Editor's Choice——Retinal ganglion cell damage and regeneration

Retinal ganglion cell apoptosis is considered to be the main cause of loss of vision in glaucoma patients. Microglia cells are phagocytic cells present in the retina. In the retina of glaucoma rat models, microglia cells become activated, which suggests a role for microglia in the pathogenesis of optic nerve injury in glaucoma patients. The retinal ganglion cell is the only cell that can produce action potential in the retina,

Experimental model of photo-oxidative damage

Background:Retinal degeneration is a common feature of several retinal diseases,such as retinitis pigmentosa and age-related macular degeneration(AMD).In this respect,experimental models of photo-oxidative damage reproduce faithfully photoreceptor loss and many pathophysiological events involved in the activation of retinal cell degeneration.Therefore,such models represent a useful tool to study the mechanisms related to cell death.Their advantage consists in the possibility of modulating the severity of damage according to the needs of the experimenter.Indeed,bright light exposure could be regulated in both time and intensity to trigger a burst of apoptosis in photoreceptors,allowing the study of degenerative mechanisms in a controlled fashion,compared to the progressive and slower rate of death in other genetic models of photoreceptor degeneration.Methods:Here,an exemplificative protocol of bright light exposure in albino rat is described,as well as the main outcomes in retinal function,photoreceptor death,oxidative stress,and inflammation,which characterize this model and reproduce the main features of retinal degeneration diseases.Discussion:Models of photo-oxidative damage represent a useful tool to study the mechanisms responsible for photoreceptor degeneration.In this respect,it is important to adapt the exposure paradigm to the experimental needs,and the wide range of variables and limitations influencing the final outcomes should be considered to achieve proper results.Trial Registration:None.

Protective effects of a novel drug RC28-E blocking both VEGF and FGF2 on early diabetic rat retina

AIM： To investigate protective effects of a novel recombinant decoy receptor drug RC28-E on retinal damage in early diabetic rats. METHODS： The streptozotocin （STZ）-induced diabetic rats were randomly divided into 6 groups： diabetes mellitus （DM） group （saline, 3 μL/eye）; RC28-E at low （0.33 μg/μL, 3 μL）, medium （1 μg/μL, 3 μL）, and high （3 μg/μL, 3 μL） dose groups; vascular endothelial growth factor （VEGF） Trap group （1 μg/μL, 3 μL）; fibroblast growth factor （FGF） Trap group （1 μg/μL, 3 μL）. Normal control group was included. At week 1 and 4 following diabetic induction, the rats were intravitreally injected with the corresponding solutions. At week 6 following the induction, apoptosis in retinal vessels was detected by TUNEL staining. Glial fibrillary acidic protein （GFAP） expression was examined by immunofluorescence. Blood-retinal barrier （BRB） breakdown was assessed by Evans blue assay. Ultrastructural changes in choroidal and retinal vessels were analyzed by transmission electron microscopy （TEM）. Content of VEGF and FGF proteins in retina was measured by enzyme linked immunosorbent assay （ELISA）. The retinal expression of intercellular cell adhesion molecule-1 （ICAM-1）, tumor necrosis factor-α （TNF-α）, VEGF and FGF genes was examined by quantitative polymerase chain reaction （qPCR）. RESULTS： TUNEL staining showed that the aberrantly increased apoptotic cells death in diabetic retinal vascular network was significantly reduced by treatments of medium and high dose RC28-E, VEGF Trap, and FGF Trap （all P〈0.05）, the effects of medium and high dose RC28-E or FGF Trap were greater than VEGF Trap （P〈0.01）. GFAP staining suggested that reactive gliosis was substantially inhibited in all RC28-E and VEGF Trap groups, but the inhibition in FGF Trap group was not as prominent. Evans blue assay demonstrated that only high dose RC28-E could significantly reduce vascular leakage in early diabetic retina （P〈0.01）. TEM revealed that the ultrastructures in choroidal and retinal vessels were damaged in early diabetic retina, which was ameliorated to differential extents by each drug. The expression of VEGF and FGF2 proteins was significantly upregulated in early diabetic retina, and normalized by RC28-E at all dosages and by the corresponding Traps. The upregulation of ICAM-1 and TNF-α in diabetic retina was substantially suppressed by RC28-E and positive control drugs. CONCLUSION： Dual blockade of VEGF and FGF2 by RC28-E generates remarkable protective effects, including anti-apoptosis, anti-gliosis, anti-leakage, and improving ultrastructures and proinflammatory microenvironment, in early diabetic retina, thereby supporting further development of RC28-E into a novel and effective drug to diabetic retinopathy （DR）.

Efficacy of granulocyte-colony stimulating factor treatment in a rat model of anterior ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy （NA-AION） is the most common cause of acute ischemic damage to the optic nerve （ON）, and the leading cause of seriously impaired vision in people over 55 years of age. It demonstrated that subcutaneous administration of Granulocyte colony-stimulating factor （G-CSF） reduces RGC death in an ON crush model in rats, and that the neuroprotective effects may involve both anti-apoptotic and anti-inflammatory processes. Our recent work shows that the protective actions of G-CSF in rAION models may involve both anti-apoptotic and anti-inflammatory processes. However, the exact rescuing mech- anisms involved in the administration of G-CSF in rAION models need further investigation. In addition, further studies on the administration of G-CSF at different time intervals after the induction of rAION may be able to illustrate whether treatment given at a later time is still neu- roprotective. Further, it is unknown whether treatment using G-CSF combined with other drugs will result in a synergistic effect in a rAION model. Inflammation induced by ischemia plays an essential role on the ON head in NA-A1ON, which can result in disc edema and compartment changes. Therefore, it is reasonable that adding an anti-inflammatory drug may enhance the therapeutic effects of G-CSF. An ongoing goal is to evaluate the novel sites of action of both G-CSF and other anti-inflammatory drugs, and to identify the functionally protective pathways to enhance RGC survival. These investigations may open up new therapeutic avenues for the treatment of ischemic optic neuropathy.

AB001. Vision impairment & repairment in diabetes

With the development of global industrialization,urbanization and changes of people’s lifestyle,Diabetes Mellitus,DM has become a serious worldwide health issue.The prevalence of diabetes in China is more than 10%.Due to the huge population base,China has surpassed the U.S.and India,becoming the country with the largest diabetic population in the world.Diabetic retinopathy(DR)is one of the most common complications of DM.The latest epidemiological survey shows that 17.8-29.2%of China’s diabetes patients developed DR,and it has become the leading cause of blindness in adults over the age of 40.Despite the continued emergence of new medicine and treatment in the past ten years,and a large number of global clinical trials have been carried out,we still couldn’t prevent the occurrence and development of DR.Microvascular damage caused by DM has been a top priority in the prevention and treatment of diabetic complications.Chinese government attaches great importance to the prevention and treatment of DR and has included it into China’s plan of the prevention and treatment of blindness.In this presentation,I’m going to focus on the pathogenesis of DR,especially the relationship between immune inflammatory response and DR.Major challenges and solutions in clinical treatment were discussed as well.