator of harmless microbes and invasive pathogens within epithelial tissues., Graphical Abstract, Highlights • Epithelial pathogens induce expression and release of IL-36γ • Proteases secreted by several epithelial pathogens activate IL-36γ • The A. fumigatus and S. pyogenes virulence factors Asp F13 and SpeB activate IL-36γ • IL-36γ is a global sensor of pathogen-derived proteases during epithelial infection, Macleod et al. demonstrate that the epithelial cytokine IL-36γ discriminates between pathogens and harmless commensals at epithelial barriers. IL-36γ is upregulated by epithelial tissue following microbial challenge, but it is only released and activated by destructive pathogenic microbes, whereupon it initiates an immune response.

Despite the introduction of biologics, topical dithranol (anthralin) has remained one of the most effective anti-psoriatic agents. Serial biopsies from human psoriatic lesions and both the c-Jun/JunB and imiquimod psoriasis mouse model allowed us to study the therapeutic mechanism of this drug. Top differentially expressed genes in the early response to dithranol belonged to keratinocyte and epidermal differentiation pathways and IL-1 family members (i.e. IL36RN) but not elements of the IL-17/IL-23 axis. In human psoriatic response to dithranol, rapid decrease in expression of keratinocyte differentiation regulators (e.g. involucrin, SERPINB7 and SERPINB13), antimicrobial peptides (e.g. ß-defensins like DEFB4A, DEFB4B, DEFB103A, S100 proteins like S100A7, S100A12), chemotactic factors for neutrophils (e.g. CXCL5, CXCL8) and neutrophilic infiltration was followed with much delay by reduction in T cell infiltration. Targeting keratinocytes rather than immune cells may be an alternative approach in particular for topical anti-psoriatic treatment, an area with high need for new drugs.

Significance Psoriasis is an autoinflammatory disease characterized by cytokine-driven keratinocyte proliferation and infiltration of immune cells. While IL-17A and TNFα are established targets in psoriasis therapy, IL-36 is emerging as an important cytokine in this disease. The mechanisms of IL-36–driven proinflammatory responses are largely unknown. Here we identified IκBζ, a transcriptional regulator of selective NF-κB target genes, as a crucial mediator of IL-36 action. In keratinocytes, IκBζ was required for the expression of several psoriasis-related cytokines and chemokines. Moreover, genetic deletion of IκBζ prevented IL-36–mediated dermatitis induction in mice. Since IκBζ is essential not only for IL-36 but also for IL-17 signaling, our results suggest that inhibition of IκBζ function could be a future strategy in psoriasis therapy., Proinflammatory cytokine signaling in keratinocytes plays a crucial role in the pathogenesis of psoriasis, a skin disease characterized by hyperproliferation and abnormal differentiation of keratinocytes and infiltration of inflammatory cells. Although IL-17A and TNFα are effective therapeutic targets in psoriasis, IL-36 has recently emerged as a proinflammatory cytokine. However, little is known about IL-36 signaling and its downstream transcriptional responses. Here, we found that exposure of keratinocytes to IL-36 induced the expression of IκBζ, an atypical IκB member and a specific transcriptional regulator of selective NF-κB target genes. Induction of IκBζ by IL-36 was mediated by NF-κB and STAT3. In agreement, IL-36–mediated induction of IκBζ was found to be required for the expression of various psoriasis-related genes involved in inflammatory signaling, neutrophil chemotaxis, and leukocyte activation. Importantly, IκBζ-knockout mice were protected against IL-36–mediated dermatitis, accompanied by reduced proinflammatory gene expression, decreased immune cell infiltration, and a lack of keratinocyte hyperproliferation. Moreover, expression of IκBζ mRNA was highly up-regulated in biopsies of psoriasis patients where it coincided with IL36G levels. Thus our results uncover an important role for IκBζ in IL-36 signaling and validate IκBζ as an attractive target for psoriasis therapy.

IL-1 family cytokines act as apical initiators of inflammation in many settings and can promote the production of a battery of inflammatory cytokines, chemokines and other inflammatory mediators in diverse cell types. IL-36 alpha, IL-36 beta and IL-36 gamma, which belong to the extended IL-1 family, have been implicated as key initiators of skin inflammation in psoriasis. IL-36 gamma is highly upregulated in lesional skin from psoriatic individuals, and heritable mutations in the natural IL-36 receptor antagonist result in a severe form of psoriasis. IL-36 family cytokines are initially expressed as inactive precursors that require proteolytic processing for activation. The neutrophil granule-derived protease elastase proteolytically processes and activates IL-36 alpha and IL-36 gamma, increasing their biological activity similar to 500-fold, and also robustly activates IL-1 alpha and IL-33 through limited proteolytic processing. Consequently, inhibitors of elastase activity may have potential as anti-inflammatory agents through antagonizing the activation of multiple IL-1 family cytokines. Using in silico screening approaches, we have identified small-molecule inhibitors of elastase that can antagonize activation of IL-36 gamma by the latter protease. The compounds reported herein may have utility as lead compounds for the development of inhibitors of elastase-mediated activation of IL-36 and other IL-1 family cytokines in inflammatory conditions, such as psoriasis.

