Proliferative Vitreoretinopathy Group Research Articles

Vitreous Biomarkers for Proliferative Vitreoretinopathy Prognostication in Patients Undergoing Primary Retinal Detachment Repair.

To compare baseline levels of exploratory biomarkers in the vitreous fluid of patients with primary retinal detachment who subsequently develop proliferative vitreoretinopathy (PVR) versus those who do not. In this exploratory case-control study, we evaluated the baseline protein biomarker levels from a biobank containing the vitreous fluid of patients who had undergone primary pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment. Undiluted samples were collected at the time of PPV and stored at -80°C. Samples from 13 patients who developed PVR within 6months (PVR group) and 13 age- and gender-matched controls who did not develop PVR (control group) were included. Protein abundance levels were evaluated using a proximity extension assay, and a confirmatory enzyme-linked immunosorbent assay (ELISA) was used to measure the concentration of vimentin. Baseline vimentin (Normalized Protein eXpression [NPX], 8.6 vs. 6.4, P < 0.0001) and heme oxygenase 1 (NPX 8.9 vs. 7.0, P < 0.001) levels were found to be elevated in vitreous fluid of patients who subsequently developed PVR compared to those who did not. Confirmatory analysis using ELISA demonstrated mean vimentin concentrations of 7254 vs. 2727 ng/mL in the PVR versus control groups (P = 0.0152). The odds ratio for developing PVR was 14 (confidence interval, 1.4-168; P = 0.03), assuming a baseline vimentin threshold of 7500 ng/mL. Vimentin is an intermediate filament protein expressed by retinal glial cells, and our data combined with prior evidence suggest that it may serve as an early vitreous biomarker for subsequent PVR formation and reactive gliosis. Furthermore, we found, for the first time, elevated baseline levels of heme oxygenase 1, a measurable indicator of oxidative stress. Our positive findings could impact clinical care for retinal detachment patients by facilitating risk stratification for targeted interventions or closer monitoring in those at the highest risk of developing PVR.

Analysis of Hypoxia-Inducible Factor-1a and Intercellular Adhesive Molecule-1 on Clinical Findings in Rhegmatogenous Retinal Detachment Patients

The aim of the study is to examine the role of hypoxia-inducible factor-1a (HIF-1a) and intercellular adhesive molecule (ICAM-1) in clinical findings found in patients with rhegmatogenous retinal detachment (RRD). The clinical findings are; the duration of retinal detachment, retinal quadrants involvement, and the severity of proliferative vitreoretinopathy (PVR). A cross sectional study was conducted, with 34 consecutive vitreous sample were obtained from dr. Cipto Mangunkusumo National General Hospital (RSCM), from October 2015 to October 2016. The samples were taken from RRD patient who received vitrectomy in the hospital. There were no significant difference between the ICAM-1 and HIF-1a levels to the clinical findings that is measured; duration of retinal detachment (p&gt;0.05), extent of retinal detachment area (p&gt;0.05) and severity of PVR (p&gt;0.05). However, there is a significant mean difference of ICAM-1 level on the duration of retinal detachment, where &lt; 1 week group has higher mean 49.71, (SD 49.54) than the other group, as well as in the retinal quadrants groups (2nd quadrant 19.42 (SD 2.49) and also in severity of PVR groups (PVR B 35.42, SD 30.13). The results from HIF-1a level on each sub group were insignificant. The level of ICAM-1 and HIF-1a cannot be used as predictor of the clinical findings found in the patients. ICAM-1 levels tend to be high on patients whose diagnosed with retinal detachment early, with smaller area of detachment (2nd quadrant) and lower PVR levels (PVR B). The level of HIF-1a shows a consistent pattern with minimal difference in between the sub groups.

Intravitreal slow-release dexamethasone alleviates traumatic proliferative vitreoretinopathy by inhibiting persistent inflammation and Müller cell gliosis in rabbits.

