American Journal of Physiology-Gastrointestinal and Liver Physiology

The transcription factor Nrf2 modulates the initiation and progression of a number of diseases including liver disorders. The aim of this study was to evaluate whether Nrf2 mediates hepatic adaptive responses to cholestasis. Wild-type and Nrf2-null mice were subjected to bile duct ligation (BDL) or a sham operation. Various assessments were performed at different days after surgery. Significant genotype-dependent changes in liver size, biliary ductular reaction, hepatocyte proliferation, and fibrotic response were not observed. However, as cholestasis progressed to Day 15 post-BDL, hepatocytes in the wild-type mice exhibited a tendency to dedifferentiate, indicated by the very weak expression of hepatic progenitor markers: CD133 and fibroblast growth factor-inducible 14 (Fn14). During the same period, Nrf2 deficiency augmented this tendency, manifested by higher CD133 expression, earlier, stronger, and continuous induction of Fn14 expression, and markedly reduced albumin production. Remarkably, as cholestasis advanced to the late stage (40 days after BDL), hepatocytes in the wild-type mice exhibited a Fn14+ phenotype and strikingly upregulated the expression of deleted in malignant brain tumor 1 (DMBT1), a protein essential for epithelial differentiation during development. In contrast, at this stage, hepatocytes in the Nrf2-null mice entirely inhibited the upregulation of DMBT1 expression, displayed a strong CD133+/Fn14+ phenotype indicative of severe dedifferentiation, and persistently reduced albumin production. Collectively, our studies revealed that Nrf2 maintains hepatocytes in the differentiated state potentially via the increased activity of the Nrf2/DMBT1 pathway during cholestasis. These findings enable us to gain novel insight into how hepatocytes respond to cholestasis. New and NoteworthyWe found that, when hepatocytes are exposed to cholestasis, they exhibit a tendency of dedifferentiation. In this case, Nrf2 is highly activated to markedly up-regulate the expression of epithelial differentiation gene DMBT1, which potentially prevent hepatocytes from dedifferentiation. Our findings revealed a plastic property of hepatocytes in response to cholestasis and demonstrated a novel Nrf2/DMBT1 pathway likely controlling this property of hepatocytes.

Gastrointestinal (GI) motility is regulated in a large part by the cells of the enteric nervous system (ENS), suggesting that ENS dysfunctions either associate with, or drive GI dysmotility in patients. However, except for select diseases such as Hirschsprungs Disease or Achalasia that show a significant loss of all neurons or a subset of neurons, our understanding of human ENS histopathology is extremely limited. Recent endoscopic advances allow biopsying patients full thickness gut tissues, which makes capturing ENS tissues simpler than biopsying other neuronal tissues, such as the brain. Yet, our understanding of ENS aberrations observed in GI dysmotility patients lags behind our understanding of central nervous system aberrations observed in patients with neurological disease. Paucity of optimized methods for histopathological assessment of ENS in pathological specimens represent an important bottleneck in ascertaining how the ENS is altered in diverse GI dysmotility conditions. While recent studies have interrogated ENS structure in surgically resected whole mount human gut, most pathological specimens are banked as formalin fixed paraffin embedded (FFPE) tissue blocks - suggesting that methods to interrogate ENS in FFPE tissue blocks would provide the biggest impetus for ENS histopathology in a clinical setting. In this report, we present optimized methods for immunohistochemical interrogation of the human ENS tissue on the basis of >25 important protein markers that include proteins expressed by all neurons, subset of neurons, hormones, and neurotransmitter receptors. This report provides a resource which will help pathologists and investigators assess ENS aberrations in patients with various GI dysmotility conditions.

IntroductionBiliary atresia (BA) is an obstructive cholangiopathy that initially affects the extrahepatic bile ducts (EHBDs) of neonates. The etiology is uncertain, but evidence points to a prenatal cause; however, the response of the fetal EHBD to injury remains unknown. The objective of this study was to define the fetal response to EHBD injury and to determine whether it follows a fetal wound healing paradigm. MethodsMouse, rat, sheep, and human EHBD samples were studied at different developmental time points. Models included a fetal sheep model of prenatal hypoxia, human BA EHBD remnants and liver samples taken at the time of the Kasai procedure, EHBDs isolated from neonatal rats and mice, and spheroids and other models generated from primary neonatal mouse cholangiocytes. ResultsA wide layer of high molecular weight HA encircling the lumen was characteristic of the normal perinatal but not adult EHBD. This layer, which was surrounded by collagen, expanded in injured ducts in parallel with extensive peribiliary gland (PBG) hyperplasia, increased mucus production and elevated serum bilirubin levels. BA EHBD remnants similarly showed increased HA centered around ductular structures compared with age-appropriate controls. High molecular weight HA typical of the fetal/neonatal ducts caused increased cholangiocyte spheroid growth, whereas low molecular weight HA induced abnormal epithelial morphology; low molecular weight HA caused matrix swelling in a bile duct-on-a-chip device. ConclusionThe fetal/neonatal EHBD, including in human EHBD remnants from Kasai surgeries, demonstrated an injury response with high levels of HA typical of the regenerative, scarless program termed fetal wound healing. Although generally beneficial, the expanded peri-luminal HA layer may swell and lead to elevated bilirubin levels and obstruction of the EHBD.

