Targeted Nrf2 activation improves vascular endothelial function with aging and prevents vascular dysfunction following disuse in younger and older adults.
Aging and physical inactivity/disuse contribute to cardiovascular disease, which is attributable, in part, to vascular endothelial dysfunction associated with impaired nuclear-factor erythroid 2-related factor 2 (Nrf2) signaling. However, the ability to augment Nrf2 activation and its effects on age- and disuse-related vascular dysfunction in humans remains limited. In a double-blind, randomized, placebo-controlled study design 20 younger adults (8M/12F, age 27 ± 7 y) and 24 older adults (12M/12F, age 67 ± 8 y) were randomized to receive either placebo or PB125 (200 mg/day, Nrf2 activator) across three visits: baseline, 2 weeks of supplementation, and following either 5 days of bed rest (old) or 2 weeks of limb immobilization (young). Brachial and popliteal artery flow-mediated dilation (FMD), passive leg movement-induced (PLM) leg blood flow (LBF) and vascular conductance (LVC) and serum antioxidant status (superoxide dismutase, SOD) were assessed at each timepoint. Compared to placebo, 2 weeks of PB125 increased brachial (PB125: 2.8 ± 1.5 to 3.8 ± 1.3%, p < 0.0001) and popliteal FMD (PB125: 1.5 ± 1.5 to 2.3 ± 1.4%, p = 0.033) in older, but not younger adults (both, p > 0.27). During bed rest, PB125 preserved brachial (3.8 ± 1.3 to 3.6 ± 1.4%, p = 0.543) and popliteal FMD (2.3 ± 1.4 to 2.7 ± 1.4%, p = 0.269), LVC (1.1 ± 0.8 to 1.1 ± 1.5 AUC, p = 0.530) and circulating SOD concentrations (28.3 ± 7.2 to 28.6 ± 8.6 U/mL, p = 0.888) in older adults compared to placebo (all, p < 0.05). Following limb immobilization, PB125 preserved popliteal FMD (4.4 ± 2.8 to 3.4 ± 1.8%, p = 0.302) in younger adults compared to placebo (p < 0.05). These findings demonstrate targeted Nrf2 activation with PB125 improves age-related vascular endothelial dysfunction while preserving vascular function and antioxidant capacity following periods of disuse.