Surface area of the digestive tract - revisited

Intraluminal causes of mechanical small bowel obstruction: CT findings and diagnostic approach

Intraluminal causes of small bowel obstruction (SBO) are less common than mural or extrinsic etiologies. This review categorizes intraluminal causes of SBO into four broad categories to provide a diagnostic framework for radiologic interpretation: 1) ingested contents, 2) bowel stasis, 3) inflammatory causes, and 4) neoplasms. Ingested materials can result in SBO when individual or accumulated contents are too large to pass, such as in the case of foreign bodies or bezoars. Bowel stasis causing SBO can be secondary to abnormal bowel function, such as in cystic fibrosis, reduced transit of contents at sites of narrowing such as surgical anastomoses, or the formation of enteroliths in diverticula which may subsequently dislodge and result in luminal obstruction. Inflammatory causes of SBO include strictures or fistulas that allow foreign bodies (such as gallstones) formed outside the bowel to enter the bowel lumen and cause obstruction. Finally, neoplasms can present as endophytic masses that occlude the bowel lumen through a ball-valve mechanism or serve as a lead point for intussusception. Recognizing the imaging features that are suggestive of intraluminal SBO is critical for accurate diagnosis and timely patient care.

Cancer-associated fungi: An emerging powerful player in cancer immunotherapy

The role of the human microbiome in cancer has been extensively studied, focusing mainly on bacteria-host interactions and their impact on tumor development and treatment response. However, fungi, an immune-active component of the human microbiome, have received less attention regarding their roles in cancer. Recent studies have identified the widespread and specific colonization and distribution of fungi in multiple sites in patients across various cancer types. Importantly, host-fungal immune interactions significantly influence immune regulation within the tumor microenvironment. The rapid advancement of immune-checkpoint blockade (ICB)-based cancer immunotherapy creates an urgent need for effective biomarkers and synergistic therapeutic targets. Cancer-associated fungi and their associated antifungal immunity demonstrate significant potential and efficacy in enhancing cancer immunotherapy. This review summarizes and discusses the growing evidence of the functions and mechanisms of commensal and pathogenic cancer-associated fungi in cancer immunotherapy. Additionally, we emphasize the potential of fungi as predictive biomarkers and therapeutic targets in cancer immunotherapy.

Comparative analysis of Caco-2 cells and human jejunal and duodenal enteroid-derived cells in gel- and membrane-based barrier models of intestinal permeability

Intestinal absorption is a key toxicokinetics parameter. Although the colon carcinoma cell line Caco-2 is the most used in vitro model to estimate human drug absorption, models representing other intestinal segments are available. We characterized the morphology, tissue-specific markers, and functionality of 3 human intestinal cell types: Caco-2, primary human enteroid-derived cells from jejunum (J2), and duodenum (D109) when cultured in the OrganoPlate 3-lane 40 microphysiological system (MPS) or static 24-well Transwells. In both conditions, J2 and D109 formed dome-like structures; Caco-2 formed uniform monolayers. In MPS, only Caco-2 formed tubules. Cells grown on Transwells formed a thicker monolayer. All cells and conditions exhibited expression of ZO-1 (tight junctions). Polarization markers Ezrin and Villin were highest in J2 and D109 in MPS, highest expression of Mucin was observed with J2. However, J2 and D109 exhibited poor barrier (70 kDa TRITC-dextran) in MPS, whereas robust barrier was recorded in Transwells. Barrier function and drug transport were evaluated using caffeine, indomethacin, and propranolol. The gel lane in MPS acted as a blockade; only a small fraction crossed, even without cells. The permeability ratios were used to parameterize the probabilistic compartmental absorption model to determine whether in vitro data could reduce uncertainty. The most accurate prediction of the fraction absorbed was achieved with Transwell-derived data from Caco-2, combined with the experimentally derived segment-specific absorption ratios. The impact of this study includes demonstration that enteroid-derived cells cultured in MPS show most physiological morphology, but that studies of drug permeability in this MPS are challenging.

Investigating accumulation of budesonide and tacrolimus in an ex vivo porcine oesophageal model: Translational potential for local application of drugs to treat eosinophilic oesophagitis

Eosinophilic oesophagitis (EoE) is a chronic inflammatory disease afflicting the oesophagus and causing lifelong morbidity. Over the last few decades, EoE has significantly increased in prevalence with oral corticosteroids, such as budesonide, being the current mainstay of therapy. Tacrolimus is an immunomodulatory drug with anti-inflammation properties that is not on the conventional therapeutic regimen for EoE but offers a promising alternative non-steroidal treatment for patients who do not respond to diet elimination, proton pump inhibitors (PPIs), or corticosteroids. This study aims to investigate and compare the accumulation between locally delivered budesonide and tacrolimus, using an ex vivo porcine oesophageal model of EoE, over a range of contact times up to 30 min. Budesonide and tacrolimus were solubilised in a cosolvent and surfactant formulation to maintain solvation capacity in artificial saliva. Injured and non-injured (control) porcine oesophageal mucosa were used as surrogates to represent EoE and healthy oesophageal mucosa in humans, respectively, due to the highly similar physiological architecture of the oesophagus. EoE-mimicking oesophageal damage was chemically induced by pancreatic enzymes and bile salts known to dilate intercellular spaces typically observed in EoE pathophysiology where tight junction damage was represented by an irreversible drop in transepithelial electrical resistance (TEER). Whole tissue and basolateral accumulation of budesonide and tacrolimus were quantified after 30 min using liquid chromatography tandem mass spectrometry (LC-MS/MS). Tacrolimus yielded a significant increase (p < 0.05) in injured tissue accumulation (approximately two-fold) in comparison to non-injured tissue, while budesonide yielded no significant difference (p > 0.05) in tissue accumulation between the two. Considering the significant accumulation of tacrolimus in this ex vivo porcine model of EoE, using injury-induced porcine oesophageal mucosa, this study suggests the use of tacrolimus as a targeted local therapy for the treatment of EoE.

A Postbiotic Derived from Lactobacillaceae Protects Intestinal Barrier Function in a Challenge Model Using Colon Organoid Tubules

Postbiotics may help strengthen intestinal barrier function. This study assessed the effects of a postbiotic derived from Limosilactobacillus fermentum and Lactobacillus delbrueckii subsp. lactis on epithelial barrier and cytokine production. Human-derived colon tubules were cultured on chips for 15 days. On day 8, the epithelial barrier was disrupted with 0.7 μM afatinib. Postbiotic doses of 5, 10, or 20 mg/mL were added on days 6, 8, 11, and 13. Trans-epithelial electrical resistance (TEER) was measured on days 6, 8, 11, 13, and 15, along with phase contrast imaging. Cytokine levels were measured on day 13. All three postbiotic concentrations resulted in better TEER recovery on day 15 vs. the control (p < 0.001). On day 13, 10 and 20 mg/mL increased TEER (p < 0.001), but only 20 mg/mL did on day 11 (p < 0.05). Phase imaging confirmed the dose-dependent effect. The 20 mg/mL dose more effectively reduced CCL2, CX3CL1, CXCL1, CXCL5, IL-8, IL-11, and IL-4 than the other doses (p < 0.01), and 10 mg/mL more effectively reduced CCL2, CXCL1, CXCL10, IL-10, IL-11, and IL-23 than 5 mg/mL (p < 0.01). In a colonic organoid model, the Lactobacillaceae-derived postbiotic prevented drug-induced epithelial damage, enhanced recovery, and modulated cytokine secretion towards a more anti-inflammatory profile in a dose-dependent manner.

Gut integrity in intensive care: alterations in host permeability and the microbiome as potential therapeutic targets

BACKGROUND

The gut has long been hypothesized to be the "motor" of critical illness, propagating inflammation and playing a key role in multiple organ dysfunction. However, the exact mechanisms through which impaired gut integrity potentially contribute to worsened clinical outcome remain to be elucidated. Critical elements of gut dysregulation including intestinal hyperpermeability and a perturbed microbiome are now recognized as potential therapeutic targets in critical care.