Interleukin (IL)-36 is a member of the IL-1 superfamily and includes three agonists (IL-36α, IL-36β, and IL-36γ) and an antagonist (IL-36Ra). IL-36 agonists bind to heterodimeric receptor complexes. Then, the heterotrimer complexes signal via intracellular functional domains, binding to downstream signaling proteins and inducing inflammatory responses. In this review, we summarized the current knowledge about the biological role of IL-36 and its correlation with systemic inflammatory diseases. The information collected will help to increase the understanding of the potential of IL-36 and may give clues for developing novel therapeutic strategies.

The IL-1 family of cytokines are well-known for their primary role in initiating inflammatory responses both in response to and acting as danger signals. It has long been established that IL-1 is capable of simultaneously regulating inflammation and angiogenesis, indeed one of IL-1's earliest names was haemopoeitn-1 due to its pro-angiogenic effects. Other IL-1 family cytokines are also known to have roles in mediating angiogenesis, either directly or indirectly via induction of proangiogenic factors such as VEGF. Of note, some of these family members appear to have directly opposing effects in different tissues and pathologies. Here we will review what is known about how the various IL-1 family members regulate vascular permeability and angiogenic function in a range of different tissues, and describe some of the mechanisms employed to achieve these effects.

Interleukin-1 (IL-1) family cytokines are key signaling molecules in both the innate and adaptive immune systems, mediating inflammation in response to a wide range of stimuli. The basic mechanism of signal initiation is a stepwise process in which an agonist cytokine binds its cognate receptor. Together, this cytokine-receptor complex recruits an often-common secondary receptor. Intracellularly, the Toll/IL-1 Receptor (TIR) domains of the two receptors are brought into close proximity, initiating an NF-κB signal transduction cascade. Due to the potent inflammatory response invoked by IL-1 family cytokines, several physiological mechanisms exist to inhibit IL-1 family signaling, including antagonist cytokines and decoy receptors. The numerous cytokines and receptors in the IL-1 superfamily are further classified into four subfamilies, dependent on their distinct cognate receptors-the IL-1, IL-33, and IL-36 subfamilies share IL-1RAcP as their secondary receptor, while IL-18 subfamily utilizes a distinct secondary receptor. Here, we describe how structural biology has informed our understanding of IL-1 family cytokine signaling, with a particular focus on molecular mechanisms of signaling complex formation and antagonism at the atomic level, as well as how these findings have advanced therapeutics to treat some chronic inflammatory diseases that are the result of dysregulated IL-1 signaling.

Identification of novel molecular adjuvants which can boost and enhance vaccine-mediated immunity and provide dose-sparing potential against complex infectious diseases and for immunotherapy in cancer is likely to play a critical role in the next generation of vaccines. Given the number of challenging targets for which no or only partial vaccine options exist, adjuvants that can address some of these concerns are in high demand. Here, we report that a designed truncated Interleukin-36 gamma (IL-36 gamma) encoded plasmid can act as a potent adjuvant for several DNA-encoded vaccine targets including human immunodeficiency virus (HIV), influenza, and Zika in immunization models. We further show that the truncated IL-36 gamma (opt-36&gamma, t) plasmid provides improved dose sparing as it boosts immunity to a suboptimal dose of a Zika DNA vaccine, resulting in potent protection against a lethal Zika challenge.

Interleukin-36 (IL-36) comprises to a cytokine family consisting of four isoforms IL-36α, IL-36β, IL-36γ, and IL-36 receptor antagonist (IL-36 Ra). These IL-36 cytokines, in turn, belong to the IL-1 superfamily. The IL-36 receptor (IL-1R6) is functional as a heterodimer formed of IL-1R6 and IL-1 receptor accessory protein (IL-1RAcP). IL-36α, IL-36β, and IL-36γ are regarded as pro-inflammatory ligands and IL-36 Ra as well as IL-38 as anti-inflammatory ligands of IL-1R6. IL-36 cytokines are mainly expressed on the barrier sites of the body e.g., bronchial, intestinal, and dermal epithelium. One of their most important biological functions is the bridging of innate and adaptive immune responses. A disturbed balance between pro-inflammatory and anti-inflammatory branches easily leads to inflammation of the corresponding tissue. The most prominent example for an altered IL-36 expression is the spectrum of psoriasis. In addition to inflammatory dermatoses, IL-36 also seems to play a role in infectious dermatoses. Microbial triggers, especially Staphylococcus aureus infection, increase the production of pro-inflammatory IL-36 cytokines and initiate/promote the inflammation of skin lesions. Due to the discovery of IL-36 as an important immune mediator, it has already been possible to develop important diagnostic tools for dermatitis. Not only in the field of inflammatory skin diseases, but also in pulmonary and intestinal inflammation, there is evidence that IL-36 cytokines might have diagnostic and/or therapeutic relevance.

