Epigenetic regulation of oxidative and inflammatory phenotypes in women with gestational diabetes and offspring

Background Hyperglycemia-induced oxidative stress and inflammation are potent drivers of atherosclerotic cardiovascular disease (ASCVD). Gestational diabetes (GDM) is characterized by chronic hyperglycemia during pregnancy and may represent a clinical model to study the mechanisms of oxidative stress and inflammation induced by hyperglycemia. GDM is associated with a range of adverse perinatal and long-term outcomes for both mother and offspring. In this perspective, it is emerging a putative association between maternal GDM and offspring's epigenetic trait. Purpose To investigate the link between histone modifications, oxidative stress and inflammatory phenotype as well as the transmission of epigenetic signatures to the offspring. Methods We analyzed peripheral blood mononuclear cells (PBMC) from GDM and control mothers as well as human umbilical vein endothelial cells (HUVEC) and cord blood mononuclear cells (CBMC) isolated from newborn umbilical cords obtained at delivery from both groups. Histone methyltransferase MLL1-dependent trimethylation of histone 3 at lysine 4 amino residue (H3K4me3) on NF-kB p65 subunit promoter region was assessed by chromatin immunoprecipitation (ChIP) and real-time qPCR in HUVEC, PBMC and CBMC, respectively. MLL1 and downstream inflammatory and redox genes were determined by real-time qPCR and immunocytochemistry in the presence and in the absence of MLL1 inhibitor MM-102. Measurement of reactive oxygen species (ROS) was performed by electron spin resonance spectroscopy. Results For the first time, we demonstrated a significant increase of MLL1 expression with subsequent MLL1-induced upregulation of NF-kB p65 gene via H3K4me3 in GDM as compared to control cells. MLL1-driven epigenetic remodeling of NF-kB p65 promoter is upstream to the activation of inflammatory pathway. Indeed, treatment with MM-102 decreased H3K4me3 and blunted expression of NF-kB p65 as well as VCAM-1, MCP-1 and IL-6 genes. We also found that expression of ROS scavenger aldehyde dehydrogenase 2 is reduced, whereas pro-oxidant nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit NOX4 is upregulated. Interestingly, the increased ROS generation observed in GDM is involved in the upregulation of MLL1 as shown by the restoring effect of antioxidant vitamin C on MLL1 expression levels. Conclusions Our results suggest that a complex interplay between oxidative stress and histone modifications are responsible for the GDM maternal inflammatory and oxidative phenotypes and its transmission to the offspring. The deciphering of epigenetic-induced chromatin remodelling opens the perspective for pharmacological reprogramming of adverse chromatin changes to reduce the burden of early development of metabolic phenotypes and ASCVD. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): University G. d'Annunzio MIUR fundings Schematic figure