Peer Review #2 of "Protein signatures linking history of miscarriages and metabolic syndrome: a proteomic study among North Indian women (v0.3)"

Background.Metabolic syndrome (MeS), a constellation of metabolic adversities, and history of miscarriage make the women at a higher risk for cardiovascular diseases (CVDs).However, molecular evidence indicating a link between the two phenotypes (history of miscarriage and MeS) among women would offer an opportunity to predict the risk factor for CVDs at an early stage.Thus, the present retrospective study attempts to identify the proteins signatures (if any) to understand the connection between the history of miscarriage and MeS.Methods.Age-matched eighty pre-menopausal women who were not on any medical intervention or drugs were recruited from a Mendelian population of the same gene pool.Recruited women were classified into four groups -(a) Group Aabsolute cases with history of miscarriage and MeS, (b) Group B -absolute controls without any history of miscarriage and MeS, (c) Group C -cases with MeS but lack any history of miscarriage, (d) Group D -cases with history of miscarriage but lack MeS.Differentially expressed proteins in plasma samples of women from four groups were identified using 2-D gel electrophoresis and mass spectrometry.Results.Three case groups (A, C, & D) showed eighteen differentially expressed proteins.Nearly 60% of proteins (11/18) were commonly dysregulated in Group C (only with MeS) and Group D (only with miscarriage history).Nearly 40% of proteins (7/18) were commonly dysregulated in the three case groups (Groups A, C, & D), indicating a shared pathophysiology.Four proteins were exclusive but shared by case groups C & D indicating the independent routes for CVDs through MeS or miscarriages.In absolute cases, transthyretin (TTR) showed exclusive upregulation, which was further validated by Western blotting and ELISA.Networking analyses showed the strong association of TTR with haptoglobin, transferrin and ApoA1 hinting towards a cross-talk among these proteins which could be a cause or an effect of TTR upregulation.Conclusion.The study provides