Intestinal Epithelial Cell Proliferation Research Articles

Nutritional strategies to reduce intestinal cell apoptosis by alleviating oxidative stress

Abstract The gut barrier is the first line of defense against harmful substances and pathogens in the intestinal tract. The balance of proliferation and apoptosis of intestinal epithelial cells (IECs) is crucial for maintaining the integrity of the intestinal mucosa and its function. However, oxidative stress and inflammation can cause DNA damage and abnormal apoptosis of the IECs, leading to the disruption of the intestinal epithelial barrier. This, in turn, can directly or indirectly cause various acute and chronic intestinal diseases. In recent years, there has been a growing understanding of the vital role of dietary ingredients in gut health. Studies have shown that certain amino acids, fibers, vitamins, and polyphenols in the diet can protect IECs from excessive apoptosis caused by oxidative stress, and limit intestinal inflammation. This review aims to describe the molecular mechanism of apoptosis and its relationship with intestinal function, and to discuss the modulation of IECs' physiological function, the intestinal epithelial barrier, and gut health by various nutrients. The findings of this review may provide a theoretical basis for the use of nutritional interventions in clinical intestinal disease research and animal production, ultimately leading to improved human and animal intestinal health.

Selection of Fermentation Supernatant from Probiotic Strains Exhibiting Intestinal Epithelial Barrier Protective Ability and Evaluation of Their Effects on Colitis Mouse and Weaned Piglet Models.

The intestinal epithelial barrier can prevent the invasion of pathogenic microorganisms and food antigens to maintain a consistent intestinal homeostasis. However, an imbalance in this barrier can result in various diseases, such as inflammatory bowel disease, malnutrition, and metabolic disease. Thus, the aim of this study was to select probiotic strains with epithelial barrier-enhancing ability in cell-based model and further investigate them for their improving effects on colitis mouse and weaned piglet models. The results showed that selected specific cell-free fermentation supernatants (CFSs) from Ligilactobacillus salivarius P1, Lactobacillus gasseri P12, and Limosilactobacillus reuteri G7 promoted intestinal epithelial cell growth and proliferation, strengthening the intestinal barrier in an intestinal epithelial cell line Caco-2 model. Further, the administration of CFSs of L. salivarius P1, L. gasseri P12, and L. reuteri G7 were found to ameliorate DSS-induced colitis in mice. Additionally, spray-dried powders of CFS from the three strains were examined in a weaned piglet model, only CFS powder of L. reuteri G7 could ameliorate the feed/gain ratio and serum levels of D-lactate and endotoxin. In conclusion, a new potential probiotic strain, L. reuteri G7, was selected and showed ameliorating effects in both colitis mouse and weaned piglet models.

Tropomyosin 2 Regulates Tumor Cell Proliferation, Immune Suppression, and Activation of the JNK Signaling Pathway in Colitis-Associated Cancer (CAC).

