scholarly journals Control of Complement Activation by the Long Pentraxin PTX3: Implications in Age-Related Macular Degeneration

2020 ◽  
Vol 11 ◽  
Author(s):  
Matteo Stravalaci ◽  
Francesca Davi ◽  
Raffaella Parente ◽  
Marco Gobbi ◽  
Barbara Bottazzi ◽  
...  
Keyword(s):  
Macular Degeneration ◽  
Complement Activation ◽  
Hot Spot ◽  
Alternative Pathway ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor ◽  
Rpe Cells ◽  
Age Related

Dysregulation of the complement system is central to age-related macular degeneration (AMD), the leading cause of blindness in the developed world. Most of the genetic variation associated with AMD resides in complement genes, with the greatest risk associated with polymorphisms in the complement factor H (CFH) gene; factor H (FH) is the major inhibitor of the alternative pathway (AP) of complement that specifically targets C3b and the AP C3 convertase. Long pentraxin 3 (PTX3) is a soluble pattern recognition molecule that has been proposed to inhibit AP activation via recruitment of FH. Although present in the human retina, if and how PTX3 plays a role in AMD is still unclear. In this work we demonstrated the presence of PTX3 in the human vitreous and studied the PTX3-FH-C3b crosstalk and its effects on complement activation in a model of retinal pigment epithelium (RPE). RPE cells cultured in inflammatory AMD-like conditions overexpressed the PTX3 protein, and up-regulated AP activating genes. PTX3 bound RPE cells in a physiological setting, however this interaction was reduced in inflammatory conditions, whereby PTX3 had no complement-inhibiting activity on inflamed RPE. However, on non-cellular surfaces, PTX3 formed a stable ternary complex with FH and C3b that acted as a “hot spot” for complement inhibition. Our findings suggest a protective role for PTX3 in response to complement dysregulation in AMD and point to a novel mechanism of complement regulation by this pentraxin with potential implications in pathology and pharmacology of AMD.

scholarly journals CFH Loss in Human RPE Cells Leads to Inflammation and Complement System Dysregulation via the NF-κB Pathway

2021 ◽  
Vol 22 (16) ◽  
pp. 8727
Author(s):  
Angela Armento ◽  
Tiziana L. Schmidt ◽  
Inga Sonntag ◽  
David A. Merle ◽  
Mohamed Ali Jarboui ◽  
...  
Keyword(s):  
Complement System ◽  
Vision Loss ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor ◽  
Major Pathway ◽  
Rpe Cells ◽  
Age Related

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is a degenerative disease of the macula, where retinal pigment epithelium (RPE) cells are damaged in the early stages of the disease, and chronic inflammatory processes may be involved. Besides aging and lifestyle factors as drivers of AMD, a strong genetic association to AMD is found in genes of the complement system, with a single polymorphism in the complement factor H gene (CFH), accounting for the majority of AMD risk. However, the exact mechanism of CFH dysregulation confers such a great risk for AMD and its role in RPE cell homeostasis is unclear. To explore the role of endogenous CFH locally in RPE cells, we silenced CFH in human hTERT-RPE1 cells. We demonstrate that endogenously expressed CFH in RPE cells modulates inflammatory cytokine production and complement regulation, independent of external complement sources, or stressors. We show that loss of the factor H protein (FH) results in increased levels of inflammatory mediators (e.g., IL-6, IL-8, GM-CSF) and altered levels of complement proteins (e.g., C3, CFB upregulation, and C5 downregulation) that are known to play a role in AMD. Moreover, our results identify the NF-κB pathway as the major pathway involved in regulating these inflammatory and complement factors. Our findings suggest that in RPE cells, FH and the NF-κB pathway work in synergy to maintain inflammatory and complement balance, and in case either one of them is dysregulated, the RPE microenvironment changes towards a proinflammatory AMD-like phenotype.

scholarly journals Complement factor H deficiency combined with smoking promotes retinal degeneration in a novel mouse model

2021 ◽  
pp. 153537022110522
Author(s):  
Liwen Feng ◽  
Kailai Nie ◽  
Qing Huang ◽  
Wei Fan
Keyword(s):  
Macular Degeneration ◽  
Cigarette Smoke ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor H ◽  
Complement Factor ◽  
Wild Type ◽  
Preclinical Research ◽  
Age Related

Age-related macular degeneration is the leading cause of blindness in the elderly. The Y402H polymorphism in complement factor H promotes disease-like pathogenesis, and a Cfh+/− murine model can replicate this phenotype, but only after two years. We reasoned that by combining CFH deficiency with cigarette smoke exposure, we might be able to accelerate disease progression to facilitate preclinical research in this disease. Wild-type and Cfh+/− mice were exposed to nose-only cigarette smoke for three months. Retinal tissue morphology and visual function were evaluated by optical coherence tomography, fundus photography and autofluorescence, and electroretinogram. Retinal pigment epithelial cell phenotype and ultrastructure were evaluated by immunofluorescence staining and transmission electron microscopy. Cfh+/− smoking mice showed a dome-like protruding lesion at the ellipsoid zone (drusen-like deposition), many retinal hyper-autofluorescence spots, and a marked decrease in A- and B-wave amplitudes. Compared with non-smoking mice, wild-type and Cfh+/− smoking mice showed sub-retinal pigment epithelium complement protein 3 deposition, activation of microglia, metabolic waste accumulation, and impairment of tight junctions. Microglia cells migrated into the photoreceptor outer segment layer in Cfh+/− smoking mice showed increased activation. Our results suggest that exposing Cfh+/− mice to smoking leads to earlier onset of age-related macular degeneration than in other animal models, which may facilitate preclinical research into the pathophysiology and treatment of this disease.

