The Complement System as a Therapeutic Target in Retinal Disease.

The complement cascade is a vital system in the human body's defense against pathogens. During the natural aging process, it has been observed that this system is imperative for ensuring the integrity and homeostasis of the retina. While this system is critical for proper host defense and retinal integrity, it has also been found that dysregulation of this system may lead to certain retinal pathologies, including geographic atrophy and diabetic retinopathy. Targeting components of the complement system for retinal diseases has been an area of interest, and in vivo, ex vivo, and clinical trials have been conducted in this area. Following clinical trials, medications targeting the complement system for retinal disease have also become available. In this manuscript, we discuss the pathophysiology of complement dysfunction in the retina and specific pathologies. We then describe the results of cellular, animal, and clinical studies targeting the complement system for retinal diseases. We then provide an overview of complement inhibitors that have been approved by the Food and Drug Administration (FDA) for geographic atrophy. The complement system in retinal diseases continues to serve as an emerging therapeutic target, and further research in this field will provide additional insights into the mechanisms and considerations for treatment of retinal pathologies.

Retinal transplant immunology and advancements.

Several gaps and barriers remain for transplanting stem cells into the eye to treat ocular disease, especially diseases of the retina. While the eye has historically been considered immune privileged, recent thinking has identified the immune system as both a barrier and an opportunity for eye stem cell transplantation. Recent approaches leveraging scaffolds or cloaking have been considered in other tissues beyond immune suppression. This perspective paper outlines approaches for transplantation and proposes opportunities to overcome barriers of the immune system in stem cell transplantation in the eye.

Retraction Note: Autoantibodies detection in patients affected by autoimmune retinopathies.

The article "Autoantibodies detection in patients affected by autoimmune retinopathies", by M.R. Ceccarini, M.C. Medori, K. Dhuli, S. Tezzele, G. Bonetti, C. Micheletti, P.E. Maltese, S. Cecchin, K. Donato, L. Colombo, L. Rossetti, G. Staurenghi, A.P. Salvetti, M. Oldani, L. Ziccardi, D. Marangoni, G. Iarossi, B. Falsini, G. Placidi, F. D'Esposito, F. Viola, M. Nassisi, G. Leone, L. Cimino, L. De Simone, V. Mastrofilippo, T. Beccari, M. Bertelli, published in Eur Rev Med Pharmacol Sci 2023; 27 (6 Suppl): 57-63-DOI: 10.26355/eurrev_202312_34690-PMID: 38112948 has been retracted by the Editor in Chief for the following reasons. Following some concerns raised on PubPeer, the Editor in Chief has started an investigation to assess the validity of the results. The outcome of the investigation revealed that the manuscript presented major flaws in the following: -       Issues with ethical approval -       Undeclared conflict of interest In light of concerns regarding the potential manipulation of Supplementary Figure 2, the journal's inquiry has been unable to conclusively determine whether the alterations noted on PubPeer constitute figure manipulation. The investigation yielded divergent evaluations. However, given the aforementioned concerns, the Editor in Chief doubts the integrity of the findings presented and thus, has opted to retract the article. The authors disagree with this retraction. This article has been retracted. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/34690.

Autoimmune retinopathy in a patient with smoldering multiple myeloma: a case report.

PURPOSE: Multiple myeloma (MM) is a plasma cell dyscrasia leading to proliferation of monoclonal plasma cells. Ocular involvement in multiple myeloma is uncommon but can occur. The ocular manifestations of MM may include the cornea, uvea, and retinal vasculature. We present a rare case of autoimmune retinopathy associated with smoldering MM. CASE: A 76-year-old female with no significant past medical or ocular history presented with four months of worsening vision, difficulty with night driving, and loss of peripheral vision. Examination was notable for pallor of the optic nerves and vascular attenuation. Visual field testing demonstrated significant and progressive field loss in both eyes. An electroretinogram was extinguished under all conditions. Serum protein electrophoresis showed a significant elevation of IgG with an M-spike, and a subsequent bone marrow biopsy was performed showing 12.5% plasma cells, consistent with the diagnosis of MM. CAR antibody testing was positive for anti-enolase, anti-GAPDH, and anti-Rab6 antibodies, consistent with autoimmune retinopathy. DISCUSSION: Autoimmune retinopathy associated with MM is exceedingly rare. Management of this condition is challenging, as treatment of the underlying disease does not often lead to improvement in visual symptoms. Ultimately, visual prognosis is very poor, and both patients and clinicians should be aware of the guarded visual potential. CONCLUSION: The association of autoimmune retinopathy with multiple myeloma is rare. It is crucial for physicians to be aware of such manifestations to ensure timely and appropriate diagnosis and management for patients.

