IL-36 Cytokines: Their Roles in Asthma and Potential as a Therapeutic

Floxed Il1rl2 Locus with mCherry Reporter Element Reveals Distinct Expression Patterns of the IL-36 Receptor in Barrier Tissues

IL-36 cytokines are emerging as beneficial in immunity against pathogens and cancers but can also be detrimental when dysregulated in autoimmune and autoinflammatory conditions. Interest in targeting IL-36 activity for therapeutic purposes is rapidly growing, yet many unknowns about the functions of these cytokines remain. Thus, the availability of robust research tools is essential for both fundamental basic science and pre-clinical studies to fully access outcomes of any manipulation of the system. For this purpose, a floxed Il1rl2, the gene encoding the IL-36 receptor, mouse strain was developed to facilitate the generation of conditional knockout mice. The targeted locus was engineered to contain an inverted mCherry reporter sequence that upon Cre-mediated recombination will be flipped and expressed under the control of the endogenous Il1rl2 promoter. This feature can be used to confirm knockout in individual cells but also as a reporter to determine which cells express the IL-36 receptor IL-1RL2. The locus was confirmed to function as intended and further used to demonstrate the expression of IL-1RL2 in barrier tissues. Il1rl2 expression was detected in leukocytes in all barrier tissues. Interestingly, strong expression was observed in epithelial cells at locations in direct contact with the environment such as the skin, oral mucosa, the esophagus, and the upper airways, but almost absent from epithelial cells at more inward facing sites, including lung alveoli, the small intestine, and the colon. These findings suggest specialized functions of IL-1RL2 in outward facing epithelial tissues and cells. The generated mouse model should prove valuable in defining such functions and may also facilitate basic and translational research.

Interleukin-36 receptor antagonist stimulation in vitro inhibits peripheral and lung-resident T cell response isolated from patients with ventilator-associated pneumonia

Interleukin-36 (IL-36) cytokine family members play an immunomodulatory function to immune cells through IL-36 receptor signaling pathway. However, the regulatory role of IL-36 exerted on T cells is not completely elucidated in patients with ventilator-associated pneumonia (VAP). For this purpose, this study enrolled 51 VAP patients and 27 controls. IL-36 levels were measured by ELISA. The mRNA levels of IL-36 receptor subunits were determined by real-time PCR. CD4+ and CD8+ T cells were enriched, and stimulated with recombinant IL-36 receptor antagonist (IL-36RA). The influence of IL-36RA on transcription factors and cytokine secretions by CD4+ T cells was investigated. The modulatory function of IL-36RA on CD8+ T cells was assessed by measuring target cell death and cytokine secretions. There were no significant differences in serum IL-36 levels between VAP patients and controls. Only IL-36RA, but not IL-36α, IL-36β, or IL-36γ, in bronchoalveolar lavage fluid was elevated in infection site of VAP patients. IL-36 receptor subunits in CD4+ and CD8+ T cells were comparable between VAP patients and controls. 10 ng/mL of IL-36RA stimulation dampened peripheral effector CD4+ T cell response isolated from both VAP patients and controls. Target cell death mediated by CD8+ T cells isolated from BAFL of VAP patients was suppressed by 100 ng/mL of IL-36RA stimulation in vitro. The down-regulations of perforin, granzyme B, interferon-γ, tumor necrosis factor-α, and Fas ligand following IL-36RA stimulation in vitro were responsible for reduced CD8+ T cell-mediated cytotoxicity. IL-36RA revealed an immunosuppressive property for T cell response in vitro, and may be involved in the protective mechanism in VAP patients.

