Th17 cell differentiation increases aquaporin-3 expression, which is further increased by treatment with NaCl.

Abstract

Abstract Aquaporin3 (AQP3) is one of 13 members of the aquaglyceroporin family that transports water and other small molecules across the cell membrane. In the immune system, AQP3 is important in macrophage phagocytosis, T cell migration, and dendritic cell activation. Th17 cells are thought to play a pivotal role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), which is sensitive to salt intake. Through microarray, we previously demonstrated that in vitro differentiation of mouse Th17 cells increases AQP3 mRNA abundance over that seen in Th0 T cells. Utilizing both Western and flow cytometric analyses, we now show that this mRNA increase is correlated with an increase in AQP3 protein abundance, whereas Th1 differentiation has no significant effect on AQP3 protein abundance as compared with Th0 cells. Moreover, increased concentration of NaCl (40 mM over standard) to the medium further augments AQP3 protein abundance, but only within Th17 differentiated cells. We have also extended these studies to human T cells and found that human CCR6 positive cells, previously characterized as IL-17 producing cells constitutively express more AQP3 protein than human CCR6 negative cells. To test whether Th17 cells express more AQP3 protein than Th1 cells in vivo, we induced EAE by immunization of the mice with MOG35–55 with the mice injected with PBS as a control. We analyzed AQP3 protein abundance in splenic T cells directly ex vivo with flow cytometry and found that Th17 cells express more AQP3 protein than Th1 cells under both conditions. We conclude that Th17 cells express more AQP3 than Th1 cells both in vitro and in vivo, and that treatment with NaCl in vitro further increases AQP3 protein abundance only in Th17 cells. Supported by NMMS PP3448.