Transinteractome analysis reveals distinct niche requirements for isotype-based plasma cell subsets in the bone marrow.

Bone marrow (BM) long-lived plasma cells (PCs) are essential for long-term protection against infection, and their persistence within this organ relies on interactions with Cxcl12-expressing stromal cells that are still not clearly identified. Here, using single cell RNAseq and in silico transinteractome analyses, we identified Leptin receptor positive (LepR ) mesenchymal cells as the stromal cell subset most likely to interact with PCs within the BM. Moreover, we demonstrated that depending on the isotype they express, PCs may use different sets of integrins and adhesion molecules to interact with these stromal cells.

Regulation of enteroendocrine cell respiration by the microbial metabolite hydrogen sulfide.

Endocrine functions of the gut are supported by a scattered population of cells, the enteroendocrine cells (EECs). EECs sense their environment to secrete hormones in a regulated manner. Distal EECs are in contact with various microbial compounds including hydrogen sulfide (HS) which modulate cell respiration with potential consequences on EEC physiology.

upregulates genes involved in maintaining the intestinal barrier function via ADP-heptose-dependent activation of the ALPK1/TIFA pathway.

The commensal bacteria that make up the gut microbiota impact the health of their host on multiple levels. In particular, the interactions taking place between the microbe-associated molecule patterns (MAMPs) and pattern recognition receptors (PRRs), expressed by intestinal epithelial cells (IECs), are crucial for maintaining intestinal homeostasis. While numerous studies showed that TLRs and NLRs are involved in the control of gut homeostasis by commensal bacteria, the role of additional innate immune receptors remains unclear.

Stimulation of motilin secretion by bile, free fatty acids, and acidification in human duodenal organoids.

Objective: Motilin is a proximal small intestinal hormone with roles in gastrointestinal motility, gallbladder emptying, and hunger initiation. In vivo motilin release is stimulated by fats, bile, and duodenal acidification but the underlying molecular mechanisms of motilin secretion remain poorly understood. This study aimed to establish the key signaling pathways involved in the regulation of secretion from human motilin-expressing M-cells.

Murine neuronatin deficiency is associated with a hypervariable food intake and bimodal obesity.

Neuronatin (Nnat) has previously been reported to be part of a network of imprinted genes downstream of the chromatin regulator Trim28. Disruption of Trim28 or of members of this network, including neuronatin, results in an unusual phenotype of a bimodal body weight. To better characterise this variability, we examined the key contributors to energy balance in Nnat mice that carry a paternal null allele and do not express Nnat.

The Human and Mouse Islet Peptidome: Effects of Obesity and Type 2 Diabetes, and Assessment of Intraislet Production of Glucagon-like Peptide-1.

To characterize the impact of metabolic disease on the peptidome of human and mouse pancreatic islets, LC-MS was used to analyze extracts of human and mouse islets, purified mouse alpha, beta, and delta cells, supernatants from mouse islet incubations, and plasma from patients with type 2 diabetes. Islets were obtained from healthy and type 2 diabetic human donors, and mice on chow or high fat diet. All major islet hormones were detected in lysed islets as well as numerous peptides from vesicular proteins including granins and processing enzymes.

Peptidomics of enteroendocrine cells and characterisation of potential effects of a novel preprogastrin derived-peptide on glucose tolerance in lean mice.

Objectives: To analyse the peptidomics of mouse enteroendocrine cells (EECs) and human gastrointestinal (GI) tissue and identify novel gut derived peptides.

Methods: High resolution nano-flow liquid chromatography mass spectrometry (LC-MS/MS) was performed on (i) flow-cytometry purified NeuroD1 positive cells from mouse and homogenised human intestinal biopsies, (ii) supernatants from primary murine intestinal cultures, (iii) intestinal homogenates from mice fed high fat diet. Candidate bioactive peptides were selected on the basis of species conservation, high expression/biosynthesis in EECs and evidence of regulated secretionin vitro.

Inhibition of mitochondrial function by metformin increases glucose uptake, glycolysis and GDF-15 release from intestinal cells.

Even though metformin is widely used to treat type2 diabetes, reducing glycaemia and body weight, the mechanisms of action are still elusive. Recent studies have identified the gastrointestinal tract as an important site of action. Here we used intestinal organoids to explore the effects of metformin on intestinal cell physiology.

