Human Biology, Technische Universität München, Freising, Germany.
Proteomics and Bioanalytics, Technische Universität München, Freising, Germany.
PLoS One. 2018 Mar 12;13(3):e0193943. doi: 10.1371/journal.pone.0193943. eCollection 2018.
BACKGROUND & AIMS: The causes of gastrointestinal complaints in irritable bowel syndrome (IBS) remain poorly understood. Altered nerve function has emerged as an important pathogenic factor as IBS mucosal biopsy supernatants consistently activate enteric and sensory neurons. We investigated the neurally active molecular components of such supernatants from patients with IBS and quiescent ulcerative colitis (UC).
Effects of supernatants from 7 healthy controls (HC), 20 IBS and 12 UC patients on human and guinea pig submucous neurons were studied with neuroimaging techniques. We identify differentially expressed proteins with proteome analysis.
Nerve activation by IBS supernatants was prevented by the protease activated receptor 1 (PAR1) antagonist SCHE79797. UC supernatants also activated enteric neurons through protease dependent mechanisms but without PAR1 involvement. Proteome analysis of the supernatants identified 204 proteins, among them 17 proteases as differentially expressed between IBS, UC and HC. Of those the four proteases elastase 3a, chymotrypsin C, proteasome subunit type beta-2 and an unspecified isoform of complement C3 were significantly more abundant in IBS compared to HC and UC supernatants. Of eight proteases, which were upregulated in IBS, the combination of elastase 3a, cathepsin L and proteasome alpha subunit-4 showed the highest prediction accuracy of 98% to discriminate between IBS and HC groups. Elastase synergistically potentiated the effects of histamine and serotonin-the two other main neuroactive substances in the IBS supernatants. A serine protease inhibitor isolated from the probiotic Bifidobacterium longum NCC2705 (SERPINBL), known to inhibit elastase-like proteases, prevented nerve activation by IBS supernatants.
Proteases in IBS and UC supernatants were responsible for nerve activation. Our data demonstrate that proteases, particularly those signalling through neuronal PAR1, are biomarker candidates for IBS, and protease profiling may be used to characterise IBS.
肠易激综合征（IBS）的胃肠道症状的病因仍知之甚少。神经功能改变已成为一个重要的致病因素，因为 IBS 黏膜活检上清液始终激活肠和感觉神经元。我们研究了来自 IBS 和静止期溃疡性结肠炎（UC）患者的此类上清液的具有神经活性的分子成分。
采用神经影像学技术研究来自 7 例健康对照（HC）、20 例 IBS 和 12 例 UC 患者的上清液对人及豚鼠黏膜下神经元的影响。我们采用蛋白质组学分析鉴定差异表达蛋白。
IBS 上清液通过蛋白酶激活受体 1（PAR1）拮抗剂 SCHE79797 可预防神经激活。UC 上清液也通过依赖蛋白酶的机制激活肠神经元，但不涉及 PAR1。上清液的蛋白质组学分析鉴定了 204 种蛋白，其中 17 种蛋白酶在 IBS、UC 和 HC 之间差异表达。在这些蛋白酶中，弹性蛋白酶 3a、糜蛋白酶 C、蛋白酶体亚基β-2 和补体 C3 的一个未指定同工型在 IBS 上清液中明显比 HC 和 UC 上清液更丰富。在 IBS 中上调的 8 种蛋白酶中，弹性蛋白酶 3a、组织蛋白酶 L 和蛋白酶体 α 亚基-4 的组合对区分 IBS 和 HC 组具有最高的预测准确性（98%）。弹性蛋白酶协同增强了组胺和 5-羟色胺（IBS 上清液中的两种其它主要神经活性物质）的作用。从益生菌双歧杆菌 NCC2705 中分离出的一种丝氨酸蛋白酶抑制剂（SERPINBL），已知可抑制弹性蛋白酶样蛋白酶，可预防 IBS 上清液引起的神经激活。
IBS 和 UC 上清液中的蛋白酶负责神经激活。我们的数据表明，蛋白酶，特别是通过神经元 PAR1 信号的蛋白酶，是 IBS 的生物标志物候选物，并且蛋白酶谱分析可用于表征 IBS。
