The Intestinal Stem Cell Niche: Homeostasis and Adaptations

Engineered epithelial curvature controls Paneth cell localization in intestinal organoids

The cellular organization within organoid models is important to regulate tissue specific function, yet few engineering approaches can control or direct cellular organization. Here, a photodegradable hydrogel is used to create softened regions that direct crypt formation within intestinal organoids, where the dimensions of the photosoftened regions generate predictable and defined crypt architectures. Guided by in vivo metrics of crypt morphology, this photopatterning method is used to control the width and length of in vitro organoid crypts, which ultimately defines the curvature of the epithelium. By tracking expression of differentiated Paneth cell markers in real-time, we show that epithelial curvature directs the localization of Paneth cells within engineered crypts, providing user-directed control over organoid functionality. We anticipate that our improved control over organoid architecture and thus Paneth cell localization will lead to more consistent in vitro organoid models for both mechanistic studies and translational applications.

Abortive PDCoV infection triggers Wnt/β-catenin pathway activation, enhancing intestinal stem cell self-renewal and promoting chicken resistance

Porcine deltacoronavirus (PDCoV) is an emerging coronavirus causing economic losses to swine industries worldwide. PDCoV can infect chickens under laboratory conditions, usually with no symptoms or mild symptoms, and may cause outbreaks in backyard poultry and wildfowl, posing a potential risk of significant economic loss to the commercial poultry industry. However, the reasons for such a subdued reaction after infection are not known. Here, using chicken intestinal organoid monolayers, we found that although PDCoV infects them nearly as well as porcine intestinal organoid monolayers, infection did not result in detectable amounts of progeny virus. In ex vivo and in vivo experiments using chickens, PDCoV infection failed to initiate interferon and inflammatory responses. Additionally, infection did not result in a disrupted intestinal barrier nor a reduced number of goblet cells and mucus secretion, as in pigs. In fact, the number of goblet cells increased as did the secreted mucus, thereby providing an enhanced protective barrier. Ex vivo PDCoV infection in chicken triggered activation of the Wnt/β-catenin pathway with the upregulation of Wnt/β-catenin pathway genes (Wnt3a, Lrp5, β-catenin, and TCF4) and Wnt target genes (Lgr5, cyclin D1, and C-myc). This activation stimulates the self-renewal of intestinal stem cells (ISCs), accelerating ISC-mediated epithelial regeneration by significant up-regulation of PCNA (transiently amplifying cells), BMI1 (ISCs), and Lyz (Paneth cells). Our data demonstrate that abortive infection of PDCoV in chicken cells activates the Wnt/β-catenin pathway, which facilitates the self-renewal and proliferation of ISCs, contributing to chickens' resistance to PDCoV infection.IMPORTANCEThe intestinal epithelium is the main target of PDCoV infection and serves as a physical barrier against pathogens. Additionally, ISCs are charged with tissue repair after injury, and promoting rapid self-renewal of intestinal epithelium will help to re-establish the physical barrier and maintain intestinal health. We found that PDCoV infection in chicken intestinal organoid monolayers resulted in abortive infection and failed to produce infectious virions, disrupt the intestinal barrier, reduce the number of goblet cells and mucus secretion, and induce innate immunity, but rather increased goblet cell numbers and mucus secretion. Abortive PDCoV infection activated the Wnt/β-catenin pathway, enhancing ISC renewal and accelerating the renewal and replenishment of shed PDCoV-infected intestinal epithelial cells, thereby enhancing chicken resistance to PDCoV infection. This study provides novel insights into the mechanisms underlying the mild or asymptomatic response to PDCoV infection in chickens, which is critical for understanding the virus's potential risks to the poultry industry.

Inflammatory Microenvironment-Responsive Microsphere Vehicles Modulating Gut Microbiota and Intestinal Inflammation for Intestinal Stem Cell Niche Remodeling in Inflammatory Bowel Disease

Intestinal stem cells (ISCs) engage in proliferation to maintain a stable stem cell population and differentiate into functional epithelial subpopulations. This intricate process is upheld by various signals derived from the host and gut microbiota, establishing an ISC niche. However, during inflammatory bowel disease (IBD), this signaling niche undergoes dramatic changes, leading to impaired ISC and hindered restoration of the damaged intestinal epithelial barrier. This study introduces intestinal inflammatory microenvironment-responsive microsphere vehicles designed to remodel the ISC niche, offering an approach to treat IBD. Using an advanced emulsion technique, these microsphere vehicles specifically target colonic inflammation sites, delivering a responsive release of MXene and l-arginine. This delivery system is formulated to modulate intestinal flora and immune responses effectively. l-arginine is converted into nitric oxide to regulate the gut microbiome, while MXene serves as a nanoimmunomodulator to stabilize immune homeostasis. Our findings demonstrate that the anti-inflammatory properties of the microspheres are key to promoting epithelial repair and remodeling of the ISC niche. This study highlights the role of antioxidant microspheres as anti-inflammatory agents that indirectly support ISC function and gut regeneration.

Thymoquinone Ameliorates Gut Epithelial Injury by Suppressing the JNK Signaling Pathway Based on Its Anti-Oxidant Property

Ulcerative colitis is one of the most common sorts of inflammatory bowel disease. This study investigates the protective effects of thymoquinone against sodium dodecyl sulfate (SDS)-induced intestinal damage and elucidates the underlying mechanisms using the Drosophila melanogaster model of ulcerative colitis. We found that Drosophila fed thymoquinone from larval to adult stages were resistant to SDS injury in adulthood. Thymoquinone pretreatment significantly restored the abnormal behaviors and intestinal morphological defects in Drosophila exposed to SDS. Moreover, thymoquinone protected the intestinal barrier function by inhibiting the overactivated c-Jun N-terminal kinase (JNK) pathway in the intestine induced by SDS. Further studies indicated that thymoquinone inhibits the JNK pathway by reducing intestinal reactive oxygen species (ROS) levels. This research provides novel pathological and mechanistic insights into the potential application of thymoquinone in developing functional foods or natural medicines, highlighting its significance in treating ulcerative colitis.

Obese Adipose Tissue Extracellular Vesicles Activate Mitochondrial Fatty Acid β-oxidation to Drive Colonic Stemness

BACKGROUND & AIMS

Patients with obesity and mouse models of obesity exhibit abnormalities in intestinal epithelial cells, including enhanced stemness. Adipose tissue (AT) is the largest endocrine organ secreting cytokines, hormones, and extracellular vesicles (EVs). Here, we characterized EV protein cargo from obese and non-obese AT and demonstrate the role of obese adipose-derived EVs in enhancing colonic stemness.

METHODS

EVs were isolated from visceral AT from mice fed high-fat diet to induce obesity or control matched-diet. EV cargo was characterized by unbiased proteomics. Mouse colonoids were treated with EVs and analyzed for fatty acid β-oxidation (FAO), expression of stem marker genes, stem function, and β-catenin expression and acetylation. Mice deficient in adipocyte-specific Tsg101 expression were generated to alter adipocyte EV protein cargo, and colonic stemness was measured.

RESULTS

EVs secreted from obese visceral AT (Ob EVs) were significantly enriched with acyl-CoA dehydrogenase long chain (ACADL), an initiator enzyme of FAO. Compared with non-obese EVs, colonoids treated with Ob EVs exhibited increased exogenous ACADL protein expression, FAO, growth, persistence of stem/progenitor function, and increased β-catenin protein expression and acetylation that was abolished by FAO inhibition. Mice deficient in adipocyte-specific Tsg101 expression exhibited Ob EVs with altered protein expression profiles and were protected from obesity-induced enhanced colonic stemness.

CONCLUSIONS

The contents of Ob EVs are poised to fuel FAO and to promote obesity-induced stemness in the colon. Alteration of metabolism is a key mechanism of adipose-to-intestinal tissue communication elicited by EVs, thereby influencing basal colonic stem cell homeostasis during obesity.

Intestinal Foxl1+ cell-derived CXCL12 maintains epithelial homeostasis by modulating cellular metabolism

Several mesenchymal cell populations are known to regulate intestinal stem cell (ISC) self-renewal and differentiation. However, the influences of signaling mediators derived from mesenchymal cells other than ISC niche factors on epithelial homeostasis remain poorly understood. Here, we show that host and microbial metabolites, such as taurine and gamma-aminobutyric acid (GABA), act on PDGFRαhigh Foxl1high sub-epithelial mesenchymal cells to regulate their transcription. In addition, we found that CXC chemokine ligand 12 (CXCL12) produced from Foxl1high sub-epithelial mesenchymal cells induces epithelial cell cycle arrest through modulation of the mevalonate-cholesterol synthesis pathway, which suppresses tumor progression in ApcMin/+ mice. We identified that Foxl1high sub-epithelial cells highly express CXCL12 among colonic mesenchymal cells. Foxl1-cre; Cxcl12f/f mice showed an increased number of Ki67+ colonic epithelial cells. CXCL12-induced Ca2+ mobilization facilitated phosphorylation of AMPK in intestinal epithelial cells, which inhibits the maturation of sterol regulatory element-binding proteins (SREBPs) that are responsible for mevalonate pathway activation. Furthermore, Cxcl12 deficiency in Foxl1-expressing cells promoted tumor development in the small and large intestines of ApcMin/+ mice. Collectively, these results demonstrate that CXCL12 secreted from Foxl1high mesenchymal cells manipulates intestinal epithelial cell metabolism, which links to the prevention of tumor progression in ApcMin/+ mice.

