Control of chemokine gradients by the retinal pigment epithelium.
OBJECTIVE
Proinflammatory cytokines in degenerative diseases can lead to the loss of normal physiology and the destruction of surrounding tissues. In the present study, the physiological responses of human fetal retinal pigment epithelia (hfRPE) were examined in vitro after polarized activation of proinflammatory cytokine receptors.


METHODS
Primary cultures of hfRPE were stimulated with an inflammatory cytokine mixture (ICM): interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma. Western blot analysis and immunofluorescence were used to determine the expression/localization of the cytokine receptors on hfRPE. Polarized secretion of cytokines was measured. A capacitance probe technique was used to measure transepithelial fluid flow (J(V)) and resistance (R(T)).


RESULTS
IL-1R1 was mainly localized to the apical membrane and TNFR1 to the basal membrane, whereas IFN-gammaR1 was detected on both membranes. Activation by apical ICM induced a significant secretion of angiogenic and angiostatic chemokines, mainly across the hfRPE apical membrane. Addition of the ICM to the basal but not the apical bath significantly increased net fluid absorption (J(V)) across the hfRPE within 20 minutes. Similar increases in J(V) were produced by a 24-hour exposure to ICM, which significantly decreased total R(T).


CONCLUSIONS
Chemokine gradients across the RPE can be altered (1) through an ICM-induced change in polarized chemokine secretion and (2) through an increase in ICM-induced net fluid absorption. In vivo, both of these factors could contribute to the development of chemokine gradients that help mediate the progression of inflammation/angiogenesis at the retina/RPE/choroid complex.
Shi
Guangpu
G
National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2510, USA.
Maminishkis
Arvydas
A
Banzon
Tina
T
Jalickee
Stephen
S
Li
Rong
R
Hammer
Jeffrey
J
Miller
Sheldon S
SS
D001693:Biological Transport, Active; D015153:Blotting, Western; D001834:Body Water / Q000378:metabolism; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism; D004338:Drug Combinations; D005333:Fetus / Q000166:cytology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D017471:Receptors, Interferon / Q000378:metabolism*; D053573:Receptors, Interleukin-1 Type I / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000096743:Interferon gamma Receptor
D004338:Drug Combinations; D007371:Interferon-gamma; D053583:Interleukin-1beta; D017471:Receptors, Interferon; D053573:Receptors, Interleukin-1 Type I; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D000096743:Interferon gamma Receptor