Leukotriene-A4-Hydrolase and Basic Aminopeptidase Activities Are Related with Collagen-Induced Arthritis in a Compartment-Dependent Manner

Objective: Previous study demonstrated the involvement of basic aminopeptidase (APB) activity in the development of collagen-induced arthritis (CIA). Two zinc dependent metalloenzymes (EC 3.4.11.6 and EC 3.3.2.6) are known to exhibit concomitantly APB and leukotriene-A4-hydrolase (LT-A4-H) activities. Influence of the interrelationship between both activities on arthritic processes, however, is presently uncertain. This study aimed to compare these activities in CIA. Methods: CIA was induced in rats and arthritis was assessed macroscopically. Ultracentrifugation was used to separate soluble (S) and solubilized membrane-bound (M) fractions from peripheral blood mononuclear cells (PBMCs) and synovial tissue (ST). Enzyme immunoassay was used to measure LT-A4-H activity, and Real Time Polymerase Chain Reaction was used for evaluating EC 3.4.11.6 and EC 3.3.2.6 gene expressions. Results: The existence of genes for EC 3.3.2.6 and EC 3.4.11.6 was demonstrated in the ST. Compared with control, LT-A4-H activity increased in synovial fluid (SF) and in S-PBMCs of CIA-arthritic and CIA-resistant and in M-ST of CIA-resistant, while it decreased in M-PBMCs of CIA-arthritic and CIA-resistant. In all these locations APB activity remained unchanged or inversely correlated with LT-A4-H activity. Conclusions: LT-A4-H and APB activities in joint-related samples are associated, for the first time, with EC 3.3.2.6 and EC 3.4.11.6 genes, exhibiting a compartment-dependent differential modulation of their specificity, efficiency and/or affinity or an inverse concurrent pattern. Changes in LT-A4-H activity have implications for development or resistance to arthritis in CIA model with a potential to be a diagnostic tool.