Neutrophil-driven and interleukin-36γ-associated ocular surface inflammation in chronic Stevens-Johnson syndrome.

PURPOSE: This study aims to elucidate the tear proteome and understand the underlying molecular mechanisms involved in the ocular complications following Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). METHODS: Mass spectrometry (MS) was performed to quantify the tear fluid proteins from chronic SJS/TEN patients (n = 22 eyes) and age- and gender-matched controls (n = 22 eyes). The candidate proteins were validated using ELISA (n = 80 eyes) in tear samples and immunohistochemistry (IHC; n = 12) in eyelid margin specimens. These proteins were compared for significant differences based on age, gender, disease duration, and ocular severity. RESULTS: A total of 1692 tear fluid proteins were identified, of which 470 were significantly differentially regulated in chronic SJS/TEN. The top 10 significantly upregulated proteins were neutrophil secretions including neutrophil elastase (p < .0001), defensin (p < .0001), and matrix metalloproteinase 8 (p < .0001). The presence of neutrophils was confirmed by the upregulation of IL-8 (p < .001) in tears, a key cytokine known for recruiting neutrophils. Additionally, positive expression of myeloperoxidase was observed in the keratinized eyelid margins of SJS/TEN to validate the presence of neutrophils. Among 41 unique proteins identified by MS, IL-36γ (p < .01) was expressed in three SJS/TEN patients and was confirmed in SJS/TEN tears and eyelid margins by ELISA and IHC, respectively. IL-36γ was specifically expressed in the superficial layers of eyelid margin keratinized conjunctiva. The majority of the significantly downregulated proteins were lacrimal gland secretions such as lacritin (p < .0001) and opiorphin (p < .002). Neutrophil elastase (p < .02) was significantly elevated in patients with severe eyelid margin keratinization. CONCLUSION: Our observations indicate a clear correlation between eyelid margin keratinization and the expression of IL-36γ, potentially mediated by neutrophils recruited via IL-8. Future experimental studies are needed to test the role of therapies targeting IL-8 and/or IL-36γ in reducing eyelid margin keratinization and its associated ocular complications in SJS/TEN.

Prognostic value of Interleukin-36s in cancers: A systematic review and meta-analysis.

BACKGROUND: Interleukin-36s (IL-36s) are a category of inflammatory cytokines and an increasing number of studies over the past decade have found that different kinds of IL-36s play different roles in cancers. This systematic review and meta-analysis aimed to evaluate the prognostic value of IL-36s in different cancer types. METHOD: Two reviewers independently searched in PubMed, Cochrane Library and EMBASE up to December 13, 2022. We extracted the hazard ratio (HR) and the confidence intervals (CIs) of the related prognostic outcomes and analyzed the pooled HR. RESULTS: We included 12 studies including 1925 patients. In all, six studies including IL-36α, five including IL-36γ and one including IL-36ß. A high expression of IL-36α was associated with better overall survival (OS) (HR = 0.48, 95 %CI: 0.37-0.62, P < 0.001) of cancer patients. The expression of IL-36γ was not related with cancers. Further, subgroup analysis showed that the expression of IL-36γ had no correlation with the OS of colorectal cancer (CRC) and non­small cell lung cancer (NSCLC) patients. Interestingly, a high expression of IL-36γ played contrasting prognostic roles in hepatocellular carcinoma (HCC) (HR = 0.43, 95 %CI: 0.27-0.69, P < 0.001) patients and gastric cancer (GC) (HR = 1.58, 95 %CI: 1.33-1.87, P < 0.001) patients. The only IL-36ß related study showed the expression of IL-36ß was not correlated with the prognosis of CRC patients (P > 0.05). CONCLUSION: IL-36α, IL-36ß and IL-36γ possibly play different roles in different cancers. High expression of IL-36α may be associated with good prognostic value in cancer patients, especially in CRC patients. The association between cancers prognosis and expression of IL-36ß or IL-36γ needs further evaluation. These conclusions need more clinical prognostic data for confirmation.

