Phenotypic and functional translation of IL1RL1 locus polymorphisms in lung tissue and asthmatic airway epithelium

Epigenomic and proteomic analyses provide insights into early-life immune regulation and asthma development in infants

Infants with severe bronchiolitis (i.e., bronchiolitis requiring hospitalization) face increased risks of respiratory diseases in childhood. We conduct epigenome-wide association studies in a multi-ethnic cohort of these infants. We identify 61 differentially methylated regions in infant blood (<1 year of age) associated with recurrent wheezing by age 3 (170 cases, 318 non-cases) and/or asthma by age 6 (112 cases, 394 non-cases). These differentially methylated regions are enriched in the enhancers of peripheral blood neutrophils. Several differentially methylated regions exhibit interaction with rhinovirus infection and/or specific blood cell types. In the same blood samples, circulating levels of 104 proteins correlate with the differentially methylated regions, and many proteins show phenotypic association with asthma. Through Mendelian randomization, we find causal evidence supporting a protective role of higher plasma ST2 (also known as IL1RL1) protein against asthma. DNA methylation is also associated with ST2 protein level in infant blood. Taken together, our findings suggest the contribution of DNA methylation to asthma development through regulating early-life systemic immune responses.

Targeting alarmins in asthma: From bench to clinic

Over the past 2 decades, mechanistic studies of allergic and type 2 (T2)-mediated airway inflammation have led to multiple approved therapies for the treatment of moderate-to-severe asthma. The approval and availability of these monoclonal antibodies targeting IgE, a T2 cytokine (IL-5) and/or cytokine receptors (IL-5Rα, IL-4Rα) has been central to the progresses made in the management of moderate-to-severe asthma over this period. However, there are persistent gaps in clinician's ability to provide precise care, given that many patients with T2-high asthma do not respond to IgE- or T2 cytokine-targeting therapies and that patients with T2-low asthma have few therapeutic options. The new frontier of precision medicine in asthma, as well as in other allergic diseases, includes the targeting of epithelium-derived cytokines known as alarmins, including thymic stromal lymphopoietin, IL-25, IL-33, and their receptors. The effects of these alarmins, which can act upstream of immune cells, involve both the innate and adaptive systems and hold potential for the treatment of both T2-high and -low disease. Tezepelumab, an anti-thymic stromal lymphopoietin antibody, has already been approved for the treatment of severe asthma. In this review, we discuss our current understanding of alarmin biology with a primary focus on allergic airway diseases. We link the mechanistic corollaries to the clinical implications and advances in drug development targeting alarmins, with a particular focus on currently approved treatments, those under study, and future potential targets in alarmin signaling pathways.

DNA-binding factor footprints and enhancer RNAs identify functional non-coding genetic variants

BACKGROUND

Genome-wide association studies (GWAS) have revealed a multitude of candidate genetic variants affecting the risk of developing complex traits and diseases. However, the highlighted regions are typically in the non-coding genome, and uncovering the functional causative single nucleotide variants (SNVs) is challenging. Prioritization of variants is commonly based on genomic annotation with markers of active regulatory elements, but current approaches still poorly predict functional variants. To address this, we systematically analyze six markers of active regulatory elements for their ability to identify functional variants.

RESULTS

We benchmark against molecular quantitative trait loci (molQTL) from assays of regulatory element activity that identify allelic effects on DNA-binding factor occupancy, reporter assay expression, and chromatin accessibility. We identify the combination of DNase footprints and divergent enhancer RNA (eRNA) as markers for functional variants. This signature provides high precision, but with a trade-off of low recall, thus substantially reducing candidate variant sets to prioritize variants for functional validation. We present this as a framework called FINDER-Functional SNV IdeNtification using DNase footprints and eRNA.

CONCLUSIONS

We demonstrate the utility to prioritize variants using leukocyte count trait and analyze variants in linkage disequilibrium with a lead variant to predict a functional variant in asthma. Our findings have implications for prioritizing variants from GWAS, in development of predictive scoring algorithms, and for functionally informed fine mapping approaches.

