TLR9 signalling activation via direct ligation and its functional consequences in CD4 + T cells.

CpG Oligodeoxynucleotides (ODNs) are established TLR9 ligands; however, their functional responses in CD4+ T cells are believed to be independent of TLR9 and MyD88. We studied ligand-receptor interactions of ODN 2216 and TLR9 in human CD4+ T cells and assessed their consequences in terms of TLR9 signalling and cell phenotype. We demonstrated that the uptake of ODN 2216, a synthetic TLR9 agonist, is controlled by TLR9 signalling molecules and results in an increase in the expression of TLR9 signalling molecules, regulated via a feedback mechanism. Next, the uptake of ODN 2216 resulted in TLR9 signalling dependent but MyD88 independent increase in expression of TGF-ß. Finally, ODN 2216 treated CD4+ T cells showed an anti-inflammatory phenotype that was similar to Th3 type of regulatory T cells. These Th3-like cells were able to suppress the proliferation of untreated CD4+ T cells. Collectively, our results demonstrate a direct and interdependent relationship between ODN 2216 uptake and TLR9 signalling in CD4+ T cells. Our findings thus pave the way for future research to explore direct modulation of adaptive immune cells, using innate immune ligands, to subvert exaggerated inflammatory responses.

Collaborative Ocular Tuberculosis Study Consensus Guidelines on the Management of Tubercular Uveitis-Report 1: Guidelines for Initiating Antitubercular Therapy in Tubercular Choroiditis.

TOPIC: An international, expert-led consensus initiative organized by the Collaborative Ocular Tuberculosis Study (COTS), along with the International Ocular Inflammation Society and the International Uveitis Study Group, systematically developed evidence- and experience-based recommendations for the treatment of tubercular choroiditis. CLINICAL RELEVANCE: The diagnosis and management of tubercular uveitis (TBU) pose a significant challenge. Current guidelines and literature are insufficient to guide physicians regarding the initiation of antitubercular therapy (ATT) in patients with TBU. METHODS: An international expert steering subcommittee of the COTS group identified clinical questions and conducted a systematic review of the published literature on the use of ATT for tubercular choroiditis. Using an interactive online questionnaire, guided by background knowledge from published literature, 81 global experts (including ophthalmologists, pulmonologists, and infectious disease physicians) generated preliminary consensus statements for initiating ATT in tubercular choroiditis, using Oxford levels of medical evidence. In total, 162 statements were identified regarding when to initiate ATT in patients with tubercular serpiginous-like choroiditis, tuberculoma, and tubercular focal or multifocal choroiditis. The COTS group members met in November 2018 to refine these statements by a 2-step modified Delphi process. RESULTS: Seventy consensus statements addressed the initiation of ATT in the 3 subtypes of tubercular choroiditis, and in addition, 10 consensus statements were developed regarding the use of adjunctive therapy in tubercular choroiditis. Experts agreed on initiating ATT in tubercular choroiditis in the presence of positive results for any 1 of the positive immunologic tests along with radiologic features suggestive of tuberculosis. For tubercular serpiginous-like choroiditis and tuberculoma, positive results from even 1 positive immunologic test were considered sufficient to recommend ATT, even if there were no radiologic features suggestive of tuberculosis. DISCUSSION: Consensus guidelines were developed to guide the initiation of ATT in patients with tubercular choroiditis, based on the published literature, expert opinion, and practical experience, to bridge the gap between clinical need and available medical evidence.

Collaborative Ocular Tuberculosis Study Consensus Guidelines on the Management of Tubercular Uveitis-Report 2: Guidelines for Initiating Antitubercular Therapy in Anterior Uveitis, Intermediate Uveitis, Panuveitis, and Retinal Vasculitis.

