Morphogenesis and maturation of the embryonic and postnatal intestine

Pro-inflammatory T cells-derived cytokines enhance the maturation of the human fetal intestinal epithelial barrier

Small intestine (SI) maturation during early life is pivotal in preventing the onset of gut diseases. In this study we interrogated the milestones of SI development by gene expression profiling and ingenuity pathway analyses. We identified a set of cytokines as main regulators of changes observed across different developmental stages. Upon cytokines stimulation, with IFNγ as the most contributing factor, human fetal organoids (HFOs) increase brush border gene expression and enzyme activity as well as trans-epithelial electrical resistance. Electron microscopy revealed developed brush border and loss of fetal cell characteristics in HFOs upon cytokine stimulation. We identified T cells as major source of IFNγ production in the fetal SI lamina propria. Co-culture of HFOs with T cells recapitulated the major effects of cytokine stimulation. Our findings underline pro-inflammatory cytokines derived from T cells as pivotal factors inducing functional SI maturation in vivo and capable of modulating the barrier maturation of HFOs in vitro.

Placental Epigenome Impacts Fetal Development: Effects of Maternal Nutrients and Gut Microbiota

Evidence is emerging on the role of maternal diet, gut microbiota, and other lifestyle factors in establishing lifelong health and disease, which are determined by transgenerationally inherited epigenetic modifications. Understanding epigenetic mechanisms may help identify novel biomarkers for gestation-related exposure, burden, or disease risk. Such biomarkers are essential for developing tools for the early detection of risk factors and exposure levels. It is necessary to establish an exposure threshold due to nutrient deficiencies or other environmental factors that can result in clinically relevant epigenetic alterations that modulate disease risks in the fetus. This narrative review summarizes the latest updates on the roles of maternal nutrients (n-3 fatty acids, polyphenols, vitamins) and gut microbiota on the placental epigenome and its impacts on fetal brain development. This review unravels the potential roles of the functional epigenome for targeted intervention to ensure optimal fetal brain development and its performance in later life.

Diversity and host interaction of the gut microbiota in specific pathogen-free pigs

Pigs are widely used as animal models in various studies related to humans. The interaction between the gut microbiota and the host has significant effects on the host's health and disease status. However, although there have been many studies investigating the pig gut microbiota, the findings have been inconsistent due to variations in rearing conditions. Interactions between the gut microbiota and host have not been fully explored in pigs. Specific pathogen-free (SPF) pigs are ideal non-primate large animals to study the interactions between the gut microbiota and the host. In this study, we performed high-throughput sequencing analysis of the gut microbiota and the gut tissue transcriptome of six SPF pigs to provide a systematic understanding of the composition, function, and spatial distribution of gut microbiota in SPF pigs. We identified significant differences in microbial diversity and functionality among different gastrointestinal tract sites. Metagenomics data analysis revealed significant differences in alpha diversity and beta diversity of microbiota in different gastrointestinal sites of SPF pigs. Additionally, transcriptomic data indicated significant differences in gene expression as well as KEGG and GO functional enrichment between the small intestine and large intestine. Furthermore, by combining microbial metagenomics and host transcriptomics analyses, specific correlations were found between gut microbiota and host genes. These included a negative correlation between the TCN1 gene and Prevotella dentalis, possibly related to bacterial metabolic pathways involving vitamin B12, and a positive correlation between the BDH1 gene and Roseburia hominis, possibly because both are involved in fatty acid metabolism. These findings lay the groundwork for further exploration of the co-evolution between the microbiota and the host, specifically in relation to nutrition, metabolism, and immunity. In conclusion, we have elucidated the diversity of the gut microbiota in SPF pigs and conducted a detailed investigation into the interactions between the gut microbiota and host gene expression. These results contribute to our understanding of the intricate dynamics between the gut microbiota and the host, offering important references for advancements in life science research, bioproduct production, and sustainable development in animal husbandry.

How do different concentrations of aluminum and zinc affect the survival, body size, morphology and immune system of Physalaemus cuvieri (Fitzinger, 1826) tadpole?

The assessment of amphibian responses as bioindicators of exposure to chemical pollutants is an important tool for conservation of native species. This study aimed to investigate the effects of chronic aluminum (Al) and zinc (Zn) exposure on survival, body size, morphology (malformations), and immune system (leukocyte profile) in P. cuvieri tadpoles. Ecotoxicological analyses were performed utilizing chronic toxicity tests in which 210 tadpoles at the 25th Gosner developmental stage were exposed to Al and Zn. Individuals of P. cuvieri were maintained in glass containers containing various concentrations of aluminum sulfate (0.1, 0.2, or 0.3 mg/L) and zinc sulfate (0.18, 0.27 or 0.35 mg/L), and tests were performed in triplicate. After 14 days, amphibians were weighed, measured and survival rate, malformations in the oral and intestine apparatus, leukocyte profile, and ratio between neutrophils and lymphocytes determined. The differing concentrations of Al and Zn did not produce lethality in P. cuvieri where 95% of the animals survived 326 hr following metal exposure. Individuals exposed to Zn achieved greater body growth and weight gain compared to controls. Aluminum increased weight gain compared controls. These metals also produced malformations of the oral and intestine apparatus and enhanced occurrence of hemorrhages, especially at the highest doses. Lymphocytes were the predominant cells among leukocytes, with lymphopenia and neutrophilia observed following Al and Zn treatment, as evidenced by elevated neutrophil/lymphocyte ratio, an important indicator of stress in animals. Data suggest that further studies need to be carried out, even with metal concentrations higher than those prescribed by CONAMA, to ensure the conservation of this species.

Lrig1 drives cryptogenesis and restrains proliferation during colon development

Growth and specification of the mouse intestine occurs in utero and concludes after birth. Although numerous studies have examined this developmental process in the small intestine, far less is known about the cellular and molecular cues required for colon development. In this study, we examine the morphological events leading to crypt formation, epithelial cell differentiation, proliferation, and the emergence and expression of a stem and progenitor cell marker Lrig1. Through multicolor lineage tracing, we show Lrig1-expressing cells are present at birth and behave as stem cells to establish clonal crypts within 3 wk of life. In addition, we use an inducible knockout mouse to eliminate Lrig1 and show Lrig1 restrains proliferation within a critical developmental time window, without impacting colonic epithelial cell differentiation. Our study illustrates morphological changes during crypt development and the importance of Lrig1 in the developing colon.NEW & NOTEWORTHY Our studies define the importance of studying Lrig1 in colon development. We address a critical gap in the intestinal development literature and provide new information about the molecular cues that guide colon development. Using a novel, inducible knockout of Lrig1, we show Lrig1 is required for appropriate colon epithelial growth and illustrate the importance of Lrig1-expressing cells in the establishment of colonic crypts.

Integrative genome-scale analyses reveal post-transcriptional signatures of early human small intestinal development in a directed differentiation organoid model

BACKGROUND

MicroRNAs (miRNAs) are important post-transcriptional gene regulators controlling cellular lineage specification and differentiation during embryonic development, including the gastrointestinal system. However, miRNA-mediated regulatory mechanisms involved in early embryonic development of human small intestine (SI) remains underexplored. To explore candidate roles for miRNAs in prenatal SI lineage specification in humans, we used a multi-omic analysis strategy in a directed differentiation model that programs human pluripotent stem cells toward the SI lineage.