Role of neutrophils in cutaneous lupus erythematosus

There are various types of cutaneous lupus erythematosus (CLE), either with or without the association of systemic lupus erythematosus (SLE). In some of the subtypes of cutaneous lupus, histopathology reveals neutrophil infiltration in the lesional skin; however, the significance of neutrophils in CLE is not yet fully elucidated. Recent studies have shown that neutrophil extracellular traps (NETs) formation by activated neutrophils is observed in several types of CLE, including lupus panniculitis, subacute lupus erythematosus, and acute lupus erythematosus, although the number of reports is small. Excessive NETosis, due to either increased NETs formation or defective clearance of NETs, may play a role in the induction of autoimmunity and autoantibody production in SLE, as well as endothelial damage, thrombus formation, and vascular damage in the lesional skin. CLE is an excessive interferon-driven autoimmune disease. Plasmacytoid dendritic cells are located in lupus erythematosus skin and contribute to the etiology of skin lesions as a main producing cell of type I interferon. Neutrophils, monocytes, and keratinocytes also produce type I interferon via several triggers. Neutrophils play an important role in the innate immune response in SLE. In this review, several types of CLE with neutrophil infiltration, as well as the role of neutrophils are discussed.

Local neutrophil and eosinophil extracellular traps formation in pyodermatitis pyostomatitis vegetans

Pyodermatitis pyostomatitis vegetans is a rare inflammatory condition, affecting the skin and/or mucous membrane. Some cases include both skin and mucous involvement, whereas others develop either skin or mucous lesions only. The typically affected areas are the scalp, face, trunk and extremities, including the flexural areas and umbilicus. Clinical features show erosive granulomatous plaques, keratotic plaques with overlying crusts and pustular lesions. Among mucous lesions, oral mucosa is most frequently involved, and gingival erythema, shallow erosions, cobblestone-like papules on the buccal mucosa or upper hard palate of the oral cavity are also observed. Some of the lesions assume a 'snail track' appearance. Although there are several similarities between pyodermatitis pyostomatitis vegetans and other diseases, that is pyoderma gangrenosum, pemphigus vegetans and pemphigoid vegetans, the histopathological features of pyodermatitis pyostomatitis vegetans are unique in that epidermal hyperplasia, focal acantholysis and dense inflammatory infiltrates with intraepidermal and subepidermal eosinophilic microabscesses are observed. Direct immunofluorescence findings are principally negative. Activated neutrophils are supposed to play an important role in the pathogenesis of pyodermatitis pyostomatitis vegetans. The expression of IL-36 and neutrophil extracellular traps (NETs) was observed in the lesional skin, and additionally, eosinophil extracellular traps (EETs) was detected in pyodermatitis pyostomatitis vegetans. A possible pathogenic role of NETs and EETs in the innate immunity and autoinflammatory aspects of pyodermatitis pyostomatitis vegetans was discussed.

Mendelian randomization analysis to analyze the genetic causality between different levels of obesity and different allergic diseases

BACKGROUND

The causal relationship between obesity and different allergic diseases remains controversial.

METHODS

The Two Sample MR package and Phenoscanner database were used to obtain and filter Genome-Wide Association Study (GWAS) data from the Open GWAS database. Mendelian randomization (MR) analysis was used to study the causal relationship between different levels of obesity and different allergic diseases. The data sets related to obesity and asthma were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened by the limma package. Cluster Profiler and GO plot packages were used for enrichment analysis to verify the results of MR analysis.

RESULTS

Two-sample MR analysis showed a causal relationship between obesity and childhood allergy (age < 16), allergic asthma and atopic dermatitis (P < 0.05). In addition, there was also a causal relationship between allergic asthma and obesity (P < 0.05), while there was no genetic causal relationship between obesity and allergic rhinitis, eczema, lactose intolerance and so on (P > 0.05). Subgroup analysis revealed a causal relationship between both class 1 and class 2 obesity and childhood allergy (age < 16) (P < 0.05). Obesity class 1 was associated with allergic asthma, while obesity class 3 was associated with atopic dermatitis (P < 0.05). Bioinformatics analysis shows that there were common DEGs between obesity and allergic asthma.

CONCLUSION

Obesity is a risk factor for childhood allergy (age < 16), allergic asthma and atopic dermatitis, while allergic asthma is also a risk factor for obesity. Class 1 and class 2 obesity are both causally associated with childhood allergy (age < 16). In addition, there is a causal relationship between milder obesity and allergic asthma, while heavier obesity is causally related to atopic dermatitis.