Tropomyosin 2 (TPM2) has been linked to the advancement of various tumor types, exhibiting distinct impacts on tumor progression. In our investigation, the primary objective was to identify the potential involvement of TPM2 in the development of colitis-associated cancer (CAC) using a mice model. This study used lentiviral vector complex for TPM2 knockdown (sh-TPM2) and the corresponding negative control lentiviral vector complex (sh-NC) for genetic interference in mice. CAC was induced in mice using azoxymethane (AOM) and dextran sulfate sodium salt (DSS). This study included 6 groups of mice models: Control, Control+sh-NC, Control+sh-TPM2, CAC, CAC+sh-NC, and CAC+sh-TPM2. Subsequently, colon tissues were collected and assessed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for TPM2 mRNA levels and flow cytometry for infiltrating immune cells. Tumor number, size, and weight within colon tissues from CAC mice were measured and recorded. The hematoxylin-eosin staining was used for observing tissue pathology changes. The intestinal epithelial cells (IECs) were isolated and analyzed for cell proliferation. This analysis included examining the levels of 5-bromo-2-deoxyuridine (BrdU) and Ki-67 using immunohistochemistry. Additionally, the mRNA levels of proliferating cell nuclear antigen (PCNA) and Ki-67 were detected by qRT-PCR. This study also investigated the activation of the c-Jun N-terminal kinase (JNK) pathway using western blot analysis. Immunogenicity analyses were conducted using immunohistochemistry for F4/80 and flow cytometry. In 8-week-old mice, AOM injections and three cycles of DSS treatment induced TPM2 upregulation in tumor tissues compared to normal tissues (p < 0.05). Fluorescence-activated cell sorting (FACS)-isolated lamina CAC adenomas revealed macrophages and dendritic cells as primary TPM2 contributors (p < 0.001). Lentiviral TPM2 gene knockdown significantly reduced tumor numbers and sizes in CAC mice (p < 0.01, and p < 0.001), without invasive cancer cells. TPM2 suppression resulted in decreased IEC proliferation (p < 0.001) and reduced PCNA and Ki-67 expression (p < 0.05). Western blot analysis indicated reduced JNK pathway activation in TPM2-knockdown CAC mice (p < 0.05, p < 0.001). TPM2 knockdown decreased tumor-associated macrophage infiltration (p < 0.01) and increased CD3+ and CD8+ T cells (p < 0.01, and p < 0.001), with increased levels of regulator of inflammatory cytokines (CD44+, CD107a+) (p < 0.01, and p < 0.001), decreased levels of PD-1+ and anti-inflammatory factor (IL10+) (p < 0.01, and p < 0.001). Our results demonstrated that TPM2 knockdown suppressed the proliferation of CAC IECs, enhanced immune suppression on CAC IECs, and inhibited the JNK signaling pathway within the framework of CAC. These findings suggest TPM2 can serve as a potential therapeutic target for CAC treatment.

Glutamine Promotes Porcine Intestinal Epithelial Cell Proliferation through the Wnt/β-Catenin Pathway.

Glutamine (Gln) is a critical nutrient required by neonatal mammals for intestinal growth, especially for newborn piglets. However, the mechanisms underlying the role of Gln in porcine intestinal epithelium development are not fully understood. The objective of the current study was to explore the possible signaling pathway involved in the promotion of porcine intestinal epithelial cell (IPEC-J2) proliferation by Gln. The results showed that 1 mM Gln promoted IPEC-J2 cell proliferation, and tandem mass tag proteomics revealed 973 differentially expressed proteins in Gln-treated IPEC-J2 cells, 824 of which were upregulated and 149 of which were downregulated. Moreover, gene set enrichment analysis indicated that the Wnt signaling pathway is activated by Gln treatment. Western blotting analysis further confirmed that Gln activated the Wnt/β-catenin signaling pathway. In addition, Gln increased not only cytosolic β-catenin but also nuclear β-catenin protein expression. LF3 (a β-catenin/TCF4 interaction inhibitor) assay and β-catenin knockdown demonstrated that Gln-mediated promotion of Wnt/β-catenin signaling and cell proliferation were blocked. Furthermore, the inhibition of TCF4 expression suppressed Gln-induced cell proliferation. These findings further confirmed that Wnt/β-catenin signaling is involved in the promotion of IPEC-J2 cell proliferation by Gln. Collectively, these findings demonstrated that Gln positively regulated IPEC-J2 cell proliferation through the Wnt/β-catenin pathway. These data greatly enhance the current understanding of the mechanism by which Gln regulates intestinal development.

LRRK2 G2019S Promotes Colon Cancer Potentially via LRRK2-GSDMD Axis-Mediated Gut Inflammation.

Leucine-rich repeat kinase 2 (LRRK2) is a serine-threonine protein kinase belonging to the ROCO protein family. Within the kinase domain of LRRK2, a point mutation known as LRRK2 G2019S has emerged as the most prevalent variant associated with Parkinson's disease. Recent clinical studies have indicated that G2019S carriers have an elevated risk of cancers, including colon cancer. Despite this observation, the underlying mechanisms linking LRRK2 G2019S to colon cancer remain elusive. In this study, employing a colitis-associated cancer (CAC) model and LRRK2 G2019S knock-in (KI) mouse model, we demonstrate that LRRK2 G2019S promotes the pathogenesis of colon cancer, characterized by increased tumor number and size in KI mice. Furthermore, LRRK2 G2019S enhances intestinal epithelial cell proliferation and inflammation within the tumor microenvironment. Mechanistically, KI mice exhibit heightened susceptibility to DSS-induced colitis, with inhibition of LRRK2 kinase activity ameliorating colitis severity and CAC progression. Our investigation also reveals that LRRK2 G2019S promotes inflammasome activation and exacerbates gut epithelium necrosis in the colitis model. Notably, GSDMD inhibitors attenuate colitis in LRRK2 G2019S KI mice. Taken together, our findings offer experimental evidence indicating that the gain-of-kinase activity in LRRK2 promotes colorectal tumorigenesis, suggesting LRRK2 as a potential therapeutic target in colon cancer patients exhibiting hyper LRRK2 kinase activity.