MAIN BODY

The gut is a finely tuned ecosystem comprising ~ 40 trillion microorganisms, a single cell layer intestinal epithelia that separates the host from the microbiome and its products, and the mucosal immune system that actively communicates in a bidirectional manner. Under basal conditions, these elements cooperate to maintain a finely balanced homeostasis benefitting both the host and its internal microbial community. Tight junctions between adjacent epithelial cells selectively transport essential molecules while preventing translocation of pathogens. However, critical illness disrupts gut barrier function leading to increased gut permeability, epithelial apoptosis, and immune activation. This disruption is further exacerbated by a shift in the microbiome toward a "pathobiome" dominated by pathogenic microbes with increased expression of virulence factors, which intensifies systemic inflammation and accelerates organ dysfunction. Research has highlighted several potential therapeutic targets to restore gut integrity in the host, including the regulation of epithelial cell function, modulation of tight junction proteins, and inhibition of epithelial apoptosis. Additionally, microbiome-targeted therapies, such as prebiotics, probiotics, fecal microbiota transplantation, and selective decontamination of the digestive tract have also been extensively investigated to promote restoration of gut homeostasis in critically ill patients. Future research is needed to validate the potential efficacy of these interventions in clinical settings and to determine if the gut can be targeted in an individualized fashion.

CONCLUSION

Increased gut permeability and a disrupted microbiome are common in critical illness, potentially driving dysregulated systemic inflammation and organ dysfunction. Therapeutic strategies to modulate gut permeability and restore the composition of microbiome hold promise as novel treatments for critically ill patients.

Advances in intestinal epithelium and gut microbiota interaction

The intestinal epithelium represents a critical interface between the host and external environment, serving as the second largest surface area in the human body after the lungs. This dynamic barrier is sustained by specialized epithelial cell types and their complex interactions with the gut microbiota. This review comprehensively examines the recent advances in understanding the bidirectional communication between intestinal epithelial cells and the microbiome. We briefly highlight the role of various intestinal epithelial cell types, such as Paneth cells, goblet cells, and enteroendocrine cells, in maintaining intestinal homeostasis and barrier function. Gut microbiota-derived metabolites, particularly short-chain fatty acids and bile acids, influence epithelial cell function and intestinal barrier integrity. Additionally, we highlight emerging evidence of the sophisticated cooperation between different epithelial cell types, with special emphasis on the interaction between tuft cells and Paneth cells in maintaining microbial balance. Understanding these complex interactions has important implications for developing targeted therapeutic strategies for various gastrointestinal disorders, including inflammatory bowel disease, metabolic disorders, and colorectal cancer.

NapBiome trial: Targeting gut microbiota to improve sleep rhythm and developmental and behavioural outcomes in early childhood in a birth cohort in Switzerland - a study protocol

INTRODUCTION

The gut-brain axis plays a crucial role in the regulation and development of psychological and physical processes. The first year of life is a critical period for the development of the gut microbiome, which parallels important milestones in establishing sleep rhythm and brain development. Growing evidence suggests that the gut microbiome influences sleep, cognition and early neurodevelopment. For term-born and preterm-born infants, difficulties in sleep regulation may have consequences on health. Identifying effective interventions on the gut-brain axis in early life is likely to have long-term implications for the health and development of at-risk infants.

METHODS AND ANALYSES

In this multicentre, four-group, double-blinded, placebo (PLC)-controlled randomised trial with a factorial design, 120 preterm-born and 260 term-born infants will be included. The study will investigate whether the administration of daily synbiotics or PLC for a duration of 3 months improves sleep patterns and neurodevelopmental outcomes up to 2 years of age. The trial will also: (1) determine the association between gut microbiota, sleep patterns and health outcomes in children up to 2 years of age; and (2) leverage the interactions between gut microbiota, brain and sleep to develop new intervention strategies for at-risk infants.

ETHICS AND DISSEMINATION

The NapBiome trial has received ethical approval by the Committee of Northwestern and Central Switzerland and Canton Vaud, Switzerland (#2024-01681). Outcomes will be disseminated through publication and will be presented at scientific conferences. Metagenomic data will be shared through the European Nucleotide Archive.

TRIAL REGISTRATION NUMBER

The US National Institutes of Health NCT06396689.

Meta-Analysis of Permeability Literature Data Shows Possibilities and Limitations of Popular Methods

Permeability is an important molecular property in drug discovery, as it co-determines pharmacokinetics whenever a drug crosses the phospholipid bilayer, e.g., into the cell, in the gastrointestinal tract, or across the blood-brain barrier. Many methods for the determination of permeability have been developed, including cell line assays (CACO-2 and MDCK), cell-free model systems like parallel artificial membrane permeability assay (PAMPA) mimicking, e.g., gastrointestinal epithelia or the skin, as well as the black lipid membrane (BLM) and submicrometer liposomes. Furthermore, many in silico approaches have been developed for permeability prediction: meta-analysis of publicly available databases for permeability data (MolMeDB and ChEMBL) was performed to establish their usability. Four experimental and two computational methods were evaluated. It was shown that repeatability of the reported permeability measurement is not great even for the same method. For the PAMPA method, two different permeabilities are reported: intrinsic and apparent. They can vary in degrees of magnitude; thus, we suggest being extra cautious using literature data on permeability. When we compared data for the same molecules using different methods, the best agreement was between cell-based methods and between BLM and computational methods. Existence of unstirred water layer (UWL) permeability limits the data agreement between cell-based methods (and apparent PAMPA) with data that are not limited by UWL permeability (computational methods, BLM, intrinsic PAMPA). Therefore, different methods have different limitations. Cell-based methods provide results only in a small range of permeabilities (-8 to -4 in cm/s), and computational methods can predict a wider range of permeabilities beyond physical limitations, but their precision is therefore limited. BLM with liposomes can be used for both fast and slow permeating molecules, but its usage is more complicated than standard transwell techniques. To sum up, when working with in-house measured or published permeability data, we recommend caution in interpreting and combining them.

Role of Intestinal Barrier Disruption to Acute-on-Chronic Liver Failure

Acute-on-chronic liver failure (ACLF) is a severe condition in patients with decompensated liver cirrhosis, marked by high short-term mortality. Recent experimental and clinical evidence has linked intestinal dysfunction to both the initiation of ACLF as well as disease outcome. This review discusses the significant role of the gut-liver axis in ACLF pathogenesis, highlighting recent advances. Gut mucosal barrier disruption, gut dysbiosis, and bacterial translocation emerge as key factors contributing to systemic inflammation in ACLF. Different approaches of therapeutically targeting the gut-liver axis via farnesoid X receptor agonists, nonselective beta receptor blockers, antibiotics, and probiotics are discussed as potential strategies mitigating ACLF progression. The importance of understanding the distinct pathophysiology of ACLF compared with other stages of liver cirrhosis is highlighted. In conclusion, research findings suggest that disruption of intestinal integrity may be an integral component of ACLF pathogenesis, paving the way for novel diagnostic and therapeutic approaches to manage this syndrome more effectively.

Intestinal Permeability in Disorders of Gut-Brain Interaction: From Bench to Bedside

Intestinal barrier function lies at a critical interface of a range of peripheral and central processes that influence disorders of gut-brain interactions (DGBI). Although rigorously tested, the role of barrier dysfunction in driving clinical phenotype of DGBI remains to be fully elucidated. In vitro, in vivo, and ex vivo strategies can test various aspects of the broader permeability and barrier mechanisms in the gut. Luminal mediators of host, bacterial, and dietary origin can influence the barrier function and a disrupted barrier can also influence the luminal milieu. Critical to our understanding is how barrier dysfunction is influenced by stress and other comorbidities that associate with DGBI and the crosstalk between barrier and neural, hormonal, and immune responses. Additionally, the microbiome's significant role in the communication between the brain and gut has led to the integrative model of a microbiome gut-brain axis with reciprocal interactions between brain networks and networks composed of multiple cells in the gut, including immune cells, enterochromaffin cells, gut microbiota and the derived luminal mediators. This review highlights the techniques for assessment of barrier function, appraises evidence for barrier dysfunction in DGBI including mechanistic studies in humans, as well as provides an overview of therapeutic strategies that can be used to directly or indirectly restore barrier function in DGBI patients.

