CD74-Downregulation of Placental Macrophage-Trophoblastic Interactions in Preeclampsia

RATIONALE

We hypothesized that cluster of differentiation 74 (CD74) downregulation on placental macrophages, leading to altered macrophage-trophoblast interaction, is involved in preeclampsia.

OBJECTIVE

Preeclamptic pregnancies feature hypertension, proteinuria, and placental anomalies. Feto-placental macrophages regulate villous trophoblast differentiation during placental development. Disturbance of this well-balanced regulation can lead to pathological pregnancies.

METHODS AND RESULTS

We performed whole-genome expression analysis of placental tissue. CD74 was one of the most downregulated genes in placentas from preeclamptic women. By reverse transcriptase-polymerase chain reaction, we confirmed this finding in early-onset (<34 gestational week, n=26) and late-onset (≥34 gestational week, n=24) samples from preeclamptic women, compared with healthy pregnant controls (n=28). CD74 protein levels were analyzed by Western blot and flow cytometry. We identified placental macrophages to express CD74 by immunofluorescence, flow cytometry, and RT-PCR. CD74-positive macrophages were significantly reduced in preeclamptic placentas compared with controls. CD74-silenced macrophages showed that the adhesion molecules ALCAM, ICAM4, and Syndecan-2, as well as macrophage adhesion to trophoblasts were diminished. Naive and activated macrophages lacking CD74 showed a shift toward a proinflammatory signature with an increased secretion of tumor necrosis factor-α, chemokine (C-C motif) ligand 5, and monocyte chemotactic protein-1, when cocultured with trophoblasts compared with control macrophages. Trophoblasts stimulated by these factors express more CYP2J2, sFlt1, TNFα, and IL-8. CD74-knockout mice showed disturbed placental morphology, reduced junctional zone, smaller placentas, and impaired spiral artery remodeling with fetal growth restriction.

CONCLUSIONS

CD74 downregulation in placental macrophages is present in preeclampsia. CD74 downregulation leads to altered macrophage activation toward a proinflammatory signature and a disturbed crosstalk with trophoblasts.

Relaxin Treatment in an Ang-II-Based Transgenic Preeclamptic-Rat Model

Relaxin is a peptide related to pregnancy that induces nitric oxide-related and gelatinase-related effects, allowing vasodilation and pregnancy-related adjustments permitting parturition to occur. Relaxin controls the hemodynamic and renovascular adaptive changes that occur during pregnancy. Interest has evolved regarding relaxin and a therapeutic principle in preeclampsia and heart failure. Preeclampsia is a pregnancy disorder, featuring hypertension, proteinuria and placental anomalies. We investigated relaxin in an established transgenic rat model of preeclampsia, where the phenotype is induced by angiotensin (Ang)-II production in mid pregnancy. We gave recombinant relaxin to preeclamtic rats at day 9 of gestation. Hypertension and proteinuria was not ameliorated after relaxin administration. Intrauterine growth retardation of the fetus was unaltered by relaxin. Heart-rate responses and relaxin levels documented drug effects. In this Ang-II-based model of preeclampsia, we could not show a salubrious effect on preeclampsia.

Abstract 125: Overexpression of the Transcription Factor Dlx5 in the Placenta of Preeclamptic Patients Leads to Decreased Trophoblast Proliferation - A Novel Mechanism Involving Loss of Imprinting

Objectives: Preeclampsia (PE) is one of the most-common, life-threatening pregnancy complication that affects maternal and offspring health, with short and long-term implications.

We hypothesize that epigenetic abnormalities and/or dysregulation of imprinted genes together with genes located in their proximity during placentation affect expression pattern of a broad spectrum of genes leading to preeclampsia. These genes can induce life-long epigenetic changes in the genome of the mother following preeclamptic pregnancy.

Methods and Results: Using large-scale bioinformatical analysis of human placenta gene expression in 25 preeclamptic patients and 23 controls we identified characteristic pattern for PE. It consists of three clusters of patients, suggesting that preeclampsia is a complex, heterologous disease. Moreover, the analysis identified distal-less homeobox 5 (DLX5), a maternally expressed gene, which is significantly upregulated in preeclamptic placenta (1.5 fold). We confirmed upregulation of DLX5 on mRNA level in the early onset (0.8 (n=6), indicating that LOI is involved in overexpression of DLX5 in PE. DLX5 is primarily known as a developmental transcription factor and is crucial for bone development. Although DLX5 is highly expressed in human placenta, its function and the target genes in trophoblasts as well as its role during placentation still remains unknown. Using Sleeping Beauty (SB) transposon system, we stably overexpressed DLX5 in SGHPL-4 trophoblast cell line that significantly reduced trophoblast proliferation as indicated by high throughput sampler cell count (654.2 ± 395.5 vs. 1709 ± 1119) and MTT colorimetric assay (A570: 0.154 ± 0.097 vs. 0.29 ± 0.099).

