Intectin, a Novel Small Intestine-specific Glycosylphosphatidylinositol-anchored Protein, Accelerates Apoptosis of Intestinal Epithelial Cells

Human LY6 gene family: potential tumor-associated antigens and biomarkers of prognosis in uterine corpus endometrial carcinoma

The human Lymphocyte antigen-6 (LY6) gene family has recently gained interest for its possible role in tumor progression. We have carried out in silico analyses of all known LY6 gene expression and amplification in different cancers using TNMplot and cBioportal. We also have analyzed patient survival by Kaplan-Meier plotter after mining the TCGA database. We report that upregulated expression of many LY6 genes is associated with poor survival in uterine corpus endometrial carcinoma (UCEC) cancer patients. Importantly, the expression of several LY6 genes is elevated in UCEC when compared to the expression in normal uterine tissue. For example, LY6K expression is 8.25× higher in UCEC compared to normal uterine tissue, and this high expression is associated with poor survival with a hazard ratio of 2.42 (p-value = 0.0032). Therefore, some LY6 gene products may serve as tumor-associated antigens in UCEC, biomarkers for UCEC detection, and possibly targets for directing UCEC patient therapy. Further analysis of tumor-specific expression of LY6 gene family members and LY6-triggered signaling pathways is needed to uncover the function of LY6 proteins and their ability to endow tumor survival and poor prognosis in UCEC patients.

Genetically encoded Runx3 and CD4+ intestinal epithelial lymphocyte deficiencies link SKG mouse and human predisposition to spondyloarthropathy

Disturbances in immune regulation, intestinal dysbiosis and inflammation characterize ankylosing spondylitis (AS), which is associated with RUNX3 loss-of-function variants. ZAP70^W163C mutant (SKG) mice have reduced ZAP70 signaling, spondyloarthritis and ileitis. In small intestine, Foxp3⁺ regulatory T cells (Treg) and CD4⁺CD8αα⁺TCRαβ⁺ intraepithelial lymphocytes (CD4-IEL) control inflammation. TGF-β and retinoic acid (RA)-producing dendritic cells and MHC-class II⁺ intestinal epithelial cells (IEC) are required for Treg and CD4-IEL differentiation from CD4⁺ conventional or Treg precursors, with upregulation of Runx3 and suppression of ThPOK. We show in SKG mouse ileum, that ZAP70^W163C or ZAP70 inhibition prevented CD4-IEL but not Treg differentiation, dysregulating Runx3 and ThPOK. TGF-β/RA-mediated CD4-IEL development, T-cell IFN-γ production, MHC class-II⁺ IEC, tissue-resident memory T-cell and Runx3-regulated genes were reduced. In AS intestine, CD4-IEL were decreased, while in AS blood CD4⁺CD8⁺ T cells were reduced and Treg increased. Thus, genetically-encoded TCR signaling dysfunction links intestinal T-cell immunodeficiency in mouse and human spondyloarthropathy.

Rhubarb Supplementation Prevents Diet-Induced Obesity and Diabetes in Association with Increased Akkermansia muciniphila in Mice

Obesity and obesity-related disorders, such as type 2 diabetes have been progressively increasing worldwide and treatments have failed to counteract their progression. Growing evidence have demonstrated that gut microbiota is associated with the incidence of these pathologies. Hence, the identification of new nutritional compounds, able to improve health through a modulation of gut microbiota, is gaining interest. In this context, the aim of this study was to investigate the gut-driving effects of rhubarb extract in a context of diet-induced obesity and diabetes. Eight weeks old C57BL6/J male mice were fed a control diet (CTRL), a high fat and high sucrose diet (HFHS) or a HFHS diet supplemented with 0.3% (g/g) of rhubarb extract for eight weeks. Rhubarb supplementation fully prevented HFHS-induced obesity, diabetes, visceral adiposity, adipose tissue inflammation and liver triglyceride accumulation, without any modification in food intake. By combining sequencing and qPCR methods, we found that all these effects were associated with a blooming of Akkermansia muciniphila, which is strongly correlated with increased expression of Reg3γ in the colon. Our data showed that rhubarb supplementation is sufficient to protect against metabolic disorders induced by a diet rich in lipid and carbohydrates in association with a reciprocal interaction between Akkermansia muciniphila and Reg3γ.

