American Journal of Physiology-Gastrointestinal and Liver Physiology

BACKGROUNDMetabolic dysfunction-associated steatotic liver disease (MASLD) is a systemic immunometabolic disorder rapidly increasing worldwide, affecting nearly 38% of adults. Gut dysbiosis and host genetic factors, such as PNPLA3 I148M variant, modulate disease development and progression. Through the gut-liver axis, increased intestinal permeability enables microbial translocation to the liver, promoting inflammation and metabolic disruption. However, the composition and functional potential of the hepatic microbiome remain poorly characterized. Understanding its relationship with histological injury and genetic susceptibility may provide novel mechanistic insights. We hypothesized that the hepatic microbiome composition and function are associated with histological severity and PNPLA3 genotype in this disease. AIMTo characterize the hepatic microbiome and assess its association with histological severity and PNPLA3 genotype. METHODSThis cross-sectional observational study included 30 patients with MASLD from a tertiary care hospital. Liver tissue underwent shotgun metagenomic sequencing. Histological severity was assessed using the NAFLD Activity Score (NAS). PNPLA3 genotype was determined by PCR. Differential abundance and functional enrichment analyses were performed using MaAsLin2. Somatic variants were identified using Mutect2. Correlation networks were constructed using Spearmans correlation coefficients. RESULTSPatients with advanced histological injury (NAS [≥]5) and PNPLA3 I148M carriers showed a trend toward higher somatic mutational load and a markedly reduced microbial abundance. Analyses revealed broad compositional shifts across bacterial, fungal, viral, and eukaryotic taxa, affecting both commensal and context-dependent pathobiont lineages. Pseudomonas species were enriched, whereas Siphoviridae phages were depleted in advanced disease and PNPLA3 I148M carriers. Functional analysis revealed enrichment of pathways related to nutrient transport and metabolic stress adaptation, while TonB-associated functions were enriched in advanced liver injury but depleted in PNPLA3 I148M carriers. Network analysis identified Sphingomonas leidyi as a keystone node associated with hexosamine metabolism. Salmonella enterica abundance positively correlated with somatic variant burden, suggesting a link between microbial signatures and genomic instability. Histological progression and the risk PNPLA3 genotype were accompanied by marked topological simplification, reflecting less resilient community structures. CONCLUSIONSThe hepatic microbiome in MASLD is a low-biomass, polymicrobial ecosystem shaped by the host genetic background. Its functional activity, taxonomic composition and system architecture bidirectionally relate to liver DNA instability and the severity of histological damage. Core tipThis study characterizes the multi-kingdom hepatic microbiome in MASLD using FFPE-derived metagenomics. We demonstrate that microbial abundance-including bacteria, fungi, protozoa, and viruses- significantly decreases with increased histological severity and the PNPLA3 risk genotype. Rather than global diversity shifts, results showed that disease progression could be linked to specific functional adaptations and simplified microbial network connectivity. In addition, we described associations between specific taxa and somatic mutational burden, suggesting a link between microbial signals and genomic instability. These findings indicate that changes in the liver microbiome as a whole, rather than specific taxonomic modifications, influence MASLD pathophysiology.

Cell division cycle 42 (Cdc42) is a member of the Rho family of small GTPases, which plays crucial roles in regulating cytoskeletal remodeling, and membrane trafficking. While previous studies implicated Cdc42 in controlling intestinal epithelial homeostasis, the involvement of this small GTPase in the process of intestinal fibrogenesis remains unexplored. Our study was designed to determine whether Cdc42 regulates the fibrogenic activation of intestinal myofibroblasts in vitro. The study was conducted using a CCD-18Co normal human colonic fibroblast cell line, and primary human intestinal myofibroblasts (HIMF) isolated from Crohns disease (CD) patients. CCD-18Co and HIMF cells were stimulated by transforming growth factor-{beta}1 (TGF-{beta}1). Cdc42 was inhibited either genetically, using siRNA-mediated knockdown, or pharmacologically using specific Cdc42 inhibitors, ML141 and CASIN. Genetic and pharmacologic inhibition of Cdc42 markedly reduced TGF-{beta}1 induced expression of the major contractile cytoskeletal proteins, -smooth muscle actin, calponin 1 and L-caldesmon. Furthermore, Cdc42 inhibition significantly attenuated expression of key extracellular matrix (ECM) proteins, fibronectin and collagen I, in activated CCD-18Co cells and HIMF. Interestingly, decreased expression of contractile and ECM proteins in Cdc42-depleted myofibroblasts was not due to downregulation of the TGF-{beta}1 signaling, decreased mRNA transcription or increased lysosomal or proteasomal degradation of these proteins. Such suppressed pro-fibrotic activation of Cdc42-deficient CCD-18Co cells and HIMF involved a selective inhibition of protein translation due to inactivation of the AKT-mammalian target of rapamycin (mTOR) signaling module. These findings highlight Cdc42 as a key regulator of intestinal fibrosis that controls mTOR activation to enhance ECM production and contractile actomyosin cytoskeleton in intestinal myofibroblasts.

