Corrigendum: Dihydromyricetin improves growth performance, immunity, and intestinal functions in weaned pigs challenged by enterotoxigenic Escherichia coli.

[This corrects the article DOI: 10.3389/fvets.2024.1421871.].

Effect of coated-benzoic acid on growth performance, immunity, and intestinal functions in weaned pigs challenged by enterotoxigenic Escherichia coli.

Introduction: Benzoic acid (BA) could be added to the diets of weaned pigs to prevent diarrhea due to its antibacterial function. However, BA may be absorbed or decomposed before it can reach the hindgut. This study was conducted to explore the effect of a novel coated benzoic acid (CBA) on growth performance, immunity, and intestinal barrier functions in weaned pigs upon enterotoxigenic Escherichia coli (ETEC) challenge. Methods: In a 21d experiment, 32 piglets were randomly assigned to 4 treatments: (1) a basal diet (CON), (2) CON added with CBA at 3 g/kg (CBA); (3) CON and challenged by ETEC (ECON); (4) CON added with CBA at 3 g/kg and challenged by ETEC (ECON). On d 22, all piglets were euthanised to obtain samples. Results: Dietary CBA supplementation elevated the average daily gain (ADG) of the ETEC-challenged pigs (p < 0.05). CBA also improved the digestibility of dry matter, gross energy, and ash (p < 0.05). Moreover, CBA elevated the ratio of blood basophil and the serum concentration of total cholesterol of the ETEC challenged pigs (p < 0.05). Importantly, CBA increased the serum concentrations of immunoglobulin A (IgA), IgG, and IgM (p < 0.05). CBA not only decreased the crypt depth but also increased the ratio of villus height to crypt depth (V:C) in the jejunum and ileum (p < 0.05). Moreover, CBA increased the activities of jejunal and ileal sucrase, and the activities of duodenal and ileal maltase (p < 0.05). Importantly, CBA elevated the expression levels of critical functional genes such as the claudin-1, occluding, glucose transporter-2 (GLUT2), and sodium/glucose cotransporter-1 (SGLT-1) in the jejunal epithelium upon ETEC challenge (p < 0.05). Additionally, CBA increased the abundances of total bacteria and Bacillus, and increased the concentrations of volatile fatty acids (acetic acid, propanoic acid, and butyric acid) in cecum (p < 0.05). Discussion: These results suggested a beneficial role for CBA in alleviating intestinal injury in weaned pigs following ETEC challenge. Such effects may be tightly associated with elevated immunity and improved intestinal epithelium functions and microbiota.

Mannose coated selenium nanoparticles normalize intestinal homeostasis in mice and mitigate colitis by inhibiting NF-κB activation and enhancing glutathione peroxidase expression.

Impaired intestinal homeostasis is a major pathological feature of inflammatory bowel diseases (IBD). Mannose and selenium (Se) both demonstrate potential anti-inflammatory and anti-oxidative properties. However, most lectin receptors bind free monosaccharide ligands with relatively low affinity and most Se species induce side effects beyond a very narrow range of dosage. This has contributed to a poorly explored therapies for IBD that combine mannose and Se to target intestinal epithelial cells (IECs) for normalization gut homeostasis. Herein, a facile and safe strategy for ulcerative colitis (UC) treatment was developed using optimized, mannose-functionalized Se nanoparticles (M-SeNPs) encapsulated within a colon-targeted hydrogel delivery system containing alginate (SA) and chitosan (CS). This biocompatible nanosystem was efficiently taken up by IECs and led to increased expression of Se-dependent glutathione peroxidases (GPXs), thereby modulating IECs' immune response. Using a mouse model of DSS-induced colitis, (CS/SA)-embedding M-SeNPs (C/S-MSe) were found to mitigate oxidative stress and inflammation through the inhibition of the NF-kB pathway in the colon. This stabilized mucosal homeostasis of IECs and ameliorated colitis-related symptoms, thereby providing a potential new approach for treatment of IBD.

The influence of AHR on immune and tissue biology.

