Cellular and Molecular Gastroenterology and Hepatology最新文献

Post-transcriptional gene regulation-particularly through RNA modifications-plays an essential but understudied role in development, homeostasis, and regeneration of rapidly changing tissues like the mammalian intestinal epithelium. RNA modifications such as N6-methyladenosine (m⁶A) represent a burgeoning area of research in posttranscriptional regulation, with m⁶A being the most abundant modification found in approximately 25% of all mRNA transcripts. Multiple groups have begun to report m⁶A and associated regulation of mRNA fate as critical to key process in the intestinal epithelium. In this review, we synthesize key findings to date into the following 3 categories: m⁶A changes in response to the homeostatic luminal environment, m⁶A as a mediator of stemness in the crypt, and m⁶A as a tool for reacting to inflammation and injury. Over the course of this review, we will demonstrate how m⁶A is uniquely positioned to regulate homeostasis and disease states in the challenging and dynamic environment of the intestinal epithelium.

Background & aims: Gut dysbiosis is involved in the pathogenesis of acute pancreatitis (AP), yet therapeutic interventions remain limited. Our previous study found the relative abundance of Blautia is significantly decreased in AP, suggesting its protective role.

Methods: We quantified Blautia coccoides in AP patients and tested its effects in AP mice. Untargeted metabolomics identified deoxycholic acid. Farnesoid X receptor (FXR) signaling was tested with agonists and antagonists. 16S rRNA sequencing was applied to explore changes of gut microbiota. In vitro co-culture assays verified the microbial interaction. The role of bile salt hydrolase (BSH) was confirmed through experiments involving inhibitor and BSH-engineered E. coli.

Results: We observed reduced B. coccoides in AP patients that correlated with disease severity. In AP mice, gavage of B. coccoides mitigated pancreatic and intestinal injury. Untargeted metabolomics revealed the increased level of deoxycholic acid (DCA) which could reproduce the protective phenotype of B. coccoides. We further found DCA acts primarily within the intestine to activate FXR, which suppressed pro-inflammatory NF-κB and NLRP3 pathways. FXR activation also induced production of fibroblast growth factor 15 (FGF15), which protected pancreatic acinar cells. 16S rRNA sequencing showed that B. coccoides increased the abundance of BSH-producing genera, Parabacteroides and Bacteroides. In vitro, B. coccoides supernatant promoted the growth of representative strains from these genera. Inhibition of BSH abrogated the protective effects of B. coccoides, while administration of BSH-engineered E. coli could ameliorate AP.

Conclusions: B. coccoides alleviated AP by reshaping gut microbiota composition, enhancing BSH-mediated DCA production, and activating the intestinal FXR-FGF15 signaling to suppress inflammation.

Introduction: Neonatal necrotizing enterocolitis (NEC) is a severe gastrointestinal disorder with high mortality, characterized by epithelial cell injury and compromised epithelial repair. The mechanisms underlying defective epithelial regeneration remain poorly understood despite advances in single-cell omics. Addressing these challenges is essential for elucidating the pathogenesis of NEC and identifying therapeutic targets to restore epithelial regeneration and replace the damaged epithelial layer.

Methods: Using a well-established neonatal mouse model of NEC induced by formula feeding, hypoxia, and lipopolysaccharide, we applied an integrated multi-omics framework to map epithelial injury at transcriptomic, chromatin accessibility, and spatial levels. These included bulk RNA sequencing, single-nucleus RNA sequencing (snRNA-seq), single-nucleus assay for transposase-accessible chromatin sequencing (snATAC-seq), and multiplexed error-robust fluorescence in situ hybridization (MERFISH) for spatial transcriptomics. Complementary in vitro experiments and in vivo mouse models were utilized to evaluate NEC phenotypes, intestinal tissue morphology, and organoid formation.

Results: Changes in cell type composition, transcriptional network remodeling, and chromatin accessibility were observed in the small intestine of neonatal mice with NEC. Chromatin accessibility significantly changed in epithelial cells, highlighting their pivotal roles in NEC. A marked reduction in intestinal stem cells (ISCs) and transit-amplifying cells, along with an increased proportion of enteroendocrine cells, indicates disrupted epithelial regeneration and functional differentiation. These changes correlated with disrupted WNT signaling and stem cell maintenance genes (e.g., Lgr5, Smoc2, Axin2) and activation of inflammatory and hypoxia-related pathways (e.g., Il6, Tnfα). The epigenetic regulator Ezh2 was identified as a critical factor in maintaining LGR5+ ISCs and epithelial homeostasis. Knockdown of Ezh2 reduced stemness and proliferation-related gene expression and exacerbated inflammation. Reactivation of WNT signaling restored Ezh2 and Lgr5 expression, improving intestinal regeneration.

