Serum Concentrations Of Adipocyte Fatty Acid Binding Protein And Retinol-binding Protein 4 In Preeclampsia

Preeclampsia,a pregnancy-specific complication occurring in the second half of human pregnancy and one of the leading causes for perinatal mortality and morbidity,is characterized by the onset of hypertension and proteinuria.The etiology remains elusive although much has been achieved in understanding the pathophysiology and pathogenesis of preeclampsia in the recent years.Insulin resistance is among the fields that attracted much attention and is one of the most important pathophysiologies in preeclampsia.Pregnancy is a state of physiological insulin resistance.This state reaches maximal in the third trimester and is exacerbated in preeclampsia.Since insulin resistance progresses as placenta develops,insulin resistance has been considered the result of combination of placental factors including human placental lactogen,prolactin, insulin-like growth hormones and steroid hormones.However,adipokines have been proposed to take a role in the insulin resistance during pregnancy and in preeclampsia.Adipokines,adipocyte-derived hormones that regulate metabolism,include adiponectin,leptin,resistin and visfatin,and are found expressed in human placentas. These hormones are proposed involved in the pathogenesis of preeclampsia by regulating metabolism and by affecting insulin sensitivity.The appearance of novel adipokines enhanced our understandings in the role of adipokines in maintaining insulin resistance during pregnancy and in the development of preeclampsia.Both adipocyte fatty acid binding protein(AFABP,also known as FABP-4 or aP2) and retinol binding protein4(RBP4) have been described as novel adipokines associated with insulin resisitance,overweight and obesity.Serum RBP4 level was elevated in insulin-resistant mice and humans with obesity and type-2 diabetes mellitus(T2DM) and overexpression of RBP4 causes insulin resistance and normalization of serum RBP4 level improve insulin resistance and glucose intolerance in mice.The level of AFABP in circulation was significantly increased in obese subjects compared with lean control and was correlated positively with waist circumference,insulin resistance,blood pressure and atherogenic dyslipidemia in diabetic subjects.Higher concentration of circulating AFABP predicted the increased risk for metabolic syndrome,T2DM and cardiovascular diseases.Due to the close link with insulin resistance,the changes of RBP4 and AFABP in gestational diabetes,a pregnancy complication characterized by insulin resistance, attracted attention of pioneer researchers.However,publication regarding the alterations of RBP4 and AFABP in preeclampsia is little.To obtain insight into the significance of RBP4 and AFABP in normal pregnancy and in preeclampsia,we determined the concentrations of RBP4 and AFABP in sera of preeclamptic women,age- and gestational age-matched controls with normal pregnancy and age-matched non-pregnant controls.Objectives:To clarify the alterations in circulating adipocyte fatty acid binding protein(AFABP) and retinol binding protein4(RBP4) in normal pregnancy and preeclampsia.Methods:Twenty-seven healthy non-pregnant women,27 healthy pregnant women at third trimester and 26 women with preeclampsia were recruited and blood samples were taken.Concentrations of serum AFABP and RBP4 were measured with enzyme-linked immuno-absorbent assay(ELISA).Results:There were significant differences in serum AFABP(P<0.001) and RBP4 (P=0.022) among non-pregnancy,normal pregnancy and preeclampsia.Serum AFABP was significantly higher in preeclampsia than non-pregnancy(P<0.001) and normal pregnancy(P=0.001).Serum RBP4 was significantly higher in preeclampsia than normal pregnancy(P=0.007) but not non-pregnancy(P=0.061).There were no significant differences in serum RBP4 and AFABP between non-pregnancy and normal pregnancy(P=0.379 and 0.91,respectively).Serum RBP4 was significantly higher in severe than mild preeclampsia(P=0.046).There was no significant difference in serum AFABP between mild and severe preeclampsia(P=0.586).Conclusion:Elevated circulating AFABP and RBP4 levels were demonstrated, suggesting their involvement in the pathophysiology of preeclampsia.No alteration of serum RBP4 and AFABP were found between healthy pregnancy and non-pregnancy. RBP4 and AFABP were not a sensitive biomarker of insulin resistance in normal healthy pregnancy.