Optimized dialysis and protease inhibition of sputum dithiothreitol supernatants

Orally administered yeast-derived β-glucan alleviates mast cell-dependent airway hyperresponsiveness and inflammation in a murine model of asthma

BACKGROUND

Particulate β-glucans (WGP) are natural compounds with regulatory roles in various biological processes, including tumorigenesis and inflammatory diseases such as allergic asthma. However, their impact on mast cells (MCs), contributors to airway hyperresponsiveness (AHR) and inflammation in asthma mice, remains unknown.

METHODS

C57BL/6 mice underwent repeated OVA sensitization without alum, followed by Ovalbumin (OVA) challenge. Mice received daily oral administration of WGP (OAW) at doses of 50 or 150 mg/kg before sensitization and challenge. We assessed airway function, lung histopathology, and pulmonary inflammatory cell composition in the airways, as well as proinflammatory cytokines and chemokines in the bronchoalveolar lavage fluid (BALF).

RESULTS

The 150 mg/kg OAW treatment mitigated OVA-induced AHR and airway inflammation, evidenced by reduced airway reactivity to aerosolized methacholine (Mch), diminished inflammatory cell infiltration, and goblet cell hyperplasia in lung tissues. Additionally, OAW hindered the recruitment of inflammatory cells, including MCs and eosinophils, in lung tissues and BALF. OAW treatment attenuated proinflammatory tumor necrosis factor (TNF)-α and IL-6 levels in BALF. Notably, OAW significantly downregulated the expression of chemokines CCL3, CCL5, CCL20, CCL22, CXCL9, and CXCL10 in BALF.

CONCLUSION

These results highlight OAW's robust anti-inflammatory properties, suggesting potential benefits in treating MC-dependent AHR and allergic inflammation by influencing inflammatory cell infiltration and regulating proinflammatory cytokines and chemokines in the airways.

Clinical, functional and inflammatory evaluation in asthmatic patients after a simple short-term educational program: a randomized trial

This study aimed to evaluate the clinical evolution, functional parameters and inflammatory activity of asthma in patients who submitted to an educational intervention. 58 adult patients over 18 years of age with partly controlled and uncontrolled asthma were randomized into an intervention group (IG) (N = 32) and a control group (CG) (N = 26) and evaluated for 12 weeks. The Asthma Control Test (ACT), Asthma Control Questionnaire (ACQ), Asthma Quality Life Questionnaire (AQLQ) and Beck Depression Inventory (BDI) questionnaires were applied. Spirometry, exhaled nitric oxide (NO), exhaled breath condensate (EBC) and induced sputum (IS), measurement of the peak flow and symptoms were performed. The IG patients received an educational activity for 30 min applied by a nurse. Statistical analysis: analysis of variance with repeated intragroup measures. IG presented a decreased number of eosinophils in IS and IL-17A in EBC, an increase in the percentage of FEV1 before and after bronchodilator and an improvement in quality of life compared to the CG. There was an improvement in depression levels and a decrease in IL-4 and IL-5 in the IS and in the EBC in both groups. Our results suggest that an educational intervention can bring benefits concerning the control of inflammation, lung function alterations, quality of life and levels of depression in asthmatic patients. Registration: ClinicalTrials.gov; NCT03655392.

Integrated DNA and RNA extraction using magnetic beads from viral pathogens causing acute respiratory infections

Current extraction methods often extract DNA and RNA separately, and few methods are capable of co-extracting DNA and RNA from sputum. We established a nucleic acid co-extraction method from sputum based on magnetic beads and optimized the method by evaluating influencing factors, such as the guanidinium thiocyanate (GTC) and dithiothreitol (DTT) concentrations, magnetic bead amount, incubation temperature, lysis buffer pH and RNA carrier type. The feasibility of the simultaneous nucleic acid co-extraction method was evaluated by amplifying DNA and RNA viruses from a single clinical specimen with a multiplex RT-qPCR method. Both DNA and RNA were most efficiently extracted when the GTC and DTT concentrations were 2.0 M and 80 mM, respectively, 20 μl magnetic beads were added, the incubation temperature was 80 °C, the pH was 8 or 9, and RNA carrier A was used. Therefore, we established a simple method to extract nucleic acids from two important respiratory viruses compared with other commercial kits. This magnetic beads-based co-extraction method for sputum followed by a multiplex RT-qPCR can rapidly and precisely detect DNA and RNA viruses from a single clinical specimen and has many advantages, such as decreased time, low cost, and a lack of harmful chemicals.