Review of yeast culture concerning the interactions between gut microbiota and young ruminant animals.

Microorganisms inhabit the gastrointestinal tract of ruminants and regulate body metabolism by maintaining intestinal health. The state of gastrointestinal health is influenced not only by the macro-level factors of optimal development and the physiological structure integrity but also by the delicate equilibrium between the intestinal flora and immune status at the micro-level. Abrupt weaning in young ruminants causes incomplete development of the intestinal tract resulting in an unstable and unformed microbiota. Abrupt weaning also induced damages to the microecological homeostasis of the intestinal tract, resulting in the intestinal infections and diseases, such as diarrhea. Recently, nutritional and functional yeast culture has been researched to tackle these problems. Herein, we summarized current known interactions between intestinal microorganisms and the body of young ruminants, then we discussed the regulatory effects of using yeast culture as a feed supplement. Yeast culture is a microecological preparation that contains yeast, enriched with yeast metabolites and other nutrient-active components, including β-glucan, mannan, digestive enzymes, amino acids, minerals, vitamins, and some other unknown growth factors. It stimulates the proliferation of intestinal mucosal epithelial cells and the reproduction of intestinal microorganisms by providing special nutrient substrates to support the intestinal function. Additionally, the β-glucan and mannan effectively stimulate intestinal mucosal immunity, promote immune response, activate macrophages, and increase acid phosphatase levels, thereby improving the body's resistance to several disease. The incorporation of yeast culture into young ruminants' diet significantly alleviated the damage caused by weaning stress to the gastrointestinal tract which also acts an effective strategy to promote the balance of intestinal flora, development of intestinal tissue, and establishment of mucosal immune system. Our review provides a theoretical basis for the application of yeast culture in the diet of young ruminants.

Effects of L-Leu-L-Leu peptide on growth, proliferation, and apoptosis in broiler intestinal epithelial cells

Small peptides are nutrients and bioactive molecules that have dual regulatory effects on nutrition and physiology. They are of great significance for maintaining the intestinal health and production performance of broilers. We here cultured the primary small intestinal epithelial cells (IEC) of chicken in a medium containing L-Leu (Leu) and L-Leu-L-Leu (Leu-Leu) for 24 h. The untreated cells were considered as the control group. The growth, proliferation, and apoptosis of IEC were examined. By combining RNA-seq and label-free sequencing technology, candidate genes, proteins, and pathways related to the growth, proliferation, and apoptosis of IEC were screened. Immunofluorescence detection revealed that the purity of the isolated primary IEC was >90%. The Leu-Leu group significantly promoted IEC growth and proliferation and significantly inhibited IEC apoptosis, and the effect was better than those of the Leu and control groups. Using transcriptome sequencing, four candidate genes, CCL20, IL8L1, IL8, and IL6, were screened in the Leu group, and one candidate gene, IL8, was screened in the Leu-Leu group. Two candidate genes, IL6 and RGN, were screened in the Leu-Leu group compared with the Leu group. Non-quantitative proteomic marker sequencing results revealed that through the screening of candidate proteins and pathways, found one growth-related candidate protein PGM3 and three proliferation-related candidate proteins RPS17, RPS11, and RPL23, and two apoptosis-related candidate proteins GPX4 and PDPK1 were found in the Leu-Leu group compared with Leu group. In short, Leu-Leu could promote IEC growth and proliferation and inhibit IEC apoptosis. On combining transcriptome and proteome sequencing technologies, multiple immune- and energy-related regulatory signal pathways were found to be related to IEC growth, proliferation, and apoptosis. Three candidate genes of IL8, IL6, and RGN were identified, and five candidate proteins of RPS17, RPS11, RPL23, GPX4, and PDPK1 were involved in IEC growth, proliferation, and apoptosis. The results provide valuable data for preliminarily elucidating small peptide-mediated IEC regulation pathways, improving the small peptide nutrition theoretical system, and establishing small peptide nutrition regulation technology.