RESULTS

We leveraged small RNA-seq to define the changing miRNA landscape, and integrated chromatin run-on sequencing (ChRO-seq) and RNA-seq to define genes subject to significant post-transcriptional regulation across the different stages of differentiation. Small RNA-seq profiling revealed temporal dynamics of miRNA signatures across different developmental events of the model, including definitive endoderm formation, SI lineage specification and SI regional patterning. Our multi-omic, integrative analyses showed further that the elevation of miR-182 and reduction of miR-375 are key events during SI lineage specification. We demonstrated that loss of miR-182 leads to an increase in the foregut master marker SOX2. We also used single-cell analyses in murine adult intestinal crypts to support a life-long role for miR-375 in the regulation of Zfp36l2. Finally, we uncovered opposing roles of SMAD4 and WNT signaling in regulating miR-375 expression during SI lineage specification. Beyond the mechanisms highlighted in this study, we also present a web-based application for exploration of post-transcriptional regulation and miRNA-mediated control in the context of early human SI development.

CONCLUSION

The present study uncovers a novel facet of miRNAs in regulating prenatal SI development. We leveraged multi-omic, systems biology approaches to discover candidate miRNA regulators associated with early SI developmental events in a human organoid model. In this study, we highlighted miRNA-mediated post-transcriptional regulation relevant to the event of SI lineage specification. The candidate miRNA regulators that we identified for the other stages of SI development also warrant detailed characterization in the future.

'Chip'-ing away at morphogenesis - application of organ-on-chip technologies to study tissue morphogenesis

Emergent cell behaviors that drive tissue morphogenesis are the integrated product of instructions from gene regulatory networks, mechanics and signals from the local tissue microenvironment. How these discrete inputs intersect to coordinate diverse morphogenic events is a critical area of interest. Organ-on-chip technology has revolutionized the ability to construct and manipulate miniaturized human tissues with organotypic three-dimensional architectures in vitro. Applications of organ-on-chip platforms have increasingly transitioned from proof-of-concept tissue engineering to discovery biology, furthering our understanding of molecular and mechanical mechanisms that operate across biological scales to orchestrate tissue morphogenesis. Here, we provide the biological framework to harness organ-on-chip systems to study tissue morphogenesis, and we highlight recent examples where organ-on-chips and associated microphysiological systems have enabled new mechanistic insight in diverse morphogenic settings. We further highlight the use of organ-on-chip platforms as emerging test beds for cell and developmental biology.

Effects of grape seed procyanidins on antioxidant function, barrier function, microbial community, and metabolites of cecum in geese

The gut is the first line of defense for body health and is essential to the overall health of geese. Grape seed procyanidins (GSPs) are proverbial for their antioxidant, anti-inflammatory, and microflora-regulating capabilities. This study aimed to inquire into the influences of dietary GSPs on the intestinal antioxidant function, barrier function, microflora, and metabolites of geese based on 16S rRNA sequencing and metabolomics. In total, 240 twenty-one-day-old Sichuan white geese were randomly divided into 4 groups, each of which was supplied with 1 of 4 diets: basal diet or a basal diet supplemented with 50, 100, or 150 mg/kg GSPs. Diets supplemented with GSPs at different concentrations significantly increased the total antioxidant capacity and superoxide dismutase activity in cecal mucosa (P < 0.001). Dietary supplementation with 50 or 100 mg/kg GSPs significantly increased catalase activity (P < 0.001). The serum diamine oxidase, D-lactic acid, and endotoxin concentrations were decreased by GSP supplementation in the goose diet. Dietary GSP supplementation increased microbial richness and diversity, enhanced the relative abundance of Firmicutes, and decreased that of Bacteroidetes in the cecum. Diets supplemented with 50 or 100 mg/kg GSPs enriched Eubacterium coprostanoligenes and Faecalibacterium. Dietary GSPs substantially raised the acetic and propionic acid concentrations in the cecum. The butyric acid concentration increased when the GSP dosage was 50 or 100 mg/kg. Additionally, dietary GSPs increased the levels of metabolites that belong to lipids and lipid-like molecules or organic acids and derivatives. Dietary GSP supplementation at 100 or 150 mg/kg reduced the levels of spermine (a source of cytotoxic metabolites) and N-acetylputrescine, which promotes in-vivo inflammation. In conclusion, dietary supplementation with GSPs was beneficial to gut health in geese. Dietary GSPs improved antioxidant activity; protected intestinal barrier integrity; increased the abundance and diversity of cecal microflora; promoted the proliferation of some beneficial bacteria; increased the production of acetic, propionic, and butyric acids in the cecum; and downregulated metabolites associated with cytotoxicity and inflammation. These results offer a strategy for promoting intestinal health in farmed geese.

The Impact of Maternal Gut Microbiota during Pregnancy on Fetal Gut-Brain Axis Development and Life-Long Health Outcomes

Gut microbiota plays a critical role in physiological regulation throughout life and is specifically modified to meet the demands of individual life stages and during pregnancy. Maternal gut microbiota is uniquely adapted to the pregnancy demands of the mother and the developing fetus. Both animal studies in pregnant germ-free rodents and human studies have supported a critical association between the composition of maternal microbiota during pregnancy and fetal development. Gut microbiota may also contribute to the development of the fetal gut-brain axis (GBA), which is increasingly recognized for its critical role in health and disease. Most studies consider birth as the time of GBA activation and focus on postnatal GBA development. This review focuses on GBA development during the prenatal period and the impact of maternal gut microbiota on fetal GBA development. It is hypothesized that adaptation of maternal gut microbiota to pregnancy is critical for the GBA prenatal development and maturation of GBA postnatally. Consequently, factors affecting maternal gut microbiota during pregnancy, such as maternal obesity, diet, stress and depression, infection, and medication, also affect fetal GBA development and are critical for GBA activity postnatally. Altered maternal gut microbiota during gestation has been shown to have long-term impact postnatally and multigenerational effects. Thus, understanding the impact of maternal gut microbiota during pregnancy on fetal GBA development is crucial for managing fetal, neonatal, and adult health, and should be included among public health priorities.

Mammalian Intestinal Development and Differentiation-The State of the Art

The development of the mammalian intestine, from its earliest origins as a morphologically uniform sheet of endoderm cells during gastrulation into the complex organ system that is essential for the life of the organism, is a truly fascinating process. During midgestation development, reciprocal interactions between endoderm-derived epithelium and mesoderm-derived mesenchyme enable villification, or the conversion of a radially symmetric pseudostratified epithelium into the functional subdivision of crypts and villi. Once a mature crypt-villus axis is established, proliferation and differentiation of new epithelial cells continue throughout life. Spatially localized signals including the wingless and Int-1, fibroblast growth factor, and Hippo systems, among others, ensure that new cells are being born continuously in the crypt. As cells exit the crypt compartment, a gradient of bone morphogenetic protein signaling limits proliferation to allow for the specification of multiple mature cell types. The first major differentiation decision is dependent on Notch signaling, which specifies epithelial cells into absorptive and secretory lineages. The secretory lineage is subdivided further into Paneth, goblet, tuft, and enteroendocrine cells via a complex network of transcription factors. Although some of the signaling molecules are produced by epithelial cells, critical components are derived from specialized crypt-adjacent mesenchymal cells termed telocytes, which are marked by Forkhead box l1, GLI Family Zinc Finger 1, and platelet-derived growth factor receptor α. The crucial nature of these processes is evidenced by the multitude of intestinal disorders such as colorectal cancer, short-bowel syndrome, and inflammatory bowel disease, which all reflect perturbations of the development and/or differentiation of the intestine.

