[Chronic obstructive pulmonary disease. A chronic inflammatory disease]

Chronic Obstructive Pulmonary Disease (COPD) is a disease caused by a chronic inflammatory response induced by the inhalation of cigarette smoke or toxic particles/gases in the airways. However, we actually know that COPD is a disease that does not only induce inflammation in lung parenchyma and bronchi, but also provokes systemic inflammation which plays a role in multiple comorbidities. Thereby, treatment of COPD should not only focus on the bronchi to relieve symptoms, improve respiratory function and reduce the rate of exacerbations, but must also be extended to the systemic effects of the disease.

[Asthma in clinical practice: from inflammatory phenotypes to personalized treatment]

Asthma is a chronic inflammatory disease of the airways. Classification of asthma in different phenotypes has therapeutic implications and may lead to personalized medicine. Induced sputum is the gold standard for asthma phenotyping but is complex, time-consuming and not widely available. The combination of different biomarkers such as exhaled nitric oxide, blood eosinophils and total serum IgE levels allows the prediction of inflammatory phenotype in 58% of asthmatic patients when sputum is not available. We recently demonstrated the interest of measuring volatile organic compounds in exhaled breath to phenotype asthma. These compounds could play an important role in the future to predict the response to expensive biologicals available in severe asthma to reduce exacerbations and the use of systemic corticosteroids.

[Probiotics in asthma treatment]

Asthma is the most prevalent chronic inflammatory airway disease worldwide. The gut microbiota possesses an important link with the development of the immunity in youth and a dysregulation of the gut flora was implicated in the asthmatic disease emergence. Moreover, a dysregulation of the intestinal microbiota exists in asthmatic individual. Probiotics are micro-organisms that can regulate our microbiome conferring potential beneficial effects on health. Thereby, their use in asthma prevention and treatment is attractive and could lead to new therapeutic perspectives. Indeed, they are well tolerated and safe and possess anti-inflammatory and immunoregulatory properties. This article is intended to update the current state of knowledge regarding the use of probiotics in the context of asthma.

[Idiopathic pulmonary fibrosis : from biomarkers to new therapeutic areas]

Pulmonary fibrosis is a pathological entity still too little understood today, burdened with significant morbidity and mortality. Idiopathic pulmonary fibrosis is a complex diagnostic disease requiring a multidisciplinary approach and in some cases the performance of a lung biopsy. In addition, the early identification of the pathology remains the key in order to preserve lung function as much as possible. In this context and in view of the diagnostic difficulty, it seems essential to identify new biomarkers to help with the differential diagnosis, the evaluation of the prognosis and the response to treatment. In addition, the evolution of the pathology remaining inexorable despite anti-fibrotic treatments, it appears critical to be able to identify new potential therapeutic routes.

Sputum IL-25, IL-33 and TSLP, IL-23 and IL-36 in airway obstructive diseases. Reduced levels of IL-36 in eosinophilic phenotype

INTRODUCTION

Alarmins ((IL-25, IL-33 and thymic stromal lymphopoietin (TSLP)) are known to promote Th2 inflammation and could be associated with eosinophilic airway infiltration. They may also play a role in airway remodeling in chronic airway obstructive diseases such as asthma and chronic obstructive pulmonary disease (COPD). IL-23 and IL-36 were shown to mediate the neutrophilic airway inflammation as seen in chronic airway obstructive diseases.

OBJECTIVES

The purpose of this project was to determine the expression and the production of these cytokines from induced sputum (IS) in patients with chronic airway obstructive diseases including asthmatics and COPD. The relationship of the mediators with sputum inflammatory cellular profile and the severity of airway obstruction was assessed.

METHODS

The alarmins (IL-25, IL-33 and TSLP) as well as IL-23 and IL-36 concentrations were measured in IS from 24 asthmatics and 20 COPD patients compared to 25 healthy volunteers. The cytokines were assessed by ELISA in the IS supernatant and by RT-qPCR in the IS cells.

RESULTS

At protein level, no difference was observed between controls and patients suffering from airway obstructive diseases regarding the different mediators. IL-36 protein level was negatively correlated with sputum eosinophil and appeared significantly decreased in patients with an eosinophilic airway inflammation compared to those with a neutrophilic profile and controls. At gene level, only IL-36, IL-23 and TSLP were measurable but none differed between controls and patients with airway obstructive diseases. IL-36 and IL-23 were significantly increased in patients with an neutrophilic inflammatory profile compared to those with an eosinophilic inflammation and were correlated with sputum neutrophil proportions. None of the mediators were linked to airway obstruction.

CONCLUSIONS

The main finding of our study is that patients with eosinophilic airway inflammation exhibited a reduced IL-36 level which could make them more susceptible to airway infections as IL-36 is implicated in antimicrobial defense. This study showed also an implication of IL-36 and IL-23 in airway neutrophilic inflammation in chronic airway obstructive diseases.

