Pretreatment circulating MAIT cells, neutrophils, and periostin predicted the real-world response after 1-year mepolizumab treatment in asthmatics

Elevated mepolizumab levels in patients with severe asthma responsive to 1 year's mepolizumab treatment

Background

Asthma involves variable airflow limitation and persistent airway inflammation. Eosinophilic asthma, characterized by cytokine-mediated type 2 inflammation, is generally treated with inhaled corticosteroids. However, patients with severe asthma may require biologics, such as mepolizumab, which targets IL-5 and can manage uncontrolled eosinophilic asthma.

Objective

We investigated the relationship between serum mepolizumab concentrations and treatment response in patients with severe asthma.

Methods

Patients with mepolizumab-treated severe asthma were enrolled onto this prospective cohort study. Baseline assessments were conducted and repeated at 3, 6, and 12 months. Those with response were categorized on the basis of improvements in asthma control test score, lung function, and asthma exacerbations. We quantified the serum concentration of mepolizumab at 3, 6, and 12 months after treatment by liquid chromatography coupled with tandem mass spectrometry.

Results

Twenty-five adult patients aged 20 years and older with severe asthma were included in the analysis. Serum mepolizumab concentrations significantly increased at 6 and 12 months compared with those at 3 months, particularly in those with disease that responded to therapy. Furthermore, the relative change in mepolizumab concentration was significantly higher in those with response than in those with no response. Body size parameters were negatively correlated with mepolizumab concentration. In those with response, there were inverse correlations between mepolizumab concentration and baseline body size parameters.

Conclusions

The study observed a yearlong increase in mepolizumab concentrations, particularly in those with response, indicating a potential mepolizumab surplus. Correlations between mepolizumab concentrations and baseline characteristics suggested differing mepolizumab requirements between those with response and those with no response. Further research is needed to validate these findings and optimize treatment strategies for patients with severe asthma.

Restoration of IFN-γ-Producing MAIT Cell Correlates to Beneficial Allergen Immunotherapy in Allergic Rhinitis Patients

BACKGROUND

Mucosal-associated invariant T cells (MAIT) are emerging as important regulators at mucosal surfaces. While these cells have been linked to a Th1-biased immune response and support for B cells, their roles in allergic diseases characterised by type 2 inflammation remain elusive. The study seeks to characterise MAIT cells in house dust mite (HDM)-induced allergic rhinitis (AR) and subsequent allergen immunotherapy (AIT), aiming to elucidate their clinical significance in AR and potential to enhance AIT effectiveness.

METHODS

MAIT cells were assessed in patients with AR and individuals undergoing AIT. The ratio and cytokine-producing capacity of these cells were analysed to explore their correlations with AR progression and their responsiveness to HDM extracts and MAIT cell-specific agonists.

RESULTS

In AR patients, there was an increase in the ratios of circulating MAIT cells and tonsil follicular T helper-like MAIT cells, alongside a decrease in the IFN-γ-producing MAIT cells. AIT restored their IFN-γ producing capacity, which was further boosted by T cell receptor (TCR) activation using MAIT cell-specific agonist-loaded artificial antigen-presenting cells (aAPCs). Synergistic effects of aAPCs and HDM enhance MAIT cell activation and IFN-γ production while reducing HDM-induced IgE levels in PBMC cocultures. Moreover, higher ratios of MAIT cells and IFN-γ-producing MAIT cells correlated with decreased IgE and increased IgG4 and improved clinical outcomes during AIT.

CONCLUSIONS

These findings underscore the compromised IFN-γ-producing MAIT cells in AR and their restoration following AIT and TCR stimulation, highlighting the cell's therapeutic potential and predictive value for clinical outcomes in AR and AIT.

Dual role of mucosal-associated invariant T cells (MAIT) in asthma

OBJECTIVE

Mucosal-associated invariant T cells (MAIT) are the predominant type of innate-like T cells in humans, and they represent a unique subset of microbiota-dependent invariant T cells. This Commentary reviews recent clinical studies and animal model research elucidating the multifaceted roles of MAIT cells in asthma.

METHOD

A literature search was performed using PubMed and Google Scholar, and covered the period from 1960 to 2024. The search yielded more than 50 articles, and only essential original research articles and selected review articles were evaluated.

RESULTS

Recent studies indicate that MAIT cell-derived effector molecules may play dual roles in asthma and allergic airway inflammation. While MAIT cells can produce the anti-inflammatory enzyme IL4I1 and the Th1 cytokine IFN-γ to repress allergic airway inflammation and airway hyperresponsiveness (AHR), they may also secrete IL-17. Which induces neutrophil infiltration and exacerbates AHR. In addition, some clinical studies from the literature search revealed a negative association between MAIT cell abundance and asthma. Regarding allergic airway inflammation, mouse model studies suggested that MAIT cells may play a protective role.

CONCLUSION

These findings raise critical questions as to whether MAIT cells are friend or foe in asthma, and whether distinct subsets of MAIT cells play different roles in allergic airway inflammation. Further studies are needed to better understand the implication of MAIT cells in asthma pathogenesis, particularly in patients with severe asthma.

