Adeno-associated viral vector (AAV) is the most important viral tool and has been widely used in gene therapy. Because of its small size, non-enveloped, non-pathogenic and other characteristics, so it is one of the main means to treat hereditary retinal diseases. Aiming at MERTK for retinitis pigmentosa, ND4 for Leber hereditary optic neuropathy or RPE1 for choroideremia, AAV gene therapy improved half patients’ visual acuity in clinic tests. Besides, there are some clinic tests in progress for Leber’s congenital amaurosis, X-linked retinoschisis, Achromatopsia, age-related macular degeneration. But more researches need to be found before clinic test for Stargardt disease, Usher syndrome and nanophthalmos. At present, AAV gene therapy is mainly used for recessive hereditary retinal diseases, and technology is needed to intervene for dominant retinal diseases. For the treatment of hereditary retinal diseases, this will be an important and complex systematic project, which requires more human and material resources to participate in and study together, and we expect to have a great breakthrough in the near future.
ObjectiveTo investigate the protective effects of different concentrations of chloroquine on RGC in n-methyl-d-aspartate (NMDA) injured mice and its possible mechanisms.MethodsFifty-four healthy male C57/BL6 mice were randomly divided into three groups, 18 in each group. The mice in low-dose chloroquine group were intraperitoneally injected with chloroquine solution at a dose of 10 mg/kg daily. Mice in high-dose chloroquine group were intraperitoneally injected with chloroquine solution at a dose of 100 mg/kg, and the mice in control group were intraperitoneally injected with the same volume of PBS. NMDA intravitreal injection was performed 2 days after intraperitoneal injection, 5 nmoles NMDA was injected into the left eye, and the same volume of PBS was injected into the right eye as a control. The RGC staining of retinal plaques were performed 7 days after NMDA injection, and the number of alive RGC was calculated. The visual acuity and electroretinogram were used to evaluate the electrophysiological functions of RGC at 9 and 10 days after modeling. Real-time quantitative PCR and retinal frozen sections and glial fibrillary acidic protein (GFAP) immunofluorescence staining were performed 11 days after NMDA injection to evaluate the glial activation of the retina. The density, visual acuity, and the amplitude of PhNR-wave of RGC between groups were compared by one-way analysis of variance.ResultsAt 7 days after NMDA injection, the density of RGC in retinal patch of low-dose chloroquine group was significantly higher than that of intraperitoneal injection of PBS control group (F=54.41, P＜0.01). The density of RGC in retinal patch of high-dose chloroquine group was lower than that of control group (F=1.18, P＞0.05). The visual acuity was higher than control group, and the difference was statistically significant (F=9.10, P＜0.05). The amplitude of PhNR-wave was significantly higher in low-dose chloroquine group than that of the control group (F=17.60, P＜0.01). The mRNA level of inflammatory factor and GFAP positive signal was also significantly lower than that of the control group (F=23.66, P＜0.05). The amplitude of PhNR-wave, the expression of GFAP (F=110.20, P＜0.01) and the mRNA level of inflammatory factors (F=167.60, 17.78; P＜0.01) in the high-dose chloroquine group were higher than the other two groups, and the differences were statistically significant.ConclusionsIn NMDA injury retinal model, low-dose chloroquine significantly increased the survival and physiological function of RGC, and the mechanism may be related to the inhibition of glial activation and inflammatory response. High-dose of chloroquine would aggravate the apoptosis of RGC.
ObjectiveTo explore the light sensitivity and kinetic of the new optogenetics tools Channelrhodopsin-XXM2.0 (XXM2.0) and Channelrhodopsin-PsCatCh2.0 (PsCatCh2.0), and analyze whether they could be used to restore the visual function by optogenetics.MethodsMolecular biology techniques were used to link the gene fragments of XXM2.0 and PsCatCh2.0 to the vector pCIG(c)-msFoxn3 containing ampicillin resistant screening gene and reporter gene to form new plasmid pCIG(c)-msFoxn3-XXM2.0 and pCIG(c)-msFoxn3-PsCatCh2.0. The constructed plasmids were transfected into HEK 293T cells, and light responses were recorded in the whole cell mode with the HEKA patch clamp system. The photocurrent was recorded under three light intensity included 2.7×1016, 4.7×1015, and 6.4×1014 photons/(cm2·s). And then, XXM2.0 and PsCatCh2.0 were stimulated with 2.7×1016 photons/(cm2·s) and fully recovered. The opening and closing time constants were analyzed with Clampfit 10.6 software. At the same light intensity, photocurrents of XXM2.0 and PsCatCh2.0 were recorded by the light pulse stimulating of 2-32 Hz. The current attenuation was analyzed at long intervals of 4000 ms and short intervals of 200 ms after repeated stimulation. Comparisons between groups were performed by independent samples t test.ResultsRestriction endonuclease sites of EcoRⅠ and EcoRⅤ were successfully introduced at XXM2.0 and PsCatCh2.0 sequences. When the digestion was completed, they were ligated by T4 DNA ligase to construct new plasmids pCIG(c)-msFoxn3-XXM2.0 and pCIG (c)-msFoxn3-PsCatCh2.0, and then transfected on HEK 293T cells. The light intensity dependence was showed in XXM2.0 and PsCatCh2.0. The greater light intensity was accompanied by the greater photocurrent. Under the light intensity 