Macrophages treated with synovial exosomes of RA patients (2.011 ± 0.3548 folds, p = 0.079) displayed relatively higher TRAP activity than those of OA patients (1.183 ± 0.2440 folds), but less prominent in AS patients (1.559 ± 0.3734 folds) or gout patients (1.435 ± 0.09832 folds) (Figure 2C). Here, ACP5 is linked to gout.