Pasteurized Akkermansia muciniphila increases whole-body energy expenditure and fecal energy excretion in diet-induced obese mice

Accumulating evidence points to Akkermansia muciniphila as a novel candidate to prevent or treat obesity-related metabolic disorders. We recently observed, in mice and in humans, that pasteurization of A. muciniphila increases its beneficial effects on metabolism. However, it is currently unknown if the observed beneficial effects on body weight and fat mass gain are due to specific changes in energy expenditure. Therefore, we investigated the effects of pasteurized A. muciniphila on whole-body energy metabolism during high-fat diet feeding by using metabolic chambers. We confirmed that daily oral administration of pasteurized A. muciniphila alleviated diet-induced obesity and decreased food energy efficiency. We found that this effect was associated with an increase in energy expenditure and spontaneous physical activity. Strikingly, we discovered that energy expenditure was enhanced independently from changes in markers of thermogenesis or beiging of the white adipose tissue. However, we found in brown and white adipose tissues that perilipin2, a factor associated with lipid droplet and known to be altered in obesity, was decreased in expression by pasteurized A. muciniphila. Finally, we observed that treatment with pasteurized A. muciniphila increased energy excretion in the feces. Interestingly, we demonstrated that this effect was not due to the modulation of intestinal lipid absorption or chylomicron synthesis but likely involved a reduction of carbohydrates absorption and enhanced intestinal epithelial turnover. In conclusion, this study further dissects the mechanisms by which pasteurized A. muciniphila reduces body weight and fat mass gain. These data also further support the impact of targeting the gut microbiota by using specific bacteria to control whole-body energy metabolism.

Effects of Nondigestible Oligosaccharides on Obesity

Obesity is a major public health concern that has almost reached the level of pandemic and is rapidly progressing. The gut microbiota has emerged as a crucial regulator involved in the etiology of obesity, and the manipulation of it by dietary intervention has been widely used for reducing the risk of obesity. Nondigestible oligosaccharides (NDOs) are attracting increasing interests as prebiotics, as the indigestible ingredients can induce compositional or metabolic improvement to the gut microbiota, thereby improving gut health and giving rise to the production of short-chain fatty acids (SCFAs) to elicit metabolic effects on obesity. In this review, the role NDOs play in obesity intervention via modification of the gut microecology, as well as the physicochemical and physiological properties and industrial manufacture of NDOs, is discussed. Our goal is to provide a critical assessment of and stimulate comprehensive research into NDO use in obesity.

The Janus Face of Cereals: Wheat-Derived Prebiotics Counteract the Detrimental Effect of Gluten on Metabolic Homeostasis in Mice Fed a High-Fat/High-Sucrose Diet

SCOPE

Cereals are important sources of carbohydrates, but also contain nutrients that could impact adiposity. The contribution of gluten to obesity and the effects of prebiotics-arabinoxylo-oligosaccharides (AXOS) and fructo-oligosaccharides (FOS)-that can be extracted from gluten-containing cereals are analyzed.

METHODS AND RESULTS

Mice are fed a control diet, Western diet (WD, consisting of high fat/high sucrose), or WD with 5% gluten. Prebiotics are tested in the WD with gluten. Gluten does not increase body weight and has a minor effect on ileal inflammation. Gluten decreases the expression of browning markers in the fat and increases the triglycerides synthesis in the muscle. AXOS decreases body weight and adiposity in fat pads muscle and liver. AXOS promotes gluten cleavage by the induction of prolyl endopeptidase that is translated into a reduction of gluten immunogenic peptides. Gluten has minor effects on cecal microbiota composition, whereas prebiotics increased Bifidobacterium, Butyricicoccus, Prevotella, and Parasutterella, which are all negatively correlated to the cecal content of gluten peptides.

