Fetal Programming by Methyl Donor Deficiency Produces Pathological Remodeling of the Ascending Aorta

Objective: Deficiency in vitamin B12/folate (methyl donor deficiency [MDD]) produces cardiovascular outcomes during aging and fetal programming effects in newborns of MDD mothers. Whether fetal programming provokes long-term effects on aorta remains largely unknown. Approach and Results: We investigated the impact of fetal programming on ascending aorta of aged rats born from mothers subjected to MDD during gestation/lactation. We performed morphological and molecular examinations of ascending aortas in 21 days- and 400 days-aged rats with initial MDD fetal programming (iMDD) compared with control matched rats. iMDD induces remodeling of the ascending aorta in aged rats, with collagen deposition (P=0.0008), decreased thickness of elastin (P<0.0001), and 8.7-fold increase of elastin breaks (P=0.0002). Proteomic analyses, Western blotting, and immunohistochemical examination revealed decreased expression of alpha-smooth muscle actin, vinculin, SM22 alpha (smooth muscle 22 alpha), and N-cadherin and increased expression of TGF (transforming growth factor) beta 1. Elastin breaks were correlated to increased neutrophil elastase (P=0.0002), cathepsin-K (P=0.0002), cathepsin-S (P<0.0001), MMP (matrix metalloproteinase) 9, and MMP2 (PP=0.02). Proximity Duolink ligation assay showed homocysteinylation of actin-associated and extracellular matrix proteins, including SM22 alpha (P=0.01), N-cadherin (P=0.0008), and vinculin (P=0.001), which was associated with elastin breaks (P=0.002) and increased expression of MARS (methionyl-tRNA synthetase; involved in irreversible protein homocysteinylation). Furthermore, we observed an inverse relationship between elastin breaks and blood pressure (systolic, P=0.004 and diastolic, P=0.0007). Conclusions: MDD fetal programming produced altered integrity and remodeling of ascending aorta during aging and irreversible MARS-associated homocysteinylation of key proteins of extracellular matrix and elastin homeostasis. This contributes to understanding why homocysteine-lowering vitamin B supplementation fails to relieve vascular complications in adulthood.