Mesenchymal stem cells-derived small extracellular vesicles alleviate diabetic retinopathy by delivering NEDD4

Background

As a leading cause of vision decline and severe blindness in adults, diabetic retinopathy (DR) is characterized by the aggravation of retinal oxidative stress and apoptosis in the early stage. Emerging studies reveal that mesenchymal stem cells-derived small extracellular vesicles (MSC-sEV) treatment represents a promising cell-free approach to alleviate ocular disorders. However, the repairing effects of MSC-sEV in DR remain largely unclear. This study aimed at exploring the role and the underlying mechanism of MSC-sEV in hyperglycemia-induced retinal degeneration.

Methods

In vivo, we used streptozotocin (STZ) to establish diabetic rat model, followed by the intravitreal injection of MSC-sEV to determine the curative effect. The cell viability and antioxidant capacity of retinal pigment epithelium (RPE) cells stimulated with high-glucose (HG) medium after MSC-sEV treatment were analyzed in vitro. By detecting the response of cell signaling pathways in MSC-sEV-treated RPE cells, we explored the functional mechanism of MSC-sEV. Mass spectrometry was performed to reveal the bioactive protein which mediated the role of MSC-sEV.

Results

The intravitreal injection of MSC-sEV elicited antioxidant effects and counteracted retinal apoptosis in STZ-induced DR rat model. MSC-sEV treatment also reduced the oxidative level and enhanced the proliferation ability of RPE cells cultured in HG conditions in vitro. Further studies showed that the increased level of phosphatase and tensin homolog (PTEN) inhibited AKT phosphorylation and nuclear factor erythroid 2-related factor 2 (NRF2) expression in RPE cells stimulated with HG medium, which could be reversed by MSC-sEV intervention. Through mass spectrometry, we illustrated that MSC-sEV-delivered neuronal precursor cell-expressed developmentally downregulated 4 (NEDD4) could cause PTEN ubiquitination and degradation, activate AKT signaling and upregulate NRF2 level to prevent DR progress. Moreover, NEDD4 knockdown impaired MSC-sEV-mediated retinal therapeutic effects.

Conclusions

Our findings indicated that MSC-sEV ameliorated DR through NEDD4-induced regulation on PTEN/AKT/NRF2 signaling pathway, thus revealing the efficiency and mechanism of MSC-sEV-based retinal protection and providing new insights into the treatment of DR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02983-0.

Seasonal and environmental variations in endophthalmitis after intravitreal anti-vascular endothelial growth factor injection: a six-year review

PURPOSE/AIM

To evaluate seasonal and environmental variations on the incidence and outcomes of post-injection endophthalmitis.

MATERIALS AND METHODS

A single-center, retrospective cohort study was conducted including all patients diagnosed with post-injection endophthalmitis between 2013-2018. Associations between climate variables and endophthalmitis incidence were evaluated.

RESULTS

Of 423,297 injections administered, seasonal distribution in spring, summer, autumn, and winter was 26%, 27%, 25%, and 22%, respectively. Of 171 cases of endophthalmitis identified, seasonal distribution over the spring, summer, autumn, and fall was 25%, 23%, 26%, and 26%, respectively. Endophthalmitis incidence was not correlated with monthly precipitation (p = 0.45), monthly snowfall (p = 0.49), or monthly temperature (p = 0.65). Worse visual outcomes at initial endophthalmitis presentation were correlated with increased precipitation level (p = 0.025), but were not correlated with snowfall level (p = 0.228) or mean monthly temperature (p = 0.132). Although there were no seasonal variations of visual acuity at endophthalmitis presentation (p = 0.894), odds of final visual acuity returning to within two lines of pre-endophthalmitis visual acuity were worse among patients with endophthalmitis diagnosed in the spring (OR, 0.041; p = 0.016).

CONCLUSION

In contrast to previous work on post-cataract endophthalmitis, seasonal and weather factors were not associated with post-injection endophthalmitis risk or bacterial species isolated. Visual outcomes at initial endophthalmitis presentation were correlated with precipitation, and worse visual outcomes were seen in patients who developed endophthalmitis in the spring.

A mathematical model of GLUT1 modulation in rods and RPE and its differential impact in cell metabolism

We present a mathematical model of key glucose metabolic pathways in two cells of the human retina: the rods and the retinal pigmented epithelium (RPE). Computational simulations of glucose transporter 1 (GLUT1) inhibition in the model accurately reproduce experimental data from conditional knockout mice and reveal that modification of GLUT1 expression levels of both cells differentially impacts their metabolism. We hypothesize that, under glucose scarcity, the RPE's energy producing pathways are altered in order to preserve its functionality, impacting the photoreceptors' outer segment renewal. On the other hand, when glucose is limited in the rods, aerobic glycolysis is preserved, which maintains the lactate contribution to the RPE.

Application Progress of High-Throughput Sequencing in Ocular Diseases

Ocular diseases affect multiple eye parts and can be caused by pathogenic infections, complications of systemic diseases, genetics, environment, and old age. Understanding the etiology and pathogenesis of eye diseases and improving their diagnosis and treatment are critical for preventing any adverse consequences of these diseases. Recently, the advancement of high-throughput sequencing (HTS) technology has paved wide prospects for identifying the pathogenesis, signaling pathways, and biomarkers involved in eye diseases. Due to the advantages of HTS in nucleic acid sequence recognition, HTS has not only identified several normal ocular surface microorganisms but has also discovered many pathogenic bacteria, fungi, parasites, and viruses associated with eye diseases, including rare pathogens that were previously difficult to identify. At present, HTS can directly sequence RNA, which will promote research on the occurrence, development, and underlying mechanism of eye diseases. Although HTS has certain limitations, including low effectiveness, contamination, and high cost, it is still superior to traditional diagnostic methods for its efficient and comprehensive diagnosis of ocular diseases. This review summarizes the progress of the application of HTS in ocular diseases, intending to explore the pathogenesis of eye diseases and improve their diagnosis.

Automatic Determination of the Center of Macular Hole Using Optical Coherence Tomography En Face Images

To evaluate the automated determination of the center of an idiopathic macular hole (MH) by using swept-source optical coherence tomography (OCT) images with new macro-based algorithms in ImageJ and to compare the difference between the MH center measurements obtained automatically and manually. This cross-sectional study included 39 eyes of 39 elderly individuals (22 women, 17 men) with stage 3 and 4 MH. The MH center was automatically determined using the ImageJ macro. The foveal center was also manually identified by two masked examiners using horizontal and vertical serial B-scan OCT angiography images. The mean age was 68.8 ± 8.3 years. After adjusting for the effect of magnification, the mean distance between the MH center determined manually by Examiner 1 and that determined automatically was 15.5 ± 9.9 µm. The mean distance between the two manually determined measurements of the MH center was 20.3 ± 19.7 µm. These two mean distance values did not differ significantly (Welch t-test, p = 0.27) and was non-inferior (p < 0.0001). The automated ImageJ-based method for determining the MH center was comparable to manual methods. This study showed that automated measurements were non-inferior to manual measurements, and demonstrated a substitutable usefulness, at least for use in clinical practice.

Comparative analysis of macular microstructure in eyes treated with human amniotic membrane plug or internal limiting membrane transplant for Failed Macular Hole

OBJECTIVE

To document comparative analysis of macular microstructures of eyes treated with autologous internal limiting membrane (ILM) transplant and human Amniotic Membrane (hAM) plug transplant for failed macular holes (FMH).

MATERIALS AND METHODS

Six patients who underwent successful surgeries for FMH were evaluated. The first three patients had undergone autologous ILM transplant, the others had undergone hAM plug transplant. They were examined using Adaptive Optics (AO) at baseline and at 6 months after surgery; OCT and OCT-Angiography were performed at 6 months. All images were evaluated morphologically; AO images were also analysed using the internal software.

RESULTS

Regarding the AO analysis in ILM-patients, the average cone density inside the lesion was 7684.44 ± 362.96 and the total spacing was 10.86 ± 0.97. In hAM-patients, the average cone density inside the plug area was 10197.9 ± 326.62 and the total spacing was 10.6 ± 0.72. It was not possible to analyse cone density in the area outside the lesion on any patients. All patients were also evaluated morphologically. OCT analysis in ILM-patients showed a subverted anatomical situation, while in hAM-patients revealed the regrowth of tissue layers and a resumption of foveal depression. OCT-Angiography analysis revealed an enlargement of the FAZ in ILM-patients and a fairly normal appearance and size of the FAZ in hAM-patients, in comparison to the fellow eye.

