FOXO4-DRI Peptide Clears Senescent Endothelial Cells and Eases Vascular Aging in Mice

Endothelial senescence is increasingly seen as a root cause of vascular aging. Senescent endothelial cells secrete inflammatory factors and matrix-degrading enzymes, and they impair vasodilation. This contributes to arterial stiffness, hypertension and damage to the heart, brain and kidneys. Senescent cells resist apoptosis, partly because FOXO4 binds p53 in the nucleus and restrains its pro-apoptotic activity. FOXO4-DRI is a D-retro-inverso peptide designed to compete with FOXO4 for p53 binding. It has shown senolytic activity in other tissues, but its effects on the vasculature were largely untested.

The researchers used three models. First, naturally aged mice (17 months, both sexes) received intraperitoneal FOXO4-DRI (5 mg/kg every 2 days) or PBS for one month. Second, young mice were given D-galactose (200 mg/kg/day) for 8 weeks to induce an aging-like state, with FOXO4-DRI given during the final 4 weeks. Third, HUVECs were treated with 50 μM FOXO4-DRI during 3 hours of oxygen-glucose deprivation (OGD) to model stress-induced endothelial senescence. Readouts included Western blot, RT-qPCR, SA-β-gal, DHE (ROS), H&E, high-frequency ultrasound with pulse wave velocity (PWV), CCK-8, tube formation, Annexin V/PI flow cytometry, TUNEL, nuclear/cytoplasmic fractionation, immunofluorescence, co-immunoprecipitation, and serum liver and kidney tests. Both cell and animal work were described as blinded.

In naturally aged mice, the text provided shows that FOXO4-DRI significantly lowered aortic p21, p16 and γ-H2AX, and raised Ki-67 and Lamin B. Senescence-associated inflammatory transcripts (Il-1β, Il-6, Cxcl15, Tnf-α) fell, SA-β-gal-positive cells decreased, and DHE staining showed less vascular ROS. Aortas were thinner and PWV was lower, which indicates better elasticity. Per the abstract, similar anti-aging effects occurred in the D-galactose model and in OGD-stressed HUVECs, where the peptide improved endothelial function.

Mechanistically, co-immunoprecipitation indicated that FOXO4-DRI prevents FOXO4 from binding p53. This is reported to promote nuclear exclusion of phosphorylated p53 (Ser46) and activate BAX and cleaved caspase-3, with the p53/BCL-2/caspase-3 axis implicated. The result is apoptosis of senescent endothelial cells, which the authors link to reduced vascular inflammation and improved function.

These results suggest that selectively removing senescent endothelial cells with a p53-targeting senolytic peptide could be a strategy against vascular aging. Several caveats apply. The work is preclinical, group sizes are small (about 3–6 per assay), and no human or long-term safety data are shown. The supplied full text was truncated after the first results section, so the D-galactose, OGD and mechanistic data are assessed here mainly from the abstract. Short OGD exposure is also an imperfect stand-in for chronic senescence. The peptide is not endothelium-specific, so effects on other cell types cannot be excluded.