To evaluate the effects of intravitreal slow-release dexamethasone on traumatic proliferative vitreoretinopathy (PVR) and Müller cell gliosis and preliminarily explored the possible inflammatory mechanism in a rabbit model induced by penetrating ocular trauma. Traumatic PVR was induced in the right eyes of pigmented rabbits by performing an 8-mm circumferential scleral incision placed 2.5 mm behind the limbus, followed by treatment with a slow-release dexamethasone implant (Ozurdex) or sham injection. Left eyes were used as normal controls. The intraocular pressure (IOP) was monitored using an iCare tonometer. PVR severity was evaluated via anatomical and histopathological examinations every week for 6wk; specific inflammatory cytokine and proliferative marker levels were measured by quantitative real-time polymerase chain reaction, Western blot, protein chip analysis, or immunofluorescence staining. During the observation period, PVR severity gradually increased. Intense Müller cell gliosis was observed in the peripheral retina near the wound and in the whole retina of PVR group. Ozurdex significantly alleviated PVR development and Müller cell gliosis. Post-traumatic inflammation fluctuated and was persistent. The interleukin-1β (IL-1β) mRNA level was significantly upregulated, peaking on day 3 and increasing again on day 21 after injury. The expression of nod-like receptor family pyrin domain containing 3 (NLRP3) showed a similar trend that began earlier than that of IL-1β expression. Ozurdex suppressed the expression of IL-1β, NLRP3, and phosphorylated nuclear factor-kappa B (NF-κB). The average IOP after treatment was within normal limits. The present study demonstrates chronic and fluctuating inflammation in a traumatic PVR rabbit model over 6wk. Ozurdex treatment significantly inhibites inflammatory cytokines expression and Müller cell gliosis, and thus alleviates PVR severity. This study highlights the important role of IL-1β, and Ozurdex inhibites inflammation presumably via the NF-κB/NLRP3/IL-1β inflammatory axis. In summary, Ozurdex provides a potential therapeutic option for traumatic PVR.

Predictive values of systemic inflammation biomarkers in proliferative vitreoretinopathy associated with primary rhegmatogenous retinal detachment

ABSTRACT Clinical relevance Proliferative vitreoretinopathy (PVR) is still the leading cause of surgical failure after rhegmatogenous retinal detachment (RRD) repair. The factors that can predict the development of PVR remain to be elucidated. Background This study evaluates the predictive values of the systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio in patients with primary RRD with and without PVR. Methods A total of 150 patients with RRD and 51 age- and sex-matched healthy participants were included in the study. Patients who developed PVR within three months after surgery were enrolled as PVR cases (n = 75, Group 1), and those who did not develop PVR were enrolled in RRD without the PVR group (n = 75, Group 2). Ocular examination findings and medical records of all participants were analysed retrospectively. Peripheral blood samples were collected, and systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratios were calculated. The systemic immune-inflammation index calculation formula is: (Neutrophil/lymphocyte) × Platelet. Results The median neutrophil-to-lymphocyte ratio and systemic immune-inflammation index levels were significantly higher in Group 1 patients compared to Group 2 and the control groups (p = 0.01, for both). However, the groups were similar regarding median platelet-to-lymphocyte ratio (p = 0.917). The optimal cut-off values of neutrophil-to-lymphocyte ratio and systemic immune-inflammation index were calculated as 1.72 (with 72% sensitivity and 48% specificity) and 407.9 (with 72% sensitivity and 49.3% specificity), respectively, for predicting PVR development in patients with RRD. Conclusion Neutrophil-to-lymphocyte ratio and systemic immune-inflammation index may be useful biomarkers for predicting the risk of PVR development in RRD patients.

Proteomic Insight into the Role of Exosomes in Proliferative Vitreoretinopathy Development.

Purpose: To characterize vitreous humor (VH) exosomes and to explore their role in the development of proliferative vitreoretinopathy (PVR) using mass spectrometry-based proteome profiling. Methods: Exosomes were isolated from undiluted VH from patients with retinal detachment (RD) with various stages of PVR (n = 9), macular hole (MH; n = 5), or epiretinal membrane (ERM; n = 5) using differential ultracentrifugation. The exosomal size, morphology, and exosome markers were analyzed using a nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and an exosome detection antibody array. The tryptic fragment sequencing of exosome-contained proteins was performed using liquid chromatography–tandem mass spectrometry (LC-MS/MS) and a Thermo Lumos Fusion Tribrid Orbitrap mass spectrometer. The pathway analysis of the MS data was performed. Results: The number of exosome particles were significantly increased only in the RD with severe PVR group compared with the control groups and the RD without PVR or with mild PVR groups. Of 724 exosome proteins identified, 382 were differentially expressed (DE) and 176 were uniquely present in PVR. Both DE proteins and exosome proteins that were only present in PVR were enriched in proteins associated with previously known key pathways related to PVR development, including reactive retinal gliosis, pathologic cellular proliferation, inflammation, growth of connective tissues, and epithelial mesenchymal transition (EMT). The SPP1, CLU, VCAN, COL2A1, and SEMA7A that are significantly upregulated in PVR were related to the tissue remodeling. Conclusions: Exosomes may play a key role in mediating tissue remodeling along with a complex set of pathways involved in PVR development.

The MDM2 Single-Nucleotide Polymorphism T309G Is Associated With the Development of Epimacular Membranes.