TOPIC: The Collaborative Ocular Tuberculosis Study (COTS), supported by the International Ocular Inflammation Society, International Uveitis Study Group, and Foster Ocular Immunological Society, set up an international, expert-led consensus project to develop evidence- and experience-based guidelines for the management of tubercular uveitis (TBU). CLINICAL RELEVANCE: The absence of international agreement on the use of antitubercular therapy (ATT) in patients with TBU contributes to a significant heterogeneity in the approach to the management of this condition. METHODS: Consensus statements for the initiation of ATT in TBU were generated using a 2-step modified Delphi technique. In Delphi step 1, a smart web-based survey based on background evidence from published literature was prepared to collect the opinion of 81 international experts on the use of ATT in different clinical scenarios. The survey included 324 questions related to tubercular anterior uveitis (TAU), tubercular intermediate uveitis (TIU), tubercular panuveitis (TPU), and tubercular retinal vasculitis (TRV) administered by the experts, after which the COTS group met in November 2019 for a systematic and critical discussion of the statements in accordance with the second round of the modified Delphi process. RESULTS: Forty-four consensus statements on the initiation of ATT in TAU, TIU, TPU, and TRV were obtained, based on ocular phenotypes suggestive of TBU and corroborative evidence of tuberculosis, provided by several combinations of immunologic and radiologic test results. Experts agreed on initiating ATT in recurrent TAU, TIU, TPU, and active TRV depending on the TB endemicity. In the presence of positive results for any 1 of the immunologic tests along with radiologic features suggestive of past evidence of tuberculosis infection. In patients with a first episode of TAU, consensus to initiate ATT was reached only if both immunologic and radiologic test results were positive. DISCUSSION: The COTS consensus guidelines were generated based on the evidence from published literature, specialists' opinions, and logic construction to address the initiation of ATT in TBU. The guidelines also should inform public policy by adding specific types of TBU to the list of conditions that should be treated as tuberculosis.

Direct Engagement of TLR9 Ligand with T Helper Cells Leads to Cell Proliferation & Up-regulation of Cytokines.

PURPOSE: Toll like receptor (TLR) engagement is primarily a function of the innate immune cells. The purpose of the study was to assess direct uptake of ODN 2216 in T helper cells and effects on cell proliferation and cytokine expression. METHODS: We isolated CD4+ CD25- T helper cells by magnetic sorting and studied the uptake of ODN 2216 using flow cytometry and confocal microscopy. We then studied the effect of ODN 2216 engagement on cell proliferation and cytokine expression using flow cytometry and gene expression of TLR9 signaling genes using real time RT-PCR. RESULTS: We made a chance observation that purified T helper cells from healthy individuals consistently bind to the TLR9 ligand ODN 2216. In PBMCs, on the other hand, 98% of monocytes preferentially bound to ODN 2216 FITC, indicating that they competed with the lymphocytes. We confirmed intracellular localization of ODN 2216 FITC as well as intracellular expression of TLR9 in Thelper cells. Furthermore, ODN 2216 FITC was also co-localized with the lysosomal membrane associated protein 1. The uptake of TLR9 ligand culminated in cellular proliferation, up-regulation of cytokines and increased mRNA expression of TLR9 and IRF7 in T helper cells, in the absence of antigen presenting cells. ODN 2216 uptake was inhibited by promethazine as well as by TLR9 antagonist. CONCLUSIONS: Our results show a direct engagement of TLR9 ligand in T helper cells and suggest involvement of TLR9 signalling in CD4+T cells, which may envisage novel targets for TLR inhibitors.

Immune Profiling of T Cells Infiltrating Vitreous Humor in Tubercular Uveitis.

PURPOSE: To assess cellular composition and local cytokine response in vitreous humor of tubercular uveitis. METHODS: Cells were collected from vitreous cassettes and peripheral blood of 8 tubercular uveitis and 5 control subjects, undergoing vitrectomy and analyzed by flow cytometry for cellular composition, activation status, proinflammatory cytokine expression, and uptake of TLR9 ligand, CpG ODN 2216. RESULTS: CD3 + T cells with equal proportion of CD4+ and CD8 + T cells formed major fraction of infiltrating cells. The vitreous humor showed higher expression of recent activation marker, CD69, and proinflammatory cytokines, IFN-γ and IL-17A, in CD4 + T cells as compared to peripheral blood. Lastly, intraocular CD4 + T cells showed reduced uptake of ODN 2216 than peripheral blood. CONCLUSIONS: Our results indicate that local antigenic stimuli trigger T cell infiltration and activation of CD4 + T cells that are hyporesponsive to TLR9 stimulation. These infiltrating T cells might be responsible in further aggravating ocular inflammation.

Epidemiology and clinical features of inflammatory retinal vascular occlusions: pooled data from two tertiary-referral institutions.