CONCLUSIONS

Our findings require validation with a longer follow-up in a larger quantity of patients, but already suggest important differences in the cellular mechanism that underlies the tissue remodelling in these two techniques.

Learning Two-Stream CNN for Multi-Modal Age-related Macular Degeneration Categorization

This paper tackles automated categorization of Age-related Macular Degeneration (AMD), a common macular disease among people over 50. Previous research efforts mainly focus on AMD categorization with a single-modal input, let it be a color fundus photograph (CFP) or an OCT B-scan image. By contrast, we consider AMD categorization given a multi-modal input, a direction that is clinically meaningful yet mostly unexplored. Contrary to the prior art that takes a traditional approach of feature extraction plus classifier training that cannot be jointly optimized, we opt for end-to-end multi-modal Convolutional Neural Networks (MM-CNN). Our MM-CNN is instantiated by a two-stream CNN, with spatially-invariant fusion to combine information from the CFP and OCT streams. In order to visually interpret the contribution of the individual modalities to the final prediction, we extend the class activation mapping (CAM) technique to the multi-modal scenario. For effective training of MM-CNN, we develop two data augmentation methods. One is GAN-based CFP/OCT image synthesis, with our novel use of CAMs as conditional input of a high-resolution image-to-image translation GAN. The other method is Loose Pairing, which pairs a CFP image and an OCT image on the basis of their classes instead of eye identities. Experiments on a clinical dataset consisting of 1,094 CFP images and 1,289 OCT images acquired from 1,093 distinct eyes show that the proposed solution obtains better F1 and Accuracy than multiple baselines for multi-modal AMD categorization. Code and data are available at https://github.com/li-xirong/mmc-amd.

Hydroalcoholic Leaf Extract of Punica granatum, alone and in Combination with Calcium Hydroxide, Is Effective against Mono- and Polymicrobial Biofilms of Enterococcus faecalis and Candida albicans

Failures in endodontic treatments are mostly associated with the difficulty in eradicating microbes of the root canal system, highlighting the need to develop novel effective antimicrobials. Punica granatum (pomegranate) leaf hydroalcoholic extract may be a potential alternative in canal dressing, owing to its antimicrobial properties. The objective of this study was to evaluate the antimicrobial activity of hydroalcoholic leaf extract of Punica granatum (HEPg) alone or in combination with calcium hydroxide (Ca(OH)₂) against Enterococcus faecalis and Candida albicans in isolation and in mono- and polymicrobial biofilms. Microdilution tests in broth and assays for inhibition of biofilm formation were carried out to evaluate the antimicrobial properties of HEPg and HEPg + Ca(OH)₂ against Enterococcus faecalis and Candida albicans. The cytotoxicity of HEPg in HaCaT cells was evaluated by MTT assay. HEPg and HEPg + Ca(OH)₂ exerted significant antimicrobial activity against planktonic cells and mono- and polymicrobial biofilms. The combination of Punica granatum extract with Ca(OH)₂ appears to be a promising alternative in endodontic treatments, which could be tested in vivo to confirm the efficacy of this mixture in disinfecting root canal systems.

Safety and outcomes of intravitreal aflibercept in diabetic macular edema - a systematic review

BACKGROUND

Recent evidence on the role of vascular endothelial growth factor (VEGF) in the pathogenesis of ischemia and microvascular hyperpermeability leading to macular edema has brought anti-VEGF intravitreal therapy into the limelight.

OBJECTIVE

We performed a systematic literature review focusing on the outcomes and safety of the intravitreal use of aflibercept in diabetic macular edema.

METHODS

The studies documented cases with at least three consecutive intravitreal injections of aflibercept (IVA) repeated monthly with a follow-up period of at least one year. The outcomes were evaluated in terms of reported functional and anatomical improvement of the macula, as reflected by changes in visual acuity and macular thickness measured by Optical Coherence Tomography (OCT). In addition, for safety assessment, all reported local and general adverse effects were analyzed.

RESULTS

All studies showed an overall significant anatomical and functional improvement. In patients with the 5 IVA monthly at the beginning of the therapy, the visual gain at 52 weeks varied widely between 5 and 18.9 EDRS letters, with a mean value of 9.48 letters. The higher gain was obtained in treatment naïve patients, with worse VA and increased CST at baseline. The lower gain was obtained in patients previously treated with anti-VEGF. Anti-Platelet Trialists' Collaboration-defined arterial thromboembolic events were not statistically different between the aflibercept group and the laser group.

CONCLUSIONS

Intravitreal aflibercept therapy provides significant improvement in visual acuity and a good safety profile. Randomized studies are needed to document the optimal frequency of intravitreal injections for optimal treatment.

Treat-and-Extend Versus Alternate Dosing Strategies with Anti-Vascular Endothelial Growth Factor agents to treat Center Involving Diabetic Macular Edema: A Systematic Review and Meta-analysis of 2346 Eyes

Anti-vascular endothelial growth factor (Anti-VEGF) agents are the standard of care for diabetic macular edema (CI-DME) with vision loss. They are commonly administered using several treatment protocols, including fixed, pro re nata (PRN) and treat-and-extend (T&E) regimens. Because of the lack of evidence defining an ideal treatment paradigm, we systematically compared T&E with fixed or PRN regimens. Visual acuity improvement was similar when comparing T&E to fixed or PRN dosing at 12 and 24 months. Regarding anatomic outcomes, no significant difference was found between T&E and fixed regimens for central retinal thickness or central subfoveal thickness at 12 and 24 months. Similarly, no significant difference was found for central retinal thickness at 12 months for T&E versus PRN regimen. Regarding total number of injections, no significant difference existed between T&E versus fixed regimens at 12 months. PRN regimens delivered fewer injections compared to T&E regimens at 12 months. The results of this analysis support that visual acuity and anatomic outcomes at 12 and 24-months are similar between T&E with either fixed or PRN regimens. More head-to-head trials comparing T&E versus fixed and PRN dosing are needed to provide visual and functional outcome data beyond year 2. PROSPERO Registration: CRD42021249362.

Mesenchymal stem cell-derived extracellular vesicles for cell-free therapy of ocular diseases

Mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) have noticeably attracted clinicians' attention in treating ocular diseases. As the paracrine factor of MSCs and an alternative for cell-free therapies, MSC-EVs can be conveniently dropped over the ocular surface or diffused through the retina upon intravitreal injection, without increasing the risks of cellular rejection and tumor formation. For clinical translation, a standardized and scalable production, as well as reprogramming the MSC-EVs, are highly encouraged. This review aims to assess the potential approaches for EV production and functional modification, in addition to summarizing the worldwide clinical trials initiated for various physiological systems and the specific biochemical effects of MSC-EVs on the therapy of eye diseases. Recent advances in the therapy of ocular diseases based on MSC-EVs are reviewed, and the associated challenges and prospects are discussed as well.

One-Year Outcome of Intravitreal Tissue Plasminogen Activator, Ranibizumab, and Gas Injections for Submacular Hemorrhage in Polypoidal Choroidal Vasculopathy

This study investigated one-year outcomes of treatment with one session of intravitreal recombinant tissue plasminogen activator, ranibizumab, and gas injections for submacular hemorrhage secondary to polypoidal choroidal vasculopathy (PCV). An extended study of a previous prospective trial of this treatment modality in PCV patients was conducted in 64 patients (64 eyes). Early Treatment Diabetic Retinopathy Study (ETDRS) score, central retinal thickness (CRT), and central pigment epithelial detachment thickness (CPEDT) before and 1, 3, and 12 months after treatment were analyzed. Mean ETDRS score increased from 58 at baseline to 64 letters (p = 0.0122), CRT decreased from 543 to 192 μm (p < 0.0001), and CPEDT decreased from 161 to 103 μm (p = 0.0668) at 3 months and were maintained until 12 months. Complications requiring reoperation occurred within one month in four eyes. Recurrence was observed in 46 eyes (72%), and 1.6 ± 1.5 (0−7) intravitreal aflibercept injections were given pro re nata. Univariate and multivariate analyses identified CPEDT as the pre- and post-treatment factor affecting 12-month ETDRS score (p < 0.0001). Improved visual acuity stabilized 3 months after treatment. Although 72% of patients experienced recurrence, an average of 1.6 aflibercept injections/patient maintained visual acuity up to 12 months. CPEDT was the most important factor associated with visual outcome.

