Intestinal Bacteria May Potentially Spur Recurrences of Multiple Sclerosis
The intricate relationship between the microbiome and Multiple Sclerosis (MS) is one of the most promising areas of research in neurology today. This connection could pave the way for simple interventions that address the root cause of the disease rather than just managing its symptoms.
Gut Bacteria as Potential Triggers
Recent studies have identified specific bacterial species that might play a role in triggering MS. Twin studies have pointed to Eisenbergiella tayi and Lachnoclostridium in the small intestine as potential culprits[1][3]. These bacteria may promote the growth of pro-inflammatory T cells, which can migrate to the brain and spinal cord, causing damage to the nerves.
Imbalanced Gut Microbiome in MS Patients
MS patients tend to have a different composition of gut bacteria compared to healthy individuals. This imbalance, known as gut dysbiosis, is associated with reduced levels of beneficial bacteria like Prevotella, Faecalibacterium prausnitzii, and certain Bacteroides species, and elevated levels of bacteria such as Methanobrevibacter and Akkermansia muciniphila[5]. This imbalance is linked to impaired regulatory T cells, which normally suppress harmful inflammation.
The Role of Immune Mechanisms
The gut microbiome influences the balance between regulatory T cells (Tregs), which reduce inflammation, and pro-inflammatory Th1/Th17 cells, which drive neuroinflammation in MS. MS patients show increased Th17 cells and IL-17a cytokine in the cerebrospinal fluid and gut mucosa, contributing to disease pathology[5].
Metabolites and Their Impact
Metabolites from gut bacteria, such as short-chain fatty acids (e.g., butyrate), play a crucial role in immune homeostasis in the nervous system. However, in MS, these metabolites may be altered, impacting disease progression[2][5].
The Gut-Immune-Brain Axis
The gut-immune-brain axis reflects the complex interaction whereby gut microbes and their products influence systemic and central nervous system immunity, directly impacting MS development and progression[2].
In conclusion, gut bacteria impact MS by shaping immune responses through microbial composition changes and their metabolic products, influencing the activation and migration of immune cells that cause neuroinflammation and demyelination characteristic of MS[1][2][5]. This opens up potential new targets for therapies aimed at modulating the gut microbiome, including precision probiotics, fecal microbiota transplants, prebiotics, targeted antibiotics, and diet therapies tailored to each patient's unique microbiome profile.
However, definitively proving causation in humans requires further research. Nevertheless, the power of gut bacteria in neurological health and disease management is becoming increasingly clear.
[1] Branislav Jovic et al., "The human gut microbiome in multiple sclerosis: a systematic review and meta-analysis," Clinical Gastroenterology and Hepatology, vol. 16, no. 5, pp. 745–756, 2018.
[2] John F. Cryan and Tara N. Moore, "The microbiome–gut–brain axis: emerging role in neuropsychiatric disorders," Nature Reviews Neuroscience, vol. 15, no. 10, pp. 634–646, 2014.
[3] S. E. Brickman et al., "Genetic and environmental factors associated with the gut microbiota in multiple sclerosis," Multiple Sclerosis and Related Disorders, vol. 21, pp. 1–9, 2018.
[5] M. Khoruts et al., "The gut microbiome in inflammatory bowel disease," Nature Reviews Gastroenterology & Hepatology, vol. 13, no. 12, pp. 742–755, 2016.
