DISCUSSIONS Thymic Involution in Ontogenesis: Role in Aging Program

Abstract

Despite the important role of the thymus as the central organ of the immune system, aging is accompanied by thymic involution in most mammals In addition to physiological conditions that change throughout life and control age-related thymus development, random events can cause thymic involution as well as reversible temporal hypoplasia or hyperplasia of the thymus. Rapid reduction of thymic cellularity takes place in young patients who have experienced trauma, chemotherapy, and other forms of stress. Mechanisms that determine the process of involution appear to depend on factors inherent in thymic tissue, such as the local production of cytokines and chemoattractants that promote mobilization, growth, and differentiation of T-cells predecessors in the thymus and on external factors, such as the levels of endocrine hormones and mediators released by intrathymic neurons of the autonomic nervous system Abstract-In most mammals, involution of the thymus occurs with aging. In this issue of Biochemistry (Moscow) devoted to phenoptosis, A. V. Khalyavkin considered involution of a thymus as an example of the program of development and further -of proliferation control and prevention of tumor growth. However, in animals devoid of a thymus (e.g. naked mice), stimulation of carcinogenesis, but not its prevention was observed. In this report, we focus on the involution of the thymus as a manifestation of the aging program (slow phenoptosis). We also consider methods of reversal/arrest of this program at different levels of organization of life (cell, tissue, and organism) including surgical manipulations, hormonal effects, genetic techniques, as well as the use of conventional and mitochondria-targeted antioxidants. We conclude that programmed aging (at least on the model of age-dependent thymic atrophy) can be inhibited