FZD5 controls intestinal crypt homeostasis and colonic Wnt surrogate agonist response

The rapidly regenerating intestinal epithelium requires crypt intestinal stem cells (ISCs). Wnt/β-catenin signaling maintains crypt homeostasis and Lgr5+ ISCs, and WNT ligands bind Frizzled receptors (FZD1-10). Identifying specific FZD(s) essential for intestinal homeostasis has been elusive; however, bioengineered antagonists blocking Wnt binding to FZD5 and FZD8 deplete the gut epithelium in vivo, highlighting potential roles. Here, an epithelial-specific Fzd5 knockout (KO) elicited lethal pan-intestinal crypt and villus loss, whereas an Lgr5+ ISC-specific Fzd5 KO depleted Lgr5+ ISCs via premature differentiation and repressed Wnt target genes. Fzd5-null phenotypes were rescued by constitutive β-catenin activation in vivo and in both mouse and human enteroids. KO of Fzd5, not Fzd8, in enteroids ablated responsiveness to dual-specificity FZD5/FZD8-selective Wnt surrogate agonists, which ameliorated DSS-induced colitis in wild-type and Fzd8 KO mice. Overall, FZD5 is a dominant and essential regulator of crypt homeostasis, Lgr5+ ISCs, and intestinal response to Wnt surrogate agonists, with implications for therapeutic mucosal repair.

Oxidative stress caused by 3-monochloro-1,2-propanediol provokes intestinal stem cell hyperproliferation and the protective role of quercetin

Recently, the contaminant 3-monochloropropane-1,2-diol (3-MCPD) found in food and the environment has garnered significant global attention due to its detrimental health effects on animals, including reproductive toxicity, neurotoxicity, and nephrotoxicity. However, the specific impacts and mechanisms of 3-MCPD on intestinal health remain elusive. Here, we employed the adult intestine of Drosophila melanogaster, a notable invertebrate model organism, to investigate the intestinal toxicity of 3-MCPD and its underlying mechanisms. Our findings revealed that exposure to 3-MCPD led to a decrease in the number of enterocyte cells and an elevation in apoptosis levels, ultimately disrupting the intestinal epithelial barrier and its function. This disruption subsequently triggered hyperproliferation and differentiation of intestinal stem cells (ISCs). Mechanistically, 3-MCPD induced oxidative stress in the Drosophila intestine, which was likely responsible for ISC hyperproliferation and intestinal damage. Intriguingly, quercetin, a natural antioxidant derived from dietary fruits and vegetables, alleviated 3-MCPD-induced intestinal toxicity by inhibiting the JNK pathway. Our findings uncover a mechanism whereby suppression of undesirable ISC hyperproliferation, caused by 3-MCPD-induced oxidative stress, maintains intestinal homeostasis, and provide a theoretical basis for exploiting quercetin, a natural antioxidant, as a dietary antidote against the intestinal hazards posed by environmental toxicants.

miR-27a-3p regulates intestinal cell proliferation and differentiation through Wnt/β-catenin signalling

Intestinal stem cells differentiate into absorptive enterocytes, characterised by increased brush border enzymes such as intestinal alkaline phosphatase (IAP), making up the majority (95%) of the terminally differentiated cells in the villus. Loss of integrity of the intestinal epithelium plays a key role in inflammatory diseases and gastrointestinal infection. Here, we show that the intestinal microRNA (miR)-27a-3p is an important regulator of intestinal epithelial cell proliferation and enterocyte differentiation. Repression of endogenous miR-27a-3p leads to increased enterocyte differentiation and decreased intestinal epithelial cell proliferation in mouse and human small intestinal organoids. Mechanistically, miR-27a-3p regulates intestinal cell differentiation and proliferation at least in part through the regulation of retinoic acid receptor α (RXRα), a modulator of Wnt/β-catenin signalling. Repression of miR-27a-3p increases the expression of RXRα and concomitantly, decreases the expression of active β-catenin and cyclin D1. In contrast, overexpression of miR-27a-3p mimic decreases the expression of RXRα and increases the expression of active β-catenin and cyclin D1. Moreover, overexpression of the miR-27a-3p mimic results in impaired enterocyte differentiation and increases intestinal epithelial cell proliferation. These alterations were attenuated or blocked by Wnt inhibition. Our study demonstrates an miR-27a-3p/RXRα/Wnt/β-catenin pathway that is important for the maintenance of enterocyte homeostasis in the small intestine.

Glial cell line derived neurotrophic factor (GDNF) induces mucosal healing via intestinal stem cell niche activation

Mucosal healing is critical to maintain and restore intestinal homeostasis in inflammation. Previous data provide evidence that glial cell line-derived neurotrophic factor (GDNF) restores epithelial integrity by largely undefined mechanisms. Here, we assessed the role of GDNF for mucosal healing. In dextran sodium sulphate (DSS)-induced colitis in mice application of GDNF enhanced recovery as revealed by reduced disease activity index and histological inflammation scores. In biopsy-based wounding experiments GDNF application in mice improved healing of the intestinal mucosa. GDNF-induced epithelial recovery was also evident in wound assays from intestinal organoids and Caco2 cells. These observations were accompanied by an increased number of Ki67-positive cells in vivo after GDNF treatment, which were present along elongated proliferative areas within the crypts. In addition, the intestinal stem cell marker and R-spondin receptor LGR5 was significantly upregulated following GDNF treatment in all experimental models. The effects of GDNF on cell proliferation, LGR5 and Ki67 upregulation were blocked using the RET-specific inhibitor BLU-667. Downstream of RET-phosphorylation, activation of Src kinase was involved to mediate GDNF effects. GDNF promotes intestinal wound healing by promoting cell proliferation. This is mediated by RET-dependent activation of Src kinase with consecutive LGR5 upregulation, indicating activation of the stem cell niche.

Transcriptome analysis reveals significant discrepancies between two in vitro models of host-trematode interaction

Cell models emulating an in vitro parasitic infection can greatly improve our understanding of helminthiases. Nonetheless, it remains challenging to select an appropriate in vitro model to study molecular pathogenesis of infections by trematodes having a complex life cycle. Therefore, adequate models are in high demand. The epidemiologically important foodborne trematode Opisthorchis felineus parasitizes bile ducts of fish-eating mammals, including humans. The human infection leads to chronic inflammation and biliary intraepithelial neoplasia, which is considered precancerous. This study was aimed at evaluating two useful in vitro research tools based on human cholangiocytes' (H69 cells') response to the trematode: coculture with live worms or incubation with parasite-derived excretory-secretory products (ESPs). We assessed H69 cells' proliferation, migration rate, cell cycle shift, and cytokine production. We also conducted genome-wide transcriptome analysis to identify affected cascades of regulatory signaling events. We demonstrated significant discrepancies between the two in vitro models of host-parasite interactions. Although differences between the two models in cell proliferation and cell migration rate were weak, there were substantial differences in the production and release of cytokines IL-6, IL-4, and TNF. A total of 144 genes in H69 cells were found to be differentially expressed after coculture with live worms, whereas 537 genes were differentially expressed after exposure to ESPs. Transcriptomic analysis revealed only 11 common upregulated genes and six common downregulated genes. Functional enrichment analysis of the gene sets also revealed some striking differences between the in vitro models. Our data will contribute to a deeper understanding of biliary neoplasia associated with liver fluke infection. This study underscores the importance of choosing an appropriate in vitro model to accurately emulate host-parasite interactions. The data also highlight the need for further investigation into the pathogenesis of the precancerous biliary lesions associated with liver fluke infection.

Milk-derived extracellular vesicles and gut health

Milk is a nutrient-rich liquid produced by mammals, offering various health benefits due to its composition of proteins, fats, carbohydrates, vitamins, and minerals. Beyond traditional nutritional aspects, recent research has focused on extracellular vesicles (EVs) found in milk and their potential health benefits, especially for gastrointestinal (GI) health. Milk-derived EVs have been shown to influence gut microbiota, promote gut barrier integrity, support tissue repair and regeneration, modulate immune responses, and potentially aid in managing conditions like inflammatory bowel disease (IBD) and colorectal cancer. This review discusses the current understanding of milk-EVs' effects on gut health, highlighting their potential therapeutic applications and future research directions. These findings underscore the promising role of milk-derived EVs in advancing GI health and therapeutics, paving the way for innovative approaches in oral drug delivery and targeted treatments for GI disorders.

