Statins in Chronic Liver Disease: Review of the Literature and Future Role.

Chronic liver disease (CLD) is a major contributor to global mortality, morbidity, and healthcare burden. Progress in pharmacotherapeutic for CLD management is lagging given its impact on the global population. While statins are indicated for the management of dyslipidemia and cardiovascular disease, their role in CLD prevention and treatment is emerging. Beyond their lipid-lowering effects, their liver-related mechanisms of action are multifactorial and include anti-inflammatory, antiproliferative, and immune-protective effects. In this review, we highlight what is known about the clinical benefits of statins in viral and nonviral etiologies of CLD and hepatocellular carcinoma (HCC), and explore key mechanisms and pathways targeted by statins. While their benefits may span the spectrum of CLD and potentially HCC treatment, their role in CLD chemoprevention is likely to have the largest impact. As emerging data suggest that genetic variants may impact their benefits, the role of statins in precision hepatology will need to be further explored.

Validation of a Machine Learning Algorithm, EVendo, for Predicting Esophageal Varices in Hepatocellular Carcinoma.

BACKGROUND: Treatment with atezolizumab and bevacizumab has become standard of care for advanced unresectable hepatocellular carcinoma (HCC) but carries an increased gastrointestinal bleeding risk. Therefore, patients are often required to undergo esophagogastroduodenoscopy (EGD) to rule out esophageal varices (EV) prior to initiating therapy, which can delay care and lead to unnecessary procedural risks and health care costs. In 2019, the EVendo score was created and validated as a noninvasive tool to accurately screen out patients who were at low risk for having EV that required treatment. We sought to validate whether the EVendo score could be used to accurately predict the presence of EV and varices needing treatment (VNT) in patients with HCC. METHODS: This was a retrospective multicenter cohort study of patients with HCC from 9/2004 to 12/2021. We included patients who underwent EGDs within 1 year after their HCC diagnosis. We collected clinical parameters needed to calculate an EVendo score at the time of EGD and compared the EVendo model prediction to the gold standard endoscopic report in predicting presence of VNT. RESULTS: 112 with HCC were recruited to this study, with 117 qualifying EGDs. VNT occurred in 39 (33.3%) patients. The EVendo score had a sensitivity of 97.4% and a negative predictive value of 96.9%, supporting the validity in applying EVendo in predicting VNT in HCC. CONCLUSION: In this study, we validated the use of the EVendo score in ruling out VNT in patients with HCC. The application of the EVendo score could safely defer about 30% of EGDs for EV screening in HCC patients. Although additional validation cohorts are needed, this suggests that EVendo score can potentially be applied in patients with HCC to avoid unnecessary EGDs, which can ultimately mitigate healthcare costs and delays in initiating HCC treatment with atezolizumab and bevacizumab.

Improved Survival After Liver Transplantation for Patients With Human Immunodeficiency Virus (HIV) and HIV/Hepatitis C Virus Coinfection in the Integrase Strand Transfer Inhibitor and Direct-Acting Antiviral Eras.

BACKGROUND: People with human immunodeficiency virus (HIV) with and without hepatitis C virus (HCV) coinfection had poor outcomes after liver transplant (LT). Integrase strand transfer inhibitors (INSTIs) and direct-acting antivirals (DAAs) have changed the treatment landscape for HIV and HCV, respectively, but their impact on LT outcomes remains unclear. METHODS: This retrospective analysis of adults with HIV monoinfection (n = 246) and HIV/HCV coinfection (n = 286) who received LT compared mortality in patients with HIV who received LT before versus after approval of INSTIs and in patients with HIV/HCV coinfection who received LT before versus after approval of DAAs. In secondary analysis, we compared the outcomes in the different eras with those of propensity score-matched control cohorts of LT recipients without HIV or HCV infection. RESULTS: LT recipients with HIV monoinfection did not experience a significant improvement in survival between the pre-INSTI and INSTI recipients with HIV (adjusted hazard ratio [aHR], 0.70 [95% confidence interval {CI}, .36-1.34]). However, recipients with HIV/HCV coinfection in the DAA era had a 47% reduction (aHR, 0.53 [95% CI, .31-9.2] in 1-year mortality compared with coinfected recipients in the pre-DAA era. Compared to recipients without HIV or HCV, HIV-monoinfected recipients had higher mortality during the pre-INSTI era, but survival was comparable between groups during the INSTI era. HIV/HCV-coinfected recipients also experienced comparable survival during the DAA era compared to recipients without HCV or HIV. CONCLUSIONS: Post-LT survival for people with HIV monoinfection and HIV/HCV coinfection has improved with the introduction of INSTI and DAA therapy, suggesting that LT has become safer in these populations.

