Airway eosinophilic inflammation, epithelial damage, and bronchial hyperresponsiveness in patients with mild-moderate, stable asthma

Serum Levels of Epithelial-Derived Cytokines as Interleukin-25 and Thymic Stromal Lymphopoietin after a Single Dose of Mepolizumab in Patients with Severe Non-Allergic Eosinophilic Asthma: A Short Report

The bronchial epithelium has continuous contact with environmental agents initiating and maintaining airway type 2 inflammation in asthma. However, there is a lack of data on whether reduced airway eosinophilic inflammation can affect the production of epithelial-derived mediators, such as interleukin-25 (IL-25) and thymic stromal lymphopoietin (TSLP). The aim of this study was to investigate the changes in serum levels of IL-25 and TSLP after a single dose of mepolizumab, a humanized monoclonal antibody to interleukin-5 (IL-5), in patients with severe non-allergic eosinophilic asthma (SNEA). We examined 9 SNEA patients before and four weeks after administration of 100 mg mepolizumab subcutaneously. The fractional exhaled nitric oxide (FeNO) level was analysed using an electrochemical assay (NIOX VERO®, Circassia, UK). Serum IL-25 and TSLP levels were measured by ELISA. Four weeks after the single dose of mepolizumab, blood eosinophil count significantly decreased from 0.55 ± 0.20 × 109/l to 0.14 ± 0.04 × 109/l (p = 0.01) and FEV1 increased from 2.1 ± 0.5 l (65.4 ± 8.8% of predicted) to 2.6 ± 0.4 l (76.4 ± 9.1% of predicted) (p = 0.04), while FeNO level has not changed (32.3 ± 8.4 vs 42.9 ± 12.6 ppb). Serum IL-25 level significantly decreased from 48.0 ± 17.2 pg/mL to 34.8 ± 17.1 pg/mL (p = 0.02) with same tendency in TSLP level: from 359.8 ± 71.3 pg/mL to 275.6 ± 47.8 pg/mL (p = 0.02). It has also been noticed a significant relation between changes in the blood eosinophil count and serum IL-25 level (r = 0.81, p = 0.008), as well as between changes in serum IL-25 and TSLP levels (r = 0.93, p = 0.004) after a single dose of mepolizumab. Thus, anti-IL-5 treatment with mepolizumab might diminish the production of bronchial epithelial-derived cytokines IL-25 and TSLP in patients with SNEA which is potentially related to reduced eosinophilic inflammation. This trial is registered in ClinicalTrial.gov with identifier NCT03388359.

A Review of Three New Anti-interleukin-5 Monoclonal Antibody Therapies for Severe Asthma

Asthma is a chronic respiratory condition that is characterized by reversible airflow obstruction. Interleukin-5 (IL-5) is involved in the pathophysiology of the disease and drugs targeting IL-5 have been studied for years as a possible treatment option for severe asthma. In this review, the authors searched PubMed for major drug therapies and clinical trials against IL-5. A total of 29 articles met the criteria for selection and were shortlisted; of these, 10 papers were on benralizumab, 14 on mepolizumab, and five on reslizumab. The three drugs proved to be safe and efficacious for patients with severe asthma, leading to decreased rates of asthma exacerbations, lowered levels of eosinophils, and improved pulmonary functions in various studies. Patients also reported an improvement in the quality of life. The side effects of these three drugs were mild and no deaths directly linked to the drug were reported. However, longer duration studies are required to draw firm and strong conclusions on the safety of these therapeutic agents.

The Role of the T lymphocytes and Remodeling in Asthma

In allergic asthma (AA), inflammatory changes in the airway epithelium may contribute to the characteristic pathophysiology and symptoms. The presence of T lymphocytes, eosinophils, mast cells and macrophages, the presence of cytokines, and also structural changes in the airway mucous membrane are characteristic for asthma. Bronchial biopsy specimens were obtained from 33 AA, 25 nonallergic asthma (NAA), and 20 healthy controls (HC). This study used immunohistochemical techniques for identified monoclonal antibodies (CD3, CD4, CD8, CD25, ECP, MBP, tenascin, and laminin) in the bronchi. The highest number of eosinophils and T lymphocyte cells in bronchial biopsies was found in AA, and NAA. The number of T lymphocytes in AA was significantly higher than in NAA and HC. The degree of epithelial damage was higher in the AA group compared to the other groups. The tenascin- and laminin-positive layers in AA were thicker than other groups. In AA, a significant negative correlation was found between epithelial integrity and the count for eosinophils or T lymphocytes. T lymphocytes and eosinophils in AA were found in the area of epithelial and lamina propria damage. This article suggests that T lymphocytes may not only contribute to the chronic airway inflammatory response, airway remodeling, and symptomatology but may also have a central role at the initiation of the allergic immune response. Th-targeted therapy would be of considerable interest in controlling AA. Having more knowledge on the roles of T lymphocytes in the pathogenesis of allergic inflammation highlights the contributions of these cells in regulating and may lead to a new therapeutic target-AA.

