Hypoxia-inducible factor 1α inhibits heat stress-induced pig intestinal epithelial cell apoptosis through eif2α/ATF4/CHOP signaling

Unstoppable global warming and increased frequency of extreme heat leads to human and animals easier to suffer from heat stress (HS), with gastrointestinal abnormalities as one of the initial clinical symptoms. HS induces intestinal mucosal damage owing to intestinal hypoxia and hyperthermia. Hypoxia-inducible factor 1α (HIF-1α) activates numerous genes to mediate cell hypoxic responses; however, its role in HS-treated intestinal mucosa is unknown. This work aimed to explore HIF-1α function and regulatory mechanisms in HS-treated pig intestines. We assigned 10 pigs to control and moderate HS groups. Physical signs, stress, and antioxidant levels were detected, and the intestines were harvested after 72 h of HS treatment to study histological changes and HIF-1α, heat shock protein 90 (HSP90), and prolyl-4-hydroxylase 2 (PHD-2) expression. In addition, porcine intestinal columnar epithelial cells (IPEC-J2) underwent HS treatment (42 °C, 5 % O2) to further explore the functions and regulatory mechanism of HIF-1α. The results of histological examination revealed HS caused intestinal villi damage and increased apoptotic epithelial cell; the expression of HIF-1α and HSP90 increased while PHD-2 showed and opposite trend. Transcriptome sequencing analysis revealed that HS activated HIF-1 signaling. To further explore the role of HIF-1α on HS induced IPEC-J2 apoptosis, the HIF-1α was interfered and overexpression respectively, and the result confirmed that HIF-1α could inhibited cell apoptosis under HS. Furthermore, HS-induced apoptosis depends on eukaryotic initiation factor 2 alpha (eif2α)/activating transcription factor 4 (ATF4)/CCAAT-enhancer-binding protein homologous protein (CHOP) pathway, and HIF-1α can inhibit this pathway to alleviate IPEC-J2 cell apoptosis. In conclusion, this study suggests that HS can promote intestinal epithelial cell apoptosis and cause pig intestinal mucosal barrier damage; the HIF-1α can alleviate cell apoptosis by inhibiting eif2α/ATF4/CHOP signaling. These results indicate that HIF-1α plays a protective role in HS, and offers a potential target for HS prevention and mitigation.

Gut-liver axis calibrates intestinal stem cell fitness

The gut and liver are recognized to mutually communicate through the biliary tract, portal vein, and systemic circulation. However, it remains unclear how this gut-liver axis regulates intestinal physiology. Through hepatectomy and transcriptomic and proteomic profiling, we identified pigment epithelium-derived factor (PEDF), a liver-derived soluble Wnt inhibitor, which restrains intestinal stem cell (ISC) hyperproliferation to maintain gut homeostasis by suppressing the Wnt/β-catenin signaling pathway. Furthermore, we found that microbial danger signals resulting from intestinal inflammation can be sensed by the liver, leading to the repression of PEDF production through peroxisome proliferator-activated receptor-α (PPARα). This repression liberates ISC proliferation to accelerate tissue repair in the gut. Additionally, treating mice with fenofibrate, a clinical PPARα agonist used for hypolipidemia, enhances colitis susceptibility due to PEDF activity. Therefore, we have identified a distinct role for PEDF in calibrating ISC expansion for intestinal homeostasis through reciprocal interactions between the gut and liver.

Intestinal FFA2 promotes obesity by altering food intake in Western diet-fed mice

Short-chain fatty acids (SCFAs) are key nutrients that play a diverse set of roles in physiological function, including regulating metabolic homeostasis. Generated through the fermentation of dietary fibers in the distal colon by the gut microbiome, SCFAs and their effects are partially mediated by their cognate receptors, including free fatty acid receptor 2 (FFA2). FFA2 is highly expressed in the intestinal epithelial cells, where its putative functions are controversial, with numerous in vivo studies relying on global knockout mouse models to characterize intestine-specific roles of the receptor. Here, we used the Villin-Cre mouse line to generate a novel, intestine-specific knockout mouse model for FFA2 (Vil-FFA2) to investigate receptor function within the intestine. Because dietary changes are known to affect the composition of the gut microbiome, and can thereby alter SCFA production, we performed an obesogenic challenge on male Vil-FFA2 mice and their littermate controls (FFA2-floxed, FFA2fl/fl) to identify physiological changes on a high-fat, high-sugar 'Western diet' (WD) compared to a low-fat control diet (CD). We found that the WD-fed Vil-FFA2 mice were transiently protected from the obesogenic effects of the WD and had lower fat mass and improved glucose homeostasis compared to the WD-fed FFA2fl/fl control group during the first half of the study. Additionally, major differences in respiratory exchange ratio and energy expenditure were observed in the WD-fed Vil-FFA2 mice, and food intake was found to be significantly reduced at multiple points in the study. Taken together, this study uncovers a novel role of intestinal FFA2 in mediating the development of obesity.

HilE represses the activity of the Salmonella virulence regulator HilD via a mechanism distinct from that of intestinal long-chain fatty acids

The expression of virulence factors essential for the invasion of host cells by Salmonella enterica is tightly controlled by a network of transcription regulators. The AraC/XylS transcription factor HilD is the main integration point of environmental signals into this regulatory network, with many factors affecting HilD activity. Long-chain fatty acids, which are highly abundant throughout the host intestine, directly bind to and repress HilD, acting as environmental cues to coordinate virulence gene expression. The regulatory protein HilE also negatively regulates HilD activity, through a protein-protein interaction. Both of these regulators inhibit HilD dimerization, preventing HilD from binding to target DNA. We investigated the structural basis of these mechanisms of HilD repression. Long-chain fatty acids bind to a conserved pocket in HilD, in a comparable manner to that reported for other AraC/XylS regulators, whereas HilE forms a stable heterodimer with HilD by binding to the HilD dimerization interface. Our results highlight two distinct, mutually exclusive mechanisms by which HilD activity is repressed, which could be exploited for the development of new antivirulence leads.

Neurofibromin 1 mediates sleep depth in Drosophila

Neural regulation of sleep and metabolic homeostasis are critical in many aspects of human health. Despite extensive epidemiological evidence linking sleep dysregulation with obesity, diabetes, and metabolic syndrome, little is known about the neural and molecular basis for the integration of sleep and metabolic function. The RAS GTPase-activating gene Neurofibromin (Nf1) has been implicated in the regulation of sleep and metabolic rate, raising the possibility that it serves to integrate these processes, but the effects on sleep consolidation and physiology remain poorly understood. A key hallmark of sleep depth in mammals and flies is a reduction in metabolic rate during sleep. Here, we examine multiple measures of sleep quality to determine the effects of Nf1 on sleep-dependent changes in arousal threshold and metabolic rate. Flies lacking Nf1 fail to suppress metabolic rate during sleep, raising the possibility that loss of Nf1 prevents flies from integrating sleep and metabolic state. Sleep of Nf1 mutant flies is fragmented with a reduced arousal threshold in Nf1 mutants, suggesting Nf1 flies fail to enter deep sleep. The effects of Nf1 on sleep can be localized to a subset of neurons expressing the GABAA receptor Rdl. Sleep loss has been associated with changes in gut homeostasis in flies and mammals. Selective knockdown of Nf1 in Rdl-expressing neurons within the nervous system increases gut permeability and reactive oxygen species (ROS) in the gut, raising the possibility that loss of sleep quality contributes to gut dysregulation. Together, these findings suggest Nf1 acts in GABA-sensitive neurons to modulate sleep depth in Drosophila.

Autoimmune amelogenesis imperfecta in patients with APS-1 and coeliac disease

Ameloblasts are specialized epithelial cells in the jaw that have an indispensable role in tooth enamel formation-amelogenesis1. Amelogenesis depends on multiple ameloblast-derived proteins that function as a scaffold for hydroxyapatite crystals. The loss of function of ameloblast-derived proteins results in a group of rare congenital disorders called amelogenesis imperfecta2. Defects in enamel formation are also found in patients with autoimmune polyglandular syndrome type-1 (APS-1), caused by AIRE deficiency3,4, and in patients diagnosed with coeliac disease5-7. However, the underlying mechanisms remain unclear. Here we show that the vast majority of patients with APS-1 and coeliac disease develop autoantibodies (mostly of the IgA isotype) against ameloblast-specific proteins, the expression of which is induced by AIRE in the thymus. This in turn results in a breakdown of central tolerance, and subsequent generation of corresponding autoantibodies that interfere with enamel formation. However, in coeliac disease, the generation of such autoantibodies seems to be driven by a breakdown of peripheral tolerance to intestinal antigens that are also expressed in enamel tissue. Both conditions are examples of a previously unidentified type of IgA-dependent autoimmune disorder that we collectively name autoimmune amelogenesis imperfecta.

