For a long time, the only treatment options we had for autoimmune conditions were medicines that suppress the immune system, such as steroid drugs. These help many people live with conditions such as rheumatoid arthritis, but can have side effects, such as raising susceptibility to infections.
The ideal autoimmunity treatment would be more specific, deactivating only certain parts of the immune system or even just the immune cells that react against the person’s body. And in the past few years, there has been some progress on this front.
One radical approach, which has been used in MS, is to target B cells. These make up the branch of the immune system that creates antibodies – proteins that recognise specific molecules, such as thoseon bacteria.
In MS, we don’t know why someone’s B cells start attacking their nerves, but it may be because they have previously been infected with a virus that has some similar molecules to those on nerve cells.
The idea with the new treatment is to "reset” the person’s immune system by killing their B cells via chemotherapy drugs and then infusing them with a stored sample of their immune system stem cells, previously extracted from their bone marrow. Once returned to their body, the stem cells start producing healthy B cells that don’t attack nerves.
Another approach is being investigated for lupus, where the immune system reacts against people’s DNA, causing a range of debilitating symptoms, such as joint pain and rashes. Here, researchers are using CAR-T cells, where some of the person’s own immune cells are genetically tweaked so they target and destroy B cells.
Originally developed as a treatment for leukaemia, which occurs when B cells start multiplying out of control, CAR-T cells have shown promise in a small trial in lupus. And the developers says this could, in principle, be used for any autoimmune condition where B cells are the main problem.
To get an even more specific treatment, where the exact immune cells that are causing the damage are suppressed, we may need to develop more sophisticated therapies still. One experimental approach is to boost activity of a special kind of immune cell called T-reg cells, whose job is to turn down the immune attack.
This approach is being investigated in early-stage trials in Crohn’s disease, where the immune system attacks an unknown target in the gut.
If we can develop ways to turn off the immune response against specific molecules, it would be a huge medical advance and it could potentially be used in non-autoimmune conditions too. These would include preventing life-threatening allergic reactions – where people react against harmless compounds in food, for instance – and would mean people who have had organ transplants no longer need to take strong immunosuppressants for life.
This goal of creating immune tolerance to specific molecules is, in some ways, the opposite of another great medical breakthrough: vaccination. Vaccines, in contrast, let us activate the immune system against specific molecules. One thing’s for sure, whichever scientists discover a way to achieve immune tolerance would surely be in the running for a Nobel prize.
