IL33: Roles in Allergic Inflammation and Therapeutic Perspectives

Elevated levels of interleukin-33 are associated with asthma: A meta-analysis

BACKGROUND

Previous studies reported that patients with asthma showed higher levels of interleukin (IL)-33 in peripheral blood, compared to healthy control (HCs). However, we also noticed that there were no significant differences of IL-33 levels between controls and asthma patients in a recent study. We aim to conduct this meta-analysis and evaluate the feasibility of IL-33 in peripheral blood that may act as a promising biomarker in asthma.

METHODS

Articles published before December 2022 were searched in these databases (PubMed, Web of Science, EMBASE, and Google Scholar). We used STATA 12.0 software to compute the results.

RESULTS

The study showed that asthmatics showed higher IL-33 level in serum and plasma, compared to HCs (serum: standard mean difference [SMD] 2.06, 95% confidence interval [CI] 1.12-3.00, I²  = 98.4%, p < .001; plasma: SMD 3.67, 95% CI 2.32-5.03, I²  = 86.0%, p < .001). Subgroup analysis indicated that asthma adults showed higher IL-33 level in serum, compared to HCs, whereas no significant difference in IL-33 level in serum was showed between asthma children and HCs (adults: SMD 2.17, 95% CI 1.09-3.25; children: SMD 1.81, 95% CI -0.11 to 3.74). The study indicated that moderate and severe asthmatics showed higher IL-33 level in serum, compared to mild asthmatics (SMD 0.78, 95% CI 0.41-1.16, I²  = 66.2%, p = .011).

CONCLUSIONS

In conclusion, the main findings of present meta-analysis suggested that there was a significant correlation between IL-33 levels and the severity of asthma. Therefore, IL-33 levels of either serum or plasma may be regarded as a useful biomarker of asthma or the degree of disease.

Th2 high and mast cell gene signatures are associated with corticosteroid sensitivity in COPD

RATIONALE

Severe asthma and chronic obstructive pulmonary disease (COPD) share common pathophysiological traits such as relative corticosteroid insensitivity. We recently published three transcriptome-associated clusters (TACs) using hierarchical analysis of the sputum transcriptome in asthmatics from the Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes (U-BIOPRED) cohort comprising one Th2-high inflammatory signature (TAC1) and two Th2-low signatures (TAC2 and TAC3).

OBJECTIVE

We examined whether gene expression signatures obtained in asthma can be used to identify the subgroup of patients with COPD with steroid sensitivity.

METHODS

Using gene set variation analysis, we examined the distribution and enrichment scores (ES) of the 3 TACs in the transcriptome of bronchial biopsies from 46 patients who participated in the Groningen Leiden Universities Corticosteroids in Obstructive Lung Disease COPD study that received 30 months of treatment with inhaled corticosteroids (ICS) with and without an added long-acting β-agonist (LABA). The identified signatures were then associated with longitudinal clinical variables after treatment. Differential gene expression and cellular convolution were used to define key regulated genes and cell types.

MEASUREMENTS AND MAIN RESULTS

Bronchial biopsies in patients with COPD at baseline showed a wide range of expression of the 3 TAC signatures. After ICS±LABA treatment, the ES of TAC1 was significantly reduced at 30 months, but those of TAC2 and TAC3 were unaffected. A corticosteroid-sensitive TAC1 signature was developed from the TAC1 ICS-responsive genes. This signature consisted of mast cell-specific genes identified by single-cell RNA-sequencing and positively correlated with bronchial biopsy mast cell numbers following ICS±LABA. Baseline levels of gene transcription correlated with the change in RV/TLC %predicted following 30-month ICS±LABA.

CONCLUSION

Sputum-derived transcriptomic signatures from an asthma cohort can be recapitulated in bronchial biopsies of patients with COPD and identified a signature of airway mast cells as a predictor of corticosteroid responsiveness.

Single cell analysis reveals satellite cell heterogeneity for proinflammatory chemokine expression

Background: The expression of proinflammatory signals at the site of muscle injury are essential for efficient tissue repair and their dysregulation can lead to inflammatory myopathies. Macrophages, neutrophils, and fibroadipogenic progenitor cells residing in the muscle are significant sources of proinflammatory cytokines and chemokines. However, the inducibility of the myogenic satellite cell population and their contribution to proinflammatory signaling is less understood.

Methods: Mouse satellite cells were isolated and exposed to lipopolysaccharide (LPS) to mimic sterile skeletal muscle injury and changes in the expression of proinflammatory genes was examined by RT-qPCR and single cell RNA sequencing. Expression patterns were validated in skeletal muscle injured with cardiotoxin by RT-qPCR and immunofluorescence.

Results: Satellite cells in culture were able to express Tnfa, Ccl2, and Il6, within 2 h of treatment with LPS. Single cell RNA-Seq revealed seven cell clusters representing the continuum from activation to differentiation. LPS treatment led to a heterogeneous pattern of induction of C-C and C-X-C chemokines (e.g., Ccl2, Ccl5, and Cxcl0) and cytokines (e.g., Tgfb1, Bmp2, Il18, and Il33) associated with innate immune cell recruitment and satellite cell proliferation. One cell cluster was enriched for expression of the antiviral interferon pathway genes under control conditions and LPS treatment. Activation of this pathway in satellite cells was also detectable at the site of cardiotoxin induced muscle injury.

Conclusion: These data demonstrate that satellite cells respond to inflammatory signals and secrete chemokines and cytokines. Further, we identified a previously unrecognized subset of satellite cells that may act as sensors for muscle infection or injury using the antiviral interferon pathway.

Platelet Activating Factor Activity Modulates Hyperoxic Neonatal Lung Injury Severity

Hyperoxia-induced inflammation contributes significantly to developmental lung injury and bronchopulmonary dysplasia (BPD) in preterm infants. Platelet activating factor (PAF) is known to be a major driver of inflammation in lung diseases such as asthma and pulmonary fibrosis, but its role in BPD has not been previously investigated. Therefore, to determine whether PAF signaling independently modulates neonatal hyperoxic lung injury and BPD pathogenesis, lung structure was assessed in 14 day-old C57BL/6 wild-type (WT) and PAF receptor knockout (PTAFR KO) mice that were exposed to 21% (normoxia) or 85% O ₂ (hyperoxia) from postnatal day 4. Lung morphometry showed that PTAFR KO mice had attenuated hyperoxia-induced alveolar simplification when compared to WT mice. Functional analysis of gene expression data from hyperoxia-exposed vs. normoxia-exposed lungs of WT and PTAFR KO showed that the most upregulated pathways were the hypercytokinemia/hyperchemokinemia pathway in WT mice, NAD signaling pathway in PTAFR KO mice, and agranulocyte adhesion and diapedesis as well as other pro-fibrotic pathways such as tumor microenvironment and oncostatin-M signaling in both mice strains, indicating that PAF signaling may contribute to inflammation but may not be a significant mediator of fibrotic processes during hyperoxic neonatal lung injury. Gene expression analysis also indicated increased expression of pro-inflammatory genes such as CXCL1, CCL2 and IL-6 in the lungs of hyperoxia-exposed WT mice and metabolic regulators such as HMGCS2 and SIRT3 in the lungs of PTAFR KO mice, suggesting that PAF signaling may modulate BPD risk through changes in pulmonary inflammation and/or metabolic reprogramming in preterm infants.

