Retinal Leakage Research Articles

Multiple sclerosis-associated uveitis in Persian population, a multicenter study

PurposeTo report the characteristics of multiple sclerosis-associated uveitis (MSU) among the Persian population. Patients and methodsRetrospective, nonrandomized, multicenter study. Epidemiological characteristics, ocular and neurologic findings, angiographic features, and visual outcomes in MSU were studied. Results92 patients (173 eyes) were included; the mean age at the time of uveitis onset was 35.9 ± 10.9 years (range; 10–60 years), 84.8 % were female, and 88.0 % had bilateral involvement. The anatomical subgroups were isolated anterior uveitis (AU) in 12.0 %, intermediate uveitis (IU) with or without AU in 84.8 % and pure retinal vasculitis in 3.3 % of patients. None of the patients were defined as having posterior or panuveitis. Uveitis had an insidious onset and chronic course in 89.1 % patients and was of granulomatous type in 81.9 %. The diagnosis of MS precedes uveitis onset in 48.8 % patients (range 1 to 35 years, median: 7 years) and was concurrent or after the uveitis onset in 52.2 % patients (range; 1 to 12 years; median: 2 years). Undifferentiated intermediate uveitis was the most common initial diagnosis (30.4 %) before MS establishment. 89.1 % of patients received at least one conventional immunotherapy agent. Peripheral retinal perivascular leakage (81.4 %) and optic disc hyperfluorescence (74.4 %) were the two most common fluorescein angiography (FA) findings The major causes of visual impairment were cataracts (52.7 %), cystoid macular edema (CME) (31.5 %), and optic neuritis (29.2 %). During an average follow-up time of 4.76 ± 3.18 years (range: 1–12 years), visual acuity improved –0.09 logMar/year and most eyes maintain relatively good visual acuity. ConclusionMSU usually presents as chronic granulomatous bilateral IU and less often isolated AU, especially in females. Retinal vasculitis can be a prominent feature. Clinically, it may resemble Undifferentiated intermediate uveitis . In geographical areas where MS is prevalent, the indication of neuroimaging should be expanded and include patients presenting with chronic granulomatous IU or AU especially if accompanied by retinal vasculitis.

Regulation of AMPK and GAPDH by Transglutaminase 2 Plays a Pivotal Role in Microvascular Leakage in Diabetic Retinas.

Diabetic retinopathy is the most common microvascular complication caused by chronic hyperglycemia and is a leading cause of blindness; however, the underlying molecular mechanism has not been clearly elucidated. Thus, we investigated whether regulation of AMPactivated protein kinase (AMPK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by transglutaminase 2 (TGase2) is important for hyperglycemia-induced microvascular leakage in the diabetic retina. In HRECs and diabetic mouse retinas, we found that TGase2, activated by sequential elevation of intracellular Ca2+ and reactive oxygen species (ROS) levels, played an essential role in hyperglycemia-induced vascular leakage. ROS generation and TGsae2 activation were involved in hyperglycemia-induced AMPK dephosphorylation, which resulted in VE-cadherin disassembly and increased fluorescein isothiocyanate-dextran extravasation. Furthermore, high glucose-induced TGase2 activation suppressed GAPDH activity, determined by an on-chip activity assay, through inhibition of AMPK, which induced VE-cadherin disassembly and endothelial permeability in HRECs. Overall, our findings suggest that inhibition of AMPK and GAPDH by TGase2 plays a pivotal role in hyperglycemia-induced microvascular leakage in the retinas of diabetic mice.

