Sequential broncho-alveolar lavages reflect distinct pulmonary compartments: clinical and research implications in lung transplantation

Liran Levy,Marcelo Cypel,Lianne G Singer,Sassan Azad,Betty Joe,Tereza Martinu,Stephen C Juvet,Shaf Keshavjee,Kristen Boonstra

doi:10.1186/s12931-018-0786-z

Liran Levy, Marcelo Cypel + Show 7 more

Open Access

https://doi.org/10.1186/s12931-018-0786-z

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Abstract

BackgroundBronchoalveolar lavage (BAL) has proven to be very useful to monitor the lung allograft after transplantation. In addition to allowing detection of infections, multiple BAL analytes have been proposed as potential biomarkers of lung allograft rejection or dysfunction. However, BAL collection is not well standardized and differences in BAL collection represent an important source of variation. We hypothesized that there are systematic differences between sequential BALs that are relevant to BAL analysis.MethodsAs part of 126 consecutive bronchoscopies in lung transplant recipients, two sequential BALs (BAL1 and BAL2) were performed in one location during each bronchoscopy by instilling and suctioning 50 ml of normal saline twice into separate containers. Cell concentration, viability and differentials, Surfactant Protein-D (SP-D), Club Cell Secretory Protein (CCSP), and levels of CXCL10, IL-10, CCL2, CCL5, VEGF-C, RAGE, CXCL9, CXCL1, IL-17A, IL-21, PDGF, and GCSF were compared between BAL1 and BAL2.ResultsTotal cell concentration did not differ between BAL1 and BAL2; however, compared to BAL2, BAL1 had more dead cells, epithelial cells, neutrophils, and higher concentrations of airway epithelium-derived CCSP and inflammatory markers. BAL2 had a higher concentration of SP-D compared to BAL1.ConclusionIn this study performed in lung transplant recipients, we show that sequential BALs represent different lung compartments and have distinct compositions. BAL1 represents the airway compartment with more epithelial cells, neutrophils, and epithelium-derived CCSP. Conversely, BAL2 samples preferentially the distal bronchoalveolar space with greater cell viability and higher SP-D. Our findings illustrate how the method of BAL collection can influence analyte concentrations and further emphasize the need for a standardized approach in translational research involving BAL samples.

Highlights

Bronchoalveolar lavage (BAL) has proven to be very useful to monitor the lung allograft after transplantation
BAL proteins have been proposed as potential biomarkers of acute rejection [3,4,5,6] and chronic lung allograft dysfunction (CLAD) [7]
The purpose of this study was to determine whether there are systematic differences between sequential BAL fractions in lung transplant patients, with a focus on cellular composition and proteins that have previously been shown to correlate with clinical outcomes in lung transplant recipients, including lymphocytes [10], neutrophils [7, 10], Surfactant Protein-D (SP-D) [11], Club Cell Secretory Protein (CCSP) [12, 13], CXCL10 [7], IL-10 [14], CCL2 [7], CCL5 [7], VEGF-C [15], RAGE [16], CXCL9 [7], CXCL1 [17], IL-17A [18], IL-21 [19], PDGF [20,21,22] and GCSF [23]

Summary

Introduction

Bronchoalveolar lavage (BAL) has proven to be very useful to monitor the lung allograft after transplantation. In addition to allowing detection of infections, multiple BAL analytes have been proposed as potential biomarkers of lung allograft rejection or dysfunction. In an attempt to create a common approach to BAL collection, BAL standardization guidelines were published by the European Respiratory Society in 1999 [2], and guidelines specific to patients with interstitial lung diseases were put forth by the American Thoracic Society in 2012 [9]. While these documents set an important precedent, they leave room for significant variability in BAL collection and processing. Neither the optimal total volume nor the number of aliquots to be instilled has been established

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