Lipophilic statins inhibit YAP coactivator transcriptional activity in HCC cells through Rho-mediated modulation of actin cytoskeleton.

Hepatocellular carcinoma (HCC) is the third leading cause of liver-related death. Lipophilic statins have been associated with a decrease in HCC incidence, raising the possibility of their use as chemoprevention agents. The Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) have emerged as an important pro-oncogenic mechanism in HCC. Statins modulate YAP/TAZ in other solid tumors, but few studies have assessed their mechanisms in HCC. We aimed to delineate how lipophilic statins regulate YAP protein localization by interrogating the mevalonate pathway in a stepwise manner using pharmacological and genetical approaches in HCC cells. Huh7 and Hep3B HCC cells were treated with the lipophilic statins cerivastatin and atorvastatin. YAP protein localization was determined using quantitative immunofluorescence (IF) imaging. The gene expression of CTGF and CYR61, known YAP/TEA-domain DNA-binding factor (TEAD)-regulated genes, was measured using quantitative real-time PCR. Rescue experiments were conducted using metabolites of the mevalonate pathway including mevalonic acid and geranylgeranyl pyrophosphate (GG-PP). The cellular cytoskeleton was assessed using F-actin IF staining. YAP protein was extruded from the nucleus to the cytoplasm with statin treatment. Consistently, CTGF and CYR61 mRNA expression significantly decreased with statins. Cytoskeletal structure was also compromised with statins. Gene expression, YAP protein localization, and cytoskeletal structure were all restored to baseline with exogenous GG-PP but not with other metabolites of the mevalonate pathway. Direct Rho GTPase inhibitor treatment mirrored the statin effects on YAP. YAP protein localization is regulated by lipophilic statins via Rho GTPases, causing cytoskeletal structural changes and is independent of cholesterol metabolites.NEW & NOTEWORTHY Statins are widely used for the treatment of cardiovascular diseases. Recently, their use has been associated with a decrease in the incidence of hepatocellular carcinoma (HCC); however, their mechanism(s) has remained elusive. In this study, we delineate the mechanism by which statins affect the Yes-associated protein (YAP), which has emerged as a key oncogenic pathway in HCC. We investigate each step of the mevalonate pathway and demonstrate that statins regulate YAP via Rho GTPases.

Comparable Survival for Hepatitis C-Related Hepatocellular Carcinoma After Liver Transplantation Irrespective of Viremic Status.

Direct-acting antiviral (DAA) therapy for the treatment of chronic hepatitis C virus (HCV) infection is efficacious and well-tolerated in the post-liver transplant (LT) setting, prompting increased use of donors with HCV infection in patients waitlisted for LT.1,2 Although the incidence of nonviral hepatocellular carcinoma (HCC) is rising, HCV remains the most common risk factor for HCC among patients listed for LT in the United States.3 The use and outcomes of HCV-infected donors among patients with active HCV viremia waitlisted for (HCV-HCC) is lacking. Our aim was to evaluate post-LT survival among patients with HCV-HCC based on both recipient (active vs cured HCV) and donor (HCV+ vs HCV-) viremic status. Using the United Network for Organ Sharing (UNOS) registry, we analyzed all adult patients with HCV-HCC who underwent LT and had available recipient/donor HCV nucleic acid test (NAT) results from March 31, 2015 (date UNOS began reporting donor NAT) through June 30, 2021. Patients with acute liver failure, simultaneous organ transplant, previous LT, and those missing recipient and/or donor NAT results were excluded.

Reduction in Racial and Ethnic Disparity in Survival Following Liver Transplant for Hepatocellular Carcinoma in the Direct-acting Antiviral Era.

