A randomized, double-blind, placebo-controlled study of tumor necrosis factor-alpha blockade in severe persistent asthma

Asthma Pathogenesis: Phenotypes, Therapies, and Gaps: Summary of the Aspen Lung Conference 2023

Although substantial progress has been made in our understanding of asthma pathogenesis and phenotypes over the nearly 60-year history of the Aspen Lung Conferences on asthma, many ongoing challenges exist in our understanding of the clinical and molecular heterogeneity of the disease and an individual patient's response to therapy. This report summarizes the proceedings of the 2023 Aspen Lung Conference, which was organized to review the clinical and molecular heterogeneity of asthma and to better understand the impact of genetic, environmental, cellular, and molecular influences on disease susceptibility, heterogeneity, and severity. The goals of the conference were to review new information about asthma phenotypes, cellular processes, and cellular signatures underlying disease heterogeneity and treatment response. The report concludes with ongoing gaps in our understanding of asthma pathobiology and provides some recommendations for future research to better understand the clinical and basic mechanisms underlying disease heterogeneity in asthma and to advance the development of new treatments for this growing public health problem.

Association of Obesity and Severe Asthma in Adults

The incidence of obesity and asthma continues to enhance, significantly impacting global public health. Adipose tissue is an organ that secretes hormones and cytokines, causes meta-inflammation, and contributes to the intensification of bronchial hyperreactivity, oxidative stress, and consequently affects the different phenotypes of asthma in obese people. As body weight increases, the risk of severe asthma increases, as well as more frequent exacerbations requiring the use of glucocorticoids and hospitalization, which consequently leads to a deterioration of the quality of life. This review discusses the relationship between obesity and severe asthma, the underlying molecular mechanisms, changes in respiratory function tests in obese people, its impact on the occurrence of comorbidities, and consequently, a different response to conventional asthma treatment. The article also reviews research on possible future therapies for severe asthma. The manuscript is a narrative review of clinical trials in severe asthma and comorbid obesity. The articles were found in the PubMed database using the keywords asthma and obesity. Studies on severe asthma were then selected for inclusion in the article. The sections: 'The classification connected with asthma and obesity', 'Obesity-related changes in pulmonary functional tests', and 'Obesity and inflammation', include studies on subjects without asthma or non-severe asthma, which, according to the authors, familiarize the reader with the pathophysiology of obesity-related asthma.

New targets for type 2-low asthma

Asthma is characterized by airway obstruction and inflammation, and presents significant diagnostic and treatment challenges. The concept of endotypes has improved understanding of the mechanisms of asthma and has stimulated the development of effective treatment strategies. Sputum profiles may be used to classify asthma into two major inflammatory types: type 2-high (T2H) and type 2-low (T2L) asthma. T2H, characterized by elevated type 2 inflammation, has been extensively studied and several effective biologic treatments have been developed. However, managing T2L is more difficult due to the lack of reliable biomarkers for accurate diagnosis and classification. Additionally, conventional anti-inflammatory therapy does not completely control the symptoms of T2L; therefore, further research is needed to identify effective biologic treatments. This review provides new insights into the clinical characteristics and underlying mechanisms of severe T2L and investigates potential therapeutic approaches to control the disease.

ST2-Mediated Neutrophilic Airway Inflammation: A Therapeutic Target for Patients With Uncontrolled Asthma

PURPOSE

Suppression of tumorigenicity 2 (ST2) has been proposed as the receptor contributing to neutrophilic inflammation in patients with type 2-low asthma. However, the exact role of ST2 in neutrophil activation remains poorly understood.

METHODS

A total of 105 asthmatic patients (classified into 3 groups according to control status: the controlled asthma [CA], partly-controlled asthma [PA], and uncontrolled asthma [UA] groups), and 104 healthy controls were enrolled to compare serum levels of soluble ST2 (sST2) and interleukin (IL)-33. Moreover, the functions of ST2 in neutrophils and macrophages (Mϕ) were evaluated ex vivo and in vivo.

RESULTS

Serum sST2 levels were significantly higher in the UA group than in the CA or PA groups (P < 0.05 for all) with a negative correlation between serum sST2 and forced expiratory volume in 1 second % (r = -0.203, P = 0.038). Significantly higher expression of ST2 receptors on peripheral neutrophils was noted in the UA group than in the PA or CA groups. IL-33 exerted its effects on the production of reactive oxygen species, the formation of extracellular traps from neutrophils, and Mϕ polarization/activation. In neutrophilic asthmatic mice, treatment with anti-ST2 antibody significantly suppressed proinflammatory cytokines (tumor necrosis factor-alpha and IL-17A) as well as the numbers of immune cells (neutrophils, Mϕ, and group 3 innate lymphoid cells) in the lungs.

CONCLUSIONS

These results suggest that IL-33 induces the activation of neutrophils and Mϕ via ST2 receptors, leading to neutrophilic airway inflammation and poor control status of asthma. ST2 could be a therapeutic target for neutrophilic airway inflammation in patients with UA.

Blood transcriptomic signature in type-2 biomarker-low severe asthma and asthma control

BACKGROUND

Patients with type-2 (T2) cytokine-low severe asthma often have persistent symptoms despite suppression of T2 inflammation with corticosteroids.

OBJECTIVES

We sought to analyze whole blood transcriptome from 738 samples in T2-biomarker-high/-low patients with severe asthma to relate transcriptomic signatures to T2 biomarkers and asthma symptom scores.

METHODS

Bulk RNA-seq data were generated for blood samples (baseline, week 24, week 48) from 301 participants recruited to a randomized clinical trial of corticosteroid optimization in severe asthma. Unsupervised clustering, differential gene expression analysis, and pathway analysis were performed. Patients were grouped by T2-biomarker status and symptoms. Associations between clinical characteristics and differentially expressed genes (DEGs) associated with biomarker and symptom levels were investigated.

RESULTS

Unsupervised clustering identified 2 clusters; cluster 2 patients were blood eosinophil-low/symptom-high and more likely to be receiving oral corticosteroids (OCSs). Differential gene expression analysis of these clusters, with and without stratification for OCSs, identified 2960 and 4162 DEGs, respectively. Six hundred twenty-seven of 2960 genes remained after adjusting for OCSs by subtracting OCS signature genes. Pathway analysis identified dolichyl-diphosphooligosaccharide biosynthesis and assembly of RNA polymerase I complex as significantly enriched pathways. No stable DEGs were associated with high symptoms in T2-biomarker-low patients, but numerous associated with elevated T2 biomarkers, including 15 that were upregulated at all time points irrespective of symptom level.

CONCLUSIONS

OCSs have a considerable effect on whole blood transcriptome. Differential gene expression analysis demonstrates a clear T2-biomarker transcriptomic signature, but no signature was found in association with T2-biomarker-low patients, including those with a high symptom burden.

Type-2-low severe asthma endotypes for new treatments: the new asthma frontier

PURPOSE OF REVIEW

Type-2 (T2)-high asthma represents a well defined group of severe eosinophilic asthma for which there are now effective biologic therapies targetting the interleukins (ILs) 4, 5 and 13, and Immunoglobulin E. T2-low asthma detected in the clinic by a low blood eosinophil count remains ill-defined and is the focus of this review.

RECENT FINDINGS

By analysing transcriptomic and proteomic expression in sputum samples in U-BIOPRED cohort, both T2-high and -low molecular phenotypes have been described. Using clustering approaches, a neutrophilic-predominant cluster associated with activation markers of neutrophilic and inflammasome activation with interferon and tumour necrosis factor expression, together with a cluster of paucigranulocytic inflammation linked to oxidative phosphorylation and senescence pathways have been described. Using gene set variation analysis, specific molecular phenotypes driven by IL-6 trans-signalling pathway, or those by IL-6, IL-17 and IL-22 pathways were identified linked to a mixed granulocytic or neutrophilic inflammation.

SUMMARY

Previous trials of antineutrophilic agents in asthma have failed because enrolled patients were not specifically chosen for these targeted treatments. Although the T2-low molecular pathways should be validated in other cohorts, the availability of targeted therapies indicated for other autoimmune conditions should encourage a trial of these respective biological therapies for these specific molecular phenotypes.

