Zinc–gene interaction related to inflammatory/immune response in ageing

Abstract

The pivotal role played by zinc-gene interaction in affecting some relevant cytokines (IL-6 and TNF-a) and heat shock proteins (HSP70-2) in ageing, successful ageing (nonagenarians) and the most common age-related diseases, such as atherosclerosis and infections, is now recognized. The polymorphisms of genes codifying proteins related to the inflammation are predictive on one hand in longevity, on the other hand they are associated with atherosclerosis or severe infections. Since the health lifespan has a strong genetic component, which in turn also affected by nutritional factors like zinc, the association of these polymorphisms with innate immune response, zinc ion bioavailability and Metallothioneins (MT) homeostasis is an useful tool to unravel the role played by zinc-gene interactions in longevity, especially due to the inability of MT in zinc release in ageing and chronic inflammation. In ageing, this last fact leads to depressed innate immune response for host defence. In contrast, in very old age the inflammation is lower with subsequent more zinc ion bioavailability, less MT gene expression and satisfactory innate immunity. Therefore, the zinc-gene (IL-6, TNF-a, Hsp70-2) interactions, via MT homeostasis, are crucial to achieve successful ageing. Human genes and longevityAgeing is a universal phenomenon that affects nearly all of animal species. According to Helfand and Rogina [69], ageing can be characterized as: (1) an inevitable consequence of being a multicellular organism; (2) associated with a random, passive decline in function; (3) leading to a global loss of homeostasis over time and (4) mortality increasing with ageing. Evolutionary studies on ageing have drawn the attention on the importance of the genetic mechanisms involved in somatic maintenance and repair that secure longevity [82]. Evidence from model organisms has indicated that subtle variation in the genes can dramatically influence lifespan. However, findings on potential candidate genetic mechanisms determining ageing and lifespan in model organisms are far to explain variations in human populations because phenotypes are critically dependent on the setting in which genes are expressed, while laboratory conditions and modern environments are markedly dissimilar [86]. Genetic analysis of human ageing is mainly approached by searching the genetic basis of susceptibility to major geriatric disorders or the allelic contributions to exceptionally long life span. It is just thanks to these last studies in centenarians populations that several candidate longevity genes or pathways including PON1 [19,130], IGF1/insulin pathway [84,120], elements of lipid metabolism [12], stress response [34] and inflammatory response have been identified [53].Genes related to inflammation and stress response, in particular the pro-inflammatory cytokines IL-1, IL-6, TNFalpha, the anti-inflammatory cytokine IL-10, the HSP70 chaperones and the regulators of trace elements homeostasis, metallothioneins (MT), seem particularly relevant taking into accoun...

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