Purpose: To investigate the role of the mouse double minute 2 (MDM2) gene single-nucleotide polymorphism (SNP) T309G in the development of epimacular membranes (EMMs) by analyzing the genotype distribution and consistency of the polymorphism in paired membrane-blood samples. Methods: This was a cross–sectional genetic association study of patients with proliferative vitreoretinopathy (PVR) or EMMs. PVR membranes (PVRMs), internal limiting membranes (ILMs) (PVR-ILMs) and blood samples (PVR-blood) from patients with PVR, and EMMs, EMM-ILMs and EMM-blood from patients with EMMs were collected. The genotype of all samples was determined by Sanger sequencing. Sex composition, mean age, the genotype distribution of MDM2 T309G, the allelic frequency of the MDM2 SNP309 G allele (% G) and the somatic mutation rate at the MDM2 T309G locus (% M) were analyzed and compared. The PVR and healthy Chinese donor groups were used as controls for different comparisons. Results: The EMM group of 62 patients was older than the PVR group of 61 patients by an average of 8.87 years (p < 0.0001), but the two groups were statistically similar in the sex composition (p = 0.1754). Importantly, G allele carriers were at a higher risk of developing EMMs than non-G allele carriers (p = 0.0479; OR = 2.047). Moreover, EMM-blood exhibited a significantly higher % G than blood samples from healthy Chinese donors (EMM-blood: 56.78%, donors: 45.61%; p = 0.0256; OR = 1.567). Regarding membrane-blood consistency, % M was significantly different between PVRMs and EMMs (PVRMs: 2.63%, EMMs: 21.57%; p = 0.0097; OR = 10.18) but not between different types of ILMs (PVR-ILMs: 18.18%, EMM-ILMs: 29.17%; p = 0.6855). Furthermore, EMMs (p = 0.0053; OR = 8.250) and EMM-ILMs (p = 0.0233; OR = 14.40) from patients with preoperative macular holes were more predisposed toward somatic mutations at the MDM2 T309G locus than those from patients without preoperative macular holes. Conclusions: MDM2 T309G is associated with the development of EMMs. Herein, the MDM2 SNP309 G allele is first reported as an associated factor of EMMs in a Chinese population. In addition, EMMs and ILMs are genetically unstable at the MDM2 T309G locus, especially when complicated with preoperative macular holes.

Results of pars plana vitrectomy with inferior retinotomy in inferior rhegmatogenous retinal detachments with inferior retinal breaks and proliferative vitreoretinopathy grades B or C

AbstractPurposeTo report the surgical outcomes of pars plana vitrectomy (PPV) with inferior retinotomy without the need for scleral buckling in primary inferior rhegmatogenous retinal detachment (RRD) with inferior retinal breaks and Proliferative vitreoretinopathy (PVR) grades B or C.MethodsRetrospective, consecutive series, single‐center study of patients that underwent PPV with inferior retinotomy for primary inferior RRD with inferior retinal breaks (4:00 to 8:00 clock hours) and PVR grades B or C. Data were obtained from patients’ medical records from October 2014 to November 2020. The primary outcomes of the study were retinal reattachment and visual acuity improvement. Data collected before and after surgery was compared between groups using chi‐square analysis and paired samples t‐test. The resulting p‐values significance level was set at p = 0.05.ResultsThirty‐two patients (32 eyes) met the inclusion criteria. PVR in stage B was present in 19 patients and stage C in 13 patients. Macula‐off RRD was diagnosed in 25 patients while the other 7 patients had RRD with the macula attached. Regarding primary outcomes, 31 out of 32 (97%) patients achieved retinal reattachment with no differences between PVR groups (p = 0.406). The best‐corrected visual acuity (BCVA) improved significantly in eyes with macula‐off RRD at presentation (p &lt; 0.001). Although macula‐attached RRD eyes had higher final BCVA, its improvement was not statistically significant (p = 0.370). Besides one retinal redetachment, no other significant complications were reported after surgery.ConclusionsInferior retinal breaks are associated with surgical failure following PPV for inferior RRD repair, especially if advanced PVR is present. Our results suggest that, in these less common and more challenging cases, PPV with an inferior retinotomy is associated with very favorable anatomic and visual outcomes.

Antioxidant Status in the Vitreous of Eyes with Rhegmatogenous Retinal Detachment with and without Proliferative Vitreoretinopathy, Macular Hole and Epiretinal Membrane.