Current Understanding of the Role of Eosinophils in CRSwNP and Implications for Treatment with Mepolizumab and Benralizumab

BACKGROUND

International consensus statements now subdivide chronic rhinosinusitis (CRS) into several phenotypes and endotypes, including the presence of polyps (CRSwNP) and eosinophilia (eCRSwNP). Biological treatments aimed at blocking eosinophilic inflammation in CRSwNP via interleukin 5 (IL5) or the interleukin 5 receptor (IL5R) have demonstrated limited efficacy thus far.

OBJECTIVE

To review the pathophysiology of eCRSwNP, the evidence for mepolizumab (anti-IL5) and benralizumab (anti-IL5R) in CRSwNP, and to highlight areas for future research and therapeutic intervention.

METHODS

Primary and secondary literature search.

RESULTS

Clinical trials on mepolizumab and benralizumab in CRSwNP are limited and restricted by trial design which prevents direct comparison with other interventions, including surgery. Both agents would appear to provide some benefit in reducing nasal polyp size but limited clinical patient benefit. Molecular biological research highlights that eCRSwNP can occur in the absence of IL5 and that other cells/cytokines play an important part in the disease's pathophysiology.

CONCLUSION

Blockade of IL5/IL5R alone would appear to provide limited "real life" clinical benefit in patients with CRSwNP due to the complexities of the pathophysiology of the condition. Therapy aimed at several simultaneous cytokine targets has logic but well-designed trials are unlikely to be forthcoming in the short term due to the financial cost and commercial conflicts of interest.

Effect of transfected induced pluripotent stem cells with Decorin gene on control of lung remodeling in allergic asthma

Asthma is a complex respiratory disease, which is controlled by genetic and environmental factors. Type 2-dominant immune response is responsible for asthma. Decorin (Dcn) and stem cells have modulatory effect on immune system and may control tissue remodeling and asthma pathophysiology. In this study, immunomodulatory effect of transduced induced pluripotent stem cells (iPSCs) with expression of Dcn gene on allergic asthma pathophysiology was evaluated. After transduction of iPSCs with Dcn gene, allergic asthma mice were treated with iPSCs and transduced iPSCs via intrabronchial. Then, airway hyperresponsiveness (AHR), levels of interleukin (IL)-4, IL-5, IL-13, IL-33, total IgE, leukotrienes (LTs) B4, C4, hydroxyproline (HP) content, and transforming growth factor-beta (TGF-β) were measured. Also, lung histopathology study was done. AHR, levels of IL-4, IL-5, IL-13, IL-33, total IgE, LTs B4, C4, TGF-β, HP content, mucus secretion, goblet cell hyperplasia, and eosinophilic inflammation were controlled by iPSCs and transduced iPSCs treatment. Therapeutic effect of iPSCs could control main allergic asthma symptoms and related pathophysiologic mechanisms and the effect can be increased when applied with Dcn expression gene.

Persisting Cryptococcus yeast species Vishniacozyma victoriae and Cryptococcus neoformans elicit unique airway inflammation in mice following repeated exposure

Background

Allergic airway disease (AAD) is a growing concern in industrialized nations and can be influenced by fungal exposures. Basidiomycota yeast species such as Cryptococcus neoformans are known to exacerbate allergic airway disease; however, recent indoor assessments have identified other Basidiomycota yeasts, including Vishniacozyma victoriae (syn. Cryptococcus victoriae), to be prevalent and potentially associated with asthma. Until now, the murine pulmonary immune response to repeated V. victoriae exposure was previously unexplored.

Objective

This study aimed to compare the immunological impact of repeated pulmonary exposure to Cryptococcus yeasts.

Methods

Mice were repeatedly exposed to an immunogenic dose of C. neoformans or V. victoriae via oropharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and lungs were collected to examine airway remodeling, inflammation, mucous production, cellular influx, and cytokine responses at 1 day and 21 days post final exposure. The responses to C. neoformans and V. victoriae were analyzed and compared.

Results

Following repeated exposure, both C. neoformans and V. victoriae cells were still detectable in the lungs 21 days post final exposure. Repeated C. neoformans exposure initiated myeloid and lymphoid cellular infiltration into the lung that worsened over time, as well as an IL-4 and IL-5 response compared to PBS-exposed controls. In contrast, repeated V. victoriae exposure induced a strong CD4+ T cell-driven lymphoid response that started to resolve by 21 days post final exposure.

Discussion

C. neoformans remained in the lungs and exacerbated the pulmonary immune responses as expected following repeated exposure. The persistence of V. victoriae in the lung and strong lymphoid response following repeated exposure were unexpected given its lack of reported involvement in AAD. Given the abundance in indoor environments and industrial utilization of V. victoriae, these results highlight the importance to investigate the impact of frequently detected fungal organisms on the pulmonary response following inhalational exposure. Moreover, it is important to continue to address the knowledge gap involving Basidiomycota yeasts and their impact on AAD.

Targeting interleukin-33 and thymic stromal lymphopoietin pathways for novel pulmonary therapeutics in asthma and COPD

Interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP) are alarmins that are released upon airway epithelial injury from insults such as viruses and cigarette smoke, and play critical roles in the activation of immune cell populations such as mast cells, eosinophils and group 2 innate lymphoid cells. Both cytokines were previously understood to primarily drive type 2 (T2) inflammation, but there is emerging evidence for a role for these alarmins to additionally mediate non-T2 inflammation, with recent clinical trial data in asthma and COPD cohorts with non-T2 inflammation providing support. Currently available treatments for both COPD and asthma provide symptomatic relief with disease control, improving lung function and reducing exacerbation rates; however, there still remains an unmet need for further improving lung function and reducing exacerbations, particularly for those not responsive to currently available treatments. The epithelial cytokines/alarmins are involved in exacerbations; biologics targeting TSLP and IL-33 have been shown to reduce exacerbations in moderate-to-severe asthma, either in a broad population or in specific subgroups, respectively. For COPD, while there is clinical evidence for IL-33 blockade impacting exacerbations in COPD, clinical data from anti-TSLP therapies is awaited. Clinical data to date support an acceptable safety profile for patients with airway diseases for both anti-IL-33 and anti-TSLP antibodies in development. We examine the roles of IL-33 and TSLP, their potential use as drug targets, and the evidence for target patient populations for COPD and asthma, together with ongoing and future trials focused on these targets.

