Department of Medicine, University of Colorado, Aurora, Colorado, United States.
Department of Immunology and Genomic Medicine, National Jewish Health, Denver, Colorado, United States.
Am J Physiol Lung Cell Mol Physiol. 2024 Nov 1;327(5):L807-L813. doi: 10.1152/ajplung.00054.2024. Epub 2024 Oct 8.
Bronchoalveolar lavage (BAL) is used by researchers to study molecular interactions within healthy and diseased human lungs. However, the utility of BAL fluid measurements may be limited by difficulties accounting for dilution of the epithelial lining fluid (ELF) sampled and inconsistent collection techniques. The use of endogenous markers to estimate ELF dilution has been proposed as a potential method to normalize acellular molecule measurements in BAL fluid, but these markers are also imperfect and prone to inaccuracy. The focus of this report is to review factors that affect the interpretation of acellular molecule measurements in lung ELF and present original data comparing the performance of several BAL dilution markers during health and in a human endobronchial endotoxin challenge model of acute inflammation. Our findings suggest that incomplete ELF and lavage fluid mixing, flux of markers across the alveolar barrier, and lung inflammation are all possible factors that can affect marker performance. Accounting for these factors, we show that commonly used markers including urea, total protein, albumin, and immunoglobulin M are likely unreliable BAL dilution markers. In contrast, surfactant protein D appears to be less affected by these factors and may be a more accurate and biologically plausible marker to improve the reproducibility of acellular BAL component measurements across individuals during health and inflammatory states. In this report, mathematical prediction models and real-world measurements are used to compare the performance of molecular markers of dilution in bronchoalveolar lavage fluid samples. Effects of acute inflammation within individual subjects are highlighted. These findings inform recommendations for normalizing measurements across bronchoalveolar lavage samples and highlight the need for additional markers to improve the rigor of translational studies utilizing bronchoalveolar lavage measurements.
支气管肺泡灌洗 (BAL) 被研究人员用于研究健康和患病人体肺部内的分子相互作用。然而，BAL 液测量的实用性可能受到难以解释上皮衬里液 (ELF) 采样稀释和不一致的采集技术的限制。使用内源性标志物来估计 ELF 稀释已被提议作为一种标准化 BAL 液中无细胞分子测量的潜在方法，但这些标志物也不完美，容易出现不准确。本报告的重点是综述影响肺 ELF 中无细胞分子测量解释的因素，并提供比较几种 BAL 稀释标志物在健康和人支气管内内毒素挑战急性炎症模型中的表现的原始数据。我们的研究结果表明，不完全的 ELF 和灌洗液混合、标志物穿过肺泡屏障的通量以及肺部炎症都是可能影响标志物性能的因素。考虑到这些因素，我们表明，包括尿素、总蛋白、白蛋白和免疫球蛋白 M 在内的常用标志物可能是不可靠的 BAL 稀释标志物。相比之下，表面活性剂蛋白 D 似乎受这些因素的影响较小，可能是一种更准确和生物学上合理的标志物，可以提高健康和炎症状态下个体间无细胞 BAL 成分测量的重现性。在本报告中，使用数学预测模型和真实测量来比较支气管肺泡灌洗液样本中稀释分子标志物的性能。突出了个体内急性炎症的影响。这些发现为标准化支气管肺泡灌洗样本中的测量提供了建议，并强调需要额外的标志物来提高利用支气管肺泡灌洗测量进行转化研究的严谨性。
