Do cytokines have a role in the regulation of lacrimal gland acinar cell ion transport and protein secretion?

Abstract

The present study explored the potential involvement of cytokines (IL-1 alpha, IL-1 beta, IL-6, and IFN-gamma) in the regulation of basic physiological processes carried out by lacrimal acinar cells. Overall, evidence gathered supports the hypothesis that cytokines may be involved in the regulation of lacrimal secretory processes. When combined with earlier studies, these data suggest that acute treatment (i.e., 20 min) of acinar cells with cytokines does not significantly impact either basal or carbachol-stimulated ion transport or protein secretion. However, chronic treatment of cultured acinar cells with cytokines does appear, in some instances, to influence these cell functions. For example, 24 h treatment of acinar cells with IL-6 or IFN-gamma did not alter basal or carbachol-stimulated protein (beta-hexosaminidase) secretion, whereas a combination of IL-1 alpha and IL-1 beta decreased carbachol-stimulated beta-hexosaminidase secretion by 80%. The mechanism behind this effect is unknown, but it appears to stem from an increase in the basal secretion rather than a decrease in the stimulated secretion. Future studies will attempt to identify the mechanism behind the actions of IL-1 alpha and IL-1 beta, in addition to testing other pertinent cytokines (e.g., TNF-alpha, TGF-beta). The study of cytokine involvement in the regulation of lacrimal acinar cell physiology has received relatively little attention. Thus, substantial gaps remain concerning the identity of cytokines, their source(s) and interplay, receptor distribution, second messenger involvement, and ultimate influence over the secretion of aqueous tears.