Sphingosylphosphorylcholine Ameliorates Experimental Sjögren's Syndrome by Regulating Salivary Gland Inflammation and Hypofunction, and Regulatory B Cells

Sjögren syndrome (SS) is an autoimmune disease in which immune cells infiltrate the exocrine gland. Since SS is caused by a disorder of the immune system, treatments should regulate the immune response. Sphingosylphosphorylcholine (SPC) is a sphingolipid that mediates cellular signaling. In immune cells, SPC has several immunomodulatory functions. Accordingly, this study verifies the immunomodulatory ability and therapeutic effect of SPC in SS. To understand the function of SPC in SS, we treated SPC in female NOD/ShiJcl (NOD) mice. The mice were monitored for 10 weeks, and inflammation in the salivary glands was checked. After SPC treatment, we detected the expression of regulatory B (B) cells in mouse splenocytes and the level of salivary secretion-related genes in human submandibular gland (HSG) cells. Salivary flow rate was maintained in the SPC-treated group compared to the vehicle-treated group, and inflammation in the salivary gland tissues was relieved by SPC. SPC treatment in mouse cells and HSG cells enhanced B cells and salivary secretion markers, respectively. This study revealed that SPC can be considered as a new therapeutic agent against SS.