(1) Background: The aim of the study was to test the hypothesis that the antioxidant status in the vitreous body of eyes, which had been vitrectomized due to rhegmatogenous retinal detachment (RRD) with or without proliferative vitreoretinopathy (PVR), is higher than in eyes vitrectomized due to other retinal diseases. (2) Methods: four patient groups were analyzed: 22 eyes of patients with RRD without PVR, 27 eyes with RRD and PVR, 22 eyes with macular hole (MH) and 10 eyes with epiretinal membrane (ERM). Spectrophotometric methods were used to determine the total antioxidant status (TAS) values as well as superoxide dismutase (SOD) and glutathione reductase (GR) activities in the vitreous fluid samples. (3) Results: no significant differences in TAS values and antioxidant enzyme activities were observed among patient with RRD with and without PVR and with MH and ERM. The longer the duration of RRD leading to PVR and better postoperative visual acuity, the higher the TAS level. No significant differences were found between “macula on” and “macula off” subgroups within the RRD group and the RRD combined with PVR group. (4) Conclusions: The preliminary results do not support the thesis that the antioxidant status of vitrectomized eyes is different in patients with RRD with or without PVR in comparison to patients with MH and ERM. In patients with RRD, PVR presence and detached macula do not affect the values of TAS, SOD and GR in the vitreous fluid. The duration of the disease influences TAS in the vitreous in eyes with RRD complicated with PVR.

Effect of aflibercept on proliferative vitreoretinopathy: Proteomic analysis in an experimental animal model

PurposeThe aim of this study was to monitor inflammatory, proliferative and progressive effects of proliferative vitreoretinopathy (PVR) and aflibercept treatment in dispase induced PVR rat model by proteomic analysis. Material and methodsA total of 35 male Long Evans pigmented rats were divided into three groups, namely, PVR (dispase+saline), PVR+aflibercept (dispase+aflibercept) and control. The PVR group received 2 μl of 0.03 IU/μl dispase and 2 μl saline, the PVR+aflibercept group received 2 μl of 0.03 IU/μl and 2 μl of 40 mg/ml aflibercept at the first day of the experiment. At the end of the 6th week all retina and vitreous specimens were collected by evisceration and transferred to the proteomics laboratory for analysis. Proteomic analysis by 2D gel electrophoresis coupled with MALDI-TOF/TOF was performed. ResultsIn the PVR and PVR+aflibercept group 16 different proteins that were identified to be differentially regulated in comparison to the control group. In the PVR+aflibercept group, ENO1, ENO2, LDH-B, PEBP-1 and GS levels were higher than the PVR group. In addition, the association of proteins such as UCHL, PEBP1, PDHB and ENO1 with PVR has been demonstrated for the first time. ConclusionSTRING analysis elucidated the functional protein-protein interaction among the differentially regulated proteins and highlighted that those proteins mainly played roles in carbon and nucleotide metabolisms. Functional analysis of the differentially regulated proteins indicated the presence of inflammation, gliosis and retinal damage in the PVR group. Aflibercept treatment had pronounced effect on prevention of inflammation and retinal damage while causing a slight increase in gliosis. However, aflibercept treatment was not effective enough to normalize the levels of differentially regulated proteins of the PVR group. Therefore, we predict that the treatment dose of aflibercept used in this study was below of its ideal concentration and should be increased in the future studies. The differential regulation of these structural proteins in this study should shed some light to the mechanism of glial wound formation in the retina and guide future treatment modalities.

Increased Glial Fibrillary Acid Protein and Vimentin in Vitreous Fluid as a Biomarker for Proliferative Vitreoretinopathy.

PurposeGlial fibrillary acid protein (GFAP) and vimentin are type III intermediate filament proteins, ubiquitously expressed in retinal glial cells. Under retinal stress, both GFAP and vimentin are well-known sensitive markers for retinal gliosis. However, little is known about whether these proteins are released into the vitreous body in response to retinal gliosis or are related to the severity of retinal gliosis seen in proliferative vitreoretinopathy (PVR).MethodsVitreous fluids were collected from 44 patients who underwent pars plana vitrectomy for macular hole (Group 1; n = 8), epiretinal membrane (Group 2; n = 8), or retinal detachment (RD) with various degrees of PVR (Group 3; n = 28). The severity of PVR was determined by cumulative scores using PVR classification. GFAP, vimentin, and total protein levels from the vitreous samples were measured.ResultsBoth GFAP and vimentin levels were significantly elevated in vitreous fluid from Group 3 (RD) compared with Groups 1 and 2 (P < 0.01). GFAP levels (ng/mL) were 12.4 ± 9.8, 17.5 ± 17.7, and 572.0 ± 11659.7, and vimentin levels (ng/mL) were 40.8 ± 61.9, 88.6 ± 86.8, and 3952.8 ± 8179.5 in Groups 1, 2, and 3, respectively. Total protein levels were not significantly different among the three groups. Elevated GFAP and vimentin levels in Group 3 were positively correlated with the areas of RD (P < 0.01, r = 0.53 in GFAP and P < 0.05, r = 0.46 in vimentin) and PVR scores (P < 0.05, r = 0.46 in GFAP and P < 0.00001, r = 0.76 in vimentin).ConclusionsOur data suggest that human vitreous GFAP and vimentin are protein biomarkers for PVR, and reactive gliosis may play a part in PVR formation.