High intestinal isoleucine is a potential risk factor for food allergy by regulating the mTOR/AKT pathway in dendritic cells

Food allergy is a global food safety problem with a growing prevalence. People in industrial regions are more susceptible to allergy, but the mechanisms behind this are not fully understood. In this study, the probiotic Lactobacillus casei Zhang (LcZ) was administered to allergic individuals and the impact on allergy-related factors were determined. LcZ alleviated allergenic responses, and there was a significant correlation between the intestinal isoleucine content and IgE concentration. Metagenomics results suggest that the metabolism of the gut microbiota is a source of isoleucine. In a mouse model of food allergy, a high isoleucine diet exacerbated allergic responses and increased the activity of allergenic dendritic cell. In a dendritic cell model, a protein array revealed that the mTOR/AKT pathway mediated the function of isoleucine, and molecular docking suggested that Sestrin2 could be the potential receptor. Overall, this study revealed the role of isoleucine in promoting food allergy, elucidated the underlying mechanisms, and suggested that a high intake of isoleucine could be a potential risk factor for food allergy.

Examination of the mechanism of Piezo ion channel in 5-HT synthesis in the enterochromaffin cell and its association with gut motility

In the gastrointestinal tract, serotonin (5-hydroxytryptamine, 5-HT) is an important monoamine that regulates intestinal dynamics. QGP-1 cells are human-derived enterochromaffin cells that secrete 5-HT and functionally express Piezo ion channels associated with cellular mechanosensation. Piezo ion channels can be blocked by Grammostola spatulata mechanotoxin 4 (GsMTx4), a spider venom peptide that inhibits cationic mechanosensitive channels. The primary aim of this study was to explore the effects of GsMTx4 on 5-HT secretion in QGP-1 cells in vitro. We investigated the transcript and protein levels of the Piezo1/2 ion channel, tryptophan hydroxylase 1 (TPH1), and mitogen-activated protein kinase signaling pathways. In addition, we observed that GsMTx4 affected mouse intestinal motility in vivo. Furthermore, GsMTx4 blocked the response of QGP-1 cells to ultrasound, a mechanical stimulus.The prolonged presence of GsMTx4 increased the 5-HT levels in the QGP-1 cell culture system, whereas Piezo1/2 expression decreased, and TPH1 expression increased. This effect was accompanied by the increased phosphorylation of the p38 protein. GsMTx4 increased the entire intestinal passage time of carmine without altering intestinal inflammation. Taken together, inhibition of Piezo1/2 can mediate an increase in 5-HT, which is associated with TPH1, a key enzyme for 5-HT synthesis. It is also accompanied by the activation of the p38 signaling pathway. Inhibitors of Piezo1/2 can modulate 5-HT secretion and influence intestinal motility.

Clostridioides difficile ferrosome organelles combat nutritional immunity

Iron is indispensable for almost all forms of life but toxic at elevated levels1-4. To survive within their hosts, bacterial pathogens have evolved iron uptake, storage and detoxification strategies to maintain iron homeostasis1,5,6. Recent studies showed that three Gram-negative environmental anaerobes produce iron-containing ferrosome granules7,8. However, it remains unclear whether ferrosomes are generated exclusively by Gram-negative bacteria. The Gram-positive bacterium Clostridioides difficile is the leading cause of nosocomial and antibiotic-associated infections in the USA9. Here we report that C. difficile undergoes an intracellular iron biomineralization process and stores iron in membrane-bound ferrosome organelles containing non-crystalline iron phosphate biominerals. We found that a membrane protein (FezA) and a P1B6-ATPase transporter (FezB), repressed by both iron and the ferric uptake regulator Fur, are required for ferrosome formation and play an important role in iron homeostasis during transition from iron deficiency to excess. Additionally, ferrosomes are often localized adjacent to cellular membranes as shown by cryo-electron tomography. Furthermore, using two mouse models of C. difficile infection, we demonstrated that the ferrosome system is activated in the inflamed gut to combat calprotectin-mediated iron sequestration and is important for bacterial colonization and survival during C. difficile infection.

Cholinergic neurons trigger epithelial Ca2+ currents to heal the gut

A fundamental and unresolved question in regenerative biology is how tissues return to homeostasis after injury. Answering this question is essential for understanding the aetiology of chronic disorders such as inflammatory bowel diseases and cancer1. We used the Drosophila midgut2 to investigate this and discovered that during regeneration a subpopulation of cholinergic3 neurons triggers Ca2+ currents among intestinal epithelial cells, the enterocytes, to promote return to homeostasis. We found that downregulation of the conserved cholinergic enzyme acetylcholinesterase4 in the gut epithelium enables acetylcholine from specific Egr5 (TNF in mammals)-sensing cholinergic neurons to activate nicotinic receptors in innervated enterocytes. This activation triggers high Ca2+, which spreads in the epithelium through Innexin2-Innexin7 gap junctions6, promoting enterocyte maturation followed by reduction of proliferation and inflammation. Disrupting this process causes chronic injury consisting of ion imbalance, Yki (YAP in humans) activation7, cell death and increase of inflammatory cytokines reminiscent of inflammatory bowel diseases8. Altogether, the conserved cholinergic pathway facilitates epithelial Ca2+ currents that heal the intestinal epithelium. Our findings demonstrate nerve- and bioelectric9-dependent intestinal regeneration and advance our current understanding of how a tissue returns to homeostasis after injury.

Phase separation of BuGZ regulates gut regeneration and aging through interaction with m6A regulators

Exploring the role of phase separation in intracellular compartment formation is an active area of research. However, the associations of phase separation with intestinal stem cell (ISC)-dependent regeneration and aging remain unclear. Here, we demonstrate that BuGZ, a coacervating mitotic effector, shows age- and injury-associated condensation in Drosophila ISC nuclei during interphase. BuGZ condensation promotes ISC proliferation, affecting Drosophila gut repair and longevity. Moreover, m6A reader YT521-B acts as the transcriptional and functional downstream of BuGZ. The binding of YT521-B promotor or m6A writer Ime4/ Mettl14 to BuGZ controls its coacervation, indicating that the promotor may accelerate the phase transition of its binding transcription factor. Hence, we propose that phase separation and m6A regulators may be critical for ameliorating ISC-dependent gut regeneration and aging and requires further study.

Uniquely preserved gut contents illuminate trilobite palaeophysiology

Trilobites are among the most iconic of fossils and formed a prominent component of marine ecosystems during most of their 270-million-year-long history from the early Cambrian period to the end Permian period1. More than 20,000 species have been described to date, with presumed lifestyles ranging from infaunal burrowing to a planktonic life in the water column2. Inferred trophic roles range from detritivores to predators, but all are based on indirect evidence such as body and gut morphology, modes of preservation and attributed feeding traces; no trilobite specimen with internal gut contents has been described3,4. Here we present the complete and fully itemized gut contents of an Ordovician trilobite, Bohemolichas incola, preserved three-dimensionally in a siliceous nodule and visualized by synchrotron microtomography. The tightly packed, almost continuous gut fill comprises partly fragmented calcareous shells indicating high feeding intensity. The lack of dissolution of the shells implies a neutral or alkaline environment along the entire length of the intestine supporting digestive enzymes comparable to those in modern crustaceans or chelicerates. Scavengers burrowing into the trilobite carcase targeted soft tissues below the glabella but avoided the gut, suggesting noxious conditions and possibly ongoing enzymatic activity.

IFNγ-Stat1 axis drives aging-associated loss of intestinal tissue homeostasis and regeneration

The influence of aging on intestinal stem cells and their niche can explain underlying causes for perturbation in their function observed during aging. Molecular mechanisms for such a decrease in the functionality of intestinal stem cells during aging remain largely undetermined. Using transcriptome-wide approaches, our study demonstrates that aging intestinal stem cells strongly upregulate antigen presenting pathway genes and over-express secretory lineage marker genes resulting in lineage skewed differentiation into the secretory lineage and strong upregulation of MHC class II antigens in the aged intestinal epithelium. Mechanistically, we identified an increase in proinflammatory cells in the lamina propria as the main source of elevated interferon gamma (IFNγ) in the aged intestine, that leads to the induction of Stat1 activity in intestinal stem cells thus priming the aberrant differentiation and elevated antigen presentation in epithelial cells. Of note, systemic inhibition of IFNγ-signaling completely reverses these aging phenotypes and reinstalls regenerative capacity of the aged intestinal epithelium.

