Ocular cytomegalovirus latency exacerbates the development of choroidal neovascularization.

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive disease which represents a leading cause of irreversible visual impairment and blindness in older individuals. Human cytomegalovirus (HCMV), which infects 50-80% of humans, is usually acquired during early life and persists in a latent state for the life of the individual. In view of its previously described pro-angiogenic properties, we hypothesized that cytomegalovirus might be a novel risk factor for progression to an advanced form, neovascular AMD, which is characterized by choroidal neovascularization (CNV). The purpose of this study was to investigate if latent ocular murine cytomegalovirus (MCMV) infection exacerbated the development of CNV in vascular endothelial growth factor (VEGF)-overexpressing VEGF-Ahyper mice. Here we show that neonatal infection with MCMV resulted in dissemination of virus to various organs throughout the body including the eye, where it localized principally to the choroid in both VEGF-overexpressingVEGF-Ahyper and wild-type(WT) 129 mice. By 6 months post-infection, no replicating virus was detected in eyes and extraocular tissues, although virus DNA was still present in all eyes and extraocular tissues of both VEGF-Ahyper and WT mice. Expression of MCMV immediate early (IE) 1 mRNA was detected only in latently infected eyes of VEGF-Ahyper mice, but not in eyes of WT mice. Significantly increased CNV was observed in eyes of MCMV-infected VEGF-Ahyper mice compared to eyes of uninfected VEGF-Ahyper mice, while no CNV lesions were observed in eyes of either infected or uninfected WT mice. Protein levels of several inflammatory/angiogenic factors, particularly VEGF and IL-6, were significantly higher in eyes of MCMV-infected VEGF-Ahyper mice, compared to uninfected controls. Initial studies of ocular tissue from human cadavers revealed that HCMV DNA was present in four choroid/retinal pigment epithelium samples from 24 cadavers. Taken together, our data suggest that ocular HCMV latency could be a significant risk factor for the development of AMD. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Parthanatos-associated proteins are stimulated intraocularly during development of experimental murine cytomegalovirus retinitis in mice with retrovirus-induced immunosuppression.

The mechanisms that contribute to retinal tissue destruction during the onset and progression of AIDS-related human cytomegalovirus (HCMV) retinitis remain unclear. Evidence for the stimulation of multiple cell death pathways including apoptosis, necroptosis, and pyroptosis during the pathogenesis of experimental murine cytomegalovirus (MCMV) retinitis in mice with retrovirus-induced immunosuppression (MAIDS) has been reported. Parthanatos is a caspase-independent cell death pathway mediated by rapid overactivation of poly (ADP-ribose) polymerase-1 (PARP-1) and distinct from other cell death pathways. Using the MAIDS model of MCMV retinitis, studies were performed to test the hypothesis that intraocular MCMV infection of mice with MAIDS stimulates parthanatos-associated messenger RNAs (mRNAs) and proteins within the eye during the development of retinal necrosis that takes place by 10 days after MCMV infection. MCMV-infected eyes of MAIDS mice exhibited significant stimulation of PARP-1 mRNA and proteins at 3 days after infection but declined thereafter at 6 and 10 days after infection. Additional studies showed the intraocular stimulation of mRNAs or proteins before MCMV retinitis development for two additional participants in parthanatos, polymer of ADP-ribose and poly (ADP-ribose) glycohydrolase. These results provide new evidence for a role for parthanatos during MAIDS-related MCMV retinitis that may also extend to AIDS-related HCMV retinitis.

Targeting noncoding RNAs in disease.

Many RNA species have been identified as important players in the development of chronic diseases, including cancer. Over the past decade, numerous studies have highlighted how regulatory RNAs such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play crucial roles in the development of a disease state. It is clear that the aberrant expression of miRNAs promotes tumor initiation and progression, is linked with cardiac dysfunction, allows for the improper physiological response in maintaining glucose and insulin levels, and can prevent the appropriate integration of neuronal networks, resulting in neurodegenerative disorders. Because of this, there has been a major effort to therapeutically target these noncoding RNAs. In just the past 5 years, over 100 antisense oligonucleotide-based therapies have been tested in phase I clinical trials, a quarter of which have reached phase II/III. Most notable are fomivirsen and mipomersen, which have received FDA approval to treat cytomegalovirus retinitis and high blood cholesterol, respectively. The continued improvement of innovative RNA modifications and delivery entities, such as nanoparticles, will aid in the development of future RNA-based therapeutics for a broader range of chronic diseases. Here we summarize the latest promises and challenges of targeting noncoding RNAs in disease.

Cytokine analysis of aqueous humor in HIV patients with cytomegalovirus retinitis.

