Arthritogenicity of Borrelia burgdorferi and Borrelia garinii: comparison of infection in mice.

Arthritogenicity, as determined by joint swelling and synovial histology, was compared between or within two Borrelia genospecies that cause Lyme arthritis in humans. The spirochete burden in bladder tissue (a site of spirochete persistence) was documented by quantitative polymerase chain reaction, and immune responses were analyzed. In C3H/HeJ mice, three B.

Borrelia burgdorferi, an extracellular pathogen, circumvents osteopontin in inducing an inflammatory cytokine response.

A classic proinflammatory T helper cell type 1 (TH1) response directed against intracellular pathogens includes the cytokine osteopontin, which acts predominantly on macrophages, where it induces the secretion of interleukin (IL)-12 and suppresses the secretion of IL-10. As cell-mediated immune responses play an important role in the resistance to Lyme arthritis, a manifestation of infection by the extracellular pathogen Borrelia burgdorferi, we tested the hypothesis that osteopontin may be required to induce T(H)1 responses and inflammation. The role of osteopontin was tested in vivo and using ex vivo macrophages in B6129F3 mice susceptible to experimental Lyme arthritis.