Comparison of particles in exhaled air and multiple breath washout for assessment of small airway function in children with cystic fibrosis

BACKGROUND

The introduction of modulator therapy for cystic fibrosis (CF) has led to an increased interest in the detection of small airway disease (SAD) as sensitive marker of treatment response. The particles in exhaled air (PExA) method, which records exhaled particle mass (PEx ng/L) and number (PExNR), detects SAD in adult patients. Our primary aim was to investigate if PExA outcomes in children with CF are different when compared to controls and associated with more severe disease. Secondary aims were to assess feasibility and repeatability of PExA in children with CF and to correlate PExA to multiple breath nitrogen washout (MBNW) as an established marker of SAD.

METHODS

Thirteen healthy children (HC), 17 children with CF with normal lung function (CF-N) (FEV1 z-score ≥ -1.64) and six with airway obstruction (CF-AO) (FEV1 z-score < -1.64) between 8 and 18 years performed MBNW followed by PExA and spirometry. Children with CF repeated the measurements after 3 months.

RESULTS

PEx ng/L and PExNR/L per liter of exhaled breath were similar between the three groups. The lung clearance index (LCI) was significantly higher in both CF-N and CF-AO compared to HC. All participants, except one, were able to perform PExA. Coefficient of variation for PEx ng/l was (median) 0.38, range 0-1.25 and PExNR/l 0.38, 0-1.09. Correlation between LCI and PEx ng/l was low, rs 0.32 (p = .07).

CONCLUSION

PExA is feasible in children. In contrast to LCI, PExA did not differentiate healthy children from children with CF suggesting it to be a less sensitive tool to detect SAD.

Non-tuberculous mycobacteria disease pre-lung transplantation: A systematic review of the treatment regimens and duration pre- and post-transplant

BACKGROUND

There is lack of consensus on non-tuberculous mycobacteria pulmonary disease (NTM-PD) treatment regimen and duration in patient listed for lung transplantation (LTx). We conducted a systematic review on treatment regimen and duration pre- and directly post-LTx, for patients with known NTM-PD pre-LTx. Additionally, we searched for risk factors for NTM disease development post-LTx and for mortality.

METHODS

Literature was reviewed on PubMed, Embase and the Cochrane Library, for articles published from inception to January 2022. Individual patient data were sought.

RESULTS

Sixteen studies were included reporting 92 patients. Most frequent used agents were aminoglycosides and macrolides for Mycobacterium abscessus (M. abscessus) and macrolides and tuberculostatic agents for Mycobacterium avium complex (M. avium complex). The median treatment duration pre-LTx was 10 months (IQR 6-17) and 2 months (IQR 2-8) directly post-LTx. Longer treatment duration pre-LTx was observed in children and in patients with M. abscessus. 46% of the patients with NTM-PD pre-LTx developed NTM disease post-LTx, related mortality rate was 10%. Longer treatment duration pre-LTx (p < 0.001) and sputum non-conversion pre-LTx (p = 0.003) were significantly associated with development of NTM-disease post-LTx. Longer treatment duration pre-LTx (p = 0.004), younger age (p < 0.001) and sputum non-conversion (p = 0.044) were risk factors for NTM related death.

CONCLUSIONS

The median treatment duration pre-LTx was 10 months (IQR 6-17) and 2 months (IQR 2-8) directly post-LTx. Patients with longer treatment duration for NTM-PD pre-LTx and with sputum non-conversion are at risk for NTM disease post-LTx and for NTM-related death. Children were particularly at risk for NTM related death.

Paraneoplastic pemphigus associated with post-transplant lymphoproliferative disorder after small bowel transplantation

BACKGROUND

PNP is a malignancy-associated autoimmune mucocutaneous syndrome due to autoantibodies against plakins, desmogleins, and other components of the epidermis and basement membrane of epithelial tissues. PNP-causing malignancies comprise mainly lymphoproliferative and hematologic neoplasms. PNP is extremely rare, especially in children.

METHODS

Here, we present the first case of a child who developed PNP on a PTLD after small bowel transplantation because of a severe genetic protein-losing enteropathy.

