The role of the intestinal microbiota in host health is increasingly revealed in its contributions to disease states. The host-microbiome interaction is multifactorial and dynamic. One of the factors that has recently been strongly associated with host physiological responses is peptidoglycan from bacterial cell walls. Peptidoglycan from gut commensal bacteria activates peptidoglycan sensors in human cells, including the nucleotide-binding oligomerization domain-containing protein 2. When present in the gastrointestinal tract, both the polymeric form (sacculi) and depolymerized fragments can modulate host physiology, including checkpoint anticancer therapy efficacy, body temperature and appetite, and postnatal growth. To utilize this growing area of biology toward therapeutic prescriptions, it will be critical to directly analyze a key feature of the host-microbiome interaction from living hosts in a reproducible and noninvasive way. Here we show that metabolically labeled peptidoglycan/sacculi can be readily isolated from fecal samples collected from both mice and humans. Analysis of fecal samples provided a noninvasive route to probe the gut commensal community including the metabolic synchronicity with the host circadian clock. Together, these results pave the way for noninvasive diagnostic tools to interrogate the causal nature of peptidoglycan in host health and disease.

中文翻译：

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活体动物肽聚糖的无创分析

肠道微生物群在宿主健康中的作用越来越多地体现在其对疾病状态的贡献中。宿主-微生物组的相互作用是多因素的、动态的。最近与宿主生理反应密切相关的因素之一是来自细菌细胞壁的肽聚糖。来自肠道共生细菌的肽聚糖可激活人体细胞中的肽聚糖传感器，包括含有核苷酸结合寡聚化结构域的蛋白质 2。当存在于胃肠道中时，聚合形式（球囊）和解聚片段都可以调节宿主生理机能，包括检查点抗癌治疗功效、体温和食欲、产后生长。为了利用这一不断发展的生物学领域来制定治疗处方，以可重复和非侵入性的方式直接分析活体宿主与微生物组相互作用的关键特征至关重要。在这里，我们表明，代谢标记的肽聚糖/球囊可以很容易地从小鼠和人类收集的粪便样本中分离出来。粪便样本分析提供了一种非侵入性途径来探测肠道共生群落，包括与宿主生物钟的代谢同步性。总之，这些结果为非侵入性诊断工具探索肽聚糖在宿主健康和疾病中的因果性质铺平了道路。