VEGF receptor blockade markedly reduces retinal microglia/macrophage infiltration into laser-induced CNV.

Although blocking VEGF has a positive effect in wet age-related macular degeneration (AMD), the effect of blocking its receptors remains unclear. This was an investigation of the effect of VEGF receptor (VEGFR) 1 and/or 2 blockade on retinal microglia/macrophage infiltration in laser-induced choroidal neovascularization (CNV), a model of wet AMD. CNV lesions were isolated by laser capture microdissection at 3, 7, and 14 days after laser and analyzed by RT-PCR and immunofluorescence staining for mRNA and protein expression, respectively. Neutralizing antibodies for VEGFR1 or R2 and the microglia inhibitor minocycline were injected intraperitoneally (IP). Anti-CD11b, CD45 and Iba1 antibodies were used to confirm the cell identity of retinal microglia/macrophage, in the RPE/choroidal flat mounts or retinal cross sections. CD11b(+), CD45(+) or Iba1(+) cells were counted. mRNA of VEGFR1 and its three ligands, PlGF, VEGF-A (VEGF) and VEGF-B, were expressed at all stages, but VEGFR2 were detected only in the late stage. PlGF and VEGF proteins were expressed at 3 and 7 days after laser. Anti-VEGFR1 (MF1) delivered IP 3 days after laser inhibited infiltration of leukocyte populations, largely retinal microglia/macrophage to CNV, while anti-VEGFR2 (DC101) had no effect. At 14 days after laser, both MF1 and DC101 antibodies markedly inhibited retinal microglia/macrophage infiltration into CNV. Therefore, VEGFR1 and R2 play differential roles in the pathogenesis of CNV: VEGFR1 plays a dominant role at 3 days after laser; but both receptors play pivotal roles at 14 days after laser. In vivo imaging demonstrated accumulation of GFP-expressing microglia into CNV in both CX3CR1(gfp/gfp) and CX3CR1(gfp/+) mice. Minocycline treatment caused a significant increase in lectin(+) cells in the sub-retinal space anterior to CNV and a decrease in dextran-perfused neovessels compared to controls. Targeting the chemoattractant molecules that regulate trafficking of retinal microglia/macrophage appears to be a compelling therapeutic strategy to control CNV and treat wet AMD.

Parstatin suppresses ocular neovascularization and inflammation.

PURPOSE: Parstatin is a 41-mer peptide formed by proteolytic cleavage on activation of the PAR1 receptor. The authors recently showed that parstatin is a potent inhibitor of angiogenesis. The purpose of the present study was to evaluate the therapeutic effect of parstatin on ocular neovascularization. METHODS: Choroidal neovascularization was generated in mice using laser-induced rupture of Bruch's membrane and was assessed after 14 days after perfusion of FITC-dextran. Oxygen-induced retinal neovascularization was established in neonatal mice by exposing them to 75% O(2) at postnatal day (P)7 for 5 days and then placing them in room air for 5 days. Evaluation was performed on P17 after staining with anti-mouse PECAM-1. The effect of parstatin was tested after intravitreal administration. The effects of subconjunctival-injected parstatin on corneal neovascularization and inflammation in rats were assessed 7 days after chemical burn-induced corneal neovascularization. Retinal leukostasis in mice was assessed after perfusion with FITC-conjugated concanavalin A. RESULTS: Parstatin potently inhibited choroidal neovascularization with an IC(50) of approximately 3 µg and a maximum inhibition of 59% at 10 µg. Parstatin suppressed retinal neovascularization with maximum inhibition of 60% at 3 µg. Ten-microgram and 30-µg doses appeared to be toxic to the neonatal retina. Subconjunctival parstatin inhibited corneal neovascularization, with 200 µg the most effective dose (59% inhibition). In addition, parstatin significantly inhibited corneal inflammation and VEGF-induced retinal leukostasis. In all models tested, scrambled parstatin was without any significant effect. CONCLUSIONS: Parstatin is a potent antiangiogenic agent of ocular neovascularization and may have clinical potential in the treatment of angiogenesis-related ocular disorders.