Interleukin-33/serum stimulation-2 pathway: Regulatory mechanisms and emerging implications in immune and inflammatory diseases

Interleukin (IL)- 33, a nuclear factor and pleiotropic cytokine of the IL-1 family, is gaining attention owing to its important role in chronic inflammatory and autoimmune diseases. This review extends our knowledge of the effects exerted by IL-33 on target cells by binding to its specific receptor serum stimulation-2 (ST2). Depending on the tissue context, IL-33 performs multiple functions encompassing host defence, immune response, initiation and amplification of inflammation, tissue repair, and homeostasis. The levels and activity of IL-33 in the body are controlled by complex IL-33-targeting regulatory pathways. The unique temporal and spatial expression patterns of IL-33 are associated with host homeostasis and the development of immune and inflammatory disorders. Therefore, understanding the origin, function, and processes of IL-33 under various conditions is crucial. This review summarises the regulatory mechanisms underlying the IL-33/ST2 signalling axis and its potential role and clinical significance in immune and inflammatory diseases, and discusses the current complex and conflicting findings related to IL-33 in host responses.

Role of IL-33-ST2 pathway in regulating inflammation: current evidence and future perspectives

Interleukin (IL)-33 is an alarmin of the IL-1 superfamily localized to the nucleus of expressing cells, such as endothelial cells, epithelial cells, and fibroblasts. In response to cellular damage or stress, IL-33 is released and activates innate immune responses in some immune and structural cells via its receptor interleukin-1 receptor like-1 (IL-1RL1 or ST2). Recently, IL-33 has become a hot topic of research because of its role in pulmonary inflammation. The IL-33-ST2 signaling pathway plays a pro-inflammatory role by activating the type 2 inflammatory response, producing type 2 cytokines and chemokines. Elevated levels of IL-33 and ST2 have been observed in chronic pulmonary obstructive disease (COPD). Notably, IL-33 is present in COPD induced by cigarette smoke or acute inflammations. The role of IL-33 in sepsis is becoming increasingly prominent, and understanding its significance in the treatment of sepsis associated with high mortality is critical. In addition to its pro-inflammatory effects, the IL-33-ST2 axis appears to play a role in bacterial clearance and tissue repair. In this review, we focused on the role of the IL-33-ST2 axis in sepsis, asthma, and COPD and summarized the therapeutic targets associated with this axis, providing a basis for future treatment.

Decoding the genetic and epigenetic basis of asthma

Asthma is a complex and heterogeneous chronic inflammatory disease of the airways. Alongside environmental factors, asthma susceptibility is strongly influenced by genetics. Given its high prevalence and our incomplete understanding of the mechanisms underlying disease susceptibility, asthma is frequently studied in genome-wide association studies (GWAS), which have identified thousands of genetic variants associated with asthma development. Virtually all these genetic variants reside in non-coding genomic regions, which has obscured the functional impact of asthma-associated variants and their translation into disease-relevant mechanisms. Recent advances in genomics technology and epigenetics now offer methods to link genetic variants to gene regulatory elements embedded within non-coding regions, which have started to unravel the molecular mechanisms underlying the complex (epi)genetics of asthma. Here, we provide an integrated overview of (epi)genetic variants associated with asthma, focusing on efforts to link these disease associations to biological insight into asthma pathophysiology using state-of-the-art genomics methodology. Finally, we provide a perspective as to how decoding the genetic and epigenetic basis of asthma has the potential to transform clinical management of asthma and to predict the risk of asthma development.

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.

