Gastro Hep Advances

BackgroundUlcerative colitis (UC) represents a global health challenge characterized by relapsing inflammation and epithelial barrier disruption. Conventional immunosuppressive therapies have reached their therapeutic ceiling, with mucosal healing and long-term remission remaining unmet therapeutic goals for many patients. Organoid-based regenerative therapy offers a new paradigm by reconstructing damaged mucosa rather than merely controlling inflammation. MethodsWe hypothesized that fragmented intestinal organoids, building upon the foundational model established by Yui et al., whose use of immunodeficient Rag2-/- mice and surgical mucosal injury first demonstrated the feasibility of colon organoid transplantation. Our study advances this framework by introducing optimized transplantation timing and employing immunocompetent C57BL/6 mice to refine translational relevance and clinical feasibility, thereby extending the applicability of organoid therapy to more realistic physiological contexts., when transplanted rectally at an optimized time point, could integrate more efficiently into inflamed mucosa and accelerate epithelial regeneration even in an immunocompetent environment. A 2.5% dextran sulfate sodium (DSS)-induced colitis model was established in C57BL/6 mice. Intestinal organoids and crypts derived from EGFP-transgenic donors were cultured and transplanted rectally using a minimally invasive delivery system. Fluorescence microscopy, histological analysis, and clinical indices were used to evaluate engraftment and mucosal repair. ResultsEGFP+ organoid fragments and crypts successfully engrafted at ulcerated sites, reconstituting epithelial structures and restoring mucosal integrity. Mice receiving organoid or crypts transplantation exhibited rapid weight recovery and reduced bleeding compared to DSS-only controls. Histological and fluorescence analyses confirmed epithelial restitution exceeding 60% by day 7 post-administration versus 18% in controls. These results validate the regenerative potential of organoid transplantation within an immunocompetent host. ConclusionThis study demonstrates that rectal transplantation of fragmented intestinal organoids and crypts promotes robust mucosal regeneration in DSS-induced colitis. By optimizing transplantation timing and employing a clinically relevant model, our work establishes a translational foundation for organoid-based regenerative therapies targeting inflammatory bowel diseases.

Metabolic dysfunction-associated steatotic liver disease (MASLD), driven by obesity and metabolic syndrome, is increasingly prevalent and a significant contributor to liver fibrosis, cirrhosis, and liver-related mortality. Emerging research implicates the gut microbiome as a critical player in MASLD progression, yet specific microbial drivers remain poorly understood. Here, we explore the role of Prevotella copri (P. copri) in MASLD progression through both human patient cohorts and a mouse model of diet-induced obesity. Using 16S rRNA sequencing, we identified elevated P. copri abundance in MASLD patients with advanced fibrosis, linked with significant shifts in microbial diversity and bacterial network connectivity. To investigate causality, experimental colonization of P. copri in mice on a high-fat diet worsened MASLD progression, with P. copri-colonized mice showing significant increases in hepatic steatosis, liver triglyceride accumulation, and body weight, independent of caloric intake. At the molecular level, P. copri colonization downregulated key lipid metabolism genes, such as Carnitine Palmitoyltransferase 1, Diacylglycerol Acyltransferase, and Adipose Triglyceride Lipase, and impaired tight intestinal junction integrity through the downregulation of cluadins, occludin, and zonula occludens-1. Collectively, our findings position P. copri as a possible driver of MASLD progression by promoting hepatic steatosis through lipid and triglyceride accumulation and fibrosis through decreased tight junction integrity. These insights suggest a promising therapeutic avenue to target specific microbial signatures like P. copri to curb MASLD progression and mitigate the associated risk of advanced fibrosis.

