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OBJECTIVESIn the United States, the Acute Liver Failure Study Group (ALFSG) registry lists approximately 11% of cases as of indeterminate etiology (IND-ALF) as determined by the respective local site principal investigator (PI). Traditionally, IND-ALF has prompted concern that other viruses or toxins might be implicated. We hypothesized that many IND- ALF cases would have an identifiable etiology upon further investigation. Improving the identification process should reduce the number of truly indeterminate cases.MethodsSpecific definitions for each etiology (“etiology-specific algorithms”) were developed by a Causality Adjudication Committee that included six reviewers (each with 20 or more years of experience). Of 2718 patients with ALF, 303 initially deemed IND-ALF by site PIs underwent committee review guided by the algorithms. Acetaminophen (APAP) protein adducts were measured in sera when available, additional HEV testing was performed, and viral sequences sought by microarray analysis and metagenomic next-generation sequencing (mNGS). Study sites were asked to provide liver biopsy and/or explant reports and to update serological findings not reported previously.ResultsNearly half (142, 46.9%) of the 303 IND-ALF cases could be reassigned to a single, defined etiology and rated as highly likely or probable; 11 additional cases, upon review, did not meet ALF criteria. Amongst reassigned etiologies, 45 were previously unrecognized APAP, 34 autoimmune hepatitis (AIH), 24 drug-induced liver injury (DILI), 13 various viral causes, 12 ischemia, and 14 miscellaneous other etiologies. The remaining 150, deemed true IND-ALF, represented just 5.5%.ConclusionsThe indeterminate etiology in ALF includes patients with a diagnosis that is discernible after closer examination. Revision of etiologic diagnoses of indeterminate cases using added testing and expert opinion is useful in understanding all aspects of ALF.

Regenerative medicine is energizing and empowering basic science and has the potential to dramatically transform health care in the future. Given the remarkable intrinsic regenerative properties of the liver, as well as widespread adoption of regenerative strategies for liver disease (eg, liver transplant, partial hepatectomy, living donor transplant), hepatology has always been at the forefront of clinical regenerative medicine. However, an expanding pool of patients awaiting liver transplant, a limited pool of donor organs, and finite applicability of the current surgical approaches have created a need for more refined and widely available regenerative medicine strategies. Although cell-based therapies have been used extensively for hematologic malignant diseases and other conditions, the potential application of cellular therapy for acute and chronic liver diseases has only more recently been explored. New understanding of the mechanisms of liver regeneration and repair, including activation of local stem/progenitor cells and contributions from circulating bone marrow–derived stem cells, provide the theoretical underpinnings for the rational use of cell-based therapies in clinical trials. In this review, we dissect the scientific rationale for various modalities of cell therapy for liver diseases being explored in animal models and review those tested in human clinical trials. We also attempt to clarify some of the important ongoing questions that need to be addressed in order to bring these powerful therapies to clinical translation. Discussions will cover transplant of hepatocytes and liver stem/progenitor cells as well as infusion or stimulation of bone marrow–derived stem cells. We also highlight tremendous scientific advances on the horizon, including the potential use of induced pluripotent stem cells and their derivatives as individualized regenerative therapy for liver disease.

Background and AimsAcetaminophen (APAP) hepatotoxicity and ischemic hepatic injury (IH) demonstrate remarkably similar biochemical patterns. Deciding between these two etiologies in the setting of acute liver failure (ALF) can be challenging. We reviewed all cases in the Acute Liver Failure Study Group (ALFSG) registry where these diagnoses were considered, to determine reasons for, and frequency of, difficulties making these diagnoses. We hypothesized that the newly developed APAP-CYS adduct assay could help in discerning the correct diagnosis.MethodsAmong 3364 patients with ALF or acute liver injury (ALI: INR ≥ 2.0 but without encephalopathy) between 1998 and 2019, 1952 (58%) received a final diagnosis of either APAP (1681) or IH (271). We utilized a review committee of senior hepatologists as well as the APAP-CYS assay (where sera were available), measuring the presence of toxic by-products of APAP injury to optimize adjudication.ResultsWith these methods, a total of 575 adduct positive APAP cases included 488 recognized APAP, as well as an additional 87 patients previously diagnosed as other etiologies. Nine cases initially attributed to IH were deemed combination APAP-IH injuries. Conversely, 215 of the 280 IH subjects tested for adducts disclosed 173 confirmed as IH with adduct testing below the toxicity threshold, while 9 cases were revised from APAP to the IH-APAP combination phenotype, where both hypotension and APAP likely played a role.ConclusionsDiscerning APAP from IH can be difficult—in rare cases, combined injury is observed (18/1952). APAP-CYS testing resulted in revising the diagnosis in 14.6% of cases.