The understanding of asthma pathogenesis in the era of precision medicine

Asthma is a syndrome with extremely diverse clinical phenotypes in which the onset, severity, and response to treatment are defined by the complex interplay of many genetic and environmental factors. Environmental factors epigenetically affect gene expression, and the disease is driven by a multidimensional dynamic network involving RNA and protein molecules derived from gene expression, as well as various metabolic products. In other words, specific pathophysiological mechanisms or endotypes are dynamic networks that arise in response to individual genotypes and the various environmental factors to which individuals have been exposed since before birth, such as diet, infection, air pollution, smoking, antibiotic use, and the bacterial flora of the intestinal tract, skin, and lungs. A key feature of asthma genome scans is their potential to reveal the molecular pathways that lead to pathogenesis. Endotypes that drive the disease have a significant impact on the phenotypes of asthma patients, including their drug responsiveness. Understanding endotypes will lead to not only the implementation of therapies that are tailored to the specific molecular network(s) underlying the patient's condition, but also to the development of therapeutic strategies that target individual endotypes, as well as to precision health, which will enable the prediction of disease onset with high accuracy from an early stage and the implementation of preventive strategies based on endotypes. Understanding of endotypes will pave the way for the practice of precision medicine in asthma care, moving away from 'one-size-fits-all' medicine and population-based prevention approaches that do not take individuals' susceptibility into account.

Determining asthma endotypes and outcomes: Complementing existing clinical practice with modern machine learning

There is unprecedented opportunity to use machine learning to integrate high-dimensional molecular data with clinical characteristics to accurately diagnose and manage disease. Asthma is a complex and heterogeneous disease and cannot be solely explained by an aberrant type 2 (T2) immune response. Available and emerging multi-omics datasets of asthma show dysregulation of different biological pathways including those linked to T2 mechanisms. While T2-directed biologics have been life changing for many patients, they have not proven effective for many others despite similar biomarker profiles. Thus, there is a great need to close this gap to understand asthma heterogeneity, which can be achieved by harnessing and integrating the rich multi-omics asthma datasets and the corresponding clinical data. This article presents a compendium of machine learning approaches that can be utilized to bridge the gap between predictive biomarkers and actual causal signatures that are validated in clinical trials to ultimately establish true asthma endotypes.

Exome variants associated with asthma and allergy

The mutational spectrum of asthma and allergy associated genes is not known although recent biobank based exome sequencing studies included these traits. We therefore conducted a secondary analysis of exome data from 281,104 UK Biobank samples for association of mostly rare variants with asthma, allergic rhinitis and atopic dermatitis. Variants of interest (VOI) were tabulated, shared genes annotated and compared to earlier genome-wide SNP association studies (GWAS), whole genome sequencing, exome and bisulfit sequencing studies. 354 VOI were significantly associated with asthma, allergic rhinitis and atopic dermatitis. They cluster mainly in two large regions on chromosome 6 and 17. After exclusion of the variants associated with atopic dermatitis and redundant variants, 321 unique VOI remain in 122 unique genes. 30 genes are shared among the 87 genes with increased and the 65 genes with decreased risk for allergic disease. 85% of genes identified earlier by common GWAS SNPs are not replicated here. Most identified genes are located in interferon ɣ and IL33 signaling pathway. These genes include already known but also new pharmacological targets, including the IL33 receptor ST2/IL1RL1, as well as TLR1, ALOX15, GSDMA, BTNL2, IL13 and IKZF3. Future pharmacological studies will need to included these VOI for stratification of the study population paving the way to individualized treatment.

Louki Zupa decoction attenuates the airway inflammation in acute asthma mice induced by ovalbumin through IL-33/ST2-NF-κB/GSK3β/mTOR signalling pathway

CONTEXT

Asthma is a common respiratory system disease. Louki Zupa decoction (LKZP), a traditional Chinese medicine, presents a promising efficacy against lung diseases.

OBJECTIVE

To investigate the pathogenic mechanism of asthma and reveal the intervention mechanism of LKZP.