Comparative Evaluation of Three Homogenization Methods for Isolating Middle East Respiratory Syndrome Coronavirus Nucleic Acids From Sputum Samples for Real-Time Reverse Transcription PCR

BACKGROUND

Real-time reverse transcription PCR (rRT-PCR) of sputum samples is commonly used to diagnose Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Owing to the difficulty of extracting RNA from sputum containing mucus, sputum homogenization is desirable prior to nucleic acid isolation. We determined optimal homogenization methods for isolating viral nucleic acids from sputum.

METHODS

We evaluated the following three sputum-homogenization methods: proteinase K and DNase I (PK-DNase) treatment, phosphate-buffered saline (PBS) treatment, and N-acetyl-L-cysteine and sodium citrate (NALC) treatment. Sputum samples were spiked with inactivated MERS-CoV culture isolates. RNA was extracted from pretreated, spiked samples using the easyMAG system (bioMérieux, France). Extracted RNAs were then subjected to rRT-PCR for MERS-CoV diagnosis (DiaPlex Q MERS-coronavirus, SolGent, Korea).

RESULTS

While analyzing 15 spiked sputum samples prepared in technical duplicate, false-negative results were obtained with five (16.7%) and four samples (13.3%), respectively, by using the PBS and NALC methods. The range of threshold cycle (Ct) values observed when detecting upE in sputum samples was 31.1-35.4 with the PK-DNase method, 34.7-39.0 with the PBS method, and 33.9-38.6 with the NALC method. Compared with the control, which were prepared by adding a one-tenth volume of 1:1,000 diluted viral culture to PBS solution, the ranges of Ct values obtained by the PBS and NALC methods differed significantly from the mean control Ct of 33.2 (both P<0.0001).

CONCLUSIONS

The PK-DNase method is suitable for homogenizing sputum samples prior to RNA extraction.

Identification of ENO1 as a potential sputum biomarker for early-stage lung cancer by shotgun proteomics

BACKGROUND

Lung cancer is the leading cancer killer. Early detection will reduce the related deaths. The objective of this study was to identify potential biomarkers for early-stage lung cancer in sputum supernatant.

MATERIALS AND METHODS

Using shotgun proteomics, we detected changes in protein profiles that were associated with lung cancer by analyzing sputum supernatants from 6 patients with early-stage lung cancer and 5 cancer-free controls. Using western blotting, we validated the proteomic results in 22 lung cancer cases and 22 controls. Using enzyme-linked immunosorbent assay (ELISA), we evaluated the diagnostic performance of the biomarker candidates in an independent set of 35 cases and 36 controls.

RESULTS

Proteomics identified 8 biomarker candidates for lung cancer. Western blotting validation of the candidates showed that enolase 1 (ENO1) displayed a higher expression level in patients with cancer than in cancer-free individuals (P = .015). ELISA revealed that the assessment of ENO1 expression in sputum supernatant had 58.33% sensitivity and 80.00% specificity in distinguishing patients with stage I lung cancer from cancer-free individuals.

CONCLUSION

The analysis of protein biomarkers in sputum may provide a potential approach for the early detection of lung cancer. Future validation of all the candidates defined by shotgun proteomics in a large cohort study may help develop additional biomarkers that can be added to ENO1 to provide more diagnostic efficacy for lung cancer.