Building better barriers: how nutrition and undernutrition impact pediatric intestinal health

Chronic undernutrition is a major cause of death for children under five, leaving survivors at risk for adverse long-term consequences. This review focuses on the role of nutrients in normal intestinal development and function, from the intestinal epithelium, to the closely-associated mucosal immune system and intestinal microbiota. We examine what is known about the impacts of undernutrition on intestinal physiology, with focus again on the same systems. We provide a discussion of existing animal models of undernutrition, and review the evidence demonstrating that correcting undernutrition alone does not fully ameliorate effects on intestinal function, the microbiome, or growth. We review efforts to treat undernutrition that incorporate data indicating that improved recovery is possible with interventions focused not only on delivery of sufficient energy, macronutrients, and micronutrients, but also on efforts to correct the abnormal intestinal microbiome that is a consequence of undernutrition. Understanding of the role of the intestinal microbiome in the undernourished state and correction of the phenotype is both complex and a subject that holds great potential to improve recovery. We conclude with critical unanswered questions in the field, including the need for greater mechanistic research, improved models for the impacts of undernourishment, and new interventions that incorporate recent research gains. This review highlights the importance of understanding the mechanistic effects of undernutrition on the intestinal ecosystem to better treat and improve long-term outcomes for survivors.

Transcriptional and epigenomic profiling identifies YAP signaling as a key regulator of intestinal epithelium maturation

During intestinal organogenesis, equipotent epithelial progenitors mature into phenotypically distinct stem cells that are responsible for lifelong maintenance of the tissue. While the morphological changes associated with the transition are well characterized, the molecular mechanisms underpinning the maturation process are not fully understood. Here, we leverage intestinal organoid cultures to profile transcriptional, chromatin accessibility, DNA methylation, and three-dimensional (3D) chromatin conformation landscapes in fetal and adult epithelial cells. We observed prominent differences in gene expression and enhancer activity, which are accompanied by local changes in 3D organization, DNA accessibility, and methylation between the two cellular states. Using integrative analyses, we identified sustained Yes-Associated Protein (YAP) transcriptional activity as a major gatekeeper of the immature fetal state. We found the YAP-associated transcriptional network to be regulated at various levels of chromatin organization and likely to be coordinated by changes in extracellular matrix composition. Together, our work highlights the value of unbiased profiling of regulatory landscapes for the identification of key mechanisms underlying tissue maturation.

An organoid-based CRISPR-Cas9 screen for regulators of intestinal epithelial maturation and cell fate

Generation of functionally mature organs requires exquisite control of transcriptional programs governing cell state transitions during development. Despite advances in understanding the behavior of adult intestinal stem cells and their progeny, the transcriptional regulators that control the emergence of the mature intestinal phenotype remain largely unknown. Using mouse fetal and adult small intestinal organoids, we uncover transcriptional differences between the fetal and adult state and identify rare adult-like cells present in fetal organoids. This suggests that fetal organoids have an inherent potential to mature, which is locked by a regulatory program. By implementing a CRISPR-Cas9 screen targeting transcriptional regulators expressed in fetal organoids, we establish Smarca4 and Smarcc1 as important factors safeguarding the immature progenitor state. Our approach demonstrates the utility of organoid models in the identification of factors regulating cell fate and state transitions during tissue maturation and reveals that SMARCA4 and SMARCC1 prevent precocious differentiation during intestinal development.

Dietary supplementation with probiotics increases growth performance, improves the intestinal mucosal barrier and activates the Wnt/β-catenin pathway activity in chicks

BACKGROUND

Probiotics comprise effective feed additives that can replace antibiotics in animal livestock production. However, mono-strain probiotics appear less effective because of their instability. Therefore, the present study aimed to investigate dietary supplementation with compound probiotics (CPP) on growth performance, diarrhea rate and intestinal mucosal barrier, as well as the possible molecular mechanism, in chicks. In total, 360 1-day-old chicks of the Hy-Line Brown Chicks were randomly divided into the control group (CON, basal diet), chlortetracycline group (500 mg kg^-1 CTC) and compound probiotics group (1000 mg kg^-1 CPP, consisting of Bacillus subtilis, Bacillus licheniformis, Enterococcus faecium and yeast). The experiment period was 56 days.

RESULTS

The results showed that, in comparison with the CON group, CPP significantly increased the average daily feed intake and average daily gain of chicks and reduced diarrhea (P < 0.05). The probiotic group exhibited increased immune organ (i.e. spleen and thymus) mass and increased levels of serum immunoglobulin (Ig)A, IgM and IgG (P < 0.05) compared to the CTC group. In addition, the jejunal mass and morphology were improved in the probiotic group (P < 0.05). Moreover, CPP reinforced jejunal barrier function, as indicated by increased transepithelial electrical resistance, protein expression of occludin and claudin-1, and diamine oxidase levels in the jejunum (P < 0.05). Likewise, enhanced fluorescence signals of proliferating cell nuclear antigen-labeled mitotic cells and villin-labeled absorptive cells in the jejunum (P < 0.05) suggested that CPP promoted intestinal stem cells activity. Mechanistically, the Wnt/β-catenin signaling pathway, including β-catenin, TCF4, c-Myc, cyclin D1 and Lgr5, was amplified in the jejunum by CPP addition (P < 0.05).

CONCLUSION

The present study demonstrated that dietary supplementation with CPP reinforced the jejunal epithelial integrity by activating Wnt/β-catenin signaling and enhanced immune function in chicks. © 2023 Society of Chemical Industry.

Effect of Purslane (Portulaca oleracea L.) on Intestinal Morphology, Digestion Activity and Microbiome of Chinese Pond Turtle (Mauremys reevesii) during Aeromonas hydrophila Infection

Large-scale mortality due to Aeromonas hydrophila (A. hydrophila) infection has considerably decreased the yield of the Chinese pond turtle (Mauremys reevesii). Purslane is a naturally active substance with a wide range of pharmacological functions, but its antibacterial effect on Chinese pond turtles infected by A. hydrophila infection is still unknown. In this study, we investigated the effect of purslane on intestinal morphology, digestion activity, and microbiome of Chinese pond turtles during A. hydrophila infection. The results showed that purslane promoted epidermal neogenesis of the limbs and increased the survival and feeding rates of Chinese pond turtles during A. hydrophila infection. Histopathological observation and enzyme activity assay indicated that purslane improved the intestinal morphology and digestive enzyme (α-amylase, lipase and pepsin) activities of Chinese pond turtle during A. hydrophila infection. Microbiome analysis revealed that purslane increased the diversity of intestinal microbiota with a significant decrease in the proportion of potentially pathogenic bacteria (such as Citrobacter freundii, Eimeria praecox, and Salmonella enterica) and an increase in the abundance of probiotics (such as uncultured Lactobacillus). In conclusion, our study uncovers that purslane improves intestinal health to protect Chinese pond turtles against A. hydrophila infection.

Prebiotic Supplementation during Lactation Affects Microbial Colonization in Postnatal-Growth-Restricted Mice

BACKGROUND

An inadequate perinatal nutritional environment can alter the maturation of the intestinal barrier and promote long-term pathologies such as metabolic syndrome or chronic intestinal diseases. The intestinal microbiota seems to play a determining role in the development of the intestinal barrier. In the present study, we investigated the impact of consuming an early postnatal prebiotic fiber (PF) on growth, intestinal morphology and the microbiota at weaning in postnatal-growth-restricted mice (PNGR).

METHODS

Large litters (15 pups/mother) were generated from FVB/NRj mice to induce PNGR at postnatal day 4 (PN4) and compared to control litters (CTRL, 8 pups/mother). PF (a resistant dextrin) or water was orally administered once daily to the pups from PN8 to PN20 (3.5 g/kg/day). Intestinal morphology was evaluated at weaning (PN21) using the ileum and colon. Microbial colonization and short-chain fatty acid (SCFA) production were investigated using fecal and cecal contents.