MATERIALS AND METHODS

Forty-eight female Balb/c mice were randomly divided into 6 groups: normal control group (NC), ovalbumin (OVA)/saline asthma model group, OVA/LL group, OVA/LM group, OVA/LH group and OVA/DEX group (n = 8 per group). The asthmatic mice were modelled through intraperitoneal injecting and neutralizing OVA. LKZP decoction was administrated by gavage at the challenge stage for seven consecutive days (2.1, 4.2 and 8.4 g/kg/day). We investigated the change in lung function, airway inflammation, mucus secretion and TH-1/TH-2-related cytokines. We further verify the activated status of the IL-33/ST2/NF-κB/GSK3β/mTOR signalling pathway.

RESULTS

LKZP was proved to improve asthmatic symptoms, as evidenced by the down-regulated airway resistance by 36%, 58% and 53% (p < 0.01, p < 0.001 vs. OVA/saline group), up-regulated lung compliance by 102%, 114% and 111%, decreased airway inflammation and mucus secretion by 33%, 40% and 33% (p < 0.001 vs. OVA/saline group). Moreover, the content of cytokines in BALF related to airway allergy (such as IgE) and T helper 1/T helper 2 cells (like IL-2, IL-4, IL-5, IL-13, TNF-α and IFN-γ), were also markedly reduced by 13-65% on LKZP intervention groups compared with model group. Mechanistic research revealed that the IL-33/ST2-NF-κB/GSK3β/mTOR signalling pathway was activated in the OVA/saline group and LKZP significantly down-regulated this pathway.

DISCUSSION AND CONCLUSION

LKZP improves lung function, airway inflammation, mucus secretion and correct immune imbalance by intervening with the IL-33/ST2-NF-κB/GSK3β/mTOR signalling pathway, presenting a promising therapeutic choice for asthma.

IL-33 Induces an Antiviral Signature in Mast Cells but Enhances Their Permissiveness for Human Rhinovirus Infection

Mast cells (MCs) are classically associated with allergic asthma but their role in antiviral immunity is unclear. Human rhinoviruses (HRVs) are a major cause of asthma exacerbations and can infect and replicate within MCs. The primary site of HRV infection is the airway epithelium and MCs localise to this site with increasing asthma severity. The asthma susceptibility gene, IL-33, encodes an epithelial-derived cytokine released following HRV infection but its impact on MC antiviral responses has yet to be determined. In this study we investigated the global response of LAD2 MCs to IL-33 stimulation using RNA sequencing and identified genes involved in antiviral immunity. In spite of this, IL-33 treatment increased permissiveness of MCs to HRV16 infection which, from the RNA-Seq data, we attributed to upregulation of ICAM1. Flow cytometric analysis confirmed an IL-33-dependent increase in ICAM1 surface expression as well as LDLR, the receptors used by major and minor group HRVs for cellular entry. Neutralisation of ICAM1 reduced the IL-33-dependent enhancement in HRV16 replication and release in both LAD2 MCs and cord blood derived MCs. These findings demonstrate that although IL-33 induces an antiviral signature in MCs, it also upregulates the receptors for HRV entry to enhance infection. This highlights the potential for a gene-environment interaction involving IL33 and HRV in MCs to contribute to virus-induced asthma exacerbations.

Dual Immune Regulatory Roles of Interleukin-33 in Pathological Conditions

Interleukin-33 (IL-33), a member of the IL-1 cytokine family and a multifunctional cytokine, plays critical roles in maintaining host homeostasis and in pathological conditions, such as allergy, infectious diseases, and cancer, by acting on multiple types of immune cells and promoting type 1 and 2 immune responses. IL-33 is rapidly released by immune and non-immune cells upon stimulation by stress, acting as an “alarmin” by binding to its receptor, suppression of tumorigenicity 2 (ST2), to trigger downstream signaling pathways and activate inflammatory and immune responses. It has been recognized that IL-33 displays dual-functioning immune regulatory effects in many diseases and has both pro- and anti-tumorigenic effects, likely depending on its primary target cells, IL-33/sST2 expression levels, cellular context, and the cytokine microenvironment. Herein, we summarize our current understanding of the biological functions of IL-33 and its roles in the pathogenesis of various conditions, including inflammatory and autoimmune diseases, infections, cancers, and cases of organ transplantation. We emphasize the nature of context-dependent dual immune regulatory functions of IL-33 in many cells and diseases and review systemic studies to understand the distinct roles of IL-33 in different cells, which is essential to the development of more effective diagnoses and therapeutic approaches for IL-33-related diseases.

