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Lipid malabsorption from altered hormonal signaling changes early gut microbial responses.

ABSTRACT: Infants with congenital diarrheal disorders caused by enteroendocrine cell dysgenesis, or the loss of intestinal endocrine cells, causes severe malabsorptive diarrhea, though the mechanism is not fully understood. The transcription factor "aristaless-related homeobox" (Arx) is specifically expressed in intestinal endocrine cells. This study seeks to characterize the early malabsorptive phenotype of mice deficient for Arx using cell-type specific gene ablation in Villin-Cre; ArxloxP/Y ( Arxint) mice. In neonatal mice, the loss of intestinal Arx caused the loss of intestinal hormones, such as cholecystokinin, secretin, neurotensin, glucose-dependent insulinotropic peptide, glucagon-like peptide (GLP)-1 and GLP-2 but also upregulation of somatostatin. Arxint mice exhibited steatorrhea with the loss of lipid transport in duodenal enterocytes, upregulation of lysozyme-positive Paneth cells, and a secondary increase in antimicrobial peptides, specifically Reg3?. When the epithelium from Arxint mice was cultured ex vivo into enteroids, however, the Reg3? upregulation was lost under the sterile conditions. Thus, Arx is required for the appropriate lineage allocation of multiple enteroendocrine subtypes. We concluded that altered hormonal signaling caused by Arx deficiency results in lipid malabsorption, premature Paneth cell differentiation, and an inflammatory response, including neutrophilic infiltrates and a microbiota-triggered upregulation of Reg3?. NEW & NOTEWORTHY The enteroendocrine transcription factor aristaless-related homeobox (Arx) plays a key role in lineage specification. Changes in hormonal expression mediated by Arx lead to lipid malabsorption and premature Paneth cell development. Furthermore, global profiling of whole intestine from Arx-deficient mice revealed significant upregulation of antimicrobial peptides. This antimicrobial response in Arx-deficient animals is lost under sterile culture conditions of enteroids.

SUBMITTER: Terry NA

PROVIDER: S-EPMC6230693 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Lipid malabsorption from altered hormonal signaling changes early gut microbial responses.

Terry Natalie A NA Ngaba Lucie V LV Wilkins Benjamin J BJ Pi Danielle D Gheewala Nishi N Kaestner Klaus H KH

American journal of physiology. Gastrointestinal and liver physiology 20180628 4

Infants with congenital diarrheal disorders caused by enteroendocrine cell dysgenesis, or the loss of intestinal endocrine cells, causes severe malabsorptive diarrhea, though the mechanism is not fully understood. The transcription factor "aristaless-related homeobox" (Arx) is specifically expressed in intestinal endocrine cells. This study seeks to characterize the early malabsorptive phenotype of mice deficient for Arx using cell-type specific gene ablation in Villin-Cre; Arx<sup>loxP/Y</sup> ...[more]

PMID: 29953253

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Project description:Background and aimsBile acid malabsorption (BAM) is a debilitating disease characterized by loose stools and high stool frequency. The pathophysiology of BAM is not well-understood. We investigated postprandial enterohepatic and gluco-metabolic physiology, as well as gut microbiome composition and fecal bile acid content in patients with BAM.MethodsTwelve participants with selenium-75 homocholic acid taurine test-verified BAM and 12 healthy controls, individually matched on sex, age, and body mass index, were included. Each participant underwent 2 mixed meal tests (with and without administration of the bile acid sequestrant colesevelam) with blood sampling and evaluation of gallbladder motility; bile acid content and microbiota composition were evaluated in fecal specimens.ResultsPatients with BAM were characterized by increased bile acid synthesis as assessed by circulating 7-alpha-hydroxy-4-cholesten-3-one, fecal bile acid content, and postprandial concentrations of glucose, insulin, C-peptide, and glucagon. The McAuley index of insulin sensitivity was lower in patients with BAM than that in healthy controls. In patients with BAM, colesevelam co-administered with the meal reduced postprandial concentrations of bile acids and fibroblast growth factor 19 and increased 7-alpha-hydroxy-4-cholesten-3-one concentrations but did not affect postprandial glucagon-like peptide 1 responses or other gluco-metabolic parameters. Patients with BAM were characterized by a gut microbiome with low relative abundance of bifidobacteria and high relative abundance of Blautia, Streptococcus, Ruminococcus gnavus, and Akkermansia muciniphila.ConclusionPatients with BAM are characterized by an overproduction of bile acids, greater fecal bile acid content, and a gluco-metabolic profile indicative of a dysmetabolic prediabetic-like state, with changes in their gut microbiome composition potentially linking their enterohepatic pathophysiology and their dysmetabolic phenotype. ClinicalTrials.gov number NCT03009916.

Project description:Endocrine therapy agents (the selective estrogen receptor (ER) modulators such as tamoxifen or the selective ER down-regulators such as ICI 182,780) are key treatment regimens for hormone receptor-positive breast cancers. While these drugs are very effective in controlling ER-positive breast cancer, many tumors that initially respond well to treatment often acquire drug resistance, which is a major clinical problem. In clinical practice, hormonal therapy agents are commonly used in combination or sequence with radiation therapy. Tamoxifen treatment and radiotherapy improve both local tumor control and patient survival. However, tamoxifen treatment may render cancer cells less responsive to radiation therapy. Only a handful of data exist on the effects of radiation on cells resistant to hormonal therapy agents. These scarce data show that cells that were resistant to tamoxifen were also resistant to radiation. Yet, the existence and mechanisms of cross-resistance to endocrine therapy and radiation therapy need to be established. Here, we for the first time examined and compared radiation responses of MCF-7 breast adenocarcinoma cells (MCF-7/S0.5) and two antiestrogen resistant cell lines derived from MCF-7/S0.5: the tamoxifen resistant MCF-7/TAMR-1 and ICI 182,780 resistant MCF-7/182R-6 cell lines. Specifically, we analyzed the radiation-induced changes in the expression of genes involved in DNA damage, apoptosis, and cell cycle regulation. We found that the tamoxifen-resistant cell line in contrast to the parental and ICI 182,780-resistant cell lines displayed a significantly less radiation-induced decrease in the expression of genes involved in DNA repair. Furthermore, we show that MCF-7/TAMR-1 and MCF-7/182R-6 cells were less susceptible to radiation-induced apoptosis as compared to the parental line. These data indicate that tamoxifen-resistant breast cancer cells have a reduced sensitivity to radiation treatment. The current study may therefore serve as a roadmap to the future analysis of the mechanisms of cross-resistance between hormonal therapy and radiation.