Lymphocytic colitis can be transcriptionally divided into channelopathic and inflammatory lymphocytic colitis.

The pathobiology of the non-destructive inflammatory bowel disease (IBD) lymphocytic colitis (LC) is poorly understood. We aimed to define an LC-specific mucosal transcriptome to gain insight into LC pathology, identify unique genomic signatures, and uncover potentially druggable disease pathways. We performed bulk RNA-sequencing of LC and collagenous colitis (CC) colonic mucosa from patients with active disease, and healthy controls (n=4-10 per cohort). Differential gene expression was analyzed by gene-set enrichment and deconvolution analyses to identify pathologically relevant pathways and cells, respectively, altered in LC. Key findings were validated using reverse transcription quantitative PCR and/or immunohistochemistry. Finally, we compared our data with a previous cohort of ulcerative colitis and Crohn's disease patients (n=4 per group) to distinguish non-destructive from classic IBD. LC can be subdivided into channelopathic LC, which is governed by organic acid and ion transport dysregulation, and inflammatory LC, which is driven by microbial immune responses. Inflammatory LC displays an innate and adaptive immunity that is limited compared to CC and classic IBD. Conversely, we noted a distinct induction of regulatory non-coding RNA species in inflammatory LC samples. Moreover, compared with CC, water channel and cell adhesion molecule gene expression decreased in channelopathic LC, whereas it was accentuated in inflammatory LC and associated with reduced intestinal epithelial cell proliferation. We conclude that LC can be subdivided into channelopathic LC and inflammatory LC that could be pathomechanistically distinct subtypes despite their shared clinical presentation. Inflammatory LC exhibits a dampened immune response compared to CC and classic IBDs. Our results point to regulatory micro-RNAs as a potential disease-specific feature that may be amenable to therapeutic intervention.

Phospholipase D Mediates Glutamine-Induced mTORC1 Activation to Promote Porcine Intestinal Epithelial Cell Proliferation

BackgroundThe intestinal epithelium is one of the fastest self-renewal tissues in the body, and glutamine plays a crucial role in providing carbon and nitrogen for biosynthesis. In intestinal homeostasis, phosphorylation-mediated signaling networks that cause altered cell proliferation, differentiation, and metabolic regulation have been observed. However, our understanding of how glutamine affects protein phosphorylation in the intestinal epithelium is limited, and identifying the essential signaling pathways involved in regulating intestinal epithelial cell growth is particularly challenging. ObjectivesThis study aimed to identify the essential proteins and signaling pathways involved in glutamine’s promotion of porcine intestinal epithelial cell proliferation. MethodsPhosphoproteomics was applied to describe the protein phosphorylation landscape under glutamine treatment. Kinase-substrate enrichment analysis was subjected to predict kinase activity and validated by qRT-PCR and Western blotting. Cell Counting Kit-8, glutamine rescue experiment, chloroquine treatment, and 5-fluoro-2-indolyl deschlorohalopemide inhibition assay revealed the possible underlying mechanism of glutamine promoting porcine intestinal epithelial cell proliferation. ResultsIn this study, glutamine starvation was found to significantly suppress the proliferation of intestinal epithelial cells and change phosphoproteomic profiles with 575 downregulated sites and 321 upregulated sites. Interestingly, phosphorylation of eukaryotic initiation factor 4E-binding protein 1 at position Threonine70 was decreased, which is a crucial downstream of the mechanistic target of rapamycin complex 1 (mTORC1) pathway. Further studies showed that glutamine supplementation rescued cell proliferation and mTORC1 activity, dependent on lysosomal function and phospholipase D activation. ConclusionIn conclusion, glutamine activates mTORC1 signaling dependent on phospholipase D and a functional lysosome to promote intestinal epithelial cell proliferation. This discovery provides new insight into regulating the homeostasis of the intestinal epithelium, particularly in pig production.

