Antibodies to oxidized low-density lipoprotein and to cardiolipin in nonpregnant and pregnant women with habitual abortion

OLR1 and Loxin Expression in PBMCs of Women with a History of Unexplained Recurrent Miscarriage: A Pilot Study

AIMS

The aim of this study was to evaluate the expression of OLR1 and its alternative splicing isoform Loxin in unexplained recurrent miscarriage (uRM).

METHODS

Sixty-three women of reproductive age were recruited and were divided into four groups: 18 pregnant and 23 non-pregnant women with uRM, and 12 pregnant and 10 non-pregnant women with physiological pregnancies. Complementary DNA derived from peripheral blood mononuclear cells (PBMCs) was analyzed by quantitative real-time PCR to evaluate the expression of OLR1 and Loxin. Oxidized low-density lipoproteins (ox-LDLs) were assayed from serum by a commercially available kit.

RESULTS

Pregnant uRM women presented with a higher, though not significant, OLR1/Loxin ratio and a higher ox-LDLs serum level (p ≤ 0.05) compared with pregnant control women. OLR1 and Loxin levels were significantly decreased in non-pregnant uRM women compared with the control (OLR1: 0.00018 vs. 0.00043, p ≤ 0.005; Loxin: 0.00018 vs. 0.00060, p ≤ 0.005, respectively). Loxin expression decreased by about two-thirds (p ≤ 0.005) in pregnant women compared with non-pregnant control women. A higher expression of OLR1 in pregnant women compared with non-pregnant women with uRM (p ≤ 0.05) was observed, but no variation in Loxin expression was observed.

CONCLUSIONS

The results of this study show an association of peripheral OLR1 and Loxin expression levels in uRM women, and they suggest the possible existence of an uncontrolled oxidative stress in these women in the first trimester of pregnancy.

Expression and localization of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in murine and human placentas

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is one of the scavenger receptors that recognizes oxidized low-density lipoprotein as a major ligand. The placenta is a major source of prooxidant during pregnancy, and the level of placental oxidative stress increases rapidly at the end of the first trimester and tapers off later in gestation. In our study, we evaluated placental expression of LOX-1 during different gestational stages in mice and humans. We used immunohistochemistry and ISH to identify LOX-1-expressing cells in murine and human placentas. In both species, higher expression of LOX-1 mRNA during early to midgestational stages compared with late gestation-corresponding to the increased oxidative stress in early pregnancy-was shown by real-time RT-PCR. In murine placenta, we showed that LOX-1-expressing cells were fibroblast-like stromal cells in metrial glands and decidua basalis and that they were glycogen trophoblast cells in the junctional and labyrinth zones. In the human, LOX-1 expression was detected in villous cytotrophoblasts in both first trimester and term placentas. These localization patterns of LOX-1 in murine and human placentas suggest the possible involvement of LOX-1 in high oxidative stress conditions of pregnancy.

Expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in human preeclamptic placenta: possible implications in the process of trophoblast apoptosis

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was originally identified as a receptor for oxidatively modified low-density lipoprotein. It has been reported that oxidative stress and hyperlipidemia play important roles in the etiology of preeclampsia, and that placental oxidative stress may stimulate syncytiotrophoblast apoptosis in preeclampsia. In this study, we examined the expression of LOX-1 in the human placentas of normal pregnancies and in preeclampsia using immunohistochemistry and Western blot analysis, and proposed that LOX-1 has a role in trophoblast apoptosis. To analyze apoptotic activity, the expression of the specific caspase cleavage site within cytokeratin 18 was assessed immunohistochemically using the monoclonal antibody M30 CytoDeath. Both LOX-1 and M30 immunoreactivity occurred predominantly in syncytiotrophoblasts. A significantly higher number of LOX-1 and M30-positive cells were found in preeclamptic placentas than in normal placentas. The number of M30-positive cells correlated with the apoptotic index of trophoblasts determined by TdT-mediated dUTP nick-end labeling (TUNEL). Syncytiotrophoblasts showing apoptotic activity were immunopositive to LOX-1 by double immunohistochemical fluorescence. We suggest that the functional role of syncytiotrophoblasts in placental dysfunction results from the localization and upregulation of LOX-1 in the preeclamptic placenta, possible implications in upregulation of syncytiotrophoblast apoptotic activity in preeclampsia.

Thyroid autoimmunity and abortion: a prospective study in women undergoing in vitro fertilization

OBJECTIVE

To determine whether an association exists between the presence of thyroid peroxidase (TPO) antibodies before pregnancy and miscarriage in women without a history of habitual abortion.

