The gut–brain axis in multiple sclerosis is a fascinating area of research. It explores how closely the immune system, the gut microbiome and the central nervous system are connected.
In this interview, Prof. Dr. Anne-Katrin Pröbstel explains why certain B cells may play a role not only in the blood and brain, but also in the gut. The conversation focuses on IgA-producing B cells, inflammatory processes in the central nervous system and the question of how basic research may one day contribute to better treatment options for people living with MS.
A particularly interesting aspect is the gut microbiome — the community of bacteria and other microorganisms living in the intestine. Prof. Pröbstel explains why diet, vitamin D, smoking and the interaction between the gut and the immune system are important research topics.
At the same time, she emphasizes an important point: much of this work is still basic research. It does not yet translate directly into specific treatment recommendations. However, the findings open new perspectives for understanding MS and for developing more targeted therapies in the future.
This article is an English adaptation of a German MS-Perspektive podcast episode originally published in January 2021. At the time of the interview, Anne-Katrin Pröbstel was based at the University of Basel. Since February 2025, Prof. Dr. Anne-Katrin Pröbstel has been Director of the Department of Neuroimmunology at University Hospital Bonn, Germany, and also serves as Managing Director of the Center of Neurology together with Prof. Ulrich Herrlinger.
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Introduction and personal motivation
Could you briefly introduce yourself?
Dr. Anne-Katrin Pröbstel: My name is Anne-Katrin Pröbstel. I am a neurologist and researcher. At the time of the interview, I was working at the Department of Biomedicine at the University of Basel, where I led a research group focusing on multiple sclerosis.
My main scientific interest is the role of the immune system in MS. We are particularly interested in B cells, a specific type of immune cell that can play an important role in multiple sclerosis. We also study how these immune cells interact with the gut microbiome, meaning the microorganisms that live in the intestine.
Clinically, my work focuses on people with MS and other autoimmune diseases of the brain and spinal cord.
What were the key steps in your career?
Dr. Anne-Katrin Pröbstel: I studied medicine at Ludwig Maximilian University in Munich. During my studies, I also spent time in Paris and Boston. In Boston, I worked on my doctoral thesis at the Max Planck Institute of Neurobiology, where my interest in neuroscience really began.
After that, I started working on multiple sclerosis. I was particularly interested in understanding why the immune system attacks the brain, often in young people. I then began my clinical training in neurology with a focus on neuroimmunology.
Later, I moved to the University of Basel, which is home to one of the world’s major centers for multiple sclerosis research and care. I then spent several years in the United States at the University of California, San Francisco, where I continued my research as a postdoctoral fellow.
It was there that I began to focus more strongly on the relationship between the immune system and the gut microbiome. I later returned to Basel to lead my own research group.
Do you have a personal motivation for your work?
Dr. Anne-Katrin Pröbstel: I have always been fascinated by the question of why the immune system attacks the nervous system. This question already played a central role during my doctoral work.
That is why I chose neurology and neuroimmunology. Neuroimmunology studies how the immune system and nervous system interact, influence each other and sometimes contribute to disease.
In recent years, there has been enormous progress in multiple sclerosis. We now have many more treatment options than before. Many therapies can reduce or prevent relapses and slow down inflammatory disease activity. However, we still cannot truly reverse MS.
That is why I want to contribute scientifically to a better understanding of the disease. My hope is that one day we will be able to treat MS even more precisely — and perhaps eventually cure it.
The gut–brain axis in multiple sclerosis
What exactly does “gut–brain axis” mean?
Dr. Anne-Katrin Pröbstel: The term gut–brain axis is used very often today. In general, it describes the connection between the gut and the brain.
This is not just about a “gut feeling.” Scientifically, we are looking at how gut bacteria, the immune system and the nervous system communicate with each other. Over the past decades, research has shown that gut bacteria can influence a wide range of diseases.
In multiple sclerosis, this is especially interesting because autoimmune diseases have become more common over recent decades. During the same period, diet, lifestyle and environmental factors have changed significantly. These include factors such as fast food, lower fiber intake, smoking and changes in vitamin D levels.
Gut bacteria can be seen as a kind of internal mirror of our environment. That is why they may be an important factor in understanding how diet and environmental influences affect autoimmunity.
