Stomach development, stem cells and disease

PHF10 inhibits gastric epithelium differentiation and induces gastric cancer carcinogenesis

Gastric cancer (GC) is characterized with differentiation disorders, the precise mechanisms of which remain unknown. Our previous study showed that PHF10 exhibits oncogenic properties in GC, with its histological presentation indicating a potential role in the modulation of differentiation disorders in GC. This study reveals a significant upregulation of PHF10 in GC tissues, showing a negative correlation with differentiation level. PHF10 was found to impede the differentiation of GC cells while promoting their stemness properties. This was attributed to the formation of a positive feedback loop between PHF10 and E2F1, resulting in dysregulated expression levels in GC. Additionally, PHF10 was found to mediate the transcriptional repression of the target gene DUSP5 in GC cells through the assembly of the SWI/SNF complex, leading to an elevation in pERK1/2 levels. In GC tissues, a negative association was noted between the expression of E2F1 or PHF10 and DUSP5, whereas a positive correlation was observed between the expression of E2F1 or PHF10 and pERK1/2. Additional rescue experiments confirmed that the inhibitory effect on differentiation of GC cells by PHF10 is dependent on the DUSP5-pERK1/2 axis. The signaling cascade involving E2F1-PHF10-DUSP5-pERK1/2 was identified as an important player in regulating differentiation and stemness in GC cells. PHF10 emerges as a promising target for differentiation induction therapy in GC.

Translational Utility of Organoid Models for Biomedical Research on Gastrointestinal Diseases

Organoid models have recently been utilized to study 3D human-derived tissue systems to uncover tissue architecture and adult stem cell biology. Patient-derived organoids unambiguously provide the most suitable in vitro system to study disease biology with the actual genetic background. With the advent of much improved and innovative approaches, patient-derived organoids can potentially be used in regenerative medicine. Various human tissues were explored to develop organoids due to their multifold advantage over the conventional in vitro cell line culture approach and in vivo models. Gastrointestinal (GI) tissues have been widely studied to establish organoids and organ-on-chip for screening drugs, nutraceuticals, and other small molecules having therapeutic potential. The function of channel proteins, transporters, and transmembrane proteins was also explained. The successful application of genome editing in organoids using the CRISPR-Cas approach has been reported recently. GI diseases such as Celiac disease (CeD), Inflammatory bowel disease (IBD), and common GI cancers have been investigated using several patient-derived organoid models. Recent advancements on organoid bio-banking and 3D bio-printing contributed significantly in personalized disease management and therapeutics. This article reviews the available literature on investigations and translational applications of patient-derived GI organoid models, notably on elucidating gut-microbial interaction and epigenetic modifications.

Time-resolved fate mapping identifies the intestinal upper crypt zone as an origin of Lgr5+ crypt base columnar cells

In the prevailing model, Lgr5+ cells are the only intestinal stem cells (ISCs) that sustain homeostatic epithelial regeneration by upward migration of progeny through elusive upper crypt transit-amplifying (TA) intermediates. Here, we identify a proliferative upper crypt population marked by Fgfbp1, in the location of putative TA cells, that is transcriptionally distinct from Lgr5+ cells. Using a kinetic reporter for time-resolved fate mapping and Fgfbp1-CreERT2 lineage tracing, we establish that Fgfbp1+ cells are multi-potent and give rise to Lgr5+ cells, consistent with their ISC function. Fgfbp1+ cells also sustain epithelial regeneration following Lgr5+ cell depletion. We demonstrate that FGFBP1, produced by the upper crypt cells, is an essential factor for crypt proliferation and epithelial homeostasis. Our findings support a model in which tissue regeneration originates from upper crypt Fgfbp1+ cells that generate progeny propagating bi-directionally along the crypt-villus axis and serve as a source of Lgr5+ cells in the crypt base.

Metabolic regulator ERRγ governs gastric stem cell differentiation into acid-secreting parietal cells

Parietal cells (PCs) produce gastric acid to kill pathogens and aid digestion. Dysregulated PC census is common in disease, yet how PCs differentiate is unclear. Here, we identify the PC progenitors arising from isthmal stem cells, using mouse models and human gastric cells, and show that they preferentially express cell-metabolism regulator and orphan nuclear receptor Estrogen-related receptor gamma (Esrrg, encoding ERRγ). Esrrg expression facilitated the tracking of stepwise molecular, cellular, and ultrastructural stages of PC differentiation. EsrrgP2ACreERT2 lineage tracing revealed that Esrrg expression commits progenitors to differentiate into mature PCs. scRNA-seq indicated the earliest Esrrg+ PC progenitors preferentially express SMAD4 and SP1 transcriptional targets and the GTPases regulating acid-secretion signal transduction. As progenitors matured, ERRγ-dependent metabolic transcripts predominated. Organoid and mouse studies validated the requirement of ERRγ for PC differentiation. Our work chronicles stem cell differentiation along a single lineage in vivo and suggests ERRγ as a therapeutic target for PC-related disorders.

A human stomach cell type transcriptome atlas

BACKGROUND

The identification of cell type-specific genes and their modification under different conditions is central to our understanding of human health and disease. The stomach, a hollow organ in the upper gastrointestinal tract, provides an acidic environment that contributes to microbial defence and facilitates the activity of secreted digestive enzymes to process food and nutrients into chyme. In contrast to other sections of the gastrointestinal tract, detailed descriptions of cell type gene enrichment profiles in the stomach are absent from the major single-cell sequencing-based atlases.

RESULTS

Here, we use an integrative correlation analysis method to predict human stomach cell type transcriptome signatures using unfractionated stomach RNAseq data from 359 individuals. We profile parietal, chief, gastric mucous, gastric enteroendocrine, mitotic, endothelial, fibroblast, macrophage, neutrophil, T-cell, and plasma cells, identifying over 1600 cell type-enriched genes.

CONCLUSIONS

We uncover the cell type expression profile of several non-coding genes strongly associated with the progression of gastric cancer and, using a sex-based subset analysis, uncover a panel of male-only chief cell-enriched genes. This study provides a roadmap to further understand human stomach biology.

Identification and characterization of Hand2 upstream genomic enhancers active in developing stomach and limbs

BACKGROUND

The bHLH transcription factor HAND2 plays important roles in the development of the embryonic heart, face, limbs, and sympathetic and enteric nervous systems. To define how and when HAND2 regulates these developmental systems, requires understanding the transcriptional regulation of Hand2.

RESULTS

Remarkably, Hand2 is flanked by an extensive upstream gene desert containing a potentially diverse enhancer landscape. Here, we screened the regulatory interval 200 kb proximal to Hand2 for putative enhancers using evolutionary conservation and histone marks in Hand2-expressing tissues. H3K27ac signatures across embryonic tissues pointed to only two putative enhancer regions showing deep sequence conservation. Assessment of the transcriptional enhancer potential of these elements using transgenic reporter lines uncovered distinct in vivo enhancer activities in embryonic stomach and limb mesenchyme, respectively. Activity of the identified stomach enhancer was restricted to the developing antrum and showed expression within the smooth muscle and enteric neurons. Surprisingly, the activity pattern of the limb enhancer did not overlap Hand2 mRNA but consistently yielded a defined subectodermal anterior expression pattern within multiple transgenic lines.

CONCLUSIONS

Together, these results start to uncover the diverse regulatory potential inherent to the Hand2 upstream regulatory interval.

