Search Results (48)

The goal of this review is to expand our understanding of how the cellular organization of the normal colonic crypt is maintained and elucidate how this intricate architecture is disrupted during tumorigenesis. Additionally, it will focus on implications for new therapeutic strategies targeting Epithelial–Mesenchymal Transition (EMT). The colonic crypt is a highly structured epithelial unit that functions in maintaining homeostasis through a complex physiological function of diverse cell types: SCs, transit-amplifying (TA) progenitors, goblet cells, absorptive colonocytes, Paneth-like cells, M cells, tuft cells, and enteroendocrine cells. These cellular subpopulations are spatially organized and regulated by multiple crucial signaling pathways, including WNT, Notch, Bone Morphogenetic Protein (BMP), and Fibroblast Growth Factor (FGF). Specifically, we discuss how these regulatory networks control the precise locations and functions of crypt cell types that are necessary to achieve cellular organization and homeostasis in the normal colon crypt. In addition, we detail how the crypt’s hierarchical structure is profoundly perturbed in colorectal cancer (CRC) development. Tumorigenesis appears to be driven by LGR5+ cancer stem cells (CSCs) and the hyperproliferation of TA cells as colonocytes undergo metabolic reprogramming. Goblet cells lose their secretory phenotype, while REG4+ Paneth-like cells foster SC niches. Tumor microenvironment is also disrupted by upregulation of M cells and by tumor-immune crosstalk that is promoted by tuft cell expansion. Moreover, the presence of enteroendocrine cells in CRC has been implicated in treatment resistance due to its contribution to tumor heterogeneity. These cellular changes are caused by the disruption of homeostasis signaling whereby: overactivation of WNT/β-catenin promotes stemness, dysregulation of Notch inhibits differentiation, suppression of BMP promotes hyperproliferation, and imbalance of FGF/WNT/BMP/NOTCH enhances cellular plasticity and invasion. Further discussion of emerging therapies targeting epithelial markers and regulatory factors, emphasizing current development in novel, precision-based approaches in CRC treatment is also included. Full article

Postbiotics, which are non-viable microbial derivatives including short-chain fatty acids (SCFAs), microbial peptides, and cell wall components, are emerging as novel therapeutic agents for Inflammatory Bowel Disease (IBD). Unlike probiotics, postbiotics offer a safer, more stable alternative while retaining potent bioactivity. IBD, encompassing Crohn’s disease and ulcerative colitis, is characterized by chronic gastrointestinal inflammation, epithelial barrier dysfunction, and immune dysregulation. Recent evidence links mitochondrial dysfunction marked by impaired energy metabolism, oxidative stress, and apoptosis with the pathogenesis and persistence of IBD. Postbiotics have shown the ability to modulate mitochondrial health through multiple mechanisms. SCFAs such as butyrate serve as primary energy substrates for colonocytes, enhancing mitochondrial respiration and promoting biogenesis. They improve mitochondrial function and boost ATP production. Moreover, postbiotics reduce oxidative damage by regulating antioxidant defenses. These antioxidant actions limit epithelial apoptosis and preserve cellular integrity. In addition, postbiotics regulate mitophagy and help maintain mitochondrial quality and reduce inflammation. Structural components such as lipoteichoic acid and peptidoglycan have been shown to interact with mitochondrial pathways and modulate inflammatory responses. Collectively, this review explores the interplay between mitochondrial dysfunction, IBD, and preventive approach using postbiotics. Understanding the connections with postbiotics could open up new avenues for therapeutic interventions aimed at mitigating IBD severity in people with IBD. Full article

Background: Glucuronide recycling in the gut and liver profoundly affects the systemic and/or local exposure of drugs and their glucuronide metabolites, impacting both clinical efficacy and toxicity. This recycling also alters drug exposure in the colon, making it critical to establish local concentration for drugs targeting colon (e.g., drugs for colon cancer and inflammatory bowel disease). Methods: In this study, a parent–metabolite middle-out physiologically based pharmacokinetic (PBPK) model was built for genistein and its glucuronide metabolite to estimate the systemic and local exposure of the glucuronide and its corresponding aglycone in rats by incorporating UDP-glucuronosyltransferase (UGT)-mediated metabolism and transporter-dependent glucuronide disposition in the liver and intestine, as well as gut microbial-mediated deglucuronidation that enables the recycling of the parent compound. Results: This parent–metabolite middle-out rat PBPK model utilized in vitro-to-in vivo extrapolated (IVIVE) metabolic and transporter clearance values based on in vitro kinetic parameters from surrogate species, the rat tissue abundance of relevant proteins, and saturable Michaelis–Menten mechanisms. Inter-system extrapolation factors (ISEFs) were used to account for transporter protein abundance differences between in vitro systems and tissues and between rats and surrogate species. Model performance was evaluated at multiple dose levels for genistein and its glucuronide. Model sensitivity analyses demonstrated the impact of key parameters on the plasma concentrations and local exposure of genistein and its glucuronide. Our model was applied to simulate the quantitative impact of glucuronide recycling on the pharmacokinetic profiles in both plasma and colonocytes. Conclusions: Our study underlines the importance of glucuronide recycling in determining local drug concentrations in the intestine and provides a preliminary modeling tool to assess the influence of transporter-mediated drug–drug interactions on glucuronide recycling and local drug exposure, which are often misrepresented by systemic plasma concentrations. Full article

