TY - JOUR
T1 - Lacritin-induced secretion of tear proteins from cultured monkey lacrimal acinar cells
AU - Fujii, Atsuko
AU - Morimoto-Tochigi, Ayumi
AU - Walkup, Ryan D.
AU - Shearer, Thomas R.
AU - Azuma, Mitsuyoshi
PY - 2013
Y1 - 2013
N2 - PURPOSE. During inflammation of the ocular surface, increased proinflammatory cytokines depress tear protein secretion, suggesting that a decline in lacrimal cell function contributes to dry eye. Lacritin, a glycoprotein secreted from lacrimal acinar cells, may function as an autocrine factor to stimulate tear protein secretion. The purpose of the present experiment was to investigate lacritin-induced protein secretion in normal and cytokine-pretreated (inflammation model) monkey acinar cells. METHODS. Acinar cells from monkey lacrimal glands were cultured with or without tumor necrosis factor alpha (TNF-α) plus interferon gamma (IFN-γ). Protein secretion was induced by lacritin or carbachol (Cch, positive control). Proteins were detected and identified by immunoblotting and immunocytochemistry. Intracellular Ca2+ was measured with the fluorophore Calcium-4, and cell damage was determined by LDH leakage into the culture medium. RESULTS. In cultured monkey acinar cells, lacritin stimulated tear protein secretion in normal cells without elevating intracellular Ca2+. In contrast, Cch elevated intracellular Ca2+ and release of tear proteins. This contrast suggested an alternate, calcium-independent mechanism for lacritin-induced protein secretion. TNF-α plus IFN-γ caused LDH leakage from sensitive human corneal epithelial cells, but even higher doses of TNF-α plus IFN-γ did not cause LDH leakage from monkey acinar cells, suggesting a higher tolerance against these cytokines. In cytokine-treated acinar cells, lacritin stimulated protein secretion as much as that in normal cells. In contrast, Cch-induced elevation of Ca2+ and release of proteins were depressed by cytokines. CONCLUSIONS. Lacritin might be a useful biotechnology-based treatment agent against ocular surface diseases where endogenous lacritin is inadequate.
AB - PURPOSE. During inflammation of the ocular surface, increased proinflammatory cytokines depress tear protein secretion, suggesting that a decline in lacrimal cell function contributes to dry eye. Lacritin, a glycoprotein secreted from lacrimal acinar cells, may function as an autocrine factor to stimulate tear protein secretion. The purpose of the present experiment was to investigate lacritin-induced protein secretion in normal and cytokine-pretreated (inflammation model) monkey acinar cells. METHODS. Acinar cells from monkey lacrimal glands were cultured with or without tumor necrosis factor alpha (TNF-α) plus interferon gamma (IFN-γ). Protein secretion was induced by lacritin or carbachol (Cch, positive control). Proteins were detected and identified by immunoblotting and immunocytochemistry. Intracellular Ca2+ was measured with the fluorophore Calcium-4, and cell damage was determined by LDH leakage into the culture medium. RESULTS. In cultured monkey acinar cells, lacritin stimulated tear protein secretion in normal cells without elevating intracellular Ca2+. In contrast, Cch elevated intracellular Ca2+ and release of tear proteins. This contrast suggested an alternate, calcium-independent mechanism for lacritin-induced protein secretion. TNF-α plus IFN-γ caused LDH leakage from sensitive human corneal epithelial cells, but even higher doses of TNF-α plus IFN-γ did not cause LDH leakage from monkey acinar cells, suggesting a higher tolerance against these cytokines. In cytokine-treated acinar cells, lacritin stimulated protein secretion as much as that in normal cells. In contrast, Cch-induced elevation of Ca2+ and release of proteins were depressed by cytokines. CONCLUSIONS. Lacritin might be a useful biotechnology-based treatment agent against ocular surface diseases where endogenous lacritin is inadequate.
KW - Cytokine
KW - Lacrimal acinar cells
KW - Lacritin
KW - Monkey
KW - Tear protein secretion
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U2 - 10.1167/iovs.12-10394
DO - 10.1167/iovs.12-10394
M3 - Article
C2 - 23482462
AN - SCOPUS:84875971968
SN - 0146-0404
VL - 54
SP - 2533
EP - 2540
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 4
ER -