Remodeling of the gastric environment in Helicobacter pylori-induced atrophic gastritis

Helicobacter pylori colonization of the human stomach is a strong risk factor for gastric cancer. To investigate H. pylori-induced gastric molecular alterations, we used a Mongolian gerbil model of gastric carcinogenesis. Histologic evaluation revealed varying levels of atrophic gastritis (a premalignant condition characterized by parietal and chief cell loss) in H. pylori-infected animals, and transcriptional profiling revealed a loss of markers for these cell types. We then assessed the spatial distribution and relative abundance of proteins in the gastric tissues using imaging mass spectrometry and liquid chromatography with tandem mass spectrometry. We detected striking differences in the protein content of corpus and antrum tissues. Four hundred ninety-two proteins were preferentially localized to the corpus in uninfected animals. The abundance of 91 of these proteins was reduced in H. pylori-infected corpus tissues exhibiting atrophic gastritis compared with infected corpus tissues exhibiting non-atrophic gastritis or uninfected corpus tissues; these included numerous proteins with metabolic functions. Fifty proteins localized to the corpus in uninfected animals were diffusely delocalized throughout the stomach in infected tissues with atrophic gastritis; these included numerous proteins with roles in protein processing. The corresponding alterations were not detected in animals infected with a H. pylori ∆cagT mutant (lacking Cag type IV secretion system activity). These results indicate that H. pylori can cause loss of proteins normally localized to the gastric corpus as well as diffuse delocalization of corpus-specific proteins, resulting in marked changes in the normal gastric molecular partitioning into distinct corpus and antrum regions.IMPORTANCEA normal stomach is organized into distinct regions known as the corpus and antrum, which have different functions, cell types, and gland architectures. Previous studies have primarily used histologic methods to differentiate these regions and detect H. pylori-induced alterations leading to stomach cancer. In this study, we investigated H. pylori-induced gastric molecular alterations in a Mongolian gerbil model of carcinogenesis. We report the detection of numerous proteins that are preferentially localized to the gastric corpus but not the antrum in a normal stomach. We show that stomachs with H. pylori-induced atrophic gastritis (a precancerous condition characterized by the loss of specialized cell types) exhibit marked changes in the abundance and localization of proteins normally localized to the gastric corpus. These results provide new insights into H. pylori-induced gastric molecular alterations that are associated with the development of stomach cancer.

Hallmarks of stemness in mammalian tissues

All adult tissues experience wear and tear. Most tissues can compensate for cell loss through the activity of resident stem cells. Although the cellular maintenance strategies vary greatly between different adult (read: postnatal) tissues, the function of stem cells is best defined by their capacity to replace lost tissue through division. We discuss a set of six complementary hallmarks that are key enabling features of this basic function. These include longevity and self-renewal, multipotency, transplantability, plasticity, dependence on niche signals, and maintenance of genome integrity. We discuss these hallmarks in the context of some of the best-understood adult stem cell niches.

Elevated stress response marks deeply quiescent reserve cells of gastric chief cells

Gastrointestinal tract organs harbor reserve cells, which are endowed with cellular plasticity and regenerate functional units in response to tissue damage. However, whether the reserve cells in gastrointestinal tract exist as long-term quiescent cells remain incompletely understood. In the present study, we systematically examine H2b-GFP label-retaining cells and identify a long-term slow-cycling population in the gastric corpus but not in other gastrointestinal organs. The label-retaining cells, which reside near the basal layers of the corpus, comprise a subpopulation of chief cells. The identified quiescent cells exhibit induction of Atf4 and its target genes including Atf3, a marker of paligenosis, and activation of the unfolded protein response, but do not show elevated expression of Troy, Lgr5, or Mist. External damage to the gastric mucosa induced by indomethacin treatment triggers proliferation of the quiescent Atf4+ population, indicating that the gastric corpus harbors a specific cell population that is primed to facilitate stomach regeneration.

Seven-Month Vitamin D Deficiency Inhibits Gastric Epithelial Cell Proliferation, Stimulates Acid Secretion, and Differentially Alters Cell Lineages in the Gastric Glands

Vitamin D (VD) deficiency can result from insufficiency of either light exposure or VD intake. We investigated the biological effects of VD deficiency for 7 months on the mouse gastric glands. Varying degrees of VD deficiency were induced in C57BL/6 mice by keeping them on standard diet with constant-dark conditions (SDD) or VD deficient diet with constant-dark conditions (VDD). Samples of serum, glandular stomach, and gastric contents were collected for LCMS/MS, RT-PCR, immunohistochemistry, and acid content measurements. Both SDD and VDD mice had a significant decline in 25OHVD metabolite, gastric epithelial cell proliferation, and mucin 6 gene expression. These effects were enhanced with the severity of VD deficiency from SDD to VDD. Besides and compared to the control group, SDD mice only displayed a significant increase in the number of zymogenic cells (p ≤ 0.0001) and high expression of the adiponectin (p ≤ 0.05), gastrin (p ≤ 0.0001), mucin 5AC (*** p ≤ 0.001) and the Cyclin-dependent kinase inhibitor 1A (**** p ≤ 0.0001). These phenotypes were unique to SDD gastric samples and not seen in the VDD or control groups. This study suggests that the body reacts differently to diverse VD deficiency sources, light or diet.

Stomach encyclopedia: Combined single-cell and spatial transcriptomics reveal cell diversity and homeostatic regulation of human stomach

The stomach is an important digestive organ with various biological functions. However, because of the complexity of its cellular and glandular composition, its precise cellular biology has yet to be elucidated. In this study, we conducted single-cell RNA sequencing (scRNA-seq) and subcellular-level spatial transcriptomics analysis of the human stomach and constructed the largest dataset to date: a stomach encyclopedia. This dataset consists of approximately 380,000 cells from scRNA-seq and the spatial transcriptome, enabling integrated analyses of transcriptional and spatial information of gastric and metaplastic cells. This analysis identified LEFTY1 as an uncharacterized stem cell marker, which was confirmed through lineage tracing analysis. A wide variety of cell-cell interactions between epithelial and stromal cells, including PDGFRA+BMP4+WNT5A+ fibroblasts, was highlighted in the developmental switch of intestinal metaplasia. Our extensive dataset will function as a fundamental resource in investigations of the stomach, including studies of development, aging, and carcinogenesis.

Gastric epithelial stem cells in development, homeostasis and regeneration

The stem/progenitor cell pool is indispensable for the development, homeostasis and regeneration of the gastric epithelium, owing to its defining ability to self-renew whilst supplying the various functional epithelial lineages needed to digest food efficiently. A detailed understanding of the intricacies and complexities surrounding the behaviours and roles of these stem cells offers insights, not only into the physiology of gastric epithelial development and maintenance, but also into the pathological consequences following aberrations in stem cell regulation. Here, we provide an insightful synthesis of the existing knowledge on gastric epithelial stem cell biology, including the in vitro and in vivo experimental techniques that have advanced such studies. We highlight the contributions of stem/progenitor cells towards patterning the developing stomach, specification of the differentiated cell lineages and maintenance of the mature epithelium during homeostasis and following injury. Finally, we discuss gaps in our understanding and identify key research areas for future work.

