# Serum proteomics of adults with acute liver failure provides mechanistic insights and attractive prognostic biomarkers

## TL;DR

This study uses serum proteomics to identify biomarkers that distinguish acetaminophen-related from non-acetaminophen-related acute liver failure and predict patient survival.

## Contribution

The study identifies novel, reproducible proteomic biomarkers that improve prognostication and understanding of ALF etiology.

## Key findings

- Three hepatocellular proteins (ALDOB, CAT, and PIGR) reliably distinguish APAP-related from non-APAP-related ALF.
- SERPINA1 and LRG1 are strong predictors of 21-day transplant-free survival.
- Proteomic models outperformed existing prognostic scores for ALF outcomes.

## Abstract

Acute liver failure (ALF) is defined as rapid onset coagulopathy and encephalopathy in patients without a prior history of liver disease. We performed untargeted and targeted serum proteomics to delineate processes occurring in adult patients with ALF and to identify potential biomarkers.

Sera of 319 adult patients with ALF (∼50% acetaminophen [APAP]-related cases) were randomly selected from admission samples of the multicenter USA Acute Liver Failure Study Group consortium and subdivided into discovery/validation cohorts. They were analyzed using untargeted proteomics with mass spectroscopy and a serum cytokine profiling and compared with 30 healthy controls. The primary clinical outcome was 21-day transplant-free survival. Single-cell RNAseq data mapped biomarkers to cells of origin; functional enrichment analysis provided mechanistic insights. Novel prognostic scores were compared with the model for end-stage liver disease and ALFSG prognostic index scores.

In the discovery cohort, 117 proteins differed between patients with ALF and healthy controls. There were 167 proteins associated with APAP-related ALF, with the majority being hepatocyte-derived. Three hepatocellular proteins (ALDOB, CAT, and PIGR) robustly and reproducibly discriminated APAP from non-APAP cases (AUROCs ∼0.9). In the discovery cohort, 37 proteins were related to 21-day outcome. The key processes associated with survival were acute-phase response and hepatocyte nuclear factor 1α signaling. SERPINA1 and LRG1 were the best individual discriminators of 21-day transplant-free survival in both cohorts. Two models of blood-based proteomic biomarkers outperformed the model for end-stage liver disease and ALFSG prognostic index and were reproduced in the validation cohort (AUROCs 0.83-0.86) for 21-day transplant-free survival.

Proteomics and cytokine profiling identified new, reproducible biomarkers associated with APAP etiology and 21-day outcome. These biomarkers may improve prognostication and understanding of the etiopathogenesis of ALF but need to be independently validated.

Acute liver failure (ALF) is a sudden, and severe condition associated with high fatality. More sensitive and specific prognostic scores are urgently needed to facilitate decision-making regarding liver transplantation in patients with ALF. Our proteomic analysis uncovered marked differences between acetaminophen and non-acetaminophen-related ALF. The identification of routinely measurable biomarkers that are associated with 21-day transplant-free survival and the derivation of novel prognostic scores may facilitate clinical management as well as decisions for/against liver transplantation. Further studies are needed to quantify less abundant proteins. Although we used two cohorts, our findings still need to be independently and prospectively validated.

Image 1

•Hepatocellular injury markers such as aldolase B reliably distinguish between APAP and non-APAP-related ALF.•Acute-phase response and nuclear factor 1α signaling emerge as key processes associated with ALF outcome.•Proteomic assessment improves the understanding of etiopathogenesis in ALF and identifies novel, biologically plausible biomarkers.

Hepatocellular injury markers such as aldolase B reliably distinguish between APAP and non-APAP-related ALF.

Acute-phase response and nuclear factor 1α signaling emerge as key processes associated with ALF outcome.

Proteomic assessment improves the understanding of etiopathogenesis in ALF and identifies novel, biologically plausible biomarkers.