PURPOSE: Cytomegalovirus retinitis (CMVR) is the most common opportunistic ocular infection in patients with AIDS. Comprehensive analysis of aqueous humor for immunologic factors has yet to be performed in patients with CMVR. This study aims to perform comprehensive immune factor analysis of aqueous humor in CMVR patients to determine the presence of any characteristic immunological profile in the aqueous humor. METHODS: Comparative prospective analysis of aqueous humor was performed across three groups: (1) AIDS patients with CMVR (CMVR group) (n=20), (2) HIV-positive patients without CMVR (HIV group) (n=6) and (3) patients undergoing cataract surgery with no underlying ocular infection or inflammation (control group) (n=11). At least 100µl of aqueous humor was drawn from all subjects and fractionated prior to analysis for 41 cytokines, chemokines and growth factors with the FlexMAP 3D (Luminex®) platform using the Milliplex Human Cytokine® kit. RESULTS: Three distinct immunologic signatures were observed in the aqueous humor of the three groups. Statistically significant differences (p<0.05) were observed across the three groups with the HIV group having lower levels and CMVR group having raised levels for the following factors: IP-10, fractalkine, PDGF-AA, G-CSF, Flt-3L and MCP-1. CONCLUSION: Aqueous humor though clinically quiescent in CMVR revealed a unique immunologic signature consistent with a combined Th-1 and monocyte-macrophage mediated response. Subsequent longitudinal analysis of aqueous cytokine levels of CMVR through the course of treatment would allow better understanding of the immunopathogenetic mechanisms of CMVR. This may also be used to better prognosticate the disease, predict complications and allow better assessment of treatment response and individualization of treatment in the future.

The immediate early 2 protein of human cytomegalovirus (HCMV) mediates the apoptotic control in HCMV retinitis through up-regulation of the cellular FLICE-inhibitory protein expression.

Human CMV (HCMV) is a widespread human pathogen that causes blindness by inducing retinitis in AIDS patients. Previously, we showed that viral immediate early 2 (IE2) protein may allow HCMV to evade the immune control by killing the Fas receptor-positive T lymphocytes attracted to the infected retina with increased secretion of Fas ligand (FasL). In this study, we further demonstrate that the secreted FasL also kills uninfected Fas-rich bystander retinal cells and that IE2 simultaneously protects the infected cells from undergoing apoptotic death, in part, by activating the expression of cellular FLIP (c-FLIP), an antiapoptotic molecule that blocks the direct downstream executer caspase 8 of the FasL/Fas pathway. c-FLIP induction requires the N-terminal 98 residues of IE2 and the c-FLIP promoter region spanning nucleotides -978 to -696. In vivo association of IE2 to this region, IE2-specific c-FLIP activation, and decrease of FasL-up-regulated activities of caspases 8 and 3 were all demonstrated in HCMV-infected human retinal cells. Moreover, c-FLIP up-regulation by IE2 appeared to involve PI3K and might also render cells resistant to TRAIL-mediated death. Finally, enhanced c-FLIP signals were immunohistochemically detected in IE-positive cells in the HCMV-infected lesions of the human retina. Taken together, these data demonstrate specific activation of c-FLIP by HCMV IE2 and indicate a novel role for c-FLIP in the pathogenesis of HCMV retinitis.

Human cytomegalovirus retinitis: pathogenicity, immune evasion and persistence.

Human cytomegalovirus (HCMV) retinitis frequently occurs in severely naturally and iatrogenically immunocompromised patients. It has been shown that the immune-privileged retinal pigment epithelium (RPE) is a major site of persistent HCMV. Recently, evidence has accumulated to show that HCMV immediate early (IE) gene expression in RPE cells deviates ocular antiviral inflammation via FasL. Moreover, unlike in other cell types, the HCMV major IE1/2 enhancer promoter (MIEP) resists activation by proinflammatory stimuli mediated by the transcription factor NF-kappaB. However, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) found at elevated levels in transplant recipients and AIDS patients with retinitis sensitize RPE cells and other retinal cells to FasL-mediated apoptosis, thus contributing to retina destruction and necrosis rather than inflammation. These specific features of RPE cells in conjunction with deregulated immune responses of immunocompromised patients seem to contribute to virus persistence and pathogenesis within the immune-privileged ocular retina.

Up-regulation of Fas ligand expression by human cytomegalovirus immediate-early gene product 2: a novel mechanism in cytomegalovirus-induced apoptosis in human retina.