Endothelial AHR activity prevents lung barrier disruption in viral infection

Disruption of the lung endothelial-epithelial cell barrier following respiratory virus infection causes cell and fluid accumulation in the air spaces and compromises vital gas exchange function1. Endothelial dysfunction can exacerbate tissue damage2,3, yet it is unclear whether the lung endothelium promotes host resistance against viral pathogens. Here we show that the environmental sensor aryl hydrocarbon receptor (AHR) is highly active in lung endothelial cells and protects against influenza-induced lung vascular leakage. Loss of AHR in endothelia exacerbates lung damage and promotes the infiltration of red blood cells and leukocytes into alveolar air spaces. Moreover, barrier protection is compromised and host susceptibility to secondary bacterial infections is increased when endothelial AHR is missing. AHR engages tissue-protective transcriptional networks in endothelia, including the vasoactive apelin-APJ peptide system4, to prevent a dysplastic and apoptotic response in airway epithelial cells. Finally, we show that protective AHR signalling in lung endothelial cells is dampened by the infection itself. Maintenance of protective AHR function requires a diet enriched in naturally occurring AHR ligands, which activate disease tolerance pathways in lung endothelia to prevent tissue damage. Our findings demonstrate the importance of endothelial function in lung barrier immunity. We identify a gut-lung axis that affects lung damage following encounters with viral pathogens, linking dietary composition and intake to host fitness and inter-individual variations in disease outcome.

Molecular characterization and function of JAK/STAT pathway in IPEC-J2 cells during Clostridium perfringens beta2 toxin stimulation

Intestinal infection with C. perfringens is responsible for outbreaks of diarrhea in piglets. Janus kinase / signal transducer and activator of transcription (JAK/STAT) is a vital signaling pathway that regulates cellular activity and inflammatory response, closely correlated with multiple diseases development and advances. Currently, the potential effect of JAK/STAT on C. perfringens beta2 (CPB2) treatment on porcine intestinal epithelial (IPEC-J2) cells has not been explored. The expression of JAK/STAT genes or proteins in IPEC-J2 cells induced by CPB2 were observed by qRT-PCR and Western blot, and further used WP1066 to explore the effect of JAK2/STAT3 on mechanism employed by CPB2 on apoptosis, cytotoxicity, oxidative stress and inflammatory cytokines of IPEC-J2 cells. JAK2, JAK3, STAT1, STAT3, STAT5A and STAT6 were highly expressed in CPB2-induced IPEC-J2 cells, among which STAT3 had the highest expression. Moreover, apoptosis, cytotoxicity and oxidative stress were attenuated via blocking the activation of JAK2/STAT3 by using WP1066 in CPB2-treated IPEC-J2 cells. Furthermore, WP1066 significantly suppressed the secretion of interleukin (IL)-6, IL-1β and TNF-α induced by CPB2 in IPEC-J2 cells.Our findings provide some insights into the functional roles of JAK2/STAT3 in piglets against to C. perfringens infection.

The gut microbiota reprograms intestinal lipid metabolism through long noncoding RNA Snhg9

The intestinal microbiota regulates mammalian lipid absorption, metabolism, and storage. We report that the microbiota reprograms intestinal lipid metabolism in mice by repressing the expression of long noncoding RNA (lncRNA) Snhg9 (small nucleolar RNA host gene 9) in small intestinal epithelial cells. Snhg9 suppressed the activity of peroxisome proliferator-activated receptor γ (PPARγ)-a central regulator of lipid metabolism-by dissociating the PPARγ inhibitor sirtuin 1 from cell cycle and apoptosis protein 2 (CCAR2). Forced expression of Snhg9 in the intestinal epithelium of conventional mice impaired lipid absorption, reduced body fat, and protected against diet-induced obesity. The microbiota repressed Snhg9 expression through an immune relay encompassing myeloid cells and group 3 innate lymphoid cells. Our findings thus identify an unanticipated role for a lncRNA in microbial control of host metabolism.

P2X7 Receptor Regulates Collagen Expression in Human Intestinal Fibroblasts: Relevance in Intestinal Fibrosis

Intestinal fibrosis is a common complication that affects more than 50% of Crohn´s Disease (CD) patients. There is no pharmacological treatment against this complication, with surgery being the only option. Due to the unknown role of P2X7 in intestinal fibrosis, we aim to analyze the relevance of this receptor in CD complications. Surgical resections from CD and non-Inflammatory Bowel Disease (IBD) patients were obtained. Intestinal fibrosis was induced with two different murine models: heterotopic transplant model and chronic-DSS colitis in wild-type and P2X7-/- mice. Human small intestine fibroblasts (HSIFs) were transfected with an siRNA against P2X7 and treated with TGF-β. A gene and protein expression of P2X7 receptor was significantly increased in CD compared to non-IBD patients. The lack of P2X7 in mice provoked an enhanced collagen deposition and increased expression of several profibrotic markers in both murine models of intestinal fibrosis. Furthermore, P2X7-/- mice exhibited a higher expression of proinflammatory cytokines and a lower expression of M2 macrophage markers. Moreover, the transient silencing of the P2X7 receptor in HSIFs significantly induced the expression of Col1a1 and potentiated the expression of Col4 and Col5a1 after TGF-β treatment. P2X7 regulates collagen expression in human intestinal fibroblasts, while the lack of this receptor aggravates intestinal fibrosis.

Protective effect of plantaricin bio-LP1 bacteriocin on multidrug-resistance Escherichia Coli infection by alleviate the inflammation and modulate of gut-microbiota in BALB/c mice model

The rapid spread of multidrug-resistant pathogens with the low efficacy of common antibiotics for humans and animals in its clinical therapeutics are a global health concern. Therefore, there is a need to develop new treatment strategies to control them clinically. The study aimed to evaluate the effects of Plantaricin Bio-LP1 bacteriocin produced from Lactiplantibacillus plantarum NWAFU-BIO-BS29 to alleviate the inflammation caused by multidrug-resistance Escherichia Coli (MDR-E. coli) infection in BALB/c mice-model. The focus was given on aspects linked to the mechanism of the immune response. Results indicated that Bio-LP1 had highly promising effects on partially ameliorating MDR-E. coli infection by reducing the inflammatory response through inhibiting the overexpression of proinflammatory-cytokines such as secretion of tumor necrosis factor (TNF-α) and interleukin (IL-6 and IL-β) and strongly regulated theTLR4 signaling-pathway. Additionally, avoided the villous destruct, colon length shortening, loss of intestinal barrier integrity, and increased disease activity index. Furthermore, significantly increased the relative abundance of beneficial-intestinal-bacteria including Ligilactobacillus, Enterorhabdus, Pervotellaceae, etc. Finally, improved the intestinal mucosal barrier to alleviate the pathological damages and promote the production of short-chain fatty acids (SCFAs) a source of energy for the proliferation. In conclusion, plantaricin Bio-LP1 bacteriocin can be considered a safe alternative to antibiotics against MDR-E. coli-induced intestinal inflammation.

A stromal lineage maintains crypt structure and villus homeostasis in the intestinal stem cell niche

BACKGROUND

The nutrient-absorbing villi of small intestines are renewed and repaired by intestinal stem cells (ISCs), which reside in a well-organized crypt structure. Genetic studies have shown that Wnt molecules secreted by telocytes, Gli1+ stromal cells, and epithelial cells are required for ISC proliferation and villus homeostasis. Intestinal stromal cells are heterogeneous and single-cell profiling has divided them into telocytes/subepithelial myofibroblasts, myocytes, pericytes, trophocytes, and Pdgfralow stromal cells. Yet, the niche function of these stromal populations remains incompletely understood.

RESULTS

We show here that a Twist2 stromal lineage, which constitutes the Pdgfralow stromal cell and trophocyte subpopulations, maintains the crypt structure to provide an inflammation-restricting niche for regenerating ISCs. Ablating Twist2 lineage cells or deletion of one Wntless allele in these cells disturbs the crypt structure and impairs villus homeostasis. Upon radiation, Wntless haplo-deficiency caused decreased production of anti-microbial peptides and increased inflammation, leading to defective ISC proliferation and crypt regeneration, which were partially rescued by eradication of commensal bacteria. In addition, we show that Wnts secreted by Acta2+ subpopulations also play a role in crypt regeneration but not homeostasis.

CONCLUSIONS

These findings suggest that ISCs may require different niches for villus homeostasis and regeneration and that the Twist2 lineage cells may help to maintain a microbe-restricted environment to allow ISC-mediated crypt regeneration.

