Abstract Background Crohn’s disease (CD) is characterised by expansion of mesenteric adipose tissue, called creeping fat, which seems to be directly related to disease activity. Adipose stem cells (ASCs) isolated from the creeping fat of CD patients exhibit dysfunction, featuring impaired adipogenesis and an intensely pro-inflammatory phenotype. This study aims to explore the transcriptome of ASCs isolated from active and inactive CD subjects in comparison with healthy subjects, seeking key markers of this dysregulation. Methods Patients were recruited at Hospital Joan XXIII of Tarragona and Hospital Vall d’Hebron of Barcelona in accordance with the principles of the Helsinki Declaration. Transcriptome profiling was performed in ASCs isolated from adipose-tissue biopsies of visceral origin: CF and hMES in Crohn subjects (n=7, each) and hMES in inactive CD patients (n=7) and healthy control subjects (n=7). Groups were matched by age, gender, and BMI. Finally, we examined the pathways involving the differentially expressed gene (DEGs) in ASCs isolated from patients with CD with different clinical activity by gene set enrichment analysis (GSEA). Results Patients with CD across different clinical activity stages exhibited similar transcriptome patterns, indicating persistent ASC dysregulation even during remission state (Fig 1A). ASCs isolated from both creeping fat and mesenteric adipose tissue distant from intestinal damage displayed similar dysregulation, implying a global dysregulation of all mesenteric fat in CD. Specifically, transcriptomic analysis identified significant dysregulation of the NK2 Homeobox 3 (NKX2-3) gene in ASCs from active CD patients. Although higher NKX2-3 expression has been associated with B cells and intestinal tissues in CD1-3, our study is the first to link elevated expression of this gene also to creeping fat. Pathway enrichment analysis revealed significant enrichment in oxidative stress and immune response pathways in active CD (Fig 1B). Furthermore, our findings indicated also an elevated NKX2-3 expression in ASCs of inactive CD compared to controls, with oxidative stress pathway up-regulation (Fig 1C). Notably, no significant DEGs were found between ASCs from active and inactive CD groups (Fig 1D), suggesting a similar profile in both states. Conclusion Our study reveals profound ASC dysregulation in CD, in both active and inactive phases. Elevated NKX2-3 expression, previously associated with increased risk of complications in IBD, is now demonstrated in the mesenteric adipose tissue, persisting even in inactive CD patients. Ref: 1. Yamazaki K, et al Gut. 2009 Feb;58(2):228-32. 2. Yu W, et al. J Crohn’s Colitis. 2009 Sep;3(3):189-95. 3. Hong SN et al. Gut. 2016 May;65(5):788-96.

Pancreatic β cell dysfunction is a key feature of type 2 diabetes, and novel regulators of insulin secretion are desirable. Here, we report that succinate receptor 1 (SUCNR1) is expressed in β cells and is upregulated in hyperglycemic states in mice and humans. We found that succinate acted as a hormone-like metabolite and stimulated insulin secretion via a SUCNR1-Gq-PKC-dependent mechanism in human β cells. Mice with β cell-specific Sucnr1 deficiency exhibited impaired glucose tolerance and insulin secretion on a high-fat diet, indicating that SUCNR1 is essential for preserving insulin secretion in diet-induced insulin resistance. Patients with impaired glucose tolerance showed an enhanced nutrition-related succinate response, which correlates with the potentiation of insulin secretion during intravenous glucose administration. These data demonstrate that the succinate/SUCNR1 axis is activated by high glucose and identify a GPCR-mediated amplifying pathway for insulin secretion relevant to the hyperinsulinemia of prediabetic states.