Organoid Sample Preparation and Extraction for LC-MS Peptidomics.

This protocol describes the peptidomic analysis of organoid lysates, FACS-purified cell populations, and 2D culture secretions by liquid chromatography mass spectrometry (LC-MS). Currently, most peptides are quantified by ELISA, limiting the peptides that can be studied. However, an LC-MS-based approach allows more peptides to be monitored.

Production of hydrogen sulfide by the intestinal microbiota and epithelial cells and consequences for the colonic and rectal mucosa.

Among bacterial metabolites, hydrogen sulfide (HS) has received increasing attention. The epithelial cells of the large intestine are exposed to two sources of HS. The main one is the luminal source that results from specific bacteria metabolic activity toward sulfur-containing substrates.

SCFA: mechanisms and functional importance in the gut.

In recent years, the importance of the gut microbiota in human health has been revealed and many publications have highlighted its role as a key component of human physiology. Owing to the use of modern sequencing approaches, the characterisation of the microbiome in healthy individuals and in disease has demonstrated a disturbance of the microbiota, or dysbiosis, associated with pathological conditions. The microbiota establishes a symbiotic crosstalk with their host: commensal microbes benefit from the nutrient-rich environment provided by the gut and the microbiota produces hundreds of proteins and metabolites that modulate key functions of the host, including nutrient processing, maintenance of energy homoeostasis and immune system development.

Secretin release after Roux-en-Y gastric bypass reveals a population of glucose-sensitive S cells in distal small intestine.

Objectives: Gastrointestinal hormones contribute to the beneficial effects of Roux-en-Y gastric bypass surgery (RYGB) on glycemic control. Secretin is secreted from duodenal S cells in response to low luminal pH, but it is unknown whether its secretion is altered after RYGB and if secretin contributes to the postoperative improvement in glycemic control. We hypothesized that secretin secretion increases after RYGB as a result of the diversion of nutrients to more distal parts of the small intestine, and thereby affects islet hormone release.

Suppression of enteroendocrine cell glucagon-like peptide (GLP)-1 release by fat-induced small intestinal ketogenesis: a mechanism targeted by Roux-en-Y gastric bypass surgery but not by preoperative very-low-calorie diet.

Objective: Food intake normally stimulates release of satiety and insulin-stimulating intestinal hormones, such as glucagon-like peptide (GLP)-1. This response is blunted in obese insulin resistant subjects, but is rapidly restored following Roux-en-Y gastric bypass (RYGB) surgery. We hypothesised this to be a result of the metabolic changes taking place in the small intestinal mucosa following the anatomical rearrangement after RYGB surgery, and aimed at identifying such mechanisms.

Single cell transcriptomic profiling of large intestinal enteroendocrine cells in mice - Identification of selective stimuli for insulin-like peptide-5 and glucagon-like peptide-1 co-expressing cells.

Objective: Enteroendocrine cells (EECs) of the large intestine, found scattered in the epithelial layer, are known to express different hormones, with at least partial co-expression of different hormones in the same cell. Here we aimed to categorize colonic EECs and to identify possible targets for selective recruitment of hormones.

Methods: Single cell RNA-sequencing of sorted enteroendocrine cells, using NeuroD1-Cre x Rosa26-EYFP mice, was used to cluster EECs from the colon and rectum according to their transcriptome.

Characterisation of proguanylin expressing cells in the intestine - evidence for constitutive luminal secretion.

Guanylin, a peptide implicated in regulation of intestinal fluid secretion, is expressed in the mucosa, but the exact cellular origin remains controversial. In a new transgenic mouse model fluorescent reporter protein expression driven by the proguanylin promoter was observed throughout the small intestine and colon in goblet and Paneth(-like) cells and, except in duodenum, in mature enterocytes. In Ussing chamber experiments employing both human and mouse intestinal tissue, proguanylin was released predominantly in the luminal direction.

Ghrelin Does Not Directly Stimulate Secretion of Glucagon-like Peptide-1.

Context: The gastrointestinal hormone ghrelin stimulates growth hormone secretion and appetite, but recent studies indicate that ghrelin also stimulates the secretion of the appetite-inhibiting and insulinotropic hormone glucagon-like peptide-1 (GLP-1).

