Transcriptomic Profile of Genes Encoding Proteins Involved in Pathogenesis of Sjögren's Syndrome Related Xerostomia-Molecular and Clinical Trial

Sjögren's syndrome (SS) is characterized by xerostomia. We aimed to investigate and compare gene expressions in the labial salivary glands of SS patients with xerostomia SS (sicca) and without xerostomia SS (non-sicca) and of healthy subjects (HS) by means of microarray analysis, and to find genes involved in xerostomia. The study group comprised 11 SS patients (3 SS (sicca) and 8 SS (non-sicca)) and 9 HS. The relative gene expression changes were validated with RT-qPCR in the larger study group. Among the differently expressed genes belonging to the "secretion" ontology group with a fold change >2 and with a p value < 0.05, the Transmembrane P24 Trafficking Protein 10 (TMED10), Protein Disulfide Isomerase Family A Member 4 (PDIA4), Calnexin (CANX), Amyloid Beta Precursor Protein (APP), and Transmembrane BAX Inhibitor Motif Containing 6 (TMBIM6) gene expressions in both SS (sicca) and SS (non-sicca) groups were lower than in HS. Significant correlations were observed between TMED10, PDIA4, and CANX gene expression in SS (sicca) patients compared to the controls. There were no differences between the SS (sicca) and SS (non-sicca) study groups in the expression of the aforementioned genes. Results indicate their role in the endoplasmic reticulum system, their overlapping function and the loss of the APP neuroprotective function in xerostomia. It has a multifactorial origin and can be triggered by disturbances to the various signaling pathways in saliva secretion.