快猫短视频

Could something in your blood be controlling how you age? The proteins in blood seem to undergo three waves of changes as we age, and can be used to determine a person鈥檚 biological age from a blood sample.

Blood proteins associated with youth could help us understand why young blood seems to rejuvenate older animals, and could hint at treatments for ageing, say at Stanford University in California and his colleagues.

The first hints that something in blood might have rejuvenating properties came from experiments that involved stitching old and young mice together so that they shared a circulatory system. The gruesome set-up seemed to benefit the older animals, while the health of the younger animals deteriorated.

Since then, other studies have found that blood plasma transfusions from young animals seem to improve multiple aspects of health of old animals. Blood from human teenagers boosts the birth of new brain cells and improves cognition in old mice. Teams are trialling 鈥測oung blood鈥� for age-related disorders like Alzheimer鈥檚, and, for $8000, transfusions of plasma from young donors can be bought at a clinic in California.

To find out what happens to our blood as we age, Lehallier and his colleagues looked at proteins in blood plasma samples taken from more than 4300 people aged between 18 and 95. The team measured the levels of almost 3000 proteins in each sample.

Waves of change

Lehallier鈥檚 team found that the levels of almost 1400 of these proteins seem to change significantly as we age. In particular, there are three waves of changes 鈥� at about ages 34, 60 and 78. The changes at 60 are likely to represent the fact that it is around then that most age-related diseases make themselves known, and these can influence blood proteins, says at the University of Exeter, UK.

鈥淭he most surprising thing is that there鈥檚 this change at 34,鈥� says at the University of Glasgow, UK. 鈥淔or somebody who鈥檚 well over 34, it鈥檚 kind of depressing.鈥�

It means that significant biological ageing is already under way when we鈥檙e in our 30s, says at the University of Liverpool, UK. Other research has found that molecular changes in the brain associated with ageing start to show in our 30s, too, he says. 鈥淵ou don鈥檛 just turn into an old man overnight, it鈥檚 a gradual process,鈥� he says. 鈥淚t makes sense that some of the changes associated with ageing occur at an early age.鈥�

But Harries thinks that the protein changes might reflect changes in the body鈥檚 external and internal environments rather than some dramatic ageing process. Plenty of people have children in their 30s, for instance. 鈥淵our physiology undergoes some major remodelling during pregnancy and lactation, and that might well be part of it,鈥� she says.

The proteins found in young people won鈥檛 necessarily be the key to rejuvenation. In fact, we might find some of these in blood taken from the oldest participants. People in their 80s and 90s are likely to have some kind of protective factor that has kept them alive, says Harries. And we still need to figure out which proteins might be causing ageing, or simply be a result of it.

It is also possible that the important proteins might be different in men and women. When Lehallier and his colleagues compared the protein profiles of male and female volunteers, they found differences between two-thirds of the proteins that changed with age.

鈥淲omen live longer than men鈥� and we really don鈥檛 know [why],鈥� says Harries. It might be because women are more resilient to stress 鈥� they need to be in order to have children, she says. But it is unclear what these proteins are doing differently in men and women.

Ticking clock

Lehallier and his colleagues have used their findings to develop a 鈥減roteomic clock鈥� that can guess a person鈥檚 biological age based on 373 of the proteins found in their blood. The clock鈥檚 estimate, which applies to both men and women, strongly correlated with the volunteers鈥� chronological age.

It was also able to guess biological age. People who were given predicted ages below their chronological age performed better on physical and cognitive tests, suggesting they are biologically younger than their years.

鈥淚t鈥檚 a potentially revolutionary study,鈥� says Selman. The aim of much of ageing research is to find a way to increase the proportion of a person鈥檚 life that is spent in good health, rather than merely increase lifespan, he says. 鈥淥ne of the big challenges in ageing is to find biomarkers that can track your healthspan,鈥� he says. 鈥淭hey鈥檝e shown that this proteomic clock appears to be a really good predictor of late life health, and that鈥檚 really exciting.鈥�

The clock could be used in clinical trials to test if anti-ageing treatments are working, and to identify people at risk of premature ageing, says Selman. 鈥淚f somebody鈥檚 on a particular trajectory, you could see if you could switch them onto the slower ageing trajectory,鈥� he says. 鈥淏asically you鈥檙e trying to slow the ticking of this clock.鈥�

Secret to youth?

Lehallier鈥檚 team hopes to be able to identify the specific proteins in blood that might be responsible for its rejuvenating effects. 鈥淚dentifying proteins within plasma that promote or antagonise ageing at different stages of life could lead to more targeted therapeutics, as well as preventative therapies,鈥� the team write.

鈥淚t would suggest that some of these proteins are having some sort of rejuvenation effect,鈥� says Selman. But she says it may be that you need a cocktail of proteins to elicit this effect.

鈥淩eally identifying what particular proteins are important is going to take a long time, but it鈥檚 exciting research,鈥� says Selman. 鈥淭he big drive in ageing research is to find realistic interventions to extend lifespan鈥� and this may be a valid route.鈥