Best practices for multi-ancestry, meta-analytic transcriptome-wide association studies: Lessons from the Global Biobank Meta-analysis Initiative

The Global Biobank Meta-analysis Initiative (GBMI), through its diversity, provides a valuable opportunity to study population-wide and ancestry-specific genetic associations. However, with multiple ascertainment strategies and multi-ancestry study populations across biobanks, GBMI presents unique challenges in implementing statistical genetics methods. Transcriptome-wide association studies (TWASs) boost detection power for and provide biological context to genetic associations by integrating genetic variant-to-trait associations from genome-wide association studies (GWASs) with predictive models of gene expression. TWASs present unique challenges beyond GWASs, especially in a multi-biobank, meta-analytic setting. Here, we present the GBMI TWAS pipeline, outlining practical considerations for ancestry and tissue specificity, meta-analytic strategies, and open challenges at every step of the framework. We advise conducting ancestry-stratified TWASs using ancestry-specific expression models and meta-analyzing results using inverse-variance weighting, showing the least test statistic inflation. Our work provides a foundation for adding transcriptomic context to biobank-linked GWASs, allowing for ancestry-aware discovery to accelerate genomic medicine.

Genetic Determinants in Airways Obstructive Diseases: The Case of Asthma Chronic Obstructive Pulmonary Disease Overlap

Genome-wide association studies (GWAS) of asthma and chronic obstructive pulmonary disease (COPD) with ever-increasing sample sizes have found multiple genetic loci associated with either disease. However, there are few intersecting loci between asthma and COPD. GWAS specifically focused on asthma-COPD overlap (ACO) have been limited by smaller sample sizes and the lack of a consistent definition of ACO that has also hampered clinical and epidemiologic studies. Other genomic techniques, such as gene expression profiling, are feasible with smaller sample sizes. Genetic analyses of objective measures of airway reactivity and allergy/T2 inflammation biomarkers in COPD studies may be another strategy to overcome limitations in ACO definitions.

Translational Analysis of Moderate to Severe Asthma GWAS Signals Into Candidate Causal Genes and Their Functional, Tissue-Dependent and Disease-Related Associations

Asthma affects more than 300 million people globally and is both under diagnosed and under treated. The most recent and largest genome-wide association study investigating moderate to severe asthma to date was carried out in 2019 and identified 25 independent signals. However, as new and in-depth downstream databases become available, the translational analysis of these signals into target genes and pathways is timely. In this study, unique (U-BIOPRED) and publicly available datasets (HaploReg, Open Target Genetics and GTEx) were investigated for the 25 GWAS signals to identify 37 candidate causal genes. Additional traits associated with these signals were identified through PheWAS using the UK Biobank resource, with asthma and eosinophilic traits amongst the strongest associated. Gene expression omnibus dataset examination identified 13 candidate genes with altered expression profiles in the airways and blood of asthmatic subjects, including MUC5AC and STAT6. Gene expression analysis through publicly available datasets highlighted lung tissue cell specific expression, with both MUC5AC and SLC22A4 genes showing enriched expression in ciliated cells. Gene enrichment pathway and interaction analysis highlighted the dominance of the HLA-DQA1/A2/B1/B2 gene cluster across many immunological diseases including asthma, type I diabetes, and rheumatoid arthritis. Interaction and prediction analyses found IL33 and IL18R1 to be key co-localization partners for other genes, predicted that CD274 forms co-expression relationships with 13 other genes, including the HLA-DQA1/A2/B1/B2 gene cluster and that MUC5AC and IL37 are co-expressed. Drug interaction analysis revealed that 11 of the candidate genes have an interaction with available therapeutics. This study provides significant insight into these GWAS signals in the context of cell expression, function, and disease relationship with the view of informing future research and drug development efforts for moderate-severe asthma.

