Mouse Small Intestine Research Articles

Permeation of Hydroxypropyl-Beta-Cyclodextrin and Its Inclusion Complex Through Mouse Small Intestine Determined by Spectrophotometry

Background: Cyclodextrins (CDs) are commonly used host molecules of inclusion complex. However, due to the lack of a sensitive determination method, the absorption process of CDs remains unclear. Objective: In this study, an oleuropein (OL) inclusion complex employing hydroxylpropyl-betacyclodextrin (HP-beta-CD) as host molecules was prepared and the formation of inclusion complex was ascertained by FT-IR and DSC. Spectrophotometry was established for the determination of HP-beta-CD, based on the fact that the absorbance of phenolphthalein (PP) decreased in the presence of HP-beta-CD. Methods: The assay conditions were optimized to augment the method sensitivity. Molecular docking was employed to verify the strong interaction between PP and HP-beta-CD. The permeation process of free HP-beta-CD, HP-beta-CD of OL inclusion complex, free OL, and OL in the inclusion complex, was examined using an in vitro mouse small intestine model. Results: Though HP-beta-CD possessed a hydrophilic outside shell, it could permeate through the mouse small intestine quickly with a cumulative permeating amount of over 90% in 2 h. Free HPbeta- CD, the host molecule HP-beta-CD, and guest molecule OL of the inclusion complex exhibited consistent permeating profiles across the mouse small intestine. Conclusion: The approach for the determination of HP-beta-CD was accurate and precise (%RSD=2.98).

Classification of pacemaker dynamics in the mouse intestine by field potential microimaging

The flexible and sophisticated movement of the gastrointestinal (GI) tract implies the involvement of mechanisms other than enteric neural circuits, to coordinate excitation in microregions. We thus performed microimaging of pacemaker dynamics in the small intestine of mice since it contains typical network-forming pacemaker cells. A dialysis membrane-reinforced low-impedance microelectrode array (MEA) enabled field potentials over a wide frequency range to be stably measured in microregions. The pacemaker dynamics were classified into basic patterns despite large variations. In the developmental process, pacemaker activity was categorized as either an ‘expanding’ or a ‘migrating’ pattern that was initiated in or propagated to the MEA sensing area, respectively. The intercellular current of the volume conductor complicated the waveform of both activities. The existence of ‘expanding’ and ‘migrating’ patterns was attributable to duplicated pacemaker systems such as intracellular Ca2+ oscillation-activated and voltage-gated mechanisms. Additionally, from the spatio-temporal feature during the period of pacemaker events, the ‘bumpy/aberrant’ pattern was defined by aberrant, incoherent propagation, and associated with local impairment of excitability, while the ‘colliding/converging’ pattern involved the interaction of multiple activities in the MEA area. Interconversion between the four micro-coordination patterns occurred in the same microregion. 5-Hydroxytryptamine (5-HT) promoted ‘migrating’ activity, implying an improvement or restoration of spatial conductivity. These results agree well with the action of 5-HT to change GI movement toward propulsion. In conclusion, our MEA method of microimaging classification enables the quantitative assessment of spatio-temporal electric coordination underlying GI motility, suggesting its application to small model animals.

P032 Host transcriptome signatures in human fecal-washes predict histological remission in IBD patients