There has been a growing interest in identifying prognostic biomarkers that alone or with available prognostic models (King’s College Criteria, KCC; MELD and ALFSG Prognostic Index) would improve prognosis in acute liver failure (ALF) patients being assessed for liver transplantation. The Acute Liver Failure Study Group (ALFSG) has evaluated 15 potential prognostic biomarkersserum AFP; apoptosis-associated proteins; serum actin-free Gc-globulin; serum glycodeoxycholic acid; sRAGE/RAGE ligands; plasma osteopontin; circulating MBL, M-, L-, H-ficolin and CL-1; plasma galectin-9; serum FABP1; serum Lct2; miRNAs; factor V; thrombocytopenia, and sCD163. The ALFSG also has reported on 4 susceptibility biomarkerskeratins 8 and 18 (K8/K18) gene variants; polymorphisms of genes encoding putative APAP-metabolizing enzymes ( UGT1A1 , UGT 1A0 , UGT 2B15 , SULT1A1 , CYP2E1 , and CYP3A5 ) as well as CD44 and BHMT1 ; single nucleotide polymorphisms (SNPs) of genes associated with human behavior, rs2282018 in the arginine vasopressin ( AVP ) gene and rs11174811 in the AVP receptor 1A gene. Finally, rs2277680 of the CSCL16 gene in HBV-ALF patients. In conclusion, we have reviewed the prognostic and susceptibility biomarkers studied by the ALFSG. We suggest that a better approach to predicting the clinical outcome of an ALF patient will require a combination of biomarkers of pathogenic processes such as cell death, hepatic regeneration, and degree of inflammation that could be incorporated into prognostic models such as KCC, MELD or ALFSG PI.

In the FAQ page of this software, it recommends not switching from version 2: “The gnomAD v2 call set contains fewer whole genomes than v3 but also contains a very large number of exomes that substantially increase its power as a reference in coding regions. [...]gnomAD v2 is still our recommended dataset for most coding regions analyses” (https://gnomad.broadinstitute.org/faq#should-i-switch-to-the-latest-version-of-gnomad). ExAC (r0.3_GRCh38: 60,706 unrelated individuals from 17 disease-specific and population genetic studies, excluding individuals affected by a severe pediatric disease) 1000G (20130502_GRCh38: integrated set of SNPs, indels, MNPs, long insertions and deletions, copy number variations, and other types of structural variations discovered and genotyped in 2,504 unrelated individuals), and Mayo Clinic Biobank (funded by a Mayo Clinic initiative for Individualized Medicine to assist investigators throughout the institution in obtaining “normal” samples to serve as controls for their patient populations, 982 whole genome samples) Furthermore, as explained in our study, we divided 26 patients into the following 2 groups: 8 patients who survived spontaneously from their acute liver failure (ALF) episode of indeterminate etiology and 18 patients with the same diagnosis who died or underwent liver transplant. See PDF] Given the small cohort size of our pilot study, we intend to expand our study to a larger population with ALF of indeterminate etiology and compare their variants distribution with patients with ALF associated with viral hepatitis, ALF associated with drug-induced liver injury, and autoimmune ALF.

INTRODUCTION:Indeterminate acute liver failure (IND-ALF) is a rare clinical syndrome with a high mortality rate. Lacking a known etiology makes rapid evaluation and treatment difficult, with liver transplantation often considered as the only therapeutic option. Our aim was to identify genetic variants from whole exome sequencing data that might be associated with IND-ALF clinical outcomes.METHODS:Bioinformatics analysis was performed on whole exome sequencing data for 22 patients with IND-ALF. A 2-tier approach was used to identify significant single-nucleotide polymorphisms (SNPs) associated with IND-ALF clinical outcomes. Tier 1 identified the SNPs with a higher relative risk in the IND-ALF population compared with those identified in control populations. Tier 2 determined the SNPs connected to transplant-free survival and associated with model for end-stage liver disease serum sodium and Acute Liver Failure Study Group prognostic scores.RESULTS:Thirty-one SNPs were found associated with a higher relative risk in the IND-ALF population compared with those in controls, of which 11 belong to the human leukocyte antigen (HLA) class II genes but none for the class I. Further analysis showed that 5 SNPs: rs796202376, rs139189937, and rs113473719 of HLA-DRB5; rs9272712 of HLA-DQA1; and rs747397929 of IDO1 were associated with a higher probability of IND-ALF transplant-free survival. Using 3 selected SNPs, a model for the polygenic risk score was developed to predict IND-ALF prognoses, which are comparable with those by model for end-stage liver disease serum sodium and Acute Liver Failure Study Group prognostic scores.DISCUSSION:Certain gene variants in HLA-DRB5, HLA-DQA1, and IDO1 were found associated with IND-ALF transplant-free survival. Once validated, these identified SNPs may help elucidate the mechanism of IND-ALF and assist in its diagnosis and management.