BACKGROUND & AIMS: Black patients with hepatocellular cancer (HCC), often attributed to hepatitis C virus (HCV) infection, have suboptimal survival following liver transplant (LT). We evaluated the impact of direct-acting antiviral (DAA) availability on racial and ethnic disparities in wait list burden post-LT survival for candidates with HCC. METHODS: Using the United Network for Organ Sharing registry, we identified patients with HCC who were listed and/or underwent LT from 2009 to 2020. Based on date of LT, patients were categorized into 2 era-based cohorts: the pre-DAA era (LT between 2009 and 2011) and DAA era (LT between 2015 and 2017, with follow-up through 2020). Kaplan-Meier and Cox proportional hazards analyses were used to compare post-LT survival, stratified by era and race and ethnicity. RESULTS: Annual wait list additions for HCV-related HCC decreased significantly in White and Hispanic patients during the DAA era, with no change (P = .14) in Black patients. Black patients had lower 3-year survival than White patients in the pre-DAA era (70.6% vs 80.1%, respectively; P < .001) but comparable survival in the DAA era (82.1% vs 85.5%, respectively; P = .16). 0n multivariable analysis, Black patients in the pre-DAA era had a 53% higher risk (adjusted hazard ratio [HR], 1.53; 95% confidence interval [CI], 1.28-1.84), for mortality than White patients, but mortality was comparable in the DAA era (adjusted HR, 1.23; 95% CI, 0.99-1.52). In a stratified analysis in Black patients, HCV-related HCC carried more than a 2-fold higher risk of mortality in the pre-DAA era (adjusted HR, 2.86; 95% CI, 1.50-5.43), which was reduced in the DAA era (adjusted HR, 1.34; 95% CI, 0.78-2.30). CONCLUSIONS: With the availability of DAA therapy, racial disparities in post-LT survival have improved.

Predictive Algorithm for Hepatic Steatosis Detection Using Elastography Data in the Veterans Affairs Electronic Health Records.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) has reached pandemic proportions. Early detection can identify at-risk patients who can be linked to hepatology care. The vibration-controlled transient elastography (VCTE) controlled attenuation parameter (CAP) is biopsy validated to diagnose hepatic steatosis (HS). We aimed to develop a novel clinical predictive algorithm for HS using the CAP score at a Veterans' Affairs hospital. METHODS: We identified 403 patients in the Greater Los Angeles VA Healthcare System with valid VCTEs during 1/2018-6/2020. Patients with alcohol-associated liver disease, genotype 3 hepatitis C, any malignancies, or liver transplantation were excluded. Linear regression was used to identify predictors of NAFLD. To identify a CAP threshold for HS detection, receiver operating characteristic analysis was applied using liver biopsy, MRI, and ultrasound as the gold standards. RESULTS: The cohort was racially/ethnically diverse (26% Black/African American; 20% Hispanic). Significant positive predictors of elevated CAP score included diabetes, cholesterol, triglycerides, BMI, and self-identifying as Hispanic. Our predictions of CAP scores using this model strongly correlated (r = 0.61, p < 0.001) with actual CAP scores. The NAFLD model was validated in an independent Veteran cohort and yielded a sensitivity of 82% and specificity 83% (p < 0.001, 95% CI 0.46-0.81%). The estimated optimal CAP for our population cut-off was 273.5 dB/m, resulting in AUC = 75.5% (95% CI 70.7-80.3%). CONCLUSION: Our HS predictive algorithm can identify at-risk Veterans for NAFLD to further risk stratify them by non-invasive tests and link them to sub-specialty care. Given the biased referral pattern for VCTEs, future work will need to address its applicability in non-specialty clinics. Proposed clinical algorithm to identify patients at-risk for NAFLD prior to fibrosis staging in Veteran.