Abstract Background Colonoscopy is the gold standard for evaluation of inflammation in inflammatory bowel diseases (IBD), yet entails cumbersome preparations and risks of injury. Existing non-invasive prognostic tools are limited in their diagnostic power. Moreover, transcriptomics of colonic biopsies have been inconclusive in their association with clinical features. Our aim was to assess the utility of host transcriptomics of fecal wash samples of IBD patients compared to controls. Methods In this prospective cohort study, we obtained biopsies and fecal-wash samples from IBD patients and controls undergoing lower endoscopy. We performed RNAseq of biopsies and matching fecal-washes, and associated them with endoscopic and histological inflammation status. We also performed fecal mass-spectrometry proteomics on a subset of samples. We inferred cell compositions using computational deconvolution and used classification algorithms to identify informative genes. Results We analyzed biopsies and fecal washes from 39 patients (19 IBD, 20 controls). Host fecal-transcriptome carried information that was distinct from biopsy RNAseq and fecal proteomics. Transcriptomics of fecal washes, yet not of biopsies, from patients with histological inflammation were significantly correlated to one another (p=5.3*10–12). Fecal-transcriptome was significantly more powerful in identifying histological inflammation compared to transcriptome of intestinal biopsies (150 genes with area-under-the-curve >0.9 in fecal samples versus 10 genes in biopsy RNAseq). Fecal samples were enriched in inflammatory monocytes, regulatory T cells, natural killer-cells and innate lymphoid cells. Figure 1 - Fecal-wash host transcriptome predicts histological inflammation. A) Study layout, B) Clustergram of fecal-wash host cell mRNA signatures, demonstrating that patients with histological inflammation (red) are clustered when measuring fecal wash transcriptome yet not biopsy transcriptomes. C-D) Principle Component Analysis demonstrating improved separation of inflamed patients based on fecal host transcriptomes. E, F) Expression of host genes in fecal washes has higher statistical power (Area under the Curve, AUC) in classifying histological inflammation compared to biopsies. D shows NFKBIA as an example, E shows the AUC of the 5% best classifying genes, F shows the overall AUC based on biopsies or washes. Gray areas have AUC>0.9. G) UMAP of cells obtained from scRNAseq of mouse small intestine fecal washes. Conclusion Fecal wash host transcriptome is a powerful biomarker reflecting histological inflammation. Furthermore, it opens the way to identifying important correlates and therapeutic targets that may be obscure using biopsy transctriptomics.

Potent bactericidal activity of reduced cryptdin-4 derived from its hydrophobicity and mediated by bacterial membrane disruption.

Defensin is a cysteine-rich antimicrobial peptide with three disulphide bonds under normal oxidative conditions. Cryptdin-4 (Crp4) is a defensin secreted by Paneth cells in the small intestine of mice, and only reduced Crp4 (Crp4red) shows activity against enteric commensal bacteria, although both oxidised Crp4 (Crp4ox) and Crp4red can kill non-commensal bacteria. To investigate the molecular factors that affect the potent antimicrobial activity of Crp4red, the bactericidal activities of Crp4ox and Crp4red, Crp4 with all Cys residues substituted with Ser peptide (6C/S-Crp4), and Crp4 with all thiol groups modified by N-ethylmaleimide (NEM-Crp4) were assessed. All peptides showed bactericidal activity against non-commensal bacteria, whereas Crp4red and NEM-Crp4 showed bactericidal activity against commensal bacteria. These potent peptides exhibited high hydrophobicity, which was strongly correlated with membrane insertion. Intriguingly, Crp4ox formed electrostatic interactions with the membrane surface of bacteria, even without exerting bactericidal activity. Moreover, the bactericidal activity of both oxidised and reduced forms of Crp4 was abolished by inhibition of electrostatic interactions; this finding suggests that Crp4red targets bacterial membranes. Finally, a liposome leakage assay against lipids extracted from commensal bacteria demonstrated a correlation with bactericidal activity. These results suggest that the potent bactericidal activity of Crp4red is derived from its hydrophobicity, and the bactericidal mechanism involves disruption of the bacterial membrane. Findings from this study provide a better understanding of the bactericidal mechanism of both Crp4ox and Crp4red.

ID2 controls differentiation of enteroendocrine cells in mouse small intestine.

The mammalian gut is the largest endocrine organ. Dozens of hormones secreted by enteroendocrine cells regulate a variety of physiological functions of the gut but also of the pancreas and brain. Here, we examined the role of the helix-loop-helix transcription factor ID2 during the differentiation of intestinal stem cells along the enteroendocrine lineage. To assess the functions of ID2 in the adult mouse small intestine, we used single-cell RNA sequencing, genetically modified mice, and organoid assays. We found that in the adult intestinal epithelium Id2 is predominantly expressed in enterochromaffin and peptidergic enteroendocrine cells. Consistently, the loss of Id2 leads to the reduction of Chromogranin A-positive enteroendocrine cells. In contrast, the numbers of tuft cells are increased in Id2 mutant small intestine. Moreover, ablation of Id2 elevates the numbers of Serotonin+ enterochromaffin cells and Ghrelin+ X-cells in the posterior part of the small intestine. Finally, ID2 acts downstream of BMP signalling during the differentiation of Glucagon-like peptide-1+ L-cells and Cholecystokinin+ I-cells towards Neurotensin+ PYY+ N-cells. ID2 plays an important role in cell fate decisions in the adult small intestine. First, ID2 is essential for establishing a differentiation gradient for enterochromaffin and X-cells along the anterior-posterior axis of the gut. Next, ID2 is necessary for the differentiation of N-cells thus ensuring a differentiation gradient along the crypt-villi axis. Finally, ID2 suppresses the commitment of secretory intestinal epithelial progenitors towards tuft cell lineage and thus controls host immune response to commensal and parasitic microbiota.