scholarly journals The role of complement system and other inflammatory factors in the development of age-related macular degeneration

2018 ◽  
Vol 99 (4) ◽  
pp. 657-664
Author(s):  
E A Abdulaeva
Keyword(s):  
Macular Degeneration ◽  
Complement System ◽  
Genetic Factors ◽  
Alternative Pathway ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Inflammatory Factors ◽  
Complement Factor ◽  
Age Related

The article is a review of literature on the role of complement system and inflammatory factors in the development of age-related macular degeneration. The review uses materials of domestic and foreign researchers. The clinical characteristics of age-related macular degeneration are presented, the role of genetic factors, complement factors, biomarkers of inflammation and alternative pathway of complement activation in the pathogenesis and risk of age-related macular degeneration is determined. Age-related macular degeneration is a chronic progressive multifactorial disease that affects macular area of the retina and is the main cause of loss of central vision in patients of older age group. The most important genetic factors are chromosome 1 (1q32) including complement factor H and complement factor H related genes and chromosome 10 (10q31). Variants associated with a moderate effect on developmental risk were identified in C3, complement factor I and complement factor B genes. In the pathogenesis of age-related macular degeneration, the key role is played by the damaged regulation of the alternative complement pathway. Single nucleotide polymorphisms in complement genes that affect the risk of development of age-related macular degeneration are predominantly involved in the alternative pathway of activation of the complement system. In pathomorphological studies, the initial localization of the pathological process of this pathology was established to be a complex of retinal pigment epithelium, Bruch’s membrane, and choriocapillaries followed by loss of photoreceptor function. The review of studies of systemic inflammatory biomarkers, cytokines, vascular endothelial growth factors in peripheral blood, blood serum, aqueous humour at various stages and forms of age-related macular degeneration is presented.

scholarly journals Complement Factor H-Related 3 Enhanced Inflammation and Complement Activation in Human RPE Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Nicole Schäfer ◽  
Anas Rasras ◽  
Delia M. Ormenisan ◽  
Sabine Amslinger ◽  
Volker Enzmann ◽  
...  
Keyword(s):  
Complement Activation ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor H ◽  
Complement Factor ◽  
Rpe Cells ◽  
Inflammatory Microenvironment ◽  
Age Related ◽  
Anaphylatoxin C3a ◽  
Human Rpe Cells

Complement Factor H-Related 3 (FHR-3) is a major regulator of the complement system, which is associated with different diseases, such as age-related macular degeneration (AMD). However, the non-canonical local, cellular functions of FHR-3 remained poorly understood. Here, we report that FHR-3 bound to oxidative stress epitopes and competed with FH for interaction. Furthermore, FHR-3 was internalized by viable RPE cells and modulated time-dependently complement component (C3, FB) and receptor (C3aR, CR3) expression of human RPE cells. Independently of any external blood-derived proteins, complement activation products were detected. Anaphylatoxin C3a was visualized in treated cells and showed a translocation from the cytoplasm to the cell membrane after FHR-3 exposure. Subsequently, FHR-3 induced a RPE cell dependent pro-inflammatory microenvironment. Inflammasome NLRP3 activation and pro-inflammatory cytokine secretion of IL-1ß, IL-18, IL-6 and TNF-α were induced after FHR-3-RPE interaction. Our previously published monoclonal anti-FHR-3 antibody, which was chimerized to reduce immunogenicity, RETC-2-ximab, ameliorated the effect of FHR-3 on ARPE-19 cells. Our studies suggest FHR-3 as an exogenous trigger molecule for the RPE cell “complosome” and as a putative target for a therapeutic approach for associated degenerative diseases.

scholarly journals Loss of Complement Factor H impairs antioxidant capacity and energy metabolism of human RPE cells

2020 ◽  
Author(s):  
Angela Armento ◽  
Sabina Honisch ◽  
Vasiliki Panagiotakopoulou ◽  
Inga Sonntag ◽  
Anke Jacob ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Energy Metabolism ◽  
Retinal Pigment ◽  
Factor H ◽  
Metabolic Reprogramming ◽  
Age Related Macular Degeneration ◽  
Complement Factor H ◽  
Complement Factor ◽  
Rpe Cells ◽  
Age Related

