AUTHOR=Hartwig Jelka , Loebel Madlen , Steiner Sophie , Bauer Sandra , Karadeniz Zehra , Roeger Carsten , Skurk Carsten , Scheibenbogen Carmen , Sotzny Franziska 

TITLE=Metformin Attenuates ROS via FOXO3 Activation in Immune Cells

JOURNAL=Frontiers in Immunology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.581799

DOI=10.3389/fimmu.2021.581799

ISSN=1664-3224

ABSTRACT=<p>Forkhead box O 3 (FOXO3) is a transcription factor involved in cell metabolism, inflammation and longevity. Here, we investigated if metformin can activate FOXO3 in human immune cells and affects the subsequent level of reactive oxygen/nitrogen species (ROS/RNS) in immune cells. AMP-activated protein kinase (AMPK) and FOXO3 activation were investigated by immunoblot or flow cytometry (FC) analysis, respectively. FOXO3 target gene expression was quantified by real-time PCR. ROS/RNS measurement using dichlorodihydrofluorescein diacetate (DCFH-DA) dye was investigated by FC. The role of the FOXO3 single nucleotide polymorphisms (SNPs) <italic>rs12212067</italic>, <italic>rs2802292</italic> and <italic>rs12206094</italic> on ROS/RNS production was studied using allelic discrimination PCR. Metformin induced activation of AMPK (pT172) and FOXO3 (pS413). ROS/RNS level was reduced in immune cells after metformin stimulation accompanied by induction of the FOXO3 targets mitochondrial superoxide dismutase and cytochrome c. Studies in Foxo3 deficient (<italic>Foxo3<sup>-/-</sup></italic>) mouse splenocytes confirmed that metformin mediates its effects <italic>via</italic> Foxo3 as it attenuates ROS/RNS in myeloid cells of wildtype (WT) but not of <italic>Foxo3<sup>-/-</sup></italic> mice. Our results suggest that FOXO3 can be activated by metformin leading to reduced ROS/RNS level in immune cells. This may add to the beneficial clinical effects of metformin observed in large cohort studies on longevity, cardiovascular and cancer risk.</p>