The intestinal mesentery has been recently classified as a 'new' organ and contains various cell types including adipocytes, preadipocytes, endothelial cells, and immune cells. In addition, neuronal cell bodies are found in the small intestinal mesentery and are situated either individually or clustered together with glial cells in small ganglion structures close to the gut wall. However, little is known about the origin or function of these extra-intestinal mesenteric neurons. The aim of this study was to better these characterize mesenteric neurons and to examine their connectivity with the ENS using calcium imaging in adult mouse ileum with the mesentery attached. Here we show that neurons in the mesentery express typical ENS neurochemical markers, respond to 5-HT, ATP and the nicotinic agonist DMPP, and receive nicotinic synaptic inputs. Furthermore, using labeling with the neuronal tracer DiI, some mesenteric neurons were found to project into the gut wall and can provide functional excitatory inputs to myenteric neurons. By contrast, we did not find evidence for mesenteric neurons providing inputs to other extrinsic neuronal targets, suggesting that they preferentially interact with the ENS. We also demonstrate that mesenteric neurons can be activated by intestinal distension and that the mesentery provides a source of inhibition to the myenteric plexus. Taken together, we show that the ENS not only interacts with vagal and spinal afferents, and sympathetic and parasympathetic nerves, but also neurons situated in the mesentery. Finally, our data suggest that these neurons may provide a form of negative feedback to the myenteric plexus such as in the event of intestinal distension. These findings have important implications for the regulation of intestinal motility in physiological and pathophysiological conditions.

Background & AimsHepatitis B virus (HBV) drives hepatocellular carcinoma in part through the activity of its X protein (HBx), yet the mechanisms by which HBx alters hepatocyte function remain incompletely understood. Progress has been limited by the lack of relevant human models that support controlled HBx expression in mature hepatocytes. Here, we use an improved hepatocyte-like organoid (HLO) platform that supports enhanced hepatocyte maturation to investigate HBx function in a differentiated hepatocyte context. MethodsAdult stem cell-derived HLOs were differentiated using an optimized protocol to generate hepatocyte-like cells with enhanced maturation and transcriptional similarity to primary liver tissue. HBx function was interrogated using both cognate promoter-driven expression and doxycycline-inducible systems across multiple donor-derived organoid lines. Transcriptomic, pathway, and single-cell imaging analyses were performed to assess the impact of HBx expression on hepatocytes. ResultsHBx expression consistently suppressed apoptosis-associated transcripts and reduced expression of core hepatocyte identity genes, including CYP3A4. Pathway analysis revealed downregulation of liver-specific functions, including metabolism, detoxification, complement, and coagulation. At the single-cell level, higher HBx expression was associated with reduced caspase 3/7 activation following apoptotic challenge and decreased hepatocyte marker expression. Functionally, HBx expression increased resistance to apoptosis and enhanced the ability of differentiated hepatocyte-like cells to revert to a proliferative, less differentiated state. ConclusionsHBx expression in differentiated human liver organoids reduces apoptosis and impairs hepatocyte identity, consistently across donors and expression systems. These findings support a model in which HBx promotes a survival-permissive less differentiated state that may contribute to early HBV-driven tumorigenesis. This HLO platform provides a relevant system to dissect HBV-host interactions and reveals a mechanism by which HBV may prime the liver for malignant transformation. Impact and implicationsUnderstanding how HBV promotes hepatocellular carcinoma remains a critical challenge, partly due to the lack of physiologically relevant human derived model systems to study HBx function. Using a differentiated adult human liver organoid system, we show that HBx simultaneously suppresses apoptosis and disrupts hepatocyte identity, providing a mechanistic framework for how HBV may prime hepatocytes for malignant transformation. These findings are particularly relevant for researchers studying HBV pathogenesis and liver cancer, as well as for clinicians aiming to better understand early disease progression. While further validation in more complex multicellular systems is needed, this platform can support the identification of HBx-targeted therapeutic strategies and guide the development of improved adult human derived models for virus-host interaction studies.