RESULTS

At weaning, the PNGR mice showed decreased body weight and ileal crypt depth compared to the CTRL. The PNGR microbiota was associated with decreased proportions of the Lachnospiraceae and Oscillospiraceae families and the presence of the Akkermansia family and Enterococcus genus compared to the CTRL pups. The propionate concentrations were also increased with PNGR. While PF supplementation did not impact intestinal morphology in the PNGR pups, the proportions of the Bacteroides and Parabacteroides genera were enriched, but the proportion of the Proteobacteria phylum was reduced. In the CTRL pups, the Akkermansia genus (Verrucomicrobiota phylum) was present in the PF-supplemented CTRL pups compared to the water-supplemented ones.

CONCLUSIONS

PNGR alters intestinal crypt maturation in the ileum at weaning and gut microbiota colonization. Our data support the notion that PF supplementation might improve gut microbiota establishment during the early postnatal period.

RETROFIT: Reference-free deconvolution of cell-type mixtures in spatial transcriptomics

Spatial transcriptomics (ST) profiles gene expression in intact tissues. However, ST data measured at each spatial location may represent gene expression of multiple cell types, making it difficult to identify cell-type-specific transcriptional variation across spatial contexts. Existing cell-type deconvolutions of ST data often require single-cell transcriptomic references, which can be limited by availability, completeness and platform effect of such references. We present RETROFIT, a reference-free Bayesian method that produces sparse and interpretable solutions to deconvolve cell types underlying each location independent of single-cell transcriptomic references. Results from synthetic and real ST datasets acquired by Slide-seq and Visium platforms demonstrate that RETROFIT outperforms existing reference-based and reference-free methods in estimating cell-type composition and reconstructing gene expression. Applying RETROFIT to human intestinal development ST data reveals spatiotemporal patterns of cellular composition and transcriptional specificity. RETROFIT is available at https://bioconductor.org/packages/release/bioc/html/retrofit.html.

TCF7L1 Controls the Differentiation of Tuft Cells in Mouse Small Intestine

Continuous and rapid renewal of the intestinal epithelium depends on intestinal stem cells (ISCs). A large repertoire of transcription factors mediates the correct maintenance and differentiation of ISCs along either absorptive or secretory lineages. In the present study, we addressed the role of TCF7L1, a negative regulator of WNT signalling, in embryonic and adult intestinal epithelium using conditional mouse mutants. We found that TCF7L1 prevents precocious differentiation of the embryonic intestinal epithelial progenitors towards enterocytes and ISCs. We show that Tcf7l1 deficiency leads to upregulation of the Notch effector Rbp-J, resulting in a subsequent loss of embryonic secretory progenitors. In the adult small intestine, TCF7L1 is required for the differentiation of secretory epithelial progenitors along the tuft cell lineage. Furthermore, we show that Tcf7l1 promotes the differentiation of enteroendocrine D- and L-cells in the anterior small intestine. We conclude that TCF7L1-mediated repression of both Notch and WNT pathways is essential for the correct differentiation of intestinal secretory progenitors.

Endosulfan affects embryonic development synergistically under elevated ambient temperature

In the present study, we determined the developmental toxicity of endosulfan at an elevated ambient temperature using the zebrafish animal model. Zebrafish embryos of various developmental stages were exposed to endosulfan through E3 medium, raised under two selected temperature conditions (28.5 °C and an elevated temperature of 35 °C), and monitored under the microscope. Zebrafish embryos of very early developmental stages (cellular cleavage stages, such as the 64-cell stage) were highly sensitive to the elevated temperature as 37.5% died and 47.5% developed into amorphous type, while only 15.0% of embryos developed as normal embryos without malformation. Zebrafish embryos that were exposed concurrently to endosulfan and an elevated temperature showed stronger developmental defects (arrested epiboly progress, shortened body length, curved trunk) compared to the embryos exposed to either endosulfan or an elevated temperature. The brain structure of the embryos that concurrently were exposed to the elevated temperature and endosulfan was either incompletely developed or malformed. Furthermore, the stress-implicated genes hsp70, p16, and smp30 regulations were synergistically affected by endosulfan treatment under the elevated thermal condition. Overall, the elevated ambient temperature synergistically enhanced the developmental toxicity of endosulfan in zebrafish embryos.

The Role of Lrig1 in the Development of the Colonic Epithelium

Growth and specification of the mouse intestine occurs in utero and concludes after birth. While numerous studies have examined this developmental process in the small intestine, far less is known about the cellular and molecular cues required for colon development. In this study, we examine the morphological events leading to crypt formation, epithelial cell differentiation, areas of proliferation, and the emergence and expression of a stem and progenitor cell marker Lrig1. Through multicolor lineage tracing, we show Lrig1 expressing cells are present at birth and behave as stem cells to establish clonal crypts within three weeks after birth. In addition, we use an inducible knockout mouse to eliminate Lrig1 during colon development and show loss of Lrig1 restrains proliferation within a critical developmental time window, without impacting colonic epithelial cell differentiation. Our study illustrates the morphological changes that occur during crypt development and the importance of Lrig1 in the developing colon.

Transplanted human intestinal organoids: a resource for modeling human intestinal development

The in vitro differentiation of pluripotent stem cells into human intestinal organoids (HIOs) has served as a powerful means for creating complex three-dimensional intestinal structures. Owing to their diverse cell populations, transplantation into an animal host is supported with this system and allows the temporal formation of fully laminated structures, including crypt-villus architecture and smooth muscle layers that resemble native human intestine. Although the endpoint of HIO engraftment has been well described, here we aim to elucidate the developmental stages of HIO engraftment and establish whether it parallels fetal human intestinal development. We analyzed a time course of transplanted HIOs histologically at 2, 4, 6 and 8 weeks post-transplantation, and demonstrated that HIO maturation closely resembles key stages of fetal human intestinal development. We also utilized single-nuclear RNA sequencing to determine and track the emergence of distinct cell populations over time, and validated our transcriptomic data through in situ protein expression. These observations suggest that transplanted HIOs do indeed recapitulate early intestinal development, solidifying their value as a human intestinal model system.

Regenerative medicine: current research and perspective in pediatric surgery

The field of regenerative medicine, encompassing several disciplines including stem cell biology and tissue engineering, continues to advance with the accumulating research on cell manipulation technologies, gene therapy and new materials. Recent progress in preclinical and clinical studies may transcend the boundaries of regenerative medicine from laboratory research towards clinical reality. However, for the ultimate goal to construct bioengineered transplantable organs, a number of issues still need to be addressed. In particular, engineering of elaborate tissues and organs requires a fine combination of different relevant aspects; not only the repopulation of multiple cell phenotypes in an appropriate distribution but also the adjustment of the host environmental factors such as vascularisation, innervation and immunomodulation. The aim of this review article is to provide an overview of the recent discoveries and development in stem cells and tissue engineering, which are inseparably interconnected. The current status of research on tissue stem cells and bioengineering, and the possibilities for application in specific organs relevant to paediatric surgery have been specifically focused and outlined.

A Cre knockin mouse reveals specific expression of Agouti gene in mesenchymal lineage cells in multiple organs and provides a unique tool for conditional gene targeting

The mouse Agouti gene encodes a paracrine signaling factor which promotes melanocytes to produce yellow instead of black pigment. It has been reported that Agouti mRNA is confined to the dermal papilla after birth in various mammalian species. In this study, we created and characterized a knockin mouse strain in which Cre recombinase was expressed in-frame with endogenous Agouti coding sequence. The Agouti-Cre mice were bred with reporter mice (Rosa26-tdTomato or Rosa26-ZsGreen) to trace the lineage of Agouti-expressing cells during development. In skin, the reporter was detected in some dermal fibroblasts at the embryonic stage and in all dermal fibroblasts postnatally. It was also expressed in all mesenchymal lineage cells in other organs/tissues, including eyes, tongue, muscle, intestine, adipose, prostate and testis. Interestingly, the reporter expression was excluded from epithelial cells in the above organs/tissues. In brain, the reporter was observed in the outermost meningeal fibroblasts. Our work helps to illustrate the Agouti expression pattern during development and provides a valuable mouse strain for conditional gene targeting in mesenchymal lineage cells in multiple organs.