Therapeutic potential of histamine H4 receptor antagonist as a preventive treatment for diabetic retinopathy in mice

Diabetic retinopathy (DR) is a prevalent complication of diabetes, often resulting in vision loss and blindness. Existing treatments primarily aim to control blood sugar levels and inhibit angiogenesis. However, current therapies for DR, such as anti-VEGF and laser photocoagulation, are frequently invasive, and can cause adverse side effects. Consequently, there is a critical need for new preventive therapeutics to address DR more effectively. This study aimed to examine the therapeutic potential of a histamine H4 receptor (HRH4) antagonist as a preventive treatment for DR in mice. A mouse model of DR was established by intraperitoneally injecting 200 mg/kg of streptozotocin (STZ). Immune cell infiltration into the retina of mice with STZ-induced diabetes was measured using fluorescence-activated cell sorting (FACS) 12 weeks after STZ injection. The preventive effects of the HRH4 antagonist on inflammation and pathological retinal vessel leakage were determined in a mouse model of DR. Infiltration of HRH4-expressing macrophages increased in the retina of mice with STZ-induced DR. The HRH4 antagonist prevented macrophage infiltration and retinal vascular leakage to prevent STZ-induced DR in mice without causing any retinal toxicity. The infiltration of macrophages increased in the retina of mice with STZ-induced diabetes through HRH4, indicating that HRH4 is potentially a novel preventative therapeutic target in DR. These findings suggest that targeting HRH4 is a promising strategy for the prevention and treatment of DR.

CST3 alleviates retinal vascular leakage by regulating the Rap1 signaling pathway

Retinal vascular leakage is a major event in several retinal diseases, including diabetic retinopathy (DR). In a previous study, we demonstrated that the aqueous humor concentration of Cystatin C (CST3), a physiological inhibitor of cysteine protease, is negatively correlated with the severity of diabetic macular edema. However, its function in the retina has not been clearly elucidated. In this study, we found a significant decrease in the aqueous humor concentration of CST3 with DR progression. Furthermore, we found that CST3 was expressed in retinal endothelial cells and that its expression was significantly downregulated in high glucose-treated human retinal microvascular endothelial cells (HRMECs) and the retinal vessels of oxygen-induced retinopathy (OIR) mice. Silencing CST3 expression resulted in decreased HRMEC migration and tubule formation ability. Exogenous addition of the CST3 protein significantly improved HRMEC migration and tubular formation. In-vivo experiments demonstrated that CST3 silencing induced retinal vascular leakage in WT mice, while its intravitreal injection significantly reduced retinal leakage in OIR mice. Mechanistically, CST3 promoted the expression of the downstream adhesion molecules, claudin5, VE-cadherin, and ZO-1, in retinal vascular cells by regulating the Rap1 signaling pathway. Therefore, this study revealed a novel mechanism by which CST3 improves retinal vascular function and provided evidence that it is a potential therapeutic target for retinal vascular leakage.

Cellular communication network factor 1 promotes retinal leakage in diabetic retinopathy via inducing neutrophil stasis and neutrophil extracellular traps extrusion

BackgroundDiabetic retinopathy (DR) is a major cause of blindness and is characterized by dysfunction of the retinal microvasculature. Neutrophil stasis, resulting in retinal inflammation and the occlusion of retinal microvessels, is a key mechanism driving DR. These plugging neutrophils subsequently release neutrophil extracellular traps (NETs), which further disrupts the retinal vasculature. Nevertheless, the primary catalyst for NETs extrusion in the retinal microenvironment under diabetic conditions remains unidentified. In recent studies, cellular communication network factor 1 (CCN1) has emerged as a central molecule modulating inflammation in pathological settings. Additionally, our previous research has shed light on the pathogenic role of CCN1 in maintaining endothelial integrity. However, the precise role of CCN1 in microvascular occlusion and its potential interaction with neutrophils in diabetic retinopathy have not yet been investigated.MethodsWe first examined the circulating level of CCN1 and NETs in our study cohort and analyzed related clinical parameters. To further evaluate the effects of CCN1 in vivo, we used recombinant CCN1 protein and CCN1 overexpression for gain-of-function, and CCN1 knockdown for loss-of-function by intravitreal injection in diabetic mice. The underlying mechanisms were further validated on human and mouse primary neutrophils and dHL60 cells.ResultsWe detected increases in CCN1 and neutrophil elastase in the plasma of DR patients and the retinas of diabetic mice. CCN1 gain-of-function in the retina resulted in neutrophil stasis, NETs extrusion, capillary degeneration, and retinal leakage. Pre-treatment with DNase I to reduce NETs effectively eliminated CCN1-induced retinal leakage. Notably, both CCN1 knockdown and DNase I treatment rescued the retinal leakage in the context of diabetes. In vitro, CCN1 promoted adherence, migration, and NETs extrusion of neutrophils.ConclusionIn this study, we uncover that CCN1 contributed to retinal inflammation, vessel occlusion and leakage by recruiting neutrophils and triggering NETs extrusion under diabetic conditions. Notably, manipulating CCN1 was able to hold therapeutic promise for the treatment of diabetic retinopathy.