Regionalized cell and gene signatures govern esophageal epithelial homeostasis

Regionalized disease prevalence is a common feature of the gastrointestinal tract. Herein, we employed regionally resolved Smart-seq3 single-cell sequencing, generating a comprehensive cell atlas of the adult mouse esophagus. Characterizing the esophageal axis, we identify non-uniform distribution of epithelial basal cells, fibroblasts, and immune cells. In addition, we demonstrate a position-dependent, but cell subpopulation-independent, transcriptional signature, collectively generating a regionalized esophageal landscape. Combining in vivo models with organoid co-cultures, we demonstrate that proximal and distal basal progenitor cell states are functionally distinct. We find that proximal fibroblasts are more permissive for organoid growth compared with distal fibroblasts and that the immune cell profile is regionalized in two dimensions, where proximal-distal and epithelial-stromal gradients impact epithelial maintenance. Finally, we predict and verify how WNT, BMP, insulin growth factor (IGF), and neuregulin (NRG) signaling are differentially engaged along the esophageal axis. We establish a cellular and transcriptional framework for understanding esophageal regionalization, providing a functional basis for epithelial disease susceptibility.

Neurotensin receptor agonist PD149163 modulates LPS-induced enterocyte apoptosis by downregulating TNFR pathway and executioner caspase 3 in endotoxemic mice: insights from in vivo and in silico study

This study was designed to evaluate the dose-dependent efficacy of neurotensin receptor-1 (NTSR1) agonist PD149163 in the amelioration of the lipopolysaccharide (LPS)-induced apoptosis in the gastrointestinal tract (GIT) of mice. PD149163 is an analogue of NTS, a GIT tri-decapeptide with anti-inflammatory and anti-oxidative effects. Swiss-albino mice (female/8 weeks/25 ± 2.5 g) were divided into six groups: control; LPS, LPS + PD149163L, and LPS + PD149163H groups were treated with LPS (0.2 μmol/L/kgBW; 5 days), followed by exposure of PD149163 to LPS + PD149163L (10.6 μmol/L/kgBW), and LPS + PD149163H (21.2 μmol/L/kgBW) for 28 days. OnlyPD149163L (10.6 μmol/L/kgBW) and onlyPD149163H (21.2 μmol/L/kgBW) groups were maintained for 28 days. Both the LPS and PD149163 were given intraperitoneally. PD149163 treatment for 4 weeks alleviated the LPS-induced enterocyte apoptosis in a dose-dependent manner. LPS-induced excessive levels of caspase-3, tumour necrosis factor-α, and leptin (biomarkers of LPS-induced apoptosis) in plasma were decreased by PD149163H treatment. Moreover, LPS-induced gut oxidative stress was ameliorated by PD149163H supplementation, as evidenced by the decreased content of malondialdehyde, lipid-hydroperoxide and increased level of superoxide-dismutase, catalase. Furthermore, PD149163H mediated elevation of the plasma anti-apoptotic protein (B-cell leukaemia/lymphoma-2) along with the NTS level contributed to the modulation of LPS-induced enterocyte apoptosis, reflected in histopathology. In vivo results were substantiated with in silico molecular docking analysis that predicted the binding of PD149163-TLR4 complex, suggesting that PD149163 can act as a TLR4 modulator and inhibit the activation of TLR4. The role of PD149163 in ameliorating GIT apoptosis by its anti-apoptotic and antioxidative effects is suggested. Further research may provide significant insights into the therapeutic intervention of PD149163 in apoptosis-related diseases of GIT.

STAT1 regulates immune-mediated intestinal stem cell proliferation and epithelial regeneration

The role of the immune system in regulating tissue stem cells remains poorly understood, as does the relationship between immune-mediated tissue damage and regeneration. Graft vs. host disease (GVHD) occurring after allogeneic bone marrow transplantation (allo-BMT) involves immune-mediated damage to the intestinal epithelium and its stem cell compartment. To assess impacts of T-cell-driven injury on distinct epithelial constituents, we have performed single cell RNA sequencing on intestinal crypts following experimental BMT. Intestinal stem cells (ISCs) from GVHD mice have exhibited global transcriptomic changes associated with a substantial Interferon-γ response and upregulation of STAT1. To determine its role in crypt function, STAT1 has been deleted within murine intestinal epithelium. Following allo-BMT, STAT1 deficiency has resulted in reduced epithelial proliferation and impaired ISC recovery. Similarly, epithelial Interferon-γ receptor deletion has also attenuated proliferation and ISC recovery post-transplant. Investigating the mechanistic basis underlying this epithelial response, ISC STAT1 expression in GVHD has been found to correlate with upregulation of ISC c-Myc. Furthermore, activated T cells have stimulated Interferon-γ-dependent epithelial regeneration in co-cultured organoids, and Interferon-γ has directly induced STAT1-dependent c-Myc expression and ISC proliferation. These findings illustrate immunologic regulation of a core tissue stem cell program after damage and support a role for Interferon-γ as a direct contributor to epithelial regeneration.

Spatial transcriptomics reveals molecular cues underlying the site specificity of the adult mouse oral mucosa and its stem cell niches

The oral cavity is a multifunctional organ composed of structurally heterogeneous mucosal tissues that remain poorly characterized. Oral mucosal tissues are highly stratified and segmented along an epithelial-lamina propria axis. Here, we performed spatial transcriptomics (tomo-seq) on the tongue, cheeks, and palate of the adult mouse to understand the cues that maintain the oral mucosal sites. We define molecular markers of unique and shared cellular niches and differentiation programs across oral sites. Using a comparative approach, we identify fibroblast growth factor (FGF) pathway components as potential stem cell niche factors for oral epithelial stem cells. Using organoid-forming efficiency assays, we validated three FGF ligands (FGF1, FGF7, and FGF10) as site-specific niche factors in the dorsal and ventral tongue. Our dataset of the spatially resolved genes across major oral sites represents a comprehensive resource for unraveling the molecular mechanisms underlying the adult homeostasis of the oral mucosa and its stem cell niches.

Crosstalk Within the Intestinal Epithelium: Aspects of Intestinal Absorption, Homeostasis, and Immunity

Gut health is crucial in many ways, such as in improving human health in general and enhancing production in agricultural animals. To maximize the effect of a healthy gastrointestinal tract (GIT), an understanding of the regulation of intestinal functions is needed. Proper intestinal functions depend on the activity, composition, and behavior of intestinal epithelial cells (IECs). There are various types of IECs, including enterocytes, Paneth cells, enteroendocrine cells (EECs), goblet cells, tuft cells, M cells, and intestinal epithelial stem cells (IESCs), each with unique 3D structures and IEC distributions. Although the communication between IECs and other cell types, such as immune cells and neurons, has been intensively reviewed, communication between different IECs has rarely been addressed. The present paper overviews the networks among IECs that influence intestinal functions. Intestinal absorption is regulated by incretins derived from EECs that induce nutrient transporter activity in enterocytes. EECs, Paneth cells, tuft cells, and enterocytes release signals to activate Notch signaling, which modulates IESC activity and intestinal homeostasis, including proliferation and differentiation. Intestinal immunity can be altered via EECs, goblet cells, tuft cells, and cytokines derived from IECs. Finally, tools for investigating IEC communication have been discussed, including the novel 3D intestinal cell model utilizing enteroids that can be considered a powerful tool for IEC communication research. Overall, the importance of IEC communication, especially EECs and Paneth cells, which cover most intestinal functional regulating pathways, are overviewed in this paper. Such a compilation will be helpful in developing strategies for maintaining gut health.

Shenling Baizhu Decoction treats ulcerative colitis of spleen-deficiency and dampness obstruction types by targeting 'gut microbiota and galactose metabolism-bone marrow' axis

ETHNOPHARMACOLOGICAL RELEVANCE

Shenlin Baizhu Decoction (SLBZD), which comes from 'Taiping Huimin Heji Ju Fang', belongs to a classical prescription for treating spleen deficiency and dampness obstruction (SQDDS)-type ulcerative colitis (UC) in traditional Chinese medicine. However, the mechanism of SLBZD in treating UC with SQDDS remains unclear.

AIM OF THE STUDY

This study aims to investigate the mechanism of SLBZD against SQDDS-type UC of based on the "gut microbiota and metabolism - bone marrow" axis to induce endogenous bone marrow mesenchymal stem cells (BMSCs) homing.