Cross-species single-cell transcriptomic analysis of animal gastric antrum reveals intense porcine mucosal immunity

As an important part of the stomach, gastric antrum secretes gastrin which can regulate acid secretion and gastric emptying. Although most cell types in the gastric antrum are identified, the comparison of cell composition and gene expression in the gastric antrum among different species are not explored. In this study, we collected antrum epithelial tissues from human, pig, rat and mouse for scRNA-seq and compared cell types and gene expression among species. In pig antral epithelium, we identified a novel cell cluster, which is marked by high expression of AQP5, F3, CLCA1 and RRAD. We also discovered that the porcine antral epithelium has stronger immune function than the other species. Further analysis revealed that this may be due to the insufficient function of porcine immune cells. Together, our results replenish the information of multiple species of gastric antral epithelium at the single cell level and provide resources for understanding the homeostasis maintenance and regeneration of gastric antrum epithelium.

An integrated cellular and molecular model of gastric neuroendocrine cancer evolution highlights therapeutic targets

Gastric neuroendocrine carcinomas (G-NEC) are aggressive malignancies with poorly understood biology and a lack of disease models. Here, we use genome sequencing to characterize the genomic landscapes of human G-NEC and its histologic variants. We identify global and subtype-specific alterations and expose hitherto unappreciated gains of MYC family members in a large part of cases. Genetic engineering and lineage tracing in mice delineate a model of G-NEC evolution, which defines MYC as a critical driver and positions the cancer cell of origin to the neuroendocrine compartment. MYC-driven tumors have pronounced metastatic competence and display defined signaling addictions, as revealed by large-scale genetic and pharmacologic screening of cell lines and organoid resources. We create global maps of G-NEC dependencies, highlight critical vulnerabilities, and validate therapeutic targets, including candidates for clinical drug repurposing. Our study gives comprehensive insights into G-NEC biology.

Mechanical force drives the initial mesenchymal-epithelial interaction during skin organoid development

Rationale: Stem cells self-organize to form organoids that generate mini-organs that resemble the physiologically-developed ones. The mechanism by which the stem cells acquire the initial potential for generating mini-organs remains elusive. Here we used skin organoids as an example to study how mechanical force drives initial epidermal-dermal interaction which potentiates skin organoids to regenerate hair follicles. Methods: Live imaging analysis, single-cell RNA-sequencing analysis, and immunofluorescence were used to analyze the contractile force of dermal cells in skin organoids. Bulk RNA-sequencing analysis, calcium probe detection, and functional perturbations were used to verify that calcium signaling pathways respond to the contractile force of dermal cells. In vitro mechanical loading experiment was used to prove that the stretching force triggers the epidermal Piezo1 expression which negatively regulates dermal cell attachment. Transplantation assay was used to test the regenerative ability of skin organoids. Results: We found that dermal cell-derived contraction force drives the movement of dermal cells surrounding the epidermal aggregates to trigger initial mesenchymal-epithelial interaction (MEI). In response to dermal cell contraction force, the arrangement of the dermal cytoskeleton was negatively regulated by the calcium signaling pathway which further influences dermal-epidermal attachment. The native contraction force generated from the dermal cell movement exerts a stretching force on the adjacent epidermal cells, activating the stretching force sensor Piezo1 in the epidermal basal cells during organoid culture. Epidermal Piezo1 in turn drives strong MEI to negatively regulate dermal cell attachment. Proper initial MEI by mechanical-chemical coupling during organoid culture is required for hair regeneration upon transplantation of the skin organoids into the back of the nude mice. Conclusion: Our study demonstrated that mechanical-chemical cascade drives the initial event of MEI during skin organoid development, which is fundamental to the organoid, developmental, and regenerative biology fields.

Dissection of gastric homeostasis in vivo facilitates permanent capture of isthmus-like stem cells in vitro

The glandular stomach is composed of two regenerative compartments termed corpus and antrum, and our understanding of the transcriptional networks that maintain these tissues is incomplete. Here we show that cell types with equivalent functional roles in the corpus and antrum share similar transcriptional states including the poorly characterized stem cells of the isthmus region. To further study the isthmus, we developed a monolayer two-dimensional (2D) culture system that is continually maintained by Wnt-responsive isthmus-like cells capable of differentiating into several gastric cell types. Importantly, 2D cultures can be converted into conventional three-dimensional organoids, modelling the plasticity of gastric epithelial cells in vivo. Finally, we utilized the 2D culture system to show that Sox2 is both necessary and sufficient to generate enterochromaffin cells. Together, our data provide important insights into gastric homeostasis, establish a tractable culture system to capture isthmus cells and uncover a role for Sox2 in enterochromaffin cells.

ROCKETS - a novel one-for-all toolbox for light sheet microscopy in drug discovery

Advancing novel immunotherapy strategies requires refined tools in preclinical research to thoroughly assess drug targets, biodistribution, safety, and efficacy. Light sheet fluorescence microscopy (LSFM) offers unprecedented fast volumetric ex vivo imaging of large tissue samples in high resolution. Yet, to date laborious and unstandardized tissue processing procedures have limited throughput and broader applications in immunological research. Therefore, we developed a simple and harmonized protocol for processing, clearing and imaging of all mouse organs and even entire mouse bodies. Applying this Rapid Optical Clearing Kit for Enhanced Tissue Scanning (ROCKETS) in combination with LSFM allowed us to comprehensively study the in vivo biodistribution of an antibody targeting Epithelial Cell Adhesion Molecule (EpCAM) in 3D. Quantitative high-resolution scans of whole organs did not only reveal known EpCAM expression patterns but, importantly, uncovered several new EpCAM-binding sites. We identified gustatory papillae of the tongue, choroid plexi in the brain and duodenal papillae as previously unanticipated locations of high EpCAM expression. Subsequently, we confirmed high EpCAM expression also in human tongue and duodenal specimens. Choroid plexi and duodenal papillae may be considered as particularly sensitive sites due to their importance for liquor production or as critical junctions draining bile and digestive pancreatic enzymes into the small bowel, respectively. These newly gained insights appear highly relevant for clinical translation of EpCAM-addressing immunotherapies. Thus, ROCKETS in combination with LSFM may help to set new standards for preclinical evaluation of immunotherapeutic strategies. In conclusion, we propose ROCKETS as an ideal platform for a broader application of LSFM in immunological research optimally suited for quantitative co-localization studies of immunotherapeutic drugs and defined cell populations in the microanatomical context of organs or even whole mice.

DNA methylation in human gastric epithelial cells defines regional identity without restricting lineage plasticity

BACKGROUND

Epigenetic modifications in mammalian DNA are commonly manifested by DNA methylation. In the stomach, altered DNA methylation patterns have been observed following chronic Helicobacter pylori infections and in gastric cancer. In the context of epigenetic regulation, the regional nature of the stomach has been rarely considered in detail.

RESULTS

Here, we establish gastric mucosa derived primary cell cultures as a reliable source of native human epithelium. We describe the DNA methylation landscape across the phenotypically different regions of the healthy human stomach, i.e., antrum, corpus, fundus together with the corresponding transcriptomes. We show that stable regional DNA methylation differences translate to a limited extent into regulation of the transcriptomic phenotype, indicating a largely permissive epigenetic regulation. We identify a small number of transcription factors with novel region-specific activity and likely epigenetic impact in the stomach, including GATA4, IRX5, IRX2, PDX1 and CDX2. Detailed analysis of the Wnt pathway reveals differential regulation along the craniocaudal axis, which involves non-canonical Wnt signaling in determining cell fate in the proximal stomach. By extending our analysis to pre-neoplastic lesions and gastric cancers, we conclude that epigenetic dysregulation characterizes intestinal metaplasia as a founding basis for functional changes in gastric cancer. We present insights into the dynamics of DNA methylation across anatomical regions of the healthy stomach and patterns of its change in disease. Finally, our study provides a well-defined resource of regional stomach transcription and epigenetics.