IMPORTANCE: In a subset of patients with retinal vasculitis, there is occlusion of blood flow through the retinal vessels. These eyes are at high risk of sight-threatening complications. BACKGROUND: To characterize epidemiology, clinical course, treatment and outcomes of occlusive retinal vasculitis (ORV). DESIGN: Retrospective study PARTICIPANTS: Seventy-seven uveitis patients with ORV at two large tertiary-care institutions (the USA and India). METHODS: Out of 2438 patients screened, 346 patients were diagnosed with retinal vasculitis of which 77 patients (96 eyes) were diagnosed with ORV. Patients with ORV (capillary, arteriolar and/or venular) were further analysed. Diagnostic criteria for occlusive vasculitis included (i) absence of blood flow in vessels (arterioles, venules and/or capillaries), (ii) capillary non-perfusion areas and/or arteriolar-venous anastomosis and (iii) intraretinal haemorrhages, cotton-wool spots or vitreous haemorrhage. MAIN OUTCOME MEASURES: Best-corrected visual acuity, treatment and complications. RESULTS: The mean age was 32.09 ± 13.51 years. Most common aetiologies were tuberculosis and Adamantiades-Behçet's disease in India and systemic lupus erythematosus in the USA. Best-corrected visual acuity improved from 0.38 ± 0.30 logMAR (20/48 Snellen equivalent) (baseline) to 0.25 ± 0.30 (20/35 Snellen equivalent) at final visit (P < 0.0001). Vitreous haemorrhage was seen in 31.08% eyes. Pars plana vitrectomy was performed in 12.16% eyes. Therapy with systemic steroids was required in 78.48% patients. In addition, 46.75% patients required immunomodulators and/or biologics. CONCLUSIONS: Occlusive retinal vasculitis is caused by heterogeneous group of uveitides depending upon the geographic location. It is imperative to identify eyes with ORV as they are predisposed to complications requiring aggressive therapy.

OCT angiography demonstrates retinal angiomatous proliferation and chorioretinal anastomosis of type 3 neovascularization.

PURPOSE: To report the OCT angiography findings of type 3 neovascularization. METHODS: Two cases (one each with retinal angiomatous proliferation and chorioretinal anastomosis) are reported, in which the conventional fundus fluorescein angiography and spectral-domain optical coherence tomography findings were inconclusive. RESULTS: OCT angiography demonstrated flow within the abnormal anastomotic network and delineated the extent of the lesion with respect to the retinal layers. CONCLUSION: OCT angiography enables a quick diagnosis of type 3 neovascularization by demonstrating a supranormal flow within the lesion and delineates the lesion within different retinal layers.

Efficacy of Ozurdex implant in recalcitrant diabetic macular edema--a single-center experience.

The purpose of this study is to report the efficacy of intravitreal Ozurdex implant in managing recalcitrant diabetic macular edema. Retrospective interventional non-randomized study of patients with recalcitrant diabetic macular edema who received intravitreal Ozurdex implant. Main outcome measures were change in the central macular thickness, visual acuity, and intraocular pressure. Sixty-seven eyes of 52 patients with recalcitrant diabetic macular edema with a mean duration of 45.4 ± 22.5 months (range 6-96 months) were studied. Mean central macular thickness decreased from 514.2 ± 177.8 µm at baseline to 394.3 ± 152.2 µm (p = 0.007), 301.8 ± 93.0 µm (p < 0.000), 316.4 ± 115.6 µm (p < 0.000), and 419.9 ± 186.3 µ (p = 0.03) at 1, 6, 12, and 24 weeks, respectively. Mean best corrected visual acuity changed from 0.82 ± 0.46 log MAR to 0. 69 ± 0.44 log MAR (p = 0.122), 0.61 ± 0.40 log MAR (p = 0.007), 0.65 ± 0.37 log MAR (p = 0.024), and 0.68 ± 0.49 log MAR (p = 0.091) at 1, 6, 12, and 24 weeks, respectively. Single injection of intravitreal Ozurdex implant led to progressive decrease in central macular thickness with maximum percentage decrease at 6 weeks (41.2 %) from the baseline which was maintained up to 12 weeks. Eight eyes showed transient rise in intraocular pressure at 2 months which was controlled by antiglaucoma medications.

Detection of Mycobacterium tuberculosis genome in vitreous fluid of eyes with multifocal serpiginoid choroiditis.