The aryl hydrocarbon receptor is a ligand dependent transcription factor which functions as an environmental sensor. Originally discovered as the sensor for man made pollutants such as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) it has recently gained prominence as an important mediator for environmental triggers via the diet or microbiota which influences many physiological functions in different cell types and tissues across the body. Notably AHR activity contributes to prevent excessive inflammation following tissue damage in barrier organs such as skin, lung or gut which has received wide attention in the past decade. In this review we will focus on emerging common AHR functions across cell types and tissues and discuss ongoing issues that confound the understanding of AHR physiology. Furthermore, we will discuss the need for deeper molecular understanding of the functional activity of AHR in different contexts with respect to development of potential therapeutic applications.

IFNγ induces epithelial reprogramming driving CXCL11-mediated T cell migration.

The cytokine interferon-gamma (IFNγ) plays a multifaceted role in intestinal immune responses ranging from anti- to pro-inflammatory depending on the setting. Here, using a 3D co-culture system based on human intestinal epithelial organoids, we explore the capacity of IFNγ-exposure to reprogram intestinal epithelia and thereby directly modulate lymphocyte responses. IFNγ treatment of organoids led to transcriptional reprogramming, marked by a switch to a pro-inflammatory gene expression profile, including transcriptional upregulation of the chemokines CXCL9, CXCL10, and CXCL11. Proteomic analysis of organoid-conditioned medium post-treatment confirmed chemokine secretion. IFNγ-treatment of organoids led to enhanced T cell migration in a CXCL11-dependent manner without affecting T cell activation status. Taken together, our results suggest a specific role for CXCL11 in T cell recruitment that could be targeted to prevent T cell trafficking to the inflamed intestine.

Cannabinoids Block Fat-induced Incretin Release via CB1-dependent and CB1-independent Pathways in Intestinal Epithelium.

Background and Aims: Glucose homeostasis is regulated by a dynamic interplay between hormones along the gastro-insular axis. For example, enteroendocrine L- and K- cells that line the intestine produce the incretins glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP), respectively, which are secreted following a meal. Broadly, incretin signaling enhances insulin release from the endocrine pancreas and participates in the control of food intake, and therapeutics that mimic their activity have recently been developed for the treatment of type-2 diabetes and obesity. Notably, genes for cannabinoid subtype-1 receptor (CB1R) are expressed in these cell subpopulations; however, roles for CB1Rs in controlling fat-induced incretin release are unclear. To address this gap in our understanding, we tested the hypothesis that intestinal epithelial CB1Rs control fat-induced incretin secretion. Methods: We treated mice with conditional deletion of CB1Rs in the intestinal epithelium (IntCB1-/-) or controls (IntCB1+/+) with oil gavage to stimulate incretin release in the presence of the cannabinoid receptor agonists, WIN55,212-2 or Δ9 tetrahydrocannabinol (THC), and the peripherally-restricted CB1R antagonist AM6545. Circulating incretin levels were measured in plasma. Results: Oral gavage of corn oil increased levels of bioactive GLP1 and GIP in IntCB1+/+ mouse plasma. Pretreatment with the WIN55,212-2 or THC blocked this response, which was largely reversed by coadministration with AM6545. WIN55,212-2 failed to inhibit fat-induced GIP release, but not GLP1, in IntCB1-/- mice. In contrast, THC inhibited the secretion of incretins irrespective of CB1R expression in intestinal epithelial cells. Conclusion: These results indicate that cannabinoid receptor agonists can differentially inhibit incretin release via mechanisms that include intestinal epithelial CB1R-dependent and CB1R-independent mechanisms.

Dual function of PHF16 in reinstating homeostasis of murine intestinal epithelium after crypt regeneration.

Intestinal stem cells (ISCs) are highly vulnerable to damage, being in a constant state of proliferation. Reserve stem cells repair the intestinal epithelium following damage-induced ablation of ISCs. Here, we report that the epigenetic regulator plant homology domain (PHD) finger protein 16 (PHF16) restores homeostasis of the intestinal epithelium after initial damage-induced repair. In Phf16-/Y mice, revival stem cells (revSCs) showed defects in exiting the regenerative state, and intestinal crypt regeneration failed even though revSCs were still induced in response to tissue damage, as observed by single-cell RNA sequencing (scRNA-seq). Analysis of Phf16-/Y intestinal organoids by RNA sequencing (RNA-seq) and ATAC sequencing identified that PHF16 restores homeostasis of the intestinal epithelium by inducing retinoic acid receptor (RAR)/retinoic X receptor (RXR) target genes through HBO1-mediated histone H3K14 acetylation, while at the same time counteracting YAP/TAZ activity by ubiquitination of CDC73. Together, our findings demonstrate the importance of timely suppression of regenerative activity by PHF16 for the restoration of gut homeostasis after acute tissue injury.