Interleukin 1 receptor-like 1 rs13408661/13431828 polymorphism is associated with persistent post-bronchiolitis asthma at school age

Aim

Interleukin (IL) 1 receptor‐like 1, encoded by the IL1RL1 gene, is a receptor for IL‐33. In European birth cohorts, IL1RL1 rs102082293, rs10204137 (rs4988955), rs13424006 and rs13431828 (rs13048661) variations were associated with asthma at school age. In a Dutch multi‐centre study, IL1RL1 rs1921622 variation was associated with severe bronchiolitis. We evaluated the associations of these five IL1RL1 variations with asthma and lung function at school age after hospitalisation for bronchiolitis in infancy.

Methods

Follow‐up data, including impulse oscillometry at age 5–7 and flow‐volume spirometry at age 11–13 years, and the IL1RL1 genotype data were available for 141 children followed until 5–7 and for 125 children followed until 11–13 age years after bronchiolitis in infancy. The IL1RL1 rs10204137 and rs4988955, and the IL1RL1 rs13048661 and rs13431828, are 100% co‐segregating in the Finnish population.

Results

The variant IL1RL1 rs13048661/13431828 genotype was constantly associated with increased asthma risk by various definitions at 5–7 and 11–13 years of ages. The result was confirmed with analyses adjusted for current confounders and early‐life environment‐related factors. Statistical significances were lost, when maternal asthma and atopic dermatitis in infancy were included in the model.

Conclusion

IL1RL1 rs13048661/13431828 variation was associated with post‐bronchiolitis asthma outcomes at school age.

IL-33, an Alarmin of the IL-1 Family Involved in Allergic and Non Allergic Inflammation: Focus on the Mechanisms of Regulation of Its Activity

Interleukin-33 (IL-33) is a member of the interleukin-1 (IL-1) family that is expressed in the nuclei of endothelial and epithelial cells of barrier tissues, among others. It functions as an alarm signal that is released upon tissue or cellular injury. IL-33 plays a central role in the initiation and amplification of type 2 innate immune responses and allergic inflammation by activating various target cells expressing its ST2 receptor, including mast cells and type 2 innate lymphoid cells. Depending on the tissue environment, IL-33 plays a wide variety of roles in parasitic and viral host defense, tissue repair and homeostasis. IL-33 has evolved a variety of sophisticated regulatory mechanisms to control its activity, including nuclear sequestration and proteolytic processing. It is involved in many diseases, including allergic, inflammatory and infectious diseases, and is a promising therapeutic target for the treatment of severe asthma. In this review, I will summarize the literature around this fascinating pleiotropic cytokine. In the first part, I will describe the basics of IL-33, from the discovery of interleukin-33 to its function, including its expression, release and signaling pathway. The second part will be devoted to the regulation of IL-33 protein leading to its activation or inactivation.

Neutrophils Affect IL-33 Processing in Response to the Respiratory Allergen Alternaria alternata

Future precision medicine requires further clarifying the mechanisms of inflammation in the severe endotypes of chronic airway diseases such as asthma and chronic rhinosinusitis (CRS). The presence of neutrophils in the airways is often associated with severe airway inflammation, while their precise contribution to the severe inflammation is largely unknown. We aimed to study the role of neutrophils in BALB/c and C57BL/6 mice exposed to Alternaria alternata (Alt). The mice were exposed to Alt extract for twelve hours or ten days to induce allergic airway inflammation. C57BL/6 mice exposed to Alt responded with eosinophilic infiltration and the characteristic IL-5 upregulation. In contrast, the inflammatory response to Alt extract in BALB/c mice was characterized by a neutrophilic response, high levels of G-CSF, and elastase in the lungs. The lack of neutrophils affected the processing of IL-33 in BALB/c mice, as was demonstrated by depletion of neutrophils through intraperitoneal injections of anti-Ly6G antibody. Our data identifies the key role of neutrophils in airway inflammation through IL-33 cleavage in the Alt-induced airway inflammation in mice, which could potentially underline the different endotypes in human disease.