6.4×1014 photons/(cm2·s) below the retinal safety threshold, large photocurrent was still generated in XXM2.0 and PsCatCh2.0 with 92.8±142.0 and 13.9±5.6 pA (t=1.24, 1.24; P=0.28, 0.29). The opening time constants of XXM2.0 and PsCatCh2.0 were 23.9±6.7 and 2.4±0.8 ms, and the closing time constants were 5803.0±568.2 and 219.9±25.6 ms. Compared with PsCatCh2.0, the opening and closing time constant of XXM2.0 were both larger than PsCatCh2.0. The differences were statistically significant (t=7.10, 31.60; P=0.00, 0.00). In terms of response frequency, XXM2.0 and PsCatCh2.0 could follow to 32 Hz high-frequency pulsed light stimulation, and all could respond to repeated light stimulation at a long (4000 ms) and a short time (200 ms) interval with the small current decay rate.ConclusionXXM2.0 and PsCatCh2.0 could be activated under light intensity with safety for the retina, and could respond to high frequency (at least 32 Hz) pulsed light stimuli with low current attenuation, which could meet the characteristics of opsins required to restore the visual function by optogenetics.
Retinal degeneration is a blind eye disease caused by changes in the function of retinal pigment epithelial cells and photoreceptor cells. Stem cell transplantation, gene therapy, retinal prosthesis implantation and other new biological technologies have made great progress in the restoration of visual function, but they still face many difficulties. Optogenetic is a new interdisciplinary technology that combines optics, physiology and genetics. It can express photosensitive proteins on retinal neurons in retinal degeneration. The light stimulation causing depolarization or hyperpolarization reaction of cells that expressed photosensitive proteins to gain light sensitivity. Compared with the immune rejection of stem cell therapy, the greater individualization of gene therapy and the greater traumatic nature of retinal prosthesis implantation, optogenetic technology has significant advantages, and it is also urgent to solve the problems of low spatial and temporal resolution and light sensitivity. With the gradual development of optogenetics technology, it is bound to form a deeper level of cross and fusion with other fields, so as to contribute to the recovery of visual function of patients with retinal degeneration.
X-linked juvenile retinoschisis (XLRS) is a rare X-linked inherited retinal disorder, mainly affects bilateral retina. Patients often present with visual deterioration accompanied by a spoke-wheel pattern in the macula due to splitting of inner retinal layers and a disproportionate decline in the b-wave relative to a-wave of electroretinogram. The current therapy is mainly directed toward treatment of complications with no effective clinical management yet. In recent years, with the deepening understanding of XLRS, adeno-associated virus(AAV)-mediated gene therapy has become a potential new approach for the treatment. Two clinical trials on XLRS gene therapy are currently underway. These two clinical trials assess the ocular safety and tolerability of recombinant AAV-RS1 vector and explore its safe dose in XLRS patients. However, the recovery of retinal structure and function in XLRS patients is unsatisfactory. Following the in-depth research and progress of clinical trials, it is expected that more accurate and effective treatments for XLRS patients will be provided in the future.
Choroideremia (CHM) is an X-linked recessive inherited retinal disease characterized by progressive degeneration of photoreceptors, retinal pigment epithelium and choroid. Clinical manifestations include slowly progressive night blindness and visual field defects, for which there is no effective treatment. The development of fundus examination technology has provided more indicators for clinical diagnosis and follow-up observation, and the emergence of next generation sequencing technology has further improved the diagnostic rate of inherited retinal diseases, gradually deepening the understanding of the pathogenesis and natural history of CHM. Numerous clinical trials of CHM gene therapy have been conducted over a decade, with important advances in vector optimization for gene therapy, treatment time window selection, and management of trial adverse events. In the future, there is a need to deepen the understanding of the natural course of CHM and to adopt personalized treatment and endpoint evaluation targets for the treatment time window. Assessing differences in disease severity and individualizing treatment plans for different stages is more beneficial to prognosis.
Ophthalmic imaging examination is the main basis for early screening, evaluation and diagnosis of eye diseases. In recent years, with the improvement of computer data analysis ability, the deepening of new algorithm research and the popularization of big data platform, artificial intelligence (AI) technology has developed rapidly and become a hot topic in the field of medical assistant diagnosis. The advantage of AI is accurate and efficient, which has great application value in processing image-related data. The application of AI not only helps to promote the development of AI research in ophthalmology, but also helps to establish a new medical service model for ophthalmic diagnosis and promote the process of prevention and treatment of blindness. Future research of ophthalmic AI should use multi-modal imaging data comprehensively to diagnose complex eye diseases, integrate standardized and high-quality data resources, and improve the performance of algorithms.