Human tetraspanin CD81 facilitates invasion of Salmonella enterica into human epithelial cells.

Human CD81 and CD9 are members of the tetraspanin family of proteins characterized by a canonical structure of four transmembrane domains and two extracellular loop domains. Tetraspanins are known as molecular facilitators, which assemble and organize cell surface receptors and partner molecules forming clusters known as tetraspanin-enriched microdomains. They have been implicated to play various biological roles including an involvement in infections with microbial pathogens. Here, we demonstrate an important role of CD81 for the invasion of epithelial cells by Salmonella enterica. We show that the overexpression of CD81 in HepG2 cells enhances invasion of various typhoidal and non-typhoidal Salmonella serovars. Deletion of CD81 by CRISPR/Cas9 in intestinal epithelial cells (C2BBe1 and HT29-MTX-E12) reduces S. Typhimurium invasion. In addition, the effect of human CD81 is species-specific as only human but not rat CD81 facilitates Salmonella invasion. Finally, immunofluorescence microscopy and proximity ligation assay revealed that both human tetraspanins CD81 and CD9 are recruited to the entry site of S. Typhimurium during invasion but not during adhesion to the host cell surface. Overall, we demonstrate that the human tetraspanin CD81 facilitates Salmonella invasion into epithelial host cells.

Set Up and Utilization of a Three-Dimensional In Vitro Bioreactor System for Human Intestinal Studies and Microbial Co-Cultures.

The study of human intestinal physiology and host-microbe interactions is crucial for understanding gastrointestinal health and disease. Traditional two-dimensional cell culture models lack the complexity of the native intestinal environment, limiting their utility in studying intestinal biology. Here, we present a detailed protocol for the set up and utilization of a three-dimensional (3D) in vitro bioreactor system for human intestinal studies and bacterial co-culture. This article outlines the design and assembly of the bioreactor system, scaffold fabrication, bacterial culture techniques, analysis methods, and troubleshooting tips. By providing step-by-step instructions, the goal is to enable other laboratories to utilize physiologically relevant tissue models of the human intestine, incorporating key features, such as nutrient flow, multiple human cell types, 3D architecture, and microbial communities. The incorporation of commensal bacteria into the bioreactor system allows for the investigation of complex host-microbe interactions, providing insight into gastrointestinal health and pathology. This article serves as a comprehensive resource for scientists seeking to advance their understanding of intestinal biology toward the development of novel therapeutic strategies for gastrointestinal disorders. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Scaffold design Basic Protocol 2: Intestinal cell culture: Caco2 cells Basic Protocol 3: Intestinal cell culture: organoids Basic Protocol 4: Bioreactor design and set up Basic Protocol 5: Bacteria in 3D bioreactor set up Basic Protocol 6: Bacteria and drug dosing.

Involvement of Intestinal Epithelium Aryl Hydrocarbon Receptor Expression and 3, 3'-Diindolylmethane in Colonic Tertiary Lymphoid Tissue Formation.

Tertiary lymphoid tissues (TLTs) are adaptive immune structures that develop during chronic inflammation and may worsen or lessen disease outcomes in a context-specific manner. Immune cell activity governing TLT formation in the intestines is dependent on immune cell aryl hydrocarbon receptor (AhR) activation. Homeostatic immune cell activity in the intestines is further dependent on ligand activation of AhR in intestinal epithelial cells (IECs), yet whether AhR activation and signaling in IECs influences the formation of TLTs in the presence of dietary AhR ligands is not known. To this end, we used IEC-specific AhR deletion coupled with a mouse model of dextran sodium sulfate (DSS)-induced colitis to understand how dietary AhR ligand 3, 3'-diindolylmethane (DIM) influenced TLT formation. DIM consumption increased the size of TLTs and decreased T-cell aggregation to TLT sites in an IEC-specific manner. In DSS-exposed female mice, DIM consumption increased the expression of genes implicated in TLT formation (Interleukin-22, Il-22; CXC motif chemokine ligand 13, CXCL13) in an IEC AhR-specific manner. Conversely, in female mice without DSS exposure, DIM significantly reduced the expression of Il-22 or CXCL13 in iAhRKO mice, but this effect was not observed in WT animals. Our findings suggest that DIM affects the immunological landscape of TLT formation during DSS-induced colitis in a manner contingent on AhR expression in IECs and biological sex. Further investigations into specific immune cell activity, IEC-specific AhR signaling pathways, and dietary AhR ligand-mediated effects on TLT formation are warranted.

