Research progress of diabetic retinopathy and gut microecology.

According to the prediction of the International Diabetes Federation, global diabetes mellitus (DM) patients will reach 783.2 million in 2045. The increasing incidence of DM has led to a global epidemic of diabetic retinopathy (DR). DR is a common microvascular complication of DM, which has a significant impact on the vision of working-age people and is one of the main causes of blindness worldwide. Substantial research has highlighted that microangiopathy and chronic low-grade inflammation are widespread in the retina of DR. Meanwhile, with the introduction of the gut-retina axis, it has also been found that DR is associated with gut microecological disorders. The disordered structure of the GM and the destruction of the gut barrier result in the release of abnormal GM flora metabolites into the blood circulation. In addition, this process induced alterations in the expression of various cytokines and proteins, which further modulate the inflammatory microenvironment, vascular damage, oxidative stress, and immune levels within the retina. Such alterations led to the development of DR. In this review, we discuss the corresponding alterations in the structure of the GM flora and its metabolites in DR, with a more detailed focus on the mechanism of gut microecology in DR. Finally, we summarize the potential therapeutic approaches of DM/DR, mainly regulating the disturbed gut microecology to restore the homeostatic level, to provide a new perspective on the prevention, monitoring, and treatment of DR.

Clinical features of retinal amyloid angiopathy with transthyretin Gly83Arg variant.

AIM: To report on the clinical features of patients with retinal amyloid angiopathy (RAA) who were identified to be caused by the transthyretin (TTR) Gly83Arg variant. METHODS: Case series of five patients diagnosed with RAA was collected at Affiliated Hospital of Zunyi Medical University from January 2010 to December 2021. The clinical features, therapeutic strategies, and prognoses of all patients were reviewed. RESULTS: Five patients with a mean age of 52.00±7.23y were diagnosed as RAA. These patients were previously diagnosed with hereditary transthyretin amyloidosis caused by the TTR Gly83Arg variant. Vitreous opacity was found in all 10 eyes, and 7 eyes developed RAA 2 to 20y after the onset of hereditary transthyretin amyloidosis. The clinical manifestations were recurrent vitreous hemorrhage in 2 eyes (29%), neovascular glaucoma in 2 eyes (29%), and iris neovascularization in 1 eye (14%). Microangioma lesions were found in all affected eyes that underwent fundus fluorescein angiography (FFA) in this group of cases, and the incidence of the retinal non-perfusion area was 67%. Although no cases of retinal neovascularization were found, the prognosis of visual acuity was not ideal. CONCLUSION: This is the first report of RAA in patients with the TTR Gly83Arg variant. Complications such as RAA and glaucoma will seriously affect the visual prognosis of patients. Thereafter, regular ophthalmic follow-up of patients with hereditary transthyretin amyloidosis is essential. And FFA after vitrectomy is very important, which can help ophthalmologists detect RAA earlier and treat it in time.

Multimodal imaging of the course of retinal changes in acute posterior multifocal placoid pigment epitheliopathy with bilateral retinal detachment: a case report.

BACKGROUND: To report a rare case of acute posterior multifocal placoid pigment epitheliopathy (APMPPE) with a combination of serous retinal detachment, papilledema, and retinal vasculitis. CASE PRESENTATION: A 19-year-old male complained of floaters in both eyes with decreased vision for 4 days. The best corrected visual acuity of the right eye and the left eye were 1.1 and 0.9 (logMAR), respectively. In both eyes, inflammatory cells can be seen suspended within the vitreous, multiple yellow/white lesions can be seen near the macula, and retinal neuroepithelial detachment. Swelling of the optic disc with blurring of the disc margins, in the left eye. Optical coherence tomography (OCT): showed retinal detachment in both eyes. The patient received oral prednisone treatment. 1 week later, OCT showed absorption of subretinal fluid in the macula of both eyes his binocular vision improved to 0.1 (logMAR). During the subsequent 28-month follow-up, fundus fluorescein angiography and OCT revealed extensive and progressive pigment epithelial atrophy in both eyes, and abnormal retinal vascular perfusion in the right eye due to persistent retinal vasculitis. Although the patient's binocular visual acuity remained at 0.1 (logMAR). CONCLUSIONS: In the present case of APMPPE with a combination of serous retinal detachment, papilledema, and retinal vasculitis, through the multimodal imaging, further confirming that the lesions were located in the choroid, while the pigment epithelial lesions were secondary changes.