BackgroundShort bowel syndrome (SBS) resulting from extensive small bowel resection is characterized by severe malabsorption and represents the leading cause of intestinal failure. Although spontaneous intestinal adaptation can partially restore nutrient absorption, the temporal coordination and hierarchy of the adaptive mechanisms involved--particularly those linking the gut microbiota, enteroendocrine function, hyperphagia, and intestinal remodeling-- remain incompletely understood. MethodsWe investigated the kinetics of spontaneous intestinal adaptation in a rat model mimicking type 2 SBS over a 28-day postoperative period. Body weight, food intake, gastrointestinal transit, fecal losses, intestinal morphology, enteroendocrine hormone secretion, hypothalamic neuropeptide expression, and gut microbiota composition were assessed longitudinally in SBS and SHAM-operated rats. ResultsExtensive small bowel resection induced marked early weight loss, accelerated intestinal transit, diarrhea, and increased fecal energy losses that persisted throughout the follow-up. Profound gut microbiota remodeling occurred as early as day 7, remained largely stable thereafter, and was characterized by reduced diversity and enrichment in Lactobacillaceae and Enterobacteriaceae. Early elongation of remaining colon and epithelial remodeling were observed, preceding the jejunal hyperplasia, which became evident from day 14 onward. Enteroendocrine adaptation was marked by an early increase in plasma peptide YY levels, whereas glucagon-like peptide-1 showed a modest response. Food intake was increased in SBS rats from day 7 onward, and hyperphagia developed gradually and reached a plateau by the end of the third postoperative week, in parallel with increased hypothalamic AgRP levels and reduced POMC levels. No significant improvement of intestinal transit and fecal energy losses was observed during the study period. ConclusionIntestinal adaptation to extensive resection follows a time-dependent sequence in which early gut microbiota remodeling and colonic adaptation precede hyperphagia and small intestinal remodeling. These findings highlight the gut microbiota and the colon as central components of the early post-resection adaptation and potential therapeutic targets in SBS.

BackgroundBiliary atresia (BA) is the leading cause of pediatric liver transplants, however; the cause of biliary atresia (BA) is unknown. Furthermore, the most common treatment for this disease is with a surgical procedure, which has a greater than 50% failure rate after 5 years. Due to a lack of proper animal models to study the pathology of the disease, little progress has been made in the field. ObjectiveThe objective of this study was to test whether pre and postnatal 1,4-phenylene di-isothiocyanate (DITC) would induce bile duct injury and cholestasis in neonatal pigs. MethodsPregnant sows received DITC once at gestation week 5 (100 mg/kg; n=2), or 3 times at gestation weeks 5, 6, and 7 (100 mg/kg each; n=2), or twice per week at gestation weeks 5-16 (15 mg/kg each; n=2). Cesarian-delivered piglets of the sows were randomly assigned to receive approximately 200 mg/kg DITC on days two, four, and six of life or to remain untreated. Piglets were fed enterally and collected blood samples were monitored for markers of liver injury for 14 days. At the end of 14 days, tissues were weighed and collected for immunohistochemistry and histopathology scoring. ResultsPiglets from sows that received DITC for 11 weeks had lower (P < 0.05) final body weight and daily gain compared to other treatments. Piglets from sows that received DITC for 11 weeks had a transient increase in gamma-glutamyl transferase. Liver histological scoring and analysis also did not show signs of BA. Piglets that received DITC from 11-week DITC-treated sows had elevated hepatic bile acids (P < 0.05), but there was no difference in serum bile acids (P > 0.05). ConclusionsThe administration of DITC to pregnant sows and neonatal piglets did not result in the development of bile duct or hepatic injury.

