Cytokine profile in the synovial fluid of children with Legg-Calvé-Perthes disease and transient synovitis of the hip

Background. The nature of synovitis development in the early stages of Legg-Calvé-Perthes disease (LCPD), as well as certain aspects of the pathogenesis of subsequent osteodestructive processes, remains incompletely understood. A targeted approach to the treatment of the hip osteochondropathy should be based on an understanding of the dysregulation of osteogenesis at the molecular and cellular levels. The aim of the study — to perform a comparative analysis of the concentrations of immunoregulatory molecules in the synovial fluid of patients with manifested Legg-Calvé-Perthes disease and those with transient synovitis of the hip. Methods. This prospective case-control pilot study included two groups of children. We analyzed the concentrations of five mediators/chemokines/cytokines (CD40, MDC/CCL22, Fractalkine (CX3CL1), IP10/CXCL10, VEGF) in the synovial fluid of 42 children with transient synovitis of the hip (TSH), as well as in 26 children with stage II LCPD according to the Waldenström classification. Results. The conducted study demonstrates differences in the nature of synovial inflammation with favorably occurring TSH and LCPD. The concentrations of regulatory molecules in synovial fluid depends on the predominant etiological factor and may influence the processes of osteoresorption and osteogenesis. Thus, changes in cytokine activity in patients with LCPD indicate the significance of disturbances in the coupling of angiogenesis and osteogenesis at the molecular and cellular levels. An increase in the concentration of phosphoprotein CD40, along with VEGF-induced glycoprotein proliferation, is associated with the activation of inflammation in vascular disorders. In the development of TSH, an increase in the level of cytokine IP10, which regulates the Th1 immune response, was observed. Conclusions. In transient synovitis of the hip, the predominant factor is the immune-inflammatory response accompanied by activation of the chemokine system. The manifestation of Legg-Calvé-Perthes disease is associated with disturbances in the coupling of angiogenesis and osteogenesis at the molecular and cellular levels, as well as with increased expression of inflammatory mediators.