Probiotics show potential to prevent and delay the development of multiple sclerosis (MS) by changing immune and inflammatory responses, according to a review study.
Data further support the link between the gut’s microbial community (microbiota) and the central nervous system (brain and spinal cord), and neurodegenerative diseases.
However, large-scale clinical studies are required to confirm these potential benefits for MS patients.
The study, “Immunomodulatory and anti-inflammatory effects of probiotics in multiple sclerosis: a systematic review,” was published in the Journal of Neuroinflammation.
The gastrointestinal tract is colonized by gut microbiota, a vast community of friendly bacteria, fungi, and viruses that play an important role in gut health. These microorganisms help to maintain a balanced gut function, protect against disease-causing organisms, and influence the host’s immune system and inflammatory responses.
An unbalanced gut microbiota has been associated with triggering or worsening several diseases, and a recent study highlighted that newly diagnosed MS patients show changes in the gut microbiota.
Thus, “targeting gut [microbiota] might be a crucial target for prevention, management, and control of the inflammatory and autoimmune diseases [such as MS],” the researchers wrote.
Increasing evidence supports that an unbalanced gut microbiota may be restored using probiotics — live-friendly microorganisms that improve gut health. However, few studies have explored the effects and mechanisms of action of probiotic supplements in MS.
Now, researchers in Iran, along with a colleague in The Netherlands, reviewed published preclinical and clinical studies on the immune and inflammatory effects of probiotics consumption in MS.
Data from animal studies showed that probiotics administration delayed the development of MS, as well as its severity and progression. This was associated with increased levels of anti-inflammatory molecules and cells — namely IL-10, IL-4, TGF-β, regulatory T-cells, and T helper 2 (Th2) cells — and decreased levels of pro-inflammatory molecules and cells, such as IFN-gamma, TNF-alpha, IL-6, IL-17, and Th1/Th17 cells.
“Overall, the animal studies well clarified that supplementation with probiotics could leave a major positive impact on the immune-inflammatory markers, reduce the severity and progression, and also delay the onset of the disease,” researchers wrote.
Regarding the two clinical studies, which involved a total of 108 MS patients, they showed that probiotics supplementation increased IL-10 levels, while suppressing the function of B-cells — a type of immune cell that promotes inflammation and loss of myelin in MS patients — and lowering the levels of IL-6 and high-sensitivity C-reactive protein (a marker of inflammation).
“According to the evidence of these two studies, it could be concluded that supplementation with probiotics may have beneficial effects on the immune function and especially inflammatory parameters,” the researchers wrote.
Clinical data also showed that 109 CFU/mL of probiotics was the most effective dose in MS patients, and suggested that the combination of several probiotics promoted stronger therapeutic effects than individual probiotics.
“The majority of the reviewed studies supported the beneficial effects, including alleviation, prevention, and delaying the onset of diseases via improving immune and inflammatory mechanisms,” the researchers wrote, adding that “probiotics may have efficient effects in management and treatment of MS.”
Based on the reviewed data, the team also proposed a possible mechanism of action of probiotics related to immune and inflammatory responses.
They hypothesized that probiotics improve gut microbiota composition, reduce the growth of disease-causing organisms, and block their entry into circulation. These effects may reduce the production of pro-inflammatory molecules, and suppress excessive immune system stimulation, while promoting a shift toward regulatory T-cells and the production of anti-inflammatory molecules.
Researchers noted, however, that large-scale clinical trials are required to clarify the therapeutic potential and mechanisms of action of probiotics supplementation in MS. They also emphasized that future studies should consider the influence of diet, antibiotic use, and environmental conditions in the results.