Background & AimsBiliary atresia (BA), the leading cause of liver transplantation in children, presents in neonates with jaundice and progressive extrahepatic bile duct obstruction, yet its etiology and pathogenesis remain unknown. Here, we aimed to investigate the molecular mechanisms underlying BA and the susceptibility of cholangiocytes in the extrahepatic biliary tree using patient-derived extrahepatic cholangiocyte organoids (EHCOs). MethodsEHCOs were derived from common bile ducts remnants of BA patients undergoing Kasai portoenterostomy and from non-BA controls at the time of liver transplantation. Transcriptomic profiling was performed via bulk RNA sequencing, and analyzed in two ways: differentially expressed pathways and perturbation analysis to predict aberrant functions. Key findings were validated through mechanistic assays, immunofluorescence staining, qPCR and transmission electron microscopy (TEM). ResultsTranscriptomic analysis predicted significant alteration in endoplasmic reticulum (ER) stress, dysregulations of drug metabolism, alongside pronounced alterations in cellular adhesion and polarity-related genes in BA-derived EHCOs. Cell-to-cell alterations were observed with various proteins including E-cadherin, RhoU, Sox17 and CFTR. BA EHCOs had an increased endoplasmic reticulum (ER) stress response, exemplified by elevated PERK, BiP, and ATF4 along with abnormal ER on TEM. Furthermore CHOP, ERO1A, WFS1, and SOD3 were decreased suggestive of abnormal ER stress response. BA EHCOs displayed increased toxicity to biliatresone-induced injury and inhibition of cytochrome P450 resulted in attenuation of the ER stress markers PERK, BiP and ATF4. Finally, liver hilum biopsies from BA patients undergoing Kasai portoenterostomy confirmed elevated PERK and PGR78(BiP) consistent with the EHCOs analysis. ConclusionsBA EHCOs exhibit disrupted polarity, ER stress, and increased susceptibility to drug toxicity. These findings highlight key pathogenic mechanisms in BA and suggest that targeting these pathways may help mitigate cholangiocyte injury in BA. Impact and implicationsThis study provides the first transcriptomic and functional analysis of human extrahepatic cholangiocyte organoids (EHCOs) derived from biliary atresia (BA) patients. By focusing on the extra-hepatic biliary tree, we identified key mechanisms of cholangiocyte injury, including persistent ER stress, impaired stress response pathways, altered drug metabolism and disrupted epithelial polarity. These findings highlight ER stress and metabolic vulnerability as potential therapeutic targets and establish EHCOs as a tractable model for investigating BA pathogenesis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/649927v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@150ab7org.highwire.dtl.DTLVardef@172953forg.highwire.dtl.DTLVardef@1a46e4eorg.highwire.dtl.DTLVardef@45c5c6_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIFirst transcriptomic profiling of extrahepatic cholangiocyte organoids (EHCOs) from BA patients, C_LIO_LIrevealing distinct molecular alterations compared to controls. C_LIO_LIBA EHCOs exhibit disrupted epithelial polarity, with downregulation of E-cadherin and Sox17 and upregulation of CFTR. C_LIO_LIER stress is a hallmark of BA cholangiocytes, with elevated PERK, BiP, and ATF4, and C_LIO_LIdysregulation of downstream effectors including CHOP, ERO1A, and SOD3. C_LIO_LIBA EHCOs are more susceptible to biliatresone-induced injury, with enhanced ER stress and structural damage. C_LIO_LIInhibition of cytochrome P450 activity (CYP4A) reduces ER stress markers. C_LI

BackgroundAn emerging clinical phenomenon in patients with end stage liver disease is progressive skeletal muscle atrophy. This loss in lean mass predicts poor survival outcomes for liver disease patients and highlights an underappreciated crosstalk between injured liver and muscle that lacks defined mediators. The purpose of our study was to identify potential liver-muscle mediator(s) in pre-clinical in vivo models of liver injury which may contribute to the muscle loss observed in liver disease. MethodsUtilizing a mouse model of carbon tetrachloride CCl4-induced liver injury in the presence or absence of cardiotoxin-induced muscle injury, we evaluated whether neutralizing Activin type IIB receptor (ActRIIB) ligands, or specifically growth differentiation factor 8 (Gdf8), could preserve or reverse muscle atrophy associated with liver disease. ResultsWe found that hepatic injury via CCl4 or bile duct ligation (BDL) similarly caused significant muscle atrophy along with decreased gene expression in key myogenesis markers. This adverse effect of injured liver on muscle were completely prevented and reversed by the intervention of Activin type IIB receptor (ActRIIB)-Fc fusion protein, which neutralizes the ActRIIB ligands, including Activins and growth differentiation factor 8 (Gdf8 or myostatin). The results indicate that ActRIIB ligands promoted muscle atrophy which was manifested in response to hepatic injury/disease and conferred the negative communication of injured liver with muscle. Indeed, direct injection of exogenous Gdf8 protein into muscle along with acute focal muscle injury recapitulated similar dysregulated muscle regeneration as observed with liver injury. Furthermore, we found that hepatocytes produced Gdf8 in response to liver injury in rodents and in patients with end stage liver disease. A neutralizing antibody to Gdf8 attenuated muscle atrophy and unexpectedly ameliorated liver fibrosis in both CCl4 and BDL models. Following this observation, we demonstrated Gdf8s ability to induce fibrogenesis in stellate cells, potentially identifying a novel hepatic role for this protein. Moreover, hepatic Gdf8 promoted muscle wasting in response to liver damage and hindered skeletal muscle regeneration. ConclusionOur findings identified Gdf8 as a novel hepatomyokine contributing to injured liver-muscle negative crosstalk and liver injury progression. Moreover, we demonstrated a promising therapeutic strategy for muscle atrophy accompanying liver diseases.

