Peripheral Immunosenescence and Central Neuroinflammation: A Dangerous Liaison - A Dietary Approach.

Abstract

In old people, both innate and adaptive immune responses are impaired, thus leading to a condition of systemic inflamm-ageing, even including the involvement of the central nervous system (CNS). Here, main mechanisms of the immune ageing and neuro-inflammation will be discussed along with the dietary approaches for the modulation of age related diseases. Neuroinflammation is caused by the passage of inflammatory mediators through the brain blood barrier to CNS. Then, in the brain, antigenic stimulation of microglia and/or its activation by peripheral cytokines lead to a robust production of free radicals with another wave of proinflammatory cytokines which, in turn, causes massive neuronal damage. Also, infiltrating T cells [T helper (h) and T cytotoxic cells] contribute to neuronal damage. Additionally, a peripheral imbalance between inflammatory Th17 cells and anti-inflammatory T regulatory cells seems to be prevalent in the aged brain, thus leading to a proinflammatory profile. Alzheimer's disease, Parkinson's disease and multiple sclerosis will be described as typical neurodegenerative diseases. Finally, modulation of the immune response thanks to the anti-oxidant and anti-inflammatory effects exerted by dietary products and nutraceuticals in ageing will be discussed. Special emphasis will be placed on polyunsaturated fatty acids, polyphenols, micronutrients and pre-probiotics and synbiotics. Ageing is characterized by an imbalance subversion of the immune system with a condition of inflamm-ageing. Neuroinflammation and neurodegenerative diseases seem to be a central manifestation of a peripheral perturbation of the immune machinery. Dietary products and nutraceuticals may lead to a down-regulation of the oxidative and pro-inflammatory profile in ageing.