Glypican-6 and Glypican-4 stimulate embryonic stomach growth by regulating Hedgehog and noncanonical Wnt signaling

BACKGROUND

Glypicans are a family of proteoglycans that play important roles in embryonic morphogenesis. The mammalian genome contains six glypicans (GPC1 to GPC6). GPC6 and GPC4 are the pair of glypicans that show the highest degree of homology within the family. GPC6-null embryos display bone abnormalities and severely shortened intestines.

RESULTS

We show that GPC6-null embryos display significantly smaller stomachs, and that Hedgehog and noncanonical Wnt signaling are dysregulated in GPC6-null stomachs. Like GPC6, GPC4 is expressed by the developing stomach. However, GPC4-null embryos have normal stomachs. To investigate whether GPC6 and GPC4 display functional overlap in the developing stomach, we crossed GPC4-null mice with GPC6 conditional mutants in which the expression of this glypican is severely reduced in the stomach. Notably, we found that the compound mutants display stomachs that are smaller than those of the GPC6 conditional mutants. We also found that this functional overlap between GPC6 and GPC4 is mediated by the noncanonical Wnt pathway.

CONCLUSION

This study demonstrates that GPC6 stimulates the growth of the embryonic stomach via Wnt and Hh signaling. In addition, we uncovered a Wnt-mediated functional overlap between GPC6 and GPC4 in the developing stomach.

Human gastric fibroblasts ameliorate A20-dependent cell survival in co-cultured gastric epithelial cells infected by Helicobacter pylori

Crosstalk within the gastric epithelium, which is closely in contact with stromal fibroblasts in the gastric mucosa, has a pivotal impact in proliferation, differentiation and transformation of the gastric epithelium. The human pathogen Helicobacter pylori colonises the gastric epithelium and represents a risk factor for gastric pathophysiology. Infection of H. pylori induces the activation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which is involved in the pro-inflammatory response but also in cell survival. In co-cultures with human gastric fibroblasts (HGF), we found that apoptotic cell death is reduced in the polarised human gastric cancer cell line NCI-N87 or in gastric mucosoids during H. pylori infection. Interestingly, suppression of apoptotic cell death in NCI-N87 cells involved an enhanced A20 expression regulated by NF-κB activity in response to H. pylori infection. Moreover, A20 acts as an important negative regulator of caspase-8 activity, which was suppressed in NCI-N87 cells during co-culture with gastric fibroblasts. Our results provide evidence for NF-κB-dependent regulation of apoptotic cell death in cellular crosstalk and highlight the protective role of gastric fibroblasts in gastric epithelial cell death during H. pylori infection.

Reprogramming of three-dimensional microenvironments for in vitro hair follicle induction

During embryonic development, reciprocal interactions between epidermal and mesenchymal layers trigger hair follicle morphogenesis. This study revealed that microenvironmental reprogramming via control over these interactions enabled hair follicle induction in vitro. A key approach is to modulate spatial distributions of epithelial and mesenchymal cells in their spontaneous organization. The de novo hair follicles with typical morphological features emerged in aggregates of the two cell types, termed hair follicloids, and hair shafts sprouted with near 100% efficiency in vitro. The hair shaft length reached ~3 mm in culture. Typical trichogenic signaling pathways were up-regulated in hair follicloids. Owing to replication of hair follicle morphogenesis in vitro, melanosome production and transportation were also monitored in the hair bulb region. This in vitro hair follicle model might be valuable for better understanding hair follicle induction, evaluating hair growth and inhibition of hair growth by drugs, and modeling gray hairs in a well-defined environment.

V-set and immunoglobulin domain containing 1 (VSIG1) as an emerging target for epithelial-mesenchymal transition of gastric cancer

V-set and Immunoglobulin domain containing 1 (VSIG1) is a cell–cell adhesion molecule which role in the genesis and evolution of gastric cancer (GC) is not understood. Only three Medline-indexed papers have focused on the role of VSIG1 in GC. The clinicopathological features of 94 GCs were examined in association with immunohistochemical (IHC) patterns of VSIG1, E-cadherin, and β-catenin which were assessed in the tumor core (central) vs. invasive edge. Cases were classified depending on the VSIG1 expression: membrane/membrane in both core and invasive front; null/negative staining in both core and invasive front; and cases with translocational patterns: membrane core/cytoplasmic buds and cytoplasmic core/null buds. Most of the tumors showed null pattern (n = 54). Cases with translocational patterns (n = 20) were GCs with a high lymph node ratio value (≥ 0.26) and advanced Dukes-MAC-like stage. Of the 20 total cases, 9 showed membrane-to-nuclear translocation of β-catenin and loss of E-cadherin, as indicators of epithelial–mesenchymal transition. All cases with membrane/membrane pattern (n = 20) involved the distal stomach. The poorest overall survival was registered in patients with subcellular translocation of VSIG1, compared to those with either membrane/membrane or null patterns (p = 0.002). In GC, VSIG1 acts as an adhesion membrane protein but its membrane-cytoplasmic translocation can be an indicator of epithelial–mesenchymal transition due to cytoplasmic VSIG1-mediated activation of canonical Wnt/β-catenin signaling pathway.

Applications of human organoids in the personalized treatment for digestive diseases

Digestive system diseases arise primarily through the interplay of genetic and environmental influences; there is an urgent need in elucidating the pathogenic mechanisms of these diseases and deploy personalized treatments. Traditional and long-established model systems rarely reproduce either tissue complexity or human physiology faithfully; these shortcomings underscore the need for better models. Organoids represent a promising research model, helping us gain a more profound understanding of the digestive organs; this model can also be used to provide patients with precise and individualized treatment and to build rapid in vitro test models for drug screening or gene/cell therapy, linking basic research with clinical treatment. Over the past few decades, the use of organoids has led to an advanced understanding of the composition of each digestive organ and has facilitated disease modeling, chemotherapy dose prediction, CRISPR-Cas9 genetic intervention, high-throughput drug screening, and identification of SARS-CoV-2 targets, pathogenic infection. However, the existing organoids of the digestive system mainly include the epithelial system. In order to reveal the pathogenic mechanism of digestive diseases, it is necessary to establish a completer and more physiological organoid model. Combining organoids and advanced techniques to test individualized treatments of different formulations is a promising approach that requires further exploration. This review highlights the advancements in the field of organoid technology from the perspectives of disease modeling and personalized therapy.