Predictors of a good response to inhaled corticosteroids in obesity-associated asthma

INTRODUCTION

Asthma in obese subjects is poorly understood. According to GINA guidelines, pulmonologists increase ICS in case of poor asthma control but lung volume restriction may also worsen respiratory symptoms in obese asthmatics leading to overtreatment in this subpopulation.

METHODS

We conducted a retrospective study on 1217 asthmatics recruited from University Hospital of Liege. 92 patients with a BMI ≥30 came at least two times at the asthma clinic (mean interval: 335 days). In this obese population, we identified predictors of good (decrease in ACQ ≥0.5) versus poor response (rise in ACQ ≥0.5) to ICS step-up therapy.

RESULTS

Obese asthmatics had a poorer asthma control and quality of life as compared to non-obese and exhibited reduced FVC, higher levels of blood leucocytes and markers of systemic inflammation. The proportion of asthma inflammatory phenotypes was similar to that observed in a general population of asthmatics. Among uncontrolled obese asthmatics receiving ICS step-up therapy, 53% improved their asthma control while 31% had a worsening of their asthma. Uncontrolled obese asthmatics showing a good response to increase in ICS had higher ACQ, lower CRP levels, higher sputum eosinophil counts and higher FeNO levels at visit 1. Uncontrolled obese asthmatics that worsened after increasing the dose of ICS had lower FVC, lower sputum eosinophil counts and higher sputum neutrophil counts.

CONCLUSION

We observed poorer asthma control in obese asthmatics despite similar bronchial inflammation. Managing obese asthmatics according to ACQ alone seems to underestimate asthma control and the contribution of restriction to dyspnea. Increasing the dose of ICS in the absence of sputum eosinophilic inflammation or in the presence of restriction or bronchial neutrophilia led to poorer asthma control. In those patients, management of obesity should be the first choice.

Altered epigenetic features in circulating nucleosomes in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disorder of unknown origin with a highly variable and unpredictable clinical course. Polymorphisms and environmentally induced epigenetic variations seem to determine individual susceptibility to the development of lung fibrosis.

METHODS

We have studied circulating epitopes on cell-free nucleosomes (cfnucleosomes) in 50 IPF patients. We have compared untreated IPF (n = 23) with IPF receiving antifibrotic therapy (n = 27) and healthy subjects (HS) (n = 27). We analyzed serum levels of five cfnucleosomes including bound HMGB1 (nucleosomes adducted to high-mobility growth protein B1), mH2A1.1 (nucleosomes containing the histone variant mH2A1.1), 5mC (nucleosomes associated with methylated DNA), and H3K9Ac and H3K27Ac (nucleosomes associated with histone H3 acetylated at lysine 9 or 27 residue).

RESULTS

Our findings showed that serum levels of bound HMGB1, mH2A1.1, 5mC, H3K9Ac, and H3K27Ac were significantly lower in IPF patients than in HS (p < 0.001, p < 0.001, p < 0.01, p < 0.001, and p < 0.0001, respectively). Moreover, we found differences in epigenetic profiles between untreated IPF patients and those receiving anti-fibrotic therapy with mH2A1.1 and 5mC being significantly lower in untreated than in treated patients (p < 0.01 and p < 0.05, respectively). Combination of four cfnucleosomes (HMGB1, 5mC, H3K9Ac, and H3K27Ac) allow to discriminate IPF vs HS with a good coefficient of determination (R² = 0.681). The AUC for the ROC curve computed by this logistic regression was 0.93 (p < 0.001) with 91% sensitivity at 80% specificity.

CONCLUSION

Our observations showed that cfnucleosomes (bound HMGB1, mH2A1.1, 5mC, H3K9Ac, and H3K27Ac) might have potential as biomarkers for diagnosis and treatment response. These results deserve further validation in longitudinal cohorts.

Sputum biomarkers in IPF: Evidence for raised gene expression and protein level of IGFBP-2, IL-8 and MMP-7

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a rare lung disease of unknown origin leading rapidly to death. This paper addresses the issue of whether sputum induction is a suitable tool to study respiratory tract inflammation and potential biomarkers in IPF compared to COPD, a fibrosing airway wall disease.

METHODS

In a cross-sectional analysis, 15 IPF patients, 32 COPD and 30 healthy subjects underwent sputum induction. Total sputum cell counts and the amount of TGF- β, IGF-1, IGF-2, IGFBP-1, IGFBP-2, IGFBP-3, IL-8, IL-13, MMP-7, MMP-9, YKL-40, TNF-α and KL-6 in sputum supernatant were analysed. We also profiled gene expression of cells in the induced sputum for TGF-β, MMP-7, YKL-40, IGFBP-2, IL-6, IL-8 and TNF-α.