Evaluating the Diagnostic Value of Lymphocyte Subsets in Bronchoalveolar Lavage Fluid and Peripheral Blood Across Various Diffuse Interstitial Lung Disease Subtypes

Diffuse interstitial lung diseases (ILD) include conditions with identifiable causes such as chronic eosinophilic pneumonia (CEP), sarcoidosis (SAR), chronic hypersensitivity pneumonitis (CHP), and connective tissue disease-associated interstitial pneumonia (CTD), as well as idiopathic interstitial pneumonia (IIP) of unknown origin. In non-IIP diffuse lung diseases, bronchoalveolar lavage (BAL) fluid appearance is diagnostic. This study examines lymphocyte subsets in BAL fluid and peripheral blood of 56 patients with diffuse ILD, excluding idiopathic pulmonary fibrosis (IPF), who underwent BAL for diagnostic purposes. Patients were classified into CEP, SAR, CHP, CTD, and IIP groups, and clinical data, BAL cell analysis, and peripheral blood mononuclear cell analysis were compared. Eosinophils and type 3 innate lymphocytes (ILC3s) were significantly increased in the BAL fluid of the CEP group. Receiver operating characteristic curve analysis identified eosinophils ≥ 8% in BAL cells and ILC3s ≥ 0.0176% in the BAL lymphocyte fraction as thresholds distinguishing CEP. SAR patients exhibited significantly elevated CD4/CD8 ratios in the BAL fluid, with a ratio of 3.95 or higher and type 1 innate lymphoid cell frequency ≥ 0.254% as differentiation markers. High Th1 cell frequency (≥17.4%) in BAL lymphocytes in IIP, elevated serum KL-6 (≥2081 U/mL) and SP-D (≥261 ng/mL) in CHP, and increased BAL neutrophils (≥2.0%) or a low CD4/CD8 ratio (≤1.2) in CTD serve as distinguishing markers for each ILD. Excluding CEP and SAR, CD4+ T cell frequencies, including Th1, Th17, and Treg cells in peripheral blood, may differentiate IIP, CHP, and CTD.

Interleukin-5 as a pleiotropic cytokine orchestrating airway type 2 inflammation: Effects on and beyond eosinophils

Interleukin (IL)-5 is the key cytokine in the maturation, activation, proliferation, migration and survival of eosinophils, which are key effector cells in many upper and lower airway diseases. Through its effects on eosinophils, IL-5 indirectly contributes to various pathophysiological processes including tissue damage, repair and remodelling. Understanding the importance of IL-5 in eosinophil-associated diseases led to the development of anti-IL-5 therapies, which provide clinical benefits across a range of conditions. However, recent evidence suggests that eosinophil-depletion alone may not account for all of the therapeutic effects of anti-IL-5 therapy and that IL-5 may also contribute to disease independently of its effects on eosinophils. Indeed, evidence from ex vivo studies and targeted therapy in vivo demonstrates that IL-5 and its inhibition affects a much broader range of cells beyond eosinophils, including epithelial cells, plasma cells, mast cells, basophils, neutrophils, type 2 innate lymphoid cells, T regulatory cells and fibroblasts. This review will provide an update on the evidence supporting the breadth of IL-5 biology relevant to disease pathogenesis beyond eosinophil-associated inflammation, where there is a need for additional insight, and the clinical implications of a more central role of IL-5 in type 2 inflammation.

CD69 Signaling in Eosinophils Induces IL-10 Production and Apoptosis via the Erk1/2 and JNK Pathways, Respectively

INTRODUCTION

Eosinophils contribute to the pathogenesis of allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis. We previously reported that human tissue eosinophils have high CD69 expression compared to blood eosinophils, and its expression is correlated with disease severity and the number of infiltrated eosinophils. However, biological CD69 signaling activity in eosinophils remains unclear.

METHODS

CD69 expression on lung tissue eosinophils obtained from mice with ovalbumin-induced asthma was measured using flow cytometry. CD69 crosslinking was performed on eosinophils purified from the spleen of IL-5 transgenic mice to investigate CD69 signaling and its function in eosinophils. Then, qPCR, Western blot, enzyme-linked immunosorbent assay, and survival assay results were analyzed.

RESULTS

Surface CD69 expression on lung tissue eosinophils in the asthma mice model was 2.91% ± 0.76%, whereas no expression was detected in the healthy group. CD69-expressed eosinophils intrinsically have an upregulation of IL-10 mRNA expression. Moreover, CD69 crosslinking induced further pronounced IL-10 production and apoptosis; these responses were mediated via the Erk1/2 and JNK pathways, respectively.

CONCLUSIONS

Our results suggested that CD69+ eosinophils play an immunoregulator role in type 2 inflammation, whereas activated tissue eosinophils contribute to the pathogenesis of asthma.

Potential of MAIT cells to modulate asthma

Despite recent advances in asthma treatments, the search for novel therapies remains necessary because there are still patients with recurrent asthma exacerbations and poor responses to the existing treatments. Since group 2 innate lymphoid cells (ILC2) play a pivotal role in asthma by triggering and exacerbating type 2 inflammation, controlling ILC2s function is key to combating severe asthma. Mucosal-associated invariant T (MAIT) cells are innate-like T cells abundant in humans and are activated both in a T cell receptor-dependent and -independent manner. MAIT cells are composed of MAIT1 and MAIT17 based on the expression of transcription factors T-bet and RORγt, respectively. MAIT cells play pivotal roles in host defense against pathogens and in tissue repair and are essential for the maintenance of immunity and hemostasis. Our recent studies revealed that MAIT cells inhibit both ILC2 proliferation and functions in a mouse model of airway inflammation. MAIT cells may alleviate airway inflammation in two ways, by promoting airway epithelial cell barrier repair and by repressing ILC2s. Therefore, reagents that promote MAIT cell-mediated suppression of ILC2 proliferation and function, or designer MAIT cells (genetically engineered to suppress ILC2s or promote repair of airway damage), may be effective therapeutic agents for severe asthma.