Immune System Rejuvenation: Inhibit inhibitors!
Weakened immunity is a serious problem for elderly people. The age-related decrease in the effectiveness of the immune system makes a person more susceptible to infectious diseases and makes recovery more difficult.
According to Professor Arne Akbar from University College London, every infectious disease transmitted by a person increases the proportion of inactive white blood cells in the terminal stage of differentiation and showing signs of physiological aging. Perhaps this phenomenon arose as a result of evolution as a mechanism of protection against the appearance of malignant tumors, but its side effect is a gradual weakening of the body's defenses.
Until now, it was believed that the aging of immune cells is mainly due to the shortening of the length of the end sections of chromosomes. These sections of DNA – telomeres – are shortened with each cell division until a critical length is reached, after which the cell loses its ability to function normally. This means that our immune cells are programmed for a certain life span, so if a person lives longer than the time allotted to his immune system, it can no longer provide him with effective protection.
However, when researchers working under the guidance of Professor Akbar analyzed the state of white blood cells in several blood samples, it turned out that some of the T-lymphocytes are inactive, despite the long telomeres. This fact indicated the existence of a previously unknown alternative mechanism for inactivating cells of the immune system.
Further study of the issue showed that after activation of the T-cell receptor caused by an encounter with an infectious agent, a signaling mechanism mediated by p38 MAPK kinase (one of the mitogen-activated protein kinases – a class of enzymes involved in cellular reactions to various stress factors, as well as involved in the processes of cellular differentiation and apoptosis) is triggered in cells. This mechanism inhibits (suppresses) the synthesis of telomerase, preventing it from restoring telomeres in "battle-ridden" cells, which leads to irreversible inactivation of T-lymphocytes.
However, scientists managed to restore the viability of cells inactivated in this way in laboratory conditions. To do this, they used experimental drugs – inhibitors of p38 MAPK kinase, currently undergoing testing as agents for the treatment of a number of diseases. Inhibitors of inhibitors caused the same effect as "minus on minus" – canceled the inactivation of T-lymphocytes. Unfortunately, not forever, but until the next meeting with any antigen.
The results were very inspiring to the researchers. In the future, they plan to test the possibility of using such drugs to temporarily restore the immune function of elderly people. Unfortunately, the aging of the immune system is an integral part of the aging process of the entire body, and the constant use of drugs that restore telomerase activity can lead to uncontrolled cell division with all the ensuing consequences. Therefore, we can only hope for temporary activation of T-lymphocytes, and it is at least premature to talk about complete and final rejuvenation of the immune system.
Article by Diletta Di Mitri et al. Reversible Senescence in Human CD4+CD45RA+CD27– Memory T Cells is published in the September issue of The Journal of Immunology.
Evgeniya Ryabtseva
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of the Biotechnology and Biological Sciences Research Council:
Research opens the possibility of temporarily reversing ageing in the immune system.
30.08.2011