Basic aminopeptidase activity is an emerging biomarker in collagen-inducedrheumatoid arthritis

ABSTRACT

The objective of this study was to investigate the catalytic activity of basic aminopeptidase (APB) and itsassociation with periarticular edema and circulating tumor necrosis factor (TNF)-alpha and type II collagen(CII) antibodies (AACII) in a rat model of rheumatoid arthritis (RA) induced by CII (CIA). Edema does not occurin part of CII-treated, even when AACII is higher than in control. TNF-alpha is detectable only in edematousCII-treated. APB in synovial membrane is predominantly a membrane-bound activity also present in solubleform and with higher activity in edematous than in non-edematous CII-treated or control. Synovial fluid andblood plasma have lower APB in non-edematous than in edematous CII-treated or control. In peripheral bloodmononuclear cells (PBMCs) the highest levels of APB are found in soluble form in control and in membraneboundform in non-edematous CII-treated. CII treatment distinguishes two categories of rats one with arthritic edema, high AACII, detectable TNF-alpha, high soluble and membrane-bound APB in synovial membrane and low APB in the soluble fraction of PBMCs, and another without edema and with high AACII,undetectable TNF-alpha, low APB in the synovial fluid and blood plasma and high APB in the membranebound fraction of PBMCs. Data suggest that APB and CIA are strongly related.