Epithelium Of Intestinal Villi Research Articles

Transcriptome and 16S rRNA Analyses Reveal That Hypoxic Stress Affects the Antioxidant Capacity of Largemouth Bass (Micropterus salmoides), Resulting in Intestinal Tissue Damage and Structural Changes in Microflora.

Dissolved oxygen (DO) is a key factor affecting the health of aquatic organisms in an intensive aquaculture environment. In this study, largemouth bass (Micropterus salmoides) were subjected to acute hypoxic stress for 96 h (DO: 1.00 mg/L) followed by recovery under sufficient DO conditions (DO: 7.50 mg/L) for 96 h. Serum biochemical indices, intestinal histomorphology, the transcriptome, and intestinal microbiota were compared between hypoxia-treated fish and those in a control group. The results showed that hypoxia caused oxidative stress, exfoliation of the intestinal villus epithelium and villus rupture, and increased cell apoptosis. Transcriptome analyses revealed that antioxidant-, inflammation-, and apoptosis-related pathways were activated, and that the MAPK signaling pathway played an important role under hypoxic stress. In addition, 16S rRNA sequencing analyses revealed that hypoxic stress significantly decreased bacterial richness and identified the dominant phyla (Proteobacteria, Firmicutes) and genera (Mycoplasma, unclassified Enterobacterales, Cetobacterium) involved in the intestinal inflammatory response of largemouth bass. Pearson's correlation analyses showed that differentially expressed genes in the MAPK signaling pathway were significantly correlated with some microflora. The results of this study will help to develop strategies to reduce damage caused by hypoxic stress in aquacultured fish.

Organoids to Dissect Gastrointestinal Virus-Host Interactions: What Have We Learned?

Historically, knowledge of human host–enteric pathogen interactions has been elucidated from studies using cancer cells, animal models, clinical data, and occasionally, controlled human infection models. Although much has been learned from these studies, an understanding of the complex interactions between human viruses and the human intestinal epithelium was initially limited by the lack of nontransformed culture systems, which recapitulate the relevant heterogenous cell types that comprise the intestinal villus epithelium. New investigations using multicellular, physiologically active, organotypic cultures produced from intestinal stem cells isolated from biopsies or surgical specimens provide an exciting new avenue for understanding human specific pathogens and revealing previously unknown host–microbe interactions that affect replication and outcomes of human infections. Here, we summarize recent biologic discoveries using human intestinal organoids and human enteric viral pathogens.

LEVEL OF PRO- AND ANTI-INFLAMMATORY CYTOKINES IN PIGLETS WITH GASTROINTESTINAL DISEASES OF BACTERIAL ETIOLOGY

The study presents the data on the level of expression of pro- and anti-inflammatory cytokines in piglets with gas-trointestinal diseases of bacterial etiology. The analysis of gene expression showed that the expression levels of IL-1α and IL-10 were significantly increased in sick piglets, while IL-1β lost its activity. During the histological examination, there were no differences between the structure of the intestines of sick and healthy piglets. However, cytological examination: of the samples obtained from sick piglets demonstrated alteration and a decrease in the adhesive barrier in the epithelium of intestinal villi.

Distribution of aquaporins and sodium transporters in the gastrointestinal tract of a desert hare, Lepus yarkandensis

Lepus yarkandensis is a desert hare of the Tarim Basin in western China, and it has strong adaptability to arid environments. Aquaporins (AQPs) are a family of water channel proteins that facilitate transmembrane water transport. Gastrointestinal tract AQPs are involved in fluid absorption in the small intestine and colon. This study aimed to determine the distribution of AQPs and sodium transporters in the gastrointestinal tract of L. yarkandensis and to compare the expression of these proteins with that in Oryctolagus cuniculus. Immunohistochemistry was performed to analyse the cellular distribution of these proteins, and the acquired images were analysed with IpWin32 software. Our results revealed that AQP1 was located in the colonic epithelium, central lacteal cells, fundic gland parietal cells, and capillary endothelial cells; AQP3 was located in the colonic epithelium, small intestinal villus epithelium, gastric pit and fundic gland; AQP4 was located in the fundic gland, small intestinal gland and colonic epithelium; and epithelial sodium channel (ENaC) and Na+-K+-ATPase were located in the epithelial cells, respectively. The higher expression levels of AQP1, AQP3, ENaC and Na+-K+-ATPase in the colon of L. yarkandensis compared to those in O. cuniculus suggested that L. yarkandensis has a higher capacity for faecal dehydration.