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Project description:The gastrointestinal microbiota is involved in the development of various diseases, such as obesity and diabetes, by affecting nutrient acquisition, energy balance, and metabolic signaling of the host. However, the underlying mechanisms of these host-microbiota interactions remain unclear. The aim of this study was to characterize effects of the microbiota on the host epithelium using a novel gastrointestinal model based on mouse organoids. We have explored the transcriptional response of organoids upon exposure to short chain fatty acids (SCFA) and products generated by two conspicuous members of the gastrointestinal microbiota; Akkermansia muciniphila and Faecalibacterium prausnitzii. We observed that A. muciniphila metabolites affect a large variety of transcription factors and genes involved in cellular lipid metabolism and growth, supporting previous in vivo findings. F. prausnitzii products exerted only a weak effect on the host transcription profile. While, A. muciniphila, and its main metabolite propionate, both stimulate fasting-induced adipose factor/angiopoietin-like protein 4 (Fiaf/Angptl4) and Ppar? expression, important regulators of lipolysis and satiety. This work illustrates that specific members of the microbiota and their metabolites differentially modulate epithelial transcription in mouse organoid lines. Organoid culture: In short, murine (WT C57BL/6) small intestinal crypts were isolated and embedded in 250 µl Matrigel (BD Biosciences) and submerged in 500 ul basal culture medium supplemented with penicillin/streptomycin, HEPES, Glutamax, N2, B27, N-acetylcysteine, and the murine growth factors EGF, noggin, and R-spondin-1 (ENR), as previously described (Sato et al., 2009. Nature 459:262–5). Organoids were passaged every 7 days with a 1:4 splitting ratio. Exposure to bacterial cultures and SCFA: A. muciniphila (ATTC BAA-835) was grown anaerobically at 37C in a basal liquid medium which contained (per liter of deionized water) the following: 0.4g KH2PO4, 0.669g, Na2HPO4 + 2H2O, 0.3g NH4CL, 0.3gNaCl, 0.1g MgCl2 + 6H2O, 10g casitone, 1mM L-threonine, 1 ml trace mineral solution, 5mM L-fucose, and 5mM D-glucose. F. prausnitzii strain A2-165 (DSM 17677) was grown anaerobically at 37ºC a liquid medium which contained (per liter of deionized water) the following: 10 g casitone, 2.5 g yeast extract, 4 g NaHCO3, 1 ml resazurine (0.1%w/v), 0.45g K2HPO4, 0.45g KH2PO4, 0.9g (NH4)2SO4, 0.9g NaCL, 0.09g MgSO4, 0.09g CaCL2, 2.5 mM acetate, 9 mM propionate, 1 mM n-valerate, 1 mM isovalerate, 1 mM isobutyrate, 0.28g KOH, 2.5 ml ethanol (95%), 10 mg haemin,, 10 ug biotin, 10 ug cobalamin, 30 ug para-aminobenzoic acid, 50 ug folic acid, 150 ug pyridoxamine, 1 g L-cysteine, and 25 mM glucose (Duncan et al., 2002. Int. J. Syst. Evol. Microbiol. 52:2141–6). The concentration of the following organic acids and sugars were determined in the culture medium before and after growth using a high performance liquid chromatography (HPLC) equipped with a Shodex Sugar SH-G and Shodex SH1821 column as has been described previously (Stams et al., 1993. Appl. Environ. Microbiol. 59:1114–9): glucose, mannose, galactose, L-fucose, glucose-N-acetylglucosamine, lactate, formate acetate, propionate, 1,2-propendiol and butyrate. Overnight-grown cultures were pelleted by centrifugation at 20 000 ×g for 10 min and supernatant was collected. At t=7 days after splitting organoids were exposed to 250 μl A. muciniphila supernatant, 250 μl unconditioned A. muciniphila culture medium, 85 μl F. prausnitzii supernatant, or 85 μl F. prausnitzii culture medium for 3 hours at 37ºC, prior to RNA extraction. 250 μl A. muciniphila supernatant and culture medium Short chain fatty acids (SCFA) sodium butyrate, sodium propionate, and sodium acetate (Sigma-Aldrich, Zwijndrecht, the Netherlands) were administered at a final concentration of 5 mM. At t=7 days after splitting mature organoids were exposed to individual SCFAs for 3 hours at 37ºC, prior to RNA extraction. Data is presented from n = 4 independent biological replicates from one line of organoids. total RNA was isolated from mouse intestinal organoids exposed for 3h to SCFA and strain-specific culture medium: Am- (organoids exposed to A. muciniphila culturing medium), Am+ (A. muciniphila-conditioned medium), Fp- (F. prausnitzii-culturing medium), Fp+ (F. prausnitzii-conditioned medium), Ace (acetate), But (butyrate), Pro (propionate) and Con (standard organoid culturing medium).

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Lipid malabsorption from altered hormonal signaling changes early gut microbial responses.

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Lipid malabsorption from altered hormonal signaling changes early gut microbial responses.

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