Physical activity may drive healthy microvascular ageing via downregulation of p66Shc.

Abstract

Narrower retinal arterioles and wider venules are linked to adverse cardiovascular outcomes. The mitochondrial adaptor p66Shc is a major source of ageing-induced generation of reactive oxygen species. Promoter DNA methylation inhibits p66Shc gene transcription. This cross-sectional study was designed to investigate the link between physical activity, retinal vessel diameters and p66Shc expression in active and sedentary ageing subjects. Altogether 158 subjects were included in the study (mean age 59.4 ± 7.0 years). Thirty-eight subjects were healthy active, 36 were healthy sedentary and 84 were sedentary with ≥2 cardiovascular risk factors. Retinal arteriolar and venular diameters were measured by means of a retinal vessel analyser. As a marker of oxidative stress, plasma 3-nitrotyrosine was determined by enzyme-linked immunosorbent assay. Gene expression of p66Shc and DNA methylation were assessed in mononuclear cells by real-time quantitative polymerase chain reaction and methylated-DNA capture (MethylMiner Enrichment kit) coupled with quantitative polymerase chain reaction, respectively. Wider retinal arterioles (179 ± 14 vs 172 ± 11 and 171 ± 14 µm; p < 0.05 and narrower venules (204 ± 17 vs 209 ± 11 and 218 ± 16 µm; p < 0.001) were observed in healthy active subjects compared with healthy sedentary subjects and sedentary subjects with ≥2 cardiovascular risk factors, respectively. Furthermore, healthy active subjects had blunted p66Shc expression and lower 3-nitrotyrosine plasma levels compared with healthy sedentary and sedentary subjects with ≥2 cardiovascular risk factors. Accordingly, hypomethylation of p66Shc promoter observed in healthy sedentary and sedentary subjects with ≥2 cardiovascular risk factors was not found in healthy active subjects. Long-term physical activity-induced DNA methylation of p66Shc may represent a putative mechanistic link whereby active lifestyle promotes healthy microvascular ageing.