Vitreous levels of Lipocalin-2 on patients with primary rhegmatogenous retinal detachment.

PurposeTo measure vitreous levels of Lipocalin2 (LCN2) in patients with rhegmatogenous retinal detachment (RRD) and investigate potential association with presence of proliferative vitreoretinopathy (PVR).Materials and methodsCollection of undiluted vitreous samples from 24 patients suffering from RRD and 10 control patients undergoing vitrectomy for: vitreomacular traction (VMT) (n = 2), idiopathic epiretinal membrane (iERM) (n = 6) and full thickness macular hole (FTMH) (n = 2). Quantitative analysis of LCN2 has been made with flow cytometry. Lens status, duration of symptoms, quadrants of detachment, as well as level of PVR, were assessed. Statistical analysis included Mann-Whitney test, Kruskal-Wallis test, t-test, Spearman’s correlation coefficient and Fisher's exact test.ResultsMedian LCN2 was significantly higher in the RRD group as compared to control (p<0.001). Within the RRD group there was a positive correlation between LCN2 and PVR grade (rs = 0.94, p<0.001). Median LCN2 was 35,759 pg/ml (IR = 55,347) in grade C PVR, 9,387 pg/ml (IR = 3721) in grade B, 4,917 pg/ml (IR = non computable) in grade A and 3,921 pg/ml (2132) in the no PVR group. Median LCN2 was also significantly higher in pseudophakic patients as compared to phakic patients (p = 0.007). LCN2 also correlates with the extend of detachment (≤2 vs >2 quadrants, p<0.001) as well as with duration of symptoms (rs = 0.87, p<0.001). After multivariate linear regression analysis, only PVR was independently related with LCN2 concentration. In particular, increased PVR grading was associated with increased LCN2 concentration (coefficient b = 2.97, 95% confidence interval = 1.89 to 4.67, p<0.001).ConclusionA positive correlation between vitreous levels of LCN2 and PVR grading reveals a potential role in the pathogenesis and progression of PVR. Further studies could elucidate if LCN2 could be a therapeutic target.

Correlation of transforming growth factor β-1 vitreous levels with clinical severity of proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment

Abstract Objective To correlate the vitreous concentration of transforming growth factor β-1 (TGF β-1) with the degree of clinical severity of proliferative vitreoretinopathy (PVR). Design A prospective, observational, cross-sectional study carried out on cases and controls. Participants The study included 40 patients with a diagnosis of PVR secondary to rhegmatogenous retinal detachment. Methods Vitreous was obtained in patients undergoing pars plana vitrectomy by rhegmatogenous retinal detachment, who were treated during the period from August 2015 to June 2016, in a national reference centre for ophthalmological care in Mexico City, Mexico. The levels of TGFβ-1 were quantified by ELISA technique. An ANOVA test was performed for the comparison of the different groups, together with a post hoc Dunns test. A statistically significant difference was considered when obtaining p Results The levels of TGFβ-1 were quantified, and the following means were found for each group: In the group with PVR grade A, 1150.6 ± 452.08 pg/ml, PVR grade B: 1129.6 ± 365.54 pg/ml, and PVR grade C: 1146.4 ± 330.21 pg/ml. The statistical analysis did not find significant differences when comparing the different PVR groups (p = 0.53). However, when performing the differential analysis for each level of severity, a statistically significant increase in the expression of TGFβ-1 was observed in the group of patients with PVR-A at a greater number of days of evolution of the detachment (p = 0.03). There were no statistically significant differences for PVR-B and PVR-C (p = 0.16 and p = 0.16, respectively). Conclusion Although the levels of TGFβ-1 are not directly related to the clinical severity grade, suggesting that there must be other factors involved in the advanced stages of PVR, TGFβ-1 may have greater relevance during the initial stages of the clinical course by promoting the epithelial–mesenchymal transition due to its greater expression in PVR-A. Thus, it can be concluded that each isoform plays a very particular role in the complex process of PVR.

Correlación de niveles del factor de crecimiento transformante β-1 con severidad de vitreorretinopatía proliferativa en pacientes con desprendimiento de retina regmatógeno

