Esther Charles R, Hill David B, Button Brian, Shi Shuai, Jania Corey, Duncan Elizabeth A, Doerschuk Claire M, Chen Gang, Ranganathan Sarath, Stick Stephen M, Boucher Richard C
Pediatric Pulmonology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina;
Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Am J Physiol Lung Cell Mol Physiol. 2017 Mar 1;312(3):L398-L404. doi: 10.1152/ajplung.00398.2016. Epub 2017 Jan 6.
Although airway mucus dehydration is key to pathophysiology of cystic fibrosis (CF) and other airways diseases, measuring mucus hydration is challenging. We explored a robust method to estimate mucus hydration using sialic acid as a marker for mucin content. Terminal sialic acid residues from mucins were cleaved by acid hydrolysis from airway samples, and concentrations of sialic acid, urea, and other biomarkers were analyzed by mass spectrometry. In mucins purified from human airway epithelial (HAE), sialic acid concentrations after acid hydrolysis correlated with mucin concentrations ( = 0.92). Sialic acid-to-urea ratios measured from filters applied to the apical surface of cultured HAE correlated to percent solids and were elevated in samples from CF HAEs relative to controls (2.2 ± 1.1 vs. 0.93 ± 1.8, < 0.01). Sialic acid-to-urea ratios were elevated in bronchoalveolar lavage fluid (BALF) from β-epithelial sodium channel (ENaC) transgenic mice, known to have reduced mucus hydration, and mice sensitized to house dust mite allergen. In a translational application, elevated sialic acid-to-urea ratios were measured in BALF from young children with CF who had airway infection relative to those who did not (5.5 ± 3.7 vs. 1.9 ± 1.4, < 0.02) and could be assessed simultaneously with established biomarkers of inflammation. The sialic acid-to-urea ratio performed similarly to percent solids, the gold standard measure of mucus hydration. The method proved robust and has potential to serve as flexible techniques to assess mucin hydration, particularly in samples like BALF in which established methods such as percent solids cannot be utilized.
尽管气道黏液脱水是囊性纤维化（CF）和其他气道疾病病理生理学的关键因素，但测量黏液水合作用具有挑战性。我们探索了一种可靠的方法，以唾液酸作为黏蛋白含量的标志物来估计黏液水合作用。通过酸水解从气道样本中裂解黏蛋白的末端唾液酸残基，并通过质谱分析唾液酸、尿素和其他生物标志物的浓度。在从人呼吸道上皮（HAE）纯化的黏蛋白中，酸水解后的唾液酸浓度与黏蛋白浓度相关（=0.92）。从应用于培养的HAE顶端表面的滤膜测量的唾液酸与尿素的比率与固体百分比相关，并且在CF HAE的样本中相对于对照升高（2.2±1.1对0.93±1.8，<0.01）。在已知黏液水合作用降低的β-上皮钠通道（ENaC）转基因小鼠和对屋尘螨过敏原致敏的小鼠的支气管肺泡灌洗液（BALF）中，唾液酸与尿素的比率升高。在一项转化应用中，相对于未发生气道感染的CF幼儿，发生气道感染的CF幼儿的BALF中测量到唾液酸与尿素的比率升高（5.5±3.7对1.9±1.4，<0.02），并且可以与已建立的炎症生物标志物同时进行评估。唾液酸与尿素的比率与固体百分比的表现相似，固体百分比是黏液水合作用的金标准测量方法。该方法被证明是可靠的，并且有潜力作为一种灵活的技术来评估黏蛋白水合作用，特别是在无法使用诸如固体百分比等既定方法的样本（如BALF）中。