Background: Gut injury after pediatric cardiac surgery remains an ongoing challenge, resulting in increased morbidity and mortality for children with congenital heart disease (CHD) and a significant burden on the healthcare system. It remains unclear what the driving forces are that result in this pro-inflammatory state following pediatric cardiac surgery with cardiopulmonary bypass. Understanding key components involved in the gut composition, gut barrier function, and systemic inflammation in children with CHD after cardiac surgery is critical to improve outcomes. Methods: A prospective study of patients aged 0-5 years with CHD undergoing cardiac surgery (CPB group) or non-CHD undergoing non-cardiac surgery (Comparison group). We collected pre-operative and post-operative stool and plasma to evaluate the microbiome, metabolites, markers of gut barrier function, and inflammatory cytokines. Clinical variables were collected to evaluate markers of inflammation. These variables were compared between the two groups to evaluate signatures and develop unique biomarker profiles. Results: We enrolled 62 patients (CPB, n=46; Comp, n=16). CPB patients had increased pro-inflammatory microbiota and reduced diversity metrics pre-operatively, which were exacerbated post-operatively. The CPB group also had increased pro-inflammatory eicosanoids and reduced gut and heart protective short-chain fatty acids versus the Comparison group. The CPB group had increased pro-inflammatory and reduced anti-inflammatory cytokines post-operatively. The CPB group also had increased markers of gut barrier dysfunction versus the Comparison group. Mediation analysis showed the microbial functional shift was associated with increased PGE2 and reduced butyric acid in the CPB group, associated with increased cytokines and clinical markers of inflammation post-operatively. Conclusion: We demonstrate unique gut microbial and metabolites profiles associated with gut permeability and systemic inflammation in children with CHD undergoing cardiac surgery highlighting a unique microbiome-inflammation axis in this patient population. Further studies to evaluate causal links with these profiles will identify potential targets to improve outcomes for these patients.

The intestine plays a crucial role in physiology, nutrition, and immune function, but intestinal anatomy and cell types have yet to be fully characterized in many fish species, the most diverse group of vertebrates. To address this gap, we characterized the structure and composition of the intestine of threespine stickleback (Gasterosteus aculeatus), an emerging model teleost in biological research. Using histology, myeloperoxidase staining, single-cell RNA sequencing, and RNA in situ hybridization, we defined major intestinal epithelial, immune, stromal, and stem/progenitor populations. Goblet cells were abundant in proximal and hindgut, while myeloperoxidase-positive granulocytes were evenly distributed throughout the intestine. To facilitate future experimental studies of stickleback intestinal function, we also developed the first intestinal organoid culture from stickleback and show that these cultures recapitulate epithelial architecture and retain expression of canonical intestinal epithelial markers. This organoid platform enables future functional studies of mucosal immunity, host-microbe interactions, and intestinal physiology in stickleback and related teleosts. Together, our integrated approach provides a comprehensive cell atlas and a novel experimental model for studying digestive and immune functions in threespine stickleback.

