Evidence of altered salivary cytokine concentrations in Rett syndrome and associations with clinical severity

Immune dysregulation may play a role in the development of Rett syndrome (RTT), a neurodevelopmental disorder caused by mutations of the MECP2 gene. Abnormal cytokine concentrations have been documented in the serum of individuals with RTT. Measurement of salivary cytokines has been investigated as a potential alternative approach to measurement in blood and serum, but it is unclear whether salivary cytokine concentrations can provide valid information about systemic immune function in neurodevelopmental disorders. The goal of this study was to evaluate the potential validity of salivary cytokines as biomarkers of immune dysregulation in RTT. Saliva samples from 16 individuals with RTT (all female; age range 2–40 years) and 16 healthy control females (age range 2–40 years) were analyzed for concentrations of 12 cytokines. Between-group differences in concentrations, and correlations with clinical severity in the RTT group were evaluated. Concentrations of several salivary cytokines (IL-1β, IL-6, IL-8, IL-10, GM-CSF, TNF-α, and VEGF) were increased in RTT compared to controls. The same cytokines showed significant positive correlations with clinical severity scores. There were no differences in concentrations of IL-2, IL-4, IL-5, IL-12p70, and IFN-γ. The results suggest that salivary cytokines may be a possible indicator of immune dysregulation in RTT. Future research should investigate whether these results can be applied to other neurodevelopmental disorders. •Immune dysregulation may play a role in the development of Rett syndrome (RTT), a disorder caused by mutations of the MECP2 gene.•Concentrations of several salivary cytokines were increased in RTT compared to controls.•These same cytokines showed significant positive correlations with clinical severity scores.•Results suggest that salivary cytokines may be a possible indicator of immune dysregulation in RTT.