Risk Mitigation of Immunogenicity: A Key to Personalized Retinal Gene Therapy.

Gene therapy (GT) for ocular disorders has advanced the most among adeno-associated virus (AAV)-mediated therapies, with one product already approved in the market. The bank of retinal gene mutations carefully compiled over 30 years, the small retinal surface that does not require high clinical vector stocks, and the relatively immune-privileged environment of the eye explain such success. However, adverse effects due to AAV-delivery, though rare in the retina have led to the interruption of clinical trials. Risk mitigation, as the key to safe and efficient GT, has become the focus of 'bedside-back-to-bench' studies. Herein, we overview the inflammatory adverse events described in retinal GT trials and analyze which components of the retinal immunological environment might be the most involved in these immune responses, with a focus on the innate immune system composed of microglial surveillance. We consider the factors that can influence inflammation in the retina after GT such as viral sensors in the retinal tissue and CpG content in promoters or transgene sequences. Finally, we consider options to reduce the immunological risk, including dose, modified capsids or exclusion criteria for clinical trials. A better understanding and mitigation of immune risk factors inducing host immunity in AAV-mediated retinal GT is the key to achieving safe and efficient GT.

CD4+ T-Cell Plasticity in Non-Infectious Retinal Inflammatory Disease.

Non-infectious uveitis (NIU) is a potentially sight-threatening disease. Effector CD4+ T cells, especially interferon-γ-(IFNγ) producing Th1 cells and interleukin-17-(IL-17) producing Th17 cells, are the major immunopathogenic cells, as demonstrated by adoptive transfer of disease in a model of experimental autoimmune uveitis (EAU). CD4+FoxP3+CD25+ regulatory T cells (Tregs) were known to suppress function of effector CD4+ T cells and contribute to resolution of disease. It has been recently reported that some CD4+ T-cell subsets demonstrate shared phenotypes with another CD4+ T-cell subset, offering the potential for dual function. For example, Th17/Th1 (co-expressing IFNγ and IL-17) cells and Th17/Treg (co-expressing IL-17 and FoxP3) cells have been identified in NIU and EAU. In this review, we have investigated the evidence as to whether these 'plastic CD4+ T cells' are functionally active in uveitis. We conclude that Th17/Th1 cells are generated locally, are resistant to the immunosuppressive effects of steroids, and contribute to early development of EAU. Th17/Treg cells produce IL-17, not IL-10, and act similar to Th17 cells. These cells were considered pathogenic in uveitis. Future studies are needed to better clarify their function, and in the future, these cell subsets may in need to be taken into consideration for designing treatment strategies for disease.

Autoantibody profiles and clinical association in Thai patients with autoimmune retinopathy.

Autoimmune retinopathy (AIR) is a rare immune-mediated inflammation of the retina. The autoantibodies against retinal proteins and glycolytic enzymes were reported to be involved in the pathogenesis. This retrospective cohort study assessed the antiretinal autoantibody profiles and their association with clinical outcomes of AIR patients in Thailand. We included 44 patients, 75% were females, with the overall median age of onset of 48 (17-74, IQR 40-55.5) years. Common clinical presentations were nyctalopia (65.9%), blurred vision (52.3%), constricted visual field (43.2%), and nonrecordable electroretinography (65.9%). Underlying malignancy and autoimmune diseases were found in 2 and 12 female patients, respectively. We found 41 autoantibodies, with anti-α-enolase (65.9%) showing the highest prevalence, followed by anti-CAII (43.2%), anti-aldolase (40.9%), and anti-GAPDH (36.4%). Anti-aldolase was associated with male gender (P = 0.012, OR 7.11, 95% CI 1.54-32.91). Anti-CAII showed significant association with age of onset (P = 0.025, 95% CI - 17.28 to - 1.24), while anti-α-enolase (P = 0.002, OR 4.37, 95% CI 1.83-10.37) and anti-GAPDH (P = 0.001, OR 1.87, 95% CI 1.32-2.64) were significantly associated with nonrecordable electroretinography. Association between the antibody profiles and clinical outcomes may be used to direct and adjust the treatment plans and provide insights in the pathogenesis of AIR.