Epithelial metaplasia is a common adaptation to chronic inflammatory processes and can be associated with increased risk of dysplasia and cancer. The distal colon of patients with inflammatory bowel disease (IBD) commonly shows crypt architectural distortion and Paneth cell metaplasia (PCM), and IBD patients also carry increased risk of colitis-associated dysplasia and cancer (CAC). Loss of SATB2 expression (Special AT-rich binding 2 protein, a colon-restricted chromatin remodeler) has recently been shown to distinguish colitis-associated dysplasia and CAC from sporadic disease. Here we report non-diffuse heterogeneous patterns of SATB2 loss across non-dysplastic distal colon biopsies from IBD patients (n=20). This cohort was specifically curated to include biopsies with well-developed histologic features of villiform growth and PCM. Notably, CDX2 was strongly expressed and P53 showed a wild-type immunolabeling pattern across our non-dysplastic cohort, regardless of SATB2 immunolabeling pattern. Our findings fit with recent murine studies in which colon-specific Satb2 deletion resulted in histologic conversion of colonic mucosa to small intestinal-like mucosa, including emergence of villi and Paneth cells. Taken together, we show that SATB2 loss is associated with a preneoplastic metaplastic response to chronic injury in human IBD and chronic colitis, reframing PCM more broadly as small intestinal metaplasia. We propose that inflammation-associated SATB2 loss mediates a remodeled chromatin landscape permissive for dysplasia and CAC.

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.

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.

Background & AimsPrimary sclerosing cholangitis (PSC) is a progressive cholangiopathy characterized by ductular remodeling, inflammation, and periportal fibrosis, for which effective medical therapies remain limited. The Hippo pathway effector TEAD1 has been implicated in liver regeneration and fibrogenesis; however, its role in cholestatic injury remains poorly defined. We investigated whether hepatocyte TEAD1 regulates injury-associated remodeling in a PSC-mimicking model and whether this mechanism is conserved in human PSC liver. MethodsHepatocyte-specific TEAD1 knockout mice (Alb-TEAD1-/-) and littermate controls were subjected to DDC-induced cholestatic injury. Ductular reaction, fibrosis, inflammation, and bile acid-related gene programs were assessed by histology, immunostaining, and gene expression analyses. Translational relevance was evaluated using bulk and single-cell transcriptomic datasets from human PSC liver. ResultsHepatocyte TEAD1 deletion attenuated DDC-induced fibrosis, ductular expansion, and inflammatory cell accumulation, while preserving hepatocyte proliferative responses. TEAD1-deficient livers exhibited reduced expression of profibrotic mediators, including Spp1, Ctgf, and Cyr61, with decreased extracellular matrix deposition. In contrast, canonical transcriptional adaptations to cholestatic stress, including suppression of bile acid uptake, induction of efflux pathways, and repression of bile acid synthesis genes, were preserved in the absence of TEAD1. Analysis of human PSC datasets demonstrated coordinated upregulation of TEAD1 and TEAD-associated target genes. Single-cell transcriptomic analysis further revealed hepatocyte-enriched TEAD1 expression and activation of a TEAD1 target gene program across all hepatic zones in PSC, with effect sizes exceeding those observed in non-parenchymal populations. TEAD1 activation was accompanied by co-expression of profibrotic mediators and downregulation of hepatocyte differentiation markers, consistent with a maladaptive hepatocyte state. ConclusionsHepatocyte TEAD1 drives ductular, inflammatory, and fibrogenic remodeling during cholestatic injury without disrupting bile acid metabolic adaptation. These findings identify TEAD1 as a hepatocyte-intrinsic regulator of epithelial-stromal crosstalk and establish conserved activation of this pathway in human PSC, supporting TEAD-directed signaling as a therapeutic target.

Pancreatitis is a potentially fatal and difficult to control exocrine-tissue defect with no FDA approved therapies. Variants of a chloride/bicarbonate transporter cystic fibrosis transmembrane conductance regulator (CFTR) pose multi-fold increased risk of pancreatitis accounting for up to 40% of the patients with idiopathic pancreatitis. However, the relationship between the duct-restricted CFTR-function and total exocrine tissue defect during pancreatitis remains less known and animal models do not translate well to human disease. To overcome this challenge, we developed a robust and highly durable iPSC-derived model system of pancreatic ductal tissues from an idiopathic pancreatitis patient with a common pancreatitis-associated CFTR variant. In the patient line termed PANx, we found deficient CFTR function and a distinct gene expression signature for ductal tissue pancreatitis marked by aberrant mucin production, inflammatory cytokines and cystic neoplasms. By applying clinically used CFTR-modulator drug ivacaftor, we observed a remarkable restoration of deficient CFTR-mediated fluid secretion as well as upto 40% reversal of the differential gene signature for PANx including the reduction in mucinous neoplasms and immunogenic cytokines such as IL-11, CCL20 and CXCL8. We further employed a microsystem device to model hyperamylasemia, a diagnostic feature of acute pancreatitis attack, due to a ductal reaction causing acinar injury. The key mucinous signature was validated in primary pancreatitis ductal tissues with a CFTR variant. Overall, we unraveled new layers of CFTR-related pathology in pancreatitis to help us better understand the early course of this debilitating condition. The test methods and model systems discovered in this study will significantly expedite the discovery of diagnostic and therapeutic tools for treating idiopathic pancreatitis. For the first time, we provided molecular and physiologic evidence supporting the benefit of CFTR modulator drug ivacaftor in human CFTR-related pancreatitis.