Alterations of nitric oxide homeostasis as trigger of intestinal barrier dysfunction in non-alcoholic fatty liver disease.

Changes in intestinal nitric oxide metabolism are discussed to contribute for the development of intestinal barrier dysfunction in non‐alcoholic fatty liver disease (NAFLD). To induce steatosis, female C57BL/6J mice were pair‐fed with a liquid control diet (C) or a fat‐, fructose‐ and cholesterol‐rich diet (FFC) for 8 weeks. Mice received the diets ± 2.49 g L‐arginine/kg bw/day for additional 5 weeks. Furthermore, mice fed C or FFC ± L‐arginine/kg bw/day for 8 weeks were concomitantly treated with the arginase inhibitor Nω‐hydroxy‐nor‐L‐arginine (nor‐NOHA, 0.01 g/kg bw). Liver damage, intestinal barrier function, nitric oxide levels and arginase activity in small intestine were assessed. Also, arginase activity was measured in serum from 13 patients with steatosis (NAFL) and 14 controls. The development of steatosis with beginning inflammation was associated with impaired intestinal barrier function, increased nitric oxide levels and a loss of arginase activity in small intestine in mice. L‐arginine supplementation abolished the latter along with an improvement of intestinal barrier dysfunction; nor‐NOHA attenuated these effects. In patients with NAFL, arginase activity in serum was significantly lower than in healthy controls. Our data suggest that increased formation of nitric oxide and a loss of intestinal arginase activity is critical in NAFLD‐associated intestinal barrier dysfunction.

Effects of black garlic on the pacemaker potentials of interstitial cells of Cajal in murine small intestine in vitro and on gastrointestinal motility in vivo

ABSTRACT Black garlic (BG) is a newly explored food stuff obtained via fermentation of raw, healthy garlic, especially in Asian countries. Interstitial cells of Cajal (ICC) are the pacemaker cells of gastrointestinal (GI) motility. The purpose of this study was to investigate the effects of BG extract on the pacemaker potentials of the ICC in the small intestines of mice and the possibility of controlling GI motility. The antioxidant activity of BG extract was also investigated. The whole-cell electrophysiological method was used to measure pacemaker potentials of the ICC in vitro, whereas GI motility was measured using the intestinal transit rate (ITR) in vivo. BG extract depolarized the pacemaker potentials of the ICC. Y25130 and RS39604 5-HT receptor antagonists could not inhibit the effect of BG extract on the pacemaker potentials of the ICC, whereas the 5-HT receptor antagonist SB269970 could. Pre-treatment with external Na+ (5 mM) or Ca2+-free solution inhibited the BG extract-induced depolarization of the ICC. With SB203580, PD98059, or c-jun NH2-terminal kinase II inhibitor pre-treatment, BG extract did not induce pacemaker potential depolarization. Moreover, the ITR values were increased by BG extract. Elevation of the ITR due to BG extract was related with increased protein expression of the 5-HT7 receptors. In addition, BG extract showed antioxidant activity. Collectively, these results highlight the ability of BG extract to regulate GI motility and the possibility of using it to develop GI motility modulators in the future. Moreover, BG showed immense potential as an antioxidant.

Cystine and Theanine as Stress-Reducing Amino Acids-Perioperative Use for Early Recovery after Surgical Stress.

