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Abstract Background Magnetic resonance imaging (MRI) and MRI‐based elastography (MRE) are the most promising noninvasive techniques in assessing liver diseases. The purpose of this study was to evaluate an advanced multiparametric imaging method for staging disease and assessing treatment response in realistic preclinical alcohol‐associated liver disease (ALD). Methods We utilized four different preclinical mouse models in our study: Model 1—mice were fed a fast‐food diet and fructose water for 48 weeks to induce nonalcoholic fatty liver disease; Model 2—mice were fed chronic‐binge ethanol (EtOH) for 10 days or 8 weeks to induce liver steatosis/inflammation. Two groups of mice were treated with interleukin‐22 at different time points to induce disease regression; Model 3—mice were administered CCl 4 for 2 to 4 weeks to establish liver fibrosis followed by 2 or 4 weeks of recovery; and Model 4—mice were administered EtOH plus CCl 4 for 12 weeks. Mouse liver imaging biomarkers including proton density fat fraction (PDFF), liver stiffness (LS), loss modulus (LM), and damping ratio (DR) were assessed. Liver and serum samples were obtained for histologic and biochemical analyses. Ordinal logistic regression and generalized linear regression analyses were used to model the severity of steatosis, inflammation, and fibrosis, and to assess the regression of these conditions. Results Multiparametric models with combinations of biomarkers (LS, LM, DR, and PDFF) used noninvasively to predict the histologic severity and regression of steatosis, inflammation, and fibrosis were highly accurate (area under the curve > 0.84 for all). A three‐parameter model that incorporates LS, DR, and ALT predicted histologic fibrosis progression ( r = 0.84, p < 0.0001) and regression ( r = 0.79, p < 0.0001) as measured by collagen content in livers. Conclusion This preclinical study provides evidence that multiparametric MRI/MRE can be used noninvasively to assess disease severity and monitor treatment response in ALD.

Physiologic aging leads to attrition of telomeres and replicative senescence. An acceleration of this process has been hypothesized in the progression of chronic liver disease. We sought to examine the association of telomere length (TL) with liver disease and its impact on mortality risk. A cohort of 7,072 adults with leukocyte TL measurements from the National Health and Nutrition Examination Survey 1999‐2002 with mortality follow‐up through 2015 was analyzed. Liver disease was defined by aminotransferase levels and classified into etiology‐based and advanced fibrosis categories. Multivariable‐adjusted linear regression models estimated effect sizes, with 95% confidence intervals (CIs), of the presence of liver disease on TL. Cox regression models evaluated associations between TL and all‐cause mortality risk using adjusted hazard ratios (HRs). The cohort was representative of the US population with mean age 46.1 years and mean TL 5.79 kilobase pairs. No overall association between TL and liver disease was found; however, there was a significant negative association of TL and advanced liver fibrosis in individuals aged 65 and above. The liver disease cohort (HR 1.22, 95% CI 0.99‐1.51) and those with metabolic syndrome (HR 1.26, 95% CI 0.96‐1.67) had increased mortality risk with shorter TL. The relationship between TL and all‐cause mortality was stronger in women (HR 1.51, 95% CI 1.02‐2.23) and in non‐Hispanic Whites (HR 1.37, 95% CI 1.02‐1.84). Conclusion: Shortened leukocyte TL is independently associated with advanced liver disease at older ages, and with a higher risk of all‐cause mortality in those with liver disease. These associations reaffirm the need to better understand the role of telomeres in the progression of liver disease.

Primary sclerosing cholangitis (PSC) is a chronic fibroinflammatory disease of the biliary tract characterized by cellular senescence and periportal fibrogenesis. Specific disease features that are cell intrinsic and either genetically or epigenetically mediated remain unclear due in part to a lack of appropriate, patient‐specific, in vitro models. Recently, our group developed systems to create induced pluripotent stem cell (iPSC)‐derived cholangiocytes (iDCs) and biliary epithelial organoids (cholangioids). We use these models to investigate whether PSC cholangiocytes are intrinsically predisposed to cellular senescence. Skin fibroblasts from healthy controls and subjects with PSC were reprogrammed to pluripotency, differentiated to cholangiocytes, and subsequently grown in three‐dimensional matrigel‐based culture to induce formation of cholangioids. RNA sequencing (RNA‐seq) on iDCs showed significant differences in gene expression patterns, including enrichment of pathways associated with cell cycle, senescence, and hepatic fibrosis, that correlate with PSC. These pathways also overlapped with RNA‐seq analysis on isolated cholangiocytes from subjects with PSC. Exome sequencing on the subjects with PSC revealed genetic variants of unknown significance in the genes identified in these pathways. Three‐dimensional culture revealed smaller size, lack of a central lumen, and increased cellular senescence in PSC‐derived cholangioids. Congruent with this, PSC‐derived iDCs showed increased secretion of the extracellular matrix molecule fibronectin as well as the inflammatory cytokines interleukin‐6, and chemokine (C‐C motif) ligand 2. Conditioned media (CM) from PSC‐derived iDCs more potently activated hepatic stellate cells compared to control CM. Conclusion: We demonstrated efficient generation of iDCs and cholangioids from patients with PSC that show disease‐specific features. PSC cholangiocytes are intrinsically predisposed to cellular senescence. These features are unmasked following biliary differentiation of pluripotent stem cells and have functional consequences in epithelial organoids.

