The Serum Marker Enzymes Activity and Metabolic Connective Tissue Disorders in Patients on Early Stages of Osteoarthritis of the Knee Joints

The article deals with the determination of the marker enzymes activity (hyaluronidase, alkaline phosphatase and its bone isoenzymes), serum and urine concentrations of fibronectin, uric acid and uric acid in patients with osteoarthritis of the knee joints of the 1-st and 2-nd stage. The concentration of serum fibronectin in the studied patients increased to 34.1 %. The increase in the concentrations of fibronectin causes by its direct combination of extracellular matrix in the joints, which, in the development of inflammatory and destructive process, is destabilizing due to chondrocytes with a matrix. Fibronectin stabilizes the ligaments and structure of the matrix of cartilage tissue, binds to the oligomeric protein of the cartilaginous matrix and adorns the surface of collagen fibrils. Lysosomal enzymes – hyaluronucleosaminidase, carried out the destruction of proteoglycans in the cartilage of the joints and hyaluron-glucuronidase, the total activity is usually called hyaluronidase activity. The activity of hyaluronidase was increased to 26.9 % compared with clinically healthy subjects. Investigation of hyaluronidase activity indicates an imbalance between destructive and biosynthetic processes in the metabolism of glycosaminoglycans in cartilage is damaged and it is a mark of inflammatory and destructive processes in the synovial fluid of the joints in osteoarthritis. The increase in serum hyaluronidase activity in some patients on the I–II stages of knee osteoarthritis, which was established during the study, indicates that the enzyme is involved in the development of the inflammatory and destructive process. This process is accompanied by depolymerization of the macromolecules of the proteoglycans of the articular cartilage, including hyaluronic acid, one of the components of the synovial fluid. In addition, one of the most informative markers of osteoblastic activity of bone tissue is the activity of bone isoenzymes of alkaline phosphatase. An increase in the activity of alkaline phosphatase and its bone isoenzymes in 94.5 % indicate damage to the tissues of the cartilage of the knee joints on the early stages of the disease. Cartilage collagen has a special structure and amino acid composition, so it is called collagen type II, which contains amino acids, proline and oxyproline (hydroxyproline). Oxiproline has an important role in stabilizing the secondary collagen structure. The relatively high content of oxyproline in collagen allows us to use the determination of the concentration of oxyproline in tissues as a marker for the total concentration of collagen proteins. The content of oxyproline in urine is used as a catabolism marker for collagen, and the concentration of oxyproline can serve as an indicator of the intensity of this process. The level of oxyproline excretion as a marker of increased catabolism of collagen in patients with early of osteoarthritis of the knee joints up to 63.5 %, uronic acids – by 27.3 % compared with clinically healthy subjects. Obviously, it is caused by a bunch of collagen fibers and the release of its main metabolite of oxyproline from the connective tissue. The knee cartilage degradation in the early stages of the disease with knee osteoarthrosis is accompanied by an increase in excretion of uronic acids due to increased catabolism of proteoglycans in the extracellular matrix of the connective tissue. These tests can be informative to assess the course of osteoarthritis of the knee joints and control the effectiveness of its treatment.