Minh Deo

Resveratrol inhibits release of soluble fms-like tyrosine kinase (sFlt-1) and soluble endoglin and improves vascular dysfunction – implications as a preeclampsia treatment

Preeclampsia is a disease of pregnancy associated with placental oxidative stress, inflammation and elevated release of anti-angiogenic factors sFlt-1 and soluble endoglin. These placental factors cause generalized maternal endothelial dysfunction. There are no treatments to halt disease progression; delivery is the only cure. Resveratrol modulates pathways involved in inflammation and oxidative stress and may offer a potential therapeutic for preeclampsia. Resveratrol reduced sFlt-1, sFlt-1 e15a and soluble endoglin secretion from primary trophoblasts and HUVECs and reduced mRNA expression of pro-inflammatory molecules NFκB, IL-6 and IL-1β in trophoblasts. IL-6, IL-1β and TNFα secretion were also significantly reduced. In HUVECs, resveratrol significantly increased mRNA of anti-oxidant enzymes HO-1, NQO1, GCLC and TXN but did not significantly alter HO-1 protein expression, whilst reducing HO-1 protein in trophoblast. Endothelial dysfunction was induced in HUVECs using TNFα, increasing expression of cell adhesion molecule VCAM1 and adhesion of peripheral blood mononuclear cells, both of which were increased further by resveratrol. In contrast, resveratrol significantly reduced TNFα-induced Endothelin-1 (a vasoconstrictor) and significantly increased the phosphorylation of endothelial nitric oxide synthase (eNOS). In summary, resveratrol decreases secretion of anti-angiogenic factors however its effects on the endothelium are mixed. Overall, it may have potential as a treatment for preeclampsia.

Endogenous Annexin-A1 Regulates Haematopoietic Stem Cell Mobilisation and Inflammatory Response Post Myocardial Infarction in Mice In Vivo

Endogenous anti-inflammatory annexin-A1 (ANX-A1) plays an important role in preserving left ventricular (LV) viability and function after ischaemic insults in vitro, but its long-term cardioprotective actions in vivo are largely unknown. We tested the hypothesis that ANX-A1-deficiency exaggerates inflammation, haematopoietic stem progenitor cell (HSPC) activity and LV remodelling in response to myocardial ischaemia in vivo. Adult ANX-A1−/− mice subjected to coronary artery occlusion exhibited increased infarct size and LV macrophage content after 24–48 h reperfusion compared with wildtype (WT) counterparts. In addition, ANX-A1−/− mice exhibited greater expansion of HSPCs and altered pattern of HSPC mobilisation 8 days post-myocardial infarction, with increased circulating neutrophils and platelets, consistent with increased cardiac inflammation as a result of increased myeloid invading injured myocardium in response to MI. Furthermore, ANX-A1−/− mice exhibited significantly increased expression of LV pro-inflammatory and pro-fibrotic genes and collagen deposition after MI compared to WT counterparts. ANX-A1-deficiency increased cardiac necrosis, inflammation, hypertrophy and fibrosis following MI, accompanied by exaggerated HSPC activity and impaired macrophage phenotype. These findings suggest that endogenous ANX-A1 regulates mobilisation and differentiation of HSPCs. Limiting excessive monocyte/neutrophil production may limit LV damage in vivo. Our findings support further development of novel ANX-A1-based therapies to improve cardiac outcomes after MI.