EGF-induced bronchial epithelial cells drive neutrophil chemotactic and anti-apoptotic activity in asthma

Chronic damage and repair of the bronchial epithelium are features of asthma. We have previously reported that ex vivo stimulation of normal bronchial epithelial cells with epidermal growth factor (EGF), a key factor of epithelial repair, enhances the mechanisms of neutrophil accumulation, thereby promoting neutrophil defences during acute injury but potentially enhancing inflammation in chronic airway diseases. We have now sought to (i) determine whether this EGF-dependent pro-neutrophil activity is increased in asthma, where EGF and its epithelial receptor are over-expressed, and (ii) elucidate some of the mechanisms underlying this asthmatic epithelial-neutrophil interaction. Primary bronchial epithelial cells (PBEC) from healthy subjects, mild asthmatics and moderate-to-severe asthmatics (Mod/Sev) were stimulated with EGF, a model that mimics a repairing epithelium. Conditioned culture media (EGF-CM) were assessed for neutrophil chemotactic and anti-apoptotic activities and inflammatory mediator production. EGF induced the epithelium to produce soluble mediators with neutrophil chemotactic (p<0.001) and pro-survival (p = 0.021) activities which were related to the clinical severity of asthma (trend p = 0.010 and p = 0.009, respectively). This was associated with enhanced IL-6, IL-8, GM-CSF and TNF-α release, and cytokine-neutralising experiments using EGF-CM from Mod/Sev asthmatics demonstrated a role for GM-CSF in neutrophil survival (p<0.001). Pre-treatment of neutrophils with specific inhibitors of the myeloid-restricted class I phosphatidylinositol-3-OH kinase (PI(3)K) isoforms showed that the EGF-CM from Mod/Sev asthmatics depended on the γ (p<0.021) but not δ isoforms, while neutrophil survival required multiple class I PI(3)Ks. The EGF-induced chemotactic, but not pro-survival activity, involved RhoA signaling in neutrophils (p = 0.012). EGF whose activity is upregulated in asthma induces ex vivo the epithelium from asthmatic patients to produce pro-neutrophil activities; these are related to asthma severity and, in moderate-to-severe asthmatics, involves class IB PI(3)Kγ signaling, providing a potential therapeutic target for neutrophilic forms of asthma.

Sputum IgE and cytokines in asthma: relationship with sputum cellular profile

BACKGROUND

Local IgE production may play a role in asthma pathogenesis. The aim of the study was to assess sputum total IgE and cytokines in asthmatics according to sputum cellular phenotype.

METHODS

We studied 122 subjects including 22 non atopic healthy subjects, 41 eosinophilic (sputum eosinophils ≥3%), 16 neutrophilic (sputum neutrophils >76%) and 43 pauci-granulocytic asthmatics (sputum eosinophils <3% and sputum neutrophils ≤76%) recruited from the asthma clinic at CHU Liege. Sputum supernatant total IgE (tIgE) was measured by ImmunoCAP and sputum supernatant cytokines (IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, IFN-γ and TNF-α) were measured with the Luminex xMAP Technology by using commercially available Fluorokine MAP kits.

RESULTS

After concentrating sputum samples, total IgE was detectable in the majority of subjects. Sputum IgE was raised in asthmatics when compared to healthy subjects. Overall, asthmatics did not significantly differ from healthy subjects with respect to cytokine levels. The eosinophilic asthma phenotype, however, was characterised by raised sputum tIgE, IL-5 and IL-13 compared to healthy subjects (p<0.001, p<0.001 and p<0.05 respectively) and pauci-granulocytic asthma (p<0.01, p<0.001 and p<0.05 respectively) and raised IL-5 compared to neutrophilic asthma (p<0.01). When patients were classified according to sputum IgE levels, it appeared that IL-5, IL-6, IL-17 and TNF-α sputum supernatant levels were raised in the "IgE high" asthmatics (IgE ≥0.1 kU/l) when compared to "IgE low" asthmatics (IgE<0.1 kU/l).

CONCLUSION

The eosinophilic asthma phenotype was associated with raised sputum IgE and a Th2 cytokine profile. Raised sputum IgE was associated with a heterogeneous cytokine overproduction.

[Clinical application of induced and spontaneous sputum in asthma and chronic obstructive pulmonary disease]

In recent years induced sputum analysis has become a non-invasive method for the assessment of airway inflammation in obstructive airway diseases. Sputum induction is safe and well tolerated by the patients. The method has been standardized, and this has markedly improved the quality and reproducibility of sputum samples. Identification of sputum eosinophilia has the greatest clinical relevance as it predicts a favorable response to corticosteroids. Treatment strategy aiming normalisation of sputum eosinophil cell count may reduce the rate of exacerbations in asthma. Profiling inflammatory mediators in sputum supernatant provides new insights into the pathogenesis of asthma and chronic obstructive pulmonary disease. Cell type analysis in spontaneous sputum may also provide much information about inflammatory processes in the airways. Based on the results of clinical studies sputum analysis should be more often used in clinical settings in the future.

