Pre-eclampsia is a leading cause of fetal and maternal morbidity and mortality that preferentially affects primiparous patients. It is associated with systemic inflammation and impaired trophoblast invasion of the decidua. Decidual cells are the major cell type of the pregnant endometrium. Macrophages and dendritic cells are major specialized antigen-presenting cells that promote both innate immunity and immune tolerance. Macrophage infiltration is implicated in impaired trophoblast invasion that leads to pre-eclampsia. By contrast, the potential modulating role of decidual dendritic cells in the genesis of pre-eclampsia has not been investigated. Interleukin-1beta (IL-1beta), a pro-inflammatory cytokine, has been implicated in the genesis of pre-eclampsia. Thus, we postulate that pre-eclampsia would be associated with enhanced decidual dendritic cells infiltration and that IL-1beta would enhance the production of relevant dendritic cell-recruiting chemokines. We used immunohistochemistry to demonstrate a marked infiltrate of immature and mature dendritic cells in pre-eclamptic decidua. Further, immunohistochemistry and immunoassays of placental bed biopsies revealed that pre-eclamptic decidua displays elevated levels of several monocyte- and dendritic cell-recruiting chemokines. Leukocyte-free first-trimester decidual cells were then treated with IL-1beta, which enhanced the mRNA and protein expression of these chemokines. The current study also confirmed previous reports that macrophages directly impaired trophoblast invasion and that this inhibitory effect is augmented by the conditioned medium of IL-1beta-treated first-trimester decidual cells. However, unlike macrophages, dendritic cells did not directly impede trophoblast invasion. This study demonstrates that the inflammatory milieu of pre-eclampsia induces decidual cells to promote dendritic cell infiltration. Given their unusual versatility in mediating both immunity and tolerance, these novel findings suggest that dendritic cells may play a critical role either in the pathogenesis of pre-eclampsia or its prevention in subsequent pregnancies.

Objective To investigate the alterations of syncytin, a fusogenic membrane protein involved in syncytiotrophoblastic layer formation, and its receptor ASCT2 expression in placental development and pre-eclampsia.Design Analyses of syncytin and ASCT2 expression in placentas from different stages of pregnancy and women with pre-eclampsia and in cytotrophoblasts cultured in normoxic and hypoxic conditions.Setting Placental samples were collected from a tertiary medical centre.Population Sixteen women with pre-eclampsia and 58 pregnant women presented as pregnancy (5-19 weeks of gestation) for elective termination, preterm birth, or normal term delivery.Methods The quantitative real-time polymerase chain reaction was used to study the syncytin and ASCT2 expression during placental development in 35 placentas from women without pre-eclampsia (ranged from 5 to 40 weeks of gestation) and the alterations of pre-eclamptic placentas (n = 16) compared with gestationalage-matched controls (n = 16). Western blot analysis was performed to study the protein level of syncytin in pre-eclamptic placentas and gestational-age-matched controls. The hypoxic effect on trophoblastic syncytin and ASCT2 expression was further studied in cytotrophoblasts cultured in 2% oxygen (n = 7).Main outcome measures Syncytin and ASCT2 messenger RNA (mRNA) in placental tissue and cytotrophoblasts.Results The level of syncytin mRNA expression increased significantly since the first trimester of pregnancy until 37 weeks of gestation, when the level of syncytin expression was reduced. The ASCT2 mRNA expression was decreased significantly since the second trimester and was relatively stable since then to 40 weeks of gestation. Furthermore, a significant reduction in syncytin mRNA expression was observed in pre-eclamptic placentas and cytotrophoblasts cultured in hypoxia, but not a reduction in ASCT2 mRNA expression. Correlatively, the protein level of syncytin was decreased in pre-eclamptic placentas.Conclusions A reduced placental expression of syncytin but not ASCT2 may contribute to altered cytotrophoblastic cell fusion processes and disturbed placental function in pre-eclampsia. Correspondingly, hypoxia decreases syncytin but not ASCT2 gene expression in cultured cytotrophoblasts.

The proteasome is a multisubunit cytosolic protein complex responsible for degrading cytosolic proteins. Several studies have implicated its involvement in the processing of viral particles used for gene delivery, thereby limiting the efficiency of gene transfer. Peptide-based nonviral gene delivery systems are sufficiently similar to viral particles in their size and surface properties and thereby could also be recognized and metabolized by the proteasome. The present study utilized proteasome inhibitors (MG 115 and MG 132) to establish that peptide DNA condensates are metabolized by the proteasome, thereby limiting their gene transfer efficiency. Transfection of HepG2 or cystic fibrosis/T1 (CF/T1) cells with CWK 18 DNA condensates in the presence of MG 115 or MG 132 resulted in significantly enhanced gene expression. MG 115 and MG 132 increased luciferase expression 30-fold in a dose-dependent manner in HepG2 and CF/T1. The enhanced gene expression correlated directly with proteasome inhibition, and was not the result of lysosomal enzyme inhibition. The enhanced transfection was specific for peptide DNA condensates, whereas Lipofectamine-and polyethylenimine-mediated gene transfer were significantly blocked. A series of novel gene transfer peptides containing intrinsic GA proteasome inhibitors (CWK 18 (GA) n , where n ¼ 4, 6, 8 and 10) were synthesized and found to inhibit the proteasome. The gene transfer efficiency mediated by these peptides in four different cell lines established that a GA repeat of four is sufficient to block the proteasome and significantly enhance the gene transfer. Together, these results implicate the proteasome as a previously undiscovered route of metabolism of peptide-based nonviral gene delivery systems and provide a rationale for the use of proteasome inhibition to increase gene transfer efficiency. Gene Therapy (2005) 12, 1581-1590.

No abstract