Airway remodeling heterogeneity in asthma and its relationship to disease outcomes

Asthma affects an estimated 262 million people worldwide and caused over 461,000 deaths in 2019. The disease is characterized by chronic airway inflammation, reversible bronchoconstriction, and airway remodeling. Longitudinal studies have shown that current treatments for asthma (inhaled bronchodilators and corticosteroids) can reduce the frequency of exacerbations, but do not modify disease outcomes over time. Further, longitudinal studies in children to adulthood have shown that these treatments do not improve asthma severity or fixed airflow obstruction over time. In asthma, fixed airflow obstruction is caused by remodeling of the airway wall, but such airway remodeling also significantly contributes to airway closure during bronchoconstriction in acute asthmatic episodes. The goal of the current review is to understand what is known about the heterogeneity of airway remodeling in asthma and how this contributes to the disease process. We provide an overview of the existing knowledge on airway remodeling features observed in asthma, including loss of epithelial integrity, mucous cell metaplasia, extracellular matrix remodeling in both the airways and vessels, angiogenesis, and increased smooth muscle mass. While such studies have provided extensive knowledge on different aspects of airway remodeling, they have relied on biopsy sampling or pathological assessment of lungs from fatal asthma patients, which have limitations for understanding airway heterogeneity and the entire asthma syndrome. To further understand the heterogeneity of airway remodeling in asthma, we highlight the potential of in vivo imaging tools such as computed tomography and magnetic resonance imaging. Such volumetric imaging tools provide the opportunity to assess the heterogeneity of airway remodeling within the whole lung and have led to the novel identification of heterogenous gas trapping and mucus plugging as important predictors of patient outcomes. Lastly, we summarize the current knowledge of modification of airway remodeling with available asthma therapeutics to highlight the need for future studies that use in vivo imaging tools to assess airway remodeling outcomes.

IL-5-producing CD4+ T cells and eosinophils cooperate to enhance response to immune checkpoint blockade in breast cancer

Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4⁺ T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8⁺ T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy.

Impact of a Saccharomyces cerevisiae fermentation product during an intestinal barrier challenge in lactating Holstein cows on ileal microbiota and markers of tissue structure and immunity

Feeding a Saccharomyces cerevisiae fermentation product (SCFP; NutriTek, Diamond V, Cedar Rapids, IA) during periods of metabolic stress is beneficial to the health of dairy cows partially through its effect on the gut microbiota. Whether SCFP alters the ileal microbiota in lactating cows during intestinal challenges induced by feed restriction (FR) is not known. We used 16S rRNA sequencing to assess if feeding SCFP during FR to induce gut barrier dysfunction alters microbiota profiles in the ileum. The mRNA abundance of key genes associated with tissue structures and immunity was also detected. Multiparous cows (97.1 ± 7.6 days in milk (DIM); n = 7 per treatment) fed a control diet or the control plus 19 g/d NutriTek for 9 wk were subjected to an FR challenge for 5 d, during which they were fed 40% of their ad libitum intake from the 7 d before FR. All cows were slaughtered at the end of FR. DNA extracted from ileal digesta was subjected to PacBio Full-Length 16S rRNA gene sequencing. High-quality amplicon sequence analyses were performed with Targeted Amplicon Diversity Analysis and MicrobiomeAnalyst. Functional analysis was performed and analyzed using PICRUSt and STAMP. Feeding SCFP did not (P > 0.05) alter dry matter intake, milk yield, or milk components during FR. In addition, SCFP supplementation tended (P = 0.07) to increase the relative abundance of Proteobacteria and Bifidobacterium animalis. Compared with controls, feeding SCFP increased the relative abundance of Lactobacillales (P = 0.03). Gluconokinase, oligosaccharide reducing-end xylanase, and 3-hydroxy acid dehydrogenase were among the enzymes overrepresented (P < 0.05) in response to feeding SCFP. Cows fed SCFP had a lower representation of adenosylcobalamin biosynthesis I (early cobalt insertion) and pyrimidine deoxyribonucleotides de novo biosynthesis III (P < 0.05). Subsets of the Firmicutes genus, Bacteroidota phylum, and Treponema genus were correlated with the mRNA abundance of genes associated with ileal integrity (GCNT3, GALNT5, B3GNT3, FN1, ITGA2, LAMB2) and inflammation (AOX1, GPX8, CXCL12, CXCL14, CCL4, SAA3). Our data indicated that the moderate FR induced dysfunction of the ileal microbiome, but feeding SCFP increased the abundance of some beneficial gut probiotic bacteria and other species related to tissue structures and immunity.

IL-33 mediates Pseudomonas induced airway fibrogenesis and is associated with CLAD

BACKGROUND

Long term outcomes of lung transplantation are impacted by the occurrence of chronic lung allograft dysfunction (CLAD). Recent evidence suggests a role for the lung microbiome in the occurrence of CLAD, but the exact mechanisms are not well defined. We hypothesize that the lung microbiome inhibits epithelial autophagic clearance of pro-fibrotic proteins in an IL-33 dependent manner, thereby augmenting fibrogenesis and risk for CLAD.

METHODS

Autopsy derived CLAD and non-CLAD lungs were collected. IL-33, P62 and LC3 immunofluorescence was performed and assessed using confocal microscopy. Pseudomonas aeruginosa (PsA), Streptococcus Pneumoniae (SP), Prevotella Melaninogenica (PM), recombinant IL-33 or PsA-lipopolysaccharide was co-cultured with primary human bronchial epithelial cells (PBEC) and lung fibroblasts in the presence or absence of IL-33 blockade. Western blot analysis and quantitative reverse transcription (qRT) PCR was performed to evaluate IL-33 expression, autophagy, cytokines and fibroblast differentiation markers. These experiments were repeated after siRNA silencing and upregulation (plasmid vector) of Beclin-1.

RESULTS

Human CLAD lungs demonstrated markedly increased expression of IL-33 and reduced basal autophagy compared to non-CLAD lungs. Exposure of co-cultured PBECs to PsA, SP induced IL-33, and inhibited PBEC autophagy, while PM elicited no significant response. Further, PsA exposure increased myofibroblast differentiation and collagen formation. IL-33 blockade in these co-cultures recovered Beclin-1, cellular autophagy and attenuated myofibroblast activation in a Beclin-1 dependent manner.

CONCLUSION

CLAD is associated with increased airway IL-33 expression and reduced basal autophagy. PsA induces a fibrogenic response by inhibiting airway epithelial autophagy in an IL-33 dependent manner.

IL1RAP expression and the enrichment of IL-33 activation signatures in severe neutrophilic asthma

BACKGROUND

Interleukin (IL)-33 is an upstream regulator of type 2 (T2) eosinophilic inflammation and has been proposed as a key driver of some asthma phenotypes.

OBJECTIVE

To derive gene signatures from in vitro studies of IL-33-stimulated cells and use these to determine IL-33-associated enrichment patterns in asthma.

METHODS

Signatures downstream of IL-33 stimulation were derived from our in vitro study of human mast cells and from public datasets of in vitro stimulated human basophils, type 2 innate lymphoid cells (ILC2), regulatory T cells (Treg) and endothelial cells. Gene Set Variation Analysis (GSVA) was used to probe U-BIOPRED and ADEPT sputum transcriptomics to determine enrichment scores (ES) for each signature according to asthma severity, sputum granulocyte status and previously defined molecular phenotypes.