Epidermal infiltration of neutrophils is a hallmark of psoriasis, where their activation leads to release of neutrophil extracellular traps (NETs). The contribution of NETs to psoriasis pathogenesis has been unclear, but here we demonstrate that NETs drive inflammatory responses in skin through activation of epidermal TLR4/IL-36R crosstalk. This activation is dependent upon NETs formation and integrity, as targeting NETs with DNase I or CI-amidine in vivo improves disease in the imiquimod (IMQ)-induced psoriasis-like mouse model, decreasing IL-17A, lipocalin2 (LCN2), and IL-36G expression. Proinflammatory activity of NETs, and LCN2 induction, is dependent upon activation of TLR4/IL-36R crosstalk and MyD88/nuclear factor-kappa B (NF-κB) down-stream signaling, but independent of TLR7 or TLR9. Notably, both TLR4 inhibition and LCN2 neutralization alleviate psoriasis-like inflammation and NETs formation in both the IMQ model and K14-VEGF transgenic mice. In summary, these results outline the mechanisms for the proinflammatory activity of NETs in skin and identify NETs/TLR4 as novel therapeutic targets in psoriasis.

Background IL-36γ is considered to be a valuable biomarker in psoriatic patients, which is expressed as an inactive precursor that needs to be proteolytically processed and activated, and neutrophil-derived proteases seemed to be potent activating enzymes of IL-36γ. Objectives This study aims to investigate the activation of IL-36γ by cathepsin G (CG) and neutrophil elastase (NE). Materials and methods We used inactive recombinant full-length (FL)-IL-36γ with different doses of NE or CG to stimulate HaCaT cells; neutrophil extracellular traps (NETs) were prepared to act on FL-IL-36γ and then stimulate HaCaT cells. Real-time quantitative PCR and ELISA were performed to detect CXCL-1 and CXCL-8 expression. We developed imiquimod-induced psoriasis-like mouse model to evaluate the effect of hypodermic injection of neutrophil-derived protease or its inhibitor. Histopathology and Western blotting were conducted for effect assessment. Results Purified CG cleaved and activated recombinant human FL-IL-36γ to promote CXCL-1 and CXCL-8 expression by human keratinocytes, and NETs activated FL-IL-36γ and the activation was inhibited by serpin A3. CG induced expression of a more truncated IL-36γ in psoriasiform lesion of mice and aggravated the psoriasis-like lesion induced by imiquimod, whereas recombinant serpin A3 alleviated the severity of the psoriasis-like mouse mode. Conclusion CG has the ability to cleave and activate IL-36γ and aggravate imiquimod-induced mouse psoriasiform lesion. Thus, CG-specific inhibitors might be promising therapeutic drugs for psoriasis.

Contains fulltext : 208841.pdf (Publisher’s version ) (Open Access) Psoriasis is an immune-mediated inflammatory skin disease that involves mainly T helper (Th)17, Th1 and Th22 lymphocytes, which cause hyper-proliferation of the epidermis with aberrant differentiation of keratinocytes, and local production of chemokines and cytokines. These fuel a self-amplifying loop where these products act on T cells to perpetuate cutaneous inflammatory processes. Among the various inflammatory mediators involved, interleukin (IL)-36 cytokines are important for the recruitment and activation of neutrophils and Th17 cells in psoriatic skin. In particular, IL-36s induce chemokines and cytokines interfere with differentiation/cornification programs in the epidermis, as well as promote pathological angiogenesis and endothelial cell activation. IL-36 cytokines belong to the IL-1 family, and comprise IL-36alpha, IL-36beta, and IL-36gamma agonists as well as IL-36 receptor antagonist and IL-38 antagonists. IL-36 cytokines are up-regulated in psoriatic epidermis, and their expression is strongly induced by TNF-alpha and IL-17. Contrarily, IL-38 antagonist is downregulated, and its impaired expression may be relevant to the dysregulated inflammatory processes induced by IL-36. Here, we discuss on the pathogenic mechanisms leading to the altered balance of IL-36 agonists/antagonists and the significance of this dysregulation in psoriasis. Collection of the information will provide a theoretical basis for the development of novel therapeutic strategies based on IL-36 agonist/antagonist manipulation in psoriasis.

Unmet needs in the treatment of psoriasis call for novel therapeutic strategies. Pustular psoriasis and psoriatic arthritis often represent a therapeutic challenge. Focus on IL-36 cytokines offers an interesting approach, as the IL-36 axis has been appointed a critical driver of the autoinflammatory responses involved in pustular psoriasis. Two IL-36R blocking antibodies, imsidolimab and spesolimab, are currently undergoing phase II and III clinical trials, with promising results.

Recent evidence has strongly implicated the IL-1 family cytokines IL-36 alpha, IL-36 beta, and IL-36 gamma as key initiators of skin inflammation. Similar to the other members of the IL-1 family, IL-36 cytokines are expressed as inactive precursors and require proteolytic processing for activation; however, the responsible proteases are unknown. Here, we show that IL-36 alpha, IL-36 beta, and IL-36 gamma are activated differentially by the neutrophil granule-derived proteases cathepsin G, elastase, and proteinase-3, increasing their biological activity similar to 500-fold. Active IL-36 promoted a strong pro-inflammatory signature in primary keratinocytes and was sufficient to perturb skin differentiation in a reconstituted 3D human skin model, producing features resembling psoriasis. Furthermore, skin eluates from psoriasis patients displayed significantly elevated cathepsin G-like activity that was sufficient to activate IL-36 beta. These data identify neutrophil granule proteases as potent IL-36-activating enzymes, adding to our understanding of how neutrophils escalate inflammatory reactions. Inhibition of neutrophil-derived proteases may therefore have therapeutic benefits in psoriasis.

we read with interest the recent paper of Hessam et al.1 regarding the involvement of IL-36 in hidradenitis suppurativa (HS). They have showed that agonist members of IL-36 were significantly overexpressed in HS lesional skin. This article is protected by copyright. All rights reserved.