Background and aimsMast cells (MCs) play a significant role in autoimmune diseases by mediating inflammatory responses, innate and adaptive responses, angiogenesis, and various pathological processes. MC numbers are significantly increased in chronic liver disease and liver cancer, and degranulation leads to a release of MC mediators, including chymase, which increases inflammation, activates hepatic stellate cells (HSCs), ultimately leading to fibrosis. Primary sclerosing cholangitis (PSC) is a chronic, progressive cholestatic liver disease characterized by inflammation, fibrosis, ductular reaction, and eventual liver failure. MCs and their mediators, particularly chymase, have been implicated in PSC pathogenesis; however, targeting chymase therapeutically has remains largely unexplored. In this study, we aimed to evaluate the efficacy of INVA8001, a highly selective chymase inhibitor, on PSC pathogenesis in the Mdr2 knockout mouse (Mdr2-/- mice) model of PSC. Approach and ResultsWe evaluated the levels of chymase and other MC markers in liver biopsy samples collected from late-stage PSC patients. The effect of chymase inhibition was evaluated using a highly selective and potent small molecule chymase inhibitor, INVA8001, in Mdr2-/- mice. Ten-week-old male Mdr2-/- mice were injected intraperitoneally (IP) with 20 mg/kg of INVA8001 daily for two weeks and varying parameters of disease pathogenesis, including MC activation, inflammation, fibrosis, biliary pathology, and cholestasis were evaluated. In addition, histological, immunohistochemical, biochemical, and molecular analyses were conducted to evaluate the effects of INVA8001 treatment in Mdr2-/- mice. The liver biopsies of PSC patients showed an increased number of chymase-positive cells compared with control samples (collected from non-diseased patients). INVA8001 treatment resulted in a reduction of MC accumulation, inflammation, histological damage, fibrosis, ductular reaction, and biliary senescence in Mdr2-/- mice. The current data show the pathophysiological role of chymase in PSC and the impact of a selective chymase inhibitor on PSC disease pathogenesis. This can further be extrapolated to various MC-driven diseases such as chronic urticaria, atopic dermatitis, asthma, metabolic dysfunction-associated steatohepatitis (MASH), and eosinophilic gastrointestinal diseases, among others, where chymase is central to the disease pathogenesis. ConclusionsOur findings identify chymase as a key driver of PSC pathogenesis establishing INVA8001 as a promising new therapeutic candidate for hepatobiliary disorders, including PSC. Chymase inhibition simultaneously targets MC activation, inflammation, fibrosis, and biliary senescence, and offers a multifaceted approach to treating PSC and other MC-related disorders.

EGF-Containing Fibulin Extracellular Matrix Protein 1 (EFEMP1, also called fibulin 3) is an extracellular matrix protein linked in a genome-wide association study to biliary atresia, a fibro-inflammatory disease of the neonatal extrahepatic bile duct. EFEMP1 is expressed in most tissues and Efemp1 null mice have decreased elastic fibers in visceral fascia; however, in contrast to other short fibulins (fibulins 4 and 5), EFEMP1 does not have a role in the development of large elastic fibers, and its overall function remains unclear. We demonstrated that EFEMP1 is expressed in the submucosa of both neonatal and adult mouse and human extrahepatic bile ducts and that, in adult Efemp1+/- mice, elastin organization into fibers is decreased. We used pressure myography, a technique developed to study the mechanics of the vasculature, to show that Efemp1+/- extrahepatic bile ducts are more compliant to luminal pressure, leading to increased circumferential stretch. We conclude that EFEMP1 has an important role in the formation of elastic fibers and mechanical properties of the extrahepatic bile duct. These data suggest that altered expression of EFEMP1 in the extrahepatic bile duct leads to an abnormal response to mechanical stress such as obstruction, potentially explaining the role of EFEMP1 in biliary atresia.