EPIREGULIN creates a developmental niche for spatially organized human intestinal enteroids

Epithelial organoids derived from intestinal tissue, called enteroids, recapitulate many aspects of the organ in vitro and can be used for biological discovery, personalized medicine, and drug development. Here, we interrogated the cell signaling environment within the developing human intestine to identify niche cues that may be important for epithelial development and homeostasis. We identified an EGF family member, EPIREGULIN (EREG), which is robustly expressed in the developing human crypt. Enteroids generated from the developing human intestine grown in standard culture conditions, which contain EGF, are dominated by stem and progenitor cells and feature little differentiation and no spatial organization. Our results demonstrate that EREG can replace EGF in vitro, and EREG leads to spatially resolved enteroids that feature budded and proliferative crypt domains and a differentiated villus-like central lumen. Multiomic (transcriptome plus epigenome) profiling of native crypts, EGF-grown enteroids, and EREG-grown enteroids showed that EGF enteroids have an altered chromatin landscape that is dependent on EGF concentration, downregulate the master intestinal transcription factor CDX2, and ectopically express stomach genes, a phenomenon that is reversible. This is in contrast to EREG-grown enteroids, which remain intestine like in culture. Thus, EREG creates a homeostatic intestinal niche in vitro, enabling interrogation of stem cell function, cellular differentiation, and disease modeling.

Molecular Mechanisms of Hyperoxia-Induced Neonatal Intestinal Injury

Oxygen therapy is important for newborns. However, hyperoxia can cause intestinal inflammation and injury. Hyperoxia-induced oxidative stress is mediated by multiple molecular factors and leads to intestinal damage. Histological changes include ileal mucosal thickness, intestinal barrier damage, and fewer Paneth cells, goblet cells, and villi, effects which decrease the protection from pathogens and increase the risk of necrotizing enterocolitis (NEC). It also causes vascular changes with microbiota influence. Hyperoxia-induced intestinal injuries are influenced by several molecular factors, including excessive nitric oxide, the nuclear factor-κB (NF-κB) pathway, reactive oxygen species, toll-like receptor-4, CXC motif ligand-1, and interleukin-6. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and some antioxidant cytokines or molecules including interleukin-17D, n-acetylcysteine, arginyl-glutamine, deoxyribonucleic acid, cathelicidin, and health microbiota play a role in preventing cell apoptosis and tissue inflammation from oxidative stress. NF-κB and Nrf2 pathways are essential to maintain the balance of oxidative stress and antioxidants and prevent cell apoptosis and tissue inflammation. Intestinal inflammation can lead to intestinal damage and death of the intestinal tissue, such as in NEC. This review focuses on histologic changes and molecular pathways of hyperoxia-induced intestinal injuries to establish a framework for potential interventions.

Necrotizing enterocolitis in premature infants-A defect in the brakes? Evidence from clinical and animal studies

A key aspect of postnatal intestinal adaptation is the establishment of symbiotic relationships with co-evolved gut microbiota. Necrotizing enterocolitis (NEC) is the most severe disease arising from failure in postnatal gut adaptation in premature infants. Although pathological activation of intestinal Toll-like receptors (TLRs) is believed to underpin NEC pathogenesis, the mechanisms are incompletely understood. We postulate that unregulated aberrant TLR activation in NEC arises from a failure in intestinal-specific mechanisms that tamponade TLR signaling (the brakes). In this review, we discussed the human and animal studies that elucidate the developmental mechanisms inhibiting TLR signaling in the postnatal intestine (establishing the brakes). We then evaluate evidence from preclinical models and human studies that point to a defect in the inhibition of TLR signaling underlying NEC. Finally, we provided a framework for the assessment of NEC risk by screening for signatures of TLR signaling and for NEC prevention by TLR-targeted therapy in premature infants.

Stromal regulation of the intestinal barrier

The intestinal barrier is a complex structure that allows the absorption of nutrients while ensuring protection against intestinal pathogens and balanced immunity. The development and maintenance of a functional intestinal barrier is a multifactorial process that is only partially understood. Here we review novel findings on the emerging role of mesenchymal cells in this process using insights gained from lineage tracing approaches, Cre-based gene deletion, and single-cell transcriptomics. The current evidence points toward a key organizer role for distinct mesenchymal lineages in intestinal development and homeostasis, regulating both epithelial and immune components of the intestinal barrier. We further discuss recent findings on functional mesenchymal heterogeneity and implications for intestinal regeneration and inflammatory intestinal pathologies.

In situ modulation of intestinal organoid epithelial curvature through photoinduced viscoelasticity directs crypt morphogenesis

Spatiotemporally coordinated transformations in epithelial curvature are necessary to generate crypt-villus structures during intestinal development. However, the temporal regulation of mechanotransduction pathways that drive crypt morphogenesis remains understudied. Intestinal organoids have proven useful to study crypt morphogenesis in vitro, yet the reliance on static culture scaffolds limits the ability to assess the temporal effects of changing curvature. Here, a photoinduced hydrogel cross-link exchange reaction is used to spatiotemporally alter epithelial curvature and study how dynamic changes in curvature influence mechanotransduction pathways to instruct crypt morphogenesis. Photopatterned curvature increased membrane tension and depolarization, which was required for subsequent nuclear localization of yes-associated protein 1 (YAP) observed 24 hours following curvature change. Curvature-directed crypt morphogenesis only occurred following a delay in the induction of differentiation that coincided with the delay in spatially restricted YAP localization, indicating that dynamic changes in curvature initiate epithelial curvature-dependent mechanotransduction pathways that temporally regulate crypt morphogenesis.

Comparison of the Pig Breeds in the Small Intestinal Morphology and Digestive Functions at Different Ages

The small intestine is the main site for digestion and absorption of nutrients, and the development of the small intestine can be affected by several factors, such as diet composition, age, and genotype. Thus, this study aimed to compare the small intestinal morphology and digestive function differences at different ages of three pig breeds. Thirty litters of newborn Taoyuan black (TB), Xiangcun black (XB), and Duroc (DR) piglets (ten litters per breed) were selected for this study. Ten piglets from each breed were selected and sampled at 1, 10, 21, and 24 days old. The results showed that the TB and XB piglets had lower growth but had higher lactase and maltase activities in the jejunum compared with the DR piglets, while most of the digestive enzyme activities in the ileum were higher in the DR piglets at different ages. The expression levels of nutrient transporters, mainly including amino acids, glucose, and fatty acids transporters, differed in the jejunum at different ages among three pig breeds and were higher in the DR piglets at 1 day old and XB piglets at 24 days old. Collectively, these findings suggest that the phenotypic differences in the growth, intestinal morphology, and digestive function among the three pig breeds mainly resulted from the differences in digestive enzymes and nutrient transporters in the intestine.