MATERIALS AND METHODS

Ultra-performance liquid chromatography-mass spectrometry was used to analysis of SLBZD qualitatively. The efficacy of SLBZD in SQDDS-type UC was evaluated based on the following indicators: the body weight, colon length, disease activity index (DAI) score, Haemotoxylin and Eosin (H&E) pathological sections, and intestinal permeability proteins (occluding and ZO-1). 16S rRNA gene sequencing and non-target metabolomics were performed to identify gut microbiota changes and its metabolites in feces, respectively. BMSCs in each group was collected, cultured, and analyzed. Optimal passaged BMSCs were injected by tail vein into UC rats of SQDDS types. BMSCs homing to the colonic mucosal tissue was observed by immunofluorescent. Finally, the repairing effect of BMSCs homing to the colonic mucosal tissue after SLBZD treatment was analyzed by transmission electron microscopy, qRT-PCR, and immunohistochemistry.

RESULTS

SLBZD effectively improved the colonic length and the body weight, reduced DAI and H&E scores, and increased the expression of the intestinal permeability proteins, including occluding and ZO-1, to treat SQDDS-type UC. After SLBZD treatment, the α-diversity and β-diversity of the gut microbiota were improved. The differential microbiota was screened as Aeromonadaceae, Lactobacillaceae, and Clostridiaceae at the family level, and Aeromonas, Lactobacillus, Clostridium_sensu_stricto_1 at the genus level. Meanwhile, the main metabolic pathway was the galactose metabolism pathway. SLBZD treatment timely corrected the aberrant levels of β-galactose in peripheral blood and bone marrow, senescence-associate-β-galactosidase in BMSCs, and galactose kinase-2, galactose mutase, and galactosidase beta-1 in peripheral blood to further elevate the expression levels of senescence-associated (SA) proteins (p16, p53, p21, and p27) in BMSCs. The Spearman's correlation analysis demonstrated the relationship between microbiota and metabolism, and the relationship between the galactose metabolism pathway and SA proteins. After BMSCs in each group injection via the tail vein, the pharmacodynamic effects were consistent with those of SLBZD in SQDDS-type UC rats. Furthermore, BMSCs have been homing to colonic mucosal tissue. BMSCs from the SLBZD treatment group had stronger restorative effects on intestinal permeability function due to increasing protein and mRNA expressions of occludin and ZO-1, and decreasing the proteins and mRNA expressions of SDF-1 and CXCR4 in colon.

CONCLUSIONS

SLBZD alleviated the damaged structure of gut microbiota and regulated their metabolism, specifically the galactose metabolism, to treat UC of SDDOS types. SLBZD treatment promotes endogenous BMSCs homing to colonic mucosal tissue to repaire the intestinal permeability. The current exploration revealed an underlying mechanism wherein SLBZD activates endogenous BMSCs by targeting 'the gut microbiota and its metabolism-bone marrow' axis and repairs colonic mucosal damage to treat SDDOS-type UC.

Gut-Microbiota-Derived Butyric Acid Overload Contributes to Ileal Mucosal Barrier Damage in Late Phase of Chronic Unpredictable Mild Stress Mice

Intestinal mucosal barrier damage is regarded as the critical factor through which chronic unpredictable mild stress (CUMS) leads to a variety of physical and mental health problems. However, the exact mechanism by which CUMS induces intestinal mucosal barrier damage is unclear. In this study, 14, 28, and 42 d CUMS model mice were established. The indicators related to ileal mucosal barrier damage (IMBD), the composition of the ileal microbiota and its amino acid (AA) and short-chain fatty acid (SCFA) metabolic functions, and free amino acid (FAA) and SCFA levels in the ileal lumen were measured before and after each stress period. The correlations between them are analyzed to investigate how CUMS induces intestinal mucosal barrier damage in male C57BL/6 mice. With the progression of CUMS, butyric acid (BA) levels decreased (14 and 28 d) and then increased (42 d), and IMBD progressively increased. In the late CUMS stage (42 d), the degree of IMBD is most severe and positively correlated with significantly increased BA levels (p < 0.05) in the ileal lumen and negatively correlated with significantly decreased FAAs, such as aspartic, glutamic, alanine, and glycine levels (p < 0.05). In the ileal lumen, the abundance of BA-producing bacteria (Muribaculaceae, Ruminococcus, and Butyricicoccus) and the gene abundance of specific AA degradation and BA production pathways and their related enzymes are significantly increased (p < 0.05). In addition, there is a significant decrease (p < 0.05) in the abundance of core bacteria (Prevotella, Lactobacillus, Turicibacter, Blautia, and Barnesiella) that rely on these specific AAs for growth and/or are sensitive to BA. These changes, in turn, promote further colonization of BA-producing bacteria, exacerbating the over-accumulation of BA in the ileal lumen. These results were validated by ileal microbiota in vitro culture experiments. In summary, in the late CUMS stages, IMBD is related to an excessive accumulation of BA caused by dysbiosis of the ileal microbiota and its overactive AA degradation.

Mouse Small Intestinal Organoid Cultures

The intestinal epithelium is a highly dynamic and self-renewing tissue that is crucial for maintaining gut homeostasis. It can be cultured in vitro from isolated crypts to form three-dimensional (3D) intestinal organoids. These organoids have the ability to proliferate and differentiate into various epithelial cell lineages, offering a more physiologically relevant model compared to traditional two-dimensional (2D) culture systems. Mesenchymal cells, located near epithelial cells, regulate epithelial behavior through paracrine signaling and provide structural support. Building on recent advances in the biology of epithelial and mesenchymal cells, we have developed a coculture system that integrates intestinal organoids with mesenchymal cells. In this system, intestinal organoids are cultured in direct or indirect contact with mesenchymal cells, allowing for the simulation of signal exchange and interactions within the in vivo-like microenvironment. This coculture system not only preserves the 3D architecture of the organoids but also enhances their physiological relevance by introducing cellular complexity. The system is capable of long-term maintenance and is adaptable to a wide range of experimental manipulations. As such, this coculture model serves as a powerful tool for studying the interactions between the intestinal epithelium and its surrounding stroma, providing new insights into stem cell biology, tissue regeneration, and disease mechanisms. Here, we introduce the methods of mouse crypt isolation, intestinal organoid culture, and its coculture with mesenchymal cell.

Single-cell spatial mapping reveals alteration of cell type composition and tissue microenvironment during early colorectal cancer formation

Colorectal cancer (CRC) is the third leading cause of cancer mortality in the United States. Familial adenomatous polyposis (FAP) is a hereditary syndrome that raises the risk of developing CRC, with total colectomy as the only effective prevention. Even though FAP is rare (0.5% of all CRC cases), this disease model is well suited for studying the early stages of malignant transformation as patients form many polyps reflective of pre-cancer states. In order to spatially profile and analyze the pre-cancer and tumor microenvironment, we have performed single-cell multiplexed imaging for 52 samples: 12 normal mucosa,16 FAP mucosa,18 FAP polyps, 2 FAP adenocarcinoma, and 4 sporadic colorectal cancer (CRCs) using Co-detection by Indexing (CODEX) imaging platform. The data revealed significant changes in cell type composition occurring in early stage polyps and during the malignant transformation of polyps to CRC. We observe a decrease in CD4+/CD8+ T cell ratio and M1/M2 macrophage ratio along the FAP disease continuum. Advanced dysplastic polyps show a higher population of cancer associated fibroblasts (CAFs), which likely alter the pre-cancer microenvironment. Within polyps and CRCs, we observe strong nuclear expression of beta-catenin and higher number neo-angiogenesis events, unlike FAP mucosa and normal colon counterparts. We identify an increase in cancer stem cells (CSCs) within the glandular crypts of the FAP polyps and also detect Tregs, tumor associated macrophages (TAMs) and vascular endothelial cells supporting CSC survival and proliferation. We detect a potential immunosuppressive microenvironment within the tumor 'nest' of FAP adenocarcinoma samples, where tumor cells tend to segregate and remain distant from the invading immune cells. TAMs were found to infiltrate the tumor area, along with angiogenesis and tumor proliferation. CAFs were found to be enriched near the inflammatory region within polyps and CRCs and may have several roles in supporting tumor growth. Neighborhood analyses between adjacent FAP mucosa and FAP polyps show significant differences in spatial location of cells based on functionality. For example, in FAP mucosa, naive CD4+ T cells alone tend to localize near the fibroblast within the stromal compartment. However, in FAP polyp, CD4+T cells colocalize with the macrophages for T cell activation. Our data are expected to serve as a useful resource for understanding the early stages of neogenesis and the pre-cancer microenvironment, which may benefit early detection, therapeutic intervention and future prevention.