Intestinal Microbiota Dysbiosis Role and Bacterial Translocation as a Factor for Septic Risk

The human immune system is closely linked to microbiota such as a complex symbiotic relationship during the coevolution of vertebrates and microorganisms. The transfer of microorganisms from the mother's microbiota to the newborn begins before birth during gestation and is considered the initial phase of the intestinal microbiota (IM). The gut is an important site where microorganisms can establish colonies. The IM contains polymicrobial communities, which show complex interactions with diet and host immunity. The tendency towards dysbiosis of the intestinal microbiota is influenced by local but also extra-intestinal factors such as inflammatory processes, infections, or a septic state that can aggravate it. Pathogens could trigger an immune response, such as proinflammatory responses. In addition, changes in the host immune system also influence the intestinal community and structure with additional translocation of pathogenic and non-pathogenic bacteria. Finally, local intestinal inflammation has been found to be an important factor in the growth of pathogenic microorganisms, particularly in its role in sepsis. The aim of this article is to be able to detect the current knowledge of the mechanisms that can lead to dysbiosis of the intestinal microbiota and that can cause bacterial translocation with a risk of infection or septic state and vice versa.

An oral liraglutide nanomicelle formulation conferring reduced insulin-resistance and long-term hypoglycemic and lipid metabolic benefits

Type 2 diabetes is a chronic disease characterized by insulin resistance and often worsened by obesity. Effective management involves the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) to assist with glycemic control and weight management. However, these drugs must be administered subcutaneously due to their low oral bioavailability. We developed an oral liraglutide (LRG) formulation by electrostatic complexation of GLP-1 RA with bile acid derivatives and nanomicelle (NM) formation, with non-ionic surfactant n-dodecyl-β-d-maltoside (DDM). The optimized formulation, LDD[1:2:4]-NM, had a mean particle size of 75.9 ± 5.60 nm and a permeability 1347 % higher than that of unformulated LRG when tested in Caco-2/HT29-MTX-E12 cell monolayers. In rats, oral bioavailability was 4.63-fold higher than that of unformulated LRG (1.11 ± 0.20 % vs. 5.14 ± 0.63 %). The absorption mechanism included clathrin-mediated endocytosis, macropinocytosis, and an ASBT-mediated pathway. A 12-week oral treatment consisting of a daily dose of 20 mg LDD[1:2:4]-NM/kg significantly reduced glycohemoglobin levels, a marker of diabetic control, and the HOMA-IR index, a marker of insulin resistance. The weight of epididymal and inguinal white adipose tissue and brown adipose tissue (BAT) was also reduced. Moreover, LDD[1:2:4]-NM had a greater impact on BAT activation, pro-inflammatory gene expression, and lipid metabolism than subcutaneous LRG. This study showed that an oral NM formulation can efficiently deliver LRG. Long-term treatment led to improved hyperglycemic effects, insulin resistance, and modulated lipid metabolism. LDD[1:2:4]-NM is thus a promising oral therapeutic option for the management of type 2 diabetes, potentially transforming treatment paradigms based on the availability of a more convenient administration route.

Osmoregulation affects elimination of microplastics in fish in freshwater and marine environments

In recent decades, microplastics (MPs) have emerged as one of the biggest environmental challenges in aquatic environments. Ingestion and toxicity of MPs in seawater (SW) and freshwater (FW) fish have been studied extensively both in field and laboratory settings. However, the basic mechanism of how fish deal with MPs in SW and FW remains unclear, although physiological conditions of fish differ significantly in the two environments. In this study, using Javanese medaka (Oryzias javanicus), a euryhaline fish that adapts readily to both SW and FW, we investigated elimination of MPs in fish in SW and FW environments. We exposed O. javanicus larvae (21 days post-hatching) to 0.25 mg/L of fluorescent polystyrene microspheres (1 μm) for 24 hours and then conducted an elimination test for up to 5 days. Results showed that the gut retention time of MPs is longer in FW than in SW, indicating that MP elimination occurs more quickly in SW than in FW. However, higher numbers of MPs tended to be retained longer in SW larvae than FW larvae. Subsequently, using a fluorescent marker, gastrointestinal fluid was found to move more rapidly in the SW group. This finding indicates that water drinking accelerates gastrointestinal fluid movement, which moves MPs through the gut in SW larvae. Beside the difference in physiological conditions, MP elimination was faster when food was available, suggesting that feeding also affects MP elimination in fish. Internal factors such as body size and intestine length were also examined, but indicated no significant difference. Therefore, osmoregulation and feeding both influence MP elimination in fish.

Development of Sheep Intestinal Organoids for Studying Deoxynivalenol-Induced Toxicity

Sheep are an important livestock species whose gastrointestinal tract is essential for overall health. Feed contaminants such as bacterial toxins and mycotoxins severely damage the sheep intestine, yet the mechanisms remain mostly elusive partially due to the lack of physiologically relevant in vitro models. Here, we investigated molecular mechanisms underlying deoxynivalenol (DON)-induced toxicity by developing intestinal organoids from isolated intestinal crypts of Hu sheep. The organoids had a central lumen and monolayer epithelium, and could be continuously passaged, cryopreserved, and resuscitated. Histological and transcriptomic analysis showed that the intestinal organoids recapitulate the cell lineages and gene expression characteristics of the original intestinal tissues. Statistical analysis indicated that DON exposure significantly inhibited organoid formation efficiency, as well as the proliferation and activity of intestinal organoid cells. RNA-seq and Western blotting analysis further revealed that DON exposure induces intestinal toxicity by inhibiting the PI3K/AKT/GSK3β/β-catenin signaling pathway. Our study provides a novel example of organoid application in toxicity studies and reveals the signaling pathway involved in DON-induced toxicity in sheep, which is of great significance for improving mitigation strategies for DON.

The Gut-Brain Axis in Parkinson's Disease

Parkinson's disease (PD) involves both the central nervous system (CNS) and enteric nervous system (ENS), and their interaction is important for understanding both the clinical manifestations of the disease and the underlying disease pathophysiology. Although the neuroanatomical distribution of pathology strongly suggests that the ENS is involved in disease pathophysiology, there are significant gaps in knowledge about the underlying mechanisms. In this article, we review the clinical presentation and management of gastrointestinal dysfunction in PD. In addition, we discuss the current understanding of disease pathophysiology in the gut, including controversies about early involvement of the gut in disease pathogenesis. We also review current knowledge about gut α-synuclein and the microbiome, discuss experimental models of PD-linked gastrointestinal pathophysiology, and highlight areas for further research. Finally, we discuss opportunities to use the gut-brain axis for the development of biomarkers and disease-modifying treatments.

Development of Novel Oral Delivery Systems Using Additive Manufacturing Technologies to Overcome Biopharmaceutical Challenges for Future Targeted Drug Delivery

Background/Objectives: The development of targeted drug delivery systems for active pharmaceutical ingredients with narrow absorption windows is crucial for improving their bioavailability. This study proposes a novel 3D-printed expandable drug delivery system designed to precisely administer drugs to the upper small intestine, where absorption is most efficient. The aim was to design, prototype, and evaluate the system's functionality for organ retention and targeted drug release. Methods: The system was created using 3D printing technologies, specifically FDM and SLA, with materials such as PLA and HPMC. The device was composed of matrices and springs, with different spring geometries (diameter, coil number, and cross-sectional shape) being tested for strength and flexibility. A gastro-resistant string was used to maintain the device in a compact configuration until it reached the neutral pH environment of the small intestine, where the string dissolved. The mechanical performance of the springs was evaluated using a texture analyzer, and the ability of the system to expand upon pH change was tested in simulated gastrointestinal conditions. Results: The results demonstrated that the system remained in the space-saving configuration for two hours under acidic conditions. Upon a pH change to 6.8, the system expanded as expected, with opening times of 5.5 ± 1.2 min for smaller springs and 2.5 ± 0.3 min for larger springs. The device was able to regain its expanded state, suggesting its potential for controlled drug release in the small intestine. Conclusions: This prototype represents a promising approach for targeted drug delivery to the upper small intestine, offering a potential alternative for drugs with narrow absorption windows. While the results are promising, further in vivo studies are necessary to assess the system's clinical potential and mechanical stability in real gastrointestinal conditions.

