The passage of time may be linear, but the journey of human aging is anything but straightforward. Instead of a gradual transition, our lives experience a series of staggered growth phases, moving from the rapid development of childhood, through the plateau of early adulthood, and then accelerating as the decades pass. Recent research has pinpointed a significant turning point in this aging trajectory: around the age of 50. Following this milestone, the rate at which our tissues and organs age increases markedly, with blood vessels being particularly vulnerable to decline.
A groundbreaking study conducted by scientists from the Chinese Academy of Sciences has shed light on this phenomenon. The researchers focused on aging-related protein changes, developing tissue-specific proteomic age clocks to characterize the aging trajectories of various organs. Their temporal analysis indicated that the aging process experiences an inflection point around age 50, particularly highlighting the early aging of blood vessels, which are known to be significantly susceptible to the effects of aging.
While humans enjoy a remarkably extended lifespan compared to most other mammals, this longevity comes with its drawbacks. One notable consequence is the decline in organ function, which subsequently increases the risk of chronic diseases as we age. Despite this, our understanding of how individual organs age remains limited. To address this gap, the researchers undertook a comprehensive investigation into how proteins within different tissues evolve over time.
The study involved collecting tissue samples from 76 organ donors aged between 14 and 68 years, all of whom had died from accidental traumatic brain injuries. These samples encompassed seven of the body’s major systems: cardiovascular, digestive, immune, endocrine, respiratory, integumentary, and musculoskeletal. Blood samples were also analyzed. The research team meticulously cataloged the proteins present in these systems, noting how their levels fluctuated with the age of the donors.
In comparing their findings with a database of diseases and their associated genes, the researchers discovered that the expression of 48 disease-related proteins increased with age. These proteins were linked to various conditions, including cardiovascular diseases, tissue fibrosis, fatty liver disease, and liver-related tumors. Notably, the most significant changes were observed between the ages of 45 and 55, during which many tissues underwent substantial proteomic remodeling. The aorta showed particularly pronounced changes, indicating its heightened susceptibility to aging.
To validate their findings, the researchers isolated a protein associated with aging found in the aortas of mice. When this protein was injected into young mice, the results were telling: treated mice exhibited reduced physical performance, decreased grip strength, diminished endurance, and compromised balance and coordination compared to their untreated counterparts. Furthermore, these mice displayed significant markers of vascular aging.
Previous studies have identified additional peaks in the aging process, occurring around ages 44 and 60. The findings from this latest research suggest that aging is a complex, step-wise process that affects different systems at various points in time. By deciphering how aging impacts specific body parts at distinct stages, researchers aim to develop targeted medical interventions that could ease the aging process.
The researchers express their commitment to constructing a comprehensive multi-tissue proteomic atlas that spans 50 years of human aging. This effort aims to illuminate the mechanisms underlying proteostasis imbalance in aging organs and to reveal both universal and tissue-specific aging patterns. These insights hold the potential to facilitate the creation of targeted treatments for aging and age-related diseases, ultimately enhancing the health and well-being of older adults.