Background: Pediatric chronic pancreatitis (CP) carries an elevated lifetime risk of pancreatic ductal adenocarcinoma (PDAC), yet the cellular and molecular mechanisms driving disease progression and early neoplastic transformation remain undefined. Methods: We performed single-nucleus RNA sequencing (snRNA-seq) on pancreatic tissue from 15 pediatric CP individuals and 6 healthy controls (HC). Findings were integrated with peripheral blood flow cytometry immunophenotyping of 8 CP and 7 HC individuals and validated by histopathological assessment. Findings: We identified 15 distinct cell populations and profound cellular remodeling in CP, including a 46% reduction in acinar cells and emergence of inflammatory fibroblasts as the dominant stromal population. Acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia (PanIN) populations bearing early PDAC-associated transcriptional signatures were detected in most CP samples. Cell-cell interaction analysis revealed that 68% of CP-specific ligand-receptor interactions converged on ADM and PanIN populations via ECM-integrin and inflammatory pathways. Peripheral blood flow cytometry demonstrated concordant systemic immune activation, including elevated monocyte CCR2 and CD80, increased CD69 on T cells, and upregulated ROR{gamma}t in regulatory T cells. Interpretation: This atlas defines the cellular landscape and intercellular signaling networks underlying pediatric CP, identifying inflammatory fibroblasts and early neoplastic cell states as central features. These findings provide a molecular foundation for understanding cancer risk in pediatric CP and provide a resource to prioritize studies into potential therapeutic targets and biomarkers. Funding: This work was supported by the Network for Pancreatic Organ donors with Diabetes (nPOD) and The Leona M. & Harry B. Helmsley Charitable Trust.

Wolman disease (WD), the severe infantile form of lysosomal acid lipase deficiency, is a rare metabolic disorder caused by inactivating mutations in the LIPA gene. Although WD is characterized by profound hepatic dysfunction, experimental human systems capable of modelling multicellular liver pathology and supporting therapeutic testing remain limited. Here, we generated an isogenic human model of WD by introducing LIPA loss-of-function mutations into induced pluripotent stem cells and differentiating them into multicellular human liver organoids (HLO). LIPA-deficient HLO preserved hepatic lineage specification while recapitulating key biochemical and cellular features of WD, including loss of LIPA activity, lysosomal expansion, lipid accumulation, and activation of inflammatory and fibrogenic programs. Single-cell RNA sequencing resolved cell-type-specific disease states across hepatocyte-, stromal-, and biliary-like populations, revealing the emergence of a reactive biliary program consistent with ductular reaction, a complex tissue response associated with chronic liver injury. Importantly, this reactive biliary phenotype was supported by targeted gene-expression analysis in WD liver organoids and independently validated in liver tissue from mouse models and WD patients. Isolated LIPA-deficient cholangiocyte organoids failed to reproduce the DR-associated program, indicating that this response depends on multicellular interactions within the hepatic microenvironment rather than on biliary cell-autonomous dysfunction alone. Consistently, hepatocyte-directed AAV-mediated restoration of LIPA expression attenuated metabolic stress, inflammatory and fibrogenic programs, and suppressed ductular reaction both in organoids and in vivo. Together, these findings establish multicellular human liver organoids as a physiologically relevant platform for modelling emergent tissue-level responses in WD and for evaluating therapeutic rescue strategies in a human context.

Aims: Serrated lesions contribute substantially to colorectal cancer (CRC), while routine management of small distal hyperplastic polyps (HPs) assumes low risk. Surveillance guidelines nevertheless incorporate uncertainty at the HP/SSL interface and recommend shortened intervals for large serrated lesions. We tested whether fibroblast activation protein-alpha; (FAPalpha) expression by stromal fibroblasts within expert-reviewed HPs stratifies risk of subsequent neoplasia. Methods and results: In a single centre historical cohort, FAPalpha; immunohistochemistry (Abcam ab53066, 1:200) was performed on FFPE colon tissues from 64 patients (normal colon n=10; HP n=39; low grade TA n=6; high-grade TA n=4; adenocarcinoma n=5). FAPalpha positive stromal fibroblasts were quantified in 20 randomly selected fields at magnification 1000 by two blinded readers (ICC 0.93). Among 39 patients with expert reviewed index HPs and colonoscopic follow up, the endpoint was metachronous adenoma occurring in the same general colonic area as the index HP, with proximal defined as ascending colon and distal as descending colon. Follow-up colonoscopies were scheduled every 2 years for up to 10 years. ROC analysis identified an optimal threshold of [≥]9 FAPalpha positive fibroblasts (AUC 0.8658; sensitivity 81.25%, specificity 87.93%). FAPalpha high status (44% of HPs) was associated with shortened neoplasm free survival (log-rank p=0.0012): five-year neoplasm free survival 41% versus 91% for FAPalpha; no/low. In multivariable Cox modelling, FAPalpha high status remained independently associated with metachronous adenoma (HR 4.5, 95% CI 1.2-16.8, p=0.022). Conclusion: FAPalpha+ fibroblasts in expert-reviewed colorectal HPs identify a high-risk subgroup for metachronous adenoma, supporting stromal activation markers as a feasible pathology-anchored stratification tool.