Perioperative nutritional therapy requires the consideration of metabolic changes, and it is desirable to reduce stress aiming at early metabolic normalization. Glutathione (GSH) is a tripeptide composed of glutamic acid, cysteine, and glycine. It is one of the strongest antioxidants in the body and important for adjusting immune function. Cystine and theanine (γ-glutamylethylamide) provide substrates of GSH, cysteine and glutamic acid, promoting the synthesis of GSH. It has been reported that the ingestion of cystine (700 mg) and theanine (280 mg) exhibits inhibitory effects against excess inflammation after strong exercise loads in athletes, based on which its application for invasive surgery has been tried. In patients undergoing gastrectomy, ingestion of cystine (700 mg) and theanine (280 mg) for 10 days from 5 days before surgery inhibited a postoperative increase in resting energy expenditure, promoted recovery from changes in interleukin-6, C-reactive protein, lymphocyte ratio, and granulocyte ratio and inhibited an increase in body temperature. In a mouse small intestine manipulation model, preoperative 5-day administration of cystine/theanine inhibited a postoperative decrease in GSH in the small intestine and promoted recovery from a decrease in behavior quantity. Based on the above, cystine/theanine reduces surgical stress, being useful for perioperative management as stress-reducing amino acids.

Crypt and Villus Transcriptomic Responses in Mouse Small Intestine Following Oral Exposure to Hexavalent Chromium.

Oral exposure to hexavalent chromium (Cr(VI)) induces tumors in the mouse duodenum. Previous microarray-based transcriptomic analyses of homogenized mouse duodenal tissue have demonstrated Cr(VI)-induced alterations in various cellular pathways and processes. However, X-ray fluorescence microscopy indicates that chromium localizes primarily to the duodenal villi following exposure to Cr(VI), suggesting that previous transcriptomic analyses of homogenized tissue provide an incomplete picture of transcriptomic responses in the duodenum. Herein, transcriptomic analyses were conducted separately on crypt and villus tissue from formalin-fixed paraffin-embedded transverse duodenal sections from the same study in which microarray-based analyses were previously conducted. A total of 28 groups (7 doses × 2 timepoints × 2 tissue compartments) were analyzed for differential gene expression, dose-response, and gene set enrichment. Tissue compartment isolation was confirmed by differences in expression of typical markers of crypt and villus compartments. Fewer than 21 genes were altered in the crypt compartment of mice exposed to 0.1-5 ppm Cr(VI) for 7 or 90 days, which increased to hundreds or thousands of genes at ≥20 ppm Cr(VI). Consistent with histological evidence for crypt proliferation, a significant, dose-dependent increase in genes that regulate mitotic cell cycle was prominent in the crypt, while subtle in the villus, when compared with samples from time-matched controls. Minimal transcriptomic evidence of DNA damage response in either the crypts or the villi is consistent with published in vivo genotoxicity data. These results are also discussed in the context of modes of action that have been proposed for Cr(VI)-induced small intestine tumors in mice.

Olfactomedin 4 Is Not a Precise Marker for Human Intestinal Stem Cells, But Is Involved in Intestinal Carcinogenesis

Olfactomedin 4 Is Not a Precise Marker for Human Intestinal Stem Cells, But Is Involved in Intestinal Carcinogenesis

Radiosensitisation of SCCVII tumours and normal tissues in mice by the DNA-dependent protein kinase inhibitor AZD7648

Background and purposeInhibitors of DNA-dependent protein kinase (DNA-PK) are effective radiation sensitisers in preclinical tumours, but little is known about risks of normal tissue radiosensitisation. Here, we evaluate radiosensitisation of head and neck squamous cell carcinoma (HNSCC) cells by DNA-PK inhibitor AZD7648 under oxia and anoxia in vitro, and tumour (SCCVII), oral mucosa and small intestine in mice. Materials and methodsRadiosensitisation of human (UT-SCC-54C) and murine (SCCVII) HNSCC cells by AZD7648 under oxia and anoxia was evaluated by clonogenic assay. Radiosensitisation of SCCVII tumours in C3H mice by oral AZD7648 (75 mg/kg) was determined by ex vivo clonogenic assay 3.5 days post-irradiation, with evaluation of normal tissue surrogate endpoints using 5-ethynyl-2′-deoxyuridine to facilitate detection of regenerating crypts in the ileum and repopulating S-phase cells in the ileum and oral mucosa of the same animals. ResultsAZD7648 potently radiosensitised both cell lines, with similar sensitiser enhancement ratios for 10% survival (SER10) under oxia and anoxia. AZD7648 diffused rapidly through multicellular layers, suggesting rapid equilibration between plasma and hypoxic zones in tumours. SCCVII tumours were radiosensitised by AZD7648 (SER10 2.5). AZD7648 also enhanced radiation-induced body weight loss and suppressed regenerating intestinal crypts and repopulating S-phase cells in the ileum and tongue epithelium with SER values similar to SCCVII tumours. ConclusionAZD7648 is a potent radiation sensitiser of both oxic and anoxic tumour cells, but also markedly radiosensitises stem cells in the small intestine and oral mucosa.