Background & AimsExclusive enteral nutrition (EEN) is used to treat pediatric Crohns disease (CD), but therapeutic benefits are not long lasting. Due to reported lower efficacy EEN is not routinely used to treat pediatric ulcerative colitis (UC). Inulin-type fructans (IN) beneficially modulate the gut microbiome and promote expansion of anti-inflammatory immune cells. We hypothesized that enriching EEN with IN (EENIN) would enhance treatment efficacy. To test this, we examined the effects of EEN-IN on colitis development, the gut microbiome and CD4+ T cells using an adoptive T cell transfer model of colitis. MethodsTCR-{beta} deficient mice were randomized to one of four groups: 1) Control, 2) Chow, 3) EEN and 4) EEN-IN, and naive CD4+ T cells were adoptively transferred into groups 2-4, after which mice were monitored for 5-weeks prior to experimental endpoint. ResultsMice fed EEN-IN showed greater colitis protection, with colonic shortening, goblet cell and crypt density loss reduced over that of EEN fed mice and reduced disease activity and immune cell infiltration compared to chow fed mice, and less crypt hyperplasia and higher survival compared to both groups. EENIN mice maintained colonic mucus layer thickness and had increased levels of Foxp3+IL-10+ and Ror{gamma}t+IL- 22+ and reduced levels of Tbet+IFN{gamma}+ and Tbet+TNF+ CD4+ T cells. EEN-IN also lead to higher butyrate, Bifidobacterium spp. and Bacteroides spp. concentrations. ConclusionThe EEN-IN group showed reduced colitis development as compared to the chow and EEN groups. This highlights the potential benefits of EEN-IN as a novel induction therapy for pediatric CD and UC patients. SynopsisWe demonstrated that inulin-type fructan enriched exclusive enteral nutrition formula reduced colitis development likely due to butyrate-dependent pathways that helped preserve the mucus layer and promote an anti-inflammatory intestinal environment via expansion of regulatory T cells.

Intestinal mucins play a crucial role in the mucosal barrier, serving as the bodys initial defense against microorganisms. However, how the host regulates the secretion and glycosylation of these mucins in response to bacterial invasion remains unclear. Our study demonstrates that when exposed to Streptococcus gallolyticus (SGG), a gut pathobiont, the host mucosa promptly adjusts the behavior of specialized goblet cells (GCs) located in the middle of the crypts. A subset of these cells undergoes a transformation, becoming intercrypt goblet cells (icGCs), which do not detach from the surface but instead migrate along intercrypt spaces while secreting mucins. These mucins form a dense layer covering the epithelial cell surface and filling the gaps between mucus plumes secreted from crypt openings, thereby forming a continuous protective mucus layer. Notably, the mucins produced by icGCs exhibit a distinct glycosylation pattern that makes them impermeable to bacterial pathogens. Significantly, a non-piliated SGG mutant unable to bind to mucus fail to induce icGCs, allowing its translocation through the mucosa and submucosa. Intriguingly, a closely related mucus-adherent bacterium, SGM, which is considered non-pathogenic, also triggers the differentiation of GCs into icGCs. This discovery opens new avenues for treating patients with intestinal diseases characterized by mucus layer deficiencies, such as inflammatory bowel diseases and metabolic disorders. Utilizing mucus-adherent probiotics to induce icGCs represents a promising strategy for reinforcing the mucosal barrier. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/601821v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@e8e11org.highwire.dtl.DTLVardef@19116bdorg.highwire.dtl.DTLVardef@6bd839org.highwire.dtl.DTLVardef@40b8aa_HPS_FORMAT_FIGEXP M_FIG C_FIG In briefWe demonstrate here that, upon oral infection by a gut pathobiont, namely Streptococcus gallolyticus, the murine intestinal mucosa displays a novel type of goblet cells recently described as intercrypt goblet cells (icGCs). These icGCs are not shed at the surface of epithelial cells, in contrast to differentiated goblet cells, and produce a continuous protective mucus layer, with a specific pattern of glycosylation rendering it impenetrable to bacteria. No icGCs were induced in response to a non-mucus binding SGG mutant, thus allowing bacterial translocation into the mucosa and submucosa, highlighting the essential role played by icGCs in the protective mucus barrier function. Importantly, SGM, a commensal mucus-adherent bacterium recognized as safe, is also able to stimulate production of icGCs, opening avenues in the treatment of patients with a "leaky gut". HighlightsO_LIInduction of intercrypt goblet cells in murine intestinal tract upon bacterial infection C_LIO_LIicGC potentially arise from differentiated goblet cells through cellular plasticity C_LIO_LIMucus produced by icGCs is critical for host defense and mucosal barrier function C_LIO_LICommensal mucus-adherent bacteria also induce icGCs, paving the way for new probiotic treatments for strengthening the mucosal barrier of patients with inflammatory bowel diseases and metabolic disorders C_LI

