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We currently know that healthy centenarian shows a gut microbiome rich in rare bacterial species, exhibits a unique microbial signature and metabolic fingerprint. However, very few is known about the effect of human aging on the gut virome community, especially in the context of inflammageing in elderly.
Every bacterial species is a potential host to an adapted virus. The interaction between our microbiome and virome has already been investigated in the clinical setting, and potentials are exciting, as the phage therapy to fight antibiotic-resistant bacterial infections… What about aging? Could our virome play a role? 😇
Bacteriophages bind to a suitable host and either propagate as a prophage by integrating into the host, or as virion production and lysis of the host (lysogenic and thelytic stages, respectively). Inflammatory molecules are known to induce lytic phage cycles and aging follows increasing inflammageing that creates a persistent pro-inflammatory environment, thus more lytic activity. However, during both the lysogenic and lytic state, viruses augment bacterial host metabolism by encoding auxiliary metabolic genes (AMG). For instance, phages encoding genes implicated in sulfur metabolism have recently been identified in human viruses, and a recent report stressed the influence of bacteriophages on the microbiome-brain axis, with effects on memory and cognition in a mouse model.
A study into the gut virome in Japanese centenarians, compared with younger adults and older individuals, found that:
The uncovered viral biodiversity consisted of 4,422 viral operational taxonomic units (vOTUs), including 1,746 undescribed vOTUs and abundant viral genera associated with Clostridium spp. and Alistipes spp. Increase of viral diversity a loss of core-virus abundance was detected.
There was a shift towards viral lytic activity in centenarians compared to the other groups (possibly due to a low-grade chronic inflammation?). The viral community experiences a state of lower viral to bacterial ratio (VBR) into adulthood, ultimately reverted in aging and in centenarians.
The centenarian virome contributes to key steps in sulfur metabolic pathways mediated by gut bacteria, especially the conversion of methionine to homocysteine and H2S release, promoting greater resistance to pathobionts and higher mucosal integrity.
Viral signatures correlated with centenarian bacterial profile, made by Clostridium scindens, Akkermansia muciniphila, Enterocloster bolteae and Parabacteroides distasonis. Healthy centenarians stand out as a separate population with high bacterial and viral richness.
The gut microbiota represents a key component in the healthy aging of centenarians, whose insights offer the key to work on longevity and sustainable, healthy lifespan. Do you share my vison?
Link to the paper: https://www.nature.com/articles/s41564-023-01370-6
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