RESULTS

IL-33-activated gene signatures were cell-specific with little gene overlap. Individual signatures, however, were associated with similar signalling pathways (TNF, NF-κB, IL-17 and JAK/STAT signalling) and immune cell differentiation pathways (Th17, Th1 and Th2 differentiation). ES for IL-33-activated gene signatures were significantly enriched in asthmatic sputum, particularly in patients with neutrophilic and mixed granulocytic phenotypes. IL-33 mRNA expression was not elevated in asthma whereas the expression of mRNA for IL1RL1, the IL-33 receptor, was up-regulated in the sputum of severe eosinophilic asthma. The mRNA expression for IL1RAP, the IL1RL1 co-receptor, was greatest in severe neutrophilic and mixed granulocytic asthma.

CONCLUSIONS

IL-33-activated gene signatures are elevated in neutrophilic and mixed granulocytic asthma corresponding with IL1RAP co-receptor expression. This suggests incorporating T2-low asthma in anti-IL-33 trials.

Protein and mRNA expression of interleukin-33 in periodontally diseased and healthy individuals and impact of nonsurgical periodontal therapy in salivary IL-33 levels

Background

Interleukin (IL)-33 is a member of IL-1 beta family of cytokines having a pivotal role in bone destruction. However, its role in periodontal disease is not clearly established. The objective of the present study was to evaluate salivary and gingival IL-33 expression in periodontally healthy and diseased individuals. The change in salivary IL-33 after nonsurgical therapy was also analyzed.

Materials and Methods

Salivary IL-33 concentration was estimated using enzyme-linked immunosorbent assay in periodontally healthy and diseased individuals (30 in each group). Re-evaluation was done in periodontitis patients after 6 weeks of nonsurgical therapy. Further, the messenger ribonucleic acid expression of IL-33 in healthy and diseased gingival tissues was also examined using reverse transcriptase-polymerase chain reaction and correlated with IL-1 beta messenger ribonucleic acid.

Results

Salivary IL-33 concentration in periodontitis patients was 1.65 fold higher than healthy controls (P < 0.0001), and 16% reduction was noticed after nonsurgical treatment. Salivary IL-33 concentration could be used to differentiate periodontitis from health at a cutoff value of 543.16 ng/mL with 93.33% sensitivity and 90% specificity (area under the curve 0.92). Upregulated gingival expression of IL-33 was also noted in periodontitis patients, and it was positively correlated with IL-1 beta (r = 0.7).

Conclusion

The study reconfirms the role of IL-33 in periodontal disease, proposed a threshold value of differentiating healthy and periodontitis patients, and suggests IL-33 as a potential diagnostic biomarker for periodontal disease and to evaluate the response to periodontal therapy.

Molecular links between allergy and cancer

Epidemiologic studies show both positive and negative associations between allergies and cancer. Allergic diseases may protect against tumorigenesis by promoting the immune surveillance, while carcinogenesis may be promoted through inflammatory responses from allergies. Histamine receptor antagonists are the focus of recent cancer studies because of their promising beneficial effect on tumor development. Also, cytokines, particularly IL-4 or IL-33, IgE as well as allergy-related immune cells such as eosinophils can contribute to tumor growth suppression. Depending on cancer types, cancer therapy may be more beneficial when considering combinatorial immunotherapy. In this review, we give an overview on molecular links between allergies and cancer.

IL-33 and the Cytokine Storm in COVID-19: From a Potential Immunological Relationship towards Precision Medicine

Coronavirus SARS-CoV-2 has represented, and still represents, a real challenge from a clinical, diagnostic and therapeutic point of view. During acute infection, the increased levels of pro-inflammatory cytokines, which are involved in the pathology of disease and the development of SARS-CoV-2-induced acute respiratory disease syndrome, the life-threatening form of this infection, are correlated with patient survival and disease severity. IL-33, a key cytokine involved in both innate and adaptive immune responses in mucosal organs, can increase airway inflammation, mucus secretion and Th2 cytokine synthesis in the lungs, following respiratory infections. Similar to cases of exposure to known respiratory virus infections, exposure to SARS-CoV-2 induces the expression of IL-33, correlating with T-cell activation and lung disease severity. In this work, we analyse current evidence regarding the immunological role of IL-33 in patients affected by COVID-19, to evaluate not only the clinical impact correlated to its production but also to identify possible future immunological therapies that can block the most expressed inflammatory molecules, preventing worsening of the disease and saving patient lives.

Single-cell atlas of murine adrenal glands reveals immune-adrenal crosstalk during systemic <i>Candida albicans</i> infection

Fungal sepsis remains a major health threat with high mortality, where the adrenal gland stress response has been rarely reported. <i>Candida albicans</i> (<i>C.albicans</i>) is the most common opportunistic fungal pathogen of life-threatening disseminated candidiasis and fungal sepsis. In the present study, we performed single-cell RNA sequencing (scRNA-Seq) using the 10x Genomics platform to analyze the changes in murine adrenal transcriptome following systemic <i>C.albicans</i> infection. A total of 16 021 cells were categorized into 18 transcriptionally distinct clusters, representing adrenocortical cells, endothelial cells, various immune cells, mesenchymal cells, smooth muscle cells, adrenal capsule, chromaffin cells, neurons and glials. As the main cell component in the adrenal gland responsible for steroidogenesis, the adrenocortical cells dramatically diminished and were further grouped into 10 subclusters, which differently distributed in the infected and uninfected samples. Pseudo-time analysis revealed transitions of the adrenocortical cells from the initial normal states to active or dysfunctional states following systemic <i>C.albicans</i> infection <i>via</i> two trajectory paths. Endothelial cells in the highly vascularized organ of adrenal gland further proliferated following infection, with the upregulation of genes positively regulating angiogenesis and downregulation of protective genes of endothelial cells. Immune cells were also excessively infiltrated in adrenal glands of <i>C.albicans</i>-infected mice. Macrophages dominated the immune microenvironments in murine adrenal glands both before and after <i>C.albicans</i> infection, mediating the crosstalk among the steroid-producing cells, endothelial cells and immune cells within the adrenal gland. NLR family, pyrin domain containing 3 (NLRP3, encoded by <i>Nlrp3</i>) and complement receptor 3 (CR3, encoded by <i>Itgam</i>) were found to be significantly upregulated on the adrenal macrophages upon systemic <i>C.albicans</i> infection and might play critical roles in mediating the myeloid response. Meanwhile, the number and strength of the interactions between the infiltrating immune cells and adrenal resident cells were unveiled by cell-cell communication analysis to be dramatically increased after systemic <i>C.albicans</i> infection, indicating that the immune-adrenal crosstalk might contribute to the compromised functions of adrenal cells. Overall, our comprehensive picture of the murine adrenal gland microenvironment in systemic <i>C.albicans</i> infection provides deeper insights into the immune-adrenal cell communications during fungal sepsis.