Background & AimsPancreatic ductal adenocarcinoma (PDAC) can develop from precursor lesions, including pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). Previous studies indicated that loss of Acvr1b accelerates the Kras-mediated development of papillary IPMN in the mouse pancreas, however, the cell type predominantly affected by these genetic changes remains unclear. MethodsWe investigated the contribution of cellular origin by inducing IPMN associated mutations-KRASG12D expression and Acvr1b loss - specifically in acinar (Ptf1aCreER;KrasLSL-G12D;Acvr1bfl/flmice) or ductal (Sox9CreER;KrasLSL- G12D;Acvr1bfl/flmice) cells in mice. We then performed MRI imaging and a thorough histopathological analysis of their pancreatic tissues. ResultsThe loss of Acvr1b increased the development of PanIN and IPMN-like lesions when either acinar and ductal cells expressed a Kras mutation. MRI, immunohistochemistry and histology revealed large IPMN-like lesions in these mice that exhibited features of flat, gastric epithelium. In addition, cyst formation in both mouse models was accompanied by chronic pancreatitis. Experimental acute pancreatitis accelerated the development of large mucinous cysts and PanIN when acinar, but not ductal, cells expressed mutant Kras and lost Acvr1b. ConclusionThese findings indicate that loss of Acvr1b in the presence of the Kras oncogene promotes the development of large and small precancerous lesions from both ductal and acinar cells. However, the IPMN-like phenotype was not equivalent to that observed when these mutations were made in all pancreatic cells during development. Our study underscores the significance of the cellular context in the initiation and progression of precursor lesions from exocrine cells.

Barretts esophagus, a metaplastic condition that originates in the distal esophagus, is the only known precursor lesion for the development of esophageal adenocarcinoma, which has a devasting 5-year survival rate of <20%. The large number of subjects diagnosed with Barretts esophagus, and therefore at higher risk for esophageal adenocarcinoma, underscores the necessity for biomarkers that would benefit surveillance and potentially early treatment. To address this, we generated epithelial stem cell organoids from normal gastric cardia, non-dysplastic and dysplastic Barretts esophagus, and esophageal and gastric adenocarcinoma. Interestingly, non-dysplastic and dysplastic Barretts esophagus displayed higher expression of multiple archetypical cancer-associated genes compared with both esophageal and gastric adenocarcinoma in addition to expression of the novel biomarker CT83. ST6GAL1, a Golgi sialyltransferase upregulated in multiple epithelioid cancers, was strongly upregulated in dysplastic Barretts esophagus at both mRNA and protein levels. ST6GAL1 protein also was highly expressed in esophageal adenocarcinoma, suggesting that regulation of ST6GAL1 may play a role in Barretts esophagus progression to esophageal adenocarcinoma and serve as a potential biomarker of the development of esophageal cancer.

