Epigenetically-driven persistence of inflammatory and oxidative phenotypes in adolescents born to women with gestational diabetes

Abstract

Abstract Background According to the theory of developmental origins of health and disease1, environmental changes during the in-utero period can permanently affect health and vulnerability to diseases later in life. As a matter of fact, the offspring of women with gestational diabetes (GD) exhibit a higher risk for developing obesity, type 2 diabetes (T2D), and atherosclerotic cardiovascular disease (ASCVD) than those individuals with a family history of diabetes2–4. Importantly, epigenetics has emerged as a crucial determinant for this transmission across generations5–8. Mixed Lineage Leukemia 1 (MLL1) histone methyltransferase activates inflammatory and oxidative pathways through trimethylation of histone 3 at lysine 4 amino (H3K4me3)9. Purpose To investigate whether such epigenetic mark regulates genes triggering inflammation and oxidative stress in GD women, and its potential transmission and persistence in their offspring. Methods We isolated peripheral blood mononuclear cells (PBMCs), fetal cord blood mononuclear cells (CBMCs), and umbilical cord vein endothelial cells (HUVECs) from GD and control pregnant women, as well as PBMCs and plasma samples from a retrospective cohort of adolescents (12-16 years old) born to control or GD women. Gene and protein expressions were investigated by RT-PCR, immunoblotting and/or confocal microscopy. H3K4me3 levels on NF-kB p65 and NADPH oxidase isoform 4 (NOX4) promoter regions were assessed by chromatin immunoprecipitation (ChIP) and RT-PCR. Mechanistic studies were performed in control- and GD-HUVECs using the MLL1 inhibitor MM-102 to assess downstream inflammatory mediators and superoxide anion (O2-) generation by electron spin resonance (ESR) spectroscopy. Results Our data showed upregulation of MLL1 and H3K4me3 levels in PBMCs, HUVECs, and CBMCs isolated from GD as compared to control women. ChIP analysis revealed H3K4me3 enrichment in the promoter region of the inflammatory and oxidative master regulatory genes NF-kB p65 and NOX4, respectively, in these cells. We also found an upregulation of NF-kB p65 target genes IL-6, MCP-1, ICAM-1, and VCAM-1, and increased monocyte adhesion and O2- production. The inhibition of MLL1 was able to reduce H3K4me3 levels blunting the inflammatory and oxidative phenotypes in GD-HUVECs. Interestingly enough, we demonstrated a persistent increase of H3K4me3 in the NF-kB p65 promoter region of PBMCs together with an elevation of inflammatory markers in plasma from adolescents born to GD women. Conclusions Our results suggest that GD may induce inflammation and oxidative stress through MLL1-dependent H3K4me3 mechanisms. Such epigenetic mark is transmitted to the offspring and, most importantly, can still be found in adolescence as a pro-inflammatory trigger. These findings pave the way for pharmacological reprogramming of adverse histone modifications to counteract early abnormal phenotypes in GD offspring which may accelerate ASCVD burden.