Proteomic profiling of urine identifies specific fragments of SERPINA1 and albumin as biomarkers of preeclampsia

Flow chart and distribution of urine samples for the challenge phase

Pregnancy-associated conditions unrelated to preeclampsia were the following: preterm labor: n = 47; preterm premature rupture of the membranes: n = 11; placenta previa: n = 4; sepsis: n = 1, and isolated IUGR: n = 1. Of the women enrolled in the cross-sectional cohort, 86 had a medically indicated delivery for preeclampsia. The remaining 110 pregnant women delivered at different gestational ages. Deliveries at < 37 weeks in this group occurred either spontaneously (n = 50) or were medically indicated for clinical conditions such as placenta previa (n = 4), nonreassuring fetal status (n = 10), or idiopathic intrauterine fetal demise (n = 2). Of the 19 women enrolled in the longitudinal cohort of the challenge phase, 3 developed sPE or spPE requiring mandated delivery at < 37 weeks. PE, preeclampsia.

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

The urinary proteomic fingerprint of severe preeclampsia requiring delivery

Representative SELDI profile from a patient with sPE at 30 weeks gestational age, illustrating the 13 biomarker components (P1-P13, marked with red bullets) of the urinary proteomic scores (UPSb = 13 and UPSr = 47) presented in comparison with a SELDI profile of urine from a healthy pregnant control patient (both UPSb and UPSr of 0) at the same gestational age (CRL). The asterisk marks a complex of peaks not part of the UPS profile that accompanies the P1-P3 complex.

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

Diagnostic performances of the proteomic profile relative to other analytes assessed in the same random urine sample

The ROC curves of the proteomic score UPSr (red line), protein-to-creatinine ratio (blue line), and sFlt-1-to-PlGF ratio (green line) for predicting a preeclampsia-related indicated delivery. Analysis included all consecutive pregnant women who contributed with urine samples to the cross-sectional challenge phase (n = 196).

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

Evolution of urinary proteomics scores during pregnancy in the longitudinal cohort of the challenge phase

Nineteen asymptomatic pregnant women at low or high risk for developing preeclampsia were followed up longitudinally from the first trimester until 6 weeks postpartum. UPSb (A) and UPSr (B) scores were generated prospectively. Black boxes represent the women who developed preeclampsia requiring an mandated preterm delivery (n = 3). Open boxes represent women who had a normal course of their pregnancy (n = 16). On the x axes, are the time periods in weeks before each patient's delivery date (time 0). pp, postpartum. On the y axes, are the values of the urinary proteomic scores (UPSb and UPSr, respectively). The arrow indicates the time point at which women manifested clinical signs and symptoms. The data are presented as percentiles with median. The ends of the boxes define the 25th and 75th percentiles, the line inside the box defines the median, and the whiskers show the largest and smallest values. Two-way ANOVA indicates P < .01 for both time periods and outcome. Bars with at least 1 common red letter are not statistically different at a value of P > .05.

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

Quantitative and qualitative changes in SERPINA1 immunoreactivity in urine and serum of women with severe preeclampsia

Fractional excretion (FE) of SERPINA1 (proportion of SERPINA1 immunoreactivity excreted in the urine compared with that filtered by the glomeruli) relative to that of A, total proteins and B, albumin in logarithmic format. Despite the significant urinary loss, circulating SERPINA1 levels are increased in women with sPE (n = 29) C, compared with controls (n = 16) at similar gestational ages (sPE: 32.7 ± 4.4 weeks vs CRL: 30.4 ± 1.5 weeks, P = .151). Western blot of SERPINA1 immunoreactivity in urine from representative CRL and women with sPE under D, denaturing or E, native conditions. The red arrow points to monomeric SERPINA1 (S1: 52 kDa). The bands above 52 kDa represent supramolecular aggregates, whereas those below represent fragments. These results suggest that women with sPE excrete a complex pattern of SERPINA1 fragments and aggregates in addition to P1-P3 biomarkers identified by us using SELDI. E, Lane 2 was loaded with SERPINA1 polymerized in vitro (pS1) to demonstrate antibody reactivity against oligomeric SERPINA1. Molecular weight markers (M) in kilodaltons (kDa) are loaded in lane 1.

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

Correspondence of biomarker peaks between detection in SELDI-TOF and Q-TOF mass spectrometers

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.

Strategy for identification of other biomarkers of the UPS profile

Buhimschi. Profiling of urine identifies fragments of SERPINA1 and albumin as biomarkers of preeclampsia. Am J Obstet Gynecol 2008.