Effect of Phosphorylated-Extracellular Regulated Kinase 1/2 Inhibitor on Retina from Light-induced Photoreceptor Degeneration

Background: The demonstrated role of mitogen-activated protein kinase (MAPK) in both cell apoptosis and the inflammation pathway makes it an attractive target for photoreceptor protection. The aim of this study was to investigate the protective effects of MAPK antagonists against photoreceptor degeneration and retinal inflammation in a rat model of light-induced retinal degeneration. Methods:Sprague Dawley rats were treated with intravitreal injections of MAPK antagonists,inhibitors of p-P38,phosphorylated?extracellular regulated kinase (p-ERK) 1/2, and p-c-Jun N-terminal kinase (JNK) just before they were assigned to dark adaptation.After dark adaptation for 24 h, rats were exposed to blue light (2500 lux) in a light box for 24 h, and then returned to the normal 12-h light/12-h dark cycle. Samples were collected at different time points. MAPK expression during light exposure was examined with immunofluorescence. Photoreceptor death was detected with histopathology and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The expression of retinal p-ERK1/2, caspase 3, activated caspase 3, tumor necrosis factor (TNF)-α, and interleukin (IL)-1βwas examined by Western blotting. Differences between groups were evaluated using unpaired one-way analysis of variance and least significant difference post hoc tests. Results: MAPKs (P38, ERK1/2, and p-JNK) were phosphorylated and activated in the light injury groups, compared with normal group, and their expressions were mainly elevated in the outer nuclear layer (ONL). Among the selected MAPK antagonists, only the p-ERK1/2 inhibitor attenuated the loss of photoreceptors and the thinning of ONL in light injury groups. Besides, p-ERK1/2 inhibitor refrained light-induced photoreceptor apoptosis, which was presented by TUNELpositive cells. Light injury significantly increased the expression of p-ERK1/2 (1.12 ± 0.06 vs. 0.57 ± 0.08, t = 9.99, P < 0.05; 1.23 ± 0.03 vs. 0.57 ± 0.08, t = 11.90, P < 0.05; and 1.12 ± 0.12 vs. 0.57 ± 0.08, t = 9.86, P < 0.05; F = 49.55, P < 0.001), and induced caspase 3 activating (0.63 ± 0.06 vs. 0.14 ± 0.05, t = 13.67, P < 0.05; 0.74 ± 0.05 vs. 0.14 ± 0.05, t = 16.87, P < 0.05; and 0.80 ± 0.05 vs. 0.14 ± 0.05, t = 18.57, P < 0.05; F = 100.15, P < 0.001), compared with normal group. The p-ERK1/2 inhibitor significantly reduced p-ERK1/2 overexpression (0.61 ± 0.06 vs. 1.12 ± 0.06, t = -9.26, P < 0.05; 0.77 ± 0.06 vs. 1.23 ± 0.03, t = -8.29, P < 0.05; and 0.68 ± 0.03 vs. 1.12 ± 0.12, t = -7.83, P < 0.05; F = 49.55, P < 0.001) and downregulated caspase 3 activating (0.23 ± 0.04 vs. 0.63 ± 0.06, t = -11.24, P < 0.05; 0.43 ± 0.03 vs. 0.74 ± 0.05, t = -8.86, P < 0.05; and 0.58 ± 0.03 vs. 0.80 ± 0.05, t = -6.17, P < 0.05; F = 100.15, P < 0.001), compared with light injury group. No significant change in the total level of caspase 3 was seen in different groups (F = 0.56, P = 0.75). As for inflammation, light injury significantly increased the expression of TNF-α (0.42 ± 0.04 vs. 0.25 ± 0.05, t = 5.99, P < 0.05; 0.65 ± 0.03 vs. 0.25 ± 0.05, t = 14.87, P < 0.05; and 0.86 ± 0.04 vs. 0.25 ± 0.05, t = 22.58, P < 0.05; F = 160.27, P < 0.001) and IL-1β (0.24 ± 0.01 vs. 0.19 ± 0.02, t = 2.33, P < 0.05; 0.35 ± 0.02 vs. 0.19 ± 0.02, t = 7.97, P < 0.05; and 0.48 ± 0.04 vs. 0.19 ± 0.02, t = 14.69, P < 0.05; F = 77.29, P < 0.001), compared with normal group. P-ERK1/2 inhibitor significantly decreased the overexpression of TNF-α (0.22 ± 0.02 vs. 0.42 ± 0.04, t = -7.40, P < 0.05; 0.27 ± 0.02 vs. 0.65 ± 0.03, t = -14.27, P < 0.05; and 0.33 ± 0.03 vs. 0.86 ± 0.04, t = -19.58, P < 0.05; F = 160.27, P < 0.001) and IL?1β (0.13 ± 0.03 vs. 0.24 ± 0.01, t = -5.77, P < 0.05; 0.17 ± 0.01 vs. 0.22 ± 0.02, t = -9.18, P < 0.05; and 0.76 ± 0.05 vs. 0.48 ± 0.04, t = -13.12, P < 0.05; F = 77.29, P < 0.001), compared with light injury group.Conclusion: The p-ERK1/2 inhibitor might protect the retina from light-induced photoreceptor degeneration and retinal inflammation.

Pediatric Infectious Endophthalmitis： A 271-case Retrospective Study at a Single Center in China

Background： Pediatric infectious endophthalmitis is a serious sight-threatening disease for children. The purpose of this study was to investigate the etiology, microbiological spectrum, and visual outcomes of infectious endophthalmitis in children at a single institution in China. Methods： It is a retrospective study of the medical records of all patients under 14 years of age with histories of infectious endophthalmitis, treated at a single institution from January 1, 2009 to January 1, 2015. The clinical characteristics, etiology, microbiological spectrum, and management, as well as the visual outcomes, were analyzed. The Kappa test and Chi-square test were used in the statistical evaluation. Results： A total of 271 children were identified, with a mean age of 5.61 ± 2.93 years （range 5 months to 14 years）. Ocular trauma （94.8%） and previous ocular surgery （3.0%） were the most common etiologies. Overall, 147 （54.2%） cases had positive cultures, and 176 organisms were isolated from these patients. A single species was isolated in 120 （81.6%） cases, with multiple organisms in 27 （18.4%） cases, and the most commonly identified organisms were coagulase-negative Staphylococcus and Streptococcus species, comprising 29.5% and 26.8% of the isolates, respectively. Moreover, of 176 isolates, 142 （80.8%） were Gram-positive organisms, 23 （13.0%） were Gram-negative organisms, and 11 （6.2%） were fungi. The final visual outcomes were 20/200 or better in 66 （24.4%） eyes, counting fingers to 20/200 in 34 （12.5%）, hand motions in 30 （11.1%）, light perception in 33 （12.2%）, no light perception in 32 （11.8%）, and 9 （3.3%） eyes were enucleated or eviscerated. The visual outcomes were not available in 67 （24.7%） patients. Conclusions： Penetrating ocular trauma is the most frequent cause of pediatric endophthalmitis in China. Streptococcus and Staphylococcus species are the most commonly identified organisms in exogenous pediatric endophthalmitis whereas Fusarium species are commonly seen in endogenous endophthalmitis. In this research, in spite of aggressive management with antibiotics and vitrectomy, the visual prognosis was found to be generally poor.