Basal-Lateral/Endomembrane Traffic in Lacrimal Acini

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DESCRIPTION (provided by applicant): Primary Lacrimal Deficiency and Sjogren's autoimmune dacryoadenitis are more common in women than men, and the same constellation of hormonal factors, i.e., insufficient bioavailable testosterone and excessive prolactin, may contribute to both pathologies. Lacrimal insufficiency also may occur after refractive surgery. Sjogren's autoimmunity targets the M3 muscarinic receptor, a cell surface protein, and various intracellular proteins. An emerging understanding of traffic between the basal-lateral plasma membranes and endomembrane compartments suggests the immune system may lose its tolerance for familiar proteins, or become activated against cryptic proteins, when: (a) changes in traffic increase the rates at which acinar cells express intracellular autoantigens at their blm or secrete them to the interstitium; (b) acinar cells begin to express MHC Class II molecules and present autoantigen peptides directly to CD4 T cells; or (c) the spectrum of immunomodulatory factors acinar cells secrete to the interstitium becomes immunostimulatory instead of immunosuppressive. In vivo experimental perturbations that alter blm / endomembrane traffic include: chronic and supramaximal secretory stimulation, which might arise in vivo as the lacrimal gland - ocular surface servomechanism compensates for lacrimal dysfunction due to androgen insufficiency or prolactin excess; stimulation with epidermal growth factor (EGF), which may be elicited in vivo in response to corneal trauma; and culture in the presence of prolactin, which may mimic high prolactin states. The specific aims of the proposed work are to: 1. Identify membrane protein sorting mechanisms that are altered when lacrimal acinar cells are stimulated with (EGF). 2. Map the traffic of M3 cholinergic receptors; test the hypotheses that acinar cells secrete M3 proteolytic fragments to the interstitium; that acinar cells present M3 peptides to CD4 T cells via MHC Class II molecules; and that chronic stimulation with carbachol decreases M3 receptor turnover, potentially decreasing M3-related antigenic stimulation. 3. Test the hypotheses that a milieu containing excessive prolactin alters protein sorting in the absence and presence of cholinergic stimulation and that excessive prolactin increases turnover of M3 receptors, potentially increasing M3-related antigenic stimulation. 4. Map the traffic of endogenously expressed IL-2 and transduced anti-inflammatory cytokines, such as IL-10. Test the hypotheses that IL-10 alters traffic of endogenous proteins; that chronic stimulation with carbachol in the absence of androgens increases traffic of IL-2 and IL-10 via the apical secretory pathway; and that chronic carbachol stimulation in the presence of androgen increases secretion via the blm.