Metastasis of colon cancer requires Dickkopf-2 to generate cancer cells with Paneth cell properties

Metastasis is the leading cause of cancer-related mortality. Paneth cells provide stem cell niche factors in homeostatic conditions, but the underlying mechanisms of cancer stem cell niche development are unclear. Here, we report that Dickkopf-2 (DKK2) is essential for the generation of cancer cells with Paneth cell properties during colon cancer metastasis. Splenic injection of Dkk2 knockout (KO) cancer organoids into C57BL/6 mice resulted in a significant reduction of liver metastases. Transcriptome analysis showed reduction of Paneth cell markers such as lysozymes in KO organoids. Single-cell RNA sequencing analyses of murine metastasized colon cancer cells and patient samples identified the presence of lysozyme positive cells with Paneth cell properties including enhanced glycolysis. Further analyses of transcriptome and chromatin accessibility suggested hepatocyte nuclear factor 4 alpha (HNF4A) as a downstream target of DKK2. Chromatin immunoprecipitation followed by sequencing analysis revealed that HNF4A binds to the promoter region of Sox9, a well-known transcription factor for Paneth cell differentiation. In the liver metastatic foci, DKK2 knockout rescued HNF4A protein levels followed by reduction of lysozyme positive cancer cells. Taken together, DKK2-mediated reduction of HNF4A protein promotes the generation of lysozyme positive cancer cells with Paneth cell properties in the metastasized colon cancers.

Establishment and Characterization of Patient-Derived Intestinal Organoids from Pediatric Crohn's Disease Patients

Purpose

This study aimed to establish and characterize patient-derived intestinal organoids (PDOs) from children with Crohn's disease (CD).

Methods

To generate PDOs, endoscopic biopsy specimens were obtained from non-inflamed duodenal bulbs of normal controls and CD patients. To verify the presence of PDOs, histological staining and quantitative reverse transcription polymerase chain reaction (RT-qPCR) analyses were performed.

Results

PDOs were successfully established in normal controls (n=2) and CD patients (n=2). Hematoxylin and eosin staining of formalin-fixed, paraffin-embedded PDO sections revealed crypt and villus structures, whereas immunofluorescence staining with EpCAM and DAPI confirmed the epithelial-specific architecture of the PDOs. RT-qPCR results revealed a significant increase in Lgr5, Si, and Chga gene expression and a decrease in Olfm4 and Muc2 expression in CD patients compared to normal controls, suggesting altered stem cell activity and mucosal barrier function (p<0.05).

Conclusion

We successfully established and characterized PDOs in children with CD, providing a valuable tool for understanding the pathophysiology of the disease and evaluating potential therapeutic approaches. The differential gene expression of PDOs in CD patients might be caused by the complex interplay between epithelial adaptation and inflammation in the intestinal epithelium.

Effects of ∆-9 tetrahydrocannabinol on the small intestine altered by high fructose diet: A Histopathological study

The consumption of fructose is increasing day by day. Understanding the impact of increasing fructose consumption on the small intestine is crucial since the small intestine processes fructose into glucose. ∆9-Tetrahydrocannabinol (THC), a key cannabinoid, interacts with CB1 and CB2 receptors in the gastrointestinal tract, potentially mitigating inflammation. Therefore, this study aimed to investigate the effects of the high-fructose diet (HFD) on the jejunum of rats and the role of THC consumption in reversing these effects. Experiments were conducted on Sprague-Dawley rats, with the experimental groups as follows: control (C), HFD, THC, and HFD + THC. The HFD group received a 10% fructose solution in drinking water for 12 weeks. THC groups were administered 1.5 mg/kg/day of THC intraperitoneally for the last four weeks. Following sacrification, the jejunum was evaluated for mucus secretion capacity. IL-6, JNK, CB2 and PCNA expressions were assessed through immunohistochemical analysis and the ultrastructural alterations via transmission electron microscopy. The results showed that fructose consumption did not cause weight gain but triggered inflammation in the jejunum, disrupted the cell proliferation balance, and increased mucus secretion in rats. Conversely, THC treatment displayed suppressed inflammation and improved cell proliferation balance caused by HFD. Ultrastructural examinations showed that the zonula occludens structures deteriorated in the HFD group, along with desmosome shrinkage. Mitochondria were found to be increased due to THC application following HFD. In conclusion, the findings of this research reveal the therapeutic potential of THC in reversing HFD-related alterations and provide valuable insights for clinical application.

Valproic acid alleviates total-body irradiation-induced small intestinal mucositis in mice

PURPOSE

Gastrointestinal (GI) injury is one of the serious problems of total-body irradiation (TBI). However, no fundamental treatment for TBI and other radiation-induced GI injury has yet been established. Valproic acid (VPA) administration reduces mortality in mice subjected to total-body irradiation (TBI) with X-rays. This study aimed to evaluate the effects of VPA on GI injury induced by TBI in mice.

MATERIALS AND METHODS

Mice were subjected to TBI with X-rays to induce GI injury. Changes in survival and weight were observed after VPA administration. The small intestine was then sampled at 0, 1, 3, 7, and 10 d after irradiation for histological and immunohistological evaluation and measurement of myeloperoxidase (MPO) activity and inflammatory cytokine levels (IL-1β).

RESULTS

VPA (200 and 600 mg/kg) increased survival rate and reduced weight loss in model mice. IL-1β expression 1 d after irradiation was significantly lower in the VPA group than that in the vehicle group. Furthermore, the increase in MPO activity at 3 and 7 d after irradiation was significantly suppressed by VPA administration. Histological examination (hematoxylin and eosin staining) revealed that 600 mg/kg VPA inhibited inflammatory cell infiltration. Immunostaining for the proliferating cell nuclear antigen involved in cell proliferation showed that VPA suppressed the irradiation-induced decrease in cell proliferative capacity.

CONCLUSIONS

Treatment with VPA in mice with GI injury caused by TBI suppressed inflammatory responses in small intestinal mucosal cells. These results suggest that VPA may be a useful therapeutic agent against TBI-induced small intestinal mucositis.

Regulation of intestinal epithelial homeostasis by mesenchymal cells

The gastrointestinal tract harbors diverse microorganisms in the lumen. Epithelial cells segregate the luminal microorganisms from immune cells in the lamina propria by constructing chemical and physical barriers through the production of various factors to prevent excessive immune responses against microbes. Therefore, perturbations of epithelial integrity are linked to the development of gastrointestinal disorders. Several mesenchymal stromal cell populations, including fibroblasts, myofibroblasts, pericytes, and myocytes, contribute to the establishment and maintenance of epithelial homeostasis in the gut through regulation of the self-renewal, proliferation, and differentiation of intestinal stem cells. Recent studies have revealed alterations in the composition of intestinal mesenchymal stromal cells in patients with inflammatory bowel disease and colorectal cancer. A better understanding of the interplay between mesenchymal stromal cells and epithelial cells associated with intestinal health and diseases will facilitate identification of novel biomarkers and therapeutic targets for gastrointestinal disorders. This review summarizes the key findings obtained to date on the mechanisms by which functionally distinct mesenchymal stromal cells regulate epithelial integrity in intestinal health and diseases at different developmental stages.

Metastasis of colon cancer requires Dickkopf-2 to generate cancer cells with Paneth cell properties

Metastasis is the leading cause of cancer-related mortality. Paneth cells provide stem cell niche factors in homeostatic conditions, but the underlying mechanisms of cancer stem cell niche development are unclear. Here we report that Dickkopf-2 (DKK2) is essential for the generation of cancer cells with Paneth cell properties during colon cancer metastasis. Splenic injection of Dkk2-knockout (KO) cancer organoids into C57BL/6 mice resulted in a significant reduction of liver metastases. Transcriptome analysis showed reduction of Paneth cell markers such as lysozymes in KO organoids. Single cell RNA sequencing analyses of murine metastasized colon cancer cells and patient samples identified the presence of lysozyme positive cells with Paneth cell properties including enhanced glycolysis. Further analyses of transcriptome and chromatin accessibility suggested Hepatocyte nuclear factor 4-alpha (HNF4A) as a downstream target of DKK2. Chromatin immunoprecipitation followed by sequencing analysis revealed that HNF4A binds to the promoter region of Sox9, a well-known transcription factor for Paneth cell differentiation. In the liver metastatic foci, DKK2 knockout rescued HNF4A protein levels followed by reduction of lysozyme positive cancer cells. Taken together, DKK2-mediated reduction of HNF4A protein promotes the generation of lysozyme positive cancer cells with Paneth cell properties in the metastasized colon cancers.

