Extent of Detached Retina and Lens Status Influence Intravitreal Protein Expression in Rhegmatogenous Retinal Detachment

Pneumatic Retinopexy for Rhegmatogenous Retinal Detachment in Elderly Patients

PURPOSE

To assess clinical outcomes in elderly patients aged ≥ 75 years who underwent pneumatic retinopexy (PnR) for primary rhegmatogenous retinal detachment (RRD).

DESIGN

Retrospective cohort study.

SUBJECTS

Patients aged ≥ 75 years with primary RRD undergoing PnR.

METHODS

This study evaluates clinical outcomes among eligible patients who presented from October 1, 2010, to December 31, 2022, with a minimum of 3 months' follow-up. There were no limitations with respect to the number, size, or location of retinal breaks. Exclusion criteria included significant proliferative vitreoretinopathy or previous retinal detachment repair in the index eye, inability to maintain the postoperative posturing requirements or inability to carry out adequate examination of the peripheral retina because of media opacity. Lens status did not impact the decision to offer PnR.

MAIN OUTCOME MEASURES

Pneumatic retinopexy primary anatomic reattachment rate and postoperative best corrected visual acuity (BCVA) at 3 months.

RESULTS

Eighty patients with a mean age of 80.6 ± 4.6 years were included in this study; 35% (28/80) were phakic and 34% (27/80) presented with a fovea-on RRD. The mean number of breaks in the detached retina was 1.52 ± 1.13, and the mean number of quadrants of detached retina was 2.35 ± 0.93. The primary anatomic reattachment rate at 3 months after PnR was 78.8% (63/80), whereas the remaining 21.2% (17/80) failed PnR and underwent an operating room procedure. There was a statistically significant improvement in logarithm of the minimum angle of resolution (logMAR) BCVA from baseline to 3 months (1.29 ± 0.94 and 0.69 ± 0.67, respectively, P < 0.001). A subgroup analysis that only included patients aged > 80 years was also performed, with a total of 39 patients with a mean age of 84.4 ± 3.5 years. The primary anatomic reattachment rate with PnR in this subgroup was 74.4% (29/39), with a statistically significant improvement in BCVA from baseline to 3 months (1.4 ± 1.05 and 0.77 ± 0.70, respectively; P = 0.004).

CONCLUSIONS

Elderly patients treated with PnR for primary RRD had relatively comparable primary anatomic reattachment rates with other surgical techniques such as pars plana vitrectomy and scleral buckle. Pneumatic retinopexy is an effective, minimally invasive office-based procedure that may be desirable for some elderly patients.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Cost-Utility of Rhegmatogenous Retinal Detachment Repair With Pars Plana Vitrectomy, Scleral Buckle, and Pneumatic Retinopexy: A Microsimulation Model

PURPOSE

To assess the cost-effectiveness of primary noncomplex rhegmatogenous retinal detachment (RRD) repair, comparing 3 different strategies, pars plana vitrectomy (PPV), scleral buckle (SB), and pneumatic retinopexy (PnR) from the health care payer perspective over a lifetime.

DESIGN

Model-based cost-utility analysis.

METHODS

A simulated cohort of 100,000 adult patients (≥18 years old) requiring primary noncomplex RRD repair in theoretical surgical centers in the United States. Quality-adjusted life years (QALYs), lifetime costs (2022 United States dollars), and the incremental cost-effectiveness ratio (ICER) of the 3 interventions were projected over a lifetime horizon, with a cost-effectiveness threshold of ≤$50,000 per gained QALY.

RESULTS

Based on inputted parameters, the primary anatomical success was highest for PPV (95.00%) compared to SB (91.76%) and PnR (63.41%). The QALYs associated with PPV, SB, and PnR were (11.87, SD 1.62), (11.84, SD 1.63), and (11.59, SD 1.72), respectively. The incurred lifetime costs of RRD repair and associated postoperative surgeries for PPV, SB, and PnR were $4445.72 (SD 655.75), $4518.04 (662.92), and $3978.45 (728.50), respectively. Parameter-level simulations suggested that PPV was most likely to be the most cost-effective therapy compared to SB and PnR beyond a threshold of $3000/QALY. The incremental cost-effectiveness ratio for PPV compared to PnR was $1693.54. SB was dominant in all scenarios. Threshold analyses indicated that the success rate of PnR would have to be 100% and/or the cost would have to be $2000 or less over lifetime for it to be more cost-effective than PPV.