The intestinal epithelium is continuously subjected to a variety of mechanical forces, including extrinsic peristaltic contractions and intrinsic tensile forces generated by epithelial cell migration. Yet, how these mechanical cues influence the cellular processes underlying intestinal homeostasis remains poorly understood. In this study, we examine the impact of mechanical forces on intestinal cell dynamics by applying controlled external stretch to intestinal organoids, combined with high-throughput single-cell transcriptomic profiling. Our analyses reveal that prolonged cyclic mechanical strain alters the composition of differentiated intestinal cell populations. Specifically, we identify a strain-induced shift in the absorptive lineage towards a less mature state, with expansion of the population of early-stage enterocytes at the crypt-villus interface. This shift is associated with downregulation of transcriptional programs controlling enterocyte maturation within absorptive precursor populations. Our findings indicate that mechanical strain directs the maturation of the intestinal absorptive lineage, and highlight a role for mechanical forces in shaping intestinal epithelial composition and function.

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide despite recent therapeutic advances, driven in part by its marked etiological and molecular heterogeneity and the lack of broadly effective therapeutic targets. Identifying conserved tumor dependencies shared across distinct etiological backgrounds may provide new opportunities for targeted therapy. Here, we developed an integrative computational framework to systematically integrate transcriptomic, functional genomics, and clinical datasets for the identification and prioritization of candidate tumor dependency genes in liver cancer. We reanalyzed transcriptomic data from murine models of liver cancer driven by genotoxic (DEN), oncogenic (c-Myc), and inflammatory (lymphotoxin) stimuli, identifying more than 380 genes consistently upregulated across all tumor models. Functional enrichment analysis revealed a strong overrepresentation of cell cycle-related pathways and liver cancer signatures. Integration with DepMap dependency datasets identified 26 genes with strong dependency scores. Candidate genes were further prioritized by comparing their expression across models of liver regeneration, chronic liver injury, and liver cancer. Analysis of the TCGA-LIHC cohort confirmed significant overexpression of all 26 genes in human HCC, with high expression associated with poor patient survival. Together, these findings establish an integrative framework for identifying conserved tumor dependencies, providing a prioritized set of proliferation-associated genes for functional evaluation as therapeutic targets in HCC.

Objectives; The role of nuclear receptor subfamily 4, group A, member 3 (NR4A3) in hepatic steatosis, inflammation, and insulin resistance (IR) within the context of metabolic dysfunction-associated steatotic liver disease (MASLD) remains largely underexplored. Consequently, this study aimed to examine NR4A3's impact on MASLD and the potential underlying mechanisms. Methods; We aimed to elucidate the functional role of NR4A3 in MASLD through its knockdown in cell culture and animal models. To establish the cell culture model of MASLD, LO2 cells were treated with free fatty acids (FFAs), while male C57BL/6 mice were fed a high-fat diet (HFD) to create the animal model. NR4A3 knockdown was achieved using specific short hairpin RNA (NR4A3-shRNA) in the mice model and three small interfering RNAs (NR4A3-siRNAs) in the cell culture model. The lipids content, fatty acid synthesis, inflammatory factors, and IR were then assessed with and without NR4A3 knockdown. Furthermore, the underlying mechanism through which NR4A3 exerts its influence was explored by analyzing the interaction between NR4A3 and activating transcription factor 3 (ATF3). Results: In the cell culture experiments, the knockdown of NR4A3 significantly decreased the lipids content, fatty acid synthesis, and inflammatory factors in the LO2 cells treated with FFAs in the NR4A3-shRNA group compared with those in the NC-shRNA control group. In the animal model experiments, NR4A3 knockdown in the HFD male C57BL/6 mice significantly ameliorated HFD-induced hepatic steatosis, inflammation, and IR. Mechanistically, the knockdown of NR4A3 downregulated the expression and transcriptional activity of ATF3, resulting in an impaired ATF3 function. ATF3 overexpression significantly reversed lipid accumulation decline and reduced inflammation after NR4A3 knockdown. Conclusion: The downregulation of NR4A3 alleviates MASLD by modulating ATF3, suggesting this may be a promising therapeutic target.