High-resolution ultrasound and speckle tracking: a non-invasive approach to assess in vivo gastrointestinal motility during development

Gastrointestinal motor activity has been extensively studied in adults; however, only few studies have investigated fetal motor skills. It is unknown when the gastrointestinal tract starts to contract during the embryonic period and how this function evolves during development. Here, we adapted a non-invasive high-resolution echography technique combined with speckle tracking analysis to examine the gastrointestinal tract motor activity dynamics during chick embryo development. We provided the first recordings of fetal gastrointestinal motility in living embryos without anesthesia. We found that, although gastrointestinal contractions appear very early during development, they become synchronized only at the end of the fetal period. To validate this approach, we used various pharmacological inhibitors and BAPX1 gene overexpression in vivo. We found that the enteric nervous system determines the onset of the synchronized contractions in the stomach. Moreover, alteration of smooth muscle fiber organization led to an impairment of this functional activity. Altogether, our findings show that non-invasive high-resolution echography and speckle tracking analysis allows visualization and quantification of gastrointestinal motility during development and highlight the progressive acquisition of functional and coordinated gastrointestinal motility before birth.

Overgrowth of Squamocolumnar Junction and Dysregulation of Stem Cell Lineages in the Stomach of Vitamin A-Deficient Mice

Junctional epithelia are common sites for pathological transformations. In mice, the stratified epithelium of the forestomach joins the simple glandular epithelium of the cardia at the limiting ridge. We previously demonstrated the expression of vitamin A receptors in the gastric stem/progenitor cells and their progeny and found that excess retinoic acid enhances cellular dynamics of gastric epithelium. This study examines how deficiency of vitamin A would alter gastric epithelial stem cell lineages. Three-week-old mice of both genders were weaned and fed with a vitamin A deficient (VAD) diet for 4 or 8 months. Sex- and weight-matched littermate mice received a standard (control) diet. To label S-phase cells, all mice received a single intraperitoneal injection of 5-bromo-2-deoxyuridine before being euthanized. Stomach tissues were processed for microscopic examination and protein analysis to investigate stem cell lineages using different stains, lectins, or antibodies. The Student’s t-test was used to compare quantified data showing differences between control and VAD groups. Eight-month-vitamin-A deficiency caused enlarged forestomach and overgrowth of the squamocolumnar junction with metaplastic and dysplastic cardiac glands, formation of intramucosal cysts, loss of surface mucosal integrity, increased amount of luminal surface mucus, and upregulation of trefoil factor 1 and H⁺,K⁺-ATPase. These changes were associated with decreased cell proliferation and upregulation of p63. In conclusion, vitamin A is necessary for maintaining gastric epithelial integrity and its deficiency predisposes the mouse stomach to precancerous lesions.

Extract of Tagetes erecta L., a medicinal plant rich in lutein, promotes gastric healing and reduces ulcer recurrence in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Tagetes erecta L. (Asteraceae), popularly known as Aztec Marigold, is used in South America to treat several ailments. Despite reports that T. erecta flowers are used in folk medicine to treat gastrointestinal diseases, there is no study regarding its gastric healing effects.

AIM OF THE STUDY

The effect of dry extract of T. erecta L. (DETe) in gastric healing and gastric ulcer recurrence was evaluated, contributing to the validation of the antiulcer potential of this medicinal plant.

METHODS

Rats were treated orally with vehicle (1 ml/kg), omeprazole (20 mg/kg), or DETe (3, 30 or 300 mg/kg) for 7 days, twice a day. The lesion area was evaluated, and the levels of reduced glutathione (GSH) and lipoperoxides (LOOH) and the activity of the superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and myeloperoxidase (MPO) were measured. The ulcer recurrence was evaluated in mice and induced by interleukin (IL)-1β (1 μg/kg, i.p). The recurred area, gastric wall thickness, GSH and cytokines levels, MPO and N-acetylglucosaminidase (NAG) activities were measured.

RESULTS

DETe accelerated the healing of gastric ulcers only at 300 mg/kg, reducing the ulcerated area by 66%. In parallel, DETe reduced LOOH levels, SOD, CAT and MPO activities, while increasing GST activity and mucin amount. In the recurrence model, DETe reduced the lesion area by 94%, and in parallel decreased the gastric wall thickness and TNF levels, while increasing IL-10 amount.

CONCLUSIONS

Corroborating the popular use of T. erecta, DETe favors the antioxidant system and reduce gastric inflammation, accelerating the gastric healing process and reducing the ulcer recurrence.

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.

Elevated Protein Kinase A Activity in Stomach Mesenchyme Disrupts Mesenchymal-epithelial Crosstalk and Induces Preneoplasia

BACKGROUND & AIMS

Mesenchymal-epithelial crosstalk (MEC) in the stomach is executed by pathways such as bone morphogenetic protein (BMP) and extracellular signal-regulated kinase (ERK). Mis-regulation of MEC disrupts gastric homeostasis and causes tumorigenesis. Protein Kinase A (PKA) crosstalks with BMP and ERK signaling; however, PKA function(s) in stomach development and homeostasis remains undefined.

METHODS

We generated a novel Six2-Cre^+/-PKAcαR^fl/wt (CA-PKA) mouse in which expression of constitutive-active PKAcαR was induced in gastric mesenchyme progenitors. Lineage tracing determined spatiotemporal activity of Six2-Cre in the stomach. For phenotyping CA-PKA mice histological, co-immunofluorescence, immunoblotting, mRNA sequencing, and bioinformatics analyses were performed.

RESULTS

Lineage tracing showed that Six2-Cre activity in the stomach is restricted to the mesenchymal compartment. CA-PKA mice showed disruption of gastric homeostasis characterized by aberrant mucosal development and epithelial hyperproliferation; ultimately developing multiple features of gastric corpus preneoplasia including decreased parietal cells, mucous cell hyperplasia, spasmolytic peptide expressing metaplasia with intestinal characteristics, and dysplastic and invasive cystic glands. Furthermore, mutant corpus showed marked chronic inflammation characterized by infiltration of lymphocytes and myeloid-derived suppressor cells along with the upregulation of innate and adaptive immune system components. Striking upregulation of inflammatory mediators and STAT3 activation was observed. Mechanistically, we determined there is an activation of ERK1/2 and downregulation of BMP/SMAD signaling characterized by marked upregulation of BMP inhibitor gremlin 1.

CONCLUSIONS

We report a novel role of PKA signaling in gastric MEC execution and show that PKA activation in the gastric mesenchyme drives preneoplasia by creating a proinflammatory and proproliferative microenvironment associated with the downregulation of BMP/SMAD signaling and activation of ERK1/2.

Stem Cell Biomarkers and Tumorigenesis in Gastric Cancer

Stomach cancer has a high mortality, which is partially caused by an absence of suitable biomarkers to allow detection of the initiation stages of cancer progression. Thus, identification of critical biomarkers associated with gastric cancer (GC) is required to advance its clinical diagnoses and treatment. Recent studies using tracing models for lineage analysis of GC stem cells indicate that the cell fate decision of the gastric stem cells might be an important issue for stem cell plasticity. They include leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5⁺), Cholecystokinin receptor 2 (Cckr2⁺), and axis inhibition protein 2 (Axin2⁺) as the stem cell markers in the antrum, Trefoil Factor 2 (TFF2⁺), Mist1⁺ stem cells, and Troy+ chief cells in the corpus. By contrast, Estrogen receptor 1 (eR1), Leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), SRY (sex determining region Y)-box 2 (Sox2), and B lymphoma Mo-MLV insertion region 1 homolog (Bmi1) are rich in both the antrum and corpus regions. These markers might help to identify the cell-lineage identity and analyze the plasticity of each stem cell population. Thus, identification of marker genes for the development of GC and its environment is critical for the clinical application of cancer stem cells in the prevention of stomach cancers.

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.

