Trends in Autoimmune Diseases
In our recent blog “The Prevalence of MS,” we explored the increased prevalence of multiple sclerosis worldwide and in the United States. MS is not the only autoimmune disease that has witnessed increases. The National Institutes of Health reported in April 2020 that autoimmunity appears to be rising in the United States. A 2021 study from London’s Francis Crick Institute estimates that the cases of autoimmune diseases are rising by 3% to 9% a year.
Autoimmune diseases are diseases of the immune system. Diseases such as MS, Type 1 Diabetes, and Crohn’s Disease result when the immune system effectively malfunctions and can no longer tell the difference between healthy cells and invading microorganisms. As a result, the immune system gets wires crossed and attacks healthy tissue, instead of protecting it.
Gut health is an important component of immune function. Approximately 80% of your immune cells are in the gastrointestinal tract. Let’s look behind the curtain so we can understand gut health and its link to autoimmune diseases, and to MS specifically.
Gut Microbiome
Your gut microbiome is composed of the trillions of microbes that live in your digestive system. In fact, there are more of these microbes than cells in your body. More than 1,300 different types of bacteria live in everyone’s gut. And this is perfectly normal.
Microbes are a collection of bacteria, fungi, and other organisms that perform needed roles in the body. They aid in digestion and influence our overall health and risk of disease. Microbes also seem to influence the immune system.
Every person has a different collection of gut biomes and are affected by numerous factors. These factors include whether you were delivered by C-section or vaginal delivery, whether you were breastfed, your family genetic history, your age, your diet, where you live, your stress level, the medications (in particular, antibiotics) you take, and, of course, your diet.
Autoimmune Disease: Why Gut Health is Important
With the increase in autoimmune diseases, along with allergies, the hygiene hypothesis has emerged to explain the negative trend. In fact, it may be that our greater efforts to clean our environments and reduce bacterial exposure may be working against us. The hygiene hypothesis proposes that childhood exposure to germs and certain infections helps the immune system develop. As a result of the exposure, the body learns to distinguish between harmless and harmful substances.
In contrast, decreased exposure and fewer infections is associated with the rise of immune-related disorders and allergic diseases. One hypothesis suggests that reduced exposure to pathogens triggers significant changes in gut microbiomes.
Role of Bacteria in Your Digestive Tract
To understand how these changes in gut microbiomes can affect autoimmune diseases, we need to explore the role that bacteria play in one’s digestive system.
Bacteria in your digestive tract help break down food into beneficial nutrients which are absorbed in your intestines. The digestive tract’s bacteria are prevented from entering the rest of our body by a cell wall which acts as a barrier. Known as the intestinal barrier, this semipermeable structure allows some substances to pass through it, but not others. The barrier plays an essential role in controlling what gets absorbed in the bloodstream. A healthy gut enables absorption of essential nutrients, while restricting pathogenic molecules and bacteria.
Leaky Gut
Changes in the gut microbiome causes disruption to the intestinal barrier, allowing for “leaking” into the bloodstream. In a leaky gut, pathogens, toxins, partially digested food, and bad bacteria can leak through the gaps between the cells and enter the body. When these substances leak through the barrier, immune cells identify them as a potential threat and initiate an immune response to protect the body.
This immune response creates inflammation. In some cases, inflammation becomes widespread throughout the body and contributes to many health issues, including the development of autoimmune disease.
Gut Microbiomes and MS
Now, let’s take a closer look at microbiomes in MS patients. Recent research has focused on how the microbiomes of MS patients are different from people without MS. For researchers, that is a question that reflects the adage: which came first, the chicken or the egg? Put differently, do differences in the microbiome increase the chance of MS flares … or do the MS flares alter the gut microbiome? It could be both.
Some studies have demonstrated that some bacteria in the gut create more inflammation. This “gut dysbiosis” has been shown in MS patients. In more than one mouse-study, MS-like symptoms improved by altering the gut microbiome.
The bacteria Prevotella histicola is present in lower quantities in patients living with MS. (Source). Interestingly, an effective treatment for MS, Copaxone (glatiramer acetate), increases these bacteria in patients treated with the drug. Another study gave Prevotella histicola to mice. The result showed an improvement like that seen in humans treated with Copaxone. This has not been tested in humans. All said, ongoing research in the field is likely to reveal valuable insights in the future for MS patients. (To read more about the scientific research, go here).
Suggestions to protect your gut microbiome include: eating more fiber, reducing alcohol intake, managing stress, limiting antibiotic use, and considering probiotic supplements.