How many types of B cells are there, and how do they differ?
Dr. Anne-Katrin Pröbstel: B cells are a subgroup of immune cells. They develop from cells in the bone marrow and go through different stages before becoming mature B cells.
Some B cells later become plasma cells. Plasma cells produce antibodies. Antibodies are proteins that can recognize specific structures, for example on viruses or bacteria.
This immune response is essential because it helps protect us from infections. However, it can also become problematic in autoimmune diseases if the immune system starts attacking the body’s own structures.
In MS, we know today that some B cells can promote inflammation. This is why there are medications that specifically remove certain B cells. These therapies can significantly suppress inflammatory activity in MS.
What is special about IgA-producing B cells?
Dr. Anne-Katrin Pröbstel: IgA-producing B cells make a specific type of antibody called immunoglobulin A, or IgA. IgA is especially common at mucosal surfaces, such as in the gut.
In our research, we observed that some B cells may migrate from the gut to the brain during an MS relapse. Interestingly, these cells did not appear to be harmful. Instead, they may have an anti-inflammatory or regulatory effect.
This was an important finding for us. Many B-cell therapies remove B cells quite broadly. But we now know that not all B cells are “bad.” Some may even help regulate inflammation.
The key question is therefore: Which B cells promote disease, and which B cells may be protective? That is exactly what we want to understand better.
B cells, IgA and international research
Many international universities were involved in your study. What does such collaboration look like in practice?
Dr. Anne-Katrin Pröbstel: Collaborations are essential in modern science. In our case, much of the work began with a discovery in Basel. We identified specific B cells in connection with the gut.
The next step was to find research partners who could help confirm these findings or investigate them using different methods. In San Francisco, for example, we were able to examine whether these cells could also be found in brain tissue from people with MS.
Other partners had specialized technical expertise, such as methods to analyze gut bacteria in greater detail. This creates a network in which different research groups contribute their specific strengths.
That is how science works today: you make a discovery, test it with different methods, and try to rule out possible sources of error.
What new approaches could come from your study results?
Dr. Anne-Katrin Pröbstel: For me, there are two important insights.
The first is that not all B cells are harmful in MS. Some B cells may have regulatory or even protective functions. Future therapies may therefore need to distinguish more precisely between B cells that should be removed and B cells that should potentially be preserved.
The second insight concerns the gut microbiome. If certain gut bacteria can influence immune cells, this might one day lead to new therapeutic strategies. Perhaps specific bacteria could be used to promote helpful immune cells.
However, this is still a vision for the future. At the moment, the priority is to understand the underlying mechanisms more clearly.
What are the next steps toward helping people with MS?
Dr. Anne-Katrin Pröbstel: First, we need to characterize the different immune cells in much greater detail. We want to understand which cells are harmful and which may be protective.
We also want to investigate which bacteria are involved. To do this, researchers compare the gut microbiome of healthy individuals with that of people living with MS.
Another important question is whether beneficial bacteria could be supported or supplemented in a targeted way. But this would need to be tested carefully in clinical studies. Only then can we know whether such an approach is safe and truly helpful for patients.
New therapeutic approaches and diet
Can any advice for people with MS already be derived from this research?
Dr. Anne-Katrin Pröbstel: I am cautious here because many of our findings come from basic research. What can be said with confidence, however, is that a healthy, balanced diet makes sense.
This includes reducing fast food and focusing on natural, fresh, local and seasonal foods where possible. Fiber is also important because it can have a positive influence on the gut microbiome.
There is also a considerable amount of data suggesting that vitamin D is relevant in the context of MS. People with MS should have their vitamin D levels checked by a healthcare professional and discuss any supplementation with their doctor.
Smoking is another important factor. There is clear evidence that smoking is unfavorable in MS. Quitting smoking is therefore an important step for overall health and MS management.
Are there specific dietary recommendations from the research?
Dr. Anne-Katrin Pröbstel: At this point, we cannot yet recommend specific bacteria or supplements. More studies are needed.
There are indications that short-chain fatty acids may be interesting. These are produced when gut bacteria process dietary fiber, and they can influence the immune system. Early studies exist, but there are not yet any final recommendations.