Conclusions: We show that the imprinted transcription factor DLX5 is upregulated in preeclampsia and propose loss of imprinting as one underlying mechanism. Overexpression of DLX5 in first trimester trophoblasts reduces cell proliferation. Our data support the importance of dysregulated epigenetic mechanism as an important feature in preeclampsia.

Abstract 042: Cd74-dysregulation of Macrophage-trophoblastic Interactions in the Preeclamptic Placenta

Objectives: Preeclamptic pregnancies feature placental anomalies. Villous trophoblast differentiation during placental development is regulated by feto-placental macrophages and disturbance of this well-balanced regulation can lead to pathological pregnancies. We hypothesized that Cluster of differentiation 74 (CD74) dysregulation of placental macrophages, leading to altered macrophage-trophoblast interaction, is involved in preeclampsia.

Methods and Results: We performed microarray analysis of placental tissue. CD74 was one of the most down-regulated (-2.5 fold) genes in placentas from preeclamptic women. We confirmed this finding in early onset (<34 gestational week, n=26) and late onset (≥34 gestational week, n=24) samples from preeclamptic women, compared to healthy pregnant controls (n=28) by real-time RT-PCR and on protein level by Western blot and flow cytometry. We localized CD74 expression in placental macrophages by immunofluorescence, flow cytometry, and real-time RT-PCR. Number and mean fluorescence intensity (MFI) of CD74-positive macrophages were significantly lower in preeclamptic placentas (7692 MFI ± 4402), as compared to controls (16283 MFI ± 3047). In CD74-silenced macrophages, expression of adhesion molecules ALCAM (-2 fold), ICAM4 (-2.1 fold), and Syndecan-2 (-1.9 fold) was lower compared to control. Macrophage adhesion to a trophoblast layer were diminished (-1.3 fold). Naïve and activated macrophages lacking CD74 showed a shift towards a pro-inflammatory signature with an increased secretion of TNFalpha(21.8 pg/ml ± 13.2 vs. 8 pg/ml ± 4.3), CCL5 (1.9 ng/ml ± 0.4 vs. 0.8 ng/ml ± 0.2) and MCP-1 (3 ng/ml ± 2.6 vs. 1 ng/ml ± 0.5), when co-cultured with trophoblasts compared to control macrophages. CD74-knockout mice showed disturbed placental morphology, reduced junctional zone (1.6 mm2 ± 0.3 vs. 2.3 mm2 ± 0.5) and smaller placentas (0.09 g ± 0.01 vs. 0.11 g ± 0.02) with fetal growth restriction (0.7 g ± 0.1 vs. 0.9 g ± 0.2) when compared to WT mice.

Conclusions: We found that CD74 downregulation in placental macrophages is present in preeclampsia. CD74 downregulation led to altered macrophage activation towards a pro-inflammatory signature, a disturbed crosstalk with trophoblasts and an abnormal placental morphology.

Regulatory T cells ameliorate intrauterine growth retardation in a transgenic rat model for preeclampsia

Preeclampsia is a multisystemic syndrome during pregnancy that is often associated with intrauterine growth retardation. Immunologic dysregulation, involving T cells, is implicated in the pathogenesis. The aim of this study was to evaluate the effect of upregulating regulatory T cells in an established transgenic rat model for preeclampsia. Application of superagonistic monoclonal antibody for CD28 has been shown to effectively upregulate regulatory T cells. In the first protocol (treatment protocol), we applied 1 mg of CD28 superagonist or control antibody on days 11 and 15 of pregnancy. In the second protocol (prevention protocol), the superagonist or control antibody was applied on days 1, 5, and 9. Superagonist increased regulatory T cells in circulation and placenta from 8.49±2.09% of CD4-positive T cells to 23.50±3.05% and from 3.85±1.45% to 23.27±7.64%, respectively. Blood pressure and albuminuria (30.6±15.1 versus 14.6±5.5 mg/d) were similar in the superagonist or control antibody-treated preeclamptic group for both protocols. Rats treated with CD28 superagonist showed increased pup weights in the prevention protocol (2.66±0.03 versus 2.37±0.05 g) and in the treatment protocol (3.04±0.04 versus 2.54±0.1 g). Intrauterine growth retardation, calculated by brain:liver weight ratio, was also decreased by the superagonist in both protocols. Further analysis of brain development revealed a 20% increase in brain volume by the superagonist. Induction of regulatory T cells in the circulation and the uteroplacental unit in an established preeclamptic rat model had no influence on maternal hypertension and proteinuria. However, it substantially improved fetal outcome by ameliorating intrauterine growth retardation.