Background and AimsAcetaminophen (APAP) overdose is the leading cause of acute liver failure, with one available treatment, N-acetyl cysteine (NAC). Yet, NAC effectiveness diminishes about ten hours after APAP overdose, urging for therapeutic alternatives. This study addresses this need by deciphering a mechanism of sexual dimorphism in APAP-induced liver injury, and leveraging it to accelerate liver recovery via growth hormone (GH) treatment. GH secretory patterns, pulsatile in males and near-continuous in females, determine the sex bias in many liver metabolic functions. Here, we aim to establish GH as a novel therapy to treat APAP hepatotoxicity. Approach and ResultsOur results demonstrate sex-dependent APAP toxicity, with females showing reduced liver cell death and faster recovery than males. Single-cell RNA sequencing analyses reveal that female hepatocytes have significantly greater levels of GH receptor expression and GH pathway activation compared to males. In harnessing this female-specific advantage, we demonstrate that a single injection of recombinant human GH protein accelerates liver recovery, promotes survival in males following sub-lethal dose of APAP, and is superior to standard-of-care NAC. Alternatively, slow-release delivery of human GH via the safe nonintegrative lipid nanoparticle-encapsulated nucleoside-modified mRNA (mRNA-LNP), a technology validated by widely used COVID-19 vaccines, rescues males from APAP-induced death that otherwise occurred in control mRNA-LNP-treated mice. ConclusionsOur study demonstrates a sexually dimorphic liver repair advantage in females following APAP overdose, leveraged by establishing GH as an alternative treatment, delivered either as recombinant protein or mRNA-LNP, to potentially prevent liver failure and liver transplant in APAP-overdosed patients.

Mutations in the ABCB4 gene lead to a wide-spectrum of rare liver diseases including progressive familial intrahepatic cholestasis type 3 (PFIC3) and low-phospholipid associated cholelithiasis (LPAC) syndrome. PFIC3 patients develop symptoms during late infancy, including severe itching, jaundice, and failure to thrive. The condition may progress to liver failure during childhood or adulthood. This is a highly unmet medical condition where liver transplantation is the only option to correct this disease. Recently, exciting data suggested that restoration of the ABCB4 function via gene replacement could rescue liver phenotypes associated with ABCB4 dysfunction in a preclinical PFIC3 mouse model. Here, we used mRNA LNP platform to determine expression and durability of ABCB4 in the liver of wildtype mice. In addition, we generated Abcb4-/- mice to study the efficacy of systemic delivery of ABCB4 mRNA LNP. We observed a robust and durable expression of hABCB4 up to 72 hours post systemic dosing in the liver of wild-type mice. Systemic administration of hABCB4 mRNA achieved a remarkable restoration of phosphatidylcholine levels in bile, a significant decrease in liver stiffness as measured by shear wave elastography, and amelioration of liver histopathology including fibrosis and ductular reaction. We conclude that administration of hABCB4 mRNA LNPs was sufficient to ameliorate fibrosis markers in the PFIC3 mouse model. Our data suggests that gene replacement using mRNA LNP modality could provide an excellent opportunity for patients with biliary diseases.

Pancreatitis is an inflammatory disease of the pancreas that can arise due to various factors, including environmental risks such as diet, alcohol, and smoking, as well as genetic predispositions. In some cases, pancreatitis may progress and become chronic, leading to irreversible damage and impaired pancreatic function. Genome-wide association studies (GWAS) have identified polymorphisms at the X-linked CLDN2 locus as risk factors for both sporadic and alcohol-related chronic pancreatitis. CLDN2 encodes claudin-2 (CLDN2), a paracellular cation-selective channel localized at tight junctions and expressed in the pancreas and other secretory organs. However, whether and how CLDN2 may modify pancreatitis susceptibility remains poorly understood. We aimed to clarify the potential role of CLDN2 in the onset and progression of pancreatitis. We employed multiple methodologies to examine the role of CLDN2 in human pancreatic tissue, caerulein-induced experimental pancreatitis mouse model, and pancreatic ductal epithelial organoids. In both human chronic pancreatitis tissues and caerulein-induced experimental pancreatitis, CLDN2 protein was significantly upregulated in pancreatic ductal epithelial cells. Our studies using pancreatic ductal epithelial organoids and mice demonstrated the inflammatory cytokine IFN{gamma} upregulates claudin-2 expression at both RNA and protein levels. Following caerulein treatment, Ifng KO mice had diminished upregulation of CLDN2 relative to WT mice, indicating that caerulein-induced claudin-2 expression is partially driven by IFN{gamma}. Functionally, Cldn2 knockout mice developed more severe caerulein-induced experimental pancreatitis, indicating CLDN2 plays a protective role in pancreatitis development. Pancreatic ductal epithelial organoid-based studies demonstrated that CLDN2 is critical for sodium-dependent water transport and necessary for cAMP-driven, CFTR-dependent fluid secretion. These findings suggest that functional crosstalk between CLDN2 and CFTR is essential for fluid transport in pancreatic ductal epithelium, which may protect against pancreatitis by adjusting pancreatic ductal secretion to prevent worsening autodigestion and inflammation. In conclusion, our studies suggest CLDN2 upregulation during pancreatitis may play a protective role in limiting disease development, and decreased CLDN2 function may increase pancreatitis severity. These results point to the possibility of modulating pancreatic ductal CLDN2 function as an approach for therapeutic intervention of pancreatitis.