The Effect of A2E on the Uptake and Release of Calcium in the Lysosomes and Mitochondria of Human RPE Cells Exposed to Blue Light.

We aimed to explore the effect of N-retinylidene-N-retinylethanolamine (A2E) on the uptake and release of calcium in lysosomes and mitochondria by establishing a model of human retinal pigment epithelial (RPE) cell injury induced by exposure to blue light. Primary human RPE cells were cultured from passages 4 to 6 and exposed to blue light at an intensity of 2000 ± 500 lux for 6 hours. After blue light exposure, the culture was maintained for 24 hours. A2E at a final concentration of 25 µM was added to the culture 2 hours before light exposure, and nifedipine at a final concentration of 10-4 M was added 1 hour before light exposure. The levels of Ca2+ in the cytosol (CaTM/2AM), mitochondria (Rhod/2AM), and lysosomes (LysoTracker Red and Fluo-3/AM) were determined. In order to measure the calcium levels in the different organelles, RPE were imaged using a laser scanning confocal microscope. Moreover, changes in the mitochondrial membrane potential were detected by flow cytometry analysis of JC-1-stained cells. The obtained results revealed that blue light illumination increased the calcium fluorescence intensity in the cytoplasm, mitochondria, and lysosomes of human RPE cells when compared with the control cells (P < 0.05). After A2E treatment, the fluorescence intensity of the calcium in the cytoplasm was further increased (P < 0.05), while that in the mitochondria and lysosomes decreased (P < 0.05). In addition, we observed that nifedipine reduced the fluorescence intensity of calcium in the RPE cells. Our results also showed that the mitochondrial membrane potential in the RPE treated with blue light and A2E was lower than that in the control, blue light, and A2E-treated cells (P < 0.05). Blue light increased calcium levels in the cytoplasm, lysosomes, and mitochondria of RPE cells. A2E damages the lysosomal and mitochondrial membranes, resulting in calcium release into the cytoplasm. Finally, our results demonstrated that both blue light and A2E treatments reduced mitochondrial membrane potential, increasing cytosolic Ca2+ levels, which can contribute to the activation of RPE death.

Improved thickness measurement method for choroidal hyperpermeability in central serous chorioretinopathy.

AIM: To observe choroidal thickness changes in the choroidal hyperpermeability area (CHA) in patients with central serous chorioretinopathy (CSC) after photodynamic therapy (PDT) using indocyanine green angiography (ICGA) combined with optical coherence tomography (OCT). METHODS: This was a cohort study of 17 eyes (17 patients) with CSC. In all patients, the range of CHA was determined by ICGA. The patients were divided into two groups based on CHA covered the fovea (group A) or not (group B). All patients received half-dose verteporfin PDT over CHA in ICGA. Choroidal thickness was measured by OCT before, 1, and 3mo after treatment. The choroidal thickness values of the fovea and CHAs were obtained for each measurement. Secondary outcomes were changes in the best-corrected visual acuity (BCVA) and amount of subretinal fluid (SRF). RESULTS: The differences in center choroidal thickness at baseline and at 1 and 3mo post-PDT were statistically significant in group A and all patients (both P<0.001). There was no significant difference in group B (P=0.059). The differences of thickness of CHA and BCVA at baseline and 1 and 3mo post-PDT were statistically significant in group A, group B, and all patients (all P<0.01). All patients showed complete SRF absorption at 3mo post-PDT. CONCLUSION: Center choroidal thickness does not accurately reflect changes in CHA of patients whose CHA does not covered the fovea center. Using CHA as the observation target can make up for this limitation, expand the scope of application, and reduce bias.

A mouse model of a novel missense mutation (Gly83Arg) in a Chinese kindred manifesting vitreous amyloidosis only.

