Bacteria are suspected contributors to several forms of immune-mediated, noninfectious forms of uveitis including that associated with ankylosing spondylitis, sarcoidosis, Behçet's disease and inflammatory bowel disease. Endotoxin (lipopolysaccharide)-induced uveitis has been a widely used model for more than 2 decades. Both rats and mice develop a transient, bilateral anterior uveitis after a systemic injection of endotoxin. Inflammation posterior to the lens is generally milder than anterior segment inflammation. The uveitis is severer if the lipopolysaccharides are injected intraocularly. The model has been invaluable in helping to identify mediators induced in the inflamed eye and in testing pharmacologic approaches to reduce eye inflammation. Muramyl dipeptide is another bacterial cell component that can induce uveitis in laboratory animals. Muramyl dipeptide is especially intriguing as a cause of uveitis because it activates the intracellular protein, Nod2, and mutations in the NOD2 gene are the cause of the autosomal dominant form of uveitis that is characteristic of Blau syndrome. Since a mutation in a gene that codes for a protein which senses a bacterial product consistently results in uveitis, it is critical to understand more fully the mechanisms by which bacterial products cause uveitis in laboratory animals.
- Muramyl dipeptide
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