RESULTS

The patient in this case report had a severe stomatitis, striate palmoplantar keratoderma, and lichenoid skin lesions. In addition, she had marked esophageal involvement. She had lung pathology due to recurrent pulmonary infections and ventilator injury. Although we found no evidence of BO, she died from severe pneumonia and respiratory failure at the age of 12 years.

CONCLUSION

It is exceptional that, despite effective treatment of the PTLD, the girl survived 5 years after her diagnosis of PNP. We hypothesize that the girl survived relatively long after the PNP diagnosis due to strong T-cell suppressive treatments for her small bowel transplantation.

New insights in phenotype and treatment of lung disease immuno-deficiency and chromosome breakage syndrome (LICS)

We report five patients with lung disease immuno-deficiency and chromosome breakage syndrome (LICS) but without recurrent infections and severe immunodeficiency. One patient had extended survival to 6.5 years. Hematopoietic stem-cell transplantation failed to cure another patient. Our findings suggest that the immunological abnormalities can be limited and do not fully explain the LICS phenotype.

Differences in lung clearance index and functional residual capacity between two commercial multiple-breath nitrogen washout devices in healthy children and adults

Multiple-breath nitrogen washout (MBNW) and its clinical parameter lung clearance index (LCI) are gaining increasing attention for the assessment of small airway function. Measurement of LCI relies on accurate assessment of functional residual capacity (FRC). The EasyOne Pro LAB (ndd) and Exhalyzer D (EM) are two commercially available MBNW devices. The aim of the study was to compare these two devices in vitro and in vivo in healthy subjects with regard to FRC, LCI and secondary outcome parameters and to relate FRC_MBNW to FRC measured by body plethysmography (pleth) and helium dilution technique. MBNW measurements were performed using a lung model (FRC between 500 and 4000 mL) in vitro and in 38 subjects aged 6–65 years followed by helium dilution and pleth in vivo using fixed and relaxed breathing techniques. In vitro accuracy within 5% of lung model FRC was 67.3% for ndd, FRC was >5% higher for EM in all tests. In vivo, FRC_pleth ranged from 1.2 to 5.6 L. Mean differences (limits of agreement) between FRC_pleth and FRC_MBNW were −7.0%, (−23.2 to 9.2%) and 5.7% (−11.2 to 22.6%) using ndd and EM, respectively. FRC_ndd was consistently lower than FRC_EM (−11.8% (−25.6 to 2%)). LCI was comparable between the two devices (−1.3% (−21.9 to 19.3%)). There was a difference of >10 % in LCI in 12 of 38 subjects. Using the most recent software updates, both devices show relevant deviations in FRC measurement both in vitro and in vivo and individual differences in LCI in a significant proportion of subjects. The devices are therefore not interchangeable.

MBNW measurements with the Exhalyzer D and EasyOne Pro LAB cannot be used interchangeably for FRC and LCI measurements. FRC measured on both devices showed deviations from in vitro and in vivo measurements.https://bit.ly/2xyyUuJ

Protocadherin-1 Localization and Cell-Adhesion Function in Airway Epithelial Cells in Asthma

Background

The asthma gene PCDH1 encodes Protocadherin-1, a putative adhesion molecule of unknown function expressed in the airway epithelium. Here, we characterize the localization, differential expression, homotypic adhesion specificity and function of PCDH1 in airway epithelial cells in asthma.

Methods

We performed confocal fluorescence microscopy to determine subcellular localization of PCDH1 in 16HBE cells and primary bronchial epithelial cells (PBECs) grown at air-liquid interface. Next, to compare PCDH1 expression and localization in asthma and controls we performed qRT-PCR and fluorescence microscopy in PBECs and immunohistochemistry on airway wall biopsies. We examined homotypic adhesion specificity of HEK293T clones overexpressing fluorescently tagged-PCDH1 isoforms. Finally, to evaluate the role for PCDH1 in epithelial barrier formation and repair, we performed siRNA knockdown-studies and measured epithelial resistance.

Results

PCDH1 localized to the cell membrane at cell-cell contact sites, baso-lateral to adherens junctions, with increasing expression during epithelial differentiation. No differences in gene expression or localization of PCDH1 isoforms expressing the extracellular domain were observed in either PBECs or airway wall biopsies between asthma patients and controls. Overexpression of PCDH1 mediated homotypic interaction, whereas downregulation of PCDH1 reduced epithelial barrier formation, and impaired repair after wounding.