CL429 enhances the renewal of intestinal stem cells by upregulating TLR2-YAP1

Intestinal stem cells (ISCs) play a crucial role in maintaining the equilibrium and regenerative potential of intestinal tissue, thereby ensuring tissue homeostasis and promoting effective tissue regeneration following injury. It has been proven that targeting Toll-like receptors (TLRs) can help prevent radiation-induced damage to the intestine. In this study, we established an intestinal injury model using IR and evaluated the effects of CL429 on ISC regeneration both in vivo and in vitro. Following radiation exposure, mice treated with CL429 showed a significant increase in survival rates (100% survival in the treated group compared to 54.54% in the control group). CL429 also showed remarkable efficacy in inhibiting radiation-induced intestinal damage and promoting ISC proliferation and regeneration. In addition, CL429 protected intestinal organoids against IR-induced injury. Mechanistically, RNA sequencing and Western blot analysis revealed the activation of the Wnt and Hippo signaling pathways by CL429. Specifically, we observed a significant upregulation of YAP1, a key transcription factor in the Hippo pathway, upon CL429 stimulation. Furthermore, knockdown of YAP1 significantly attenuated the radioprotective effect of CL429 on intestinal organoids, indicating that CL429-mediated intestinal radioprotection is dependent on YAP1. In addition, we investigated the relationship between TLR2 and YAP1 using TLR2 knockout mice, and our results showed that TLR2 knockout abolished the activation of CL429 on YAP1. Taken together, our study provides evidence supporting the role of CL429 in promoting ISC regeneration through activation of TLR2-YAP1. And further investigation of the interaction between TLRs and other signaling pathways may enhance our understanding of ISC regeneration after injury.

The intestinal stem cell as a target: A review

Human intestinal epithelium handles several events that may affect health. It is composed of villi and crypts, which contain different types of cells. Each cell type plays an essential role in intestinal functions, including absorption, defense, self-renewal, and regeneration. Intestinal stem cells (ISCs), located at the base of intestinal crypts, play an important role in intestinal homeostasis and renewal. Any disruption in intestinal homeostasis, in which ISCs alter their function, may result in tumor growth. As Wnt and Notch signaling pathways are essential for ISCs homeostasis and for maintaining self-renewal, any defects in these pathways could increase the risk of developing colorectal cancer (CRC). Lgr5+ cells have been identified as intestinal stem cells expressing a leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), which is involved in the regulation of Wnt signaling. Several studies have reported upregulated expression of LGR5 in CRC. Hence, in this review, we discuss the relationship between LGR5, Wnt signaling, and Notch signaling and the development of CRC, as well as recent therapeutic strategies targeting LGR5, cancer stem cells (CSCs), and the aforementioned signaling pathways.

Examining the potentials of stem cell therapy in reducing the burden of selected non-communicable diseases in Africa

Stem cell therapy (SCT) is a promising solution for addressing health challenges in Africa, particularly non-communicable diseases (NCDs). With their regenerative potential, stem cells have the inherent capacity to differentiate into numerous cell types for tissue repair. Despite infrastructural, ethical, and legal challenges, SCT holds immense promise for managing chronic illnesses and deep-seated tissue injuries. The rising prevalence of NCDs in Africa highlights the need for innovative strategies and treatment options. SCT offers hope in combating conditions like burns, osteoarthritis, diabetes, Alzheimer's disease, stroke, heart failure and cancer, potentially reducing the burden of NCDs on the continent. Despite SCT's opportunities in Africa, there are significant obstacles. However, published research on SCT in Africa is scarce, but recent initiatives such as the Basic School on Neural Stem Cells (NSC) express interest in developing NSC research in Africa. SCT research in African regions, notably on neurogenesis, demonstrates a concentration on studying neurological processes in indigenous settings. While progress has been made in South Africa and Nigeria, issues such as brain drain and impediments to innovation remain. Clinical trials have investigated the efficacy of stem cell treatments, emphasising both potential benefits and limitations in implementing these therapies efficiently. Financing research, developing regulatory frameworks, and resolving affordability concerns are critical steps toward realizing the potential of stem cell treatment in Africa.

Both intrinsic and microenvironmental factors contribute to the regulation of stem cell quiescence

Precise regulation of stem cell quiescence is essential for tissue development and homeostasis. Therefore, its aberrant regulation is intimately correlated with various human diseases. However, the detailed mechanisms of stem cell quiescence and its specific role in the pathogenesis of various diseases remain to be determined. Recent studies have revealed that the intrinsic and microenvironmental factors are the potential candidates responsible for the orderly switch between the dormant and activated states of stem cells. In addition, defects in signaling pathways related to internal and external factors of stem cells might contribute to the initiation and development of diseases by altering the dormancy of stem cells. In this review, we focus on the mechanisms underlying stem cell quiescence, especially the involvement of intrinsic and microenvironmental factors. In addition, we discuss the relationship between the anomalies of stem cell quiescence and related diseases, hopefully providing therapeutic insights for developing novel treatments.

Dynamics of Endothelial Cell Diversity and Plasticity in Health and Disease

Endothelial cells (ECs) are vital structural units of the cardiovascular system possessing two principal distinctive properties: heterogeneity and plasticity. Endothelial heterogeneity is defined by differences in tissue-specific endothelial phenotypes and their high predisposition to modification along the length of the vascular bed. This aspect of heterogeneity is closely associated with plasticity, the ability of ECs to adapt to environmental cues through the mobilization of genetic, molecular, and structural alterations. The specific endothelial cytoarchitectonics facilitate a quick structural cell reorganization and, furthermore, easy adaptation to the extrinsic and intrinsic environmental stimuli, known as the epigenetic landscape. ECs, as universally distributed and ubiquitous cells of the human body, play a role that extends far beyond their structural function in the cardiovascular system. They play a crucial role in terms of barrier function, cell-to-cell communication, and a myriad of physiological and pathologic processes. These include development, ontogenesis, disease initiation, and progression, as well as growth, regeneration, and repair. Despite substantial progress in the understanding of endothelial cell biology, the role of ECs in healthy conditions and pathologies remains a fascinating area of exploration. This review aims to summarize knowledge and concepts in endothelial biology. It focuses on the development and functional characteristics of endothelial cells in health and pathological conditions, with a particular emphasis on endothelial phenotypic and functional heterogeneity.

Activation of fetal-like molecular programs during regeneration in the intestine and beyond

Tissue regeneration after damage is generally thought to involve the mobilization of adult stem cells that divide and differentiate into progressively specialized progeny. However, recent studies indicate that tissue regeneration can be accompanied by reversion to a fetal-like state. During this process, cells at the injury site reactivate programs that operate during fetal development but are typically absent in adult homeostasis. Here, we summarize our current understanding of the molecular signals and epigenetic mediators that orchestrate "fetal-like reversion" during intestinal regeneration. We also explore evidence for this phenomenon in other organs and species and highlight open questions that merit future examination.

Modeling the cell biology of monogenetic intestinal epithelial disorders

Monogenetic variants are responsible for a range of congenital human diseases. Variants in genes that are important for intestinal epithelial function cause a group of disorders characterized by severe diarrhea and loss of nutrient absorption called congenital diarrheas and enteropathies (CODEs). CODE-causing genes include nutrient transporters, enzymes, structural proteins, and vesicular trafficking proteins in intestinal epithelial cells. Several severe CODE disorders result from the loss-of-function in key regulators of polarized endocytic trafficking such as the motor protein, Myosin VB (MYO5B), as well as STX3, STXBP2, and UNC45A. Investigations of the cell biology and pathophysiology following loss-of-function in these genes have led to an increased understanding of both homeostatic and pathological vesicular trafficking in intestinal epithelial cells. Modeling different CODEs through investigation of changes in patient tissues, coupled with the development of animal models and patient-derived enteroids, has provided critical insights into the enterocyte differentiation and function. Linking basic knowledge of cell biology with the phenotype of specific patient variants is a key step in developing effective treatments for rare monogenetic diseases. This knowledge can also be applied more broadly to our understanding of common epithelial disorders.

Viewing cancer as a chaotic ‘information processing system’

The effort to define life encompasses a wide range of disciplines, from biology and physics to spirituality. Traditionally, replies were restricted to specialized specialties, resulting in disjointed solutions. Cancer research has mostly concentrated on genetic and cellular factors. This essay aims to reframe the way we think about cancer by looking at it through the perspective of information processing. It investigates the cybernetic component of life, perceiving it as a unified system of information processing at all scales. Stem cell research reveals their complex heterogeneity and flexibility, which are critical for tissue repair and development. Initially thought to be harmful, chaotic gene expression is now acknowledged to provide cellular flexibility. Using chaos to improve adaptation contrasts with the unpredictability of evolution, showcasing the system's ability to learn and adapt. Creativity, disorder and chaos interact, opening up new avenues for new ideas. This viewpoint opposes the gene‐centric view of cancer and highlights the importance of understanding biological processes beyond genetic reductionism. The essay finishes by pushing for a paradigm change towards seeing cancer as an informational process rather than just a hereditary disease and encouraging a better knowledge of the information processing capabilities of cellular life.

