Gut microbiota markers associated with lifestyle and diet in extreme longevity: focus on Sardinian healthy centenarians. Gut microbiota markers associated with lifestyle and diet in extreme longevity: focus on Sardinian healthy centenarians

The present study is aimed at characterizing the gut microbiota (GM) and its functional profile in two groups of Sardinian subjects with a long healthy life expectancy, overall named Long-Lived Subjects (LLS) [17 centenarians (CENT) and 29 nonagenarians (NON)] by comparing them to 46 healthy younger controls (CTLs). In addition, the contribution of genetics and environmental factors to the GM phenotype was assessed by comparing a subgroup of 7 centenarian parents (CPAR) with a paired cohort of centenarians' offspring (COFF). The analysis was performed through Next Generation Sequencing (NGS) of the V3 and V4 hypervariable region of the 16S bacterial rRNA gene on the MiSeq Illumina platform. The Verrucomicrobia phylum was identified as the main biomarker in CENT, together with its members Verrucomicrobiaceae, Akkermansia, Akkermansia muciniphila, Prosthecobacter, Luteolibacter, Luteolibacter algae, Rubritaleaceae and Rubritalea; on the other hand, within the Firmicutes phylum the strongest associations were related to Acidaminococcaceae, Phascolarctobacterium and Phascolarctobacterium faecium. In NON, the strongest associations concern Actinobacteria phylum and related members Bifidobacteriaceae, Bifidobacterium spp., Coriobacteriaceae, Collinsella, Collinsella tanakaei, Eggerthellaceae, Slackia and Blautia coccoides. A strong association was also found for the taxa Streptococcaceae, Streptococcus, Streptococcus spp., Lactobacillaceae, Lactobacillus, Lactobacillus spp., Veillonellaceae, Veillonella, Veillonella dispar, Veillonella atypica, Thermicanaceae, Thermicanus, Bacillales Family X Incertae Sedis, all of which belong to Firmicutes phylum. In CTLs, the strongest associations were related to the Bacteroidetes phylum and its members Bacteroidaceae, Bacteroides and Bacteroides spp. Intestinal microbiota of CPAR and COFF did not differ significantly from each other after Bonferroni's post-hoc correction. The comparative functional metagenome prediction showed a common significant decrease in glycan degradation and a significant increase in the secretion system and in signal transduction (two-component system) in both LLS groups compared to CTLs. In CENT, the bacterial secretion system and the pathway of replication, recombination and reparation of proteins were also highly expressed, while the metabolism of pyrimidine, amino and nucleotide sugar was depleted, in comparison to CTLs. Several significant correlations between bacterial taxa and clinical and lifestyle data, especially with Mediterranean diet adherence, were observed. The intestinal microbial community structure of CENT and NON subjects was significantly different from that of CTLs. Our findings seem to define a harmonically balanced intestinal community structure, in which the increase in taxa associated with intestinal health would limit and counteract the action of potentially pathogenic bacterial species in centenarians. This intestinal microbial ecosystem would guarantee intestinal health, which would consequently be beneficial for the health of the whole organism. The GM of long-lived individuals showed an intrinsic ability to adapt to changing environmental conditions, as confirmed by functional analysis The results deriving from the GM analysis of centenarians’ offspring suggest that genetics and environmental factors act synergistically as a multifactorial cause in the modulation of GM towards a phenotype similar to that of centenarians, although these findings need to be confirmed by larger study cohorts and by prospective studies to clarify whether such microbial phenotypic patterns are predisposing factors in longevity.