Few investigators have simultaneously evaluated leptin, soluble leptin receptor (SLR) and leptin gene polymorphisms in preeclampsia cases and controls.We examined these three biomolecular markers in 40 preeclampsia cases and 39 controls.Plasma leptin and SLR concentrations were determined using immunoassays. Genotype for the tetranucleotide
repeat (TTTC)n, polymorphism in the 3′-flanking region of the leptin gene was determined using PCR.Alleles of the polymorphism were characterized by size distributions [short repeats (class I); and long repeats (class II)].Logistic regression was used to calculate odds ratio
s (OR) and 95 % confidence intervals (CI).Leptin concentrations were
higher in our cases than in the controls (53.1±4.7 vs. 17.7±2.4 ng/ml,p<0.05).
SLR concentrations were slightly lower in our patients than in the controls (25.7±1.9 vs. 29.1±1.1 ng/ml, p>0.05). Elevated leptin (≥ 14.5 ng/ml) was associated with a 3.8-fold (CI 1.0-14.4) increased risk; whereas low SLR (< 28.5 ng/ml) was associated with a 6.3-fold (CI 1.7-23.2) increased risk of preeclampsia. The I/II genotype was associated with a 3.8-fold increased risk of preeclampsia (OR=3.8; 95 % CI 0.8-18.0); and the II/II genotype was not observed among our cases (0 % vs. 33 % p<0.001). Larger studies would be needed to confirm and further clarify the relations between functional variants in the leptin gene and preeclampsia risk.
Oxidative stress plays an important role in the pathophysiology of preeclampsia. In a case-control study of 99 women with preeclampsia and 99 controls, we assessed maternal plasma oxidized low-density lipoprotein (oxidized LDL) in relation to preeclampsia risk. Logistic regression procedures were used to derive odds ratios (OR) and 95 % confidence intervals (CI). Plasma oxidized LDL was determined using enzyme immunoassay. Maternal plasma oxidized LDL was significantly positively correlated with lipids in both cases and controls. After adjusting for nulliparity, pre-pregnancy body mass index, physical inactivity, family history of chronic hypertension and plasma vitamin C concentrations, women who had elevated oxidized LDL concentrations (50 U/l) experienced a 2.9-fold increased risk of preeclampsia when compared with women having lower oxidized LDL concentrations (95 % CI 1.4-5.9). The risk of preeclampsia was markedly increased in women who had both elevated oxidized LDL and elevated triglyceride concentrations (OR=8.9, 95 % CI 3.1-26.2). Women with both elevated oxidized LDL and low vitamin C concentrations experienced a 9.8-fold increased risk of preeclampsia (95 % CI 3.0-32.2). Our results confirm the role of oxidative stress in the pathogenesis of preeclampsia. Prospective studies are needed to determine if elevated oxidized LDL concentrations can predict the occurrence of preeclampsia.