Role of interleukin-36γ induced by ultraviolet radiation in chronic actinic dermatitis.

BACKGROUND: Chronic actinic dermatitis (CAD) is an immune-mediated photodermatosis characterized by a high eosinophil count and total immunoglobulin E (IgE) in the peripheral blood of patients. At present, however, the reasons for their elevation remain unclear. OBJECTIVE: The current study aimed to detect changes in inflammatory cytokines in CAD and explore their role in this disease. METHODS: Enzyme-linked immunosorbent assay and Luminex assay were conducted to measure inflammatory factor levels. Immunohistochemical analysis and quantitative real-time polymerase chain reaction were performed to evaluate the expression levels of interleukin-36γ (IL-36γ), IL-8, chemokine (C-C motif) ligand 17 (CCL17), and CCL18. CCK8 kits were used to assess cell proliferation. Immunofluorescence was used to detect nuclear factor κB (NF-κB) p65 nuclear translocation. Western blot analysis was performed to detect the protein expression level of phosphorylated NF-κB (p-NF-κB) p65. Hematoxylin and eosin and Masson trichrome staining were applied to observe histological changes in a chronic photo-damaged mouse model. RESULTS: Eosinophils, total IgE, IL-36γ, IL-8, tumor necrosis factor α, CCL17, and CCL18 were elevated in CAD. Of note, IL-36γ promoted the proliferation of eosinophilic cells (EOL-1) and the production of IgE in peripheral blood mononuclear cells. IL-36γ also promoted the production of IL-8 and CCL18 in immortalized human keratinocytes (HaCaT cells), while ultraviolet radiation (UVR)-induced IL-36γ via activation of the NF-κB signaling pathway. CONCLUSIONS: IL-36γ was involved in the pathogenesis of CAD and UVR contributed to the production of IL-36γ, which may provide a novel therapeutic target for CAD.

Interleukin-38: A crucial player in periodontitis.

BACKGROUND: The objective of this study was to compare the levels of gingival crevicular fluid (GCF), salivary, and serum matrix metalloproteinase-9, interleukin (IL)-17, IL-36γ, and IL-38 in individuals with healthy periodontium, gingivitis, and periodontitis and to evaluate their correlations with clinical periodontal parameters. MATERIALS AND METHODS: Ninety systemically healthy and nonsmoking volunteers divided into a healthy (H) group (n = 30), a gingivitis (G) group (n = 30), and a periodontitis (P) group (n = 30) were included in this study. Clinical periodontal parameters of volunteers were recorded, and GCF, unstimulated saliva, and serum samples were collected. Data analysis was done with enzyme-linked immunosorbent assays. The Kruskal-Wallis test and Bonferroni correction were used for multiple comparisons and post hoc statistical analyses. RESULTS: The group H had significantly lower clinical parameters than the group P (p < 0.001). GCF and salivary IL-36γ and IL-38 levels were significantly higher in the group P than in the H and G groups (p < 0.05). Positive correlations between biochemical findings and clinical periodontal parameters were observed. CONCLUSIONS: IL-36γ and IL-38 levels in GCF, saliva, and serum correlate with clinical periodontal parameters and may play a role in determining the activity of periodontitis.

Skin surface biomarkers are associated with future development of atopic dermatitis in children with family history of allergic disease.