[Construction of the stable expression system of NIH3T3 fibroblast with pcDNA3.1(-)-hTGFbeta3 and the study on the proliferation of the system fibroblasts].

OBJECTIVE: To construct and identify the stable expression system of NIH3T3 fibroblast with eukaryotic expression vector of human transforming growth factor beta3 (pcDNA3.1 (-)/TGFbeta3). So as to investigate the proliferation of NIH3T3 fibroblasts transfected with hTGFbeta3 gene stably. METHODS: The stable transfection of NIH3T3 fibroblasts with recombinant plasmid expressing hTGFbeta3 was established by using LipofectamineTM2000 and G418 selection. The mRNA and protein expression of TGFbeta3 were detected by the RT-PCR and Western blot method, respectively. Microscope and MTT were adopted to examine the proliferation of the stable expression system of fibroblasts with hTGFbeta3. RESULTS: After G418 selection, RT-PCR and Western blot analysis, 7 out of 10 cell lines transfected with pcDNA3.1 (-)/TGFbeta3 expressed with very high level of TGFbeta3, as compared with vector control transfectants that showed no expression, and compared with the other cell lines that expressed relatively low level. The stable transfection of NIH3T3 fibroblasts growth slowed down significantly (P < 0.05). CONCLUSION: The stable expression system of NIH3T3 fibroblast with hTGFbeta3 were constructed successfully. The TGFbeta3 gene could inhibit the proliferation of NIH3T3 fibroblasts in vitro.

Activation of microglia and chemokines in light-induced retinal degeneration.

PURPOSE: Microglial cells, which are activated and recruited by chemokines, have been shown to play crucial roles in neuronal degenerations of the central nervous system (CNS). This study investigated the activation and migration of retinal microglial cells and expression of chemokines in retinas in light-induced photoreceptor degeneration in mice. METHODS: Ninety-five Balb/cJ mice were kept in cyclic light for 1 week followed by dark adaptation for 48 h prior to light exposure of 3 h at 3.5 Klux. Animals were enthuanized at various times after light exposure. Terminal deoxynucleotidyl transferase-mediated dUTP nick end label (TUNEL) assay, rat-anti-mouse CD11b and 5D4 antibodies, isolectin-B4, and a chemokine-specific gene array were used to detect DNA fragmentation during retinal degeneration, to label retinal microglial cells, and to determine the expression of retinal chemokines and chemokine receptors, respectively. Reverse-transcriptase coupled polymerase chain reactions (RT-PCRs) were conducted on selected chemokine mRNAs to confirm the gene array findings. RESULTS: After intense light exposure, TUNEL-positive cells were noted in the outer nuclear layer (ONL) of the retina at 3 h, and their presence were noticeably increased at 1 day but declined at 3 days and 7 days after light exposure. In contrast, CD11b- or isolectin-B4-positive cells were seen in the ONL as early as 6 h and their presence increased significantly at 1 day and 3 days after light exposure. These cells displayed a round or ovoid morphology at 6 h and 1 day but assumed a more ameboid configuration at 3 days. By 7 day, the number of the microglial cells declined in the ONL and they became ramified, and were present mostly in the subretinal space. 5D4-positive cells with large cell bodies were only noted at 3 day and 7 day but not earlier. With chemokine-specific gene array analysis, we identified four chemokines and two chemokine receptors showing significant increases in their gene expressions. Among them, monocyte chemoattractant protein-3 (MCP-3), showed a remarkable 4.4 fold increase in its gene expression. RT-PCR confirmed a marked increase of MCP-3 expression in retinas at 3 h to 1 day, and a return to normal at 3 days following light injury. CONCLUSIONS: Retinal chemokines such as MCP-3 and their receptors are involved in the activation and migration of retinal microglia in light-induced retinal degeneration, which in turn modulate the apoptotic loss of photoreceptor cells in the outer retina.