OBJECTIVES: Peptidoglycan (PG), a component of Gram-positive bacteria, may
be involved in rheumatoid arthritis (RA) because of its ability to induce
production of proinflammatory cytokines, to induce arthritis in rodents,
and its presence in antigen-presenting cells in RA joints. METHODS: In the
present study, physiologically relevant PG was able to induce T-cell
proliferation in peripheral blood and synovial fluid samples of RA
patients, but the magnitude of the response did not differ from that of
cells from healthy subjects. In addition, production of cytokines
associated with RA (interleukins (IL)-1beta, IL-6, IL-8, IL-10, IL-12 and
tumour necrosis factor alpha) and of the matrix metalloproteinase,
gelatinase B (MMP-9), was induced in blood and synovial fluid cultures of
RA patients. CONCLUSION: The fact that PG, which can be found in synovial
tissues of RA patients is able to induce the production of inflammatory
mediators supports t