Impaired Respiratory System Resistance and Reactance Are Associated With Bronchial Wall Thickening in Persistent Asthma

Chest CT assess the impact of omalizumab treatment on airway remodeling in refractory asthma

BACKGROUND

To evaluate the benefits of omalizumab treatment in patients through real-world follow-up and assess the impact of omalizumab treatment on airway remodeling using chest CT.

METHODS

This is a single-center prospective, observational study included Chinese patients with refractory asthma who received omalizumab treatment from May 2021 to December 2022. We collected real-world clinical data, including their hospitalization information, pulmonary function, FENO, laboratory assessment, ACT scores, chest CT at baseline and every follow-up month. A comparison was made between the pre-treatment and post-treatment laboratory indicators, pulmonary function, airway parameters, and mucous plug scores under chest CT.

RESULTS

This study included a total of 61 patients with refractory asthma treated with omalizumab. The study found that: ①regardless of whether the treatment lasted for a full four months or not, it significantly improved patient asthma control scores and reduced hospitalization costs and length of stay (p<0.05). ②After four months of treatment, pulmonary ventilation function examination revealed significant improvements (p<0.05) in MEF75, MEF50, MEF75/25, PEF, and FEV1/FVC. ③After four months of omalizumab treatment, the ratio of wall thickness and outer radius (T/D) and wall area percentage (WA%) of the bronchial wall decreased significantly (p<0.05). ④After medication, the expression of airway mucous plugs decreased.

CONCLUSIONS

Omalizumab treatment can reduce airway wall thickness, decrease the percentage of airway wall area, and the expression of airway mucous plugs, thereby improving airflow limitation. Utilizing chest CT provides a novel and intuitive assessment of the efficacy of omalizumab treatment.

TRIAL REGISTRATION

This study was registered in Chinese Clinical Trial Registry, the number is ChiCTR2100046343.

Airway Remodeling in Asthma: Mechanisms, Diagnosis, Treatment, and Future Directions

Airway remodeling (AR) with chronic inflammation, are key features in asthma pathogenesis. AR characterized by structural changes in the bronchial wall is associated with a specific asthma phenotype with poor clinical outcomes, impaired lung function and reduced treatment response. Most studies focus on the role of inflammation, while understanding the mechanisms driving AR is crucial for developing disease-modifying therapeutic strategies. This review paper summarizes current knowledge on the mechanisms underlying AR, diagnostic tools, and therapeutic approaches. Mechanisms explored include the role of the resident cells and the inflammatory cascade in AR. Diagnostic methods such as bronchial biopsy, lung function testing, imaging, and possible biomarkers are described. The effectiveness on AR of different treatments of asthma including corticosteroids, leukotriene modifiers, bronchodilators, macrolides, biologics, and bronchial thermoplasty is discussed, as well as other possible therapeutic options. AR poses a significant challenge in asthma management, contributing to disease severity and treatment resistance. Current therapeutic approaches target mostly airway inflammation rather than smooth muscle cell dysfunction and showed limited benefits on AR. Future research should focus more on investigating the mechanisms involved in AR to identify novel therapeutic targets and to develop new effective treatments able to prevent irreversible structural changes and improve long-term asthma outcomes.

Lower skeletal muscle density and airway structure on computed tomography in asthma

BACKGROUND

Lower skeletal muscle density may reflect muscle adiposity and metabolic dysregulation that potentially impair disease control and lung function independent of high body mass index (BMI) in patients with asthma.

OBJECTIVE

To investigate whether the lower density of pectoralis muscles (PMs) and erector spinae muscles (ESMs) on chest computed tomography was associated with airway structural changes in patients with asthma.

METHODS

Consecutive patients with asthma and healthy controls undergoing chest computed tomography were retrospectively analyzed. The ESM and PM density, areas of subcutaneous adipose tissue near the PM and epicardial adipose tissue, wall area percent of the airways, and airway fractal dimension (AFD) were quantified on computed tomography.

