Bronchiectasis in severe asthma is associated with eosinophilic airway inflammation and activation

Asthma and respiratory comorbidities

Asthma is a common respiratory condition with various phenotypes, nonspecific symptoms, and variable clinical course. The occurrence of other respiratory conditions with asthma, or respiratory comorbidities (RCs), is not unusual. A literature search of PubMed was performed for asthma and a variety of respiratory comorbidities for the years 2019 to 2024. The 5 conditions with the largest number of references, other than rhinitis and rhinosinusitis (addressed elsewhere), or that are the most problematic in the authors' clinical experience, are summarized. Others are briefly discussed. The diagnosis and treatment of both asthma and RCs are complicated by the overlap of symptoms and signs. Recognizing RCs is especially problematic in adult-onset, non-type 2 asthma because there are no biomarkers to assist in confirming non-type 2 asthma. Treatment decisions in subjects with suspected asthma and RCs are complicated by the potential similarities between the symptoms or signs of the RC and asthma, the absence of a sine quo non for the diagnosis of asthma, the likelihood that many RCs improve with systemic corticosteroid therapy, and the possibility that manifestations of the RCs are misattributed to asthma or vice versa. Recognition of RCs is critical to the effective management of asthma, particularly severe or difficult-to-treat asthma.

Rethinking bronchiectasis as an inflammatory disease

Bronchiectasis is understood to be the result of a complex interaction between infection, impaired mucociliary clearance, inflammation, and lung damage. Current therapeutic approaches to bronchiectasis are heavily focused on management of infection along with enhancing mucus clearance. Long-term antibiotics have had limited success in clinical trials, suggesting a need to re-evaluate the concept of bronchiectasis as an infective disorder. We invoke the example of asthma, for which treatment paradigms shifted away from targeting smooth muscle constriction, towards permanently suppressing airway inflammation, reducing risk and ultimately inducing remission with precision anti-inflammatory treatments. In this Review, we argue that bronchiectasis is primarily a chronic inflammatory disease, requiring early identification of at-risk individuals, and we introduce a novel concept of disease activity with important implications for clinical practice and future research. A new generation of novel anti-inflammatory treatments are under development and repurposing of anti-inflammatory agents from other diseases could revolutionise patient care.

Daphnetin alleviates allergic airway inflammation by inhibiting T-cell activation and subsequent JAK/STAT6 signaling

Allergic asthma is a major health burden on society as a chronic respiratory disease characterized by inflammation and muscle tightening around the airways in response to inhaled allergens. Daphne kiusiana Miquel is a medicinal plant that can suppress allergic airway inflammation; however, its specific molecular mechanisms of action are unclear. In this study, we aimed to elucidate the mechanisms by which D. kiusiana inhibits allergic airway inflammation. We evaluated the anti-inflammatory effects of the ethyl acetate (EA) fraction of D. kiusiana and its major compound, daphnetin, on murine T lymphocyte EL4 cells stimulated with phorbol 12-myristate 13-acetate and ionomycin in vitro and on asthmatic mice stimulated with ovalbumin in vivo. The EA fraction and daphnetin inhibited T-helper type 2 (Th2) cytokine secretion, serum immunoglobulin E production, mucus secretion, and inflammatory cell recruitment in vivo. In vitro, daphnetin suppressed intracellular Ca2+ mobilization (a critical regulator of nuclear factor of activated T cells) and functions of the activator protein 1 transcription factor to reduce interleukin (IL)-4 and IL-13 expression. Daphnetin effectively suppressed the IL-4/-13-induced activation of Janus kinase (JAK)/signal transducer and activator of transcription 6 (STAT6) signaling in vitro and in vivo, thereby inhibiting the expression of GATA3 and PDEF, two STAT6-target genes responsible for producing Th2 cytokines and mucins. These findings indicate that daphnetin suppresses allergic airway inflammation by stabilizing intracellular Ca2+ levels and subsequently inactivating the JAK/STAT6/GATA3/PDEF pathway, suggesting that daphnetin is a promising alternative to existing asthma treatments.

