Tryptophan derivatives in EHEC pathogenesis

EHEC 发病机制中的色氨酸衍生物

• 批准号: 10596380
• 负责人: VANESSA SPERANDIO
• 金额: $ 48.49万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-08 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10596380
• 关键词: Anabolism; Animal Model; Bacteria; Behavioral; Binding; Blood flow; Brain; Cells; Chemical Structure; Chemicals; Chlorides; Citrobacter rodentium; Colitis; Colon; Communication; Cues; Disease; Engineering; Enterochromaffin Cells; Enterocytes; Environment; Enzymes; Epithelial Cells; Escherichia coli EHEC; Excision; Gastrointestinal Diseases; Gastrointestinal tract structure; Gene Expression; Genes; Genetic Transcription; Grant; Human; Hyperplasia; Immune response; Indoles; Infection; Intestinal Mucosa; Intestines; Knockout Mice; Lamina Propria; Lesion; Mediating; Membrane; Modeling; Mus; Muscle Contraction; Names; Neurotransmitters; Nucleic Acid Regulatory Sequences; Orphan; Pathogenesis; Pathogenicity Island; Pharmacology; Phosphoric Monoester Hydrolases; Phosphotransferases; Physiology; Potassium; Process; Receptor Signaling; Regulation; Role; Serotonin; Serotonin Agonists; Shiga Toxin; Signal Pathway; Signal Transduction; Signaling Molecule; Smooth Muscle; Source; Study models; Tissues; Tryptophan; Tryptophan 5-monooxygenase; Tryptophanase; Virulence; arm; disease prognosis; enteric pathogen; gastrointestinal; gut inflammation; gut-brain axis; host microbiota; host-microbe interactions; in vivo; in vivo Model; inhibitor; intestinal barrier; intestinal epithelium; microbiota; mouse model; novel; pathogen; protein-histidine kinase; receptor; renal damage; response; reuptake; serotonin receptor; transcriptome

PROJECT SUMMARY The colon contains tryptophan derivatives such as indole, which is a microbiota-derived signaling molecule, and the host-derived serotonin neurotransmitter that is primarily synthesized in the GI tract. Indole is also known to be absorbed by host cells and helps strengthen the integrity of the intestinal barrier, being regarded as a beneficial chemical cue within microbial/host interactions. Indole is synthesized by tryptophanase, which is encoded by the tnaA gene. We have shown that the concentration of indole is significantly higher in the lumen of the colon (the compartment where the microbiota resides) compared to colonic tissues (where indole is absorbed by intestinal epithelial cells). Serotonin is synthesized in enterochromaffin cells by the enzyme tryptophan hydroxylase (TpH1). Upon its synthesis, serotonin is released into the lamina propria and is secreted into the lumen. Serotonin signaling in the intestinal mucosa is terminated by removal of serotonin by the serotonin selective reuptake transporter (SERT), which is expressed by epithelial cells. We showed that both serotonin and indole converge to decrease virulence gene expression from enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium, a murine pathogen employed as a surrogate animal model for EHEC. We also identified the bacterial receptor for these signals as CpxA. Upon sensing serotonin and/or indole, CpxA functions primarily as a phosphatase, dephosphorylating itself and CpxR, that activates virulence in its phosphorylated state. Through transcriptome studies we also identified the Indole Sequestering Receptor (Isr), which in the absence of indole directly activates virulence expression. However, in the presence of indole, Isr is no longer able to activate transcription of virulence genes. Using TpH1 pharmacological inhibitors (decrease the levels of serotonin in the gut) and SERT knockout mice (have increased levels of luminal serotonin), we showed that the presence of higher levels of serotonin in the intestine of mice decreased virulence in C. rodentium, while decreased levels of serotonin are conducive to increased pathogenesis. Moreover, we synthetically altered the concentration of indole in the GI tract of mice. This allowed us to assess the role of self-produced versus microbiota-produced indole, and show that decreased indole concentrations promote bacterial pathogenesis, while increased levels of indole decreases bacterial virulence gene expression during murine infection. Altogether, both serotonin and indole decrease virulence of C. rodentium during murine infection. Our studies show that fluctuations in the levels of indole and the serotonin neurotransmitter significantly impact disease prognosis. However several questions regarding this exquisite signaling regulation of bacterial virulence remain unanswered. Consequently the specific aims of this grant are: Aim 1. Define the CpxA/CpxR and Isr serotonin/indole signaling cascade. Aim 2. Investigate the intersection of serotonin with endogenous and exogenous indole signaling in bacterial pathogenesis during mammalian infection.

项目概要 结肠含有色氨酸衍生物，例如吲哚，这是一种源自微生物群的信号分子，并且 宿主衍生的血清素神经递质，主要在胃肠道中合成。吲哚还被称为 被宿主细胞吸收，有助于增强肠道屏障的完整性，被认为是 微生物/宿主相互作用中有益的化学线索。吲哚是由色氨酸酶合成的，色氨酸酶是 由 tnaA 基因编码。我们已经表明，吲哚的浓度在管腔中明显较高 结肠（微生物群所在的区室）与结肠组织（其中吲哚是 被肠上皮细胞吸收）。血清素由肠嗜铬细胞中的酶合成 色氨酸羟化酶（TpH1）。合成后，血清素被释放到固有层并被分泌 进入管腔。肠粘膜中的血清素信号传导通过去除血清素而终止。 血清素选择性再摄取转运蛋白（SERT），由上皮细胞表达。我们证明了两者 血清素和吲哚共同降低肠出血性大肠杆菌 (EHEC) 的毒力基因表达 啮齿类柠檬酸杆菌，一种用作肠出血性大肠杆菌替代动物模型的鼠类病原体。我们也 鉴定出这些信号的细菌受体为 CpxA。检测到血清素和/或吲哚后，CpxA 主要作为磷酸酶发挥作用，使自身和 CpxR 去磷酸化，从而激活其毒力 磷酸化状态。通过转录组研究，我们还鉴定了吲哚螯合受体（Isr）， 在没有吲哚的情况下，它直接激活毒力表达。然而，在吲哚存在的情况下，Isr 不再能够激活毒力基因的转录。使用TpH1药物抑制剂（减少 肠道中血清素水平）和 SERT 基因敲除小鼠（管腔血清素水平增加），我们证明 小鼠肠道中血清素水平较高会降低啮齿类弯曲杆菌的毒力， 而血清素水平降低则有利于发病加重。此外，我们综合 改变小鼠胃肠道中吲哚的浓度。这使我们能够评估自制产品的作用 与微生物群产生的吲哚相比，并表明吲哚浓度降低会促进细菌 发病机制，而吲哚水平的增加会降低小鼠体内细菌毒力基因的表达 感染。总而言之，血清素和吲哚都会降低鼠类感染过程中啮齿类梭菌的毒力。我们的 研究表明，吲哚和血清素神经递质水平的波动会显着影响 疾病预后。然而，关于细菌这种精致的信号调节的几个问题 毒力仍未得到解答。因此，这笔赠款的具体目标是： 目标 1. 定义 CpxA/CpxR 和 Isr 血清素/吲哚信号级联。目标 2. 研究血清素与内源性的交叉点 和哺乳动物感染期间细菌发病机制中的外源吲哚信号传导。