LINKED CONTENTThis article is linked to Singal et al and Barnard & Dave papers. To view these articles, visit https://doi.org/10.1111/apt.16461 and https://doi.org/10.1111/apt.16491

Alcohol‐associated hepatitis (AAH) is a severe form of liver injury with mortality as high as 30%‐40% at 90 days. As a result of altered immune function in AAH, bacterial infections are common and are associated with poor outcomes. However, determining the risk and subsequent development of infection in patients with AAH remain challenging. We performed a retrospective study of consecutive patients admitted with a diagnosis of AAH at two independent tertiary centers from 1998 to 2018 (test cohort, n = 286) who developed infections following hospitalization. The diagnosis of AAH was confirmed by manual chart review according to the recent National Institute on Alcohol Abuse and Alcoholism definition. Infections were categorized by location and time of diagnosis as hospital‐acquired infection (48 hours after admission until discharge) and posthospital infections (up to 6 months following discharge). The cohort was 66% men, and the median age was 48 (21‐83) years. Corticosteroids were used in 32% of all patients with AAH. The overall infection rate was 24%. Of those with infections, 46% were hospital acquired and 54% were acquired after hospitalization. Variables found to be significant risk factors for bacterial infection included the presence of ascites on admission (hazard ratio [HR], 2.06), corticosteroid administration (HR, 1.70), Model for End‐Stage Liver Disease (MELD) >23 (HR, 2.61), and white blood cell (WBC) count on admission per point (HR, 1.02). Conclusion: In this multicenter cohort study of patients hospitalized with AAH, MELD score, ascites, WBC count, and use of corticosteroids were identified as significant predictors of the development of bacterial infection. We created a novel predictive equation that may be used to aid in the identification of patients with AAH at high risk of infection.

SummaryBackgroundAlcohol use and alcohol‐associated liver disease (ALD) burden are increasing in young individuals.AimTo assess host factors associated with this burden.MethodsNational Health and Nutrition Examination Survey (NHANES), National Inpatient Sample (NIS), and United Network for Organ Sharing (UNOS) databases (2006‐2016) were used to identify individuals with harmful alcohol use, ALD‐related admissions, and ALD‐related LT listings respectively.ResultsOf 15 981 subjects in NHANES database, weighted prevalence of harmful alcohol use was 17.7%, 29.3% in <35 years (G1) versus 16.9% in 35‐64 years (G2) versus 5.1% in ≥65 years (G3). Alcohol use was about 11 and 4.7 folds higher in G1 and G2 versus G3, respectively. Male gender and Hispanic race associated with harmful alcohol use. Of 593 600 ALD admissions (5%, 77%, and 18% in G1‐G3 respectively), acute on chronic liver failure (ACLF) occurred in 7.2%, (7.2 in G2 vs 6.7% in G1 and G3, P < 0.001). After controlling for other variables, ACLF development among ALD hospitalizations was higher by 14% and 10% in G1 and G2 versus G3, respectively. Female gender and Hispanic race were associated with increased ACLF risk by 8% and 17% respectively. Of 20,245 ALD LT listings (3.4%, 84.4%, and 12.2% in G1‐G3 respectively), ACLF occurred in 28% candidates. Risk of severe (grade 2 or 3) ACLF was higher by about 1.7 fold in G1, 1.5 fold in females and 20% in Hispanics.ConclusionYoung age, female gender, and Hispanic race are independently associated with ALD‐related burden and ACLF in the United States. If these findings are validated in prospective studies, strategies will be needed to reduce alcohol use in high risk individuals to reduce burden from ALD.

Background: Obesity paradox is a phenomenon in which obesity increases the risk of obesity-related chronic diseases but paradoxically is associated with improved survival among obese patients with these diagnoses. Objectives: The aim of this study was to explore the obesity paradox among critically ill patients with cirrhosis admitted to the Intensive Care Unit. Methods: A retrospective cohort of 1,143 consecutive patients with cirrhosis admitted to the ICU between January of 2006 and December of 2015 was analyzed. Primary outcome of interest was in-hospital mortality with secondary end points including ICU and short-term mortality at 30 days post ICU admission. Results: Logistic regression with generalized additive models was used, controlling for clinically relevant and statistically significant factors to determine the adjusted relationship between body mass index (BMI) and ICU, post-ICU in-hospital, and 30 day mortality following ICU discharge. ICU and hospital length of stay was similar across all BMI classes. Adjusted ICU mortality was also similar when stratified by BMI. However, a significant reduction in post-ICU hospital mortality was observed in class I and II obese patients with cirrhosis (BMI 30-39.9 kg/m 2 ) compared to normal BMI (OR = 0.41; 95% CI, 0.20 to 0.83; P = 0.014). Similarly, overweight (BMI 25-29.9 kg/m 2 ) and class I and II obese patients with cirrhosis had significantly lower 30-day mortality following ICU discharge (OR = 0.52, 95% CI 0.31 to 0.87; P = 0.014; OR = 0.50, 95% CI 0.29 to 0.86; P = 0.012, respectively) compared to those with normal BMI. Conclusion: The signal of obesity paradox is suggested among critically ill patients with cirrhosis.