METTL14 Regulates Intestine Cellular Senescence through m6A Modification of Lamin B Receptor

N-6-Methyladenosine (m⁶A) modification is involved in multiple biological processes including aging. However, the regulation of m⁶A methyltransferase-like 14 (METTL14) in aging remains unclear. Here, we revealed that the level of m⁶A modification and the expression of METTL14 were particularly decreased in the intestine of aged mice as compared to young mice. Similar results were confirmed in Drosophila melanogaster. Knockdown of Mettl14 in Drosophila resulted in a short lifespan, associated disrupted intestinal integrity, and reduced climbing ability. In human CCD-18Co cells, knockdown of METTL14 accelerated cellular senescence, and the overexpression of METTL14 rescued senescent phenotypes. We also identified the lamin B receptor (LBR) as a target gene for METTL14-mediated m⁶A modification. Knockdown of METTL14 decreased m⁶A level of LBR, resulted in LBR mRNA instability, and thus induced cellular senescence. Our findings suggest that METTL14 plays an essential role in the m⁶A modification-dependent aging process via the regulation of LBR and provides a potential target for cellular senescence.

Intestinal atresia and necrotizing enterocolitis: Embryology and anatomy

The primitive gut originates at week 3 of gestation from the endoderm, with posterior incorporation of the remaining embryo layers. Wnt, Notch and TLR4 pathways have been shown to play central roles in the correct development of the intestine. The classical hypothesis for intestinal atresia development consists of failure in bowel recanalization or a vascular accident with secondary bowel reabsorption. These have been challenged due to the high frequency of associated malformations, and furthermore, with the discovery of molecular pathways and genes involved in bowel formation and correlated defects producing atresia. Necrotizing enterocolitis (NEC) has a multifactorial pathogenesis with prematurity being the most important risk factor; therefore, bowel immaturity plays a central role in NEC. Some of the same molecular pathways involved in gut maturation have been found to correlate with the predisposition of the immature bowel to develop the pathological findings seen in NEC.

Effects of dietary β-1,3-glucan addition on the growth performance, mRNA expression in jejunal barrier, and cecal microflora of broilers challenged with Clostridium perfringens

This experiment aimed to explore the interaction of β-1,3-glucan and Clostridium perfringens on the growth performance, intestinal health and cecal microflora of broilers. A total of 384 one-day-old Arbor Acre broilers were sorted into 4 treatments with 6 replications. There were 2 factors in this trial: dietary β-1,3-glucan addition including 0 and 250 mg/kg, intestinal enteritis challenged with Clostridium perfringens attack or not. Results showed that Clostridium perfringens infection disrupted the integrity of the intestinal mucosa by reducing the jejunal Occludin and Claudin-1 mRNA expression of broiler chickens at 21 d of age (P < 0.05). Meanwhile, when considering Clostridium perfringens as the main effect, it also decreased the mRNA expression of the glucose transporter recombinant sodium/glucose cotransporter 1 (SGLT1) at d 21 and the fatty acid transporter liver fatty acid-binding protein (L-FABP) at d 42 (P < 0.05) as well as affect cecum microbial diversity, especially in relative abundance of Firmicutes and Bacteroidetes. In addition, Clostridium perfringens infection reduced body weight, daily weight gain, and feed-gain ratio (FCR) in broilers at d 42 (P < 0.05). The dietary β-1,3-glucan could alleviate intestinal mucosal damage caused by the Clostridium perfringens to some extent. When considering β-1,3-glucan as the main effect, it increased the SGLT1 at 42 d of age (P < 0.05), and stabilized gut microbiota disorder caused by Clostridium perfringens. More over dietary β-1,3-glucan addition increased body weight at 42-day-old (P < 0.05), and improved daily weight gain and FCR during 1 to 42 d (P < 0.05). In conclusion, dietary β-1,3-glucan could improve growth performance and intestinal health in broilers infected with Clostridium perfringens.

Benefits and Risks of Early Life Iron Supplementation

Infants are frequently supplemented with iron to prevent iron deficiency, but iron supplements may have adverse effects on infant health. Although iron supplements can be highly effective at improving iron status and preventing iron deficiency anemia, iron may adversely affect growth and development, and may increase risk for certain infections. Several reviews exist in this area; however, none has fully summarized all reported outcomes of iron supplementation during infancy. In this review, we summarize the risks and benefits of iron supplementation as they have been reported in controlled studies and in relevant animal models. Additionally, we discuss the mechanisms that may underly beneficial and adverse effects.

SOX9 in organogenesis: shared and unique transcriptional functions

The transcription factor SOX9 is essential for the development of multiple organs including bone, testis, heart, lung, pancreas, intestine and nervous system. Mutations in the human SOX9 gene led to campomelic dysplasia, a haploinsufficiency disorder with several skeletal malformations frequently accompanied by 46, XY sex reversal. The mechanisms underlying the diverse SOX9 functions during organ development including its post-translational modifications, the availability of binding partners, and tissue-specific accessibility to target gene chromatin. Here we summarize the expression, activities, and downstream target genes of SOX9 in molecular genetic pathways essential for organ development, maintenance, and function. We also provide an insight into understanding the mechanisms that regulate the versatile roles of SOX9 in different organs.

Stand by me: Fibroblasts regulation of the intestinal epithelium during development and homeostasis

The epithelium of the small intestine is composed of a single layer of cells that line two functionally distinct compartments, the villi that project into the lumen of the gut and the crypts that descend into the underlying connective tissue. Stem cells are located in crypts, where they divide and give rise to transit-amplifying cells that differentiate into secretory and absorptive epithelial cells. Most differentiated cells travel upwards from the crypt towards the villus tip, where they shed into the lumen. While some of these cell behaviors are an intrinsic property of the epithelium, it is becoming evident that tight coordination between the epithelium and the underlying fibroblasts plays a critical role in tissue morphogenesis, stem-cell niche maintenance and regionalized gene expression along the crypt-villus axis. Here, we will review the current literature describing the interaction between epithelium and fibroblasts during crypt-villus axis development and intestinal epithelium renewal during homeostasis.

Recent advances in biofabricated gut models to understand the gut-brain axis in neurological diseases

Increasing evidence has accumulated that gut microbiome dysbiosis could be linked to neurological diseases, including both neurodegenerative and psychiatric diseases. With the high prevalence of neurological diseases, there is an urgent need to elucidate the underlying mechanisms between the microbiome, gut, and brain. However, the standardized aniikmal models for these studies have critical disadvantages for their translation into clinical application, such as limited physiological relevance due to interspecies differences and difficulty interpreting causality from complex systemic interactions. Therefore, alternative in vitro gut–brain axis models are highly required to understand their related pathophysiology and set novel therapeutic strategies. In this review, we outline state-of-the-art biofabrication technologies for modeling in vitro human intestines. Existing 3D gut models are categorized according to their topographical and anatomical similarities to the native gut. In addition, we deliberate future research directions to develop more functional in vitro intestinal models to study the gut–brain axis in neurological diseases rather than simply recreating the morphology.

Physical organogenesis of the gut

The gut has been a central subject of organogenesis since Caspar Friedrich Wolff’s seminal 1769 work ‘De Formatione Intestinorum’. Today, we are moving from a purely genetic understanding of cell specification to a model in which genetics codes for layers of physical–mechanical and electrical properties that drive organogenesis such that organ function and morphogenesis are deeply intertwined. This Review provides an up-to-date survey of the extrinsic and intrinsic mechanical forces acting on the embryonic vertebrate gut during development and of their role in all aspects of intestinal morphogenesis: enteric nervous system formation, epithelium structuring, muscle orientation and differentiation, anisotropic growth and the development of myogenic and neurogenic motility. I outline numerous implications of this biomechanical perspective in the etiology and treatment of pathologies, such as short bowel syndrome, dysmotility, interstitial cells of Cajal-related disorders and Hirschsprung disease.