CONCLUSION

While gluten may affect metabolic homeostasis, these effects are lessened when gluten is consumed along with cereal-derived fibers. If confirmed in humans, the authors bring new arguments to eat fiber-rich cereals to promote a healthy diet.

Gut microbiota-mediated inflammation in obesity: a link with gastrointestinal cancer

Overweight and obesity are associated with increased risk of developing metabolic disorders such as diabetes and cardiovascular diseases. However, besides these metabolic diseases, excess body weight is also associated with different cancers, including gastrointestinal cancers, such as liver, pancreatic and colon cancers. Inflammation is a common feature of both obesity and cancer; however, the origin of this inflammation has been largely debated. Over the past decade, growing evidence has shown that the composition of the gut microbiota and its activity might be associated not only with the onset of inflammation but also with metabolic disorders and cancer. Here, we review the links between the gut microbiota, gut barrier function and the onset of low-grade inflammation in the development of gastrointestinal cancer. We also describe the mechanisms by which specific microorganism-associated molecular patterns crosstalk with the immune system and how the metabolic activity of bacteria induces specific signalling pathways beyond the gut that eventually trigger carcinogenesis.

Interactions between gut microbes and host cells control gut barrier and metabolism

Gut microbes are now considered as key partners involved in human physiology. Data have shown that microbes contribute to regulate energy, lipid, and glucose homeostasis through several mechanisms. Among them, the role of pathogen-associated molecular pattern and bacterial metabolites has been proposed (for example, metabolic endotoxemia and bioactive lipids). This short review, briefly discusses the role of the gut barrier as well as the impact of both the innate immune system and bioactive molecules (for example, endocannabinoids, cytochrome P450 derived arachidonic acids compounds) in the framework of gut microbes and cardiometabolic disorders.

Rhubarb extract prevents hepatic inflammation induced by acute alcohol intake, an effect related to the modulation of the gut microbiota

SCOPE

Binge consumption of alcohol is an alarming global health problem. Acute ethanol intoxication is characterized by hepatic inflammation and oxidative stress, which could be promoted by gut barrier function alterations. In this study, we have tested the hypothesis of the hepatoprotective effect of rhubarb extract in a mouse model of binge drinking and we explored the contribution of the gut microbiota in the related metabolic effects.

METHODS AND RESULTS

Mice were fed a control diet supplemented with or without 0.3% rhubarb extract for 17 days and were necropsied 6 h after an alcohol challenge. Supplementation with rhubarb extract changed the microbial ecosystem (assessed by 16S rDNA pyrosequencing) in favor of Akkermansia muciniphila and Parabacteroides goldsteinii. Furthermore, it improved alcohol-induced hepatic injury, downregulated key markers of both inflammatory and oxidative stresses in the liver tissue, without affecting significantly steatosis. In the gut, rhubarb supplementation increased crypt depth, tissue weight, and the expression of antimicrobial peptides.

CONCLUSIONS

These findings suggest that some bacterial genders involved in gut barrier function, are promoted by phytochemicals present in rhubarb extract, and could therefore be involved in the modulation of the susceptibility to hepatic diseases linked to acute alcohol consumption.