Comparison Between L-312 Hydrophobic-Hydrophilic Acrylate and US-860 UV Hydrophilic Acrylate IOL Opacification Characteristic

Objective

To compare opacity characteristics of US-860 UV and L-312 IOL, and report the phenomenon of glistenings in hydrophobic-hydrophilic acrylic IOLs.

Setting

Qingdao Eye Hospital.

Design

Experimental study.

Methods

Four medical records (4 eyes) of patients with L-312 or US-860 UV IOL opacification reporting decreased or lost vision who underwent IOL explanation between 2019 and 2021 were reviewed. Explanted IOLs were analyzed by slit-lamp examination, confocal microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) at Qingdao Eye Hospital and Qingdao university of science and technology.

Results

The 4 explanted IOLs were represented by 2 hydrophilic acrylic designs. The preoperative mean corrected distance visual acuity changed from 1.84 ± 1.09 logarithm of the minimum angle of resolution (log MAR) to 0.20 ± 0.03 log MAR postoperatively except case 3. The mean interval of the L-312 IOL was 56.67 ± 14.19 months (range 44 to 72 months), and the interval of the US-860 UV IOL was 27 months. Morphological findings were surface, subsurface calcifications of the US-860 UV IOL material, and the optical region of L-312 IOLs are teeming with a great number of vacuoles by light microscope, scanning electron microscope and Energy Dispersive X-ray Spectral.

Conclusion

The cause of US-860 UV opacification was primary calcification, and vacuoles resulted in L-312 IOL opacification.

Examining the Relationship Between Diabetic Macular Edema, and Obstructive Sleep Apnea

Purpose

This prospective cohort study examined the relationship between diabetic macular edema (DME), diabetic retinopathy (DR) and obstructive sleep apnea (OSA) in patients after 1 year of treatment with anti-VEGF injection and/or continuous positive airway pressure (CPAP).

Patients and Methods

The study included adults with type 1 or 2 diabetes mellitus with diabetic retinopathy. Polysomnography metrics were measured at baseline. Ophthalmologic metrics were measured at baseline, six-month (6m) and twelve-month (12m) follow-up. All DME+ patients received standard care, and all OSA+ patients were advised continuous positive airway pressure (CPAP). Logistic regression between DR severity and OSA severity was performed. Analysis of variance (ANOVA) was performed between subgroups.

Results

Seventy-four eyes of 49 patients with DR were included. Prevalence of OSA was significantly higher in the DME+ group (70.7%) than DME- group (42.4%, p < 0.05). A significantly lower average minimum SaO₂ was noted in OSA+DME+ (81.74%) than OSA+DME- eyes (88.23%, p < 0.05). Logistic regression analysis of ophthalmological and sleep metrics showed no correlation between DR and OSA severity. CPAP adherence was 20% (6/30) in the OSA+DME+ cohort and 36% (5/14) in the OSA+DME- cohort. At 12m, CPAP-adherent OSA+DME+ showed significantly lower DR severity score (1.00 ± 0.0) than CPAP non-adherent OSA+DME+ (1.36 ± 0.80, p = 0.042). No significant patterns were noted for visual acuity and mean central retinal thickness.

Conclusion

DME is associated with the presence of OSA. Minimum SaO₂ is a significant OSA clinical variable for DME. DR severity is not associated with OSA severity. CPAP coupled with intravitreal anti-VEGF therapy may be helpful for reducing DR severity in DME+ eyes. Presence of OSA may diminish intravitreal anti-VEGF efficacy on anatomical (mean CRT) and functional (VA) outcomes of DME.

Secretomes as an emerging class of bioactive ingredients for enhanced cosmeceutical applications

Skin aging is predominantly caused by either intrinsic or extrinsic factors, leading to undesirable skin features. Advancements in both molecular and cellular fields have created possibilities in developing novel stem cell-derived active ingredients for cosmeceutical applications and the beauty industry. Mesenchymal stromal cell (MSC)-derived secretomes or conditioned media hold great promise for advancing skin repair and regeneration due to the presence of varying cytokines. These cytokines signal our cells and trigger biological mechanisms associated with anti-inflammatory, antioxidant, anti-aging, proliferative, and immunomodulatory effects. In this review, we discuss the potential of MSC secretomes as novel biomaterials for skincare and rejuvenation by illustrating their mechanism of action related to wound healing, anti-aging, and whitening properties. The advantages and disadvantages of secretomes are compared to both plant-based and animal-derived extracts. In addition, this paper reviews the current safety standards, regulations, market products and research work related to the cosmeceutical applications of secretomes along with strategies to maintain and improve the therapeutic efficacy and production of secretomes. The future outlook of beauty industry is also presented. Lastly, we highlight significant challenges to be addressed for the clinical realization of MSC secretomes-based skin therapies as well as providing perspectives for the future direction of secretomes.

Optimization of adipose tissue-derived mesenchymal stromal cells transplantation for bone marrow repopulation following irradiation

BACKGROUND

Bone marrow (BM) suppression is one of the most common side effects of radiotherapy and the primary cause of death following exposure to irradiation. Despite concerted efforts, there is no definitive treatment method available. Recent studies have reported using mesenchymal stromal cells (MSCs), but their therapeutic effects are contested.

AIM

We administered and examined the effects of various amounts of adipose-derived MSCs (ADSCs) in mice with radiation-induced BM suppression.

METHODS

Mice were divided into three groups: Normal control group, irradiated (RT) group, and stem cell-treated group following whole-body irradiation (WBI). Mouse ADSCs (mADSCs) were transplanted into the peritoneal cavity either once or three times at 5 × 105 cells/200 μL. The white blood cell count and the levels of, plasma cytokines, BM mRNA, and BM surface markers were compared between the three groups. Human BM-derived CD34+ hematopoietic progenitor cells were co-cultured with human ADSCs (hADSCs) or incubated in the presence of hADSCs conditioned media to investigate the effect on human cells in vitro.

RESULTS

The survival rate of mice that received one transplant of mADSCs was higher than that of mice that received three transplants. Multiple transplantations of ADSCs delayed the repopulation of BM hematopoietic stem cells. Anti-inflammatory effects and M2 polarization by intraperitoneal ADSCs might suppress erythropoiesis and induce myelopoiesis in sub-lethally RT mice.

CONCLUSION

The results suggested that an optimal amount of MSCs could improve survival rates post-WBI.

Challenges to Gene Editing Approaches in the Retina

Retinal gene therapy has recently been at the cutting edge of clinical development in the diverse field of genetic therapies. The retina is an attractive target for genetic therapies such as gene editing due to the distinctive anatomical and immunological features of the eye, known as immune privilege, so that inherited retinal diseases (IRDs) have been studied in several clinical studies. Thus, rapid strides are being made toward developing targeted treatments for IRDs. Gene editing in the retina faces a group of heterogenous challenges, including editing efficiencies, off-target effects, the anatomy of the target organ, immune responses, inactivation, and identifying optimal application methods. As clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated nuclease (Cas) based technologies are at the forefront of current gene editing advances, their specific editing efficiency challenges and potential off-target effects were assessed. The immune privilege of the eye reduces the likelihood of systemic immune responses following retinal gene therapy, but possible immune responses must not be discounted. Immune responses to gene editing in the retina may be humoral or cell mediated, with immunologically active cells, including microglia, implicated in facilitating possible immune responses to gene editing. Immunogenicity of gene therapeutics may also lead to the inactivation of edited cells, reducing potential therapeutic benefits. This review outlines the broad spectrum of potential challenges currently facing retinal gene editing, with the goal of facilitating further advances in the safety and efficacy of gene editing therapies.

