Short pulse laser induces less inflammatory cytokines in the murine retina after laser photocoagulation.

AIMS: The purpose of this study was to evaluate the effect of pulse duration on the expression of inflammatory cytokines in the murine retina after laser photocoagulation treatment with a PASCAL(®) pattern scan laser photocoagulator and conventional laser treatment. METHODS: Retinal scatter laser photocoagulation was performed on C57BL/6J mice using a short pulse (10 ms) with a PASCAL laser or conventional settings (100 ms) with a multicolor laser. Eyes were enucleated before treatment (control) and 1 day, 3 days and 7 days after treatment. The levels of inflammatory cytokines (i.e., VEGF, MCP-1, RANTES and IL-6) in the retina/choroid were quantified by an ELISA. The expression patterns of VEGF and macrophages (i.e., F4/80) in the retina/choroid were evaluated by immunohistochemistry. RESULTS: The levels of RANTES, IL-6 and MCP-1 after PASCAL and conventional laser treatments were significantly elevated compared with controls (p < 0.05). Conventional laser treatment, but not PASCAL treatment, resulted in the up-regulation of VEGF. RANTES and IL-6 levels on day 1 and MCP-1 levels on day 3 in the sensory retina were also significantly up-regulated with conventional laser treatment compared with PASCAL treatment (p < 0.05). Immunohistochemical analysis showed that PASCAL treatment was associated with lower VEGF and F4/80 expression levels compared with conventional laser treatment. CONCLUSIONS: Our data suggested that the short pulse duration induced fewer inflammatory cytokines in the sensory retina compared with the conventional pulse duration. Short pulse laser photocoagulation with the PASCAL may prevent macular edema after panretinal photocoagulation.

Efficient delivery of siRNA by atelocollagen in a murine laser-induced choroidal neovascularization model.

PURPOSE: Previous studies have shown that small interfering RNAs (siRNAs) could suppress angiogenesis via stimulation of toll-like receptor-3 (TLR3). The purpose of this study was to determine the efficacy of atelocollagen to deliver siRNA without TLR3 stimulation in the laser-induced choroidal neovascularization (CNV) model. METHODS: CNV was induced by laser injury in C57BL/6J mice and volumes were measured 7 days later. Nontargeted siRNA, 21-nucleotide (nt) siRNA-Luc (Luciferase) and 21-nt siRNA-Vegfa were injected into the vitreous following injury. Atelocollagen was incubated with naked 21-nt siRNAs before injection. To block TLR3 endosomal activity, chloroquine was injected intravitreously after laser injury. RESULTS: The mean CNV volumes were significantly smaller in the naked siRNA-Luc, naked siRNA-Vegfa, or siRNA-Vegfa/atelocollagen complex compared with PBS, atelocollagen or siRNA-Luc/atelocollagen complex-injected mice (p < 0.05). CONCLUSION: These findings demonstrate that atelocollagen may deliver siRNA without nonspecific TLR3 stimulation in the murine laser-CNV model.

Five-year follow-up of fundus autofluorescence and retinal sensitivity in the fellow eye in exudative age-related macular degeneration in Japan.

PURPOSE: To assess the 5-year change in abnormal fundus autofluorescence (FAF) patterns and retinal sensitivity in the fellow eye of Japanese patients with unilateral exudative age-related macular degeneration (AMD). METHODS: Patients with unilateral exudative AMD who developed abnormal FAF in the fellow eyes were enrolled. FAF imaging and microperimetry were performed at baseline and follow-ups. FAF findings were classified into 8 patterns based on the International Fundus Autofluorescence Classification Group to assess retinal sensitivity. Forty-five points covering the central 12 degrees on microperimetry were superimposed onto the FAF images. Each point was classified depending on the distance from the abnormal FAF. "Close" was defined as the portion within 1 degree from the border of any abnormal FAF, and "Distant" was defined as the portion over 1 degree from the border of abnormal FAF. To investigate the association between the retinal sensitivity and distance from the abnormal FAF, hierarchical linear mixed-effect models were used with the distance, time and time squared from baseline (months), and angle (degrees) as fixed effects. Differences among patients, eyes, and test point locations were considered successively nested random effects. RESULTS: We studied 66 fellow eyes with abnormal FAF. Twenty-seven eyes were followed-up during the 5 years. In the 13 of 27 eyes (48%), the abnormal FAF patterns had changed during the 5 years. We found retinal sensitivity was associated significantly with the distance from the abnormal FAF ("Distant": p<0.001, time2 from baseline: p<0.001, angle: p<0.001). The mean retinal sensitivity of the "Close" tended to deteriorate after the third year and eventually showed the similar sensitivity as the portion within the abnormal FAF. CONCLUSION: FAF patterns can change about half during the 5 years and the retinal sensitivity near abnormal FAF tends to deteriorate after the third year.