Conclusions

In conclusion, PCDH1 is localized to the cell membrane of bronchial epithelial cells baso-lateral to the adherens junction. Expression of PCDH1 is not reduced nor delocalized in asthma even though PCDH1 contributes to homotypic adhesion, epithelial barrier formation and repair.

Protocadherin-1 binds to SMAD3 and suppresses TGF-β1-induced gene transcription

Genetic studies have identified Protocadherin-1 (PCDH1) and Mothers against decapentaplegic homolog-3 (SMAD3) as susceptibility genes for asthma. PCDH1 is expressed in bronchial epithelial cells and has been found to interact with SMAD3 in yeast two-hybrid (Y2H) overexpression assays. Here, we test whether PCDH1 and SMAD3 interact at endogenous protein levels in bronchial epithelial cells and evaluate the consequences thereof for transforming growth factor-β1 (TGF-β1)-induced gene transcription. We performed Y2H screens and coimmunoprecipitation (co-IP) experiments of PCDH1 and SMAD3 in HEK293T and 16HBE14o(-) (16HBE) cell lines. Activity of a SMAD3-driven luciferase reporter gene in response to TGF-β1 was measured in BEAS-2B cells transfected with PCDH1 and in 16HBE cells transfected with PCDH1-small-interfering RNA (siRNA). TGF-β1-induced gene expression was quantified in BEAS-2B clones overexpressing PCDH1 and in human primary bronchial epithelial cells (PBECs) transfected with PCDH1-siRNA. We confirm PCDH1 and SMAD3 interactions by Y2H and by co-IP in HEK293T cells overexpressing both proteins, and at endogenous protein levels in 16HBE cells. TGF-β-induced activation of a SMAD3-driven reporter was reduced by exogenous PCDH1 in BEAS2B cells, whereas it was increased by siRNA-mediated knockdown of endogenous PCDH1 in 16HBE cells. Overexpression of PCDH1 suppressed expression of TGF-β target genes in BEAS-2B cells, whereas knockdown of PCDH1 in human PBECs increased TGF-β-induced gene expression. In conclusion, we demonstrate that PCDH1 binds to SMAD3 and regulates its activation by TGF-β signaling in bronchial epithelial cells. We propose that PCDH1 and SMAD3 act in a single pathway in asthma susceptibility that affects sensitivity of the airway epithelium to TGF-β.

Untargeted lipidomic analysis in chronic obstructive pulmonary disease. Uncovering sphingolipids

RATIONALE

Cigarette smoke is the major risk factor in the development of chronic obstructive pulmonary disease (COPD). Lipidomics is a novel and emerging research field that may provide new insights in the origins of chronic inflammatory diseases, such as COPD.

OBJECTIVES

To investigate whether expression of the sputum lipidome is affected by COPD or cigarette smoking.

METHODS

Lipid expression was investigated with liquid chromatography and high-resolution quadrupole time-of-flight mass spectrometry in induced sputum comparing smokers with and without COPD, and never-smokers. Changes in lipid expression after 2-month smoking cessation were investigated in smokers with and without COPD.

MEASUREMENTS AND MAIN RESULTS

More than 1,500 lipid compounds were identified in sputum. The class of sphingolipids was significantly higher expressed in smokers with COPD than in smokers without COPD. At single compound level, 168 sphingolipids, 36 phosphatidylethanolamine lipids, and 5 tobacco-related compounds were significantly higher expressed in smokers with COPD compared with smokers without COPD. The 13 lipids with a high fold change between smokers with and without COPD showed high correlations with lower lung function and inflammation in sputum. Twenty (glyco)sphingolipids and six tobacco-related compounds were higher expressed in smokers without COPD compared with never-smokers. Two-month smoking cessation reduced expression of 26 sphingolipids in smokers with and without COPD.

CONCLUSIONS

Expression of lipids from the sphingolipid pathway is higher in smokers with COPD compared with smokers without COPD. Considering their potential biologic properties, they may play a role in the pathogenesis of COPD.