Correlations between IL-36 family cytokines in peripheral blood and subjective and objective assessment results in patients with allergic rhinitis

BACKGROUND

Interleukin (IL)-36 family cytokines have received increasing attention, especially in the fields of inflammation and immunity research. However, whether IL-36 family cytokine levels are correlated with the results of the assessment of allergic rhinitis (AR) and affect the severity of AR remains unknown. Therefore, this study aimed to investigate the correlations between IL-36 family cytokine levels and subjective and objective assessment results and to further analyze the possible mechanisms of IL-36 family cytokines in the development of AR.

METHODS

An enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of the IL-36 family cytokines IL-36α, IL-36β, IL-36γ, IL-36Ra, and IL-38 in the peripheral blood of patients with AR. The condition of patients with AR was assessed by 22-item sino-nasal outcome test (SNOT-22) score, visual analogue scale (VAS) scores for disease severity, and serum inhalant allergen immunoglobulin E (IgE) detection. Correlations between IL-36 family cytokine levels and subjective and objective assessment results in patients with AR were analyzed.

RESULTS

The concentration of IL-36α in the peripheral blood of patients with AR was the highest, and the concentration of IL-36β was the lowest. The concentration of IL-36α was higher in juvenile patients than in adult patients, and there was a difference in the IL-36Ra level between the perennial allergen group and the seasonal allergen group. There was a positive correlation between IL-36α level and IL-36γ level, IL-36γ level and IL-36Ra level, and IL-36Ra level and IL-38 level, and IL-36β level was positively correlated with IL-36Ra and IL-38 levels, respectively. IL-36α level was positively correlated with VAS score for nasal congestion symptom. IL-36β level was positively correlated with the total VAS score for ocular symptoms and VAS scores for ocular itching and eye pain symptoms. However, there was no correlation between the levels of all cytokines in IL-36 family and SNOT-22 score, the number of positive inhaled allergens, or the highest positive intensity of allergen specific immunoglobulin E (sIgE).

CONCLUSION

Peripheral blood IL-36 family cytokines play an important role in AR, and the concentrations of IL-36α and IL-36β were related to the severity of symptoms in patients with AR.

Interleukin-36 Receptor Signaling Attenuates Epithelial Wound Healing in C57BL/6 Mouse Corneas

The IL-36 cytokines are known to play various roles in mediating the immune and inflammatory response to tissue injury in a context-dependent manner. This study investigated the role of IL-36R signaling in mediating epithelial wound healing in normal (NL) and diabetic (DM) C57BL/6 mouse corneas. The rate of epithelial wound closure was significantly accelerated in IL-36 receptor-deficient (IL-36R^-/-) compared to wild-type (WT) mice. Wounding increased IL-36α and -36γ but repressed IL-36R antagonist (IL-36Ra) expression in B6 mouse corneal epithelial cells. The wound-induced proinflammatory cytokines CXCL1 and CXCL2 were dampened, while the antimicrobial peptides (AMPs) S100A8 and A9 were augmented in IL-36R^-/- mouse corneas. Intriguingly, the expression of AMP LCN2 was augmented at the mRNA level. LCN2 deficiency resulted in an acceleration of epithelial wound healing. IL-36R deficiency also greatly increased the healing rate of the corneal epithelial wound in DM mice. IL-36R deficiency also suppressed IL-1β, IL-1Ra, and ICAM expression in unwounded-DM mice and wounded NL corneas. Opposing IL-1β and ICAM, the expression of IL-Ra in DM corneas of IL-36R^-/- mice was augmented. The presence of recombinant IL-1Ra and IL-36Ra accelerated epithelial wound closure in T1DM corneas of B6 mice. Our study revealed an unprecedented role of IL-36R signaling in controlling corneal epithelial wound healing in normal (NL) and diabetic (DM) mice. Our data suggest that IL-36Ra, similar to IL-1Ra, might be a therapeutic reagent for improving wound healing and reducing wound-associated ulceration, particularly in the cornea and potentially in the skin of DM patients.

Rhinovirus infection of the airway epithelium enhances mast cell immune responses via epithelial-derived interferons

BACKGROUND

Mast cells (MCs) within the airway epithelium in asthma are closely related to airway dysfunction, but cross talk between airway epithelial cells (AECs) and MCs in asthma remains incompletely understood. Human rhinovirus (RV) infections are key triggers for asthma progression, and AECs from individuals with asthma may have dysregulated antiviral responses.