New insights into the pathophysiology and therapeutic targets of asthma and comorbid chronic rhinosinusitis with or without nasal polyposis

Asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP) are chronic respiratory diseases. These two disorders often co-exist based on common anatomical, immunological, histopathological, and pathophysiological basis. Usually, asthma with comorbid CRSwNP is driven by type 2 (T2) inflammation which predisposes to more severe, often intractable, disease. In the past two decades, innovative technologies and detection techniques in combination with newly introduced targeted therapies helped shape our understanding of the immunological pathways underlying inflammatory airway diseases and to further identify several distinct clinical and inflammatory subsets to enhance the development of more effective personalized treatments. Presently, a number of targeted biologics has shown clinical efficacy in patients with refractory T2 airway inflammation, including anti-IgE (omalizumab), anti-IL-5 (mepolizumab, reslizumab)/anti-IL5R (benralizumab), anti-IL-4R-α (anti-IL-4/IL-13, dupilumab), and anti-TSLP (tezepelumab). In non-type-2 endotypes, no targeted biologics have consistently shown clinical efficacy so far. Presently, multiple therapeutical targets are being explored including cytokines, membrane molecules and intracellular signalling pathways to further expand current treatment options for severe asthma with and without comorbid CRSwNP. In this review, we discuss existing biologics, those under development and share some views on new horizons.

Mechanistic Links Between Obesity and Airway Pathobiology Inform Therapies for Obesity-Related Asthma

Obesity-related asthma is associated with a high disease burden and a poor response to existent asthma therapies, suggesting that it is a distinct asthma phenotype. The proposed mechanisms that contribute to obesity-related asthma include the effects of the mechanical load of obesity, adipokine perturbations, and immune dysregulation. Each of these influences airway smooth muscle function. Mechanical fat load alters airway smooth muscle stretch affecting airway wall geometry, airway smooth muscle contractility, and agonist delivery; weight loss strategies, including medically induced weight loss, counter these effects. Among the metabolic disturbances, insulin resistance and free fatty acid receptor activation influence distinct signaling pathways in the airway smooth muscle downstream of both the M2 muscarinic receptor and the β2 adrenergic receptor, such as phospholipase C and the extracellular signal-regulated kinase signaling cascade. Medications that decrease insulin resistance and dyslipidemia are associated with a lower asthma disease burden. Leptin resistance is best understood to modulate muscarinic receptors via the neural pathways but there are no specific therapies for leptin resistance. From the immune perspective, monocytes and T helper cells are involved in systemic pro-inflammatory profiles driven by obesity, notably associated with elevated levels of interleukin-6. Clinical trials on tocilizumab, an anti-interleukin antibody, are ongoing for obesity-related asthma. This armamentarium of therapies is distinct from standard asthma medications, and once investigated for its efficacy and safety among children, will serve as a novel therapeutic intervention for pediatric obesity-related asthma. Irrespective of the directionality of the association between asthma and obesity, airway-specific mechanistic studies are needed to identify additional novel therapeutic targets for obesity-related asthma.

T2-Low Asthma: A Discussed but Still Orphan Disease

Asthma affects 10% of the worldwide population; about 5% of cases are severe with the need for target therapies such as biologics. All the biologics approved for asthma hit the T2 pathway of inflammation. T2-high asthma is classified as allergic and non-allergic, whereas T2-low asthma can be further defined as paucigranulocytic asthma, Type 1 and Type-17 inflammation and the neutrophilic form that accounts for 20-30% of all patients with asthma. Neutrophilic asthma's prevalence is even higher in patients with severe or refractory asthma. We searched Medline and PubMed archives from the past ten years for articles with the subsequent titles: "neutrophilic asthma", "non-type 2 asthma" and "paucigranulocytic asthma". We identified 177 articles; 49 were considered relevant by the title and 33 by the reading of the abstract. Most of these articles are reviews (n = 19); only 6 are clinical trials. No study identified an effective treatment. We used the literature reported by these articles to search for further biologic treatments that target pathways different from T2. We identified 177 articles, 93 of which were considered relevant for the review and included in the present article. In conclusion, T2-low asthma remains poorly investigated in terms of biomarkers, especially as a therapeutic orphan disease.

Anti-Tumor Necrosis Factor for Supplementary Management in Severe Asthma: A Systematic Review and Meta-analysis

Tumor-necrosis factor (TNF) is recognized as a therapeutic target in inflammatory diseases, including asthma. In severe forms of asthma, biologics such as anti-TNF are rendered to be investigated as therapeutic options in severe asthma. Hence, this work is done to assess the efficacy and safety of anti-TNF as a supplementary therapy for patients with severe asthma. A systematic search of 3 databases (Cochrane Central Register of Controlled Trials, MEDLINE, ClinicalTrials.gov) was performed to identify for published and unpublished randomized controlled trials comparing anti-TNF (etanercept, adalimumab, infliximab, certolizumab pegol, golimumab) with placebo in patients diagnosed with persistent or severe asthma. Random-effects model was used to estimate risk ratios and mean differences (MDs) with confidence intervals (95% CIs). PROSPERO registration number is CRD42020172006. Four trials with 489 randomized patients were included. Comparison between etanercept and placebo involved 3 trials while comparison between golimumab and placebo involved 1 trial. Etanercept produced a small but significant impairment in forced expiratory flow in 1 second (MD 0.33, 95% CI 0.09-0.57, I² statistic = 0%, P = 0.008) and a modest improvement of asthma control using the Asthma Control Questionnaire. However, using the Asthma Quality of Life Questionnaire, the patients exhibit an impaired quality of life with etanercept. Treatment with etanercept showed a reduced injection site reaction and gastroenteritis compared with placebo. Although treatment with anti-TNF is shown to improve asthma control, severe asthma patients did not benefit from this therapy as there is limited evidence for improvement in lung function and reduction of asthma exacerbation. Hence, it is unlikely to prescribe anti-TNF in adults with severe asthma.

Definition, Phenotyping of Severe Asthma, Including Cluster Analysis

Asthma is defined as severe when it is uncontrolled despite the high intensity of treatment, or that loses control when a therapeutic step down is tried.These patients, for years, have been "uniformly" treated with massive doses of inhaled and oral corticosteroids regardless of their inflammatory state.Initially, asthma was considered of genesis "exclusively allergic." Subsequently, thanks to the development of noninvasive tools and of human monoclonal antibodies targeting interleukin 5, a pathogenetic role has been given to eosinophils. Management of steroids based on sputum eosinophil counts has been suggested according to clinical phenotypes identified through cluster analysis.The algorithms obtained from the cluster analysis have proved later to be poorly predictive of the inflammatory phenotype and difficult to apply in clinical practice.In the new era of precision medicine, the greatest challenge is finding clinical or biological elements predictive of response to therapies such as biologics. Cluster analyses performed on omics data or on cohorts of patients treated with biologics are more promising in this sense.In this article, starting from the current definition of severe asthma, we review the phenotypes proposed over time to date, showing the difficulty underlying the process of "phenotyping" due to the scarcity of available biomarkers.

Combination of IL-17A/F and TNF-α uniquely alters the bronchial epithelial cell proteome to enhance proteins that augment neutrophil migration

Background

The heterodimer interleukin (IL)-17A/F is elevated in the lungs in chronic respiratory disease such as severe asthma, along with the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). Although IL-17A/F and TNF-α are known to functionally cooperate to exacerbate airway inflammation, proteins altered by their interaction in the lungs are not fully elucidated.

Results

We used Slow Off-rate Modified Aptamer-based proteomic array to identify proteins that are uniquely and/or synergistically enhanced by concurrent stimulation with IL-17A/F and TNF-α in human bronchial epithelial cells (HBEC). The abundance of 38 proteins was significantly enhanced by the combination of IL-17A/F and TNF-α, compared to either cytokine alone. Four out of seven proteins that were increased > 2-fold were those that promote neutrophil migration; host defence peptides (HDP; Lipocalin-2 (LCN-2) and Elafin) and chemokines (IL-8, GROα). We independently confirmed the synergistic increase of these four proteins by western blots and ELISA. We also functionally confirmed that factors secreted by HBEC stimulated with the combination of IL-17A/F and TNF-α uniquely enhances neutrophil migration. We further showed that PI3K and PKC pathways selectively control IL-17A/F + TNF-α-mediated synergistic production of HDPs LCN-2 and Elafin, but not chemokines IL-8 and GROα. Using a murine model of airway inflammation, we demonstrated enhancement of IL-17A/F, TNF-α, LCN-2 and neutrophil chemokine KC in the lungs, thus corroborating our findings in-vivo.