BACKGROUND: Atopic dermatitis (AD) is a common childhood chronic inflammatory skin disorder that can significantly impact quality of life and has been linked to the subsequent development of food allergy, asthma, and allergic rhinitis, an association known as the "atopic march." OBJECTIVE: The aim of this study was to identify biomarkers collected non-invasively from the skin surface in order to predict AD before diagnosis across a broad age range of children. METHODS: Non-invasive skin surface measures and biomarkers were collected from 160 children (3-48 months of age) of three groups: (A) healthy with no family history of allergic disease, (B) healthy with family history of allergic disease, and (C) diagnosed AD. RESULTS: Eleven of 101 children in group B reported AD diagnosis in the subsequent 12 months following the measurements. The children who developed AD had increased skin immune markers before disease onset, compared to those who did not develop AD in the same group and to the control group. In those enrolled with AD, lesional skin was characterized by increased concentrations of certain immune markers and transepidermal water loss, and decreased skin surface hydration. CONCLUSIONS: Defining risk susceptibility before onset of AD through non-invasive methods may help identify children who may benefit from early preventative interventions.

A novel biomarker for pleural effusion diagnosis: Interleukin-36γ in pleural fluid.

BACKGROUND: Numerous studies have described the critical importance of interleukin (IL) -36γ in host defense against lung infections, but it is unknown whether it plays a role in infectious pleural effusion (IPE). This study aimed to examine the levels of IL-36γ in pleural effusions of different etiologies and evaluate the diagnostic accuracy of IL-36γ in the differential diagnosis of IPE. METHODS: A total of 112 individuals was enrolled in this research. IL-36γ levels in pleural fluids of all 112 patients were measured by enzyme-linked immunosorbent assay (ELISA). We also characterized these markers' diagnostic values across various groups. RESULTS: Patients with tuberculous pleural effusion (TPE) and parapneumonic effusion (PPE) had exhibited markedly higher IL-36γ levels in their pleural fluid than the malignant pleural effusion (MPE) and transudative effusion patients. Furthermore, the IL-36γ concentrations in TPE patients were evidently higher than in uncomplicated parapneumonic effusion (UPPE) patients but significantly lower than in complicated parapneumonic effusion (CPPE)/empyema patients. Pleural fluid IL-36γ is a useful marker to differentiate TPE from UPPE, at a cut-off value for 657.5 pg/ml (area under the curve = 0.904, p < 0.0001) with 70.0% sensitivity and 95.7% specificity. CONCLUSIONS: The elevated IL-36γ in pleural effusion may be used as a novel biomarker for infectious pleural effusion diagnosis, particularly in patients with CPPE/empyema, and is a potentially promising biomarker to differentiate between TPE and UPPE.

The mechanism on Prevotella melaninogenica promoting the inflammatory progression of oral lichen planus.

Oral lichen planus (OLP) is a common chronic inflammatory disease occurring in the oral mucosa. Bacteria are a key driver of mucosal immune responses and can induce changes in gene expression and function of epithelial keratinocytes. IL-36γ can induce the expression of antimicrobial peptides, cytokines, and chemokines, and is widely involved in many chronic inflammatory diseases. Our aim is to explore the role of IL-36γ in the pathological process of OLP when Prevotella melaninogenica (P. melaninogenica) invades the oral mucosa. The expression of IL-36γ in OLP lesions and mice was detected by immunohistochemistry. Recombinant human IL-36Gamma (rhIL-36γ) was used to treat oral keratinocytes and the expression levels of inflammatory cytokines were detected by qRT-PCR and ELISA. The expression of IL-36γ and TRPV1 was detected by western blotting following co-culturing P. melaninogenica with oral keratinocytes. The mRNA expression of IL-36γ was detected by qRT-PCR. From our results, IL-36γ was upregulated in OLP lesions. Exogenous rhIL-36γ promoted the expression of pro-inflammatory cytokines and antibacterial peptides in oral keratinocytes. The expression of IL-36γ was significantly increased following the stimulation of P. melaninogenica in oral keratinocytes and mice. TRPV1 activation was induced by P. melaninogenica and its activation enhanced the expression of IL-36γ. IL-36Ra could reduce the inflammation in OLP in vitro. In summary, overexpression of IL-36γ in OLP lesions could promote its pathogenesis by inducing inflammation. P. melaninogenica invasion of oral keratinocytes could induce the expression of IL-36γ by the activation of TRPV1, thereby regulating the interaction between bacteria and oral epithelial cells.