Background/Objectives: Engineered nanomaterials, particularly silver nanoparticles (AgNPs), have emerged as promising tools in oncology due to their ability to enhance tumor targeting and minimize off-target effects. This study investigates the cytotoxic effects of two different types of AgNPs—citrate-coated (AgNPs-cit) and EG₆OH-coated (AgNPs-EG₆OH)—on colorectal cancer (CRC) cell lines and healthy colonocytes, aiming to assess their potential as selective therapeutic agents. Methods: AgNPs-cit and AgNPs-EG₆OH were synthesized and characterized for size and surface properties. LoVo (microsatellite instability-high) and HT-29 (microsatellite stable) CRC cell lines, along with primary colonocyte cultures from healthy mucosal tissues, were exposed to these nanoparticles. Cytotoxicity was assessed through MTT assays, while morphological changes were observed using fluorescence microscopy. Internalization of the nanoparticles was evaluated by confocal microscopy. Results: AgNPs-cit exhibited significant cytotoxicity in LoVo cells, reducing viability and inducing morphological changes indicative of programmed cell death, especially after 48 h of exposure. In contrast, AgNPs-EG₆OH showed minimal effects on LoVo cells and no significant toxicity on HT-29 cells or primary colonocytes. Confocal microscopy confirmed nanoparticle internalization, with surface functionalization influencing the distribution patterns within cells. Conclusions: This study demonstrates that surface functionalization significantly influences the cytotoxicity of AgNPs, with citrate-coated nanoparticles showing selective effects on microsatellite instability-high CRC cells. These findings underscore the potential of surface-modified nanoparticles for targeted cancer therapy and highlight the importance of tailoring nanoparticle design to optimize therapeutic efficacy while minimizing off-target effects. Full article

Short-chain fatty acids (SCFAs), mainly produced by gut microbiota through the fermentation process of dietary fibers and proteins, are crucial to human health, with butyrate, a famous four-carbon SCFA, standing out for its inevitably regulatory impact on both gut and immune functions. Within this narrative review, the vital physiological functions of SCFAs were examined, with emphasis on butyrate’s role as an energy source for colonocytes and its ability to enhance the gut barrier while exhibiting anti-inflammatory effects. Knowledge of butyrate synthesis, primarily generated by Firmicutes bacteria, can be influenced by diets with specifically high contents of resistant starches and fiber. Butyrate can inhibit histone deacetylase, modulate gene expression, influence immune functionality, and regulate tight junction integrity, supporting the idea of its role in gut barrier preservation. Butyrate possesses systemic anti-inflammatory properties, particularly, its capacity to reduce pro-inflammatory cytokines and maintain immune homeostasis, highlighting its therapeutic potential in managing dysbiosis and inflammatory diseases. Although butyrate absorption into circulation is typically minimal, its broader health implications are substantial, especially regarding obesity and type 2 diabetes through its influence on metabolic regulation and inflammation. Furthermore, this narrative review thoroughly examines butyrate’s growing recognition as a modulator of neurological health via its interaction with the gut–brain axis. Additionally, butyrate’s neuroprotective effects are mediated through activation of specific G-protein-coupled receptors, such as FFAR3 and GPR109a, and inhibition of histone deacetylases (HDACs). Research indicates that butyrate can alleviate neurological disorders, including Alzheimer’s, Parkinson’s, autism spectrum disorder, and Huntington’s disease, by reducing neuroinflammation, enhancing neurotransmitter modulation, and improving histone acetylation. This focus will help unlock its full therapeutic potential for metabolic and neurological health, rather than exclusively on its well-known benefits for gut health, as these are often interconnected. Full article