Activation of bile acid (BA) receptor, farnesoid X receptor (FXR) has been shown to inhibit inflammatory responses and improve tissue ischemia-reperfusion injury (IRI). This study investigated the effect of FXR deficiency on liver IRI, using a liver warm IRI mouse model. We demonstrate that liver IRI resulted in decreased FXR expression in the liver of WT mice. FXR-/-mice displayed greater liver damage and inflammatory responses than WT mice, characterized by significant increases in liver weight, serum AST and ALT, hepatocyte apoptosis and liver inflammatory cytokines. Liver IRI increased expression of X box binding protein 1 (XBP1) and FGF21 in WT liver, but not in FXR-/- liver, which conversely increased CHOP expression, suggesting a loss of ER stress protection in the absence of FXR. FXR deficiency increased circulating total BAs and altered BA composition with reduced TUDCA and hepatic BA synthesis markers. FXR deficiency also reshaped gut microbiota composition with increased Bacteroidetes and Proteobacteria and decreased Firmicutes. Curiously, Bacteroidetes were positively and Firmicutes were negatively correlated with serum ALT levels. Administration of FXR agonist CDCA inhibited NF-{kappa}B activity and TNF expression in vitro and improved liver IRI in vivo. Our findings demonstrate that FXR signaling plays an important role in the modulation of liver IRI.

Background and AimsGlissons capsule is the interstitial connective tissue that surrounds the liver. As part of its normal physiology, it withstands significant daily changes in liver size. The pathophysiology of the capsule in disease is not well understood. The aim of this study was to characterize the changes in capsule matrix, cellular composition, and mechanical properties that occur in liver disease and to determine whether these correlate with disease severity or etiology. Methods10 control, 6 steatotic, 7 moderately fibrotic and 37 cirrhotic patient samples were collected from autopsies, intraoperative biopsies and liver explants. Matrix proteins and cell markers were assessed by staining and second harmonic generation imaging. Mechanical tensile testing was performed on a test frame. ResultsCapsule thickness was significantly increased in cirrhotic samples compared to normal controls irrespective of disease etiology (69.62 {+/-} 9.99 and 171.269 {+/-} 16.65 {micro}m respectively), whereas steatosis and moderate fibrosis had no effect on thickness (62.15 {+/-} 4.97 {micro}m). Changes in cirrhosis included an increase in cell number (fibroblasts, vascular cells, infiltrating immune cells and biliary epithelial cells). Key matrix components (collagens 1 and 3, hyaluronan, versican and elastin) were all deposited in the lower capsule although only the relative amounts per area of hyaluronan and versican were increased. Organizational features including crimping and alignment of collagen fibers were also altered in cirrhosis. Unexpectedly, capsules from cirrhotic livers had decreased resistance to loading in comparison to controls. ConclusionsThe liver capsule, like the parenchyma, is an active site of disease, demonstrating changes in matrix and cell composition as well as mechanical properties. Lay summaryWe assessed the changes in composition and response to stretching of the liver outer sheath, the capsule, in human liver disease. We find an increase in key structural components and numbers of cells as well as a change in matrix organization of the capsule in the later stages of disease. This allows the diseased capsule to stretch more under any given force, suggesting it is less stiff than healthy tissue. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/505570v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@10a9b60org.highwire.dtl.DTLVardef@15eea52org.highwire.dtl.DTLVardef@69b874org.highwire.dtl.DTLVardef@cccd03_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThe capsule is an active site of disease: thickness and cellularity increase markedly in cirrhosis C_LIO_LIExtracellular matrix composition and organization change in cirrhosis C_LIO_LIThe cirrhotic capsule stretches more and is less stiff C_LI

IntroductionNeonatal 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. MethodsMulti-omics approaches were employed to investigate molecular and spatial changes in experimental NEC at epigenetic and transcriptomic 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. ResultsChanges 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, Tnf). 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. ConclusionThis study reveals dynamic transcriptomic, epigenetic, and spatial changes in NEC and highlights Ezh2 as a key regulator of LGR5+ intestinal stem cell function and epithelial regeneration. These findings provide insights into NEC pathogenesis and a basis for therapies targeting Ezh2 and WNT signaling to restore intestinal integrity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/647851v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@1ad89eaorg.highwire.dtl.DTLVardef@396282org.highwire.dtl.DTLVardef@172596forg.highwire.dtl.DTLVardef@4daf28_HPS_FORMAT_FIGEXP M_FIG C_FIG