Inefficacy of anti-VEGF therapy reflected in VEGF-mediated photoreceptor degeneration

Retinal neovascularization (RNV) is primarily driven by vascular endothelial growth factor (VEGF). However, current anti-VEGF therapies are limited by short half-lives and repeated injections, which reduce patient quality of life and increase medical risks. Additionally, not all patients benefit from anti-VEGF monotherapy, and some problems, such as unsatisfactory vision recovery, persist after long-term treatment. In this study, we constructed a recombinant adeno-associated virus (AAV), AAV2-SPLTH, which encodes an anti-VEGF antibody similar to bevacizumab, and assessed its effects in a doxycycline-induced Tet-opsin-VEGFA mouse model of RNV. AAV2-SPLTH effectively inhibited retinal leakage, RNV progression, and photoreceptor apoptosis in a Tet-opsin-VEGF mouse model. However, protemic sequencing showed that AAV2-SPLTH failed to rescue the expression of phototransduction-related genes, which corresponded with reduced photoreceptor cell numbers. This study suggests that anti-VEGF monotherapy can significantly inhibit RNV to some extent, but may not be enough to save visual function in the long term.

TET2-mediated ECM1 hypomethylation promotes the neovascularization in active proliferative diabetic retinopathy

BackgroundStudies have shown that tet methylcytosine dioxygenase 2 (TET2) is highly expressed in diabetic retinopathy (DR), which reduces the DNA methylation of downstream gene promoters and activates the transcription. Abnormally expressed TET2 and downstream genes in a high-glucose environment are associated with retinal capillary leakage and neovascularization. Here, we investigated the downstream genes of TET2 and its potential association with neovascularization in proliferative diabetic retinopathy (PDR).MethodsGSE60436, GSE57362, and GSE158333 datasets were analyzed to identify TET2-related hypomethylated and upregulated genes in PDR. Gene expression and promoter methylation of these genes under high glucose treatment were verified. Moreover, TET2 knockdown was used to assess its impact on tube formation and migration in human retinal microvascular endothelial cells (HRMECs), as well as its influence on downstream genes.ResultsOur analysis identified three key genes (PARVB, PTPRE, ECM1) that were closely associated with TET2 regulation. High glucose-treated HRMECs exhibited increased expression of TET2 and ECM1 while decreasing the promoter methylation level of ECM1. Subsequently, TET2 knockdown led to decreased migration ability and tube formation function of HRMECs. We further found a decreased expression of PARVB, PTPRE, and ECM1, accompanied by an increase in the promoter methylation of ECM1.ConclusionsOur findings indicate the involvement of dysregulated TET2 expression in neovascularization by regulating the promoter methylation and transcription of downstream genes (notably ECM1), eventually leading to PDR. The TET2-induced hypomethylation of downstream gene promoters represents a potential therapeutic target and offers a novel perspective on the mechanism underlying neovascularization in PDR.Graphical

Treatment of neovascular age-related macular degeneration with anti-vascular endothelial growth factor drugs: progress from mechanisms to clinical applications.

Neovascular age-related macular degeneration (nARMD) is an important cause of visual impairment and blindness in the elderly, with choroidal neovascularization in the macula as the main pathological feature. The onset of nARMD is closely related to factors including age, oxidative stress, and lipid metabolism. Vascular endothelial growth factor (VEGF) is an important factor contributing to nARMD as well as choroidal neovascularization and retinal leakage formation. At present, anti-VEGF therapy is the only treatment that improves vision and halts disease progression in most patients, making anti-VEGF drugs a landmark development for nARMD treatment. Although intravitreal injection of anti-VEGF drugs has become the first-line treatment for nARMD, this treatment has many shortcomings including repeated injections, poor or no response in some patients, and complications such as retinal fibrosis. As a result, several new anti-VEGF drugs are being developed. This review provides a discussion of these new anti-VEGF drugs for the treatment of nARMD.