Protective effects of Lactobacillus on heat stress-induced intestinal injury in finisher broilers by regulating gut microbiota and stimulating epithelial development

Heat stress (HS) is a critical challenge in broilers due to the high metabolic rate and lack of sweat glands. Results from this study show that implementing a cyclic chronic HS (34 °C for 7 h/d) to finisher broilers decreased the diversity of cecal microbiota and impaired intestinal barrier, resulting in gut leak and decreased body weight (both P < 0.05). These alterations might be related to inflammatory outbursts and the retarded proliferation of intestinal epithelial cells (IECs) according to the transcriptome analysis. Considering the potential beneficial properties of Lactobacillus on intestinal development and function, the protective effects of Lactobacillus rhamnosus (L. rhamnosus) on the intestine were investigated under HS conditions in this study. Orally supplemented L. rhamnosus improved the composition of cecal microbiota and upregulated the transcription of tight junction proteins in both duodenum and jejunum, with a consequent suppression in intestinal gene expressions of pro-inflammatory cytokines and facilitation in digestive capability. Meanwhile, the jejunal villus height of the birds that received L. rhamnosus was significantly higher compared with those treated with the broth (P < 0.05). The expression abundances of genes related to IECs proliferation and differentiation were increased by L. rhamnosus, along with upregulated mRNA levels of Wnt3a and β-catenin in jejunum. In addition, L. rhamnosus attenuated enterocyte apoptosis as indicated by decreased caspase-3 and caspase-9 gene expressions. The results indicated that oral administration with L. rhamnosus mitigated HS-induced dysfunction by promoting intestinal development and epithelial maturation in broilers and that the effects of L. rhamnosus might be dependent of Wnt/β-catenin signaling.

P112 Lymphocytic colitis can be transcriptionally divided into channelopathic and inflammatory lymphocytic colitis

Abstract Background The pathobiology of the non-destructive inflammatory bowel disease (IBD) lymphocytic colitis (LC) is poorly understood. We aimed to define an LC-specific mucosal transcriptome to gain insight into LC pathology, identify unique genomic signatures, and uncover potentially druggable disease pathways. Methods We performed bulk RNA-sequencing of LC and collagenous colitis (CC) colonic mucosa from patients with active disease, and healthy controls (n=4-10 per cohort). Differential gene expression was analyzed by gene-set enrichment and deconvolution analyses to identify pathologically relevant pathways and cells, respectively, altered in LC. Key findings were validated using reverse transcription quantitative PCR and/or immunohistochemistry. Finally, we compared our data to a previous cohort of ulcerative colitis and Crohn’s disease patients (n=4 per group) to distinguish non-destructive from classic IBD. Results LC can be subdivided into channelopathic LC, which is governed by organic acid and ion transport dysregulation; and inflammatory LC, which is driven by microbial immune responses. Inflammatory LC displays an innate and adaptive immunity that is limited compared to CC and classic IBD (Fig. 1). Conversely, we noted a distinct induction of regulatory non-coding RNA species in inflammatory LC samples. Moreover, compared to CC, water channel and cell adhesion molecule gene expression decreased in channelopathic LC, whereas it was accentuated in inflammatory LC and associated with reduced intestinal epithelial cell proliferation. Conclusion We conclude that LC can be subdivided into channelopathic LC and inflammatory LC that could be pathomechanistically distinct subtypes despite their shared clinical presentation. Inflammatory LC exhibits a dampened immune response compared to CC and classic IBDs. Our results point to regulatory micro-RNAs as a potential disease-specific feature that may be amenable to therapeutic intervention.

Bile Acid Metabolic Profiles and Their Correlation with Intestinal Epithelial Cell Proliferation and Barrier Integrity in Suckling Piglets.

Bile acids (BAs) are crucial for maintaining intestinal epithelial homeostasis. However, the metabolic changes in BAs and the communication between intestinal epithelial cells (IECs) in infants after birth remain unclear. This study aims to elucidate the BA profiles of newborn piglets (NPs) and suckling piglets (SPs), and to investigate their regulatory effects on IEC proliferation and barrier integrity, as well as the potential underlying mechanisms. In this study, compared with NPs, there were significant increases in serum triglycerides, total cholesterol, glucose, and albumin levels for SPs. The total serum BA content in SPs exhibited an obvious increase. Moreover, the expression of BA synthase cytochrome P450 27A1 (CYP27A1) was increased, and the ileal BA receptor Takeda G-coupled protein receptor 5 (TGR5) and proliferation marker Ki-67 were upregulated and showed a strong positive correlation through a Spearman correlation analysis, whereas the expression of farnesoid X receptor (FXR) and occludin was markedly downregulated in SPs and also revealed a strong positive correlation. These findings indicate that the increased synthesis and metabolism of BAs may upregulate TGR5 and downregulate FXR to promote IEC proliferation and influence barrier function; this offers a fresh perspective and evidence for the role of BAs and BA receptors in regulating intestinal development in neonatal pigs.