AIRE Gene Mutation Presenting at Age 2 Years With Autoimmune Retinopathy and Steroid-Responsive Acute Liver Failure: A Case Report and Literature Review.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autosomal recessive disorder caused by mutation in the autoimmune regulator (AIRE) gene. Patients usually are diagnosed at ages between 5 and 15 years when they show 3 or more manifestations, most typically mucocutaneous candidiasis, Addison's disease, and hypoparathyroidism. APECED-associated hepatitis (APAH) develops in only 10% to 40% of patients, with severity varying from subclinical chronic active hepatitis to potentially fatal acute liver failure (ALF). Ocular abnormalities are fairly common, most often keratopathy but sometimes retinopathy. Here we report a 2-year-old Japanese girl with an AIRE gene mutation who developed APAH with ALF, preceded by autoimmune retinopathy associated with anti-recoverin antibody before major symptoms suggested a diagnosis of APECED. Intravenous pulse methylprednisolone therapy followed by a corticosteroid combined with azathioprine treatment resolved ALF and achieved control of APAH. To our knowledge, our patient is the youngest reported to have ALF resulting from an AIRE gene mutation. Pulse methylprednisolone induction therapy followed by treatment with corticosteroid plus azathioprine may well be effective in other children with APAH and AIRE gene mutations.

Coronavirus-induced autoimmunity.

The pandemic of Coronavirus disease 2019 (COVID-19), caused by a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spotlighted the link between viral infection and autoimmunity. In this review, we focus on coronavirus-induced autoimmunity based on evidence from experimental animal models, SARS-CoV infection with in vitro studies of molecular mimicry and COVID-19 with several clinical reports of autoimmune manifestations of this disease. Further studies will be needed to better characterize the role of SARS-CoV-2 in the development of autoimmunity.

The phase changes of M1/M2 phenotype of microglia/macrophage following oxygen-induced retinopathy in mice.

OBJECTIVE: Microglia/macrophage activation is previously reported to be involved in various ocular diseases. However, the separate role of M1/M2 phenotype microglia/macrophage in the pathological process of oxygen-induced retinopathy (OIR) remains unknown. In this research, we explored the role and regulatory mechanism of M1/M2 microglia/macrophage in OIR in C57BL/6J mice. Furthermore, we demonstrated the time phase of M1/M2 shifting of microglia/macrophage during the natural process of OIR, which is very essential for further investigations. MATERIALS AND METHODS: C57BL/6j pups were exposed to hyperoxia environment from postnatal 7(P7) to P12 then returned to normoxia. The mice were then euthanized, and the eyes were harvested at a series of time points for further investigation. The M1/M2 phenotype microglia/macrophage activity was presented by immunofluorescent staining and real-time quantitative polymerase chain reaction (qPCR). The NF-κb-STAT3 signaling and IL-4-STAT6-PPAR-γ signaling pathway activity was examined by western blot analysis. RESULTS: The microglia/macrophage were activated when the OIR model was set up after P12. The M1 microglia/macrophage activation was found in neovascularization (NV) tufts in both central and peripheral retina, which started from P12 when the mice were returned to normoxia environment and peaked at P17. During this period of time, the NF-κb-STAT3 signaling pathway was activated, resulting in the upregulated M1 phenotype microglia/macrophage polarization, along with the enhanced inflammatory cytokine expression including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1ß. Consequently, the NV tufts were observed from P12 and the volume continued to increase until P17. However, the M2 phenotype microglia/macrophage activity took over during the late phase of OIR started from P17. The IL-4-STAT6-PPAR-γ signaling activity was upregulated from P17 and peaked at P20, inducing M2 phenotype microglia polarization, which consequently led to the inhibition of inflammatory cytokines and spontaneous regression of NV tufts. CONCLUSIONS: Microglia/macrophage participate actively in the natural process of OIR in mice, and two phenotypes exert different functions. Treatment modulating microglia/macrophage polarize toward M2 phenotype might be a novel and promising method for ocular neovascular diseases such as retinopathy of prematurity (ROP), wet age-related macular degeneration (wAMD), and diabetic retinopathy (DR).