Short-Chain Fatty Acid Decreases the Expression of CEBPB to Inhibit miR-145-Mediated DUSP6 and Thus Further Suppresses Intestinal Inflammation.

Intestinal inflammation is a common disease which can further lead to inflammatory bowel disease and even intestinal cancer. The increasing focus has come to the role of short-chain fatty acid (SCFA) in various bowel diseases. Hence, this study was designed to explore the specific role of SCFA in intestinal inflammation. In vivo and in vitro models of intestinal inflammation were constructed by lipopolysaccharide (LPS) injection in mice and LPS treatment on intestinal epithelial cells. A possible regulatory mechanism involving SCFA, CCAAT enhancer-binding protein beta (CEBPB), microRNA-145 (miR-145), and dual-specificity phosphatase 6 (DUSP6) in intestinal inflammation was verified by ChIP assay and dual-luciferase reporter gene assay. To evaluate the effects of SCFA on LPS-treated intestinal epithelial cells, the expression of relevant genes and inflammatory factors (IL-6, TNF-α, and IL-1β) were determined. Last, the role of SCFA in vivo was explored through the scoring of disease activity index (DAI) and observation of colonic histology of LPS-treated mice. SCFA decreased the CEBPB expression in mouse colon tissues and small intestine epithelial cells induced by LPS. Furthermore, CEBPB could bind to the miR-145 promoter to inhibit its expression, thereby promoting the expression of DUSP6. In addition, SCFA improved the DAI, colonic histology, and the expression of serum inflammatory factors in LPS-treated mice and cells, noting that SCFA alleviated intestinal inflammation in vitro and in vivo. To sum up, SCFA inhibited DUSP6 by upregulating miR-145 through CEBPB repression and thus prevented the development of intestinal inflammation.

Identification of SSRI-evoked antidepressant sensory signals by decoding vagus nerve activity

The vagus nerve relays mood-altering signals originating in the gut lumen to the brain. In mice, an intact vagus is required to mediate the behavioural effects of both intraluminally applied selective serotonin reuptake inhibitors and a strain of Lactobacillus with antidepressant-like activity. Similarly, the prodepressant effect of lipopolysaccharide is vagus nerve dependent. Single vagal fibres are broadly tuned to respond by excitation to both anti- and prodepressant agents, but it remains unclear how neural responses encode behaviour-specific information. Here we demonstrate using ex vivo experiments that for single vagal fibres within the mesenteric neurovascular bundle supplying the mouse small intestine, a unique neural firing pattern code is common to both chemical and bacterial vagus-dependent antidepressant luminal stimuli. This code is qualitatively and statistically discernible from that evoked by lipopolysaccharide, a non-vagus-dependent antidepressant or control non-antidepressant Lactobacillus strain and are not affected by sex status. We found that all vagus dependent antidepressants evoked a decrease in mean spike interval, increase in spike burst duration, decrease in gap duration between bursts and increase in intra-burst spike intervals. Our results offer a novel neuronal electrical perspective as one explanation for mechanisms of action of gut-derived vagal dependent antidepressants. We expect that our ex vivo individual vagal fibre recording model will improve the design and operation of new, extant electroceutical vagal stimulation devices currently used to treat major depression. Furthermore, use of this vagal antidepressant code should provide a valuable screening tool for novel potential oral antidepressant candidates in preclinical animal models.

Spatial gene expression maps of the intestinal lymphoid follicle and associated epithelium identify zonated expression programs.

