Line H Tangerås1, Gabriela B Silva1, Guro S Stødle1, Lobke M Gierman2, Bente Skei2, Karin Collett3, Anne-Lise Beversmark4, Ragnhild B Skråstad5, Liv Cecilie V Thomsen6, Line Bjørge7, Ann-Charlotte Iversen8. 1. Centre of Molecular Inflammation Research (CEMIR), Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway; Department of Gynecology and Obstetrics, St. Olavs Hospital, NO-7030, Trondheim, Norway. 2. Centre of Molecular Inflammation Research (CEMIR), Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway. 3. Department of Pathology, Haukeland University Hospital, NO-5058, Bergen, Norway; Center for Cancer Biomarkers CCBIO, Department of Clinical Science, University of Bergen, NO-5021, Bergen, Norway. 4. Department of Gynecology and Obstetrics, St. Olavs Hospital, NO-7030, Trondheim, Norway. 5. Department of Clinical Pharmacology, St. Olavs Hospital, NO-7030, Trondheim, Norway; Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway. 6. Centre of Molecular Inflammation Research (CEMIR), Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway; Center for Cancer Biomarkers CCBIO, Department of Clinical Science, University of Bergen, NO-5021, Bergen, Norway; Department of Gynecology and Obstetrics, Haukeland University Hospital, NO-5058, Bergen, Norway. 7. Center for Cancer Biomarkers CCBIO, Department of Clinical Science, University of Bergen, NO-5021, Bergen, Norway; Department of Gynecology and Obstetrics, Haukeland University Hospital, NO-5058, Bergen, Norway. 8. Centre of Molecular Inflammation Research (CEMIR), Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway. Electronic address: ann-charlotte.iversen@ntnu.no.
Abstract
INTRODUCTION: Normal pregnancy is characterized by an elevated inflammatory state involving the placenta. The placental inflammation is further increased in preeclampsia, resulting in release of harmful danger signals to the maternal circulation. Activation of toll-like receptors (TLR)2 and TLR4 by endogenous danger signals plays a role in inflammatory diseases. Placental TLR2 and TLR4 expression has been reported, and high mobility group box 1 (HMGB1) is a likely endogenous activator of these receptors. We aimed to examine HMGB1 activation of TLR2 and TLR4 as mechanisms of placental inflammation in normal and preeclamptic pregnancies, by combined analysis of expression and function of the ligand HMGB1, the receptors TLR2 and TLR4, and the cytokine responder interleukin (IL)-8. METHODS: Protein expression was analyzed in placental tissue from normal and preeclamptic pregnancies, and cytokine responses to two distinct HMGB1 isoforms were examined in placental explants and trophoblasts. Inflammatory and anti-angiogenic markers were measured in maternal serum. RESULTS: We demonstrated strong co-localized expression of HMGB1, TLR4 and IL-8 in the syncytium layer of the placenta. Syncytium TLR4 expression and maternal serum levels of IL-8 were significantly increased in preeclamptic compared to normal pregnancies. Functionality was confirmed by TLR4-dependent release of IL-8 from placental explants and trophoblasts in response to the inflammatory isoform of HMGB1. DISCUSSION: This demonstrates a role for the HMGB1-TLR4 pathway at the syncytium layer and suggests involvement in placental inflammation and preeclampsia.
INTRODUCTION: Normal pregnancy is characterized by an elevated inflammatory state involving the placenta. The placental inflammation is further increased in preeclampsia, resulting in release of harmful danger signals to the maternal circulation. Activation of toll-like receptors (TLR)2 and TLR4 by endogenous danger signals plays a role in inflammatory diseases. Placental TLR2 and TLR4 expression has been reported, and high mobility group box 1 (HMGB1) is a likely endogenous activator of these receptors. We aimed to examine HMGB1 activation of TLR2 and TLR4 as mechanisms of placental inflammation in normal and preeclamptic pregnancies, by combined analysis of expression and function of the ligand HMGB1, the receptors TLR2 and TLR4, and the cytokine responder interleukin (IL)-8. METHODS: Protein expression was analyzed in placental tissue from normal and preeclamptic pregnancies, and cytokine responses to two distinct HMGB1 isoforms were examined in placental explants and trophoblasts. Inflammatory and anti-angiogenic markers were measured in maternal serum. RESULTS: We demonstrated strong co-localized expression of HMGB1, TLR4 and IL-8 in the syncytium layer of the placenta. Syncytium TLR4 expression and maternal serum levels of IL-8 were significantly increased in preeclamptic compared to normal pregnancies. Functionality was confirmed by TLR4-dependent release of IL-8 from placental explants and trophoblasts in response to the inflammatory isoform of HMGB1. DISCUSSION: This demonstrates a role for the HMGB1-TLR4 pathway at the syncytium layer and suggests involvement in placental inflammation and preeclampsia.
Authors: Danny J Schust; Elizabeth A Bonney; Jun Sugimoto; Toshi Ezashi; R Michael Roberts; Sehee Choi; Jie Zhou Journal: Int J Mol Sci Date: 2021-02-10 Impact factor: 6.208
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