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Complement C5 is not critical for the formation of sub-RPE deposits in Efemp1 mutant mice.

ABSTRACT: The complement system plays a role in the formation of sub-retinal pigment epithelial (RPE) deposits in early stages of age-related macular degeneration (AMD). But the specific mechanisms that connect complement activation and deposit formation in AMD patients are unknown, which limits the development of efficient therapies to reduce or stop disease progression. We have previously demonstrated that C3 blockage prevents the formation of sub-RPE deposits in a mouse model of EFEMP1-associated macular degeneration. In this study, we have used double mutant Efemp1^R345W/R345W:C5^-/- mice to investigate the role of C5 in the formation of sub-RPE deposits in vivo and in vitro. The data revealed that the genetic ablation of C5 does not eliminate the formation of sub-RPE deposits. Contrarily, the absence of C5 in RPE cultures promotes complement dysregulation that results in increased activation of C3, which likely contributes to deposit formation even in the absence of EFEMP1-R345W mutant protein. The results also suggest that genetic ablation of C5 alters the extracellular matrix turnover through an effect on matrix metalloproteinases in RPE cell cultures. These results confirm that C3 rather than C5 could be an effective therapeutic target to treat early AMD.

SUBMITTER: Garland DL

PROVIDER: S-EPMC8128922 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Complement factor B is critical for sub-RPE deposit formation in the Efemp1 R345W mutant mouse model with features of age-related macular degeneration

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2023-03-11 | PXD035772 | Pride

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Extensive Sub-RPE Complement Deposition in a Nonhuman Primate Model of Early Stage Diabetic Retinopathy

Project description:Purpose: This study aims to reveal retinal abnormities in a spontaneous diabetic nonhuman primate (NHP) model and explore the mechanism of featured injuries. Methods: Twenty-eight cynomolgus monkeys were identified to suffer from spontaneous Type 2 diabetes from a colony of more than eight hundred aged monkeys and twenty-six age-matched ones were used as controls. Their blood biochemistry profiles were determined and the retinal changes were examined by multimodal imaging, hematoxylin-eosin (H&E) staining and immunofluorescence. Retinal pigment epithelium (RPE) cells were isolated and determined by RNA-sequencing and computational analyses. Results: Diabetic monkeys were characterized by early vascular and neural damage in the retina and dyslipidemia. The typical acellular capillaries and pericyte ghost were found in the diabetic retina, which also exhibited reduced retinal nerve fiber layer (RNFL) thickness compared to the controls. Of note, distinct sub-RPE drusenoid lesions were extensively observed in these diabetic monkeys and complements deposition including C3 and C5b-9 were accumulated in these lesions. The RNA-seq data of RPE cells showed complement activation, AGE/RAGE activation and 18 inflammatory response at the setting of diabetes. Consistently, the plasma levels of C3 and C4 were also increased in the diabetic monkeys. Conclusions: The spontaneous Type 2 diabetic cynomolgus monkeys featured with early-stage retinopathy including not only typical vascular and neural damage, but also a distinct sub-RPE deposition. The complement activation and metabolic stress of RPE cells in response to hyperglycemia might contribute to the deposition, revealing an unrecognized role of RPE cells in the early-stage pathological process of diabetic retinopathy (DR).

2021-03-31 | GSE160617 | GEO

Complement factor B is critical for sub-RPE deposit accumulation in a model of Doyne honeycomb retinal dystrophy with features of age-related macular degeneration.

Project description:EFEMP1 R345W is a dominant mutation causing Doyne honeycomb retinal dystrophy/malattia leventinese (DHRD/ML), a rare blinding disease with clinical pathology similar to age-related macular degeneration (AMD). Aged Efemp1 R345W/R345W knock-in mice (Efemp1ki/ki) develop microscopic deposits on the basal side of retinal pigment epithelial cells (RPE), an early feature in DHRD/ML and AMD. Here, we assessed the role of alternative complement pathway component factor B (FB) in the formation of these deposits. RNA-seq analysis of the posterior eyecups revealed increased unfolded protein response, decreased mitochondrial function in the neural retina (by 3 months of age) and increased inflammatory pathways in both neural retina and posterior eyecups (at 17 months of age) of Efemp1ki/ki mice compared with wild-type littermate controls. Proteomics analysis of eye lysates confirmed similar dysregulated pathways as detected by RNA-seq. Complement activation was increased in aged Efemp1ki/ki eyes with an approximately 2-fold elevation of complement breakdown products iC3b and Ba (P < 0.05). Deletion of the Cfb gene in female Efemp1ki/ki mice partially normalized the above dysregulated biological pathway changes and oral dosing of a small molecule FB inhibitor from 10 to 12 months of age reduced sub-RPE deposits by 65% (P = 0.029). In contrast, male Efemp1ki/ki mice had fewer sub-RPE deposits than age-matched females, no elevation of ocular complement activation and no effect of FB inhibition on sub-RPE deposits. The effects of FB deletion or inhibition on Efemp1ki/ki mice supports systemic inhibition of the alternative complement pathway as a potential treatment of dry AMD and DHRD/ML.

| S-EPMC9840207 | biostudies-literature

Extensive Sub-RPE Complement Deposition in a Nonhuman Primate Model of Early-Stage Diabetic Retinopathy.

Project description:PurposeThis study aims to reveal retinal abnormities in a spontaneous diabetic nonhuman primate model and explore the mechanism of featured injuries.MethodsTwenty-eight cynomolgus monkeys were identified to suffer from spontaneous type 2 diabetes from a colony of more than eight-hundred aged monkeys, and twenty-six age-matched ones were chosen as controls. Their blood biochemistry profiles were determined and retinal changes were examined by multimodal imaging, hematoxylin and eosin staining, and immunofluorescence. Retinal pigment epithelium (RPE) cells were further investigated by RNA sequencing and computational analyses.ResultsThese diabetic monkeys were characterized by early retinal vascular and neural damage and dyslipidemia. The typical acellular capillaries and pericyte ghost were found in the diabetic retina, which also exhibited reduced retinal nerve fiber layer thickness compared to controls (all P < 0.05). Of note, distinct sub-RPE drusenoid lesions were extensively observed in these diabetic monkeys (46.43% vs. 7.69%), and complements including C3 and C5b-9 were deposited in these lesions. RNA-seq analysis revealed complement activation, AGE/RAGE activation and inflammatory response in diabetic RPE cells. Consistently, the plasma C3 and C4 were particularly increased in the diabetic monkeys with drusenoid lesions (P = 0.028 and 0.029).ConclusionsThe spontaneous type 2 diabetic monkeys featured with early-stage retinopathy including not only typical vascular and neural damage but also a distinct sub-RPE deposition. The complement activation of RPE cells in response to hyperglycemia might contribute to the deposition, revealing an unrecognized role of RPE cells in the early-stage pathological process of diabetic retinopathy.

| S-EPMC7991921 | biostudies-literature

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