Intestinal Epithelial Homeostasis Research Articles

Anti-inflammatory and glial response maintain normal colon function in trimethyltin-treated rats.

Studies on the contribution of enteric neuropathy and intestinal homeostasis to central nervous system degeneration using animal models have reported varying results. Recently, colonic myenteric plexus degeneration was observed in trimethyltin-treated rats. Further characterization of this animal model is necessary to determine its potential for investigating the relationship between the enteric nervous system and central nervous system degeneration. In this study, trimethyltin-treated rats (8mg/kg body weight, i.p.) were used to measure colonic function, structure, and possible colon abnormalities. The colonic function was assessed by measuring fecal pellet output and transit time. Hematoxylin and eosin staining and immunohistochemistry were performed to evaluate inflammatory profiles and intestinal epithelial cell homeostasis. The expression of mRNA encoding tight junction proteins was quantified with quantitative PCR to determine colon permeability. Histological examination of the colon revealed mucosal immune cell infiltration, crypt damage, and high iNOS and arginase-1 expression in the mucosal layer of trimethyltin-treated rats. At the same time, trimethyltin induced high expression of iNOS, arginase-1, and GFAP and increased cell death in the colonic myenteric plexus. The low cell proliferation and low goblet cell distribution suggested altered intestinal epithelial cell homeostasis in trimethyltin-treated rats. Trimethyltin also upregulated claudin 1 expression. However, normal colon function was preserved. In conclusion, the results show that trimethyltin induces colon inflammation and cell death in the colonic myenteric plexus, and disrupts intestinal epithelial cell homeostasis. However, the balance between anti-inflammatory and pro-inflammatory responses maintains normal colon function in trimethyltin-treated rats.

IFN-γ-dependent regulation of intestinal epithelial homeostasis by NKT cells

Intestinal homeostasis is maintained through the combined functions of epithelial and immune cells that collaborate to preserve the integrity of the intestinal barrier. However, the mechanisms by which immune cell populations regulate intestinal epithelial cell (IEC) homeostasis remain unclear. Here, we use a multi-omics approach to study the immune-epithelial crosstalk and identify CD1d-restricted natural killer T (NKT) cells as key regulators of IEC biology. We find that NKT cells are abundant in the proximal small intestine and show hallmarks of activation at steady state. Subsequently, NKT cells regulate the survival and the transcriptional and cellular composition landscapes of IECs in intestinal organoids, through interferon-γ (IFN-γ) and interleukin-4 secretion. Invivo, lack of NKT cells results in an increase in IEC turnover, while NKT cell activation leads to IFN-γ-dependent epithelial apoptosis. Our findings propose NKT cells as potent producers of cytokines that contribute to the regulation of IEC homeostasis.

Vasoactive intestinal peptide promotes secretory differentiation and mitigates radiation-induced intestinal injury

BackgroundVasoactive intestinal peptide (VIP) is a neuronal peptide with prominent distribution along the enteric nervous system. While effects of VIP on intestinal motility, mucosal vasodilation, secretion, and mucosal immune cell function are well-studied, the direct impact of VIP on intestinal epithelial cell turnover and differentiation remains less understood. Intestinal stem and progenitor cells are essential for the maintenance of intestinal homeostasis and regeneration, and their functions can be modulated by factors of the stem cell niche, including neuronal mediators. Here, we investigated the role of VIP in regulating intestinal epithelial homeostasis and regeneration following irradiation-induced injury.MethodsJejunal organoids were derived from male and female C57Bl6/J, Lgr5-EGFP-IRES-CreERT2 or Lgr5-EGFP-IRES-CreERT2/R26R-LSL-TdTomato mice and treated with VIP prior to analysis. Injury conditions were induced by exposing organoids to 6 Gy of irradiation (IR). To investigate protective effects of VIP in vivo, mice received 12 Gy of abdominal IR followed by intraperitoneal injections of VIP.ResultsWe observed that VIP promotes epithelial differentiation towards a secretory phenotype predominantly via the p38 MAPK pathway. Moreover, VIP prominently modulated epithelial proliferation as well as the number and proliferative activity of Lgr5-EGFP+ progenitor cells under homeostatic conditions. In the context of acute irradiation injury in vitro, we observed that IR injury renders Lgr5-EGFP+ progenitor cells more susceptible to VIP-induced modulations, which coincided with the strong promotion of epithelial regeneration by VIP. Finally, the observed effects translate into an in vivo model of abdominal irradiation, where VIP showed to prominently mitigate radiation-induced injury.ConclusionsVIP prominently governs intestinal homeostasis by regulating epithelial progenitor cell proliferation and differentiation and promotes intestinal regeneration following acute irradiation injury.