CONCLUSIONS

This study found PPV to be the most cost-effective primary procedure for RRD repair at a threshold of $50,000/QALY gained over a lifetime horizon from the health care payer perspective.

Increased intravitreal glucose in rhegmatogenous retinal detachment

PURPOSE

Altered glucose metabolism, along with low-grade inflammation, has been proposed to be involved in retinal detachment (RD)-induced cone loss. Here, we assessed intravitreal glucose and cytological profile in patients with macula-off RD.

METHODS

Glucose concentration was analysed in vitreous samples from 137 non-diabetic patients undergoing vitrectomy for either primary macula-off RD (n = 73) or epiretinal membrane (ERM; n = 64). Cellularity was assessed in vitreous cytospin preparations by a semi-quantitative immunostaining approach.

RESULTS

Intravitreal glucose concentration was higher in the RD group (2.28 mmol.L-1 n =73 vs 1.6 mmol.L-1 n = 64; p < 0.0001). Overall cellularity and density of macrophages were significantly higher in the vitreous of RD patients (respectively p = 0.003 and p < 0.0001). Among the RD patients, intravitreal glucose concentration correlated with macrophages density (p = 0.002): its levels remained significantly higher in eyes in which macrophages were innumerable compared to lower macrophages densities RD eyes (p = 0.0095).

CONCLUSIONS

We observed a strong relationship between intravitreal glucose concentration and vitreous macrophage density. Additional indicators for vitreous glycation and low-grade inflammation should be further studied.

Upregulation of Neuroinflammatory Protein Biomarkers in Acute Rhegmatogenous Retinal Detachments

The purpose of this study is to characterize the inflammatory cytokine profile in rhegmatogenous retinal detachments (RRDs) compared to surgical controls. Vitreous humor was collected from patients undergoing vitrectomy for RRD and noninflammatory vitreoretinal diseases. A quantitative immunoassay was used to measure the levels of 36 cytokine markers. Linear regression analysis with the duration of detachment as the predictor and log-transformed cytokine levels as the outcome was conducted for normally distributed cytokines as determined by the Shapiro-Wilk test. The analysis was adjusted for age, sex, and race. The Kruskal-Wallis test was used for cytokines not normally distributed. Twenty-seven RRD cases and thirteen control cases were studied. Between all RRDs and controls, fibroblast growth factor 2 (FGF2) (p = 0.0029), inducible protein-10(IP-10) (p = 0.0021), monocyte chemoattractant protein-1 (MCP-1) (p = 0.0040), interleukin (IL)-16 (p = 0.018), IL-8 (p = 0.0148), IL-6 (p = 0.0071), eotaxin (p = 0.0323), macrophage inflammatory protein (MIP)-1 alpha (p = 0.0149), MIP-1 beta (p = 0.0032), and the thymus and activation regulated cytokine (TARC) (p = 0.0121) were elevated in RRD cases. Between acute RRDs (n = 16) and controls, FGF2 (p = 0.0001), IP10 (p = 0.0027), MCP-1 (p = 0.0015), MIP-1β (p = 0.0004), IL-8 (p = 0.0146), and IL-6 (p = 0.0031) were elevated. Determining alterations in inflammatory cytokine profiles may aid in understanding their impact on RRD development, clinical course, and complications before and after surgical repair.

Preoperative and Postoperative Factors Affecting Functional Success in Anatomically Successful Retinal Detachment Surgery

PURPOSE

To investigate preoperative and postoperative factors affecting functional success in anatomically successful retinal detachment surgery.

METHODS

Seventy-five eyes of 75 patients with rhegmatogenous retinal detachment who underwent anatomically successful surgery from 2014 to 2019 with more than 1 year follow-up were included in the study. Demographic characteristics, ocular examination findings, preoperative and postoperative spectral domain optic coherence tomography images were retrospectively evaluated.

RESULTS

The mean age was 53.9 ± 17 years (range, 11-85 years). The mean follow-up period was 36.7 ± 16 months (range, 14-72 months). The mean best-corrected visual acuity of the patients before surgery was 1.35 ± 1.24 and at postoperative 12 months was 0.66 ± 0.5 logarithm of the minimum angle of resolution. Patients who were operated in 7 days of visual symptoms onset were found to have better visual acuity at the first and subsequent postoperative exams. Preoperative proliferative vitreoretinopathy, vitreous hemorrhage, and extent of retinal detachment were found to have a negative effect on functional success at 12 months. Regeneration of the outer retinal layers had a positive effect on visual acuity at 12 months but did not significantly increase visual acuity after 12 months. Multivariate analysis showed that preoperative external limiting membrane integrity was significantly associated with better functional outcomes.

