The modulation of intra-articular inflammation, cartilage matrix and bone loss in mono-articular arthritis induced by heat-killed Mycobacterium tuberculosis

Abstract

Inflammation models for the assessment of anti-rheumatic drug activity utilize a variety of stimuli and sites. However, the determination of cartilage and bone degradation remains time consuming and problematic. A rapid rat model of Mycobacterium tuberculosis monoarticular arthritis with induces of inflammation, as well as patellar cartilage proteoglycan and bone degradation has been reported. This study characterizes this model with respect to the actions of anti-rheumatic drugs. Dexamethasone, cyclosporin and prednisolone inhibited all three parameters. Methotrexate inhibited joint inflammation alone, whilst azathioprine was without effect. Levamisole inhibited cartilage and bone degradation without affecting joint inflammation. NSAIDs were divided in their actions. Naproxen, piroxicam, diclofenac and tiaprofenic acid all inhibited joint inflammation and bone loss, but naproxen and piroxicam both significantly potentiated cartilage proteoglycan loss. This model appears to rely on cellular recruitment at this early stage, the anti-metabolites being ineffective. The modulation of inflammation can result in a protection against cartilage and bone damage in arthritis; however, certain NSAIDs are detrimental to cartilage integrity. The pharmacological manipulation of inflammatory arthritis can therefore dislocate inflammation from its effects on tissue destruction.