Matrix metalloproteinase-8 and osteoprotegerin in saliva of children with chronic kidney disease

Abstract

Changes in mineral homeostasis cause bone disorders of the dentition in children with chronic kidney disease (CKD) and may develop long before the onset of clinical manifestations of uremic toxemia in stage 2 CKD. In recent years, much attention has been paid to noninvasive methods for diagnosing oral pathology in children. The most common indicators of metabolic bone disorders are matrix metalloproteinase-8 (MMP-8) and osteoprotogerin (OPG).
The aim of the study was to establish the patterns of changes in salivary concentrations of MMP-8 and OPG in children with various severity of CKD.
Subject and methods. Salivary levels of MMP-8 and OPG were studied in 76 children divided into four equal groups: group 1, children with stage 1-2 CKD receiving a drug treatment; group 2, children with end-stage CKD receiving renal replacement therapy with hemodialysis; group 3, children one year after the kidney transplantation; and group 4 (comparison group), children with a minor surgical pathology without a kidney pathology. Saliva samples were collected by the absorption method before administration of drugs for the underlying disease, one hour before the morning meal. Salivary concentrations of MMP-8 and OPG were measured by enzyme-linked immunosorbent assay.
Results. Salivary levels of MMP-8 and OPG were significantly higher in children with various severity of CKD than in the comparison group. The highest values of MMP-8 were observed in group 2 children with end-stage CKD on hemodialysis. Increased salivary OPG was noted in group 1 children with stage 1-2 CKD and in group 3 patients one year after the kidney transplantation.
Conclusion. Saliva can be used as a biological fluid for diagnosis of preclinical stages of bone metabolism disorders in children with CKD, and salivary MMP-8 and OPG can be considered as predictive and prognostic markers.