CONCLUSIONS

Early intervention, presence of preoperative external limiting membrane integrity, and restoration of postoperative outer retinal layers positively affected functional success. The presence of preoperative vitreous hemorrhage, preoperative proliferative vitreoretinopathy, and the extent of retinal detachment had a negative effect on prognosis at 12 months.

Impact of Primary RPE Cells in a Porcine Organotypic Co-Cultivation Model

The pathological events of age-related macular degeneration are characterized by degenerative processes involving the photoreceptor cells, retinal pigment epithelium (RPE), and the Bruch's membrane as well as choroidal alterations. To mimic in vivo interactions between photoreceptor cells and RPE cells ex vivo, complex models are required. Hence, the aim of this study was to establish a porcine organotypic co-cultivation model and enlighten the interactions of photoreceptor and RPE cells, with a special emphasis on potential neuroprotective effects. Porcine neuroretina explants were cultured with primary porcine RPE cells (ppRPE) or medium derived from these cells (=conditioned medium). Neuroretina explants cultured alone served as controls. After eight days, RT-qPCR and immunohistology were performed to analyze photoreceptors, synapses, macroglia, microglia, complement factors, and pro-inflammatory cytokines (e.g., IL1B, IL6, TNF) in the neuroretina samples. The presence of ppRPE cells preserved photoreceptors, whereas synaptical density was unaltered. Interestingly, on an immunohistological as well as on an mRNA level, microglia and complement factors were comparable in all groups. Increased IL6 levels were noted in ppRPE and conditioned medium samples, while TNF was only upregulated in the ppRPE group. IL1B was elevated in conditioned medium samples. In conclusion, a co-cultivation of ppRPE cells and neuroretina seem to have beneficial effects on the neuroretina, preserving photoreceptors and maintaining synaptic vesicles in vitro. This organotypic co-cultivation model can be used to investigate the complex interactions between the retina and RPE cells, gain further insight into neurodegenerative pathomechanisms occurring in retinal diseases, and evaluate potential therapeutics.

Multiplex protein analysis for the study of glaucoma

INTRODUCTION

Glaucoma, a leading cause of irreversible blindness in the world, is a chronic neurodegenerative disease of multifactorial origin. Extensive research is ongoing to better understand, prevent, and treat progressive degeneration of retinal ganglion cells in glaucoma. While experimental models of glaucoma and postmortem tissues of human donors are analyzed for pathophysiological comprehension and improved treatment of this blinding disease, clinical samples of intraocular biofluids and blood collected from glaucoma patients are analyzed to identify predictive, diagnostic, and prognostic biomarkers. Multiplexing techniques for protein analysis offer a valuable approach for translational glaucoma research.

AREAS COVERED

This review provides an overview of the increasing applications of multiplex protein analysis for glaucoma research and also highlights current research challenges in the field and expected solutions from emerging technological advances.

EXPERT OPINION

Analytical techniques for multiplex analysis of proteins can help uncover neurodegenerative processes for enhanced treatment of glaucoma and can help identify molecular biomarkers for improved clinical testing and monitoring of this complex disease. This evolving field and continuously growing availability of new technologies are expected to broaden the comprehension of this complex neurodegenerative disease and speed up the progress toward new therapeutics and personalized patient care to prevent blindness from glaucoma.

Vitreous cytokine expression profiles in patients with retinal detachment

PURPOSE

To compare the expression profiles of various cytokines and chemokines in vitreous samples from patients with retinal detachment (RD) to those from controls and to analyze their association with various clinical features.

METHODS

In this prospective study, undiluted vitreous fluid was obtained from 41 patients with primary RD and 33 controls with macular hole or vitreomacular traction. A multiplex bead immunoassay was performed to determine the expression of 27 inflammatory mediators.

RESULTS

Eleven mediators were significantly upregulated in the vitreous of RD patients compared with controls, including the following: cytokines IL-1ra, IL-6, IL-7, IL-8, IFN-γ; chemokines CCL2, CCL3, CCL4, CXCL10 and CCL11 and growth factor G-CSF. Correlation analyses showed that levels of IL-1ra, CXCL10, CCL11 and G-CSF were positively correlated to the extent of detachment, while those of IL-1ra and CXCL10 were associated with the duration of detachment. There was also a positive association between the concentrations of CXCL10 and CCL11 and preoperative flare values. Additional analysis revealed that flare values and both CXCL10 and CCL11 levels were significantly higher in eyes with grade B or C proliferative vitreoretinopathy (PVR).

