ABSTRACT
Objective To compare the pharmacodynamics between different batches of recombinant decoy receptor innovative drug RC28-E1 and RC28-E2 in retinal angiogenesis and neovascularization,and analyze its mechanism.Methods Sixty postnatal Day 4 (P4) C57BL/6J mice were randomly divided into normal control group,vascular endothelial growth factor (VEGF)+fibroblast growth factor 2 (FGF2) group,VEGF+FGF2+RC28-E1 group,VEGF+FGF2+RC28-E2 group,VEGF+FGF2+conbercept group and VEGF+FGF2+FGF trap group by using a random number table,with 10 mice in each group.The mouse retinal explant culture system was established,and stimulated with the corresponding factors and drugs prepared in the starving culture media.The normal controls were treated with the starving media.Then the retinal explants were stained with Isolectin B4 and imaged.The number of filopodia per vascular length was quantified.In addition,ninety-six P7 C57BL/6J mice were randomly divided into normal control group,oxygen-induced retinopathy (OIR) model control group,OIR + RC28-E1 group,OIR + RC28-E2 group,OIR+conbercept group and OIR+FGF trap group by using a random number table,with 16 mice in each group.The normal controls were raised under normoxia for 10 days,and the rest of the groups were raised under hyperoxia for 5 days,then returned to normoxia for another 5 days.On P17,the retinas were isolated and stained with Isolectin B4.The stained retinas were mountedon the slides and photographed.The relative vessel obliteration and neovascularization in retina were analyzed with computer software.Then the protein levels of VEGF and FGF2 were examined by Western blot in the retinas of each group in the OIR experiment.Finally,in the RF/6A cells stimulated with VEGF and FGF2,the activities of the signaling pathways,including MEK-extracellular regulated protein kinases (Erk),protein kinase C (PKC) and protein kinase B (Akt) pathways,were examined by Western blot.All experimental procedures were evaluated and approved by the Institutional Animal Care and Use Committee of Tianjin Medical University (SYXK 2009-0001),and were in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.Results The results of retinal explant cultures showed that the numbers of filopodia per vascular length in VEGF + FGF2 + RC28-E1,VEGF + FGF2 + RC28-E2,VEGF + FGF2 + conbcrcept,and VEGF+FGF2+FGF trap groups were all significantly less than that in the VEGF+FGF2 group (all at P ＜ 0.001).The filopodia number in retinal vascular front in RC28-E1 group was similar to that in the RC28-E2 group (P =0.15),whereas the filopodia numbers in both groups were significantly decreased as compared to those in VEGF+ FGF2+conbercept group and VEGF+FGF2+FGF trap group (all at P＜0.001).The results from the OIR mouse model showed that the relative vessel obliteration area in OIR model control group was dramatically higher than those in the drug intervention groups (all at P＜0.05).There was no statistical significance in the relative vessel obliteration area between OIR+RC28-E1 group and OIR+RC28-E2 group (P =0.17),while the obliteration areas in both RC28-E-intervened groups were significantly lower than those in the OIR+conbercept group and OIR+FGF trap group (all at P＜0.05).The relative neovascular pixels in the intervention groups were significantly lower than those in the OIR model control group (all at P＜0.001).The neovascular pixels in OIR+RC28-E1 group were significantly lower than those in VEGF+FGF2+conbercept group and VEGF + FGF2 + FGF trap group (both at P ＜ 0.05),but comparable to those in OIR+RC28-E2 group (P =0.39).Western blot result showed that,the protein expression of VEGF and FGF2 in the OIR mouse retinas were significantly upregulated compared to those in the normal ones (both at P＜0.001).The upregulation of both genes were normalized by both RC28-E1 and RC28-E2.In addition,the stimulation of VEGF and FGF2 induced an enhanced activity in MEK-Erk pathway in RF/6A cells,whereas RC28-E1 inhibited the overactivation.Conclusions RC28-E1 and RC28-E2 both can inhibit angiogenesis in the retinal explants isolated from neonatal mice;they also reduce vessel obliteration and mitigate neovascularization in the OIR mouse model.Therefore,the pharmacology batch and pilot test batch of RC28-E have similar efficacies and reliable stability,and are superior in the anti-angiogenic and anti-neovascular efficacy to the currently clinically available drugs conbercept and FGF trap.RC28-E1 may suppress pathological neovascularization through inhibiting the overactivation of MEK-Erk pathway in retinal vascular endothelial cells.
