Neutralizing gut bacterial fragments improves autoimmunity

An antibody that neutralizes a specific type of bacterial cell wall fragment, lessening the severity of several autoimmune diseases in mice, is reported in a paper published online in Nature Microbiology this week. Further research is needed to determine whether this neutralization approach is safe and effective in human patients with autoimmune disease.

Bacteria are powerful activators of the immune system. Previous work suggests a link between human microbiota - the bacteria that normally live on and inside us - and the development of autoimmune disease. It has also been shown that microbiota can release pieces of their cell walls into circulating blood, and that cell walls can aggravate autoimmune disease in animals.

Yue Wang and colleagues show that a type of cell wall fragment known as a peptidoglycan subunit turns on the immune system and worsens autoimmune arthritis in mice. They then developed an antibody that specifically neutralizes this fragment, and demonstrated that administering the antibody in mice lessens the severity and onset of several autoimmune disorders.

The study offers a potentially new treatment avenue for autoimmunity: administering an antibody to remove a bacterial immune signal rather than using immunosuppression drugs, which can have undesirable side effects.