Pancreatic α-Amylase Controls Glucose Assimilation by Duodenal Retrieval through N-Glycan-specific Binding, Endocytosis, and Degradation

α-Amylase, a major pancreatic protein and starch hydrolase, is essential for energy acquisition. Mammalian pancreatic α-amylase binds specifically to glycoprotein N-glycans in the brush-border membrane to activate starch digestion, whereas it significantly inhibits glucose uptake by Na(+)/glucose cotransporter 1 (SGLT1) at high concentrations (Asanuma-Date, K., Hirano, Y., Le, N., Sano, K., Kawasaki, N., Hashii, N., Hiruta, Y., Nakayama, K., Umemura, M., Ishikawa, K., Sakagami, H., and Ogawa, H. (2012) Functional regulation of sugar assimilation by N-glycan-specific interaction of pancreatic α-amylase with glycoproteins of duodenal brush border membrane. J. Biol. Chem. 287, 23104-23118). However, how the inhibition is stopped was unknown. Here, we show a new mechanism for the regulation of intestinal glucose absorption. Immunohistochemistry revealed that α-amylase in the duodena of non-fasted, but not fasted, pigs was internalized from the pancreatic fluid and immunostained. We demonstrated that after N-glycan binding, pancreatic α-amylase underwent internalization into lysosomes in a process that was inhibited by α-mannoside. The internalized α-amylase was degraded, showing low enzymatic activity and molecular weight at the basolateral membrane. In a human intestinal Caco-2 cell line, Alexa Fluor 488-labeled pancreatic α-amylase bound to the cytomembrane was transported to lysosomes through the endocytic pathway and then disappeared, suggesting degradation. Our findings indicate that N-glycan recognition by α-amylase protects enterocytes against a sudden increase in glucose concentration and restores glucose uptake by gradual internalization, which homeostatically controls the postprandial blood glucose level. The internalization of α-amylase may also enhance the supply of amino acids required for the high turnover of small intestine epithelial cells. This study provides novel and significant insights into the control of blood sugar during the absorption stage in the intestine.

Microbiome of prebiotic-treated mice reveals novel targets involved in host response during obesity

The gut microbiota is involved in metabolic and immune disorders associated with obesity and type 2 diabetes. We previously demonstrated that prebiotic treatment may significantly improve host health by modulating bacterial species related to the improvement of gut endocrine, barrier and immune functions. An analysis of the gut metagenome is needed to determine which bacterial functions and taxa are responsible for beneficial microbiota-host interactions upon nutritional intervention. We subjected mice to prebiotic (Pre) treatment under physiological (control diet: CT) and pathological conditions (high-fat diet: HFD) for 8 weeks and investigated the production of intestinal antimicrobial peptides and the gut microbiome. HFD feeding significantly decreased the expression of regenerating islet-derived 3-gamma (Reg3g) and phospholipase A2 group-II (PLA2g2) in the jejunum. Prebiotic treatment increased Reg3g expression (by ∼50-fold) and improved intestinal homeostasis as suggested by the increase in the expression of intectin, a key protein involved in intestinal epithelial cell turnover. Deep metagenomic sequencing analysis revealed that HFD and prebiotic treatment significantly affected the gut microbiome at different taxonomic levels. Functional analyses based on the occurrence of clusters of orthologous groups (COGs) of proteins also revealed distinct profiles for the HFD, Pre, HFD-Pre and CT groups. Finally, the gut microbiota modulations induced by prebiotics counteracted HFD-induced inflammation and related metabolic disorders. Thus, we identified novel putative taxa and metabolic functions that may contribute to the development of or protection against the metabolic alterations observed during HFD feeding and HFD-Pre feeding.

Short toxin-like proteins attack the defense line of innate immunity

ClanTox (classifier of animal toxins) was developed for identifying toxin-like candidates from complete proteomes. Searching mammalian proteomes for short toxin-like proteins (coined TOLIPs) revealed a number of overlooked secreted short proteins with an abundance of cysteines throughout their sequences. We applied bioinformatics and data-mining methods to infer the function of several top predicted candidates. We focused on cysteine-rich peptides that adopt the fold of the three-finger proteins (TFPs). We identified a cluster of duplicated genes that share a structural similarity with elapid neurotoxins, such as α-bungarotoxin. In the murine proteome, there are about 60 such proteins that belong to the Ly6/uPAR family. These proteins are secreted or anchored to the cell membrane. Ly6/uPAR proteins are associated with a rich repertoire of functions, including binding to receptors and adhesion. Ly6/uPAR proteins modulate cell signaling in the context of brain functions and cells of the innate immune system. We postulate that TOLIPs, as modulators of cell signaling, may be associated with pathologies and cellular imbalance. We show that proteins of the Ly6/uPAR family are associated with cancer diagnosis and malfunction of the immune system.