The purpose of this study is to establish a mouse model of transthyretin (TTR) Gly83Arg gene mutation by the technique of gene targeting for research on hereditary vitreous amyloidosis (HVA) and to confirm whether this point mutation is a genetic feature of HVA. A vector (pBR322-MK-TTR) was constructed to target ES cells. The successfully transfected ES cells were used for blastocyst injection, thus generating F0. F0 and Flp mice were mated to generate F1 (TTR+/-, Flp +/-) mice that lacked the neo gene but carried the Flp gene. F1 mice were mated with C57BL/6N wild type mice to generate F2 (TTR+/-) mice. F3 homozygous and heterozygous mice were generated by mating F2 mice with each other. PCR and sequencing were performed for F3 mice. Amyloid was detected using Congo red stain and polarized light. Immunohistochemistry was used to detect the expression of TTR in the tissues. Quantitative fluorescent PCR and Western blotting were used to detect the expression of TTR mRNA and TTR protein, respectively. Two F0-generation, 2 F1-generation and 15 F3-generation mice were obtained. The gene sequencing of F3 mice showed TTR Gly83Arg mutation. When examined with Congo red and polarized light, the vitreous of TTR Gly83Arg mutant mice tested positive for amyloid. The hearts, livers, brains and kidneys of the experimental group and control group were all negative by Congo red staining. Immunohistochemical staining showed that the vitreous of TTR Gly83Arg mutant mice and the livers of the control mice were positive, but the kidneys, hearts and brains of both groups were negative. Quantitative fluorescent PCR showed that the mRNA expression of mutant mice was significantly lower than that of wild-type mice (F = 0.295, P = 0.023). Western blotting showed that the expression of TTR protein was significantly lower in the model mice than in the wild-type mice (t = 3.224, P = 0.018). TTR gene mutation is indeed a molecular characteristic of HVA and manifest in the eye disease only. A C57BL/6 mouse line carrying the TTR Gly83Arg gene mutation was successfully established. This strain of mice can be used for the study of HVA.

Profiling of human leukocyte antigens in Eales disease and tuberculosis.

To analyze the association between Eales disease, histocompatibility leukocyte antigen alleles (HLA-A/B, HLA-DRB/DQB) and tuberculosis infection, and to explore susceptible genes and protective genes associated with Eales disease and tuberculosis infection in a population of Han nationals from Zunyi City in Guizhou Province, China. The subjects were analyzed by a case-control study consisting of three groups--Eales disease group (47 cases), pulmonary tuberculosis group (36 cases) and normal control group (100 cases). The Eales disease group was divided into four parts. Part one consisted of 12 patients who had suffered from pulmonary tuberculosis. Part two consisted of 27 patients who had not suffered from pulmonary tuberculosis. Parts three and four consisted of 27 patients with a positive purified protein derivative test and 12 patients with a negative test, respectively. DNA samples from 47 patients with Eales disease, 36 patients with pulmonary tuberculosis and 100 healthy people were detected by polymerase chain reaction with sequence-specific primers. The 59 HLA-A/B and HLA-DRB/DQB alleles from Eales disease were compared with those from tuberculosis and normal control, and a correlativity test of common susceptible genes was performed to analyze the potential relationship between Eales disease and pulmonary tuberculosis. The frequency distribution of HLA-A*02 alleles (OR 9.719, OR 95 % CI 4.377-21.580, P = 0.000) and HLA-B*07 (OR 11.605, OR 95 % CI 2.397-56.191, P = 0.001) in the Eales disease group was higher than in the normal control group, but the HLA-A*11 alleles (OR 0.495, OR 95 % CI 0.245-1.000, P = 0.048) were lower than in the normal control group, showing a significant difference. Compared with parts two and four, the frequency distribution of HLA-A*02, HLA-A*11 and HLA-B*07 alleles in parts one and three showed no significant difference (P > 0.05). HLA-A*A02, HLA-A*24, HLA-B*07 and HLA-DRB*16 alleles between the Eales disease, pulmonary tuberculosis and normal control group showed statistical significance (P < 0.05). HLA-A*24 alleles in the pulmonary tuberculosis group were lower than the Eales disease group (χ(2) 7.289, P = 0.007), but HLA-A*02 alleles showed no significant difference (P > 0.05) between the two groups. The results show that HLA-A*02 and HLA-B*07 may be genetic predisposing genes, but HLA-A*11 alleles may be protective genes of Eales disease, the HLA-A*02 allele may be a common susceptible gene of Eales disease and pulmonary tuberculosis. HLA-A*11 and HLA-A24 alleles are protective genes of Eales disease and pulmonary tuberculosis, respectively. In summary, the frequency distribution of susceptible genes of Eales disease and pulmonary tuberculosis in a population of Han nationals from Zunyi City in Guizhou Province, China showed no significant difference.

