New biomarkers of liver injury are required in the clinic and in preclinical pharmaceutical evaluation. Previous studies demonstrate that two liver-enriched microRNAs (miR-122 and miR-192) are promising biomarkers of acetaminophen-induced acute liver injury (APAP-ALI) in mice. We have examined these molecules, for the first time, in humans with APAP poisoning. Serum miR-122 and miR-192 were substantially higher in APAP-ALI patients, compared to healthy controls (median DDCt [25th, 75th percentile]) (miR-122: 1,265 [491, 4,270] and -192 were substantially higher in APAP-ALI patients than CKD patients (miR-122: P < 0.0001; miR-192: P < 0.0004). miR-122 correlated with peak ALT levels in the APAP-ALI cohort (Pearson R 5 0.46, P 5 0.0005), but not with prothrombin time. miR-122 was also raised alongside peak ALT levels in a group of patients with non-APAP ALI. Day 1 serum miR-122 levels were almost 2-fold higher in APAP-ALI patients who satisfied King's College Criteria (KCC), compared to those who did not satisfy KCC, although this did not reach statistical significance (P 5 0.15). Conclusion: This work provides the first evidence for the potential use of miRNAs as biomarkers of human drug-induced liver injury. (HEPATOLOGY 2011;54:1767-1776 T he development of informative biomarkers of drug-induced liver injury (DILI) remains a primary aim in clinical and preclinical settings. The challenge is to develop biomarkers that are stable, that can be rapidly and accurately quantified in standard hospital laboratories, are minimally invasive, tissue specific, and add true diagnostic/prognostic value to detect and monitor the level of a pathogenic insult to the liver.1 The current battery of available biomarkers to assess liver integrity includes circulating protein markers of hepatocellular injury, such as the aminotransferases, markers of liver functional impairment, such as prothrombin time, markers of blood chemistry, and a number of novel mechanistic biomarkers of tissue injury (e.g., cytokeratin-18 and high-mobility group box-1 protein). 2 Deficiencies discovered with current blood-based biomarkers include the unacceptable frequency of false positives/negatives, poor

Background & Aims Full length keratin-18 (FL-K18) and High Mobility Group Box-1 (HMGB1) represent circulating indicators of necrosis during acetaminophen (APAP) hepatotoxicity in vivo. In addition, the caspase-cleaved fragment of K18 (cK18) and hyper-acetylated HMGB1 represent serum indicators of apoptosis and immune cell activation respectively. The study aim was to assess their mechanistic utility to establish the balance between apoptosis, necrosis and immune cell activation throughout the time course of clinical APAP hepatotoxicity. Methods HMGB1 (total, acetylated) and K18 (apoptotic, necrotic) were identified and quantified by novel LC-MS/MS assays in APAP overdose patients (n=78). Results HMGB1 (total; 15.4±1.9ng/ml, p<0.01, acetylated; 5.4±2.6ng/ml, p<0.001), cK18 (5649.8±721.0U/l, p<0.01) and FL-K18 (54770.2±6717.0U/l, p<0.005) were elevated in the sera of APAP overdose patients with liver injury compared to overdose patients without liver injury and healthy volunteers. HMGB1 and FL-K18 correlated with alanine aminotransferase (ALT) activity (R2=0.60 and 0.58 respectively, p<0.0001) and prothrombin time (R2=0.62 and 0.71 respectively, p<0.0001). Increased total and acetylated HMGB1 and FL-K18 were associated with worse prognosis (King’s College Criteria) or patients that died/required liver transplant compared to spontaneous survivors (all p<0.05-0.001), a finding not reflected by ALT and supported by ROC analysis. Acetylated HMGB1 was a better predictor of outcome than the other markers of cell death. Conclusion K18 and HMGB1 represent blood-based tools to investigate the cell death balance clinical APAP hepatotoxicity. Activation of the immune response was seen later in the time course as shown by the distinct profile of acetylated HMGB1 and was associated with worse outcome.

Our objective was to identify microRNA (miRNA) biomarkers of drug-induced liver and kidney injury by profiling the circulating miRNome in patients with acetaminophen overdose. Plasma miRNAs were quantified in age- and sex-matched overdose patients with (N = 27) and without (N = 27) organ injury (APAP-TOX and APAP-no TOX, respectively). Classifier miRNAs were tested in a separate cohort (N = 81). miRNA specificity was determined in non-acetaminophen liver injury and murine models. Sensitivity was tested by stratification of patients at hospital presentation (N = 67). From 1809 miRNAs, 75 were 3-fold or more increased and 46 were 3-fold or more decreased with APAP-TOX. A 16 miRNA classifier model accurately diagnosed APAP-TOX in the test cohort. In humans, the miRNAs with the largest increase (miR-122-5p, miR-885-5p, miR-151a-3p) and the highest rank in the classifier model (miR-382-5p) accurately reported non-acetaminophen liver injury and were unaffected by kidney injury. miR-122-5p was more sensitive than ALT for reporting liver injury at hospital presentation, especially combined with miR-483-3p. A miRNA panel was associated with human kidney dysfunction. In mice, miR-122-5p, miR-151a-3p and miR-382-5p specifically reported APAP toxicity - being unaffected by drug-induced kidney injury. Profiling of acetaminophen toxicity identified multiple miRNAs that report acute liver injury and potential biomarkers of drug-induced kidney injury.

SUMMARY BackgroundAcute liver failure is a devastating clinical syndrome with a persistently high mortality rate despite critical care advances. Orthotopic liver transplantation (OLT) is a life-saving treatment in selected cases, but effective use of this limited resource requires accurate prognostication because of surgical risks and the requirement for subsequent life-long immunosuppression.

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