Effect of the Microbiome on Intestinal Innate Immune Development in Early Life and the Potential Strategy of Early Intervention

Early life is a vital period for mammals to be colonized with the microbiome, which profoundly influences the development of the intestinal immune function. For neonates to resist pathogen infection and avoid gastrointestinal illness, the intestinal innate immune system is critical. Thus, this review summarizes the development of the intestinal microbiome and the intestinal innate immune barrier, including the intestinal epithelium and immune cells from the fetal to the weaning period. Moreover, the impact of the intestinal microbiome on innate immune development and the two main way of early-life intervention including probiotics and fecal microbiota transplantation (FMT) also are discussed in this review. We hope to highlight the crosstalk between early microbial colonization and intestinal innate immunity development and offer some information for early intervention.

Toxicity and genotoxicity of imidacloprid in the tadpoles of Leptodactylus luctator and Physalaemus cuvieri (Anura: Leptodactylidae)

Imidacloprid is a neonicotinoid insecticide used to control agricultural pests around the world. This pesticide can have adverse effects on non-target organisms, especially in aquatic environments. The present study evaluated the toxicity of an imidacloprid-based insecticide in amphibians, using Leptodactylus luctator and Physalaemus cuvieri tadpoles as study models. Spawning of both species were collected within less than 24 h of oviposition from a non-agricultural land at Erechim, Rio Grande do Sul state, Brazil. Survival, swimming activity, body size, morphological malformations, and genotoxic parameters were analyzed at laboratory conditions. A short-term assay was conducted over 168 h (7 days) with five different concentrations of imidacloprid (3–300 µg L⁻¹) being tested. The insecticide did not affect survival, although the tadpoles of both species presented reduced body size, malformed oral and intestine structures, and micronuclei and other erythrocyte nuclear abnormalities following exposure to this imidacloprid-based compound. Exposure also affected swimming activity in L. luctator, which reflected the greater sensitivity of L. luctator to imidacloprid in comparison with P. cuvieri. The swimming activity, body size, and malformations observed in L. luctator and the morphological malformations found in P. cuvieri indicated that even the lowest tested concentration of the insecticide were harmful to amphibians. At concentrations of over 3 μg L⁻¹, P. cuvieri presents a smaller body size, and both species are affected by genotoxic cell damage. This demonstrates that imidacloprid is potentially toxic for the two study species at environmentally relevant concentrations.

Mesenchymal-epithelial interaction regulates gastrointestinal tract development in mouse embryos

After gut tube patterning in early embryos, the cellular and molecular changes of developing stomach and intestine remain largely unknown. Here, combining single-cell RNA sequencing and spatial RNA sequencing, we construct a spatiotemporal transcriptomic landscape of the mouse stomach and intestine during embryonic days E9.5-E15.5. Several subpopulations are identified, including Lox⁺ stomach mesenchyme, Aldh1a3⁺ small-intestinal mesenchyme, and Adamdec1⁺ large-intestinal mesenchyme. The regionalization and heterogeneity of both the epithelium and the mesenchyme can be traced back to E9.5. The spatiotemporal distributions of cell clusters and the mesenchymal-epithelial interaction analysis indicate that a coordinated development of the epithelium and mesenchyme contribute to the stomach regionalization, intestine segmentation, and villus formation. Using the gut tube-derived organoids, we find that the cell fate of the foregut and hindgut can be switched by the regional niche factors, including fibroblast growth factors (FGFs) and retinoic acid (RA). This work lays a foundation for further dissection of the mechanisms governing this process.

Ginsenoside Rh2 attenuates CDAHFD-induced liver fibrosis in mice by improving intestinal microbial composition and regulating LPS-mediated autophagy

BACKGROUND

Nowadays, liver diseases are threatening more and more people all over the world and one of the main causes is liver fibrosis. However, there is no effective way to reverse liver fibrosis.

PURPOSE

To investigate whether ginsenoside Rh2 (G-Rh2) can alleviate liver fibrosis and elucidate its underlying mechanism.

METHODS

In vivo and in vitro methods were adopted in this research. Choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) was used to feed mice to induce liver fibrosis, and HSC-T6 cells were used to establish an LPS-induced model of liver fibrosis. Through histopathological staining, hematoxylin-eosin (H&E) staining, western blot analysis, intestinal bacteria 16SrRNA sequencing, and other technical means, the research explored whether G-Rh2 possesses anti-fibrotic activity.

RESULTS

G-Rh2 could notably alleviate CDAHFD-induced liver fibrosis in mice. In particular, it could alleviate liver injury and reduce plasma lipopolysaccharide (LPS) levels. Additionally, G-Rh2 could repair intestinal injury as well as regulate intestinal microbial diversity and composition. HSC-T6 cells could be activated and autophagy could be induced further by LPS in vitro. After being treated with G-Rh2, autophagy was restrained and activation of hepatic stellate cells (HSCs) was controlled. Deeper research showed that G-Rh2 restrained the activation of HSCs via stimulating the AKT-mTOR signaling pathway, restraining autophagy.

CONCLUSION

The results of our studies clearly suggest that G-Rh2 repairs intestinal injury, improves intestinal microbial composition, reduces plasma LPS levels, and activates the AKT-mTOR signaling pathway to restrain LPS-mediated autophagy, thus playing an important role in anti-hepatic fibrosis. G-Rh2 was found to have the potential to effectively alleviate liver fibrosis.

Review of glucose oxidase as a feed additive: production, engineering, applications, growth-promoting mechanisms, and outlook

The regulation and prohibition of antibiotics used as growth promoters (AGP) in the feed field are increasing because they cause antimicrobial resistance and drug residue issues and threaten community health. Recently, glucose oxidase (GOx) has attracted increasing interest in the feed industry as an alternative to antibiotics. GOx specifically catalyzes the production of gluconic acid (GA) and hydrogen peroxide (H₂O₂) by consuming molecular oxygen, and plays an important role in relieving oxidative stress, preserving health, and promoting animal growth. To expand the application of GOx in the feed field, considerable efforts have been made to mine new genetic resources. Efforts have also been made to heterologously overexpress relevant genes to reduce production costs and to engineer proteins by modifying enzyme properties, both of which are bottleneck problems that limit industrial feed applications. Herein, the: different sources, diverse biochemical properties, distinct structural features, and various strategies of GOx engineering and heterologous overexpression are summarized. The mechanism through which GOx promotes growth in animal production, including the improvement of antioxidant capacity, maintenance of intestinal microbiota homeostasis, and enhancement of gut function, are also systematically addressed. Finally, a new perspective is provided for the future development of GOx applications in the feed field.

Early life Lactobacillus rhamnosus GG colonisation inhibits intestinal tumour formation

BACKGROUND

Gut microbiota dysbiosis is closely related to the progression of colorectal cancer. Our previous study revealed that early life colonisation with Lactobacillus rhamnosus GG (LGG) had long-term positive effects on health. We sought to investigate whether early life LGG colonisation could inhibit intestinal tumour formation in offspring.

METHODS

Adult C57BL/6 female mice were mated with Apcmin/+ male mice. Pregnant mice with the same conception date received 108 cfu live or fixed LGG from day 18 of pregnancy until natural delivery. After genotyping, offspring mice received 107 cfu of live or fixed LGG for 0-5 days after birth.

RESULTS

Early life LGG colonisation significantly promoted intestinal development, inhibited low-grade intestinal inflammation and altered the gut microbiota composition of offspring in the weaning period (3 week old). Notably, early life LGG colonisation reduced the multiplicity of intestinal tumours in adulthood (12 week old), possibly due to inhibition of Wnt signalling and promotion of tumour cell apoptosis. Importantly, at the genus level, Bifidobacterium and Anaeroplasma with potential anti-tumour effects were increased in adulthood, while Peptostreptococcus, which potentially contributes to tumour formation, was decreased.