Objective: To investigate the putative effect of ghrelin on GLP-1 secretion in vivo and in vitro.

Subjects And Methods: A randomized placebo-controlled crossover study was performed in eight hypopituitary subjects.

Abcc5 Knockout Mice Have Lower Fat Mass and Increased Levels of Circulating GLP-1.

Objective: A previous genome-wide association study linked overexpression of an ATP-binding cassette transporter, ABCC5, in humans with a susceptibility to developing type 2 diabetes with age. Specifically, ABCC5 gene overexpression was shown to be strongly associated with increased visceral fat mass and reduced peripheral insulin sensitivity. Currently, the role of ABCC5 in diabetes and obesity is unknown.

Fructose malabsorption induces cholecystokinin expression in the ileum and cecum by changing microbiota composition and metabolism.

Current fructose consumption levels often overwhelm the intestinal capacity to absorb fructose. We investigated the impact of fructose malabsorption on intestinal endocrine function and addressed the role of the microbiota in this process. To answer this question, a mouse model of moderate fructose malabsorption [ketohexokinase mutant (KHK)] and wild-type (WT) littermate mice were used and received a 20%-fructose (KHK-F and WT-F) or 20%-glucose diet.

Comparison of Human and Murine Enteroendocrine Cells by Transcriptomic and Peptidomic Profiling.

Enteroendocrine cells (EECs) produce hormones such as glucagon-like peptide 1 and peptide YY that regulate food absorption, insulin secretion, and appetite. Based on the success of glucagon-like peptide 1-based therapies for type 2 diabetes and obesity, EECs are themselves the focus of drug discovery programs to enhance gut hormone secretion. The aim of this study was to identify the transcriptome and peptidome of human EECs and to provide a cross-species comparison between humans and mice.

Acipimox Acutely Increases GLP-1 Concentrations in Overweight Subjects and Hypopituitary Patients.

Context: Glucagon-like peptide-1 (GLP-1) is an incretin hormone used therapeutically in type 2 diabetes and obesity. The interplay between ambient free fatty acids (FFAs) and GLP-1 remains unclear. Acipimox suppresses adipose tissue lipolysis via activation of the PUMA-G (also known as HCA2 and GPR109a) receptor.

Important Role of the GLP-1 Axis for Glucose Homeostasis after Bariatric Surgery.

Bariatric surgery is widely used to treat obesity and improves type 2 diabetes beyond expectations from the degree of weight loss. Elevated post-prandial concentrations of glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and insulin are widely reported, but the importance of GLP-1 in post-bariatric physiology remains debated. Here, we show that GLP-1 is a major driver of insulin secretion after bariatric surgery, as demonstrated by blocking GLP-1 receptors (GLP1Rs) post-gastrectomy in lean humans using Exendin-9 or in mice using an anti-GLP1R antibody.

PYY plays a key role in the resolution of diabetes following bariatric surgery in humans.

Background: Bariatric surgery leads to early and long-lasting remission of type 2 diabetes (T2D). However, the mechanisms behind this phenomenon remain unclear. Among several factors, gut hormones are thought to be crucial mediators of this effect.

Butyrate Produced by Commensal Bacteria Down-Regulates () Expression a Dual Mechanism in Human Intestinal Epithelial Cells.

Commensal bacteria are crucial for the development and maintenance of a healthy immune system therefore contributing to the global well-being of their host. A wide variety of metabolites produced by commensal bacteria are influencing host health but the characterization of the multiple molecular mechanisms involved in host-microbiota interactions is still only partially unraveled. The intestinal epithelial cells (IECs) take a central part in the host-microbiota dialogue by inducing the first microbial-derived immune signals.

Quantitative mass spectrometry for human melanocortin peptides in vitro and in vivo suggests prominent roles for β-MSH and desacetyl α-MSH in energy homeostasis.

Objective: The lack of pro-opiomelanocortin (POMC)-derived melanocortin peptides results in hypoadrenalism and severe obesity in both humans and rodents that is treatable with synthetic melanocortins. However, there are significant differences in POMC processing between humans and rodents, and little is known about the relative physiological importance of POMC products in the human brain. The aim of this study was to determine which POMC-derived peptides are present in the human brain, to establish their relative concentrations, and to test if their production is dynamically regulated.