# Antigen-specific activation of gut immune cells drives autoimmune neuroinflammation

## TL;DR

This study shows how gut bacteria expressing brain antigens can trigger immune responses linked to autoimmune neuroinflammation, like multiple sclerosis.

## Contribution

The paper introduces a novel method of using genetically engineered gut bacteria to study antigen-specific immune activation in autoimmunity.

## Key findings

- Bacteria expressing myelin peptides, but not ovalbumin, worsen autoimmune neuroinflammation in mice.
- Antigen-specific T and B cells in the gut are activated by these engineered bacteria.
- The findings suggest that targeting specific gut bacteria could help treat autoimmune diseases.

## Abstract

Microbiome-based therapies are promising new treatment avenues. While global alterations in microbiota composition have been shown in multiple sclerosis, whether and how gut microbiota influence autoimmune responses in an antigen-specific manner is unclear. Here, we genetically engineered gut bacteria to express a brain antigen and dissect their pathogenic potential in a murine model of autoimmune neuroinflammation. Colonization with bacteria expressing myelin - but not ovalbumin-peptide exacerbates an encephalitogenic immune response in the gut by activating antigen-specific T cells as well as B cells leading to accelerated neuroinflammatory disease. These results demonstrate how antigen-specific microbial modulation can influence autoimmunity, providing insight for development of therapeutic strategies targeting specific bacterial taxa for treatment of MS and other autoimmune diseases.