Cruciferous vegetable-derived indole-3-carbinol prevents coronavirus cell egression mechanisms in tracheal and intestinal 3D in vitro models

The potential antiviral effects of indole-3-carbinol (I3C), a phytochemical found in Cruciferous vegetables, were investigated. Fibroblasts and epithelial cells were co-cultured on Alvetex® scaffolds, to obtain ad hoc 3D in vitro platforms able to mimic the trachea and intestinal mucosae, which represent the primary structures involved in the coronavirus pathogenesis. The two barriers generated in vitro were treated with various concentrations of I3C for different incubation periods. A protective effect of I3C on both intestinal and trachea models was demonstrated. A significant reduction in the transcription of the two main genes belonging to the Homologous to E6AP C-terminus (HECT)-E3 ligase family members, namely NEDD4 E3 Ubiquitin Protein Ligase (NEDD4) and WW Domain Containing E3 Ubiquitin Protein Ligase 1 (WWP1), which promote virus matrix protein ubiquitination and inhibit viral egression, were detected. These findings indicate I3C potential effect in preventing coronavirus cell egression processes that inhibit viral production. Although further studies are needed to clarify the molecular mechanisms whereby HECT family members control virus life cycle, this work paves the way to the possible therapeutic use of new natural compounds that may reduce the clinical severity of future pandemics.

p57Kip2 acts as a transcriptional corepressor to regulate intestinal stem cell fate and proliferation

p57Kip2 is a cyclin/CDK inhibitor and a negative regulator of cell proliferation. Here, we report that p57 regulates intestinal stem cell (ISC) fate and proliferation in a CDK-independent manner during intestinal development. In the absence of p57, intestinal crypts exhibit an increased proliferation and an amplification of transit-amplifying cells and of Hopx+ ISCs, which are no longer quiescent, while Lgr5+ ISCs are unaffected. RNA sequencing (RNA-seq) analyses of Hopx+ ISCs show major gene expression changes in the absence of p57. We found that p57 binds to and inhibits the activity of Ascl2, a transcription factor critical for ISC specification and maintenance, by participating in the recruitment of a corepressor complex to Ascl2 target gene promoters. Thus, our data suggest that, during intestinal development, p57 plays a key role in maintaining Hopx+ ISC quiescence and repressing the ISC phenotype outside of the crypt bottom by inhibiting the transcription factor Ascl2 in a CDK-independent manner.

Trans-Golgi protein TVP23B regulates host-microbe interactions via Paneth cell homeostasis and Goblet cell glycosylation

A key feature in intestinal immunity is the dynamic intestinal barrier, which separates the host from resident and pathogenic microbiota through a mucus gel impregnated with antimicrobial peptides. Using a forward genetic screen, we have found a mutation in Tvp23b, which conferred susceptibility to chemically induced and infectious colitis. Trans-Golgi apparatus membrane protein TVP23 homolog B (TVP23B) is a transmembrane protein conserved from yeast to humans. We found that TVP23B controls the homeostasis of Paneth cells and function of goblet cells, leading to a decrease in antimicrobial peptides and more penetrable mucus layer. TVP23B binds with another Golgi protein, YIPF6, which is similarly critical for intestinal homeostasis. The Golgi proteomes of YIPF6 and TVP23B-deficient colonocytes have a common deficiency of several critical glycosylation enzymes. TVP23B is necessary for the formation of the sterile mucin layer of the intestine and its absence disturbs the balance of host and microbe in vivo.

Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500-1700 nm) lanthanide nanomaterials NaGdF4:Yb3+,Er3+@NaGdF4,Nd3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

Profiling the human intestinal environment under physiological conditions

The spatiotemporal structure of the human microbiome1,2, proteome3 and metabolome4,5 reflects and determines regional intestinal physiology and may have implications for disease6. Yet, little is known about the distribution of microorganisms, their environment and their biochemical activity in the gut because of reliance on stool samples and limited access to only some regions of the gut using endoscopy in fasting or sedated individuals7. To address these deficiencies, we developed an ingestible device that collects samples from multiple regions of the human intestinal tract during normal digestion. Collection of 240 intestinal samples from 15 healthy individuals using the device and subsequent multi-omics analyses identified significant differences between bacteria, phages, host proteins and metabolites in the intestines versus stool. Certain microbial taxa were differentially enriched and prophage induction was more prevalent in the intestines than in stool. The host proteome and bile acid profiles varied along the intestines and were highly distinct from those of stool. Correlations between gradients in bile acid concentrations and microbial abundance predicted species that altered the bile acid pool through deconjugation. Furthermore, microbially conjugated bile acid concentrations exhibited amino acid-dependent trends that were not apparent in stool. Overall, non-invasive, longitudinal profiling of microorganisms, proteins and bile acids along the intestinal tract under physiological conditions can help elucidate the roles of the gut microbiome and metabolome in human physiology and disease.

A gut-secreted peptide suppresses arousability from sleep

Suppressing sensory arousal is critical for sleep, with deeper sleep requiring stronger sensory suppression. The mechanisms that enable sleeping animals to largely ignore their surroundings are not well understood. We show that the responsiveness of sleeping flies and mice to mechanical vibrations is better suppressed when the diet is protein rich. In flies, we describe a signaling pathway through which information about ingested proteins is conveyed from the gut to the brain to help suppress arousability. Higher protein concentration in the gut leads to increased activity of enteroendocrine cells that release the peptide CCHa1. CCHa1 signals to a small group of dopamine neurons in the brain to modulate their activity; the dopaminergic activity regulates the behavioral responsiveness of animals to vibrations. The CCHa1 pathway and dietary proteins do not influence responsiveness to all sensory inputs, showing that during sleep, different information streams can be gated through independent mechanisms.

Comparative Transcriptomic Analysis Reveals the Functionally Segmented Intestine in Tunicate Ascidian

The vertebrate intestinal system consists of separate segments that remarkably differ in morphology and function. However, the origin of intestinal segmentation remains unclear. In this study, we investigated the segmentation of the intestine in a tunicate ascidian species, Ciona savignyi, by performing RNA sequencing. The gene expression profiles showed that the whole intestine was separated into three segments. Digestion, ion transport and signal transduction, and immune-related pathway genes were enriched in the proximal, middle, and distal parts of the intestine, respectively, implying that digestion, absorption, and immune function appear to be regional specializations in the ascidian intestine. We further performed a multi-species comparison analysis and found that the Ciona intestine showed a similar gene expression pattern to vertebrates, indicating tunicates and vertebrates might share the conserved intestinal functions. Intriguingly, vertebrate pancreatic homologous genes were expressed in the digestive segment of the Ciona intestine, suggesting that the proximal intestine might play the part of pancreatic functions in C. savignyi. Our results demonstrate that the tunicate intestine can be functionally separated into three distinct segments, which are comparable to the corresponding regions of the vertebrate intestinal system, offering insights into the functional evolution of the digestive system in chordates.

Intestinal neuropod cell GUCY2C regulates visceral pain

Visceral pain (VP) is a global problem with complex etiologies and limited therapeutic options. Guanylyl cyclase C (GUCY2C), an intestinal receptor producing cyclic GMP(cGMP), which regulates luminal fluid secretion, has emerged as a therapeutic target for VP. Indeed, FDA-approved GUCY2C agonists ameliorate VP in patients with chronic constipation syndromes, although analgesic mechanisms remain obscure. Here, we revealed that intestinal GUCY2C was selectively enriched in neuropod cells, a type of enteroendocrine cell that synapses with submucosal neurons in mice and humans. GUCY2Chi neuropod cells associated with cocultured dorsal root ganglia neurons and induced hyperexcitability, reducing the rheobase and increasing the resulting number of evoked action potentials. Conversely, the GUCY2C agonist linaclotide eliminated neuronal hyperexcitability produced by GUCY2C-sufficient - but not GUCY2C-deficient - neuropod cells, an effect independent of bulk epithelial cells or extracellular cGMP. Genetic elimination of intestinal GUCY2C amplified nociceptive signaling in VP that was comparable with chemically induced VP but refractory to linaclotide. Importantly, eliminating GUCY2C selectively in neuropod cells also increased nociceptive signaling and VP that was refractory to linaclotide. In the context of loss of GUCY2C hormones in patients with VP, these observations suggest a specific role for neuropod GUCY2C signaling in the pathophysiology and treatment of these pain syndromes.