Eight-year follow-up of airway hyperresponsiveness in patients with primary Sjögren's syndrome

OBJECTIVE

To evaluate in a longitudinal study the influence of airway hyperresponsiveness (AHR) on lung function in patients with primary Sjögren's syndrome (pSS).

METHODS

Lung function was studied over an eight-year period in 15 patients who fulfilled the Copenhagen criteria for primary Sjögren's syndrome and who were covered in our earlier published study on AHR in patients with Sjögren's syndrome. Standard spirometry and measurements of lung volumes, diffusing capacity (DLCO), and AHR to methacholine were performed.

RESULTS

A significant decline over time was found in total lung capacity (TLC), vital capacity (VC), forced vital capacity (FVC), functional residual capacity (FRC), and expiratory midflows (FEF₅₀). A sign of small airway obstruction (decrease in FEF₅₀) at entry correlated with VC at follow-up (r = .8, P < .003), and the individual change in FEF₅₀ during the observation period correlated with the individual change in VC (r = .6, P < .05). Six patients had increased AHR, and three of them had decreased DLCO. Six of the patients progressively reduced DLCO over time, and five of them had spirometric signs of increased small airway obstruction.

CONCLUSIONS

During this eight-year follow-up we observed that one-third of the patients with pSS developed a significant reduction in lung function. Our findings suggest that small airways obstruction and AHR are associated with reduction of VC and development of impaired DLCO as a sign of interstitial lung disease in this group of patients.

Serial Changes in Serum Eosinophil-associated Mediators between Atopic and Non-atopic Children after Mycoplasma pneumoniae pneumonia

Purpose

Mycoplasma pneumoniae pneumonia (MP) is associated with the exacerbation, timing, and onset of asthma. The goal of this study was to elucidate the impact of MP on eosinophil-related hyper-reactive amplification in atopic children.

Methods

We studied 48 patients with MP (26 atopic, 22 non-atopic), between 3 and 12 years of age. Serial changes in blood eosinophil counts, serum interleukin-5 (IL-5), and serum eosinophil cationic protein (ECP) levels were measured in atopic and non-atopic children with MP upon admission, recovery, and at 2 months post-recovery. Serum IL-5 and ECP levels were measured by enzyme-linked immunosorbent assays; eosinophil counts were measured using an autoanalyzer.

Results

Serial changes in serum IL-5, ECP, and total eosinophil counts were significantly higher in atopic patients, relative to non-atopic controls (P≤0.001). Serum IL-5 and ECP levels were significantly higher in atopic patients at all three time points tested, while eosinophil counts were higher in the clinical recovery and follow-up phases, but not in the acute phase. Furthermore, among atopic patients, serum ECP levels were significantly higher in the recovery and follow-up phases than in the acute phase.

Conclusions

The present study demonstrated significant differences in eosinophil counts, serum IL-5, and serum ECP levels between atopic and non-atopic children with MP at admission, recovery, and 2 months after clinical recovery. These outcomes are suggestive of eosinophil-related hyperreactivity in atopic children, with this status maintained for at least 2 months after MP.

Rationale and clinical results of inhibiting interleukin-5 for the treatment of severe asthma

Severe asthma is responsible for considerable morbidity and a high proportion of the healthcare costs attributable to asthma. Management is not straightforward as the clinical, pathological and physiological features are heterogeneous and the relationships between these features are poorly understood. In recent years significant progress has been made in understanding this heterogeneity and eosinophilic asthma has emerged as a potentially clinically important phenotype because treatment with monoclonal antibodies against IL-5 is effective. This has required a change in our understanding of the role of eosinophilic airway inflammation in airways disease and the developments of reliable biomarkers of eosinophilic airway inflammation. We will review these developments and describe the clinical experience so far with treatment with monoclonal antibiotics against IL-5.

