Our immune system changes with age. A recent study shows exactly how immune cells age and what influence infections and vaccinations can influence this process: using a big data approach, researchers led by CiiM Director Prof. Yang Li have established a computer model called the “Single-Cell Immune Aging Clock”, which can be used to determine aging processes within individual immune cells. The study has been published in the journal Nature Aging.

For their study, the scientists used thousands of transcriptome datasets – the set of all active genes in a cell at a given time – for five different immune cell types from freely accessible data and literature sources. In total, these were data sets of more than two million immune cells from blood samples of around 1,000 healthy people aged between 18 and 97 years. They used machine learning to create a computer model, which they called the “Single-Cell Immune Aging Clock”.
“We were able to identify specific genes for each type of immune cell that are involved in important immunological processes and whose activity changes during the aging process. These serve as marker genes for the respective immune cell type and as a reference in the subsequent application of the model,” explains Prof. Li. “Incidentally, the genes we identified play a decisive role in the development of inflammatory processes. It is well known that aging processes are particularly associated with inflammatory processes. We were able to confirm this once again with our study.”

The research team then applied the aging clock in two case studies. They wanted to find out how a COVID-19 infection or a tuberculosis vaccination affects the ageing processes within the different immune cell types. In COVID-19 patients, ageing processes were only evident in the monocytes. However, ageing was significantly less pronounced in people with a mild course of the disease. “Our results suggest that severe infections can cause our immune cells to age more quickly,” says Prof. Li. ” But – and this is good news – these changes seem to be reversible: After about three weeks, as COVID-19 patients slowly recover, the monocytes start to return to their original age profile.”

In the second case study, the researchers used the aging clock to examine the age of different immune cell types in people after a tuberculosis vaccination. Here, the team discovered an interesting correlation: the vaccination had very different effects within one immune cell type, the so-called CD8 T cells, depending on how many inflammatory processes were currently taking place in the body. However, in people with high inflammation levels, the vaccination had a rejuvenating effect on the immune cells.

The research team is making the “Single-Cell Immune Aging Clock” freely available so that it can be used for further research projects.

The text is based on a press release of the HZI by Nicole Silbermann.

To the photo: With increasing age, the activity of our genes changes. Researchers have now developed an ‘Aging Clock’ to determine this process in immune cells. Copyright: Karin Kaiser/MHH/KI generiert