[Clinical relevance of distal airway involvement in asthma]

Small Airway Dysfunction in Children With Controlled Asthma

INTRODUCTION

Asthma is characterized by chronic inflammation of the central and distal airways. The aim of this study was to assess the small airway (SA) of children with moderate-severe asthma with normal FEV1.

METHODS

This was an open-label, prospective, observational, cross-sectional study with consecutive inclusion of patients with moderate-severe asthma, receiving standard clinical treatment, with normal baseline FEV₁. We determined multiflow FEno (CAno), oscillatory resistance and reactance (R5-R20, X5), forced spirometry (FEV1, FEF_25-75), total body plethysmography (RV/TLC) and bronchodilation test. SA involvement was defined as: CAno>4.5 ppb, R5-R20>0.147kPa/L/s, X5<-0.18kPa/L, FEF_25-75<-1.65 z-score, RV/TLC>33%. Poor asthma control was defined as ≤ 19 points on the ACT questionnaire or ≤ 20 on the c-ACT.

RESULTS

In a cohort of 100 cases, 76 had moderate asthma and 24 had severe asthma; 71 children were classified as poorly controlled and 29 were well-controlled. In total, 77.78% of the group with all the correct determinations (n=72) showed ≥ 1 altered SA parameter and 48.61% ≥ 2 parameters. There were no differences between well-controlled or poorly controlled cases.

CONCLUSIONS

Children with moderate-severe asthma, with normal FEV₁, show a phenotype of dysfunctional SA. In our series, the evaluation of SA using the techniques described above did not provide information on disease control.

Y-27632 is associated with corticosteroid-potentiated control of pulmonary remodeling and inflammation in guinea pigs with chronic allergic inflammation

Background

Previously, we showed that treatment with the Rho-kinase inhibitor Y-27632 was able to control airway responsiveness, inflammation, remodeling, and oxidative stress in an animal model of asthma, suggesting that this drug is beneficial in asthma. However, studies evaluating the effects of these inhibitors in conjunction with corticosteroids on chronic pulmonary inflammation have not been conducted. Therefore, we evaluated the effects of treatment with the Rho-kinase inhibitor Y-27632, with or without concurrent dexamethasone treatment, on airway and lung tissue mechanical responses, inflammation, extracellular matrix remodeling, and oxidative stress in guinea pigs with chronic allergic inflammation.

Methods

The guinea pigs were subjected to seven ovalbumin or saline inhalation exposures. Treatment with Y-27632 (1 mM) and dexamethasone (2 mg/kg) started at the fifth inhalation. Seventy-two hours after the seventh inhalation, the pulmonary mechanics were evaluated and exhaled nitric oxide (E_NO) levels were determined. The lungs were removed and histological analysis was performed using morphometry.

Results

The treatment of guinea pigs with the Rho-kinase inhibitor and dexamethasone (ORC group) decreased E_NO, the maximal mechanical responses after antigen challenge, inflammation, extracellular matrix remodeling and oxidative stress in the lungs.

This therapeutic strategy reduced the levels of collagen and IFN-γ in the airway walls, as well as IL-2, IFN-γ, 8-iso-PGF2α and NF-κB in the distal parenchyma, when compared to isolated treatment with corticosteroid or Rho-kinase inhibitor (P < 0.05) and reduced the number of TIMP-1-positive cells and eosinophils in the alveolar septa compared to corticosteroid-treated animals (P < 0.05). The combined treatment with the Rho-kinase inhibitor and the corticosteroid provided maximal control over the remodeling response and inflammation in the airways and parenchyma.

Conclusions

Rho-kinase inhibition, alone or in combination with corticosteroids, can be considered a future pharmacological tool for the control of asthma.