Background and Aims Crohn’s disease [CD] is characterised by the expansion of mesenteric adipose tissue [MAT], named creeping fat [CF], which seems to be directly related to disease activity. Adipose-stem cells [ASCs] isolated from the CF of patients with CD are extremely pro-inflammatory, which persists during disease remission. We hypothesised that the dysfunctional ASCs in CD accumulate epigenetic modifications triggered by the inflammatory environment, that could serve as molecular markers. Methods Genome-wide DNA methylome and transcriptome profiling were performed in ASCs isolated from MAT biopsies of patients with active and inactive disease and from non-Crohn’s disease patients [non-CD]. A validation cohort was used to test the main candidate genes via quantitative polymerase chain reaction in other fat depots and immune cells. Results We found differences in DNA methylation and gene expression between ASCs isolated from patients with CD and from non-CD subjects, but we found no differences related to disease activity. Pathway enrichment analysis revealed that oxidative stress and immune response were significantly enriched in active CD, and integration analysis identified MAB21L2, a cell fate-determining gene, as the most affected gene in CD. Validation analysis confirmed the elevated gene expression of MAB21L2 in MAT and in adipose tissue macrophages in active CD. We also found a strong association between expression of the calcium channel subunit gene CACNA1H and disease remission, as CACNA1H expression was higher in ASCs and MAT from patients with inactive CD, and correlates negatively with C-reactive protein in peripheral blood mononuclear cells. Conclusion We identified a potential gene signature of CD in ASCs obtained from MAT. Integration analysis highlighted two novel genes demonstrating a negative correlation between promoter DNA methylation and transcription: one linked to ASCs in CD [MAB21L2] and the other [CACNA1H] related to disease remission.

BACKGROUND & AIMS: Enteroendocrine cells (EECs) and their hormones are essential regulators of whole-body energy homeostasis. EECs sense luminal nutrients and microbial metabolites and subsequently secrete various hormones acting locally or at a distance. Impaired development of EECs during embryogenesis is life-threatening in newborn mice and humans due to compromised nutrient absorption. However, the physiological importance of the EEC system in adult mice has yet to be directedly studied. Herein, we aimed to determine the long-term consequences of a total loss of EECs in healthy adults on energy metabolism, intestinal transcriptome, and microbiota. METHODS: We depleted intestinal EECs by tamoxifen treatment of adult Neurog3(fl/fl); Villin-CreER(T2) male mice. We studied intestinal cell differentiation, food efficiency, lipid absorption, microbiota composition, fecal metabolites, and transcriptomic responses in the proximal and distal small intestines of mice lacking EECs. We also determined the high-fat diet-induced transcriptomic changes in sorted Neurog3(eYFP/+) EECs. RESULTS: Induction of EEC deficiency in adults is not life-threatening unless fed with a high-fat diet. Under a standard chow diet, mice lose 10% of weight due to impaired food efficiency. Blood concentrations of cholesterol, triglycerides, and free fatty acids are reduced, and lipid absorption is impaired and delayed in the distal small intestine. Genes controlling lipogenesis, carbohydrate metabolism, and neoglucogenesis are upregulated. Microbiota composition is rapidly altered after EECs depletion and is characterized by decreased a-diversity. Bacteroides and Lactobacillus were progressively enriched, whereas Lachnospiraceae declined without impacting fecal short-chain fatty acid concentrations. CONCLUSIONS: EECs are dispensable for survival in adult male mice under a standard chow diet. The absence of EECs impairs intestinal lipid absorption, leading to transcriptomic and metabolic adaptations and remodeling of the gut microbiota.

OBJECTIVES:Readily accessible human pancreatic beta cells that are functionally close to primary adult beta cells are a crucial model to better understand human beta cell physiology and develop new treatments for diabetes. We here report the characterization of EndoC-βH5 cells, the latest in the EndoC-βH cell family.METHODS:EndoC-βH5 cells were generated by integrative gene transfer of immortalizing transgenes hTERT and SV40 large T along with Herpes Simplex Virus-1 thymidine kinase into human fetal pancreas. Immortalizing transgenes were removed after amplification using CRE activation and remaining non-excized cells eliminated using ganciclovir. Resulting cells were distributed as ready to use EndoC-βH5 cells. We performed transcriptome, immunological and extensive functional assays.RESULTS:Ready to use EndoC-βH5 cells display highly efficient glucose dependent insulin secretion. A robust 10-fold insulin secretion index was observed and reproduced in four independent laboratories across Europe. EndoC-βH5 cells secrete insulin in a dynamic manner in response to glucose and secretion is further potentiated by GIP and GLP-1 analogs. RNA-seq confirmed abundant expression of beta cell transcription factors and functional markers, including incretin receptors. Cytokines induce a gene expression signature of inflammatory pathways and antigen processing and presentation. Finally, modified HLA-A2 expressing EndoC-βH5 cells elicit specific A2-alloreactive CD8 T cell activation.CONCLUSIONS:EndoC-βH5 cells represent a unique storable and ready to use human pancreatic beta cell model with highly robust and reproducible features. Such cells are thus relevant for the study of beta cell function, screening and validation of new drugs, and development of disease models.

