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Primary human choroidal melanocytes express functional Toll‐Like Receptors ( TLR s)
Author(s) -
Cioanca V.A.,
McCluskey P.J.,
Madigan M.C.
Publication year - 2017
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2017.03346
Subject(s) - innate immune system , toll like receptor , immune system , tlr3 , receptor , flagellin , biology , microbiology and biotechnology , chemistry , immunology , biochemistry
Purpose Human choroidal melanocytes ( HCM s) are an abundant heterogeneous, melanin‐containing population of cells within the vascular uveal tract. Toll‐like receptors ( TLR s) are pattern recognition receptors involved in the innate immune response against phylogenetically conserved microbial components. Immune cells are established to express TLR s and more recent studies showed TLR expression on non‐immune cells including corneal and conjunctival epithelia, retinal microglia and RPE , iris pigment epithelium, and skin melanocytes. The expression of TLR s on uveal melanocytes however remains to be investigated. Methods HCM s were isolated and cultured from donor human eyes. TLR 1‐10 and MYD 88 (a critical adaptor protein in the TLR signalling pathway) expression was investigated using RT ‐ PCR and confirmed by immunocytochemistry. The production of IL ‐8 and CCL 2 in response to TLR agonists was measured by ELISA . Results HCM s constitutively expressed TLR 1‐6, TLR 9, and MYD 88. Stimulation of HCM s with bacterial‐derived TLR agonists [Pam3 CSK 4 ( TLR 1/2), HKLM ( TLR 2), LPS ( TLR 4), Flagellin ( TLR 5) and, FSL ‐1 ( TLR 6/2)] and virus‐mimicking TLR agonists [Poly I:C ( TLR 3), Imiquimod ( TLR 7), ss RNA 40 ( TLR 8) and ODN 2006 ( TLR 9)] induced variable secretion of IL ‐8 and CCL 2 ( MCP ‐1). Control levels of IL 8 (140 pg/ml) increased in response to Pam3 CSK 4 (2360 pg/ml), Poly I:C (3620 pg/ml), LPS (4100 pg/ml), Flagellin (1550 pg/ml) and FSL ‐1 (2160 pg/ml). Virus‐mimicking agonists imiquimod, ss RNA 40 and ODN 2006, and intriguingly bacteria‐derived HKML , did not significantly affect secreted IL 8. Secreted CCL 2 showed a similar pattern of response following stimulation with TLR agonists. HCM s were immunoreactive for TLR 2, TLR 3 and TLR 4 protein. Conclusions The findings suggest that HCM s are potentially involved in innate immune responses against bacterial and viral pathogens within the human choroid.