Autoimmune hepatitis (AIH) is a chronic progressive liver disease that despite suggestive serum autoantibodies or plasma cell enrichment, remains functionally a diagnosis of exclusion. Whether the broader cellular composition of the liver might enable improved specificity of diagnosis has not been systematically tested. We prospectively recruited patients undergoing a clinically-indicated liver biopsy for suspected AIH and performed single-nucleus RNA sequencing (snRNA-seq) on biopsy tissue to map the cellular landscape of AIH and its diagnostic mimics. Unsupervised clustering on cell-type abundances alone largely separated AIH from non-AIH samples. Among individual populations, a subset of CD8 T-cells marked by high TOX and PD1 expression was the most discriminating feature: its enrichment perfectly distinguished AIH by both snRNA-seq and in situ density (AUC = 1.00), outperforming plasma cell abundance (AUC = 0.83). CD8TOX T-cell enrichment may therefore be the histologic lesion that marks the diagnosis of AIH.

Inflammatory bowel disease (IBD) burden is rising globally, yet only subsets of patients benefit from available therapies, underscoring the need for more precise molecular and cellular stratification. In the PREDICT study, we enrolled treatment-naive pediatric patients with IBD, alongside disorders of gut-brain interaction (DGBI) controls and healthy donors, and profiled their intestinal and blood-derived T cells using single-cell RNA sequencing (scRNA-seq). Across 107 participants, we identify a unique population of cytotoxic CD4+ T cells (CD4 CTL) enriched in the inflamed gut of patients with Crohn's disease (CD) and ulcerative colitis. CD4 CTLs are clonally expanded and express cytotoxic effector molecules and IFNG, consistent with antigen-driven activation. Cell-cell interaction analyses implicate macrophage-derived IL-27 as the top candidate for CD4 CTL differentiation, and IL-27 blockade in a mouse model limits CD4 CTL formation. Notably, elevated CD4 CTL frequencies in gut and peripheral blood at diagnosis are associated with subsequent poor outcome of anti-TNF therapy in pediatric CD. Findings in our identification cohort are validated in an independent cohort and through reanalysis of published datasets. Importantly, we designed a simple flow cytometry panel to isolate blood CD4+ CXCR6+ CD27- T cells, which displayed a CD4 CTL transcriptional phenotype. Together, our results link CD4 CTLs to anti-TNF nonresponse and support their potential as an early, blood-accessible biomarker for treatment stratification in pediatric CD.

Hirschsprung disease (HSCR) is a rare congenital disorder of the enteric nervous system (ENS), marked by the absence of enteric ganglia along variable lengths of the distal gastrointestinal tract, resulting in functional intestinal obstruction. Individuals with Trisomy 21 (Down syndrome) face a 50- to 100-fold increased risk of HSCR relative to the general population, yet the molecular basis of this susceptibility remains poorly understood. Here, we investigated this association using isogenic induced pluripotent stem cells (iPSCs) derived from a mosaic individual with Down syndrome, enabling direct comparison of Trisomy 21 and Disomy 21 cells within an identical genetic background following differentiation into enteric neural crest-derived cells (ENCDCs). Trisomy 21 ENCDCs exhibited reduced proliferative and migratory capacity and an impaired ability to differentiate into enteric neurons relative to Disomy 21 controls. These phenotypes were accompanied by decreased RET expression at both the transcript and protein levels, together with broad downregulation of the RET gene regulatory network, including GDNF, GFRA1, EDNRB, SEMA3C, and NRG1, and of cell cycle and DNA replication pathways. Strikingly, we identified SOD1, a chromosome 21-encoded antioxidant enzyme not previously linked to RET regulation, as a dosage-sensitive driver of this effect: SOD1 overexpression in disomic ENCDCs was sufficient to suppress RET, whereas shRNA-mediated knockdown in Trisomy 21 ENCDCs restored RET expression. Mechanistically, Trisomy 21 ENCDCs displayed markedly elevated catalase and a redox imbalance, and exogenous hydrogen peroxide recapitulated RET suppression in disomic cells, implicating oxidative stress as a mediator of RET downregulation. Collectively, these findings establish Trisomy 21 dosage effects as disruptors of RET-dependent enteric neural crest development and implicate SOD1-driven oxidative stress as a candidate mechanism, providing a framework for understanding the elevated risk of HSCR in Down syndrome.

