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Dragonieri S, Bikov A, Capuano A, Scarlata S, Carpagnano GE. Methodological Aspects of Induced Sputum. Adv Respir Med 2023; 91:397-406. [PMID: 37887074 PMCID: PMC10603896 DOI: 10.3390/arm91050031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/21/2023] [Accepted: 09/21/2023] [Indexed: 10/28/2023]
Abstract
We aimed to conduct a state-of-the-art review of the current literature and offer further insights into the methodological aspects concerning induced sputum. The increasing popularity of sputum induction as a non-invasive and cost-effective method for obtaining lower airway secretions from patients who cannot produce sputum naturally has led to extensive research and applications in respiratory conditions like asthma and COPD. This technique allows for analysis of the cellular and biochemical components of the sputum to take place, providing insights into airway inflammation, immune cells, and help in predicting treatment response. Furthermore, induced sputum enables various analyses, including microRNA and gene expression studies and immunophenotyping. The procedure is generally safe and well tolerated, even in patients with airflow limitations; however, monitoring lung function is essential, especially in those with airway hyperresponsiveness. Optimal saline solution concentration and inhalation duration have been investigated, recommending a 15-20 min induction with hypertonic saline. Expectoration involves coughing at the end of each inhalation time. Careful handling during sputum processing is necessary for obtaining accurate results in cell cytology, immunocytochemistry, and in situ hybridization. Overall, induced sputum offers significant advantages as a preferred alternative for large-scale and repeated airway sampling, despite some technical demands and limitations.
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Affiliation(s)
- Silvano Dragonieri
- Department of Respiratory Diseases, University of Bari, 70124 Bari, Italy; (S.D.); (A.C.); (G.E.C.)
| | - Andras Bikov
- Manchester Academic Health Science Centre, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester M13 9WL, UK
- Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Alessandro Capuano
- Department of Respiratory Diseases, University of Bari, 70124 Bari, Italy; (S.D.); (A.C.); (G.E.C.)
| | - Simone Scarlata
- Department of Internal Medicine, Unit of Respiratory Pathophysiology and Thoracic Endoscopy, Bio-Medical Campus, 00128 Rome, Italy;
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Pedersen F, Trinkmann F, Abdo M, Kirsten AM, Rabe KF, Watz H, Baraldo S, Saetta M, Hohlfeld JM, Holz O. Influence of Cell Quality on Inflammatory Biomarkers in COPD Sputum Supernatant. Int J Chron Obstruct Pulmon Dis 2021; 16:487-493. [PMID: 33688174 PMCID: PMC7935341 DOI: 10.2147/copd.s284938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/07/2021] [Indexed: 12/01/2022] Open
Abstract
Purpose We recently introduced a sputum cell quality score to rate how cell morphology, cellular debris and squamous cell contamination influence inflammatory cell identification during microscopic evaluation. However, sputum cell quality is generally not considered for the interpretation of sputum fluid phase biomarkers. Therefore, we compared the soluble protein concentrations between sputum samples with different cell quality. The impact of cell quality was compared to other factors potentially affecting soluble biomarker concentrations. Methods A comprehensive sputum dataset from 154 clinically stable COPD patients was used to analyse the differences and the variability of sputum supernatant concentrations for 23 proteins between low, medium, and high sputum cell quality samples. A model was developed and tested to compare the impact of different factors on sputum supernatant protein levels. Results Mean percentages of sputum macrophages, neutrophils, eosinophils, monocytes and lymphocytes showed no significant differences between low, medium and high cell quality levels. The mean percentage of squamous cells were lower, while total cell count/mL sputum and cell viability were significantly higher in sputum samples with higher cell quality. The concentrations of Interleukin-6, Interleukin-8 and Tumor Necrosis Factor Receptor 2 were significantly increased in sputum samples of higher cell quality. The variability of most protein concentrations declined with increasing cell quality levels. Sixteen proteins showed significantly negative correlations with the percentage of squamous cells. For 14 proteins we observed a positive correlation with cell number/mL sputum. Multiple regression analysis shows that generally less than 30% of the protein variability can be explained by the included factors. Conclusion Sputum cell quality has a significant impact on some soluble biomarker concentrations in sputum supernatant. Sputum samples with low sputum cell quality show a higher variability of fluid phase proteins in comparison to medium and high sputum cell quality levels.