TRIM27 maintains gut homeostasis by promoting intestinal stem cell self-renewal

Dysregulation of gut homeostasis is associated with irritable bowel syndrome (IBS), a chronic functional gastrointestinal disorder affecting approximately 11.2% of the global population. The poorly understood pathogenesis of IBS has impeded its treatment. Here, we report that the E3 ubiquitin ligase tripartite motif-containing 27 (TRIM27) is weakly expressed in IBS but highly expressed in inflammatory bowel disease (IBD), a frequent chronic organic gastrointestinal disorder. Accordingly, knockout of Trim27 in mice causes spontaneously occurring IBS-like symptoms, including increased visceral hyperalgesia and abnormal stool features, as observed in IBS patients. Mechanistically, TRIM27 stabilizes β-catenin and thus activates Wnt/β-catenin signaling to promote intestinal stem cell (ISC) self-renewal. Consistent with these findings, Trim27 deficiency disrupts organoid formation, which is rescued by reintroducing TRIM27 or β-catenin. Furthermore, Wnt/β-catenin signaling activator treatment ameliorates IBS symptoms by promoting ISC self-renewal. Taken together, these data indicate that TRIM27 is critical for maintaining gut homeostasis, suggesting that targeting the TRIM27/Wnt/β-catenin axis could be a potential treatment strategy for IBS. Our study also indicates that TRIM27 might serve as a potential biomarker for differentiating IBS from IBD.

Stereoselective Metabolism of Bupropion to Active Metabolites in Cellular Fractions of Human Liver and Intestine

Striking stereoselective disposition of the antidepressant and smoking cessation aid bupropion (BUP) and its active metabolites observed clinically influence patients' response to BUP therapy and its clinically important drug-drug interactions (DDI) with CYP2D6 substrates. However, understanding of the biochemical mechanisms responsible is incomplete. This study comprehensively examined hepatic and extrahepatic stereoselective metabolism of BUP in vitro Racemic-, R-, and S-BUP were incubated separately with pooled cellular fractions of human liver [microsomes (HLMs), S9 fractions (HLS9s), and cytosols (HLCs)] and intestinal [microsomes (HIMs), S9 fractions (HIS9s), and cytosols (HICs)] and cofactors. Formations of diastereomers of 4-hydroxyBUP (OHBUP), threohydroBUP (THBUP), and erythrohydroBUP (EHBUP) were quantified using a novel chiral ultra-high performance liquid chromatography/tandem mass spectrometry method. Racemic BUP (but not R- or S-BUP) was found suitable to determine stereoselective metabolism of BUP; both enantiomers showed complete racemization. Compared with that of RR-THBUP, the in vitro intrinsic clearance (Clint) for the formation of SS-THBUP was 42-, 19-, and 8.3-fold higher in HLMs, HLS9 fractions, and HLCs, respectively; Clint for the formation of SS-OHBUP and RS-EHBUP was also higher (2.7- to 3.9-fold) than their R-derived counterparts. In cellular fractions of human intestine, ≥ 95% of total reduction was accounted by the formation of RR-THBUP. Ours is the first to demonstrate marked stereoselective reduction of BUP in HLCs, HIMs, HIS9 fractions, and HICs, providing the first evidence for tissue- and cellular fraction-dependent stereoselective metabolism of BUP. These data may serve as the first critical step toward understanding factors dictating BUP's stereoselective disposition, effects, and DDI risks. SIGNIFICANCE STATEMENT: This work provides a deeper insight into bupropion (BUP) stereoselective oxidation and reduction to active metabolites in cellular fractions of human liver and intestine tissues. The results demonstrate tissue- and cellular fraction-dependent stereospecific metabolism of BUP. These data may improve prediction of BUP stereoselective disposition and understanding of BUP's effects and CYP2D6-dependent drug-drug interaction in vivo.

Diosgenin alleviates nonalcoholic steatohepatitis through affecting liver-gut circulation

Nonalcoholic steatohepatitis (NASH), as the aggressive form of nonalcoholic fatty liver disease (NAFLD), rapidly becomes the leading cause of end-stage liver disease or liver transplantation. Nowadays, there has no approved drug for NASH treatment. Diosgenin possesses multiple beneficial effects towards inhibition of lipid accumulation, cholesterol metabolism, fibrotic progression and inflammatory response. However, there has been no report concerning its effects on NASH so far. Using methionine and choline-deficient (MCD) feeding mice, we evaluated the anti-NASH effects of diosgenin. 16 S rDNA was used to investigate gut microbiota composition. Transcriptome sequencing, LC/MS and GC/MS analysis were used to evaluate bile acids (BAs) metabolism and their related pathway. Compared with the MCD group, diosgenin treatment improved the hepatic dysfunction, especially decreased the serum and hepatic TC, TG, ALT, AST and TBA to nearly 50%. Content of BAs, especially CA and TCA, were decreased from 59.30 and 26.00-39.71 and 11.48 ng/mg in liver and from 0.96 and 2.1-0.47 and 1.13 μg/mL in serum, and increased from 7.01 and 11.08-3.278 and 5.11 ng/mg in feces, respectively. Antibiotic and fecal microbiota transplantation (FMT) treatment further confirmed the therapeutic effect of diosgenin on gut microbiota, especially Clostridia (LDA score of 4.94), which regulated BAs metabolism through the hepatic FXR-SHP and intestinal FXR-FGF15 pathways. These data indicate that diosgenin prevents NASH by altering Clostridia and BAs metabolism. Our results shed light on the mechanisms of diosgenin in treating NASH, which pave way for the design of novel clinical therapeutic strategies.

Conserved roles for Hnf4 family transcription factors in zebrafish development and intestinal function

Transcription factors play important roles in the development of the intestinal epithelium and its ability to respond to endocrine, nutritional, and microbial signals. Hepatocyte nuclear factor 4 family nuclear receptors are liganded transcription factors that are critical for the development and function of multiple digestive organs in vertebrates, including the intestinal epithelium. Zebrafish have 3 hepatocyte nuclear factor 4 homologs, of which, hnf4a was previously shown to mediate intestinal responses to microbiota in zebrafish larvae. To discern the functions of other hepatocyte nuclear factor 4 family members in zebrafish development and intestinal function, we created and characterized mutations in hnf4g and hnf4b. We addressed the possibility of genetic redundancy amongst these factors by creating double and triple mutants which showed different rates of survival, including apparent early lethality in hnf4a; hnf4b double mutants and triple mutants. RNA sequencing performed on digestive tracts from single and double mutant larvae revealed extensive changes in intestinal gene expression in hnf4a mutants that were amplified in hnf4a; hnf4g mutants, but limited in hnf4g mutants. Changes in hnf4a and hnf4a; hnf4g mutants were reminiscent of those seen in mice including decreased expression of genes involved in intestinal function and increased expression of cell proliferation genes, and were validated using transgenic reporters and EdU labeling in the intestinal epithelium. Gnotobiotics combined with RNA sequencing also showed hnf4g has subtler roles than hnf4a in host responses to microbiota. Overall, phenotypic changes in hnf4a single mutants were strongly enhanced in hnf4a; hnf4g double mutants, suggesting a conserved partial genetic redundancy between hnf4a and hnf4g in the vertebrate intestine.

Preventive Mechanism of Lycopene on Intestinal Toxicity Caused by Cyclophosphamide Chemotherapy in Mice by Regulating TLR4-MyD88/TRIF-TRAF6 Signaling Pathway and Gut-Liver Axis

Cyclophosphamide (CYC) is the first-line chemotherapy drug for cancer in clinical practice, and its intestinal toxicity seriously affects the treatment effect and prognosis of patients. Lycopene (LP) is the main pigment of ripe tomatoes and has strong antioxidant activity. However, the mechanism by which LP prevents CYC-induced intestinal injury remains unclear. The aim of this study was to investigate the mechanism of LP in preventing intestinal toxicity caused by CYC chemotherapy in mice. The results showed that LP significantly prevented spleen and thymus atrophy induced by CYC. In terms of intestinal injury, LP significantly increased the levels of superoxide dismutase (SOD), secretory immunoglobulin A (sIgA), interleukin (IL)-4, IL-12, and interferon (IFN)-γ, decreased the content of lipid oxidation (MDA), upregulated the protein expressions of toll-like receptors 4 (TLR4), myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), toll/IL-1receptor domain containing adaptor protein inducing IFN-β (TRIF), p-P38 MAPK (P38), and p-nuclear factor kappa-B (NF-κB) p65, and improved the small intestine tissue injury induced by CYC. In terms of liver injury, LP significantly increased the content of glutathione (GSH), decreased the contents of MDA, nitric oxide (NO), IL-1β, IL-6, and tumor necrosis factor (TNF)-α, and repaired the liver tissue injury induced by CYC. Importantly, 10 mg/kg LP significantly prevented intestinal microbiota dysregulation in CYC mice. These results suggested that LP significantly prevented intestinal injury induced by CYC in mice by regulating the TLR4-MyD88/TRIF-TRAF6 signaling pathway and gut-liver axis.

