*4.4. Psoriatic Arthritis*

An increase in the number of circulating endothelial, platelet, and monocyte-derived MPs in psoriatic patients was also observed in a study conducted by Takeshita et al. [9]. In another paper, Papadavid et al. described a considerable increase in the number of PMPs correlating with an increase in the concentration of interleukin 12 (IL-12) and an increase in the disease activity as assessed by the PASI (Psoriasis Area Severity Index) [83]. In another study with patients with severe psoriasis (with or without psoriatic arthritis), Ho et al. observed a larger number of circulating PMPs and EMPs in patients compared with the control group [47]. The researchers did not observe any differences in the number of MPs between patients with psoriasis and those with psoriatic arthritis. Contrary to expectations, no difference was observed in the number of PMPs or EMPs before and after a three-month treatment with IL12/23 p40 subunit inhibitor, despite a significant clinical improvement

measured with PASI. Increased number of PMPs in synovial fluid of patients with PsA compared to osteoarthritis was described by Boilard et al. [8].
