Innate Immunosenescence and Its Impact on Healthy Ageing

Early recognition and elimination of invading pathogens is the defining feature of innate immunity. However, it has become apparent in recent years that the function of the innate immune system extends beyond host protection, with studies demonstrating roles for innate immune cells in immune modulation [88], the resolution of inflammation [12, 13], wound healing [89] and the clearance of senescent cells [11]. Thus, with these observations in mind, could innate immunosenescence have more far reaching consequences for older adults than just simply increasing their susceptibility to infection? In this section, we consider the wider-impact that age- related changes in NK cell (Fig. 1.2), neutrophil and macrophage biology may have on older adults and discuss how a low-grade chronic up-regulation in circulating inflammatory mediators may underlie the development of several age-related pathologies.

NK cell immunosenescence and its impact upon the health and well-being of older adults

Fig. 1.2 NK cell immunosenescence and its impact upon the health and well-being of older adults. Aside from the associations reported in older adults between reduced NK cell function and increased infection-related morbidity and mortality rates [65-67], age-related changes in NK cell cytokine/chemokine production (i), surface phenotype (ii) and NKCC (iii) may have additional consequences for the health of older adults. These include; (a) the accumulation of senescent cells and the subsequent development of such age-related pathologies as sarcopenia and cardiovascular disease (CVD) [14], (b) impaired resolution of inflammatory responses and increased immune- mediated tissue damage as a consequence of impaired NK-mediated induction of neutrophil, DC and CD4+ T cell lysis and (c) reduced vaccine efficacy as a result of aberrant NK-DC cross talk

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