Mouse model of radiation retinopathy reveals vascular and neuronal injury

PurposeTo characterize the neuronal and vascular pathology in vivo and in vitro in a mouse model of radiation retinopathy. MethodsC57Bl/6J mice underwent cranial irradiation with 12 Gy and in vivo imaging by optical coherence tomography and of relative blood flow velocity by laser speckle flowgraphy for up to 3–6 months after irradiation. Retinal architecture, vascular density and leakage and apoptosis were analyzed by histology and immunohistochemistry before irradiation or at 10, 30, 240, and 365 days after treatment. ResultsThe vascular density decreased in the plexiform layers starting at 30 days after irradiation. No impairment in retinal flow velocity was seen. Subtle perivascular leakage was present at 10 days, in particular in the outer plexiform layer. This corresponded to increased width of this layer. However, no significant change in the retinal thickness was detected by OCT-B scans. At 365 days after irradiation, the nuclear density was significantly reduced compared to baseline. Apoptosis was detected at 30 days and less prominent at 365 days. ConclusionsBy histology, vascular leakage at 10 days was followed by increased neuronal apoptosis and loss of neuronal and vascular density. However, in vivo imaging approaches that are commonly used in human patients did not detect pathology in mice.

AAV2-antiVEGFscFv gene therapy for retinal neovascularization

Retinal neovascularization (NV) may lead to irreversible vision impairment, the main treatment for which is the inhibition of vascular endothelial growth factor (VEGF). Existing drugs show limited clinical benefits because of their high prices and short half-lives, which increase the financial burden and medical risks to patients. Gene therapy on the basis of adeno-associated viruses is a promising approach to overcome these limitations because ofthe nonintegrative nature, low immunogenicity, and potential long-term gene expression of adeno-associated viruses. In this study, we constructed a novel recombinant adeno-associated virus with the single-chain fragment variable (scFv) fragment ofthe anti-VEGF antibody, AAV2-antiVEGFscFv, consisting ofthe VH and VL structural domains of IgG. AAV2-antiVEGFscFv effectively inhibited NV, retinal leakage, and retinal detachment in oxygen-induced retinopathy (OIR) mice, Tet/opsin/VEGF double-transgenic mice, and VEGF-induced rabbit NV models. AAV2-antiVEGFscFv also significantly suppressed VEGF-induced inflammation. Furthermore, we showed that AAV2-antiVEGFscFv could be sustainably expressed for a prolonged period and exhibited low immunotoxicity invivo. This study indicates that AAV2-antiVEGFscFv could be a potential approach for NV treatment and provides strong support for preclinical research.

Retraction of cystoid macular edema from the fovea after intravitreal anti-VEGF therapy for birdshot chorioretinopathy.

To report the effect of anti-vascular endothelial growth factor inhibitor (anti-VEGF) on fovea-involving cystoid macular edema in a patient with Birdshot chorioretinopathy. A 42-year-old male patient presented to our hospital with bilateral posterior uveitis with retinal vasculitis, cystoid macular edema and optic disc edem a. He was diagnosed with birdshot chorioretinopathy based on clinical appearance and tissue type HLA-A29. The patient underwent vitrectomy in the right eye without any change in visual acuity. Retinal leakage was reduced by oral prednisolone, which could not be tapered below 50 mg per day without relapse. Oral prednisolone, topical dexamethasone and subtenonal kenalog were associated with intraocular pressure rise in both eyes. Hence, his uveitis responded to steroids, but there was no detectable effect of any steroid-sparing immunomodulatory drugs. The patient had been on oral prednisolone 50 mg for five years when it was decided to attempt intravitreal VEGF inhibitor injection therapy. The anti-VEGF therapy diminished cystoid macular edema in the fovea and improved the visual acuity. Here we report for the first time the long-term outcomes of anti-VEGF injections on fovea-involving cystoid macular edema in Birdshot chorioretinopathy to keep steroid at the minimal possible doses and preserve a satisfying visual acuity level.