Serum Levels of Selected IL-1 Family Cytokines in Patients with Morphea

Morphea/localized scleroderma (LoS) represents an inflammatory-sclerotic skin disease, the pathogenesis of which is not fully understood. Given the important role of IL-1 family cytokines in the development and therapy of inflammatory diseases, including systemic sclerosis, we analyzed the clinical significance of serum levels of selected IL-1 family cytokines (IL-1α, IL-1β, IL-18, IL-33, IL-37 and IL-38) in LoS patients (n = 30) using the standardized disease assessment tools and comparison to healthy controls (n = 28). We also compared the pre- and post-treatment concentrations, i.e., before and after systemic (glucocorticosteroids and/or methotrexate) and/or topical (topical glucocorticosteroids and/or calcineurin inhibitors). Our findings did not reveal significant differences in baseline IL-1α, IL-1β, IL-18, IL-33, IL-37 and IL-38 levels between LoS group and HCs; however, after treatment, there were marked changes in concentrations of IL-1α and IL-33 within LoS group as well as in comparison to HCs. We also found significant negative correlations between PGA-A and IL-1α concentration as well as between mLoSSI and IL-1α after treatment. Furthermore, we showed an inverse correlation of baseline IL-1β levels with mLoSSI scores of borderline significance. We believe that IL-1α and IL-33, as well as Il-1β, may be potential mediators and targets of interest in LoS.

Peribronchial Inflammation Resulting from Regulatory T Cell Deficiency Damages the Respiratory Epithelium and Disturbs Barrier Function

Regulatory T cells (Tregs) that express the transcription factor Foxp3 have a critical role in limiting inflammatory processes and tissue damage. Whether Tregs are functional in maintaining epithelial barriers and in control of tight junction expression has not yet been explored. In this study, we investigated the effect of Treg deficiency on the airway epithelial barrier in an experimental murine model in which diphtheria toxin was repeatedly injected in Foxp3-diphtheria toxin receptor (DTR) mice to deplete Tregs. This resulted in spontaneous peribronchial inflammation and led to a systemic and local increase of IL-4, IL-5, CCL3, IFN-γ, and IL-10 and a local (lung) increase of IL-6 and IL-33 and decreased amphiregulin levels. Moreover, Treg depletion increased airway permeability and decreased epithelial tight junction (protein and mRNA) expression. CTLA4-Ig treatment of Treg-depleted mice almost completely prevented barrier dysfunction together with suppression of lung inflammation and cytokine secretion. Treatment with anti–IL-4 partly reversed the effects of Treg depletion on tight junction expression, whereas neutralization of IL-6 of IFN-γ had either no effect or only a limited effect. We conclude that Tregs are essential to protect the epithelial barrier at the level of tight junctions by restricting spontaneous T cell activation and uncontrolled secretion of cytokines, in particular IL-4, in the bronchi.

The Genetic Factors of the Airway Epithelium Associated with the Pathology of Asthma

Asthma is a chronic disease of the airways characterized by inflammation, tightened muscles, and thickened airway walls leading to symptoms such as shortness of breath, chest tightness, and cough in patients. The increased risk of asthma in children of asthmatics parents supports the existence of genetic factors involved in the pathogenesis of this disease. Genome-wide association studies have discovered several single nucleotide polymorphisms associated with asthma. These polymorphisms occur within several genes and can contribute to different asthma phenotypes, affect disease severity, and clinical response to different therapies. The complexity in the etiology of asthma also results from interactions between environmental and genetic factors. Environmental exposures have been shown to increase the prevalence of asthma in individuals who are genetically susceptible. This review summarizes what is currently known about the genetics of asthma in relation to risk, response to common treatments, and gene-environmental interactions.

Emerging roles for IL-25 and IL-33 in colorectal cancer tumorigenesis

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide, and is largely refractory to current immunotherapeutic interventions. The lack of efficacy of existing cancer immunotherapies in CRC reflects the complex nature of the unique intestinal immune environment, which serves to maintain barrier integrity against pathogens and harmful environmental stimuli while sustaining host-microbe symbiosis during homeostasis. With their expression by barrier epithelial cells, the cytokines interleukin-25 (IL-25) and IL-33 play key roles in intestinal immune responses, and have been associated with inappropriate allergic reactions, autoimmune diseases and cancer pathology. Studies in the past decade have begun to uncover the important roles of IL-25 and IL-33 in shaping the CRC tumour immune microenvironment, where they may promote or inhibit tumorigenesis depending on the specific CRC subtype. Notably, both IL-25 and IL-33 have been shown to act on group 2 innate lymphoid cells (ILC2s), but can also stimulate an array of other innate and adaptive immune cell types. Though sometimes their functions can overlap they can also produce distinct phenotypes dependent on the differential distribution of their receptor expression. Furthermore, both IL-25 and IL-33 modulate pathways previously known to contribute to CRC tumorigenesis, including angiogenesis, tumour stemness, invasion and metastasis. Here, we review our current understanding of IL-25 and IL-33 in CRC tumorigenesis, with specific focus on dissecting their individual function in the context of distinct subtypes of CRC, and the potential prospects for targeting these pathways in CRC immunotherapy.

Integrated proteomic analysis to explore the molecular regulation mechanism of IL-33 mRNA increased by black carbon in the human endothelial cell line EA.hy926

Black carbon (BC) correlates with the occurrence and progression of atherosclerosis and other cardiovascular diseases. Increasing evidence has demonstrated that BC could impair vascular endothelial cells, but the underlying mechanisms remain obscure. It is known that IL-33 exerts a significant biological role in cardiovascular disease, but little is known about the molecular regulation of IL-33 expression at present. We first found that BC significantly increased IL-33 mRNA in EA.hy926 cells in a concentration and time-dependent manner, and we conducted this study to explore its underlying mechanism. We identified that BC induced mitochondrial damage and suppressed autophagy function in EA.hy926 cells, as evidenced by elevation of the aspartate aminotransferase (GOT2), reactive oxygen species (ROS) and p62, and the reduction of mitochondrial membrane potential (ΔΨm). However, ROS cannot induce IL-33 mRNA-production in BC-exposed EA.hy926 cells. Further, experiments revealed that BC could promote IL-33 mRNA production through the PI3K/Akt/AP-1 and p38/AP-1 signaling pathways. It is concluded that BC could induce oxidative stress and suppress autophagy function in endothelial cells. This study also provided evidence that the pro-cardiovascular-diseases properties of BC may be due to its ability to stimulate the PI3K/AKT/AP-1 and p38/AP-1 pathway, further activate IL-33 and ultimately result in a local vascular inflammation.

Interrelationship and Sequencing of Interleukins4, 13, 31, and 33 - An Integrated Systematic Review: Dermatological and Multidisciplinary Perspectives

The interrelations and sequencing of interleukins are complex (inter)actions where each interleukin can stimulate the secretion of its preceding interleukin. In this paper, we attempt to summarize the currently known roles of IL-4, IL-13, IL-31, and IL-33 from a multi-disciplinary perspective. In order to conduct a comprehensive review of the current literature, a search was conducted using PubMed, Google Scholar, Medscape, UpToDate, and Key Elsevier for keywords. The results were compiled from case reports, case series, letters, and literature review papers, and analyzed by a panel of multi-disciplinary specialist physicians for relevance. Based on 173 results, we compiled the following review of interleukin signaling and its clinical significance across a multitude of medical specialties. Interleukins are at the bed rock of a multitude of pathologies across different organ systems and understanding their role will likely lead to novel treatments and better outcomes for our patients. New interleukins are being described, and the role of this inflammatory cascade is still coming to light. We hope this multi-discipline review on the role interleukins play in current pathology assists in this scope.