Eosinophilic Bronchiectasis: Prevalence, Severity, and Associated Features-A Cohort Study

Background: Bronchiectasis (BE) has been traditionally associated with neutrophilic inflammation, but eosinophilic bronchiectasis (EB) has recently emerged. Data about prevalence, clinical features, and disease severity are lacking. This study aimed to assess the EB prevalence, compare EB with non-EB, evaluate the Type-2 (T2) high endotype in BE (T2-high EB) versus non-T2-high EB, and identify EB predictors. Methods: We conducted a prospective study involving 153 BE patients. The data collected included clinical, radiological, and microbiological findings. BE severity was assessed using the bronchiectasis severity index (BSI), FACED and E-FACED scores, and the bronchiectasis etiology and comorbidity index (BACI). EB was defined as a blood eosinophil count (BEC) ≥ 300 cells/μL, and T2-high EB as BEC ≥ 300 cells/μL with fractional exhaled nitric oxide (FeNO) ≥ 25 ppb. Results: Prevalence was 27% for EB and 20% for T2-high EB. EB patients exhibited poorer lung function and more severe radiologic features, with significantly higher severity scores [BSI, FACED, E-FACED, BACI (p < 0.05)], and a higher median exacerbation rate [4 (2-5) in EB vs. 2 (1-4) in non-EB, p = 0.0002], compared with non-EB patients. T2-high EB patients showed higher severity scores [BSI, FACED, E-FACED (p < 0.05)], as well as worse lung function parameters [FEV1%, FVC%, FEF 25-75% (p < 0.05)] compared with non-T2-high EB patients. In our study, patients with EB exhibited notably worsened lung function and higher BE severity scores compared with their non-EB counterparts, with exacerbations playing a major role in these differences. We found statistically significant positive correlations between BEC and disease severity scores, such as BSI, FACED, and mMRC, as well as an inverse relationship with pulmonary function. The likelihood of EB being present was significantly higher in association with mMRC ≥ 1 (OR = 2.53; 95% CI, 1.26-5.64), exacerbations/year ≥ 1 (OR = 1.27; 95% CI, 1.0-1.63), and chronic PA colonization (OR = 3.9; 95% CI, 1.08-15.8). Conclusions: EB is a distinct endotype. Dyspnea, exacerbations, and PA colonization may be predictive of EB, emphasizing the importance of early detection for improved outcomes. BEC could serve as a useful biomarker of disease severity to consider when diagnosing EB.

Type-2 severe asthma comorbidities in the era of biologics: time to rethink clinical response?

INTRODUCTION

The use of monoclonal antibodies in patients with severe asthma has led clinicians to explore new levels of clinical improvement, as testified by the growing interest on clinical remission achievement. In this context, a major role is played by asthma-related comorbidities, which can influence asthma pathophysiology and treatment response.

AREAS COVERED

In this special report, we highlighted how asthma-related comorbidities could deeply affect monoclonal antibody response as well as clinical remission achievement. As examples, we provided data from clinical trials and real-life experiences involving patients with severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), eosinophilic granulomatosis with polyangiitis (EGPA) or bronchiectasis.

EXPERT OPINION

Comorbidities associated with severe asthma development should be carefully assessed in everyday clinical practice, even with the help of new diagnostic technologies, artificial intelligence and multidisciplinary teams. Future studies should address the role of comorbidities in remission achievement, describing how these diseases could generate new trajectories of clinical and functional response in patient treated with monoclonal antibodies.

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.

Management of comorbidities in difficult and severe asthma

Difficult-to-treat and severe asthma are challenging clinical entities. In the face of suboptimal asthma control, the temptation for clinicians is to reflexively escalate asthma-directed therapy, including increasing exposure to corticosteroids and commencement of costly but potent biologic therapies. However, asthma control is objectively and subjectively assessed based on measurable parameters (such as exacerbations or variability in pulmonary physiology), symptoms and patient histories. Crucially, these features can be confounded by common untreated comorbidities, affecting clinicians' assessment of asthma treatment efficacy.