Illustration of Gut-Thyroid Axis in Alcohol Use Disorder: Interplay of Gut Dysfunction, Pro-Inflammatory Responses, and Thyroid Function

(1) Background: Heavy and chronic alcohol drinking leads to altered gut dysfunction, coupled with a pro-inflammatory state. Thyroid-associated hormones and proteins may be dysregulated by heavy and chronic alcohol intake; however, the mechanism for altered gut-derived changes in thyroid function has not been studied thus far. This study investigates the role of alcohol-induced gut dysfunction and pro-inflammatory cytokine profile in the thyroid function of patients with alcohol use disorder (AUD). (2) Methods: Male and female AUD patients (n = 44) were divided into Gr.1, patients with normal thyroid-stimulating hormone (TSH) levels (n = 28, 0.8 ≤ TSH ≤ 3 mIU/L); and Gr.2, patients with clinically elevated TSH levels (n = 16, TSH > 3 mIU/L). Demographics, drinking measures, comprehensive metabolic panels, and candidate thyroid markers (TSH, circulating triiodothyronine (T3), and free thyroxine (fT4)) were analyzed. Gut-dysfunction-associated markers (lipopolysaccharide (LPS), LPS-binding protein (LBP), and soluble LPS-induced pathogen-associated protein (sCD14)), and candidate pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-8, MCP-1, PAI-1) were also evaluated. (3) Results: Patients in both groups presented with a borderline overweight BMI category. Gr.2 reported numerically higher indices of chronic and heavy drinking patterns than Gr.1. The fT4 levels were elevated, while T3 was within normal limits in both groups. The gut dysfunction markers LBP and sCD14 were numerically elevated in Gr.2 vs. Gr.1, suggesting subtle ongoing changes. Candidate pro-inflammatory cytokines were significantly elevated in Gr.2, including IL-1 β, MCP-1, and PAI-1. Gr.2 showed a strong and statistically significant effect on the gut–immune–thyroid response (r = 0.896, 36 p = 0.002) on TSH levels in a multivariate regression model with LBP, sCD14, and PAI-1 levels as upstream variables in the gut–thyroid pathway. In addition, AUROC analysis demonstrated that many of the cytokines strongly predicted TSH in Gr.2, including IL-6 (area = 0.774, 39 p < 0.001) and TNF-α (area = 0.708, p = 0.017), among others. This was not observed in Gr.1. Gr.2 demonstrated elevated fT4, as well as TSH, which suggests that there was subclinical thyroiditis with underlying CNS dysfunction and a lack of a negative feedback loop. (4) Conclusions: These findings reveal the toxic effects of heavy and chronic drinking that play a pathological role in thyroid gland dysregulation by employing the gut–brain axis. These results also emphasize potential directions to carefully evaluate thyroid dysregulation in the overall medical management of AUD.

Intestinal mucus-derived metabolites modulate virulence of a clade 8 enterohemorrhagic Escherichia coli O157:H7

The human colonic mucus is mainly composed of mucins, which are highly glycosylated proteins. The normal commensal colonic microbiota has mucolytic activity and is capable of releasing the monosaccharides contained in mucins, which can then be used as carbon sources by pathogens such as Enterohemorrhagic Escherichia coli (EHEC). EHEC can regulate the expression of some of its virulence factors through environmental sensing of mucus-derived sugars, but its implications regarding its main virulence factor, Shiga toxin type 2 (Stx2), among others, remain unknown. In the present work, we have studied the effects of five of the most abundant mucolytic activity-derived sugars, Fucose (L-Fucose), Galactose (D-Galactose), N-Gal (N-acetyl-galactosamine), NANA (N-Acetyl-Neuraminic Acid) and NAG (N-Acetyl-D-Glucosamine) on EHEC growth, adhesion to epithelial colonic cells (HCT-8), and Stx2 production and translocation across a polarized HCT-8 monolayer. We found that bacterial growth was maximum when using NAG and NANA compared to Galactose, Fucose or N-Gal, and that EHEC adhesion was inhibited regardless of the metabolite used. On the other hand, Stx2 production was enhanced when using NAG and inhibited with the rest of the metabolites, whilst Stx2 translocation was only enhanced when using NANA, and this increase occurred only through the transcellular route. Overall, this study provides insights on the influence of the commensal microbiota on the pathogenicity of E. coli O157:H7, helping to identify favorable intestinal environments for the development of severe disease.

Intestinal Osteopontin Protects From Alcohol-induced Liver Injury by Preserving the Gut Microbiome and the Intestinal Barrier Function

BACKGROUND & AIMS

The gut-liver axis plays a key role in the pathogenesis of alcohol-associated liver disease (ALD). We demonstrated that Opn^-/- develop worse ALD than wild-type (WT) mice; however, the role of intestinal osteopontin (OPN) in ALD remains unknown. We hypothesized that overexpression of OPN in intestinal epithelial cells (IECs) could ameliorate ALD by preserving the gut microbiome and the intestinal barrier function.

METHODS

Opn^{KI IEC}, Opn^ΔIEC, and WT mice were fed control or ethanol Lieber-DeCarli diet for 6 weeks.

RESULTS

Opn^{KI IEC} but not Opn^ΔIEC mice showed improved intestinal barrier function and protection from ALD. There were less pathogenic and more beneficial bacteria in ethanol-fed Opn^{KI IEC} than in WT mice. Fecal microbiome transplant (FMT) from Opn^{KI IEC} to WT mice protected from ALD. FMT from ethanol-fed WT to Opn^{KI IEC} mice failed to induce ALD. Antimicrobial peptides, Il33, pSTAT3, aryl hydrocarbon receptor (Ahr), and tight-junction protein expression were higher in IECs from jejunum of ethanol-fed Opn^{KI IEC} than of WT mice. Ethanol-fed Opn^{KI IEC} showed more tryptophan metabolites and short-chain fatty acids in portal serum than WT mice. FMT from Opn^{KI IEC} to WT mice enhanced IECs Ahr and tight-junction protein expression. Oral administration of milk OPN replicated the protective effect of Opn^{KI IEC} mice in ALD.

CONCLUSION

Overexpression of OPN in IECs or administration of milk OPN maintain the intestinal microbiome by intestinal antimicrobial peptides. The increase in tryptophan metabolites and short-chain fatty acids signaling through the Ahr in IECs, preserve the intestinal barrier function and protect from ALD.

Enhanced therapeutic effect on colitis with powder formulations of Painong San associated with the promotion of intestinal adhesion and absorption

ETHNOPHARMACOLOGICAL RELEVANCE

Painong San is a prescription composed of traditional Chinese medicine, which has been used to treat colitis. The Painong San's usage recorded in "Jingui Yaolve" by Zhongjing Zhang in the Later Han Dynasty is powder. However, the decoction is often used in reality. It's unclear which dosage form of Painong San is more suitable for colitis treatment and why?

AIM OF THE STUDY

This study aims to evaluate the different therapeutic effects of Painong San (a powder of Painong San) and Painong Decoction (a decoction of Painong San) on a dextran sulfate sodium salt-induced colitis model and the possible reasons of these different effects.

MATERIALS AND METHODS

The contents of paeoniflorin, naringin, heperidin and neohesperidin in Painong San and Painong decoction were determined by an ultra-performance liquid chromatography system. The therapeutic effect on colitis was evaluated by intragastric administration of Painong San or Painong Decoction in dextran sulfate sodium salt-induced mouse model. The accumulated release rate of Painong San in vitro was analyzed with artificial gastric juice, artificial intestinal juice, and artificial colon juice. The concentrations of four compounds in the blood, intestinal contents, and intestinal fluids were detected by an-ultra performance liquid chromatography-tandem quadrupole mass spectrometry system. In situ intestinal perfusion experiments were used to observe the adhesion of Painong San to the intestine's surface. The expression of Mucin-2 and Trefoil Factor 3 in the colon was studied by immunohistochemistry.

RESULTS

There was no significant difference in the contents of the four compounds in Painong San and Painong Decoction. In vivo, Painong San has a better therapeutic effect than Painong Decoction in the treatment of colitis. Painong San could be released slowly in the simulated human digestion environment in vitro, and more Painong San particles were released on the intestinal surface in the colitis state in the healthy state. Painong San could increase the bioavailability of hesperidin and neohesperidin, and their concentrations in local intestinal tissue, intestinal fluid and intestinal contents. The expression of trefoil Factor 3 protein on the surface of the colon tended to be in the intestinal cavity and overlapped with the expression of mucin-2. Trefoil Factor 3 accumulates in the intestinal cavity of the colon in the state of colitis, which may increase the adhesion of Painong San particles.

CONCLUSION

In conclusion, this experiment proved that Painong San is a more suitable dosage form for the treatment of dextran sulfate sodium salt-induced colitis than Painong Decoction, which may be related to the enhancement of Painong San particle adhesion to the intestine in colitis. This study provides a reference for the selection of clinical dosage forms for traditional Chinese medicine.

