A new study by scientists from University College London has found why older people are prone to cancer and infections of the skin.
They have shown that defective immunity in the skin is caused by an inability to mobilize essential defenses that would otherwise recognize threats and clear them before irreparable damage is done.
According to the researchers, this discovery could be important for preventing, managing or treating many age-related skin health problems.
"Older people are very prone to having infections generally and our studies in the skin of such subjects identifies one reason for this," said Professor Arne Akbar from UCL, who led the study.
"It's actually incredibly difficult to get to the root of exactly which mechanisms cause the diseases that show up as a factor of old age. We wanted to uncover the workings of skin health in order to see why older people don't deal well with skin infections and are prone to skin cancers also," Akbar added.
It has been known for some time that older people have compromised immunity and therefore defend themselves less well against infection and disease than younger people.
In the past, the reduction in skin health was put down to potential defects in the white blood cells called T-cells that would usually help to identify and clear infection.
However, when experiments were carried out with healthy young individuals under the age of 40 years and older individuals over the age of 70 years in this study, it was shown that in fact there is nothing wrong with the T-cells in the older group; instead it is the inability of their skin tissue to attract T-cells where and when they are needed that is the source of reduced immunity.
"Knowing this now raises the question of whether the same defect also occurs in other tissues during ageing. Is it possible that, for example, lung tissues also fail to give out the right message to T-cells to bring them into the tissue to do their job? This may explain, in part, the higher rates of lung cancer, chest infections and pneumonia in older people, perhaps," Akbar said.
"We also, obviously, would like to know if it is possible to reverse the skin defect in older people. We've done some experiments that show that, at least in the test tube, it is possible to make older skin express the missing signals that attract T cells. This indicates that, in principle, the defect is entirely reversible. Once we get to the bottom of exactly which part of the signal to T-cells has gone wrong we might then be in a position to intervene to boost skin immunity in older people," Akbar added.
The study will be published in 31 August edition of the Journal of Experimental Medicine.