PURPOSE: To compare 3 different molecular techniques to detect the Mycobacterium tuberculosis genome in vitreous fluid of eyes with multifocal serpiginoid choroiditis (MSC). DESIGN: Prospective, interventional case series. PARTICIPANTS: Eleven patients (11 eyes) with active MSC in at least 1 eye underwent diagnostic pars plana vitrectomy (PPV) between October 2012 and December 2013. METHODS: Vitreous fluid samples were subjected to multitargeted polymerase chain reaction (PCR) for a M. tuberculosis assay, the Gene Xpert MTB/RIF assay (Cepheid, Sunnyvale, CA), and a line probe assay (GenoType MTBDRplus; Hain Lifescience, GmbH, Nehren, Germany). The samples with positive results were subjected to rpoB gene sequencing to demonstrate rifampicin resistance. The clinical details, digital fundus imaging, and treatment details and outcomes also were noted. MAIN OUTCOME MEASURES: Detection of the M. tuberculosis genome and rifampicin resistance in the vitreous samples. RESULTS: Of the 11 eyes subjected to PPV, the multitargeted PCR results for tuberculosis were positive for 10 eyes, the MTBDRplus assay results were positive in 6 eyes, and the Gene Xpert MTB/RIF assay results were positive in 4 eyes. Rifampicin resistance was detected in 3 eyes by rpoB gene sequencing, in 3 eyes by the MTBDRplus assay, and in 1 eye by the Gene Xpert MTB/RIF assay. CONCLUSIONS: We detected the M. tuberculosis genome in the vitreous fluid of eyes with MSC using 3 different molecular techniques. Rifampicin resistance was detected for the first time in eyes with MSC.

Enhanced depth imaging spectral domain optical coherence tomography versus ultrasonography B-Scan for measuring retinochoroidal thickness in normal eyes.

PURPOSE: To assess the accuracy of retinochoroidal thickness measurements obtained by ultrasonography (USG) B-Scan (over eyelids) and high-resolution immersion USG (with lids open) compared with enhanced depth imaging optical coherence tomography (EDI-OCT) in normal subjects. METHODS: Retinochoroidal thickness measurements were performed in normal subjects using USG over eyelids and high-resolution immersion USG (with lids open) using the 20-MHz probe keeping EDI-OCT as the gold standard. Mean retinochoroidal thickness at the fovea, 1.5 mm nasally and temporally were analyzed for interobserver agreement using intraclass correlation coefficient test. Paired t-test was used to compare the values obtained by the three techniques. A 10% difference was defined as clinically significant in the measurements obtained using USG compared with EDI-OCT. RESULTS: Thirty-two eyes of 18 healthy volunteers (15 men) with normal baseline ophthalmologic examination (spherical equivalent, -2 to +2 diopter) were enrolled. Retinochoroidal thickness measurements showed good interobserver agreement for EDI-OCT (intraclass correlation coefficient = 0.999), immersion USG (intraclass correlation coefficient = 0.983), and USG over eyelids (intraclass correlation coefficient = 0.97). Mean retinochoroidal thickness using the above 3 techniques measured 631.77 ± 98.48, 617.17 ± 95.22, and 953 ± 151.28 µm, respectively. Immersion USG measurements were not significantly different from the gold standard, that is, EDI-OCT. However, over eyelids USG provided significantly higher values (P < 0.001) when compared with EDI-OCT and immersion USG. CONCLUSION: Ultrasonography over eyelids overestimates the retinochoroidal thickness. Immersion USG provides values comparable with EDI-OCT and high-quality imaging where EDI-OCT cannot be performed.

Choroidal granulomas visualized by enhanced depth imaging optical coherence tomography.

PURPOSE: To assess the visualization of choroidal granulomas (CG) by enhanced depth imaging optical coherence tomography (EDI-OCT) and to describe their EDI-OCT characteristics. METHODS: Combined indocyanine green (ICG) angiography and EDI-OCT images of 44 CG (sarcoid, tubercular, or Vogt-Koyanagi-Harada related) were reviewed. By ICG angiography, CG were classified as full thickness or partial thickness and as small or large. Two independent operators evaluated EDI-OCT scans over granulomas to record their characteristics (full thickness/partial thickness, shape, reflectivity, internal pattern, margins, and shadowing/increased transmission effect). The agreement between ICG angiography and EDI-OCT, the interobserver agreement, and the correlations between EDI-OCT features and lesion size or disease were studied. RESULTS: Enhanced depth imaging optical coherence tomography could visualize 100% of CG detected on ICG. Lesions resulted full thickness in 90.9% and 77.3% of the cases on ICG angiography and EDI-OCT, respectively (K = 0.5). All CG were more homogeneous and showed increased transmission of the optical coherence tomography signal as compared with the surrounding choroid. Choroidal granulomas angiographic size influenced lesions characteristics on EDI-OCT. Large granulomas were more likely to be full thickness, round shaped, with defined margins, lower reflective than the surrounding structures, and with internal homogenous pattern. The type of disease significantly influenced CG shape and pattern. Most of tubercular-related lesions showed lobulated shape and nonhomogeneous internal pattern. CONCLUSION: Enhanced depth imaging optical coherence tomography is suitable to visualize CG and to describe their characteristics. Choroidal granulomas size and disease influence lesions appearance on EDI-OCT. Increased transmission effect could be helpful for CG identification.

