Simultaneous quantification of six proteins related to liver injury using nano liquid chromatography-tandem mass...

In clinical diagnosis of liver injury, which is an important health concern, serum aminotransferase assays have been the go-to method used worldwide. However, the measurement of serum enzyme activity has limitations, including inadequate disease specificity and enzyme specificity.

With the high selectivity and specificity provided by nano liquid chromatography-tandem mass spectrometry (LC/MS/MS), this work describes a method for the simultaneous determination of six proteins in liver that can be potentially used as biomarkers for liver injury: glutamic-pyruvic transaminase 1 (GPT1), glutamic oxaloacetic transaminase 1 (GOT1), methionine adenosyl transferase 1A (MAT1A), glutathione peroxidase 1 (GPX1), cytokeratin 18 (KRT18) and apolipoprotein E (APOE).

In validation, the method was shown to have good selectivity and sensitivity (limits of detection at pg/mL level). The analytical method revealed that, compared with normal mice, in carbon tetrachloride-induced acute liver injury mice, liver MAT1A and GPX1 were significantly lower (p < 0.01 and p < 0.05, respectively), KRT18 was significantly higher (p < 0.05) and APOE and GPT1 were marginally significantly lower (p between 0.05 and 0.1). This is the first work reporting the absolute contents of GPT1, GOT1, MAT1A, GPX1 and KRT18 proteins based on LC/MS.

The proposed method provides a basis for establishing more specific diagnostic indicators of liver injury.