The role of natural killer T cells in the pathogenesis of acute exacerbation of human asthma

BACKGROUND

Natural killer T (NKT) cells have been reported to play a crucial role in the pathogenesis of asthma in a mouse model of acute asthma. The present study aimed to investigate the role of NKT cells in the immune pathogenesis of acute exacerbation of human asthma.

METHODS

Blood and sputum were obtained at baseline and 8 h after a challenge in 20 asthmatics who underwent allergen bronchial provocation testing and during exacerbation and convalescence in 9 asthmatics who were admitted to hospital with an acute exacerbation after an upper respiratory tract infection. 6B11+ or Vα24+ NKT cells were measured with flow cytometry. Inflammatory cells, cytokines and chemokines were determined in sputum.

RESULTS

The number of blood NKT cells did not change after a positive allergen challenge compared to the baseline. However, blood CD4+Vα24+ NKT cells decreased during infection-associated asthma exacerbations compared to the convalescence measurements of the same patients (p < 0.05) or the baseline measurements of asthmatics who underwent allergen challenges (p < 0.01). The number of sputum NKT cells did not change after a positive allergen challenge or during infection-associated asthma exacerbations. Eosinophils and various cytokines and chemokines increased in sputum during infection-associated asthma exacerbations. Blood CD4+Vα24+ NKT cells were inversely related to sputum eosinophils (Spearman's correlation coefficient = -0.62; p < 0.01).

CONCLUSION

Blood NKT cells decreased during infection-associated asthma exacerbation and were inversely associated with eosinophilic airway inflammation, suggesting that blood NKT cells might be mobilized to the airways and lungs during asthma exacerbation in humans.

Frequent chronic obstructive pulmonary disease exacerbators: how much real, how much fictitious?

Exacerbations are important events in the natural history of chronic obstructive pulmonary disease (COPD). The higher the number of COPD exacerbations, the worse are the clinical and economical consequences. The distribution of COPD exacerbations is however highly variable. Some patients do not exhibit exacerbations at all whereas others suffer frequent events (i.e., "frequent COPD exacerbators"). We review the scientific evidence regarding the impact of COPD exacerbation frequency and assess whether or not these frequent exacerbators represent a unique population of COPD patients with higher morbidity and mortality risks. A definition of "frequent COPD exacerbators" is suggested to differentiate it from other related terms, such as "treatment failure" and "recurrence." The standardization of this terminology seems to be necessary to further identify COPD phenotypes in patients who have an individual susceptibility to develop frequent exacerbations. It can also be of help to refine the most appropriate therapeutic and preventative measures.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

Analyses of asthma severity phenotypes and inflammatory proteins in subjects stratified by sputum granulocytes

BACKGROUND

Patients with severe asthma have increased granulocytes in their sputum compared with patients with mild to moderate asthma.

OBJECTIVE

We hypothesized that inflammatory granulocytes in sputum may identify specific asthma severity phenotypes and are associated with different patterns of inflammatory proteins in sputum supernatants.

METHODS

This hypothesis was tested in 242 patients with asthma enrolled in the Severe Asthma Research Program who provided sputum samples for cell count, differential cell determinations, cell lysates for Western blot, and supernatant analyses by inflammatory protein microarrays and ELISAs. ANOVA and multiple linear regression models tested mediator associations.