One promising goal for utilizing the molecular information circulating in biofluids is the discovery of clinically useful biomarkers. Extracellular RNAs (exRNAs) are one of the most diverse classes of molecular cargo, easily assayed by sequencing and with expressions that rapidly change in response to subject status. Despite diverse exRNA cargo, most evaluations from biofluids have focused on small RNA sequencing and analysis, specifically on microRNAs (miRNAs). Another goal of characterizing circulating molecular information, is to correlate expression to injuries associated with specific tissues of origin. Biomarker candidates are often described as being specific, enriched in a particular tissue or associated with a disease process. Likewise, miRNA data is often reported to be specific, enriched for a tissue, without rigorous testing to support the claim. Here we provide a tissue atlas of small RNAs from 30 different tissues and three different blood cell types. We analyzed the tissues for enrichment of small RNA sequences and assessed their expression in biofluids: plasma, cerebrospinal fluid, urine, and saliva. We employed published data sets representing physiological (resting vs. acute exercise) and pathologic states (early- vs. late-stage liver fibrosis, and differential subtypes of stroke) to determine differential tissue-enriched small RNAs. We also developed an online tool that provides information about exRNA sequences found in different biofluids and tissues. The data can be used to better understand the various types of small RNA sequences in different tissues as well as their potential release into biofluids, which should help in the validation or design of biomarker studies.

The increasing use of complementary and alternative medicines (CAMs) has been associated with a rising incidence of CAM-induced drug-induced liver injury (DILI). The aim of this study was to examine the clinical features and outcomes among patients with acute liver failure (ALF) and acute liver injury (ALI) enrolled in the Acute Liver Failure Study Group database, comparing CAM-induced with prescription medicine (PM)-induced DILI. A total of 2,626 hospitalized patients with ALF/ALI of any etiology were prospectively enrolled between 1998 and 2015 from 32 academic transplant centers. Only those with CAM or PM-induced ALI/ALF were selected for analysis. A total of 253 (9.6%) subjects were found to have idiosyncratic DILI, of which 41 (16.3%) were from CAM and 210 (83.7%) were due to PM. The fraction of DILI-ALF/ALI cases due to CAM increased from 1998-2007 to 2007-2015 (12.4 vs. 21.1%, P=0.047). There was no difference in the type of liver injury-hepatocellular, cholestatic, or mixed-between groups as determined by R score (P=0.26). PM-induced DILI showed higher serum alkaline phosphatase levels compared with the CAM group (median IU/L, 171 vs. 125, P=0.003). The CAM population had fewer comorbid conditions (1.0 vs. 2.0, P<0.005), higher transplantation rates (56 vs. 32%, P<0.005), and a lower ALF-specific 21-day transplant-free survival (17 vs. 34%, P=0.044). CAM-induced DILI is at least as severe in presentation as that observed due to PM with higher rates of transplantation and lower transplant-free survival in those who progress to ALF. This study highlights the increasing incidence of CAM-induced liver injury and emphasizes the importance of early referral and evaluation for liver transplantation when CAM-induced liver injury is suspected.

When hepatitis C virus (HCV) infection recurs after liver transplantation, it is unclear whether the liver graft is colonized by virions present in the circulation or by those associated with peripheral blood mononuclear cells (PBMC). In 6 HCV-infected transplant recipients, HCV sequences were analyzed by the single-strand conformational polymorphism (SSCP) assay and direct sequencing in pretransplant-paired PBMC and serum samples and in posttransplant follow-up serum samples. In 2 patients, SSCP patterns for pretransplant PBMC-serum pairs were identical, while in 4 patients they were different. In 3 patients from the latter group, the posttransplant viral sequences resembled those found in pretransplant serum samples, whereas in the other patient from that group, viral sequences after transplantation were transiently identical to those found in pretransplant PBMC. In HCV-positive liver transplant recipients, the liver graft is colonized primarily by liver-derived virus remaining in the circulation. However, virus variants of likely extrahepatic origin can be detected in serum early after transplantation.

Background. Hepatitis C virus (HCV)–infected women—in particular, those coinfected with human immunodeficiency virus type 1 (HIV‐1)—can transmit infection to their children and sex partners. Methods. The present study was conducted to analyze the presence of HCV RNA in cervicovaginal lavage (CVL) fluid from 71 women (58 HCV/HIV‐1–coinfected women and 13 HCV‐infected, HIV‐1–uninfected women) enrolled in the Women’s Interagency HIV Study. Results. HCV RNA was detected (by a commercial polymerase chain reaction assay) in CVL fluid from 18 (29%) of the HIV‐1–infected women and from none of the HIV‐1–uninfected women (P<.05). Multivariate analysis revealed that risk factors for the presence of HCV RNA in CVL fluid were HCV viremia (odds ratio [OR], 16.81; P=.02) and HIV‐1 RNA in CVL fluid (OR, 19.87; P=.02). This observation suggests local interactions between HIV‐1 and HCV in the genital tract compartment. There was no correlation between HCV RNA in CVL fluid and CD4, CD8, or CD3 cell counts, HIV‐1 RNA viremia, the number of leukocytes in CVL fluid, or HIV‐1 therapy. Furthermore, in 3 of 5 analyzed patients who had a detectable CVL HCV RNA load, we found viral variants differing in the 5′ untranslated region that were present neither in plasma nor in peripheral‐blood mononuclear cells. Conclusions. Our observations point to the importance of the genital tract compartment, in which local HCV replication could be facilitated by local HIV‐1 replication.