DNA accessibility in immune cells tracks ageing
Not all cells read their DNA the same way.
Scientists are building increasingly sophisticated ageing clocks. A new clock, discussed in the Fight Aging! newsletter, measures not gene activity but the accessibility of the DNA itself: which regions are open and readable, and which are tightly packed and closed. Researchers call this chromatin accessibility. The clock was evaluated across multiple immune cell types simultaneously.
Why immune cells are at the centre
Most molecular ageing clocks rely on immune cells from a blood sample. That is practical: blood is easy to collect. But immune cells are not a uniform group. A T cell, a B cell, and a macrophage each have a different DNA landscape. A clock trained on one cell type may therefore give a skewed reading.
The new approach tests whether a chromatin-accessibility-based clock performs consistently across multiple immune cell types. This matters because DNA openness partly determines which genes are active, and therefore how a cell responds to infection, inflammation, or other stressors. As cells age, that pattern changes. Some DNA regions that were once closed open up; others close down. This may contribute to the dysregulated immune responses seen in older age. According to the researchers, that is the central principle.
From population to individual: still a gap to bridge
Ageing clocks perform reasonably well at the population level. They predict average risks. For a single individual, however, their clinical value remains limited. Whether a higher biological age score actually predicts more disease or a shorter lifespan for you personally is hard to establish. That caveat applies to this chromatin clock as well.
The study reflects a broader trend: researchers want clocks that do more than produce a number. A clock that measures chromatin accessibility ties its output to a concrete biological process. That makes interpretation somewhat less abstract, even if the translation to clinical use remains a large step.
Search terms to explore further: chromatin accessibility aging clock, ATAC-seq immune cells age, epigenomic clock immune aging