The intestine is lined with isolated lymphoid follicles (ILFs) that facilitate sampling of luminal antigens to elicit immune responses. Technical challenges related to the scarcity and small sizes of ILFs and their follicle-associated epithelium (FAE) impeded the characterization of their spatial gene expression programs. Here, we combined RNA sequencing of laser capture microdissected tissues with single-molecule transcript imaging to obtain a spatial gene expression map of the ILF and its associated FAE in the mouse small intestine. We identified zonated expression programs in both follicles and FAEs, with a decrease in enterocyte antimicrobial and absorption programs and a partial induction of expression programs normally observed at the villus tip. We further identified Lepr+ subepithelial telocytes at the FAE top, which are distinct from villus tip Lgr5+ telocytes. Our analysis exposes the epithelial and mesenchymal cell states associated with ILFs.

MMP-12 siRNA improves the homeostasis of the small intestine and metabolic dysfunction in high-fat diet feeding-induced obese mice

The changes of small intestinal homeostasis have been recognized to contribute essentially to the obese development. However, the core small intestinal regulator which mediates over-nutrient impacts on the homeostasis of the small intestines remains elusive. Here, we identify the MMP-12 as such a responsive factor in mouse small intestines. Taking advantages of the nano delivery system, we demonstrate that small intestine-specific MMP-12 knockdown alleviates high-fat diet feeding-induced metabolic disorders and improves intestinal homeostasis in mice, including a significant decrease in lipid transportation, bile acid reabsorption, and inflammation. In parallel, the small intestinal integrity is recovered and the gut microbiota composition is reversed towards that under normal diet feeding. Mechanistically, MMP-12, differing from its traditional elastolytic function, acts as a transcriptional factor to activate Fabp4 transcription through epigenetic modification. In translational medicine, clinical applications of our nanosystem and therapeutic interventions targeting MMP-12 will benefit patients with obesity and associated diseases.

Organoid vs In Vivo Mouse Model: Which is Better Research Tool to Understand the Biologic Mechanisms of Intestinal Epithelium?

Organoid vs In Vivo Mouse Model: Which is Better Research Tool to Understand the Biologic Mechanisms of Intestinal Epithelium?

A Novel Identified Peptide Hormone "Metabolitin" Attenuates Lipid Absorption in the Small Intestine of Diabetic Mice with Nonalcoholic Fatty Liver Disease by Regulating Neurotensin and AMPK Signaling Pathway.

Aim The purpose of this study was to explore the effect of a novel identified peptide hormone “metabolitin” on lipid absorption in the small intestine of mice with type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) and potential mechanisms. Methods T2DM was induced in mice by 4–6 weeks of high-fat diets followed by intraperitoneal injection of 35 mg/kg STZ. NAFLD was induced in diabetic mice by a month of high-fat diets. Oral administration of 4 pmol/g or 12 pmol/g metabolitin every two days was performed during one-month high-fat diets. Triglyceride (TG) and total cholesterol (TC) detection and Oil Red O staining were performed to evaluate lipid absorption. The neurotensin (NT) levels in the intestinal tissues and serum were determined by ELISA. Lipogenesis- and lipolysis-related proteins, AMP-activated protein kinase (AMPK), and p-AMPK were examined by Western blot analysis. Results It was found that glucose tolerance test (GTT), insulin tolerance test (ITT), TG, and TC indicated lower levels in the serum of NAFLD/T2DM mice receiving 4 pmol/g and 12 pmol/g metabolitin compared to the mice receiving normal saline (P < 0.05). No significant difference was noted in the TC level of the feces among mice with different diets (P > 0.05), but compared to NAFLD/T2DM mice with normal saline, the mice administrated with 4 pmol/g and 12 pmol/g metabolitin revealed much higher TG levels in the feces (P < 0.05). The results of Oil Red O staining revealed that the intestinal epithelial cells of NAFLD/T2DM mice receiving 12 pmol/g metabolitin indicated resistance to lipid absorption and the area of staining was smaller than that of NAFLD/T2DM mice with normal saline (P < 0.05). The NAFLD/T2DM mice receiving 4 pmol/g and 12 pmol/g metabolitin showed a higher extent of p-AMPK concomitant with lower levels of NT in the serum and small intestine than the mice with normal saline (P < 0.05). Western blot analysis also suggested that NAFLD/T2DM mice receiving 4 pmol/g and 12 pmol/g metabolitin revealed lower expressions in fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase-1 (SCD-1), and sterol regulatory element-binding transcription factor-1 (SREBP1) proteins and higher expressions in carnitine palmitoyltransferase 1 (CPT1), peroxisome proliferator-activated receptor alpha (PPARα), and fatty acid translocase (CD36) proteins than NAFLD/T2DM mice with normal saline (P < 0.05). Conclusion According to the data we observed, oral administration of metabolitin could attenuate lipid absorption in the small intestine of NAFLD/T2DM mice, which may be a novel therapeutic approach for NAFLD/T2DM.

