Regulation of macrophage polarization by metformin through inhibition of TLR4/NF-κB pathway to improve pre-eclampsia.

INTRODUCTION

Pre-eclampsia (PE) is a pregnancy complication featuring hypertension and proteinuria. Metformin exerts clinically preventive effects on PE with an unspecified mechanism.

METHODS

Placental tissues from PE patients and normal pregnant (NP) women were collected. Twenty-four pregnant mice were divided into control, PE (40 μg/kg lipopolysaccharides (LPS)-induced modeling), aspirin, and metformin groups. After acquisition of bone marrow-derived macrophages (BMDM) and THP-1 cells, cells were categorized into control, LPS (100 ng/mL), metformin, and metformin + toll-like receptor 4 (TLR4) agonist RS 09 groups. Inflammatory factors and macrophage polarization were detected by ELISA, flow cytometry, immunofluorescence, immunohistochemistry, and qRT-PCR methods. TLR4/Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway protein expression was examined using Western blot.

RESULTS

Both PE patients and PE-like mice enhanced inducible nitric oxide synthase (iNOS), TLR4, p-NF-κB/NF-κB, and p-inhibitor of NF-κB (IκBα)/IκBα expression, and lower arginase 1 (Arg-1) expression. Moreover, metformin treatment in PE-like mice increased fetal number and weight and reduced hypertension, proteinuria, insulin resistance, tumor necrosis factor-α (TNF-α), IL-6, IL-1β, chemokine ligand 4 (CCL4), C-X-C motif chemokine ligand 2 (CXCL2) expression and M1 macrophage polarization, with similar inhibition to aspirin. In LPS-induced cells, metformin had the same effects mentioned above. Decreased TLR4, p-NF-κB/NF-κB, and p-IκBα/IκBα protein expression was caused by metformin both in vivo and in vitro. In vitro, RS 09 intervention inhibited anti-inflammatory and pro-M2 polarizing effects of metformin, activating TLR4/NF-κB pathway.

CONCLUSION

Metformin may ameliorate PE by promoting M2 macrophage polarization through up-regulating TLR4/NF-κB pathway, laying theoretical basis for metformin clinical application in PE.