Conclusion

This study identifies proteins and signaling mediated by concurrent IL-17A/F and TNF-α exposure in the lungs, relevant to respiratory diseases characterized by chronic inflammation, especially neutrophilic airway inflammation such as severe asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-022-00323-w.

T-cell responses in asthma exacerbations

OBJECTIVE

Asthma is a chronic lung disease comprising multiple endotypes and characterized by periodic exacerbations. A diverse array of T cells has been found to contribute to all endotypes of asthma in pathogenic and regulatory roles. Here, we review the contributions of CD4+, CD8+, and unconventional T cells in allergic and nonallergic asthma.

DATA SOURCES

Review of published literature pertaining to conventional and unconventional T-cell types in asthma.

STUDY SELECTIONS

Recent peer-reviewed articles pertaining to T cells in asthma, with additional peer-reviewed studies for context.

RESULTS

Much research in asthma has focused on the roles of CD4+ TH cells. Roles for TH2 cells in promoting allergic asthma pathogenesis have been well-described, and the recent description of pathogenic TH2A cells provides additional insight into these responses. Other TH types, notably TH1 and TH17, have been linked to neutrophilic and steroid-resistant asthma phenotypes. Beyond CD4+ T cells, CD8+ Tc2 cells are also strongly associated with allergic asthma. An emerging area for study is unconventional T-cell types, including γδT, invariant natural killer T, and mucosal-associated invariant T cells. Although data in asthma remain limited for these cells, their ability to bridge innate and adaptive responses likely makes them key players in asthma. A number of asthma therapies target T-cell responses, and, although data are limited, they seem to modulate T-cell populations.

CONCLUSION

Given the diversity and heterogeneity of asthma and T-cell responses, there remain many rich avenues for research to better understand the pathogenesis of asthma. Despite the breadth of T cells in asthma, approved therapeutics remain limited to TH2 networks.

Human Lung Mast Cells: Therapeutic Implications in Asthma

Mast cells are strategically located in different compartments of the lung in asthmatic patients. These cells are widely recognized as central effectors and immunomodulators in different asthma phenotypes. Mast cell mediators activate a wide spectrum of cells of the innate and adaptive immune system during airway inflammation. Moreover, these cells modulate the activities of several structural cells (i.e., fibroblasts, airway smooth muscle cells, bronchial epithelial and goblet cells, and endothelial cells) in the human lung. These findings indicate that lung mast cells and their mediators significantly contribute to the immune induction of airway remodeling in severe asthma. Therapies targeting mast cell mediators and/or their receptors, including monoclonal antibodies targeting IgE, IL-4/IL-13, IL-5/IL-5Rα, IL-4Rα, TSLP, and IL-33, have been found safe and effective in the treatment of different phenotypes of asthma. Moreover, agonists of inhibitory receptors expressed by human mast cells (Siglec-8, Siglec-6) are under investigation for asthma treatment. Increasing evidence suggests that different approaches to depleting mast cells show promising results in severe asthma treatment. Novel treatments targeting mast cells can presumably change the course of the disease and induce drug-free remission in bronchial asthma. Here, we provide an overview of current and promising treatments for asthma that directly or indirectly target lung mast cells.

Anti-IL-5 therapies for asthma

BACKGROUND

This is the second update of previously published reviews in the Cochrane Library (2015, first update 2017). Interleukin-5 (IL-5) is the main cytokine involved in the proliferation, maturation, activation and survival of eosinophils, which cause airway inflammation and are a classic feature of asthma. Studies of monoclonal antibodies targeting IL-5 or its receptor (IL-5R) suggest they reduce asthma exacerbations, improve health-related quality of life (HRQoL) and lung function in appropriately selected patients, justifying their inclusion in the latest guidelines.

OBJECTIVES

To compare the effects of therapies targeting IL-5 signalling (anti-IL-5 or anti-IL-5Rα) with placebo on exacerbations, health-related quality-of-life (HRQoL) measures and lung function in adults and children with chronic asthma, and specifically in those with eosinophilic asthma refractory to existing treatments.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trials registers, manufacturers' websites, and reference lists of included studies. The most recent search was 7 February 2022.

SELECTION CRITERIA

We included randomised controlled trials comparing mepolizumab, reslizumab and benralizumab versus placebo in adults and children with asthma.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and analysed outcomes using a random-effects model. We used standard methods expected by Cochrane.

MAIN RESULTS

Seventeen studies on about 7600 participants met the inclusion criteria. Six used mepolizumab, five used reslizumab, and six used benralizumab. One study using benralizumab was terminated early due to sponsor decision and contributed no data. The studies were predominantly on people with severe eosinophilic asthma, which was similarly but variably defined. One was in children aged 6 to 17 years; nine others included children over 12 years but did not report results by age group separately. We deemed the overall risk of bias to be low, with all studies contributing data of robust methodology. We considered the certainty of the evidence for all comparisons to be high overall using the GRADE scheme, except for intravenous (IV) mepolizumab and subcutaneous (SC) reslizumab because these are not currently licensed delivery routes. The anti-IL-5 treatments assessed reduced rates of 'clinically significant' asthma exacerbation (defined by treatment with systemic corticosteroids for three days or more) by approximately half in participants with severe eosinophilic asthma on standard care (at least medium-dose inhaled corticosteroids (ICS)) with poorly controlled disease (either two or more exacerbations in the preceding year or Asthma Control Questionnaire (ACQ) score of 1.5 or more), except for reslizumab SC. The rate ratios for these effects were 0.45 (95% confidence interval (CI) 0.36 to 0.55; high-certainty evidence) for mepolizumab SC, 0.53 (95% CI 0.44 to 0.64; moderate-certainty evidence) for mepolizumab IV, 0.43 (95% CI 0.33 to 0.55; high-certainty evidence) for reslizumab IV, and 0.59 (95% CI 0.52 to 0.66; high-certainty evidence) for benralizumab SC. Non-eosinophilic participants treated with benralizumab also showed a significant reduction in exacerbation rates, an effect not seen with reslizumab IV, albeit in only one study. No data were available for non-eosinophilic participants treated with mepolizumab. There were improvements in validated HRQoL scores with all anti-IL-5 agents in severe eosinophilic asthma. This met the minimum clinically important difference (MCID) for the broader St. George's Respiratory Questionnaire (SGRQ; 4-point change) for benralizumab only, but the improvement in the ACQ and Asthma Quality of Life Questionnaire (AQLQ), which focus on asthma symptoms, fell short of the MCID (0.5 point change for both ACQ and AQLQ) for all of the interventions. The evidence for an improvement in HRQoL scores in non-eosinophilic participants treated with benralizumab and reslizumab was weak, but the tests for subgroup difference were negative. All anti-IL-5 treatments produced small improvements in mean pre-bronchodilator forced expiratory flow in one second (FEV1) of between 0.08 L and 0.15 L in eosinophilic participants, which may not be sufficient to be detected by patients. There were no excess serious adverse events with any anti-IL-5 treatment; in fact, there was a reduction in such events with benralizumab, likely arising from fewer asthma-related hospital admissions. There was no difference compared to placebo in adverse events leading to discontinuation with mepolizumab or reslizumab, but significantly more discontinued benralizumab than placebo, although the absolute numbers were small (42/2026 (2.1%) benralizumab versus 11/1227 (0.9%) placebo). The implications for efficacy or adverse events are unclear.

AUTHORS' CONCLUSIONS

Overall this analysis supports the use of anti-IL-5 treatments as an adjunct to standard care in people with severe eosinophilic asthma and poor symptom control. These treatments roughly halve the rate of asthma exacerbations in this population. There is limited evidence for improved HRQoL scores and lung function, which may not meet clinically detectable levels. The studies did not report safety concerns for mepolizumab or reslizumab, or any excess serious adverse events with benralizumab, although there remains a question over adverse events significant enough to prompt discontinuation. Further research is needed on biomarkers for assessing treatment response, optimal duration and long-term effects of treatment, risk of relapse on withdrawal, non-eosinophilic patients, children (particularly under 12 years), comparing anti-IL-5 treatments to each other and, in patients meeting relevant eligibility criteria, to other biological (monoclonal antibody) therapies. For benralizumab, future studies should closely monitor rates of adverse events prompting discontinuation.

Differences in Clinical Presentation of Eosinophilic Esophagitis in Pediatric Patients With Ulcerative Colitis and Crohn Disease

SIGNIFICANCE

Eosinophilic esophagitis (EoE) is an inflammatory condition characterized by T helper-2 (T H 2) cytokines. Ulcerative colitis (UC) and Crohn disease (CD) are inflammatory conditions with different clinical presentations and immune profiles. UC is associated with T H 2 cytokines and CD with T H 1 cytokines. We investigated potential differences in the association of EoE with UC and CD because of these different immune profiles.