In Vivo Studies Should Take Priority When Defining Mechanisms of Intestinal Crypt Morphogenesis.

In Vivo Studies Should Take Priority When Defining Mechanisms of Intestinal Crypt Morphogenesis.

Rotavirus susceptibility of antibiotic-treated mice ascribed to diminished expression of interleukin-22.

The commensal microbiota regulates susceptibility to enteric pathogens by fine-tuning mucosal innate immune responses, but how susceptibility to enteric viruses is shaped by the microbiota remains incompletely understood. Past reports have indicated that commensal bacteria may either promote or repress rotavirus replication in the small intestine of mice. We now report that rotavirus replicated more efficiently in the intestines of germ-free and antibiotic-treated mice compared to animals with an unmodified microbiota. Antibiotic treatment also facilitated rotavirus replication in type I and type III interferon (IFN) receptor-deficient mice, revealing IFN-independent proviral effects. Expression of interleukin-22 (IL-22) was strongly diminished in the intestine of antibiotic-treated mice. Treatment with exogenous IL-22 blocked rotavirus replication in microbiota-depleted wild-type and Stat1-/- mice, demonstrating that the antiviral effect of IL-22 in animals with altered microbiome is not dependent on IFN signaling. In antibiotic-treated animals, IL-22-induced a specific set of genes including Fut2, encoding fucosyl-transferase 2 that participates in the biosynthesis of fucosylated glycans which can mediate rotavirus binding. Interestingly, IL-22 also blocked rotavirus replication in antibiotic-treated Fut2-/- mice. Furthermore, IL-22 inhibited rotavirus replication in antibiotic-treated mice lacking key molecules of the necroptosis or pyroptosis pathways of programmed cell death. Taken together, our results demonstrate that IL-22 determines rotavirus susceptibility of antibiotic-treated mice, yet the IL-22-induced effector molecules conferring rotavirus resistance remain elusive.

L-Cell Expression of Melanocortin-4-Receptor Is Marginal in Most of the Small Intestine in Mice and Humans and Direct Stimulation of Small Intestinal Melanocortin-4-Receptors in Mice and Rats Does Not Affect GLP-1 Secretion.

The molecular sensors underlying nutrient-stimulated GLP-1 secretion are currently being investigated. Peripheral administration of melanocortin-4 receptor (MC4R) agonists have been reported to increase GLP-1 plasma concentrations in mice and humans but it is unknown whether this effect results from a direct effect on the GLP-1 secreting L-cells in the intestine, from other effects in the intestine or from extra-intestinal effects. We investigated L-cell expression of MC4R in mouse and human L-cells by reanalyzing publicly available RNA sequencing databases (mouse and human) and by RT-qPCR (mouse), and assessed whether administration of MC4R agonists to a physiologically relevant gut model, isolated perfused mouse and rat small intestine, would stimulate GLP-1 secretion or potentiate glucose-stimulated secretion. L-cell MC4R expression was low in mouse duodenum and hardly detectable in the ileum and MC4R expression was hardly detectable in human L-cells. In isolated perfused mouse and rat intestine, neither intra-luminal nor intra-arterial administration of NDP-alpha-MSH, a potent MC4R agonist, had any effect on GLP-1 secretion (P ≥0.98, n = 5–6) from the upper or lower-half of the small intestine in mice or in the lower half in rats. Furthermore, HS014—an often used MC4R antagonist, which we found to be a partial agonist—did not affect the glucose-induced GLP-1 response in the rat, P = 0.62, n = 6). Studies on transfected COS7-cells confirmed bioactivity of the used compounds and that concentrations employed were well within in the effective range. Our combined data therefore suggest that MC4R-activated GLP-1 secretion in rodents either exclusively occurs in the colon or involves extra-intestinal signaling.