At present, researchers consider there to be a bidirectional relationship between aging of the gut microbiome and aging of the immune system. The immune system gardens the microbial populations of the gut to minimize the number of problematic microbes, but growth in number of those inflammatory, disruptive microbes can contribute to loss of immune function. As is the case for many processes in aging, interactions between systems are as important as problems that occur within systems. Improving late life immune function should improve the gut microbiome. Conversely, restoring a more youthful balance of microbial populations in the gut microbiome should improve late life immune function.
The gut microbiome has come to prominence across research disciplines, due to its influence on major biological systems within humans. Recently, a relationship between the gut microbiome and hematopoietic system has been identified and coined the gut-bone marrow axis. It is well established that the hematopoietic system and gut microbiome separately alter with age; however, the relationship between these changes and how these systems influence each other demands investigation.
Since the hematopoietic system produces immune cells that help govern commensal bacteria, it is important to identify how the microbiome interacts with hematopoietic stem cells (HSCs). The gut microbiota has been shown to influence the development and outcomes of hematologic disorders, suggesting dysbiosis may influence the maintenance of HSCs with age. Short chain fatty acids (SCFAs), lactate, iron availability, tryptophan metabolites, bacterial extracellular vesicles, microbe associated molecular patterns (MAMPs), and toll-like receptor (TLR) signalling have been proposed as key mediators of communication across the gut-bone marrow axis and will be reviewed in this article within the context of aging.
Link: https://doi.org/10.1...yon.2024.e32831
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