Senescent cells accumulate with age and push the body toward pathologies. Senolytics, which eliminate them, usually require long-term administration, and their effects are rarely tested separately in males and females. Our work sits alongside research on aging as a loss of regulation, but differs in that it tests not a hypothesis but a specific immunotherapy in middle-aged animals with separation by sex. This is the first test of whether a short course of an anti-GD3 antibody can provide long-term protection against age-related diseases in both sexes.
Eighteen-month-old mice (25 males and 25 females per group) received an antibody against GD3 or a combination of dasatinib with quercetin (D+Q) every 15 days, for a total of six doses. Some animals were sacrificed at 21 and 24 months for tissue analysis, and the rest were followed to the end of life. Frailty was assessed monthly using a composite index, along with body weight, and blood and urine were collected. Causes of death were divided into cancer and non-cancer. In the lungs, liver, and kidneys, fibrosis, GD3 expression, and expression of the senescence marker Glb1 were measured. Lung RNA was sequenced at 21 and 24 months.
In all mice, anti-GD3 produced a trend toward increased survival (p=0.052) and significantly reduced the frailty index compared with control and D+Q (p<0.001): median survival increased by 19.8% versus control and by 34.5% versus D+Q, and frailty at the median lifespan fell by 33%. Separation by sex revealed strong dimorphism: in males, 75th-percentile survival increased by 105%, frailty remained reduced for more than a year after treatment cessation, and death from non-cancer causes was delayed by about 200 days (+56%). In females, median survival barely changed (+13.8%), but death from tumors was delayed by almost 200 days (+66%), although the frequency and spectrum of tumors did not change. In tissues, anti-GD3 reduced lung fibrosis in both sexes, liver fibrosis more strongly in males, and kidney fibrosis only in females. The lung transcriptome three months after treatment cessation showed activation of innate immunity (NK cells, neutrophils) and metabolic pathways in males, and of adaptive immunity (B cells, antigen presentation) in females. D+Q acted differently: immediately and through extracellular matrix pathways, without sexual dimorphism.
The work shows that GD3 acts as an immune checkpoint of aging, and that it can be temporarily blocked in middle age to provide protection for a year or more. Unlike neighboring studies, where aging is viewed as a loss of regulation in general, here a specific molecular mechanism is proposed and tested in animals with separation by sex. The main difference from previous senolytics is the short course and sex-specific mechanisms: innate immunity and metabolism in males, adaptive immunity in females. This is the first case where the same therapy yields different protective pathways in different sexes.
The field may move toward the search for other immune checkpoints on senescent cells and for combinations that enhance the effect in both sexes. A separate question is why, in females, protection from cancer is not accompanied by a reduction in the number of tumors: perhaps immunity better restrains their growth but not their occurrence. Long-term observations after treatment cessation will help clarify how durable the effect is and whether the course needs to be repeated.
The results will influence geroscience and the development of senolytic immunotherapies, as well as preclinical protocols, where the sex of the animals will now have to be taken into account.
Test anti-GD3 in other models of aging and in other species, and determine which immune cells destroy senescent cells in males and females.
For gerontology, the key unresolved problem is why senescent cells escape immunity and how to restore surveillance without harming healthy tissues. This work is the first to link the sexual dimorphism of aging to different branches of the immune response, which may explain why the same senolytics work differently in males and females.
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.