Human Amniotic Epithelial Stem Cells Promote Colonic Recovery in Experimental Colitis via Exosomal MiR-23a-TNFR1-NF-κB Signaling.

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, manifests as chronic intestinal inflammation with debilitating symptoms, posing a significant burden on global healthcare. Moreover, current therapies primarily targeting inflammation can lead to immunosuppression-related complications. Human amniotic epithelial stem cells (hAESCs), which exhibit low immunogenicity and ethical acceptability, have gained attention as potential therapeutics. In this study, it is demonstrated that their encapsulation in a hydrogel and administration via anal injection enhanced the colonic mucosal barrier repair in a murine colitis model induced by dextran sodium sulfate during the recovery phase. The underlying mechanism involved the release of exosomes from hAESCs enriched with microRNA-23a-3p, which post-transcriptionally reduced tumor necrosis factor receptor 1 expression, suppressing the nuclear factor-κB pathway in colonic epithelial cells, thus played a key role in inflammation. The novel approach shows potential for IBD treatment by restoring intestinal epithelial homeostasis without the immunosuppressive therapy-associated risks. Furthermore, the approach provides an alternative strategy to target the key molecular pathways involved in inflammation and promotes intestinal barrier function using hAESCs and their secreted exosomes. Overall, this study provides key insights to effectively treat IBD, addresses the unmet needs of patients, and reduces related healthcare burden.

Dual function of PHF16 in reinstating homeostasis of murine intestinal epithelium after crypt regeneration

Intestinal stem cells (ISCs) are highly vulnerable to damage, being in a constant state of proliferation. Reserve stem cells repair the intestinal epithelium following damage-induced ablation of ISCs. Here, we report that the epigenetic regulator plant homology domain (PHD) finger protein 16 (PHF16) restores homeostasis of the intestinal epithelium after initial damage-induced repair. In Phf16-/Y mice, revival stem cells (revSCs) showed defects in exiting the regenerative state, and intestinal crypt regeneration failed even though revSCs were still induced in response to tissue damage, as observed by single-cell RNA sequencing (scRNA-seq). Analysis of Phf16-/Y intestinal organoids by RNA sequencing (RNA-seq) and ATAC sequencing identified that PHF16 restores homeostasis of the intestinal epithelium by inducing retinoic acid receptor (RAR)/retinoic X receptor (RXR) target genes through HBO1-mediated histone H3K14 acetylation, while at the same time counteracting YAP/TAZ activity by ubiquitination of CDC73. Together, our findings demonstrate the importance of timely suppression of regenerative activity by PHF16 for the restoration of gut homeostasis after acute tissue injury.

Characterizing the effects of triclosan and triclocarban on the intestinal epithelial homeostasis using small intestinal organoids

