Identification of Serum Protein Biomarkers in Biliary Atresia by Mass Spectrometry and Enzyme-Linked Immunosorbent Assay.

Objective: There is an urgent need to identify noninvasive and convenient biomarkers for early diagnosis of biliary atresia (BA). The aim of the present study was to identify potential protein biomarkers for BA.Methods: Serum samples from 42 infants with BA, 38 infants with non-BA neonatal cholestasis (NC), and 36 healthy controls (HC) were randomly divided into a training set and a test set. Serum proteomic profiles were measured using surface-enhanced desorption/ionization time-of-flight mass spectrometry. Candidate biomarkers were purified using high-performance liquid chromatography, identified using liquid chromatography tandem mass spectrometry, and validated using enzyme-linked immunosorbent assay.Results: A total of 2 protein peaks (m/z with 8697 and 9098 Da) with differential expression levels were found using surface-enhanced desorption/ionization time-of-flight mass spectrometry. These peaks were then analyzed by a support vector machine to construct a classification model in the training set. The sensitivity and specificity of the model were 94.1% and 91.8%, respectively, in the test set. One candidate biomarker (9098 Da) was identified as Apo C-II, and was found to be downregulated in BA samples compared with HC samples, and upregulated in BA samples compared with NC samples. The other candidate biomarker (8697 Da) was identified as Apo C-III, and was found to be upregulated in BA compared with NC and HC.Conclusions: Apo C-II and Apo C-III may be potential protein biomarkers of BA and may be useful in distinguishing infants with BA from healthy and NC infants. Further studies with additional populations or using prediagnostic serum are needed to confirm the importance of these findings as diagnostic markers of infants with BA.