Giant retinal pigment epithelial tear following photodynamic therapy for the bullous variant of central serous chorioretinopathy: A case report

RATIONALE

The bullous variant of central serous chorioretinopathy (CSC) is a severe form of chronic CSC. Patients with the bullous variant of CSC have an increased risk of experiencing multiple pigment epithelial detachments (PEDs) and retinal pigment epithelium (RPE) tears. Photodynamic therapy (PDT) is a treatment for the bullous variant of CSC. RPE tear is a possible postoperative complication of PDT for eyes with PEDs. To our knowledge, no cases of giant RPE tears following PDT for the bullous variant of CSC have been reported previously. This case report presents the first instance of a giant RPE tear after half-time PDT for the bullous variant of CSC, accompanied by a series of images depicting the tear development.

PATIENT CONCERNS

A 63-year-old male patient presented with rapidly deteriorating vision in his left eye over a 3-month period. He also reported a previous episode of vision loss in his right eye 2 years prior. Best-corrected visual acuity (BCVA) in the left eye was 0.2.

DIAGNOSIS

The right eye was diagnosed with chronic non-bullous CSC, while the left eye was diagnosed with the bullous variant of CSC with a large PED.

INTERVENTIONS

Half-time PDT was administered to the left eye.

OUTCOMES

One month after half-time PDT, a giant RPE tear exceeding 3 clock-hours in size was confirmed in the lower temporal quadrant of the left eye. Three months after the initial half-time PDT, a second half-time PDT was performed owing to recurrent retinal detachment. Two months after the second half-time PDT, the retinal detachment resolved, and BCVA improved to 0.4, 6 months after the second half-time PDT.

LESSONS

In cases where the bullous variant of CSC is complicated by extensive PED, clinicians should consider the potential development of a giant RPE tear as a treatment complication.

Bone morphogenetic protein 6 (BMP6) antagonises experimental proliferative vitreoretinopathy established by TGF-β2 stimulation in retinal pigment epithelial cells through modulation of the p38 and JNK MAPK pathways

The formation of the epiretinal fibrotic membrane by retinal pigment epithelial (RPE) cells is a primary pathological change for proliferative vitreoretinopathy (PVR). Bone morphogenetic protein 6 (BMP6) is an antifibrogenic factor in various cells. To date, it is still unknown whether BMP6 can interfere with the fibrogenesis of RPE cells during the progression of PVR. This work aimed to address the relationship between BMP6 and transforming growth factor-β2 (TGF-β2)-elicited fibrogenesis of RPE cells, an experimental model for studying PVR in vitro. The BMP6 level was down-regulated, while the TGF-β2 level was up-regulated in the vitreous humor of PVR patients. The BMP6 level was down-regulated in human RPE cells challenged with TGF-β2. The treatment of RPE cells with TGF-β2 resulted in significant increases in proliferation, migration, epithelial-to-mesenchymal transition (EMT), and extracellular matrix (ECM) remodelling. These effects were found to be inhibited by the overexpression of BMP6 or exacerbated by the knockdown of BMP6. BMP6 overexpression reduced the phosphorylation of p38 and JNK in TGF-β2-stimulated RPE cells, while BMP6 knockdown showed the opposite effects. The inhibition of p38 or JNK partially reversed the BMP6-silencing-induced promoting effects on TGF-β2-elicited fibrogenesis in RPE cells. Taken together, BMP6 demonstrates the ability to counteract the proliferation, migration, EMT, and ECM remodelling of RPE cells induced by TGF-β2. This is achieved through the regulation of the p38 and JNK MAPK pathways. These findings imply a potential connection between BMP6 and PVR, and highlight the potential application of BMP6 in therapeutic interventions for PVR.

ITF2357 regulates NF-κB signaling pathway to protect barrier integrity in retinal pigment epithelial cells

The robust integrity of the retinal pigment epithelium (RPE), which contributes to the outer brain retina barrier (oBRB), is compromised in several retinal degenerative and vascular disorders, including diabetic macular edema (DME). This study evaluates the role of a new generation of histone deacetylase inhibitor (HDACi), ITF2357, in regulating outer blood-retinal barrier function and investigates the underlying mechanism of action in inhibiting TNFα-induced damage to RPE integrity. Using the immortalized RPE cell line (ARPE-19), ITF2357 was found to be non-toxic between 50 nM and 5 μM concentrations. When applied as a pre-treatment in conjunction with an inflammatory cytokine, TNFα, the HDACi was safe and effective in preventing epithelial permeability by fortifying tight junction (ZO-1, -2, -3, occludin, claudin-1, -2, -3, -5, -19) and adherens junction (E-cadherin, Nectin-1) protein expression post-TNFα stress. Mechanistically, ITF2357 depicted a late action at 24 h via attenuating IKK, IκBα, and p65 phosphorylation and ameliorated the expression of IL-1β, IL-6, and MCP-1. Also, ITF2357 delayed IκBα synthesis and turnover. The use of Bay 11-7082 and MG132 further uncovered a possible role for ITF2357 in non-canonical NF-κB activation. Overall, this study revealed the protection effects of ITF2357 by regulating the turnover of tight and adherens junction proteins and modulating NF-κB signaling pathway in the presence of an inflammatory stressor, making it a potential therapeutic application for retinal vascular diseases such as DME with compromised outer blood-retinal barrier.