Background and AimsEpithelial permeability barrier dysfunction is a central pathogenic driver of Crohns disease (CD), fueling microbial translocation, chronic inflammation, and progressive tissue injury. While current therapies suppress inflammation, none directly restore epithelial barrier function. Importantly, in CD patients, permeability barrier healing (BH) rather than mucosal healing is associated with long-term remission and a reduced risk of disease complications. Yet BH remains an unaddressed therapeutic target in CD. Here, we investigated whether pharmacologic inhibition of the integrated stress response (ISR) and RIPK3-mediated necroptosis, two convergent pathways of epithelial injury, can promote epithelial viability, regeneration, and barrier integrity in CD. MethodsWe employed villin-1/gelsolin double knockout (DKO) mice with epithelial-intrinsic ISR activation, TNF{Delta}ARE/+ mice with chronic inflammation, and CD patient-derived enteroids (PDEs). Animals and PDE were treated with ISR inhibitor ISRIB, RIPK3 inhibitor Necrostatin-1 (Nec-1), or FDA-approved cancer drugs pazopanib and ponatinib, repurposed as potent RIPK3 inhibitors. Epithelial survival, regenerative growth (enteroid formation, budding), and barrier function (transepithelial electrical resistance, TEER) were assessed. ResultsChronic ISR activation and necroptosis were prominent in both murine models and CD PDEs, causing epithelial death, Paneth cell expansion, impaired enteroid survival, and regenerative failure. Pharmacologic inhibition with ISRIB, Nec-1, pazopanib, or ponatinib restored villus architecture, reduced inflammation, enhanced epithelial survival and regeneration, and significantly improved TEER. ConclusionsISR activation and RIPK3-mediated necroptosis converge to drive epithelial injury and barrier dysfunction in CD. Repurposing pazopanib and ponatinib restored epithelial regeneration and BH, offering an immediately translatable therapeutic strategy for sustained remission in CD. SynopsisISR activation and RIPK3-mediated necroptosis drive epithelial injury in Crohns disease. Repurposed RIPK3 inhibitors, pazopanib and ponatinib, restore epithelial homeostasis and permeability barrier function, providing a translational strategy to achieve sustained remission in CD.

ObjectivesThe pathogenesis of pancreas cancer (PDAC) remains poorly understood, hindering efforts to develop a more effective therapy for PDAC. Recent discoveries show the aryl hydrocarbon receptor (AHR) plays a crucial role in the pathogenesis of several cancers, and can be targeted for therapeutic effect. However, its involvement in PDAC remains unclear. Therefore, we evaluated the role of AHR in the development of PDAC in vivo. MethodsWe created a global AHR-null, mutant Kras-driven PDAC mouse model (A-/-KC) and evaluated the changes in PDAC precursor lesion formation (Pan-IN 1, 2, and 3) and associated fibro-inflammation between KC and A-/-KC at 5 months of age. We then examined the changes in the immune microenvironment followed by single-cell RNA-sequencing analysis to evaluate concomitant transcriptomic changes. ResultsWe found a significant increase in PanIN-1 lesion formation and PanIN-1 associated fibro-inflammatory infiltrate in A-/-KC vs KC mice. This was associated with significant changes in the adaptive immune system, particularly a decrease in the CD4+/CD8+ T-cell ratio, as well as a decrease in the T-regulatory/Th17 T-cell ratio suggesting unregulated inflammation. ConclusionThese findings show the loss of AHR results in heightened Kras-induced PanIN formation, through modulation of immune cells within the pancreatic tumor microenvironment.

Background and AimsParkinsons disease (PD) is an age-related neurodegenerative disorder characterised by classical motor symptoms due to a loss of dopaminergic neurons in the substantia nigra pars compacta. The type-I interferons (IFNs) are elevated in the aging brain and we have implicated them in the neuroinflammatory response in PD. With increasing evidence of gastrointestinal (GI) dysfunction in PD patients, this study explored the contribution of the type-I IFNs to the transmission of pathology from the brain to the gut in PD. MethodsYoung (10-12 weeks) and aged (40-50 weeks) wildtype and IFNAR1-/- mice received an intrastriatal injection of human alpha-synuclein (-Syn) pre-formed fibrils (PFF) (8ug) with gut tissue analysed 6-months post-injection (p.i). A mouse intestinal organoid culture model was established to further characterise the -Syn induced inflammatory response in the gut. ResultsAn intrastriatal injection of human -Syn PFFs was shown to initiate a type-I IFN-dependent neuroinflammatory response in the GI tract of wildtype mice at 6-months p.i. This response was attributed to an elevation in type-I IFN signalling in aged mice that was absent in the IFNAR1-/- mice. Mouse intestinal organoid cultures confirmed -Syn was taken up by the enteroendocrine cells (EECs) to induce a type-I IFN mediated pro-inflammatory response that was attenuated in IFNAR1-/- cultures. ConclusionThis study has confirmed the type-I IFNs modulate the -Syn PFF induced inflammatory response within the gut potentiating pathology progression along the gut-brain axis. Early intervention of this type-I IFN response may be a potential therapeutic target to limit the progression of PD.