Optimal Efficacy and Safety of Humanized Anti-Scg3 Antibody to Alleviate Oxygen-Induced Retinopathy.

The retinopathy of prematurity (ROP), a neovascular retinal disorder presenting in premature infants, is the leading causes of blindness in children. Currently, there is no approved drug therapy for ROP in the U.S., highlighting the urgent unmet clinical need for a novel therapeutic to treat the disease. Secretogranin III (Scg3) was recently identified as a disease-selective angiogenic factor, and Scg3-neutralizing monoclonal antibodies were reported to alleviate pathological retinal neovascularization in mouse models. In this study, we characterized the efficacy and safety of a full-length humanized anti-Scg3 antibody (hAb) to ameliorate retinal pathology in oxygen-induced retinopathy (OIR) mice, a surrogate model of ROP, by implementing histological and functional analyses. Our results demonstrate that the anti-Scg3 hAb outperforms the vascular endothelial growth factor inhibitor aflibercept in terms of efficacy and safety to treat OIR mice. Our findings support the development of anti-Scg3 hAb for clinical application.

Dual-acting therapeutic proteins for intraocular use.

Intravitreally injected antibody-based medicines have revolutionised the treatment of retinal disease. Bispecific and dual-functional antibodies and therapeutic proteins have the potential to further increase the efficacy of intraocular medicines.

Complement-Mediated Microglial Phagocytosis and Pathological Changes in the Development and Degeneration of the Visual System.

The focus of this review is the role of complement-mediated phagocytosis in retinal and neurological diseases affecting the visual system. Complement activation products opsonize synaptic material on neurons for phagocytic removal, which is a normal physiological process during development, but a pathological process in several neurodegenerative diseases and conditions. We discuss the role of complement in the refinement and elimination of synapses in the retina and lateral geniculate nucleus, both during development and in disease states. How complement and aberrant phagocytosis promotes injury to the visual system is discussed primarily in the context of multiple sclerosis, where it has been extensively studied, although the role of complement in visual dysfunction in other diseases such as stroke and traumatic brain injury is also highlighted. Retinal diseases are also covered, with a focus on glaucoma and age-related macular degeneration. Finally, we discuss the potential of complement inhibitory strategies to treat diseases affecting the visual system.

The protective effect of quercetin on retinal inflammation in mice: the involvement of tumor necrosis factor/nuclear factor-κB signaling pathways.

Quercetin is a natural flavonoid that occurs in fruits and vegetables. Retinal inflammation is an important cause of vision loss. This study was aimed to analyze the effects of oral administration of quercetin on retinal inflammation. Transgenic mice, carrying nuclear factor-κB (NF-κB)-driven luciferase genes, were injected with 1 mg per kg body weight of lipopolysaccharide (LPS). Various amounts (1, 10, and 100 mg per kg body weight) of quercetin were orally given to mice. LPS-induced retinal inflammation was evaluated by bioluminescence imaging and histological examination 4 hours later. RNA-Seq analysis of gene expression profiles was performed to explain the mechanisms of quercetin on eye inflammation. Our data showed that LPS enhanced luminescent signals on ocular tissues, while LPS-induced luminescence intensities were significantly suppressed by quercetin by 73.61 ± 21.74%. LPS significantly increased the thickness of retinal tissues by 1.52 ± 0.37 fold, in comparison with the mock, while quercetin reduced the LPS-induced retinal thickness and decreased the accumulation of infiltrating granulocytes. Biological pathway analysis showed that tumor necrosis factor (TNF), cytokine, and NF-κB signaling pathways were involved in the anti-inflammatory mechanisms of quercetin. Immunohistochemical staining further showed that quercetin reduced the activation of NF-κB, the expression of interleukin-1ß and TNF-α, and the infiltration of granulocytes in retinal tissues. In conclusion, this is the first study reporting the effects and mechanisms of orally administered quercetin against LPS-induced retinal inflammation in mice. Due to its safety, our study suggested that supplementation of quercetin has beneficial effects on the eyes.

