Gastrointestinal Regions Research Articles

Validation of gut transit rate assessment methodology and the mitigation of sampling stress in Atlantic salmon, Salmo salar

Gut transit rate is an important component of the digestive process in fish, particularly in the context of aquaculture, where factors such as rearing temperature and dietary formulation impact on-farm performance. As such, developing and validating research methodologies that explore these critical physiological responses in fish is vital in the context of precision aquaculture practices. However, there are inherent methodological constraints of gut transit rate assessments, particularly when assessing the effect of sampling on the stress response of fish. In light of this, the present study aimed to assess the gut transit rate and plasma cortisol levels of Atlantic salmon (Salmo salar) subjected to the more commonly applied, repeated sampling model that results in multiple tanks disturbances (e.g., 2, 4, 8, 16 and 24 h post-feed) in comparison to one requiring only a singular tank disturbance at one of the designated time points. An inert beaded marker was integrated into diet formulations to determine the transit rate of digesta in three major gastrointestinal tract regions: the stomach, mid-intestine, and distal intestine over a period of 48 h following the provision of food. A significantly higher plasma cortisol concentration was recorded in fish subjected to a repeated disturbance, particularly at 16 h post feed (22.99 ± 6.88 ng mL−1), compared to fish sampled from tanks subjected to a single sampling event (11.35 ± 0.92 ng mL−1). Despite this, gut transit rate was generally unaffected by sampling design over the duration of the study with both groups of fish displaying a similar rate of gut transit. This suggests that repeated tank sampling (i.e. sampling multiple fish from the same tank at multiple timepoints) is suitable to assess gut transit rate in fish as it does not significantly confound gut transit rate assessments. It is envisioned that this data will contribute to the growing understanding of the digestive process of Atlantic salmon and the relationship with stress response in fish and experimental design. Moreover, it should strengthen future studies aimed at assessing key digestive processes in cultured species.

Characterization of the gastrointestinal microbiome of the Syrian hamster (Mesocricetus auratus) and comparison to data from mice.

Syrian hamsters (Mesocricetus auratus) have been increasingly used as rodent models in recent years, especially for SARS-CoV-2 since the pandemic. However, the physiology of this animal model is not yet well-understood, even less when considering the digestive tract. Generally, the gastrointestinal microbiome influences the immune system, drug metabolism, and vaccination efficacy. However, a detailed understanding of the gastrointestinal microbiome of hamsters is missing. Therefore, we analyzed 10 healthy 11-week-old RjHan:AURA hamsters fed a pelleted standard diet. Their gastrointestinal content was sampled (i.e., forestomach, glandular stomach, ileum, cecum, and colon) and analyzed using 16S rRNA gene amplicon sequencing. Results displayed a distinct difference in the bacterial community before and after the cecum, possibly due to the available nutrients and digestive functions. Next, we compared hamsters with the literature data of young-adult C57BL/6J mice, another important animal model. We sampled the same gastrointestinal regions and analyzed the differences in the microbiome between both rodents. Surprisingly, we found strong differences in their specific gastrointestinal bacterial communities. For instance, Lactobacillaceae were more abundant in hamsters' forestomach and ileum, while Muribaculaceae dominated in the mouse forestomach and ileum. Similarly, in mouse cecum and colon, Muribaculaceae were dominant, while in hamsters, Lachnospiraceae and Erysipelotrichaceae dominated the bacterial community. Molecular strains of Muribaculaceae in both rodent species displayed some species specificity. This comparison allows a better understanding of the suitability of the Syrian hamster as an animal model, especially regarding its comparability to other rodent models. Thereby, this work contributes to the characterization of the hamster model and allows better experimental planning.

Microbial Biogeography along the Gastrointestinal Tract of a Wild Chinese Muntjac (Muntiacus reevesi).