Fundus autofluorescence and retinal sensitivity in fellow eyes of age-related macular degeneration in Japan.

PURPOSE: Abnormal fundus autofluorescence (FAF) potentially precedes onset of late age-related macular degeneration (AMD) in Caucasian patients. Many differences exist between Asian and Caucasian patients regarding AMD types and severity, gender, and genetic backgrounds. We investigated the characteristics of abnormal FAF and retinal sensitivity in the fellow eyes of Japanese patients with unilateral neovascular AMD. METHODS: Sixty-six patients with unilateral neovascular AMD and abnormal FAF in the fellow eye were enrolled in this multicenter, prospective, observational study. The best-corrected visual acuity, fundus photographs, FAF images, and retinal sensitivity on microperimetry were measured periodically for 12 months. The FAF images were classified into eight patterns based on the International Fundus Autofluorescence Classification Group. The points measured by microperimetry were superimposed onto the FAF images and fundus photographs and classified as "within," "close," and "distant," based on the distance from the abnormal FAF and other findings. The relationship between the location of the baseline abnormal FAF and retinal sensitivity was investigated. RESULTS: In Japanese patients, patchy (33.3%) and focally increased (30.3%) patterns predominated in the abnormal FAF. Intermediate-to-large drusen was associated predominantly with hyperfluorescence and hypofluorescence. Neovascular AMD developed within 1 year in six (9.1%) eyes, the mean baseline retinal sensitivity of which was 12.8 ± 4.7 dB, significantly (p<0.002) lower than the other eyes. In 44 of the other 60 eyes, microperimetry was measurable at baseline and month 12 and the mean retinal sensitivity improved significantly from 13.5 ± 4.4 to 13.9 ± 4.8 dB (p<0.001), possibly associated with lifestyle changes (e.g., smoking cessation, antioxidant and zinc supplementation). The mean retinal sensitivities of points within and close to the abnormal FAF were 9.9 and 11.7 dB, respectively, which were significantly lower than the 14.0 dB of the points distant from the abnormal FAF. CONCLUSION: In Japanese patients, patchy and focally increased patterns predominated in the abnormal FAF. The retinal sensitivity was lower close to/within the abnormal FAF. FAF and microperimetry are useful to assess macular function before development of neovascular AMD or geographic atrophy.

Long-term retention of dye after indocyanine green-assisted internal limiting membrane peeling.

PURPOSE: To evaluate dye retention in the fundus after indocyanine green (ICG)-assisted internal limiting membrane peeling. METHODS: Ten eyes with stage 3 or 4 nondiabetic idiopathic macular hole (MH group) and six eyes with diffuse diabetic macular edema (DM group) were studied. The fundus was examined with 780-nm infrared illumination by a scanning laser ophthalmoscope (SLO) after ICG-assisted internal limiting membrane peeling. The postoperative follow-up period ranged from 6 to 12 months (mean+/-SD, 3.7+/-2.6 months). RESULTS: Fluorescence from ICG was detected in all studied eyes in both groups up to 6 months after surgery. At 9 months after surgery, ICG fluorescence was visible in all eyes of the DM group, but in only one-third of eyes of the MH group. No fluorescence was detected in fellow eyes that had not been operated on. CONCLUSION: The present study using SLO revealed that ICG remains in the fundus for over 6 months after surgery. The results also suggested that a longer time might be required for dye clearance from the diabetic retina than from the nondiabetic retina.

Retention of dye after indocyanine Green-assisted internal limiting membrane peeling.

