Polyarthritis and periostitis induced by Escherichia coli. Lipopolysaccharide injection in young male hamsters

OBJECTIVE: To describe the clinicopathological manifestations of lipopolysaccharide (LPS) induced arthritis in the hamster and to compare its time of onset, duration, and severity with other forms of experimentally induced arthritis. METHODS: A preparation containing 30 microg LPS from Escherichia coli was injected subcutaneously for 5 to 21 days into young male hamsters (Mesocricetus auratus). Arthritis was quantified by measuring soft tissue swelling of affected joints with calipers. After decalcification, paraffin sections were cut and stained with hematoxylin and eosin, Giemsa, and azan. Acute phase reactant apolipoprotein serum amyloid A (apoSAA) levels were determined by ELISA. RESULTS: Symmetrical polyarthritis developed within 3 days and persisted for 14-21 days, provided the hamsters received daily LPS injections. Most prominent were lesions in the carpal-metacarpal joints of the front legs and in the tarsal-metatarsal joints of the hind legs. Animals in whom LPS injections were discontinued after 4 or 7 days recovered completely. Histological findings of exudative synovitis, periarticular soft tissue swelling, and juxtaarticular periostitis were associated with a sharp rise in serum titers of apoSAA. CONCLUSION: The unusually rapid onset of arthritis and periostitis in this experimental animal model suggests that its systemic manifestations were not mediated by a classical immune response, and may represent an "innate" response of targeted cells within the synovial membrane and periosteum to bacterial cell wall endotoxins.