Survival of exfoliated epithelial cells: a delicate balance between anoikis and apoptosis

The recovery of exfoliated cells from biological fluids is a noninvasive technology which is in high demand in the field of translational research. Exfoliated epithelial cells can be isolated from several body fluids (i.e., breast milk, urines, and digestives fluids) as a cellular mixture (senescent, apoptotic, proliferative, or quiescent cells). The most intriguing are quiescent cells which can be used to derive primary cultures indicating that some phenotypes retain clonogenic potentials. Such exfoliated cells are believed to enter rapidly in anoikis after exfoliation. Anoikis can be considered as an autophagic state promoting epithelial cell survival after a timely loss of contact with extracellular matrix and cell neighbors. This paper presents current understanding of exfoliation along with the influence of methodology on the type of gastrointestinal epithelial cells isolated and, finally, speculates on the balance between anoikis and apoptosis to explain the survival of gastrointestinal epithelial cells in the environment.

Non-invasive exploration of neonatal gastric epithelium by using exfoliated epithelial cells

Background & Aims

In preterm infants, exfoliated gastric epithelial cells can be retrieved from aspirates sampled through the naso-gastric feeding tube. Our aims were to determine (1) whether the recovery of exfoliated cells is feasible at any time from birth through the removal of the nasogastric tube, (2) whether they can be grown in culture in vitro, and (3) whether the physiological state of exfoliated cells expressing H+/K+ -ATPases reflects that of their counterparts remaining in situ at the surface of the gastric epithelium in neonatal rat pups.

Methods

In infants, gastric fluid aspirates were collected weekly after birth or every 3 hours over 24-h periods, and related to clinical parameters (Biocollection PROG/09/18). In rat pups submitted to a single fasting/refeeding cycle, we explored circadian exfoliation with the cellular counter-parts in the gland. All samples were analyzed by confocal imaging and Enzyme-Linked Immunosorbent Assay.

Results

Epithelial cells were identified by microscopy using membrane-bound anti-H+/K+ ATPases antibody, assessed for nucleus integrity, and the expression of selected proteins (autophagy, circadian clock). On 34 infants, the H+/K+ -ATPase-positive cells were consistently found quiescent, regardless of gestational age and feeding schedule from day-5 of life to the day of removal of the naso-gastric tube. By logistic regression analysis, we did find a positive correlation between the intensity of exfoliation (cellular loss per sample) and the postnatal age (p<0.001). The H+/K+ ATPase-positive cells established in culture retained the expression of a biomarker of progenitor status (Pouf5F1-Oct4). In rat pups, the expression pattern of Survivin in H+/K+ ATPase-positive exfoliated cells paralleled that observed in cells remaining at the surface of the gastric gland.

Conclusions

Tracking parietal cells can improve clinical monitoring and understanding of the autophagic death via the phosphatidylinositol 3-kinase/Akt/survivin pathway.