PURPOSE: To describe the long-term retention of indocyanine green (ICG) in the fundus after ICG-assisted internal limiting membrane peeling. DESIGN: Case report. Two patients underwent vitrectomy including ICG-assisted internal limiting membrane peeling. The fundus was examined with a 780-nm infrared illumination of a scanning laser ophthalmoscope after surgery. RESULTS: No ICG staining of the fundus was visible ophthalmoscopically. Examination with a scanning laser ophthalmoscope, however, detected fluorescence from residual ICG until 6 months after surgery in case 1 and 9 months in case 2. No complication related to the residual ICG was observed. CONCLUSIONS: The results suggested that ICG remains in the fundus for a long period after surgery. Clearance of the dye from the diabetic retina may be prolonged.

Suppression of laser-induced choroidal neovascularization by a CCR3 antagonist.

PURPOSE: To evaluate the efficacy of a novel CCR3 antagonist for laser injury-induced choroidal neovascularization (CNV) in mice. METHODS: We evaluated YM-344031, a novel and selective small-molecule CCR3 antagonist. CNV was induced by laser injury in C57BL/6J mice, and its volume was measured after 7 days by confocal microscopy. Leakage from the CNV was also measured after 7 days by fluorescein angiography. The CCR3 antagonist was administered by gavage at 1 hour before and 1 day after the laser injury, or intravitreous injection immediately after the laser injury. After the laser injury, ELISA, Western blot analysis, and real-time RT-PCR for VEGF-A expression in the RPE/choroid, and immunohistochemistry for CCR3, CCL11, Ki67, and Rac1 was performed. RESULTS: Both oral administration and intravitreous injection of YM-344031 significantly suppressed the CNV volume (P < 0.0001 and P < 0.01, respectively). Pathologically significant leakage was significantly less common in YM-344031-injected mice (P < 0.0001). The mean VEGF protein level was significantly increased in vehicle-injected eyes after the laser injury (P < 0.05). Although the YM-344031-injected eyes did not show VEGF-A suppression after the laser injury, VEGF164 mRNA upregulation was significantly suppressed in YM-344031-injected mice (P < 0.05), and intravitreous injection of YM-344031 appeared to suppress CCR3, CCL11 (eotaxin), Ki67, and Rac1 expression after the laser injury. CONCLUSIONS: The present data suggest that the CCR3 antagonist YM-344031 can suppress CNV, via suppression of the upregulation of VEGF164 mRNA in VEGF isoform after the laser injury. Although our findings may warrant further investigation, YM-344031 may have potential as a new therapy for age-related macular degeneration.

Suppression of laser-induced choroidal neovascularization by nontargeted siRNA.

PURPOSE. To investigate the effect of nontargeted siRNAs on vascular leakage and vascular endothelial growth factor (VEGF)-A expression in the development of choroidal neovascularization (CNV). METHODS. Nontargeted siRNAs were 21-nt (nucleotides) siRNA-Luc (Luciferase) or 16-nt siRNA-Luc. Targeted 21-nt siRNA-Vegfa or phosphate-buffered saline (PBS) was used for comparison. Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice; 7 days later, vascular leakage was determined by fluorescein angiography, and CNV volumes were measured by confocal microscopy. Expression of VEGF-A in the retinal pigment epithelium (RPE)/choroid was quantified by ELISA 3 days after photocoagulation. RESULTS. Pathologically significant leakage developed in most of the 16nt-siRNA-Luc- or PBS-injected mice but in significantly fewer 21nt-siRNA-Luc- and 21nt-siRNA-Vegfa-injected mice (P = 0.0004, P = 0.0001, respectively). CNV volume in 21-nt siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes was significantly lower than in PBS-injected eyes (P = 0.0124, P = 0.0040, respectively). CNV volume was not suppressed by 16-nt siRNA-Luc injection (P = 0.7700). The mean VEGF protein level decreased significantly in the 21nt-siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes compared with PBS-injected eyes 3 days after laser photocoagulation (P = 0.0011, P = 0.0063, respectively). The 16nt-siRNA-Luc-injected eyes did not show VEGF-A suppression 3 days after laser photocoagulation (P = 0.3177). Between 21-nt siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes, there were no significant differences in CNV volume, the VEGF-A level, or pathologic leakage detected by fluorescein. CONCLUSIONS. These data suggest that nontarget 21nt-siRNA can suppress laser-induced choroidal neovascularization anatomically and functionally through VEGF suppression.