Intestinal epithelium has the largest surface of human body, contributes dramatically to defense of toxicant-associated intestinal injury. Triclosan (TCS) and triclocarban (TCC), extensively employed as antibacterial agents in personal care products (PCPs) and healthcare facilities, caused serious damage to human intestine. However, the role of the intestinal epithelium in TCS/TCC-induced intestinal toxicity and its underlying toxic mechanisms remain incompletely understood. In this study, a novel 3D intestinal organoid model was utilized to investigate that exposure to TCS/TCC led to a compromised self-renewal and differentiation of intestinal stem cells (ISCs). Consequently, this disrupted intestinal epithelial homeostasis ultimately caused a reduction in nutrient absorption and deficient of epithelial defense to exogenous and endogenous pathogens stimulation. The inhibition of the Wnt signaling pathway in intestinal stem cell was contributed to the intestinal toxicity of TCS/TCC. These results were further confirmed in vivo with mice exposed to TCS/TCC. The findings of this study provide evidence that TCS/TCC possess the capacity to disturb the homeostasis of the intestinal epithelium, and emphasize the credibility of organoids as a valuable model for toxicological studies, as they could faithfully recapitulate in vivo phenomena.

Control of Intestinal Stemness and Cell Lineage by Histone Variant H2A.Z Isoforms.

The histone variant H2A.Z plays important functions in the regulation of gene expression. In mammals, it is encoded by two genes, giving rise to two highly related isoforms named H2A.Z.1 and H2A.Z.2, which can have similar or antagonistic functions depending on the promoter. Knowledge of the physiopathological consequences of such functions emerges, but how the balance between these isoforms regulates tissue homeostasis is not fully understood. Here, we investigated the relative role of H2A.Z isoforms in intestinal epithelial homeostasis. Through genome-wide analysis of H2A.Z genomic localization in differentiating Caco-2 cells, we uncovered an enrichment of H2A.Z isoforms on the bodies of genes which are induced during enterocyte differentiation, stressing the potential importance of H2A.Z isoforms dynamics in this process. Through a combination of invitro and invivo experiments, we further demonstrated the two isoforms cooperate for stem and progenitor cells proliferation, as well as for secretory lineage differentiation. However, we found that they antagonistically regulate enterocyte differentiation, with H2A.Z.1 preventing terminal differentiation and H2A.Z.2 favoring it. Altogether, these data indicate that H2A.Z isoforms are critical regulators of intestine homeostasis and may provide a paradigm of how the balance between two isoforms of the same chromatin structural protein can control physiopathological processes.

Limosilactobacillus fermentum SLAM 216-Derived Extracellular Vesicles Promote Intestinal Maturation in Mouse Organoid Models.

Probiotics, when consumed in adequate amounts, can promote the health of the host and beneficially modulate the host's immunity. Particularly during the host's early life, the gut intestine undergoes a period of epithelial maturation in which epithelial cells organize into specific crypt and villus structures. This process can be mediated by the gut microbiota. Recent studies have reported that the administration of probiotics can further promote intestinal maturation in the neonatal intestine. Therefore, in this study, we investigated the effects of extracellular vesicles derived from the Limosilactobacillus fermentum SLAM 216 strain, which is an established probiotic with known immune and anti-aging effects on intestinal epithelial maturation and homeostasis, using mouse small intestinal organoids. As per our findings, treatment with L. fermentum SLAM 216-derived LF216EV (LF216EV) has significantly increased the bud number and size of organoid buds. Furthermore, extracellular vesicle (EV) treatment upregulated the expression of maturation-related genes, including Ascl2, Ephb2, Lgr5, and Sox9. Tight junctions are known to have an important role in the intestinal immune barrier, and EV treatment has significantly increased the expression of genes associated with tight junctions, such as Claudin, Muc2, Occludin, and Zo-1, indicating that it can promote intestinal development. This was supported by RNA sequencing, which revealed the upregulation of genes associated with cAMP-mediated signaling, which is known to regulate cellular processes including cell differentiation. Additionally, organoids exposed to LF216EV exhibited upregulation of genes associated with maintaining brain memory and neurotransmission, suggesting possible future functional implications.

