Background/Purpose: Cathepsin G (CTSG) is a member of the serine protease family. It is stored in primary granules of myeloid cells, dendritic cells, plasma cells, and others, and when cells are stimulated by immune complexes, pharmacological agents, or phagocytosis, CTSG is released into the extracellular space or binds to the surface of those cells that have receptors for it. Cathepsin G plays an important role in the development of inflammation, as it promotes the migration of neutrophils, monocytes, and antigen-presenting cells by changing chemokines and converting prochemerin to chemerin, and by activating cell surface receptors.

The aim of the study was to examine the level of Cathepsin G in the synovial fluid of patients with psoriatic arthritis.

Methods: The level of CTSG in the synovial fluid of 156 patients with psoriatic arthritis was studied (56 of them with DAPSA≤14, 50 with DAPSA≥14.1≤28, and 50 with DAPSA≥ < 28.1). Control groups included 50 patients with activated gonarthrosis and 10 healthy volunteers. . The synovial fluid was taken by arthrocentesis by an experienced rheumatologist, after signing the informed consent of all persons examined and observing the principles of good clinical practice. The study was conducted in the Immunology Laboratory of the Bulgarian Academy of Sciences, Sofia through ELISA. Statistical processing includes descriptive and correlation analyzes, with statistical significance p< 0.05.

Results: The level of CTSG in the synovial fluid of patients with psoriatic arthritis and DAPSA≤14 is 0.113 ± 0.02 ng/ml, of those with DAPSA≥14.1≤28 – 0.152 ± 0.02 ng/ml, of those with DAPSA≥ < 28.1 - 0.179 ± 0.02 ng/ml). The level of CTSG in the synovial fluid of patients with gonarthrosis and effusion is 0.07 ± 0.01 ng/ml and in healthy controls 0.064 ± 0.01 ng/ml. The level of CTSG in the synovial fluid of patients with psoriatic arthritis was higher than that of patients with gonarthrosis and healthy controls (p < 0.05). The level of CTSG in the synovial fluid of patients with psoriatic arthritis correlated positively with the disease activity assessed by DAPSA (R_x,y= 0.89).

Conclusion: The level of CTSG in the synovial fluid of patients with psoriatic arthritis is significantly higher in patients with high disease activity, which is associated with more severe joint destruction.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-role-of-cathepsin-g-in-joint-destruction-in-patients-with-psoriatic-arthritis/