Here, we examined the role of succinate, a metabolite that acts by engaging the succinate receptor 1 (SUCNR1), in regulating insulin secretion by β-cells. We found that glucose increases SUCNR1 expression in β-cells and that activating SUCNR1 with either extracellular succinate or a synthetic agonist boosts glucose-stimulated insulin secretion through the Gq and PKC signaling pathways. Also, we identified that SUCNR1 is essential for preserving insulin secretion in a diet-induced insulin-resistance model. Mice with β-cell-specific SUCNR1 deficiency had impaired glucose tolerance and reduced insulin secretion when fed a high-fat diet, without changes in β-cell mass or insulin sensitivity. To investigate the physiological significance of succinate as a secretagogue in humans, we studied the potential connection between circulating succinate levels and β-cell function in response to oral and intravenous glucose challenges in a cohort of patients with impaired glucose tolerance (IGT). These patients were characterized by presenting hyperinsulinemia during both oral and intravenous glucose tests, compared to normal glucose tolerance (NGT) individuals. Moreover, succinate levels were elevated in IGT patients in response to these challenges compared to NGT patients, whereas circulating GLP-1 levels during the tests were not different between groups. Remarkably, we found that circulating succinate levels are positively correlated with insulin secretion potentiation during intravenous glucose administration, indicating that this system is activated by high glucose levels and partially regulated by the β-cell in an autocrine fashion. These findings suggest that succinate may act as a hormone, potentiating insulin secretion in humans through SUCNR1- a compensatory mechanism particularly relevant in the hyperinsulinemia elicited by insulin resistance. Our work sheds new light on the role of the succinate-SUCNR1 axis as a potential therapeutic target for improving insulin secretion in metabolic disorders. Disclosure J.Sabadell-basallote: None. J.J.Vendrell: None. S.Fernandez-veledo: None. B.D.Astiarraga: None. M.Ejarque: None. M.Repollés-de-dalmau: None. F.X.Sureda: None. D.F.De jesus: None. C.Núñez roa: None. A.Mari: Consultant; Eli Lilly and Company. R.Kulkarni: Advisory Panel; Novo Nordisk, Inversago, Biomea Fusion, Inc., REDD Pharma, Research Support; Inversago. Funding Spanish Ministry of Science and Innovation (SAF2015-65019-R, RTI2018-093919-B-100); Instituto de Salud Carlos III (FI18/00151, CP10/00438, CPII16/00008); Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CB07708/0012); Catalan Association of Diabetes (PV21039S)

Abstract Context DNA methylation in the diagnosis of gestational diabetes. Objective To assess the value of DNA methylation in the diagnosis of gestational diabetes (GDM) and in the prediction of maternal postpartum glucose disturbances. Methods Two-stage observational study performed between July 2006 and December 2010, at University Hospital. Forty-eight randomly selected pregnant women formed the discovery cohort (24 with GDM and 24 controls) and 252 pregnant women (94 with GDM and 158 controls) formed the replication cohort. GDM women were re-evaluated 4 years postpartum. The main outcome measures were GDM, type 2 diabetes or prediabetes at 4 years postpartum. Results We identified 3 CpG sites related to LINC00917, TRAPPC9, and LEF1 that were differentially methylated in women with GDM and abnormal glucose tolerance; and sites associated with LINC00917 and TRAPPC9 were independently associated with an abnormal glucose tolerance status 4 years postpartum after controlling for clinical variables. Moreover, the site associated with LINC00917 and the combination of the 3 sites had the highest predictive values. Conclusion Our results suggest that some of these sites may be implicated in the development of GDM and postpartum abnormal glucose tolerance.

