One of the most abundant amino acids found in humans is finally getting the recognition it seemingly deserves, with a new study showing how important it is for our health as we age. While no anti-aging silver bullet, it appears to be more important to aging well than we've given it credit for.
The new study out of the Yale School of Medicine supports early findings from 2023 that found a connection between taurine levels and healthy aging and longevity in animal models. But specific mechanisms facilitated by this amino acid on our cells was unclear.
This new research sheds light on why it's particularly impactful for staving off inflammaging – the chronic inflammation that becomes common as we age. While it's not solely responsible for negatively affecting our lifespan, scientific evidence supports that it does play a key role in how healthily we age.
The scientists found that taurine plays a pivotal role in how the innate immune system picks up on danger signals. Our innate immune system is what responds quickly to novel pathogens or biological threats – as opposed to our adaptive immune system, which is more like the memory center that recognizes previous bugs and mounts a slower attack. If the innate "first line of defence" immune system fails to stop the invader, the adaptive system will be activated.
The innate immune system's main attack strategy is triggering inflammation. However, as we age, our immune system's efficacy declines; so we get worse at fighting off pathogens but become more prone to widespread inflammatory conditions.
"Since the innate immune system does not have specific receptors for each and every different type of danger signal, this pattern recognition has always been a mystery," says says senior author Vishwa Deep Dixit, PhD, director of theYale Center for Research on Aging (Y-Age).
The scientists also found that besides bolstering our innate immune system, boosting taurine levels may actually also subdue inflammaging symptoms.
“Biology has lots of surprises,” says Dixit. “And the biggest surprise in this study is that taurine is controlling the innate sensing mechanism.”
Taurine caught the scientist's attention when he observed in research that people who had restricted their calorie intake for up to 12 months had higher levels of taurine compared with those who were on no diet regimen. Calorie restriction has also been tied to lower inflammation. However, it was unclear if taurine was actively involved or an independent byproduct observed by researchers.
“We wanted to test whether taurine is just a passenger or a driver of the reduction in inflammatory response caused by caloric restriction,” Dixit adds.
Unsurprisingly, Dixit felt that like many building blocks that make up our biology, taurine levels might fall as we age. But after comparing blood serum samples of 20-40-year-olds with those from older adults aged 60-99 years, the Yale team found that taurine actually increased with age – which they did not expect to see at all.
Ultimately, this led the researchers to hypothesize that our body produces more taurine as we age in an attempt to counter the inflammation being triggered by our declining innate immune system.
A key part of inflammaging involves the activation of a molecular complex known as the NLRP3 inflammasome. Essentially, aging creates the perfect environment for NLRP3 to become overly active. But what if taurine was helping keeping NLRP3 in check?
To find out, the team cultivated macrophages – the specialized immune cells that engulf and destroy targets deemed dangerous – and then exposed them to various threats including bacterial toxins.
In response to the signals, NLRP3 complexes assembled with the macrophages. In the process, the macrophages released up to 80% of their taurine. But when the team put the taurine back into the cells, it blocked downstream inflammation caused by NLRP3 activity.
"Now we know that taurine allows immune sensing and is one of the brakes within the cells that is keeping the inflammasome in check," says Dixit.
And when the scientists lowered taurine levels in the macrophages of mice, it drove up NLRP3 inflammation even in young specimens.
“What we have answered is the first step of the puzzle in what causes this very critical innate immune system sensor to be activated,” Dixit adds.
As to why our aging innate immune system is full of macrophages that leak taurine as they respond to danger signals, and where this amino acid ultimately ends up in our body, it's not clear – but the scientists are hoping to figure this out next.
Since taurine doesn't deplete with age, adding more of it to your diet – via sources like seafood, dark meats and seaweed – isn't likely going to counter inflammaging. But if scientists can work out how to get aging macrophages to hold onto their taurine, since it appears to suppress the activity of NLRP3 complexes, it has the potential to pump the brakes on an inevitable part of aging.
The study was published in the journal Cell.
Source: Yale School of Medicine