Diabetic Macular Edema Is Predictive of Renal Failure in Patients With Diabetes Mellitus and Chronic Kidney Disease.

Chronic hyperglycemia in patients with diabetes mellitus (DM) causes retinal damage and leakage, resulting in vision loss. Although diabetic retinopathy (DR) and diabetic kidney disease (DKD) are usually correlated, the relationship between diabetic macular edema (DME) and DKD remains unknown. To assess whether DME presence can predict renal failure in patients with DM and chronic kidney disease (CKD). This retrospective cohort study used data from 120 healthcare organizations in the TriNetX network. Electronic medical records of approximately 90 million patients were reviewed. The study population was classified into DME and non-DME cohorts. Primary and secondary outcomes were new-onset end-stage renal disease (ESRD) and all-cause mortality, respectively. Covariate factors were incorporated to reduce confounding effects. Before matching, the DME cohort used more medication and had poorer renal function and blood sugar control than the non-DME cohort. Subsequently, the 2 groups were well-matched in demographics, socioeconomic status, lifestyle, comorbidities, and medication usage. The DME cohort had a significantly higher risk of ESRD, dialysis, and renal transplantation than the non-DME cohort. Subgroup analyses showed consistent results irrespective of follow-up duration, initial estimated glomerular filtration rate, or glycated hemoglobin levels. Additionally, the DME cohort had a lower risk of all-cause mortality than the non-DME cohort. Statistically significant 5-year increased risks of ESRD, dialysis, and renal transplantation were observed in patients with concurrent DME. Therefore, close monitoring and follow-up of the renal function in DM patients with DME are necessary and strongly recommended.

Medium-term efficacy and safety analysis of Ex-PRESS shunt implantation for the treatment of secondary glaucoma in Sturge-Weber syndrome

Objective: To evaluate the medium-term efficacy and safety of Ex-PRESS shunt implantation in the treatment of secondary glaucoma associated with Sturge-Weber Syndrome (SWS). Methods: This was a retrospective case series study. Medical records of patients diagnosed with secondary glaucoma due to SWS who underwent Ex-PRESS shunt implantation at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, between January 2013 and February 2020 were collected. Only the right eye were included in the analysis when both eyes were affected. Follow-up visits were scheduled at postoperative week 1, 3 months, 6 months, 1 year, 2 years, and 3 years. Clinical data including intraocular pressure (IOP), vertical cup-to-disc (C/D) ratio, corneal horizontal diameter, visual field, anterior chamber condition, anti-glaucoma medication usage, and additional surgeries were evaluated and analyzed before and after the procedure. Surgical success rates and procedure-related complications at each follow-up time point were assessed. Statistical analyses were performed using t-test, Mann-Whitney U test, and χ2 test. Results: A total of 21 patients (21 eyes) were included in the study, comprising 10 females and 11 males. Among them, 15 eyes were on the right side, and 6 eyes were on the left side. The patients' ages ranged from 3 to 51 years, with a median age of 8.1 (6.3, 11.9) years. The follow-up period ranged from 3 to 53 months, with a median of 11 (6, 24) months. Preoperatively, the IOP in the 21 operated eyes was (32.9±9.1) mmHg (1 mmHg=0.133 kPa), significantly higher than the IOP in the 19 healthy eyes, which was (17.1±4.3) mmHg (t=5.80, P<0.001). The C/D ratio in the operated eyes was (0.75±0.13), also significantly higher than that in the healthy eyes, which was (0.32±0.10) (t=11.22, P<0.001). At the 1-year, 2-year, and 3-year follow-up, 8 eyes out of 16 operated eyes, 6 eyes out of 9 operated eyes, and 7 eyes out of 10 operated eyes achieved overall surgical success (complete success+conditional success), respectively. The number of eyes with complete success at the three follow-up time points was 3, 2, and 4, respectively. The IOP in the operated eyes was significantly reduced at all follow-up time points compared to preoperative values (all P<0.05), while there was no statistically significant difference in C/D ratio before and after surgery (all P>0.05). Two operated eyes experienced retinal detachment or choroidal leakage postoperatively, both of which recovered after conservative treatment. One eye developed postoperative degree Ⅰ shallow anterior chamber, and it resolved spontaneously on the third day after surgery. No serious surgical complications, such as bleb-related complications, malignant glaucoma, expulsive choroidal hemorrhage, or endophthalmitis, were observed postoperatively. Conclusions: Ex-PRESS shunt implantation for the treatment of secondary glaucoma in SWS demonstrated a relatively high level of safety. The medium-term IOP in the operated eyes significantly decreased compared to preoperative values. However, the majority of operated eyes did not achieve complete surgical success.