ObjectiveTo correlate the vitreous concentration of transforming growth factor β-1 (TGF β-1) with the degree of clinical severity of proliferative vitreoretinopathy (PVR). DesignA prospective, observational, cross-sectional study carried out on cases and controls. ParticipantsThe study included 40 patients with a diagnosis of PVR secondary to rhegmatogenous retinal detachment. MethodsVitreous was obtained in patients undergoing pars plana vitrectomy by rhegmatogenous retinal detachment, who were treated during the period from August 2015 to June 2016, in a national reference centre for ophthalmological care in Mexico City, Mexico. The levels of TGFβ-1 were quantified by ELISA technique. An ANOVA test was performed for the comparison of the different groups, together with a post-hoc Dunns test. A statistically significant difference was considered when obtaining P <.05. ResultsThe levels of TGFβ-1 were quantified, and the following means were found for each group: In the group with PVR grade A, 1150.6 ± 452.08 pg / ml, PVR grade B: 1129.6 ± 365.54 pg / ml, and PVR grade C: 1146.4 ± 330.21 pg / ml. The statistical analysis did not find significant differences when comparing the different PVR groups. (P=.53).However, when performing the differential analysis for each level of severity, a statistically significant increase in the expression of TGFβ-1 was observed in the group of patients with PVR-A at a greater number of days of evolution of the detachment. (P=.03). There were no statistically significant differences for PVR-B and PVR-C (P=.16 and P=.16, respectively). ConclusionAlthough the levels of TGFβ-1 are not directly related to the clinical severity grade, suggesting that there must be other factors involved in the advanced stages of PVR, TGFβ-1 may have greater relevance during the initial stages of the clinical course by promoting the epithelial-mesenchymal transition due to its greater expression in PVR-A. Thus, it can be concluded that each isoform plays a very particular role in the complex process of PVR.

Histopathological and ophthalmoscopic evaluation of apocynin on experimental proliferative vitreoretinopathy in rabbit eyes.

The aim of the current study was to evaluate the effect of apocynin (APO) on the development of proliferative vitreoretinopathy (PVR). New Zealand-type male rabbits were randomly grouped into three as follows: (1) Sham group rabbits which were applied intraperitoneal (i.p.) vehicle without PVR; (2) PVR group rabbits where PVR was created and an i.p. vehicle was administered for 21 successive days; (3) PVR+APO group rabbits where PVR was created and i.p. APO was administered for 21 successive days. Fundus examination was conducted with an indirect ophthalmoscope before starting the experiments and at each visit afterwards. At the end of the work, the rabbits were sacrificed under high-dose anesthesia and then eye tissues were taken for histopathological analyses. In the PVR+APO group, histopathologic and ophthalmoscopic examination revealed significant decrease in PVR formation. As the result, it has been observed that APO at least partially inhibits PVR formation.

The Role of Thrombin in Proliferative Vitreoretinopathy

To determine the role of thrombin in the development of proliferative vitreoretinopathy (PVR). Vitreous was collected from patients undergoing a vitrectomy (macular holes and puckers, n = 11 [controls]; retinal detachment without PVR development following vitrectomy, n = 15 [RRD1]; retinal detachment with PVR development within 6 months after vitrectomy, n = 11 [RRD2]; and established PVR, n = 14 [PVR]). Thrombin activity in vitreous was determined using a thrombin-specific chromogenic substrate. ARPE-19 cells were stimulated with 8× diluted vitreous samples in the presence and absence of hirudin. The samples were analyzed at t = 0 and t = 24 hours for the presence of 27 cytokines/chemokines and growth factors using a multiplex approach. In comparable studies, ARPE-19 cells were stimulated for 2 hours, and mRNA expression levels for CCL2, CXCL8, GMCSF, IL6, and PDGFB were determined by real-time quantitative (RQ)-PCR. Thrombin activity was significantly (P < 0.05) higher in vitreous of the PVR group compared to the other groups. Proliferative vitreoretinopathy vitreous stimulated the production of chemokine (C-C motif) ligand (CCL)2, chemokine (C-X-C motif) ligand (CXCL)8, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, and platelet-derived growth factor (PDGF)-BB by ARPE-19 to significantly (P < 0.05) higher levels than vitreous from the RRD1 and RRD2 groups. These effects of PVR vitreous were significantly (P < 0.05) reduced by hirudin. These data were confirmed by mRNA studies. Thrombin activity is increased in vitreous of patients with established PVR and is involved in the activation of proinflammatory and profibrotic pathways in RPE cells. Inhibition of thrombin activity may therefore represent a potential treatment option for proliferative vitreoretinopathy.