Background & AimsIntestinal tuft cells have recently been the interest of studies in several human gastrointestinal diseases. However, the impact of tuft cell deletion on intestinal physiological functions are not fully understood. This study investigated the effects of acute tuft cell loss on nutrient absorption and cell lineage differentiation. MethodsTuft cell deletion was induced in DCLK1-IRES-GFP-CreERT2/+;Rosa-DTA (DCLK1-DTA) mice by a single tamoxifen injection concomitant with littermate controls. Intestinal tissues were analyzed two-, four-, or seven-days post tamoxifen injection. ResultsDCLK1-DTA mice showed significantly shortened small intestinal length and body weight loss on day 4. Impaired activities of Na+-dependent glucose transporter 1 (SGLT1) and cystic fibrosis transmembrane regulator (CFTR) were observed in Ussing chamber experiments. Tissue immunostaining revealed a transient deletion of intestinal and biliary tuft cells, which was maximal on day 4 and recovered by day 7. On day 4 post tamoxifen, cholecystokinin (CCK)+ enteroendocrine cell numbers were increased particularly in the ileum. Correlated with the tuft cell reduction, the frequency of mislocalized Paneth cells, which were co-labeled by Paneth and goblet cell markers, was increased in the villus regions. In the lamina propria, fewer mast cells and leukocytes were found in the day 4 DCLK1-DTA mice than in controls. ConclusionAblation of intestinal tuft cells may induce nutrient malabsorption through alterations in epithelial cell proliferation and differentiation along with changes in mucosal defense response. These observations elucidate a new role for tuft cells in regulating intestinal absorption and mucosal regeneration.

Background & AimsAutophagy has been demonstrated to play roles in esophageal pathologies both benign and malignant. Here, we aim to define the role of autophagy in esophageal epithelium under homeostatic conditions. MethodsWe generated tamoxifen-inducible, squamous epithelial-specific Atg7 (autophagy related 7) conditional knockout mice to evaluate effects on esophageal homeostasis and response to the carcinogen 4-nitroquinoline 1-oxide (4NQO) using histological and biochemical analyses. We FACS sorted esophageal basal cells based upon fluorescence of the autophagic vesicle (AV)-identifying dye Cyto-ID, then subjected these cells to transmission electron microscopy, image flow cytometry, 3D organoid assays, RNA-Sequencing (RNA-Seq), and cell cycle analysis. 3D organoids were subjected to passaging, single cell (sc) RNA-Seq, cell cycle analysis, and immunostaining. ResultsGenetic autophagy inhibition in squamous epithelium resulted in increased proliferation of esophageal basal cells. Esophageal basal cells with high AV level (Cyto-IDHigh) displayed limited organoid formation capability upon initial plating but passaged more efficiently than their counterparts with low AV level (Cyto-IDLow). RNA-Seq suggested increased autophagy in Cyto- IDHigh esophageal basal cells along with decreased cell cycle progression, the latter of which was confirmed by cell cycle analysis. scRNA-Seq of 3D organoids generated by Cyto-IDLow and Cyto- IDHigh cells identified expansion of 3 cell populations, enrichment of G2/M-associated genes, and aberrant localization of cell cycle-associated genes beyond basal cell populations in the Cyto- IDHigh group. Ki67 expression was also increased in organoids generated by Cyto-IDHigh cells, including in cells beyond the basal cell layer. Squamous epithelial-specific autophagy inhibition induced significant weight loss in mice treated with 4NQO that further displayed perturbed epithelial tissue architecture. ConclusionsHigh AV level identifies esophageal epithelium with limited proliferation and enhanced self-renewal capacity that contributes to maintenance of the esophageal proliferation- differentiation gradient in vivo.

BackgroundHirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of Hirschsprungs disease (HSCR). This study investigated the role of Paneth cells (PCs) and gut microbiota in HAEC development. MethodsMale Sprague-Dawley rats with HSCR were established by exposure of 0.1% (n = 30) benzalkonium chloride (BAC) to rectosigmoid serosa and sacrificed at 1-, 3-, 5-, 8-, and 12-weeks postintervention. The sham group was included and sacrificed on Week 12. Hematoxylin-Eosin staining was conducted to count the number of ganglionic cells and analyze the degree of enterocolitis. Intestinal barrier function was assessed for the ratio of anti-peripherin, occludin and acetylcholinesterase (AChE)/butyrylcholinesterase (BChE). PCs antimicrobial peptide (AMP) was evaluated by cryptdins, secretory Phospholipase A2, and lysozyme levels by qRT-PCR, respectively. 16S rRNA high throughput sequencing on faecal samples was used to analyze the changes in intestinal microbiota diversity in each group. ResultsCompared with sham groups, 0.1% BAC group rats had fewer ganglion cells after 1-week postintervention. Occludin and peripherin were decreased, and AChE/BChE ratio was increased, respectively. Sigmoid colon tissues from BAC-treated rats showed increased -defensins positive PCs on Week 5 postintervention. Conversely, PCs-produced AMP tended to decrease from Week 5 to Week 12. Rats in the sham group demonstrated increased Lactobacillus and decreased Bacteroides, while rats in the 0.1% BAC exhibited reciprocal changes. Enterocolitis occurred from Week 1 postintervention onwards. ConclusionDisruption of PCs in the Week 5 postintervention and dysbiosis exacerbate the occurrence of HAEC. This research sheds new light on the cellular mechanisms of HAEC development.

Background and AimsIn clinical trials for reducing fibrosis in NASH patients, therapeutics that target macrophages have had variable results. We evaluated intrahepatic macrophages in patients with non-alcoholic steatohepatitis to determine if fibrosis influenced phenotypes and expression of CCR2 and Galectin-3. Approach & ResultsWe used nCounter to analyze liver biopsies from well-matched patients with minimal (n=12) or advanced (n=12) fibrosis to determine which macrophage-related genes would be significantly different. Known therapy targets (e.g., CCR2 and Galectin-3) were significantly increased in patients with cirrhosis. However, several genes (e.g., CD68, CD16, and CD14) did not show significant differences, and CD163, a marker of pro-fibrotic macrophages was significantly decreased with cirrhosis. Next, we analyzed patients with minimal (n=6) or advanced fibrosis (n=5) using approaches that preserved hepatic architecture by multiplex-staining with anti-CD68, Mac387, CD163, CD14, and CD16. Spectral data were analyzed using deep learning/artificial intelligence to determine percentages and spatial relationships. This approach showed patients with advanced fibrosis had increased CD68+, CD16+, Mac387+, CD163+, and CD16+CD163+ populations. Interaction of CD68+ and Mac387+ populations was significantly increased in patients with cirrhosis and enrichment of these same phenotypes in individuals with minimal fibrosis correlated with poor outcomes. Evaluation of a final set of patients (n=4) also showed heterogenous expression of CD163, CCR2, Galectin-3, and Mac387, and significant differences were not dependent on fibrosis stage or NAFLD activity. ConclusionsApproaches that leave hepatic architecture intact, like multispectral imaging, may be paramount to developing effective treatments for NASH. In addition, understanding individual differences in patients may be required for optimal responses to macrophage-targeting therapies.

PurposeHirschsprung-associated enterocolitis remains a major postoperative complication of Hirschsprungs disease (HD), and impaired epithelial barrier integrity has been proposed as a contributing factor. In this study, we investigated whether 12-hydroxyheptadecatrienoic acid (12-HHT), an endogenous leukotriene B4 receptor 2 (BLT-2) agonist, enhances the epithelial barrier and exerts anti-inflammatory effects in patient-derived colonic organoids. MethodsNormoganglionic specimens from rectal/rectosigmoid HD at pull-through (HD-N; n = 8) and transverse colon specimens from anorectal malformation (ARM) at colostomy closure (n = 10) were used to generate colonic organoids. Epithelia were isolated using ethylenediaminetetraacetic acid and subsequently embedded in Matrigel. Baseline expression of TJP1, TJP2, F11R (encoding junctional adhesion molecule-A), JAM2, CLDN1, CLDN3, CLDN4) and LTB4R2 (encoding BLT-2) was assessed by qPCR and immunoblotting. Organoids were then treated with 12-HHT (0.4, 2, or 10 M) for 7 days, followed by qPCR. Additional experiments assessed cytokine expression (IL1B, IL6) and TJPs after 24 h with tumor necrosis factor- (TNF-, 100 ng/mL) plus phosphate buffered saline or 12-HHT. Barrier function was evaluated using FITC-dextran influx assays. ResultsHD-N and ARM organoids exhibited similar growth efficiencies. Baseline expression for F11R, JAM2, CLDN1, CLDN3, CLDN4, and LTB4R2 was significantly lower in HD-N than in ARM. TJPs were upregulated by 12-HHT at 2 and 10 M in both groups, with stronger effects in ARM. In HD-N organoids, 10 M 12-HHT suppressed TNF--induced IL1B and IL6 elevation mitigated tight junction proteins (TJPs) downregulation more effectively than 2 M. 12-HHT attenuated TNF--induced FITC-dextran influx in HD-N organoids. Conclusion12-HHT may exert anti-inflammatory effects by integrating TJPs of HD-N.