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Terry G Coursey, David B. Corry, Stephen C Pflugfelder; Conjunctival goblet cell produced secretory leukocyte peptidase inhibitor (SLPI) controls growth of Aspergillus fumigatus. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the mechanisms that conjunctival goblet cells (GC) use to regulate fungal growth in the eye. The eye is constantly subjected to fungi as an exposed mucosal site. Surprisingly, fungi (of any kind) in healthy human eyes are rare. Very little is known about how the eye controls and prevents fungal growth in normal circumstances.
Primary conjunctival GC cultures were established from tissue explants of forniceal conjunctiva dissected from female C57BL/6 mice. GC culture supernatants were harvested after 10 days of culture. 100 or 500 A. fumigatus conidia (fungal spores) were incubated with control medium (Keratinocyte serum-free media, KSFM) or GC conditioned KSFM supernatants for 24h. GC cultures were treated with protease from Aspergillus oryzae (PAO) (100 ug/mL) for 24h prior to harvesting conditioned supernatant. Fungal growth was quantified using cell-proliferation reagent WST-1 for the last two hours of the 24h incubation with GC supernatant or recombinant human (rh) SLPI (5 and 10 μM). Expression of SLPI in GC cultures was determined by qPCR.
Incubation of conidia from A. fumigatus with supernatants from conjunctival GC culture supernatant inhibited fungal growth by 60% compared to control medium. Incubation with supernatant from cultures treated with PAO reduced fungal growth by 80%. Treatment of GC cultures with PAO increased mRNA expression of SLPI by 2.5-fold. GC cultures expressed SLPI 20-fold higher than corneal epithelial cell cultures. The addition of rhSLPI to conidia from A. fumigatus reduced fungal growth by 40%.
These studies suggest that conjunctival GC make antimicrobial products that inhibit fungal growth constitutively, and this GC function is augmented during exposure to fungal proteases. Production of SLPI by conjunctival GCs may be an important mechanism by which fungal growth is controlled in the eye. Understanding of the mechanisms employed by the eye to control fungal growth may lead to improved, less toxic treatments for fungal keratitis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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