Interaction between microRNA-195 and HuR regulates Paneth cell function in the intestinal epithelium by altering SOX9 translation.

Paneth cells at the bottom of small intestinal crypts secrete antimicrobial peptides, enzymes, and growth factors and contribute to pathogen clearance and maintenance of the stem cell niche. Loss of Paneth cells and their dysfunction occur commonly in various pathologies, but the mechanism underlying the control of Paneth cell function remains largely unknown. Here, we identified microRNA-195 (miR-195) as a repressor of Paneth cell development and activity by altering SOX9 translation via interaction with RNA-binding protein HuR. Tissue-specific transgenic expression of miR-195 (miR195-Tg) in the intestinal epithelium decreased the levels of mucosal SOX9 and reduced the numbers of lysozyme-positive (Paneth) cells in mice. Ectopically expressed SOX9 in the intestinal organoids derived from miR-195-Tg mice restored Paneth cell development ex vivo. miR-195 did not bind to Sox9 mRNA but it directly interacted with HuR and prevented HuR binding to Sox9 mRNA, thus inhibiting SOX9 translation. Intestinal mucosa from mice that harbored both Sox9 transgene and ablation of the HuR locus exhibited lower levels of SOX9 protein and Paneth cell numbers than those observed in miR-195-Tg mice. Inhibition of miR-195 activity by its specific antagomir improved Paneth cell function in HuR-deficient intestinal organoids. These results indicate that interaction of miR-195 with HuR regulates Paneth cell function by altering SOX9 translation in the small intestinal epithelium.NEW & NOTEWORTHY Our results indicate that intestinal epithelial tissue-specific transgenic miR-195 expression decreases the levels of SOX9 expression, along with reduced numbers of Paneth cells. Ectopically expressed SOX9 in the intestinal organoids derived from miR-195-Tg mice restores Paneth cell development ex vivo. miR-195 inhibits SOX9 translation by preventing binding of HuR to Sox9 mRNA. These findings suggest that interaction between miR-195 and HuR controls Paneth cell function via SOX9 in the intestinal epithelium.

Dihydromyricetin improves growth performance, immunity, and intestinal functions in weaned pigs challenged by enterotoxigenic Escherichia coli.

Enteric infection is a major cause of enteric disorder in neonatal pigs during the weaning transition. Dihydromyricetin (DMY) is a natural flavanonol compound extracted from Ampelopsis grossedentata with numerous biological activities such as antioxidative and immunomodulatory functions. The objective of this study was to investigate the effects of dietary dihydromyricetin supplementation on growth performance, immunity, and intestinal functions in weaned pigs challenged by enterotoxigenic Escherichia coli (ETEC). In total, 24 weaned DLY (Duroc × Landrace × Yorkshire) pigs were allotted to 3 treatments. Pigs fed with basal diet or basal diet containing 300 mg/kg DMY were orally infused with sterilized culture or ETEC (2.5 × 1011 colony-forming units). Dietary DMY supplementation significantly elevated the final weight and average daily gain (ADG) but reduced diarrhea incidence in the weaned pigs of the EDMY group compared to the pigs of the ECON group (p < 0.05). Compared to the ECON group, DMY also improved the digestibility of dry matter (DM), ether extract (EE), gross energy (GE), and ash of the EDMY group (p < 0.05). Moreover, DMY not only significantly decreased the ratio of albumin/globulin but also elevated serum concentrations of immunoglobulins (e.g., IgA and IgG) in the weaned pigs of the EDMY group compared to the pigs of the ECON group (p < 0.05). Interestingly, the villus height, the ratio of villus height to crypt depth (V:C), and the activities of mucosal alkaline phosphatase, sucrase, and maltase in the duodenum and jejunum of the EDMY group were higher than those in the ECON group (p < 0.05). Importantly, DMY significantly elevated the expression levels of jejunal zonula occludens-1 (ZO-1), claudin-1, cationic amino acid transporter-1 (CAT-1), and fatty acid transport protein-1 (FATP-1) in the weaned pigs of the EDMY group compared to the pigs of the ECON group (p < 0.05). Additionally, compared to the ECON group, DMY increased the concentrations of microbial SCFA metabolites (e.g., acetic acid and propanoic acid), but reduced the abundance of Escherichia coli in the cecum of the EDMY group (p < 0.05). Dietary DMY supplementation can attenuate the ETEC-induced growth retardation and intestinal injury, which was attributed to the amelioration of intestinal nutrient digestion and transport functions as well as the improved microbiota.