Plaque psoriasis and pustular psoriasis are overlapping, but distinct, disorders. The therapeutic response to biologics supports the pivotal role of the tumour necrosis alpha (TNF-?)/ interleukin (IL)-23/IL-17/IL-22 axis in the pathogenesis of these disorders. Recently, functional activation of the IL-36 receptor (IL-36R) was discovered to be another driving force in the pathogenesis of psoriasis. This was first highlighted by the discovery that a loss-of-function mutation of the IL-36R antagonist (IL-36Ra) causes pustular psoriasis. Although the TNF-?/IL-23/IL-17/IL-22 axis and the functional activation of IL-36R are fundamentally involved in plaque psoriasis and pustular psoriasis, respectively, the 2 pathways are closely related and mutually reinforced, resulting in full-blown clinical manifestations. This review summarizes current topics on how IL-36 agonists (IL-36?, IL-36?, IL-36?) signal IL-36R, the pathological expression of IL-36 agonists and IL-36Ra in plaque and pustular psoriatic lesions, and the cross-talk between the TNF-?/IL-23/IL-17/IL-22 axis and the functional activation of IL-36R in the epidermal milieu.

Long-term administration of nitrogen-containing bisphosphonates can induce detrimental side effects such as bisphosphonate-related osteonecrosis of the jaw (BRONJ) in human. Although inflammation is known to be associated with BRONJ development, the detailed underlying mechanism remains unknown. Here, we report that the pro-inflammatory cytokine IL-36α is, in part, responsible for the BRONJ development. We found a notably higher level of IL-36α and lower level of collagen in the BRONJ lesions in mice. We also found that IL-36α remarkably suppressed TGF-β-mediated expression of Collα1 and α-Sma via the activation of Erk signaling pathway in mouse gingival mesenchymal stem cells. When IL-36 signaling was abrogated in vivo, development of BRONJ lesions was ameliorated in mice. Taken together, we showed the pathologic role of IL-36α in BRONJ development by inhibiting collagen expression and demonstrated that IL-36α could be a potential marker and a therapeutic target for the prevention and treatment of BRONJ. © 2016 American Society for Bone and Mineral Research.

L'Interleukine (IL)-36 fait référence à un groupe de cytokine incluant trois agonistes (IL-36alpha, bêta et gamma) et un antagoniste (IL-36Ra). L'IL-36 et l'IL-1 stimulent des voies de signalisation intracellulaires identiques via l'utilisation d'un co-récepteur commun l'IL-1 Receptor accessory protein (IL-1RAcP). Malgré ces similitudes, un excès relatif d'IL-36 ou d'IL-1 produit des phénotypes distincts chez l'homme. Dans ce travail, les niveaux d'ARN messager d'IL-36 Receptor (IL-36R) et d'IL-1 Receptor type 1 (IL-1R1) dans diverses cellules immunitaires humaines ont été mesurés par RT-qPCR. Les cellules ont ensuite été stimulées par des doses saturantes d'IL-36bêta ou d'IL-1bêta et la production de cytokines mesurée par RT-qPCR et ELISA. Les résultats montrent que l'expression des récepteurs et les réponses cellulaires à l'IL-36 et l'IL-1 varient de manière importante et démontrent que les cellules de Langerhans et les macrophages M2 répondent à l'IL-36, alors que les autres types cellulaires répondent de manière prédominante à l'IL-1.