The gut microbiota plays an important role in host nutrient absorption, immune function, and behavioral patterns. Much research on the gut microbiota of wildlife has focused on feces samples, so the microbial composition along the gastrointestinal tract of wildlife is not well reported. To address this gap, we performed high-throughput sequencing of 16s rRNA genes and ITs rRNA genes in the gastrointestinal contents of a wild adult male Chinese muntjac (Muntiacus reevesi) to comparatively analyze the microbial diversity of different gastrointestinal regions. The results showed that the dominant bacterial phyla were Firmicutes (66.19%) and Bacteroidetes (22.7%), while the dominant fungal phyla were Ascomycetes (72.81%). The highest bacterial diversity was found in the stomach, and the highest fungal diversity was found in the cecum. The microbial communities of the large intestine and small intestine were of similar structures, which were distinct from that of the stomach. These results would facilitate the continued exploration of the microbial composition and functional diversity of the gastrointestinal tract of wild Chinese muntjacs and provide a scientific basis for microbial resource conservation of more wildlife.

A Novel Use of Embryonic Gut Organoid Culture to Investigate Duodenal Atresia

BackgroundThe cause of duodenal atresia (DA) is not known. Tandler's “solid cord” hypothesis conflicts with current biological evidence. In humans, a genetic aetiology is supported by the association with Trisomy 21. Interruption of Fgf10 is the strongest genetic link to DA in mice, demonstrating an increased incidence and severity as embryos mature. This project aimed to develop an organoid model to facilitate ex vivo DA research on the FGF10/FGFR2b signalling pathway. We hypothesised that DA morphology represents an evolving spectrum of disease and that Fgf10 knockout organoids would vary in growth pattern compared to wild-type. MethodsOrganoids were cultured from the duodenum of E12.5 Fgf10 knockout, heterozygous and wild-type embryos, using an air-liquid interface with Growth Factor reduced Matrigel. Organoids were photographed every 48 h to observe growth. Organoids were isolated and fixed after 14 days, then stained with DAPI, KI-67, and cytokeratin to demonstrate proliferation and differentiation. ResultsWild-type duodenum developed into crypt-forming organoids. Fgf10 heterozygous duodenum failed to progress beyond the development stage of spheroids. Fgf10 knockout duodenum failed to demonstrate any growth. Wholemount staining showed the greatest cell proliferation and differentiation in wild-type tissue. ConclusionThis research presents a novel concept for the growth of embryonic gastrointestinal tissue to inform normal biology. The small sample numbers and restricted culture duration limit longer-term growth analysis. While this model serves as a potential ex vivo setting for future research, that research should consider organoid models with greater standardisation and other gastrointestinal regions. Level of EvidenceAnimal/laboratory study.

The human colon: Evidence for degenerative changes during aging and the physiological consequences.

The incidence of constipation increases among the elderly (>65 years), while abdominal pain decreases. Causes include changes in lifestyle (e.g., diet and reduced exercise), disease and medications affecting gastrointestinal functions. Degenerative changes may also occur within the colo-rectum. However, most evidence is from rodents, animals with relatively high rates of metabolism and accelerated aging, with considerable variation in time course. In humans, cellular and non-cellular changes in the aging intestine are poorly investigated. To examine all available studies which reported the effects of aging on cellular and tissue functions of human isolated colon, noting the region studied, sex and age of tissue donors and study size. The focus on human colon reflects the ability to access full-thickness tissue over a wide age range, compared with other gastrointestinal regions. Details are important because of natural human variability. We found age-related changes within the muscle, in the enteric and nociceptor innervation, and in the submucosa. Some involve all regions of colon, but the ascending colon appears more vulnerable. Changes can be cell- and sublayer-dependent. Mechanisms are unclear but may include development of "senescent-like" and associated inflammaging, perhaps associated with increased mucosal permeability to harmful luminal contents. In summary, reduced nociceptor innervation can explain diminished abdominal pain among the elderly. Degenerative changes within the colon wall may have little impact on symptoms and colonic functions, because of high "functional reserve," but are likely to facilitate the development of constipation during age-related challenges (e.g., lifestyle, disease, and medications), now operating against a reduced functional reserve.

Yeast Expressing a Phage Endolysin Reduces Endogenous Clostridium perfringens Ex Vivo in 21-Day-Old Broiler Chicken Intestinal Fluids.