Self-Renewal and Cancers of the Gastric Epithelium: An Update and the Role of the Lectin TFF1 as an Antral Tumor Suppressor

In 2020, gastric cancer was the fourth leading cause of cancer deaths globally. About 90% of gastric cancers are sporadic and the vast majority are correlated with Helicobacter pylori infection; whereas familial clustering is observed in about 10% of cases. Gastric cancer is now considered to be a disease originating from dysregulated self-renewal of the gastric glands in the setting of an inflammatory environment. The human stomach contains two types of gastric units, which show bi-directional self-renewal from a complex variety of stem cells. This review focuses on recent progress concerning the characterization of the different stem cell populations and the mainly mesenchymal signals triggering their stepwise differentiation as well as the genesis of pre-cancerous lesions and carcinogenesis. Furthermore, a model is presented (Lectin-triggered Receptor Blocking Hypothesis) explaining the role of the lectin TFF1 as an antral tumor suppressor possibly regulating Lgr5⁺ antral stem cells in a paracrine or maybe autocrine fashion, with neighboring antral gland cells having a role as niche cells.

Helicobacter pylori infection activates Wnt/β-catenin pathway to promote the occurrence of gastritis by upregulating ASCL1 and AQP5

Helicobacter pylori (H. pylori) infection is a well-recognized contributing factor to gastritis, but the underlying mechanisms remain to be established. It is interesting to note that AQP5 was predicted to be highly expressed in intestinal metaplasia (IM) based on H. pylori infection-related microarray data, and the transcription factor ASCL1 was bioinformatically predicted to associate with AQP5. Therefore, the purpose of this study is to evaluate the mechanistic significance of ASCL1 and AQP5 in H. pylori infection of gastritis. Gastritis mouse models were established by H. pylori infection, followed by determination of AQP5 and ASCL1 in gastric mucosa. Besides, the effects of AQP5 on H. pylori-induced gastritis were explored using AQP5^-/- mice. It was observed that H. pylori infection elevated expression of AQP5 and ASCL1 in gastric mucosa and gastric epithelial cells (GECs). H. pylori induced AQP5 expression by regulating ASCL1 and activated WNT/β-catenin signaling pathway in GECs. It was also found that AQP5 knockdown suppressed inflammatory response and apoptosis in H. pylori-infected mice. Moreover, H. pylori infection-elevated ASCL1 and AQP5 expression promoted apoptosis and inflammation in GECs. Taken together, the key findings of the present study demonstrate that H. pylori infection activated WNT/β-catenin signaling pathway by upregulating ASCL1/AQP5 to induce gastritis.

Microanalysis of the stomach of southern white-breasted hedgehog (Erinaceus concolor): Histological, histochemical, immunohistochemical, and scanning electron microscopic studies

This study was designed to provide more detailed knowledge on the stomach histochemistry and immunohistochemistry in the southern white-breasted hedgehog (Erinaceus concolor). Two animals were used in the present work. Periodic acid Schiff's (PAS) and Alcian blue were used for histochemical purposes. SOX9, gastrin, serotonin, and glucagon markers were traced immunohistochemically. The mucosa was extremely folded in the fundus with numerous opening of glands. The body and pylorus mucosa were almost smooth and equipped with gastric gland openings. A simple columnar epithelium covered the stomach entirely. Cardiac glands region was mucus secreting with both positive and negative reactions to PAS. Fundic mucosa was contained cardiac glands near to the cardia, and toward the body it was divided into the light and dark zones. These zones and body contained proper gastric gland, which constituted of parietal, chief, and mucous neck cells. These glands contained PAS-positive cells on their basal portions. The pyloric glands were mucus secreting but negative for PAS. All gastric glands were Alcian blue-negative, but epithelium showed moderate reaction especially in the pylorus. SOX and gastrin were express highly in the body and fundus. The expression of serotonin and glucagon was rare. Comparatively, some similarities between the stomach of hedgehog and dog can be assumed. The present findings provide additional information concerning the histochemical characteristics and endocrine cells distribution in the stomach of the southern white-breasted hedgehog (Erinaceus concolor). Further detailed studies are required to enhance the current knowledge on histophysiology of the digestive system in this species as a pet and exotic animal.

Morphogen Signals Shaping the Gastric Glands in Health and Disease

The adult gastric mucosa is characterised by deep invaginations of the epithelium called glands. These tissue architectural elements are maintained with the contribution of morphogen signals. Morphogens are expressed in specific areas of the tissue, and their diffusion generates gradients in the microenvironment. Cells at different positions in the gland sense a specific combination of signals that instruct them to differentiate, proliferate, regenerate, or migrate. Differentiated cells perform specific functions involved in digestion, such as the production of protective mucus and the secretion of digestive enzymes or gastric acid. Biopsies from gastric precancerous conditions usually display tissue aberrations and change the shape of the glands. Alteration of the morphogen signalling microenvironment is likely to underlie those conditions. Furthermore, genes involved in morphogen signalling pathways are found to be frequently mutated in gastric cancer. We summarise the most recent findings regarding alterations of morphogen signalling during gastric carcinogenesis, and we highlight the new stem cell technologies that are improving our understanding of the regulation of human tissue shape.

Intestinal Wnt in the transition from physiology to oncology

Adult stem cells are necessary for self-renewal tissues and regeneration after damage. Especially in the intestine, which self-renews every few days, they play a key role in tissue homeostasis. Therefore, complex regulatory mechanisms are needed to prevent hyperproliferation, which can lead in the worst case to carcinogenesis or under-activation of stem cells, which can result in dysfunctional epithelial. One main regulatory signaling pathway is the Wnt/β-catenin signaling pathway. It is a highly conserved pathway, with β-catenin, a transcription factor, as target protein. Translocation of β-catenin from cytoplasm to nucleus activates the transcription of numerous genes involved in regulating stem cell pluripo-tency, proliferation, cell differentiation and regulation of cell death. This review presents a brief overview of the Wnt/β-catenin signaling pathway, the regulatory mechanism of this pathway and its role in intestinal homeostasis. Additionally, this review highlights the molecular mechanisms and the histomorphological features of Wnt hyperactivation. Furthermore, the central role of the Wnt signaling pathway in intestinal carcinogenesis as well as its clinical relevance in colorectal carcinoma are discussed.

Functional human gastrointestinal organoids can be engineered from three primary germ layers derived separately from pluripotent stem cells

Human organoid model systems lack important cell types that, in the embryo, are incorporated into organ tissues during development. We developed an organoid assembly approach starting with cells from the three primary germ layers-enteric neuroglial, mesenchymal, and epithelial precursors-that were derived separately from human pluripotent stem cells (PSCs). From these three cell types, we generated human antral and fundic gastric tissue containing differentiated glands surrounded by layers of smooth muscle containing functional enteric neurons that controlled contractions of the engineered antral tissue. Using this experimental system, we show that human enteric neural crest cells (ENCCs) promote mesenchyme development and glandular morphogenesis of antral stomach organoids. Moreover, ENCCs can act directly on the foregut to promote a posterior fate, resulting in organoids with a Brunner's gland phenotype. Thus, germ layer components that are derived separately from PSCs can be used for tissue engineering to generate complex human organoids.