IL-36α and IL-36γ expressions in the differential diagnosis of palmoplantar psoriasis and palmoplantar eczema: A retrospective histopathologic and immunohistochemical study.

BACKGROUND: Diagnosing hyperkeratotic lesions on the palms and soles is often challenging for both clinicians and pathologists. Interleukin (IL)-36 cytokines play an important role in the pathogenesis of psoriasis. METHODS: We retrospectively re-evaluated hematoxylin-eosin-stained biopsy specimens of 30 patients with clinically diagnosed palmoplantar psoriasis (PP) and 30 patients with palmoplantar eczema (PE), and then performed IL-36α and IL-36γ immunohistochemistry. RESULTS: Among the histopathologic features, thinning of the rete ridges and vertical alternation of parakeratosis and orthokeratosis had the highest positive predictive value (PPV) in diagnosing PP (72.7% and 69.3%, respectively). Immunohistochemically, patients with PP predominantly showed diffuse or focal strong expression with IL-36α and IL-36γ staining in the upper layers of the epidermis (86.7% and 83.3%, respectively). The comparison of the mean IL-36α and IL-36γ expression scores significantly differed between PP and PE (P < .001). Among all histopathologic and immunohistochemical features, diffuse strong expression of IL-36α and IL-36γ staining had the highest PPVs in favor of a diagnosis of PP (75% and 76.7%, respectively). CONCLUSIONS: Our data suggest that IL-36α and IL-36γ immunohistochemistry can be used in the differential diagnosis of PP and PE.

IL-36γ-armed oncolytic virus exerts superior efficacy through induction of potent adaptive antitumor immunity.

In this study, we aimed to apply the cytokine IL-36γ to cancer immunotherapy by constructing new oncolytic vaccinia viruses (OV) expressing interleukin-36γ (IL-36γ-OVs), leveraging unique synergism between OV and IL-36γ's ability to promote antitumor adaptive immunity and modulate tumor microenvironment (TME). IL-36γ-OV had dramatic therapeutic efficacies in multiple murine tumor models, frequently leading to complete cancer eradication in large fractions of mice. Mechanistically, IL-36-γ-armed OV induced infiltration of lymphocytes and dendritic cells, decreased myeloid-derived suppressor cells and M2-like tumor-associated macrophages, and T cell differentiation into effector cells. Further study showed that IL-36γ-OV increased the number of tumor antigen-specific CD4+ and CD8+ T cells and the therapeutic efficacy depended on both CD8+ and CD4+ T cells. These results demonstrate that these IL36γ-armed OVs exert potent therapeutic efficacy mainly though antitumor immunity and they may hold great potential to advance treatment in human cancer patients.

Involvement of the cytokine TWEAK in the pathogenesis of psoriasis vulgaris, pustular psoriasis, and erythrodermic psoriasis.

Psoriasis is a common chronic inflammatory dermatitis in which various cytokines play a detrimental role. The cytokine tumor necrosis factor-related weak inducer of apoptosis (TWEAK) is involved in the pathogenesis of multiple inflammatory disorders. However, the potential role of TWEAK in various subtypes of psoriasis has not been studied in depth. To investigate whether the levels of TWEAK are associated with clinical traits and the levels of some known psoriasis-related cytokines, such as interleukin (IL)-17A, IL-22, interferon (IFN)-γ, and IL-36γ, 20 patients with psoriasis vulgaris (PV), 8 patients with pustular psoriasis (PP), 8 patients with erythrodermic psoriasis (EP), and 20 healthy controls (HCs) were recruited into this study. The levels of serum cytokines were detected by commercial enzyme-linked immunosorbent assay kits. The average levels of TWEAK, IL-17A, IL-22, IFN-γ, and IL-36γ were significantly higher in the psoriasis groups than in the HC group. Furthermore, there was a statistically significant correlation between TWEAK and IL-17A/IFN-γ in PV and IL-36γ in EP, but there was no correlation between TWEAK and IL-22 in any subtype of psoriasis. This study suggests that TWEAK may have a role in the pathogenesis of PV, PP, and EP via synergy with IL-17A, IFN-γ, or IL-36γ, but not with IL-22.