The phage endolysin PlyCP41 when purified from Escherichia coli exhibits lytic activity against Clostridium perfringens (CP) in vitro. The anti-clostridial activity of PlyCP41 endolysin expressed in transgenic yeast (Saccharomyces cerevisiae) was verified in phosphate buffered saline via mixing experiments with cultured CP and transgenic yeast slurries followed by serial dilution plating and colony counts on tryptose sulfite cycloserine (CP indicator) plates. The transgenic yeast containing PlyCP41 resulted in a log10 4.5 reduction (99.997%; P < 0.01) of the cultured CP. In addition, this serial dilution plating assay was used to demonstrate that transgenic yeast slurries could reduce the endogenous CP content in fluids from three different gastrointestinal regions (proximal, medial, and distal) from 21-day-old broiler chickens. The transgenic yeast treatment of gut slurries resulted in a log 10 1.19, 4.53, and 1.28 reduction in proximal, medial, and distal gut slurries (90% to 99.99% of the endogenous CP; P < 0.01), respectively, compared to nontreatment controls. These results indicate that the phage endolysin PlyCP41 expressed in S. cerevisiae is effective at reducing the endogenous CP in gastrointestinal fluids of broiler chickens. Future studies will measure the anti-CP effect in vivo by administering transgenic yeast to broiler chickens in the feed.

Distribution of interstitial cells within the mouse esophagus and their spatial relationship to enteric neurons

Background/Objectives: The esophagus is a conduit for the passage of ingested material into the stomach. In humans, it is divided into thirds; the proximal portion is composed of skeletal muscle, the distal is composed of smooth muscle and the middle is a transition zone between skeletal and smooth muscles. In other species such as the mouse, the esophagus has been described to consist entirely of skeletal muscle. Despite this, interstitial cells of Cajal (ICC), cells that regulate gastrointestinal (GI) smooth muscle contractility, have been identified throughout the mouse esophageal body (Rumessen et al., 2001; PMID:11683170). Additional studies in the human esophagus have identified another interstitial cell type, PDGFRa+ cells (Chen et al., 2013; PMID:23734090). However, the distribution of interstitial cells, motor and sensory neurons and their spatial relationship to one another have never been examined. Since interstitial cells modulate contractility of smooth muscle in other GI regions, the presence of these cells leads to the hypothesis that the mouse esophagus also contains smooth muscle cells (SMCs). Therefore, the aims of our study were to 1) determine if SMCs are found within the mouse esophagus, 2) characterize the distribution of ICC and PDGFRa+ cells, and 3) examine the relationship of interstitial cells to enteric motor and sensory neurons. Methods: Wildtype (C57Bl/6) and smooth muscle eGFP (smMHC-eGFP) mouse esophagus was used for dual labeling immunohistochemistry. ICC were labeled with antibodies against Kit or ANO1. PDGFRa+ cells were labeled with antibodies against PDGFRa or SK3. Extrinsic sympathetic neurons were labeled with tyrosine hydroxylase (TH). Motor neurons were labeled with antibodies against NOS, VIP (inhibitory) and vChAT (excitatory). Sensory neurons were labeled with CGRP. Images were taken with a Leica Stellaris 5 confocal microscope and processed using LasX software. Results: SMCs were found throughout the length of the esophagus, although their density declined proximally. Intramuscular ICC expressed ANO1 and were distributed throughout the length of the esophagus with the greatest density in the gastroesophageal junction (GEJ). Submucosal and intramuscular PDGFRa+ cells were distributed throughout the esophagus and GEJ. Intramuscular PDGFRa+ cells expressed SK3 though this expression declined proximally. SMCs, intramuscular ICC and PDGFRa+ cells were closely associated with one another as well as with neurons. Discussion/Conclusions: This study is the first to systematically characterize SMCs, ICC, PDGFRa+ cells and neurons in the mouse esophagus. These findings suggest that the mouse may represent a better translational model for studying esophageal motility than previously assumed. NIH DK129528 and P20GM130459. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Differential Colonization and Mucus Ultrastructure Visualization in Bovine Ileal and Rectal Organoid-Derived Monolayers Exposed to Enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) is a critical public health concern due to its role in severe gastrointestinal illnesses in humans, including hemorrhagic colitis and the life-threatening hemolytic uremic syndrome. While highly pathogenic to humans, cattle, the main reservoir for EHEC, often remain asymptomatic carriers, complicating efforts to control its spread. Our study introduces a novel method to investigate EHEC using organoid-derived monolayers from adult bovine ileum and rectum. These polarized epithelial monolayers were exposed to EHEC for four hours, allowing us to perform comparative analyses between the ileal and rectal tissues. Our findings mirrored in vivo observations, showing a higher colonization rate in the rectum compared with the ileum (44.0% vs. 16.5%, p < 0.05). Both tissues exhibited an inflammatory response with increased expression levels of TNF-a (p < 0.05) and a more pronounced increase of IL-8 in the rectum (p < 0.01). Additionally, the impact of EHEC on the mucus barrier varied across these gastrointestinal regions. Innovative visualization techniques helped us study the ultrastructure of mucus, revealing a net-like mucin glycoprotein organization. While further cellular differentiation could enhance model accuracy, our research significantly deepens understanding of EHEC pathogenesis in cattle and informs strategies for the preventative measures and therapeutic interventions.