Activation of aryl hydrocarbon receptor by azatyrosine-phenylbutyric hydroxamide inhibits progression of diabetic retinopathy mice

Diabetic retinopathy (DR) is a severe consequence of long-term diabetes mellitus and may lead to vision loss. Retinal pigment epithelial (RPE) cells are a diverse group of retinal cells with varied metabolic and functional roles. In hypoxic conditions, RPE cells have been shown to produce angiogenic factors, such as vascular endothelial growth factor (VEGF), which is regulated by hypoxia-inducible factor 1-alpha (HIF1A). VEGF plays a crucial role in angiogenesis in DR. In the present study, we investigated whether azatyrosine-phenylbutyric hydroxamide (AZP) has therapeutic effect on DR therapy. In this study, we treated high glucose-activated human retinal pigment epithelial cells (ARPE-19) with and without AZP. The effector proteins were evaluated using western blotting. In the in vivo study, AZP was administered to the db/db mice as a DR animal model. Moreover, invasive imaging techniques such as optical coherence tomography (OCT), fundus photography, and fundus fluorescein angiography (FFA) were performed on the mice to assess DR progression. We found that treatment of AZP for 12 weeks reversed increasing DR retinal alterations in db/db mice, decreasing vascular density, retinal blood perfusion, retinal thickness, decreasing DR lesion, lipofuscin accumulation, HIF1A, VEGF, and inflammation factor expression. In addition, AZP treatment could activate the aryl hydrocarbon receptor AHR and reverse the high-glucose-induced HIF1A and VEGF in ARPE-19 cells and db/db mice. In conclusion, AZP activated AHR while inhibiting HIF1A and VEGF. This study indicates that AZP may be a promising therapeutic agent for treating DR.

EFFECT OF RANIBIZUMAB AND AFLIBERCEPT ON RETINAL PIGMENT EPITHELIAL DETACHEMENT, SUBRETINAL AND INTRARETINAL FLUID IN AGE-RELATED MACULAR DEGENERATION

PURPOSE

The aim of the study was to compare the effect of three initial doses of the anti-VEGF ranibizumab and aflibercept medication on serous pigment epithelial detachment (PED), subretinal fluid (SRF) and intraretinal fluid (IRF) in the macula of treatment naive neovascular AMD (nvAMD) patients.

MATERIAL AND METHODS

The cohort consists of 148 patients, of which 74 patients were treated with ranibizumab (51 females and 23 males) and 74 with aflibercept (46 females and 28 males). The data was recorded prospectively from the moment of diagnosis and start of treatment for a period of 3 months. At the moment of diagnosis and 3 months later, an OCT examination (Spectralis OCT, Heidelberg Engineering, Heidelberg, Germany) was performed. The OCT examination included a macular scan with 25 scans. Using the OCT instrument software, we measured the maximum anterior-posterior elevation of serous PED, the highest thickness of SRF and the largest diameter of the intraretinal cystic space. The statistical significance of differences between groups was evaluated using the t-test for continuous data and the Fisher exact test for categorical data. Changes in values of continuous variables over time were evaluated using the Wilcoxon paired test. Paired comparisons of binary parameters were determined by the McNemar test.

RESULTS

Full regression of PED, SRF and IRF occurred in 3 (4.1%), 25 (39%) and 20 (51%) patients treated with ranibizumab, and in 5 (7.9%, p = 0.470), 28 (47%, p = 0.470) and 25 (57%, p = 0.827) patients treated with aflibercept, respectively. The average regression of PED, SRF and IRF was -60.4 μm (median -37.5 μm), -84.3 μm (median -85 μm) and -109.3 μm (median -81 μm) in patients treated with ranibizumab, and -46.3 μm (median -30 μm, p = 0.389), -127.7 μm (median -104 μm, p = 0.096) and -204.4 μm (median -163 μm, p = 0.005) in patients treated with aflibercept, respectively. We did not show a statistically significant difference in the regression rates of PED, SRF and IRF between the ranibizumab and aflibercept groups. (in patients with IRF after adjustment of the higher baseline IRF volumes in patients treated with aflibercept, p = 0.891).

CONCLUSION

We are convinced that ranibizumab and aflibercept have the same effect on serous PED, SRF and IRF in the macula in patients with treatment naive nvAMD during the initial loading phase.

Potential applications of bacteriorhodopsin mutants

Bacteriorhodopsin (BR), a model system in biotechnology, is a G-protein dependent trans membrane protein which serves as a light driven proton pump in the cell membrane of Halobacterium salinarum. Due to the linkage of retinal to the protein, it seems colored and has numbers of versatile properties. As in vitro culture of the Halobacteria is very difficult, and isolation is time consuming and usually inefficient, production of genetically modified constructs of the protein is essential. There are three important characteristics based on protein catalytic cycle and molecular functions of photo-electric, photochromic and proton transporting, which makes this protein as a strategic molecule with potential applications in biotechnology. Such applications include protein films, used in artificial retinal implants, light modulators, three-dimensional optical memories, color photochromic sensors, photochromic and electrochromic papers and ink, biological camouflage and photo detectors for biodefense and non-defense purposes.