The Preliminary Study Of Disintegrin And Metalloprotease ADAM 12 As A Marker For Preeclampsia

BACKGROUNDPreeclampsia is the major cause of maternal and fetal morbidity and mortality, the early diagnosis and prevention remains a enormous challenge for us because of it's elusive etiology. The secreted form of ADAM 12 is a member of ADAM family, recent studies hypothesized that it could be a potentially important marker for prenatal screening.OBJECTIVESTo develop a indirect competitive ELISA to quantify human ADAM 12 in serum preliminarily, and use it to assess ADAM 12 levels in second-trimester maternal serum as a potential marker for preeclampsia.METHODSUsing peptide synthesis and choose the most specific 34 amino acids C-terminal of ADAM 12-S as coating antigen and standardization, ADAM 12-S level in samples can be quantified through molecular weight ratio. Immune a rabbit with the vector-coupled peptide to prepare anti-ADAM 12-S polyclonal antibody, and used it as the first antibody after purification. Determine the optimal concentration of coating antigen and dilution of the first antibody, a standard curve under these conditions generated to establish indirect competitive ELISA preliminarily. Using this method, a case-control study performed. Serum samples collected in 14 to 18 weeks of gestational age from 100 women who later developed preeclampsia and 200 normal pregnant women, all of them had prenatal examinations and delivered in PUMCH from 2002 to 2006. Serum ADAM 12 levels were assayed and converted to MoM versus gestational age, compare them for any significant difference. RESULTSThe optimal concentration of coating antigen is 0.25μg/ml, the dilution of anti-ADAM 12-S polyclonal antibody is 1∶6,000. Under these conditions, the lowest detection limit is 0.137μg/L (peptide), the quantitative detection interval between 0.137μg/L to 100μg/L (peptide), the standard curve regression coefficient is 0.984. Using this method, the median of serum ADAM 12 level in 14 to 18 weeks of gestational age in normal pregnant women is 680μg/L, 738μg/L, 801μg/L, 849μg/L and 900μg/L respectively, that in women who later developed preeclampsia is 598μg/L, 664μg/L, 729μg/L, 791μg/L and 839μg/L respectively. Serum ADAM 12 levels in case and control gradually increased with similar upward trend in this period. Serum ADAM 12 levels in women who later developed preeclampsia had a mean log MoM of -0.05242, which was significantly lower than the mean log MoM of -0.00368 for ADAM 12 levels observed in serum samples from women with normal pregnancy (P<0.001).CONCLUSIONSWe developed a indirect competitive ELISA to quantify human ADAM 12 in serum preliminarily, obtained the median of serum ADAM 12 level in 14 to 18 weeks of gestational age in normal pregnant women and women who later developed preeclampsia. Serum ADAM 12 level in case and control gradually increased with similar upward trend in this period. The maternal serum levels of ADAM 12 are significantly lower in 14 to 18 weeks of gestational age in women who later developed preeclampsia when compared with levels in women with normal pregnancies. Second trimester serum ADAM 12 may be served as a marker for preeclampsia screening, but its value remains to be confirmed by additional large sample prospective study.