The contemplation of amylosefor the delivery of ulcerogenic nonsteroidal anti-inflammatory drugs.

This manuscript proposes an innovative approach to mitigate the gastrointestinal adversities linked withnonsteroidal anti-inflammatory drugs (NSAIDs) by exploiting amylose as a novel drug delivery carrier. The intrinsic attributes of V-amylose, such as its structural uniqueness, biocompatibility andbiodegradability, as well asits capacity to form inclusion complexes with diverse drug molecules, are meticulously explored. Through a comprehensive physicochemical analysis of V-amylose and ulcerogenic NSAIDs, the plausibility of amylose as a protective carrier for ulcerogenic NSAIDs to gastrointestinal regions is elucidated. This review further discusses the potential therapeutic advantages of amylose-based drug delivery systems in the management of gastric ulcers. By providing controlled release kinetics and enhanced bioavailability, these systems offer promising prospects for the development of more effective ulcer therapies.

Antimicrobial Properties of Colostrum and Milk.

The growing number of antibiotic resistance genes is putting a strain on the ecosystem and harming human health. In addition, consumers have developed a cautious attitude towards chemical preservatives. Colostrum and milk are excellent sources of antibacterial components that help to strengthen the immunity of the offspring and accelerate the maturation of the immune system. It is possible to study these important defenses of milk and colostrum, such as lactoferrin, lysozyme, immunoglobulins, oligosaccharides, etc., as biotherapeutic agents for the prevention and treatment of numerous infections caused by microbes. Each of these components has different mechanisms and interactions in various places. The compound's mechanisms of action determine where the antibacterial activity appears. The activation of the antibacterial activity of milk and colostrum compounds can start in the infant's mouth during lactation and continue in the gastrointestinal regions. These antibacterial properties possess potential for therapeutic uses. In order to discover new perspectives and methods for the treatment of bacterial infections, additional investigations of the mechanisms of action and potential complexes are required.

The Microbiota Architecture of the Chinchilla Gastrointestinal Tract.

The gastrointestinal microbiota develop alongside the host and play a vital role in the health of cecal fermenters such as chinchillas. However, little is known about the microbiota architecture in healthy chinchillas. Illumine-based 16S rRNA gene amplicon sequencing was used to investigate the microbiota present in six different gastrointestinal tract regions of three healthy adult chinchillas. The findings revealed significantly more abundant microbiota in the large intestine compared with the proximal segments. In addition, the cecum exhibited better evenness compared to the colon. The core microbiota are Firmicutes, Bacteroidota, Actinobacteriota, and Proteobacteria at the phylum level. The signature microbiota of each segment were identified. The cecum had 10 signature microbiota, which had the widest coverage and overlapped with that of the cecum. The stomach had five signature microbiota, exhibiting the second widest coverage and overlapping with the duodenum. No signature microbiota were detected in the jejunum and ileum. While similarities exist with the microbiota of other cecal fermenters, chinchillas exhibit distinct microbiota closely related to their unique digestive mechanisms. This study is a preliminary study of the gastrointestinal microbiota architecture and distribution in healthy chinchillas. Further study is needed in order to better understand the effect of gastrointestinal microbiota on the health of the chinchilla.