Th2 cytokines IL-4 and IL-13 downregulate paxillin expression in bronchial airway epithelial cells

Asthma is characterized by infiltration and shedding of the bronchial epithelium. The Th2 cytokines IL-4 and IL-13 are involved in the cellular recruitment and infiltration seen in asthma. The effects of IL-4 and IL-13 on cell-matrix interactions and epithelial shedding are unknown. We hypothesize that bronchial airway epithelial cells (BAEC) express paxillin, a structural focal adhesion protein, and downregulation of paxillin by Th2 cytokines lead to BAEC hyperpermeability. We showed by confocal microscopy the presence of paxillin in BAEC. We demonstrated by Western blot analysis that IL-4 and IL-13 stimulation results in downregulation of paxillin production. IL-4 and IL-13 stimulation decreased epithelial cell-matrix attachment as measured by electrical cell-substrate impedance sensing system (ECIS). Our results suggest that Th2 cytokines IL-4 and IL-13 downregulate paxillin production by BAEC, thereby disrupting the cell-matrix interactions. This may help explain the epithelial shedding and epithelial membrane hyperpermeability that occurs in asthma.

Exhaled nitric oxide levels in non-allergic and allergic mono- or polysensitised children with asthma

BACKGROUND

Increased fractional exhaled NO concentrations (FENO) and blood/tissue eosinophilia are frequently reported in allergic children with mild asthma and are thought to reflect the intensity of the inflammation characterising the disease. The aim of this study was to investigate possible differences in FENO levels or in the intensity of the blood eosinophilia in allergic and non-allergic asthmatic children.

METHODS

112 children with stable, mild, intermittent asthma with a positive bronchial challenge to methacholine were consecutively enrolled in the study; 56 were skin prick test and RAST negative (non-sensitised) while 56 were sensitised to house dust mites (23 only to house dust mites (monosensitised) and 33 were sensitised to mites and at least another class of allergens (pollens, pet danders, or moulds)). Nineteen sex and age matched healthy children formed a control group.

RESULTS

Compared with non-allergic patients, allergic children had a significantly higher rate of blood eosinophilia (p=0.0001) with no differences between mono- and polysensitised individuals. Forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75%)), and the degree of bronchial reactivity to methacholine were similar in non-atopic and atopic children, with no differences between mono- and polysensitised individuals. FENO levels measured by chemiluminescence analyser were higher in asthmatic children (15.9 (14.3) ppb) than in the control group (7.6 (1.6) ppb, p=0.04) and higher in allergic patients (23.9 (2.1) ppb) than in non-allergic patients (7.9 (0.8) ppb, p=0.0001), but there were no differences between mono- and polysensitised individuals (p>0.1). Significant correlations between blood eosinophilia and FENO levels were seen only in allergic (r=0.35, p<0.01) and in polysensitised individuals (r=0.45, p<0.05).

CONCLUSIONS

In children with mild asthma, a similar degree of functional disease severity may be associated with a higher inflammatory component in allergic than in non-allergic subjects.

Inflammatory patterns of allergic and nonallergic rhinitis

Rhinitis is a chronic condition of the nasal mucosa that affects a large segment of the population. The symptoms of rhinitis occur in a variety of sinonasal conditions, which may be broadly classified as allergic (seasonal or perennial) or nonallergic (infectious or a number of noninfectious etiologies) based on the presence or absence of atopy. The cytokine profile and inflammatory patterns underlying these two conditions vary because of certain differences in their pathophysiology as discussed in this review.

Dissociation between exhaled nitric oxide and hyperresponsiveness in children with mild intermittent asthma

BACKGROUND

Bronchial hyperresponsiveness and airway inflammation are distinctive features of asthma. Evaluation of nitric oxide (NO) levels in expired air have been proposed as a reliable method for assessing the airway inflammatory events in asthmatic subjects. A study was undertaken to evaluate whether airway hyperresponsiveness is related to levels of exhaled NO.

METHODS

Thirty two steroid-naive atopic children with mild intermittent asthma of mean (SD) age 11.8 (2.3) years and 28 age matched healthy controls were studied to investigate whether baseline lung function or airway hyperresponsiveness is related to levels of exhaled NO. Airway responsiveness was assessed as the dose of methacholine causing a 20% decrease in forced expiratory volume in one second (FEV(1)) from control (PD(20) methacholine) and exhaled NO levels were measured by chemiluminescence analysis of exhaled air.

RESULTS

At baseline asthmatic children had significantly higher NO levels than controls (mean difference 25.87 ppb (95% CI 18.91 to 32.83); p<0.0001) but there were no significant differences in lung function parameters (forced vital capacity (FVC), FEV(1) (% pred), and forced expiratory flows at 25-75% of vital capacity (FEF(25-75%))). In the asthmatic group exhaled NO levels were not significantly correlated with baseline lung function values or PD(20) methacholine.

CONCLUSIONS

These results suggest that levels of exhaled NO are not accurate predictors of the degree of airway responsiveness to inhaled methacholine in children with mild intermittent asthma.