Effects of force-feeding on immunology, digestive function and oxidative stress in the duodenal and jejunal mucosa of Pekin ducks

Force-feeding was considered as a traditional high-efficiency approach to improve growth performance and accelerate fat deposition of Pekin ducks. However, force-feeding is a serious violation of international advocacy on animal welfare, because it can induce serious injuries to animals, such as damages to the digestive tract, effects on immunity and even severe oxidative stress. Therefore, it is urgent to stop force-feeding. The aim of this study was to determine the effects of force feeding on immune function, digestive function and oxidative stress in the mucosa of duodenum and jejunum of Pekin ducks. A total of 500 ducks were randomly divided into two groups. The control group was allowed to feed freely on a basal diet. The experimental group was force-fed by inserting a plastic feeding tube 8 to 10 inches long down the esophagus for 6 days. Compared with the control group, there was a significant (P<0.05) increase in serum diamine oxidase, d-lactic acid, endotoxin and corticosterone levels in the force-feeding group. The crypt depth in duodenum and jejunum showed significant differences (P<0.05) between the two groups and the intestinal villus epithelium cell was severely damaged in force-feeding group. Similarly, the activities of digestive enzymes as well as the levels of immune function in the duodenal and jejunal mucosa in the force-feeding group were significantly higher than the control group (P<0.05). However, there was a significant decrease in the superoxide dismutase, glutathione peroxidase and catalase levels with a marked increase in malondialdehyde level in duodenal and jejunal mucosa (P<0.05). In summary, at the end of the fattening period with force-feeding for 6 days, Pekin ducks experienced an adverse effect on the integrity of their duodenal and jejunal mucosa epithelium cell as well as their immune function and antioxidant capacity of Pekin ducks but also had improvement in digestive enzyme activities.

Peyer's patch myeloid cells infection by Listeria signals through gp38+ stromal cells and locks intestinal villus invasion.

The foodborne pathogen Listeria monocytogenes (Lm) crosses the intestinal villus epithelium via goblet cells (GCs) upon the interaction of Lm surface protein InlA with its receptor E-cadherin. Here, we show that Lm infection accelerates intestinal villus epithelium renewal while decreasing the number of GCs expressing luminally accessible E-cadherin, thereby locking Lm portal of entry. This novel innate immune response to an enteropathogen is triggered by the infection of Peyer's patch CX3CR1+ cells and the ensuing production of IL-23. It requires STAT3 phosphorylation in epithelial cells in response to IL-22 and IL-11 expressed by lamina propria gp38+ stromal cells. Lm-induced IFN-γ signaling and STAT1 phosphorylation in epithelial cells is also critical for Lm-associated intestinal epithelium response. GC depletion also leads to a decrease in colon mucus barrier thickness, thereby increasing host susceptibility to colitis. This study unveils a novel innate immune response to an enteropathogen, which implicates gp38+ stromal cells and locks intestinal villus invasion, but favors colitis.

