Preclinical (animal)
Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression.
Born E, Lipskaia L, Breau M, Houssaini A, Beaulieu D, Marcos E, Pierre R, Do Cruzeiro M, Lefevre M, Derumeaux G, et al.; Abid S., Circulation, 2023;147(8):650-666
published
A study of what removing senescent cells does in animal models of pulmonary hypertension, using four separate interventions: a suicide-gene construct driven by the p16 promoter, the senolytic compound ABT263, inactivation of p16, and the cell-permeable FOXO4–p53 interfering peptide FOXO4-DRI. Models included mice in normoxia, chronic hypoxia or hypoxia plus Sugen, mice overexpressing the serotonin transporter (SM22-5-HTT+), and rats given monocrotaline. Only the arm using FOXO4-DRI is recorded on this page.
- In mice overexpressing the serotonin transporter, given either ABT263 or FOXO4-DRI, the authors report pulmonary haemodynamic alterations and loss of pulmonary endothelial cells compared with the relevant controls. Their conclusion is that elimination of senescent pulmonary endothelial cells by senolytic interventions may worsen pulmonary haemodynamics, and that this should be considered wherever cell senescence is being controlled.
Context
Removing senescent cells is not uniformly favourable in animals. In the pulmonary hypertension work, the same class of intervention that reduces senescence markers elsewhere was accompanied by loss of pulmonary endothelial cells and worsening haemodynamics. Two findings, two tissues, two directions — which is what an unsettled preclinical literature looks like, and the reason nothing on this page should be read as a settled property of the molecule.
Laboratory (in vitro)Preclinical (animal)
Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging.
Baar MP, Brandt RMC, Putavet DA, Klein JDD, Derks KWJ, Bourgeois BRM, Stryeck S, Rijksen Y, van Willigenburg H, Feijtel DA, et al.; de Keizer PLJ., Cell, 2017;169(1):132-147.e16
published
The peptide was designed from a FOXO4 sequence built as a D-retro-inverso isoform — D-amino acids in the reversed order — and fused to HIV-TAT, a basic, hydrophilic sequence that carries cargo into cells. Using an antibody against HIV-TAT the authors detected uptake 2 to 4 hours after exposure and for at least 72 hours afterwards.
Three mouse models were used, each carrying the p16∷3MR reporter, which drives Renilla luciferase from the promoter of the senescence gene p16-INK4a so that senescence can be followed over time: a doxorubicin chemotoxicity model, the fast-aging XpdTTD/TTD strain, and naturally aged mice. In the chemotoxicity experiment the peptide was given over the course of the experiment.
- In NMR competition experiments, adding increasing amounts of a recombinant N-terminal domain of p53 to a solution of the labelled FOXO4 forkhead domain produced progressive chemical-shift perturbations indicating specific binding. Stepwise addition of FOXO4-DRI reverted those perturbations toward the unbound state, which the authors read as the peptide competing with FOXO4 for p53 in a concentration-dependent way and with higher affinity.
- In IMR90 fibroblasts, the peptide reduced the viability of senescent cells relative to control cells, with real-time cell-density measurements placing the effect 24 to 36 hours after exposure. The same peptide in its L-isoform did not, and neither did an unrelated D-retro-inverso peptide based on a different forkhead protein, FOXM1. Stable knock-down of p53 reduced the effect, as did co-incubation with the pan-caspase inhibitors QVD-OPH or ZVAD-FMK.
- In doxorubicin-exposed mice the authors report that the peptide neutralised the doxorubicin-induced reduction in total body weight and the rise in plasma aspartate aminotransferase, a marker of liver damage. In the fast-aging strain and in naturally aged mice they report reduced p16-driven luciferase signal, higher fur-density scores, and lower plasma urea, which they interpret as restored renal filtering capacity. The paper states these results as directions with the supporting values in its figure panels; no numeric value is recorded here for them.
- Comparing platelet counts before and 30 days after exposure, the authors report no noticeable change in platelets or in other whole-blood values, and no deleterious effect on non-proliferative tissue as far as tested, naming the heart. They set this against the severe thrombocytopenia reported for the pan-BCL inhibitors ABT-263 and ABT-737, and describe it as passing initial safety concerns.
Limitations
No human study of this peptide is recorded here, because this project found none. What exists is cell culture, NMR and animals. The design paper's mouse findings are stated by its authors as directions with the numbers in figure panels, so this page reports them as directions too, rather than manufacturing values the paper did not print.
