SERUM LEVELS OF SOLUBLE RECEPTOR ACTIVATOR OF NUCLEAR FACTOR- KAPPA-B Ligand (S-RANKL) IN PATIENTS WITH DIFUSSE IDIOPATHIC SKELETAL HYPEROSTOSIS AND ANKILOSING SPONDILITIS

Background: S-RANKL (Receptor activator of nuclear factor Кappa-B ligand) is a member of the TNF/TNF receptor superfamily. RANKL has been identified to control bone regeneration and remodeling. S-RANKL is secreted by osteoblasts and binds to the RANK receptor on osteoclast precursor and mature osteoclast cells. Variation in concentration levels of S-RANKL throughout several organs reconfirms the importance of RANKL in bone growth. S-RANKL is ability to stimulate osteoclast formation and activity.Methods: S-RANKL is estimated on 55 patients with Diffuse Idiopathic Skeletal Hyperostosis (DISH), 25 patients with Ankylosing Spondilitis (AS), 50 patients with spondylosis and 15 particularly healthy people aged 55-65. All patients were treated and monitored in University Clinic of Rheumatology, UMHAT “Sveti Georgi”, Plovdiv, Bulgaria. The measuring of the S-RANKL is done by ЕLISA-method with reader (Sitio-Microplate reader, Seac, Itаlу), ƛ 450 nm, with a kits of eBioscience, Austria. The statistic processing is done with SPSS 23 programme (p<0.01).Results:The average measurements of s-RANKL of patients with DISH were 197,00±35,90 pg/ml, in patients with AS 190,86±18,54 pg/ml. S-RANKL in patients with spondilosis were 20,60±66,16 pg/ml, and in old control group were 23,33±15,07 pg/ml. The average measurements of s-RANKL in patients with DISH and AS were significant higher in comparison with the results of patients with spondylosis and healthy people, regardless of their age (p<0.05).Conclusion: S-RANKL is significantly increased in patients with DISH and spondylosis in comparison with the results of patients with AS and healthy old people. Hypothetically, this might be a result as a sequence of events, based on stimulation of inflammatory proteins, on-going osteoporosis and compresion fractures in patients with DISH and spondylitis. The endurance of the vertebrae is decreased and the body increases the production of proteins from the osteoblasts to form compensatory more bone substance. The overproduction of S-RANKL is implicated in new bones formation in patients with DISH. Blocked up at S-RANK might have an important role in the suppression of pathological processes in this diseases. The results indicate a possible common pathogenic connection between inflammatory joint disease (AS) and degenerative joint disease(DISH).