CONCLUSION

Our results confirm that RD induces a marked inflammatory response with a complex cytokine network. We identified proteins specifically linked to several clinical features that might contribute to photoreceptor degeneration and PVR-related redetachment. These proteins may represent potential therapeutic targets for improving the anatomical and functional outcomes of RD surgery.

Impact of submacular fluid volume on visual outcome in macula-off rhegmatogenous retinal detachment using automated optical coherence tomography volumetric quantification

Background

We investigated effects of submacular fluid volume (SMFV) on visual outcomes following surgery for macula‐off primary rhegmatogenous retinal detachment (RRD) using automated fluid volumetric quantification with optical coherence tomography (OCT).

Methods

We analysed 127 eyes that were surgically treated for macula‐off RRDs. We obtained preoperative images following the spectral domain (SD)‐OCT dense volume protocol, applied automated retinal segmentation and used an automated algorithm to quantify each eye's SMFV. We used multivariate models to identify various risk factors for impaired visual outcome.

Results

Linear regression showed that preoperative SMFV (ß = 0.013; P = .005) was significantly associated with a reduced visual outcome 12 months after the treatment of macula‐off RRDs. SMFV was negatively correlated with 12‐month postoperative (r = .311; P = .001) visual acuity (VA). The group with low preoperative SMFV (≤9.0 mm³) showed an increasing VA up to 12 months postoperatively (P < .001), while the VA did not increase in the group with high SMFV (>9.0 mm³) beyond 3 months of follow‐up. Patients with a high SMFV were 8.0 times more likely to have worse visual outcomes after 12 months of follow‐up (P = .018).

Conclusions

SMFV was negatively correlated with visual outcomes after the surgical treatment of macula‐off RRDs. Patients with SMFV <9.0 mm³ 12 months after surgery had an 8.0 times greater chance for better visual recovery than patients with high preoperative SMFV. Our findings highlight the efficacy of automated SMFV quantification in predicting surgical outcomes in patients with RRDs, which could be useful in future clinical practice and the development of research models.

Molecular pathogenesis of rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is an ophthalmic emergency, which usually requires prompt surgery to prevent further detachment and restore sensory function. Although several individual factors have been suggested, a systems level understanding of molecular pathomechanisms underlying this severe eye disorder is lacking. To address this gap in knowledge we performed the molecular level systems pathology analysis of the vitreous from 127 patients with RRD using state-of-the art quantitative mass spectrometry to identify the individual key proteins, as well as the biochemical pathways contributing to the development of the disease. RRD patients have specific vitreous proteome profiles compared to other diseases such as macular hole, pucker, or proliferative diabetic retinopathy eyes. Our data indicate that various mechanisms, including glycolysis, photoreceptor death, and Wnt and MAPK signaling, are activated during or after the RRD to promote retinal cell survival. In addition, platelet-mediated wound healing processes, cell adhesion molecules reorganization and apoptotic processes were detected during RRD progression or proliferative vitreoretinopathy formation. These findings improve the understanding of RRD pathogenesis, identify novel targets for treatment of this ophthalmic disease, and possibly affect the prognosis of eyes treated or operated upon due to RRD.

Immunological biomarkers of the vitreous responsible for proliferative alteration in the different forms of retinal detachment

Background

The purpose of the study was to explore the immunological components that are responsible for the proliferative alterations in the different forms of retinal detachment (RD).

Methods

Vitreous fluids were collected during 23G pars plana vitrectomy from 54 eyes of 54 patients with different RD types, such as rhegmatogenous RD (RRD) without proliferative vitreoretinopathy (PVR) (n = 30), PVR (n = 16) and proliferative diabetic retinopathy (PDR) with tractional RD (n = 8). Vitreous fluids were obtained from 19 eyes with epiretinal membrane (ERM), which were used as control samples. A multiplex chemiluminescent immunoassay was performed to evaluate the concentrations of 48 cytokines, chemokines and growth factors.

