In the young body, less than 1% of the cells are senescent. In old age, this number can reach up to 15% in certain body tissues.

Over time, our bodies build up these senescent cells – commonly known as aging cells. And while studies show that removing these cells could delay age-related diseases, reduce inflammation, and save lives, there is currently no drug that can target these cells directly. Based on a recent finding, researchers at the Weizmann Institute of Science are now suggesting an alternative approach.

Led by Prof. Valery Krizhanovsky, Weizmann researchers discovered that senescent cells from a mouse’s lung express high quantities of proteins – particularly PD-L1 – which repress the immune system.

Moreover, an accumulation of senescent cells, and the resulting increase of PD-L1, doesn’t just affect aging. Current studies show that these cells may also contribute to chronic lung diseases and other disorders.

With this knowledge, Prof. Krizhanovsky’s team began exploring advances in immunotherapy as a removal method for senescent cells.

Once it became clear that senescent cells – like cancer cells – express high levels of PD-L1, the researchers hypothesized a new way to target them. Using an antibody already approved for treating various kinds of cancer, researchers were able to activate T cells – the immune system’s warriors – which led to a reduction in the number of senescent cells.

“While the treatment we examined did not stop the aging clock, it did manage to get rid of senescent cells in mice and even reduce the release of small proteins that encourage inflammation in old age and in chronic diseases,” Prof. Krizhanovsky says. “This discovery raises hopes that immunotherapy can be used in the future for treating not only cancer but also age-related diseases and chronic inflammation.”