Salivary cytokines in children with nephrotic syndrome versus healthy children: A comparative study

Background: The aims of this study were to compare salivary cytokines and total protein between children with nephrotic syndrome (NS) and healthy children, and to examine whether saliva parameters can differentiate between steroid sensitivity and resistance and between disease remission and relapse. Methods: Twenty-seven children with nephrotic syndrome were classified according to steroid sensitivity and resistance, and disease remission and relapse. Twenty healthy children served as controls. Whole saliva samples were collected from all the participants. Urine and blood tests done on the same day as the saliva collection were recorded. Salivary total protein was quantified using bicinchoninic acid and IFNγ, IL-4, IL-8, IL-6, and IL1β levels using ELISA. Results: The mean ages of the nephrotic syndrome and control groups were 11.3 ± 2.4 and 9 ± 4.2, respectively. Compared to the control group, for the nephrotic syndrome group, total salivary protein was significantly lower, as were the levels of all the cytokines examined except IFNγ. Statistically significant differences were not found in any of the salivary markers examined between the children with nephrotic syndrome who were treatment sensitive (n = 19) and resistant (n = 8). Protein and IL-8 salivary levels were lower in the active (n = 7) than in the remission (n = 20) group. Conclusions: Salivary parameters distinguished children with nephrotic syndrome in relapse from healthy children. This may be due to decreased salivary protein excretion, which reflects decreased plasma levels, consequent to proteinuria. Accordingly, salivary markers may be developed as a diagnostic or screening tool for NS activity.