Trifuhalol A Suppresses Allergic Inflammation through Dual Inhibition of TAK1 and MK2 Mediated by IgE and IL-33

The activation and degranulation of immune cells play a pivotal role in allergic inflammation, a pathological condition that includes anaphylaxis, pruritus, and allergic march-related diseases. In this study, trifuhalol A, a phlorotannin isolated from Agarum cribrosum, inhibited the degranulation of immune cells and the biosynthesis of IL-33 and IgE in differentiated B cells and keratinocytes, respectively. Additionally, trifuhalol A suppressed the IL-33 and IgE-mediated activation of RBL-2H3 cells through the regulation of the TAK1 and MK2 pathways. Hence, the effect of trifuhalol A on allergic inflammation was evaluated using a Compound 48/80-induced systemic anaphylaxis mouse model and a house dust mite (HDM)-induced atopic dermatitis (AD) mouse model. Trifuhalol A alleviated anaphylactic death and pruritus, which appeared as an early-phase reaction to allergic inflammation in the Compound 48/80-induced systemic anaphylaxis model. In addition, trifuhalol A improved symptoms such as itching, edema, erythema, and hyperkeratinization in HDM-induced AD mice as a late-phase reaction. Moreover, the expression of IL-33 and thymic stromal lymphopoietin, inflammatory cytokines secreted from activated keratinocytes, was significantly reduced by trifuhalol A administration, resulting in the reduced infiltration of immune cells into the skin and a reduction in the blood levels of IgE and IL-4. In summarizing the above results, these results confirm that trifuhalol A is a potential therapeutic candidate for the regulation of allergic inflammation.

Critical Players and Therapeutic Targets in Chronic Itch

Chronic itch is one of the most prominent clinical characteristics of diverse systematic diseases. It is a devastating sensation in pathological diseases. Despite its importance, there are no FDA-labelled drugs specifically geared toward chronic itch. The associated complex pathogenesis and diverse causes escalate chronic itch to being one of the top challenges in healthcare. Humanized antibodies against IL-13, IL-4, and IL-31 proved effective in treatment of itch-associated atopic dermatitis but remain to be validated in chronic itch. There are still no satisfactory anti-itch therapeutics available toward itch-related neuropeptides including GRP, BNP, SST, CGRP, and SP. The newly identified potential itch targets including OSM, NMB, glutamate, periostin, and Serpin E1 have opened new avenues for therapeutic development. Proof-of-principle studies have been successfully performed on antagonists against these proteins and their receptors in itch treatment in animal models. Their translational interventions in humans need to be evaluated. It is of great importance to summarize and compare the newly emerging knowledge on chronic itch and its pathways to promote the development of novel anti-itch therapeutics. The goal of this review is to analyze the different physiologies and pathophysiologies of itch mediators, whilst assessing their suitability as new targets and discussing future therapeutic development.

A dysregulated sebum-microbial metabolite-IL-33 axis initiates skin inflammation in atopic dermatitis

Microbial dysbiosis in the skin has been implicated in the pathogenesis of atopic dermatitis (AD); however, whether and how changes in the skin microbiome initiate skin inflammation, or vice versa, remains poorly understood. Here, we report that the levels of sebum and its microbial metabolite, propionate, were lower on the skin surface of AD patients compared with those of healthy individuals. Topical propionate application attenuated skin inflammation in mice with MC903-induced AD-like dermatitis by inhibiting IL-33 production in keratinocytes, an effect that was mediated through inhibition of HDAC and regulation of the AhR signaling pathway. Mice lacking sebum spontaneously developed AD-like dermatitis, which was improved by topical propionate application. A proof-of-concept clinical study further demonstrated the beneficial therapeutic effects of topical propionate application in AD patients. In summary, we have uncovered that the dysregulated sebum-microbial metabolite-IL-33 axis might play an initiating role in AD-related skin inflammation, thereby highlighting novel therapeutic strategies for the treatment of AD.

Expression of Interleukin-33 Gene in Hemodialysis Patients with Chronic Toxoplasmosis in Baghdad, Iraq

Toxoplasmosis is a protozoan parasite with high distribution, leading to different abnormalities in hosts. The present study aimed to determine the distribution of toxoplasmosis in hemodialysis patients and the expression of the Interleukin (IL)-33 gene in chronic Toxoplasmosis. The present study evaluated 120 subjects, including 60 patients who were undergoing dialysis and 60 healthy samples as the control group, from the 1^st February to 1^st November 2021. Anti-Toxoplasma gondii IgG was detected by using the enzyme-linked immunosorbent assay (ELISA) technique and the real-time polymerase-chain-reaction (PCR) was used to perform IL-33. The results demonstrated that the highest anti-toxoplasmosis IgG antibody rate was observed in the age group 51-70 years who were undergoing dialysis, in comparison with that in the control group (P<0.05). The male patients who had anti-toxoplasmosis IgG antibodies outnumbered the healthy people (P<0.05), while the female patients did not significantly differ from the healthy group. Chronic toxoplasmosis showed a higher number according to residency (the urban and rural patients), compared to healthy people. The frequency of dialysis times per week in chronic Toxoplasmosis patients was significantly higher among the infected patients. The findings were displayed to be positive in dialysis at 2 weeks (P<0.05). The expression of the IL-33 gene was investigated in patients who were undergoing hemodialysis and in healthy controls by using real-time PCR. The findings demonstrated that there was a high Ct value for patients and controls with a high Ct value of templates, preoperational to the gene concentration. The high prevalence of toxoplasmosis in dialysis patients and the role of IL-33 in cellular immunity in these patients highlight the need to investigate the mechanisms limiting infection with intracellular protozoa.

Potential roles of non-lymphocytic cells in the pathogenesis of IgG4-related disease

Studies have confirmed the involvement of a variety of lymphocyte subsets, including type 2 helper T lymphocytes (Th2) and IgG4⁺ B lymphocytes, in the pathogenesis of IgG4-related disease (IgG4-RD). Those lymphocytes contribute to the major pathogenetic features of IgG4-RD. However, they are not the only cellular components in the immunoinflammatory environment of this mysterious disease entity. Recent studies have suggested that various non-lymphocytic components, including macrophages and fibroblasts, may also play an important role in the pathogenetic process of IgG4-RD in terms of contributing to the chronic and complex progress of the disease. Therefore, the potential role of non-lymphocyte in the pathogenesis of IgG4-RD is worth discussing.