Monthly Alternating Injections of Aflibercept and Bevacizumab for Neovascular Age-Related Macular Degeneration

We investigated the efficacy of monthly alternating injections of aflibercept and bevacizumab (MAAB) for maintenance treatment in patients with neovascular age-related macular degeneration (AMD) who showed improvement with the initial monthly injections but presented with rapid worsening after conversion to bimonthly injections. We included 72 patients with neovascular AMD who showed improvement with loading injections of aflibercept. For maintenance treatment, bevacizumab was administered every alternate month between the bimonthly aflibercept injections in 24 (33.3%) eyes showing worsening (MAAB group). The other eyes were treated with aflibercept (BiA group) bimonthly. Baseline low retinal thickness, thick choroid, and presence of intraretinal fluid were associated with worsening after extending the injection intervals. Visual improvement was lower in the MAAB group than in the BiA group, but the final visual outcomes were comparable. Additional bevacizumab stabilized the early fluctuation of retinal thickness, thus maintaining long-term visual stability without increasing the risk of geographic atrophy or disciform scar until the second year. Previously treated eyes or those with polypoidal choroidal vasculopathy responded less to the initial loading doses and showed worsening under the bimonthly regimen. MAAB was effective in preventing anatomical and functional deterioration when bimonthly aflibercept proved insufficient for the maintenance treatment of neovascular AMD.

Optical coherence tomography and imaging biomarkers as outcome predictors in diabetic macular edema treated with dexamethasone implant

In this retrospective, multicenter study, we determined the predictive value of imaging biomarkers in diabetic macular edema (DME) outcomes following dexamethasone (DEX) implant(s). Sixty-seven eyes of 47 patients' best-corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography (OCT) before and after intravitreal DEX implants were evaluated. Baseline imaging biomarkers were graded using fundus photography and OCT, and the predictive value of biomarkers for significant treatment effects at six months was analyzed. Six months after 2.0 ± 0.8 (mean ± SD) DEX implants, 35 (52%) and 16 (24%) eyes had CFT reduction ≥ 10% from baseline and decreased to < 300 µm, respectively. BCVA improved ≥ 3 lines in 15 (22%) and remained stable in 38 (57%) eyes. At six months, eyes with severe intraretinal cyst (IRC), abundant hyperreflective dots (HRD), and moderate or severe hard exudate had a significantly higher chance of CFT reduction ≥ 10%. Eyes with abundant HRD at baseline and those underwent three DEX implants were more likely to achieve CFT < 300 µm. Eyes with DME and severe IRC, abundant HRD, or moderate-to-severe hard exudate at baseline were more likely to show a significant reduction in CFT six months after DEX implant.

YOSEMITE and RHINE

Purpose

Faricimab is a novel anti–angiopoietin-2 and anti–vascular endothelial growth factor (VEGF) bispecific antibody with high affinities and specificities for both VEGF and angiopoietin-2. It is postulated that targeting angiogenic factors and inflammatory pathways in addition to the VEGF pathway will increase treatment durability and improve outcomes. The phase 3 YOSEMITE (ClinicalTrials.gov identifier, NCT03622580) and RHINE (ClinicalTrials.gov identifier, NCT03622593) trials are designed to assess efficacy, safety, and durability of faricimab compared with aflibercept in patients with diabetic macular edema (DME). The trials evaluate a personalized treatment interval (PTI) approach to address heterogeneity in treatment response among patients with DME.

Design

Two identically designed, global, double-masked, randomized, controlled phase 3 trials (YOSEMITE and RHINE).

Participants

Adults with center-involving DME secondary to type 1 or 2 diabetes mellitus.

Methods

These studies were designed to evaluate 3 treatment groups: faricimab 6.0 mg dosed either at fixed dosing every 8 weeks after initial treatment with 6 intravitreal doses at 4-week intervals, or faricimab 6.0 mg dosed according to PTI after initial treatment with 4 every-4-week doses, compared with aflibercept 2.0 mg dosed every 8 weeks after 5 initial every-4-week doses. The primary end point of the studies was change from baseline in best-corrected visual acuity at 1 year, averaged over weeks 48, 52, and 56. Secondary end points included anatomic, durability, and patient-reported outcomes. Safety outcomes included incidence and severity of ocular and nonocular adverse events. The PTI is a protocol-defined flexible regimen based on the treat-and-extend concept, which allowed up to every-16-week adjustable dosing based on objective and standardized criteria. The PTI design aimed to maximize therapeutic results while minimizing treatment burden.

Main Outcome Measures

We describe the rationale for the study design and the novel PTI (up to every-16-week adjustable dosing) approach for treatment with faricimab.

Results

YOSEMITE and RHINE enrolled 940 and 951 patients, respectively. Results from each study will be reported separately.

Conclusions

YOSEMITE and RHINE were the first registrational trials in retinal disease to incorporate an objective PTI regimen, allowing for up to every-16-week adjustable dosing with a dual angiopoietin-2 and VEGF-A inhibitor, faricimab 6.0 mg, for treatment of DME.

Insights into pathological mechanisms and interventions revealed by analyzing a mathematical model for cone metabolism

This work analyzes a mathematical model for the metabolic dynamics of a cone photoreceptor, which is the first model to account for energy generation from fatty acids oxidation of shed photoreceptor outer segments (POS). Multiple parameter bifurcation analysis shows that joint variations in external glucose, the efficiency of glucose transporter 1 (GLUT1), lipid utilization for POS renewal, and oxidation of fatty acids affect the cone’s metabolic vitality and its capability to adapt under glucose-deficient conditions. The analysis further reveals that when glucose is scarce, cone viability cannot be sustained by only fueling energy production in the mitochondria, but it also requires supporting anabolic processes to create lipids necessary for cell maintenance and repair. In silico experiments are used to investigate how the duration of glucose deprivation impacts the cell without and with a potential GLUT1 or oxidation of fatty acids intervention as well as a dual intervention. The results show that for prolonged duration of glucose deprivation, the cone metabolic system does not recover with higher oxidation of fatty acids and requires greater effectiveness of GLUT1 to recover. Finally, time-varying global sensitivity analysis (GSA) is applied to assess the sensitivity of the model outputs of interest to changes and uncertainty in the parameters at specific times. The results reveal a critical temporal window where there would be more flexibility for interventions to rescue a cone cell from the detrimental consequences of glucose shortage.

Central retinal thickness changes and risk of neovascular glaucoma after intravitreal bevacizumab injection in patients with central retinal vein occlusion

This retrospective study evaluated changes in the central retinal thickness (CRT) and the risk factors for neovascular glaucoma (NVG) after intravitreal bevacizumab injection under a pro re nata (PRN) regimen for macular oedema in 57 eyes with central retinal vein occlusion (CRVO). The clinical characteristics at the time of NVG diagnosis were assessed, and baseline and final clinical characteristics and mean CRT values at 1-, 3-, and 6-month follow-up evaluations were recorded. The incidence of NVG was 21.1%, with the neovascular group (12 eyes) showing poor baseline and final visual acuity, a higher incidence of baseline ischaemic-type CRVO and subretinal fluid, a higher mean CRT at the 1-month follow-up, and a higher number of intravitreal bevacizumab injections during the 6-month follow-up. Nine eyes with NVG (75%) showed a mean CRT < 300 μm at the time of diagnosis. An ischaemic CRVO and higher CRT at the 1-month follow-up were related to the development of NVG in the multivariate analysis. Thus, NVG development in CRVO patients treated with intravitreal bevacizumab injections was associated with an ischaemic CRVO and elevated CRT at the 1-month follow-up; PRN bevacizumab regimens based on CRT or control of macular oedema did not completely prevent NVG development.

One-year outcomes of the treat-and-extend regimen using aflibercept for the treatment of diabetic macular edema

BACKGROUND

Optimal regimen using intravitreal aflibercept injections for diabetic macular edema (DME) in clinical practice remains to be elucidated. The purpose of this study is to evaluate a treat-and-extend (TAE) approach using intravitreal aflibercept in participants with center-involved DME.

METHODS

A 52-week open-label, prospective, multicenter, interventional study was conducted between August 2015 and November 2017 in Taiwan. Adults with diabetes mellitus and center-involved DME who have best-corrected visual acuity (BCVA) of 73 to 24 Early Treatment Diabetic Retinopathy Study letters and central retinal thickness (CRT) >300 μm were included. Participants received five monthly loading doses of 2 mg intravitreal aflibercept, followed by a TAE regimen with a four-week increment/decrement interval over 48 weeks; the maximum interval was 12 weeks. Main outcomes included changes in BCVA and CRT from baseline to week 52, additional anatomical outcomes, and treatment burden parameters.