OBJECTIVE

We utilized primary AECs in an ex vivo coculture model system to examine cross talk between AECs and MCs after epithelial rhinovirus infection.

METHODS

Primary AECs were obtained from 11 children with asthma and 10 healthy children, differentiated at air-liquid interface, and cultured in the presence of laboratory of allergic diseases 2 (LAD2) MCs. AECs were infected with rhinovirus serogroup A 16 (RV16) for 48 hours. RNA isolated from both AECs and MCs underwent RNA sequencing. Direct effects of epithelial-derived interferons on LAD2 MCs were examined by real-time quantitative PCR.

RESULTS

MCs increased expression of proinflammatory and antiviral genes in AECs. AECs demonstrated a robust antiviral response after RV16 infection that resulted in significant changes in MC gene expression, including upregulation of genes involved in antiviral responses, leukocyte activation, and type 2 inflammation. Subsequent ex vivo modeling demonstrated that IFN-β induces MC type 2 gene expression. The effects of AEC donor phenotype were small relative to the effects of viral infection and the presence of MCs.

CONCLUSIONS

There is significant cross talk between AECs and MCs, which are present in the epithelium in asthma. Epithelial-derived interferons not only play a role in viral suppression but also further alter MC immune responses including specific type 2 genes.

Exploring the transcriptomic changes underlying recombinant vaccine efficacy against Teladorsagia circumcincta in 3-month-old lambs

Teladorsagia circumcincta is an abomasal parasitic nematode that can cause serious issues in small ruminant production, which are aggravated by drug resistance. Vaccines have been suggested as a feasible, long-lasting alternative for control since adaptation to the host's immune mechanisms by helminths develops at a much slower pace than anthelmintic resistance. Recently, a T. circumcincta recombinant subunit vaccine yielded over a 60% reduction in egg excretion and worm burden and induced strong humoral and cellular anti-helminth responses in vaccinated 3-month-old Canaria Hair Breed (CHB) lambs, but Canaria Sheep (CS) of a similar age were not protected by the vaccine. Here, we compared the transcriptomic profiles in the abomasal lymph nodes of such 3-month-old CHB and CS vaccinates 40 days after infection with T. circumcincta to understand differences in responsiveness at the molecular level. In the CS, differentially expressed genes (DEG) identified were related to general immunity processes such as antigen presentation or antimicrobial proteins and down-regulation of inflammation and immune response through regulatory T cell-associated genes. However, upregulated genes in CHB vaccinates were associated with type-2 oriented immune responses, i.e., immunoglobulin production, activation of eosinophils, as well as tissue structure and wound repair-related genes and protein metabolism pathways such as DNA and RNA processing. These results highlight potentially more optimal timing and orientation of immune responses in CHB sheep compared to CS associated with vaccine-induced protection. The data obtained in this study thus deepens our understanding of variations in responsiveness to vaccination in young lamb and provides insights for vaccine refinement strategies.

Allergen immunotherapy: progress and future outlook

INTRODUCTION

Allergy, the immunological hypersensitivity to innocuous environmental compounds, is a global health problem. The disease triggers, allergens, are mostly proteins contained in various natural sources such as plant pollen, animal dander, dust mites, foods, fungi and insect venoms. Allergies can manifest with a wide range of symptoms in various organs, and be anything from just tedious to life-threatening. A majority of all allergy patients are self-treated with symptom-relieving medicines, while allergen immunotherapy (AIT) is the only causative treatment option.

AREAS COVERED

This review will aim to give an overview of the state-of-the-art allergy management, including the use of new biologics and the application of biomarkers, and a special emphasis and discussion on current research trends in the field of AIT.

EXPERT OPINION

Conventional AIT has proven effective, but the years-long treatment compromises patient compliance. Moreover, AIT is typically not offered in food allergy. Hence, there is a need for new, effective and safe AIT methods. Novel routes of administration (e.g. oral and intralymphatic), hypoallergenic AIT products and more effective adjuvants holds great promise. Most recently, the development of allergen-specific monoclonal antibodies for passive immunotherapy may also allow treatment of patients currently not treated or treatable.