Results

The expression levels of eotaxin, IFN-gamma, IL-6, IL-8, IL-16, MCP-1, MIF and MIP-1 beta were significantly higher in all RD groups than in the ERM group. The levels of CTACK, IP-10, SCGF-beta, and SDF-1 alpha were significantly higher in patients with diabetic tractional RD and PVR than in other patients. The upregulation of VEGF and IL-18 was detected in PDR.

Conclusions

Our results indicate that complex and significant immunological mechanisms are associated with the pathogenesis of different forms of RD: selected cytokines, chemokines and growth factors are upregulated in the vitreous of eyes with RD. The detected proteins are present in different concentrations both in RRD and PVR. In the presence of PVR and PDR, the majority of cytokines are upregulated; thus, they may serve as biomarkers to estimate the progression or severity level of proliferation and later to develop personalized therapeutic strategies to slow down or prevent pathological changes.

Insulin inhibits inflammation-induced cone death in retinal detachment

BACKGROUND

Rhegmatogenous retinal detachment (RD) involving the macula is a major cause of visual impairment despite high surgical success rate, mainly because of cone death. RD causes the infiltration of activated immune cells, but it is not clear whether and how infiltrating inflammatory cells contribute to cone cell loss.

METHODS

Vitreous samples from patients with RD and from control patients with macular hole were analyzed to characterize the inflammatory response to RD. A mouse model of RD and retinal explants culture were then used to explore the mechanisms leading to cone death.

RESULTS

Analysis of vitreous samples confirms that RD induces a marked inflammatory response with increased cytokine and chemokine expression in humans, which is closely mimicked by experimental murine RD. In this model, we corroborate that myeloid cells and T-lymphocytes contribute to cone loss, as the inhibition of their accumulation by Thrombospondin 1 (TSP1) increased cone survival. Using monocyte/retinal co-cultures and TSP1 treatment in RD, we demonstrate that immune cell infiltration downregulates rod-derived cone viability factor (RdCVF), which physiologically regulates glucose uptake in cones. Insulin and the insulin sensitizers rosiglitazone and metformin prevent in part the RD-induced cone loss in vivo, despite the persistence of inflammation CONCLUSION: Our results describe a new mechanism by which inflammation induces cone death in RD, likely through cone starvation due to the downregulation of RdCVF that could be reversed by insulin. Therapeutic inhibition of inflammation and stimulation of glucose availability in cones by insulin signaling might prevent RD-associated cone death until the RD can be surgically repaired and improve visual outcome after RD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03318588.

Position of macula lutea and presence of proliferative vitreoretinopathy affect vitreous cytokine expression in rhegmatogenous retinal detachment

Our purpose was to evaluate the concentrations of vitreous cytokines in patients with rhegmatogenous retinal detachment (RRD). We hypothesized that patients with macula on RRD have lower levels of cytokines compared to patients with macula off RRD and proliferative vitreoretinopathy (PVR). Vitreous fluids were collected during 23G pars plana vitrectomy from 58 eyes of 58 patients. Indication for vitrectomy included macula off and macula on RRD, PVR, and idiopathic epiretinal membrane (ERM). A multiplex chemiluminescent immunoassay was performed to measure the concentrations of 48 cytokines, chemokines, and growth factors. Levels of HGF, IL-6, IL-8, IL-16, IFN-gamma, MCP-1, and MIF were significantly higher in all groups of retinal detachment compared to ERM. Levels of CTACK, eotaxin, G-CSF, IP-10, MIG, SCF, SCGF-beta, SDF-1alpha were significantly higher in PVR compared to macula on RRD and ERM. Levels of IL-1ra, IL-5, IL-9, M-CSF, MIP-1alpha, and TRIAL were significantly higher in PVR compared to macula on RRD. Our results indicate that the position of macula lutea and the presence of PVR significantly influence vitreous cytokine expression. The detected proteins may serve as biomarkers to estimate the possibility of PVR formation and may help to invent personalized therapeutic strategies to slow down or prevent PVR.

Distinct Serum and Vitreous Inflammation-Related Factor Profiles in Patients with Proliferative Vitreoretinopathy

INTRODUCTION

Proliferative vitreoretinopathy (PVR), which is regulated by growth factors and cytokines, is the leading cause of failure in vitreoretinal surgery. In this study, we aimed to investigate the role of the human serum and vitreous inflammation-related factors in the development of proliferative vitreoretinopathy (PVR).