Characteristics and prognosis of small bowel tumors: A retrospective study

BACKGROUND

Small bowel tumors (SBTs) are a heterogeneous group of difficult-to-diagnose tumors that account for 2%-5% of all gastrointestinal tumors. Single-balloon enteroscopy greatly enhances the diagnosis and treatment of SBTs. However, few epidemiological studies have been conducted in Taiwan to determine the clinical profile of SBTs.

AIM

To investigate the clinical characteristics, managements and prognosis of SBTs in a medical center in Taiwan.

METHODS

The study enrolled 51 patients aged 58.9 ± 8.8 years (range, 22-93) diagnosed with SBTs from November 2009 to July 2021. We retrospectively recorded clinical characteristics, indications, endoscopic findings, pathological results, management, and outcomes for further analysis.

RESULTS

A male preponderance was observed (56.8%). The most common indications were suspected small intestinal tumors (52.9%) and obscure gastrointestinal bleeding (39.2%). The most common tumor location was the ileum (41.2%). The performance of imaging studies (P = 0.004) and the types of findings (P = 0.005) differed significantly between malignant and benign SBTs. The most frequent imaging finding was a small intestinal mass (43.1%). The top three malignant tumor types were gastrointestinal stromal tumors (GISTs), adenocarcinomas, and lymphomas. Moreover, the proportions of benign and malignant tumors were 27.5% and 72.5%, respectively. The survival rates of patients with malignant tumors in the GIST and non-GIST groups differed significantly (P = 0.015). Kaplan-Meier survival analysis showed a significant difference in survival between patients in the malignant and benign groups (P = 0.04). All patients with lymphoma underwent chemotherapy (n = 7/8, 87.5%), whereas most patients with GISTs underwent surgery (n = 13/14, 92.8%).

CONCLUSION

Patients with GISTs have a significantly higher survival rate than those with other malignant SBTs. Therefore, a large-scale nationwide study is warranted to evaluate the population-based epidemiology of SBTs.

Gut dysbiosis mediates the association between antibiotic exposure and chronic disease

Antibiotics are safe, effective drugs and continue to save millions of lives and prevent long-term illness worldwide. A large body of epidemiological, interventional and experimental evidence shows that exposure to antibiotics has long-term negative effects on human health. We reviewed the literature data on the links between antibiotic exposure, gut dysbiosis, and chronic disease (notably with regard to the "developmental origins of health and disease" ("DOHaD") approach). Molecular biology studies show that the systemic administration of antibiotic to infants has a rapid onset but also often a long-lasting impact on the microbial composition of the gut. Along with other environmental factors (e.g., an unhealthy "Western" diet and sedentary behavior), antibiotics induce gut dysbiosis, which can be defined as the disruption of a previously stable, functionally complete microbiota. Gut dysbiosis many harmful long-term effects on health. Associations between early-life exposure to antibiotics have been reported for chronic diseases, including inflammatory bowel disease, celiac disease, some cancers, metabolic diseases (obesity and type 2 diabetes), allergic diseases, autoimmune disorders, atherosclerosis, arthritis, and neurodevelopmental, neurodegenerative and other neurological diseases. In mechanistic terms, gut dysbiosis influences chronic disease through direct effects on mucosal immune and inflammatory pathways, plus a wide array of direct or indirect effects of short-chain fatty acids, the enteric nervous system, peristaltic motility, the production of hormones and neurotransmitters, and the loss of intestinal barrier integrity (notably with leakage of the pro-inflammatory endotoxin lipopolysaccharide into the circulation). To mitigate dysbiosis, the administration of probiotics in patients with chronic disease is often (but not always) associated with positive effects on clinical markers (e.g., disease scores) and biomarkers of inflammation and immune activation. Meta-analyses are complicated by differences in probiotic composition, dose level, and treatment duration, and large, randomized, controlled clinical trials are lacking in many disease areas. In view of the critical importance of deciding whether or not to prescribe antibiotics (especially to children), we suggest that the DOHaD concept can be logically extended to "gastrointestinal origins of health and disease" ("GOHaD") or even "microbiotic origins of health and disease" ("MOHaD").

Assessing nanotoxicity of food-relevant particles: A comparative analysis of cellular responses in cell monolayers versus 3D gut epithelial cultures

Engineered nanoparticles (NPs) are extensively used in the food industry, yet safety concerns remain. The lack of validated methodologies is a bottleneck towards resolving this uncertainty. Hence, the current study aims to compare two cell models by examining the toxicological impacts of two food-relevant NPs (SiO2 and Ag) on intestinal epithelia using monolayer Caco-2 cells and full-thickness 3D tissue models of human small intestines (EpiIntestinal™). Comprehensive characterization and dosimetric analysis of the NPs were performed to determine effective doses and model realistic exposures. Neither genotoxicity nor cytotoxicity were detected in the 3D tissues after NP treatment, while the 2D cultures exhibited cytotoxic response from Ag NP treatment for 24 h at 1 μg/ml. Hyperspectral imaging and transmission electron microscopy confirmed uptake of both NPs by cells in both 2D and 3D culture models. Ag NPs caused an increase in autophagy, whereas SiO2 NPs induced increased cytoplasmic vacuolization. Based on realistic exposure levels studied, the 3D small intestinal tissue model was found to be more resilient to NP treatment compared to 2D cell monolayers. This comparative approach towards toxicological assessment of food relevant NPs could be used as a framework for future analysis of NP behavior and nanotoxicity in the gut.

Enteroendocrine cells regulate intestinal homeostasis and epithelial function

Enteroendocrine cells (EECs) are well-known for their systemic hormonal effects, especially in the regulation of appetite and glycemia. Much less is known about how the products made by EECs regulate their local environment within the intestine. Here, we focus on paracrine interactions between EECs and other intestinal cells as they regulate three essential aspects of intestinal homeostasis and physiology: 1) intestinal stem cell function and proliferation; 2) nutrient absorption; and 3) mucosal barrier function. We also discuss the ability of EECs to express multiple hormones, describe in vitro and in vivo models to study EECs, and consider how EECs are altered in GI disease.

Understanding of formation, gastrointestinal breakdown, and application of whey protein emulsion gels: Insights from intermolecular interactions

Whey protein emulsion gel is an ideal model food for revealing how the multilength scale food structures affect food digestion, as their structure and mechanical properties can be precisely manipulated by controlling the type and intensity of intermolecular interactions between protein molecules. However, there are still significant understanding gaps among intermolecular interactions, protein aggregation and gelation, emulsion gel formation, gel breakdown in the gastrointestinal tract (GIT), and the practical use of whey protein emulsion gels, which limits their GIT-targeted applications. In this regard, the relationship between the structure and digestion behavior of heat-set whey protein emulsion gels is reviewed and discussed mainly from the following aspects: (1) structural characteristics of whey protein molecules; (2) how different types of intermolecular interactions influence heat-induced aggregation and gelation of whey protein in the aqueous solutions and the oil-in-water emulsions, and the mechanical properties of the final gels; (3) functions of the mouth, the stomach, and the small intestine in processing of solid foods, and how different types of intermolecular interactions influence the breakdown properties of heat-set whey protein emulsion gels in GIT (i.e., their respective role in controlling gel digestion). Finally, the implications of knowledge derived from the formation and gastrointestinal breakdown of heat-set whey protein emulsion gels for developing controlled delivery vehicles, human satiety enhancers, and sensory modifiers are highlighted.

Dectin-1 as a therapeutic target for inflammatory bowel disease

Inflammatory bowel disease (IBD) encompasses chronic inflammatory conditions of the distal gastrointestinal tract, including Crohn's disease and ulcerative colitis. This chapter explores the potential of Dendritic cell-associated C-type lectin-1 (Dectin-1), a pattern recognition receptor, as a therapeutic target for IBD. We delve into the multifaceted roles of Dectin-1 in immune response modulation, focusing on its interactions with the gut microbiota and immune system. Key sections include an examination of intestinal dysbiosis and its impact on IBD, highlighting the critical role of fungal dysbiosis and immune responses mediated by Dectin-1. The chapter discusses the dual functions of Dectin-1 in maintaining gut homeostasis and its contribution to disease pathogenesis through interactions with the gut's fungal community. Furthermore, the genetic and molecular mechanisms underpinning Dectin-1's role in IBD susceptibility are explored, alongside its signaling pathways and their effects on immune modulation. We also present therapeutic strategies targeting Dectin-1, including innovative drug delivery systems that leverage its natural binding affinity for β-glucans, enhancing targeted delivery to inflamed tissues. The chapter underscores the potential of dietary modulation of Dectin-1 pathways to restore gut microbiota balance and suggests future research directions to fully exploit Dectin-1's therapeutic potential in managing IBD. By elucidating the complex interplay between Dectin-1 and the gut microbiota, this chapter provides insights into novel therapeutic approaches aimed at mitigating IBD symptoms and improving patient outcomes.

