Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Diseases, Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China.
The University of Queensland Diamantina Institute, Faculty of Medicine, Brisbane, Australia; APC Microbiome Ireland, University College Cork, Cork, Ireland.
Gastroenterology. 2021 Jan;160(1):317-330.e11. doi: 10.1053/j.gastro.2020.09.036. Epub 2020 Oct 2.
BACKGROUND & AIMS: Proteus spp, Gram-negative facultative anaerobic bacilli, have recently been associated with Crohn's disease (CD) recurrence after intestinal resection. We investigated the genomic and functional role of Proteus as a gut pathogen in CD.
Proteus spp abundance was assessed by ure gene-specific polymerase chain in 54 pairs of fecal samples and 101 intestinal biopsies from patients with CD and healthy controls. The adherence, invasion, and intracellular presence of 2 distinct isolates of Proteus mirabilis in epithelial cells were evaluated using immunofluorescence and electron microscopy. Intracellular gene expression profiles and regulated pathways were analyzed by RNA sequencing and KEGG pathway analysis. Biologic functions of 2 isolates of P mirabilis were determined by in vitro cell culture, and in vivo using conventional mice and germ-free mice.
Proteus spp were significantly more prevalent and abundant in fecal samples and colonic tissue of patients with CD than controls. A greater abundance of the genus Fusobacterium and a lesser abundance of the genus Faecalibacterium were seen in patients with CD with a high Proteus spp abundance. All 24 Proteus monoclones isolated from patients with CD belonged to members of P mirabilis lineages and 2 isolates, recovered from stool or mucosa, were used in further studies. Mice gavaged with either P mirabilis strain had more severe colonic inflammation. Co-culture of the isolates with epithelial cell lines showed bacterial adherence, invasion, increased production of pro-inflammatory cytokines IL-18 and IL-1α, and cell necrosis. Both isolates induced key pro-inflammatory pathways, including NOD-like receptor signaling, Jak-STAT signaling, and MAPK signaling, and induced pro-inflammatory genes and activated inflammation-related pathways in gnotobiotic mice.
P mirabilis in the gut is associated with CD and can induce inflammation in cells and animal models of colitis. P mirabilis can act as a pathobiont and play a crucial role in the pathogenesis of CD.
普罗透斯菌属是革兰氏阴性兼性需氧杆菌，最近与肠切除术后克罗恩病（CD）的复发有关。我们研究了普罗透斯菌作为 CD 肠道病原体的基因组和功能作用。
通过粪便样本和 CD 患者和健康对照者的 101 个肠活检样本中 ure 基因特异性聚合酶链反应评估普罗透斯菌属丰度。使用免疫荧光和电子显微镜评估 2 种不同的奇异变形杆菌分离株在肠上皮细胞中的粘附、侵袭和细胞内存在情况。通过 RNA 测序和 KEGG 途径分析分析细胞内基因表达谱和调控途径。通过体外细胞培养和常规小鼠和无菌小鼠体内实验确定 2 种奇异变形杆菌分离株的生物学功能。
与对照组相比，CD 患者粪便样本和结肠组织中的普罗透斯菌属明显更为普遍和丰富。在 CD 患者中，丰度较高的梭菌属和丰度较低的粪杆菌属与高丰度的普罗透斯菌属有关。从 CD 患者中分离出的 24 个普罗透斯单克隆均属于奇异变形杆菌系，从粪便或粘膜中分离出的 2 个分离株用于进一步研究。用任一奇异变形杆菌株灌胃的小鼠均有更严重的结肠炎症。将这些分离株与肠上皮细胞系共培养显示细菌粘附、侵袭、促炎细胞因子 IL-18 和 IL-1α 的产生增加以及细胞坏死。这两种分离株均诱导关键的促炎途径，包括 NOD 样受体信号、Jak-STAT 信号和 MAPK 信号，并在无菌小鼠中诱导促炎基因和激活炎症相关途径。
肠道中的奇异变形杆菌与 CD 有关，并可在细胞和结肠炎动物模型中引起炎症。奇异变形杆菌可以作为条件致病菌在 CD 的发病机制中发挥关键作用。