IL-33 biology in cancer: An update and future perspectives

Interleukin-33 (IL-33) is a member of the IL-1 family of cytokines that is constitutively expressed in the nucleus of epithelial, endothelial and fibroblast-like cells. Upon cell stress, damage or necrosis, IL-33 is released into the cytoplasm to exert its prime role as an alarmin by binding to its specific receptor moiety, ST2. IL-33 exhibits pleiotropic function in inflammatory diseases and particularly in cancer. IL-33 may play a dual role as both a pro-tumorigenic and anti-tumorigenic cytokine, dependent on tumor and cellular context, expression levels, bioactivity and the nature of the inflammatory environment. In this review, we discuss the differential contribution of IL-33 to malignant or inflammatory conditions, its multifaceted effects on the tumor microenvironment, while providing possible explanations for the discrepant findings described in the literature. Additionally, we examine the emerging and divergent functions of IL-33 in the nucleus, and aspects of IL-33 biology that are currently under-addressed.

The contribution of mouse models to understanding atopic dermatitis

Atopic dermatitis (AD) is a dermatological disease accompanied by dry and cracked skin with severe pruritus. Although various therapeutic strategies have been introduced to alleviate AD, it remains challenging to cure the disorder. To achieve such a goal, understanding the pathophysiological mechanisms of AD is a prerequisite, requiring mouse models that properly reflect the AD phenotypes. Currently, numerous AD mouse models have been established, but each model has its own advantages and weaknesses. In this review, we categorized and summarized mouse models of AD and described their characteristics from a researcher's perspective.

Bacillus Calmette-Guérin-Induced Human Mast Cell Activation Relies on IL-33 Priming

Bacillus Calmette-Guérin (BCG) vaccine is an attenuated strain of Mycobacterium bovis that provides weak protection against tuberculosis (TB). Mast cells (MCs) are tissue-resident immune cells strategically that serve as the first line of defence against pathogenic threats. In this study, we investigated the response of human MCs (hMCs) to BCG. We found that naïve hMCs exposed to BCG did not secrete cytokines, degranulate, or support the uptake and intracellular growth of bacteria. Since we could show that in hMCs IL-33 promotes the transcription of host-pathogen interaction, cell adhesion and activation genes, we used IL-33 for cell priming. The treatment of hMCs with IL-33, but not IFN-γ, before BCG stimulation increased IL-8, MCP-1 and IL-13 secretion, and induced an enhanced expression of the mycobacteria-binding receptor CD48. These effects were comparable to those caused by the recombinant Mycobacterium tuberculosis (Mtb) 19-KDa lipoprotein. Finally, stimulation of hMCs with IL-33 incremented MC-BCG interactions. Thus, we propose that IL-33 may improve the immunogenicity of BCG vaccine by sensitising hMCs.

Association of the presence of allergic disease with subsequent risk of liver cancer in a nationwide retrospective cohort among Koreans

A number of studies have proposed an inverse association between allergic diseases and risk of cancer, but only a few studies have specifically investigated the risk of primary liver cancer, including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). The aim of this study was to evaluate the association of allergic diseases with risk of primary liver cancer. We conducted a retrospective cohort study of the Korean National Health Insurance Service database consisted of 405,512 Korean adults ages 40 and above who underwent health screening before January 1st, 2005. All participants were followed up until the date of liver cancer, death, or December 31st, 2013, whichever happened earliest. Those who died before the index date or had pre-diagnosed cancer were excluded from the analyses. Cox proportional hazards regression was used to determine the adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for risk of primary liver cancer according to the presence of allergic diseases, including atopic dermatitis, asthma, and allergic rhinitis. The aHR (95% CI) for overall liver cancer among allergic patients was 0.77 (0.68–0.87) compared to those without allergic disease. Allergic patients had significantly reduced risk of HCC (aHR, 0.72; 95% CI 0.62–0.85) but not ICC (aHR, 0.95; 95% CI 0.73–1.22). The presence of allergies was associated with significantly lower risk of liver cancer among patients whose systolic blood pressure is lower than 140 mmHg (aHR, 0.64; 95% CI 0.62–0.78 for overall liver cancer; aHR, 0.64; 95% CI 0.52–0.78 for HCC) but this effect was not observed among patients whose systolic blood pressure is higher than 140 mmHg (aHR, 0.91; 95% CI 0.71–1.18 for overall liver cancer; aHR, 0.91; 95% CI 0.71–1.18 for HCC) The aHR (95% CI) for overall liver cancer of allergic patients with and without chronic hepatitis virus infection were 0.60 (95% CI 0.44–0.81) and 0.77 (95% CI 0.64–0.93), respectively. In addition, allergic patients without cirrhosis showed significantly lower risk of overall liver cancer (aHR, 0.73; 95% CI 0.63–0.83). Patients with allergic diseases have significantly lower risk of primary liver cancer compared to those without allergic diseases, which supports the rationale for immunotherapy as an effective treatment for liver cancer.

The anti-inflammatory feature of glucagon-like peptide-1 and its based diabetes drugs—Therapeutic potential exploration in lung injury

Since 2005, GLP-1 receptor (GLP-1R) agonists (GLP-1RAs) have been developed as therapeutic agents for type 2 diabetes (T2D). GLP-1R is not only expressed in pancreatic islets but also other organs, especially the lung. However, controversy on extra-pancreatic GLP-1R expression still needs to be further resolved, utilizing different tools including the use of more reliable GLP-1R antibodies in immune-staining and co-immune-staining. Extra-pancreatic expression of GLP-1R has triggered extensive investigations on extra-pancreatic functions of GLP-1RAs, aiming to repurpose them into therapeutic agents for other disorders. Extensive studies have demonstrated promising anti-inflammatory features of GLP-1RAs. Whether those features are directly mediated by GLP-1R expressed in immune cells also remains controversial. Following a brief review on GLP-1 as an incretin hormone and the development of GLP-1RAs as therapeutic agents for T2D, we have summarized our current understanding of the anti-inflammatory features of GLP-1RAs and commented on the controversy on extra-pancreatic GLP-1R expression. The main part of this review is a literature discussion on GLP-1RA utilization in animal models with chronic airway diseases and acute lung injuries, including studies on the combined use of mesenchymal stem cell (MSC) based therapy. This is followed by a brief summary.

Novel Biological Therapies for Severe Asthma Endotypes

Severe asthma comprises several heterogeneous phenotypes, underpinned by complex pathomechanisms known as endotypes. The latter are driven by intercellular networks mediated by molecular components which can be targeted by specific monoclonal antibodies. With regard to the biological treatments of either allergic or non-allergic eosinophilic type 2 asthma, currently available antibodies are directed against immunoglobulins E (IgE), interleukin-5 (IL-5) and its receptor, the receptors of interleukins-4 (IL-4) and 13 (IL-13), as well as thymic stromal lymphopoietin (TSLP) and other alarmins. Among these therapeutic strategies, the best choice should be made according to the phenotypic/endotypic features of each patient with severe asthma, who can thus respond with significant clinical and functional improvements. Conversely, very poor options so far characterize the experimental pipelines referring to the perspective biological management of non-type 2 severe asthma, which thereby needs to be the focus of future thorough research.

