The Unexplored World of Human Virome, Mycobiome, and Archaeome in Aging

Abstract

In the last decades, improvements in different aspects of sanitation, medical care, and nutrition, among others, have permitted an increase in the average lifespan of human population around the world. These advances have stimulated an increased interest in the study of the aging process and age-sensitive characteristics, such as the microbial community that colonizes the human body (microbiome). The human microbiome is composed of bacteria (bacteriome), archaea (archaeome), fungi (mycobiome), and viruses (virome). To date, research has mainly been centered on the composition of the bacteriome, with other members remain poorly studied. Interestingly, changes in the composition of the microbiome have been implicated in aging and age-related diseases. Therefore, in the present perspective, we suggest expanding the scope to research to include the role and the possible associations that the other members of the microbiome could have in the aging organism. An expanded view of the microbiome would increase our knowledge of the physiology of aging and may be particularly valuable for the treatment and diagnosis of age-related diseases.

The role of gut mycobiome in health and diseases

“…Fungal community increased with age in infancy but decreased when they grow up to young adults ( Figure 2 ). 88 However, gut mycobiota alteration in elder subjects was less reported, 114 and most of the older adults studied were reported with known diseases including hypertriglyceridemia (HG), 115 Alzheimer’s disease (AD), 51 , 116 and type 2 diabetes mellitus (T2DM). 19 In Denmark, gut mycobiome analysis was performed in 100 elderly participants (70 with normotriglyceridemia versus 30 with hypertriglyceridemia) aged 65–81 years by ITS 2 amplicon sequencing on their fecal samples.…”

Features of the Skin Microbiota in Common Inflammatory Skin Diseases

“…A large number of microorganisms (bacteria, fungi, viruses) are found on the surface of or inside numerous human tissues and fluids, including skin, mammary glands, placenta, semen, uterus, ovarian follicles, lungs, saliva, oral mucosa, conjunctiva, and the biliary and gastrointestinal tracts. The largest share [ 2 ] of the microbiota is made up of bacteria, followed by fungi, viruses, and arthropods. Changes in human skin microbiota composition and/or functionality are believed to trigger immune dysregulation, and consequently an inflammatory response, thereby playing a potentially significant role in the clinical manifestations of inflammatory skin diseases [ 3 ].…”

The gut microbiome and frailty

“…The human virome consists of viruses that perpetually reside in host cells, endogenous viral elements integrated into cellular components, and viruses that infect other microbiota elements, particularly bacteriophages which inhabit bacteria. 162,163 The herpesviridae family member cytomegalovirus (CMV) has been particularly prominently identified as having a significant association with the immunosenescent phenotype. CMV is highly ubiquitous in the general population, mostly latent in immunocompetent hosts and persistent in its presence in aging populations.…”

“…CMV is highly ubiquitous in the general population, mostly latent in immunocompetent hosts and persistent in its presence in aging populations. 162,164 Clonal expansion of memory T cells specific for CMV antigens has been observed with age and also associated with heightened pro inflammatory cytokine production. Marked CMV clonal expansion in older adults has been postulated to restrict the T cell repertoire, with the potential to impair responses to other microbial antigens.…”

“…The gut virome constitutes the largest human virome compartment with an estimated 10 9 viral particles per gram of intestinal content. 159,162,163 This compartment consists predominantly of bacteriophages that infect prokaryotic cells, primarily inhabiting the gut bacterial microbiome. 158 Studies suggest that bacteriophages can modify the function of the bacterial microbiome.…”