Increased expression of interleukin 36 in chronic rhinosinusitis and its contribution to chemokine secretion and increased epithelial permeability.

BACKGROUND: IL-36 family, a recently reported member of the IL-1 cytokine family, plays an essential role in nonspecific innate immune response to infection. This study aims at investigating the expression of IL-36 family members (α, ß, and γ) in normal and inflammatory sinus mucosa of patients with chronic rhinosinusitis (CRS), their effects on chemokine secretion and on the barrier function of epithelial and endothelial cells, and the effect of Toll-like receptors on the expression of IL-36 in epithelial cells. MATERIAL AND METHODS: The expression of IL-36 family in normal and inflammatory sinus mucosa, the production of chemokines or the expression levels of IL-36 family in epithelial cells treated with IL-36 family members or stimulated with TLR3, TLR4, TLR5, or TLR7/8 agonists were measured with real time PCR, ELISA, immunohistochemistry, or Western blot. The epithelial and endothelial permeability, and transendothelial leukocyte migration were investigated using cultured epithelial and endothelial cells. RESULTS: IL-36α, IL-36ß, and IL-36γ were localized in epithelial cells of sinonasal mucosa. Their levels increased in inflammatory mucosa of CRS patients and are up-regulated by TLR3, TLR4, or TLR5 agonists. IL-36α, or IL-36γ induced CXCL1, CXCL2, and CXCL3 production. Epithelial and endothelial permeability, transendothelial leukocyte migration were increased in cells treated with IL-36α, IL-36ß, or IL-36γ. CONCLUSIONS: These results suggest that IL-36α, IL-36ß, and IL-36γ localized in superficial epithelium may act as a responder to microbial and nonmicrobial elements through TLR and subsequently produce CXC chemokines, playing an interplay between innate and adaptive immune response.

Upregulation of IL-36 cytokines in folliculitis and eosinophilic pustular folliculitis.

BACKGROUND: Members of the interleukin (IL)-36 family, IL-36α, IL-36ß and IL-36γ, are potent chemoattractive cytokines for neutrophils and eosinophils. IL-36 receptor antagonist (IL-36Ra) inhibits IL-36α, IL-36ß and IL-36γ activity. However, the immunohistological expression of IL-36α, IL-36ß, IL-36γ and IL-36Ra has never been addressed in normal follicles, folliculitis or eosinophilic pustular folliculitis (EPF). METHODS: We performed immunohistochemical staining for IL-36α, IL-36ß, IL-36γ and IL-36Ra using 10 cases of EPF, nine of non-specific folliculitis, 10 normal skin samples and 10 samples of normal follicles adjacent to a sebaceous naevus as a control. Two dermatologists, who were blind to the patient records, evaluated all of the slides. RESULTS: The immunoreactive IL-36α was hardly detected in the follicular epithelium and epidermis in the normal skin, folliculitis or EPF. The expression of IL-36ß, IL-36γ and IL-36Ra was augmented in both folliculitis and EPF compared with that in normal follicles. Negative correlations were detected between IL-36ß and IL-36Ra and between IL-36γ and IL-36Ra in normal follicles; however, these were absent in folliculitis. In contrast to normal follicles and folliculitis, a significant positive correlation between IL-36ß/γ and IL-36Ra was shown in EPF. CONCLUSIONS: The overexpression of IL-36ß, IL-36γ and IL-36Ra is an integral part of the inflammatory response of folliculitis and EPF. The coordinated expression of IL-36γ and IL-36Ra may be related to the pathomechanism of EPF.