Mouse protocadherin-1 gene expression is regulated by cigarette smoke exposure in vivo

Protocadherin-1 (PCDH1) is a novel susceptibility gene for airway hyperresponsiveness, first identified in families exposed to cigarette smoke and is expressed in bronchial epithelial cells. Here, we asked how mouse Pcdh1 expression is regulated in lung structural cells in vivo under physiological conditions, and in both short-term cigarette smoke exposure models characterized by airway inflammation and hyperresponsiveness and chronic cigarette smoke exposure models. Pcdh1 gene-structure was investigated by Rapid Amplification of cDNA Ends. Pcdh1 mRNA and protein expression was investigated by qRT-PCR, western blotting using isoform-specific antibodies. We observed 87% conservation of the Pcdh1 nucleotide sequence, and 96% conservation of the Pcdh1 protein sequence between men and mice. We identified a novel Pcdh1 isoform encoding only the intracellular signalling motifs. Cigarette smoke exposure for 4 consecutive days markedly reduced Pcdh1 mRNA expression in lung tissue (3 to 4-fold), while neutrophilia and airway hyperresponsiveness was induced. Moreover, Pcdh1 mRNA expression in lung tissue was reduced already 6 hours after an acute cigarette-smoke exposure in mice. Chronic exposure to cigarette smoke induced loss of Pcdh1 protein in lung tissue after 2 months, while Pcdh1 protein levels were no longer reduced after 9 months of cigarette smoke exposure. We conclude that Pcdh1 is highly homologous to human PCDH1, encodes two transmembrane proteins and one intracellular protein, and is regulated by cigarette smoke exposure in vivo.

Diminished expression of multidrug resistance-associated protein 1 (MRP1) in bronchial epithelium of COPD patients

Cigarette smoke is the principal risk factor for chronic obstructive pulmonary disease (COPD). Multidrug resistance proteins, such as multidrug resistance-associated protein-1 (MRP1), P-glycoprotein (P-gp), and lung resistance-related protein (LRP), may protect against oxidative stress and toxic compounds generated by cigarette smoking. Expression of MRP1, P-gp, and LRP was evaluated in bronchial epithelium of two study groups of COPD patients and their controls and was associated with disease status and smoking history. In study group 1, MRP1, but not P-gp and LRP expression, was lower (p=0.029) in normal bronchial epithelium of COPD patients (n=11) compared to healthy controls (n=8). MRP1 expression was high in squamous metaplastic epithelium. When including expression in squamous metaplastic cells, MRP1 was still lower in total bronchial epithelium in the COPD group (p=0.038). In study group 2, expression of MRP1, but not of P-gp and LRP, was lower (p=0.047) in lung tissue of (very) severe COPD (n=10) vs mild to moderate COPD (n=9) patients. In conclusion, MRP1 expression was lower in bronchial biopsies of COPD patients than of healthy controls and was also lower in patients with severe COPD than with mild/moderate COPD. Our findings indicate that diminished MRP1 expression in normal bronchial epithelium is associated with COPD. The exact role in COPD pathogenesis is to be revealed by further functional studies.

Increased number of B-cells in bronchial biopsies in COPD

Recently, it has been shown that the accumulated volume of B-cells in small airways is increased in chronic obstructive pulmonary disease (COPD) Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 3 and 4. Little is known about the number of B-cells in central airways in COPD. The present authors hypothesised that the number of B-cells in bronchial biopsies of large airways is higher in patients with COPD than in controls without airflow limitation and higher in more severe COPD. Therefore, bronchial biopsies were collected from 114 COPD patients (postbronchodilator forced expiratory volume in one second (FEV1) 63+/-9 % predicted value, FEV1/inspiratory vital capacity (IVC) 48+/-9%) and 28 controls (postbronchodilator FEV1 108+/-12 % predicted value, FEV1/IVC 78+/-4%). Paraffin sections were stained for B-cells (CD20+) and their number was determined in the subepithelial area (excluding muscle, glands and vessels). B-cell numbers were higher in patients with COPD versus controls (8.5 versus 3.9 cells x mm(-2), respectively) and higher in patients with GOLD severity stage 3 (n = 11) than stage 2 (n = 103; 22.3 versus 7.8 cells x mm(-2)). No relationship was found between the number of B-cells and clinical characteristics within the chronic obstructive pulmonary disease group. The authors suggest that these increased B-cell numbers may have an important contribution to the pathogenesis of chronic obstructive pulmonary disease.

