Proteomics Indicates Lactate Dehydrogenase is Prognostic in Acetaminophen-induced Acute Liver Failure Patients and Reveals a Role for LKB1-AMPK Signaling

ABSTRACT Better biomarkers to predict death early in acute liver failure (ALF) are needed. To that end, we obtained early (study day 1) and later (day 3) serum samples from transplant-free survivors (n=28) and non-survivors (n=30) of acetaminophen (APAP)-induced ALF from the NIH-sponsored Acute Liver Failure Study Group, and from control volunteers (n=10). To identify proteins that increase early in serum during ALF, we selected individuals from this cohort for whom ALT was lower on day 1 than day 3, indicating a time point before the peak of injury (n=10/group). We then performed untargeted proteomics on their day 1 samples. Out of 1,682 quantifiable proteins, 79 were elevated ≥4-fold in ALF patients vs. controls and 23 of those were further elevated ≥4-fold in non-survivors vs. survivors, indicating potential to predict death. Interestingly, the biomarker with best performance was LDH. To confirm the prognostic potential of LDH, we measured activity in all day 1 and 3 samples from all 58 ALF patients. LDH was elevated in the non-survivors vs. survivors on both days. In addition, receiver operating characteristic (ROC) curve analyses revealed that LDH alone performed similarly to the model for end-stage liver disease (MELD), while a combination of MELD and LDH outperformed either alone. Finally, Upstream Analysis of our proteomics data indicated activation of LKB1-AMPK signaling in liver regeneration after APAP overdose and we confirmed that in mice. Overall, we conclude LDH can predict death in APAP-induced ALF and that LKB1-AMPK signaling may be a promising therapeutic target to improve survival.