TLR3-Induced Placental miR-210 Down-Regulates the STAT6/Interleukin-4 Pathway

Shelley E Kopriva,Piyali Chatterjee,Brett M Mitchell,Valorie L Chiasson,Paul G Thomas

doi:10.1371/journal.pone.0067760

Shelley E Kopriva, Piyali Chatterjee + Show 3 more

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https://doi.org/10.1371/journal.pone.0067760

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Abstract

Several clinical studies have reported increased placental miR-210 expression in women with PE compared to normotensive women, but whether miR-210 plays a role in the etiology of PE is unknown. We reported that activation of TLR3 produces the PE-like symptoms of hypertension, endothelial dysfunction, and proteinuria in mice only when pregnant, but whether TLR3 activation in pregnant mice and human cytotrophoblasts (CTBs) increases miR-210 and modulates its targets related to inflammation are unknown. Placental miR-210 levels were increased significantly in pregnant mice treated with the TLR3 agonist poly I:C (P-PIC). Both HIF-1α and NF-κBp50, known to bind the miR-210 promoter and induce its expression, were also increased significantly in placentas of P-PIC mice. Target identification algorithms and gene ontology predicted STAT6 as an inflammation-related target of miR-210 and STAT6 was decreased significantly in placentas of P-PIC mice. IL-4, which is regulated by STAT6 and increases during normotensive pregnancy, failed to increase in serum of P-PIC mice. P-PIC TLR3 KO mice did not develop hypertension and placental HIF-1α, NF-κBp50, miR-210, STAT6, and IL-4 levels were unchanged. To determine the placental etiology, treatment of human CTBs with poly I:C significantly increased HIF-1α, NF-κBp50, and miR-210 levels and decreased STAT6 and IL-4 levels. Overexpression of miR-210 in CTBs decreased STAT6 and IL-4 while inhibition of miR-210 increased STAT6 and IL-4. These findings demonstrate that TLR3 activation induces placental miR-210 via HIF-1α and NF-κBp50 leading to decreased STAT6 and IL-4 levels and this may contribute to the development of PE.

Highlights

Preeclampsia (PE) is a vascular disorder that affects 5–8% of all pregnancies and is diagnosed by the onset of hypertension and proteinuria at or after the 20th week of gestation [1]
We demonstrate that TLR3 activation induces miR-210 expression via the transcription factors hypoxia inducible factor-1a (HIF-1a) and NF-kBp50 and that STAT6 is a target of miR-210
The induction of miR-210 by TLR3 decreases STAT6 and IL-4 which may contribute to the inflammatory state evident in PE

Summary

Introduction

Preeclampsia (PE) is a vascular disorder that affects 5–8% of all pregnancies and is diagnosed by the onset of hypertension and proteinuria at or after the 20th week of gestation [1]. One possible cause of the inflammatory state may be excessive activation of Toll-like receptors (TLRs) which are present throughout utero-placental tissues to guard against foreign pathogens [4–7]. TLRs recognize exogenous pathogens and endogenous ligands from necrotic tissues and initiate innate immune responses by inducing pro-inflammatory cytokines and type I interferons (IFNa/b) [8,9]. We have reported previously that TLR3 activation is increased in placentas of women with PE and that activating the maternal immune system with the TLR3 agonist poly I:C in pregnant mice leads to PE-like symptoms [13,14]. TLR3-induced PE mice exhibit increased serum levels of pro-inflammatory cytokines including IFNc, TNFa, and IL-12, while levels of the antiinflammatory cytokine IL-4 fail to increase [13]. Clinical studies reported increased levels of pro-inflammatory cytokines in women with PE and decreased levels of IL-4 [15,16]. We sought to determine the molecular mechanism by which IL-4 levels fail to increase during PE

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