Enterococcus-derived tyramine hijacks α2A-adrenergic receptor in intestinal stem cells to exacerbate colitis

Inflammatory bowel disease (IBD) is characterized by dysbiosis of the gut microbiota and dysfunction of intestinal stem cells (ISCs). However, the direct interactions between IBD microbial factors and ISCs are undescribed. Here, we identify α2A-adrenergic receptor (ADRA2A) as a highly expressed GPCR in ISCs. Through PRESTO-Tango screening, we demonstrate that tyramine, primarily produced by Enterococcus via tyrosine decarboxylase (tyrDC), serves as a microbial ligand for ADRA2A. Using an engineered tyrDC-deficient Enterococcus faecalis strain and intestinal epithelial cell-specific Adra2a knockout mice, we show that Enterococcus-derived tyramine suppresses ISC proliferation, thereby impairing epithelial regeneration and exacerbating DSS-induced colitis through ADRA2A. Importantly, blocking the axis with an ADRA2A antagonist, yohimbine, disrupts tyramine-mediated suppression on ISCs and alleviates colitis. Our findings highlight a microbial ligand-GPCR pair in ISCs, revealing a causal link between microbial regulation of ISCs and colitis exacerbation and yielding a targeted therapeutic approach to restore ISC function in colitis.

Environmentally relevant concentrations of benzophenones exposure disrupt intestinal homeostasis, impair the intestinal barrier, and induce inflammation in mice

The aim of this study is to investigate the adverse effects of benzophenones (BPs) on the intestinal tract of mice and the potential mechanism. F1-generation ICR mice were exposed to BPs (benzophenone-1, benzophenone-2, and benzophenone-3) by breastfeeding from birth until weaning, and by drinking water after weaning until maturity. The offspring mice were executed on postnatal day 56, then their distal colons were sampled. AB-PAS staining, HE staining, immunofluorescence, Transmission Electron Microscope, immunohistochemistry, Western Blot and RT-qPCR were used to study the effects of BPs exposure on the colonic tissues of offspring mice. The results showed that colonic microvilli appeared significantly deficient in the high-dose group, and the expression of tight junction markers Zo-1 and Occludin was significantly down-regulated and the number of goblet cells and secretions were reduced in all dose groups, and the expression of secretory cell markers MUC2 and KI67 were decreased, as well as the expression of intestinal stem cell markers Lgr5 and Bmi1, suggesting that BPs exposure caused disruption of intestinal barrier and imbalance in the composition of the intestinal stem cell pool. Besides, the expression of cellular inflammatory factors such as macrophage marker F4/80 and tumor necrosis factor TNF-α was elevated in the colonic tissues of all dose groups, and the inflammatory infiltration was observed, which means the exposure of BPs caused inflammatory effects in the intestinal tract of F1-generation mice. In addition, the contents of Notch/Wnt signaling pathway-related genes, such as Dll-4, Notch1, Hes1, Ctnnb1and Sfrp2 were significantly decreased in each high-dose group (P < 0.05), suggesting that BPs may inhibit the regulation of Notch/Wnt signaling pathway. In conclusion, exposure to BPs was able to imbalance colonic homeostasis, disrupt the intestinal barrier, and trigger inflammation in the offspring mice, which might be realized through interfering with the Notch/Wnt signaling pathway.

Claudin-7 is essential for the maintenance of colonic stem cell homoeostasis via the modulation of Wnt/Notch signalling

Intestinal stem cells (ISCs) play a crucial role in the continuous self-renewal and recovery of the intestinal epithelium. In previous studies, we have revealed that the specific absence of Claudin-7 (Cldn-7) in intestinal epithelial cells (IECs) can lead to the development of spontaneous colitis. However, the mechanisms by which Cldn-7 maintains homeostasis in the colonic epithelium remain unclear. Therefore, in the present study, we used IEC- and ISC-specific Cldn-7 knockout mice to investigate the regulatory effects of Cldn-7 on colonic Lgr5+ stem cells in the mediation of colonic epithelial injury and repair under physiological and inflammatory conditions. Notably, our findings reveal that Cldn-7 deletion disrupts the self-renewal and differentiation of colonic stem cells alongside the formation of colonic organoids in vitro. Additionally, these Cldn-7 knockout models exhibited heightened susceptibility to experimental colitis, limited epithelial repair and regeneration, and increased differentiation toward the secretory lineage. Mechanistically, we also established that Cldn-7 facilitates the proliferation, differentiation, and organoid formation of Lgr5+ stem cells through the maintenance of Wnt and Notch signalling pathways in the colonic epithelium. Overall, our study provides new insights into the maintenance of ISC function and colonic epithelial homoeostasis.

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.

Intestinal stem cells: guardians of homeostasis in health and aging amid environmental challenges

The intestinal epithelium is the first line of defense and acts as an interface between the vast microbial world within the gastrointestinal tract and the body's internal milieu. The intestinal epithelium not only facilitates nutrient absorption but also plays a key role in defending against pathogens and regulating the immune system. Central to maintaining a healthy epithelium are intestinal stem cells (ISCs), which are essential for replenishing the intestinal epithelium throughout an individual's lifespan. Recent research has unveiled the intricate interplay between ISCs and their niche, which includes various cell types, extracellular components, and signaling molecules. In this review, we delve into the most recent advances in ISC research, with a focus on the roles of ISCs in maintaining mucosal homeostasis and how ISC functionality is influenced by the niche environment. In this review, we explored the regulatory mechanisms that govern ISC behavior, emphasizing the dynamic adaptability of the intestinal epithelium in the face of various challenges. Understanding the intricate regulation of ISCs and the impact of aging and environmental factors is crucial for advancing our knowledge and developing translational approaches. Future studies should investigate the interactive effects of different risk factors on intestinal function and develop strategies for improving the regenerative capacity of the gut.

Maternal Supplementation with Ornithine Promotes Placental Angiogenesis and Improves Intestinal Development of Suckling Piglets

The blood vessels of the placenta are crucial for fetal growth. Here, lower vessel density and ornithine (Orn) content were observed in placentae for low-birth-weight fetuses versus normal-birth-weight fetuses at day 75 of gestation. Furthermore, the Orn content in placentae decreased from day 75 to 110 of gestation. To investigate the role of Orn in placental angiogenesis, 48 gilts (Bama pig) were allocated into four groups. The gilts in the control group were fed a basal diet (CON group), while those in the experimental groups were fed a basal diet supplemented with 0.05% Orn (0.05% Orn group), 0.10% Orn (0.10% Orn group), and 0.15% Orn (0.15% Orn group), respectively. The results showed that 0.15% Orn and 0.10% Orn groups exhibited increased birth weight of piglets compared with the CON group. Moreover, the 0.15% Orn group was higher than the CON group in the blood vessel densities of placenta. Mechanistically, Orn facilitated placental angiogenesis by regulating vascular endothelial growth factor-A (VEGF-A). Furthermore, maternal supplementation with 0.15% Orn during gestation increased the jejunal and ileal villi height and the concentrations of colonic propionate and butyrate in suckling piglets. Collectively, these results showed that maternal supplementation with Orn promotes placental angiogenesis and improves intestinal development of suckling piglets.

Gut-liver axis calibrates intestinal stem cell fitness

The gut and liver are recognized to mutually communicate through the biliary tract, portal vein, and systemic circulation. However, it remains unclear how this gut-liver axis regulates intestinal physiology. Through hepatectomy and transcriptomic and proteomic profiling, we identified pigment epithelium-derived factor (PEDF), a liver-derived soluble Wnt inhibitor, which restrains intestinal stem cell (ISC) hyperproliferation to maintain gut homeostasis by suppressing the Wnt/β-catenin signaling pathway. Furthermore, we found that microbial danger signals resulting from intestinal inflammation can be sensed by the liver, leading to the repression of PEDF production through peroxisome proliferator-activated receptor-α (PPARα). This repression liberates ISC proliferation to accelerate tissue repair in the gut. Additionally, treating mice with fenofibrate, a clinical PPARα agonist used for hypolipidemia, enhances colitis susceptibility due to PEDF activity. Therefore, we have identified a distinct role for PEDF in calibrating ISC expansion for intestinal homeostasis through reciprocal interactions between the gut and liver.

Research progress of the effects of bisphenol analogues on the intestine and its underlying mechanisms: A review

Bisphenol A (BPA) and its analogues have prompted rising concerns, especially in terms of human safety, due to its broad use and ubiquity throughout the ecosystem. Numerous studies reported various adverse effects of bisphenols, including developmental disorders, reproductive toxicity, cardiovascular toxicity, and so on. There is increasing evidence that bisphenols can enter the gastrointestinal tract. Consequently, it is important to investigate their effects on the intestine. Several in vivo and in vitro studies have examined the impacts of bisphenols on the intestine. Here, we summarized the literature concerning intestinal toxicity of bisphenols over the past decade and presented compelling evidence of the link between bisphenol exposure and intestinal disorders. Experiment studies revealed that even at low levels, bisphenols could promote intestinal barrier dysregulation, disrupt the composition and diversity of intestinal microbiota as well as induce an immunological response. Moreover, possible underlying mechanisms of these effects were discussed. Because of a lack of empirical data, the potential risk of bisphenol exposure in humans is still unidentified, particularly regarding intestinal disorders. Thus, we propose to conduct additional epidemiological investigations and animal experiments to elucidate the associations between bisphenol exposure and human intestinal health and reveal underlying mechanisms to develop preventative and therapeutic techniques.