Conclusion: This study provides a comprehensive multi-omics atlas of epithelial injury in experimental NEC and reveals Ezh2 as a key regulator of LGR5+ ISC identity and regeneration. By integrating chromatin, transcriptomic, and spatial information, our findings highlight previously unrecognized mechanisms of ISC failure in NEC and support therapeutic strategies targeting Ezh2 and WNT signaling to restore epithelial integrity.

Background: Inflammatory cholangiopathies involve complex hepatic cell-cell interactions, contributing to inflammation, cholestasis, oxidative stress, senescence, and bile acid dysregulation. The objective of this proof-of-principle study was to examine the early-stage effects of lauric acid (LA), a dietary fatty acid and precursor of the LRH-1 agonist DLPC, in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet-induced cholangiopathy model.

Methods: We employed a 3-day DDC diet in male C57/BL6 mice and supplemented it with 20% dietary LA. Liver, primary hepatocytes and intrahepatic immune cells were analyzed for senescence, oxidative stress, and macrophage polarization.

Results: DDC mice showed elevated liver chemistries, hepatic inflammation (F4/80 histochemistry), ductular reaction and increased hepatocyte senescence markers. Using LC-MS metabolomics, we found that DDC liver injury was marked by increased hepatic levels of hydrophobic bile acids and oxidative stress. LA restored bile acid homeostasis and FXR-LRH-1 signaling in the liver and ileum, reduced oxidative stress, and normalized cholestasis-related gene expression in conjunction with improved liver injury, inflammation, and ductular reaction. DDC mice exhibited enhanced hepatocyte senescence (upregulated Cdkn1a, Cdkn1b, Ccl2) and STAT1 activation, all of which were attenuated by LA. ChIP confirmed STAT1 binding to the senescence Cdkn1b promoter, which was suppressed by LA. Additionally, LA enhanced LRH-1-STAT6 colocalization and signaling in BMDM from DDC mice, promoting polarization from pro-inflammatory to anti-inflammatory phenotypes, which was associated with increased STAT6 and LRH-1 activation and STAT6 promoter occupancy at anti-inflammatory genes.

Conclusions: These findings indicate the plausibility of LA's therapeutic potential in inflammatory cholangiopathies, which should be pursued in chronic cholangiopathy models.

Background & aims: The liver undergoes significant hemodynamic changes during surgery, transplantation, or cirrhosis with portal hypertension (PH). The hepatic artery buffer response (HABR), which compensates for reduced portal venous flow by increasing hepatic artery (HA) flow, is hypothesized to induce pathological portal tract remodeling. This study investigates the molecular mechanisms underlying this process.

Methods: PH was induced in Sprague-Dawley rats via partial portal vein ligation (PPVL). Structural evaluation (micro computed tomography [microCT]), immune cell profiling, hemodynamic measurements, and transcriptomic analysis in macrophages from sham or PPVL rats were conducted.

Results: MicroCT revealed decreased portal vein flow and increased HA flow correlated with portal pressure (r = 0.799; P < .01). A 2-fold increase in portal tract fibrosis (P < .001) was observed with increased alpha smooth muscle actin (α-SMA)+ myofibroblasts in PPVL rats. CD68⁺ macrophages peaked at 10 days post-PPVL, and their depletion significantly reduced fibrosis (P < .001), indicating critical roles of macrophages in portal tract remodeling. Vascular cell adhesion molecule 1 (VCAM-1) was elevated in HA endothelium and portal fibroblasts (PFs); VCAM-1 neutralization reduced collagen accumulation (P < .05), CD68+ macrophages (46.3%; P < .01), and CD3+ T cells (18%; P < .05). Macrophage-conditioned medium increased VCAM-1 in PFs (8-fold; P < .001) and enhanced PF migration, whereas VCAM-1 knockdown reduced this effect (P < .01). Single-cell RNA sequencing data (GSE171904) and RNA-fluorescence in situ hybridization revealed increased interactions between Osteopontin (Spp1)⁺ macrophages and PFs, with Spp1+ macrophages driving fibrosis. Spp1 knockdown in macrophages co-culture reduced PF fibrogenic markers, whereas recombinant Spp1 upregulated Col1a1, Fn1, and Acta2 expression in PFs.

Conclusions: Increased VCAM-1 in arterial endothelial cells and PFs facilitates the recruitment of Spp1⁺ macrophages, which drive HA flow-mediated vascular remodeling and portal tract fibrosis. These findings highlight arterial flow-induced fibrosis as a key mechanism in PH, potentially contributing to disease progression and decompensation.