Dysfunctional adipocyte precursors have emerged as key determinants for obesity- and aging-related inflammation, but the mechanistic basis remains poorly understood. Here, we explored the dysfunctional adipose tissue of elderly and obese individuals focusing on the metabolic and inflammatory state of human adipose-derived mesenchymal stromal cells (hASCs), and on sirtuins, which link metabolism and inflammation. Both obesity and aging impaired the differentiation potential of hASCs but had a different impact on their proliferative capacity. hASCs from elderly individuals (≥65 years) showed an upregulation of glycolysis-related genes, which was accompanied by increased lactate secretion and glycogen storage, a phenotype that was exaggerated by obesity. Multiplex protein profiling revealed that the metabolic switch to glycogenesis was associated with a pro-inflammatory secretome concomitant with a decrease in the protein expression of SIRT1 and SIRT6. siRNA-mediated knockdown of SIRT1 and SIRT6 in hASCs from lean adults increased the expression of pro-inflammatory and glycolysis-related markers, and enforced glycogen deposition by overexpression of protein targeting to glycogen (PTG) led to a downregulation of SIRT1/6 protein levels, mimicking the inflammatory state of hASCs from elderly subjects. Overall, our data point to a glycogen-SIRT1/6 signaling axis as a driver of age-related inflammation in adipocyte precursors.

MATERIALS AND METHODS Study selection and sample processing hASCs were obtained from the SAT of ageand sex-matched donors undergoing non-acute surgical interventions, such as hernia or cholecystectomy, in a scheduled routine surgery (n=6 per group) using standard protocols.1–4 Briefly, SAT was washed extensively with phosphate buffered saline (PBS) and treated with 0.1% collagenase in PBS+1% bovine serum albumin (BSA) for 1 hour at 37oC with agitation. Digested samples were centrifuged to separate adipocytes from stromal cells. The cell pellet containing the stromal fraction was resuspended in stromal culture medium. The medium was replaced 24 hours after seeding to remove non-adherent cells. When cultures reached approximately 80% confluency at passage 0 (P0), the cells were harvested by trypsin and seeded for the following passage or centrifuged to resuspend the pellet at a concentration of 106 hASCs/ml in cryomedium (10% DMSO, 10% DMEM/F12, 80% bovine calf serum). The cells were dispensed in 1-ml aliquots in cryovials, maintained overnight in a -80oC freezer and then stored in liquid nitrogen until they were required for the individual experiments. All participants gave their informed consent and the study was reviewed and approved by the ethics and research committee of University Hospital Joan XXIII, Tarragona, Spain. Clinical and laboratory data of the participants are shown in Table S1.

Our understanding of the interplay between human adipose tissue and the immune system is limited. The mesothelium, an immunologically active structure, emerged as a source of visceral adipose tissue. After investigating the mesothelial properties of human visceral and subcutaneous adipose tissue and their progenitors, we explored whether the dysfunctional obese and Crohn's disease environments influence the mesothelial/mesenchymal properties of their adipocyte precursors, as well as their ability to mount an immune response. Using a tandem transcriptomic/proteomic approach, we evaluated the mesothelial and mesenchymal expression profiles in adipose tissue, both in subjects covering a wide range of body-mass indexes and in Crohn's disease patients. We also isolated adipose tissue precursors (adipose-derived stem cells, ASCs) to assess their mesothelial/mesenchymal properties, as well as their antigen-presenting features. Human visceral tissue presented a mesothelial phenotype not detected in the subcutaneous fat. Only ASCs from mesenteric adipose tissue, named creeping fat, had a significantly higher expression of the hallmark mesothelial genes mesothelin (MSLN) and Wilms' tumor suppressor gene 1 (WT1), supporting a mesothelial nature of these cells. Both lean and Crohn's disease visceral ASCs expressed equivalent surface percentages of the antigen-presenting molecules human leucocyte antigen-DR isotype (HLA-DR) and CD86. However, lean-derived ASCs were predominantly HLA-DR dim, whereas in Crohn's disease, the HLA-DR bright subpopulation was increased 3.2-fold. Importantly, the mesothelial-enriched Crohn's disease precursors activated CD4+ T-lymphocytes. Our study evidences a mesothelial signature in the creeping fat of Crohn's disease patients and its progenitor cells, the latter being able to present antigens and orchestrate an immune response.