ABSTRACT
Background Reasearches showed that α-melanocyte-stimulating hormone (α-MSH) inhibits inflammation and ameliorates the ocular surface abnormalities in a scopolamine-induced dry eye rat model,and the managing effect of sodium carboxymethylcellulose (CMC) on dry eyes also has been determined.However,whether α-MSH can enhance the therapeutic effects of CMC remains to be investigated.Objective This study was to investigate the protective effects of α-MSH combined with CMC on ocular surface in a scopolamine-induced dry eye rat model.Methods Sixty clean female Wistar rats were randomly divided into normal control group,model control group,NaCl group,CMC group,α-MSH group and α-MSH+CMC group,and 10 rats for each group.The dry eye models were established by subcutaneous injection of scopolamine hydrobromide at 9:00,12:00,15:00 and 18:00 per day for 28 days.0.9％ NaCl solution,1×10 3 mg/ml α-MSH solution,0.5％ CMC eye drop,and 1 ×10-3 mg/ml α-MSH+0.5％ CMC solution were topically administered twice a day (8:00,17:00) since the initial day of modeling according to grouping.Shirmer Ⅰ test (S Ⅰ t),breakup time of tear film (BUT) and corneal fluorescence staining were performed before and 7,14,21,28 days after the application of drugs.At 28 days following the administration of drugs,the eyeballs of the rats were collected.Hemotoxylin and eosin staining was employed to examine the morphology of corneas,and periodic acid schiff (PAS) staining was used to count the conjunctival goblet cells.This study protocol was approved by Experimental Animal Ethic Committee of Tianjin Medical University (SYXK 2009-0001),and the use and care of the rats complied with ARVO Statement.Results The S Ⅰ t and BUT values were significantly reduced,and the corneal fluorescence staining scores were significantly increased over time following modeling in the model control group (all at P＜0.01).No significant differences were found in the S Ⅰ t,BUT and corneal fluorescence staining scores between model control group and NaCl group at various time points (all at P＞0.05).At 7,14 and 21 days after intervention,the S Ⅰ t values were (4.800±0.789),(4.100±0.516) and (4.300±0.856) mm in the α-MSH+CMC group,which were considerably higher than (2.875 ±0.719),(2.375 ±0.619) and (2.532±0.957)mm in the NaCl group (all at P＜0.01).At 7 days after intervention,the BUT values were (4.938± 1.843) seconds and (5.000±1.491) seconds in the α-MSH group and α-MSH+CMC group,which were significantly higher than (3.250±1.000) seconds in the NaCl group (both at P＜0.01).The corneal fluorescence staining scores in the CMC group,α-MSH group and α-MSH+CMC group were significantly lower than that in the NaCl group,with the lowest score in the α-MSH +CMC group (all at P＜0.05).The thickening of corneal epithelial layer,corneal edema and arrangement disorder of corneal stroma were found in the model control group and NaCl group;while slight corneal edema and epithelial cell proliferation were exhibited in the α-MSH+CMC group by hemotoxylin and eosin staining.PAS staining showed that the number of goblet cells was much more in the CMC group,α-MSH group and α-MSH+ CMC group than that in the model control group and NaCl group (all at P ＜ 0.01).Conclusions The sole application of α-MSH or CMC alleviates ocular surface damage and morphological abnormality to certain extent,and the combination of α-MSH and CMC generates more effective protection in comparison with sole administration of α-MSH or CMC.The early application of the drugs plays an improvement role in tear secretion and tear film stability in dry eyes.