Treatment to improve immune function in older adults

It has long been established that beyond a certain age , typically above 60 years, one’s immune response starts to weaken. This means that individuals become more susceptible to infection and vulnerable to cancers as a result of reduced vaccine effectiveness and decreasing immune cell population - a process known as Immunosenescence. This raises a critical question , is it possible to reverse or retard these changes ?

Scientists have been working closely to rejuvenate immune systems and reduce the associated effects . The latest trial by Dr MJ Friedrich was successful in replenishing immune cells with no adverse side effects , marking a significant scientific achievement .

This article discusses his method , the processes involved and the achieved outcomes along with the potential they posses to reshape immune-based healthcare for older adults.

Background

Ageing has a profound effect on the immune system. In humans and most mammals the thymus gland is responsible for the production of T-cells - a type of white blood cell essential to our body’s immune system . With age the thymus shrinks considerably , leading to reduced or dysfunctional T-cell output.

T- cell output is dependant on 3 factors , DLL1 / FLT3-L/IL-7 , commonly referred to as DFI. DFI gives rise to Common Lymphoid Progenitors (CLP’s) which give rise to a variety of immune cells including T-cells. These factors are abundant in the thymus of healthy individuals but diminish with age, contributing to immune decline.

This specific study also worked in close association with 2 important components , mRNA and LNP’s : Messenger Ribo Nucleic Acid (mRNA) is a common biological molecule in our body. It can be produced and manipulated externally , it contains instructions needed to produce specific proteins. Lipid Nano Particles (LNP’s) are carriers that can deliver drugs and genetic material into the body's cells , they are commonly used in vaccines. This mechanism ensures that the constituent materials reach the target site without degradation.

What process did the scientists carry out ?

Scientists have administered DFI (factors that regulate T-cell production ) into the liver of older mice populations. Rather than injecting the factors directly into the body of the mice they have encoded them into mRNA . To ensure that the mRNA is not disturbed it was wrapped in Lipid Nanoparticles (LNP’s) engineered to travel to the liver upon administration with minimal transfer to other tissues. After reaching the liver mRNA codes for proteins that will develop DFI , eventually giving rise to functional T-cells.

Why was liver the chosen organ ?

The unique anatomy and blood flow of the liver makes it an ideal organ for priming and maintaining T-cell production . Additionally, the liver retains its ability to produce proteins even at advanced ages allowing for the delivered mRNA to function efficiently. Further, this delivery of mRNA does not affect the abundance or composition of liver cells ensuring that there is no disruption in regular liver function.

What results did the scientists obtain ?

After 4 weeks of administering DFI in aged mice it was observed that T cell output was amplified. Additionally, to test the functionality of T-cells , scientists administered Ovalbumin - a substance that triggers T-cells to respond. It was found that older mice treated with DFI produced more active T-cells, responded more strongly to the vaccine, and behaved similarly to much younger mice.

These results conclude that ageing effects of immunity were mitigated. Not only did the count of immune cells in the body increase , but their efficiency was also restored. There was no changes in body weight, liver function or blood glucose levels of the mice - modelling no adverse side effects.

Why are these results better than before ? Are there any drawbacks ?

Previously , the approaches taken by scientists proved to be clinically challenging due to rapid clearing of T-cells upon production , frequent administration of high-doses of DFI , all of which often resulted in significant toxicity build-up within the body. This mRNA based approach is also confined to a dosing window and reverses after treatment is stopped . This means that there are no permanent changes in the body, necessitating repeated administration in order to sustain therapeutic effects. The long-term effects of such exposure need to be analysed to ensure the safety of said procedure. Although this could be a potential drawback , compared to previous trials this approach taken by scientists was scalable and has yielded positive results as compared to previous trials.

What potential does this method have to change immune treatment?

This research is now moving toward human trials, where it has the potential to strengthen immune function and improve immune responses in older adults. While it may take time for this treatment to be a clinically widespread practice, the findings offer strong promise. If successfully translated to humans, this treatment has the potential to improve health outcomes and address a wide range of human diseases and conditions - including but not limited to improved immune outcomes and vaccine responses - not only in aged adults, but also in those individuals with compromised immune systems.

Overall, This study demonstrates how organs can be temporarily repurposed to restore declining immune function, challenging the long-held belief that age-related immune deterioration is irreversible. By showing that the ageing immune system can indeed be rejuvenated through the right triggers, this research significantly contributes to the popular science of healthy ageing.

Friedrich, Mirco J., et al. “Transient Hepatic Reconstitution of Trophic Factors Enhances Aged Immunity.” Nature, 17 Dec. 2025,https://doi.org/10.1038/s41586-025-09873-4.

Fatema Raja | Writer | The STEM Review