One organ might age quicker than the rest, affecting health and mortality.
Cells undergo metabolic changes that harm organs and cause death as people age. A new protein study1 reveals that these alterations aren't uniform: organs can age at different rates, and a given organ can age quicker in one person than another with the same chronological age.
The scientists analysed 11 key organs and found that blood protein levels can accelerate ageing in all of them. Nearly 20% of the 5,600 trial participants satisfied the investigators' criteria for accelerated organ ageing. The study indicated that those with hyper-aged organs are more likely to get sick and die prematurely, nature.com reported.
According to Stanford University computational biologist Hamilton Oh, a study co-author, tests for organ age-related proteins could assist researchers develop treatments for age-related health issues and drive personalised treatment regimens. Since doctors already measure some proteins, the authors' test “would be expanding their toolkit”, he says.
The paper appeared in Nature today.
Ageing numerically
DNA mutations and epigenome alterations, which gather chemical tags on DNA, are biological hallmarks of ageing2, according to previous research2. In the past decade, academics have developed algorithms to estimate a person's "biological age," which might be greater or lower than their chronological age3.
Alterations in protein production are another sign of ageing. Oh and his colleagues examined over 5,000 proteins in blood samples from 1,398 healthy persons to study organ ageing. They found 850 proteins from a single organ and developed a machine-learning algorithm to predict age based on protein levels. They tested their model with over 4,000 blood samples.
The results demonstrated that organ biological age affects illness risk. Approximately 2% of participants exhibited accelerated cardiac ageing, meaning their blood protein levels differed significantly from those of other people their age. Premature heart age raised heart failure risk by 250%, the investigators observed.
Marking time
Some studies employed epigenetic markers to show that organ ageing differs by individual4. Matt Kaeberlein, CEO of Seattle-based biotechnology business Optispan and an expert on ageing biology, believes epigenetic modifications are a mystery. He thinks proteins are “much closer to the downstream mechanisms that might be driving ageing”. He adds that protein biomarkers may help researchers find anti-aging medication targets.
According to Sara Hägg, a biological ageing epidemiologist at the Karolinska Institute in Stockholm, combining ageing markers may yield more accurate organ age assessments than protein tests alone. She commends the researchers' “impressive” data analysis, but she notes that it's unclear whether proteins cause ageing or are byproducts. She also questions whether the team's approach forecasts illness risk or just reflects disease-related protein changes.
Identifying causality is vital but time-consuming, adds Kaeberlein. He adds these protein indicators may “help people by directing them to change their lifestyle or take some supplement” with more investigation. “That’s powerful despite causality.” Several biomarker-based ageing tests are available, however Kaeberlein advises against using them. He adds, “we don't have a good understanding if these clocks are actionable or precise yet”. A non-invasive technique to forecast organ health from one sample is exciting.
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