Gut microbiota biotransformation of drug glucuronides leading to gastrointestinal toxicity: Therapeutic potential of bacterial β-glucuronidase inhibition in mycophenolate-induced enteropathy

AimsDrug-induced enteropathy is often associated with the therapeutic use of certain glucuronidated drugs. One such drug is mycophenolic acid (MPA), a well-established immunosuppressant of which gastrointestinal adverse effects are a major concern. The role of bacterial β-glucuronidase (β-G) from the gut microbiota in MPA-induced enteropathy has recently been discovered. Bacterial β-G hydrolyzes MPAG, the glucuronide metabolite of MPA excreted in the bile, leading to the digestive accumulation of MPA that would favor in turn these adverse events. We therefore hypothesized that taming bacterial β-G activity might reduce MPA digestive exposure and prevent its toxicity. Main methodsBy using a multiscale approach, we evaluated the effect of increasing concentrations of MPA on intestinal epithelial cells (Caco-2 cell line) viability, proliferation, and migration. Then, we investigated the inhibitory properties of amoxapine, a previously described bacterial β-G inhibitor, by using molecular dynamics simulations, and evaluated its efficiency in blocking MPAG hydrolysis in an Escherichia coli-based β-G activity assay. The pharmacological effect of amoxapine was evaluated in a mouse model. Key findingsWe observed that MPA impairs intestinal epithelial cell homeostasis. Amoxapine efficiently blocks the hydrolysis of MPAG to MPA and significantly reduces digestive exposure to MPA in mice. As a result, administration of amoxapine in MPA-treated mice significantly attenuated gastrointestinal lesions. SignificanceCollectively, these results suggest that the digestive accumulation of MPA is involved in the pathophysiology of MPA-gastrointestinal adverse effects. This study provides a proof-of-concept of the therapeutic potential of bacterial β-G inhibitors in glucuronidated drug-induced enteropathy.

IFN-γ stimulates Paneth cell secretion through necroptosis mTORC1 dependent.

Immune mediators affect multiple biological functions of intestinal epithelial cells (IECs) and, like Paneth and Paneth-like cells, play an important role in intestinal epithelial homeostasis. IFN-γ a prototypical proinflammatory cytokine disrupts intestinal epithelial homeostasis. However, the mechanism underlying the process remains unknown. In this study, using in vivo and in vitro models we demonstrate that IFN-γ is spontaneously secreted in the small intestine. Furthermore, we observed that this cytokine stimulates mitochondrial activity, ROS production, and Paneth and Paneth-like cell secretion. Paneth and Paneth-like secretion downstream of IFN-γ, as identified here, is mTORC1 and necroptosis-dependent. Thus, our findings revealed that the pleiotropic function of IFN-γ also includes the regulation of Paneth cell function in the homeostatic gut.

Role of long non-coding RNA in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a group of recurrent chronic inflammatory diseases, including Crohn's disease (CD) and ulcerative colitis (UC). Although IBD has been extensively studied for decades, its cause and pathogenesis remain unclear. Existing research suggests that IBD may be the result of an interaction between genetic factors, environmental factors and the gut microbiome. IBD is closely related to non-coding RNAs (ncRNAs). NcRNAs are composed of microRNA(miRNA), long non-coding RNA(lnc RNA) and circular RNA(circ RNA). Compared with miRNA, the role of lnc RNA in IBD has been little studied. Lnc RNA is an RNA molecule that regulates gene expression and regulates a variety of molecular pathways involved in the pathbiology of IBD. Targeting IBD-associated lnc RNAs may promote personalized treatment of IBD and have therapeutic value for IBD patients. Therefore, this review summarized the effects of lnc RNA on the intestinal epithelial barrier, inflammatory response and immune homeostasis in IBD, and summarized the potential of lnc RNA as a biomarker of IBD and as a predictor of therapeutic response to IBD in the future.