[Lipopolysaccharide induces inflammation and up-regulates the expression of methyltransferase-like 3 (METTL3) and METTL14 in human and mouse intestinal epithelial cells]

Objective To investigate the changes of N⁶-methyladenosine (m⁶A) modification in the inflammatory status of HIEC-6 human intestinal epithelial cells and MODE-K mouse intestinal epithelial cells. Methods HIEC-6 cells and MODE-K cells were induced by different concentrations of lipopolysaccharide (LPS), interleukin-1β (IL-1β), IL-6 and tumor necrosis factor alpha (TNF-α) for 10 hours or the same concentration of LPS, IL-1β, IL-6 and TNF-α for 0, 3, 6, 12, 24 hours, respectively. The mRNA expression levels of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were detected by real-time quantitative PCR. The mRNA and protein expression levels of m⁶A modification-related molecules methyltransferase-like 3 (METTL3), METTL14, METTL16, Wilm's tumor 1-associated protein (WTAP), alkylation repair homolog protein 5 (ALKBH5), fat-mass and obesity-associated protein (FTO), YTH domain-containing 1 (YTHDC1), YTHDC2 were detected through real-time quantitative PCR and Western blot, respectively. Results The mRNA expression levels of IL-1β, IL-6 and TNF-α were increased and the mRNA and protein expression levels of METTL3 and METTL14 were simultaneously up-regulated in time-dependent and concentration-dependent LPS-induced model in HIEC-6 cells and MODE-K cells. Conclusion LPS can induce inflammation and up-regulate the expression of METTL3 and METTL14 in intestinal epithelial cells.

Nicotinamide phosphoribosyltransferase (Nampt) of hybrid crucian carp protects intestinal barrier and enhances host immune defense against bacterial infection

Nicotinamide phosphoribosyltransferase (Nampt) can act extracellularly as a mediator of inflammation or intracellularly as a rate-limiting enzyme, regulating nicotinamide adenine dinucleotide (NAD) biosynthesis in the NAD salvage pathway. Nampt exerts important immunological functions during infection in mammals. However, the in vivo function of fish Nampt in immune regulation and inflammation is essentially unknown. With an aim to elucidate the antimicrobial mechanism of Nampt in fish, we in this study examined the function of Nampt from hybrid crucian carp. Hybrid crucian carp Nampt (WR-Nampt) possesses the conserved nicotinamide phosphoribosyltransferase domain and shows high similarity to that of mammalian Nampt. WR-Nampt is expressed in multiple tissues and is upregulated by bacterial infection. Overexpression of WR-Nampt significantly increased the number of goblet cells of distal intestine. In addition, WR-Nampt induced significant inductions in the expression of the antimicrobial molecules (IL-22, Hepcidin-1, LEAP-2 and MUC2) and tight junctions (ZO-1 and Occludin). Consistent with this, fish administered with WR-Nampt significantly alleviated the intestinal permeability and apoptosis, thereby enhancing host's resistance against bacterial infection. Together these results revealed the potential effect of WR-Nampt in intestinal barrier and immune defense against bacterial infection.

Exploring the pathogenesis of type 2 diabetes mellitus intestinal damp-heat syndrome and the therapeutic effect of Gegen Qinlian Decoction from the perspective of exosomal miRNA

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes is a common, complex, chronic metabolic disease. A randomized, double-blind, placebo-parallel controlled clinical study has shown that Gegen Qinlian Decoction (GQD) can reduce glycosylated hemoglobin in type 2 diabetes mellitus (T2DM) intestinal damp-heat syndrome patients in a dose-dependent manner.

AIM

To explore the pathogenesis of T2DM intestinal damp-heat syndrome and the therapeutic effect of GQD from the perspective of exosomal microRNA (miRNA).

METHODS

Eligible patients were selected and treated with GQD for 3 months to evaluate their clinical efficacy. Effective cases were matched with healthy volunteers, and saliva samples were collected. Exosomal miRNA was extracted from saliva and analyzed by chip sequencing. Subsequently, the function of the differential gene and the signal transduction pathway were analyzed using bioinformatics technology. Finally, three target miRNAs were randomly selected from the T2DM group/healthy group, and two target miRNAs in the T2DM before treatment/after treatment group were randomly selected for qPCR verification. Finally, we conducted a correlation analysis of the miRNAs and clinical indicators. The registration number for this research is ChiCTR-IOR-15006626.

RESULTS

(1) The expression of exosomal miRNA chips showed that there were 14 differentially expressed miRNAs in the T2DM group/healthy group, and 26 differentially expressed miRNAs in the T2DM before treatment/after treatment group. (2) Enrichment results showed that in the T2DM group/healthy group, it was primarily related to cell development, body metabolism, TGF-β, and ErbB signaling pathways. In the T2DM before treatment/after treatment group, it was mainly related to cellular metabolic regulation processes, and insulin, Wnt, and AMPK signaling pathways. (3) The qPCR verification showed that the expressions of hsa-miR-9-5p, hsa-miR-150-5p, and hsa-miR-216b-5p in the T2DM group was higher (P<0.05). Following GQD treatment, hsa-miR-342-3p and hsa-miR-221-3p were significantly downregulated (P<0.05). (4) hsa-miR-9-5p was positively correlated with BMI (P<0.05), and hsa-miR-150-5p was positively correlated with total cholesterol and triglycerides (P<0.05). The GQD efficacy-related gene hsa-miR-342-3p was positively correlated with the patient's initial blood glucose level (P<0.05), and hsa-miR-221-3p was positively correlated with total cholesterol and triglycerides (P<0.05).

CONCLUSION

The exosomal miRNA expression profile and signaling pathways related to T2DM intestinal damp-heat syndrome and the efficacy of GQD were established, which provides an alternative strategy for precision traditional Chinese medicine treatment.

A Transcriptomic Approach to Elucidate the Mechanisms of Gefitinib-Induced Toxicity in Healthy Human Intestinal Organoids

Gefitinib is a tyrosine kinase inhibitor (TKI) that selectively inhibits the epidermal growth factor receptor (EGFR), hampering cell growth and proliferation. Due to its action, gefitinib has been used in the treatment of cancers that present abnormally increased expression of EGFR. However, side effects from gefitinib therapy may occur, among which diarrhoea is most common, that can lead to interruption of the planned therapy in the more severe cases. The mechanisms underlying intestinal toxicity induced by gefitinib are not well understood. Therefore, this study aims at providing insight into these mechanisms based on transcriptomic responses induced in vitro. A 3D culture of healthy human colon and small intestine (SI) organoids was exposed to 0.1, 1, 10 and 30 µM of gefitinib, for a maximum of three days. These drug concentrations were selected using physiologically-based pharmacokinetic simulation considering patient dosing regimens. Samples were used for the analysis of viability and caspase 3/7 activation, image-based analysis of structural changes, as well as RNA isolation and sequencing via high-throughput techniques. Differential gene expression analysis showed that gefitinib perturbed signal transduction pathways, apoptosis, cell cycle, FOXO-mediated transcription, p53 signalling pathway, and metabolic pathways. Remarkably, opposite expression patterns of genes associated with metabolism of lipids and cholesterol biosynthesis were observed in colon versus SI organoids in response to gefitinib. These differences in the organoids’ responses could be linked to increased activated protein kinase (AMPK) activity in colon, which can influence the sensitivity of the colon to the drug. Therefore, this study sheds light on how gefitinib induces toxicity in intestinal organoids and provides an avenue towards the development of a potential tool for drug screening and development.

Bifidobacterium lactis BL-99 modulates intestinal inflammation and functions in zebrafish models

This study was designed to explore the therapeutics and the mechanisms of a patented and marked gastric acid and intestine juice-resistant probiotics Bifidobacterium lactis BL-99 (B. lactis BL-99) on the intestinal inflammation and functions in the zebrafish models. After feeding for 6 hours, B. lactis BL-99 was fully retained in the larval zebrafish intestinal tract and stayed for over 24 hours. B. lactis BL-99 promoted the intestinal motility and effectively alleviated aluminum sulfate-induced larval zebrafish constipation (p < 0.01). Irregular high glucose diet induced adult zebrafish intestinal functional and metabolic disorders. After fed with B. lactis BL-99, IL-1β gene expression was significantly down-regulated, and IL-10 and IL-12 gene levels were markedly up-regulated in this model (p < 0.05). The intestinal lipase activity was elevated in the adult zebrafish intestinal functional disorder model after B. lactis BL-99 treatment (p < 0.05), but tryptase content had no statistical changes (p > 0.05). B. lactis BL-99 improved the histopathology of the adult zebrafish intestinal inflammation, increased the goblet cell numbers, and up-and-down metabolites were markedly recovered after treatment of B. lactis BL-99 (p < 0.05). These results suggest that B. lactis BL-99 could relieve intestinal inflammation and promote intestinal functions, at least in part, through modulating intestinal and microbial metabolism to maintain intestinal health.