[Experimental research of endostatin microcapsules by periocular injection].

OBJECTIVE: To detect the release of endostatin in microcapsules of calcium alginate gel by emulsification-internal gelatification technology, to observe the distribution of Endostatin microcapsules in the eye by periocular injection and biocompatibility. METHODS: The calcium alginate gel microcapsules encapsulating endostatin were prepared by emulsification-internal gelatification technology, the release of endostatin in microcapsules in vitro was examined by uv-Spectrophotometry. 32 SD mice were divided into randomly four groups: group A, periocular injection of endostatin microcapsules 20 microl (2.4 g/L); group B, periocular injection of endostatin protein 20 microl (2.5 g/L); group C, periocular injection of null-Microcapsules 20 microl; group D, periocular injection of saline 20 microl. Western blot, immunohistochemical and enzyme-linked immunosorbent assay were used. Protein expression and pathology of the heart, liver, spleen, lung, kidney and periocular tissue were examined. Daily activities and eating condition were observed.t-test was used to analyze the data. RESULTS: SDS polyacrylamide gel electrophoresis showed strap of ES protein. Concentration of ES protein in superior schedule fluid gradually increased at 3, 7, 14, 21 days. A group: ES protein expression were observed in inner nuclear layer, outer nuclear layer and RPE lamina after periocular injection 7 or 14 days. B group: ES protein expression were observed in above tissues at 7 days, but not at 14 days. C and D group: ES protein expression were not observed in above tissues at 7 or 14 days. The results showed that Endostatin microcapsules was able to pass through the sclera and spread out in various retinal tissues. Concentration of endostatin in the homogenates of eyeball was (63.16 +/- 7.64) microg.L(-1).eye(-1) and (33.2 +/- 5.77) microg.L(-1).eye(-1) respectively after one and two weeks in A group, but (33.2 +/- 2.89) microg.L(-1).eye(-1) and (15.73 +/- 2.08) microg.L(-1).eye(-1). The concentration of endostatin was significant difference in two group, A group was obviously larger than B group (t = 6.364 and 4.920, P = 0.003 and 0.008 respectively). Periocular administration. Daily activities and eating condition were normal. The abnormality in important organs were not detected by pathologic examination. CONCLUSIONS: Endostatin microcapsules is able to release persistently, to pass through the sclera and spread out in various retinal tissues. There were good biocompatibility and not ill effect remarkably.

[Relationship between blue light-induced apoptosis and mitochondrial membrane potential and cytochrome C in cultured human retinal pigment epithelium cells].

