Quantitative peptidomic analysis by a newly developed one-step direct transfer technology without depletion of major blood proteins: Its potential utility for monitoring of pathophysiological status in pregnancy-induced hypertension

We have recently developed a new target plate (BLOTCHIP®) for MALDI‐MS. An advantage of this procedure is that it does not require the lowering of protein concentrations in test samples prior to analysis. Accordingly, this new technology enables the detection of peptides present in blood samples, including those that would otherwise be adsorbed to abundant blood proteins and would thus escape detection. Using this technology, we analyzed the peripheral blood of patients with pregnancy‐induced hypertension (PIH; the most common serious complication of pregnancy) to test a potential utility of the technology for monitoring of the pathophysiological status. In the present study, we found 23 characteristic peptides for PIH in the blood serum of pregnant women. Offline LC‐MALDI MS/MS identified 7 of the 23 peptides as fragments derived from kininogen‐1 (three peptides), fibrinogen‐α, complement component C4‐A/B, α‐2‐HS‐glycoprotein and inter‐α‐trypsin inhibitor heavy chain H4. 2‐D scatter plots with combinations of the peptides found in the present study can be grouped for pregnant women with/without PIH, which would be satisfactory reflected for their status. Additionally, the levels of most of these peptides found were significantly decreased by albumin/IgG depletion prior to BLOTCHIP® analysis in accordance with conventional proteomics procedures. These results indicated that BLOTCHIP® analysis can be applied for discovery study of PIH biomarker candidates.