The biogeography of the mucosa-associated microbiome in health and disease

Introduction

Little is known about the biogeography of the mucosa associated microbiome (MAM) in patients with inflammatory bowel disease (IBD) versus controls in different segments of the gastrointestinal tract, as well as the links between the MAM, gastrointestinal symptoms, and use of proton pump inhibitors (PPI).

Methods

We recruited 59 controls (without structural abnormalities and gastrointestinal symptoms), 44 patients with ulcerative colitis (UC) and 31 with Crohn's disease (CD). Biopsies from various segments of the upper and lower gastrointestinal tract were collected. Microbial composition was assessed via 16S rRNA gene amplicon analysis and the bacterial load of the mucosal biopsies were assessed via qPCR. The MAM was examined in the context of disease status, PPI usage, the severity of gastrointestinal symptoms, and the symptom response to a standardised nutrient challenge (SNC).

Results

Microbial communities of the MAM in the upper and lower gastrointestinal tract differed. IBD patients were characterised by relative and absolute depletion of numerous genera known to produce butyrate and/or propionate, with the largest differentiation being the depletion of Faecalibacterium in the lower gastrointestinal tract of CD patients. Notably, PPI users exhibited an enrichment of Faecalibacterium in the lower gastrointestinal tract. The severity of gastrointestinal symptoms, as well as the symptom response to the SNC, were significantly associated with MAM composition in the gastrointestinal tract.

Conclusion

The absolute and relative composition of the MAM is variable across different segments of the gastrointestinal tract. These quantitative changes indicates that MAM can be targeted in specific segments of the GI tract to improve patient outcomes.

Understanding neurotropic enteric viruses: routes of infection and mechanisms of attenuation

The intricate connection between the gut and the brain involves multiple routes. Several viral families begin their infection cycle in the intestinal tract. However, amongst the long list of viral intestinal pathogens, picornaviruses, and astroviruses stand out for their ability to transition from the intestinal epithelia to central or peripheral nervous system cells. In immunocompromised, neonates and young children, these viral infections can manifest as severe diseases, such as encephalitis, meningitis, and acute flaccid paralysis. What confers this remarkable plasticity and makes them efficient in infecting cells of the gut and the brain axes? Here, we review the current understanding of the virus infection along the gut-brain axis for some enteric viruses and discuss the molecular mechanisms of their attenuation.

Colon or semicolon: gut sampling microdevices for omics insights

Ingestible microdevices represent a breakthrough in non-invasive sampling of the human gastrointestinal (GI) tract. By capturing the native spatiotemporal microbiome and intricate biochemical gradients, these devices allow a non-invasive multi-omic access to the unperturbed host-microbiota crosstalk, immune/nutritional landscapes and gut-organ connections. We present the current progress of GI sampling microdevices towards personalized metabolism and fostering collaboration among clinicians, engineers, and data scientists.

Interleukin-22 Promotes Cell Proliferation to Combat Virus Infection in Human Intestinal Epithelial Cells

Interferon lambdas (IFN-λs) are crucial to control virus infections at mucosal surfaces. Interleukin-22 (IL-22) was reported to help IFN-λ control rotavirus infection in the intestinal epithelium of mice either by aiding in the induction of interferon-stimulated genes (ISGs) or by increasing cell proliferation thereby clearing virally infected cells. We investigated whether IL-22 and IFN-λs exhibit similar synergistic effects in human intestinal epithelial cells (IECs) models. Our results showed that co-treatment of IL-22 and IFN-λ induced more phosphorylation of STAT1 than either cytokine used alone. However, this increased STAT1 activation did not translate to increased ISGs production or antiviral protection. Transcriptomics analysis revealed that despite sharing a common subunit (IL-10Rb) within their heterodimeric receptors and activating similar STATs, the signaling generated by IL-22 and IFN-λs is independent, with IFN-λ signaling inducing ISGs and IL-22 signaling inducing cell proliferation genes. Using human intestinal organoids, we confirmed that IL-22 increased the size of the organoids through increased cell proliferation and expression of the stem cell marker (OLFM4). These findings suggest that in human intestinal cells, IFN-λs and IL-22 act independently to clear virus infections. IFN-λs induce ISGs to control virus replication and spread, whereas IL-22 increases cell proliferation to eliminate infected cells and repair the damage epithelium. Although these two cytokines do not act synergistically, each plays a key function in the protection of human IECs.

mRNA vaccines contribute to innate and adaptive immunity to enhance immune response in vivo

Messenger RNA (mRNA) therapeutics have been widely employed as strategies for the treatment and prevention of diseases. Amid the global outbreak of COVID-19, mRNA vaccines have witnessed rapid development. Generally, in the case of mRNA vaccines, the initiation of the innate immune system serves as a prerequisite for triggering subsequent adaptive immune responses. Critical cells, cytokines, and chemokines within the innate immune system play crucial and beneficial roles in coordinating tailored immune reactions towards mRNA vaccines. Furthermore, immunostimulators and delivery systems play a significant role in augmenting the immune potency of mRNA vaccines. In this comprehensive review, we systematically delineate the latest advancements in mRNA vaccine research, present an in-depth exploration of strategies aimed at amplifying the immune effectiveness of mRNA vaccines, and offer some perspectives and recommendations regarding the future advancements in mRNA vaccine development.

Roles of programmed death-1 and muscle innate lymphoid cell-derived interleukin 13 in sepsis-induced intensive care unit-acquired weakness

BACKGROUND

Intensive care unit-acquired weakness (ICU-AW) is a syndrome characterized by a long-term muscle weakness often observed in sepsis-surviving patients during the chronic phase. Although ICU-AW is independently associated with increased mortality, effective therapies have yet to be established. Programmed death-1 (PD-1) inhibitors have attracted attention as potential treatments for reversing immune exhaustion in sepsis; however, its impact on ICU-AW remains to be elucidated. Here, we study how PD-1 deficiency affects sepsis-induced skeletal muscle dysfunction in a preclinical sepsis model.

METHODS

Chronic sepsis model was developed by treating wild-type (WT) and PD-1 knockout (KO) mice with caecal slurry, followed by resuscitation with antibiotics and saline. Mice were euthanized on days 15-17. Body weights, muscle weights, and limb muscle strengths were measured. Interleukin 13 (IL-13) and PD-1 expressions were examined by flow cytometry. Messenger RNA (mRNA) expressions of slow-twitch muscles were measured by reverse transcription and quantitative polymerase chain reaction (RT-qPCR). In an in vitro study, C2C12 myotubes were treated with lipopolysaccharide (LPS) and recombinant IL-13 followed by gene expression measurements.

RESULTS

WT septic mice exhibited decreased muscle weight (quadriceps, P < 0.01; gastrocnemius, P < 0.05; and tibialis anterior, P < 0.01) and long-term muscle weakness (P < 0.0001), whereas PD-1 KO septic mice did not exhibit any reduction in muscle weights and strengths. Slow-twitch specific mRNAs, including myoglobin (Mb), troponin I type 1 (Tnni1), and myosin heavy chain 7 (Myh7) were decreased in WT skeletal muscle (Mb, P < 0.0001; Tnni1, P < 0.05; and Myh7, P < 0.05) after sepsis induction, but mRNA expressions of Tnni1 and Myh7 were increased in PD-1 KO septic mice (Mb, not significant; Tnni1, P < 0.0001; and Myh7, P < 0.05). Treatment of C2C12 myotube cells with LPS decreased the expression of slow-twitch mRNAs, which was restored by IL-13 (Mb, P < 0.0001; Tnni1, P < 0.001; and Myh7, P < 0.05). IL-13 production was significantly higher in ILC2s compared to T cells in skeletal muscle (P < 0.05). IL-13-producing ILC2s in skeletal muscle were examined and found to increase in PD-1 KO septic mice, compared with WT septic mice (P < 0.05). ILC2-derived IL-13 was increased by PD-1 KO septic mice and thought to protect the muscles from experimental ICU-AW.