Human intestinal organoid-derived PDGFRα + mesenchymal stroma enables proliferation and maintenance of LGR4 + epithelial stem cells

BackgroundIntestinal epithelial cells derived from human pluripotent stem cells (hPSCs) are generally maintained and cultured as organoids in vitro because they do not exhibit adhesion when cultured. However, the three-dimensional structure of organoids makes their use in regenerative medicine and drug discovery difficult. Mesenchymal stromal cells are found near intestinal stem cells in vivo and provide trophic factors to regulate stem cell maintenance and proliferation, such as BMP inhibitors, WNT, and R-spondin. In this study, we aimed to use mesenchymal stromal cells isolated from hPSC-derived intestinal organoids to establish an in vitro culture system that enables stable proliferation and maintenance of hPSC-derived intestinal epithelial cells in adhesion culture.MethodsWe established an isolation protocol for intestinal epithelial cells and mesenchymal stromal cells from hPSCs-derived intestinal organoids and a co-culture system for these cells. We then evaluated the intestinal epithelial cells and mesenchymal stromal cells' morphology, proliferative capacity, chromosomal stability, tumorigenicity, and gene expression profiles. We also evaluated the usefulness of the cells for pharmacokinetic and toxicity studies.ResultsThe proliferating intestinal epithelial cells exhibited a columnar form, microvilli and glycocalyx formation, cell polarity, and expression of drug-metabolizing enzymes and transporters. The intestinal epithelial cells also showed barrier function, transporter activity, and drug-metabolizing capacity. Notably, small intestinal epithelial stem cells cannot be cultured in adherent culture without mesenchymal stromal cells and cannot replaced by other feeder cells. Organoid-derived mesenchymal stromal cells resemble the trophocytes essential for maintaining small intestinal epithelial stem cells and play a crucial role in adherent culture.ConclusionsThe high proliferative expansion, productivity, and functionality of hPSC-derived intestinal epithelial cells may have potential applications in pharmacokinetic and toxicity studies and regenerative medicine.

PI3K/Akt signaling pathway mediates the effect of low-dose boron on barrier function, proliferation and apoptosis in rat intestinal epithelial cells

Boron is an essential trace element with roles in growth, development, and physiological functions; however, its mechanism of action is still unclear. In this study, the regulatory roles of the PI3K/Akt signaling pathway on boron-induced changes in barrier function, proliferation, and apoptosis in rat intestinal epithelial cells were evaluated. Occludin levels, the proportion of cells in the G2/M phase, cell proliferation rate, and mRNA and protein expression levels of PCNA were higher, while the proportions of cells in the G0/G1 and S phases, apoptosis rate, and caspase-3 mRNA and protein expression levels were lower in cells treated with 0.8 mmol/L boron than in control IEC-6 cells (P < 0.01 or P < 0.05). However, 40 mmol/L boron decreased ZO-1 and Occludin levels, the proportion of cells in the G2/M phase, cell proliferation rate, and mRNA and protein levels of PCNA and increased the apoptosis rate and caspase-3 mRNA expression (P < 0.01 or P < 0.05). After specifically blocking PI3K and Akt signals (using LY294002 and MK-2206 2HCL), 0.8 mmol/L boron had no effects on Occludin, PCNA level, apoptosis rates, and caspase-3 levels (P < 0.05); however, the proliferation rate and PCNA levels decreased significantly (P < 0.01 or P < 0.05). The addition of 40 mmol/L boron did not affect ZO-1 and Occludin levels and did not affect the apoptosis rate or PCNA and caspase-3 levels. These results suggested that the PI3K/Akt signaling pathway mediates the effects of low-dose boron on IEC-6 cells.

LTβR-RelB signaling in intestinal epithelial cells protects from chemotherapy-induced mucosal damage.