Protein arginine methyltransferase 1 regulates mouse enteroendocrine cell development and homeostasis

BackgroundThe adult intestinal epithelium is a complex, self-renewing tissue composed of specialized cell types with diverse functions. Intestinal stem cells (ISCs) located at the bottom of crypts, where they divide to either self-renew, or move to the transit amplifying zone to divide and differentiate into absorptive and secretory cells as they move along the crypt-villus axis. Enteroendocrine cells (EECs), one type of secretory cells, are the most abundant hormone-producing cells in mammals and involved in the control of energy homeostasis. However, regulation of EEC development and homeostasis is still unclear or controversial. We have previously shown that protein arginine methyltransferase (PRMT) 1, a histone methyltransferase and transcription co-activator, is important for adult intestinal epithelial homeostasis.ResultsTo investigate how PRMT1 affects adult intestinal epithelial homeostasis, we performed RNA-Seq on small intestinal crypts of tamoxifen-induced intestinal epithelium-specific PRMT1 knockout and PRMT1fl/fl adult mice. We found that PRMT1fl/fl and PRMT1-deficient small intestinal crypts exhibited markedly different mRNA profiles. Surprisingly, GO terms and KEGG pathway analyses showed that the topmost significantly enriched pathways among the genes upregulated in PRMT1 knockout crypts were associated with EECs. In particular, genes encoding enteroendocrine-specific hormones and transcription factors were upregulated in PRMT1-deficient small intestine. Moreover, a marked increase in the number of EECs was found in the PRMT1 knockout small intestine. Concomitantly, Neurogenin 3-positive enteroendocrine progenitor cells was also increased in the small intestinal crypts of the knockout mice, accompanied by the upregulation of the expression levels of downstream targets of Neurogenin 3, including Neuod1, Pax4, Insm1, in PRMT1-deficient crypts.ConclusionsOur finding for the first time revealed that the epigenetic enzyme PRMT1 controls mouse enteroendocrine cell development, most likely via inhibition of Neurogenin 3-mediated commitment to EEC lineage. It further suggests a potential role of PRMT1 as a critical transcriptional cofactor in EECs specification and homeostasis to affect metabolism and metabolic diseases.

MiRNA Expression Analysis of IPEC-J2 Cells Damaged by Soybean 7S Globulin Reveals ssc-miR-221-5p as the Factor Alleviating Cell Damage.

The most significant and sensitive antigen protein that causes diarrhea in weaned pigs is soybean 7S globulin. Therefore, identifying the primary target for minimizing intestinal damage brought on by soybean 7S globulin is crucial. MicroRNA (miRNA) is closely related to intestinal epithelium's homeostasis and integrity. However, the change of miRNAs' expression and the function of miRNAs in Soybean 7S globulin injured-IPEC-J2 cells are still unclear. In this study, the miRNAs' expression profile in soybean 7S globulin-treated IPEC-J2 cells was investigated. Fifteen miRNAs were expressed differently. The differentially expressed miRNA target genes are mainly concentrated in signal release, cell connectivity, transcriptional inhibition, and Hedgehog signaling pathway. Notably, we noticed that the most significantly decreased miRNA was ssc-miR-221-5p after soybean 7S globulin treatment. Therefore, we conducted a preliminary study on the mechanisms of ssc-miR-221-5p in soybean 7S globulin-injured IPEC-J2 cells. Our research indicated that ssc-miR-221-5p may inhibit ROS production to alleviate soybean 7S globulin-induced apoptosis and inflammation in IPEC-J2 cells, thus protecting the cellular mechanical barrier, increasing cell proliferation, and improving cell viability. This study provides a theoretical basis for the prevention and control of diarrhea of weaned piglets.

Epithelial Skiv2l deletion promotes aberrant secretory cell differentiation in the small intestine