BACKGROUND: Perfluorooctane sulfonate (PFOS) is a widely distributed persistent organic pollutant in the environment and has been associated with an increased risk of atherosclerosis. However, the underlying pathogenic mechanisms remain largely unclear. This study aimed to investigate the effects of PFOS on atherosclerosis and its associated gut-vascular axis. METHODS: Pseudo-germ-free mouse models and fecal microbiota transplantation (FMT) were used to determine the role of the gut microbiota in PFOS-induced atherosclerosis. Metagenomic sequencing was performed to characterize alterations in gut microbial composition following PFOS exposure, and targeted metabolomics was used to assess bile acid profiles in the ileum and plasma. Transcriptomic analysis of Bacteroides caecimuris (B.caecimuris) was conducted to explore the reasons for the increased abundance of B.caecimuris after PFOS exposure. In addition, intestinal transcriptomics and ChIP-qPCR were performed to validate transcriptional regulation within the FXR-TLR3 signaling axis. RESULTS: Among 127 participants with paired serum and fecal samples, including 82 patients undergoing coronary angiography with Gensini scores (GS score), fecal PFOS levels were significantly associated with lipid profiles and GS score, whereas serum PFOS showed no such association. Mechanistically, PFOS exposure promotes intestinal enrichment of B. caecimuris by upregulating its tolC gene, thereby enhancing efflux capacity. This microbial shift was accompanied by reduced levels of tauro-ursodeoxycholic acid (TUDCA) and aberrant activation of intestinal FXR signaling. Further analyses demonstrated that FXR activation upregulated TLR3 expression and promoted inflammatory responses and atherosclerosis progression via the TLR3-NF-{kappa}B signaling axis. Both intestinal epithelial-specific FXR deficiency (Fxr{Delta}IE) and TUDCA supplementation significantly suppressed pathway activation and alleviated disease phenotypes.Functional experiments identified TLR3 as a key downstream effector of FXR. Overexpression of TLR3 abolished the protective effects observed in Fxr{Delta}IE mice. Moreover, pharmacological inhibition of TLR3 using CU CPT-4a significantly improved established atherosclerotic lesions in vivo. CONCLUSIONS: This study identifies a gut microbiota-driven FXR-TLR3 signaling axis that mediates PFOS-induced atherosclerosis. These findings provide new mechanistic insights into environmentally induced cardiovascular disease and suggest potential targets for risk assessment and therapeutic intervention.

Ulcerative colitis (UC) is a chronic inflammatory disease characterized by colonic inflammation and bloody diarrhoea. Accumulating evidence suggests that UC not only affects the intestinal tract, but also distant organs including the brain. Environmental factors are key determinants of the disease course, yet the impact and potential disease modifying effects of living environment complexity on microbiota-gut-brain axis signalling during colitis remain unclear. To address this gap, we investigated how enhanced environmental complexity (EC) affects the disease course and gut-brain axis signalling during experimental colitis in mice. Our results show that EC exacerbates dextran sulphate sodium (DSS)-induced colitis in female mice, but not in male mice, as evidenced by greater weight loss and higher disease activity. Immune cell profiling across the gut-brain axis reveals strong effects of DSS treatment on colonic, circulating and brain immune cell populations and a restriction of central nervous system (CNS) T cell infiltration due to EC. In addition, female EC/DSS mice have higher circulating corticosterone levels than controls indicating chronic stress. Metabolomics across the gut-brain axis revealed that EC exacerbates colitis-induced metabolite perturbations in plasma, brain tissue, brain interstitial and cerebrospinal fluid. Notably, microbiota-derived metabolites, including deoxycholic acid and trimethylamine-N-oxide (TMAO), are increased in EC/DSS mice, concordant with EC-associated microbiome changes and anxiety-like behaviour. Overall, this study indicates that EC worsens experimental colitis in female mice and directs microbiota-gut-brain axis signalling during colitis towards a less favourable state. From a translational perspective, this study highlights the importance of environmental factors for a sex-specific disease course of UC and associated neurobehavioral comorbidities.