Infection with a hypervirulent strain of Helicobacter pylori primes gastric cells toward intestinal transdifferentiation

BACKGROUND

Intestinal metaplasia, gastric-to-intestinal transdifferentiation, occurs as a result of the misexpression of certain regulatory factors, leading to genetic reprogramming. Here, we have evaluated the H. pylori-induced expression patterns of these candidate genes.

METHODS

The expression levels of 1) tissue-specific transcription factors (RUNX3, KLF5, SOX2, SALL4, CDX1 and CDX2), 2) stemness factors (TNFRSF19, LGR5, VIL1) and 3) tissue-specific mucins (MUC5AC, MUC2) were evaluated by quantitative real-time PCR in gastric primary cells (GPCs), in parallel with two gastric cancer (MKN45 and AGS) cell lines, up to 96h following H. pylori infection.

RESULTS

Following H. pylori infection of GPCs, RUNX3 declined at 24h post infection (-6.2 ± 0.3) and remained downregulated for up to 96h. Subsequently, overexpression of self-renewal and pluripotency transcription factors, KLF5 (3.6 ± 0.2), SOX2 (7.6 ± 0.5) and SALL4 (4.3 ± 0.2) occurred. The expression of TNFRSF19 and LGR5, demonstrated opposing trends, with an early rise of the former (4.5 ± 0.3) at 8h, and a simultaneous fall of the latter (-1.8 ± 0.5). This trend was reversed at 96h, with the decline in TNFRSF19 (-5.5 ± 0.2), and escalation of LGR5 (2.6 ± 0.2) and VIL1 (1.8 ± 0.3). Ultimately, CDX1 and CDX2 were upregulated by 1.9 and 4.7-fold, respectively. The above scenario was, variably observed in MKN45 and AGS cells.

CONCLUSION

Our data suggests an interdependent gene regulatory network, induced by H. pylori infection. This interaction begins with the downregulation of RUNX3, upregulation of self-renewal and pluripotency transcription factors, KLF5, SOX2 and SALL4, leading to the downregulation of TNFRSF19, upregulation of LGR5 and aberrant expression of intestine-specific transcription factors, potentially facilitating the process of gastric-to-intestinal transdifferentiation.

Follow the Metaplasia: Characteristics and Oncogenic Implications of Metaplasia's Pattern of Spread Throughout the Stomach

The human stomach functions as both a digestive and innate immune organ. Its main product, acid, rapidly breaks down ingested products and equally serves as a highly effective microbial filter. The gastric epithelium has evolved mechanisms to appropriately handle the myriad of injurious substances, both exogenous and endogenous, to maintain the epithelial barrier and restore homeostasis. The most significant chronic insult that the stomach must face is Helicobacter pylori (Hp), a stomach-adapted bacterium that can colonize the stomach and induce chronic inflammatory and pre-neoplastic changes. The progression from chronic inflammation to dysplasia relies on the decades-long interplay between this oncobacterium and its gastric host. This review summarizes the functional and molecular regionalization of the stomach at homeostasis and details how chronic inflammation can lead to characteristic alterations in these developmental demarcations, both at the topographic and glandular levels. More importantly, this review illustrates our current understanding of the epithelial mechanisms that underlie the pre-malignant gastric landscape, how Hp adapts to and exploits these changes, and the clinical implications of identifying these changes in order to stratify patients at risk of developing gastric cancer, a leading cause of cancer-related deaths worldwide.

The pediatric stomach - congenital abnormalities

Diagnostic imaging of the pediatric stomach often provides a challenge for practicing radiologists. Radiologists should be aware of relatively unusual congenital pathology, especially when imaging very young children with gastrointestinal symptoms. We review congenital pathology of the pediatric stomach.

Cross-tissue single-cell transcriptomic landscape reveals the key cell subtypes and their potential roles in the nutrient absorption and metabolism in dairy cattle

•

Discover 55 cell types and their specific markers in the first single-cell atlas of cattle;

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Identify and verify 3 epithelial progenitor-like cell subtypes in the forestomach

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Reveal vital but nonimmune functions of neutrophils in the mammary gland;

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Uncover key cell subtypes with preferential nutrient uptake;

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Find Th17 cells regulate epithelial cells responding to nutrient transport in the forestomach.

Introduction

Dairy cattle are a vitally important ruminant in meeting the demands for high-quality animal protein production worldwide. The complicated biological process of converting human indigestible biomass into highly digestible and nutritious milk is orchestrated by various tissues. However, poorly understanding of the cellular composition and function of the key metabolic tissues hinders the improvement of health and performance of domestic ruminants.

Objectives

The cellular heterogeneity, metabolic features, interactions across ten tissue types of lactating dairy cattle were studied at single-cell resolution in the current study.

Methods

Unbiased single-cell RNA-sequencing and analysis were performed on the rumen, reticulum, omasum, abomasum, ileum, rectum, liver, salivary gland, mammary gland, and peripheral blood of lactating dairy cattle. Immunofluorescences and fluorescence in situ hybridization were performed to verify cell identity.

Results

In this study, we constructed a single-cell landscape covering 88,013 high-quality (500 < genes < 4,000, UMI < 50, 000, and mitochondrial gene ratio < 40% or 15%) single cells and identified 55 major cell types in lactating dairy cattle. Our systematic survey of the gene expression profiles and metabolic features of epithelial cells related to nutrient transport revealed cell subtypes that have preferential absorption of different nutrients. Importantly, we found that T helper type 17 (Th17) cells (highly expressing CD4 and IL17A) were specifically enriched in the forestomach tissues and predominantly interacted with the epithelial cell subtypes with high potential uptake capacities of short-chain fatty acids through IL-17 signaling. Furthermore, the comparison between IL17RA^highIL17RC^high cells (epithelial cells with IL17RA and IL17RC expression levels both greater than 0.25) and other cells explained the importance of Th17 cells in regulating the epithelial cellular transcriptional response to nutrient transport in the forestomach.

Conclusion

The findings enhance our understanding of the cellular biology of ruminants and open new avenues for improved animal production of dairy cattle.

Gastric Organoids: Progress and Remaining Challenges

The stomach is a complex and physiologically necessary organ, yet large differences in physiology between mouse and human stomachs have impeded translation of physiological discoveries and drug screens performed using murine gastric tissues. Gastric cancer (GC) is a global health threat, with a high mortality rate and limited treatment options. The heterogeneous nature of GC makes it poorly suited for current "one size fits all" standard treatments. In this review, we discuss the rapidly evolving field of gastric organoids, with a focus on studies expanding cultures from primary human tissues and describing the benefits of mouse organoid models. We introduce the differing methods for culturing healthy gastric tissue from adult tissues or pluripotent stem cells, discuss the promise these systems have for preclinical drug screens, and highlight applications of organoids for precision medicine. Finally, we discuss the limitations of these models and look to the future to present potential ways gastric organoids will advance treatment options for patients with GC.