METHODS

Blood and vitreous samples were obtained from patients undergoing pars plana vitrectomy. Inflammation-related factors were detected using an immunology multiplex assay on a Luminex® xMAP® platform. Patients with PVR and rhegmatogenous retinal detachment (RRD) were compared with macular hole (MH) or epiretinal membrane (ERM) patients without any other ocular or systemic disease.

RESULTS

Thirty-six serum samples and 34 vitreous samples were obtained. Thirty-one different growth factors and cytokines were detected in serum samples. However, none of the circulating growth factors and cytokines were found to be different from the controls. Ten different growth factors and cytokines were measured in the vitreous samples. The concentration levels of PDGF-AA, TGF-α, VEGF, IL-6, IL-8, and TNFβ were found to have significantly increased in the vitreous of PVR patients.

CONCLUSION

Our study found that none of the circulating inflammation-related factors were changed in PVR or RRD patients, indicating the absence of a system inflammatory biomarkers to predict the development of proliferative vitreoretinopathy. As a supplement to previous research, the concentrations of PDGF-AA, TGF-α, VEGF, IL-6, IL-8, and TNFβ were significantly upregulated in the vitreous of PVR patients. These factors should be considered for preventing PVR.

Inflammatory and Fibrogenic Factors in Proliferative Vitreoretinopathy Development

Purpose

Proliferative vitreoretinopathy (PVR) occurs in 5%-10% of rhegmatogenous retinal detachment cases and is the principle cause for failure of retinal reattachment surgery. Although there are a number of surgical adjunctive agents available for preventing the development of PVR, all have limited efficacy. Discovering predictive molecular biomarkers to determine the probability of PVR development after retinal reattachment surgery will allow better patient stratification for more targeted drug evaluations.

Methods

Narrative literature review.

Results

We provide a summary of the inflammatory and fibrogenic factors found in ocular fluid samples during the development of retinal detachment and PVR and discuss their possible use as molecular PVR predictive biomarkers.

Conclusions

Studies monitoring the levels of the above factors have found that few if any have predictive biomarker value, suggesting that widening the phenotype of potential factors and a combinatorial approach are required to determine predictive biomarkers for PVR.

Translational Relevance

The identification of relevant biomarkers relies on an understanding of disease signaling pathways derived from basic science research. We discuss the extent to which those molecules identified as biomarkers and predictors of PVR relate to disease pathogenesis and could function as useful disease predictors. (http://www.umin.ac.jp/ctr/ number, UMIN000005604).

Vitreous Cytokine Expression and a Murine Model Suggest a Key Role of Microglia in the Inflammatory Response to Retinal Detachment

Purpose

Retinal detachment (RD) separates the retina from the underlying retinal pigment epithelium, resulting in a gradual degeneration of photoreceptor (PR) cells. It is known that RD also results in an inflammatory response, but its contribution to PR degeneration is unknown. In this study we examine the inflammatory responses to RD in patient vitreous and validate a mouse experimental RD as a model of this phenomenon.

Methods

Multiplex bead arrays were used to examine cytokine levels in vitreous samples from 24 patients with macula-off rhegmatogenous retinal detachment (RRD) undergoing reattachment surgery and from 10 control patients undergoing vitrectomy for vitreous opacities or epiretinal membrane. Activation of the innate immune response was then examined in a mouse model of RD.

Results

Twenty-eight factors were significantly increased in vitreous from RD patients versus controls. Notable were the cytokines MCP-1 (CCL2), IP-10 (CXCL10), fractalkine (CX3CL1), GRO (CXCL1), MDC (CCL22), IL-6, and IL-8, which all exhibited relatively high concentrations and several-fold increases in the vitreous of RD patients. Concentrations of various analytes correlated with a range of clinical variables such as duration of detachment and visual acuity. Retinal detachment in the mouse resulted in cytokine mRNA expression changes consistent with human RD vitreous results, as well as microglial proliferation and migration toward the outer retina.

Conclusions

The findings suggest that an inflammatory response involving microglia is a component of the reaction to retinal detachment that may impact visual acuity after surgical repair and that mouse experimental RD can serve as a model to study this effect.

Rapid monocyte infiltration following retinal detachment is dependent on non-canonical IL6 signaling through gp130

BACKGROUND

Retinal detachment (RD) can lead to proliferative vitreoretinopathy (PVR), a leading cause of intractable vision loss. PVR is associated with a cytokine storm involving common proinflammatory molecules like IL6, but little is known about the source and downstream signaling of IL6 and the consequences for the retina. Here, we investigated the early immune response and resultant cytokine signaling following RD in mice.

