The immune privileged retina mediates an alternative activation of J774A.1 cells.
OBJECTIVE
We have previously found that retinal pigment epithelial (RPE) cells suppressed endotoxin-stimulated macrophages; moreover, it induced expression of anti-inflammatory cytokines. We further assessed the possibility that the RPE is alternatively activating macrophages.


METHODS
J774A.1 cells were stimulated with endotoxin and treated with the conditioned media (CM) of RPE, or neuroretinal eyecups from healthy mouse eyes. The supernatant was assayed for IL-1 beta, TNF-alpha, IL-6, IL-12(p70), and IL-10, and for nitric-oxide generation. The RPE conditioned media (RPE CM) was absorbed of known soluble factors to identify the factor that augments nitric-oxide generation.


RESULTS
We found the RPE CM suppressed all cytokine production except IL-10, and augmented nitric-oxide generation. The augmented nitric-oxide levels were mediated by RPE derived alpha-melanocyte stimulating hormone (alpha-MSH).


CONCLUSIONS
Healthy RPE not only suppresses inflammatory activity, it promotes an alternative activation of macrophages that can further promote immune privilege.
Lau
Chun H
CH
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02116, USA.
Taylor
Andrew W
AW
D000818:Animals; D002460:Cell Line; D003470:Culture Media / Q000494:pharmacology; D016207:Cytokines / Q000037:antagonists & inhibitors; D004731:Endotoxins / Q000494:pharmacology; D005260:Female; D007108:Immune Tolerance / Q000502:physiology*; D016753:Interleukin-10 / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000096:biosynthesis; D012160:Retina / Q000276:immunology / Q000502:physiology*; D055213:Retinal Pigment Epithelium / Q000276:immunology / Q000502:physiology; D046509:Tissue Culture Techniques; D000521:alpha-MSH / Q000378:metabolism
D003470:Culture Media; D016207:Cytokines; D004731:Endotoxins; D016753:Interleukin-10; D009569:Nitric Oxide; D000521:alpha-MSH