Transcriptional Control of Trpm6 by the Nuclear Receptor FXR

Farnesoid x receptor (FXR) is a nuclear bile acid receptor that belongs to the nuclear receptor superfamily. It plays an essential role in bile acid biosynthesis, lipid and glucose metabolism, liver regeneration, and vertical sleeve gastrectomy. A loss of the FXR gene or dysregulations of FXR-mediated gene expression are associated with the development of progressive familial intrahepatic cholestasis, tumorigenesis, inflammation, and diabetes mellitus. Magnesium ion (Mg²⁺) is essential for mammalian physiology. Over 600 enzymes are dependent on Mg²⁺ for their activity. Here, we show that the Trpm6 gene encoding a Mg²⁺ channel is a direct FXR target gene in the intestinal epithelial cells of mice. FXR expressed in the intestinal epithelial cells is absolutely required for sustaining a basal expression of intestinal Trpm6 that can be robustly induced by the treatment of GW4064, a synthetic FXR agonist. Analysis of FXR ChIP-seq data revealed that intron regions of Trpm6 contain two prominent FXR binding peaks. Among them, the proximal peak from the transcription start site contains a functional inverted repeat 1 (IR1) response element that directly binds to the FXR-RXRα heterodimer. Based on these results, we proposed that an intestinal FXR-TRPM6 axis may link a bile acid signaling to Mg²⁺ homeostasis.

IL-17RA-signaling in Lgr5+ intestinal stem cells induces expression of transcription factor ATOH1 to promote secretory cell lineage commitment

The Th17 cell-lineage-defining cytokine IL-17A contributes to host defense and inflammatory disease by coordinating multicellular immune responses. The IL-17 receptor (IL-17RA) is expressed by diverse intestinal cell types, and therapies targeting IL-17A induce adverse intestinal events, suggesting additional tissue-specific functions. Here, we used multiple conditional deletion models to identify a role for IL-17A in secretory epithelial cell differentiation in the gut. Paneth, tuft, goblet, and enteroendocrine cell numbers were dependent on IL-17A-mediated induction of the transcription factor ATOH1 in Lgr5+ intestinal epithelial stem cells. Although dispensable at steady state, IL-17RA signaling in ATOH1+ cells was required to regenerate secretory cells following injury. Finally, IL-17A stimulation of human-derived intestinal organoids that were locked into a cystic immature state induced ATOH1 expression and rescued secretory cell differentiation. Our data suggest that the cross talk between immune cells and stem cells regulates secretory cell lineage commitment and the integrity of the mucosa.

Bacterial peptidoglycan muropeptides benefit mitochondrial homeostasis and animal physiology by acting as ATP synthase agonists

The symbiotic relationship between commensal microbes and host animals predicts unidentified beneficial impacts of individual bacterial metabolites on animal physiology. Peptidoglycan fragments (muropeptides) from the bacterial cell wall are known for their roles in pathogenicity and for inducing host immune responses. However, the potential beneficial usage of muropeptides from commensal bacteria by the host needs exploration. We identified a striking role for muropeptides in supporting mitochondrial homeostasis, development, and behaviors in Caenorhabditis elegans. We determined that the beneficial molecules are disaccharide muropeptides containing a short AA chain, and they enter intestinal-cell mitochondria to repress oxidative stress. Further analyses indicate that muropeptides execute this role by binding to and promoting the activity of ATP synthase. Therefore, given the exceptional structural conservation of ATP synthase, the role of muropeptides as a rare agonist of the ATP synthase presents a major conceptual modification regarding the impact of bacterial cell metabolites on animal physiology.

A Major Intestinal Catabolite of Quercetin Glycosides, 3-Hydroxyphenylacetic Acid, Protects the Hepatocytes from the Acetaldehyde-Induced Cytotoxicity through the Enhancement of the Total Aldehyde Dehydrogenase Activity

Aldehyde dehydrogenases (ALDHs) are the major enzyme superfamily for the aldehyde metabolism. Since the ALDH polymorphism leads to the accumulation of acetaldehyde, we considered that the enhancement of the liver ALDH activity by certain food ingredients could help prevent alcohol-induced chronic diseases. Here, we evaluated the modulating effects of 3-hydroxyphenylacetic acid (OPAC), the major metabolite of quercetin glycosides, on the ALDH activity and acetaldehyde-induced cytotoxicity in the cultured cell models. OPAC significantly enhanced the total ALDH activity not only in mouse hepatoma Hepa1c1c7 cells, but also in human hepatoma HepG2 cells. OPAC significantly increased not only the nuclear level of aryl hydrocarbon receptor (AhR), but also the AhR-dependent reporter gene expression, though not the nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent one. The pretreatment of OPAC at the concentration required for the ALDH upregulation completely inhibited the acetaldehyde-induced cytotoxicity. Silencing AhR impaired the resistant effect of OPAC against acetaldehyde. These results strongly suggested that OPAC protects the cells from the acetaldehyde-induced cytotoxicity, mainly through the AhR-dependent and Nrf2-independent enhancement of the total ALDH activity. Our findings suggest that OPAC has a protective potential in hepatocyte models and could offer a new preventive possibility of quercetin glycosides for targeting alcohol-induced chronic diseases.

Soy diet induces intestinal inflammation in adult Zebrafish: Role of OTX and P53 family

Inflammatory bowel diseases (IBDs) are a group of inflammatory conditions of the colon and small intestine, including Crohn's disease and ulcerative colitis. Since Danio rerio is a promising animal model to study gut function, we developed a soy-dependent model of intestinal inflammation in adult zebrafish. The soya bean meal diet was given for 4 weeks and induced an inflammatory process, as demonstrated by morphological changes together with an increased percentage of neutrophils infiltrating the intestinal wall, which developed between the second and fourth week of treatment. Pro-inflammatory genes such as interleukin-1beta, interleukin-8 and tumour necrosis factor alpha were upregulated in the second week and anti-inflammatory genes such as transforming growth factor beta and interleukin-10. Interestingly, an additional expression peak was found for interleukin-8 at the fourth week. Neuronal genes, OTX1 and OTX2, were significantly upregulated in the first two  weeks, compatible with the development of the changes in the gut wall. As for the genes of the p53 family such as p53, DNp63 and p73, a statistically significant increase was observed after two weeks of treatment compared with controls. Interestingly, DNp63 and p73 were shown an additional peak after four weeks. Our data demonstrate that soya bean meal diet negatively influences intestinal morphology and immunological function in adult zebrafish showing the features of acute inflammation. Data observed at the fourth week of treatment may suggest initiation of chronic inflammation. Adult zebrafish may represent a promising model to better understand the mechanisms of food-dependent intestinal inflammation.

Glycaemia and body weight are regulated by sodium-glucose cotransporter 1 (SGLT1) expression via O-GlcNAcylation in the intestine

Objective

Methods

Results

Conclusion

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Intestine-specific OGT depletion results in weight loss and hypoglycaemia.

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It reduces SGLT1 expression, resulting in glucose absorption from the gut.

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OGT knockdown may contribute to diminish glucose-induced incretin secretion.

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OGT may regulate SGLT1 expression via the cAMP/CREB-dependent pathway.

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O-GlcNAcylation regulates SGLT1 expression in the intestine and the kidney.

Rhamnolipids enhance growth performance by improving the immunity, intestinal barrier function, and metabolome composition in broilers

BACKGROUND

Rhamnolipids (RLS), well known as glycolipid biosurfactants, display low toxicity, high biodegradability, and strong antibacterial properties. This study was carried out to evaluate the use of RLS supplementation as a substitute for antibiotics, and particularly to evaluate its effects on growth performance, immunity, intestinal barrier function, and metabolome composition in broilers.

RESULTS

The RLS treatment improved the growth performance, immunity, and intestinal barrier function in broilers. The 16S rRNA sequencing revealed that the genus Alistipes was the dominant genus in broilers treated by RLS. An ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based metabolomic analysis indicated that the sphingolipid metabolism, glycine, serine, and threonine metabolism, the gycerophospholipid metabolism, and the tryptophan metabolism were changed in broilers that were treated with RLS.

CONCLUSION

l-Tryptophan may be the medium for RLS to regulate the growth and physiological metabolism. Rhamnolipids can be used as a potential alternative to antibiotics, with similar functions to antibiotics in the diet of broilers. The optimal level of supplemented RLS in the diet was 1000 mg kg^-1 . © 2021 Society of Chemical Industry.