Study of saliva transcriptome and proteome in Thai patients with dental fluorosis

Abstract

The purpose of this study was to examine the expression profiles of RNA and protein in Thai individuals with dental fluorosis and compare them with those without fluorosis. Additionally, the study aimed to establish a correlation between the severity of dental fluorosis, urinary fluoride levels, and water fluoride levels.

Methods: Schoolchildren in areas endemic for fluoride in Lamphun and Ratchaburi provinces of Thailand were screened for dental fluorosis severity and then enrolled in the study. Fluoride concentration in 24-hour urine and drinking water samples was measured using an ion-selective fluoride electrode. Saliva samples were collected in sterile tubes and stored at -20๐C for subsequent analysis. The saliva of dental and non-dental fluorosis groups were prepared for proteomic and transcriptomic analysis. Finally, urinary fluoride levels, water fluoride levels, RNA expression (transcriptome), and protein profile (proteome) were compared between individuals with and without dental fluorosis.

Result: Among 47 schoolchildren aged between 6-16 years, 27 were non-dental fluorosis, 10 were severe dental fluorosis and 10 were moderate dental fluorosis. The urine fluoride level in the severe group was significantly higher than that in the control group (p=0.007), but there was no statistically significant difference when compared to moderate groups (p=0.054). There was no statistically significant difference in water fluoride among the three groups (p=0.246). For transcriptomic analysis, there was no statistically significant difference in RNA profiles between the severe dental fluorosis and control groups. For proteomic analysis, 12 proteins were found to be differentially expressed. S100A9 was upregulated in both the severe and moderate groups when compared to the control group.

Conclusion: The study showed that the children having severe dental fluorosis had an elevation in urinary fluoride concentration. Twelve proteins were found differentially expressed between severe dental fluorosis, moderate dental fluorosis and non-dental fluorosis which are involved in biological processes including inflammation and cell apoptosis.