Effect of 1-year smoking cessation on airway inflammation in COPD and asymptomatic smokers

Smoking cessation is the only treatment in patients with chronic obstructive pulmonary disease (COPD) effective in slowing down disease progression. Its effect on airway inflammation in COPD is unknown, although cross-sectional studies suggest ongoing inflammation in ex-smokers. In order to elucidate the effect of smoking cessation on airway inflammation, 28 smokers with COPD (mean age: 55 yrs; forced expiratory volume in one second: 71% predicted) and 25 asymptomatic smokers with normal lung function (aged 50 yrs) were included in a 1-yr smoking cessation programme. Effects of smoking cessation on airway inflammation were investigated in bronchial biopsies (baseline, 12 months) and sputum samples (baseline, 2, 6 and 12 months). In the 12 candidates with COPD who successfully ceased smoking, airway inflammation persisted in bronchial biopsies, while the number of sputum neutrophils, lymphocytes, interleukin (IL)-8 and eosinophilic-cationic-protein levels significantly increased at 12 months. In the 16 asymptomatic smokers who successfully quitted, inflammation significantly reduced (i.e. number of sputum macrophages, percentage of eosinophils and IL-8 levels) or did not change. The current authors suggest that the observed persistent airway inflammation in patients with chronic obstructive pulmonary disease is related to repair of tissue damage in the airways. It remains to be elucidated whether this reflects a beneficial or detrimental effect.

Smoking cessation improves both direct and indirect airway hyperresponsiveness in COPD

Smoking induces chronic obstructive pulmonary disease (COPD) and is associated with airway inflammation and airway hyperresponsiveness (AHR). It has not been studied in COPD whether direct (methacholine) and indirect (adenosine-5'-monophosphate (AMP)) stimuli are associated with airway inflammation and neither whether smoking cessation improves these features. The current authors cross-sectionally investigated the relationship of AHR to methacholine and AMP with lung function and inflammatory cells in the sputum of 33 smokers with COPD. In addition, changes in these parameters were prospectively assessed in 14 smokers who successfully quit smoking for 1 yr. The presence of AHR to both methacholine and AMP was associated with lower lung function, but not with sputum inflammation. AHR to methacholine and AMP improved significantly after a 1-yr smoking cessation, yet this was unrelated to changes in sputum cell counts. The numbers of neutrophils and epithelial cells significantly increased with smoking cessation. Both direct and indirect airway hyperresponsiveness are associated with lower lung function, but not with sputum inflammation in chronic obstructive pulmonary disease. Interestingly, 1-yr smoking cessation improved both direct and indirect airway hyperresponsiveness, yet without a significant association with changes in lung function or sputum inflammation. Thus, other factors are likely to induce these improvements, e.g. a reduction in stimulation of irritant receptors, airway wall changes or mucus hypersecretion.

The impact of smoking cessation on respiratory symptoms, lung function, airway hyperresponsiveness and inflammation

Smoking is the main risk factor in the development of chronic obstructive pulmonary disease (COPD), and smoking cessation is the only effective treatment for avoiding or reducing the progression of this disease. Despite the fact that smoking cessation is a very important health issue, information about the underlying mechanisms of the effects of smoking cessation on the lungs is surprisingly scarce. It is likely that the reversibility of smoke-induced changes differs between smokers without chronic symptoms, smokers with nonobstructive chronic bronchitis and smokers with COPD. This review describes how these three groups differ regarding the effects of smoking cessation on respiratory symptoms, lung function (forced expiratory volume in one second), airway hyperresponsiveness, and pathological and inflammatory changes in the lung. Smoking cessation clearly improves respiratory symptoms and bronchial hyperresponsiveness, and prevents excessive decline in lung function in all three groups. Data from well-designed studies are lacking regarding the effects on inflammation and remodelling, and the few available studies show contradictory results. In chronic obstructive pulmonary disease, a few histopathological studies suggest that airway inflammation persists in exsmokers. Nevertheless, many studies have shown that smoking cessation improves the accelerated decline in forced expiratory volume in one second, which strongly indicates that important inflammatory and/or remodelling processes are positively affected.