Activated macrophages induce neovascularization through upregulation of MMP-9 and VEGF in rat corneas.
OBJECTIVE
To explore the mechanisms of activated macrophages (A-Mφ) involved in corneal angiogenesis.


METHODS
Activated macrophages were elicited by mineral oil lumbar injection and implanted into corneal micropockets in rats for the treatment group, A-Mφ, and phosphate-buffered saline group as control. Corneal changes were observed with a slit lamp microscope, and histopathological features were evaluated by immunofluorescence. Reverse transcription-polymerase chain reaction was used to detect the relative expression of angiogenesis-associated factors and inflammatory mediators in the activated macrophages and corneal tissue after implantation.


RESULTS
Immunofluorescence showed that peritoneal cells expressed antigens of cluster of differentiation 68 (CD68, ED1), matrix metalloproteinases-9 (MMP-9), and vascular endothelial growth factor (VEGF). Activated macrophages significantly induced corneal neovascularization (CNV), which peaked on day 5, whereas the control group and normal corneas showed less CNV. The activated macrophages and corneal tissue after implantation expressed the angiogenesis-related factors, such as cyclooxygenase-2, platelet-derived growth factor, transforming growth factor beta, interleukin-1 alpha, MMP-9, and VEGF in messenger RNA (mRNA). However, mRNA expression of MMP-9 and VEGF differed significantly only in the cornea between the A-Mφ group and phosphate-buffered saline group 5 days after the implantation. MMP-9 and VEGF expression of mRNA and protein was higher in the A-Mφ group than that in the control group and normal corneas.


CONCLUSIONS
Activated macrophages induce obvious CNV and related mechanisms, which may be correlated with MMP-9 and VEGF autocrine in activated macrophages and upregulation of MMP-9 and VEGF in corneal tissue.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Zhan-rong
ZR
Li
Yong-ping
YP
Li
Miao-li
ML
Lin
Wen-ru
WR
Su
Wen-Xin
WX
Zhang
Ying
Y
Zhang
Lin
L
Yao
Dan
D
Liang
D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D017690:Cell Transplantation; D003315:Cornea / Q000601:surgery; D016510:Corneal Neovascularization / Q000201:enzymology* / Q000209:etiology; D004195:Disease Models, Animal; D053331:Ectodysplasins / Q000235:genetics / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D008262:Macrophage Activation / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000502:physiology* / Q000637:transplantation; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; D053331:Ectodysplasins; D020780:Matrix Metalloproteinase 9; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C539355:CD68 protein, rat; D000097382:CD68 Molecule; C467498:vascular endothelial growth factor A, rat; C572337:Mmp9 protein, rat