Intestinal organoids are useful for the in vitro investigation of the properties of intestinal epithelial cells and their interaction with the gut microbiome. In this study, we cultured cecal and colonic organoids from common marmosets, which are highlighted as model nonhuman primates but are susceptible to gastrointestinal diseases. The organoids established were capable of passaging and long-term culture. The results of quantitative reverse transcription PCR and immunostaining showed that the organoids differentiated into major cell types (colonocytes, goblet cells, and enteroendocrine cells) in the intestinal epithelium, enabling the in vitro analysis of these cells in marmosets. The organoids could therefore represent a useful model for the investigation of gut physiology in relation to gastrointestinal diseases and host-microbiome interactions, further expanding medical, biological, and veterinary research in the future. Full article

Cystathionine gamma-lyase (CSE) and TNF-α are now recognized as key regulators of intestinal homeostasis, inflammation, and wound healing. In colonic epithelial cells, both molecules have been shown to influence a variety of biological processes, but the specific interactions between intracellular signaling pathways regulated by CSE and TNF-α are poorly understood. In the present study, we investigated these interactions in normal colonocytes and an organoid model of the healthy human colon using CSE-specific pharmacological inhibitors and siRNA-mediated transient gene silencing in analytical and functional assays in vitro. We demonstrated that CSE and TNF-α mutually regulated each other’s functions in colonic epithelial cells. TNF-α treatment stimulated CSE activity within minutes and upregulated CSE expression after 24 h, increasing endogenous CSE-derived H₂S production. In turn, CSE activity promoted TNF-α-induced NF-ĸB and ERK1/2 activation but did not affect the p38 MAPK signaling pathway. Inhibition of CSE activity completely abolished the TNF-α-induced increase in transepithelial permeability and wound healing. Our data suggest that CSE activity may be essential for effective TNF-α-mediated intestinal injury response. Furthermore, CSE regulation of TNF-α-controlled intracellular signaling pathways could provide new therapeutic targets in diseases of the colon associated with impaired epithelial wound healing. Full article

An over-active renin-angiotensin system (RAS) is characterized by elevated angiotensin II (Ang II). While Ang II can promote metabolic and mitochondrial dysfunction in tissues, little is known about its role in the gastrointestinal system (GI). Here, we treated rat primary colonic epithelial cells with Ang II (1–5000 nM) to better define their role in the GI. We hypothesized that Ang II would negatively affect mitochondrial bioenergetics as these organelles express Ang II receptors. Ang II increased cellular ATP production but reduced the mitochondrial membrane potential (MMP) of colonocytes. However, cells maintained mitochondrial oxidative phosphorylation and glycolysis with treatment, reflecting metabolic compensation with impaired MMP. To determine whether lipid dysregulation was evident, untargeted lipidomics were conducted. A total of 1949 lipids were detected in colonocytes spanning 55 distinct (sub)classes. Ang II (1 nM) altered the abundance of some sphingosines [So(d16:1)], ceramides [Cer-AP(t18:0/24:0)], and phosphatidylcholines [OxPC(16:0_20:5(2O)], while 100 nM Ang II altered some triglycerides and phosphatidylserines [PS(19:0_22:1). Ang II did not alter the relative expression of several enzymes in lipid metabolism; however, the expression of pyruvate dehydrogenase kinase 2 (PDK2) was increased, and PDK2 can be protective against dyslipidemia. This study is the first to investigate the role of Ang II in colonic epithelial cell metabolism. Full article

The gut microbiota is a complex ecosystem of microorganisms residing in the human gastrointestinal tract, playing a crucial role in various biological processes and overall health maintenance. Dysbiosis, an imbalance in the composition and function of the gut microbiota, is linked to systemic autoimmune diseases (SAD). Short-chain fatty acids (SCFAs), especially butyrate, produced by the gut microbiota through the fermentation of dietary fibers, play a significant role in immunomodulation and maintaining intestinal homeostasis. Butyrate is essential for colonocyte energy, anti-inflammatory responses, and maintaining intestinal barrier integrity. Studies show reduced butyrate-producing bacteria in SAD patients, suggesting that increasing butyrate levels could have therapeutic benefits. Butyrate’s anti-inflammatory effects and its potential therapeutic role have been studied in rheumatoid arthritis, Sjogren’s syndrome, systemic lupus erythematosus, systemic sclerosis, and Behçet’s disease. Despite promising in vitro and animal model results, human studies are limited, and the optimal strategies for modulating dysbiosis in SADs remain elusive. This review explores the current evidence on the immunoregulatory role of butyrate and its potential therapeutic effects in SAD. Full article