Exfoliated epithelial cells: potentials to explore gastrointestinal maturation of preterm infants

Exfoliated epithelial cells represent valuable source of information on the physiopathological state of the mucosa. However, the interpretation of data obtained from exfoliated cells is complicated by the conditions of isolation as well as the health of the subject. Exfoliation is either: a) a natural loss of body cells implying a molecular signal related to the turnover of terminally differentiated cells and to the progressive mobilization of proliferative as well as stem cells or b) the result of manual exfoliation by applying mechanical constraints like scraping. Depending on the methodology of isolation, exfoliated epithelial cells are believed to be either in apoptosis or in anoïkis. Most studies are using microscopic examination to demonstrate the presence of typical cells along with measurements on a limited number of biomarkers. Only few studies using proteomics or transcriptomics are available and they open discussion about tissue references and normalization. The main advantage of measures realized on exfoliated epithelial cells is that they are strictly non-invasive and open the possibility to evaluate maturation of gastric and intestinal tissues in long-term experiments performed on the same animal or in translational research on samples recovered from preterm infants.

The major locus for mouse adenovirus susceptibility maps to genes of the hematopoietic cell surface-expressed LY6 family

Susceptibility to mouse adenovirus type 1 is associated with the major quantitative trait locus Msq1. Msq1 was originally mapped to a 13-Mb region of mouse chromosome (Chr) 15 in crosses between SJL/J and BALB/cJ inbred mice. We have now narrowed Msq1 to a 0.75-Mb interval from 74.68 to 75.43 Mb, defined by two anonymous markers, rs8259436 and D15Spn14, using data from 1396 backcross mice. The critical interval includes 14 Ly6 or Ly6-related genes, including Ly6a (encoding Sca-1/TAP), Ly6e (Sca-2/Tsa1), Ly6g (Gr-1), and gpihbp1 (GPI-anchored high-density lipoprotein-binding protein 1), as well as the gene encoding an aldosterone synthase (Cyp11b2). The Ly6 family members are attractive candidates for virus susceptibility genes because their products are GPI-anchored membrane proteins expressed on lymphoid and myeloid cells, with proposed functions in cell adhesion and cell signaling. To determine interstrain variation in susceptibility and produce additional resources for cloning Msq1, we assayed the susceptibility phenotype of four previously untested inbred mouse strains. Susceptibility of strain 129S6/SvEvTac was subsequently localized to the Ly6 complex region, using polymorphic genetic markers on Chr 15 in a population of 271 (129S6/SvEvTac x BALB/cJ)F(1) x BALB/cJ backcross mice. We identified a major 129S6/SvEvTac susceptibility allele, Msq1(129S6), on Chr 15 in the same region as Msq1(SJL). The results indicate that a major host factor in mouse adenovirus type 1 susceptibility is likely to be a member of the Ly6 gene family.

Attenuation of apoptosis in enterocytes by blockade of potassium channels

Apoptosis plays an important role in maintaining the balance between proliferation and cell loss in the intestinal epithelium. Apoptosis rates may increase in intestinal pathologies such as inflammatory bowel disease and necrotizing enterocolitis, suggesting pharmacological prevention of apoptosis as a therapy for these conditions. Here, we explore the feasibility of this approach using the rat epithelial cell line IEC-6 as a model. On the basis of the known role of K+ efflux in apoptosis in various cell types, we hypothesized that K+ efflux is essential for apoptosis in enterocytes and that pharmacological blockade of this efflux would inhibit apoptosis. By probing intracellular [K+] with the K+-sensitive fluorescent dye and measuring the efflux of 86Rb+, we found that apoptosis-inducing treatment with the proteasome inhibitor MG-132 leads to a twofold increase in K+ efflux from IEC-6 cells. Blockade of K+ efflux with tetraethylammonium, 4-aminopyridine, stromatoxin, chromanol 293B, and the recently described K+ channel inhibitor 48F10 prevents DNA fragmentation, caspase activation, release of cytochrome c from mitochondria, and loss of mitochondrial membrane potential. Thus K+ efflux occurs early in the apoptotic program and is required for the execution of later events. Apoptotic K+ efflux critically depends on activation of p38 MAPK. These results demonstrate for the first time the requirement of K+ channel-mediated K+ efflux for progression of apoptosis in enterocytes and suggest the use of K+ channel blockers to prevent apoptotic cell loss occurring in intestinal pathologies.