Epithelial cells are the first line of defense against invading pathogens and external threats in the environment. Keratinocytes, often not perceived of as immune cells, release cytokines in response to infection or injury to signal danger to neighboring cells and recruit effector leukocytes to prevent further damage to the host. IL-1 and IL-36 cytokines are a group of closely related proteins that share similarities in structure and function and have been shown to play key roles in inflammatory responses of epithelial tissues. While IL-1, consisting of IL-1α and IL-1β, have been widely studied and recognized as pinnacle cytokines in a variety of inflammatory responses, relatively little is understood about IL-36 cytokines since their discovery more than 15 years ago, and how they differ from their better-known IL-1 relatives. IL-36 cytokines, consisting of IL-36α, IL-36β, and IL-36γ, signal through the same receptor, IL-36R, which is expressed most abundantly on epithelial cells. IL-36 proteins garnered attention when it was discovered that a missense mutation in the gene encoding the naturally occurring receptor antagonist, IL-36Ra, was associated with the deadly form of psoriasis, generalized pustular psoriasis (GPP). This disease is characterized by episodic flares of keratinocyte hyperproliferation leading to red scaly lesions all over the body, excessive neutrophil recruitment to the epidermis resulting in pustule formation, and severe fever. Our data presented here demonstrate that IL-36α, but not IL-36β or IL-36γ is critical for the psoriatic phenotype, including epidermal thickening and neutrophil recruitment, generated during a murine model of psoriasis induced by the drug Imiquimod. Furthermore, IL-36α was found to induce IL-1α expression and vice versa through a signaling feedback loop which perpetuated disease. These data provide insight into mechanisms whereby IL-36 signaling can lead to excessive inflammatory effects in patients with pre-existing regulation deficiencies, which can lead to acute flares of disease. Beyond their association with disease, IL-1 has been shown to contribute to anti-bacterial and anti-viral responses of the immune system by upregulating inflammatory signals and chemoattractants. Herpes Simplex Virus-1 (HSV-1) is a human pathogen that has developed several strategies to manipulate elements of the immune system to avoid detection by the host. One such mechanism is the prevention of activation and release of IL-1β from infected cells thereby blocking its pro-inflammatory responses. Our data show that keratinocytes infected with HSV-1 actively release IL-1α to alert danger to neighboring cells to circumvent this blockage of IL-1β signaling. This release of IL-1α initiates recruitment of leukocytes to early HSV-1 microinfection sites resulting in increased protection against disease, as evident by the increased mortality rate of mice deficient in the IL-1 receptor, IL-1R1. This study, for the first time in vivo, demonstrates the ability of IL-1α to act as an alarmin to initiate an immune response to combat infection. The role of IL-36 cytokines during viral infections has been less defined than that of IL-1. Several studies have shown the upregulation of IL-36 expression during viral infections in epithelial tissues, such as HSV-1 and Influenza, yet a direct link has not been established between these proteins and anti-viral responses. Our research presented within this thesis show that IL-36β, but not IL-36α nor IL-36γ, provides protection against the lethal outcome of cutaneous HSV-1 infection, as demonstrated by IL-36β knockout mice dying earlier and more often than wild type mice. Surprisingly, while previous reports have found IL-36 cytokines to be capable of activating the adaptive immune system, our results found no significant differences in development of HSV-1 specific antibodies or CD8+ T cell development between wild type and IL-36β knockout mice. Furthermore, we found no significant differences in viral copy numbers at infection sites between the two groups. Although our data show that IL-36β clearly plays a critical role in controlling the outcome of HSV-1 infection, further studies are necessary to define the mechanisms behind this protection. The final section of this thesis focuses on the endogenous nature of IL-36 cytokines, specifically IL-36γ, and their potential processing. IL-36 cytokines were originally believed to be synthesized as full-length fully active proteins; however, large concentrations of the recombinant proteins were required to elicit cellular responses in vitro. Since then, studies have shown that IL-36 cytokines gained up to 1000-fold increases in reactivity following processing at very specific N-terminal locations of each individual cytokine, however this processing has never been shown to occur in vivo. These studies were recently expanded when neutrophil proteases were found to be responsible for processing of these proteins in vitro. Data presented here show, for the first time, that IL-36γ may be endogenously processed by neutrophils in wounded murine skin in vivo, yet, the amino acid processing site appears to be different from that predicted. Although further studies are required to fully characterize the nature of this processing, these data provide valuable insight into the natural mechanisms involved in the potential activation of these cytokines. Taken together, the research presented within this thesis sheds light on the mechanisms whereby IL-1 and IL-36 cytokines enhance immunological defenses against potential threats, and yet, can contribute to disease if unregulated. Furthermore, these studies demonstrate the evolutionary advantage of producing multiple cytokines that appear to have redundant roles within the body, yet can provide multiple levels of protection to the host. This knowledge contributes to our overall understanding of these proteins and their contribution to immunological systems within the body.

The IL-36 subfamily is a recently described group of cytokines with pro-inflammatory behavior, comprising three agonists (α, β and γ), its receptor (R) and one antagonist (Ra). The expression and function of IL-36 subfamily members in the estrous cycle in healthy and infected pregnancy have not been described. We evaluated mRNA and protein expression of IL-36 family members during the estrous cycle, implantation, fetal development and post-labor periods in a model of allogenic pregnancy in mice. We also explored the ability of Listeria monocytogenes to modulate expression of IL-36 subfamily members during pregnancy. Expression of IL-36 subfamily members showed different expression during the estrous cycle and pregnancy, but was induced at estrous, 16.5 days post coitum (dpc), 18.5 dpc and labor. IL-36 subfamily members showed a characteristic distribution in the glandular epithelium, perimetrium, myometrium, and stratum vasculare. Infection with Listeria monocytogenes during pregnancy induced strong production of IL-36 subfamily members, an observation that correlated with an increasing prevalence of fetal loss. Conclusions: IL-36 agonists showed specific patterns of mRNA and protein expression that might suggest functional specialization or specific target cells. Infection with Listeria monocytogenes during pregnancy induced strong production of IL-36 subfamily members.