Provider Attitudes Toward Risk-Based Hepatocellular Carcinoma Surveillance in Patients With Cirrhosis in the United States.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) surveillance rates are suboptimal in clinical practice. We aimed to elicit providers' opinions on the following aspects of HCC surveillance: preferred strategies, barriers and facilitators, and the impact of a patient's HCC risk on the choice of surveillance modality. METHODS: We conducted a web-based survey among gastroenterology and hepatology providers (40% faculty physicians, 21% advanced practice providers, 39% fellow-trainees) from 26 US medical centers in 17 states. RESULTS: Of 654 eligible providers, 305 (47%) completed the survey. Nearly all (98.4%) of the providers endorsed semi-annual HCC surveillance in patients with cirrhosis, with 84.2% recommending ultrasound ± alpha fetoprotein (AFP) and 15.4% recommending computed tomography (CT) or magnetic resonance imaging (MRI). Barriers to surveillance included limited HCC treatment options, screening test effectiveness to reduce mortality, access to transportation, and high out-of-pocket costs. Facilitators of surveillance included professional society guidelines. Most providers (72.1%) would perform surveillance even if HCC risk was low (≤0.5% per year), while 98.7% would perform surveillance if HCC risk was ≥1% per year. As a patient's HCC risk increased from 1% to 3% to 5% per year, providers reported they would be less likely to order ultrasound ± AFP (83.6% to 68.9% to 57.4%; P < .001) and more likely to order CT or MRI ± AFP (3.9% to 26.2% to 36.1%; P < .001). CONCLUSIONS: Providers recommend HCC surveillance even when HCC risk is much lower than the threshold suggested by professional societies. Many appear receptive to risk-based HCC surveillance strategies that depend on patients' estimated HCC risk, instead of our current "one-size-fits all" strategy.

Duodenal Microbiome and Serum Metabolites Predict Hepatocellular Carcinoma in a Multicenter Cohort of Patients with Cirrhosis.

BACKGROUND: Hepatocellular carcinoma (HCC) is rapidly increasing in the U.S. and is a leading cause of mortality for patients with cirrhosis. Discovering novel biomarkers for risk stratification of HCC is paramount. We examined biomarkers of the gut-liver axis in a prospective multicenter cohort. METHODS: Patients with cirrhosis without a history of HCC were recruited between May 2015 and March 2020 and prospectively followed at 3 tertiary care hospitals in Los Angeles. Microbiome analysis was performed on duodenal biopsies and metabolomic analysis was performed on serum samples, collected at the time of enrollment. Optimal microbiome-based survival analysis and Cox proportional hazards regression analysis were used to determine microbiota and metabolite associations with HCC development, respectively. RESULTS: A total of 227 participants with liver cirrhosis contributed a total of 459.58 person-years of follow-up, with 14 incident HCC diagnoses. Male sex (HR = 7.06, 95% CI = 1.02-54.86) and baseline hepatic encephalopathy (HE, HR = 4.65, 95% CI = 1.60-13.52) were associated with developing HCC over follow-up. Adjusting for age, sex, baseline HE, and alkaline phosphatase, an increased risk of HCC were observed for participants with the highest versus lowest three quartiles for duodenal Alloprevotella (HR = 3.22, 95% CI = 1.06-9.73) and serum taurocholic acid (HR = 6.87, 95% CI = 2.32-20.27), methionine (HR = 9.97, 95% CI = 3.02-32.94), and methioninesulfoxide (HR = 5.60, 95% CI = 1.84-17.10). Being in the highest quartile for Alloprevotella or methionine had a sensitivity and specificity for developing HCC of 85.71% and 60.56%, respectively, with an odds ratio of 10.92 (95% CI = 2.23-53.48). CONCLUSION: Alloprevotella and methionine, methioninesulfoxide, and taurocholic acid predicted future HCC development in a high-risk population of participants with liver cirrhosis.

Nonalcoholic Fatty Liver Disease Risk Factors Affect Liver-Related Outcomes After Direct-Acting Antiviral Treatment for Hepatitis C.

