Quantitative plasma proteomics identifies metallothioneins as a marker of acute-on-chronic liver failure associated acute kidney injury

Evaluation of Acute Kidney Injury (AKI) Biomarkers FABP1, NGAL, Cystatin C and IL-18 in an Indian Cohort of Hospitalized Acute-on-chronic Liver Failure (ACLF) Patients

Background/Aims

Acute-on-chronic liver failure (ACLF) is a complication of cirrhosis associated with systemic inflammation and organ dysfunction. In ACLF, the development of acute kidney injury (AKI) is associated with poor outcomes. FABP1, NGAL, Cys C and IL-18 have been shown to correlate with ACLF severity and mortality. Hence, our study aimed to evaluate the association of these biomarkers with organ dysfunctions, particularly AKI, in an Indian ACLF patient cohort.

Methods

151 study participants including ACLF (n = 91; with AKI n = 63, no-AKI n = 28), non-liver AKI (n = 30) and healthy controls (n = 30) were recruited. Serum ELISA was performed for biomarker estimation. Data interpolation and graphical representation were performed using GraphPad Prism and statistical analyses performed using STATA 14.0.

Results

FABP1 and Cys C levels were higher in ACLF-AKI patients compared to ACLF no-AKI (P-value ≤ 0.0005). Serum Cys C levels were significantly increased in non-liver AKI compared to ACLF-AKI (P-value ≤ 0.001). AUROC analysis showed better performance of Cys C (AUC 0.79; 95% CI (0.68-0.89)) compared to serum creatinine (AUC 0.71; 95% CI (0.61-0.82)) in discriminating AKI and no-AKI. Correlation analysis revealed positive correlations of FABP1 with creatinine and urea, Cys C with creatinine, urea and OF-Kidney, NGAL, and IL-18 with general markers of organ dysfunction. Plasma MTs) measured in a subset of ACLF patients were elevated in progression-to-AKI.

Conclusion

Our study showed that in an Indian population of ACLF patients with a high short-term mortality, serum Cys C and FABP1 were elevated in ACLF-AKI, however did not have predictive potential for ACLF-AKI. Cys C levels were significantly higher in non-liver AKI patients vs. ACLF-AKI and correlated with markers of kidney dysfunction whereas NGAL and IL-18 represented higher inflammation and total organ dysfunction. Hence, we conclude that these biomarkers were elevated in ACLF-AKI but did not have predictive potential for AKI in ACLF.

Exposure of Bisphenols (BPA, BPB and BPC) in HepG2 Cells Results in Lysosomal Dysfunction and Lipid Accumulation

Nonalcoholic fatty liver disease poses a significant public health concern, as do the issues surrounding plastic usage. The bisphenols are reported to cause fat accumulation in the liver. However, literature is scanty about the effect of bisphenols on lysosomes or lysosomal functions. We predicted the interaction of bisphenols with lysosomal proteins available in the online databases using in silico tools. Molecular docking revealed that chosen Bisphenols interact with critical lysosomal proteins including lipid hydrolyzing enzymes. Following exposure of BPA, BPB and BPC to HepG2 cells fat accumulation and lysosomal functions were evaluated. Exposure to BPB and BPC results intracellular fat accumulation under experimental conditions like BPA. All three Bisphenols disturb lysosomal homeostasis perhaps by different mechanisms. Overall our results suggest that Bisphenols can also cause fat accumulation in liver by disturbing lysosomal homeostasis.

Identification of proteins related to SIS3 by iTRAQ and PRM-based comparative proteomic analysis in cisplatin-induced acute kidney injury

Background

Cisplatin is a commonly used nephrotoxic drug and can cause acute kidney injury (AKI). In the present study, isobaric tags for relative and absolute quantification (iTRAQ) and parallel reaction monitoring (PRM)-based comparative proteomics were used to analyze differentially expressed proteins (DEPs) to determine the key molecular mechanism in mice with cisplatin-induced AKI in the presence or absence of SIS3, a specific p-smad3 inhibitor, intervention.

Methods

The cisplatin-induced AKI mouse model was established and treated with SIS3. We used iTRAQ to search for DEPs, PRM to verify key DEPs and combined Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for bioinformatics analysis. We then assessed lipid deposition, malondialdehyde (MDA) and reactive oxygen species (ROS) and detected the expression of SREBF1, SCD1, CPT1A, PPARα and NDRG1 in vitro.

Results

Proteomic analysis showed that the identified DEPs were mainly enriched in energy metabolism pathways, especially in lipid metabolism. When SIS3 was applied to inhibit the phosphorylation of Smad3, the expression of NDRG1 and fatty acid oxidation key proteins CPT1A and PPARα increased, the expression of lipid synthesis related proteins SREBF1 and SCD1 decreased and the production of lipid droplets, MDA and ROS decreased.

Conclusion

SIS3 alleviates oxidative stress, reduces lipid accumulation and promotes fatty acid oxidation through NDRG1 in cisplatin-induced AKI. Our study provides a new candidate protein for elucidating the molecular mechanisms of fatty acid metabolism disorders in cisplatin-induced acute kidney injury.

Technical report: The clinically useful selection of proteins protocol: An approach to identify clinically useful proteins for validation

Clinical proteomics studies aiming to develop markers of clinical outcome or disease typically involve distinct discovery and validation stages, neither of which focus on the clinical applicability of the candidate markers studied. Our clinically useful selection of proteins (CUSP) protocol proposes a rational approach, with statistical and non-statistical components, to identify proteins for the validation phase of studies that could be most effective markers of disease or clinical outcome. Additionally, this protocol considers commercially available analysis methods for each selected protein to ensure that use of this prospective marker is easily translated into clinical practice. SIGNIFICANCE: When developing proteomic markers of clinical outcomes, there is currently no consideration at the validation stage of how to implement such markers into a clinical setting. This has been identified by several studies as a limitation to the progression of research findings from proteomics studies. When integrated into a proteomic workflow, the CUSP protocol allows for a strategically designed validation study that improves researchers' abilities to translate research findings from discovery-based proteomics into clinical practice.

Growing Evidence for Survival Benefit with Plasma Exchange to Treat Liver Failure

Plasma exchange (PLEX) to treat liver failure patients is gaining increasing momentum in recent years. Most reports have used PLEX to treat patients with acute liver failure (ALF) or acute on chronic liver failure (ACLF). Etiology of liver disease has an important bearing on the prognosis of the illness in these patients. The accruing data suggest survival benefit with PLEX compared with standard medical treatment to treat ALF and ACLF patients, in randomised controlled trials done world-over. The American College of Apheresis now recommends high-volume PLEX as first-line treatment for ALF patients. Most matched cohort studies done from India which recruited patients with a specific etiology of ALF or ACLF report survival benefit with PLEX compared to standard medical treatment. The survival benefit with PLEX appears more pronounced in ALF patients rather than in ACLF patients. Systematic analysis of the efficacy of PLEX to treat ALF and ACLF patients is needed. There is also a need to identify dynamic predictive scores to assess which patients with ALF or ACLF will respond to PLEX.