Avery Ellen G, Haag Lea-Maxie, McParland Victoria, Kedziora Sarah M, Zigra Gabriel J, Valdes Daniela S, Kirchner Marieluise, Popp Oliver, Geisberger Sabrina, Nonn Olivia, Karlsen Tine V, N'Diaye Gabriele, Yarritu Alex, Bartolomaeus Hendrik, Bartolomaeus Theda U P, Tagiyeva Nurana A, Wimmer Moritz I, Haase Nadine, Zhang Yiming D, Wilhelm Andreas, Grütz Gerald, Tenstad Olav, Wilck Nicola, Forslund Sofia K, Klopfleisch Robert, Kühl Anja A, Atreya Raja, Kempa Stefan, Mertins Philipp, Siegmund Britta, Wiig Helge, Müller Dominik N
Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
Experimental and Clinical Research Center, a Cooperation of Charité-Universitätsmedizin Berlin and Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Cardiovasc Res. 2025 May 23;121(5):803-816. doi: 10.1093/cvr/cvae267.
The gastrointestinal (GI) tract is composed of distinct sub-regions, which exhibit segment-specific differences in microbial colonization and (patho)physiological characteristics. Gut microbes can be collectively considered as an active endocrine organ. Microbes produce metabolites, which can be taken up by the host and can actively communicate with the immune cells in the gut lamina propria with consequences for cardiovascular health. Variation in bacterial load and composition along the GI tract may influence the mucosal microenvironment and thus be reflected its interstitial fluid (IF). Characterization of the segment-specific microenvironment is challenging and largely unexplored because of lack of available tools.
Here, we developed methods, namely tissue centrifugation and elution, to collect IF from the mucosa of different intestinal segments. These methods were first validated in rats and mice, and the tissue elution method was subsequently translated for use in humans. These new methods allowed us to quantify microbiota-derived metabolites, mucosa-derived cytokines, and proteins at their site-of-action. Quantification of short-chain fatty acids showed enrichment in the colonic IF. Metabolite and cytokine analyses revealed differential abundances within segments, often significantly increased compared to plasma, and proteomics revealed that proteins annotated to the extracellular phase were site-specifically identifiable in IF. Lipopolysaccharide injections in rats showed significantly higher ileal IL-1β levels in IF compared to the systemic circulation, suggesting the potential of local as well as systemic effect.
Collection of IF from defined segments and the direct measurement of mediators at the site-of-action in rodents and humans bypasses the limitations of indirect analysis of faecal samples or serum, providing direct insight into this understudied compartment.
胃肠道由不同的亚区域组成，这些亚区域在微生物定植和（病理）生理特征方面表现出特定节段的差异。肠道微生物可被视为一个活跃的内分泌器官。微生物产生代谢产物，这些代谢产物可被宿主吸收，并能与肠道固有层中的免疫细胞进行积极交流，从而影响心血管健康。胃肠道细菌载量和组成的变化可能会影响黏膜微环境，进而反映在其组织间液（IF）中。由于缺乏可用工具，对特定节段微环境的表征具有挑战性且很大程度上未被探索。
在此，我们开发了组织离心和洗脱等方法，从不同肠段的黏膜收集组织间液。这些方法首先在大鼠和小鼠中得到验证，随后组织洗脱方法被转化应用于人类。这些新方法使我们能够在作用部位对微生物衍生的代谢产物、黏膜衍生的细胞因子和蛋白质进行定量。短链脂肪酸的定量显示结肠组织间液中含量丰富。代谢产物和细胞因子分析揭示了各节段内丰度的差异，与血浆相比通常显著增加，蛋白质组学显示注释为细胞外相的蛋白质在组织间液中可位点特异性识别。大鼠注射脂多糖后显示，与全身循环相比，回肠组织间液中白细胞介素-1β水平显著更高，表明存在局部和全身效应的潜力。
从特定节段收集组织间液，并直接在啮齿动物和人类的作用部位测量介质，绕过了粪便样本或血清间接分析的局限性，为深入了解这个研究不足的隔室提供了直接视角。