CoInNet: A Convolution-Involution Network With a Novel Statistical Attention for Automatic Polyp Segmentation.

Polyps are very common abnormalities in human gastrointestinal regions. Their early diagnosis may help in reducing the risk of colorectal cancer. Vision-based computer-aided diagnostic systems automatically identify polyp regions to assist surgeons in their removal. Due to their varying shape, color, size, texture, and unclear boundaries, polyp segmentation in images is a challenging problem. Existing deep learning segmentation models mostly rely on convolutional neural networks that have certain limitations in learning the diversity in visual patterns at different spatial locations. Further, they fail to capture inter-feature dependencies. Vision transformer models have also been deployed for polyp segmentation due to their powerful global feature extraction capabilities. But they too are supplemented by convolution layers for learning contextual local information. In the present paper, a polyp segmentation model CoInNet is proposed with a novel feature extraction mechanism that leverages the strengths of convolution and involution operations and learns to highlight polyp regions in images by considering the relationship between different feature maps through a statistical feature attention unit. To further aid the network in learning polyp boundaries, an anomaly boundary approximation module is introduced that uses recursively fed feature fusion to refine segmentation results. It is indeed remarkable that even tiny-sized polyps with only 0.01% of an image area can be precisely segmented by CoInNet. It is crucial for clinical applications, as small polyps can be easily overlooked even in the manual examination due to the voluminous size of wireless capsule endoscopy videos. CoInNet outperforms thirteen state-of-the-art methods on five benchmark polyp segmentation datasets.

Characterizing bacterial and fungal communities along the longitudinal axis of the intestine in cynomolgus monkeys

ABSTRACT The gut microbiota develops specialized local communities along the gastrointestinal (GI) tract of the host. Among these microbes, intestinal bacteria and fungi interact closely with the host and play vital roles in their health. However, the gut biogeography of bacteria and fungi has rarely been studied simultaneously, and their correlations have not been reported. In this study, we collected the intestinal luminal contents from different gastrointestinal regions (the ileum, caecum, and colon) of wild-type female cynomolgus monkeys and performed 16S and 18S rRNA gene sequencing to determine the gut biogeography of bacterial and fungal communities. The richness and diversity of bacteria and fungi increased gradually from the small to the large intestine. The bacterial and fungal composition of ileum differed significantly from that of the colon. Specifically, Bacteroidia and Spirochaetia were abundant in the caecum and colon, while Actinobacteria and Cyanobacteria were enriched in the ileum. As for fungal taxa, the genera Aspergillus , Wallemia , and Cryptococcus_f_Tremellaceae were enriched in the colon, while the genus Fusarium was abundant in the caecum. Consequently, the bacterial and fungal functions of the ileum differed from those of the caecum and colon. Notably, we characterized the correlations between intestinal bacteria and fungi at different gastrointestinal regions of cynomolgus monkeys using Spearman correlation analysis. In summary, our results contribute to a more comprehensive understanding of the composition and function of intestinal bacteria and fungi in non-human primates (NHPs) and reveal their correlations along the longitudinal axis of the intestine. IMPORTANCE Gut microbiota varies along the gastrointestinal (GI) tract and exerts profound influences on the host’s physiology, immunity, and nutrition. Given that gut microbes interact with the host closely and the gastrointestinal function differed from the small to the large intestine, it is essential to characterize the gut biogeography of the microbial community. Here, we focused on intestinal bacteria and fungi in cynomolgus monkeys and determined their spatial distribution along the GI tract by performing 16S and 18S rRNA gene sequencing. The composition and function of bacterial and fungal communities differed significantly at different biogeographic sites of the intestine, and the site-specific correlations between intestinal bacteria and fungi were revealed. Thus, our studies characterized the gut biogeography of bacteria and fungi in NHPs and revealed their site-specific correlations along the GI tract.