Background: Inflammatory bowel disease (IBD) remains a global concern, with millions affected and incidence increasing. The etiology of IBD is multifaceted, but gene variants in epithelial and immune cells can contribute to its onset. Trichohepatoenteric syndrome (THES) is a form of monogenic very early onset IBD (VEO-IBD) that arises due to variants in SKIV2L and TTC37, which are components of the cytoplasmic RNA exosome involved in mRNA quality control. Patients with THES experience a decreased quality of life characterized by poor growth, intractable diarrhea, and immune defects. There are limited drugs approved by the FDA for treatment of IBD in children and those that have been approved are geared towards suppressing the immune system and have side effects. Therefore, there is a need for the development of therapeutics that target epithelial regeneration and repair. Understanding how genetic variants, such as those observed in THES, are involved in epithelial function is one avenue to improved therapies. The objective of the current study is to understand how the RNA exosome contributes to intestinal epithelial homeostasis by studying deletion of SKIV2L. Preclinical studies in mice revealed that global Skiv2l deletion resulted in increased mTOR signaling, and overactivated T cells, while B cell specific deletion of Skiv2l led to impaired B cell development. Ex vivo studies from our lab revealed that colonoids from THES patients exhibit decreased organoid formation effciency (OFE), suggesting that SKIV2L may have important roles in the intestinal stem cell self-renewal. We hypothesize that SKIV2L is required for intestinal epithelial cell growth and tissue function. Methods: We generated VillinCre;Skiv2l ( Skiv2l KO) mice with Skiv2l deletion in intestinal epithelial cells. Skiv2l WT and KO mice weights were monitored weekly, starting from ~2 weeks of age. Between 4 and 6 weeks of age, intestines were harvested for immunofluorescence, flow cytometry and OFE assays. Results and conclusion: Skiv2l KO mice experienced failure to thrive, were significantly smaller, and had shorter colons and small intestines compared to their WT counterparts. Immunofluorescence and flow cytometry revealed increased secretory cells in the small intestine of Skiv2l KO compared to WT mice, with significant accumulation of goblet cells in the crypt region in KO mice. Furthermore, Skiv2l KO mice had reduced OFE. These findings suggest that SKIV2L is essential for intestinal homeostasis and that aberrant secretory cell differentiation may underlie the decreased stem cell self-renewal observed in Skiv2l KO mice and THES patients. More broadly, these studies suggest an essential role for mRNA quality control in normal intestinal homeostasis. University of Pennsylvania, Institution of Regenerative Medicine; NIH R01DK124369. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 5636: CUX1 transcriptionally regulates intestinal epithelial homeostasis

Abstract The small intestine digests and absorbs nutrients, a role made possible by specialized secretory and absorptive cells that constantly replenish from the intestinal stem cell niche. Disruption in intestinal epithelium homeostasis has been linked to pathologies including inflammatory bowel disease (IBD) and cancer. However, the processes regulating differentiation in healthy and disease setting are incompletely understood. CUX1 is a highly conserved homeodomain-containing transcription factor that is expressed in small intestinal crypts and has been previously shown to be essential in mice and Drosophila. CUX1 is upregulated upon inflammatory stress conditions, including intestinal damage and in IBD. In addition, CUX1 is predicted to be protective against IBD from genome-wide association studies. The aim of the current work is to determine the mechanistic role of CUX1 in secretory intestinal cells differentiation and epithelial homeostasis. To this end, we have generated transgenic mouse models that modulate CUX1 levels in an inducible manner. Mice with near-null CUX1 levels exhibit rapid weight loss requiring euthanasia while mice with ~50% residual CUX1 halt normal weight gain. Histologic examination of tissues from mice with CUX1 knock-down reveals a lack of mature secretory cells, including goblet and Paneth cells, the latter playing a supportive role to intestinal stem cells. Moreover, mouse intestinal tissues from our knock-down models demonstrated decreased proliferation with increased apoptosis. In transcriptome profiling, we observed downregulation of proliferation, intestinal stem cell, and digestive system developmental gene signatures and decreased levels of key secretory cell regulators, pointing towards a role for CUX1 in stem cell maintenance and differentiation. Indeed, reducing CUX1 levels decreased β-catenin protein levels, while Wnt/β-catenin signaling is required for the organization of the crypt-villus axis. Finally, CUX1 knock-down compromises the ability to form budding organoids, demonstrating the cell intrinsic role for CUX1 in stem cell differentiation. In ongoing studies, we are identifying CUX1 genome-wide binding targets and the epigenetic impact of CUX1 in intestinal epithelium cells. Our findings indicate that CUX1 is a critical regulator of intestinal epithelium homeostasis that has a role in differentiation and potential role in injury-induced de-differentiation in healthy as well as IBD patients. We propose that CUX1 regulates stem cell maintenance and crypt composition by regulating Wnt/β-catenin signaling and inducing fetal-like transcriptomic repair program shown to be coopted by colon cancers. Resolving an intricate network of transcriptional regulation of differentiation in the intestinal crypt holds the potential to successfully target inflammation-related damage in human intestines. Citation Format: Katarzyna Zawieracz, Ningfei An, Megan McNerney. CUX1 transcriptionally regulates intestinal epithelial homeostasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5636.