Expression of insulin-like growth factor binding protein-6 in the vitreous and serum in a proliferative vitreoretinopathy rat model

Background Proliferative vitreoretinopathy (PVR) is one of the major causes of retinal detachment surgery failure.Based on proteomic studies of PVR vitreous,the insulin-like growth factor binding protein-6 (IGFBP-6) protein was specifically expressed in the vitreous and serum of PVR patients.Furthermore,its expression level is higher in the vitreous and serum in severe PVR patients than that in mild PVR patients.Objective This experiment was to detect the expression of IGFBP-6 in a PVR rat model.Methods Seventy 7-week old male SPF Wistar rats were included and were randomized into the PVR model group and control group.A mixture of RPE-J cell suspension(5 μl) and platelet-rich plasma (5 μl) was intravitreally injected in the left eyes of adult Wistar rats to establish the PVR model,and normal saline solution was administered in the same way in the control group.The rat eyes were clinically examined 1 week,2,3 and 4 weeks after injection,and PVR was graded based on the criteria of Francine.The animals were sacrificed after 1 week,2,4 or 8 weeks for the preparation of retinal sections and liver extraction.Expression levels of IGFBP-6 mRNA in the rat retina and liver were assayed by real-time Q-PCR.The expression of IGFBP-6 protein in the rat serum and vitreous was detected by ELISA.The use of animals complied with the Regulations for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Commission.Results Purified IGFBP-6 RNA was extracted from the liver and retina of Wistar rat and quantified by real-time Q-PCR.The expression level of IGFBP-6 mRNA in retina was (3.79± 1.33) × 10-4 in the PVR model rats,showing a significant decline in comparison with the control rats with a level of(8.32±2.96) × 10 4,4 weeks after injection (t =3.42,P＜0.01).The expression of IGFBP-6 mRNA in the 4th week was significantly lower than that of 1 week,2 or 8 weeks after the establishment of the PVR model(P＜0.05).No significant difference was found in the IGFBP-6 mRNA level in the liver between the PVR group and control group(27.60± 14.01 × 10 4 vs.25.01 ± 12.04 ×10-4,respectively),as well as among the different time points(P＞0.05).IGFBP-6 mRNA content in the retina was significantly reduced in grades 1,2 or 3 of the PVR groups compared with the control group(P＞0.05),but there was no significant difference among the different grades of PVR groups (P＞0.05).Concentrations of IGFBP-6 protein in grades 1,2 and 3 of the PVR model group were (221.00 ± 19.32),(229.63 ± 18.89) and (225.70 ± 26.71) μg/L,with a significant elevation in comparison with (173.25 ±21.11) μg/L of the control group (t =2.14,P＜0.05).However,there was no significant change among the different grades of PVR groups(t=1.24,1.46,P＞0.05).The concentrations of IGFBP-6 protein in the vitreous and serum were higher in PVR rat samples (vitreous:225.44±19.36 μg/L;serum:108.48 ± 15.78 μg/L) than in control rats (vitreous:173.25 ± 21.11 μg/L,serum:95.96 ±17.40 μg/L)(P＜0.05).Conclusions The concentrations of IGFBP-6 protein in the vitreous and serum increase in PVR rats.The results indicate that the increased IGFBP-6 in the vitreous might be a localized autocrine secretion of the eye. Key words: Insulin-like growth factor binding protein; Proliferative vitreoretinopathy; Rat/ model; Retina

Prediction of Proliferative Vitreoretinopathy after Retinal Detachment Surgery: Potential of Biomarker Profiling

To investigate the potential of a combined assessment of clinical risk factors and biomarker profiling in the prediction of proliferative vitreoretinopathy (PVR) after retinal detachment surgery. Retrospective case-control study. Multiplex bead-based immunoassays were used for the simultaneous measurement of 50 biomarkers in subretinal fluid samples obtained from patients who underwent scleral buckling surgery for primary rhegmatogenous retinal detachment (RRD). Of 306 samples that were collected and stored in our BioBank, we selected 21 samples from patients in whom a redetachment developed as a result of PVR within 3 months after reattachment surgery for primary RRD (PVR group). These were compared with age-, sex-, and storage time-matched RRD samples from 54 patients with an uncomplicated postoperative course after primary RRD repair (RRD group). Preoperative PVR was the only clinical variable that was an independent predictor of postoperative PVR development (P = .035) and resulted in an area under the receiver operating characteristic curve of 0.67 (95% confidence interval, 0.51 to 0.83). The addition of the biomarkers chemokine (C-C motif) ligand 22, interleukin-3, and macrophage migration inhibitory factor improved the model significantly (P < .001) and resulted in an area under the receiver operating characteristic curve of 0.93 (95% confidence interval, 0.82 to 1.04). A sensitivity of 94.1% and a specificity of 94.2% were reached, using a cutoff value of 5%. In combination with preoperative PVR grade, the measurement of a single biomarker or a small multibiomarker panel shows great potential and may predict postoperative PVR development after primary RRD in a highly sensitive and specific manner.