IL-17A synergistically enhances TLR3-mediated IL-36γ production by keratinocytes: A potential role in injury-amplified psoriatic inflammation.

Skin injury can trigger formation of new lesions in psoriasis (Koebner phenomenon). The mechanisms through which injury exacerbates psoriasis are unclear. During wound repair, epidermal keratinocytes are activated and produce abundant IL-36γ, further promoting the skin inflammation. IL-17A is the cornerstone cytokine in the pathogenesis of psoriasis. We sought to investigate the effects of IL-17A on injury-induced keratinocyte activation and IL-36γ production. Here, we demonstrated that dsRNA released from necrotic keratinocytes induced the expression of IL-36γ. Silencing of TLR3 by siRNA decreased the IL-36γ induction by necrotic keratinocyte supernatant. Co-stimulation with dsRNA and IL-17A synergistically increased the expression of IL-36γ and other proinflammatory mediators (CCL20, CXCL8, DEFB4 and LCN2) in keratinocytes. The synergistic effects were not dependent on TLR3 upregulation, TNF receptor signalling and mRNA stabilization. Co-stimulation with dsRNA and IL-17A resulted in an accumulation of IκBζ. The synergistic upregulation of IL-36γ and proinflammatory mediators were inhibited by IκBζ siRNA. Co-stimulation with IL-17A and poly(I:C) markedly activated the p38 MAPK and NF-κB pathway, compared with poly(I:C). Blockade of p38 MAPK and NF-κB suppressed dsRNA/IL-17A-mediated IκBζ and IL-36γ induction. These findings demonstrated that IL-17A synergistically enhanced the dsRNA-mediated IL-36γ production through a p38 MAPK-, NF-κB-, and IκBζ-dependent mechanism.

Keratinocyte-derived IL-36γ plays a role in hydroquinone-induced chemical leukoderma through inhibition of melanogenesis in human epidermal melanocytes.

Chemical leukoderma is an acquired type of vitiligo that can be initiated by various exogenous chemicals such as hydroquinone (HQ), rhododendrol (RD), or 4-tertiary butyl phenol (4-TBP). Despite the importance of epidermal keratinocytes in diverse dermatological conditions, their toxicological role in chemical leukoderma is poorly understood. To elucidate their role in the pathogenesis of chemical leukoderma, genome-scale transcriptional analysis was performed in human epidermal keratinocytes (HEKs) treated with a sub-cytotoxic HQ concentration (10 µM). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway-based functional enrichment analysis of HQ-induced differentially expressed genes (DEGs) revealed that HQ significantly upregulated DEGs related to the IL-17 signaling pathway and significantly downregulated DEGs associated with melanogenesis in HEKs. The meta-analysis between the HQ-induced and cytokine-induced transcriptional data (GSE53751) showed that 58 DEGs were commonly upregulated between HQ- and IL-17A-treated HEKs. Notably, the expression of IL36G was significantly increased in HEKs in response to both HQ and IL-17A. IL-36γ (2 µg/ml) directly inhibits melanin biosynthesis in cultured human epidermal melanocytes (HEMs) and downregulates the gene transcription of key enzymes in the melanogenesis pathway including TYR, DCT, and TYRP1. Moreover, IL-36γ autocrinally regulated keratinocyte function to produce the proinflammatory cytokines IL-36γ, IL-6, and CXCL8/IL-8 in a concentration-dependent manner, suggesting that IL-36γ may stimulate the amplification cycle of cutaneous inflammation. In this regard, hydroquinone-induced IL-36γ from human keratinocytes plays a pivotal role in the development of chemical leukoderma by autocrinally or paracrinally modulating the crosstalk between keratinocytes and melanocytes.

Targeted codelivery of doxorubicin and IL-36γ expression plasmid for an optimal chemo-gene combination therapy against cancer lung metastasis.