The intricate immune mechanisms governing mucosal healing following intestinal damage induced by cytotoxic drugs remain poorly understood. The goal of this study was to investigate the role of lymphotoxin beta receptor (LTβR) signaling in chemotherapy-induced intestinal damage. LTβR deficient mice exhibited heightened body weight loss, exacerbated intestinal pathology, increased proinflammatory cytokine expression, reduced IL-22 expression, and proliferation of intestinal epithelial cells following methotrexate (MTX) treatment. Furthermore, LTβR-/-IL-22-/- mice succumbed to MTX treatment, suggesting that LTβR- and IL-22- dependent pathways jointly promote mucosal repair. Although both LTβR ligands LIGHT and LTβ were upregulated in the intestine early after MTX treatment, LIGHT-/- mice, but not LTβ-/- mice, displayed exacerbated disease. Further, we revealed the critical role of T cells in mucosal repair as T cell-deficient mice failed to upregulate intestinal LIGHT expression and exhibited increased body weight loss and intestinal pathology. Analysis of mice with conditional inactivation of LTβR revealed that LTβR signaling in intestinal epithelial cells, but not in Lgr5+ intestinal stem cells, macrophages or dendritic cells was critical for mucosal repair. Furthermore, inactivation of the non-canonical NF-kB pathway member RelB in intestinal epithelial cells promoted MTX-induced disease. Based on these results, we propose a model wherein LIGHT produced by T cells activates LTβR-RelB signaling in intestinal epithelial cells to facilitate mucosal repair following chemotherapy treatment.

Human breast milk-derived phospholipid DOPE ameliorates intestinal injury associated with NEC by inhibiting ferroptosis.

Neonatal necrotizing enterocolitis (NEC) is a severe inflammatory bowel disease that commonly affects premature infants. Breastfeeding has been proven to be one of the most effective methods for preventing NEC. However, the specific role of lipids, the second major nutrient category in human breast milk (HBM), in intestinal development remains unclear. Our preliminary lipidomic analysis of the HBM lipidome revealed that dioleoyl phosphatidylethanolamine (DOPE) is not only abundant but also shows high solubility in lipids, endowing it with significant biological utility. Experimental results confirmed that DOPE significantly reduces the mortality of neonatal rats, ameliorates impairment of intestinal barrier function, and alleviates the expression of intestinal inflammatory factors IL-1β and IL-6. Furthermore, DOPE promotes the migration and proliferation of intestinal epithelial cells, thereby enhancing the integrity of the intestinal barrier function in vitro. The progression of NEC is linked with the onset of ferroptosis. Our cellular-level analysis of lipid peroxide and iron ion concentrations revealed that DOPE significantly reduces the indicators of ferroptosis, while also modulating the expression of pivotal ferroptosis-associated factors, including SLC7A11, GPX4, and ACSL4. Hence, this research on DOPE is expected to provide novel insights into the bioactive lipids present in HBM.

Bacillus spp. as potential probiotics: promoting piglet growth by improving intestinal health.

The application of Bacillus spp. as probiotics in the swine industry, particularly for piglet production, has garnered significant attention in recent years. This review aimed to summarized the role and mechanisms of Bacillus spp. in promoting growth and maintaining gut health in piglets. Bacillus spp. can enhance intestinal barrier function by promoting the proliferation and repair of intestinal epithelial cells and increasing mucosal barrier integrity, thereby reducing the risk of pathogenic microbial invasion. Additionally, Bacillus spp. can activate the intestinal immune system of piglets, thereby enhancing the body's resistance to diseases. Moreover, Bacillus spp. can optimize the gut microbial community structure, enhance the activity of beneficial bacteria such as Lactobacillus, and inhibit the growth of harmful bacteria such as Escherichia coli, ultimately promoting piglet growth performance and improving feed efficiency. Bacillus spp. has advantages as well as challenges as an animal probiotic, and safety evaluation should be conducted when using the newly isolated Bacillus spp. This review provides a scientific basis for the application of Bacillus spp. in modern piglet production, highlighting their potential in improving the efficiency of livestock production and animal welfare.

Luminol-conjugated cyclodextrin biological nanoparticles for the treatment of severe burn-induced intestinal barrier disruption.

