PDF(Pubmed)
Abstract：
Adherent-invasive Escherichia coli (AIEC) strain LF82, isolated from patients with Crohn\'s disease, invades gut epithelial cells, and replicates in macrophages contributing to chronic inflammation. In this study, we found that RstAB contributing to the colonization of LF82 in a mouse model of chronic colitis by promoting bacterial replication in macrophages. By comparing the transcriptomes of rstAB mutant- and wild-type when infected macrophages, 83 significant differentially expressed genes in LF82 were identified. And we identified two possible RstA target genes (csgD and asr) among the differentially expressed genes. The electrophoretic mobility shift assay and quantitative real-time PCR confirmed that RstA binds to the promoters of csgD and asr and activates their expression. csgD deletion attenuated LF82 intracellular biofilm formation, and asr deletion reduced acid tolerance compared with the wild-type. Acidic pH was shown by quantitative real-time PCR to be the signal sensed by RstAB to activate the expression of csgD and asr. We uncovered a signal transduction pathway whereby LF82, in response to the acidic environment within macrophages, activates transcription of the csgD to promote biofilm formation, and activates transcription of the asr to promote acid tolerance, promoting its replication within macrophages and colonization of the intestine. This finding deepens our understanding of the LF82 replication regulation mechanism in macrophages and offers new perspectives for further studies on AIEC virulence mechanisms.
摘要：
粘附侵袭性大肠杆菌（AIEC）菌株LF82，分离自克罗恩病患者，侵入肠道上皮细胞，并在巨噬细胞中复制导致慢性炎症。在这项研究中,我们发现RstAB通过促进巨噬细胞中的细菌复制而促进LF82在慢性结肠炎小鼠模型中的定植.通过比较感染巨噬细胞时rstAB突变体和野生型的转录组，在LF82中鉴定了83个显著差异表达的基因。并且我们在差异表达基因中鉴定了两个可能的RstA靶基因（csgD和asr）。电泳迁移率变化测定和定量实时PCR证实RstA与csgD和asr的启动子结合并激活它们的表达。csgD缺失减弱LF82细胞内生物膜形成，与野生型相比，asr缺失降低了酸耐受性。定量实时PCR显示酸性pH是RstAB检测到的激活csgD和asr表达的信号。我们发现了一条信号转导途径，即LF82响应巨噬细胞内的酸性环境，激活csgD的转录以促进生物膜的形成，并激活ASR的转录以促进酸耐受性，促进其在巨噬细胞内的复制和肠道的定植。这一发现加深了我们对巨噬细胞中LF82复制调节机制的理解，并为进一步研究AIEC毒力机制提供了新的视角。