Thrombophilic risk factors are uncommon in young patients with retinal vein occlusion.

PURPOSE: To study the thrombotic factors, namely deficiencies of plasma proteins C, S, and antithrombin, factor V Leiden mutation, and positivity for antiphospholipid antibodies in young patients with retinal vein occlusion. METHODS: The thrombophilia parameters listed above were analyzed from the laboratory records of 50 patients with the clinical diagnosis of retinal vein occlusion, aged less than 50 years. RESULTS: A single prothrombotic factor was seen in 2 (4%) cases. The highest positivity was for the antiphospholipid antibodies (lupus anticoagulant in 6%, anticardiolipin antibodies in 2%, and anti-ß 2 glycoprotein 1 in 10% cases). Other than one case where antiphospholipid syndrome was confirmed, these were transient. One patient had antithrombin deficiency. Protein C and protein S deficiency and factor V Leiden mutation were not seen in this group. CONCLUSION: Our data suggest that these thrombophilia risk factors are not commonly associated with retinal vein occlusion, and there is a need for studies on other factors that contribute to the development of this condition.

Giant cell arteritis in India: Report from a tertiary care center along with total published experience from India.

OBJECTIVES: Giant cell arteritis (GCA) is a granulomatous large vessel vasculitis with very scarce data from India. The purpose of this study was to present a comprehensive data of all published Indian cases along with our experience from North India. MATERIALS AND METHODS: This was a retrospective study of all patients diagnosed to be having GCA according to the American College of Rheumatology criteria at a large tertiary care hospital. The demographic data, clinical, investigations, treatment details, and outcomes were noted. Details of all case series and case reports published from India were pooled along with our experience in order to generate a cumulative data of all cases from India. This was then compared with several large published case series from South America, Europe, and Asia. RESULTS: A total of 72 patients (17 patients in the present series and another 55 patients from other Indian case series and case reports) were identified. The findings of our study are similar to the studies published from other parts of the world, except for the onset of the disease a decade earlier, a male predilection, a lower temporal artery biopsy positivity, and a higher incidence of ophthalmic complications. CONCLUSIONS: Indian patients with GCA have an earlier age of onset, male preponderance, and higher ophthalmic complications.

Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography.

The purpose is to study the ability of an event-based analysis of retinal nerve fibre layer (RNFL) attenuation measured by Stratus(®) optical coherence tomography (OCT) and to detect progression across the spectrum of glaucoma. Adult glaucoma suspects, ocular hypertensives and glaucoma patients who had undergone baseline RNFL thickness measurement on Stratus OCT and reliable automated visual field examination by Humphrey's visual field analyser prior to March 2007 and had 5-year follow-up data were recruited. Progression on OCT was defined by two criteria: decrease in average RNFL thickness from baseline by at least 10 and 20 µ. Visual field progression was defined by the modified Hodapp-Parrish-Anderson criteria. Absolute and percentage change in RNFL thickness from baseline was compared in progressors and non-progressors on visual fields. Concordance between structural and functional progression was analysed. 318 eyes of 162 patients were analysed. 35 eyes (11 %) progressed by visual fields, 8 (2.5 %) progressed using the 20 µ loss criterion, while 30 eyes (9.4 %) progressed using the 10 µ loss criterion. In glaucoma suspects, mean absolute RNFL attenuation was 8.6 µ (12.1 % of baseline) in those who progressed to glaucoma by visual fields. OCT was more useful to detect progression in early glaucoma, but performed poorly in advanced glaucoma. The 10 µ criterion appears to be closer to visual field progression. However, the ability to detect progression varies considerably between functional and structural tools depending upon the severity of the disease.

