Immunology Of Aging

The rapidity of scientific progress over the last few years guarantees the utility of this new collection of state-of-the-art reviews on the immunology of aging, which is the result of extensive collaboration of more than sixty of the greatest thinkers and scholars in the field, in cooperation with a number of junior colleagues. The book summarizes current knowledge on the cellular and molecular aspects of the aging immune system and their clinical relevance, providing insights into the effects of the aging process on susceptibilities to those diseases most common among elders. The retrieval strategies used to slow down the decline in the immune system in the elderly are another subject detailed extensively. By providing a broad overview of immunosenescence and its consequences, as well as their potential modulation, this book will fill a gap in a timely manner. It will be of value to all immunologists, whether novice or experienced, as well as geriatricians and epidemiologists.

In the classic sense, immunity is the ability of an organism to resist disease. On the one hand, we must distinguish between age and disease; on the other hand, the interaction between them is of considerable theoretical and practical interest. To the gerontologic research community, therefore, immunity also becomes the ability of an organism to resist age. Were the immune and other protective systems of the body able to maintain themselves over the course of time, and if there were no degradation related to age, the everyday loss of energy and vitality that occurs in the lives of older people as a consequence of viruses, arthritis, and other debilitating circumstances would be greatly lessened. The objective of gerontologists is not just to extend the life span but rather to improve the vigor, health, and quality oflife. To date, we have not developed a single index to measure immunity that is of use clinically in the evaluation of older people and of their immunologic compe tence. It may not be surprising that just such a clinical index may be available in the not-too-distant future. We can also look forward to the assembling of a greater body of information explaining how and why the immune system fails with age while, paradoxically, the incidence of autoimmune diseases increases with age. It is this latter phenomenon that may playa part in a wide range of chronic diseases from rheumatoid arthritis to senile dementia.

This book contains two personal reminiscences of historical importance to research on stress and infectious disease. It deals with perspectives on immunity, aging, and disease and the prospects for immunorestoration in the treatment of immunodeficiency arising from aging and stress.

The world population presents an increased percentage of individuals over 65 years old and the fastest growing subgroup is over 85 years old. The increase in life expectancy observed in the last century has not been synonymous with extra years lived in good health (disability-free years). Population studies have shown that as individuals age, they can present a great heterogeneity of ability and health. Therefore, aging has been associated for some individuals with disabilities and hospitalizations. Deaths related to infectious pathogens are increased in the aging population mainly due to pneumonia and influenza whereas Cytomegalovirus, Epstein-Barr virus, among other viruses seem to contribute to the low-grade inflammatory process observed (inflammaging). Aging is a complex and multifactorial process in which functions of the organism are adjusted (remodelled) in order to deal with damaging events during life. One of the most important changes in aging individuals occurs in the immune system (innate and adaptive responses) with consequences such as poor response to new infections and vaccinations; increased susceptibility to cancer development and autoimmune diseases; frailty, and organ dysfunction. In addition, it has been proposed that immunosenescence not only reflects the aging of the organism but also contributes to this process. Bone marrow presents decreased hematopoiesis, the thymus undergoes involution and lymphoid organs (lymph nodes, spleen) also present reduced functionality. Therefore, cells derived, matured, or residing in these tissues decline in number and function. These changes have been identified in experimental models, in vitro conditions, peripheral blood, and biopsies via biomarkers such as cell phenotype, stimulus-induced proliferation, cytokines and antibodies levels. Telomere length and telomerase activity also decline in bone marrow-derived and peripheral blood cells and have been shown to play a role in immunosenescence. More recently, the investigation of short non-coding RNA molecules (microRNAs; miRNAs) pointed to this system as a possible control of aging-related mechanisms. Data obtained on these markers for aging individuals could lead to the generation of a marker panel for pathology prediction, to indicate interventions, and to evaluate the efficacy of interventions. Interventions such as nutrition supplements, exercise, vaccination (different dose, concentration of antigen, adjuvants) have been proposed to circumvent age-related diseases. Considering the heterogeneity in the aging process, further investigation is vital before the indication of interventions for aging individuals. As the extension of life expectancy is a reality, it is a challenge to understand how the aging population copes with the remodelling of the organism and how interventions could provide longevity in good health.

Aging inspired a large number of theories trying to rationalize the aging process common to all living beings. In this publication the most important environmental and intrinsic mechanisms involved in the aging process and in its pathological consequences are reviewed. Furthermore theoretical and experimental evidence of the most important theoretical elements based on Darwinian evolution, cellular aging, role of cell membranes, free radicals and oxidative processes, receptor-mediated reactions, the extracellular matrix and immune functions as well as the most important environmental and intrinsic mechanisms involved in the aging process and in its pathological consequences are discussed. These presentations of theories and related experimental facts give a global overview of up to date concepts of the biology of the aging process and are of essential reading not only for specialists in this field but also for practitioners of scientific, medical, social and experimental sciences.