Abstract 666: RNAi Therapeutics Targeting Human Angiotensinogen (hAGT) Ameliorate Preeclamptic Sequelae in an Established Transgenic Rodent Model for Preeclampsia

Preeclampsia, a disorder with the hallmark features of new-onset hypertension and proteinuria beginning after 20 weeks of gestation, affects 5% of pregnancies in industrialized nations. It is a major cause of fetal and maternal morbidity/mortality. Several studies have demonstrated that angiotensinogen is involved in the pathogenesis of the disease; however, treatment with ACE Inhibitor or AT1 Receptor blocker is contraindicated due to fetal toxicity.

RNAi therapeutics are highly potent mediators of gene-specific silencing. We tested a human angiotensinogen (hAGT)-specifc siRNA, conjugated to triantennary GalNAc, for the ability to ameliorate symptoms of preeclampsia in an established rat model, without affecting the fetus. Transgenic rats expressing hAGT and human renin (hREN) were crossed to produce a model of preeclampsia (PE rat) in the dams. Beginning on day 3 of gestation, transgenic hAGT dams were dosed subcutaneously with 10 mg/kg siRNA every third day through gestation day 15. Mean blood pressure was continuously recorded by radiotelemetry and 24 hour urine samples were collected in metabolic cages at day 18 of gestation. Rats were euthanized at day 21 of gestation.

Treatment with the GalNAc-conjugated siRNA reduced the spike in blood pressure seen on gestation day 13 and lasted through study termination (MAP on day 16 of gestation: 155.1 ± 1.4 mmHg untreated vs. 138.4 ± 1.8 mmHg treated). Proteinuria was ameliorated (21.7 ± 3.1 mg/d untreated vs. 2.7 ± 0.6 mg/d treated) and levels of agonistic autoantibodies against the angiotensin receptor AT1 were reduced below the limit of detection. Fetal and uteroplacental unit weights increased with RNAi therapy, demonstrating a reduction in intra-uterine growth restriction (brain to liver ratio (0.95 ± 0.04 untreated vs. 0.73 ± 0.02 treated). mRNA levels of hAGT were reduced to background levels in the liver, but were not affected in the placenta, which is of fetal origin.

Our data show that an RNAi therapeutic targeting hAGT ameliorates the clinical sequelae of preeclampsia in a transgenic rat model and improves the outcome of the fetus.

Relaxin does not improve Angiotensin II-induced target-organ damage

Relaxin is a corpus-luteum produced protein hormone with vasodilatatory, anti-fibrotic, and angiogenic properties that are opposite to angiotensin (Ang) II. We investigated whether or not relaxin ameliorates Ang II-induced target-organ damage. We used double transgenic rats harboring both human renin and angiotensinogen genes (dTGR) that develop severe hypertension, target-organ damage, and die untreated within 7–8 weeks. Recombinant relaxin at a low (26 μg/kg/d) and a high dose (240 μg/kg/d) was given to 4 week-old dTGR and age-matched Sprague-Dawley rats (SD). Systolic blood pressure increased progressively in untreated dTGRs from 162±3 mmHg at week 5 to 225±5 mmHg at week 7. Relaxin had no effect on blood pressure whereas SD rats were normotensive (106±1 mmHg). Untreated and relaxin-treated dTGR had similarly severe cardiac hypertrophy indices. Relaxin did not ameliorate albuminuria and did not prevent matrix-protein deposition in the heart and kidney in dTGR. Finally, relaxin treatment did not reduce mortality. These data suggest that pharmacological doses of relaxin do not reverse severe effects of Ang II.