Project description:Neural circuits driving mammalian behaviors are highly plastic and modulated by internal and external factors, including the gut microbiome. We identify imidazole propionate (ImP), a microbial metabolite linked to metabolic disorders, as a key modulator of brain activity and behavior. Bacterially derived ImP enters the systemic circulation and brain, where it alters neuronal gene expression and activity in the hypothalamus without inducing overt neuroinflammation. Elevating systemic ImP promotes stress-related pathways and disrupts GABAergic/glutamatergic signaling in the hypothalamus before peripheral glucose dysregulation occurs. Similarly, colonization with the ImP-producing bacterium Eggerthella lenta elevates behavioral and molecular features of stress. In a mouse model of type 2 diabetes, the gut microbiome exhibits an enhanced ability to produce ImP, leading to elevated systemic levels that are associated with heightened stress responses. In humans, higher ImP associates with reduced hypothalamic reactivity to food cues, impaired stress-coping, and increased emotional eating, mirroring the causal links between ImP, hypothalamic activity, and stress-related behaviors in mice. Overall, these findings establish ImP as a notable microbial metabolite that links gut dysbiosis to altered hypothalamic function and stress in metabolic disease.
Project description:Atherosclerosis is the main underlying cause of cardiovascular diseases (CVDs). Its prevention is based on traditional cardiovascular risk factor-based scores but often fails to identify individuals at early stages of the disease. Here, we identified microbially produced imidazole propionate (ImP) as an early biomarker of atherosclerosis in mice and in two independent human cohorts. Furthermore, ImP administration induced atherosclerosis without altering lipid metabolism and it was associated with activation of both systemic and local innate and adaptive immunity and inflammation. Here, we used single-cell RNA-seq to characterize the local changes of aorta-derived cells in mice under treatment with ImP for 4 and 8 weeks. Notably, ImP caused atherosclerosis through the Imidazoline-1 receptor (I1R), and the blockade of the ImP/I1R axis inhibited the development of atherosclerosis induced by ImP as well as by high cholesterol diet in mice. Identification of ImP as an early biomarker for atherosclerosis and uncovering the contribution of the ImP/I1R axis in disease progression open new avenues to improve atherosclerosis early diagnosis and therapy.
Project description:Atherosclerosis is the main underlying cause of cardiovascular diseases (CVDs). Its prevention is based on traditional cardiovascular risk factor-based scores but often fails to identify individuals at early stages of the disease. Here, we identified microbially produced imidazole propionate (ImP) as an early biomarker of atherosclerosis in mice and in two independent human cohorts. Furthermore, ImP administration induced atherosclerosis without altering lipid metabolism and it was associated with activation of both systemic and local innate and adaptive immunity and inflammation. Notably, ImP caused atherosclerosis through the Imidazoline-1 receptor (I1R), and the blockade of the ImP/I1R axis inhibited the development of atherosclerosis induced by ImP as well as by high cholesterol diet in mice. Here, we profiled three cell lines which represent cell types typically found in aortas (bone marrow-derived macrophages, mouse embryonic fibroblasts and mouse aortic endothelial cells) upon in vitro stimulation with ImP at different time points to better understand the transcriptional regulation of the ImP/I1R axis and its role in the development of the disease. Identification of ImP as an early biomarker for atherosclerosis and uncovering the contribution of the ImP/I1R axis in disease progression open new avenues to improve atherosclerosis early diagnosis and therapy.
Project description:The hypothalamus is a central regulator of many behaviors essential for survival such as temperature regulation, food intake and circadian rhythms. However, the molecular pathways that mediate hypothalamic development are largely unknown. To identify genes expressed in developing mouse hypothalamus, microarray analysis at 12 different developmental time points was performed. Developmental in situ hybridization was conducted for 1,045 genes dynamically expressed by microarray analysis. In this way, we identified markers that stably labeled each major hypothalamic nucleus over the entire course of neurogenesis, and thus constructed a detailed molecular atlas of the developing hypothalamus. As proof of concept for the utility of this data, we used these markers to analyze the phenotype of mice where Sonic Hedgehog (Shh) was selectively deleted from hypothalamic neuroepithelium, demonstrating an essential role for Shh in anterior hypothalamic patterning. Our results serve as a resource for functional investigations of hypothalamic development, connectivity, physiology, and dysfunction. Affymetrix MOE430 microarrays were used to analyze the expression patterns of mouse hypothalamic and preoptic area tissues. The results were compared across the variables of Strain, Sex and Age.
Project description:Background & aimsCirculating levels of imidazole propionate (ImP), a microbial metabolite of histidine, were higher in participants with type 2 diabetes (T2D) compared to those without and also induced insulin resistance. We hypothesize that low intake of magnesium (Mg) and/or low body Mg status in humans may lead to low Mg concentrations in gut microbiota, and, in turn, elevated microbial production of ImP and increased levels of circulating ImP.MethodsWe tested this hypothesis in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (registered at clinicaltrials.gov as NCT01105169), a double-blind 2 × 2 factorial randomized controlled trial enrolling 240 participants at high risk of Mg deficiency. Among 68 participants (34 each in the treatment and placebo arms), we measured plasma metabolites using the untargeted Metabolon's global Precision Metabolomics™ LC-MS platform.ResultsMg treatment significantly reduced ImP by 39.9% compared to a 6.0% increase in the placebo arm (P = 0.02). We found the correlation coefficients were -0.12 (P = 0.32) and -0.31 (P < 0.01) between the change in ImP and changes in serum Mg and urinary Mg, respectively. In addition, we found Mg treatment increased circulating levels of propionic acid (InP) by 27.5% (P = 0.07) and reduced levels of glutarate by 17.9% (P = 0.04) compared to the placebo arm.ConclusionsFurther studies are needed to replicate these findings and to investigate whether Mg treatment specifically changes the production of ImP by microbiota. Also, future studies are warranted to confirm the effect of Mg treatment on glutarate and InP.
Project description:To better understand the epigenetic mechanism underlying pubertal onset, the hypothalamic genome-wide chromatin accessibility patterns in mouse arcuate nucleus at early and late pubertal stages were explored. Female mice have been widely used in multiple studies on pubertal development as they present the similar molecular behaviors in HPG axis and stable cycles of menstrual calendar like human. Hypothalamic ARC underwent a huge epigenetic and genetic reprogramming to adapt to the response and feedback on sexual hormones during the stages of early pubertal (2-5-week of age) and late puberty (5-8-week of age) . We harvested 4- and 8-week hypothalamic ARC and employed ATAC-seq on a genome-wide scale. Combined with previous RRBS, RRHP and RNA-seq, the connections between DNA (hydroxyl)methylation in retroelements and gene expression were studied, emphasizing the importance of epigenetic alterations in regulating transcription in puberty onset.