Pluripotent Stem Cell-Derived Hepatocytes Inhibit T Cell Proliferation In Vitro through Tryptophan Starvation.

Regenerative medicine aims to replace damaged tissues by stimulating endogenous tissue repair or by transplanting autologous or allogeneic cells. Due to their capacity to produce unlimited numbers of cells of a given cell type, pluripotent stem cells, whether of embryonic origin or induced via the reprogramming of somatic cells, are of considerable therapeutic interest in the regenerative medicine field. However, regardless of the cell type, host immune responses present a barrier to success. The aim of this study was to investigate in vitro the immunological properties of human pluripotent stem cell (PSC)-derived hepatocyte-like cells (HLCs). These cells expressed MHC class I molecules while they lacked MHC class II and co-stimulatory molecules, such as CD80 and CD86. Following stimulation with IFN-γ, HLCs upregulated CD40, PD-L1 and MHC class I molecules. When co-cultured with allogeneic T cells, HLCs did not induce T cell proliferation; furthermore, when T cells were stimulated via αCD3/CD28 beads, HLCs inhibited their proliferation via IDO1 and tryptophan deprivation. These results demonstrate that PSC-derived HLCs possess immunoregulatory functions, at least in vitro

Interleukin 6 increases production of cytokines by colonic innate lymphoid cells in mice and patients with chronic intestinal inflammation

Background & Aims: Innate lymphoid cells (ILCs) are a heterogeneous group of mucosal inflammatory cells that participate in chronic intestinal inflammation. We investigated the role of interleukin 6 (IL6) in inducing activation of ILCs in mice and in human beings with chronic intestinal inflammation. Methods: ILCs were isolated from colons of Tbx21-/- × Rag2-/- mice (TRUC), which develop colitis; patients with inflammatory bowel disease (IBD); and patients without colon inflammation (controls). ILCs were characterized by flow cytometry; cytokine production was measured by enzyme-linked immunosorbent assay and cytokine bead arrays. Mice were given intraperitoneal injections of depleting (CD4, CD90), neutralizing (IL6), or control antibodies. Isolated colon tissues were analyzed by histology, explant organ culture, and cell culture. Bacterial DNA was extracted from mouse fecal samples to assess the intestinal microbiota. Results: IL17A- and IL22-producing, natural cytotoxicity receptor-negative, ILC3 were the major subset of ILCs detected in colons of TRUC mice. Combinations of IL23 and IL1α induced production of cytokines by these cells, which increased further after administration of IL6. Antibodies against IL6 reduced colitis in TRUC mice without significantly affecting the structure of their intestinal microbiota. Addition of IL6 increased production of IL17A, IL22, and interferon-γ by human intestinal CD3-negative, IL7-receptor-positive cells, in a dose-dependent manner. Conclusions: IL6 contributes to activation of colonic natural cytotoxicity receptor-negative, CD4-negative, ILC3s in mice with chronic intestinal inflammation (TRUC mice) by increasing IL23- and IL1α-induced production of IL17A and IL22. This pathway might be targeted to treat patients with IBD because IL6, which is highly produced in colonic tissue by some IBD patients, also increased the production of IL17A, IL22, and interferon-γ by cultured human colon CD3-negative, IL7-receptor-positive cells

Interleukin-22 orchestrates a pathological endoplasmic reticulum stress response transcriptional programme in colonic epithelial cells.

OBJECTIVE: The functional role of interleukin-22 (IL22) in chronic inflammation is controversial, and mechanistic insights into how it regulates target tissue are lacking. In this study, we evaluated the functional role of IL22 in chronic colitis and probed mechanisms of IL22-mediated regulation of colonic epithelial cells. DESIGN: To investigate the functional role of IL22 in chronic colitis and how it regulates colonic epithelial cells, we employed a three-dimentional mini-gut epithelial organoid system, in vivo disease models and transcriptomic datasets in human IBD. RESULTS: As well as inducing transcriptional modules implicated in antimicrobial responses, IL22 also coordinated an endoplasmic reticulum (ER) stress response transcriptional programme in colonic epithelial cells. In the colon of patients with active colonic Crohn's disease (CD), there was enrichment of IL22-responsive transcriptional modules and ER stress response modules. Strikingly, in an IL22-dependent model of chronic colitis, targeting IL22 alleviated colonic epithelial ER stress and attenuated colitis. Pharmacological modulation of the ER stress response similarly impacted the severity of colitis. In patients with colonic CD, antibody blockade of IL12p40, which simultaneously blocks IL12 and IL23, the key upstream regulator of IL22 production, alleviated the colonic epithelial ER stress response. CONCLUSIONS: Our data challenge perceptions of IL22 as a predominantly beneficial cytokine in IBD and provide novel insights into the molecular mechanisms of IL22-mediated pathogenicity in chronic colitis. Targeting IL22-regulated pathways and alleviating colonic epithelial ER stress may represent promising therapeutic strategies in patients with colitis. TRIAL REGISTRATION NUMBER: NCT02749630

Developing in vitro expanded CD45RA⁺ regulatory T cells as an adoptive cell therapy for Crohn's disease