Adipose-derived mesenchymal stem cells (ASCs) are a promising option for the treatment of obesity and its metabolic co-morbidities. Despite the recent identification of brown adipose tissue (BAT) as a potential target in the management of obesity, the use of ASCs isolated from BAT as a therapy for patients with obesity has not yet been explored. Metabolic activation of BAT has been shown to have not only thermogenic effects, but it also triggers the secretion of factors that confer protection against obesity. Herein, we isolated and characterized ASCs from the visceral adipose tissue surrounding a pheochromocytoma (IB-hASCs), a model of inducible BAT in humans. We then compared the anti-obesity properties of IB-hASCs and human ASCs isolated from visceral white adipose tissue (W-hASCs) in a murine model of diet-induced obesity. We found that both ASC therapies mitigated the metabolic abnormalities of obesity to a similar extent, including reducing weight gain and improving glucose tolerance. However, infusion of IB-hASCs was superior to W-hASCs in suppressing lipogenic and inflammatory markers, as well as preserving insulin secretion. Our findings provide evidence for the metabolic benefits of visceral ASC infusion and support further studies on IB-hASCs as a therapeutic option for obesity-related comorbidities.

Background and PurposeGlucagon‐like peptide‐2 (GLP‐2) is a gastrointestinal hormone released in response to nutritional intake that exerts a wide range of effects by activating GLP‐2 receptors. In addition to its intestinotrophic effects, GLP‐2 also positively influences glucose metabolism under conditions of obesity, but the mechanisms behind this remain unclear. Here, we have investigated the molecular role of the GLP‐2/GLP‐2 receptor axis in energetic metabolism, focusing on its potential modulatory effects on adipose tissue.Experimental ApproachPhysiological measurements (body weight, food intake, locomotor activity, and energy expenditure) and metabolic studies (glucose and insulin tolerance tests) were performed on lean and obese mice treated with the protease‐resistant GLP‐2 analogue teduglutide.Key ResultsAcute but not chronic centrally administered teduglutide decreased food intake and weight‐gain. By contrast, chronic activation of peripheral GLP‐2 receptors increased body weight‐independent glucose tolerance and had anti‐inflammatory effects on visceral adipose tissue. Using a gene silencing approach, we found that adipose tissue is necessary for these beneficial effects of teduglutide. Finally, teduglutide regulates the inflammatory state and acts as an anabolic signal in human adipocytes.Conclusion and ImplicationsOverall, our data identify adipose tissue as a new, clinically relevant, site of action for GLP‐2 activity in obesity.LINKED ARTICLESThis article is part of a themed issue on Cellular metabolism and diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.10/issuetoc

