LaRusso, Nicholas F

ABSTRACT Background Primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are rare, chronic cholestatic liver diseases with heterogeneous progression and limited biomarkers of disease biology. Epigenetic age acceleration has been demonstrated in PSC and PBC, suggesting accelerated biological aging. DNA methylation–derived telomere length (DNAmTL) reflects replicative aging and cellular turnover, but its role in PSC and PBC remains unclear. We aimed to evaluate DNAmTL in PSC and PBC and its association with disease severity. Methods We analysed and compared DNAmTL and age‐adjusted DNAmTL among patients with PSC ( n = 474) versus PSC controls ( n = 484) and patients with PBC ( n = 291) versus PBC controls ( n = 291). Associations with clinical outcomes were assessed using nonparametric tests and multivariable logistic regression models. Correlations with primary sclerosing cholangitis Risk Estimate Tool (PREsTO) score and epigenetic age acceleration (AgeAccelGrim) were evaluated using linear regression. Results Patients with PSC demonstrated significantly shorter age‐adjusted DNAmTL compared with controls (median −0.036 vs. 0.016, p < 0.001). Patients with PBC also exhibited reduced DNAmTL relative to controls (median 6.814 vs. 6.885, p < 0.001). Within PSC, shorter DNAmTL was associated with cirrhosis (OR 0.21, 95% CI 0.06–0.69, p = 0.013) and advanced disease (OR 0.20, 95% CI 0.06–0.67, p = 0.009). Shorter DNAmTL was also observed in hepatic decompensation and hepatobiliary malignancy, including cholangiocarcinoma. DNAmTL inversely correlated with PReSTO score ( p < 0.001). DNAmTL was strongly inversely correlated with AgeAccelGrim in both PSC and PBC ( p < 0.001). Conclusion Cholestatic liver diseases are associated with shortened DNAmTL, which independently correlates with disease severity in PSC. Together with epigenetic age acceleration, these findings support a model of accelerated biological aging in PSC and PBC characterized by converging signatures of accelerated biological aging that may contribute to progressive biliary injury and fibrosis.

Introduction: Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease without approved medical therapies. We examined the efficacy and safety of oral vancomycin (OV) in those with PSC. Methods: In this phase 3, 18-month, double-blind, placebo-controlled trial, we randomly assigned adults with PSC and a serum alkaline phosphatase (SAP) greater than 1.5 times the upper limit of normal to placebo or oral vancomycin (OV) with dosages ranging from 125-375 mg four times daily pending biochemical response. The primary endpoint was normalization of SAP. Results: Of the 82 patients who underwent randomization, 73 individuals had at least one outcome assessment. Individuals who withdrew early were less likely to rate their baseline health as excellent or very good (23.4% vs 54.5%, p<0.01) despite having similar PSC prognostic features to those who completed the study. SAP normalization rates were similar (5% placebo, 6.7% OV, p=1.00) after 18 months. Those who received OV had greater reduction in SAP (+1.2% placebo, -21.9% OV, p=0.03). There were no differences in the changes in either the Mayo PSC risk score (-0.1 placebo, -0.1 OV, p=0.88) or liver stiffness values (+0.1 kPa placebo, -4.0 kPa OV, p=0.15). Discoloration of the teeth and tongue was the most common side effect of OV (17.5%). Conclusions: OV was not associated with clinically significant reductions in markers of PSC disease severity. Impairments in quality of life may influence patient retention in clinical trials.

Cholangiocytes are specialized epithelial cells that line the intrahepatic and extrahepatic biliary tree and play a critical role in bile modification, liver homeostasis, and response to injury. Cholangiocytes exhibit notable heterogeneity and plasticity, and their dysfunction is central to a spectrum of diseases targeting the bile ducts, collectively called cholangiopathies. These disorders include genetic, infectious, immune-mediated, and malignant diseases, with primary sclerosing cholangitis (PSC) representing one of the most complex and enigmatic of these disorders. PSC is a progressive, fibro-inflammatory disease of the bile ducts that is closely linked to inflammatory bowel disease, carries a heightened risk of cancer, and lacks any approved therapies. This review explores the biology of cholangiocytes, including their development, functional plasticity, and roles in secretion, absorption, and cellular signaling. We provide a detailed examination of cholangiopathies, particularly PSC, a complex cholangiopathy characterized by a paradoxical state of cholangiocyte senescence and hyperproliferation. We describe how immune cell dysfunction, the gut microbiome, genetic predispositions, and environmental factors converge to mediate PSC pathogenesis. We revisit the foundational technologies that empowered early discoveries and shaped the field as we know it today. We also explore how newer techniques such as organoid cultures, single-cell transcriptomics, epigenomics, and spatialomics have transformed our modern understanding of biliary pathophysiology. Finally, we provide an overview of existing rodent models of cholangiopathies and discuss their relevance to human disease. PSC remains therapeutically unaddressed, and thus ongoing multidisciplinary efforts are essential to developing targeted interventions. This review serves as a comprehensive resource for researchers and clinicians navigating the rapidly evolving landscape of cholangiocyte-centered liver disease research.

