Vitamin D and Gut Bacteria: More Clues and Questions

I just got back from ACTRIMS (Americas Committee for the Treatment and Research in MS), where more than 700 MS doctors and researchers shared their results, especially their work aligned with this year’s theme: Environmental Factors, Genetics, and Epigenetics in MS Susceptibility and Clinical Course. This was my first time at ACTRIMS and I found the theme and the talks really compelling.
One thing that struck me is the evolving story about how specific things we all encounter in our lives interact with the “cards” (genes) we were dealt at birth. Our genes predispose us to be susceptible to various medical conditions, but that doesn’t mean we will get those conditions. In the case of MS, now there are 200 genetic variants identified that increase a person’s likelihood of getting the disease. I’m struck by how many “moving parts” seem to be involved in whether or not a person gets MS and what their MS experience and course will be.
For example, not everyone who has MS has necessarily been exposed to the risk factors identified so far – like low vitamin D, adolescent obesity or smoking – and just because a person has been exposed to these factors doesn’t mean they will develop MS. Add to that various other things that might influence the disease, like a person’s diet or other lifestyle factors, and even the bacteria living in our intestines.
Dr. Ellen Mowry (Johns Hopkins University) described the growing evidence that low levels of vitamin D in the blood increases risk of MS (Abstract S2.1). An interesting wrinkle, she said, is that we don’t know if the blood marker we measure – 25-hydroxyD – is the right one, it’s just the easiest to test. Nevertheless, for the patients she cares for, she likes to make sure their blood levels are within a normal range of between 40-60 ng/mL, and has them take supplements of about 2,000 to 4,000 International Units (I.U.) of vitamin D per day – or sometimes more – to get their blood levels up, but not without testing how much they have beforehand. One thing I didn’t know is that vitamin D supplements start out stronger than it says on the label, and get weaker the closer they get to their expiration date. Good to know!
Dr. Mowry learned a lot about vitamin D when designing and leading a clinical trial to see whether vitamin D supplements, added to glatiramer acetate therapy (e.g. Copaxone), can reduce disease activity. I’m really eager to learn the outcomes when it’s completed, and really proud that the Society is funding this work.  
Another “moving part” is the emerging story of how the bacteria in our guts (microbiome) might talk to the brain, immune system and other organs. Dr. Irah King (McGill University) explained how many different factors, like our diets, genes, medications, stress, hygiene, infections and age, can influence the content of our gut bacteria (Abstract S5.1).  Dr. Sergio Baranzini (University of California, San Francisco) explained that new technology is enabling a whole new look at the millions of bugs in our guts and how they impact immune responses. In one study, his team transplanted gut bacteria from people with MS into germ-free mice. The mice then had much worse EAE (an MS-like disease) than mice without the transplants.
Dr. Baranzini and others are building national and global collaborations like the MS Microbiome Consortium to tease out differences in people with MS, and to see how we might alter the microbiome in hopes of turning off disease activity.  
What about probiotics? You can buy them in the vitamin aisle, but which probiotics might help? Dr. Howard Weiner of Harvard presented his and others’ work in this exciting field, but it’s still early days in this area. As he put it, “…we need a lot of science before we know what we’re doing in terms of probiotic treatment.”
Researchers are learning a lot about how the environment and genes, and even the foods we eat, play a role in MS susceptibly and clinical course. Conferences like ACTRIMS allow researchers and clinicians to compare notes and try to put it all together to advance our understanding of MS.
Check back tomorrow for a blog by my colleague Douglas Landsman, who has other observations around the ACTRIMS theme.
News: ACTRIMS Meeting Focuses on Factors Influencing MS Susceptibility and Disease Course
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Elisabeth Mari, PhD

Dr. Elisabeth Mari is Director of Biomedical Research at the National MS Society. Her responsibilities include supporting the Society’s biomedical research grant portfolio and the International Progressive MS Alliance. An immunologist by training, she attended the University of Delaware and then earned her PhD at Imperial College London. Dr. Mari did a postdoctoral research fellowship at Thomas Jefferson University in Philadelphia. She joined the Society in 2016 and brings over 13 years of experience in biomedical research.