Tritrichomonas muris sensitizes the intestinal epithelium to doxorubicin-induced apoptosis.

Doxorubicin (DXR) is a widely used chemotherapy drug that can induce severe intestinal mucositis. While the influence of gut bacteria on DXR-induced damage has been documented, the role of eukaryotic commensals remains unexplored. We discovered Tritrichomonas muris (Tmu) in one of our mouse colonies exhibiting abnormal tuft cell hyperplasia, prompting an investigation into its impact on DXR-induced intestinal injury. Mice from Tmu-colonized and Tmu-excluded facilities were injected with DXR, and tissue morphology and gene expression were evaluated at acute injury (6 h) and peak regeneration (120 h) phases. Contrary to previous reports, DXR did not significantly alter villus height, crypt depth, or crypt density in any mice. However, we did observe apoptosis, measured by cleaved caspase 3 (CC3) staining, in intestinal crypts at 6 h post-DXR that was significantly higher in mice colonized by Tmu. Interestingly, while DXR did not alter the expression of active and facultative intestinal stem cell (ISC) marker genes in control mice, it significantly reduced their expression in Tmu + mice. Tmu, but not DXR, is also associated with increased inflammation and expression of the type 2 cytokines IL-5 and IL-13. However, pre-treatment of intestinal organoids with these cytokines is not sufficient to drive elevated DXR-induced apoptosis. These findings highlight the significant influence of commensal microbiota, particularly eukaryotic organisms like Tmu, on intestinal biology and response to chemotherapy, underscoring the complexity of gut microbiota interactions in drug-induced mucositis.

Protective Effect of Coated Benzoic Acid on Intestinal Epithelium in Weaned Pigs upon Enterotoxigenic Escherichia coli Challenge.

The study was designed to investigate the protective effect of dietary supplementation with coated benzoic acid (CBA) on intestinal barrier function in weaned pigs challenged with enterotoxigenic Escherichia coli (ETEC). Thirty-two pigs were randomized to four treatments and given either a basal diet or a basal diet supplemented with 3.0 g/kg CBA, followed by oral administration of ETEC or culture medium. The results showed that CBA supplementation increased the average daily weight gain (ADWG) in the ETEC-challenged pigs (p < 0.05). CBA also increased the serum activity of total superoxide dismutase (T-SOD) and the total antioxidant capacity (T-AOC), as it decreased the serum concentrations of endotoxin, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the ETEC-challenged pigs (p < 0.05). Interestingly, the CBA alleviated the ETEC-induced intestinal epithelial injury, as indicated by a reversal of the decrease in D-xylose absorption and a decrease in the serum levels of D-lactate and diamine oxidase (DAO) activity, as well as a decrease in the quantity of apoptotic cells in the jejunal epithelium following ETEC challenge (p < 0.05). Moreover, CBA supplementation significantly elevated the mucosal antioxidant capacity and increased the abundance of tight junction protein ZO-1 and the quantity of sIgA-positive cells in the jejunal epithelium (p < 0.05). Notably, CBA increased the expression levels of porcine beta defensin 2 (PBD2), PBD3, and nuclear factor erythroid-2 related factor 2 (Nrf-2), while downregulating the expression of toll-like receptor 4 (TLR4) in the jejunal mucosa (p < 0.05). Moreover, CBA decreased the expression levels of interleukin-1ß (IL-1ß), myeloid differentiation factor 88 (MyD88), and nuclear factor-kappa B (NF-κB) in the ileal mucosa upon ETEC challenge (p < 0.05). These results suggest that CBA may attenuate ETEC-induced damage to the intestinal epithelium, resulting in reduced inflammation, enhanced intestinal immunity and antioxidant capacity, and improved intestinal epithelial function.

Development of an intestinal mucosa ex vivo co-culture model to study viral infections.