Cancer metastasis is the main cause for the high mortality in breast cancer patients. In this work we developed a polymer POEG-st-Pmor for targeted co-delivery of IL-36γ expression plasmid and doxorubicin (Dox) to lung metastasis of breast cancer. The polymer readily formed micelles that were effective in loading Dox and simultaneously forming complexes with IL-36γ plasmid. Interestingly, particles co-loaded with Dox and plasmid was significantly smaller and more stable than the particles loaded with Dox only. Gene transfection in both lungs and s.c. tumors was significantly higher with our polymer compared to PEI. In addition, the Dox + IL-36γ/POEG-st-Pmor not only could bring improved anti-metastatic effect but synergistically enhance the type I immune response by increasing the IFN-γ positive CD4+ and CD8+ T cells and simultaneously decreasing the immunosuppressive myeloid-derived suppressor cells in the lung. POEG-st-Pmor may represent a simple and effective delivery system for an optimal chemo-gene combination therapy.

IL-36γ inhibits differentiation and induces inflammation of keratinocyte via Wnt signaling pathway in psoriasis.

Psoriasis is a common inflammatory skin disease characterized by abnormal keratinocyte inflammation and differentiation that has a major impact on patients' quality of life. IL-36γ, a member of IL-36 cytokine family, is highly expressed in psoriasis and plays an important role in inflammation response and differentiation. However, the function of IL-36γ in differentiation and inflammation of keratinocyte in psoriasis has not been clearly identified. Thus, this study aimed to investigate the role of IL-36γ on differentiation and inflammation in HaCaT cells. HaCaT cells were divided into three groups: (1) Control group; (2) IL-36γ (100 ng/mL) group; (3) IL-36γ (100 ng/mL) + IWP-2 (1µM) group. Real time PCR was used to detect gene expression; the inflammation cytokines were examined by ELISA. We showed that treatment of HaCaT cells with IL-36γ significantly upregulated the expression levels of ß-catenin, cyclin D1, and ki-67. IL-36γ also promoted the production of the inflammatory cytokines IFN-γ, IL-1ß and IL-6, suppressed the expression of filaggrin, involucrin, keratin 1 and keratin 5. Meanwhile, we demonstrated the role of IWP-2, an inhibitor of the Wnt signaling pathway, in IL-36γ-treated HaCaT cells. Collectively, our findings suggest that IL-36γ inhibits differentiation and induces inflammation of keratinocyte via Wnt signaling pathway in psoriasis, this indicated that downregulation of IL-36γ may be a potential therapeutic option in psoriasis.

Altered expression of IL36γ and IL36 receptor (IL1RL2) in the colon of patients with Hirschsprung's disease.

PURPOSE: Hirschsprung's disease associated enterocolitis (HAEC) is the most common cause of morbidity and mortality in Hirschsprung's disease (HSCR). Altered intestinal epithelial barrier function and abnormal microbiota are implicated in the pathogenesis of HAEC. IL-36γ, a member of the IL-1 superfamily, is involved in host defense and contributes to proinflammatory responses and development of inflammatory diseases. The IL36 receptor (IL1RL2) is an important mediator molecule in the inflammatory response. Animal data suggests that IL1RL2 is involved in mucosal healing. We designed this study to investigate the hypothesis that the IL-36γ axis is altered in HSCR. METHODS: We investigated IL-36γ and IL1RL2 expression in ganglionic and aganglionic bowel of HSCR patients (n = 10) and controls (n = 10). qPCR, Western blotting and confocal immunofluorescence were performed. MAIN RESULTS: qPCR and Western blot analysis revealed that IL-36γ is strongly expressed in the aganglionic and ganglionic colon of patients with HSCR. ILR1L2 expression was significantly decreased in HSCR specimens compared to controls (p < 0.05). Confocal microscopy revealed a markedly increased expression of IL36γ in the colonic epithelium of patients with HSCR compared to controls. IL1RL2 was localized in the colonic epithelium and showed a markedly decreased expression in all HSCR specimens. CONCLUSION: To our knowledge, we report for the first time the expression of IL36γ and ILRL2 in the colon of patients with HSCR. The increased expression of IL36γ and the markedly decreased expression of IL1RL2 in the aganglionic and ganglionic bowel in HSCR may result in an increased inflammatory response and altered mucosal response healing leading to the susceptibility to develop HAEC.