An innovative cell-printed microscale collagen model for mimicking intestinal villus epithelium

Cell-printing technology for obtaining a cell-laden structure has been extensively used in tissue engineering applications due to its advantages over the conventional scaffold, which is not simultaneously fabricated with cells. To date, a realistic villi model using cell-laden bioink with both the biocompatibility and mechanical strength to achieve villus structure has not been developed. Here, we developed a human intestinal villi model with an innovative cell-printing process. The cell-laden villus structure was fabricated using a cell-laden collagen bioink cross-linked with a natural polyphenol (tannic acid). The fabricating condition was optimized and a Caco-2-laden collagen villus structure was fabricated. Using the processing conditions, a 3D collagen villus structure with appropriate geometry and a high initial cell-viability (over 90%) was obtained. In vitro cellular activities of the cell-laden villus structure demonstrated satisfactory cell viability with a growth-rate meaningfully higher than that in the fabricated villi structure cultured with the cell-seeding method (control). Moreover, expression of MUC17, junction marker (E-Cadherin), and alkaline phosphatase, as differentiation indicators of the epithelial cells, was significantly higher and earlier in the cell-laden structure compared to that in the control. These results indicate that the modified cell-printing process using collagen-bioink would be a highly efficient model mimicking the human intestinal epithelium.

DOT1L-Mediated H3K79 Methylation in Chromatin Is Dispensable for Wnt Pathway-Specific and Other Intestinal Epithelial Functions

Methylation of H3K79 is associated with chromatin at expressed genes, though it is unclear if this histone modification is required for transcription of all genes. Recent studies suggest that Wnt-responsive genes depend particularly on H3K79 methylation, which is catalyzed by the methyltransferase DOT1L. Human leukemias carrying MLL gene rearrangements show DOT1L-mediated H3K79 methylation and aberrant expression of leukemogenic genes. DOT1L inhibitors reverse these effects, but their clinical use is potentially limited by toxicity in Wnt-dependent tissues such as intestinal epithelium. Genome-wide positioning of the H3K79me2 mark in Lgr5(+) mouse intestinal stem cells and mature intestinal villus epithelium correlated with expression levels of all transcripts and not with Wnt-responsive genes per se. Selective Dot1l disruption in Lgr5(+) stem cells or in whole intestinal epithelium eliminated H3K79me2 from the respective compartments, allowing genetic evaluation of DOT1L requirements. The absence of methylated H3K79 did not impair health, intestinal homeostasis, or expression of Wnt target genes in crypt epithelium for up to 4 months, despite increased crypt cell apoptosis. Global transcript profiles in Dot1l-null cells were barely altered. Thus, H3K79 methylation is not essential for transcription of Wnt-responsive or other intestinal genes, and intestinal toxicity is not imperative when DOT1L is rendered inactive in vivo.

Physiological relevance of cell-specific distribution patterns of CFTR, NKCC1, NBCe1, and NHE3 along the crypt-villus axis in the intestine.

We examined the cell-specific subcellular expression patterns for sodium- and potassium-coupled chloride (NaK2Cl) cotransporter 1 (NKCC1), Na(+) bicarbonate cotransporter (NBCe1), cystic fibrosis transmembrane conductance regulator (CFTR), and Na(+)/H(+) exchanger 3 (NHE3) to understand the functional plasticity and synchronization of ion transport functions along the crypt-villus axis and its relevance to intestinal disease. In the unstimulated intestine, all small intestinal villus enterocytes coexpressed apical CFTR and NHE3, basolateral NBCe1, and mostly intracellular NKCC1. All (crypt and villus) goblet cells strongly expressed basolateral NKCC1 (at approximately three-fold higher levels than villus enterocytes), but no CFTR, NBCe1, or NHE3. Lower crypt cells coexpressed apical CFTR and basolateral NKCC1, but no NHE3 or NBCe1 (except NBCe1-expressing proximal colonic crypts). CFTR, NBCe1, and NKCC1 colocalized with markers of early and recycling endosomes, implicating endocytic recycling in cell-specific anion transport. Brunner's glands of the proximal duodenum coexpressed high levels of apical/subapical CFTR and basolateral NKCC1, but very low levels of NBCe1, consistent with secretion of Cl(-)-enriched fluid into the crypt. The cholinergic agonist carbachol rapidly (within 10 min) reduced cell volume along the entire crypt/villus axis and promoted NHE3 internalization into early endosomes. In contrast, carbachol induced membrane recruitment of NKCC1 and CFTR in all crypt and villus enterocytes, NKCC1 in all goblet cells, and NBCe1 in all villus enterocytes. These observations support regulated vesicle traffic in Cl(-) secretion by goblet cells and Cl(-) and HCO(3)(-) secretion by villus enterocytes during the transient phase of cholinergic stimulation. Overall, the carbachol-induced membrane trafficking profile of the four ion transporters supports functional plasticity of the small intestinal villus epithelium that enables it to conduct both absorptive and secretory functions.