RESULTS

Forty-five participants with mean (SD) age of 63.7 (8.3) years were analyzed. At baseline, mean (SD) BCVA and CRT were 58.3 (11.9) letters and 434.4 (116.8) μm, respectively. Changes from baseline in BCVA and CRT were +8.3 (9.3) letters and -138.2 (150.0) μm (both p < 0.001) at week 52, respectively. In addition, 22% (10/45) of patients gained ≥15 letters, 14% (6/44) of participants achieved ≥2-level improvement in diabetic retinopathy severity, and 51% (23/45) demonstrated dry retina at week 52 compared with 13% (6/45) at baseline. In total, 87% (39/45) of patients reached disease stability, entering TAE at week 20. Subsequently, 89% (40/45) of patients reached maximum interval at week 52. Mean (SD) number of injections was 7.7 (1.5) over a period of 52 weeks.

CONCLUSION

This straightforward and practical TAE regimen using intravitreal aflibercept injections resulted in favorable clinical outcomes with minimal treatment burden for DME at week 52.

Treat-and-Extend vs. Pro Re Nata Regimen of Ranibizumab for Diabetic Macular Edema—A Two-Year Matched Comparative Study

Purpose

To compare 2-year treatment outcomes of ranibizumab using treat-and-extend (T&E) or pro re nata (PRN) regimens for diabetic macular edema (DME) in clinical settings.

Methods

We retrospectively enrolled 34 patients (34 eyes) with DME treated with ranibizumab using the T&E regimen, and 34 patients (34 eyes) treated with ranibizumab using the PRN regimen and matched to cases in the treat-and-extend group by baseline best-corrected visual acuity (BCVA) and central foveal thickness (CFT). BCVA and CFT changes, number of injections and recurrence of macular edema over 2 years were compared between the groups.

Results

The average BCVA gain in the T&E and PRN groups was 16.2 and 7.6 ETDRS letters at 2 years (p = 0.011), respectively. The mean CFT reduction was 145.5 ± 127.3 and 97.3 ± 152.5 μm in the T&E and PRN groups at 2 years (p = 0.035), respectively. The T&E group had a higher proportion of patients with BCVA gain ≥ 15 letters at months 18 (p = 0.015) and 24 (p = 0.029) than the PRN group. During the 2-year treatment periods, the T&E group received more injections than the PRN group (11.0 ± 3.2 vs. 6.2 ± 2.0; p < 0.001), while the PRN group had more recurrence of macular edema than the T&E group (71 vs. 41%; p = 0.015).

Conclusions

After 2-year ranibizumab treatment for DME, better visual and anatomical improvement and less recurrence of macular edema were achieved in the T&E group, with more injections administered.

Assessment of intravitreal anti-VEGF drugs and dexamethasone for retinal diseases in real world setting: A multi-centre prospective study from Southern Italy

Describe drug utilisation and clinical outcomes of intravitreal anti-VEGF drug and dexamethasone use in the real-world setting in Southern Italy using data from multi-centre study of retinal disease. Clinical data of retinal disease patients treated with anti-VEGF drugs and dexamethasone implant in 6 out-patient ophthalmology centres from Southern Italy were collected by means of an electronic case report form. Patients receiving at least one intravitreal injection/implant of the study drugs were followed for up to two years and described in terms of demographics and clinical characteristics. Drug utilisation patterns were described. A sign-rank test was used to compare clinical data on visual acuity and other ophthalmic parameters from baseline at different follow-up times for each indication. Data from 1327 patients was collected. Most patients were diagnosed with age-related macular degeneration (AMD) (660, 49.7%), followed by diabetic macular oedema (423, 31.9%), retinal vein occlusion (164, 12.3%), and myopic choroidal neovascularization (80, 6.0%). Patients were followed for a median of 10.3 months (interquartile range: 3.6 - 24.7 months). Mean patient age was 69.7 (±10.9) years and 54.2% were males. Ranibizumab (55.4%) and aflibercept (27.5%) were the most commonly used drugs. Baseline visual acuity significantly improved by about 0.05 to 0.1 logMAR at all follow-up times for AMD and RVO but less consistently for the other diseases. Intravitreal ranibizumab use accounted for half of all treatment for retinal diseases in a Southern Italian out-patient setting. Patients treated with anti-VEGF drugs for AMD and RVO in Southern Italy experienced significant improvement in VA.

Efficacy and safety of aflibercept therapy for diabetic macular edema: A systematic review and meta-analysis

Purpose:

To assess the real-world efficacy and safety of aflibercept for the treatment of diabetic macular edema (DME).

Methods:

A systematic search was conducted across multiple databases. Articles were included if participants had DME and received aflibercept treatment for a minimum of 52 ± 4 weeks. Primary outcomes included changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT). A risk of bias assessment of studies was completed, pooled estimates were obtained, and a meta-regression was performed. Information on adverse events was collected.

Results:

The search yielded 2112 articles, of which 30 were included. Aflibercept was more effective than laser photocoagulation functionally (12-month BCVA-weighted mean difference [WMD] = 10.77 letters, P < 0.001; 24 months = 8.12 letters, P < 0.001) and anatomically (12-month CMT WMD = –114.12 μm, P < 0.001; 24 months = –90.4 μm, P = 0.004). Compared to bevacizumab, aflibercept was noninferior at improving BCVA at 12 months (WMD = 1.71 letters, P = 0.34) and 24 months (WMD = 1.58 letters, P = 0.083). One study found that aflibercept was more effective than bevacizumab anatomically at 1 and 2 years (P < 0.001 at 12 and 24 months). Compared to ranibizumab, aflibercept rendered a greater improvement in BCVA at 1 year (WMD = 1.76 letters, P = 0.001), but not 2 years (WMD = 1.66 letters, P = 0.072). CMT was not significantly different between both therapies at 12 months (WMD = −14.30 μm, P = 0.282) and 24 months (P = 0.08). One study reported greater functional improvement with aflibercept compared with dexamethasone (P = 0.004), but inferiority in reducing CMT (P < 0.001). Meta-regression analysis demonstrated that dosing schedule was found to impact outcomes at 12 and 24 months, while study design and sample size did not impact outcomes at 12 months. There were minimal safety concerns using aflibercept therapy.

Conclusions:

Aflibercept is a safe and effective therapy option for DME in the clinical setting, performing superiorly to laser photocoagulation. Evidence regarding comparisons with bevacizumab, ranibizumab, and dexamethasone is mixed and limited.

Establishing in vitro and in vivo Co-culture Models of Staphylococcus epidermidis and Enterococcus faecalis to Evaluate the Effect of Topical Fluoroquinolone on Ocular Microbes

Purpose: To establish in vitro and in vivo ocular co-culture models of Staphylococcus epidermidis and Enterococcus faecalis and to study how various concentrations of moxifloxacin affect the survival of these two endophthalmitis-causing bacteria. Methods: Standard strains of S. epidermidis and E. faecalis were used. Color detection agar plates were employed to distinguish their colonies. To establish the in vitro and in vivo co-culture models, S. epidermidis and E. faecalis were co-cultivated at different ratios for various periods. For the in vivo model, various volumes and concentrations of either a mono-culture or co-culture were inoculated into the lower conjunctival sac of rabbits. Finally, the newly developed in vitro and in vivo co-culture models were subjected to the moxifloxacin treatment to access its effect on S. epidermidis and E. faecalis. Results: When S. epidermidis and E. faecalis were cultured separately in tryptic soy broth, their growth peaked and plateaued at approximately 16 and 6 h, respectively. When they were co-cultured, the growth peak of S. epidermidis got delayed, whereas the growth peak of E. faecalis did not change. The number of E. faecalis was significantly higher in the co-culture than that in the mono-culture. Treatment with moxifloxacin in the in vitro co-culture model rapidly decreased the number of S. epidermidis cells at doses ≥ 0.125 μg/ml. In contrast, the number of E. faecalis did not change significantly up to 16 μg/ml moxifloxacin. In in vivo co-culture (at 1:1), the S. epidermidis count decreased in a pattern similar to that seen in in vivo mono-culture and was barely detectable at 24 h after inoculation. In contrast, the of E. faecalis count increased up to 16 h and then decreased. When moxifloxacin was applied (zero, one, or two times) to this model, the S. epidermidis count decreased in proportion to the number of treatments. In contrast, the E. faecalis count increased with moxifloxacin treatment. Conclusions: The in vitro and in vivo co-culture models of S. epidermidis and E. faecalis were established to determine the influence of moxifloxacin eye drops on these bacteria. The results clearly show that the moxifloxacin eye drops can make E. faecalis dominant on the ocular surface.