GTP Cyclohydrolase‐I (GTPCHI) is the rate‐limiting enzyme for the synthesis of tetrahydrobiopterin (BH4), which is an essential cofactor for the enzymatic activity of endothelial nitric oxide synthase (eNOS). To better understand the role of GTPCHI in maintaining eNOS function, we analyzed GTPCHI subcellular localization and activity in human umbilical cord vein endothelial cells (HUVEC). Western blot analysis showed similar levels of GTPCHI protein expression in both Triton X‐100 ‐soluble and ‐insoluble fractions, suggesting membrane targeting of GTPCHI. Further analysis of membrane‐associated proteins using sucrose gradient ultracentrifugation revealed that GTPCHI protein expression was localized to caveolar microdomains along with caveolin‐1(Cav‐1) and eNOS. HPLC analysis for GTPCHI activity confirmed the localization of GTPCHI to caveolar microdomains as well as golgi‐associated membrane fractions. Using an in vitro GST pull‐down assay with recombinantGST‐caveolin‐1 fusion protein incubated with the lysate of HUVEC, we demonstrated specific binding of GTPCHI to caveolin‐1. To determine if caveolin‐1 may regulate GTPCHI activity in vivo, we analyzed aortas from Cav‐1 −/ − mice and were able to detect a two‐fold increase in BH4 production and GTPCHI activity in the aortas of Cav‐1 −/ − mice when compared to eNOS −/ − mice or wild type mice. These studies reveal that BH4 synthesis can occur in specialized membrane compartments in close proximity to eNOS and may be subjected to posttranslational regulation by caveolin‐1 which has an inhibitory effect on GTPCHI enzyme activity. Funded by NIH grant HL‐53524.

Farnesoid X Receptor (FXR) mediates important signaling functions of bile acids in diverse cell types including those residing in the vascular wall. Indeed, recent work has identified FXR as a potential regulator of vascular structure and function in part through transcriptional activation of MMP‐9. However, the signal transduction pathways linking bile acids to changes in actin cytoskeleton that are responsible for bile acid induced vascular cell migration remain unexplored. The FXR agonist and prototypical bile acid, chenodeoxycholic acid (CDCA), significantly increased endothelial cell (EC) motility, as analyzed by time lapse video microscopy, and tube formation, an in vitro correlate for angiogenesis. Increased cell motility was associated with prominent increases in focal adhesion (FA) plaques and was inhibited by FXR or MMP‐9 siRNA, indicating a FXR‐MMP‐9‐dependency of this signaling pathway. Mechanistically, incubation of cells with CDCA was associated with phosphorylation of a key FA protein, Focal Adhesion Kinase (FAK) at Y397 but not at Y576/577, or Y925. Studies using a site‐specific phosphodefective FAK mutant revealed that FAK phosphorylation at tyrosine residue ‐397 was required for CDCA induced activation of the downstream FA assembly protein, paxillin. Lastly, siRNA based silencing of FAK as well as phosphodefective FAK mutant both inhibited CDCA induced upregulation of MMP‐9, cell motility and tube formation. Thus, this study demonstrates a pivotal role for FAK in the process of FXR‐induced and MMP‐9 ‐dependent EC motility and vascular tube formation. Funded by NIH Grant # DK059615

Mechanisms that mediate migration, homing and integration of blood outgrowth endothelial cells (BOEC) to sites of vascular injury are incompletely understood, although matrix metalloproteinases (MMPs) have been implicated in this process. Farnesoid X receptor (FXR) signaling pathway has recently been recognized to regulate vascular wall signaling. The aim of this study was to characterize the expression of FXR in human BOEC and examine signaling pathways relevant to BOEC migration. FXR mRNA and protein levels were detected by reverse‐transcriptase PCR and Western blot. Microarray analysis using a focused human endothelial cell biology array (Superarray) suggested that natural (Chenodeoxycholic acid (CDCA), 0.1–100μM) and synthetic (6‐ethylchenodeoxycholic acid (6‐ECDCA) 0.01–10μM) FXR ligands significantly increased MMP9 transcription which was confirmed by real time PCR and gelatin zymography. SiRNA based silencing of FXR prevented CDCA induced increases in MMP9 mRNA, while retroviral over‐expression of FXR in BOEC enhanced MMP9 mRNA levels. CDCA induced expression of Small Heterodimeric Partner (SHP), a downstream target of FXR. Retroviral over‐expression of SHP increased, whereas siRNA silencing of SHP inhibited CDCA induced MMP9 mRNA levels. Migration analysis using Boyden assay demonstrated that CDCA stimulated migration of BOEC which was blocked by transfection with FXR or MMP9 siRNA (p<0.05; n=5). These studies identify a novel signaling pathway by which a key protein important in cell homing and migration, MMP9, is regulated through a previously unrecognized FXR‐SHP pathway in BOEC. Funded by NIH Grant # DK59615