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.

Background and aimsThe immunosuppressive T regulatory cells (Tregs) regulate immune responses and maintain immune homeostasis, yet their functions in nonalcoholic fatty liver disease (NAFLD) pathogenesis remains controversial. MethodsMice were fed a normal diet (ND) or a western diet (WD) for 16 weeks to induce NAFLD. Diphtheria toxin injection to deplete Tregs in Foxp3DTR mice or Treg induction therapy in WT mice to augment Treg numbers was initiated at twelve and eight weeks, respectively. Liver tissues from mice and NASH human subjects were analyzed by histology, confocal imaging, and qRT-PCR. ResultsWD triggered accumulation of adaptive immune cells, including Tregs and effector T cells, within the liver parenchyma. This pattern was also observed in NASH patients, where an increase in intrahepatic Tregs was noted. In the absence of adaptive immune cells in Rag1 KO mice, WD promoted accumulation of intrahepatic neutrophils and macrophages and exacerbated hepatic inflammation and fibrosis. Similarly, targeted Treg depletion exacerbated WD-induced hepatic inflammation and fibrosis. In Treg-depleted mice, hepatic injury was associated with increased accumulation of neutrophils, macrophages, and activated T cells within the liver. Conversely, induction of Tregs using recombinant IL2/IL2 mAb cocktail reduced hepatic steatosis, inflammation, and fibrosis in WD-fed mice. Analysis of intrahepatic Tregs from WD-fed mice revealed a phenotypic signature of impaired Treg function in NAFLD. Ex vivo functional studies showed that glucose and palmitate, but not fructose, impaired the immunosuppressive ability of Treg cells. ConclusionsOur findings indicate that the liver microenvironment in NAFLD impairs ability of Tregs to suppress effector immune cell activation, thus perpetuating chronic inflammation and driving NAFLD progression. These data suggest that targeted approaches aimed at restoring Treg function may represent a potential therapeutic strategy for treating NAFLD. Lay summaryIn this study, we elucidate the mechanisms contributing to the perpetuation of chronic hepatic inflammation in nonalcoholic fatty liver disease (NAFLD). We show that dietary sugar and fatty acids promote chronic hepatic inflammation in NAFLD by impairing immunosuppressive function of regulatory T cells. Finally, our preclinical data suggest that targeted approaches aimed at restoring T regulatory cell function have the potential to treat NAFLD.

Mucosal healing following inflammatory injury is poorly understood and often neglected, despite being the best indicator of long-term outcomes in inflammatory bowel diseases. We report here that the enigmatic small molecular weight heat shock protein, Hsp25 (the human form is Hsp27), plays a vital role in converging microbial and host factors to promote pSTAT3-mediated mucosal healing. In wild type mice, the proximal-to-distal gradient of intestinal epithelial cell (IEC) Hsp25 expression is dependent on microbial cues. Patients with left-sided ulcerative colitis, however, show reduced levels of Hsp27 expression in both uninvolved and involved areas compared to normal colons of non-IBD patients. In mice with global or IEC-specific Hsp25 gene-targeted deletion, impaired mucosal healing with development of hallmarks of chronic disease are observed following DSS-induced or TNBS-induced colitis, whereas mucosal restitution is accelerated in IEC-specific overexpressing Hsp25 transgenic mice. In colonic IECs derived from these murine lines, Hsp25 binds and stabilizes a phospho-STAT3/YAP nuclear complex stimulated by IL-22 to sustain its wound healing gene programming. Thus, our findings provide insight into the mechanism of action of IEC Hsp25/27 in integrating host and microbial drivers of mucosal restitution, which can be leveraged to develop novel approaches for achieving and maintaining remission in complex immune disorders like IBD.