Probiotic Consortia Protect the Intestine Against Radiation Injury by Improving Intestinal Epithelial Homeostasis

PurposeRadiation-induced intestinal injuries (RIII) commonly occur during abdomin-pelvic cancer radiotherapy; however, no effective prophylactic or therapeutic agents are available to manage RIII currently. This study aimed to clarify the potential of probiotic consortium supplementation in alleviating RIII. Materials and MethodsMale C57BL/6J mice were orally administered a probiotic mixture comprising Bifidobacterium longum BL21, Lactobacillus paracasei LC86, and Lactobacillus plantarum Lp90 for 30 days before exposure to 13 Gy of whole abdominal irradiation (WAI). The survival rates, clinical scores, and histological changes in the intestines of mice were assessed. The impacts of probiotic consortium treatment on intestinal stem cells (ISCs) proliferation, differentiation, and epithelial barrier function, oxidative stress, and inflammatory cytokines were evaluated. A comprehensive examination of the gut microbiota composition was conducted through 16S rRNA sequencing, while changes in metabolites were identified using liquid chromatography-mass spectrometry. ResultsThe probiotic consortium alleviated RIII, as reflected by increased survival rates, improved clinical scores, and mitigated mucosal injury. The probiotic consortium treatment exhibited enhanced therapeutic effects at the histological level when compared to individual probiotic strains, although there was no corresponding improvement in survival rates and colon length. Moreover, probiotic consortium stimulated ISCs proliferation and differentiation, enhanced the integrity of the intestinal epithelial barrier, and regulated redox imbalance and inflammatory responses in irradiated mice. Notably, the treatment induced a restructuring of gut microbiota composition, particularly enriching short-chain fatty acid-producing bacteria. Metabolomic analysis revealed distinctive metabolic changes associated with probiotic consortium, including elevated levels of anti-inflammatory and anti-radiation metabolites. ConclusionsThe probiotic consortium attenuated RIII by modulating the gut microbiota and metabolites, improving inflammatory symptoms, and regulating oxidative stress. These findings provide new insights into the maintenance of intestinal health with the probiotic consortium supplementation and will facilitate the development of probiotic-based therapeutic strategies for RIII in clinical practice.

Endoplasmic reticulum stress: A possible connection between intestinal inflammation and neurodegenerative disorders.

Different studies have shown the key role of endoplasmic reticulum (ER) stress in autoimmune and chronic inflammatory disorders, as well as in neurodegenerative diseases. ER stress leads to the formation of misfolded proteins which affect the secretion of different cell types that are crucial for the intestinal homeostasis. In this review, we discuss the role of ER stress and its involvement in the development of inflammatory bowel diseases, chronic conditions that can cause severe damage of the gastrointestinal tract, focusing on the alteration of Paneth cells and goblet cells (the principal secretory phenotypes of the intestinal epithelial cells). ER stress is also discussed in the context of neurodegenerative diseases, in which protein misfolding represents the signature mechanism. ER stress in the bowel and consequent accumulation of misfolded proteins might represent a bridge between bowel inflammation and neurodegeneration along the gut-to-brain axis, affecting intestinal epithelial homeostasis and the equilibrium of the commensal microbiota. Targeting intestinal ER stress could foster future studies for designing new biomarkers and new therapeutic approaches for neurodegenerative disorders.