Human CMV (HCMV) is an important pathogen that causes widespread diseases in immunocompromised individuals. Among the opportunistic HCMV infections, HCMV retinitis is most common in transplant recipients and AIDS patients. It often leads to blindness if left untreated. The question as to how HCMV infection causes retinal pathogenesis remains unresolved. Here, we report that viral immediate-early gene product 2 (IE2), but not IE1, up-regulates the Fas ligand (FasL) expression in HCMV-infected human retinal pigment epithelium cells. Increased secretion of FasL from virally infected cells into cultured medium was observed upon HCMV infection. The capability of such cell-free medium to induce apoptosis of Fas (CD95)-expressing Jurkat cells further implies that Fas-FasL interaction might mediate cell death in the lesion of HCMV retinitis. To support this idea, we observed augmented soluble FasL levels in vitreous from AIDS patients with HCMV retinitis as compared with that from AIDS patients without HCMV infection. In addition, by in situ hybridization and immunohistochemistry, we detected enhanced signals of FasL, the existence of viral IE Ags and apoptotic cells at the same sites in the lesion of HCMV-infected retina. These results strongly suggest that IE2 induction of FasL expression in human retina might be an important event that takes place in the early stage of infection and finally leads to visual loss in individuals affiliated with HCMV retinitis.

Cytomegalovirus infection decreases expression of thrombospondin-1 and -2 in cultured human retinal glial cells: effects of antiviral agents.

In fibroblasts, infection with human cytomegalovirus (HCMV) inhibits expression of the extracellular matrix proteins thrombospondin-1 and -2 (TSP-1 and TSP-2). These effects may depend on expression of HCMV immediate-early (IE) genes, which are activated by cellular transcription factor NF-kappaB. The influence of HCMV infection on TSP-1 and TSP-2 expression and the ability of different antiviral drugs to prevent these cellular changes in permissive cultures of human retinal glial cells were observed. Ganciclovir inhibited only HCMV late antigen (LA) expression, whereas antisense oligonucleotide ISIS 2922 and peptide SN50, inhibitors of HCMV IE expression and NF-kappaB activity, respectively, inhibited both IE and LA expression. ISIS 2922 and SN50, but not ganciclovir, prevented down-modulation of TSP-1 and TSP-2. The results showed that HCMV-induced down-modulation of TSP-1 and TSP-2 in retinal glial cells is prevented by inhibition of HCMV IE expression. These findings may be relevant to pathogenesis and treatment of HCMV retinitis.

Triple viral retinitis diagnosed by polymerase chain reaction of the vitreous biopsy in a patient with Richter syndrome.

PURPOSE: To report the evaluation and identification of herpes viruses associated with retinitis in a patient with Richter syndrome. METHODS: Diagnostic vitrectomy was performed on a patient with systemic leukemia and retinitis. The vitreous sample was evaluated by cytology, analysis of cytokines by ELISA, and detection of virus by polymerase chain reaction. RESULTS: The vitreous biopsy specimen showed no malignant cells but predominant CD8+ lymphocyte infiltration with elevated interferon gamma and interleukin-6. DNA amplification and Southern blot analysis demonstrated DNA of herpes simplex, varicella-zoster, and cytomegalovirus. CONCLUSION: Retinitis associated with multiple viruses in the vitreous biopsy may mimic leukemic infiltration in the eye.

An immunohistochemical study of TNF-alpha in optic nerves from AIDS patients.

PURPOSE: Both in vitro and in vivo studies have implicated a role for tumor necrosis factor (TNF-alpha) in the pathology of demyelinating diseases. The purpose of this study was to address the hypothesis that TNF-alpha is a mediator of AIDS-related optic nerve injury and to determine the cell types involved in the proliferation of TNF-alpha in the AIDS optic nerve. METHODS: Ten optic nerves from seven patients with AIDS, and three from persons who were HIV negative were stained, using the indirect immunoperoxidase method. Six of the ten AIDS optic nerves were positive for cytomegalovirus (CMV), but the remainder did not have abnormal fundus findings. RESULTS: In all the optic nerves from AIDS patients with or without CMV retinitis, the vast majority of astrocytes stained strongly for TNF-alpha. Microglial cells (MPS-derived macrophages) varied from not staining to staining strongly positive for TNF-alpha. However, oligodendrocytes were not labeled positively for TNF-alpha. Some endothelial cells also stained for TNF-alpha. Examination of normal optic nerves and controls did not reveal any cell type that stained positively for TNF-alpha. CONCLUSIONS: The present study supports the contention that TNF-alpha is a major mediator of AIDS-associated optic neuropathy. HIV infection induces the production of TNF-alpha in macrophages and astrocytes, which probably causes demyelination and other neuronal damage.