Abstract：
BACKGROUND: Aspiration pneumonia (AP), which is a major cause of death in the elderly, does present with typical symptoms in the early stages of onset, thus it is difficult to detect and treat at an early stage. In this study, we identified biomarkers that are useful for the detection of AP and focused on salivary proteins, which may be collected non-invasively. Because expectorating saliva is often difficult for elderly people, we collected salivary proteins from the buccal mucosa.
METHODS: We collected samples from the buccal mucosa of six patients with AP and six control patients (no AP) in an acute-care hospital. Following protein precipitation using trichloroacetic acid and washing with acetone, the samples were analyzed by liquid chromatography and tandem mass spectrometry (LC-MS/MS). We also determined the levels of cytokines and chemokines in non-precipitated samples from buccal mucosa.
RESULTS: Comparative quantitative analysis of LC-MS/MS spectra revealed 55 highly (P values < 0.10) abundant proteins with high FDR confidence (q values < 0.01) and high coverage (> 50%) in the AP group compared with the control group. Among the 55 proteins, the protein abundances of four proteins (protein S100-A7A, eukaryotic translation initiation factor 1, Serpin B4, and peptidoglycan recognition protein 1) in the AP group showed a negative correlation with the time post-onset; these proteins are promising AP biomarker candidates. In addition, the abundance of C-reactive protein (CRP) in oral samples was highly correlated with serum CRP levels, suggesting that oral CRP levels may be used as a surrogate to predict serum CRP in AP patients. A multiplex cytokine/chemokine assay revealed that MCP-1 tended to be low, indicating unresponsiveness of MCP-1 and its downstream immune pathways in AP.
CONCLUSIONS: Our findings suggest that oral salivary proteins, which are obtained non-invasively, can be utilized for the detection of AP.
METHODS: We collected samples from the buccal mucosa of six patients with AP and six control patients (no AP) in an acute-care hospital. Following protein precipitation using trichloroacetic acid and washing with acetone, the samples were analyzed by liquid chromatography and tandem mass spectrometry (LC-MS/MS). We also determined the levels of cytokines and chemokines in non-precipitated samples from buccal mucosa.
RESULTS: Comparative quantitative analysis of LC-MS/MS spectra revealed 55 highly (P values < 0.10) abundant proteins with high FDR confidence (q values < 0.01) and high coverage (> 50%) in the AP group compared with the control group. Among the 55 proteins, the protein abundances of four proteins (protein S100-A7A, eukaryotic translation initiation factor 1, Serpin B4, and peptidoglycan recognition protein 1) in the AP group showed a negative correlation with the time post-onset; these proteins are promising AP biomarker candidates. In addition, the abundance of C-reactive protein (CRP) in oral samples was highly correlated with serum CRP levels, suggesting that oral CRP levels may be used as a surrogate to predict serum CRP in AP patients. A multiplex cytokine/chemokine assay revealed that MCP-1 tended to be low, indicating unresponsiveness of MCP-1 and its downstream immune pathways in AP.
CONCLUSIONS: Our findings suggest that oral salivary proteins, which are obtained non-invasively, can be utilized for the detection of AP.
摘要：
背景：吸入性肺炎（AP），这是老年人死亡的主要原因，在发病早期有典型的症状，因此很难在早期发现和治疗。在这项研究中,我们确定了可用于检测AP并专注于唾液蛋白的生物标志物，可以非侵入性地收集。因为对于老年人来说，吐唾液通常很困难，我们从颊粘膜收集唾液蛋白。
方法：我们在一家急诊医院收集了6名AP患者和6名对照患者（无AP）的颊粘膜样本。使用三氯乙酸沉淀蛋白质并用丙酮洗涤后，通过液相色谱和串联质谱(LC-MS/MS)分析样品。我们还测定了来自颊粘膜的非沉淀样品中细胞因子和趋化因子的水平。
结果：LC-MS/MS光谱的比较定量分析显示，与对照组相比，AP组中55种高度（P值<0.10）丰富的蛋白质具有高FDR置信度（q值<0.01）和高覆盖率（>50％）。在55种蛋白质中，四种蛋白质的蛋白质丰度(蛋白质S100-A7A，AP组中的真核翻译起始因子1，SerpinB4和肽聚糖识别蛋白1）与发病后时间呈负相关；这些蛋白质是有前途的AP生物标志物候选物。此外,口腔样本中C反应蛋白（CRP）的丰度与血清CRP水平高度相关，提示口服CRP水平可作为预测AP患者血清CRP的替代指标。多重细胞因子/趋化因子测定显示MCP-1趋于低，表明AP中MCP-1及其下游免疫途径无反应。
结论：我们的研究结果表明，口腔唾液蛋白，这些都是非侵入性的，可用于AP的检测。
方法：我们在一家急诊医院收集了6名AP患者和6名对照患者（无AP）的颊粘膜样本。使用三氯乙酸沉淀蛋白质并用丙酮洗涤后，通过液相色谱和串联质谱(LC-MS/MS)分析样品。我们还测定了来自颊粘膜的非沉淀样品中细胞因子和趋化因子的水平。
结果：LC-MS/MS光谱的比较定量分析显示，与对照组相比，AP组中55种高度（P值<0.10）丰富的蛋白质具有高FDR置信度（q值<0.01）和高覆盖率（>50％）。在55种蛋白质中，四种蛋白质的蛋白质丰度(蛋白质S100-A7A，AP组中的真核翻译起始因子1，SerpinB4和肽聚糖识别蛋白1）与发病后时间呈负相关；这些蛋白质是有前途的AP生物标志物候选物。此外,口腔样本中C反应蛋白（CRP）的丰度与血清CRP水平高度相关，提示口服CRP水平可作为预测AP患者血清CRP的替代指标。多重细胞因子/趋化因子测定显示MCP-1趋于低，表明AP中MCP-1及其下游免疫途径无反应。
结论：我们的研究结果表明，口腔唾液蛋白，这些都是非侵入性的，可用于AP的检测。