Microbial regulation of intestinal radiosensitivity

We describe a method for treating germ-free (GF) mice with gamma-irradiation and transplanting them with normal or genetically manipulated bone marrow while maintaining their GF status. This approach revealed that GF mice are markedly resistant to lethal radiation enteritis. Furthermore, administering lethal doses of total body irradiation to GF mice produces markedly fewer apoptotic endothelial cells and lymphocytes in the mesenchymal cores of their small intestinal villi, compared with conventionally raised animals that have acquired a microbiota from birth. Analysis of GF and conventionally raised Rag1-/- mice disclosed that mature lymphocytes are not required for the development of lethal radiation enteritis or the microbiota-associated enhancement of endothelial radiosensitivity. Studies of gnotobiotic knockout mice that lack fasting-induced adipose factor (Fiaf), a fibrinogen/angiopoietin-like protein normally secreted from the small intestinal villus epithelium and suppressed by the microbiota, showed that Fiaf deficiency results in loss of resistance of villus endothelial and lymphocyte populations to radiation-induced apoptosis. Together, these findings provide insights about the cellular and molecular targets involved in microbial regulation of intestinal radiosensitivity.

Transient changes of transforming growth factor-β expression in the small intestine of the pig in association with weaning

It is well known that early weaning causes marked changes in intestinal structure and function, and transforming growth factor-beta (TGF-beta) is believed to play an important regulatory role in post-weaning adaptation of the small intestine. The present study examined the distribution and expression intensity of TGF-beta in the small intestinal mucosa of pre- and post-weaning pigs using a specific immunostaining technique and Western blot analysis. The level of TGF-beta in the intestinal mucosa, as estimated by Western blot analysis, did not change significantly during weaning. However, when examined by the immunostaining technique, TGF-beta1 (one of the TGF-beta isoforms dominantly expressed in the tissue) at the intestinal villus epithelium, particularly at the apical membrane of the epithelium, decreased significantly 4 d after weaning, while the staining intensity increased significantly at the intestinal crypts compared with that in pre-weaning pigs. These changes were transient, with the immunostaining intensity for TGF-beta1 at the intestinal villi and the crypts returning to the pre-weaning level by 8 d post-weaning. The transient decrease in TGF-beta1 level at the intestinal villus epithelium was associated with obvious intestinal villus atrophy and marked reduction of mucosal digestive enzyme activities. Furthermore, the number of leucocytes staining positively for TGF-beta1 increased significantly in the pig intestinal lamina propria 4 d after weaning. These findings strongly suggest that TGF-beta plays an important role in the post-weaning adaptation process in the intestine of the pig.

Alterations in hexose, amino acid and peptide transporter expression in intestinal epithelial cells during Nippostrongylus brasiliensis infection in the rat