Generation and Characterization of Torudokimab (LY3375880): A Monoclonal Antibody That Neutralizes Interleukin-33

Background

Interleukin-33 (IL-33) is an alarmin that is released following cellular damage, mechanical injury, or necrosis. It is a member of the IL-1 family and binds to a heterodimer receptor consisting of ST2 and IL-1RAP to induce the production of a wide range of cellular mediators, including the type 2 cytokines IL-4, IL-5 and IL-13. This relationship has led to the hypothesis that the IL-33/ST2 pathway is a driver of allergic disease and inhibition of the IL-33 and ST2 association could have therapeutic benefit.

Methods

In this paper, we describe the selection of a phage antibody through the ability to bind human IL-33 and block IL-33/ST2 interaction. This hit antibody was then affinity matured by site-directed mutagenesis of the antibody complementarity-determining regions (CDRs). Further characterization of a fully human monoclonal antibody (mAb), torudokimab (LY3375880) included demonstration of human IL-33 neutralization activity in vitro with an NFκB reporter assay and IL-33 induced mast cell cytokine secretion assay, followed by an in vivo IL-33-induced pharmacodynamic inhibition assay in mice that used IL-5 production as the endpoint.

Results

Torudokimab is highly specific to IL-33 and does not bind any of the other IL-1 family members. Furthermore, torudokimab binds human and cynomolgus monkey IL-33 with higher affinity than the binding affinity of IL-33 to ST2, but does not bind mouse, rat, or rabbit IL-33. Torudokimab’s half-life in cynomolgous monkey projects monthly dosing in the clinic.

Conclusion

Due to torudokimab’s high affinity, its ability to completely neutralize IL-33 activity in vitro and in vivo, and the observed cynomolgus monkey pharmacokinetic properties, this molecule was selected for clinical development.

Role of Interleukin-1 Receptor-Like 1 (ST2) in Cerebrovascular Disease

Following both ischemic and hemorrhagic stroke, innate immune cells initiate a proinflammatory response that further exacerbate tissue injury in the acute phase, but these cells also play an important reparative role thereafter. Numerous cytokines and signaling pathways have been implicated in driving the deleterious proinflammatory response, but less is known about the mediators that connect the initial vascular injury to the systemic immune response and the relationship between proinflammatory and reparative immune responses. The Interleukin-33 (IL-33) and serum stimulation-2 (ST2) axis is an interleukin signaling pathway that is a prime candidate to fulfill this role. In this review, we describe the biology of the IL-33/ST2 system, present evidence that its soluble decoy receptor, soluble ST2 (sST2), plays a key role in secondary neurologic injury after stroke, and discuss this in the context of the known role of IL-33/ST2 in other disease.

Genetically determined NLRP3 inflammasome activation associates with systemic inflammation and cardiovascular mortality

AIMS

Inflammation plays an important role in cardiovascular disease (CVD) development. The NOD-like receptor protein-3 (NLRP3) inflammasome contributes to the development of atherosclerosis in animal models. Components of the NLRP3 inflammasome pathway such as interleukin-1β can therapeutically be targeted. Associations of genetically determined inflammasome-mediated systemic inflammation with CVD and mortality in humans are unknown.