METHODS

We utilized ICD-9 and ICD-10 codes to find patients with inflammatory bowel disease (IBD) and EoE. We defined EoE as any esophageal biopsy with >15 eosinophils. We collected demographic, clinical, laboratory, endoscopic, and histological data.

RESULTS

Thirty patients had both EoE and IBD. 14.9% of UC patients had EoE and 5.7% of CD patients had EoE. 64.7% of UC patients presented with UC and EoE at the same time, whereas 76.9% of CD patients presented with EoE at follow up. Ten of 13 CD patients were on anti-tumor necrosis factor (TNF) at EoE diagnosis. No UC patients were on anti-TNF at EoE diagnosis. Eighty-three percent of CD patients had mild disease or were in remission, whereas 50% of UC patients had moderate to severe disease at the time of EoE diagnosis.

CONCLUSION

A higher percentage of UC than CD patients had EoE. EoE was more likely to be present at the initial diagnosis of UC than CD. EoE was more likely after diagnosis and treatment of CD with anti-TNF, when CD activity was mild or in remission. The difference in presentation suggests that anti-TNF or it's impact on inflammation may differentially impact the association of EoE with CD and UC.

Corticosteroid resistance in asthma: Cellular and molecular mechanisms

Inhaled glucocorticoids (GCs) are drugs widely used as treatment for asthma patients. They prevent the recruitment and activation of lung immune and inflammatory cells and, moreover, have profound effects on airway structural cells to reverse the effects of disease on airway inflammation. GCs bind to a specific receptor, the glucocorticoid receptor (GR), which is a member of the nuclear receptor superfamily and modulates pro- and anti-inflammatory gene transcription through a number of distinct and complementary mechanisms. Targets genes include many pro-inflammatory mediators such as chemokines, cytokines, growth factors and their receptors. Inhaled GCs are very effective for most asthma patients with little, if any, systemic side effects depending upon the dose. However, some patients show poor asthma control even after the administration of high doses of topical or even systemic GCs. Several mechanisms relating to inflammation have been considered to be responsible for the onset of the relative GC resistance observed in these patients. In these patients, the side-effect profile of GCs prevent continued use of high doses and new drugs are needed. Targeting the defective pathways associated with GC function in these patients may also reactivate GC responsiveness.

Neutrophils and Asthma

Although eosinophilic inflammation is characteristic of asthma pathogenesis, neutrophilic inflammation is also marked, and eosinophils and neutrophils can coexist in some cases. Based on the proportion of sputum cell differentiation, asthma is classified into eosinophilic asthma, neutrophilic asthma, neutrophilic and eosinophilic asthma, and paucigranulocytic asthma. Classification by bronchoalveolar lavage is also performed. Eosinophilic asthma accounts for most severe asthma cases, but neutrophilic asthma or a mixture of the two types can also present a severe phenotype. Biomarkers for the diagnosis of neutrophilic asthma include sputum neutrophils, blood neutrophils, chitinase-3-like protein, and hydrogen sulfide in sputum and serum. Thymic stromal lymphoprotein (TSLP)/T-helper 17 pathways, bacterial colonization/microbiome, neutrophil extracellular traps, and activation of nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 pathways are involved in the pathophysiology of neutrophilic asthma and coexistence of obesity, gastroesophageal reflux disease, and habitual cigarette smoking have been associated with its pathogenesis. Thus, targeting neutrophilic asthma is important. Smoking cessation, neutrophil-targeting treatments, and biologics have been tested as treatments for severe asthma, but most clinical studies have not focused on neutrophilic asthma. Phosphodiesterase inhibitors, anti-TSLP antibodies, azithromycin, and anti-cholinergic agents are promising drugs for neutrophilic asthma. However, clinical research targeting neutrophilic inflammation is required to elucidate the optimal treatment.

Inhibition of Spleen Tyrosine Kinase Restores Glucocorticoid Sensitivity to Improve Steroid-Resistant Asthma

Background: Regulation or restoration of therapeutic sensitivity to glucocorticoids is important in patients with steroid-resistant asthma. Spleen tyrosine kinase (Syk) is activated at high levels in asthma patients and mouse models, and small-molecule Syk inhibitors such as R406 show potent anti-inflammatory effects in the treatment of immune inflammatory diseases. Several downstream signaling molecules of Syk are involved in the glucocorticoid response, so we hypothesized that R406 could restore sensitivity to dexamethasone in severe steroid-resistant asthma.

Objective: To discover the role of the Syk inhibitor R406 in glucocorticoid resistance in severe asthma.

Methods: Steroid-resistant asthma models were induced by exposure of C57BL/6 mice to house dust mite (HDM) and β-glucan and by TNF-α administration to the bronchial epithelial cell line BEAS-2B. We evaluated the role of the Syk inhibitor R406 in dexamethasone (Dex)-insensitive airway inflammation. Pathological alterations and cytokines in the lung tissues and inflammatory cells in BALF were assessed. We examined the effects of Dex or R406 alone and in combination on the phosphorylation of MAPKs, glucocorticoid receptor (GR) and Syk, as well as the transactivation and transrepression induced by Dex in mouse lung tissues and BEAS-2B cells.

Results: Exposure to HDM and β-glucan induced steroid-resistant airway inflammation. The Syk inhibitor R406 plus Dex significantly reduced airway inflammation compared with Dex alone. Additionally, TNF-α-induced IL-8 production in BEAS-2B cells was not completely inhibited by Dex, while R406 markedly promoted the anti-inflammatory effect of Dex. Compared with Dex alone, R406 enhanced Dex-mediated inhibition of the phosphorylation of MAPKs and GR-Ser226 induced by allergens or TNF-α in vivo and in vitro. Moreover, R406 also restored the impaired expression and nuclear translocation of GRα induced by TNF-α. Then, the activation of NF-κB and decreased HDAC2 activity in the asthmatic model were further regulated by R406, as well as the expression of GILZ.

Conclusions: The Syk inhibitor R406 improves sensitivity to dexamethasone by modulating GR. This study provides a reference for the development of drugs to treat severe steroid-resistant asthma.

The Interactions Between Autoinflammation and Type 2 Immunity: From Mechanistic Studies to Epidemiologic Associations

Autoinflammatory diseases are a group of clinical syndromes characterized by constitutive overactivation of innate immune pathways. This results in increased production of or responses to monocyte- and neutrophil-derived cytokines such as interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), and Type 1 interferon (IFN). By contrast, clinical allergy is caused by dysregulated type 2 immunity, which is characterized by expansion of T helper 2 (Th2) cells and eosinophils, as well as overproduction of the associated cytokines IL-4, IL-5, IL-9, and IL-13. Traditionally, type 2 immune cells and autoinflammatory effectors were thought to counter-regulate each other. However, an expanding body of evidence suggests that, in some contexts, autoinflammatory pathways and cytokines may potentiate type 2 immune responses. Conversely, type 2 immune cells and cytokines can regulate autoinflammatory responses in complex and context-dependent manners. Here, we introduce the concepts of autoinflammation and type 2 immunity. We proceed to review the mechanisms by which autoinflammatory and type 2 immune responses can modulate each other. Finally, we discuss the epidemiology of type 2 immunity and clinical allergy in several monogenic and complex autoinflammatory diseases. In the future, these interactions between type 2 immunity and autoinflammation may help to expand the spectrum of autoinflammation and to guide the management of patients with various autoinflammatory and allergic diseases.

Novel potential treatable traits in asthma: Where is the research taking us?

Asthma is a complex, heterogeneous disease in which the underlying mechanisms are not fully understood. Patients are often grouped into phenotypes (based on clinical, biologic, and physiologic characteristics) and endotypes (based on distinct genetic or molecular mechanisms). Recently, patients with asthma have been broadly split into 2 phenotypes based on their levels of type 2 inflammation: type 2 and non-type 2 asthma. However, this approach is likely oversimplified, and our understanding of the non-type 2 mechanisms in asthma remains extremely limited. A better understanding of asthma phenotypes and endotypes may assist in development of drugs for new therapeutic targets in asthma. One approach is to identify "treatable traits," which are specific patient characteristics related to phenotypes and endotypes that can be targeted by therapies. This review will focus on emerging treatable traits in asthma and aim to describe novel patient subgroups and endotypes that may represent the next step in the search for new therapeutic approaches.