Cholangiocyte pathophysiological activation was examined in a model of murine cholestasis. CX3CR1 + macrophages are recruited to the periportal region, likely mediated by cholangiocyte expression of CX3CL1. Cholangiocyte transcriptomics from cholestatic mice display activation of a “pathogen-induced cytokine storm” pathway, and exhibit activation of the transcription factor NF-Y. In human cholangiocytes, NF-Y promotes expression of the profibrogenic ligand TGFβ1. These observations provide insights into the cholestatic cholangiocyte pathobiology contributing to periductal inflammation and fibrosis.

Abstract Senescent cells secrete proinflammatory factors known as the senescence-associated secretory phenotype (SASP), contributing to tissue dysfunction and aging. Mitochondrial dysfunction is a key feature of senescence, influencing SASP via mitochondrial DNA (mtDNA) release and cGAS/STING pathway activation. Here, we demonstrate that mitochondrial RNA (mtRNA) also accumulates in the cytosol of senescent cells, activating RNA sensors RIG-I and MDA5, leading to MAVS aggregation and SASP induction. Inhibition of these RNA sensors significantly reduces SASP factors. Furthermore, BAX and BAK plays a key role in mtRNA leakage during senescence, and their deletion diminishes SASP expression in vitro and in a mouse model of Metabolic Dysfunction Associated Steatohepatitis (MASH). These findings highlight mtRNA's role in SASP regulation and its potential as a therapeutic target for mitigating age-related inflammation.

Background: The epigenome, the set of modifications to DNA and associated molecules that control gene expression, cellular identity, and function, plays a major role in mediating cellular responses to outside factors. Thus, evaluation of the epigenetic state can provide insights into cellular adaptions occurring over the course of disease. Methods: We performed epigenome-wide association studies of primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) using the Illumina MethylationEPIC Bead Chip. Results: We found evidence of increased epigenetic age acceleration and differences in predicted immune cell composition in patients with PSC and PBC. Epigenetic profiles demonstrated differences in predicted protein levels including increased levels of tumor necrosis factor receptor superfamily member 1B in patients with cirrhotic compared to noncirrhotic PSC and PBC. Epigenome-wide association studies of PSC discovered strongly associated 5′-C-phosphate-G-3′ sites in genes including vacuole membrane protein 1 and SOCS3, and epigenome-wide association studies of PBC found strong 5′-C-phosphate-G-3′ associations in genes including NOD-like receptor family CARD domain containing 5, human leukocyte antigen-E, and PSMB8. Analyses identified disease-associated canonical pathways and upstream regulators involved with immune signaling and activation of macrophages and T-cells. A comparison of PSC and PBC data found relatively little overlap at the 5′-C-phosphate-G-3′ and gene levels with slightly more overlap at the level of pathways and upstream regulators. Conclusions: This study provides insights into methylation profiles of patients that support current concepts of disease mechanisms and provide novel data to inspire future research. Studies to corroborate our findings and expand into other -omics layers will be invaluable to further our understanding of these rare diseases with the goal to improve and individualize prognosis and treatment.

AbstractBackground & AimsPrimary sclerosing cholangitis (PSC) is a chronic liver disease characterized by peribiliary inflammation and fibrosis. Cholangiocyte senescence is a prominent feature of PSC. Here, we hypothesize that extracellular vesicles (EVs) from senescent cholangiocytes influence the phenotype of target cells.MethodsEVs were isolated from normal human cholangiocytes (NHCs), cholangiocytes from PSC patients and NHCs experimentally induced to senescence. NHCs, malignant human cholangiocytes (MHCs) and monocytes were exposed to 108 EVs from each donor cell population and assessed for proliferation, MAPK activation and migration. Additionally, we isolated EVs from plasma of wild‐type and Mdr2−/− mice (a murine model of PSC), and assessed mouse monocyte activation.ResultsEVs exhibited the size and protein markers of exosomes. The number of EVs released from senescent human cholangiocytes was increased; similarly, the EVs in plasma from Mdr2−/− mice were increased. Additionally, EVs from senescent cholangiocytes were enriched in multiple growth factors, including EGF. NHCs exposed to EVs from senescent cholangiocytes showed increased NRAS and ERK1/2 activation. Moreover, EVs from senescent cholangiocytes promoted proliferation of NHCs and MHCs, findings that were blocked by erlotinib, an EGF receptor inhibitor. Furthermore, EVs from senescent cholangiocytes induced EGF‐dependent Interleukin 1‐beta and Tumour necrosis factor expression and migration of human monocytes; similarly, Mdr2−/− mouse plasma EVs induced activation of mouse monocytes.ConclusionsThe data continue to support the importance of cholangiocyte senescence in PSC pathogenesis, directly implicate EVs in cholangiocyte proliferation, malignant progression and immune cell activation and migration, and identify novel therapeutic approaches for PSC.