CONCLUSIONS

Long-term muscle weakness in experimental ICU-AW was ameliorated in PD-1 KO mice. ILC2-derived IL-13 production in skeletal muscles was increased in PD-1 KO mice, thereby suggesting that IL-13 alleviates muscle weakness during sepsis. This study demonstrates the effects of PD-1 blockade in preserving muscle strength during sepsis through an increase in ILC2-derived IL-13 and may be an attractive therapeutic target for sepsis-induced ICU-AW.

The potential of enteroids derived from children and adults to study age-dependent differences in intestinal CYP3A4/5 metabolism

Drug metabolism in the intestinal wall affects bioavailability of orally administered drugs and is influenced by age. Hence, it is important to fully understand the drug metabolizing capacity of the gut to predict systemic exposure. The aim of this study was to investigate the potential of enteroids as a tool to study CYP3A4/5 -mediated metabolism in both children and adults. Bioconversion of midazolam, a CYP3A4/5 model substrate, was studied using enteroid monolayers as well as tissue explants in the Ussing chamber, both derived from pediatric [median (range age): 54 weeks (2 days - 13 years), n = 21] and adult (n = 5) tissue. Caco-2 cellular monolayers were employed as controls. In addition, mRNA expression of CYP3A4 was determined in enteroid monolayers (n = 11), tissue (n = 23) and Caco-2 using RT-qPCR. Midazolam metabolism was successfully detected in all enteroid monolayers, as well as in all tissue explants studied in the Ussing chamber, whereas Caco-2 showed no significant metabolite formation. The extracted fraction of midazolam was similar between enteroid monolayers and tissue. The fraction of midazolam extracted increased with age in enteroid monolayers derived from 0 to 70 week old donors. No statistically significant correlation was observed in tissue likely due to high variability observed and the smaller donor numbers included in the study. At the level of gene expression, CYP3A4 increased with age in tissues (n = 32), while this was not reflected in enteroid monolayers (n = 16). Notably, asymmetric metabolite formation was observed in enteroids and tissue, with higher metabolite formation on the luminal side of the barrier. In summary, we demonstrated that enteroids can be used to measure CYP3A4/5 midazolam metabolism, which we show is similar as observed in fresh isolated tissue. This was the case both in children and adults, indicating the potential of enteroids to predict intestinal metabolism. This study provides promising data to further develop enteroids to study drug metabolism in vitro and potentially predict oral absorption for special populations as an alternative to using fresh tissue.

Formulation Attributes Impact Immune Profile of an Oral and Thermostable COVID-19 Subunit Vaccine

While approved vaccines for COVID-19 provide protection against severe disease and death, they have limited efficacy in the prevention of infection and virus transmission. Mucosal immunity is preferred over systemic immunity to provide protection at the point of entry against pathogens such as SARS-CoV-2. VaxForm has developed an oral vaccine delivery platform that elicits mucosal and systemic immune responses by targeting immune cells in the gut through C-type lectin receptors. The technology consists of microencapsulating the vaccine with an enteric polymer, which also results in enhanced thermostability. This article describes the formulation development and in vivo testing of a novel protein-based oral COVID-19 vaccine using this technology. Results demonstrate successful induction of immune response in mice and showed that the particle size of the vaccines following administration can impact the ratio of mucosal to systemic response. Immunogenicity and thermostability of liquid suspension and dry powder versions of the vaccine were compared in mice. The liquid suspension vaccine showed excellent heat resistance by maintaining immunogenicity after 14 days of storage at 60 °C. While further investigation is needed to determine correlates of protection and duration of response for mucosal immunity, this study demonstrates the vaccine's potential as a COVID-19 booster to enhance mucosal protection in humans and improve global access by lowering the cost of production, removing cold-chain requirements, and allowing self-administration.

Utilizing pigs as a model for studying intestinal barrier function

Intestinal permeability has been extensively studied, particularly in gastrointestinal diseases such as inflammatory bowel disease, food allergy, visceral disease, celiac disease, and Crohn’s disease. These studies have established that changes in intestinal permeability contribute to the pathogenesis of many gastrointestinal and systemic diseases. While numerous works in the 20th century focused on this topic, it remains relevant for several reasons. Despite the development of new research techniques, it is still unclear whether changes in intestinal permeability are the primary mechanism initiating the disease process or if they occur secondary to an ongoing chronic inflammatory process. Investigating the possibility of stabilizing the intestinal barrier, thereby reducing its permeability preemptively to prevent damage and after the damage has occurred, may offer new therapeutic approaches. Increased intestinal permeability is believed to lead to reduced nutrient absorption, resulting in decreased immunity and production of digestive enzymes.

Breaking the Barrier: The Role of Gut Epithelial Permeability in the Pathogenesis of Hypertension

PURPOSE OF THE REVIEW

To review what intestinal permeability is and how it is measured, and to summarise the current evidence linking altered intestinal permeability with the development of hypertension.

RECENT FINDINGS

Increased gastrointestinal permeability, directly measured in vivo, has been demonstrated in experimental and genetic animal models of hypertension. This is consistent with the passage of microbial substances to the systemic circulation and the activation of inflammatory pathways. Evidence for increased gut permeability in human hypertension has been reliant of a handful of blood biomarkers, with no studies directly measuring gut permeability in hypertensive cohorts. There is emerging literature that some of these putative biomarkers may not accurately reflect permeability of the gastrointestinal tract. Data from animal models of hypertension support they have increased gut permeability; however, there is a dearth of conclusive evidence in humans. Future studies are needed that directly measure intestinal permeability in people with hypertension.

Effects of Differently Processed Tea on the Gut Microbiota

Tea is a highly popular beverage, primarily due to its unique flavor and aroma as well as its perceived health benefits. The impact of tea on the gut microbiome could be an important means by which tea exerts its health benefits since the link between the gut microbiome and health is strong. This review provided a discussion of the bioactive compounds in tea and the human gut microbiome and how the gut microbiome interacts with tea polyphenols. Importantly, studies were compiled on the impact of differently processed tea, which contains different polyphenol profiles, on the gut microbiota from in vivo animal feeding trials, in vitro human fecal fermentation experiments, and in vivo human feeding trials from 2004-2024. The results were discussed in terms of different tea types and how their impacts are related to or different from each other in these three study groups.

Villification of the intestinal epithelium is driven by Foxl1

The primitive gut tube of mammals initially forms as a simple cylinder consisting of the endoderm-derived, pseudostratified epithelium and the mesoderm-derived surrounding mesenchyme. During mid-gestation a dramatic transformation occurs in which the epithelium is both restructured into its final cuboidal form and simultaneously folded and refolded to create intestinal villi and intervillus regions, the incipient crypts. Here we show that the mesenchymal winged helix transcription factor Foxl1, itself induced by epithelial hedgehog signaling, controls villification by activating BMP and PDGFRa as well as planar cell polarity genes in epithelial-adjacent telocyte progenitors, both directly and in a feed- forward loop with Foxo3. In the absence of Foxl1-dependent mesenchymal signaling, villus formation is delayed, the separation of epithelial cells into mitotic intervillus and postmitotic villus cells impaired, and the differentiation of secretory progenitors blocked. Thus, Foxl1 orchestrates key events during the epithelial transition of the fetal mammalian gut.