Fecal microbiota transplantation is also being studied. This involves transferring gut microbiome material from healthy individuals to patients. However, this is still a highly experimental approach and is not currently a recommendation for MS.
For now, the most reliable advice remains: eat a balanced diet, limit fast food, do not smoke, keep an eye on vitamin D and always discuss treatment decisions with a qualified healthcare professional.
Quick-fire Q&A
What is the best advice you have ever received?
Dr. Anne-Katrin Pröbstel: The best advice was to make my own decisions. It is good to listen to others and seek advice, but in the end, you have to find your own path.
This also applies, in a broader sense, to people living with MS. There is a lot of information and many recommendations, but each person has to find out together with their healthcare team what fits their individual situation.
A treatment plan or diet that someone cannot realistically maintain is unlikely to help in the long run. Decisions have to fit the person’s life.
What is your current life motto?
Dr. Anne-Katrin Pröbstel: In research, I would say that science is exciting, but it also involves a lot of work and frustration.
You have to overcome obstacles and keep going. That applies to research, but also to difficult situations in life.
My motto would be: try to make the best of the situation and keep moving forward step by step. Even when things are difficult, progress is possible. Do not give up — keep looking ahead.
Which person would you like to have a fireside chat with, and what would you talk about?
Dr. Anne-Katrin Pröbstel: I would very much like to speak with Marie Curie. She was an extraordinary scientist.
I would be interested in how she found her way in science. She worked at a time when women were far less visible in research. At the same time, she was both a scientist and a mother. I would like to ask her how she experienced and managed these challenges.
Please complete the sentence: “For me, multiple sclerosis is …”
Dr. Anne-Katrin Pröbstel: For me, multiple sclerosis is a diverse and multifaceted disease. It affects every person differently.
That makes it challenging for people living with MS, but also for physicians and researchers. We still do not fully understand why the disease course can vary so much from person to person. That is exactly why further research is so important.
Which websites do you recommend for reliable MS information?
Dr. Anne-Katrin Pröbstel: I recommend the websites of national MS societies. In Germany, this would be the German Multiple Sclerosis Society. In Switzerland, the Swiss Multiple Sclerosis Society. In the United States, the National MS Society.
These organizations provide well-prepared and scientifically reviewed information. Especially for topics such as infections, vaccinations, MS therapies or everyday life with MS, reliable sources are very important.
Is there a book or audiobook you would recommend?
Dr. Anne-Katrin Pröbstel: I read a book about motivation called Drive. It explores what motivates people.
I found the idea particularly interesting that people are often most motivated when they can act autonomously. This applies to research, but also to everyday life: people need meaning, responsibility and the opportunity to make their own decisions.
Final thoughts
Is there anything you would like listeners to take away?
Dr. Anne-Katrin Pröbstel: The audience is probably very diverse. Some listeners may live with MS themselves, others may be relatives, caregivers or professionals interested in the topic.
What I would like to say is this: I have great respect for people living with MS and for the way they deal with this disease. At the same time, I believe that scientific progress can offer hope.
Many physicians and researchers are working to better understand MS and to develop improved therapies. Progress is not always fast, but it is moving forward step by step.
I would like to encourage people affected by MS to stay hopeful.
How can people follow your research?
Dr. Anne-Katrin Pröbstel: Information about Prof. Pröbstel’s research can be found through her laboratory and institutional profiles. Since the original German interview was recorded, her academic and clinical role has changed. She is now Director of the Department of Neuroimmunology at University Hospital Bonn and continues to work in the field of neuroimmunology, B cells, antibodies and the gut microbiome in inflammatory diseases of the nervous system.
For people living with MS, national MS societies remain a valuable source of accessible, evidence-based information. They help translate new scientific findings into understandable updates while clearly distinguishing between established recommendations and early-stage research.
Contact details and information about Dr Pröbstel
www.proebstellab.com
Departement Biomedizin
Hebelstrasse 20
4031 Basel
Schweiz
Email: anne-katrin.proebstel[at]unibas.ch
Since February 2025, Prof. Anne-Katrin Pröbstel has been the new Director of the Department of Neuroimmunology at the University Hospital Bonn (UKB).
See you soon and try to make the best out of your life,
Nele
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