The breakdown of intestinal barrier integrity occurs after severe burn injury and is responsible for the subsequent reactions of inflammation and oxidative stress. A new protective strategy for the intestinal barrier is urgently needed due to the limitations of the traditional methods. Recently, the application of nanoparticles has become one of the promising therapies for many inflammation-related diseases or oxidative damage. Herein, we developed a new anti-inflammatory and antioxidant nanoparticle named luminol-conjugated cyclodextrin (LCD) and aimed to evaluate its protective effects in severe burn-induced intestinal injury. First, LCD nanoparticles, engineered with covalent conjugation between luminol and β-cyclodextrin (β-CD), were synthesized and examined. Then a mouse burn model was successfully established before the mouse body weight, intestinal histopathological manifestation, permeability, tight junction (TJ) expression and pro-inflammatory cytokines were determined in different groups. The proliferation, apoptosis, migration and reactive oxygen species (ROS) of intestinal epithelial cells (IECs) were assessed. Intraepithelial lymphocytes (IELs) were isolated and cultured for analysis by flow cytometry. LCD nanoparticle treatment significantly relieved the symptoms of burn-induced intestinal injury in the mouse model, including body weight loss and intestinal permeability abnormalities. Moreover, LCD nanoparticles remarkably recovered the mechanical barrier of the intestine after severe burn, renewed TJ structures, promoted IEC proliferation and migration, and inhibited IEC apoptosis. Mechanistically, LCD nanoparticles dramatically alleviated pro-inflammation factors (tumor necrosis factor-α, IL-17A) and ROS accumulation, which could be highly involved in intestinal barrier disruption. Furthermore, an increase in IL-17A and the proportion of IL-17A+Vγ4+ γδ T subtype cells was also observed in vitro in LPS-treated Vγ4+ γδ T cells, but the use of LCD nanoparticles suppressed this increase. Taken together, these findings demonstrate that LCD nanoparticles have the protective ability to ameliorate intestinal barrier disruption and provide a therapeutic intervention for burn-induced intestinal injury.

Amino acid transporter SLC7A5 regulates cell proliferation and secretary cell differentiation and distribution in the mouse intestine.

The intestine is critical for not only processing nutrients but also protecting the organism from the environment. These functions are mainly carried out by the epithelium, which is constantly being self-renewed. Many genes and pathways can influence intestinal epithelial cell proliferation. Among them is mTORC1, whose activation increases cell proliferation. Here, we report the first intestinal epithelial cell (IEC)-specific knockout (ΔIEC) of an amino acid transporter capable of activating mTORC1. We show that the transporter, SLC7A5, is highly expressed in mouse intestinal crypt and Slc7a5ΔIEC reduces mTORC1 signaling. Surprisingly, adult Slc7a5ΔIEC intestinal crypts have increased cell proliferation but reduced mature Paneth cells. Goblet cells, the other major secretory cell type in the small intestine, are increased in the crypts but reduced in the villi. Analyses with scRNA-seq and electron microscopy have revealed dedifferentiation of Paneth cells in Slc7a5ΔIEC mice, leading to markedly reduced secretory granules with little effect on Paneth cell number. Thus, SLC7A5 likely regulates secretory cell differentiation to affect stem cell niche and indirectly regulate cell proliferation.

Changes of Colon in Rats with Different Ages in Response to Lipopolysaccharide.

Lipopolysaccharide (LPS) is an endotoxin that causes inflammation, and the content of LPS increases gradually during the process of aging. Whether the response of the colon to LPS stimulation will increase with age is yet unknown. The study investigated the effects of LPS stimulation on the colon of adult and aging rats. 43 healthy male SD rats were divided into 4 different groups: adult group and LPS-stimulated adult group at the age of 4 months, and aging group and LPS-stimulated aging group at the age of 22 months. Rats were stimulated by intraperitoneal injection of LPS (1mg/kg) for 24 h. The morphological changes of the colon were observed, and intestinal inflammatory response, tight junction proteins, apoptosis, and proliferation in intestinal epithelial cells were detected. A series of morphology changes occurred in the colon of adult rats after LPS stimulation, the higher inflammatory response (TLR4, NF-κB, and IL-1β), changes in the protein levels of tight junctions (ZO-1, Claudin1, and Claudin2), and increased apoptosis (Bax, Bcl2) and proliferation (PCNA) of intestinal epithelial cells. The above changes were also found in aging rats. LPS stimulation further promotes the above changes to some extent in the colon of aging rats. A series of colon changes in rats was significantly damaged during LPS stimulation and aging, and these changes were further aggravated to some extent in LPS-stimulated aging rats.