RESULTS

The study included 179 patients with asthma (52% women) and 88 controls (47% women). All the controls were 60 years old or younger. The PM and ESM density in female patients with asthma who were 60 years old or younger were significantly lower than those in controls after adjustment for BMI. In female patients with asthma at all ages, lower PM and ESM density (but not subcutaneous or epicardial adipose tissue area) was associated with greater wall area percent of the airways and lower AFD after adjusting for age, height, BMI, smoking status, blood eosinophil count, and oral corticosteroid use. The only association between ESM density and AFD was found in male patients with asthma.

CONCLUSION

Lower skeletal muscle density may be associated with airway wall thickening and less complexity of the airway luminal tree in female patients with asthma.

The New Paradigm: The Role of Proteins and Triggers in the Evolution of Allergic Asthma

Epithelial barrier damage plays a central role in the development and maintenance of allergic inflammation. Rises in the epithelial barrier permeability of airways alter tissue homeostasis and allow the penetration of allergens and other external agents. Different factors contribute to barrier impairment, such as eosinophilic infiltration and allergen protease action-eosinophilic cationic proteins' effects and allergens' proteolytic activity both contribute significantly to epithelial damage. In the airways, allergen proteases degrade the epithelial junctional proteins, allowing allergen penetration and its uptake by dendritic cells. This increase in allergen-immune system interaction induces the release of alarmins and the activation of type 2 inflammatory pathways, causing or worsening the main symptoms at the skin, bowel, and respiratory levels. We aim to highlight the molecular mechanisms underlying allergenic protease-induced epithelial barrier damage and the role of immune response in allergic asthma onset, maintenance, and progression. Moreover, we will explore potential clinical and radiological biomarkers of airway remodeling in allergic asthma patients.

The role of oscillometry in asthma

PURPOSE OF REVIEW

Oscillometry is a noninvasive pulmonary function test that has gained significant interest in the evaluation of lung disease. Currently, oscillometry is primarily a research tool, but there is a growing body of evidence supporting its clinical use. This review describes the recent work evaluating the role of oscillometry in the diagnosis and treatment of asthma.

RECENT FINDINGS

A large body of observational data supports the ability of oscillometry to distinguish healthy individuals from those with respiratory symptoms or lung disease. Oscillometry may not be as useful as an isolated diagnostic test in asthma, but the combination with other pulmonary function tests may improve its diagnostic ability. Oscillometry can detect peripheral airways dysfunction in asthma, which is associated with symptoms and the risk for exacerbations. To help guide future research, minimal clinically important differences for specific oscillometry variables have been developed. Oscillometry may be useful in monitoring the response to biological therapy and has potential for personalizing treatment for individual patients. Oscillometry also has potential in uncovering unique aspects of the pathophysiology of asthma in obesity.

SUMMARY

Oscillometry is a promising tool in the diagnosis and management of asthma. More research is needed to support its routine clinical use.

Clinical impact of obesity on oscillometry lung mechanics in adults with asthma

BACKGROUND

In the year 2035, projections have estimated that 5% of the Scottish population will be morbidly obese defined as a body mass index (BMI) greater than or equal to 40 kg/m2. Airway oscillometry is an effort-independent test akin to bronchial sonar which measures resistance and compliance.

OBJECTIVE

To evaluate the impact of obesity on lung mechanics using oscillometry.

METHODS

Clinical data for 188 patients with respiratory physician-diagnosed moderate-to-severe asthma were retrospectively collected and analyzed.

RESULTS

Obesity (BMI 30-39.9 kg/m2) and morbid obesity (BMI ≥ 40 kg/m2) were associated with a significantly worse heterogeneity of peripheral resistance between 5 Hz and 20 Hz and peripheral compliance as low-frequency reactance at 5 Hz and area under the reactance curve, as compared with normal weight (BMI 18.5-24.9 kg/m2). Cluster analysis incorporating oscillometry identified a patient cohort who was older, obese, and female with combined impairment of spirometry and oscillometry coupled with more frequent severe exacerbations.

CONCLUSION

Obesity is associated with worse peripheral airway dysfunction in moderate-to-severe asthma, including a patient cluster who was older, obese, and female with more frequent exacerbations.