INTRODUCTION: In hepatitis C (HCV) patients, obesity and/or diabetes may increase the risk of liver-related outcomes. We aimed to determine whether diabetes and/or obesity are associated with adverse outcomes in direct-acting antiviral (DAA)-treated HCV patients. METHODS: We conducted a retrospective study of 33,003 HCV-infected, DAA-treated Veterans between 2013 and 2015. Body mass index was used to categorize patients into underweight (< 18.5 kg/m2), normal weight (18.5 to < 25 kg/m2), overweight (25 to < 30 kg/m2), obesity I (30 to < 35 kg/m2), and obesity II-III (> 35 kg/m2). Diabetes was defined by ICD-9/10 codes in association with hemoglobin A1c > 6.5% or medication prescriptions. Patients were followed from 180 days post-DAA initiation until 2/14/2019 to assess for development of cirrhosis, decompensations, hepatocellular carcinoma (HCC), and death. Multivariable Cox proportional hazards regression models were used to determine the association between diabetes and/or obesity and outcomes. RESULTS: During a mean follow-up of 3 years, 10.1% patients died, 5.0% were newly diagnosed with cirrhosis, 4.7% had a decompensation and 4.0% developed HCC. Diabetes was associated with an increased risk of mortality (AHR = 1.25, 95% CI 1.10-1.42), cirrhosis (AHR = 1.31, 95% CI 1.16-1.48), decompensation (AHR = 1.74, 95% CI 1.31-2.31), and HCC (AHR = 1.32, 95% CI 1.01-1.72) among patients without baseline cirrhosis. Compared to normal-weight persons, obese persons had a higher risk of cirrhosis, but overweight and obese persons had lower risk of mortality and HCC. CONCLUSIONS: In this large DAA-treated Veterans cohort, pre-DAA diabetes increases mortality and liver-related events independent of SVR. Continued vigilance is warranted in patients with diabetes despite SVR. Elevated BMI categories appear to have improved outcomes, although further studies are needed to understand those associations.

The IBD-associated long noncoding RNA IFNG-AS1 regulates the balance between inflammatory and anti-inflammatory cytokine production after T-cell stimulation.

The inflammatory bowel diseases (IBD) are a complex set of chronic gastrointestinal inflammatory conditions arising from the interplay of genetic and environmental factors. This study focuses on noncoding RNA transcripts as potential mediators of IBD pathophysiology. One particular gene, interferon γ-antisense 1 (IFNG-AS1), has been consistently observed to be elevated in the intestinal mucosa of patients with actively inflamed IBD versus healthy controls. This study builds on these observations, demonstrating that the second splice variant is specifically altered, and this alteration even stratifies within inflamed patients. With the use of a CRISPR-based overexpression system, IFNG-AS1 was selectively overexpressed directly from its genomic loci in T cells. An unbiased mRNA array on these cells identified a large increase in many inflammatory cytokines and a decrease in anti-inflammatory cytokines after IFNG-AS1 overexpression. Media from T cells overexpressing IFNG-AS1 elicited an inflammatory signaling cascade in primary human peripheral blood mononuclear cells, suggesting the potential functional importance of IFNG-AS1 in IBD pathophysiology. The significance of these results is amplified by studies suggesting that a single-nucleotide polymorphism in IFNG-AS1, rs7134599, was associated with both subtypes of patients with IBD independently of race.NEW & NOTEWORTHY Long noncoding RNAs are an emerging field of inflammatory bowel disease (IBD) research. This study mechanistically analyzes the role of a commonly upregulated gene in IBD and shows IFNG-AS1 as a mediator of an inflammatory signaling cascade.

Casting a Wider NET: An Unusual Cause of Acute Liver Failure in a Pregnant Patient.

We present a case patient in her second trimester of pregnancy who developed acute liver failure from metastatic neuroendocrine tumor (NET). Although she underwent prompt induction of a non-viable fetus due to initial concerns of hemolysis, elevated liver enzymes, and low platelet count syndrome, her liver function continued to deteriorate postpartum. She was subsequently transferred to our institution in order to undergo further evaluation that included a transjugular liver biopsy and subsequent diagnosis of high-grade NET. She was given salvage carboplatin-based chemotherapy, as she was not a liver transplant candidate. Unfortunately, the patient expired from cardiovascular collapse as a component of multiorgan failure.

Generalized Cytokine Increase in the Setting of a Multisystem Clinical Disorder and Carcinoid Syndrome Associated with a Novel NLRP12 Variant.

