Secretory leukocyte protease inhibitor influences periarticular joint inflammation in -infected mice.

Lyme disease, caused by , is the most common tick-borne infection in the United States. Arthritis is a major clinical manifestation of infection, and synovial tissue damage has been attributed to the excessive pro-inflammatory responses. The secretory leukocyte protease inhibitor (SLPI) promotes tissue repair and exerts anti-inflammatory effects. The role of SLPI in the development of Lyme arthritis in C57BL/6 mice, which can be infected with , but only develop mild joint inflammation, was therefore examined. -deficient C57BL/6 mice challenged with had a higher infection load in the tibiotarsal joints and marked periarticular swelling, compared to infected wild type control mice. The ankle joint tissues of infected -deficient mice contained significantly higher percentages of infiltrating neutrophils and macrophages. -infected -deficient mice also exhibited elevated serum levels of IL-6, neutrophil elastase, and MMP-8. Moreover, using a recently developed BASEHIT (cterial election to lucidate ost-microbe nteractions in high hroughput) library, we found that SLPI directly interacts with . These data demonstrate the importance of SLPI in suppressing periarticular joint inflammation in Lyme disease.