The gut microbiome associated with LGI1-antibody encephalitis

Area of Science:

• Neuroimmunology
• Microbiome Research
• Genetics

Background:

• Autoimmune encephalitis involves auto-antibodies targeting neuronal proteins, causing brain inflammation and dysfunction.
• LGI1-antibody encephalitis is a common form, often presenting with focal seizures, with unknown causes despite genetic predispositions like human leukocyte antigen (HLA) alleles.
• A hypothesis suggests environmental factors, such as the gut microbiome, interact with genetic susceptibility to trigger autoimmune responses.

Purpose of the Study:

• To investigate the role of the gut microbiome in LGI1-antibody encephalitis.
• To compare the gut microbiome composition and function between patients with LGI1-antibody encephalitis and matched controls.

Main Methods:

• Studied 42 patients with LGI1-antibody encephalitis (LGI1-Ab-E) and 27 controls.
• Performed metagenomic shotgun sequencing to analyze gut microbiome differences.
• Assessed compositional and functional aspects of the gut microbiome.

Main Results:

• LGI1-Ab-E patients showed a reduced ratio of Firmicutes (or Bacillota) and Bacteroidetes phyla in their gut microbiomes.
• This reduction correlated with the dosage of HLA susceptibility alleles in LGI1-Ab-E patients.
• Functional gene profiles revealed a decrease in neuroprotective short-chain fatty acids (SCFAs) in LGI1-Ab-E patients.

Conclusions:

• A compositional shift in the gut microbiome is associated with the neuroinflammatory state in LGI1-Ab-E.
• Reduced SCFA production may contribute to the pathogenesis of LGI1-antibody encephalitis.
• The gut microbiome offers potential insights into the complex etiology of autoimmune encephalitis, warranting further validation studies.