Studying viral infections necessitates well-designed cell culture models to deepen our understanding of diseases and develop effective treatments. In this study, we present a readily available ex vivo 3D co-culture model replicating the human intestinal mucosa. The model combines fully differentiated human intestinal epithelium (HIE) with human monocyte-derived macrophages (hMDMs) and faithfully mirrors the in vivo structural and organizational properties of intestinal mucosal tissues. Specifically, it mimics the lamina propria, basement membrane, and the air-exposed epithelial layer, enabling the pioneering observation of macrophage migration through the tissue to the site of viral infection. In this study, we applied the HIE-hMDMs model for the first time in viral infection studies, infecting the model with two globally significant viruses: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human norovirus GII.4. The results demonstrate the model's capability to support the replication of both viruses and show the antiviral role of macrophages, determined by their migration to the infection site and subsequent direct contact with infected epithelial cells. In addition, we evaluated the production of cytokines and chemokines in the intestinal niche, observing an increased interleukin-8 production during infection. A parallel comparison using a classical in vitro cell line model comprising Caco-2 and THP-1 cells for SARS-CoV-2 experiments confirmed the utility of the HIE-hMDMs model in viral infection studies. Our data show that the ex vivo tissue models hold important implications for advances in virology research.IMPORTANCEThe fabrication of intricate ex vivo tissue models holds important implications for advances in virology research. The co-culture model presented here provides distinct spatial and functional attributes not found in simplified models, enabling the evaluation of macrophage dynamics under severe acute respiratory syndrome coronavirus 2 and human norovirus (HuNoV) infections in the intestine. Moreover, these models, comprised solely of primary cells, facilitate the study of difficult-to-replicate viruses such as HuNoV, which cannot be studied in cell line models, and offer the opportunity for personalized treatment evaluations using patient cells. Similar co-cultures have been established for the study of bacterial infections and different characteristics of the intestinal tissue. However, to the best of our knowledge, a similar intestinal model for the study of viral infections has not been published before.

Amelioration of Serum Aß Levels and Cognitive Impairment in APPPS1 Transgenic Mice Following Symbiotic Administration.

Alzheimer's disease (AD) is a neurodegenerative process responsible for almost 70% of all cases of dementia. The clinical signs consist in progressive and irreversible loss of memory, cognitive, and behavioral functions. The main histopathological hallmark is the accumulation of amyloid-ß (Aß) peptide fibrils in the brain. To date, the origin of Aß has not been determined. Recent studies have shown that the gut microbiota produces Aß, and dysbiotic states have been identified in AD patients and animal models of AD. Starting from the hypothesis that maintaining or restoring the microbiota's eubiosis is essential to control Aß's production and deposition in the brain, we used a mixture of probiotics and prebiotics (symbiotic) to treat APPPS1 male and female mice, an animal model of AD, from 2 to 8 months of age and evaluated their cognitive performances, mucus secretion, Aß serum concentration, and microbiota composition. The results showed that the treatment was able to prevent the memory deficits, the reduced mucus secretion, the increased Aß blood levels, and the imbalance in the gut microbiota found in APPPS1 mice. The present study demonstrates that the gut-brain axis plays a critical role in the genesis of cognitive impairment, and that modulation of the gut microbiota can ameliorate AD's symptomatology.

Metabolite-based inter-kingdom communication controls intestinal tissue recovery following chemotherapeutic injury.

Cytotoxic chemotherapies have devastating side effects, particularly within the gastrointestinal tract. Gastrointestinal toxicity includes the death and damage of the epithelium and an imbalance in the intestinal microbiota, otherwise known as dysbiosis. Whether dysbiosis is a direct contributor to tissue toxicity is a key area of focus. Here, from both mammalian and bacterial perspectives, we uncover an intestinal epithelial cell death-Enterobacteriaceae signaling axis that fuels dysbiosis. Specifically, our data demonstrate that chemotherapy-induced epithelial cell apoptosis and the purine-containing metabolites released from dying cells drive the inter-kingdom transcriptional re-wiring of the Enterobacteriaceae, including fundamental shifts in bacterial respiration and promotion of purine utilization-dependent expansion, which in turn delays the recovery of the intestinal tract. Inhibition of epithelial cell death or restriction of the Enterobacteriaceae to homeostatic levels reverses dysbiosis and improves intestinal recovery. These findings suggest that supportive therapies that maintain homeostatic levels of Enterobacteriaceae may be useful in resolving intestinal disease.