A new architecture combining convolutional and transformer-based networks for automatic 3D multi-organ segmentation on CT images.

Deep learning-based networks have become increasingly popular in the field of medical image segmentation. The purpose of this research was to develop and optimize a new architecture for automatic segmentation of the prostate gland and normal organs in the pelvic, thoracic, and upper gastro-intestinal (GI) regions. We developed an architecture which combines a shifted-window (Swin) transformer with a convolutional U-Net. The network includes a parallel encoder, a cross-fusion block, and a CNN-based decoder to extract local and global information and merge related features on the same scale. A skip connection is applied between the cross-fusion block and decoder to integrate low-level semantic features. Attention gates (AGs) are integrated within the CNN to suppress features in image background regions. Our network is termed "SwinAttUNet." We optimized the architecture for automatic image segmentation. Training datasets consisted of planning-CT datasets from 300 prostate cancer patients from an institutional database and 100 CT datasets from a publicly available dataset (CT-ORG). Images were linearly interpolated and resampled to a spatial resolution of (1.0×1.0×1.5) mm3 . A volume patch (192×192×96) was used for training and inference, and the dataset was split into training (75%), validation (10%), and test (15%) cohorts. Data augmentation transforms were applied consisting of random flip, rotation, and intensity scaling. The loss function comprised Dice and cross-entropy equally weighted and summed. We evaluated Dice coefficients (DSC), 95th percentile Hausdorff Distances (HD95), and Average Surface Distances (ASD) between results of our network and ground truth data. SwinAttUNet, DSC values were 86.54±1.21, 94.15±1.17, and 87.15±1.68% and HD95 values were 5.06±1.42, 3.16±0.93, and 5.54±1.63mm for the prostate, bladder, and rectum, respectively. Respective ASD values were 1.45±0.57, 0.82±0.12, and 1.42±0.38mm. For the lung, liver, kidneys and pelvic bones, respective DSC values were: 97.90±0.80, 96.16±0.76, 93.74±2.25, and 89.31±3.87%. Respective HD95 values were: 5.13±4.11, 2.73±1.19, 2.29±1.47, and 5.31±1.25mm. Respective ASD values were: 1.88±1.45, 1.78±1.21, 0.71±0.43, and 1.21±1.11mm. Our network outperformed several existing deep learning approaches using only attention-based convolutional or Transformer-based feature strategies, as detailed in the results section. We have demonstrated that our new architecture combining Transformer- and convolution-based features is able to better learn the local and global context for automatic segmentation of multi-organ, CT-based anatomy.

Gastrointestinal microbiome, resistance genes, and risk assessment of heavy metals in wild giant pandas

The gastrointestinal microbiome (GM) of giant panda (GP) plays an important role in food utilization and health and is also an essential reservoir of resistance genes. Currently, little knowledge is available on the GM, acid resistance genes (AcRGs), antibiotic resistance genes (ARGs), metal resistance genes (MRGs), and mobile genetic elements (MGEs) in wild GPs. We sampled the gastrointestinal tract of a dead GP and explored the composition and function of GM and resistance genes through cryo-scanning electron microscopy, metagenomic sequencing, and genome-resolved metagenomics. The concentration of metals in the gastrointestinal lumen, feces, bamboo, and soil was measured by inductively coupled plasma mass spectrometry. Results showed that the composition of the microbiota varied in different gastrointestinal regions. Fecal microbiota was highly associated with small intestinal and colonic microbes. The lignocellulosic cross-linked structure of bamboo was destroyed in the stomach initially and destroying degree increased from stomach to anus. Reconstruction of metagenome-assembled-genomes confirmed that core GM, e.g., Streptococcus, Clostridium, Lactococcus, Leuconostoc, and Enterococcus, carried genes encoding the lignocellulose degradation enzyme. There were no significant differences of resistance genes between gastrointestinal and fecal samples, except MGEs. Multidrug and multi-metal resistance genes were predominant in all samples, while the transposase gene tnpA was the major type of MGE. Significant correlations were observed among the abundance of GM, resistance genes, and MGEs. Gastrointestinal and fecal mercury and chromium were the main metals influencing GM and resistance genes. The content of gastrointestinal and fecal metals was significantly associated with the presence of the same metals in bamboo, which could pose a threat to the health of wild GPs. This study characterized the gastrointestinal microbiome of wild GPs, providing new evidence for the role of the gastrointestinal microbiome in degrading lignocellulose from bamboo and highlighting the urgent need to monitor metal levels in soil and bamboo.