T2-low: what do we know?: Past, present, and future of biologic therapies in noneosinophilic asthma

T2-low asthma is an often severe asthma subtype with limited treatment options and biologic therapeutics are lacking. Several monoclonal antibodies (mAbs) targeting non-T2 cytokines were previously reported to be ineffective in asthma. These trials often investigated heterogeneous asthma populations and negative outcomes could be related to unsuitable study cohorts. More tailored approaches in selecting participants based on specific biomarkers have been beneficial in treating severe T2-high asthma. Similarly, mAbs previously deemed ineffective bear the potential to be useful when administered to the correct target population. Here, we review individual clinical trials conducted between 2005 and 2021 and assess the suitability of the selected cohorts, whether study end points were met, and whether outcome measures were appropriate to investigate the effectiveness of the respective drug. We discuss potential target groups within the T2-low asthma population and suggest biomarkers that may predict a treatment response. Furthermore, we assess whether biomarker-guided approaches or subgroup analyses were associated with more positive study outcomes. The mAbs directed against alarmins intervene early in the inflammatory cascade and are the first mAbs found to have efficacy in T2-low asthma. Several randomized controlled trials performed predefined subgroup analyses that included T2-low asthma. Subgroup analyses were associated with positive outcomes and were able to reveal a stronger response in at least 1 subgroup. A better understanding of T2-low subgroups and specific biomarkers is necessary to identify the most responsive target population for a given mAb.

Therapeutic Potential of Combining IL-6 and TNF Blockade in a Mouse Model of Allergic Asthma

Combined anti-cytokine therapy is a promising therapeutic approach for uncontrolled steroid-resistant asthma. In this regard, simultaneous blockade of IL-4 and IL-13 signaling by Dupilumab (anti-IL-4Ra monoclonal antibody) was recently approved for severe eosinophilic asthma. However, no therapeutic options for neutrophilic asthma are currently available. Recent advances in our understanding of asthma pathogenesis suggest that both IL-6 and TNF may represent potential targets for treatment of severe neutrophilic asthma. Nevertheless, the efficacy of simultaneous pharmacological inhibition of TNF and IL-6 in asthma was not yet studied. To evaluate the potency of combined cytokine inhibition, we simultaneously administrated IL-6 and TNF inhibitors to BALB/c mice with HDM-induced asthma. Combined IL-6/TNF inhibition, but not individual blockade of these two cytokines, led to complex anti-inflammatory effects including reduced Th2-induced eosinophilia and less prominent Th17/Th1-mediated neutrophilic infiltrate in the airways. Taken together, our results provide evidence for therapeutic potential of combined IL-6/TNF inhibition in severe steroid-resistant asthma.

House dust mite sensitization and exposure affects bronchial epithelial anti-microbial response to viral stimuli in patients with asthma

Introduction

Allergen exposure worsens viral‐triggered asthma exacerbations and could predispose the host to secondary bacterial infections. We have previously demonstrated that exposure to house dust mite (HDM) reduced TLR‐3‐induced IFN‐β in human bronchial epithelial cells (HBECs) from healthy donors. We hypothesize that HDM sensitization in different ways may be involved in both viral and bacterial resistance of HBECs in asthma. In this study, the role of HDM sensitization and effects of HDM exposure on viral stimulus‐challenged HBECs from asthmatic donors have been explored with regard to expression and release of molecules involved in anti‐viral and anti‐bacterial responses, respectively.

Methods

HBECs from HDM‐sensitized (HDM+) and unsensitized (HDM‐) patients with asthma were used. HBECs were exposed to HDM or heat inactivated (hi)‐HDM (20 μg/ml) for 24 h prior to stimulation with the viral infection mimic, Poly(I:C), for 3 or 24 h. Samples were analyzed with ELISA and RT‐qPCR for β‐defensin‐2, IFN‐β, TSLP, and neutrophil‐recruiting mediators: IL‐8 and TNF‐⍺. NFκB signaling proteins p105, p65, and IκB‐⍺ were analyzed by Western blot.

Results

Poly(I:C)‐induced IFN‐β expression was reduced in HBECs from HDM + compared to HDM‐ patients (p = 0.05). In vitro exposure of HBECs to HDM furthermore reduced anti‐microbial responses to Poly(I:C) including β‐defensin‐2, IL‐8, and TNF‐⍺, along with reduced NFκB activity. This was observed in HBECs from asthma patients sensitized to HDM, as well as in non‐sensitized patients. By contrast, Poly (I:C)‐induced release of TSLP, a driver of T2 inflammation, was not reduced with exposure to HDM.

Conclusion

Using HBECs challenged with viral infection mimic, Poly(I:C), we demonstrated that allergic sensitization to HDM was associated with impaired anti‐viral immunity and that HDM exposure reduced anti‐viral and anti‐bacterial defense molecules, but not TSLP, across non‐allergic as well as allergic asthma. These data suggest a role of HDM in the pathogenesis of asthma exacerbations evoked by viral infections including sequential viral‐bacterial and viral‐viral infections.

Asthma Phenotype with Metabolic Dysfunction

Asthma is chronic eosinophilic bronchitis with the dominancy of T helper 2 (Th2) inflammation. However, patients with asthma and metabolic dysfunction have pathogenic and pathological differences from those with Th2 inflammation. Metabolic dysfunction, typically presented as metabolic syndrome, has several important clinical components including central obesity, insulin resistance or glucose intolerance, dyslipidemia, and vitamin D deficiency. Data from large epidemiological studies support the significance of these components in the control of asthma and their contribution to airway remodeling, suggesting the presence of an asthma phenotype with metabolic dysfunction. These components are quite interactive with each other, so it is difficult to reveal the individual role of each. It is well known that asthma is difficult to treat in patients with obesity, due in part to inadequate response to inhaled corticosteroids. Additionally, vitamin D deficiency and insulin resistance have been regarded as aggravating factors of asthma control and airway remodeling. Recent clinical and in vivo studies have revealed the specific mechanisms of these components, which may aggravate asthma control and airway remodeling. In this review article, I summarize the recent studies and unmet needs for patients with asthma and metabolic dysfunction.

Which Therapy for Non-Type(T)2/T2-Low Asthma

Currently, the asthmatic population is divided into Type 2-high and non-Type 2/Type 2-low asthmatics, with 50% of patients belonging to one of the two groups. Differently from T2-high, T2-low asthma has not been clearly defined yet, and the T2-low patients are identified on the basis of the absence or non-predominant expression of T2-high biomarkers. The information about the molecular mechanisms underpinning T2-low asthma is scarce, but researchers have recognized as T2-low endotypes type 1 and type 3 immune response, and remodeling events occurring without inflammatory processes. In addition, the lack of agreed biomarkers reprents a challenge for the research of an effective therapy. The first-choice medication is represented by inhaled corticosteroids despite a low efficacy is reported for/in T2-low patients. However, macrolides and long-acting anti-muscarinic drugs have been recognized as efficacious. In recent years, clinical trials targeting biomarkers playing key roles in T3 and T1 immune pathways, alarmins, and molecules involved in neutrophil recruitment have provided conflicting results probably misleading (or biased) in patients' selection. However, further studies are warranted to achieve a precise characterization of T2-low asthma with the aim of defining a tailored therapy for each single asthmatic patient.

Considering biomarkers in asthma disease severity

Amongst patients with asthma, reliance on the type/dose of prescribed medication and symptom control does not adequately capture those at risk of adverse outcomes, and we need biomarkers for risk and treatment stratification which are consistently accurate, readily quantifiable and reproducible. The majority of patients with severe asthma, regardless of age, have predominant type-2 (T2) inflammation mediated disease, making airway/blood eosinophils, FeNO, periostin and/or allergic sensitization potentially important biomarkers for severe disease. In both adult and pediatric asthma, there is scope to improve prediction of severe attacks by using a composite T2 biomarkers of blood eosinophils and FeNO. Technological advances in component-resolved diagnostics (CRD) microarray technologies coupled with the development of interpretation software offer a possibility to use CRD as biomarkers of asthma severity amongst sensitized asthmatics. Genetic predisposition and polygenic risk scores of relevant traits (e.g., lung function, host immune responses, biomarkers of exposure from the indoor and outdoor environment, infection and microbial dysbiosis) may also contribute to prediction algorithms. We challenge the idea that asthma can be accurately defined in an individual patient by a discrete and static "endotype" (e.g., T2-high asthma). As we traverse the new era of molecular endotyping in asthma, we need to understand how relevant mechanisms impact patient outcomes, and in parallel develop new tools and approaches to stratify therapies and define individual patient trajectories.

