Sex differences in markers of oxidation and inflammation. Implications for ageing

Sexual dimorphism is a key factor to consider in the ageing process given the impact that it has on life expectancy. The oxidative-inflammatory theory of ageing states that the ageing process is the result of the establishment of oxidative stress which, due to the interplay of the immune system, translates into inflammatory stress, and that both processes are responsible for the damage and loss of function of an organism. We show that there are relevant gender differences in a number of oxidative and inflammatory markers and propose that they may account for the differential lifespan between sexes, given that males display, in general, higher oxidation and basal inflammation. In addition, we explain the significant role of circulating cell-free DNA as a marker of oxidative damage and an inductor of inflammation, connecting both processes and having the potential to become a useful ageing marker. Finally, we discuss how oxidative and inflammatory changes take place differentially with ageing in each sex, which could also have an impact on the sex-differential lifespan. Further research including sex as an essential variable is needed to understand the grounds of sex differences in ageing and to better comprehend ageing itself.