Differences Seen in Composition of Gut Microbiome in MG Patients

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Differences in gut bacteria composition in people with myasthenia gravis (MG) may be a promising avenue to explore in developing new therapies, a study highlights.

Findings suggest that these bacteria might contribute to disease onset and progression, its researchers wrote.

The study, “Gut bacterial microbiota in patients with myasthenia gravis: results from the MYBIOM study,” was published in the journal Therapeutic Advances in Neurological Disorders.

The human digestive system is home to billions of bacteria and other microorganisms, collectively known as the gut microbiome. These tiny microbes play a crucial role in health that is only starting to be understood.

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Past research has suggested that the gut microbiome is dysregulated in people with autoimmune diseases like MG, although the role that these bacteria play in MG is still unclear. Also unclear is whether the gut microbiome of MG patients tends to differ from that found in people with other diseases.

“Therefore, we set up an observational study with the primary [goal] of determining whether the gut microbiota is altered in patients with MG compared with patients with non-inflammatory neurological disorders (NINDs) and patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), another autoimmune neurological disease,” the research team in Germany wrote.

These specific groups were selected to “allow comparison of gut microbiota among patients with inflammatory disorders of the peripheral nervous system who have different underlying immunological drivers (MG versus CIDP) and to compare patients with inflammatory versus non-inflammatory disorders (MG versus NINDs),” the researchers added. Of note, the peripheral nervous system comprises the network of nerves found outside the central nervous system, that of the brain and the spinal cord.

The team assessed gut bacteria composition in 41 people with MG, six with CIDP, and 18 with other NINDs (such as stroke, headache, or Parkinson’s disease). For comparison, investigators also assessed gut bacteria composition in 12 healthy volunteers.

Microbiome composition was assessed by analyzing bacteria in fecal samples using 16S rRNA gene sequencing, a technique that basically involves looking at the sequence of a piece of the bacterial genome to identify the types of bacteria present in a sample. The team then used statistical analyses to compare gut bacteria composition across the different groups.

No significant differences in bacterial diversity were found among MG, CIPD, and NINDs patients. However, some analyses showed the gut microbiome of MG patients was significantly less diverse compared with healthy controls.

These findings support the idea that “gut microbiota should be considered as a contributor to disease onset and progression in patients with MG,” according to researchers, who also noted that targeting abnormal gut bacteria may be therapeutically useful in MG or other diseases.

Further analyses revealed some specific differences among the patient groups. For example, MG patients generally had higher numbers of bacteria belonging to a group called Faecalibacterium. These bacteria, specifically, were significantly more abundant in MG patients compared with those with NINDs.

“An antibiotic treatment of Faecalibacterium could be an interesting approach in future randomised controlled interventional trials of MG,” the researchers wrote.

Noted study limitations include its small size, as well as the fact that most participants were actively taking disease-relevant treatments, which might have affected the results.

“Potential therapeutic approaches modulating the gut microbiota need to be explored in future studies to better understand the involvement of the gut microbiota in the development of this debilitating acquired autoimmune disease,” the team concluded.