Adrenomedullin in cultured human retinal pigment epithelial cells.
OBJECTIVE
To determine whether adrenomedullin (ADM), a vasorelaxant peptide is produced and secreted by human retinal pigment epithelial (RPE) cells, whether ADM expression is regulated by inflammatory cytokines and a growth factor, and whether ADM has proliferative effects on these cells.


METHODS
Production and secretion of ADM by cultured human RPE cells were examined by Northern blot analysis and radioimmunoassay. Regulation of the ADM expression by basic fibroblast growth factor, interferon (IFN)-gamma, tumor necrosis factor-alpha, interleukin (IL)1beta, or all-trans-retinoic acid was studied. In addition, proliferative effects of ADM on human RPE cells were examined by modified 3-(4,5-dimetylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay.


RESULTS
ADM mRNA was expressed constitutively in all three human RPE cell lines (F-0202, D407, and ARPE-19) examined. Immunoreactive ADM was detected in the cultured media by radioimmunoassay. Sephadex G-50 column chromatography of the cultured medium showed a single peak eluting in the position of ADM-(1-52). Treatment with IFN-gamma or IL-beta increased ADM mRNA levels and immunoreactive-ADM levels in the medium in dose- and time-dependent manners in ARPE-19 cells. Exogenously added ADM increased the number of F-0202 cells and ARPE-19 cells, and the treatment with ADM antibody or ADM-(22-52) (an ADM antagonist) decreased it.


CONCLUSIONS
Human RPE cells produced and secreted ADM. IFN-gamma and IL-1beta induced ADM expression in ARPE-19 cells. Furthermore, ADM stimulated proliferation of RPE cells. These results raise the possibility that ADM is related to the pathophysiology of some inflammatory and proliferative ocular diseases.
Udono
T
T
Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Miyagi, Japan.
Takahashi
K
K
Nakayama
M
M
Murakami
O
O
Durlu
Y K
YK
Tamai
M
M
Shibahara
S
S
D053607:Adrenomedullin; D015152:Blotting, Northern; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002850:Chromatography, Gel; D016207:Cytokines / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D010455:Peptides / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D011863:Radioimmunoassay; D014212:Tretinoin / Q000494:pharmacology; D014665:Vasodilator Agents / Q000378:metabolism* / Q000494:pharmacology
D016207:Cytokines; D010455:Peptides; D012333:RNA, Messenger; D014665:Vasodilator Agents; D053607:Adrenomedullin; D014212:Tretinoin; D005346:Fibroblast Growth Factors