Does toll-like receptor-3 (TLR-3) have any role in Indian AMD phenotype?

Age-related macular degeneration (AMD) is a devastating disease that results in irreversible central vision loss. TLRs signaling pathway has been found to play an important role in AMD pathogenesis as evidenced by several studies. The objective of the study was to determine the single nucleotide polymorphism (SNP) changes in TLR3 in North Indian AMD patients. We recruited 176 patients comprising 115 AMD patients and 61 controls. Real time PCR was used to evaluate the SNP changes at rs3775291 locus. Pearson's χ(2) test was used evaluate association between various groups. No significant association in genotype and allele frequency was found in AMD patients as compared to control. The results suggest that AMD pathology in North Indian AMD patients is not affected by TLR3 signaling but it could be influenced by other genetic or environmental factors unique to North India.

Outcome of cytomegalovirus retinitis in immunocompromised patients without Human Immunodeficiency Virus treated with intravitreal ganciclovir injection.

PURPOSE: To study the outcomes of treatment with intravitreal ganciclovir injection for cytomegalovirus (CMV) retinitis in patients without Human Immunodeficiency Virus (HIV) infection. METHODS: In this retrospective cohort study, demographic and clinical characteristics of patients with CMV retinitis without HIV were noted. Patients received intravitreal ganciclovir injection (2 mg/0.1 ml) alone until quiescence. The outcome measures were time taken for the lesions to heal, number of injections, change in best-corrected visual acuity (BCVA), recurrence of retinitis, occurrence of immune recovery uveitis (IRU) or injection-related complications and retinal detachment (RD). RESULTS: 18 eyes of ten patients (six males) with mean age of 33.7 years from June 2004 to March 2013 were included. Thirteen eyes with active lesions (mean BCVA of 0.51 ± 0.41) received 5.54 ± 3.36 intravitreal ganciclovir injections with complete healing within 1.81 ± 1.25 months. The final BCVA was 0.43 ± 0.52. IRU was observed in six eyes (33.33%) and RD developed in one eye. One eye had recurrence 1 month after stopping ganciclovir injections. The rest of the patients had recurrence-free follow-up at 9.46 ± 12.42 months. CONCLUSIONS: Non-HIV patients with CMV retinitis can be successfully treated with intravitreal ganciclovir injection alone, avoiding the systemic side effects of systemic anti-CMV therapy.

Pathological vitreous causes cell line-derived (but not donor-derived) retinal pigment epithelial cells to display proliferative vitreoretinopathy-like features in culture.

BACKGROUND: It is well understood that epithelial mesenchymal transformation occurs when retinal pigment epithelial cells, sourced from either a cell line or cadaver eye, are cultured in the presence of cadaver-derived vitreous. We sought to study the changes in retinal pigment epithelial cells when cell line-derived retinal pigment epithelial cells are cultured in the presence of pathological vitreous. DESIGN: Prospective study. SAMPLES: 42 patients with rhegmatogenous retinal detachments. METHODS: D407 retinal pigment epithelial cells were cultured in the presence of cadaver-derived vitreous or vitreous/subretinal fluid derived from patients undergoing retinal reattachment surgeries. Besides the changes in phenotypic characteristics, the viability, proliferation, migration, mesenchymal marker expression and changes in the extracellular matrix components were also evaluated. MAIN OUTCOME MEASURES: Fibrotic phenotype in cell culture. RESULTS: Our study clearly demonstrates that cell line-derived retinal pigment epithelial cells (unlike donor-derived retinal pigment epithelial cells) cultured in the presence of patient-derived vitreous/subretinal fluid, exhibit characteristic features of proliferative vitreoretinopathy. CONCLUSIONS: We propose that it is the synergistic effect of the combined use of (i) pathological vitreous, rather than cadaver-derived vitreous (since rhegmatogenous retinal detachment-derived pathological vitreous and subretinal fluid contain exaggerated amounts of growth factors, which could predispose to proliferative vitreoretinopathy development) and (ii) cells from an immortal cell culture (cell line), rather than from primary cell cultures (since cells subjected to continuous serial passaging acquire some mesenchymal characteristics), which together result in not only a unique phenotype, but also prime these cells towards display of features associated with proliferative vitreoretinopathy.