THE IMPACT OF TACROLIMUS ON GROWTH FACTORS IN EXPERIMENTAL PROLIFERATIVE VITREORETINOPATHY

To investigate the effect of intravitreal tacrolimus on an animal model of proliferative vitreoretinopathy (PVR) and on growth factors implicated in its pathogenesis. Twenty-one guinea pigs were randomly assigned to one of three groups of seven animals each: no-PVR/saline group (no PVR/intravitreal saline-injected group), PVR/saline group (dispase-induced PVR group, treated with control injections of intravitreal saline), and PVR/tacrolimus group (treatment group, dispase-induced PVR group treated with intravitreal tacrolimus injections). At the end of the experiment, eyes were enucleated and the identification of the stages of PVR was carried out. While a halves of the enucleated globes were evaluated histopathologically for PVR formation, the retinas of the other halves of globes were used for the preparation of retinal homogenates. The transforming growth factor-β, platelet-derived growth factor, and fibroblast growth factor levels in homogenized retina tissues were measured by the enzyme-linked immunosorbent assay method. When assessing the average PVR stages in terms of severe PVR rates, the PVR/tacrolimus group had significantly improved when compared with the PVR/saline group. The PVR/tacrolimus group demonstrated significantly decreased levels of transforming growth factor-β, platelet-derived growth factor, and fibroblast growth factor when compared with the PVR/saline group and also demonstrated significant improvement in epiretinal membrane formation and retinal fold in the presence of histopathologic levels. The difference in degradation of photoreceptor cells between the PVR/tacrolimus and the PVR/saline groups was not statistically significant. This study suggests that intravitreal tacrolimus application may suppress PVR development and that tacrolimus may merit investigation for the prophylaxis of PVR.

ANTIANGIOGENIC ISOFORMS OF VASCULAR ENDOTHELIAL GROWTH FACTOR PREDOMINATE IN SUBRETINAL FLUID OF PATIENTS WITH RHEGMATOGENOUS RETINAL DETACHMENT AND PROLIFERATIVE VITREORETINOPATHY

In proliferative vitreoretinopathy (PVR), a nonangiogenic eye disease that is characterized by the formation of mainly avascular membranes, vascular endothelial growth factor (VEGF) levels are found to be upregulated. Recently, it was discovered that VEGF is alternatively spliced to form the angiogenic (VEGF xxx) and antiangiogenic (VEGF xxx b) family of isoforms. Previous studies on expression of VEGF in PVR samples have not distinguished between the two families of isoforms. We measured total VEGF and VEGF xxx b levels in subretinal fluid of patients with PVR (n = 10) and in patients with uncomplicated rhegmatogenous retinal detachment (n = 27) using enzyme-linked immunosorbent assay. : We found total VEGF levels to be 2- to 3-fold elevated in the PVR group as compared with the rhegmatogenous retinal detachment group (P = 0.047). Antiangiogenic VEGF xxx b isoforms predominated (>60% of total VEGF) in the majority of rhegmatogenous retinal detachment and PVR samples investigated, although a wide variability of isoform ratios was observed within both groups. The absence of an increased ratio of VEGF xxx to VEGF xxx b in patients with PVR as compared with patients with uncomplicated rhegmatogenous retinal detachment may explain a lack of blood vessels in PVR membranes. Elevated VEGF levels indicate that this cytokine may play a role in the pathogenesis of PVR that is not related to angiogenesis.

Adipokine levels in subretinal fluid from patients with rhegmatogenous retinal detachment

Adipokines have recently emerged as a novel group of mediators with important roles in inflammatory and immune responses and in the process of wound healing. This study investigated the involvement of several adipokines in the future development of proliferative vitreoretinopathy (PVR) following reattachment surgery for rhegmatogenous retinal detachment (RRD). A multiplex immunoassay was used to measure 6 different adipokines in 75 subretinal fluid samples collected during reattachment surgery for primary RRD. Twenty-one patients who developed a redetachment due to postoperative PVR after scleral buckling surgery (PVR group) were compared with age-, sex-, and storage-time-matched RRD samples from 54 patients with an uncomplicated postoperative course (RRD group). Levels of adiponectin ( P = 0.006), cathepsin S ( P = 0.001), and leptin ( P = 0.041) were significantly elevated in the PVR group as compared to the RRD group. Levels of tissue inhibitor of metalloproteinase (TIMP)-1 were significantly lower in the PVR group than in the RRD group ( P = 0.044). After correction for diabetes, body mass index (BMI), macular involvement, and preoperative PVR, the association between postoperative PVR development and adiponectin, cathepsin S, and TIMP-1 remained statistically significant ( P < 0.05), whereas the significant correlation between PVR and elevated leptin levels was lost ( P = 0.068). There were no significant differences in levels of chemerin ( P = 0.351) and adipsin ( P = 0.915). Of all adipokines investigated, multivariate logistic regression analysis showed that adiponectin was the exclusive predictor of the development of postoperative PVR after scleral buckling surgery ( P = 0.003). Our findings indicate that, at the time of surgery for primary RRD, an altered expression of certain adipokines is associated with the future development of postoperative PVR.