Background and AimsWe previously identified small molecules predicted to reverse an ileal gene signature for future Crohns Disease (CD) strictures. Here we used a new human intestinal organoid (HIO) model system containing macrophages to test a lead candidate, eicosatetraynoic acid (ETYA). MethodsInduced pluripotent stem cell lines (iPSC) were derived from CD patients and differentiated into macrophages and HIOs. Macrophages and macrophage:HIO co-cultures were exposed to lipopolysaccharide (LPS) with and without ETYA pre-treatment. Cytospin and flow cytometry characterized macrophage morphology and activation markers, and RNA sequencing defined the global pattern of macrophage gene expression. TaqMan Low Density Array, Luminex multiplex assay, immunohistologic staining, and sirius red polarized light microscopy were performed to measure macrophage cytokine production and HIO pro-fibrotic gene expression and collagen content. ResultsiPSC-derived macrophages exhibited morphology similar to primary macrophages and expressed inflammatory macrophage cell surface markers including CD64 and CD68. LPS-stimulated macrophages expressed a global pattern of gene expression enriched in CD ileal inflammatory macrophages and matrisome secreted products, and produced cytokines and chemokines including CCL2, IL1B, and OSM implicated in refractory disease. ETYA suppressed CD64 abundance and pro-fibrotic gene expression pathways in LPS stimulated macrophages. Co-culture of LPS-primed macrophages with HIO led to up-regulation of fibroblast activation genes including ACTA2 and COL1A1, and an increase in HIO collagen content. ETYA pre-treatment prevented pro-fibrotic effects of LPS-primed macrophages. ConclusionsETYA inhibits pro-fibrotic effects of LPS-primed macrophages upon co-cultured HIO. This model may be used in future untargeted screens for small molecules to treat refractory CD.

Background & AimsSystemic metabolic dysfunction promotes degenerative diseases in many organs, including liver and kidney. The liver is a master regulator of systemic metal ion homeostasis. Hepatic copper deficiency is increasingly observed in metabolic dysfunction associated steatotic liver disease (MASLD) and is associated with greater disease severity and poor outcomes. However, mechanisms linking copper dysregulation to MASLD and its co-morbidities remain poorly defined. We investigated whether impaired mitochondrial copper homeostasis contributes to MASLD-related pathobiology and represents a modifiable therapeutic axis. Methods & ResultsUsing dietary mouse models of MASLD and in vitro systems, we found that dietary copper deficiency induces lipotoxicity and suppresses mitochondrial metabolic programs. MASLD livers exhibited marked depletion of copper, impaired cytochrome c oxidase integrity, and bioenergetic failure. Targeted restoration of mitochondrial copper with the copper ionophore elesclomol normalized copper-handling programs, improved mitochondrial function, and suppressed ferroptotic stress, hepatocyte senescence, and fibroinflammatory remodeling. Mechanistically, reduced expression of the mitochondrial copper transporter SLC25A3 and MT-CO1 disrupted the SLC25A3-SCO1-MT-CO1-CTR1 axis, limited copper uptake and destabilized copper-iron balance, promoting maladaptive cell fate changes. Across multiple human cohorts and mouse models, copper-iron imbalance tracks with MASLD progression, clinical outcomes, and multiple extrahepatic comorbidities; restoring copper homeostasis in mice with MASLD attenuates both liver and kidney inflammation and fibrosis. ConclusionsMitochondrial copper deficiency is a mechanistically actionable driver of MASLD that promotes bioenergetic failure, ferroptosis, senescence and fibroinflammatory damage in the liver and other organs. Targeting copper-centered mitochondrial regulation represents a novel biomarker and therapeutic strategy for MASLD and its systemic complications.

Prior studies indicate no correlation between gut microbiota of healthy first-degree relatives (HFDRs) of Crohns disease (CD) patients and development of CD. Here, we utilized HFDRs as controls to examine the microbiota and metabolome in individuals with active (CD-A) and quiescent (CD-R) CD, thereby minimizing the influence of genetic and environmental factors. Compared to non-relative controls, the use of HFDR controls identified fewer differential taxa. Faecalibacterium, Dorea, and Fusicatenibacter showed decreased abundances in CD-R, independent of inflammation, and correlated with fecal SCFAs. Validation with a large multi-center cohort confirmed decreased abundances in Faecalibacterium and other SCFA-producing genera in CD-R. Classification models based on these genera distinguished CD-R and CD-A from healthy individuals, in both the discovery and validation cohorts. Thus, the decreased presence of Faecalibacterium, Dorea, and Fusicatenibacter in CD-R likely contributed to disease relapse through reduced SCFA production, highlighting their potential as diagnostic markers and therapeutic targets for CD.