Role of Interleukin 36γ in Host Defense Against Tuberculosis.

Tuberculosis remains a major killer worldwide, not the least because of our incomplete knowledge of protective and pathogenic immune mechanism. The roles of the interleukin 1 (IL-1) and interleukin 18 pathways in host defense are well established, as are their regulation through the inflammasome complex. In contrast, the regulation of interleukin 36γ (IL-36γ), a recently described member of the IL-1 family, and its immunological relevance in host defense remain largely unknown. Here we show that Mycobacterium tuberculosis infection of macrophages induces IL-36γ production in a 2-stage-regulated fashion. In the first stage, microbial ligands trigger host Toll-like receptor and MyD88-dependent pathways, leading to IL-36γ secretion. In the second stage, endogenous IL-1ß and interleukin 18 further amplify IL-36γ synthesis. The relevance of this cytokine in the control of M. tuberculosis is demonstrated by IL-36γ-induced antimicrobial peptides and IL-36 receptor-dependent restriction of M. tuberculosis growth. Thus, we provide first insight into the induction and regulation of the proinflammatory cytokine IL-36γ during tuberculosis.

IL-36 antagonism blunts the proliferation and migration of oral squamous cell carcinoma cells.

IL-36 is known to mediate inflammation and fibrosis. Nevertheless, IL-36 signalling axis has also been implicated in cancer, although understanding of exact contribution of IL-36 to cancer progression is very limited, partly due to existence of multiple IL-36 ligands with agonistic and antagonistic function. Here we explored the role of IL-36 in oral squamous cell carcinoma (OSCC). Firstly, we analyzed expression of IL-36 ligands and receptor and found that the expression of IL-36γ was significantly higher in head and neck cancer (HNSCC) than that of normal tissues, and that the high expression of IL-36γ predicted poor clinical outcomes. Secondly, we investigated the direct effect of IL-36γ on OSCC cells and found that IL-36γ stimulated proliferation of OSCC cells with high expression of IL-36R expression. Interestingly, IL-36γ also promoted migration of OSCC cells with low to high IL-36R expression. Critically, both proliferation and migration of OSCC cells induced by IL-36γ were abrogated by anti-IL-36R mAb. Fittingly, RNA sequence analysis revealed that IL-36γ regulated genes involved in cell cycle and cell division. In summary, our results showed that IL-36γ can be a tumor-promoting factor, and targeting of IL-36R signalling may be a beneficial targeted therapy for patients with abnormal IL-36 signalling.

IL-36γ is secreted through an unconventional pathway using the Gasdermin D and P2X7R membrane pores.

Mucosal innate immunity functions as the first line of defense against invading pathogens. Members of the IL-1 family are key cytokines upregulated in the inflamed mucosa. Inflammatory cytokines are regulated by limiting their function and availability through their activation and secretion mechanisms. IL-1 cytokines secretion is affected by the lack of a signal peptide on their sequence, which prevents them from accessing the conventional protein secretion pathway; thus, they use unconventional protein secretion pathways. Here we show in mouse macrophages that LPS/ATP stimulation induces cytokine relocalization to the plasma membrane, and conventional secretion blockade using monensin or Brefeldin A triggers no IL-36γ accumulation within the cell. In silico modeling indicates IL-36γ can pass through both the P2X7R and Gasdermin D pores, and both IL-36γ, P2X7R and Gasdermin D mRNA are upregulated in inflammation; further, experimental blockade of these receptors' limits IL-36γ release. Our results demonstrate that IL-36γ is secreted mainly by an unconventional pathway through membrane pores formed by P2X7R and Gasdermin D.