Identification and characterization of novel TRPM1 autoantibodies from serum of patients with melanoma-associated retinopathy.

Melanoma-associated retinopathy (MAR) is a rare paraneoplastic retinal disorder usually occurring in the context of metastatic melanoma. Patients present with night blindness, photopsias and a constriction of the visual field. MAR is an auto-immune disorder characterized by the production of autoantibodies targeting retinal proteins, especially autoantibodies reacting to the cation channel TRPM1 produced in melanocytes and ON-bipolar cells. TRPM1 has at least three different isoforms which vary in the N-terminal region of the protein. In this study, we report the case of three new MAR patients presenting different anti-TRPM1 autoantibodies reacting to the three isoforms of TRPM1 with variable binding affinity. Two sera recognized all isoforms of TRPM1, while one recognized only the two longest isoforms upon immunolocalization studies on overexpressing cells. Similarly, the former two sera reacted with all TRPM1 isoforms on western blot, but an immunoprecipitation enrichment step was necessary to detect all isoforms with the latter serum. In contrast, all sera labelled ON-bipolar cells on Tprm1+/+ but not on Trpm1-/- mouse retina as shown by co-immunolocalization. This confirms that the MAR sera specifically detect TRPM1. Most likely, the anti-TRPM1 autoantibodies of different patients vary in affinity and concentration. In addition, the binding of autoantibodies to TRPM1 may be conformation-dependent, with epitopes being inaccessible in some constructs (truncated polypeptides versus full-length TRPM1) or applications (western blotting versus immunohistochemistry). Therefore, we propose that a combination of different methods should be used to test for the presence of anti-TRPM1 autoantibodies in the sera of MAR patients.

Autoimmune retinopathy associated with monoclonal gammopathy of undetermined significance: a case report.

BACKGROUND: Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell dyscrasia and precursor to multiple myeloma. It has known ocular manifestations, but has not previously been shown to have an association with autoimmune retinopathy. CASE PRESENTATION: A 57 year-old female presented with 1 year of progressive, bilateral, peripheral vision loss, photopsias, and nyctalopia. Her fundus examination and extensive ancillary testing were concerning for hereditary versus autoimmune retinopathy. The patient was found to have anti-retinal antibodies against carbonic anhydrase II and enolase proteins with a negative genetic retinal dystrophy panel. Malignancy work-up was negative, but the patient was diagnosed with MGUS, a premalignant condition. The patient was treated with immunosuppressive therapies, with rituximab demonstrating the most robust therapeutic response with respect to patient symptoms and ophthalmic testing. CONCLUSIONS: MGUS should be considered as a potential etiology of autoimmune retinopathy in patients without other autoimmune or malignant disease processes. Immunosuppressive therapy may be helpful in limiting disease progression, with rituximab showing efficacy in retinopathy refractory to other agents.

Innate immune response in retinal homeostasis and inflammatory disorders.

Innate immune cells such as neutrophils, monocyte-macrophages and microglial cells are pivotal for the health and disease of the retina. For the maintenance of retinal homeostasis, these cells and immunosuppressive molecules in the eye actively regulate the induction and the expression of inflammation in order to prevent excessive activation and subsequent tissue damage. In the disease context, these regulatory mechanisms are modulated genetically and/or by environmental stimuli such as damage-associated molecular patterns (DAMPs), and a chronic innate immune response regulates or contributes to the formation of diverse retinal disorders such as uveitis, retinitis pigmentosa, retinal vascular diseases and retinal fibrosis. Here we summarize the recent knowledge regarding the innate immune response in both ocular immune regulation and inflammatory retinal diseases, and we describe the potential of the innate immune response as a biomarker and therapeutic target.