Inside every person's cells, an invisible clock is ticking. It doesn't show time on a dial; it measures biological age, meaning how worn the body is and how close it has come to the diseases of old age. This clock is made of chemical marks on DNA that switch genes on and off. In people with HIV, that clock often runs faster than in their healthy peers, and Japanese scientists have set out to find whether it can be slowed down.
At Komagome Hospital in Tokyo, researchers are recruiting 100 men with HIV who have been taking medication for at least a year. Each will give blood, from which DNA will be extracted and read at roughly 930,000 sites where these marks are especially common. Then, using several formulas known as epigenetic clocks, the scientists will calculate biological age. Some of those formulas were derived from people in Europe and America, and others from Japanese subjects, so that local genetic and lifestyle features are taken into account.
The central question is whether the speed of this inner clock depends on how long a person has been in treatment. The scientists suspect that in those who have been on therapy longer, biological age will be closer to chronological age. They will also compare different treatment regimens: some drugs may push the clock forward less than others. In addition, participants will be asked about smoking, alcohol, physical activity, sleep and diet, and their blood will be tested for markers of inflammation.
These data are especially valuable because almost all earlier research was done in the West. The Japanese population differs genetically and in lifestyle, so clocks trained on Japanese people will give a more accurate picture. If it is confirmed that long-term therapy or certain drugs slow biological aging, doctors will be able to choose treatment regimens with that effect in mind.
For now the study is only getting under way: recruitment will continue until spring 2027. But even now it is clear that it will be the first to link the inner clock of aging to everyday habits in people with HIV in Japan. And it may show that this clock can not only be read but also turned back a little.
The Horvath epigenetic clock, created in 2013, can predict chronological age with an error of only about 3.6 years from a sample of almost any tissue, including blood, brain, and skin.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.