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Affiliation(s)
- Frauke Pedersen
- Pulmonary Research Institute at LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany.,LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Frederik Trinkmann
- Pneumology and Critical Care Medicine, Thoraxklinik at University Hospital Heidelberg, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), Heidelberg, Germany
| | - Mustafa Abdo
- LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Anne-Marie Kirsten
- Pulmonary Research Institute at LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Klaus F Rabe
- LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Henrik Watz
- Pulmonary Research Institute at LungenClinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Simonetta Baraldo
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, Respiratory Diseases Clinic, University of Padova, Padova, Italy
| | - Marina Saetta
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, Respiratory Diseases Clinic, University of Padova, Padova, Italy
| | - Jens M Hohlfeld
- Fraunhofer ITEM, Clinical Airway Research - Biomedical Research in End-Stage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany.,Department of Respiratory Medicine, Hannover Medical School (MHH), Biomedical Research in End-Stage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Olaf Holz
- Fraunhofer ITEM, Clinical Airway Research - Biomedical Research in End-Stage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
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Lay JC, Peden DB, Alexis NE. Flow cytometry of sputum: assessing inflammation and immune response elements in the bronchial airways. Inhal Toxicol 2011; 23:392-406. [PMID: 21639708 DOI: 10.3109/08958378.2011.575568] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The evaluation of sputum leukocytes by flow cytometry (FCM) is an opportunity to assess characteristics of cells residing in the central airways, yet it is hampered by certain inherent properties of sputum including mucus and large amounts of contaminating cells and debris. OBJECTIVE To develop a gating strategy based on specific antibody panels in combination with light scatter properties for flow cytometric evaluation of sputum cells. METHODS Healthy and mild asthmatic volunteers underwent sputum induction. Manually selected mucus "plug" material was treated with dithiothreitol, filtered and total leukocytes acquired. Multicolor FCM was performed using specific gating strategies based on light scatter properties, differential expression of CD45 and cell lineage markers to discriminate leukocytes from squamous epithelial cells and debris. RESULTS The combination of forward scatter and CD45 expression reliably segregated sputum leukocytes from contaminating squamous epithelial cells and debris. Overlap of major leukocyte populations (neutrophils, macrophages/monocytes) required the use of specific antibodies (e.g. CD16, CD64, CD14, HLA-DR) that differentiated granulocytes from monocytes and macrophages. These gating strategies allowed identification of small populations of eosinophils, CD11c+ myeloid dendritic cells, B-cells and natural killer cells. CONCLUSIONS Multicolor FCM can be successfully applied to sputum samples to identify and characterize leukocyte populations residing on the surfaces of the central airways. CLINICAL RELEVANCE This research describes detailed methods to overcome difficulties associated with FCM of sputum samples, which previously has been lacking in the literature. FCM of sputum samples can provide valuable information on inflammation and immunological response elements in the bronchial airways for both clinical diagnostic and research applications and can be a useful tool in inhalation toxicology for assessing health effects of inhaled environmental pollutants.
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Affiliation(s)
- John C Lay
- Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina School of Medicine, Chapel Hill, USA.
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Strassburg A, Luers A, Dalhoff K. Decreased apoptosis of pulmonary PMN in COPD patients with community-acquired pneumonia. CLINICAL RESPIRATORY JOURNAL 2010; 4:111-9. [PMID: 20565485 DOI: 10.1111/j.1752-699x.2009.00157.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Chronic obstructive pulmonary disease (COPD) predisposes for the acquisition of community-acquired pneumonia (CAP). OBJECTIVE/METHODS To assess clinically and scientifically suggested disorders in innate immune response during acute phrase and resolution CAP (T2), we evaluated peripheral and pulmonary polymorphnuclear neutrophils (PMN), recovered by induced sputum, from CAP patients with and without COPD with regard to cell activation, interleukin-8 (CXCL-8) and CXCL-8 receptor expression, and apoptosis rate. RESULTS At T1, COPD patients displayed significantly lower pulmonary PMN apoptosis rates, while total cell count, the amount of macrophages, and vital and necrotic neutrophils in sputum samples were similar between study groups. At T2, there were no differences between study groups or between pulmonary and peripheral compartment. While under systemic steroid treatment apoptosis rates of peripheral and pulmonary PMN at T1 were slightly decreased, there were no significant differences in intrapulmonary CXCL-8 levels. Regarding cell activation, no significant differences could be seen, neither in comparing study groups nor in pulmonary to peripheral PMN. CONCLUSION Elucidating the pathology of suspected disorder in innate immune response, we found decreased apoptosis rates of pulmonary neutrophils in COPD at the peak of CAP indicating an increased inflammatory response, which is independent from anti-apoptotic cytokines such as CXCL-8, severity of disease and isolation of bacteria from sputum cultures.
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Nicholas B, Skipp P, Mould R, Rennard S, Davies DE, O'Connor CD, Djukanović R. Shotgun proteomic analysis of human-induced sputum. Proteomics 2006; 6:4390-401. [PMID: 16819730 DOI: 10.1002/pmic.200600011] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Induced sputum is a readily accessible biological fluid whose composition may alter as a consequence of disease. To date, however, the proteins that routinely populate this biofluid are largely unknown, in part due to the technical difficulties in processing such mucin-rich samples. To provide a catalogue of sputum proteins, we have surveyed the proteome of human-induced sputum (sputome). A combination of 2-D gel analysis and GeLC-MS/MS allowed a total of 191 human proteins to be confidently assigned. In addition to the expected components, several hitherto unreported proteins were found to be present, including three members of the annexin family, kallikreins 1 and 11, and peroxiredoxins 1, 2 and 5. Other sets of proteins identified included four proteins previously annotated as hypothetical or conserved hypothetical. Taken together, these data represent the first extensive survey of the proteome of induced sputum and provide a platform for future identification of biomarkers of lung disease.
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Affiliation(s)
- Ben Nicholas
- Division of Infection, Inflammation and Repair, School of Medicine, Southampton General Hospital, Southampton, UK
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