Bacterial DNAemia in older subjects and nonagenarian offspring and association with redox biomarkers : results from MARK-AGE Study

Abstract

Aging and age-related diseases have been linked to microbial dysbiosis with changes in blood bacterial DNA concentration. This condition may promote chronic low-grade inflammation, which can be further aggravated by antioxidant nutrient deficiency. Low plasma carotenoids are associated with an increased risk of inflammation and cellular damage and predict mortality. However, no evidence is yet available on the relationship between antioxidants and the blood bacterial DNA (BB-DNA). Therefore, this study aimed to compare BB-DNA from (i) GO (nonagenarian offspring), (ii) age matched controls [(Randomly recruited Age-Stratified Individuals from the General population (RASIG)] and (iii) Spouses of GO (SGO) recruited in the MARK-AGE project, as well as to investigate the association between BB-DNA, behavior habits, Charlson comorbidity index (CCI), leucocyte subsets, and the circulating levels of some antioxidants and oxidative stress markers.BB-DNA was higher in RASIG than GO and SGO, while GO and SGO participants showed similar values. BB-DNA increased in smokers and in males with CCI≥2 compared to those with CCI≤1 within RASIG. Moreover, BB-DNA was positively associated with lymphocyte, neutrophil and monocyte counts, but not with self-reported dietary habits. Higher quartiles of BB-DNA were associated with low lutein and zeaxanthin and elevated malondialdehyde plasma concentrations in RASIG. BB-DNA was also positively correlated with nitric oxide levels.Herein, we provide evidence of a reduced BB-DNA in individuals from long-living families and their spouses, suggesting a decreased microbial dysbiosis and bacterial systemic translocation. BB-DNA was also associated with smoking, CCI, leukocyte subsets and some redox biomarkers in older subjects.