Our evolving view of neutrophils in defining the pathology of chronic lung disease

Neutrophils are critical components of the body's immune response to infection, being loaded with a potent arsenal of toxic mediators and displaying immense destructive capacity. Given the potential of neutrophils to impart extensive tissue damage, it is perhaps not surprising that when augmented these cells are also implicated in the pathology of inflammatory diseases. Prominent neutrophilic inflammation is a hallmark feature of patients with chronic lung diseases such as chronic obstructive pulmonary disease, severe asthma, bronchiectasis and cystic fibrosis, with their numbers frequently associating with worse prognosis. Accordingly, it is anticipated that neutrophils are central to the pathology of these diseases and represent an attractive therapeutic target. However, in many instances, evidence directly linking neutrophils to the pathology of disease has remained somewhat circumstantial and strategies that have looked to reduce neutrophilic inflammation in the clinic have proved largely disappointing. We have classically viewed neutrophils as somewhat crude, terminally differentiated, insular and homogeneous protagonists of pathology. However, it is now clear that this does not do the neutrophil justice, and we now recognize that these cells exhibit heterogeneity, a pronounced awareness of the localized environment and a remarkable capacity to interact with and modulate the behaviour of a multitude of cells, even exhibiting anti-inflammatory, pro-resolving and pro-repair functions. In this review, we discuss evidence for the role of neutrophils in chronic lung disease and how our evolving view of these cells may impact upon our perceived assessment of their contribution to disease pathology and efforts to target them therapeutically.

From Biomarkers to Novel Therapeutic Approaches in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and complex disorder. In this review, we provided a comprehensive overview of biomarkers involved in COPD, and potential novel biological therapies that may provide additional therapeutic options for COPD. The complex characteristics of COPD have made the recommendation of a generalized therapy challenging, suggesting that a tailored, personalized strategy may lead to better outcomes. Existing and unmet needs for COPD treatment support the continued development of biological therapies, including additional investigations into the potential clinical applications of this approach.

30 Years of Biotherapeutics Development-What Have We Learned?

Since the birth of biotechnology, hundreds of biotherapeutics have been developed and approved by the US Food and Drug Administration (FDA) for human use. These novel medicines not only bring significant benefit to patients but also represent precision tools to interrogate human disease biology. Accordingly, much has been learned from the successes and failures of hundreds of high-quality clinical trials. In this review, we discuss general and broadly applicable themes that have emerged from this collective experience. We base our discussion on insights gained from exploring some of the most important target classes, including interleukin-1 (IL-1), tumor necrosis factor α (TNF-α), IL-6, IL-12/23, IL-17, IL-4/13, IL-5, immunoglobulin E (IgE), integrins and B cells. We also describe current challenges and speculate about how emerging technological capabilities may enable the discovery and development of the next generation of biotherapeutics.

Innate-like Lymphocytes and Innate Lymphoid Cells in Asthma

Asthma is a chronic pulmonary disease, highly associated with immune disorders. The typical symptoms of asthma include airway hyperresponsiveness (AHR), airway remodeling, mucus overproduction, and airflow limitation. The etiology of asthma is multifactorial and affected by genetic and environmental factors. Increasing trends toward dysbiosis, smoking, stress, air pollution, and a western lifestyle may account for the increasing incidence of asthma. Based on the presence or absence of eosinophilic inflammation, asthma is mainly divided into T helper 2 (Th2) and non-Th2 asthma. Th2 asthma is mediated by allergen-specific Th2 cells, and eosinophils activated by Th2 cells via the secretion of interleukin (IL)-4, IL-5, and IL-13. Different from Th2 asthma, non-Th2 asthma shows little eosinophilic inflammation, resists to corticosteroid treatment, and occurs mainly in severe asthmatic patients. Previous studies of asthma primarily focused on the function of Th2 cells, but, with the discovery of non-Th2 asthma and the involvement of innate lymphoid cells (ILCs) in the pathogenesis of asthma, tissue-resident innate immune cells in the lung have become the focus of attention in asthma research. Currently, innate-like lymphocytes (ILLs) and ILCs as important components of the innate immune system in mucosal tissues are reportedly involved in the pathogenesis of or protection against both Th2 and non-Th2 asthma. These findings of the functions of different subsets of ILLs and ILCs may provide clues for the treatment of asthma.

Novel mechanisms of action contributing to Benralizumab's potent anti-eosinophilic activity

Benralizumab is a humanised, anti-IL-5Rα monoclonal antibody with anti-eosinophilic activity. Lack of fucose (afucosylation) increases its affinity to CD16a and significantly enhances antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells. Although benralizumab proved clinically efficacious in clinical trials for patients with severe asthma and hypereosinophilic syndrome, in-depth characterisation of its anti-eosinophilic mechanisms of action remain elusive. Here, we further investigated the mechanisms involved in benralizumab's anti-eosinophilic activities. In the presence of NK cells benralizumab induced potent eosinophil apoptosis as demonstrated by the upstream induction of caspase 3/7 and upregulation of cytochrome C. In addition, we uncovered a previously unrecognised mechanism whereby benralizumab can induce eosinophil phagocytosis/efferocytosis by macrophages, a process called antibody-dependent cell phagocytosis (ADCP). Using live cell imaging we unravel the stepwise processes leading to eosinophil apoptosis and uptake by activated macrophages. Through careful observations of cellular co-culture assays we identified a novel role for macrophage derived TNF to further enhance benralizumab-mediated eosinophil apoptosis through activation of TNF-receptor 1 on eosinophils. TNF-induced eosinophil apoptosis was associated with Cytochrome C upregulation, mitochondrial membrane depolarisation, and increased caspase 3/7 activity. Moreover, activated NK cells were found to amplify this axis through the secretion of IFNγ, subsequently driving TNF expression by macrophages. Our data provide insights into the timely appearance of events leading to benralizumab-induced eosinophil apoptosis and suggest that additional mechanisms may contribute to the potent anti-eosinophilic activity of benralizumab in vivo Importantly, afucosylation of benralizumab strongly enhanced its potency for all mechanisms investigated.

Prevalence of Anemia in Pediatric Patients According to Asthma Control: Propensity Score Analysis

Purpose

To investigate whether the degree of asthma control is associated with anemia in pediatric patients.

Patients and Methods

A cross-sectional study was performed using a dataset from the Health Insurance Reviews & Assessment Service (HIRA) of South Korea in 2016, which included children and adolescent patients diagnosed with asthma. Binary logistic regression was used to assess the association between asthma control and the prevalence of anemia.

Results

A total of 236,429 patients under 18 years old were included in the study, including 233,975 patients with controlled and 2454 with uncontrolled asthma. Binary logistic regression after adjustment for confounding factors showed that patients with uncontrolled asthma had a 2.64-fold higher prevalence of anemia than those with well-controlled asthma (OR = 2.64, 95% CI: 2.16-3.22). While there was no effect of gender on the results, there was a statistically significant association between the prevalence of anemia and asthma control in patients under 13 years old.

Conclusion

These findings suggest that the prevalence of anemia is inversely correlated with asthma control in pediatric patients. Further studies are necessary to obtain pathophysiological insight into the relationship between severe inflammatory diseases and anemia.

Immunologic Adverse Effects of Biologics for the Treatment of Atopy

The use of biologic agents as therapies for atopic diseases such as asthma and atopic dermatitis has increased greatly in recent years. The biological agents used to treat atopic diseases are for the most part monoclonal antibodies that suppress the immune response and reduce inflammation by targeting particular cytokines or other molecules involved in Th1, Th2, or Th17 immune reactions. Various side effects and rare complications have been reported from these agents. In this review, we discuss mechanisms of various adverse effects for the biologic agents currently in use or in development for atopic and inflammatory diseases. Monoclonal antibodies targeting the Th1 and Th17 pathways have been associated with significant side effects, partially due to their ability to cause significant impairment in immune responses to pathogens because of the immunologic alterations that they produce. Biologicals targeting Th2-mediated inflammation have had fewer reported side effects, though many are new and emerging drugs whose adverse effects may remain to be fully elucidated with more use. Therefore, continued long-term safety monitoring is required. As with all therapies, the risks associated with side effects of biologics must be balanced against the benefits these drugs offer for treating atopic diseases. One of the most apparent benefits is the steroid-sparing effect of well-chosen biologic therapy used to treat severe atopic disease. In contrast with the quite favorable safety profile of currently available biologics that target the Th2-mediated immune response, chronic systemic corticosteroid use is associated with significant side effects, many of which impact the majority of patients who are placed on long-term steroid therapy.

