PDF(Pubmed)
Abstract：
The precise etiology of inflammatory bowel diseases (IBDs) remains elusive. The Escherichia coli strain LF82 (LF82) is known to be associated with IBD, and we hypothesized that this association may be related to the chuT and shuU genes. Here we constructed a germ-free (GF) honeybee model to investigate the effects of LF82 chuT and shuU genes on the honeybee intestine and their mechanisms. The chuT and shuU gene deletion strains LF82∆chuT and LF82∆shuU were generated by CRISPR-Cas9. These strains, together with nonpathogenic E. coli MG1655 (MG1655) and wildtype LF82, were allowed to colonize the guts of GF honeybees to establish single bacterial colonization models. Intestinal permeability was assessed following the administration of a sterile Brilliant Blue (FCF) solution. Comprehensive transcriptomic and metabolomic analyses of intestinal samples indicated that MG1655 had few disadvantageous effects on honeybees. Conversely, colonization with LF82 and its gene-deletion mutants provoked pronounced activation of genes associated with innate immune pathways, stimulated defensive responses, and induced expression of genes associated with inflammation, oxidative stress, and glycosaminoglycan degradation. Crucially, the LF82∆chuT and LF82∆shuU strains perturbed host heme and iron regulation, as well as tryptophan metabolism. These findings suggest that the deletion of chuT and shuU genes in E. coli LF82 may alleviate intestinal inflammation by partially modulating tryptophan catabolism. Our study proposes that targeting iron uptake mechanisms could be a potential strategy to mitigate the virulence of IBD-associated bacteria.
摘要：
炎症性肠病（IBD）的确切病因仍然难以捉摸。已知大肠杆菌菌株LF82（LF82）与IBD有关，我们假设这种关联可能与chuT和shuU基因有关。在这里，我们构建了一个无菌（GF）蜜蜂模型，以研究LF82chuT和shuU基因对蜜蜂肠道的影响及其机制。通过CRISPR-Cas9产生了chuT和shuU基因缺失菌株LF82ΔchuT和LF82ΔshuU。这些菌株，与非致病性大肠杆菌MG1655（MG1655）和野生型LF82一起，允许定植GF蜜蜂的肠道，以建立单细菌定植模型。在施用无菌亮蓝(FCF)溶液后评估肠渗透性。肠道样品的综合转录组和代谢组分析表明，MG1655对蜜蜂几乎没有不利影响。相反，LF82及其基因缺失突变体的定植引起与先天免疫途径相关的基因的明显激活，刺激的防御反应，并诱导与炎症相关的基因表达，氧化应激，和糖胺聚糖降解。至关重要的是，LF82ΔchuT和LF82ΔshuU菌株扰乱了宿主血红素和铁的调节，以及色氨酸代谢。这些发现表明，大肠杆菌LF82中chuT和shuU基因的缺失可能通过部分调节色氨酸分解代谢来减轻肠道炎症。我们的研究表明，靶向铁摄取机制可能是减轻IBD相关细菌毒力的潜在策略。