Thymosin {beta}4 (T{beta}4) is a conserved acidic polypeptide with 43-amino acids participating in multiple pathophysiological processes. In this study in vivo effects of T{beta}4 on liver regeneration are investigated in carbon-tetrachloride (CCL4) induced rodent animal liver jury models. Results illustrate that exogenous T{beta}4 treatment significantly reduced CCL4-rendered liver necrosis around central vein. At 48 hours after CCL4 insults hepatocytes proliferation occur mainly around the periportal area, while hepatocytes proliferation around the necrosis area is prominently increased by exogenous T{beta}4 treatment. The holistic proliferation level of liver tissues are also enhanced by exogenous T{beta}4. Hepatocyte proliferation activities negatively correlate with the necrosis extent of the liver tissue. These results suggested firstly exogenous T{beta}4 treatment could enhance liver regeneration and exhibit prosperous potential for application in clinical conditions such as liver transplantation.

Introduction. TAC/SARIFA has been introduced as a new robust and easy-to-evaluate biomarker in several cancer entities, including colorectal cancer. It is defined by direct contact between at least five tumour cells and one adipocyte and is believed to indicate metabolic reprogramming associated with adverse outcome. However, the mechanism that leads to TAC/SARIFA positivity remains unclear. To investigate whether there is an individual component, we conducted a study on double and triple cancers, establishing a within patient design. Methods. We retrospectively analysed a total of 135 cases with 276 colorectal cancers from two academic medical centres. The TAC/SARIFA status was evaluated, as were the basic histopathological factors. The median follow-up time was 120 months. Results. Cases with any TAC/SARIFA positive tumours showed significantly reduced overall survival (62 vs. 88 months; p = 0.011). Analysing the entire cohort, the rates of concordant and discordant cases followed a random distribution. However, restricting the analysis to synchronous pT3/4 cases revealed a significant deviation from a random distribution (p = 0.016). Conclusion. This study reveals significant concordance of TAC/SARIFA status in synchronous locally advanced colorectal double/triple carcinomas, supporting the concept that tumour adipocyte interaction reflects a host related microenvironmental condition linked to metabolic reprogramming rather than a purely tumour intrinsic event.

Cyclooxygenase-1 (COX-1) is classically regarded as a constitutive enzyme that produces eicosanoids with housekeeping functions, but recent evidence indicates that it may also be involved in the acute phase of severe systemic inflammation. There is evidence indicating that COX-1 is selectively activated in the spleen via post-translational mechanisms early the course of LPS-induced systemic inflammation. However, the mechanistic link between COX-1 and the spleen has not yet been demonstrated in direct experiments. The present study was conducted to fill this gap. The effects of the COX-1 inhibitor SC-560 on the LPS-induced severity triad (hypotension, hypothermia and acidosis) were evaluated in rats subjected to splenectomy or in sham-operated controls. In the sham-operated group, SC-560 significantly attenuated the severity triad independently of changes in plasma cytokines (TNF and IL-1{beta}). In the splenectomized rats, SC-560 completely lost its ability to attenuate the hypotension and the acidosis induced by LPS. The effect of SC-560 on LPS-induced hypothermia was also impaired by splenectomy, though not completely. We then conducted a lipidomic screening to identify which COX-1-derived eicosanoids might be responsible for mediating the severity triad. Based on spleen-blood correlations, the screening identified PGE2 and PGD2 as putative candidates. In conclusion, the present study provides direct evidence for a mechanistic link between the spleen and COX-1 in the mediation of severity in systemic inflammation, and identifies PGE2 and PGD2 as putative candidates involved.