Mechanisms and biomarkers of airway epithelial cell damage in asthma: A review

Bronchial asthma is a heterogeneous disease with complex pathological mechanisms representing different phenotypes, including severe asthma. The airway epithelium is a major site of complex pathological changes in severe asthma due, in part, to activation of inflammatory and immune mechanisms in response to noxious agents. Current imaging procedures are unable to accurately measure epithelial and airway remodeling. Damage of airway epithelial cells occurs is linked to specific phenotypes and endotypes which provides an opportunity for the identification of biomarkers reflecting epithelial, and airway, remodeling. Identification of patients with more severe epithelial disruption using biomarkers may also provide personalised therapeutic opportunities and/or markers of successful therapeutic intervention. Here, we review the evidence for ongoing epithelial cell dysregulation in the pathogenesis of asthma, the sentinel role of the airway epithelium and how understanding these molecular mechanisms provides the basis for the identification of candidate biomarkers for asthma prediction, prevention, diagnosis, treatment and monitoring.

Identification and treatment of T2-low asthma in the era of biologics

Currently, and based on the development of relevant biologic therapies, T2-high is the most well-defined endotype of asthma. Although much progress has been made in elucidating T2-high inflammation pathways, no specific clinically applicable biomarkers for T2-low asthma have been identified. The therapeutic approach of T2-low asthma is a problem urgently needing resolution, firstly because these patients have poor response to steroids, and secondly because they are not candidates for the newer targeted biologic agents. Thus, there is an unmet need for the identification of biomarkers that can help the diagnosis and endotyping of T2-low asthma. Ongoing investigation is focusing on neutrophilic airway inflammation mediators as therapeutic targets, including interleukin (IL)-8, IL-17, IL-1, IL-6, IL-23 and tumour necrosis factor-α; molecules that target restoration of corticosteroid sensitivity, mainly mitogen-activated protein kinase inhibitors, tyrosine kinase inhibitors and phosphatidylinositol 3-kinase inhibitors; phosphodiesterase (PDE)3 inhibitors that act as bronchodilators and PDE4 inhibitors that have an anti-inflammatory effect; and airway smooth muscle mass attenuation therapies, mainly for patients with paucigranulocytic inflammation. This article aims to review the evidence for noneosinophilic inflammation being a target for therapy in asthma; discuss current and potential future therapeutic approaches, such as novel molecules and biologic agents; and assess clinical trials of licensed drugs in the treatment of T2-low asthma.

Novel Anti-Cytokine Strategies for Prevention and Treatment of Respiratory Allergic Diseases

Asthma is a heterogeneous inflammatory disease characterized by airflow obstruction, wheezing, eosinophilia and neutrophilia of the airways. Identification of distinct inflammatory patterns characterizing asthma endotypes led to the development of novel therapeutic approaches. Cytokine or cytokine receptor targeting by therapeutic antibodies, such as anti-IL-4 and anti-IL-5, is now approved for severe asthma treatment. However, the complexity of cytokine networks in asthma should not be underestimated. Inhibition of one pro-inflammatory cytokine may lead to perturbed expression of another pro-inflammatory cytokine. Without understanding of the underlying mechanisms and defining the molecular predictors it may be difficult to control cytokine release that accompanies certain disease manifestations. Accumulating evidence suggests that in some cases a combined pharmacological inhibition of pathogenic cytokines, such as simultaneous blockade of IL-4 and IL-13 signaling, or blockade of upstream cytokines, such as TSLP, are more effective than single cytokine targeting. IL-6 and TNF are the important inflammatory mediators in the pathogenesis of asthma. Preliminary data suggests that combined pharmacological inhibition of TNF and IL-6 during asthma may be more efficient as compared to individual neutralization of these cytokines. Here we summarize recent findings in the field of anti-cytokine therapy of asthma and discuss immunological mechanisms by which simultaneous targeting of multiple cytokines as opposed to targeting of a single cytokine may improve disease outcomes.

Inhibitory Effect of Paquinimod on a Murine Model of Neutrophilic Asthma Induced by Ovalbumin with Complete Freund's Adjuvant

Background

Quinoline-3-carboxamides have been used to treat autoimmune/inflammatory diseases in humans because they inhibit the functions of S100 calcium-binding protein A9 (S100A9), which participates in the development of neutrophilic inflammation in asthmatics and in an animal model of neutrophilic asthma. However, the therapeutic effects of these chemicals have not been evaluated in asthma. The purpose of this study was to evaluate the effect of paquinimod, one of the quinoline-3-carboxamides, on a murine model of neutrophilic asthma.

Methods

Paquinimod was orally administered to 6-week-old C57BL/6 mice sensitized and challenged with ovalbumin (OVA)/complete Freund's adjuvant (CFA) and OVA. Lung inflammation and remodeling were evaluated using bronchoalveolar lavage (BAL) and histologic findings including goblet cell count. S100A9, caspase-1, IL-1β, MPO, IL-17, IFN-γ, and TNF-α were measured in lung lysates using western blotting.

Results

Paquinimod restored the enhancement of airway resistance and the increases in numbers of neutrophils and macrophages of BAL fluids and those of goblet cells in OVA/CFA mice toward the levels of sham-treated mice in a dose-dependent manner (0.1, 1, 10, and 25 mg/kg/day, p.o.). Concomitantly, p20 activated caspase-1, IL-1β, IL-17, TNF-α, and IFN-γ levels were markedly attenuated.

Conclusion

These data indicate that paquinimod effectively inhibits neutrophilic inflammation and remodeling in the murine model of neutrophilic asthma, possibly via downregulation of IL-17, IFN-γ, and IL-1β.

Neutrophils in asthma: the good, the bad and the bacteria

Airway inflammation plays a key role in asthma pathogenesis but is heterogeneous in nature. There has been significant scientific discovery with regard to type 2-driven, eosinophil-dominated asthma, with effective therapies ranging from inhaled corticosteroids to novel biologics. However, studies suggest that approximately 1 in 5 adults with asthma have an increased proportion of neutrophils in their airways. These patients tend to be older, have potentially pathogenic airway bacteria and do not respond well to classical therapies. Currently, there are no specific therapeutic options for these patients, such as neutrophil-targeting biologics.Neutrophils comprise 70% of the total circulatory white cells and play a critical defence role during inflammatory and infective challenges. This makes them a problematic target for therapeutics. Furthermore, neutrophil functions change with age, with reduced microbial killing, increased reactive oxygen species release and reduced production of extracellular traps with advancing age. Therefore, different therapeutic strategies may be required for different age groups of patients.The pathogenesis of neutrophil-dominated airway inflammation in adults with asthma may reflect a counterproductive response to the defective neutrophil microbial killing seen with age, resulting in bystander damage to host airway cells and subsequent mucus hypersecretion and airway remodelling. However, in children with asthma, neutrophils are less associated with adverse features of disease, and it is possible that in children, neutrophils are less pathogenic.In this review, we explore the mechanisms of neutrophil recruitment, changes in cellular function across the life course and the implications this may have for asthma management now and in the future. We also describe the prevalence of neutrophilic asthma globally, with a focus on First Nations people of Australia, New Zealand and North America.

Oxidative Imbalance as a Crucial Factor in Inflammatory Lung Diseases: Could Antioxidant Treatment Constitute a New Therapeutic Strategy?

Inflammatory lung disease results in a high global burden of death and disability. There are no effective treatments for the most severe forms of many inflammatory lung diseases, such as chronic obstructive pulmonary disease, emphysema, corticosteroid-resistant asthma, and coronavirus disease 2019; hence, new treatment options are required. Here, we review the role of oxidative imbalance in the development of difficult-to-treat inflammatory lung diseases. The inflammation-induced overproduction of reactive oxygen species (ROS) means that endogenous antioxidants may not be sufficient to prevent oxidative damage, resulting in an oxidative imbalance in the lung. In turn, intracellular signaling events trigger the production of proinflammatory mediators that perpetuate and aggravate the inflammatory response and may lead to tissue damage. The production of high levels of ROS in inflammatory lung diseases can induce the phosphorylation of mitogen-activated protein kinases, the inactivation of phosphoinositide 3-kinase (PI3K) signaling and histone deacetylase 2, a decrease in glucocorticoid binding to its receptor, and thus resistance to glucocorticoid treatment. Hence, antioxidant treatment might be a therapeutic option for inflammatory lung diseases. Preclinical studies have shown that antioxidants (alone or combined with anti-inflammatory drugs) are effective in the treatment of inflammatory lung diseases, although the clinical evidence of efficacy is weaker. Despite the high level of evidence for the efficacy of antioxidants in the treatment of inflammatory lung diseases, the discovery and clinical investigation of safer, more efficacious compounds are now a priority.

