An immune sentinel that briefly loses its vigilance, then goes back to hunting down senescent cells. That is one way to describe what happens in the bodies of mice after a short course of an antibody against GD3. At 18 months, when the animals had already accumulated age-related changes, they received this antibody for three months. It binds to the GD3 molecule on the surface of senescent cells, which helps them hide from the immune system. After the course, the sentinel sees the trespassers again and clears them out.
The effect turned out to be strikingly long-lasting. In males, 75th-percentile survival rose by 105%, and frailty stayed reduced for more than a year after treatment ended. Death from non-cancer causes was pushed back by roughly 200 days, that is, by 56% compared with controls. In females, median survival barely changed, but death from tumors was delayed by almost 200 days, even though tumor frequency and spectrum were unchanged. This means the immune system became better at holding back tumor growth, though not at preventing tumors from arising.
In tissues, anti-GD3 reduced lung fibrosis in both sexes, liver fibrosis more strongly in males, and kidney fibrosis only in females. This suggests that each sex has its own target organs. The classical senolytic dasatinib with quercetin acted differently: immediately and through extracellular matrix pathways, with no sexual dimorphism.
Before this work, it was unknown whether a short course of immunotherapy against GD3 in middle age could provide long-term protection against age-related diseases, and how the effect differs between males and females. Now it is clear that the three-month course improves health and survival, protecting males from non-cancer deaths through innate immunity and females from cancer deaths through adaptive immunity. Comparison with a control group and with the classical senolytic D+Q, along with observation until natural death and matching of survival data with histology and the transcriptome, made this possible to establish. Even today, this is a rationale for preclinical trials of anti-GD3 as a preventive measure against age-related pathologies, especially with sex taken into account.
The sentinel is back on duty. A brief intervention in the immune system in middle age changes the trajectory of aging, but differently in males and females. Perhaps in the future other immune checkpoints will emerge that can be temporarily blocked to restore the body's ability to clear out senescent cells.
In female mice, after anti-GD3 was stopped, GD3 levels in the lungs returned to baseline, while in males they remained reduced, as if immune memory persists longer in males.
In Douglas Adams's novel The Hitchhiker's Guide to the Galaxy, people seek a way to extend life but encounter unexpected side effects. Here the idea is similar: a short intervention in the immune system in middle age changes the trajectory of aging, but differently in men and women.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.