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

Background & objectives: 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). Aims: 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. Discussion: 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. Conclusion: 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.