A new phenotype or retinal involvement in Steinert Disease: a case report.

To report a case illustrating the association of Steinert Disease (SD) with peripheral retinal non-perfusion areas and epiretinal membrane. Case report. A 47-year-old Caucasian female diagnosed with SD was referred for blurred vision in her right eye (RE). She presented bilateral ptosis with deficit of elevator muscle.Dilated fundus examination revealed altered macular reflex, peripheral vascular alterations, and ghost vessels bilaterally. Structural spectral domain optical coherence tomography (SD-OCT) showed an epiretinal membrane with a partial alteration of the foveal profile in the RE. Optical coherence tomography angiography (OCTA) images revealed no evidence of neovascular membrane in the macular region. Fluoresceine angiography (FA) showed retinal peripheral non perfusion areas and leakage in the late phases of the examination. Any retinal alteration should be considered during the ophthalmological examination of patients suffering from type 1 myotonic dystrophy. OCT and fluoresceine angiography should be performed evaluating the SD patient that complains about visual impairment.

Ocular manifestations and clinical outcomes in Tubulointerstitial Nephritis and Uveitis Syndrome (TINU).

To describe the various ocular clinical features and visual outcomes in Tubulointerstitial Nephritis and Uveitis Syndrome (TINU). The medical records of 13 patients (26 eyes) diagnosed with TINU were reviewed. Twenty-six (26) eyes of 13 patients with TINU were reviewed in this study. The median age at onset of uveitis was 14 (range, 9-45). Eight (61.5%) subjects were female. The median follow-up of patients was 30 months (range, 6-89 months). Posterior segment findings were seen in 18 eyes of 9 patients (69.2%). The most common posterior findings were optic nerve head inflammation (16 eyes, 88.8%) and retinal vasculitis (13 eyes, 72.2%). Other posterior findings included vitritis (8 eyes, 44.4%), macular edema (6 eyes, 33.3%), snowball (4 eyes, 22.2%), and chorioretinal lesions (2 eye, 11.1%). Eight patients had fluorescein angiography (FA) data available and most eyes had retinal capillary leakage (13 eyes, 81.2%) followed by optic disc staining/leakage (12 eyes, 75%). Twelve (12) patients (92.3%) were treated with immunomodulatory treatment (IMT) and/or biologics. Five patients (%38.4) required biologics to control intraocular inflammation. Posterior segment involvement may be common in patients with TINU syndrome. FA provides significant information for detecting posterior segment involvement and disease activity in TINU. The majority of patients required systemic treatment in order to control intraocular inflammation and prevent relapses.

Wait-and-see and other factors associated with recurrence risk in central serous chorioretinopathy patients: A systematic review and meta-analysis of cohort studies

