Disorders of the lipoprotein metabolism are a major cause of endothelial dysfunction that may result in hypertension and proteinuria, clinical hallmarks of preeclampsia (PE). Lipoproteins and low-density lipoprotein (LDL) subfractions were investigated in 15 women with severe PE and compared with 23 women with a normal course of pregnancy. Compared with normal pregnancy, in PE apolipoprotein (apo)B in very low-density lipoprotein was increased by 76% (P = 0.008), and the triglyceride content of intermediate dense lipoproteins (IDL) was increased by 51% (P < 0.001); cholesterol and apoB in LDL were decreased by 26% (P = 0.005) and 23% (P = 0.016), respectively. Although not significant, the LDL profile was dominated by the most buoyant LDL-1. ApoB in the most dense LDL (dLDL), namely LDL-5 and LDL-6, was significantly decreased by 49% (P < 0.001) and 55% (P < 0.001), respectively. Diastolic blood pressure was positively correlated with the triglyceride content of IDL (r = 6.31; P < 0.001 and r = 0.352; P = 0.033 by partial correlation controlling for the presence or absence of PE) and negatively correlated with the concentration of apoB in dLDL (r = -0.500; P = 0.002). In addition, IDL triglycerides correlated negatively with infant birth weight percentile (r = -0.373; P = 0.027) and positively with proteinuria (r = 0.430; P = 0.014). Low birth weight was associated with high IDL triglycerides and low rather than high concentrations of dLDL. Triglyceride-rich remnants are known to cause endothelial dysfunction. Because the triglyceride content of IDL was positively correlated with elevated blood pressure and proteinuria, triglyceride-rich remnant lipoproteins might contribute to the pathophysiology of PE.

Pregnancy is accompanied by changes in the maternal lipoprotein metabolism that may serve to satisfy the nutritional demands of the fetus. In this study lipoprotein metabolism was investigated in 23 women during normal pregnancy in the first, second, and third trimesters and in 15 healthy nonpregnant women with regular menstrual cycles. Lipid and apolipoprotein concentrations were measured in total plasma, very low density, intermediate density, low density (LDL), and high density lipoproteins, and in each of six LDL subfractions. During early pregnancy, triglycerides, and dense LDL were higher than in the nonpregnant state. With advancing gestation, triglycerides increased and the distribution of apolipoprotein B-100-containing lipoproteins became increasingly dominated by the accumulation of very low density and intermediate density lipoproteins and buoyant, triglyceride-rich LDL. This is the first study that investigates LDL subfractions in pregnancy using a method that strictly separates LDL subfractions by virtue of density. The accumulation of buoyant, triglyceride-rich lipoproteins may be related to the down-regulation of maternal lipase activities by placental hormones. As a consequence, the metabolic changes of late pregnancy may result in an increased flux of lipoprotein-derived lipids to the placenta, which, with advancing gestation, increasingly expresses receptors with a high affinity for triglyceride-rich lipoproteins.

The two forms of the progesterone receptor, PR-A and PR-B, are independently regulated at the transcriptional level, and show distinct responses to progesterone antagonists. We were interested in possible differences in the PR-A to PR-B ratio between uterine myometrium and leiomyomata (fibroid), that might influence the response of fibroids to progesterone agonists and antagonists, and thus have consequences for the treatment of this condition. Fibroid and adjacent normal myometrium were obtained from 11 women undergoing hysterectomy. Immunohistochemistry using a monoclonal antibody which recognizes both PR-A and PR-B showed exclusively nuclear staining, and this was stronger in the leiomyomata than in adjacent myometrium. An antibody specific for PR-B gave fainter staining of both tissues. Western blotting confirmed a higher concentration of PR in leiomyomata than myometrium in eight out of 11 cases. In all cases both forms were present, with a consistent dominance of PR-A over PR-B. However an RNase protection assay showed that there was no difference between the concentrations of mRNA encoding PR-A and PR-B, or between the mRNA concentrations in leiomyomata and normal myometrium. We conclude that the observed differences between the levels of immunoreactive PR in leiomyomata and myometrium may result from post-translational control, and support the use of progesterone antagonists in the treatment of leiomyomata.

Placental macrophages (Hofbauer cells) are located close to trophoblast cells and fetal capillaries, which makes them ideal candidates for involvement in regulatory processes within the villous core. Their production of various cytokines and prostaglandin (PG) synthesizing enzymes has previously been shown immunohistochemically. Hofbauer cells were isolated from human placenta after term deliveries by Ficoll and Percoll gradient centrifugation. Remaining trophoblast cells were removed with anti-epidermal growth factor (EGF)-receptor-coated Dynabeads followed by differential adherence. The identity of isolated cells was investigated by immunohistochemistry with anti-CD68, which showed that >90% cells were positive. After a 36 h recovery period in either 20% O2 or 5% O2, fresh medium was applied and PGE2 and thromboxane (TXA2) production analysed by enzyme immunoassay at 4, 8, and 24 h. PGE2 and TXA2 were both produced by placental macrophages with PGE2 synthesis being predominant. Concentrations of both could be stimulated by lipopolysaccharide with maximum effect after 24 h. Culture in low oxygen caused decreased PGE2 concentrations, whereas TXA2 production remained unchanged. In conclusion, the presented isolation protocol allows further study of Hofbauer cell function. This study also presents novel findings regarding the prostaglandin production of term Hofbauer cells under normal and hypoxic conditions.

In pre-eclampsia, the ratio of prostacyclin:thromboxane production rate is decreased favouring the vasoconstrictive thromboxane. One of the rate-limiting steps in prostaglandin synthesis is cyclooxygenase (COX) activity. Therefore, we investigated the expression of COX-1 and COX-2 in human placenta and placental bed. Tissue specimens from the 29th to 40th week of pregnancy were obtained from Caesarean sections after uncomplicated and pre-eclamptic pregnancies before the onset of labour. COX-1 and COX-2 were localized immunohistochemically with the identification of positive cells by double immunofluorescence staining. The protein and mRNA levels were analysed by immunoblotting and quantitative reverse transcriptase-polymerase chain reaction. Expression of both COX-1 and COX-2 could be observed in placenta and placental bed. COX-1-like immunoreactivity was observed in most cell types with strongest staining in macrophages. Only macrophages, endothelium, vascular leiomyocytes and fibroblasts stained positively for COX-2. In placenta, COX-1 and -2 expression was unchanged after pre-eclampsia. In placental bed, protein and mRNA levels of COX-1 were increased in the pre-eclamptic group (P < 0.05), whereas COX-2 expression did not differ significantly from normal pregnancies. An increased expression of COX-1 could be involved in the pathophysiology of pre-eclamptic changes within the placental bed. A therapy with drugs inhibiting COX-1 might be beneficial in this condition.