Immunity and Aging

In this chapter, we will outline the impact of the immune system on the process of aging. Firstly, we discuss the general role of immunity in detecting and neutralizing pathogens, in order to reduce the global burden of infectious diseases. We distinguish the features and cell types of innate and adaptive immunity and describe their response over time after contact with an antigen. Then, we describe that epigenetic regulation is fundamental for the differentiation of immune cells, as well as for their adaptive response to several environmental challenges, such as microbe infections. In this context, we discuss trained immunity and the impact of transcription factors, such as the vitamin D receptor (VDR), for a well-functioning immune system. Next, we present the principles of acute inflammation caused by pathogen-associated molecular patterns (PAMPs) and compare it with systemic chronic inflammation, which is primarily initiated by damage-associated molecular patterns (DAMPs). The latter develops during aging and leads to deterioration of the organism via inflammaging. Finally, we describe functional decline based on the aging immune system, such as the decrease production of naïve T cells and changes in the microbiome.