Colorectal cancer (CRC) stands as a significant global health concern, ranking second in mortality and third in frequency among cancers worldwide. While only a small fraction of CRC cases can be attributed to inherited genetic mutations, the majority arise sporadically due to somatic mutations. Emerging evidence reveals gut microbiota dysbiosis to be a contributing factor, wherein polyketide synthase-positive Escherichia coli (pks+ E. coli) plays a pivotal role in CRC pathogenesis. pks+ bacteria produce colibactin, a genotoxic protein that causes deleterious effects on DNA within host colonocytes. In this review, we examine the role of the gut microbiota in colon carcinogenesis, elucidating how colibactin-producer bacteria induce DNA damage, promote genomic instability, disrupt the gut epithelial barrier, induce mucosal inflammation, modulate host immune responses, and influence cell cycle dynamics. Collectively, these actions foster a microenvironment conducive to tumor initiation and progression. Understanding the mechanisms underlying pks+ bacteria-mediated CRC development may pave the way for mass screening, early detection of tumors, and therapeutic strategies such as microbiota modulation, bacteria-targeted therapy, checkpoint inhibition of colibactin production and immunomodulatory pathways. Full article

Short chain fatty acids (SCFAs) are primarily produced in the caecum and proximal colon via the bacterial fermentation of undigested carbohydrates that have avoided digestion in the small intestine. Increasing evidence supports the critical role that SCFAs play in health and homeostasis. Microbial SCFAs, namely butyric acid, serve as a principal energy source for colonocytes, and their production is essential for gut integrity. A direct link between SCFAs and some human pathological conditions, such as inflammatory bowel disease, irritable bowel syndrome, diarrhea, and cancer, has been proposed. The direct measurement of SCFAs in feces provides a non-invasive approach to demonstrating connections between SCFAs, microbiota, and metabolic diseases to estimate their potential applicability as meaningful biomarkers of intestinal health. This study aimed to adapt a robust analytical method (liquid–liquid extraction, followed by isobutyl chloroformate derivatization and GC–MS analysis), with comparable performances to methods from the literature, and to use this tool to tackle the question of pre-analytical conditions, namely stool processing. We focused on the methodology of managing stool samples before the analysis (fresh stool or dilution in either ethanol/methanol, lyophilized stool, or RNAlater^®), as this is a significant issue to consider for standardizing results between clinical laboratories. The objective was to standardize methods for future applications as diagnostic tools. In this paper, we propose a validated GC–MS method for SCFA quantification in stool samples, including pre- and post-analytical comparison studies that could be easily used for clinical laboratory purposes. Our results show that using lyophilization as a stool-processing method would be the best method to achieve this goal. Full article

Colorectal cancer (CRC) is a leading cause of death worldwide. Conventional therapies are available with varying effectiveness. Acetate, a short-chain fatty acid produced by human intestinal bacteria, triggers mitochondria-mediated apoptosis preferentially in CRC but not in normal colonocytes, which has spurred an interest in its use for CRC prevention/therapy. We previously uncovered that acetate-induced mitochondrial-mediated apoptosis in CRC cells is significantly enhanced by the inhibition of the lysosomal protease cathepsin D (CatD), which indicates both mitochondria and the lysosome are involved in the regulation of acetate-induced apoptosis. Herein, we sought to determine whether mitochondrial function affects CatD apoptotic function. We found that enhancement of acetate-induced apoptosis by CatD inhibition depends on oligomycin A-sensitive respiration. Mechanistically, the potentiating effect is associated with an increase in cellular and mitochondrial superoxide anion accumulation and mitochondrial mass. Our results provide novel clues into the regulation of CatD function and the effect of tumor heterogeneity in the outcome of combined treatment using acetate and CatD inhibitors. Full article