Background Crohn’s disease (CD) is characterized by persistent inflammation and ulceration of the small or large bowel, and expansion of mesenteric adipose tissue, termed creeping fat (CF). We previously demonstrated that human adipose-derived stem cells (hASCs) from CF of patients with CD exhibit dysfunctional phenotypes, including a pro-inflammatory profile, high phagocytic capacity, and weak immunosuppressive properties. Importantly, these phenotypes persist in patients in remission and are found in all adipose depots explored including subcutaneous fat. We hypothesized that changes in hASCs are a consequence of epigenetic modifications. Methods We applied epigenome-wide profiling with a methylation array (Illumina EPIC/850k array) and gene expression analysis to explore the impact of CD on the methylation signature of hASCs isolated from the subcutaneous fat of patients with CD and healthy controls ( n = 7 and 5, respectively; cohort I). Differentially methylated positions ( p value cutoff < 1 × 10 −4 and ten or more DMPs per gene) and regions (inclusion threshold 0.2, p value cutoff < 1 × 10 −2 and more than 2 DMRs per gene) were identified using dmpfinder and Bumphunter (minfi), respectively. Changes in the expression of differentially methylated genes in hASCs were validated in a second cohort ( n = 10/10 inactive and active CD and 10 controls; including patients from cohort I) and also in peripheral blood mononuclear cells (PBMCs) of patients with active/inactive CD and of healthy controls (cohort III; n = 30 independent subjects). Results We found a distinct DNA methylation landscape in hASCs from patients with CD, leading to changes in the expression of differentially methylated genes involved in immune response, metabolic, cell differentiation, and development processes. Notably, the expression of several of these genes in hASCs and PBMCs such as tumor necrosis factor alpha (TNFA) and PR domain zinc finger protein 16 (PRDM16) were not restored to normal (healthy) levels after disease remission. Conclusions hASCs of patients with CD exhibit a unique DNA methylation and gene expression profile, but the expression of several genes are only partially restored in patients with inactive CD, both in hASCs and PBMCs. Understanding how CD shapes the functionality of hASCs is critical for investigating the complex pathophysiology of this disease, as well as for the success of cell-based therapies. Graphical abstract Human adipose-stem cells isolated from subcutaneous fat of patients with Crohn’s disease exhibit an altered DNA methylation pattern and gene expression profile compared with those isolated from healthy individuals, with immune system, cell differentiation, metabolic and development processes identified as the main pathways affected. Interestingly, the gene expression of several genes involved in these pathways is only partially restored to control levels in patients with inactive Crohn’s disease, both in human adipose-stem cells and peripheral blood mononuclear cells. Understanding how Crohn’s disease shapes the functionality of human adipose-stem cells is critical for investigating the complex pathophysiology of this disease, as well as for the success of cell-based therapies.

Abstract Background Crohn’s disease (CD) is characterised by the expansion of mesenteric adipose tissue, termed creeping fat (CF). We previously demonstrated that human adipose-tissue stem cells (hASCs) from CF exhibit a dysfunctional phenotype, including a pro-inflammatory profile, high phagocytic capacity and weak immunosuppressive properties. Importantly, these phenotypes persist in patients in remission, and are found in all adipose depots explored including subcutaneous fat. We hypothesised that this is a consequence of epigenetic modifications. Methods Epigenome-wide association studies using the 850k EPIC Illumina array were used to explore the impact of CD on the methylation signature of hASCs isolated from the subcutaneous fat (Figure 1). Changes in the expression of differentially methylated candidate genes were validated in hASCs of patients with active/inactive CD and healthy controls (Figure 1). Conclusion hASCs of patients with CD exhibit an alter DNA-methylation and gene expression profile. Remarkably, the expression of several genes is only partially restored in patients with inactive CD. Understanding how CD shapes the functionality of hASCs is critical for investigating the complex pathophysiology of this disease, as well as for the success of cell-based therapies.

Fetal programming has been proposed as a key mechanism underlying the association between intrauterine exposure to maternal diabetes and negative health outcomes in offspring. To determine whether gestational diabetes mellitus (GDM) might leave an imprint in fetal precursors of the amniotic membrane and whether it might be related to adverse outcomes in offspring, a prospective case-control study was conducted, in which amniotic mesenchymal stem cells (AMSCs) and resident macrophages were isolated from pregnant patients, with either GDM or normal glucose tolerance, scheduled for cesarean section. After characterization, functional characteristics of AMSCs were analyzed and correlated with anthropometrical and clinical variables from both mother and offspring. GDM-derived AMSCs displayed an impaired proliferation and osteogenic potential when compared with control cells, accompanied by superior invasive and chemotactic capacity. The expression of genes involved in the inflammatory response (TNF alpha, MCP-1, CD40, and CTSS) was upregulated in GDM-derived AMSCs, whereas anti-inflammatory IL-33 was downregulated. Macrophages isolated from the amniotic membrane of GDM mothers consistently showed higher expression of MCP-1 as well. In vitro studies in which AMSCs from healthy control women were exposed to hyperglycemia, hyperinsulinemia, and palmitic acid confirmed these results. Finally, genes involved in the inflammatory response were associated with maternal insulin sensitivity and prepregnancy body mass index, as well as with fetal metabolic parameters. These results suggest that the GDM environment could program stem cells and subsequently favor metabolic dysfunction later in life. Fetal adaptive programming in the setting of GDM might have a direct negative impact on insulin resistance of offspring.

