Gut microbiota as the key controllers of “healthy” aging of elderly people

Abstract

Extrinsic factors, such as lifestyle and diet, are shown to be essential in the control of human healthy aging, and thus, longevity. They do so by targeting at least in part the gut microbiome, a collection of commensal microorganisms (microbiota), which colonize the intestinal tract starting after birth, and is established by the age of three. The composition and abundance of individual microbiota appears to continue to change until adulthood, presumably reflecting lifestyle and geographic, racial, and individual differences. Although most of these changes appear to be harmless, a major shift in their composition in the gut (dysbiosis) can trigger harmful local and systemic inflammation. Recent reports indicate that dysbiosis is increased in aging and that the gut microbiota of elderly people is enriched in pro-inflammatory commensals at the expense of beneficial microbes. The clinical consequence of this change remains confusing due to contradictory reports and a high degree of variability of human microbiota and methodologies used. Here, we present the authors’ thoughts that underscore dysbiosis as a primary cause of aging-associated morbidities, and thus, premature death of elderly people. We provide evidence that the dysbiosis triggers a chain of pathological and inflammatory events. Examples include alteration of levels of microbiota-affected metabolites, impaired function and integrity of the gastrointestinal tract, and increased gut leakiness. All of these enhance systemic inflammation, which when associated with aging is termed inflammaging, and result in consequent aging-associated pathologies.

Adsorptive granulomonocytapheresis alters the gut bacterial microbiota in patients with active ulcerative colitis

“…In turn, the gut microbiota influences the innate and adaptive immune systems in the human body 28 . Recent studies indicate that dysbiosis may be increased by the aging and that the gut microbiota performed enriched in pro‐inflammatory commensals at the expense of beneficial microbes in the elderly people, the changing of gut microbiota maybe triggers a chain of pathological and inflammatory events 29 …”

Spontaneous and Induced Tumors in Germ-Free Animals: A General Review

“…The similarity with tumors occurring in human old population or in immune-suppressed patients suggests that in these cases the contribution of the microbiome is basically less relevant than hormonal and immunological changes occurring with aging and immune impairment. Nevertheless, dysbiosis is observed to occur more frequently with the aging and can represent an additionally harmful condition increasing the constitutive risk of degenerative events [86]. Anyway, the "good" and the "bad" of bacteria in cancer development start to be better described due to the discovery of unexpected anti-cancer properties as opposed to the dysbiosis sustaining the carcinogenic processes [87].…”

A Dual-Route Perspective of SARS-CoV-2 Infection: Lung- vs. Gut-specific Effects of ACE-2 Deficiency

“…Evidence is accumulating that implicates the gut microbiota dysbiosis in the pathogenesis, severity, and disease course of COVID-19. The severity of COVID-19 is increased in the older population, which may be related to reduced bacterial diversity and enrichment in pro-inflammatory commensals with age (Ragonnaud and Biragyn, 2021).…”