CONCLUSIONS

Early life LGG colonisation inhibited the intestinal tumour formation of offspring in adulthood.

Nutrition for the micro preemie: Beyond milk

Nutritional support is a fundamental component of the care of the extremely preterm infant, including the "micro preemie" (here defined as a baby born weighing less than 500 g), but goes beyond considerations of milk as a food. This is because milk from an infant's own mother, unlike currently available substitutes, additionally provides invaluable non-nutritive benefits. Nutritional support requires suitable devices or techniques to administer nutrients enterally or intravenously, products shown to be safe in preterm populations, and efficacy demonstrated in respect of important functional outcomes. Sadly, preterm feeding remains characterised by a deficit of evidence. In this chapter, we will briefly describe the history of preterm nutrition, discuss current enteral and parenteral practice, important evidence gaps, a summary of approaches for evaluating nutritional practice, and key considerations for future endeavour. Our discussion refers to all extremely preterm infants and it not confined to the micro preemie.

Nrf2 Transcriptional Activity Governs Intestine Development

Our recent findings indicate that Nrf2 transcriptional activity is essential in maintaining the proper large intestinal structure in adult mice. Here, we aimed to verify whether Nrf2-related intestine abnormalities stemmed from the early weaning or gestational periods. Therefore, we analyzed 4-day-old pups and embryos devoid of Nrf2 transcriptional activity (tKO) and their wild-type counterparts. We found significant changes in the intestinal structure of 4-day-old Nrf2 tKO pups including a longer colon, altered crypt distribution, and enlargement of the goblet cells with a markedly higher level of mucin 2. Tracing back the origin of these alterations, we observed that they appeared as early as day 14.5 of embryonic development, independently of sex. Importantly, in this period, we observed a significant increase in the Nrf2 level and a distinctive, untimely pattern of expression of the proliferation factor Ki67. At the latest stage of embryonic development, we detected a premature drop in the differentiation factor Notch1. We suspect that intestine abnormalities in mice lacking Nrf2 transcriptional activity stem from sex-independent disturbed intestinal cell proliferation and could be further exacerbated by altered differentiation. Summing up, we identified Nrf2 transcriptional activity as an important regulator of intestinal formation. It influences the hindgut cell proliferation and differentiation at different stages of embryonic development.

Single-cell chromatin profiling of the primitive gut tube reveals regulatory dynamics underlying lineage fate decisions

Development of the gastrointestinal system occurs after gut tube closure, guided by spatial and temporal control of gene expression. However, it remains unclear what forces regulate these spatiotemporal gene expression patterns. Here we perform single-cell chromatin profiling of the primitive gut tube to reveal organ-specific chromatin patterns that reflect the anatomical patterns of distinct organs. We generate a comprehensive map of epigenomic changes throughout gut development, demonstrating that dynamic chromatin accessibility patterns associate with lineage-specific transcription factor binding events to regulate organ-specific gene expression. Additionally, we show that loss of Sox2 and Cdx2, foregut and hindgut lineage-specific transcription factors, respectively, leads to fate shifts in epigenomic patterns, linking transcription factor binding, chromatin accessibility, and lineage fate decisions in gut development. Notably, abnormal expression of Sox2 in the pancreas and intestine impairs lineage fate decisions in both development and adult homeostasis. Together, our findings define the chromatin and transcriptional mechanisms of organ identity and lineage plasticity in development and adult homeostasis.

The primitive gut tube gives rise to all major internal organs, while underlying regulatory mechanisms are unclear. Here, the authors analyze its chromatin landscape at the single-cell level and define the epigenetic regulation of lineage fate decisions and plasticity in organ development and homeostasis.

Strong and tough self-wrinkling polyelectrolyte hydrogels constructed via a diffusion-complexation strategy

Self-wrinkling hydrogels enable various engineering and biomedical applications. The major challenge is to couple the self-wrinkling technologies and enhancement strategies, so as to get rid of the poor mechanical properties of existing self-wrinkling gels. Herein we present a facile diffusion-complexation strategy for constructing strong and ultratough self-wrinkling polyelectrolyte hydrogels with programmable wrinkled structures and customizable 3D configurations. Driven by the diffusion of low-molecular-weight chitosan polycations into the polyanion hydrogels, the high-modulus polyelectrolyte complexation shells can form directly on the hydrogel surface. Meanwhile, the polyanion hydrogels deswell/shrink due to the low osmotic pressure, which applies an isotropous surface compressive stress for inducing the formation of polygonal wrinkled structures. When the diffusion-complexation reaction occurs on a pre-stretched hydrogel sheet, the long-range ordered wrinkled structures can form during the springback/recovery of the hydrogel matrix. Moreover, through controlling the regions of diffusion-complexation reaction on the pre-stretched hydrogels, they can be spontaneously transformed into various 3D configurations with ordered wrinkled structures. Notably, because of the introduction of plenty of electrostatic binding (i.e., sacrificial bonds), the as-prepared self-wrinkling gels possess outstanding mechanical properties, far superior to the reported ones. This diffusion-complexation strategy paves the way for the on-demand design of high-performance self-wrinkling hydrogels.

Tracking the developmental events in the duodenum of the quail embryo: Using light and electron microscope

The present study described the full morphology of the duodenum of the Japanese quail during the embryonic stage from 3rd day of incubation till hatching using the light and electron (scanning and transmission) microscope. The specimens were collected, analyzed and described anatomically, morphometrically and microscopically. The first recognition of the prospective duodenum was at the 4th day of incubation and developed continuously by age progression. The prospective duodenum consisted of a flat pseudostratified epithelium, mesenchyme and covering mesothelium. On day 8th of incubation, the epithelium developed three evaginations lead to formation three previllous ridges protruding inside the duodenal lumen, which later at the 9th day differentiated into numbers of projections; villi. On the 9th day, the epithelium lined the villi transformed into a simple columnar type, the duodenal villi appeared as pyramidal-shaped projections, had wide base and narrow apex and by age progression, the duodenal villi went through changes in number, size and shape. On hatching day, the duodenal epithelium consisted of enterocytes interspersed with secretory goblet cells, which stained positive for both Periodic Acid Schiff (PAS) and Alcian blue AB and represented filled with metachromatic granules. The muscular wall started as mesenchymal condensation on the 6th day then differentiated into the circular smooth muscle layer on the 9th day of incubation. Giving detailed information about the morphological development of the duodenum during the incubation period of quail embryo helps in reaching a satisfactory explanation about how the duodenum plays a vital role in digestion, absorption and immunity.

Epithelial cells adapt to curvature induction via transient active osmotic swelling

Generation of tissue curvature is essential to morphogenesis. However, how cells adapt to changing curvature is still unknown because tools to dynamically control curvature in vitro are lacking. Here, we developed self-rolling substrates to study how flat epithelial cell monolayers adapt to a rapid anisotropic change of curvature. We show that the primary response is an active and transient osmotic swelling of cells. This cell volume increase is not observed on inducible wrinkled substrates, where concave and convex regions alternate each other over short distances; and this finding identifies swelling as a collective response to changes of curvature with a persistent sign over large distances. It is triggered by a drop in membrane tension and actin depolymerization, which is perceived by cells as a hypertonic shock. Osmotic swelling restores tension while actin reorganizes, probably to comply with curvature. Thus, epithelia are unique materials that transiently and actively swell while adapting to large curvature induction.

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Rapid inward and outward epithelial rolling triggers cell volume increase

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Epithelial folding induces a mechano-osmotic feedback loop that involvs ion channels

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Cell volume regulation in curved tissues involves actin, membrane tension, and mTORC2