[Effects of mechanical stress on expressions of monocyte chemoattractant protein-1 and interleukin-8 of cultured human retinal pigment epithelial cells].
OBJECTIVE
To investigate the expressions of monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) of cultured human retinal pigment epithelial (hRPE) cells under mechanical stress in vitro, so as to mimic and understand the role of these 2 inflammatory cytokines in the early stage of development of primary retinal detachment.


METHODS
Ferric oxide beads coated with collagen were added to the culture plate containing wall-attaching hRPE cells and then the cells were incubated and washed to remove the unbound beads. A magnet was put to the culture plate to provide vertical magnetic force. Cytochalasin D (CD) was added to the culture fluid to inhibit the phagocytizing, secreting, and moving functions of the hRPE. Before the experiment and 15 min, 0.5 h, 1 h, 4 h, and 8 h the beginning of experiment, the MCP-1 mRNA and IL-8 mRNA in the hRPE cells were measured with reverse transcriptase polymerse chain reaction (RT-PCR), and the MCP-1 and IL-8 protein expression in the supernatants was tested with enzyme-linked immunosorbent assay (ELISA) kits.


RESULTS
MCP-1 and IL-8 mRNA were expressed at very low levels in the RPE cells and supernatant not exposed to magnetic force. After exposure to magnetic force, both MCP-1 and IL-8 mRNA demonstrated "double peaks" expression. Their first peak levels appeared within 0.5 h, being 3.30 ng/L +/- 0.12 ng/L and 1.88 ng/L +/- 0.08 ng/L respectively. The first peaks of MCP-1 and IL-8 protein expression were within 1 h, being 552.05 ng/L +/- 7.64 ng/Land 236.67 ng/L +/- 14.30 ng/L respectively, and the second peaks appeared about 4 hours later. After cytochalasin D pretreated, the expression and secretion of both MCP-1 and IL-8 of the hRPE cells were significantly decreased to the levels of 2.36 ng/L +/- 0.27 ng/L and 1.64 ng/L +/- 0.08 ng/L, and 353.80 ng/L +/- 16.68 ng/L and 101.86 ng/L +/- 15.92 ng/L respectively.


CONCLUSIONS
Mechanical stress induces the RPE cells to express MCP-1 and IL-8, and this effect was inhibited in part by pretreatment of CD, indicating that the cytoskeleton may be involved in the effect and that these two inflammatory cytokines take a part in the early stage of development of primary retinal detachment.
Zhang
Xiao-guang
XG
Eye Institute of the People's Liberation Army, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
Hui
Yan-nian
YN
Han
Quan-hong
QH
Hou
Xu
X
Chen
Li-jun
LJ
Ma
Ji-xian
JX
D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D008280:Magnetics; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013314:Stress, Mechanical
D018932:Chemokine CCL2; D016209:Interleukin-8; D012333:RNA, Messenger