Age-related aging of the immune system (1)

Between the death of immune cells and the activation of cytokine synthesis

Immuno senescence in aging: between immune cells depletion and cytokines up-regulation
Maria Teresa Ventura et al., Clinical and Molecular Allergy, 2017.
Translated by Evgenia Ryabtseva
For links, see the original article.

Introduction

Aging of the immune system is a relatively new area of research associated with a linear increase in average life expectancy, which began in the nineteenth century and continues to this day. The most important sign of aging of the immune system is the accumulation of memory cells and effector cells in the "immunological space", which occurs as a result of stimulation under the influence of repeated clinical and subclinical infections, as well as prolonged exposure to antigens (inhaled allergens, food, etc.).

This condition of chronic inflammation, characteristic of aging of the immune system, has a significant impact on survival and the general condition of the body. In fact, the state of senile decrepitude develops much less frequently in conditions of rare contacts with viral pathogens and parasitic diseases. Moreover, the aging of the immune system is characterized by a special "remodeling" induced by oxidative stress.

Apoptosis plays a central role in old age – a period when the ability of cells to apoptosis may change. Remodeling of apoptosis, in combination with "inflamaging" and stimulation of immune reactions with subsequent secretion of pro-inflammatory lymphokines, is the main determining factor for the rate of aging and longevity, as well as the development of most common age-related diseases and tumors. The changes also affect innate immunity – the first line of defense, providing a rapid but nonspecific reaction mediated mainly by monocytes, natural killer cells and dendritic cells, the action of which creates prerequisites for the formation of an adaptive (acquired) immune response mediated by T- and B-lymphocytes and having a slower but highly specific effect.

Markers of "inflameiding" during the development of an adaptive immune response in centenarians are characterized by a decrease in the number of "naive" T cells. A decrease in the population of naive CD8 cells may be associated with the risk of morbidity and death, as well as a combination of an increase in the number of CD8+ cells with a decrease in CD4+ T-lymphocytes and CD19+ B-lymphocytes. The immune functions of the elderly are weakened due to the depletion of the population of naive T cells (CD95-), which are replaced by clonal expansion of CD28−T lymphocytes.

Conclusions

Increased levels of pro-inflammatory cytokines are associated with dementia, Parkinson's disease, atherosclerosis, type 2 diabetes mellitus, sarcopenia and a high risk of morbidity and mortality. Proper modulation of immune responses and the phenomenon of apoptosis can be useful for suppressing the development of age-related degenerative diseases, as well as inflammatory and neoplastic diseases.

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