Modern View of Neutrophilic Asthma Molecular Mechanisms and Therapy

For a long time asthma was commonly considered as a homogeneous disease. However, recent studies provide increasing evidence of its heterogeneity and existence of different phenotypes of the disease. Currently, classification of asthma into several phenotypes is based on clinical and physiological features, anamnesis, and response to therapy. This review describes five most frequently identified asthma phenotypes. Neutrophilic asthma (NA) deserves special attention, since neutrophilic inflammation of the lungs is closely associated with severity of the disease and with the resistance to conventional corticosteroid therapy. This review focuses on molecular mechanisms of neutrophilic asthma pathogenesis and on the role of Th1- and Th17-cells in the development of this type of asthma. In addition, this review presents current knowledge of neutrophil biology. It has been established that human neutrophils are represented by at least three subpopulations with different biological functions. Therefore, total elimination of neutrophils from the lungs can result in negative consequences. Based on the new knowledge of NA pathogenesis and biology of neutrophils, the review summarizes current approaches for treatment of neutrophilic asthma and suggests new promising ways to treat this type of asthma that could be developed in future.

Treatment options in type-2 low asthma

Monoclonal antibodies targeting IgE or the type-2 cytokines interleukin (IL)-4, IL-5 and IL-13 are proving highly effective in reducing exacerbations and symptoms in people with severe allergic and eosinophilic asthma, respectively. However, these therapies are not appropriate for 30-50% of patients in severe asthma clinics who present with non-allergic, non-eosinophilic, "type-2 low" asthma. These patients constitute an important and common clinical asthma phenotype, driven by distinct, yet poorly understood pathobiological mechanisms. In this review we describe the heterogeneity and clinical characteristics of type-2 low asthma and summarise current knowledge on the underlying pathobiological mechanisms, which includes neutrophilic airway inflammation often associated with smoking, obesity and occupational exposures and may be driven by persistent bacterial infections and by activation of a recently described IL-6 pathway. We review the evidence base underlying existing treatment options for specific treatable traits that can be identified and addressed. We focus particularly on severe asthma as opposed to difficult-to-treat asthma, on emerging data on the identification of airway bacterial infection, on the increasing evidence base for the use of long-term low-dose macrolides, a critical appraisal of bronchial thermoplasty, and evidence for the use of biologics in type-2 low disease. Finally, we review ongoing research into other pathways including tumour necrosis factor, IL-17, resolvins, apolipoproteins, type I interferons, IL-6 and mast cells. We suggest that type-2 low disease frequently presents opportunities for identification and treatment of tractable clinical problems; it is currently a rapidly evolving field with potential for the development of novel targeted therapeutics.

Asthma and Obesity: Two Diseases on the Rise and Bridged by Inflammation

Asthma and obesity are two epidemics affecting the developed world. The relationship between obesity and both asthma and severe asthma appears to be weight-dependent, causal, partly genetic, and probably bidirectional. There are two distinct phenotypes: 1. Allergic asthma in children with obesity, which worsens a pre-existing asthma, and 2. An often non allergic, late-onset asthma developing as a consequence of obesity. In obesity, infiltration of adipose tissue by macrophages M1, together with an increased expression of multiple mediators that amplify and propagate inflammation, is considered as the culprit of obesity-related inflammation. Adipose tissue is an important source of adipokines, such as pro-inflammatory leptin, produced in excess in obesity, and adiponectin with anti-inflammatory effects with reduced synthesis. The inflammatory process also involves the synthesis of pro-inflammatory cytokines such as IL-1β, IL-6, TNFα, and TGFβ, which also contribute to asthma pathogenesis. In contrast, asthma pro-inflammatory cytokines such as IL-4, IL-5, IL-13, and IL-33 contribute to maintain the lean state. The resulting regulatory effects of the immunomodulatory pathways underlying both diseases have been hypothesized to be one of the mechanisms by which obesity increases asthma risk and severity. Reduction of weight by diet, exercise, or bariatric surgery reduces inflammatory activity and improves asthma and lung function.

Biologics for atopic diseases: Indication, side effect management, and new developments

With the advent of biologicals, more and more therapeutics are available that specifically address specific switch points in the pathomechanism of immunologically dominated diseases. Thus, the focus of diagnostics and therapy (precision medicine) is more on the individual disease characteristics of the individual patient. Regarding the different phenotypes of atopic diseases, severe asthma was the first entity for which biologicals were approved, followed by urticaria, and finally atopic dermatitis and chronic rhinosinusitis with nasal polyps. Experience in the treatment of severe bronchial asthma has shown that the intensity of the response to biological therapy depends on the quality of clinical and immunological phenotyping of the patients. This also applies to different diseases of the atopic form, as patients can suffer from several atopic diseases at the same time, each with different characteristics. Biologics are already emerging that may represent a suitable therapy for allergic bronchial asthma, which often occurs together with severe neurodermatitis, and chronic rhinosinusitis with nasal polyps. In practice, however, the question of possible combinations of biologicals for the therapy of complex clinical pictures of individual patients is increasingly arising. In doing so, the side effect profile must be taken into account, including hypersensitivity reactions, whose diagnostic and logistical management must aim at a safe and efficient therapy of the underlying disease. Increased attention must also be paid to biological therapy in pregnancy and planned (predictable) vaccinations as well as existing infections, such as SARS-CoV-2 infection. Before starting a biological therapy, the immune status should be checked with regard to chronic viral and bacterial infections and, if necessary, the vaccination status should be refreshed or missing vaccinations should be made up for before starting therapy. Currently, reliable data on the effect of biologicals on the immunological situation of SARS-CoV-2 infection and COVID-19 are not available. Therefore, research and development of suitable diagnostic methods for detection of immunologically caused side effects as well as detection of potential therapy responders and non-responders is of great importance.

Applying personalized medicine to adult severe asthma

Background: Severe asthma is a heterogeneous disease that consists of various phenotypes driven by different pathways. Associated with significant morbidity, an important negative impact on the quality of life of patients, and increased health care costs, severe asthma represents a challenge for the clinician. With the introduction of various antibodies that target type 2 inflammation (T2) pathways, severe asthma therapy is gradually moving to a personalized medicine approach. Objective: The purpose of this review was to emphasize the important role of personalized medicine in adult severe asthma management. Methods: An extensive research was conducted in medical literature data bases by applying terms such as "severe asthma" associated with "structured approach," "comorbidities," "biomarkers," "phenotypes/endotypes," and "biologic therapies." Results: The management of severe asthma starts with a structured approach to confirm the diagnosis, assess the adherence to medications and identify confounding factors and comorbidities. The definition of phenotypes or endotypes (phenotypes defined by mechanisms and identified through biomarkers) is an important step toward the use of personalized medicine in asthma. Severe allergic and nonallergic eosinophilic asthma are two defined T2 phenotypes for which there are efficacious targeted biologic therapies currently available. Non-T2 phenotype remains to be characterized, and less efficient target therapy exists. Conclusion: Despite important progress in applying personalized medicine to severe asthma, especially in T2 inflammatory phenotypes, future research is needed to find valid biomarkers predictive for the response to available biologic therapies to develop more effective therapies in non-T2 phenotype.

Obesity-associated asthma in childhood

Obesity and bronchial asthma are very common diseases in children and adolescents, associated with a considerable burden of disease, reduced quality of life and comorbidities. Obesity is a significant risk factor for bronchial asthma. On the one hand, obesity leads to changes in the mechanics and function of the lungs and chest. On the other hand, obesity-associated inflammatory processes with increased production of leptin and cytokines may trigger bronchial inflammation with the appearance of asthmatic symptoms. The diseases are also linked by genetic factors. Physical activity and weight reduction have a significant benefit. Pharmacotherapy must be based on the pattern of inflammation. This article summarizes the current state of the literature on the association of asthma and obesity and presents current and possible future treatment options.

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.