Freestanding region-responsive bilayer for functional packaging of ingestible devices

Ingestible capsules have the potential to become an attractive alternative to traditional means of treating and detecting gastrointestinal (GI) disease. As device complexity increases, so too does the demand for more effective capsule packaging technologies to elegantly target specific GI locations. While pH-responsive coatings have been traditionally used for the passive targeting of specific GI regions, their application is limited due to the geometric restrictions imposed by standard coating methods. Dip, pan, and spray coating methods only enable the protection of microscale unsupported openings against the harsh GI environment. However, some emerging technologies have millimeter-scale components for performing functions such as sensing and drug delivery. To this end, we present the freestanding region-responsive bilayer (FRRB), a packaging technology for ingestible capsules that can be readily applied for various functional ingestible capsule components. The bilayer is composed of rigid polyethylene glycol (PEG) under a flexible pH-responsive Eudragit® FL 30 D 55, which protects the contents of the capsule until it arrives in the targeted intestinal environment. The FRRB can be fabricated in a multitude of shapes that facilitate various functional packaging mechanisms, some of which are demonstrated here. In this paper, we characterize and validate the use of this technology in a simulated intestinal environment, confirming that the FRRB can be tuned for small intestinal release. We also show a case example where the FRRB is used to protect and expose a thermomechanical actuator for targeted drug delivery.

Low endogenous deoxyribonuclease activity in the colon as a factor contributing to the pathogenesis of ulcerative colitis

In inflammatory bowel disease (IBD), tissue damage and cell death occur, which are accompanied by the release of DNA into the extracellular space. Deoxyribonucleases (DNases) are enzymes that cleave phosphodiester bonds in DNA. Exogenous DNases have anti-inflammatory effects in animal models. It is not known whether endogenous DNase activity can affect the pathogenesis of IBD. Herein we hypothesize that lower DNase activity found in the distal colon compared with proximal parts of the gastrointestinal tract could be partially responsible for the limited localization of ulcerative colitis to distal parts of the gastrointestinal tract and contribute to the ineffective removal of pro-inflammatory extracellular DNA. Hypothesis testing was performed on homogenates of individual parts of the gastrointestinal tract, in which endogenous DNase activity and its change after addition of DNase as a therapeutic were measured. A more accurate determination of DNase activity in individual gastrointestinal regions and uncovering the unknown DNase inhibitors in the colon could help to optimize the preparation of targeted therapeutics for IBD. Localized exogenous delivery of DNases to cleave extracellular DNA and eliminate inflammation could thus represent an effective supplementary therapy.

Effects of Hesperidin and Diosmin on Necrotizing Enterocolitis: An Experimental Study

