Scientists have uncovered details regarding an immune response to a virus present in all human tissues, that kicks in the elderly and eliminates senescent, or aging, cells in the skin.

Senescent cells are those that stop dividing but do not die, accumulating in the body over time, fuelling chronic inflammation and contributing to conditions such as cancer and degenerative disorders.

Eliminating senescent cells from aging tissues has been found to restore tissue balance in mice, leading to an increased healthy lifespan. When a team of scientists, led by Massachusetts General Hospital (MGH), US, found that the number of senescent cells in samples from old individuals did not increase as the individuals got older, they realised that there is some mechanism kicking in to keep the aging in check.

The scientists have described their findings in the journal Cell.

Experiments have proved that in the elderly, certain immune cells called killer CD4+ T cells keep senescent cells from increasing.

Further investigating the procedure through which this happens revealed that aging skin cells express a protein, or antigen, produced by human cytomegalovirus, a pervasive herpesvirus that establishes lifelong latent infection in most humans without any symptoms.

By expressing this protein, senescent cells become targets for attack by killer CD4+ T cells.

“Most of us are infected with human cytomegalovirus, and our immune system has evolved to eliminate cells, including senescent cells, that upregulate the expression of cytomegalovirus antigens,” said senior author Shawn Demehri, director of the High Risk Skin Cancer Clinic at MGH.

These findings, highlighting a beneficial function of viruses living in our body, could have a variety of clinical applications.

“Our research enables a new therapeutic approach to eliminate aging cells by boosting the anti-viral immune response,” said Demehri. Demehri noted that the work may also lead to advances in cosmetic dermatology, for example in the development of new treatments to make skin look younger.     Source: PTI