Background: Central serous chorioretinopathy (CSC) is a common macular disease characterized by serous retinal detachment and leakage spots at the level of the retinal pigment epithelium. While acute CSC is often self-limiting, chronic and recurrent CSC can lead to permanent vision loss. The identification of risk factors associated with recurrent CSC is crucial for preventive measures and appropriate management. This systematic review aims to determine the various risk factors for the recurrence of central serous chorioretinopathy, with a particular focus on the "wait and see" approach and other contributing factors. Methods: The review protocol was registered in PROSPERO (ID: CRD42023413852). A systematic literature search was conducted across four databases (PubMed, Cochrane, Embase, and ScienceDirect) using the keywords "((Central serous chorioretinopathy) AND (Recurrence) AND (Risk))". Meta-analyses were performed using Review Manager 5.4. Results: A total of five studies met the inclusion criteria for all factors, while three studies were selected for meta-analyses regarding the "wait and see" approach. The analysis revealed four significant risk factors for CSC recurrence: patient's clinical condition, therapy administration, age and gender, and patient history. Additionally, a meta-analysis based on three studies involving 1025 eyes demonstrated a statistically significant difference between CSC patients who received no therapy (wait and see) and those who underwent specific therapeutic interventions, with a relative risk of 1.82 (95% CI 1.49–2.22, I2 95%, P &lt;0.00001). Conclusions: Early identification of risk factors, including the ‘wait and see’ approach and other factors, is crucial in preventing the recurrence of central serous chorioretinopathy. Patients at high risk of recurrence should receive vigilant treatment and routine monitoring to avoid permanent vision loss. This systematic review provides valuable insights for clinical decision-making and emphasizes the importance of individualized management strategies for CSC patients.

Therapeutic potential of elema-1,3,7(11),8-tetraen-8,12-lactam from Curcuma wenyujin on diabetic retinopathy via anti-inflammatory and anti-angiogenic pathways

Ethnopharmacological relevanceIn traditional Chinese medicine, the causes of diabetic retinopathy (DR) are blood stasis and heat. Curcuma wenyujin Y. H. Chen & C. Ling and its extracts have the effects of promoting blood circulation to remove blood stasis, clearing the heart, and cooling the blood, and have been used in the treatment of DR. Elema-1,3,7 (11),8-tetraen-8,12-lactam (Ele), an N-containing sesquiterpene isolated from this plant. However, the anti-inflammatory and anti-angiogenic effects of Ele and its therapeutic potential in DR are still unknown. Aim of the studyTo evaluate the anti-inflammatory and anti-angiogenic effects of Ele and its therapeutic potential in DR. Materials and methodsIn vitro, anti-inflammatory and anti-angiogenic effects were assessed using TNF-α or VEGF-stimulated HUVECs. Protein expression was analyzed using Western blotting. ICAM-1 and TNF-α mRNA expressions were analyzed using real-time quantitative RT-PCR. The therapeutic potential in DR was assessed using both animal models of STZ-induced diabetes and oxygen-induced retinopathy. The retinal vascular permeability was measured using Evans blue, and the quantitation of retinal leukostasis using FITC-coupled Con A. The retinal neovascular tufts were analyzed using fluorescein angiography and counting pre-retinal vascular lumens. ResultsEle inhibited NF-κB pathway, and ICAM-1, TNF-α mRNA expression in TNF-α- stimulated HUVECs. It also inhibits the multistep process of angiogenesis by inhibiting the phosphorylation of VEGFR2 and its downstream signaling kinases Src, Erk1/2, Akt, and mTOR in VEGF-stimulated HUVECs. Intravitreal injection of Ele can significantly reduce retinal microvascular leakage, leukostasis, and expression of ICAM-1, TNF-α in diabetic rats and inhibits oxygen-induced retinal neovascularization and VEGFR2 phosphorylation in OIR mice. ConclusionsEle has anti-inflammatory and anti-angiogenic effects through inhibiting NF-κB and VEGFR2 signaling pathways, and it may be a potential drug candidate for DR.

Pathological Neurovascular Unit Mapping onto Multimodal Imaging in Diabetic Macular Edema.