BACKGROUND: Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are a group of cytoplasmic sensors that survey danger signals released by invading pathogens or damaged tissue. Mutations in the NLRP subfamily affect pro-inflammatory mediators and cause nonspecific systemic symptoms. AIMS: We sought to identify a potential genetic etiology of an inflammatory syndrome in a patient that presented with an atypical multisystem illness with carcinoid syndrome as well as atopic and autoimmune features. METHODS: Exome sequencing was performed using the Agilent SureSelect Clinical Research Exome XT kit on an Illumina HiSeq 2500. Longitudinal monitoring of pro-inflammatory cytokines was performed. RESULTS: We identified a novel variant (heterozygous c.536C > T [p.Thr179Ile]) in the NLRP12 gene in a 63-year-old woman and her daughter, who presented with an unusual clinical syndrome that differs from autoinflammatory disorders previously reported in association with the NLRP subfamily gene mutations. This NLRP12 variant was predicted to be pathogenic by functional analysis through Hidden Markov Models (FATHMM). Both the mother and the daughter had episodes of abdominal pain, fever, diarrhea, skin rash, hypothyroidism, and elevated urine 5-hydroxyindoleacetic acid (5-HIAA) levels. The proband also had elevated serum levels of pro-inflammatory (IL-1ß, IL-6, IL-12, and TNF-α), Th1 (IL-2, IFN-γ), and Th2 (IL-4, IL-5, IL-13) cytokines, but not of Th17 (IL-17) and IL-10. CONCLUSION: This report adds to the expanding spectrum of clinical manifestations attributed to the NLRP subfamily gene variants and suggests a role of NLRP12 in the regulation of multiple cytokines.

Microbiome and bile acid profiles in duodenal aspirates from patients with liver cirrhosis: The Microbiome, Microbial Markers and Liver Disease Study.

AIM: Cirrhosis is a leading cause of death worldwide, yet there are no well-established risk stratifying tools for lethal complications, including hepatocellular carcinoma (HCC). Patients with liver cirrhosis undergo routine endoscopic surveillance, providing ready access to duodenal aspirate samples that could be a source for identifying novel biomarkers. The aim of this study was to characterize the microbiome and bile acid profiles in duodenal aspirates from patients with liver cirrhosis to assess the feasibility of developing biomarkers for HCC risk stratification. METHODS: Thirty patients with liver cirrhosis were enrolled in the Microbiome, Microbial Markers, and Liver Disease study between May 2015 and March 2017. Detailed clinical and epidemiological data were collected at baseline and at 6-monthly follow-up visits. Duodenal aspirate fluid was collected at baseline for microbial characterization using 16S ribosomal RNA sequencing and bile acid quantification using mass spectroscopy. RESULTS: Alcohol-related cirrhosis was associated with reductions in the Bacteroidetes phylum, particularly Prevotella (13-fold reduction), and expansion of Staphylococcus (13-fold increase), compared to hepatitis C virus-related cirrhosis. Participants with hepatic encephalopathy (HE) had less microbial diversity compared to patients without HE (P < 0.05), and were characterized by expansion of Mycobacterium (45-fold increase) and Gram-positive cocci including Granulicatella (3.1-fold increase), unclassified Planococcaceae (3.3-fold increase), and unclassified Streptococcaceae (4.5-fold increase). Non-Hispanic White patients had reduced microbial richness (P < 0.01) and diversity (P < 0.05), and increased levels of conjugated ursodeoxycholic acid (glycoursodeoxycholic acid and tauroursodeoxycholic acid, P < 0.05) compared to Hispanic patients. CONCLUSION: Microbial profiles of duodenal aspirates differed by cirrhosis etiology, HE, and Hispanic ethnicity.

Gastrointestinal Manifestations of Hereditary Hemorrhagic Telangiectasia (HHT): A Systematic Review of the Literature.

Hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu syndrome, is an autosomal dominant genetic disease that affects the vasculature of numerous organs. The prevalence of HHT is estimated to be between 1.5 and 2 persons per 10,000. While there is still much to learn about this condition, there is an increasing understanding its underlying pathophysiology, genetic basis, presentations, and management. Recognizing that the clinical manifestations of HHT can involve a number of organ systems will provide clinicians with a higher index of suspicion for the disease. This early diagnosis and genotyping can greatly reduce mortality for a patient with HHT through appropriate screening for complications. This review will focus on the gastrointestinal manifestations of HHT and how these can dictate treatment and prognosis.