RESULTS

IPF patients, like COPD, had increased sputum absolute number of neutrophils, eosinophils, macrophages and epithelial cells compared to HS. IPF sputum supernatants had increased concentrations of IGFBP-2, IL-8, TGF-β, MMP-7, MMP-9 and KL-6 (p<0.05, p<0.0001, p<0.05, p<0.05, p<0.0001, p<0.05 respectively) when compared to healthy subjects where COPD had higher IL-6 and TNF-α levels than IPF (p<0.05 and p<0.05 respectively) and HS (p<0.0001 and p<0.001 respectively) and higher IL-8 and MMP-9 than HS (p<0.0001 and p<0.001 respectively). Conversely to IL-6 and TNF-α, MMP-7 was increased in IPF compared to COPD (p<0.05). The KL-6 and MMP-7 protein levels in sputum were inversely correlated with total lung capacity (TLC, % of predicted) in IPF patients (r = -0.73 and r = -0.53 respectively). Sputum gene expression analysis identified a significant increase for IGFBP-2, IL-6, IL-8 and MMP-7 in IPF compared to HS (p<0.05, p<0.01, p<0.05 and p<0.0001 respectively) and for IGFBP-2, YKL-40, IL-6, IL-8 and MMP-7 compared to COPD (p<0.01, p<0.01, p<0.05, p<0.01 and p<0.0001 respectively). Furthermore, gene expression of TGF-β was increased in IPF compared to COPD (p<0.001) but not to HS.

CONCLUSION

Our data show clear increase in expression and production of IGFBP-2, IL-8 and MMP-7 in sputum from patients with IPF that may contribute to the disease.

Raised interferon-β, type 3 interferon and interferon-stimulated genes - evidence of innate immune activation in neutrophilic asthma

BACKGROUND

Interferons play an important role in innate immunity. Previous studies report deficiency in virus induction of interferon (IFN)-α, IFN-β and IFN-λ in bronchial epithelial and bronchial lavage cells in atopic asthmatics. It is now recognized that asthma is a heterogeneous disease comprising different inflammatory phenotypes, some of which may involve innate immune activation in the absence of overt infection.

OBJECTIVE

The aim of this study was to investigate whether the severity of asthma or a specific cellular sputum pattern may be linked to evidence of innate immune activation.

METHODS

Here we investigate the expression of IFN-β, IFN-λ1 (IL-29), IFN-λ2/3 (IL-28A/B) and the interferon-stimulated genes (ISGs) such as myxovirus resistance 1 (Mx1), oligoadenylate synthetase (OAS) and viperin in unstimulated sputum cells in 57 asthmatics (including 16 mild, 19 moderate and 22 severe asthma patients) and compared them with 19 healthy subjects.

RESULTS

We observed increased expression of IFN-β, IFN-λ1/IL-29, OAS and viperin in asthmatics compared with healthy subjects, while IL-28 was not expressed in any group. The overexpression was restricted to neutrophilic asthmatics (sputum neutrophils ≥ 76%), while eosinophilic asthmatics (sputum eosinophils ≥ 3%) did not differ from healthy subjects or even showed a lower expression of Mx1. No difference in interferon or ISG expression was observed according to clinical asthma severity.

CONCLUSION AND CLINICAL RELEVANCE

Neutrophilic, but not eosinophilic, asthmatics display overexpression of IFN-β, IFN-λ1/IL-29 and ISGs in their sputum cells that may reflect ongoing innate immune activation.

Disturbed cytokine production at the systemic level in difficult-to-control atopic asthma: evidence for raised interleukin-4 and decreased interferon-γ release following lipopolysaccharide stimulation

BACKGROUND

Disturbed cytokine production is thought to govern inflammation in asthma, which, in its turn, may lead to uncontrolled disease. The aim of this study was to assess the relationship between cytokine production from blood leucocytes and the level of asthma control.

METHODS

We compared the production of interleukin (IL)-4, IL-6, IL-10, interferon (IFN)-γ and tumour necrosis factor-α from peripheral blood leucocytes in non-atopic healthy subjects (n = 22), atopic non-asthmatics (n = 10), well-controlled asthmatics [Juniper asthma control questionnaire (ACQ) score <1.5; n = 20] and patients with uncontrolled asthma despite inhaled or oral corticoids (ACQ score ≥1.5; n = 20). Fifty microlitres of peripheral blood was incubated for 24 h with RPMIc, lipopolysaccharide (LPS; 1 ng/ml) or phytohaemagglutinin (1 μg/ml), and cytokines were measured by immunotrapping (ELISA).

RESULTS

Both controlled and uncontrolled asthmatics as well as atopic non-asthmatics spontaneously produced more IL-4 than non-atopic healthy subjects (p < 0.001). IL-4 production induced by LPS was significantly greater (p < 0.05) in both asthma groups compared to atopic non-asthmatics and non-atopic healthy subjects. By contrast, IFN-γ release induced by LPS was lower in uncontrolled asthmatics than in non-atopic healthy subjects (p < 0.05) and controlled asthmatics (p < 0.05). IL-10 release after LPS was greater in uncontrolled asthmatics than in atopic non-asthmatics (p < 0.05). No difference was observed regarding other cytokines.

CONCLUSION

Blood cells from patients with difficult-to-control atopic asthma display highly skewed Th2 cytokine release following LPS stimulation.