OBJECTIVE: To investigate the effect of blue light on apoptosis and mitochondrial permeability transition (MPT) of cultured human retinal pigment epithelium (RPE) cells in vitro. METHODS: Human RPE cells were exposed to blue light (wave length 470 -490 nm). The present study consisted of three parts. Part one studied the effect of various intensities of blue light on the RPE cells. Cells were irradiated with (500+/-100) lx (group 1) , (2000+/-500) lx (group 2) and (3000+/-500)lx ( group 3) blue light, and followed by 24 hours observation. Part two studied the effect of various duration of blue light at identical intensity on the RPE cells. For the study on various subtypes of RPE cells, cells were irradiated by blue light at (2000+/-500) x for 6, 12, and 24 hours. For the study of mitochondrial membrane potential, cells were irradiated for 3, 6, and 12 hours. Part three studied cells irradiated with blue light at identical intensity and duration, but with various prolongation of post-exposure culture. The prolongation of post-exposure culture was 6, 12, 24, and 36 hours. Phototoxicity was quantified at various periods after exposure by staining of the nuclei of membrane-compromised cells, by TdT-dUTP terminal nick-end labeling (TUNEL) of apoptotic cells and by Annexin V labeling for phosphatidylserine exposure. Transmission electronmicroscopy was used to determine the ultrastructure changes of RPE cells. Mitochondrial membrane potential ( deltaPsim ) was measured by rhodamine 123 staining and subsequent flow cytometry. Cytochrome C activity was assayed by ELISA. Caspase-3 was detected by colorimetric assay. RESULTS: TUNEL-positive labeling cells in first group of part two study showed cell shrinkage, membrane blebbing, apoptotic body, condensation and fragmentation of chromatin. Mitochondrial swelling, extinction of inner mitochondrial membrane ridge, dilation of rough endoplasmic reticulum and increase of the lysosome were also observed in transmission electronmicroscopy. Blue light at (500 +/- 100) x intensity did not induce damage to RPE cells, but decrease of delta Psim was observed. A significant increase of apoptotic, apoptotic necrotic and necrotic percentages, as well as significant decrease of deltaPsim were observed at higher light intensity in part one study. Increase of apoptotic percentage was the main response to shorter exposure of blue light. Increase of apoptotic necrotic and necrotic percentage and pronounced decrease of deltaPsim occurred in cells irradiated by longer exposure in part two study. In part 3 study, apoptotic response was increased gradually during 6 and 12 hours prolongation of post-exposure culture, more apoptotic necrosis or necrosis were found after post-exposure 24 hours. Decrease of deltaPsim was observed in 6 hours prolongation of post-exposure culture and lasting for 48 hours. The concentration of cytochrome C was significantly increased in post-exposure 24 and 36 hours, without any changes of Caspase-3 activity. CONCLUSIONS: Blue light exposure can induce damages to human RPE cells in vitro, which include apoptosis, apoptotic necrosis and necrosis. These changes are caused by triggering the mitochondrial permeability transition, which results in decrease of deltaPsim and release of cytochrome C. deltaPsim can be used as a earlier parameter of blue light-induced apoptosis.

[The effect of blue light on mitochondrial membrane potential and cytochrome C of cultured human retinal pigment epithelium cells].

OBJECTIVE: To answer the question whether mitochondrial permeability transition (MPT) participates in blue light-induced damage to human retinal pigment epithelium (RPE) cells, this study was directed at assessing the effect of blue light on mitochondrial membrane potential (delta psi(m)) and cytochrome C (Cyt C) of cultured human RPE cells. METHODS: Human RPE cells were exposed to blue light (wave length 470-490 nm); delta psi(m) was measured by rhodamine 123 staining and subsequent flow cytometry. Three groups were investigated: Group A (exposure to different intensity of blue light); group B (exposure to identical intensity for different duration); group C (exposure to identical intensity and duration, different prolongation of post-exposure culture). Cyt C activity was assayed by ELISA. Caspase-3 was detected by colorimetric assay. In these aspects, two groups were investigated: Group I [(2000+/-500) 1x for 6 h]; Group II [(2000+/-500) 1x for 12 h]. RESULTS: When human RPE cells were exposed to blue light, the more pronounced decrease of delta psi(m) was consistent with the increase of light intensity in group A. Pronounced decrease of delta psi(m) was seen at 6 h and 12 h of exposure duration in group B. At 6 h prolongation of post-exposure culture in group C, the decrease of delta psi(m) was observed, lasting 48 h. The concentration of Cyt C was detected; no significant changes were found at 6 h and 12 h prolongation of post-exposure culture, but a significant increase was found at 24 h and 36 h post-exposure in the two groups. The increase was more significant in Group II than in Group I at 24 h post-exposure. The activity change of caspase-3 was not found in the two groups. CONCLUSION: Blue light exposure over threshold can induce damage to human RPE cells, probably by triggering the mitochondrial permeability transition, which results in the decrease of delta psi(m) and the release of cytochrome C.