Comparative analysis of the expression of the soluble IL-7 receptor in patients with arthropathy

Arthropathy is one of the most prevalent diseases, which are based on the destruction and remodeling of cartilage and bone tissue. The inflammation that precedes destruction can be caused by mechanical stress on the joints, or by autoimmune reactions. Recently, IL-7 is considered as one of the key cytokines that promote the production of matrix metalloproteinases, catabolic enzymes, T cell-mediated activation of monocytes, and maturation of osteoclasts. The soluble form of the IL-7 receptor can help prolong the lifespan of IL-7 and thereby it ensures the bioavailability of the cytokine and mediates effect of IL-7 on cells. The aim of this study was to determine the soluble form of the IL-7 receptor (sIL-7R) in the blood plasma of patients with rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA) and psoriasis vulgaris (PS), as well as healthy individuals. The RA patients included in the study had moderate to high disease activity according to the DAS28 index. Patients with PsA predominantly had moderate and low disease activity (DAS28) and were characterized by mild to moderate disease severity (PASI). In accordance with the PASI index, patients with PS with mild and severe severity of the disease were included in the study. All patients with OA had a metabolic phenotype that is accompanied by an elevated body mass index. sIL-7R was determined in blood plasma by enzyme-linked immunosorbent assay. It was found that in patients with arthropathy, the level of soluble form of IL-7 was increased relative to healthy individuals, with the exception of the group of patients with PsA. Also, a high concentration of sIL-7R was observed in patients with PS. Analyzing the clinical characteristics of the patients, we found that sIL-7R levels were elevated in RA and PsA patients with high disease activity by DAS28. In addition, positive correlations were found between the concentration of sIL-7R and DAS28 in RA and PsA. In patients with PsA with moderate severity of the disease (PASI), the concentration of sIL-7R was also increased relative to donor's values. On the contrary, in patients with PS, a high level of sIL-7R was noted regardless of the severity of the disease. In patients with OA, no relationship was found between sIL-7R levels and clinical parameters. Thus, an elevated level of sIL-7R in patients with arthropathy may indicate the involvement of IL-7 and its receptor system in the pathogenesis of joint diseases. The IL-7 receptor may becom