DESIGN

Prospective study and nested case-control study.

SETTING

Inner-city teaching hospital.

PATIENT(S)

Four hundred eighty-nine women in an IVF program.

INTERVENTION(S)

In the prospective study, we measured levels of TPO antibodies and TSH. In the nested case-control study, we also measured levels of anticardiolipin antibodies.

MAIN OUTCOME MEASURE

Miscarriage.

RESULT(S)

One hundred seventy-three women were observed, of whom 31% (54/173) became pregnant. Pregnancy occurred in 48% (12/25) of the antibody-positive women and in 28% (42/148) of the antibody-negative women. Among those who became pregnant, miscarriage occurred in 33% (4/12) of TPO antibody-positive women and in 19% (8/42) of TPO antibody-negative women. The TSH level was abnormal (<0.2 microIU/mL) in only one of the TPO antibody-positive women who miscarried. The presence of anticardiolipin antibodies was not associated with miscarriage.

CONCLUSION(S)

No association was found between the presence of TPO antibodies before pregnancy and miscarriage in women without a history of habitual abortion. The presence of TPO antibodies did not adversely affect a woman's chances of becoming pregnant.

Postmenopausal hormone replacement therapy and autoantibodies against oxidized LDL

OBJECTIVES

Oxidative modification of low-density lipoprotein (oxLDL) has been suggested to play an important role in the pathogenesis of atherosclerosis, and autoantibodies against oxLDL have recently found to reflect this process. The antioxidant effect and inhibition of LDL oxidation may be one of the cardioprotective mechanisms of postmenopausal estrogen therapy.

METHODS

The effects of postmenopausal hormone replacement therapy (HRT) on the concentrations of serum lipids and oxLDL autoantibodies were studied in a population-based prospective 1-year study with 64 early postmenopausal women (mean age 52.2 +/- 0.4 (S.E.M.) years). The participants were randomized into two treatment groups: HRT-group: Sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate alone or in combination with vitamin D3, 300 IU/day + calcium lactate, 500 mg/day (n = 31) and the non-HRT-group: Calcium lactate, 500 mg/day alone or in combination with vitamin D3, 300 IU/day (n = 33). The groups were well matched regarding age, body mass index and baseline serum lipid concentrations.

RESULTS

The serum concentrations of total cholesterol and LDL-cholesterol decreased in the HRT-group (4.1%, P = 0.05 and 6.4%, P = 0.03, respectively, paired t-test) but did not change in the non-HRT-group. No changes in the serum concentrations of HDL-cholesterol or triglycerides were observed. Additionally, no changes in oxLDL autoantibody concentrations were observed in either group.

CONCLUSIONS

Although 1-year HRT lowered serum total- and LDL-cholesterol levels, it did not influence oxLDL antibody titers. On the basis of the present results we cannot question the possibility of there being beneficial effects of HRT on the oxidative modification of LDL. However, this effect is not reflected in the levels of oxLDL autoantibodies.

Antibodies to beta 2-glycoprotein I and prothrombin in habitual abortion

OBJECTIVE

To determine the occurrence of antibodies to beta 2-glycoprotein I (beta 2-GP-I) and prothrombin in women with histories of habitual abortions when pregnant and nonpregnant.

DESIGN

Antibodies to beta 2-GP-I and prothrombin were measured by ELISA using irradiated polystyrene plates in 43 women with habitual abortions and 22 healthy controls.

SETTING

Departments I and II of Obstetrics and Gynecology, University Central Hospital of Helsinki.

PATIENT(S)

Twenty-two women of the habitual abortion patients had never delivered (primary aborters) and 21 had delivered at least one living child before miscarriage (secondary aborters).

INTERVENTION(S)

Venous blood samples were collected before and during pregnancy.

MAIN OUTCOME MEASURE(S)

Immunoglobulin G class antibodies to beta 2-GP-I and prothrombin.

RESULT(S)

The secondary aborters showed higher levels of antibodies to prothrombin than the primary aborters when both pregnant and nonpregnant and also showed higher levels of antiprothrombin antibodies than the controls when pregnant. No such differences were found in levels of antibodies to beta 2-GP-I. The habitual abortion patients showed a tendency toward higher levels of these autoantibodies when pregnant than when nonpregnant. Gestational diabetes was more common among the antibody-positive habitual abortion patients than among the antibody-negative patients.

CONCLUSION(S)

Increased levels of antiprothrombin antibodies were associated with secondary abortions. Elevated levels of antibodies to beta 2-GP-I and prothrombin often were found in habitual abortion patients with gestational diabetes.