Gastrointestinal and Hepatobiliary Manifestations Associated with Untreated Celiac Disease in Adults and Children: A Narrative Overview

Celiac disease (CeD) is a chronic inflammatory disease of the small intestine, produced by ingesting dietary gluten products in susceptible people. Gluten causes an impairment of the mucosal surface and, consequently, an abnormal absorption of nutrients. Although malabsorption of essential nutrients is a major risk factor for various CeD-associated morbidities, genetic, immunological, and environmental factors also play an important role. The clinical presentation of CeD widely varies and can range from asymptomatic to full-blown symptoms due to the multi-system nature of CeD. The typical gastrointestinal (GI) manifestations of CeD include abdominal pain, diarrhea, bloating, and weight loss, but several hepatobiliary manifestations and a poor nutritional status have also been described. Currently, a gluten-free diet (GFD) is the only current evidence-based treatment that leads to the complete recovery of mucosal damage and the reversibility of its progression. Conversely, undiagnosed CeD might have severe consequences in children as well as in adult patients. This narrative overview aims to characterize the GI and hepatobiliary manifestations, nutritional deficiencies, and delayed pediatric development associated with unrecognized CeD in order to identify it promptly. Moreover, the role of GFD and how it could prevent long-term complications of CeD are described.

Parameterization of Physiologically Based Biopharmaceutics Models: Workshop Summary Report

This Article shares the proceedings from the August 29th, 2023 (day 1) workshop "Physiologically Based Biopharmaceutics Modeling (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives". The focus of the day was on model parametrization; regulatory authorities from Canada, the USA, Sweden, Belgium, and Norway presented their views on PBBM case studies submitted by industry members of the IQ consortium. The presentations shared key questions raised by regulators during the mock exercise, regarding the PBBM input parameters and their justification. These presentations also shed light on the regulatory assessment processes, content, and format requirements for future PBBM regulatory submissions. In addition, the day 1 breakout presentations and discussions gave the opportunity to share best practices around key questions faced by scientists when parametrizing PBBMs. Key questions included measurement and integration of drug substance solubility for crystalline vs amorphous drugs; impact of excipients on apparent drug solubility/supersaturation; modeling of acid-base reactions at the surface of the dissolving drug; choice of dissolution methods according to the formulation and drug properties with a view to predict the in vivo performance; mechanistic modeling of in vitro product dissolution data to predict in vivo dissolution for various patient populations/species; best practices for characterization of drug precipitation from simple or complex formulations and integration of the data in PBBM; incorporation of drug permeability into PBBM for various routes of uptake and prediction of permeability along the GI tract.

Mitochondrial function and gastrointestinal diseases

Mitochondria are dynamic organelles that function in cellular energy metabolism, intracellular and extracellular signalling, cellular fate and stress responses. Mitochondria of the intestinal epithelium, the cellular interface between self and enteric microbiota, have emerged as crucial in intestinal health. Mitochondrial dysfunction occurs in gastrointestinal diseases, including inflammatory bowel diseases and colorectal cancer. In this Review, we provide an overview of the current understanding of intestinal epithelial cell mitochondrial metabolism, function and signalling to affect tissue homeostasis, including gut microbiota composition. We also discuss mitochondrial-targeted therapeutics for inflammatory bowel diseases and colorectal cancer and the evolving concept of mitochondrial impairment as a consequence versus initiator of the disease.

Effects of a multistrain Bacillus-based direct-fed microbial on gastrointestinal permeability and biomarkers of inflammation during and following feed restriction in mid-lactation Holstein cows

Objectives were to evaluate the effects of a multistrain Bacillus-based (Bacillus subtilis and Bacillus pumilus blend) direct-fed microbial (DFM) on production, metabolism, inflammation biomarkers and gastrointestinal tract (GIT) permeability during and following feed restriction (FR) in mid-lactation Holstein cows. Multiparous cows (n = 36; 138 ± 53 DIM) were randomly assigned to 1 of 3 dietary treatments: (1) control (CON; 7.5 g/d rice hulls; n = 12), (2) DFM10 (10 g/d Bacillus DFM, 4.9 × 109 cfu/d; n = 12) or 3) DFM15 (15 g/d Bacillus DFM, 7.4 × 109 cfu/d; n = 12). Before study initiation, cows were fed their respective treatments for 32 d. Cows continued to receive treatments during the trial, which consisted of 3 experimental periods (P): P1 (5 d) served as baseline for P2 (5 d), during which all cows were restricted to 40% of P1 DMI, and P3 (5 d), a "recovery" where cows were fed ad libitum. On d 4 of P1 and on d 2 and 5 of P2, GIT permeability was evaluated in vivo using the oral paracellular marker Cr-EDTA. As anticipated, FR decreased milk production, insulin, glucagon, and BUN but increased nonesterified fatty acids. During recovery, DMI rapidly increased on d 1 then subsequently decreased (4.9 kg) on d 2 before returning to baseline, whereas milk yield slowly increased but remained decreased (13%) relative to P1. The DFM10 cows had increased DMI and milk yield relative to DFM15 during P3 (10%). Overall, milk lactose content was increased in DFM cows relative to CON (0.10 percentage units), and DFM10 cows tended to have increased lactose yield relative to CON and DFM15 during P3 (8% and 10%, respectively). No overall treatment differences were observed for other milk composition variables. Circulating glucose was quadratically increased in DFM10 cows compared with CON and DFM15 during FR and recovery. Plasma Cr area under the curve was increased in all cows on d 2 (9%) and 5 (6%) relative to P1. Circulating LPS binding protein (LBP), serum amyloid A (SAA), and haptoglobin (Hp) increased in all cows during P2 compared with baseline (31%, 100%, and 9.0-fold, respectively). Circulating Hp concentrations continued to increase during P3 (274%). Overall, circulating LBP and Hp tended to be increased in DFM15 cows relative to DFM10 (29% and 81%, respectively), but no treatment differences were observed for SAA. Following feed reintroduction during P3, fecal pH initially decreased (0.62 units), but returned to baseline levels whereas fecal starch markedly increased (2.5-fold) and remained increased (82%). Absolute quantities of a fecal Butyryl-CoA CoA transferase (but) gene associated with butyrate synthesis, collected by fecal swab were increased in DFM10 cows compared with CON and DFM15 cows. In summary, FR increased GIT permeability, caused inflammation, and decreased production. Feeding DFM10 increased some key production and metabolism variables and upregulated a molecular biomarker of microbial hindgut butyrate synthesis, while DFM15 appeared to augment immune activation.

Standardizing designed and emergent quantitative features in microphysiological systems

Microphysiological systems (MPSs) are cellular models that replicate aspects of organ and tissue functions in vitro. In contrast with conventional cell cultures, MPSs often provide physiological mechanical cues to cells, include fluid flow and can be interlinked (hence, they are often referred to as microfluidic tissue chips or organs-on-chips). Here, by means of examples of MPSs of the vascular system, intestine, brain and heart, we advocate for the development of standards that allow for comparisons of quantitative physiological features in MPSs and humans. Such standards should ensure that the in vivo relevance and predictive value of MPSs can be properly assessed as fit-for-purpose in specific applications, such as the assessment of drug toxicity, the identification of therapeutics or the understanding of human physiology or disease. Specifically, we distinguish designed features, which can be controlled via the design of the MPS, from emergent features, which describe cellular function, and propose methods for improving MPSs with readouts and sensors for the quantitative monitoring of complex physiology towards enabling wider end-user adoption and regulatory acceptance.

The Interplay between Endogenous and Foodborne Pro-Oxidants and Antioxidants in Shaping Redox Homeostasis

Oxidative stress has been known about in biological sciences for several decades; however, the understanding of this concept has evolved greatly since its foundation. Over the past years, reactive oxygen species, once viewed as solely deleterious, have become recognized as intrinsic components of life. In contrast, antioxidants, initially believed to be cure-all remedies, have failed to prove their efficacy in clinical trials. Fortunately, research on the health-promoting properties of antioxidants has been ongoing. Subsequent years showed that the former assumption that all antioxidants acted similarly was greatly oversimplified. Redox-active compounds differ in their chemical structures, electrochemical properties, mechanisms of action, and bioavailability; therefore, their efficacy in protecting against oxidative stress also varies. In this review, we discuss the changing perception of oxidative stress and its sources, emphasizing everyday-life exposures, particularly those of dietary origin. Finally, we posit that a better understanding of the physicochemical properties and biological outcomes of antioxidants is crucial to fully utilize their beneficial impact on health.