Astragalus polysaccharide promotes the regeneration of intestinal stem cells through HIF-1 signalling pathway

Ionizing radiation (IR)-induced intestinal injury is usually accompanied by high lethality. Intestinal stem cells (ISCs) are critical and responsible for the regeneration of the damaged intestine. Astragalus polysaccharide (APS), one of the main active ingredients of Astragalus membranaceus (AM), has a variety of biological functions. This study was aimed to investigate the potential effects of APS on IR-induced intestine injury via promoting the regeneration of ISCs. We have established models of IR-induced intestinal injury and our results showed that APS played great radioprotective effects on the intestine. APS improved the survival rate of irradiated mice, reversed the radiation damage of intestinal tissue, increased the survival rate of intestinal crypts, the number of ISCs and the expression of intestinal tight junction-related proteins after IR. Moreover, APS promoted the cell viability while inhibited the apoptosis of MODE-K. Through organoid experiments, we found that APS promoted the regeneration of ISCs. Remarkably, the results of network pharmacology, RNA sequencing and RT-PCR assays showed that APS significantly upregulated the HIF-1 signalling pathway, and HIF-1 inhibitor destroyed the radioprotection of APS. Our findings suggested that APS promotes the regeneration of ISCs through HIF-1 signalling pathway, and it may be an effective radioprotective agent for IR-induced intestinal injury.

Synbiotic Combination between Lactobacillus paracasei VL8 and Mannan-Oligosaccharide Repairs the Intestinal Barrier in the Dextran Sulfate Sodium-Induced Colitis Model by Regulating the Intestinal Stem Cell Niche

Previously, Lactobacillus paracasei VL8, a lactobacillus strain isolated from the traditional Finnish fermented dairy product Viili, demonstrated immunomodulatory and antibacterial effects. The prebiotic mannan-oligosaccharide (MOS) further promoted its antibacterial activity and growth performance, holding promise for maintaining intestinal health. However, this has not been verified in vivo. In this study, we elucidated the process by which L. paracasei VL8 and its synbiotc combination (SYN) with MOS repair the intestinal barrier function in dextran sodium sulfate (DSS)-induced colitis mice. SYN surpasses VL8 or MOS alone in restoring goblet cells and improving the tight junction structure. Omics analysis on gut microbiota reveals SYN's ability to restore Lactobacillus spp. abundance and promote tryptophan metabolism. SYN intervention also inhibits the DSS-induced hyperactivation of the Wnt/β-catenin pathway. Tryptophan metabolites from Lactobacillus induce intestinal organoid differentiation. Co-housing experiments confirm microbiota transferability, replicating intestinal barrier repair. In conclusion, our study highlights the potential therapeutic efficacy of the synbiotic combination of Lactobacillus paracasei VL8 and MOS in restoring the damaged intestinal barrier and offers new insights into the complex crosstalk between the gut microbiota and intestinal stem cells.

Understanding bovine embryo elongation: a transcriptomic study of trophoblastic vesicles

Background: During the process of elongation, the embryo increases in size within the uterus, while the extra-embryonic tissues (EETs) develop and differentiate in preparation for implantation. As it grows, the ovoid embryo transforms into a tubular form first and then a filamentous form. This process is directed by numerous genes and pathways, the expression of which may be altered in the case of developmental irregularities such as when the conceptus is shorter than expected or when the embryo develops after splitting. In bovines, efforts to understand the molecular basis of elongation have employed trophoblastic vesicles (TVs)-short tubular EET pieces that lack an embryo-which also elongate in vivo. To date, however, we lack molecular analyses of TVs at the ovoid or filamentous stages that might shed light on the expression changes involved. Methods: Following in vivo development, we collected bovine conceptuses from the ovoid (D12) to filamentous stages (D18), sectioned them into small pieces with or without their embryonic disc (ED), and then, transferred them to a receptive bovine uterus to assess their elongation abilities. We also grew spherical blastocysts in vitro up to D8 and subjected them to the same treatment. Then, we assessed the differences in gene expression between different samples and fully elongating controls at different stages of elongation using a bovine array (10 K) and an extended qPCR array comprising 224 genes across 24 pathways. Results: In vivo, TVs elongated more or less depending on the stage at which they had been created and the time spent in utero. Their daily elongation rates differed from control EET, with the rates of TVs sometimes resembling those of earlier-stage EET. Overall, the molecular signatures of TVs followed a similar developmental trajectory as intact EET from D12-D18. However, within each stage, TVs and intact EET displayed distinct expression dynamics, some of which were shared with other short epithelial models. Conclusion: Differences between TVs and EET likely result from multiple factors, including a reduction in the length and signaling capabilities of TVs, delayed elongation from inadequate uterine signals, and modified crosstalk between the conceptus and the uterus. These findings confirm that close coordination between uterine, embryonic, and extra-embryonic tissues is required to orchestrate proper elongation and, based on the partial differentiation observed, raise questions about the presence/absence of certain developmental cues or even their asynchronies.

p53 suppresses MHC class II presentation by intestinal epithelium to protect against radiation-induced gastrointestinal syndrome

Radiation-induced gastrointestinal syndrome is a major complication and limiting factor for radiotherapy. Tumor suppressor p53 has a protective role in radiation-induced gastrointestinal toxicity. However, its underlying mechanism remains unclear. Here we report that regulating the IL12-p40/MHC class II signaling pathway is a critical mechanism by which p53 protects against radiation-induced gastrointestinal syndrome. p53 inhibits the expression of inflammatory cytokine IL12-p40, which in turn suppresses the expression of MHC class II on intestinal epithelial cells to suppress T cell activation and inflammation post-irradiation that causes intestinal stem cell damage. Anti-IL12-p40 neutralizing antibody inhibits inflammation and rescues the defects in intestinal epithelial regeneration post-irradiation in p53-deficient mice and prolongs mouse survival. These results uncover that the IL12-p40/MHC class II signaling mediates the essential role of p53 in ensuring intestinal stem cell function and proper immune reaction in response to radiation to protect mucosal epithelium, and suggest a potential therapeutic strategy to protect against radiation-induced gastrointestinal syndrome.

Host-microbiota interaction in intestinal stem cell homeostasis

Intestinal stem cells (ISCs) play a pivotal role in gut physiology by governing intestinal epithelium renewal through the precise regulation of proliferation and differentiation. The gut microbiota interacts closely with the epithelium through myriad of actions, including immune and metabolic interactions, which translate into tight connections between microbial activity and ISC function. Given the diverse functions of the gut microbiota in affecting the metabolism of macronutrients and micronutrients, dietary nutrients exert pronounced effects on host-microbiota interactions and, consequently, the ISC fate. Therefore, understanding the intricate host-microbiota interaction in regulating ISC homeostasis is imperative for improving gut health. Here, we review recent advances in understanding host-microbiota immune and metabolic interactions that shape ISC function, such as the role of pattern-recognition receptors and microbial metabolites, including lactate and indole metabolites. Additionally, the diverse regulatory effects of the microbiota on dietary nutrients, including proteins, carbohydrates, vitamins, and minerals (e.g. iron and zinc), are thoroughly explored in relation to their impact on ISCs. Thus, we highlight the multifaceted mechanisms governing host-microbiota interactions in ISC homeostasis. Insights gained from this review provide strategies for the development of dietary or microbiota-based interventions to foster gut health.

Protein arginine methyltransferase 1 is required for the maintenance of adult small intestinal and colonic epithelial cell homeostasis

The vertebrate adult intestinal epithelium has a high self-renewal rate driven by intestinal stem cells (ISCs) in the crypts, which play central roles in maintaining intestinal integrity and homeostasis. However, the underlying mechanisms remain elusive. Here we showed that protein arginine methyltransferase 1 (PRMT1), a major arginine methyltransferase that can also function as a transcription co-activator, was highly expressed in the proliferating cells of adult mouse intestinal crypts. Intestinal epithelium-specific knockout of PRMT1, which ablates PRMT1 gene starting during embryogenesis, caused distinct, region-specific effects on small intestine and colon: increasing and decreasing the goblet cell number in the small intestinal and colonic crypts, respectively, leading to elongation of the crypts in small intestine but not colon, while increasing crypt cell proliferation in both regions. We further generated a tamoxifen-inducible intestinal epithelium-specific PRMT1 knockout mouse model and found that tamoxifen-induced knockout of PRMT1 in the adult mice resulted in the same region-specific intestinal phenotypes. Thus, our studies have for the first time revealed that the epigenetic enzyme PRMT1 has distinct, region-specific roles in the maintenance of intestinal epithelial architecture and homeostasis, although PRMT1 may influence intestinal development.