Infection with the nematode Nippostrongylus brasiliensis induces various types of cytological alterations in the intestinal villus epithelium. The aim of this study was to analyse the expression of hexose, peptide and amino acid transporters in the small intestinal epithelium after infection. Brown-Norway rats were infected with 2000 N. brasiliensis L3 larvae and villus epithelial cells were isolated at various time points after infection. Expression of hexose transporters Na +/glucose cotransporter SGLT1 and glucose transporter GLUT-1, -2 and -5, a peptide transporter (PepT1) and an amino acid transporter (LAT2) was examined by reverse transcription-PCR, Western blotting or immunohistochemistry. Semi-quantitative reverse transcription-PCR studies of separated jejunal epithelial cells showed that expression levels of GLUT5, PepT1 and LAT2 were significantly decreased 7 and 14 days after infection, while these changes were not observed in the ileal epithelium. Although the apical surface glucose transporter SGLT1 showed no significant alteration in mRNA expression, Western blotting analyses of jejunal epithelial cell lysate showed a marked decrease. Contrary to SGLT1, GLUT5, PepT1 and LAT2, expression of GLUT1, which is essential in maintaining high rates of glucose influx, was significantly up-regulated in the jejunal epithelium 7 and 14 days after infection in reverse transcription-PCR as in Western blotting analyses. Immunohistochemical studies showed that GLUT1 immunoreactivity was localised to the basolateral membrane of intestinal epithelial cells 7 days after infection. These results show that N. brasiliensis infection results in an increase in GLUT1 and a decrease in various hexose, amino acid and peptide transporter expression in jejunal epithelial cells. Up-regulation of GLUT1 might be a compensatory response in injured epithelial cells.

Cell type-specific expressions of c-ras gene products in the normal rat.

Expression of proteins encoded by the ras proto-oncogenes was examined immunohistochemically in formalin-fixed, paraffin-embedded tissues of the normal rat using anti-ras p21 antibodies generated against synthetic peptides. Cell type specific expressions of ras gene products were detected in distal tubules of kidney, megakaryocytes in spleen, neural cells in cerebrum, Purkinje cells in cerebellum, cells lining the pulmonary alveoli and cells in the epithelium of intestinal villi. Region specific expressions of the ras proteins were observed in spleen and thymus, where the ras proteins were detected in splenic nodules including germinal centers and thymic medulla, respectively. These findings suggest that the c-ras gene products in normal rat organs are expressed in specific cell-types within a tissue and may be associated with degree of cellular differentiation.

Fluidity of the neural epithelium during forebrain formation in rat embryos.

During neurulation in rat embryos, the forebrain grows more rapidly than can be accounted for by intrinsic cell division alone, while the adjacent midbrain/rostral hindbrain maintains a constant cell number despite a high mitotic index (the cell cycle time is 6 h throughout the neural epithelium). We have proposed that neuroepithelial cells flow in a rostral direction within the midbrain/rostral hindbrain region, towards and into the rapidly expanding forebrain. Evidence in support of this hypothesis is provided by cell-labelling studies: labelled neuroepithelial cells were injected into specific sites in the midbrain or rostral hindbrain neuroepithelium of unlabelled embryos; after culture of these embryos for 24 h, the labelled cells were found in positions rostral to the injection sites. In the midbrain/rostral hindbrain region, mitotic spindles were found to be predominantly orientated parallel with the long axis of the embryo; transversely orientated spindles were more frequently observed close to the lateral edges than more medially. Neural crest cells emigrate from the lateral edges during neurulation. These observations suggest that mitotic spindle orientation reflects the direction of cell movement: in the lateral region movement towards the lateral edge would maintain cell number in the transverse plane as neural crest cells emigrate; elsewhere, cells are moving mainly in the longitudinal plane, towards the forebrain. The possible causal relationship between cell movement and mitotic spindle orientation is discussed. Cell flow within the intact neural epithelium is compared with cell flow in the intestinal villus epithelium. Other types of epithelial cell movement observed in the cranial neural epithelium during neurulation include expansion and shrinkage of the epithelial surface associated with change of cell shape and microfilament-mediated curvature. Cell rearrangement involving exchange of neighbours and cell movement towards and into a site of epithelio-mesenchymal conversion are also implicated.

Epithelial Cell Migration in the Alimentary Mucosa of the Suckling Pig

SummaryThe small intestinal villus epithelium in day-old pigs was replaced in 7-10 days, while that in 3-week-old pigs was replaced in 2-4 days. Decreased replacement time with age was associated with an increase in crypt depth and a decrease in villus length. Epithelia in the large intestine were also replaced more slowly in day-old than in 3-week-old pigs. Squamous epithelia in esophagus and stomach were replaced at similar rates in both age groups.