Activating Transcription Factor 3 Is Reduced in Preeclamptic Placentas and Negatively Regulates sFlt-1 (Soluble fms-Like Tyrosine Kinase 1), Soluble Endoglin, and Proinflammatory Cytokines in PlacentaNovelty and Significance

Preeclampsia is a major pregnancy complication associated with poor placental perfusion and placental hypoxia. Systemic and placental inflammation and elevated placental secretion of the antiangiogenic factors sFlt-1 (soluble fms-like tyrosine kinase 1) and sEng (soluble endoglin) are hallmarks of preeclampsia, causing endothelial dysfunction and multiorgan injury. A molecule that links placental hypoxia, inflammation, and antiangiogenic factor release has not been described. ATF3 (activating transcription factor 3) is highly expressed in placenta. We assessed whether placental ATF3 is dysregulated in preterm preeclampsia, is altered by hypoxia, and regulates proinflammatory cytokine and antiangiogenic factor production. ATF3 mRNA and protein expression was significantly reduced in preterm preeclamptic placentas compared with gestation-matched controls. Hypoxia reduced ATF3 expression in primary cytotrophoblast and placental explants. Silencing ATF3 in primary cytotrophoblast increased proinflammatory cytokine (IL-6 [interleukin 6], TNF-&agr; [tumor necrosis factor &agr;]) and NF-&kgr;B (nuclear factor &kgr;B) expression. In silico analysis identified an ATF3–binding site in the promoter of Flt-1 (the transcript from which sFlt-1 is produced). Silencing ATF3 increased sFlt-1 and sEng secretion from primary cytotrophoblast possibly by increasing Rab11a and Arf1, cargo proteins that facilitate exosomal release of sFlt-1. ATF3 knockout mice did not have a preeclampsia phenotype, suggesting that these pathways may be specific to humans (preeclampsia is a uniquely human condition). To conclude, we have shown that ATF3 is decreased in preeclamptic placentas and that this decrease is likely to occur after prolonged hypoxia. We show that ATF3 is a regulator of placental proinflammatory cytokines and antiangiogenic factors sFlt-1 and sEng. Therefore, reduced ATF3 may be centrally involved in the pathology of preeclampsia.

Nuclear factor of activated T-cells (NFAT) regulates soluble fms-like tyrosine kinase-1 secretion (sFlt-1) from human placenta

INTRODUCTION Preeclampsia is a serious complication affecting 5-8% of pregnancies. Central to its pathogenesis is placental hypoxia and inflammation which leads to secretion of soluble fms-like tyrosine kinase 1 (sFlt-1). sFlt-1 causes widespread endothelial dysfunction. The molecular mechanisms regulating sFlt-1 production remain poorly understood. Recently, a binding site for the nuclear factor activated T cells (NFAT) transcription factor has been found on fms-like tyrosine kinase 1 (FLT-1) promoter. METHODS We assessed whether inhibiting NFAT impacts FLT-1, sFlt-1 and cytokine expression, as well as sFlt-1 secretion in primary cytotrophoblasts, placental explants and human umbilical vein endothelial cells (HUVECs). We investigated whether NFAT is regulated by hypoxia in primary cytotrophoblasts. We characterised the expression of NFAT1-4 in preterm preeclamptic compared to gestationally matched placentas. RESULTS Inhibiting NFAT reduced FLT-1 and sFlt-1 splice variant e15a transcription, concordant with reduced total sFlt-1 and sFlt-1 e15a secretion from primary human cytotrophoblasts. This effect appeared tissue specific as inhibiting NFAT did not change sFlt-1 secretion from endothelial cells. Inhibiting NFAT also reduced transcription of inflammatory cytokines IL-1β and IL-10 in primary cytotrophoblasts. NFAT1 and NFAT3 mRNA expression were significantly increased under hypoxia (1% O2). Inhibiting NFAT under hypoxia significantly reduced FLT-1 and sFlt-1 e15a transcription, but did not reduce sFlt-1 secretion. NFAT mRNA and protein localisation was not different in preeclamptic compared to gestationally matched placenta. DISCUSSION NFAT positively regulates placental FLT-1 and sFlt-1 e15a, secretion of sFlt-1 and inflammatory cytokine expression. It may be involved in the pathophysiology of preeclampsia.

Author Correction: Endogenous Annexin-A1 Regulates Haematopoietic Stem Cell Mobilisation and Inflammatory Response Post Myocardial Infarction in Mice In Vivo

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.