Modasia Amisha, Parker Aimee, Jones Emily, Stentz Regis, Brion Arlaine, Goldson Andrew, Defernez Marianne, Wileman Tom, Ashley Blackshaw L, Carding Simon R
Gut Microbes and Health Research Programme, Quadram Institute Bioscience, Norwich, United Kingdom.
Core Science Resources, Quadram Institute Bioscience, Norwich, United Kingdom.
Front Microbiol. 2020 Nov 6;11:575595. doi: 10.3389/fmicb.2020.575595. eCollection 2020.
Gut microbes have critical roles in maintaining host physiology, but their effects on epithelial chemosensory enteroendocrine cells (EEC) remain unclear. We investigated the role that the ubiquitous commensal gut bacterium (Bt) and its major fermentation products, acetate, propionate, and succinate (APS) have in shaping EEC networks in the murine gastrointestinal tract (GIT). The distribution and numbers of EEC populations were assessed in tissues along the GIT by fluorescent immunohistochemistry in specific pathogen free (SPF), germfree (GF) mice, GF mice conventionalized by Bt or (Lr), and GF mice administered APS. In parallel, we also assessed the suitability of using intestinal crypt-derived epithelial monolayer cultures for these studies. GF mice up-regulated their EEC network, in terms of a general EEC marker chromogranin A (ChrA) expression, numbers of serotonin-producing enterochromaffin cells, and both hormone-producing K- and L-cells, with a corresponding increase in serum glucagon-like peptide-1 (GLP-1) levels. Bt conventionalization restored EEC numbers to levels in SPF mice with regional specificity; the effects on ChrA and L-cells were mainly in the small intestine, the effects on K-cells and EC cells were most apparent in the colon. By contrast, Lr did not restore EEC networks in conventionalized GF mice. Analysis of secretory epithelial cell monolayer cultures from whole small intestine showed that intestinal monolayers are variable and with the possible exclusion of GIP expressing cells, did not accurately reflect the EEC cell makeup seen . Regarding the mechanism of action of Bt on EECs, colonization of GF mice with Bt led to the production and accumulation of acetate, propionate and succinate (APS) in the caecum and colon, which when administered at physiological concentrations to GF mice via their drinking water for 10 days mimicked to a large extent the effects of Bt in GF mice. After withdrawal of APS, the changes in some EEC were maintained and, in some cases, were greater than during APS treatment. This data provides evidence of microbiota influences on regulating EEC networks in different regions of the GIT, with a single microbe, Bt, recapitulating its role in a process that may be dependent upon its fermentation products.
肠道微生物在维持宿主生理功能方面发挥着关键作用，但其对上皮化学感应肠内分泌细胞（EEC）的影响仍不清楚。我们研究了常见的共生肠道细菌（Bt）及其主要发酵产物乙酸盐、丙酸盐和琥珀酸盐（APS）在塑造小鼠胃肠道（GIT）中EEC网络方面所起的作用。通过荧光免疫组织化学方法，在无特定病原体（SPF）小鼠、无菌（GF）小鼠、经Bt或（Lr）定殖的GF小鼠以及给予APS的GF小鼠中，评估了沿GIT各组织中EEC群体的分布和数量。同时，我们还评估了使用肠道隐窝来源的上皮单层培养物进行这些研究的适用性。就一般EEC标志物嗜铬粒蛋白A（ChrA）的表达、产生5-羟色胺的肠嗜铬细胞数量以及产生激素的K细胞和L细胞而言，GF小鼠上调了其EEC网络，同时血清胰高血糖素样肽-1（GLP-1）水平相应升高。Bt定殖将EEC数量恢复到具有区域特异性的SPF小鼠水平；对ChrA和L细胞的影响主要在小肠，对K细胞和EC细胞的影响在结肠最为明显。相比之下，Lr并未恢复定殖的GF小鼠中的EEC网络。对来自整个小肠的分泌性上皮细胞单层培养物的分析表明，肠道单层培养物存在差异，并且在可能排除表达GIP的细胞后，不能准确反映所观察到的EEC细胞组成。关于Bt对EEC的作用机制，用Bt定殖GF小鼠导致盲肠和结肠中乙酸盐、丙酸盐和琥珀酸盐（APS）的产生和积累，当以生理浓度通过饮用水给予GF小鼠10天时，在很大程度上模拟了Bt对GF小鼠的影响。停止给予APS后，一些EEC的变化得以维持，在某些情况下，变化程度大于APS治疗期间。这些数据提供了微生物群对调节GIT不同区域EEC网络有影响的证据，单一微生物Bt在可能依赖其发酵产物的过程中重现了其作用。