Effect of acetylcholinesterase inhibition on immune cells in the murine intestinal mucosa

The gastrointestinal tract (GI) is the largest immune organ whose function is controlled by a complex network of neurons from the enteric nervous system (ENS) as well as the sympathetic and parasympathetic system. Evolving evidence indicates that cross-communication between gut-innervating neurons and immune cells regulates many essential physiological functions including protection against mucosal infections. We previously demonstrated that following paraoxon treatment, 70 % of the mice were able to survive an oral infection with S. typhimurium, a virulent strain of Salmonella enterica serovar Typhimurium. The present study aims to investigate the effect that rivastigmine, a reversible AChE inhibitor used for the treatment of neurodegenerative diseases, has on the murine immune defenses of the intestinal mucosa. Our findings show that, similar to what is observed with paraoxon, administration of rivastigmine promoted the release of secretory granules from goblet and Paneth cells, resulting in increased mucin layer. Surprisingly, however, and unlike paraoxon, rivastigmine treatment did not affect overall mortality of infected mice. In order to investigate the mechanistic basis for the differential effects observed between paraoxon and rivastigmine, we used multi-color flowcytometric analysis to characterize the immune cell landscape in the intraepithelial (IE) and lamina propria (LP) compartments of intestinal mucosa. Our data indicate that treatment with paraoxon, but not rivastigmine, led to an increase of resident CD3+CD8+ T lymphocytes in the ileal mucosa (epithelium and lamina propria) and CD11b- CD11c+ dendritic cells in the LP. Our findings indicate the requirement for persistent cholinergic pathway engagement to effect a change in the cellular landscape of the mucosal tissue that is necessary for protection against lethal bacterial infections. Moreover, optimal protection requires a collaboration between innate and adaptive mucosal immune responses in the intestine.

Host defense peptides human β defensin 2 and LL-37 ameliorate murine necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of preterm infant morbidity and mortality. Treatment for NEC is limited and non-targeted, which makes new treatment and prevention strategies critical. Host defense peptides (HDPs) are essential components of the innate immune system and have multifactorial mechanisms in host defense. LL-37 and hBD2 are two HDPs that have been shown in prior literature to protect from neonatal sepsis-induced mortality or adult inflammatory bowel disease, respectively. Therefore, this article sought to understand if these two HDPs could influence NEC severity in murine preclinical models. NEC was induced in P14-16 C57Bl/6 mice and HDPs were provided as a pretreatment or treatment. Both LL-37 and hBD2 resulted in decreased NEC injury scores as a treatment and hBD2 as a pretreatment. Our data suggest LL-37 functions through antimicrobial properties, while hBD2 functions through decreases in inflammation and improvement of intestinal barrier integrity.

The MUC2 Gene Product: Polymerisation and Post-Secretory Organisation-Current Models

MUC2 mucin, the primary gel-forming component of intestinal mucus, is well researched and a model of polymerisation and post-secretory organisation has been published previously. Recently, several significant developments have been made which either introduce new ideas or challenge previous theories. New ideas include an overhaul of the MUC2 C-terminal globular structure which is proposed to harbour several previously unobserved domains, and include a site for an extra intermolecular disulphide bridge dimer between the cysteine 4379 of adjacent MUC2 C-termini. MUC2 polymers are also now thought to be secreted attached to the epithelial surface of goblet cells in the small intestine and removed following secretion via a metalloprotease meprin β-mediated cleavage of the von Willebrand D2 domain of the N-terminus. It remains unclear whether MUC2 forms intermolecular dimers, trimers, or both, at the N-termini during polymerisation, with several articles supporting either trimer or dimer formation. The presence of a firm inner mucus layer in the small intestine is similarly unclear. Considering this recent research, this review proposes an update to the previous model of MUC2 polymerisation and secretion, considers conflicting theories and data, and highlights the importance of this research to the understanding of MUC2 mucus layers in health and disease.

A thermally reversible injectable adhesive for intestinal tissue repair and anti-postoperative adhesion

Intestine damage is an acute abdominal disease that usually requires emergency sealing. However, traditional surgical suture not only causes secondary damage to the injured tissue, but also results in adhesion with other tissues in the abdominal cavity. To this end, a thermally reversible injectable gelatin-based hydrogel adhesive (GTPC) is constructed by introducing transglutaminase (TGase) and proanthocyanidins (PCs) into a gelatin system. By reducing the catalytic activity of TGase, the density of covalent and hydrogen bond crosslinking in the hydrogel can be regulated to tune the sol-gel transition temperature of gelatin-based hydrogels above the physiological temperature (42 °C) without introducing any synthetic small molecules. The GTPC hydrogel exhibits good tissue adhesion, antioxidant, and antibacterial properties, which can effectively seal damaged intestinal tissues and regulate the microenvironment of the damaged site, promoting tissue repair and regeneration. Intriguingly, temperature-induced hydrogen bond disruption and reformation confer the hydrogel with asymmetric adhesion properties, preventing tissue adhesion when applied in vivo. Animal experiment outcomes reveal that the GTPC hydrogel can seal the damaged intestinal tissue firmly, accelerate tissue healing, and efficiently prevent postoperative adhesion.

Bacteriophage defends murine gut from Escherichia coli invasion via mucosal adherence

Bacteriophage are sophisticated cellular parasites that can not only parasitize bacteria but are increasingly recognized for their direct interactions with mammalian hosts. Phage adherence to mucus is known to mediate enhanced antimicrobial effects in vitro. However, little is known about the therapeutic efficacy of mucus-adherent phages in vivo. Here, using a combination of in vitro gastrointestinal cell lines, a gut-on-a-chip microfluidic model, and an in vivo murine gut model, we demonstrated that a E. coli phage, øPNJ-6, provided enhanced gastrointestinal persistence and antimicrobial effects. øPNJ-6 bound fucose residues, of the gut secreted glycoprotein MUC2, through domain 1 of its Hoc protein, which led to increased intestinal mucus production that was suggestive of a positive feedback loop mediated by the mucus-adherent phage. These findings extend the Bacteriophage Adherence to Mucus model into phage therapy, demonstrating that øPNJ-6 displays enhanced persistence within the murine gut, leading to targeted depletion of intestinal pathogenic bacteria.

Dynamics and metabolic effects of intestinal gases in healthy humans

Many living beings use exogenous and/or endogenous gases to attain evolutionary benefits. We make a comprehensive assessment of one of the major gaseous reservoirs in the human body, i.e., the bowel, providing extensive data that may serve as reference for future studies. We assess the intestinal gases in healthy humans, including their volume, composition, source and local distribution in proximal as well as distal gut. We analyse each one of the most abundant intestinal gases including nitrogen, oxygen, nitric oxide, carbon dioxide, methane, hydrogen, hydrogen sulfide, sulfur dioxide and cyanide. For every gas, we describe diffusive patterns, active trans-barrier transport dynamics, chemical properties, intra-/extra-intestinal metabolic effects mediated by intracellular, extracellular, paracrine and distant actions. Further, we highlight the local and systemic roles of gasotransmitters, i.e., signalling gaseous molecules that can freely diffuse through the intestinal cellular membranes. Yet, we provide testable hypotheses concerning the still unknown effects of some intestinal gases on the myenteric and submucosal neurons.

High Accuracy Localization for Miniature Ingestible Devices Using Mutual Inductance

This article demonstrates an inductively coupled high-accuracy localization system for miniature ingestible devices. It utilizes an inductance double capacitances-series capacitance (LCC-S) compensation architecture that enables mutual inductance measurement at primary side that is positioned outside the human body and less constrained by power budget and size than the miniature ingestible. Depending on the secondary circuit architecture, only limited and simple cooperative measurements are needed from the ingestible secondary side, which saves power and area in the miniature device. The errors in the system are modeled thoroughly, providing insights about system require-ments for a particular localization accuracy target for efficient design and to identify key building blocks with large influence on overall performance. The model shows that sub-centimeter localization root-mean-square error (RMSE) can be achieved with a modest external ADC (18bit) using three primary coils and three secondary coils. The localization is verified along a complete small intestine tract with realistic dimensions. The proposed model is verified by simulation and experiment showing that at the selected frequency range up to 5 MHz the body has no influence on the accuracy. The use of 0.9% saline as phantom is proposed which guarantees the analysis validity for all body types.