Microbiota, diet, and the gut–brain axis in multiple sclerosis and stroke

Abstract

Intestinal microbiota can influence the phenotype and function of immune cell responses through the dissemination of bacterial antigens or metabolites. Diet is one of the major forces shaping the microbiota composition and metabolism, contributing to host homeostasis and disease susceptibility. Currently, nutrition is a complementary and alternative approach to the management of metabolic and neurological diseases and cancer. However, the knowledge of the exact mechanism of action of diet and microbiota on the gut–brain communication is only developing in recent years. Here, we reviewed the current knowledge on the effect of diet and microbiota on the gut–brain axis in patients with two different central nervous system diseases, multiple sclerosis and stroke. We have also highlighted the open questions in the field that we believe are important to address to gain a deeper understanding of the mechanisms by which diet can directly or indirectly affect the host via the microbiota. We think this will open up new approaches to the treatment, diagnosis, and monitoring of various diseases.

Gut microbiota and autoimmune neurologic disorders: a two-sample bidirectional Mendelian randomization study

“…This study used publicly available data from a GWAS summary to identify suitable IVs for MR analysis to investigate the causal relationship between gut microbiota and three autoimmune neurologic disorders: MS, MG, and GBS ( Figure 1 ). Three assumptions were strictly adhered to in order to ensure the accuracy of the results: ( Vass, 2012 ) the IVs should relate to the exposure; ( Rubin et al, 2018 ) they should not be related to any confounding factors; ( Diaz-Marugan et al, 2023 ) their effects on outcomes should only be through the exposure. Ethical approval and informed consent have been provided in the original studies.…”

“…Despite a lack of understanding of the exact causes of autoimmune neurologic disorders, genetics, environmental factors, and their interactions are believed to play a major role in their development ( Diaz-Marugan et al, 2023 ; Kapoor et al, 2023 ). Evidence has been mounting that the gut microbiota is closely related to the host’s health and is implicated in the cause of a variety of complex human diseases, including autoimmune diseases ( Wang et al, 2023 ).…”

“…For example, an investigation found considerable disparities in the concentrations of operational taxa among MG patients, specifically Firmicutes , Bacteroides , and Actinobacteria ( Kapoor et al, 2023 ). Reports showed that MS patients have a decreased presence of Parabacteroides and Butyricicoccus ( Cekanaviciute et al, 2017 ; Diaz-Marugan et al, 2023 ), while Amuciniphila , Eggerthellalenta , Bifidobacterium adolescentis , and Ruminococcus taxa are more abundant. Additionally, a strong connection was observed between GBS and Campylobacter jejuni infection ( Allos, 1997 ).…”

Immunotherapy and Dietary Selection

“…Above all, it's important to note that while certain dietary factors may have potential immunomodulatory effects, there is no one-size-fits-all approach. Dietary interventions should be personalized and consider individual factors such as cancer type, treatment plan, overall health, and any existing dietary restrictions or sensitivities [19][20][21][22][23][24][25].…”