Par-C10 Acinar-Spheres a Novel in vitro Model of Differentiated Acini

The use of polarized salivary gland cell monolayers has contributed to our understanding of salivary gland physiology. However, these cell models are not representative of glandular epithelium in vivo, and, therefore, are not ideal for investigating salivary epithelial functions. Objectives: to develop a three-dimensional (3D) cell culture model for rat Par-C10 parotid gland and to study the effects of: 1) the anion channel blocker DIDS, 2) replacing chloride with gluconate and 3) SS-associated proinflammatory cytokines, on agonist-mediated changes in transepithelial potential difference (PD) in rat parotid gland Par-C10 cell 3D cultures. Methods: Par-C10 cells were grown on growth factor-reduced Matrigel to allow 3D sphere formation. Confocal microscopy was used to evaluate acinar morphology and tight junction (TJ) protein distribution in polarized 3D acinar cultures with discernible lumens. Carbachol-induced changes in PD were measured in the lumen of cultures using glass microelectrodes filled with 0.3 M KCl connected to an intracellular amplifier. Results: These 3D Par-C10 acinar-like spheres displayed characteristics similar to differentiated acini in salivary glands, including cell polarization, TJ formation required to maintain PD, and responsiveness to the muscarinic receptor agonist, carbachol. The PD changes after carbachol addition was blocked by DIDS, by replacing chloride with gluconate. Additionally treatment with the proinflammatory cytokines TNFα and IFNγ caused a decrease in agonist-induced changes PD. Conclusion: These studies suggest that the Par-C10 3D spheres are "acinar-like” and suggest that cytokines decrease saliva secretion by altering TJ integrity. Thus, 3D Par-C10 acinar-like spheres represent a novel in vitro model to study physiological and pathophysiological functions of differentiated acini. Supported by NIH-NIDCR K08DE017633