Objective: To compare inflammatory peripheral arthritis in wild-type and high molecular weight kininogen (HK)-deficient rats, both on the genetically susceptible Lewis background.
Methods: By backcrossing Brown-Norway HK-deficient rats with Lewis rats for 6 generations, 2 new strains were produced, wild-type F6 and HK-deficient F6, each with a 98.5% Lewis genome. Inflammatory arthritis was induced by intraperitoneal injection of peptidoglycan-polysaccharide (PG-PS), and the clinical, histopathologic, and biochemical responses were compared in both strains.
Results: Eighteen days after PG-PS injection, rats with normal concentrations of HK showed weight loss and marked increase in hind ankle diameter with severe synovial inflammation and cartilage abnormalities. In contrast, HK-deficient rats showed no weight loss (P < 0.05), no increase in hind ankle diameter (P < 0.05), and an absence of inflammatory changes (P < 0.05), as measured by the histologic and morphometric Mankin grading system for synovial and cartilage injury.
Conclusion: Plasma HK is a key mediator of acute and chronic inflammatory arthritis in genetically susceptible Lewis rats.