Retinal displacement and intraretinal structural changes after idiopathic macular hole surgery

PURPOSE

To investigate the correlations of thickness of three retinal layers with retinal displacement after idiopathic macular hole surgery.

STUDY DESIGN

Retrospective, consecutive, case series.

METHODS

42 eyes of 42 patients undergoing macular hole surgery with internal limiting membrane peeling were studied. Retinal distance was measured with near-infrared images between the optic nerve and the intersection of retinal vessels at four quadrants. Retinal thicknesses of inner retinal layer, inner nuclear layer and outer retinal layer were measured 1000 μm away from the central fovea using Spectralis.

RESULTS

Retinal distances other than the nasal quadrant decreased postoperatively (p < 0.001). Retinal displacement (%) correlated significantly with the change in inner nuclear layer thickness in the temporal sector at 1, 3, and 6 months, in the superior sector at 2 weeks, 1, and 6 months, and in the inferior sector at 3 and 6 months postoperatively (r = 0.319-0.570, p < 0.001-0.040), but not in the inner or outer retinal layers.

CONCLUSION

Internal limiting membrane peeling for macular hole enhances retinal displacement toward the optic disc, whose distances correlate with the changes in inner nuclear layer thickness.

Treatment of Macular Edema in Vascular Retinal Diseases: A 2021 Update

Macular edema (ME) is associated with various conditions; however, the main causes of ME are retinal vein occlusion (RVO) and diabetes. Laser photocoagulation, formerly the gold standard for the treatment of ME, has been replaced by anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections. Despite its efficiency, this treatment requires frequent injections to preserve the outcomes of anti-VEGF therapy, and as many patients do not sufficiently respond to the treatment, ME is typically a chronic condition that can lead to permanent visual impairment. Generalized recommendations for the treatment of ME are lacking, which highlights the importance of reviewing treatment approaches, including recent anti-VEGFs, intravitreal steroid implants, and subthreshold micropulse lasers. We reviewed relevant studies, emphasizing the articles published between 2019 and 2021 and using the following keywords: macular edema, diabetic macular edema, retinal vein occlusion, laser photocoagulation, anti-VEGF, and intravitreal injections. Our results revealed that a combination of different treatment methods may be beneficial in resistant cases. Additionally, artificial intelligence (AI) is likely to help select the best treatment option for patients in the near future.

First we eat, then we do everything else: The dynamic metabolic regulation of efferocytosis

Clearance of apoptotic cells, or "efferocytosis," is essential for diverse processes including embryonic development, tissue turnover, organ regeneration, and immune cell development. The human body is estimated to remove approximately 1% of its body mass via apoptotic cell clearance daily. This poses several intriguing cell metabolism problems. For instance, phagocytes such as macrophages must induce or suppress metabolic pathways to find, engulf, and digest apoptotic cells. Then, phagocytes must manage the potentially burdensome biomass of the engulfed apoptotic cell. Finally, phagocytes reside in complex tissue architectures that vary in nutrient availability, the types of dying cells or debris that require clearance, and the neighboring cells they interact with. Here, we review advances in our understanding of these three key areas of phagocyte metabolism. We end by proposing a model of efferocytosis that integrates recent findings and establishes a new paradigm for testing how efferocytosis prevents chronic inflammatory disease and autoimmunity.

Relationship between Cataract Surgery and Mortality in Elderly Patients with Cataract: Nationwide Population-Based Cohort Study in South Korea

We aimed to investigate the relationship between cataract surgery and all-cause and cause-specific mortality in Korean elderly patients with cataract using the Korean National Health Insurance Service-Senior cohort database. Elderly patients (≥60 years) diagnosed with cataract from 2002 through 2012 were included. The baseline characteristics included demographics and systemic and ocular comorbidities. Adjusted Cox regression models with time-varying covariates for cataract surgery were used to assess the relationship between cataract surgery and mortality. The study cohort included 241,062 patients, of whom 127,941 were in the cataract surgery group and 113,121 were in the cataract diagnosis group. The incidence of all-cause mortality was 3.62 deaths/100 person-years and 3.19 deaths/100 person-years in the cataract surgery and cataract diagnosis groups, respectively. Cataract surgery was associated with a decreased hazard of all-cause mortality after adjusting for demographics as well as systemic and ocular comorbidities (hazard ratio (HR), 0.93; p < 0.001). A protective association was noted between cataract surgery and mortality from vascular (HR, 0.92; p < 0.001) or neurologic (HR, 0.64; p < 0.001) causes. Patients with cataract who were 85 years of age and older, women, those who had lower income, and a Charlson comorbidity index score of 5 or more, or those without glaucoma revealed the largest reductions in mortality hazards resulting from cataract surgery.

Ocular Delivery of Predatory Bacteria with Cryomicroneedles Against Eye Infection

The development of potent antibiotic alternatives with rapid bactericidal properties is of great importance in addressing the current antibiotic crisis. One representative example is the topical delivery of predatory bacteria to treat ocular bacterial infections. However, there is a lack of suitable methods for the delivery of predatory bacteria into ocular tissue. This work introduces cryomicroneedles (cryoMN) for the ocular delivery of predatory Bdellovibrio bacteriovorus (B. bacteriovorus) bacteria. The cryoMN patches are prepared by freezing B. bacteriovorus containing a cryoprotectant medium in a microneedle template. The viability of B. bacteriovorus in cryoMNs remains above 80% as found in long-term storage studies, and they successfully impede the growth of gram-negative bacteria in vitro or in a rodent eye infection model. The infection is significantly relieved by nearly six times through 2.5 days of treatment without substantial effects on the cornea thickness and morphology. This approach represents the safe and efficient delivery of new class of antimicrobial armamentarium to otherwise impermeable ocular surface and opens up new avenues for the treatment of ocular surface disorders.

Aqueous humor analyses of diabetic macular edema patients with subretinal fluid

We identified treatment-naïve diabetic macular edema (DME) patients with or without subretinal fluid (SRF). We compared their baseline characteristics: aqueous concentrations of interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, and IL-17, as well as tumor necrosis factor-α, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF). We also compared fundus and optical coherence tomography (OCT) findings, and responsiveness to anti-VEGF treatments. Of 67 DME patients, 18 (26.87%) had SRF. Compared to the no SRF group, the SRF group had significantly higher levels of IL-6, IL-8, VEGF, and PlGF in aqueous humor. After grouping according to diabetic retinopathy stage, non-proliferative diabetic retinopathy (NPDR) patients with SRF had higher aqueous levels of IL-6 and IL-8, compared to NPDR patients without SRF. Moreover, proliferative diabetic retinopathy (PDR) patients with SRF had higher aqueous levels of VEGF and PlGF, compared to PDR patients without SRF. Fundus and OCT analyses revealed that the SRF group had a greater proportion of patients with succinate or patch-shaped hard exudates involving the macula, and greater central subfield thickness (CST) at baseline. After 6 months of anti-VEGF treatments, the SRF group showed better responsiveness in terms of CST; however, visual acuity was not correlated with responsiveness. Considering higher aqueous levels of VEGFs and pro-inflammatory cytokines, SRF could be a biomarker related to diabetic retinopathy activity. DME patients with SRF showed better anatomical responsiveness to anti-VEGF treatments, but did not show better functional improvement on short-term evaluation compared to those of DME patients without SRF.

