Understanding transplant rejection

25 July 2022

Dr Rhys Evans has been keeping a close eye on the latest scientific research looking at how our immune systems work. He has spotted a recent finding that could help avoid kidney transplants being rejected. We are delighted to fund Rhys’ work

The problem

Our immune system is made up of a group of different cells that search our bodies looking for things that aren’t “us”. The vast majority of the time this is hugely beneficial. Working as a team, the cells of our immune system find germs, bacteria and cells infected with viruses and then destroy them. However, this mechanism works against us when we transplant organs such as the kidneys from one person into another.

There are various criteria that doctors use to match kidneys between donors and recipients. However, no matter how good the match, transplant recipients will still have to take drugs to weaken their immune system to stop it attacking the new kidney. This leaves transplant recipients more susceptible to infections and many of these medications have side effects that are undesirable for patients.

Researchers have been trying for some time to find ways to make the immune system of transplant recipients less likely to attack the donor organ without the need for lots of medications. Recently it has been discovered that having more salt in your diet can make your immune system more aggressive, with some evidence to suggest that high salt may lead to worse outcomes for transplanted kidneys.

Do you want more salt? Na…:

Is the opposite true? Does a decrease in salt in the diet of transplant recipients help to protect the new kidney from an overkeen immune system?

Dr Rhys Evans from University College London wants to find out. He is going to take transplant recipients’ own white blood cells and test them in the lab. Rhys plans to expose these white blood cells to increasing concentrations of salt to see if this increases behaviour in the cells that is associated with transplant rejection. He will then use this work to inform work with transplant recipients themselves. Rhys will place them on a low salt diet along with a tablet that should decrease the amount of salt in their blood. He will then check the white blood cells from his participants to see if the white blood cells have changed in a way that should reduce the risk of rejection.

What this means for kidney patients

Dr Rhys Evans

This project will increase our understanding of how transplant rejection works. By further reducing the risk of rejection in transplant recipients we can increase the functional lifespan of a transplanted kidney. Depending on how effective a low salt diet is, it could even mean a reduction in the amount of medicine transplant recipients have to take to protect their new kidney.

Rhys said, “We are so grateful to Kidney Research UK for their support of our work investigating how salt affects the immune system of kidney transplant recipients. For the last four years we have been investigating the effect of salt on cells in the immune system that provide protection against infection. We demonstrated that patients who are severely salt deplete have a weakened immune system which we think may actually be beneficial for patients who have had a kidney transplant.

"We hope to learn if changing salt concentrations affects the development of rejection. We hope that in the future we may be able to initiate a lifestyle intervention in patients that will allow us to reduce the amount of medications they have to use. This grant is the first step on this path and we are really excited to take this research forward.”