RESUMO
Retinal necrosis is a severe condition that threatens visual function. It is caused by viruses that are known to cause acute retinal necrosis (ARN) and progressive outer retinal necrosis (PORN), which are called necrotizing herpetic retinopathies (NHR). ARN causes severe intraocular inflammation, including anterior chamber intravitreal cells, keratic precipitate, vitreous opacity, and retinal vasculitis, whereas intraocular inflammation in PORN is considered mild or virtually absent. In addition, PORN is a disease that manifests in immunosuppressive patients, such as those with acquired immunodeficiency syndrome. Here, we present a case of unilateral retinal necrosis after chemotherapy, allogeneic peripheral blood stem cell transplantation, and cord blood transplantation for acute myelogenous leukemia (AML) in a 31-year-old male patient. AML treatment resulted in metabolic remission, and oral steroids and tacrolimus were continued. After two days, the patient visited an ophthalmologist because he noticed a sudden onset of floaters and visual field disturbance in the left eye. The peripheral retina was already necrotic in all layers, causing total retinal detachment. Intraocular inflammation, retinal opacity, or hemorrhagic spots in the fundus were not observed. His previous CD4 count was 43 cells/µL. A polymerase chain reaction test of the anterior chamber fluid revealed varicella-zoster virus (VZV), and vitrectomy was performed four days after disease onset. The excised vitreous demonstrated minimal opacity. The peripheral necrotic retina was excised, photocoagulation was performed on the residual retinal limbus, and silicone oil was injected to maintain retinal attachment. The retinal restoration was maintained under silicone oil tamponade, and corrected visual acuity improved to 20/32 without strong inflammation after vitrectomy. However, two months postoperatively, he contracted coronavirus disease 2019 (COVID-19), his general condition rapidly deteriorated, and he died. This case of retinal necrosis without inflammatory results in an immunocompromised patient and VZV detection in an intraocular sample led us to suspect PORN. However, the patchy or spread retinal whitening characteristic of PORN was completely absent, whereas the well-defined, peripheral, full-layer retinal necrosis characteristic of ARN was present. Thus, this is a rare case of VZV-induced NHR with partial features of PORN and ARN that progressed very silently.
RESUMO
To investigate the effect of brain derived neurotrophic factor (BDNF) on the phagocytic activity in iris pigment epithelial (IPE) cells, purified porcine photoreceptor outer segments (POS) were applied to cultured IPE cells for three hours. To measure phagocytic activities, bound and total POS were differentially stained using a double immunofluorescence staining method. BDNF increased the binding of POS in IPE cells in a dose-dependent manner. Ingestion of POS, however, was not affected throughout the concentrations used in this study. To investigate the signal transduction pathways of BDNF, a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002, and MAPK/ERK kinase (MEK) inhibitor, PD98059, were used for this study. LY294002 had no effect on the binding and ingestion of POS in BDNF-treated IPE cells. On the other hand, PD98059 completely inhibited the increase of POS binding in BDNF-treated cells and also decreased the ingestion of POS. These results indicate that increased POS binding activity by BDNF and the decreased ingestion of POS were mediated through the MAPK pathway.