Background: Necrotizing enterocolitis (NEC) is a serious intestinal illness in newborns. Objectives: We aimed to investigate the potential protective effects of hesperidin (Hsd) and diosmin on NEC. Methods: Thirty newborn rats were divided into 3 groups: The control group (n = 10), the NEC group (n = 10), and the treatment group (n = 10). The treatment group was given 100 mg/kg of the flavonoid by oral gavage twice daily. On day 5 of the study, animals were sacrificed under anesthesia. After laparotomy, the tissue samples were obtained from the stomach, cecum, and ileum. NEC scoring was performed histopathologically. Apoptotic changes were evaluated by TUNEL (terminal deoxynucleotidyl transferase–mediated biotin–deoxyuridine triphosphate nick-end labeling) staining. Furthermore, levels of oxidants and antioxidants were determined by biochemical analyzes of the tissues. Results: Glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) levels were significantly higher in the NEC group than in the control group in all gastrointestinal tract regions examined. Similar to the control group, GSH-Px and MDA were found to be low only in the cecum in the group treated with flavonoids. NEC damage score and apoptotic index in all 3 regions examined were significantly higher in the NEC group than in the control and treatment groups. The apoptotic index values in the treatment group were similar in the stomach and cecum, and the NEC damage score was similar to those in the control group only in the cecum. Conclusions: Hsd and diosmin treatment significantly reduces the severity of NEC-induced damage and apoptotic cell death, especially in the cecum.

High-fat diet-induced resistance to helminth infection via alternative induction of type 2 immunity

Gastrointestinal nematode infections cause morbidity and socioeconomic loss in the most deprived communities. The shift in the context of obesity has led to spatial overlap with endemic gastrointestinal nematode regions resulting in the emergence of a novel comorbidity. Despite this, the impact of a high-fat diet (HFD) on immune-regulated protection against gastrointestinal infections remains largely unknown. We employed the murine model of nematode infection, Trichuris muris, to investigate the effect of an HFD on the immune response against chronic infection. Surprisingly, diet-induced obesity drove parasite expulsion in both single and repeated trickle low doses of T. muris eggs. Mechanistically, an HFD increased the expression of the ST2 receptor on CD4+ T cells, priming an enhanced type 2 helper T (Th2) cell cytokine production following interleukin (IL)-33 stimulation ex vivo. Despite IL-33-/- mice demonstrating that IL-33 is not critical for host protective immunity to T. muris under a conventional diet, HFD-fed T-cell deplete mice adoptively transferred with ST2-/- CD4 T cells were unable to expel a T. muris infection unlike those transferred with ST2-sufficient cells. Collectively, this study demonstrates that an HFD primes CD4+ T cells to utilize the IL-33-ST2 axis in a novel induction of type 2 immunity, providing insights into the emerging comorbidities of obesity and nematode infection.

Biodistribution of 89Zr-DFO-labeled avian pathogenic Escherichia coli outer membrane vesicles by PET imaging in chickens

Avian pathogenic Escherichia coli (APEC) is a serious systemic infectious disease in poultry infections, causing severe economic losses to the poultry industry. Previous studies have shown that secretion of virulence proteins was required for the pathogenicity of APEC through the secretion system. Outer membrane vesicles (OMVs) are a generalized secretion system of Gram-negative bacteria that play a key role in the long-distance delivery of virulence factors, but whether they are associated with the pathogenic mechanism of APEC has not been determined. In this study, OMVs were purified and characterized from AE17 (O2 serotype) by ultracentrifugation and density gradient centrifugation and their protein cargo was identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, 89Zr was labeled after chelating AE17 OMVs by DFO and positron emission tomography PET imaging was used to track 89Zr-DFO-OMVs in chickens and to pathologically analyze the distribution sites. This study showed that AE17 OMVs were membrane vesicles ranging in size from 20 to 200 nm and proteomic analysis revealed the presence of virulence proteins, including adhesion proteins OmpA, OmpC, OmpF, OmpX, FimH, FimC and FigE, and serum resistance proteins OmpT and MliC and immune response regulator proteins (FliC). In addition, in vivo PET imaging to track the biodistribution of AE17 OMVs showed that AE17 OMVs were taken up by the lung region and the gastrointestinal and renal regions but were not detected in other areas. Pathological analysis of the tissue sites where AE17 OMVs were ingested showed inflammatory responses and damage. These findings suggested that AE17 OMVs not only contained a group of virulence proteins associated with AE17 infection but can also deliver these virulence proteins over long distances and caused tissue inflammatory damage. Our study revealed a previously unidentified causative microbial signal in the pathogenesis of APEC that could aid in the development of vaccines and antibiotics effective against APEC.