Rejuvenate the aging immune system?
Improving the quality of medical care and living conditions in general have significantly increased people's life expectancy. However, a person pays a price for this: as they age, the immune system loses its functionality, which leads to an increase in the body's susceptibility to infections. Researchers at the Helmholtz Center for the Study of Infectious Diseases in Braunschweig (Germany), working under the guidance of Eva Medina, are studying this aspect of aging on a mouse model of age-associated susceptibility to infections.
A comparison of the immune responses of young and old mice developing with bacterial infection showed that the tissues of old animals contain significantly fewer macrophages – cells that play an important role in eliminating pathogenic bacteria that have entered the body. The authors suggested that an insufficient number of protective cells may be the reason for the susceptibility of an aging organism to infectious diseases. Indeed, the introduction of macrophage colony-stimulating factor (M-CSF) into old mice led to an increase in the number of these cells and an increase in the effectiveness of their fight against the infectious agent. The results of the work are published in the Journal of Pathology in the article "Streptococcus pyogenes infection in mice: underlying immune dysfunction and strategy to enhance immunity".
The main task of the immune system is to protect the body from infections, provided by the joint work of cells of various types and molecular factors. Unfortunately, the immune system ages together with a person, which leads to more frequent development and more severe course of infectious diseases. All this indicates that maintaining the functional state of the immune system is the key to prolonging youth and ensuring healthy aging.
Currently, researchers are actively studying age-related changes in the immune system in the hope of developing effective methods of intervention in this process. In their work, the authors used young (aged 2-3 months) and old (older than 20 months, which corresponds to 70-80 years in humans) mice to study specific changes in the immune system leading to an age-associated increase in susceptibility to hemolytic streptococcus (Streptococcus pyogenes). This microorganism is the cause of severe life-threatening infectious diseases in the elderly. Animals were injected subcutaneously and intravenously with various doses of the pathogen, after which the course of the disease was monitored. As a result, it turned out that, compared with young animals, older mice were characterized by faster development of the disease, earlier onset of deaths and higher mortality even with the introduction of smaller doses of the pathogen.
The study of the immune mechanisms involved in the fight against infection, namely the functioning of macrophages, which are the first line of defense of the body against bacterial infections, showed that macrophages of old animals destroy pathogens as effectively as cells of young mice, but their number in tissues is significantly reduced.
Taking into account the well-known fact that the number of macrophages in tissues depends on the level of production of macrophage growth factor by other cells of the immune system, the authors decided to test how the introduction of this factor can affect the population of tissues of elderly mice with macrophages and the resistance of animals to infections. According to scientists' expectations, the procedure significantly increased the population of tissue macrophages and increased the resistance of old mice to infection.
The authors state that their results indicate the expediency of periodic administration of macrophage growth factor to elderly people. This preventive measure will ensure the maintenance of the population of tissue macrophages and increase the efficiency of the immune system as a whole.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on ScienceDaily: Rejuvenating the Old Immune System.
01.02.2010