Purine Catabolic Enzymes in Human Synovial Fluids
The metabolic derangements that cause or are associated with osteoarthritis (OA), calcium pyrophosphate dihydrate (CPPD) crystal deposition disease and Milwaukee shoulder syndrome (MSS, also called basic calcium phosphate [BCP] arthropathy) are poorly understood. Observation of elevated concentrations of inorganic pyrophosphate (PPi) in synovial fluid compared to plasma from patients with each of these diseases suggest a role for PPi in these arthropathies (1–3). Tenebaum, et al, have found that extracts of articular cartilage from patients with OA and CPPD deposition contain elevated activities of ATP pyrophosphohydrolase (NPPH) and 5′-nucleotidase (5NT) compared to normal cartilage with the highest activities found in CPPD-containing cartilage (4). Increased activities of these two enzymes, which are ecto-enzymes in articular cartilage (5–7), theoretically could contribute to the pathogenesis of these arthropathies by causing increased PPi accumulation (Figure 1). Synovial fluid adenosine deaminase (ADA) activity has recently been reported to be elevated in rheumatoid arthritis (RA) compared to OA (8). We have measured the activity of these three enzymes plus alkaline phosphatase (AP) in synovial fluids from 173 patients with well-characterized arthropathies to determine the relationship between the activities of these enzymes and various diseases.
KeywordsSynovial Fluid Matrix Vesicle Basic Calcium Phosphate Inorganic Pyrophosphate CPPD Crystal
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