METHODS AND RESULTS

We explored the association of genetic NLRP3 variants with prevalent CVD and cardiovascular mortality in 538 167 subjects on the individual participant level in an explorative gene-centric approach without performing multiple testing. Functional relevance of single-nucleotide polymorphisms on NLRP3 inflammasome activation has been evaluated in monocyte-enriched peripheral blood mononuclear cells (PBMCs). Genetic analyses identified the highly prevalent (minor allele frequency 39.9%) intronic NLRP3 variant rs10754555 to affect NLRP3 gene expression. rs10754555 carriers showed significantly higher C-reactive protein and serum amyloid A plasma levels. Carriers of the G allele showed higher NLRP3 inflammasome activation in isolated human PBMCs. In carriers of the rs10754555 variant, the prevalence of coronary artery disease was significantly higher as compared to non-carriers with a significant interaction between rs10754555 and age. Importantly, rs10754555 carriers had significantly higher risk for cardiovascular mortality during follow-up. Inflammasome inducers (e.g. urate, triglycerides, apolipoprotein C3) modulated the association between rs10754555 and mortality.

CONCLUSION

The NLRP3 intronic variant rs10754555 is associated with increased systemic inflammation, inflammasome activation, prevalent coronary artery disease, and mortality. This study provides evidence for a substantial role of genetically driven systemic inflammation in CVD and highlights the NLRP3 inflammasome as a therapeutic target.

The transcription factors GFI1 and GFI1B as modulators of the innate and acquired immune response

GFI1 and GFI1B are small nuclear proteins of 45 and 37kDa, respectively, that have a simple two-domain structure: The first consists of a group of six c-terminal C₂H₂ zinc finger motifs that are almost identical in sequence and bind to very similar, specific DNA sites. The second is an N-terminal 20 amino acid SNAG domain that can bind to the pocket of the histone demethylase KDM1A (LSD1) near its active site. When bound to DNA, both proteins act as bridging factors that bring LSD1 and associated proteins into the vicinity of methylated substrates, in particular histone H3 or TP53. GFI1 can also bring methyl transferases such as PRMT1 together with its substrates that include the DNA repair proteins MRE11 and 53BP1, thereby enabling their methylation and activation. While GFI1B is expressed almost exclusively in the erythroid and megakaryocytic lineage, GFI1 has clear biological roles in the development and differentiation of lymphoid and myeloid immune cells. GFI1 is required for lymphoid/myeloid and monocyte/granulocyte lineage decision as well as the correct nuclear interpretation of a number of important immune-signaling pathways that are initiated by NOTCH1, interleukins such as IL2, IL4, IL5 or IL7, by the pre TCR or -BCR receptors during early lymphoid differentiation or by T and B cell receptors during activation of lymphoid cells. Myeloid cells also depend on GFI1 at both stages of early differentiation as well as later stages in the process of activation of macrophages through Toll-like receptors in response to pathogen-associated molecular patterns. The knowledge gathered on these factors over the last decades puts GFI1 and GFI1B at the center of many biological processes that are critical for both the innate and acquired immune system.

The central role of IL-33/IL-1RL1 pathway in asthma: From pathogenesis to intervention

Interleukin-33 (IL-33), a member of the IL-1 family, and its cognate receptor, Interleukin-1 receptor like-1 (IL-1RL1 or ST2), are susceptibility genes for childhood asthma. In response to cellular damage, IL-33 is released from barrier tissues as an 'alarmin' to activate the innate immune response. IL-33 drives type 2 responses by inducing signalling through its receptor IL-1RL1 in several immune and structural cells, thereby leading to type 2 cytokine and chemokine production. IL-1RL1 gene transcript encodes different isoforms generated through alternative splicing. Its soluble isoform, IL-1RL1-a or sST2, acts as a decoy receptor by sequestering IL-33, thereby inhibiting IL1RL1-b/IL-33 signalling. IL-33 and its receptor IL-1RL1 are therefore considered as putative biomarkers or targets for pharmacological intervention in asthma. This review will provide an overview of the genetics and biology of the IL-33/IL-1RL1 pathway in the context of asthma pathogenesis. It will discuss the potential and complexities of targeting the cytokine or its receptor, how genetics or biomarkers may inform precision medicine for asthma targeting this pathway, and the possible positioning of therapeutics targeting IL-33 or its receptor in the expanding landscape of novel biologicals applied in asthma management.