Liver X receptors balance lipid stores in hepatic stellate cells through Rab18, a retinoid responsive lipid droplet protein.

UNLABELLED: Liver X receptors (LXRs) are determinants of hepatic stellate cell (HSC) activation and liver fibrosis. Freshly isolated HSCs from Lxrαß(-/-) mice have increased lipid droplet (LD) size, but the functional consequences of this are unknown. Our aim was to determine whether LXRs link cholesterol to retinoid storage in HSCs and how this impacts activation. Primary HSCs from Lxrαß(-/-) and wild-type mice were profiled by gene array during in vitro activation. Lipid content was quantified by high-performance liquid chromatography and mass spectroscopy. Primary HSCs were treated with nuclear receptor ligands, transfected with small interfering RNA and plasmid constructs, and analyzed by immunocytochemistry. Lxrαß(-/-) HSCs have increased cholesterol and retinyl esters. The retinoid increase drives intrinsic retinoic acid receptor signaling, and activation occurs more rapidly in Lxrαß(-/-) HSCs. We identify Rab18 as a novel retinoic acid-responsive, LD-associated protein that helps mediate stellate cell activation. Rab18 mRNA, protein, and membrane insertion increase during activation. Both Rab18 guanosine triphosphatase activity and isoprenylation are required for stellate cell LD loss and induction of activation markers. These phenomena are accelerated in Lxrαß(-/-) HSCs, where there is greater retinoic acid flux. Conversely, Rab18 knockdown retards LD loss in culture and blocks activation, just like the functional mutants. Rab18 is also induced with acute liver injury in vivo. CONCLUSION: Retinoid and cholesterol metabolism are linked in stellate cells by the LD-associated protein Rab18. Retinoid overload helps explain the profibrotic phenotype of Lxrαß(-/-) mice, and we establish a pivotal role for Rab18 GTPase activity and membrane insertion in wild-type stellate cell activation. Interference with Rab18 may have significant therapeutic benefit in ameliorating liver fibrosis.

Impact of GeneXpert MTB/RIF on patients and tuberculosis programs in a low-burden setting. a hypothetical trial.

RATIONALE: Guidelines recommend routine nucleic-acid amplification testing in patients with presumed tuberculosis (TB), but these tests have not been widely adopted. GeneXpert MTB/RIF (Xpert), a novel, semiautomated TB nucleic-acid amplification test, has renewed interest in this technology, but data from low-burden countries are limited. OBJECTIVES: We sought to estimate Xpert's potential clinical and public health impact on empiric treatment, contact investigation, and housing in patients undergoing TB evaluation. METHODS: We performed a prospective, cross-sectional study with 2-month follow-up comparing Xpert with standard strategies for evaluating outpatients for active pulmonary TB at the San Francisco Department of Public Health TB Clinic between May 2010 and June 2011. We calculated the diagnostic accuracy of standard algorithms for initial empiric TB treatment, contact investigation, and housing in reference to three Mycobacterium tuberculosis sputum cultures, as compared with that of a single sputum Xpert test. We estimated the incremental diagnostic value of Xpert, and the hypothetical reductions in unnecessary treatment, contact investigation, and housing if Xpert were adopted to guide management decisions. MEASUREMENTS AND MAIN RESULTS: A total of 156 patients underwent Xpert testing. Fifty-nine (38%) received empiric TB treatment. Thirteen (8%) had culture-positive TB. Xpert-guided management would have hypothetically decreased overtreatment by 94%, eliminating a median of 44 overtreatment days (interquartile range, 43-47) per patient and 2,169 total overtreatment days (95% confidence interval, 1,938-2,400) annually, without reducing early detection of TB patients. We projected similar benefits for contact investigation and housing. CONCLUSIONS: Xpert could greatly reduce the frequency and impact of unnecessary empiric treatment, contact investigation, and housing, providing substantial patient and programmatic benefits if used in management decisions.