Background/Purpose:   Sjögren’s syndrome (SS) is an autoimmune exocrinopathy of unknown etiology that is characterized by decreased salivary secretion (xerostomy) and lacrimal (xerophthalmy). Histopathological lesions of the glandular tissue in SS are characterized by the presence of mononuclear cell infiltrates and acinar atrophy. Studies on the pattern of inflammatory mediators have shown high amounts of IL-2, IFN-γ, IL-10, IL-1β, IL-6, SDF-1α and TNF-α. However, little is known about the implication of this cytokine profile in de SS pathogenesis. Objectives:1) to establish and characterize a model of human salivary gland in vitro, and 2) analyze if this model the functional effect of proinflammatory mediators present in the glandular microenvironment of SS patients.

Methods:  human epithelial cells from biopsies of non-cancerous parotid gland, were enzymatically dispersed, cultured and expanded in medium MCDB153 supplemented with insulin, hydrocortisone and epidermal growth factor. Proliferation assays were performed using a cell proliferation kit. The expression of amylase, VAMP-2, SMA1 and epithelial sodium channels (ENaC), were studied by immunofluorescence in confocal microscopy. The gene expression of the mineralocorticoid receptor, sodium channels (α, β, γ) and a number of genes characteristic of ducts or acini were analyzed by real-time RT-PCR. For the functional study of sodium channels in the plasma membrane were determined by patch clamp assays. Amylase activity in cell-free supernatant was assayed by a fibril-degradation assay and was used as a surrogate marker of exocrine gland function.

Results:  Cells from human salivary gland had morphology of epithelial cells and were able to proliferate in culture. The pattern of gene expression of these cells was more compatible with an acinar rather than ductal origin. Furthermore, the functionality of epithelial sodium channel in their surface was analyzed by patch clamp experiments. The presence of 10μM isoproterenol and 2 mM Ca⁺⁺ for 24 hours increased three times the basal activity of amylase in the cell-free supernatant of these cells. Moreover, the presence of TNF-α and SDF-1α  caused a significant dose-response reduction in the amylase activity in the cell-free supernatant.

Conclusion: It is possible to set up a functional model of human salivary gland in vitro that allows the development of studies which could lead to better understanding of the pathogenesis of SS and may help to develop therapeutic interventions for this disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characterization-of-an-in-vitro-model-of-human-salivary-gland-for-studying-sjogren-syndrome-ss/