We show that IL-36R is expressed by T (CD4+ and CD8+) and B (CD19+) lymphocytes in human blood and also by CD4+ T lymphocytes in the intestinal lamina propria. IL-36R protein was mostly stored in the cytoplasm of CD4 lymphocytes and B cells, during steady state conditions and the greatest expression of IL-36R mRNA was measured in CD4+ (T helper) lymphocytes. IL-36 β, which functions via IL-36R induced rapid and significant (P < 0.05) proliferation of CD4+ lymphocytes, within 48 h. IL-36R expression was also maintained on the surface of circulating CD4+ lymphocytes which enter the intestinal lamina propria. In conclusion our study is the first to show that (1) all human blood lymphocytes express IL-36R; (2) IL-36R expression is maintained by circulating CD4+ lymphocytes which enter the intestinal lamina propria and (3) IL-36R/IL-36 β induces rapid CD4 lymphocyte proliferation. The possible significance of these results in the context of human disease is discussed.

Summary Interleukin (IL)-36α, IL-36β and IL-36γ are expressed highly in skin and are involved in the pathogenesis of psoriasis, while the antagonists IL-36Ra or IL-38, another potential IL-36 inhibitor, limit uncontrolled inflammation. The expression and role of IL-36 cytokines in rheumatoid arthritis (RA) and Crohn's disease (CD) is currently debated. Here, we observed that during imiquimod-induced mouse skin inflammation and in human psoriasis, expression of IL-36α, γ and IL-36Ra, but not IL-36β and IL-38 mRNA, was induced and correlated with IL-1β and T helper type 17 (Th17) cytokines (IL-17A, IL-22, IL-23, CCL20). In mice with collagen-induced arthritis and in the synovium of patients with RA, IL-36α, β, γ, IL-36Ra and IL-38 were all elevated and correlated with IL-1β, CCL3, CCL4 and macrophage colony-stimulating factor (M-CSF), but not with Th17 cytokines. In the colon of mice with dextran sulphate sodium-induced colitis and in patients with CD, only IL-36α, γ and IL-38 were induced at relatively low levels and correlated with IL-1β and IL-17A. We suggest that only a minor subgroup of patients with RA (17–29%) or CD (25%) had an elevated IL-36 agonists/antagonists ratio, versus 93% of patients with psoriasis. By immunohistochemistry, IL-36 cytokines were produced by various cell types in skin, synovium and colonic mucosa such as keratinocytes, CD68+ macrophages, dendritic/Langerhans cells and CD79α+ plasma cells. In primary cultures of monocytes or inflammatory macrophages (M1), IL-36β and IL-36Ra were produced constitutively, but IL-36α, γ and IL-38 were produced after lipopolysaccharide stimulation. These distinct expression profiles may help to explain why only subgroups of RA and CD patients have a potentially elevated IL-36 agonists/antagonists ratio.

Recent evidence has strongly implicated IL-36 cytokines as key initiators of inflammation in the skin barrier. IL-36 cytokines belong to the extended IL-1 family and, similar to most members of this family, are expressed as inactive precursors that require proteolytic processing for activation. Because the proteases responsible for activation of members of the IL-36 subfamily have not been reported, we have developed a method for the production of biologically active IL-36 through introduction of a caspase cleavage motif, DEVD, within the N-termini of these cytokines. Here, we show that DEVD-modified IL-36 alpha, IL-36 beta and IL-36 gamma cytokines were highly soluble and were readily processed and activated by caspase-3. Caspase-3-processed IL-36 family cytokines exhibited robust biological activity on a range of responsive cell types, including primary keratinocytes. We also generated specific polyclonal antibodies against all three IL-36 family members through immunization with purified recombinant IL-36 cytokines. The modified forms of IL-36 described herein will be useful for production of large quantities of biologically active IL-36 for structure and function studies on these important proinflammatory cytokines.

The importance of inflammation in cancer is well established, with cytokines/chemokines playing an important role in carcinogenesis. IL-33 was recently identified as the ligand for ST2. ST2 is a member of the toll-like receptor/IL-1 receptor family. Three isoforms of ST2 exist: a trans-membrane receptor (ST2L), a secreted soluble form (sST2), and a variant form (ST2V). The IL-33/ST2 pathway has been implicated in inflammatory bowel disease, a major risk factor for colon cancer. The aim of the first part of my thesis was to investigate the role of IL-33 and ST2 in colon cancer. CT26 and HT29 colon cancer cells were found to express ST2 and IL-33 in vitro, with expression increased by inflammatory mediators (LPS, TNF-α and PGE2). Stimulation with IL-33 increased the migration, but not proliferation, of colon tumour cells. Functional analyses showed that stimulation with IL-33 induced the expression of CXCL-1 by CT26 and CCL2 expression by HT29 cells. To investigate the role of ST2 in vivo, ST2 knockdown cells were generated using ST2-specific shRNA (CT26 ST2shRNA) and injected subcutaneously into BALB/C mice. Knockdown of ST2 in colon tumours resulted in enhanced tumour growth (2.3 fold increase compared to CT26 scrshRNA) in vivo. This was associated with alterations in immune cell infiltration, including an increase in macrophage infiltration. In contrast, characterisation of human colon tumours revealed that ST2L expression was increased in tumour cells relative to adjacent non-tumour cells, with no change in expression of total ST2. These results indicate that the IL-33/ST2 signalling axis may play an important role in colon carcinogenesis and merits further investigation. The role of the IL-36R, a second IL-1R family member, in colon cancer was investigated in the second part of my thesis. Characterization of human colon tumours ex vivo showed significantly increased expression of the IL-36 ligands, IL-36α and IL-36γ, compared to adjacent non-tumour tissue. In vitro colon cancer cell lines HT29 and SW480 were shown to express the IL-36R and IL-36 ligands. IL-36α and IL-36γ stimulation of HT29 cells also increased the expression of the chemokines CXCL-1, CCL2, CCL20, and IL-8. This suggests that IL-36 signalling may promote tumour-derived immune cell recruitment. This field requires further study to determine if the recruitment of immune cells by IL-36 signalling could be utilised to break tolerance against tumour antigens. This thesis has laid the basis for further studies to explore the role of IL-36 signalling in colon cancer.

