Exploring the complex relations between inflammation and aging (inflamm-aging): anti-inflamm-aging remodelling of inflamm- aging, from robustness to frailty

Abstract

"Inflamm-aging" denotes the up-regulation of certain pro-inflammatory cytokines at older ages, and associated chronic diseases. It is well known that blood levels of cortisol also increase with age, an increase commonly considered to be due to activation of the Hypothalamus- Pituitary- Adrenal (HPA) axis by many non-specific stressors. On the contrary, herein I describe how the activation of Hypothalamus- Pituitary-Adrenal (HPA), far from being unspecific, constitutes: a) the main specific response and counterbalance to "Inflammaging" ('anti-inflammaging'), b) an explanation for the well known paradox of immune-senescence: i.e. the coexistence of inflammation and immunodeficiency, as well as c) a complex mechanism of remodelling elicited by inflammaging, explaining the long and winding pathophysiological road that goes from robustness to frailty. Indeed, the phenomenon of anti-inflammaging, mainly exerted by cortisol, with the passage of time becomes the cause of a marked decline of immunological functions, and its coexistence with the increased levels of pro-inflammatory cytokines of inflammaging, ultimately have negative impacts on metabolism, bone density, strength, exercise tolerance, the vascular system, cognitive function, and mood. Thus inflammaging and anti-inflammaging together determine many of the progressive pathophysiological changes that characterize the "aged-phenotype", and the struggle to maintain robustness finally results in frailty.The same consequences also result the age-dependent decline of dehydroepiandrosterone (DHEA).