Under physiological conditions, mesenchymal stem cells (MSCs) are known to modulate the function of diverse types of immune cells, both adaptive and innate. However, only recently has their role in an inflammatory microenvironment undergone scrutiny. In this sense, our group reveals that MSCs isolated from adipose tissue (called adipose-derived stem cells; ASCs) from Crohn’s disease (CD) patients are immune activated (showing a high inflammatory profile, high invasive and phagocytic capacities and worse immunosupressive properties). So, our hypothesis is that in CD, ASCs within the creeping fat (CF) and also the mesentery (MES) are tightly stacked in a chronic inflammatory milieu, which may cause their enforced expression of Class II major histocompatibility complex (MHC) due to an inappropriate response to intestinal dysbiotic microbiota. Donors are being recruited at Hospital Joan XXIII of Tarragona and Hospital Vall d’Hebron of Barcelona in accordance with the principles of the Helsinki Declaration. ASCs were isolated from adipose tissue biopsies of visceral origin: CF and MES in Crohn subjects (n = 6) and MES in no-Crohn subjects (n = 6). Groups were matched by age, gender, and BMI. Antigen-presenting cell properties were studied by flow cytometer, gene expression and immunofluorescence in ASCs of Crohn vs. no-Crohn subjects. Significant differences in the surface expression of human leucocyte antigen–DR isotype (HLA-DR) and the costimulatory molecule 86 (CD86) were observed between ASCs isolated from Crohn vs. no-Crohn subjects (Figure 1A and B). Interestingly, all ASCs were able to uptake ovalbumin (OVA) when we administered to the cell (Figure 1C). Furthermore, multiple genes involved in MHCII antigen processing and presentation increased in ASCs isolated from Crohn patients (Figure 1D). Figure 1. Adipose-derived stem cells from Crohn's disease patients function as antigen-presenting cells. (A) Adipose-derived stem cells (ASCs) obtained from 6 no-Crohn and 6 Crohn donors and stained with the panel of antibodies and analysed by flow cytometry on the FACS ARIA III cytometer (BD). (B) Representative histogram of HLA-DR in ASCs of Crohn and no-Crohn subjects. (C) Fluorescence representative image of OVA uptake by ASCs. (D) Gene expression of antigen presentation markers in ASCs isolated from Crohn and no-Crohn subjects. *p < 0.05 vs. no-Crohn subjects. No parametric test (U-Mann Whitney). Our investigation highlights a role of ASCs as antigen-presenting cell in CD subjects promoting the immune system activation, influencing CD outcome and disease progression.

Succinate is a signaling metabolite sensed extracellularly by succinate receptor 1 (SUNCR1). The accumulation of succinate in macrophages is known to activate a pro-inflammatory program; however, the contribution of SUCNR1 to macrophage phenotype and function has remained unclear. Here we found that activation of SUCNR1 had a critical role in the anti-inflammatory responses in macrophages. Myeloid-specific deficiency in SUCNR1 promoted a local pro-inflammatory phenotype, disrupted glucose homeostasis in mice fed a normal chow diet, exacerbated the metabolic consequences of diet-induced obesity and impaired adipose-tissue browning in response to cold exposure. Activation of SUCNR1 promoted an anti-inflammatory phenotype in macrophages and boosted the response of these cells to type 2 cytokines, including interleukin-4. Succinate decreased the expression of inflammatory markers in adipose tissue from lean human subjects but not that from obese subjects, who had lower expression of SUCNR1 in adipose-tissue-resident macrophages. Our findings highlight the importance of succinate-SUCNR1 signaling in determining macrophage polarization and assign a role to succinate in limiting inflammation.