Trophoblast invasion of the uterine extracellular matrix, a critical process of human implantation and essential for fetal development, is a striking example of controlled invasiveness. To identify molecules that regulate trophoblast invasion, mRNA signatures of trophoblast cells isolated from first trimester (high invasiveness) and term placentae (no/low invasiveness) were compared using U95A GeneChip microarrays yielding 220 invasion/migrationrelated genes. In this 'invasion cluster', KiSS-1 and its G-protein-coupled receptor KiSS-1R were expressed at higher levels in first trimester trophoblasts than at term of gestation. Receptor and ligand mRNA and protein were localized to the trophoblast compartment. In contrast to KiSS-1, which is only expressed in the villous trophoblast, KiSS-1R was also found in the extravillous trophoblast, suggesting endocrine/paracrine activation mechanisms. The primary translation product of KiSS-1 is a 145 amino acid polypeptide (Kp-145), but shorter kisspeptins (Kp) with 10, 13, 14 or 54 amino acid residues may be produced. We identified Kp-10, a dekapeptide derived from the primary translation product, in conditioned medium of first trimester human trophoblast. Kp-10, but not other kisspeptins, increased intracellular Ca 2+ levels in isolated first trimester trophoblasts. Kp-10 inhibited trophoblast migration in an explant as well as transwell assay without affecting proliferation. Suppressed motility was paralleled with suppressed gelatinolytic activity of isolated trophoblasts. These results identifed Kp-10 as a novel paracrine/endocrine regulator in fine-tuning trophoblast invasion generated by the trophoblast itself.

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The molecular mechanisms governing invasive differentiation of human trophoblasts remain largely elusive. Here, we investigated the role of Wnt-␤-catenin-T-cell factor (TCF) signaling in this process. Reverse transcriptase-polymerase chain reaction and Western blot analyses demonstrated expression of Wnt ligands, frizzled receptors, LRP-6, and TCF-3/4 transcription factors in total placenta and different trophoblast cell models. Immunohistochemistry of placental tissues and differentiating villous explant cultures showed that expression of TCF-3/4 strongly increased in invading trophoblasts. Some of these cells also accumulated dephosphorylated ␤-catenin in the nucleus. Wnt3A treatment of primary cytotrophoblasts and SGHPL-5 cells induced activity of TCF-luciferase reporters. Accordingly, the ligand provoked interaction of TCF-3/4 with ␤-catenin as assessed in electrophoretic mobility shift assays (EMSAs) and upregulation of Wnt/TCF target genes as observed by Western blot analyses. Wnt3A stimulated trophoblast migration and invasion through Matrigel, which could be blocked by addition of Dickkopf-1, mediating inhibition of canonical Wnt signaling. Dickkopf-1 also reduced basal migration, invasion, and proliferation of cytotrophoblasts, suggesting expression of endogenous Wnt ligand(s). Immunohistochemistry revealed that the percentage of extravillous trophoblasts containing nuclear ␤-catenin was significantly higher in placentas of complete hydatidiform mole pregnancies as compared to normal placentas. Thus, canonical Wnt signaling may promote invasive trophoblast differentiation, and exaggerated activation of the pathway could contribute to trophoblastic hyperplasia and local invasion.

Infection-triggered disease onset, chronic immune activation and autonomic dysregulation in CFS point to an autoimmune disease directed against neurotransmitter receptors. Autoantibodies against G-protein coupled receptors were shown to play a pathogenic role in several autoimmune diseases. Here, serum samples from a patient cohort from Berlin (n=268) and from Bergen with pre- and post-treatment samples from 25 patients treated within the KTS-2 rituximab trial were analysed for IgG against human α and β adrenergic, muscarinic (M) 1-5 acetylcholine, dopamine, serotonin, angiotensin, and endothelin receptors by ELISA and compared to a healthy control cohort (n=108). Antibodies against β2, M3 and M4 receptors were significantly elevated in CFS patients compared to controls. In contrast, levels of antibodies against α adrenergic, dopamine, serotonin, angiotensin, and endothelin receptors were not different between patients and controls. A high correlation was found between levels of autoantibodies and elevated IgG1-3 subclasses, but not with IgG4. Further patients with high β2 antibodies had significantly more frequently activated HLA-DR+ T cells and more frequently thyreoperoxidase and anti-nuclear antibodies. In patients receiving rituximab maintenance treatment achieving prolonged B-cell depletion, elevated β2 and M4 receptor autoantibodies significantly declined in clinical responder, but not in non-responder. We provide evidence that 29.5% of patients with CFS had elevated antibodies against one or more M acetylcholine and β adrenergic receptors which are potential biomarkers for response to B-cell depleting therapy. The association of autoantibodies with immune markers suggests that they activate B and T cells expressing β adrenergic and M acetylcholine receptors. Dysregulation of acetylcholine and adrenergic signalling could also explain various clinical symptoms of CFS.

We have tested the hypothesis that elevated concentrations of TNF alpha could impair trophoblast invasion. Using first-trimester placental explant cultures, we have demonstrated that the cytokine inhibits in vitro migration of extravillous trophoblasts (EVT) on collagen I, and invasion through Matrigel. To elucidate the underlying mechanism, proliferation and differentiation of EVT in vitro were analyzed by immunohistochemistry of serial sections, Western blotting, zymography, ELISA, and RT-PCR from RNA pools of mechanically separated cell populations. At 24 h of cultivation in the presence or absence of TNF alpha, anchorage and proliferation of trophoblasts had occurred to generate cell columns containing viable, post-mitotic, differentiated EVT [positive for integrins alpha 1 and alpha 5, matrix metalloproteinase (MMP)-2, and human leukocyte antigen-G1; negative for proliferating cellular nuclear antigen, cytokeratin 18 neoepitope, and in 5-Bromo-2-deoxy-uridine labeling]. At 72 h, control cells had broken away from the column to migrate through the extracellular matrix; whereas, in contrast, TNF alpha-treated EVT remained as contiguous cell columns, despite increased MMP-9 expression. Thus, in vitro MMP9 activity appears not to be essential for trophoblast migration. Expression of plasminogen activator inhibitor (PAI)-1 was elevated in TNF alpha-treated EVT, and adding antibodies that inhibit PAI-1 activity restored migration, whereas tissue-inhibitor-of-metalloproteinases-1-blocking antibodies were ineffective. Induction of PAI-1 by TNF alpha could be related to restricted trophoblast invasion in preeclampsia.