RESULTS

Stratified by sputum granulocytes, <2% or > or = 2% eosinophils and <40% or > or = 40% neutrophils, subjects with both increased eosinophils and neutrophils had the lowest lung function and increased symptoms and health care use. Subjects with elevated eosinophils with or without increased neutrophils had significantly increased fraction exhaled nitric oxide (FeNO) and serum eosinophils and greater frequency of daily beta-agonist use. Microarray data stratified by granulocytes revealed 25 to 28 inflammatory proteins increased >2-fold in sputa with > or = 40% neutrophils. Microarray analyses stratified by severity of asthma identified 6 to 9 proteins increased >2-fold in sputa in subjects with severe asthma compared with nonsevere asthma. ELISA data stratified by sputum granulocytes showed significant increases in brain-derived neurotrophic factor, IL-1beta, and macrophage inflammatory protein 3alpha/CCL20 for those with > or = 40% neutrophils; these mediators demonstrated positive associations with neutrophil counts.

CONCLUSION

Combined increased sputum eosinophils and neutrophils identified patients with asthma with the lowest lung function, worse asthma control, and increased symptoms and health care requirements. Inflammatory protein analyses of sputum supernatants found novel mediators increased in patients with asthma, predominantly associated with increased sputum neutrophils.

Induced sputum: a window to lung pathology

Sputum is recognized as a sampling method for the monitoring and assessment of chronic lung diseases such as asthma, COPD (chronic obstructive pulmonary disease) and cystic fibrosis. Sputum samples the central airways and its protein components (e.g. mucins and cytokines), cellular components (e.g. eosinophils and neutrophils) and microbiological components (e.g. viruses and bacteria) can be used as markers of disease severity, exacerbation, susceptibility or progression. This paper describes the basic constituents of induced sputum and how these influence the quantification and identification of novel biomarkers of chronic lung diseases using techniques such as proteomics.

Diversity of protein carbonylation in allergic airway inflammation

Oxidative stress is involved in asthma. This study assessed the carbonylation of sputum proteins in 23 uncontrolled adult asthmatic patients and 23 healthy controls. Carbonylated proteins (68 kDa and 53 kDa) were elevated in asthmatics when compared to controls and the 68-kDa carbonylated protein was significantly correlated with sputum eosinophilia. The kinetics of protein carbonylation in bronchoalveolar lavage fluid (BALF) were then examined in a mouse ovalbumin-induced allergic inflammation model. It was found that the carbonylation of various BALF proteins did not uniformly occur after challenge. The appearance of the 53-kDa carbonylated protein was limited within 24 h, while carbonylation of 68-kDa protein peaked at 48 h and was associated with BALF eosinophilia. Thus, it was demonstrated that the 68-kDa and 53-kDa proteins, corresponding to albumin and alpha1-antitrypsin, respectively, were specifically carbonylated in allergic inflammation in humans and in mice and that eosinophils may play a role in mediating carbonylation of albumin.

Granulocyte-macrophage colony-stimulating factor expression in induced sputum and bronchial mucosa in asthma and COPD

Background:

Granulocyte–macrophage colony-stimulating factor (GM-CSF) has been implicated as an important mediator in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). However, the expression of GM-CSF and its receptor in airway samples in asthma and COPD across disease severity needs to be further defined.

Methods:

Sputum GM-CSF was measured in 18 control subjects, 45 subjects with asthma and 47 subjects with COPD. Enumeration of GM-CSF+ cells in the bronchial submucosa and airway smooth muscle bundle was performed in 29 control subjects, 36 subjects with asthma and 10 subjects with COPD.

Results:

The proportion of subjects with measurable GM-CSF in the sputum was raised in those with moderate (7/14) and severe (11/18) asthma, and in those with COPD GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage II (7/16), III (8/17) and IV (7/14) compared with controls (1/18) and those with mild asthma (0/13); p = 0.001. The sputum GM-CSF concentration was correlated with the sputum eosinophilia in subjects with moderate to severe asthma (r_s = 0.41; p = 0.018). The median (interquartile range) GM-CSF+ and GM-CSFR+ cells/mm² of submucosa was increased in severe asthma (1.4 (3.0) and 2.1 (8.4)) compared with those with mild to moderate asthma (0 (2.5) and 1.1 (5)) and healthy controls (0 (0.5) and 0 (1.6)), (p = 0.004 and p = 0.02, respectively).

Conclusions:

The findings support a potential role for GM-CSF in asthma and COPD and suggest that overexpression of GM-CSF in sputum and the bronchial mucosa is a particular feature of severe asthma.