Translational models of 3-D organoids and cancer stem cells in gastric cancer research

It is postulated as a general concept of cancer stem cells (CSCs) that they can produce cancer cells overtly and repopulate cancer progenitor cells indefinitely. The CSC niche is part of a specialized cancer microenvironment that is important to keep the phenotypes of CSCs. Stem cell- and induced pluripotent stem cell (iPSC)-derived organoids with genetic manipulation are beneficial to the investigation of the regulation of the microenvironment of CSCs. It would be useful to assess the efficiency of the cancer microenvironment on initiation and progression of cancers. To identify CSCs in cancer tissues, normal cell organoids and gastric cancer organoids from the cancerous areas, as well as iPSCs, were established several years ago. However, many questions remain about the extent to which these cultures recapitulate the development of the gastrointestinal tract and the mechanism of Helicobacter pylori-induced cancer progression. To clarify the fidelity of human organoid models, we have noted several key issues for the cultivation of, and differences between, normal and cancerous organoids. We developed precise culture conditions for gastric organoids in vitro to improve the accuracy of the generation of organoid models for therapeutic and medical applications. In addition, the current knowledge on gastrointestinal CSC research, including the topic of CSC markers, cancer cell reprogramming, and application to target cancer cell plasticity through niches, should be reinforced. We discuss the progression of cancers derived from human gastric organoids and the identification of CSCs.

Organoid technology for tissue engineering

For centuries, attempts have been continuously made to artificially reconstitute counterparts of in vivo organs from their tissues or cells. Only in the recent decade has organoid technology as a whole technological field systematically emerged and been shown to play important roles in tissue engineering. Based on their self-organizing capacities, stem cells of versatile organs, both harvested and induced, can form 3D structures that are structurally and functionally similar to their in vivo counterparts. These organoid models provide a powerful platform for elucidating the development mechanisms, modeling diseases, and screening drug candidates. In this review, we will summarize the advances of this technology for generating various organoids of tissues from the three germ layers and discuss their drawbacks and prospects for tissue engineering.

Stem cells and origins of cancer in the upper gastrointestinal tract

The esophagus and stomach, joined by a unique transitional zone, contain actively dividing epithelial stem cells required for organ homeostasis. Upon prolonged inflammation, epithelial cells in both organs can undergo a cell fate switch leading to intestinal metaplasia, predisposing to malignancy. Here we discuss the biology of gastroesophageal stem cells and their role as cells of origin in cancer. We summarize the interactions between the stromal niche and gastroesophageal stem cells in metaplasia and early expansion of mutated stem-cell-derived clones during carcinogenesis. Finally, we review new approaches under development to better study gastroesophageal stem cells and advance the field.

A genome-scale CRISPR screen reveals factors regulating Wnt-dependent renewal of mouse gastric epithelial cells

An ability to safely harness the powerful regenerative potential of adult stem cells for clinical applications is critically dependent on a comprehensive understanding of the underlying mechanisms regulating their activity. Epithelial organoid cultures accurately recapitulate many features of in vivo stem cell-driven epithelial renewal, providing an excellent ex vivo platform for interrogation of key regulatory mechanisms. Here, we employed a genome-scale clustered, regularly interspaced, short palindromic repeats (CRISPR) knockout (KO) screening assay using mouse gastric epithelial organoids to identify modulators of Wnt-driven stem cell-dependent epithelial renewal in the gastric mucosa. In addition to known Wnt pathway regulators, such as Apc, we found that KO of Alk, Bclaf3, or Prkra supports the Wnt independent self-renewal of gastric epithelial cells ex vivo. In adult mice, expression of these factors is predominantly restricted to non-Lgr5-expressing stem cell zones above the gland base, implicating a critical role for these factors in suppressing self-renewal or promoting differentiation of gastric epithelia. Notably, we found that Alk inhibits Wnt signaling by phosphorylating the tyrosine of Gsk3β, while Bclaf3 and Prkra suppress regenerating islet-derived (Reg) genes by regulating the expression of epithelial interleukins. Therefore, Alk, Bclaf3, and Prkra may suppress stemness/proliferation and function as novel regulators of gastric epithelial differentiation.

GATA4 Controls Epithelial Morphogenesis in the Developing Stomach to Promote Establishment of Glandular Columnar Epithelium

BACKGROUND & AIMS

The transcription factor GATA4 is broadly expressed in nascent foregut endoderm. As development progresses, GATA4 is lost in the domain giving rise to the stratified squamous epithelium of the esophagus and forestomach (FS), while it is maintained in the domain giving rise to the simple columnar epithelium of the hindstomach (HS). Differential GATA4 expression within these domains coincides with the onset of distinct tissue morphogenetic events, suggesting a role for GATA4 in diversifying foregut endoderm into discrete esophageal/FS and HS epithelial tissues. The goal of this study was to determine how GATA4 regulates differential morphogenesis of the mouse gastric epithelium.

METHODS

We used a Gata4 conditional knockout mouse line to eliminate GATA4 in the developing HS and a Gata4 conditional knock-in mouse line to express GATA4 in the developing FS.

RESULTS

We found that GATA4-deficient HS epithelium adopted a FS-like fate, and conversely, that GATA4-expressing FS epithelium adopted a HS-like fate. Underlying structural changes in these epithelia were broad changes in gene expression networks attributable to GATA4 directly activating or repressing expression of HS or FS defining transcripts. Our study implicates GATA4 as having a primary role in suppressing an esophageal/FS transcription factor network during HS development to promote columnar epithelium. Moreover, GATA4-dependent phenotypes in developmental mutants reflected changes in gene expression associated with Barrett's esophagus.

CONCLUSIONS

This study demonstrates that GATA4 is necessary and sufficient to activate the development of simple columnar epithelium, rather than stratified squamous epithelium, in the embryonic stomach. Moreover, similarities between mutants and Barrett's esophagus suggest that developmental biology can provide insight into human disease mechanisms.

Human gastrointestinal epithelia of the esophagus, stomach, and duodenum resolved at single-cell resolution

The upper gastrointestinal tract, consisting of the esophagus, stomach, and duodenum, controls food transport, digestion, nutrient uptake, and hormone production. By single-cell analysis of healthy epithelia of these human organs, we molecularly define their distinct cell types. We identify a quiescent COL17A1high KRT15high stem/progenitor cell population in the most basal cell layer of the esophagus and detect substantial gene expression differences between identical cell types of the human and mouse stomach. Selective expression of BEST4, CFTR, guanylin, and uroguanylin identifies a rare duodenal cell type, referred to as BCHE cell, which likely mediates high-volume fluid secretion because of continual activation of the CFTR channel by guanylin/uroguanylin-mediated autocrine signaling. Serotonin-producing enterochromaffin cells in the antral stomach significantly differ in gene expression from duodenal enterochromaffin cells. We, furthermore, discover that the histamine-producing enterochromaffin-like cells in the oxyntic stomach express the luteinizing hormone, yet another member of the enteroendocrine hormone family.

Evolution of organoid technology: Lessons learnt in Co-Culture systems from developmental biology

In recent years, the development of 3D organoids has opened new avenues of investigation into development, physiology, and regenerative medicine. Organoid formation and the process of organogenesis share common developmental pathways; thus, our knowledge of developmental biology can help model the complexity of different organs to refine organoids into a more sophisticated platform. The developmental process is strongly dependent on complex networks and communication of cell-cell and cell-matrix interactions among different cell populations and their microenvironment, during embryogenesis. These interactions affect cell behaviors such as proliferation, survival, migration, and differentiation. Co-culture systems within the organoid technology were recently developed and provided the highly physiologically relevant systems. Supportive cells including various types of endothelial and stromal cells provide the proper microenvironment, facilitate organoid assembly, and improve vascularization and maturation of organoids. This review discusses the role of the co-culture systems in organoid generation, with a focus on how knowledge of developmental biology has directed and continues to shape the development of more evolved 3D co-culture system-derived organoids.