Autocrine CCL2, CXCL4, CXCL9 and CXCL10 signal in retinal endothelial cells and are enhanced in diabetic retinopathy.
This study aimed at examining the presence and role of chemokines (angiogenic CCL2/MCP-1 and angiostatic CXCL4/PF-4, CXCL9/Mig, CXCL10/IP-10) in proliferative diabetic retinopathy (PDR). Regulated chemokine production in human retinal microvascular cells (HRMEC) and chemokine levels in vitreous samples from 40 PDR and 29 non-diabetic patients were analyzed. MCP-1, PF-4, Mig, IP-10 and VEGF levels in vitreous fluid from PDR patients were significantly higher than in controls. Except for IP-10, cytokine levels were significantly higher in PDR with active neovascularization and PDR without traction retinal detachment (TRD) than those in inactive PDR, PDR with TRD and control subjects. Exploratory regression analysis identified associations between higher levels of IP-10 and inactive PDR and PDR with TRD. VEGF levels correlated positively with MCP-1 and IP-10. Significant positive correlations were observed between MCP-1 and IP-10 levels. In line with these clinical findings Western blot analysis revealed increased PF-4 expression in diabetic rat retinas. HRMEC produced MCP-1, Mig and IP-10 after stimulation with IFN-γ, IL-1β or lipopolysaccharide. IFN-γ synergistically enhanced Mig and IP-10 production in response to IL-1β or lipopolysaccharide. MCP-1 was produced by HRMEC in response to VEGF treatment and activated HRMEC via the ERK and Akt/PKB pathway. On the other hand, phosphorylation of ERK induced by VEGF and MCP-1 was inhibited by PF-4, Mig and IP-10. In accordance with inhibition of angiogenic signal transduction pathways, PF-4 inhibited in vitro migration of HRMEC. Thus, regulatory roles for chemokines in PDR were demonstrated. In particular, IP-10 might be associated with the resolution of active PDR and the development of TRD.
Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh 11411, Saudi Arabia.
M I
MI
Nawaz
K
K
Van Raemdonck
G
G
Mohammad
D
D
Kangave
J
J
Van Damme
A M
AM
Abu El-Asrar
S
S
Struyf
D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism*; D054357:Chemokine CXCL10 / Q000378:metabolism*; D054370:Chemokine CXCL9 / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008297:Male; D055806:Microvessels / Q000166:cytology / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology; D010978:Platelet Factor 4 / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012171:Retinal Vessels / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism / Q000494:pharmacology; D014822:Vitreous Body / Q000378:metabolism
C111835:CCL2 protein, human; C114753:CXCL10 protein, human; C080810:CXCL9 protein, human; C505723:CXCL9 protein, rat; C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D054357:Chemokine CXCL10; D054370:Chemokine CXCL9; C091326:Cxcl10 protein, rat; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D010978:Platelet Factor 4