Vanillic acid restores homeostasis of intestinal epithelium in colitis through inhibiting CA9/STIM1-mediated ferroptosis

The damage of integrated epithelial epithelium is a key pathogenic factor and closely associated with the recurrence of ulcerative colitis (UC). Here, we reported that vanillic acid (VA) exerted potent therapeutic effects on DSS-induced colitis by restoring intestinal epithelium homeostasis via the inhibition of ferroptosis. By the CETSA assay and DARTS assay, we identified carbonic anhydrase IX (CAIX, CA9) as the direct target of VA. The binding of VA to CA9 causes insulin-induced gene-2 (INSIG2) to interact with stromal interaction molecule 1 (STIM1), rather than SREBP cleavage-activating protein (SCAP), leading to the translocation of SCAP-SREBP1 from the endoplasmic reticulum (ER) to the Golgi apparatus for cleavage into mature SREBP1. The activation of SREBP1 induced by VA then significantly facilitated the transcription of stearoyl-CoA desaturase 1 (SCD1) to exert an inhibitory effect on ferroptosis. By inhibiting the excessive death of intestinal epithelial cells caused by ferroptosis, VA effectively preserved the integrity of intestinal barrier and prevented the progression of unresolved inflammation. In conclusion, our study demonstrated that VA could alleviate colitis by restoring intestinal epithelium homeostasis through CA9/STIM1-mediated inhibition of ferroptosis, providing a promising therapeutic candidate for UC.

Fosfomycin mitigated apoptosis while increased mucin secretion in swine intestinal explants challenged by Lawsonia intracellularis

Lesions induced by the obligate intracellular bacterium Lawsonia intracellularis, the etiological agent of porcine proliferative enteropathy, are characterized by crypt hyperplasia in the intestinal epithelium with minimal inflammatory infiltration. An increased population of immature enterocytes at the expense of reduced goblet cells suggests that dysregulated apoptosis may be crucial in the pathogenesis of L. intracellularis.Fosfomycin, a widely employed antibiotic in swine production, has also exhibited non-microbicidal effects, encompassing immunomodulation, augmentation of phagocytosis, and the promotion of cell survival. In this study, we assessed the immunomodulatory impact of fosfomycin on intestinal epithelial homeostasis using porcine intestinal explants challenged with L. intracellularis.Our findings reveal that L. intracellularis elicited significant nuclear alterations, increased apoptotic indices, and prompted extensive mucin secretion in the intestinal explants. When fosfomycin was added to L. intracellularis-challenged intestinal explants, it mitigated the degree of apoptosis but also induced an inflammatory response. Consequently, treatment with fosfomycin in the context of L. intracellularis challenge appears to initiate an early mucosal response, maintaining cell viability, preserving the mucin barrier, and fostering inflammatory recruitment.

The loss of antioxidant activities impairs intestinal epithelium homeostasis by altering lipid metabolism

Reactive oxygens species (ROS) are common byproducts of metabolic reactions and could be at the origin of many diseases of the elderly. Here we investigated the role of ROS in the renewal of the intestinal epithelium in mice lacking catalase (CAT) and/or nicotinamide nucleotide transhydrogenase (NNT) activities. Cat−/− mice have delayed intestinal epithelium renewal and were prone to develop necrotizing enterocolitis upon starvation. Interestingly, crypts lacking CAT showed fewer intestinal stem cells (ISC) and lower stem cell activity than wild-type. In contrast, crypts lacking NNT showed a similar number of ISCs as wild-type but increased stem cell activity, which was also impaired by the loss of CAT. No alteration in the number of Paneth cells (PCs) was observed in crypts of either Cat−/− or Nnt−/− mice, but they showed an evident decline in the amount of lysozyme. Cat deficiency caused fat accumulation in crypts, and a fall in the remarkable high amount of adipose triglyceride lipase (ATGL) in PCs. Notably, the low levels of ATGL in the intestine of Cat −/− mice increased after a treatment with the antioxidant N-acetyl-L-cysteine. Supporting a role of ATGL in the regulation of ISC activity, its inhibition halt intestinal organoid development. These data suggest that the reduction in the renewal capacity of intestine originates from fatty acid metabolic alterations caused by peroxisomal ROS.