ObjectiveTo explore the light response, retinal inflammation and apoptosis of the retinal ganglion cells (RGCs) 1 year after the new type of channelrhodopsin PsCatCh2.0 was transfected into the retina of rd1 mice. MethodsTwenty-four male rd1 mice were randomly divided into rd1 experimental group and rd1 control group, 12 mice in each group. 1.5 μl of recombinant adeno-associated virus (rAAV)2/2-cytomegalovirus (CMV)-PsCatCh2.0-enhanced green fluorescent protein (EGFP) was injected into the vitreous cavity 1 mm below the corneoscleral limbus of mice in the rd1 experimental group, and the same dose of recombinant virus was injected 2 weeks later at temporal side 1 mm below the corneoscleral limbus. One year after virus injection, the light response of RGCs expressing PsCatCh2.0 was recorded by patch clamp technique; the expression of PsCatCh2.0 in the retina was evaluated by immunofluorescence staining; the transfection efficiency of recombinant virus was evaluated by the transfection efficiency of virus and the number of RGCs. Hematoxylin-eosin staining was performed to measure the inner retinal thickness. Western blotting was used to detect the protein expression of nuclear factor (NF)-κB p65 in retina; real-time quantitative polymerase chain reaction was used to detect the relative expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and Bax mRNA. Terminal deoxynucleotidyl transferase kit was used to observe the apoptosis of retinal cells in each group of mice. ResultsOne year after the intravitreal injection of recombinant virus, PsCatCh2.0-expressing RGCs can still generate 30 pA photocurrent. The virus PsCatCh2.0-EGFP was mainly transfected into RGCs, and partly transfected into amacrine cells, almost no transfection was seen in bipolar and horizontal cells. There were no significant differences in the number of RGCs and thickness of the inner retina between the rd1 experimental group and the rd1 control group (F=14.35, 0.05; P＞0.05), while the rd1 experimental group NF-κB p65 protein expression, TNF-α and IL-6 mRNA quantification were significantly lower than those of rd1 control group (F=4.61, 5.91, 5.78; P＜0.05). The number of red fluorescent apoptotic cells in the retina of mice in the rd1 experimental group was less than that in the rd1 control group, and the Bax mRNA expression was lower than that in the rd1 control group, and the difference was statistically significant (F=7.52, P＜0.01). ConclusionOne year after intravitreal injection of recombinant virus, the PsCatCh2.0 expressing RGCs can still generate photocurrent. Long term transfection and expression of PsCatCh2.0 has no obvious cytotoxic effect on RGCs, nor it increases the inflammatory effect of the retina of rd1 mice with retinal degeneration.
Objective To analyze the pathogenic gene and clinical phenotypes of a family affected with rare sector retinitis pigmentosa (sector RP). Methods A retrospective clinical study. A patient with sector RP diagnosed in Renmin Hospital of Wuhan University and his parents were included in the study. Detailed medical history was collected; best corrected visual acuity (BCVA), fundus color photography, autofluorescence (AF), visual field, optical coherence tomography (OCT), electroretinogram, fluorescein fundus angiography (FFA), indocyanine green angiography (ICGA) examination were performed. The peripheral venous blood of the patient and his parents were collected, and DNA was extracted. A whole exon sequencing was used for the proband. The mutations were verified by targeted Sanger sequencing and quantitative polymerase chain reaction. Bioinformatics analysis and cosegregation analysis were performed. ResultsThe proband, a 17-year-old male, had presented with gradually decreased vision in the past 2 years with BCVA of 0.4 in both eyes. Retinal vessels attenuation and macular dystrophy without obvious pigmentation on the fundus were observed. AF showed, in bilateral eyes, a symmetrical hypo-autofluorescent region only in the inferonasal quadrant and “petal-like” hyper-AF macula. The visual field examination showed defects in the superotemporal quadrant corresponding to the affected retina. OCT showed loss of the photoreceptor layer except for the foveal region. Electroretinogram examination presented reduced scotopic wave peaks and extinct photopic response. FFA and ICGA showed the atrophy retinal pigment epithelium around the optic disk and in the inferior retina. The clinical phenotypes of the parents were normal. The whole exon sequencing identified one mutation in SPATA7 gene, c.1112T>C (p.Ile371Thr) in exon10 and a copy number variation in trans. The missense mutation resulted in the change of isoleucine to threonine at amino acid 371 in the encoded SPATA7 protein, and the mother carried this heterozygous mutation c.1112T>C. According to the guidelines of the American College of Medical Genetics and Genomics (ACMG) criteria and guidelines for classification of genetic variants, the missense mutation was classified as the uncertain significance. The CNV, originating from his father, contributed to the loss of exon10 and was confirmed as the likely pathogenic variant. ConclusionsThe macula can be involved in sector RP, leading to the macular dystrophy. The missense variant in SPATA7 gene, c.1112T>C (p.Ile371Thr), might be a pathogenic mutation site in this pedigree.