Department of Clinical Science, Laboratory of Clinical Biochemistry, University of Bergen, Laboratory Building, 9th Floor, Jonas Lies veg 87, 5021, Bergen, Norway.
Bevital AS, Jonas Lies veg 87, 5021, Bergen, Norway.
Sci Rep. 2022 May 6;12(1):7426. doi: 10.1038/s41598-022-11520-1.
Protein biomarkers and microheterogeneity have attracted increasing attention in epidemiological and clinical research. Knowledge of within-person reproducibility over time is paramount to determine whether a single measurement accurately reflects an individual's long-term exposure. Yet, research investigating within-person reproducibility for proteoforms is limited. We investigated the reproducibility of the inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), and calprotectin (S100A8/9), and the renal function marker cystatin C (CnC) using a novel immuno-MALDI-TOF MS assay. Reproducibility, expressed as intraclass correlation coefficient (ICC), was calculated for 16 proteoforms using plasma samples of the Western Norway B Vitamin Intervention Trial (WENBIT) cohort collected 1-3 y apart from 295 stable angina pectoris (SAP) patients and 16 weeks apart from 38 subjects of the Intervention with Omega Fatty Acids in High-risk Patients with Hypertriglyceridemic Waist (OMEGA) trial with abdominal obesity but no other documented co-morbidities. ICCs for inflammatory markers were lower in WENBIT (CRP: 0.51, SAAt: 0.38, S100At: 0.31) compared to OMEGA subjects (CRP: 0.71, SAAt: 0.73, S100At: 0.48), while comparable for CnCt (WENBIT: 0.69, OMEGA: 0.67). Excluding SAP patients with elevated inflammation (CRP > 10 µg/ml) increased the ICC of SAAt to 0.55. Reduction of the time interval from 3 to 1 y in WENBIT group increased ICCs for all proteoforms. With a few exceptions ICCs did not differ between proteoforms of the same biomarker. ICCs were highest in OMEGA subjects with fair-to-good reproducibility for all markers. Reproducibility of SAA and S100A8/9 proteoforms in the WENBIT cohort was related to inflammation. This work will inform future clinical and epidemiological research which relies on single time point biomarker assessment to investigate inflammation and renal function.
蛋白质生物标志物和微观异质性在流行病学和临床研究中受到越来越多的关注。了解个体随时间的内在可重复性对于确定单次测量是否准确反映个体的长期暴露至关重要。然而，目前针对蛋白形式的个体内可重复性研究有限。我们使用新型免疫-MALDI-TOF MS 测定法，研究了炎症标志物 C 反应蛋白 (CRP)、血清淀粉样蛋白 A (SAA) 和钙卫蛋白 (S100A8/9) 以及肾功能标志物胱抑素 C (CnC) 的可重复性。使用来自西方挪威维生素 B 干预试验 (WENBIT) 队列的血浆样本，我们计算了 295 例稳定型心绞痛 (SAP) 患者在 1-3 年内和 38 例腹部肥胖但无其他已确诊合并症的干预性 Omega 脂肪酸高危高甘油三酯血症患者 (OMEGA) 试验中每隔 16 周采集的 16 种蛋白形式的重复性，以组内相关系数 (ICC) 表示。与 OMEGA 组相比，WENBIT 组的炎症标志物 ICC 较低 (CRP：0.51，SAAt：0.38，S100At：0.31)，而 CnCt 相似 (WENBIT：0.69，OMEGA：0.67)。排除 CRP 升高 (>10 µg/ml) 的 SAP 患者后，SAAt 的 ICC 增加到 0.55。WENBIT 组将时间间隔从 3 年缩短至 1 年，所有蛋白形式的 ICC 均增加。除了几个例外，同一生物标志物的蛋白形式之间的 ICC 没有差异。OMEGA 组的 ICC 最高，所有标志物的可重复性均为良好至中等。WENBIT 队列中 SAA 和 S100A8/9 蛋白形式的可重复性与炎症有关。这项工作将为未来的临床和流行病学研究提供信息，这些研究依赖于单次生物标志物评估来研究炎症和肾功能。