The eubiotic state of the gut microbiota is primarily brought about by various probiotic species that colonize the gut. It is becoming very clear that the probiotic-metabolite mixtures in the gut luminal milieu is central in establishing cross-kingdom signalling networks to maintain gut-multi-organ axes health. Culturally, different fermented foods and beverages have been regional staples since ancient times, and are known to be enriched with probiotics. However, regional variations including the environment, the staple food source (prebiotics), and fermentation methods, among other factors, influence the fermenting probiotic species. Fermented rice water (FRW), an economical, easy to make, simple beverage is a rich source of synbiotics. Therefore, consumption of fermented rice water allows for the intake of a variety of region-specific live probiotics. The secondary metabolites (postbiotics) present in such symbiotic mixtures may also contribute toward maintaining normal intestinal cellular functions. In this study, we highlight that regional staples such as rice consumed in their fermented form may hold promise in alleviating gut-related diseases. Our results show that simple overnight fermentation of cooked edible rice enables the growth of probiotic bacterial species belonging to the Lactic Acid Bacteria group (Leuconostoc lactis, Weisella confusa, Weisella cibacria, Lactococcus lactis, lactococcus taiwanensis, Lactobacillus fermentum, Lactobacillus nagelii, and Lactobacillus delbrueckii ssp. indicus). Metabolomic analysis of the overnight fermented and over two-nights fermented rice water identified more than 200 postbiotic metabolites. Our results show that postbiotics contributing to energy metabolism, gut-multiorgan axes, and microbial paraprobiotics are enriched in the overnight (~10 h) fermented rice water as compared to the over two-nights fermented rice water. Functional analysis via gene expression studies for nutrient absorption (mct-1 and mct-2) and barrier integrity (occludin and zo-1) reveals significant upregulation of these genes upon FRW treatment of HT29 colon cells. This study is a first-of-its-kind to demonstrate the proof-of-principle that postbiotics of naturally fermented rice water positively modulates colonocyte health. Full article

Reactive sulfur species (RSS) like hydrogen sulfide (H₂S) and cysteine persulfide (Cys-SSH) emerged as key signaling molecules with diverse physiological roles in the body, depending on their concentration and the cellular environment. While it is known that H₂S and Cys-SSH are produced by both colonocytes and by the gut microbiota through sulfur metabolism, it remains unknown how these RSS affect amebiasis caused by Entamoeba histolytica, a parasitic protozoan that can be present in the human gastrointestinal tract. This study investigates H₂S and Cys-SSH’s impact on E. histolytica physiology and explores potential therapeutic implications. Exposing trophozoites to the H₂S donor, sodium sulfide (Na₂S), or to Cys-SSH led to rapid cytotoxicity. A proteomic analysis of Cys-SSH-challenged trophozoites resulted in the identification of >500 S-sulfurated proteins, which are involved in diverse cellular processes. Functional assessments revealed inhibited protein synthesis, altered cytoskeletal dynamics, and reduced motility in trophozoites treated with Cys-SSH. Notably, cysteine proteases (CPs) were significantly inhibited by S-sulfuration, affecting their bacterial biofilm degradation capacity. Immunofluorescence microscopy confirmed alterations in actin dynamics, corroborating the proteomic findings. Thus, our study reveals how RSS perturbs critical cellular functions in E. histolytica, potentially influencing its pathogenicity and interactions within the gut microbiota. Understanding these molecular mechanisms offers novel insights into amebiasis pathogenesis and unveils potential therapeutic avenues targeting RSS-mediated modifications in parasitic infections. Full article

The fermentation of dietary fibres in the human colon generates short-chain fatty acids (SCFAs) that potentially mediate the health benefits associated with high fibre intake. In the colonic lumen, SCFAs support gut health and stimulate the release of the appetite-regulating hormones glucagon-like peptide 1 (GLP-1) and peptide-YY (PYY). In addition, SCFAs act as fuel for colonocytes and serve as precursors for substrate metabolism in the liver. The SCFAs that ultimately reach the systemic circulation may influence physiological processes in organs at a distance. Yet, when consuming plant-based fermented foods containing SCFAs, the SCFAs are absorbed in the small intestine and will not reach the colon, which might affect their physiological effects. We hypothesise that, compared to colonic delivery, a larger fraction of SCFAs will reach the systemic circulation and that the stimulation of gut hormone release will be less pronounced. To test this hypothesis, we designed two randomised crossover human intervention studies in healthy participants in which SCFAs will be targeted either to the small intestine (test day 1) or colon (test day 2) using standard capsules or capsules with a colon delivery coating, respectively. Study 1 will assess the systemic bioavailability of postprandial concentrations of labelled SCFAs after oral administration of stable isotope 13C-labelled SCFAs and intravenous administration of ²H-labelled SCFAs. In study 2, postprandial concentrations of GLP-1 and PYY, glucose, and insulin will be quantified after the administration of capsules with unlabelled SCFAs. These studies will clarify the importance of the site of administration on the kinetics of SCFAs and the gut hormone release that will contribute to elucidating the role of SCFAs as health-supporting metabolites. Full article