Across the long arc of a human life, the body quietly accumulates wear: stiffened hearts, scarred livers, tired kidneys. Researchers at Monash University have now identified a protein made by immune cells, Granzyme K, that appears to push these organs toward damage as the years advance, and that, unlike the immune system itself, can be separated from the aging process. The finding, reported in the journal Immunity, comes from mice and remains a glimpse of a possible door rather than a path already walked, but it offers a hopeful new direction for keeping later life healthier.
Blocking Granzyme K Protein May Shield Heart, Liver and Kidneys From Age-Related Damage
Their organs held up better, even as their immune systems aged normally.
Mark
Start with the basic finding. What did the Monash team actually see?
Mimi
Older mice without Granzyme K had better heart function and less fibrosis, which is scarring that hampers an organ. Their liver and kidneys also showed less age-related damage.
Mark
And the immune system part?
Mimi
That's the surprising bit. Their immune systems still aged normally. So organ ageing and immune ageing may be separable, which challenges a long-held assumption.
Luke
Before we get excited, these are mice. The source says plainly the work is preclinical.
Mimi
Right, and Professor La Gruta says the same about humans. Further research is needed to know if the benefits carry over.
Mark
The human data, though, showed something.
Luke
It showed elevated Granzyme K in patients with lupus nephritis and heart failure, among other conditions. That's an association. It doesn't show the protein causes damage in people, and La Gruta says its role in age-related damage still needs work.
Mark
Is there a design problem with the mouse study?
Mimi
Yes. The mice never had the protein at any point in their lives. Blocking it in an older animal might not work the same way.
Luke
And that's unknown for now. The team is working on ways to block it selectively to find out, but no results are reported here.
O Pulso
- Mice that lacked Granzyme K kept stronger hearts and showed less scarring in the heart, liver and kidneys than their ageing counterparts.
- The long-held belief that organ decline and immune decline travel together is unsettled, as the immune systems of these mice aged normally anyway.
- Elevated Granzyme K turns up in people with lupus nephritis and heart failure, raising the question of whether the same mechanism operates in human bodies.
- The protein has not yet been tested as a target: the mice never had it removed partway through life, so the real question of later intervention is still open.
- Researchers are now building ways to selectively block Granzyme K in older animals, and the results of those experiments will decide whether this becomes a treatment path.
Across the long arc of a human life, the body quietly accumulates wear: stiffened hearts, scarred livers, tired kidneys. Researchers at Monash University have now identified a protein made by immune cells, Granzyme K, that appears to push these organs toward damage as the years advance, and that, unlike the immune system itself, can be separated from the aging process. The finding, reported in the journal Immunity, comes from mice and remains a glimpse of a possible door rather than a path already walked, but it offers a hopeful new direction for keeping later life healthier.
Researchers at Monash University have traced a protein called Granzyme K to the slow damage that builds in the heart, liver and kidneys as people grow older. The protein is produced by immune cells, and its levels climb with age in both mice and humans. Until now, no one had shown whether it actually drives the wear on organs or merely travels alongside it.
To find out, the team compared older mice that lacked the protein with older mice that had it. The mice without Granzyme K had noticeably better heart function, less fibrosis, the scarring that stiffens an organ, and less age-related harm in the liver and kidneys. Professor Nicole La Gruta, the senior researcher, noted a striking detail: these mice still aged in their immune systems as normal. That suggests organ ageing and immune ageing may not be as tightly bound together as scientists assumed, a possibility she called an exciting avenue for keeping organs healthy longer.
The team also found elevated Granzyme K in human patients with inflammatory and fibrotic conditions, including lupus nephritis and heart failure. La Gruta was clear that this does not yet prove the protein plays the same role in ordinary human ageing.
The study carries an important limitation. The mice lived their whole lives without the protein, which says nothing about whether removing it later, as a real patient would require, could help. The researchers are now developing ways to selectively block Granzyme K in older animals. Those experiments will be the next results to watch, and they will determine whether this protein becomes a meaningful target for healthier ageing.
Researchers at Monash University have pinpointed a protein that appears to push the heart, liver and kidneys toward damage as the body ages. The protein is Granzyme K, and the work, published in the journal Immunity, points to a possible new target for treatments aimed at keeping people healthier into later life.
Granzyme K is made by immune cells. Its levels are known to rise substantially with age in both mice and humans. What nobody had pinned down was whether the protein actually contributes to the wear on organs or simply accompanies it.
To test that, the team worked in mouse models. They compared older mice that lacked Granzyme K with older mice that had it. The mice without the protein had markedly better heart function and less fibrosis, the scarring that can impair how well an organ works. They also showed less age-related damage in the liver and kidneys.
One detail stood out to the senior researcher, Professor Nicole La Gruta of the Monash Biomedicine Discovery Institute. The immune systems of the mice without Granzyme K still aged normally, even as their organs held up better. She said this challenges the long-held assumption that organ ageing and immune ageing are inextricably linked, and she called it an exciting avenue for developing treatments that help people keep healthier organs for longer.
The researchers also looked at human datasets. They found elevated Granzyme K in patients with several inflammatory and fibrotic diseases, including lupus nephritis and heart failure. La Gruta was careful to say that more research is needed to establish the protein's role in age-related organ damage in people.
She framed the stakes around ageing itself, which she described as one of the biggest risk factors for chronic conditions, including cardiovascular and kidney disease. Damage that builds up in organs over the years can leave people more vulnerable to serious illness later. If that damage can be limited, she said, people may keep healthier organs for longer and potentially lower their risk of age-related disease.
A significant caveat sits inside the design. The mice in the study lived their entire lives without Granzyme K. That does not tell researchers whether removing the protein later in life would help, which is the situation any real patient would be in. The team is now investigating ways to selectively block Granzyme K to test whether targeting it in later life offers similar protection.
Whether the same benefits could be achieved in humans is a separate question that remains open. La Gruta said there is still a lot of work to do, but that finding a protein contributing to damage across multiple organs gives research into healthier ageing a promising new direction. The next results to watch are from the selective-blocking experiments in older animals.
Citações Notáveis
Because these mice have lived their entire lives without Granzyme K, we now need to understand whether blocking the protein later in life could achieve similar benefits.— Professor Nicole La Gruta, Monash Biomedicine Discovery Institute
Mice without this protein showed reduced signs of organ ageing, even though their immune systems continued to age normally.— Professor Nicole La Gruta, Monash Biomedicine Discovery Institute
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