BACKGROUND AND AIM: Thymus-derived regulatory T cells (T(regs)) mediate dominant peripheral tolerance and treat experimental colitis. T(regs) can be expanded from patient blood and were safely used in recent phase 1 studies in graft versus host disease and type 1 diabetes. T(reg) cell therapy is also conceptually attractive for Crohn's disease (CD). However, barriers exist to this approach. The stability of T(regs) expanded from Crohn's blood is unknown. The potential for adoptively transferred T(regs) to express interleukin-17 and exacerbate Crohn's lesions is of concern. Mucosal T cells are resistant to T(reg)-mediated suppression in active CD. The capacity for expanded T(regs) to home to gut and lymphoid tissue is unknown. METHODS: To define the optimum population for T(reg) cell therapy in CD, CD4(+)CD25(+)CD127(lo)CD45RA(+) and CD4(+)CD25(+)CD127(lo)CD45RA(−) T(reg) subsets were isolated from patients’ blood and expanded in vitro using a workflow that can be readily transferred to a good manufacturing practice background. RESULTS: T(regs) can be expanded from the blood of patients with CD to potential target dose within 22–24 days. Expanded CD45RA(+) T(regs) have an epigenetically stable FOXP3 locus and do not convert to a Th17 phenotype in vitro, in contrast to CD45RA(−) T(regs). CD45RA(+) T(regs) highly express α(4)β(7) integrin, CD62L and CC motif receptor 7 (CCR7). CD45RA(+) T(regs) also home to human small bowel in a C.B-17 severe combined immune deficiency (SCID) xenotransplant model. Importantly, in vitro expansion enhances the suppressive ability of CD45RA(+) T(regs). These cells also suppress activation of lamina propria and mesenteric lymph node lymphocytes isolated from inflamed Crohn's mucosa. CONCLUSIONS: CD4(+)CD25(+)CD127(lo)CD45RA(+) T(regs) may be the most appropriate population from which to expand T(regs) for autologous T(reg) therapy for CD, paving the way for future clinical trials

Loss of Sugar Detection by GLUT2 Affects Glucose Homeostasis in Mice

International audienceBACKGROUND: Mammals must sense the amount of sugar available to them and respond appropriately. For many years attention has focused on intracellular glucose sensing derived from glucose metabolism. Here, we studied the detection of extracellular glucose concentrations in vivo by invalidating the transduction pathway downstream from the transporter-detector GLUT2 and measured the physiological impact of this pathway. METHODOLOGY/PRINCIPAL FINDINGS: We produced mice that ubiquitously express the largest cytoplasmic loop of GLUT2, blocking glucose-mediated gene expression in vitro without affecting glucose metabolism. Impairment of GLUT2-mediated sugar detection transiently protected transgenic mice against starvation and streptozotocin-induced diabetes, suggesting that both low- and high-glucose concentrations were not detected. Transgenic mice favored lipid oxidation, and oral glucose was slowly cleared from blood due to low insulin production, despite massive urinary glucose excretion. Kidney adaptation was characterized by a lower rate of glucose reabsorption, whereas pancreatic adaptation was associated with a larger number of small islets. CONCLUSIONS/SIGNIFICANCE: Molecular invalidation of sugar sensing in GLUT2-loop transgenic mice changed multiple aspects of glucose homeostasis, highlighting by a top-down approach, the role of membrane glucose receptors as potential therapeutic targets

Invalidation de la détection des sucres par le transporteur-détecteur GLUT2 (impacts sur les homéostasies glucidique et énergétique)

La détection des sucres est le mécanisme par lequel les concentrations de sucres sont converties en signaux intracellulaires permettant aux cellules d adapter leur équipement protéique et leurs fonctions. Nous étudions les mécanismes de détection des sucres par GLUT2. Par sa fonction de transporteur de glucose à l intérieur de la cellule, GLUT2 participe à la voie métabolique de détection des sucres intracellulaires. De plus, GLUT2 est impliqué dans la détection et la transmission du signal issu du glucose extracellulaire. Nous avons évalué l importance de la détection extracellulaire in vivo par une approche de souris Tg chez lesquelles seule la fonction de détection de GLUT2 a été invalidée. L homéostasie glucidique de ces souris est altérée, elles présentent une réduction des dépôts adipeux, un défaut de sécrétion d insuline et sont intolérantes au glucose. Néanmoins, ces souris sont protégées contre l excès de glucose par une fuite massive de glucose dans les urines. L homéostasie énergétique est également modifiée. La prise alimentaire des souris transgéniques est plus importante et n est plus régulée en présence ou en absence de glucose. De plus, la régulation des neuropeptides orexigéniques et anorexigéniques est altérée tout comme la sécrétion d hormones adipocytaires. Un détecteur des sucres extracellulaires, comme GLUT2, par sa localisation membranaire est accessible aux drogues offrant ainsi de nouvelles possibilités thérapeutiques pour les pathologies associées à la dérégulation de la prise alimentaire et également pour les pathologies associées à une malabsorption du glucoseWe are investigating the mechanisms by which cells sense and adapt their functions to their nutritional environment, focusing on glucose detection. Glucose is not only a substrate for most cells but it also generates a signal to the nucleus that regulates gene transcription. In culture cells, we can block the stimulation of glucose sensitive gene transcription by inhibiting glucose metabolism or by expressing a GLUT2 loop domain that leaves unaffected glucose metabolism. Thus the detection of extracellular glucose triggered by GLUT2 can be studied independently of intracellular glucose metabolism. To evaluate in vivo, the importance of this detection pathway, we produced transgenic mice that expressed ubiquitously the GLUT2 loop domain. Transgenic mice displayed increased daily food intake and perturbed hypothalamic expression of orexigenic and anorexigenic peptides. Interestingly, meal consumptions were neither reduced after a glucose injection nor increased after 2-deoxyglucose injection, suggesting a poor detection of glucose abundance or glucopenia. We recorded by indirect calorimetry that mice favoured lipid over glucose oxidation in accordance with their low fat mass. During an oral glucose challenge, we underlined a significantly reduced plasma insulin response. Together pancreatic and hypothalamic failures to detect glucose could contribute to the growth retardation of transgenic mice. Nevertheless, insulin tolerance tests were unchanged suggesting that peripheral tissues, that are not expressing GLUT2, were unaffected in these mice. Taken together, these data suggest that the detection of extracellular sugar mediated by GLUT2 in pancreas and brain, without affecting their basal functions, controls multiple aspects of food intake, satiety and glucose homeostasis. The sugar detector GLUT2 might constitute a new therapeutic target for the benefit of patients suffering from food intake disorders.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

