Proinflammatory microbial products as etiologic agents of inflammatory arthritis.

Muramyl peptides, peptidoglycans, peptidoglycan-polysaccharide complexes, and endotoxins are examples of proinflammatory microbial components that may play an etiologic role in various chronic inflammatory arthritides in humans. This article reviews the data supporting this hypothesis. The biologic activities of these substances are discussed, with particular emphasis on the mechanisms by which they induce various forms of arthritis in experimental animals. In addition, the current status of studies attempting to demonstrate definitively a role for these agents in human disease also is discussed.