Contamination of multi dose eyedrops in the intra and perioperative context

In this study, we examined the rate of contamination of multi-dose ophthalmic solutions in the operating theatre and the underlying risk for infection by examining the microbiological load on the tips of the dispenser bottles. A total of 245 samples of eye drop bottles were collected and analysed between June 2018 and January 2019. All were collected in the operating theatre of the University Eye Hospital Hamburg-Eppendorf. Contamination of the dropper tip occurred in 2% of the samples. Although the prevalence of contamination was low, the results of this study reveal the possibility of contamination of multi-dose eyedrops even when used by health care professionals in the controlled environment of an operating theatre. Following these results, we recommend the use of single-dose eyedrops in the pre- and intraoperative context.

Exosomes as a New Delivery Vehicle in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a type of chronic relapsing inflammatory disease. The pathogenesis of IBD is still unclear, which may involve environmental factors, genetic factors, intestinal microbiota disorder, and abnormal immune responses. Exosomes (30–150 nm) are found in various body fluids, including blood, saliva, urine, and cerebrospinal fluid. Exosomes mediate intercellular communication and regulate cell biological activity by carrying non-coding RNAs, proteins, and lipids. There is evidence that exosomes are involved in the pathogenesis of IBD. In view of the important roles of exosomes in the pathogenesis of IBD, this work systematically reviews the latest research progress of exosomes in IBD, especially the roles of exosomes as non-coding RNA delivery systems in the pathogenesis of IBD, including a disordered immune response, barrier function, and intestinal microbiota. The review will help to clarify the pathogenesis of IBD and explore new diagnostic markers and therapeutic targets for patients with IBD.

Metabolic rescue of cone photoreceptors in retinitis pigmentosa

Retinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. It is a leading cause of visual disability, with an incidence of ~1 in 7000 persons. Although most RP is nonsyndromic, 20%-30% of patients with RP also have an associated nonocular condition. The gene mutations responsible for RP occur overwhelmingly in rod photoreceptors. Visual loss frequently begins with night blindness in adolescence, followed by concentric visual field loss, reflecting the principal dysfunction of rod photoreceptors. Although the visual disability from rod dysfunction is significant, it is the subsequent loss of central vision later in life due to cone degeneration that is catastrophic. Until recently, the reason for cone dysfunction in RP was unknown. However, it is now recognized that cones degenerate, losing outer segment (OS) synthesis and inner segment (IS) disassembly because of glucose starvation following rod demise. Rod OS phagocytosis by the apical microvilli of retinal pigment epithelium is necessary to transport glucose from the choriocapillaris to the subretinal space. Although cones lose OS with the onset of rod degeneration in RP, regardless of the gene mutation in rods, cone nuclei remain viable for years (i.e. enter cone dormancy) so that therapies aimed at reversing glucose starvation can prevent and/or recover cone function and central vision.

Cyclodextrins Allow the Combination of Incompatible Vancomycin and Ceftazidime into an Ophthalmic Formulation for the Treatment of Bacterial Keratitis

Ceftazidime (CZ) and vancomycin (VA) are two antibiotics used to treat bacterial keratitis. Due to their physical incompatibility (formation of a precipitate), it is not currently possible to associate both molecules in a single container for ophthalmic administration. We firstly characterized the incompatibility then investigated if 2-hydroxypropyl-beta (HPβCD) and 2-hydroxypropyl-gamma cyclodextrins (HPγCD) could prevent this incompatibility. The impact of pH on the precipitation phenomena was investigated by analysing the supernatant solution of the mixture using high performance liquid chromatography. A characterization of the inclusion of CZ with HPγCD using ¹H nuclear magnetic resonance (NMR), and VA with HPβCD using ¹H-NMR and a solubility diagram was performed. A design of experiment was built to determine the optimal conditions to obtain a formulation that had the lowest turbidity and particle count. Our results showed that VA and CZ form an equimolar precipitate below pH 7.3. The best formulation obtained underwent an in-vitro evaluation of its antibacterial activity. The impact of HPCDs on incompatibility has been demonstrated through the inclusion of antibiotics and especially VA. The formulation has been shown to be able to inhibit the incompatibility for pH higher than 7.3 and to possess unaltered antibacterial activity.

Visual acuity outcomes of anti-VEGF treatment for neovascular age-related macular degeneration in clinical trials

Anti-VEGF treatment for neovascular age-related macular degeneration (nAMD) has been evaluated in clinical trials. To select the best anti-VEGF drug and the best treatment regimen for nAMD, a thorough understanding of the characteristics of each anti-VEGF drug and treatment regimen is essential. In this review, we summarized visual acuity (VA) changes in 30 previous clinical trials of anti-VEGF treatment for nAMD. In most studies, ranibizumab, aflibercept, and brolucizumab improved the VA by 6 to 12 letters from the baseline VA of 50-65 letters and maintained the VA improvement regardless of the treatment regimen; the VA improved from 0.2-0.4 to 0.3-0.7 in Snellen equivalents. The improvement was rapid during the first month and became slower after the second injection, and 60% to 90% of the VA improvement was attained within the first 3 months. The upper limit of the VA improvement should be determined according to eyes with nAMD themselves, not according to anti-VEGF drugs or treatment regimens. Since a fixed regimen can result in overtreatment, whilst a pro re nata regimen can result in insufficient treatment, a treat-and-extend regimen would be optimal to treat nAMD. Insufficient treatment fails to improve VA to the upper limit and/or to maintain the improved VA, whereas overtreatment can cause macular atrophy. One study reported no difference in the risk of macular atrophy between ranibizumab and aflibercept, whilst many studies have suggested that aflibercept causes more choroidal thinning, one of the risk factors for macular atrophy, than does ranibizumab. Further evaluation of drugs and regimens should be performed from the viewpoint of complications and minimum number of injections required to improve and maintain VA.

cGMP-PKG dependent transcriptome in normal and degenerating retinas: Novel insights into the retinitis pigmentosa pathology

Retinitis Pigmentosa represents a group of genetic disorders that cause progressive vision loss via degeneration of photoreceptors, but there is in principle no treatment available. For any therapy development, a deeper comprehension of the disease-leading mechanism(s) at the molecular level is needed. Here we focused on the cGMP-PKG system, which has been suggested to be a driver in several models of the disease. To gain insights in its downstream signaling we manipulated the cGMP-PKG system with the aid of organotypic retinal explant cultures from either a mouse-based disease model, i.e. the rd1 mouse, or its healthy wild-type counterpart (wt), by adding different types of cGMP analogues to either inhibit or activate PKG in retinal explants from rd1 and wt, respectively. An RNA sequencing was then performed to study the cGMP-PKG dependent transcriptome. Expression changes of gene sets related to specific pathways or functions, that fulfilled criteria involving that the changes should match PKG activation and inhibition, were determined via bioinformatics. The analyses highlighted that several gene sets linked to oxidative phosphorylation and mitochondrial pathways were regulated by this enzyme system. Specifically, the expression of such pathway components was upregulated in the rd1 treated with PKG inhibitor and downregulated in the wt with PKG activator treatment, suggesting that cGMP-PKG act as a negative regulator in this context. Downregulation of energy production pathways may thus play an integral part in the mechanism behind the degeneration for at least several RP mutations.

Transplantation Efficacy of Human Ciliary Epithelium Cells from Fetal Eye and Lin-ve Stem Cells from Umbilical Cord Blood in the Murine Retinal Degeneration Model of Laser Injury

A number of degenerative conditions affecting the neural retina including age-related macular degeneration have no successful treatment, resulting in partial or complete vision loss. There are a number of stem cell replacement strategies for recovery of retinal damage using cells from variable sources. However, literature is still deficit in the comparison of efficacy of types of stem cells. The purpose of the study was to compare the therapeutic efficacy of undifferentiated cells, i.e., lineage negative stem cells (Lin-ve SC) with differentiated neurosphere derived from ciliary epithelium (CE) cells on retinal markers associated with laser-induced retinal injury. Laser-induced photocoagulation was carried out to disrupt Bruch’s membrane and retinal pigmented epithelium in C57BL/6 mouse model. Lineage negative cells were isolated from human umbilical cord blood, whereas neurospheres were derived from CE of post-aborted human eyeballs. The cells were then transplanted into subretinal space to study their effect on injury. Markers of neurotropic factors, retina, apoptosis, and proliferation were analyzed after injury and transplantation. mRNA expression was also analyzed by real-time polymerase chain reaction at 1 week, and 3-month immunohistochemistry was evaluated at 1-week time point. CE cell transplantation showed enhanced differentiation of rods and retinal glial cells. However, Lin-ve cells exerted paracrine-dependent modulation of neurotrophic factors, which is possibly mediated by antiapoptotic and proliferative effects. In conclusion, CE transplantation showed superior regenerative outcome in comparison to Lin-ve SC for rescue of artificially injured rodent retinal cells. It is imperative that this source for transplantation may be extensively studied in various doses and additional retinal degeneration models for prospective clinical applications.