The Schema and Organization of the Cell: An Introduction to Ernst Brücke's Die Elementarorganismen (1861).

Ernst Brücke's 1861 essay Die Elementarorganismen has often been cited as a watershed in the history of physiology as well as in the history of cell theory. In its time it was widely read as a reform of animal cell theory, shifting the concept of the cell away from Schleiden and Schwann's original cell schema of a membranous vesicle with a nucleus, and towards the protoplasm theory that had developed in botany, centered on the cell's living contents. It was also notorious for its arguments against the necessity of both the nucleus and the cell membrane. An English translation of "The Elementary Organisms" is presented for the first time in this journal issue, with annotations and illustrations, https://doi.org/10.1007/s10739-024-09773-9 . Brücke's essay was not only an intervention into cell theory: historians can read it as a continuation of debates on the nature of the organism and theories of organization, and as an epistemological meditation on the microscope. In addition, although Brücke was known as a founder of the Berlin school of organic physics, "The Elementary Organisms" shows how he combined an avant-garde physicalist physiology with a much older tradition of comparative anatomy and physiology. The following introductory essay will provide a scientific biography of Ernst Brücke up to 1863, with background on debates on biological organization, cell theory, and muscle histology.

LncRNA Nostrill promotes interferon-γ-stimulated gene transcription and facilitates intestinal epithelial cell-intrinsic anti-Cryptosporidium defense.

Intestinal epithelial cells possess the requisite molecular machinery to initiate cell-intrinsic defensive responses against intracellular pathogens, including intracellular parasites. Interferons(IFNs) have been identified as cornerstones of epithelial cell-intrinsic defense against such pathogens in the gastrointestinal tract. Long non-coding RNAs (lncRNAs) are RNA transcripts (>200 nt) not translated into protein and represent a critical regulatory component of mucosal defense. We report here that lncRNA Nostrill facilitates IFN-γ-stimulated intestinal epithelial cell-intrinsic defense against infection by Cryptosporidium, an important opportunistic pathogen in AIDS patients and a common cause of diarrhea in young children. Nostrill promotes transcription of a panel of genes controlled by IFN-γ through facilitating Stat1 chromatin recruitment and thus, enhances expression of several genes associated with cell-intrinsic defense in intestinal epithelial cells in response to IFN-γ stimulation, including Igtp, iNos, and Gadd45g. Induction of Nostrill enhances IFN-γ-stimulated intestinal epithelial defense against Cryptosporidium infection, which is associated with an enhanced autophagy in intestinal epithelial cells. Our findings reveal that Nostrill enhances the transcription of a set of genes regulated by IFN-γ in intestinal epithelial cells. Moreover, induction of Nostrill facilitates the IFN-γ-mediated epithelial cell-intrinsic defense against cryptosporidial infections.

Bioaccessibility and Caco-2 cell uptake of iron chlorophyllin using a biologically relevant digestion model.

Iron deficiency remains a top nutrient deficiency worldwide. Iron chlorophyllin (IC), a compound structurally analogous to heme, utilizes the protoporphyrin ring of chlorophyll to bind iron. IC has previously been shown to deliver more iron to Caco-2 cells than FeSO4, the most common form prescribed for supplementation. However, previous test conditions used digestive conditions outside of those observed in humans. This study sought to assess IC bioaccessibility and Caco-2 cell uptake using physiologically relevant digestive solutions, pH, and incubation time, as compared to other iron sources (i.e., FeSO4, and hemoglobin (Hb)). Co-digestion with ascorbic acid (AA) and albumin was also investigated. Following gastric, duodenal, and jejunal digestion, IC-bound iron was less bioaccessible than iron delivered as FeSO4, and IC-bound iron was less bioaccessible than Hb-bound iron. IC-bound iron bioaccessibility was not affected by AA and was enhanced 2x when co-digested with a low dose of albumin. However, Caco-2 cell incubation with IC-containing digesta increased cell ferritin 2.5x more than FeSO4 alone, and less than Hb. IC with AA or with 400 mg albumin also increased cell ferritin more than IC alone, with the greatest increases observed following incubation of digesta containing IC + AA + 400 mg albumin. These results suggest IC can serve as an improved source of iron for supplementation as compared to FeSO4. These results also support further in vivo investigations of IC-based iron delivery in populations at risk of iron deficiency.