Tuberculosis remains a major health problem in the world nowadays. The increasing incidence of resistant tuberculosis is associated with a poor diagnosis, reflecting important difficulties for total eradication. Understand host-pathogen interactions is crucial to establish new therapeutic strategies. This work first shows the limited contribution of IL-36 pathway during mycobacterial infection. These results suggest that IL-36 could be targeted for the treatment of psoriasis without a high risk of tuberculosis reactivation. We then demonstrate the differential role of TNF pathway among myeloid or lymphoid cells during M. tuberculosis infection, and our data support the development of immunomodulatory strategies to boost host immune response, thus helping to clear the infection. Moreover, we characterize a humanized murine model allowing the study of new anti-TNF candidates in the context of M. tuberculosis infection. Finally, we show that antibodies targeting IL-17 does not dampen host control of M. tuberculosis infection, unlike anti-TNF, and that IL-22 does not compensate absence of IL-17 for this control.; La tuberculose est encore aujourd’hui un problème de santé majeur et l’augmentation des cas de tuberculoses résistantes au niveau mondial, associé au dépistage et diagnostic insuffisants, suggère une éradication totale encore lointaine. La compréhension des relations hôte-pathogène est essentielle pour permettre d’établir de nouvelles stratégies thérapeutiques. Ces travaux de thèse ont mis en exergue la contribution limitée de la voie de signalisation IL-36, cytokine de la famille de l’IL-1, au cours de l’infection mycobactérienne. Ces données permettent d’envisager sérieusement l’IL-36 en tant que cible thérapeutique pour le psoriasis sans risquer la réactivation de tuberculose latente chez les patients. De plus, nous avons également démontré le rôle différentiel de la voie de signalisation TNF au sein de populations cellulaires spécifiques lors de l’infection par M. tuberculosis, et nos résultats apportent des connaissances solides pour envisager des stratégies immuno-modulatoires qui pourraient constituer l’avenir des traitements antituberculeux. D’autre part, nous avons caractérisé un modèle murin humanisé pour une étude facilitée des anticorps anti-TNF humains actuels. L’utilisation de ce modèle pourrait permettre, à termes, d’identifier et de valider de nouveaux candidats d’anticorps anti-TNF de deuxième génération. Enfin, nous avons montré que des anticorps neutralisants l’IL-17 ne perturbent pas la réponse immunitaire à la tuberculose, contrairement aux anticorps anti-TNF, et que l’absence de l’IL-17 n’est pas compensée par l’IL-22 puisque des animaux déficients pour ces deux voies de signalisation sont capables de contrôler l’infection.

We investigated the expression and proinflammatory activity of interleukin (IL)-36 in patients with systemic lupus erythematosus (SLE). The expression level of IL-36, its putative receptors and the frequency of CD19+CD24highCD27+ regulatory B (Breg) lymphocytes of peripheral blood from 43 SLE patients and 16 normal control (NC) subjects were studied using ELISA and flow cytometry. Plasma cytokines/chemokines and ex vivo productions of cytokine/chemokine from peripheral blood mononuclear cells (PBMC) stimulated with recombinant IL-36 were determined by Luminex multiplex assay. Plasma concentrations of IL-36α, IL-36γ and the proportions of circulating IL-36R-positive CD19+ B lymphocytes in total B lymphocytes and PBMC were significantly increased in active SLE patients compared with NC (all p &lt, 0.05). Plasma IL-36α and IL-36γ correlated positively with SLE disease activity and elevated plasma IL-10 concentration (all p &lt, 0.05). The frequencies of circulating Breg lymphocytes in total B lymphocytes and PBMC were significantly decreased in both inactive and active SLE patients compared with NC (all p &lt, 0.01). The frequency of Breg lymphocytes in total B lymphocytes correlated negatively with the proportion of IL-36R-positive B lymphocytes (p &lt, 0.05). IL-36α exerted substantial proinflammatory effect in PBMC from SLE patients by inducing the production of IL-6 and CXCL8. Upon stimulation with IL-36α and IL-36γ, ex vivo productions of IL-6 and CXCL8 were significantly increased in SLE patients compared with NC (all p &lt, 0.05). This cross-sectional study demonstrated that over expression of circulating IL-36α may exert a proinflammatory effect as observed in human SLE.