Foveal Microvascular Integrity Association With Anti-VEGF Treatment Response for Diabetic Macular Edema

Purpose

To investigate the association between foveal microvascular integrity and anti-vascular endothelial growth factor (VEGF) treatment response for diabetic macular edema (DME).

Methods

This retrospective study enrolled 58 eyes (from 45 patients) with DME. Treatment strategy was three to five monthly anti-VEGF injections followed by a PRN protocol. Treatment with an intravitreal corticosteroid would be considered for persistent DME after five consecutive anti-VEGF injections. Eyes achieving a treatment-free interval ≥ four months within two years were classified into the good clinical course group (group 1). Eyes with frequent recurrent edema (treatment-free interval < four months) or requiring an intravitreal corticosteroid within two years were classified into the suboptimal clinical course group (group 2). Foveal microvascular integrity was evaluated by two continuous variables, that is, vessel density (%) within a width of 300 µm around the foveal avascular zone (FD-300) on optical coherence tomography angiography (OCTA) and perifoveal leakage (area %) on fluorescein angiography (FA).

Results

There were 37 eyes in group 1 and 21 eyes in group 2. FD-300 (odds ratio 0.733, 95% CI 0.620–0.867, P < 0.001) and perifoveal leakage (odds ratio 1.064, 95% CI 1.007–1.124, P = 0.027) were significantly associated with suboptimal clinical course. Area under curve (AUC) was 0.820 for FD-300 and 0.723 for perifoveal leakage in predicting clinical course. FD-300 was negatively correlated with perifoveal leakage (coefficient = −0.325, P = 0.014).

Conclusions

Compromised foveal microvascular integrity, represented by lower FD-300 and more severe perifoveal fluorescein leakage, was associated with suboptimal clinical course in anti-VEGF treatment for DME. A negative correlation between FD-300 and perifoveal leakage existed.

Does Endogenous Endophthalmitis Need a More Aggressive Treatment?

Topic: To focus on endogenous endophthalmitis management, particularly etiology-based medical and surgical therapy.Methods: Literature search of published studies from July 1990 to February 2019 on endogenous endophthalmitis available on PubMed was made without any language constraints.Results: A total of 78 articles were retrieved from 728 initially analyzed and 62 studies were included. Although the superiority of vitrectomy over tap and inject techniques is controversial, the most recent publications favor an early surgical approach for endogenous endophthalmitis. Vitrectomy is useful in severe cases complicated by marked vitreous opacity, retinal detachment, poor initial visual acuity, and more virulent pathogens. Oral or intravenous antibiotics are also necessary to treat systemic infection. Vitrectomy is superior to blood cultures in diagnosing the etiology of infection.Conclusions: Endogenous endophthalmitis is an important cause of visual acuity impairment. Prompt treatment with appropriate use of pharmacological or surgical therapy is mandatory to preserve visual function.Abbreviations: IOP: intra-ocular pressure; AIDS: acquired immune deficiency syndrome; EVS: endophthalmitis vitrectomy study; CEVE: complete and early vitrectomy for endophthalmitis.

Absence of retbindin blocks glycolytic flux, disrupts metabolic homeostasis, and leads to photoreceptor degeneration

We previously reported a model of progressive retinal degeneration resulting from the knockout of the retina-specific riboflavin binding protein, retbindin (Rtbdn ^-/- ). We also demonstrated a reduction in neural retinal flavins as a result of the elimination of RTBDN. Given the role of flavins in metabolism, herein we investigated the underlying mechanism of this retinal degeneration by performing metabolomic analyses on predegeneration at postnatal day (P) 45 and at the onset of functional degeneration in the P120 retinas. Metabolomics of hydrophilic metabolites revealed that individual glycolytic products accumulated in the P45 Rtbdn ^-/- neural retinas along with the elevation of pentose phosphate pathway, while TCA cycle intermediates remained unchanged. This was confirmed by using ¹³C-labeled flux measurements and immunoblotting, revealing that the key regulatory step of phosphoenolpyruvate to pyruvate was inhibited via down-regulation of the tetrameric pyruvate kinase M2 (PKM2). Separate metabolite assessments revealed that almost all intermediates of acylcarnitine fatty acid oxidation, ceramides, sphingomyelins, and multiple toxic metabolites were significantly elevated in the predegeneration Rtbdn ^-/- neural retina. Our data show that lack of RTBDN, and hence reduction in flavins, forced the neural retina into repurposing glucose for free-radical mitigation over ATP production. However, such sustained metabolic reprogramming resulted in an eventual metabolic collapse leading to neurodegeneration.

Retina Metabolism and Metabolism in the Pigmented Epithelium: A Busy Intersection

The outer retina is nourished from the choroid, a capillary bed just inside the sclera. O₂, glucose, and other nutrients diffuse out of the choroid and then filter through a monolayer of retinal pigment epithelium (RPE) cells to fuel the retina. Recent studies of energy metabolism have revealed striking differences between retinas and RPE cells in the ways that they extract energy from fuels. The purpose of this review is to suggest and evaluate the hypothesis that the retina and RPE have complementary metabolic roles that make them depend on each other for survival and for their abilities to perform essential and specialized functions. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Current and future therapies for persistent corneal epithelial defects and neurotrophic keratopathy

PURPOSE OF REVIEW

The corneal epithelium is a crucial barrier against pathogens, and when disrupted in the setting of certain underlying risk factors such as neurotrophic keratopathy (NK), may result in persistent epithelial defects (PEDs) of the cornea. Management is challenging and may require a variety of different approaches ranging from conservative medical therapy to surgical intervention. The purpose of this review is to provide an update on current and potential future therapeutic options for PEDs and NK.

RECENT FINDINGS

Recent research has yielded promising results for numerous novel therapies aimed at treating PEDs. Many of these attempt to stimulate healing at the cellular level, via signaling of corneal epithelial differentiation, migration, and proliferation. Considerable advances have also been made regarding medical and surgical promotion of corneal re-innervation and restoration of corneal sensitivity to directly address the underlying NK condition.

SUMMARY

Together with the current well established therapeutic options available for PEDs and NK, growing research on newer alternatives suggest increasing potential for both more effective and more convenient therapies for these difficult situations.

Retinal Pigment Epithelium Remodeling in Mouse Models of Retinitis Pigmentosa

In retinitis pigmentosa (RP), one of many possible genetic mutations causes rod degeneration, followed by cone secondary death leading to blindness. Accumulating evidence indicates that rod death triggers multiple, non-cell-autonomous processes, which include oxidative stress and inflammation/immune responses, all contributing to cone demise. Inflammation relies on local microglia and recruitment of immune cells, reaching the retina through breakdowns of the inner blood retinal barrier (iBRB). Leakage in the inner retina vasculature suggests similarly altered outer BRB, formed by junctions between retinal pigment epithelium (RPE) cells, which are crucial for retinal homeostasis, immune response, and privilege. We investigated the RPE structural integrity in three models of RP (rd9, rd10, and Tvrm4 mice) by immunostaining for zonula occludens-1 (ZO-1), an essential regulatory component of tight junctions. Quantitative image analysis demonstrated discontinuities in ZO-1 profiles in all mutants, despite different degrees of photoreceptor loss. ZO-1 interruption zones corresponded to leakage of in vivo administered, fluorescent dextran through the choroid-RPE interface, demonstrating barrier dysfunction. Dexamethasone, administered to rd10 mice for rescuing cones, also rescued RPE structure. Thus, previously undetected, stereotyped abnormalities occur in the RPE of RP mice; pharmacological targeting of inflammation supports a feedback loop leading to simultaneous protection of cones and the RPE.