Diabetic retinopathy is a form of diabetic microangiopathy, and vascular hyperpermeability in the macula leads to retinal thickening and concomitant reduction of visual acuity in diabetic macular edema (DME). In this review, we discuss multimodal fundus imaging, comparing the pathogenesis and interventions. Clinicians diagnose DME using two major criteria, clinically significant macular edema by fundus examination and center-involving diabetic macular edema using optical coherence tomography (OCT), to determine the appropriate treatment. In addition to fundus photography, fluorescein angiography (FA) is a classical modality to evaluate morphological and functional changes in retinal capillaries, e.g., microaneurysms, capillary nonperfusion, and fluorescein leakage. Recently, optical coherence tomography angiography (OCTA) has allowed us to evaluate the three-dimensional structure of the retinal vasculature and newly demonstrated that lamellar capillary nonperfusion in the deep layer is associated with retinal edema. The clinical application of OCT has accelerated our understanding of various neuronal damages in DME. Retinal thickness measured by OCT enables us to quantitatively assess therapeutic effects. Sectional OCT images depict the deformation of neural tissues, e.g., cystoid macular edema, serous retinal detachment, and sponge-like retinal swelling. The disorganization of retinal inner layers (DRIL) and foveal photoreceptor damage, biomarkers of neurodegeneration, are associated with visual impairment. Fundus autofluorescence derives from the retinal pigment epithelium (RPE) and its qualitative and quantitative changes suggest that the RPE damage contributes to the neuronal changes in DME. These clinical findings on multimodal imaging help to elucidate the pathology in the neurovascular units and lead to the next generation of clinical and translational research in DME.

Fluorescence Angiography with Dual Fluorescence for the Early Detection and Longitudinal Quantitation of Vascular Leakage in Retinopathy

Diabetic retinopathy (DR) afflicts more than 93 million people worldwide and is a leading cause of vision loss in working adults. While DR therapies are available, early DR development may go undetected without treatment due to the lack of sufficiently sensitive tools. Therefore, early detection is critically important to enable efficient treatment before progression to vision-threatening complications. A major clinical manifestation of early DR is retinal vascular leakage that may progress from diffuse to more localized focal leakage, leading to increased retinal thickness and diabetic macular edema (DME). In preclinical research, a hallmark of DR in mouse models is diffuse retinal leakage without increased thickness or DME, which limits the utility of optical coherence tomography and fluorescein angiography (FA) for early detection. The Evans blue assay detects diffuse leakage but requires euthanasia, which precludes longitudinal studies in the same animals. We developed a new modality of ratiometric fluorescence angiography with dual fluorescence (FA-DF) to reliably detect and longitudinally quantify diffuse retinal vascular leakage in mouse models of induced and spontaneous DR. These studies demonstrated the feasibility and sensitivity of FA-DF in detecting and quantifying retinal vascular leakage in the same mice over time during DR progression in association with chronic hyperglycemia and age. These proof-of-concept studies demonstrated the promise of FA-DF as a minimally invasive method to quantify DR leakage in preclinical mouse models longitudinally.

A Nonrandomized Phase 2 Trial of EG-Mirotin, a Novel, First-in-Class, Subcutaneously Deliverable Peptide Drug for Nonproliferative Diabetic Retinopathy.

Background and objectives: EG-Mirotin (active ingredient EGT022) targets nonproliferative diabetic retinopathy (NPDR), the early stage of retinopathy. EG-Mirotin reverses capillary damage before NPDR progresses to an irreversible stage. EG-Mirotin safety and efficacy were investigated in patients with type 1 or type 2 diabetes mellitus and moderate to severe NPDR. Methods: In this open-label, single-arm, single-center, exploratory phase II study, 10 patients (20 eyes) received EG-Mirotin once a day (3 mg/1.5 mL sterile saline) for 5 days and were evaluated for ischemic index changes and safety. End of study was approximately 8 ± 1 weeks (57 ± 7 days) after the first drug administration. Results: EG-Mirotin injections were well tolerated, with no dose-limiting adverse events, serious adverse events, or deaths. Four treatment-emergent adverse events (TEAEs) unrelated to the investigational drug were observed in 2 out of 10 participants (20%) who had received the investigational drug. The overall average percent change in ischemic index at each evaluation point compared with baseline was statistically significant (Greenhouse-Geisser F = 9.456, p = 0.004 for the main effect of time), and a larger change was observed when the baseline ischemic index value was high (Greenhouse-Geisser F = 10.946, p = 0.002 for time × group interaction). Conclusions: The EG-Mirotin regimen established in this study was shown to be feasible and safe and was associated with a trend toward potential improvement in diabetes-induced ischemia and retinal capillary leakage.