The aim of the present study was to investigate the effects of blue honeysuckle extract (BHE), which contains high level of phenolic compounds, on
endotoxin-induced
uveitis (EIU). Male Lewis rats were randomly divided into 5 groups with 14 rats in each (eight rats for collection of aqueous humor, six rats for histologic examination). EIU was induced by a footpad injection of
lipopolysaccharide (LPS). 1, 10, or 100 mg of BHE was injected intravenously immediately after LPS injection. The aqueous humor was collected at 24 h after LPS injection, the number of infiltrating cells,
protein concentration,
nitric oxide (NO),
tumor necrosis factor (
TNF)-alpha, and
prostaglandin (PG)-E2 levels in the aqueous humor were determined. Some eyes were enucleated for histologic examination and immunohistochemical analysis. Immunohistochemical staining with a
monoclonal antibody against activated nuclear factor (
NF)-kappaB was performed to evaluate the effect of BHE on
NF-kappaB activation. To further clarify the anti-inflammatory effect, RAW264.7 cells (a mouse macrophage cell line) were stimulated with LPS in the presence or absence of BHE and its major phenolics,
cyanidin 3-glucoside (C3G),
cyanidin 3-rutinoside (C3R),
chlorogenic acid (CA). Expression of inducible
NO synthase (iNOS) and
cyclooxygenase-2 (COX-2) were analyzed by Western blot method. BHE treatment significantly reduced the inflammatory cell infiltration, the
protein concentration, the levels of NO,
TNF-alpha and
PGE2 in the aqueous humor and improved histologic status of the ocular tissue. The number of activated
NF-kappaB-positive cells was lower in the iris-ciliary body treated with BHE at 3 h after LPS injection. BHE significantly suppressed the production of NO,
PGE2 and
TNF-alpha in the culture medium as well as the expression of iNOS and COX-2 by LPS-stimulated RAW264.7 cells in a dose-dependent fashion. C3G, C3R and CA showed no or weak inhibitory effects on the level of inflammatory mediators and the expression of iNOS and COX-2. These results suggest that BHE attenuates the degree of
inflammation in eyes with EIU by inhibiting the
NF-kappaB dependent signaling pathway and the subsequent production of proinflammatory mediators.