METHODS

RD was induced in C57BL/6 J and IL6 knockout mice, and the resulting inflammatory response was examined using immunohistochemistry and flow cytometry. Cytokines and signaling proteins of vitreous and retinas were quantified by multiple cytokine arrays and Western blotting. To attempt to block IL6 signaling, a neutralizing antibody of IL6 receptor α (IL6Rα) or IL6 receptor β (gp-130) was injected intravitreally immediately after RD.

RESULTS

Within one day of RD, bone marrow-derived Cd11b + monocytes had extravasated from the vasculature and lined the vitreal surface of the retina, while the microglia, the resident macrophages of the retina, were relatively unperturbed. Cytokine arrays and Western blot analysis revealed that this sterile inflammation did not cause activation of IL6 signaling in the neurosensory retina, but rather only in the vitreous and aqueous humor. Monocyte infiltration was inhibited by blocking gp130, but not by IL6 knockout or IL6Rα blockade.

CONCLUSIONS

Together, our results demonstrate that monocytes are the primary immune cell mediating the cytokine storm following RD, and that any resulting retinal damage is unlikely to be a direct result of retinal IL6 signaling, but rather gp130-mediated signaling in the monocytes themselves. These results suggest that RD should be treated immediately, and that gp130-directed therapies may prevent PVR and promote retinal healing.

Human neural progenitor cells decrease photoreceptor degeneration, normalize opsin distribution and support synapse structure in cultured porcine retina

Retinal neurodegenerative disorders like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy and retinal detachment decrease retinal functionality leading to visual impairment. The pathological events are characterized by photoreceptor degeneration, synaptic disassembly, remodeling of postsynaptic neurons and activation of glial cells. Despite intense research, no effective treatment has been found for these disorders. The current study explores the potential of human neural progenitor cell (hNPC) derived factors to slow the degenerative processes in adult porcine retinal explants. Retinas were cultured for 3 days with or without hNPCs as a feeder layer and investigated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), immunohistochemical, western blot and quantitative real time-polymerase chain reaction (qRT-PCR) techniques. TUNEL showed that hNPCs had the capacity to limit photoreceptor cell death. Among cone photoreceptors, hNPC coculture resulted in better maintenance of cone outer segments and reduced opsin mislocalization. Additionally, maintained synaptic structural integrity and preservation of second order calbindin positive horizontal cells was also observed. However, Müller cell gliosis only seemed to be alleviated in terms of reduced Müller cell density. Our observations indicate that at 3 days of coculture, hNPC derived factors had the capacity to protect photoreceptors, maintain synaptic integrity and support horizontal cell survival. Human neural progenitor cell applied treatment modalities may be an effective strategy to help maintain retinal functionality in neurodegenerative pathologies. Whether hNPCs can independently hinder Müller cell gliosis by utilizing higher concentrations or by combination with other pharmacological agents still needs to be determined.

High MMP-9 Expression May Contribute to Retroprosthetic Membrane Formation after KPro Implantation in Rabbit Corneal Alkali Burn Model

Purpose. To evaluate aqueous humor MMP-9 levels in alkali-burned rabbit cornea following KPr implantation and their roles in RPMs formation. Methods. Left eyes of 36 rabbits received a deep corneal alkali wound. 12 corneas were implanted with KPro and the other 24 control corneas were either penetrating keratoplasty or left without keratoplasty. Aqueous humor MMP-9 and TIMP-1 levels were determined and RPMs were obtained for histopathological and ultrastructural examination. Results. Alkali exposure induced significant increase in aqueous humor MMP-9 level and the data were further enhanced by KPro implantation. By contrast, TMIP-1 levels in aqueous humor showed a decreased trend following corneal alkali burn and KPro surgery. RPMs were developed in 5 out of 10 cases of KPro successfully implanted eyes. Histopathology showed the presence of a large number of fibroblasts and collagen fibers arranged irregularly with inflammatory cells infiltration, and an ingrowth of new blood vessels in this retrokeratoprosthesis fibrous tissue. Immunohistochemical analysis showed positive stain of RPMs for both MMP-9 and TIMP-1. Aqueous humor MMP-9 levels were significantly higher in RPM group postoperatively, while TIMP-1 levels were comparatively lower than that of No-RPM group. Conclusions. Our study evidenced the potential pathophysiological role of MMP-9 expression in RPM formation following KPro implantation.