Background Cancer immunotherapy attempts to stimulate the immune system to reject and destroy tumors and is one of the cancer treatment strategies. Recently, interluekin36 (IL36) has been used as immunotherapeutic agents in cancer gene therapy. Present study investigated that the IL36 gene therapy effects on the regression of tumor masses in mouse model. Aim of this study is determination of the gene therapy effects by IL36 in the regression of tumor masses in mouse model. Methods To study the therapeutic efficacy of this cytokine, WEHI-164 tumor cells were transected with mIL36 plasmids. ELISA test was used to check cytokine production by transected cells. To establish fibro sarcoma mouse model, Tumoral transfected cells were injected subcutaneously to inoculate tumor in BALB/C mice. Tumor volumes were measured by caliper. Mice were sacrificed and tumors were extracted. The expression of IL36 and IFN-γ was studied with Real-time PCR and immunoblotting. The expression of Ki-67 (a tumor proliferation marker) in tumor masses was studied by immunohistochemistry staining. In this study we had 2 groups which are treated with IL-36 and Untreated with IL-36 as a blank. Results The group treated with IL36 indicated decrease of tumor mass volume (p

The interleukin (IL)-1 family includes 11 members that are important in inflammatory processes. It includes various agonists and two antagonists, IL-1Ra and IL-36Ra. Our aim was to investigate whether the IL-1 family is involved in allergic contact dermatitis (ACD). The expression of IL-1 family members was evaluated by PCR and immunohistochemistry in the positive patch test reaction site (involved skin) and in the uninvolved skin of ACD patients. We also examined these cytokines in an ex vivo model of ACD. The antagonistic activity of IL-36Ra was evaluated by injecting recombinant IL-36Ra in uninvolved skin biopsies of ACD patients. IL-1Ra and IL-36Ra expression was quantified in mononuclear cells of nickel-sensitized patients challenged in vitro with nickel. IL-33 involvement in ACD was investigated by intra-dermal injection of anti-IL-33 in the uninvolved skin of patients ex vivo. Results showed that IL-1β, IL-1Ra, IL-36α, IL-36β, IL-36γ and IL-33 expression, but not IL-36Ra expression, was enhanced in ACD-involved skin. Immunohistochemical analysis and ex vivo skin cultures confirmed these results. Injection of anti-IL-33 in ACD-uninvolved skin inhibited IL-8 expression, whereas IL-36Ra inhibited IL-36α, IL-36β, IL-36γ and IL-8 expression. Nickel induced IL-1Ra expression in lymphocytes of nickel-sensitized patients. Hence, various IL-1 agonists and antagonists may be involved in ACD pathogenesis.

IL-36 is another family member of IL-1 and induces the production of proinflammatory cytokines and activates MAPK and NFκB pathways. IL-36 is a common mediator of innate and adaptive immune response and is inhibited by IL-36 receptor antagonist (RA). IL-36RA acts on IL-36 receptor ligand which exerts proinflammatory effect in vivo and in vitro. IL-38 binds to IL-36 receptor as does IL-36RA and has similar biological effects on immune cells. IL-38 is also a member of IL-1 cytokine and shares some characteristics of IL-1RA, binding the same IL-1 receptor type I. IL-38 plays a role in the pathogenesis of inflammatory diseases, exerting protective effect in some autoimmune diseases. Both IL-38 and IL-36RA have an anti-inflammatory biological effect, however in some cases have contrary effects.

Interleukin-36 (IL-36) is a pro-inflammatory cytokine which plays an important role in innate and adaptive immunity. IL-36 activates MAPK and NF-kB pathways and is produced by many different cells. This cytokine is a family member of interleukin-1 (IL-1) and plays an important role in the pathophysiology of several diseases. Here we summarise and review the new aspects of this important pro-inflammatory cytokine.

Serum levels of interleukin (IL)-33, IL-36 and IL-37 have been reported to be up-regulated in various T helper (Th)1/Th17 mediated autoimmune/inflammatory diseases. Although IL-33 and IL-36 expression are increased in skin lesions of patients with psoriasis, their serum levels in such patients have not yet been adequately studied. We aimed to evaluate serum level of IL-33, IL-36 and IL-37 cytokines and IL-37 gene expression in patients with autoimmune/inflammatory disease of psoriasis and to explore their correlation with disease severity. Such evaluation further clarifies disease pathogenesis and may be utilized in clinical practice. 47 patients with psoriasis vulgaris and 47 healthy individuals were included. Serum IL-33, IL-36 and IL-37 levels were measured by Elisa and gene expression of IL-37 measured by real time PCR in all participants. The disease activity was assessed by the psoriasis area and severity index (PASI). Linear Correlation between interleukin measures and PASI score was calculated. Also sensitivity and specificity of such measurements were determined. Serum IL-36 and 37 levels in patients with psoriasis vulgaris were significantly higher than those in healthy controls and positively correlated with disease activity (PASI score). Serum IL-33 levels in patients were equal to those in healthy controls but positively correlated with disease activity. Serum IL-36 levels were significantly higher than serum IL-33 levels. Gene expression of IL-37 levels in patients were higher than healthy controls but was not correlated with disease activity. Serum IL-36 and IL-37 levels are generally increased in psoriasis vulgaris and correlated with disease severity. Therefore, serum IL-36 and IL-37 levels may be markers of treatment and diagnosis of psoriasis.