The immune cell transcription factor T-bet:A novel metabolic regulator

Obesity-associated insulin resistance is accompanied by an alteration in the Th1/Th2 balance in adipose tissue. T-bet (Tbx21) is an immune cell transcription factor originally described as the master regulator of Th1 cell development, although is now recognized to have a role in both the adaptive and innate immune systems. T-bet also directs T-cell homing to pro-inflammatory sites by the regulation of CXCR3 expression. T-bet(-/-) mice have increased visceral adiposity but are more insulin-sensitive, exhibiting reduced immune cell content and cytokine secretion specifically in the visceral fat depot, perhaps due to altered T-cell trafficking. Studies of T-bet deficiency on Rag2-- and IFN-γ-deficient backgrounds indicate the importance of CD4(+) T cells and IFN-γ in this model. This favorable metabolic phenotype, uncoupling adiposity from insulin resistance, is present in young lean mice yet persists with age and increasing obesity. We suggest a novel role for T-bet in metabolic regulation

Retinoic Acid Signaling in B Cells Is Essential for Oral Immunization and Microflora Composition

Retinoic acid (RA)() is a critical regulator of the intestinal adaptive immune response. However, the intrinsic impact of RA on B cell differentiation in the regulation of gut humoral immunity in vivo has never been directly shown. To address this issue, we have been able to generate a mouse model where B-cells specifically express a dominant negative receptor α for RA. Here, we show that the silencing of RA signaling in B-cells reduces the numbers of IgA(+) antibody secreting cells (ASC) both in vitro and in vivo, suggesting that RA has a direct effect on IgA plasma cell (PC) differentiation. Moreover, the lack of RA signaling in B-cells abrogates Ag-specific IgA responses after oral immunization and affects the microbiota composition. In conclusion, these results suggest that RA signaling in B-cells through the RA receptor α is important to generate an effective gut humoral response and to maintain a normal microbiota composition

Sugar sensing by enterocytes combines polarity, membrane bound detectors and sugar metabolism.

International audienceSugar consumption and subsequent sugar metabolism are known to regulate the expression of genes involved in intestinal sugar absorption and delivery. Here we investigate the hypothesis that sugar-sensing detectors in membranes facing the intestinal lumen or the bloodstream can also modulate intestinal sugar absorption. We used wild-type and GLUT2-null mice, to show that dietary sugars stimulate the expression of sucrase-isomaltase (SI) and L-pyruvate kinase (L-PK) by GLUT2-dependent mechanisms, whereas the expression of GLUT5 and SGLT1, did not rely on the presence of GLUT2. By providing sugar metabolites, sugar transporters, including GLUT2, fuelled a sensing pathway. In Caco2/TC7 enterocytes, we could disconnect the sensing triggered by detector from that produced by metabolism, and found that GLUT2 generated a metabolism-independent pathway to stimulate the expression of SI and L-PK. In cultured enterocytes, both apical and basolateral fructose could increase the expression of GLUT5, conversely, basolateral sugar administration could stimulate the expression of GLUT2. Finally, we located the sweet-taste receptors T1R3 and T1R2 in plasma membranes, and we measured their cognate G alpha Gustducin mRNA levels. Furthermore, we showed that a T1R3 inhibitor altered the fructose-induced expression of SGLT1, GLUT5, and L-PK. Intestinal gene expression is thus controlled by a combination of at least three sugar-signaling pathways triggered by sugar metabolites and membrane sugar receptors that, according to membrane location, determine sugar-sensing polarity. This provides a rationale for how intestine adapts sugar delivery to blood and dietary sugar provision