Halogenation Activity of Mammalian Heme Peroxidases

Mammalian heme peroxidases are fascinating due to their unique peculiarity of oxidizing (pseudo)halides under physiologically relevant conditions. These proteins are able either to incorporate oxidized halides into substrates adjacent to the active site or to generate different oxidized (pseudo)halogenated species, which can take part in multiple (pseudo)halogenation and oxidation reactions with cell and tissue constituents. The present article reviews basic biochemical and redox mechanisms of (pseudo)halogenation activity as well as the physiological role of heme peroxidases. Thyroid peroxidase and peroxidasin are key enzymes for thyroid hormone synthesis and the formation of functional cross-links in collagen IV during basement membrane formation. Special attention is directed to the properties, enzymatic mechanisms, and resulting (pseudo)halogenated products of the immunologically relevant proteins such as myeloperoxidase, eosinophil peroxidase, and lactoperoxidase. The potential role of the (pseudo)halogenated products (hypochlorous acid, hypobromous acid, hypothiocyanite, and cyanate) of these three heme peroxidases is further discussed.

T Helper 2-Associated Immunity in the Pathogenesis of Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease that mainly affects women in their reproductive years. A complex interaction of environmental and genetic factors leads to the disruption of immune tolerance towards self, causing overt immune activation and production of autoantibodies that attack multiple organs. Kidney damage, termed lupus nephritis, is the leading cause of SLE-related morbidity and mortality. Autoantibodies are central to propagating lupus nephritis through forming immune complexes and triggering complements. Immunoglobulin G (IgG) potently activates complement; therefore, autoantibodies were mainly considered to be of the IgG isotype. However, studies revealed that over 50% of patients produce autoantibodies of the IgE isotype. IgE autoantibodies actively participate in disease pathogenesis as omalizumab treatment, a humanized anti-IgE monoclonal antibody, improved disease severity in an SLE clinical trial. IgE is a hallmark of T helper 2-associated immunity. Thus, T helper 2-associated immunity seems to play a pathogenic role in a subset of SLE patients. This review summarizes human and animal studies that illustrate type 2 immune responses involved during the pathology of SLE.

TLR Signals in Epithelial Cells in the Nasal Cavity and Paranasal Sinuses

The respiratory tract is constantly at risk of invasion by microorganisms such as bacteria, viruses, and fungi. In particular, the mucosal epithelium of the nasal cavity and paranasal sinuses is at the very forefront of the battles between the host and the invading pathogens. Recent studies have revealed that the epithelium not only constitutes a physical barrier but also takes an essential role in the activation of the immune system. One of the mechanisms equipped in the epithelium to fight against microorganisms is the Toll-like receptor (TLR) response. TLRs recognize common structural components of microorganisms and activate the innate immune system, resulting in the production of a plethora of cytokines and chemokines in the response against microbes. As the epithelia-derived cytokines are deeply involved in the pathogenesis of inflammatory conditions in the nasal cavity and paranasal sinuses, such as chronic rhinosinusitis (CRS) and allergic rhinitis (AR), the molecules involved in the TLR response may be utilized as therapeutic targets for these diseases. There are several differences in the TLR response between nasal and bronchial epithelial cells, and knowledge of the TLR signals in the upper airway is sparse compared to that in the lower airway. In this review, we provide recent evidence on TLR signaling in the upper airway, focusing on the expression, regulation, and responsiveness of TLRs in human nasal epithelial cells (HNECs). We also discuss how TLRs in the epithelium are involved in the pathogenesis of, and possible therapeutic targeting, for CRS and AR.

Emerging Roles of Platelets in Allergic Asthma

Allergic asthma is a complex chronic inflammatory disease of the airways, driven by Th2 immune responses and characterized by eosinophilic pulmonary inflammation, airway hyperresponsiveness, excessive mucus production, and airway remodeling. Overwhelming evidence from studies in animal models and allergic asthmatic patients suggests that platelets are aberrantly activated and recruited to the lungs. It has been established that platelets can interact with other immune cells and secrete various biochemical mediators to promote allergic sensitization and airway inflammatory response, and platelet deficiency may alleviate the pathological features and symptoms of allergic asthma. However, the comprehensive roles of platelets in allergic asthma have not been fully clarified, leaving attempts to treat allergic asthma with antiplatelet agents questionable. In this review, we summarize the role of platelet activation and pulmonary accumulation in allergic asthma; emphasis is placed on the different interactions between platelets with crucial immune cell types and the contribution of platelet-derived mediators in this context. Furthermore, clinical antiplatelet approaches to treat allergic asthma are discussed. This review provides a clearer understanding of the roles of platelets in the pathogenesis of allergic asthma and could be informative in the development of novel strategies for the treatment of allergic asthma.

The Interleukin-1 (IL-1) Superfamily Cytokines and Their Single Nucleotide Polymorphisms (SNPs)

Interleukins (ILs)—which are important members of cytokines—consist of a vast group of molecules, including a wide range of immune mediators that contribute to the immunological responses of many cells and tissues. ILs are immune-glycoproteins, which directly contribute to the growth, activation, adhesion, differentiation, migration, proliferation, and maturation of immune cells; and subsequently, they are involved in the pro and anti-inflammatory responses of the body, by their interaction with a wide range of receptors. Due to the importance of immune system in different organisms, the genes belonging to immune elements, such as ILs, have been studied vigorously. The results of recent investigations showed that the genes pertaining to the immune system undergo progressive evolution with a constant rate. The occurrence of any mutation or polymorphism in IL genes may result in substantial changes in their biology and function and may be associated with a wide range of diseases and disorders. Among these abnormalities, single nucleotide polymorphisms (SNPs) can represent as important disruptive factors. The present review aims at concisely summarizing the current knowledge available on the occurrence, properties, role, and biological consequences of SNPs within the IL-1 family members.

IL-33 regulates M1/M2 chemokine expression via mitochondrial redox-related mitophagy in human monocytes

Interleukin (IL)-33 is an epithelial-derived cytokine that enhances T helper (Th) 2 responses. Allergens and other agents induce IL-33 in asthma. Excessive production of reactive oxygen species (ROS) leads to airway inflammation. Mitophagy is the selective degradation of mitochondria by autophagy and often occurs in defective mitochondria, followed by ROS production. In the present study, we examined the effects of IL-33 on ROS production and mitophagy in human monocytes, and the detailed mechanisms were investigated. Human monocyte cell line THP-1 was pretreated with different concentrations of IL-33. ROS production was measured by flow cytometry. Mitochondrial involvement and the mitophagy and intercellular pathway activation were evaluated by quantitative real-time PCR, western blotting, and confocal microscopy, and cytokine/chemokine concentrations were detected by ELISA. The data showed that IL-33 alone could induce ROS expression in THP-1 cells. The expression of complex II and V mRNA was increased in the presence of IL-33. The mitophagy-related proteins PINK1, Parkin, and LC3 were regulated by IL-33 through the AMPK pathway. IL-33 significantly decreased M1-related cytokines CXCL-10 and TNF-α production and significantly increased M2-related cytokine CCL-22 production. In conclusion, IL-33 induces ROS production and subsequently influences mitophagy through AMPK activation, altering the macrophage-polarization phenotype of monocytes.