Aim: This study aimed to identify novel miRNAs (miRs) as regulators of UGT1A gene expression and to evaluate them as potential risk factors for the development of liver fibrosis/cirrhosis. Material...

Background: Aging is characterized by the progressive decline of physiological functions and is associated with an increasing risk for developing multiple age‐related diseases. UDP‐glucuronosyltransferase (UGT)1A enzymes detoxify a variety of endo‐ and xenobiotic reactive metabolites, thereby acting as indirect antioxidants. A common genetic UGT1A haplotype was shown to affect redox balance in humanized transgenic (htg) UGT1A mice. Since oxidative stress is a main activator of cellular senescence, we aimed to investigate the role of genetic UGT1A variants in the process of aging. Methods: Htg UGT1A ‐WT and htg UGT1A ‐SNP mice were harvested at the age of either 12 weeks (young) or 18 months (aged). The effect of aging was examined by analyzing UGT1A expression and activity, expression of senescence markers, and senescence‐associated secretory phenotype (SASP) factors, as well as blood counts, serum parameter, and histological staining. Results: In comparison to aged htg UGT1A ‐WT mice, hepatic UGT1A mRNA and protein expression as well as UGT activity were significantly reduced in aged htg UGT1A ‐SNP mice. Moreover, elderly htg UGT1A ‐SNP mice exhibited increased levels of oxidative stress, senescence markers, SASP factors, and peripheral leukocyte counts compared to the respective htg UGT1A ‐WT mice. Consistent with these findings, we observed higher amounts of collagen and amyloid fibrils as well as an elevated senescence‐associated β‐galactosidase (SA‐β‐gal) activity in histological sections of the liver obtained from aged htg UGT1A ‐SNP mice. Conclusion: Our data suggest an accelerated aging process caused by a common UGT1A haplotype. Moreover, elderly individuals carrying the UGT1A haplotype might exhibit an altered metabolism of drugs, which could necessitate dose adjustments.

Background: Primary sclerosing cholangitis (PSC) is a chronic liver disease leading to inflammation with scaring and strictures of bile ducts, which can lead to liver cirrhosis. A subtype of PSC characterized by high serum IgG4 (sIgG4) levels has been reported to be associated with poor outcomes, but the exact role and the longitudinal development of sIgG4 levels in PSC progression remains to be clarified. The aim of this study was to investigate if subsequent analysis of sIgG4 levels allows the identification of the PSC phenotype with high sIgG4. Methods: sIgG4 values were repeatedly analysed in a well-characterized European PSC cohort of 110 individuals. Biochemical parameters, clinical endpoints, death and liver transplantation were compared between PSC subgroups. Results: 12.7% (n = 14) of PSC patients showed increased sIgG4 levels (PSC-IgG4). The values normalized in 57.1% (n = 8; PSC-IgG4_norm) during follow-up measurements, whereas the values remained permanently elevated in 42.9% (n = 6; PSC-IgG4_const). Serum values of AP and γGT were significantly higher in PSC-IgG4_const compared to PSC-IgG4_norm at final blood sampling. Furthermore, mean age at PSC diagnosis was markedly lower in PSC-IgG4_const compared to PSC-IgG4_norm. Conclusions: This is the first study analyzing longitudinal development of sIgG4 in PSC. Our data indicate that only sequential determination of sIgG4 levels allow to accurately distinguish between the PSC phenotype with high sIgG4 and PSC with low sIgG4. Graphical

Primary sclerosing cholangitis (PSC) is a chronic, progressive cholestatic liver disease characterized by inflammation and fibrosis of the bile ducts. Altered bile acid (BA) profile was shown to trigger immune responses in the liver, contributing to inflammation and liver fibrosis. Here, we analyzed BAs, their precursors (oxysterols), surrogate markers of cholesterol synthesis as well as of absorption, and studied their association with clinical/ immunological parameters in PSC. We analyzed concentrations of BAs (cholic acid, CA; chenodeoxycholic acid, CDCA; deoxycholic acid, DCA; lithocholic acid, LCA; ursodeoxycholic acid, UDCA), their precursors (7α-, 24-, 27-hydroxycholesterol, 7αOH-Chol, 24OH-Chol, 27OH-Chol), cholesterol synthesis marker lathosterol and cholesterol absorption markers (5α-cholestanol, sitosterol, campesterol) in serum from patients with PSC (n = 33) in comparison to healthy blood donors (n = 30). Inflammatory cytokines in serum were measured using flow-cytometry-based bead array. While serum concentrations of cholesterol and its precursor lathosterol were comparable between patients with PSC and healthy individuals, serum concentrations of CA and CDCA were statistically significant increased in PSC. Furthermore, we observed elevated concentrations of cholesterol absorption markers in PSC. Association with clinical parameters revealed a statistically significant correlation of CA, CDCA, and cholesterol absorption markers with AP, bilirubin, AST, and ALT. In addition, pro-inflammatory IP-10 (interferon-gamma-inducible protein-10) was increased in serum of PSC patients and associated with primary BAs and liver fibrosis. Our findings reveal a distinct metabolic signature in PSC characterized by increased primary BAs and cholesterol absorption markers in serum. The correlations between IP-10, BAs, and fibrosis suggest a bile acid-driven pro-inflammatory circuit potentially contributing to disease progression.

Primary sclerosing cholangitis (PSC) is a rare cholestatic liver disease characterized by progressive inflammation of the intra- and extrahepatic bile ducts and a high association with inflammatory bowel disease. Since bacterial and viral stimuli are thought to contribute to the pathogenesis of autoimmune diseases, our study aims to investigate the effects of synthetic pathogenic agonists on the cytotoxic function of cluster of differentiation (CD)56+ natural killer (NK) cells and CD8+ T cells in PSC. A total of 17 PSC patients, 18 autoimmune hepatitis (AIH) patients, and 14 healthy controls (HCs) were included in this study. Using multicolor flow cytometry, we analyzed cytotoxic activity (CD107a assay) and secretion of interferon-gamma and tumor necrosis factor-alpha in peripheral CD56+ NK-cell subsets and CD8+ T cells after in vitro stimulation with synthetic bacterial (Pam3CSK, lipopolysaccharide [LPS], CpG-ODN-2216, and flagellin) and viral agonists (polyinosinic: polycytidylic acid [poly(I: C)], poly(I: C)-high molecular weight/LyoVec™, 5’ppp-dsRNA/LyoVec™, and R837). Compared with AIH patients and HCs, CD56+ NK-cell subsets from PSC patients showed reduced cytotoxicity both at baseline and upon in vitro stimulation with synthetic bacterial/viral agonists. Notably, the percentage of unstimulated CD107a+CD56dimCD16+ NK cells positively correlated with clinical serum parameters in PSC. In addition, the percentage of CD107a+CD8+ cells was significantly reduced after synthetic bacterial/viral stimulation in PSC patients. Finally, in PSC patients, production of pro-inflammatory cytokines was markedly reduced in CD56highCD16− NK cells upon in vitro stimulation with Pam3CSK and LPS, respectively. This hyporesponsiveness of CD56+ NK cells and CD8+ T cells may contribute to the development of hepatic inflammation, representing a hallmark of PSC pathogenesis.