ELISA-based validation of differentially expressed Fibrinogen, S100A9, SERPINA3 and SERPINA6 proteins in Polycystic...

Polycystic ovary syndrome (PCOS) remains difficult to diagnose reliably, especially when clinical decisions rely heavily on ovarian morphology, which is often mis-interpreted. To address the need for more objective molecular indicators, we validated four serum proteins highlighted in earlier nLC-MS/MS based proteomic work, namely; Fibrinogen, S100A9, SERPINA3 and SERPINA6. The objective was to analyse differential expression of these proteins and evaluate the diagnostic performance by using ROC curves.

Blood samples were collected from Endocrinology clinic, Aga Khan University Hospital and further categorized into 2 groups of cases (44 infertile PCOS and 44 healthy control fertile females). Enzyme-Linked Immunosorbent Assay (ELISA) technique was used to validate proteins. SPSS (IBM SPSS 21) was used for statistical analysis whereas, GraphPad statistical software (v.8.02) was used to generate ROC curves.

Both PCOS and healthy control sample groups showed non-significant differences in age and BMI while significant difference was observed in FSH, LH and AMH levels. ELISA showed the similar pattern of expression profiling as mass spectrometric data. Fibrinogen and SERPINA6 concentrations were significantly higher in women with PCOS (p-value < 0.05), whereas S100A9 and SERPINA3 protein expression levels were significantly lower (p-value < 0.05) as compared to healthy control group. In addition, ROC curve analyses showed AUC (Area Under the Curve) value of all proteins ranging from 0.639 to 0.725 showing acceptable discrimination potential of the these differentially expressed proteins with Fibrinogen (AUC = 0.707) and SERPINA3 (AUC = 0.725) showing good discrimination efficiency.

In conclusion, these serum proteins may serve as a diagnostic tool for the detection PCOS.