AbstractAge-related macular degeneration (AMD) is the leading cause of blindness in the elderly population. About 50% of AMD patients present polymorphisms in the Complement Factor H (CFH) gene, coding for Factor H protein (FH). AMD-associated CFH risk variants, Y402H in particular, impair FH function leading to complement overactivation. In AMD, retinal homeostasis is compromised due to dysfunction of retinal pigment epithelium (RPE) cells. Whether FH contributes to AMD pathogenesis only via complement system dysregulation remains unclear. To investigate the potential role of FH on energy metabolism and oxidative stress in RPE cells, we silenced CFH in human hTERT-RPE1 cells. FH-deprived RPE cells exposed to oxidative insult, showed altered metabolic homeostasis, including reduction of glycolysis and mitochondrial respiration, paralleled by an increase in lipid peroxidation. Our data suggest that FH protects RPE cells from oxidative stress and metabolic reprogramming, highlighting a novel function for FH in AMD pathogenesis.Graphical abstract

scholarly journals CFH loss in human RPE cells leads to inflammation and complement system dysregulation via the NF-ƙB pathway

2021 ◽  
Author(s):  
Angela Armento ◽  
Tiziana Luisa Schmidt ◽  
Inga Sonntag ◽  
David Merle ◽  
Mohamed-ali Jarboui ◽  
...  
Keyword(s):  
Complement System ◽  
Vision Loss ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor ◽  
Major Pathway ◽  
Rpe Cells ◽  
Age Related

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is a degenerative disease of the macula, where retinal pigment epithelium (RPE) cells are damaged in the early stages of the disease and chronic inflammatory processes may be involved. Besides ageing and lifestyle factors as drivers of AMD, a strong genetic association to AMD is found in genes of the complement system, with a single polymorphism in the complement factor H gene (CFH), accounting for the majority of AMD risk. However, the exact mechanism by which CFH dysregulation confers such a great risk for AMD and its role in RPE cells homeostasis is unclear. To explore the role of endogenous CFH locally in RPE cells, we silenced CFH in human hTERT-RPE1 cells. We demonstrate that endogenously expressed CFH in RPE cells modulates inflammatory cytokine production and complement regulation, independent of external complement sources or stressors. We show that loss of the factor H protein (FH) results in increased levels of inflammatory mediators (e.g. IL-6, IL-8, GM-CSF) and altered levels of complement proteins (e.g. C3, CFB upregulation and C5 downregulation) that are known to play a role in AMD. Moreover, we identified the NF-ƙB pathway as the major pathway involved in the regulation of these inflammatory and complement factors. Our findings suggest that in RPE cells, FH and the NF-ƙB pathway work in synergy to maintain inflammatory and complement balance and in case either one of them is dysregulated, the RPE microenvironment changes towards a pro-inflammatory AMD-like phenotype.

scholarly journals Complement Factor H-Related 3 induces inflammation and complosome activation in human RPE cells

2021 ◽  
Author(s):  
Nicole Schäfer ◽  
Anas Rasras ◽  
Delia Ceteras ◽  
Sabine Amslinger ◽  
Volker Enzmann ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Complement Factor H ◽  
Complement Factor ◽  
Rpe Cells ◽  
Age Related ◽  
Anaphylatoxin C3a ◽  
Human Rpe Cells

Abstract Background Complement Factor H-Related 3 (FHR-3) is a major regulator of the complement system, which is associated with different diseases, such as age-related macular degeneration. The non-canonical local, cellular functions of FHR-3 remained poorly understood.Methods Human retinal pigment epithelium (RPE) cells (ARPE-19 cells and primary human RPE cells (hpRPE)), cultivated in Transwell® inserts, were apically treated with either FHR‑3 alone or with the chimerized monoclonal anti‑FHR-3 antibody RETC-2-ximab, or with FHR-1, FH, Properdin or not treated for 5 – 24 h, respectively. Interaction of FHR-3 with oxidative stress epitopes was determined by ELISA. Internalization studies of FHR-3 or FH by ARPE‑19 cells was determined by immunofluorescence live cell imaging. Impact of FHR-3 on RPE cell-specific complement components and inflammation markers were analyzed on mRNA (RT-qPCR) and on protein level (Western Blot, ELISA, protein secretion assays, immunofluorescence). Results Here, we report that FHR-3 bound to oxidative stress epitopes and competed with FH for interaction. Furthermore, FHR-3 was internalized by senescent viable RPE cells and modulated time-dependently complement component (C3, CFB) and receptor (C3aR, CR3) expression of human RPE cells. Independently of any external blood-derived proteins, complement activation products were detected. Anaphylatoxin C3a was visualized in treated cells and showed a translocation from the cytoplasm to the cell membrane after FHR-3 exposure. Subsequently, FHR-3 induced a RPE cell dependent pro-inflammatory micro-environment. Inflammasome NLRP3 activation and pro-inflammatory cytokine secretion of IL-1ß, IL-18, IL-6 and TNF-α were induced after FHR-3-RPE interaction. Additionally, important pattern recognition molecules of the innate immune system, Toll-like receptors 1 and 3, as well as proteasome subunits were impaired in RPE cells after FHR-3 incubation. A chimerized monoclonal anti-FHR-3 antibody, RETC‑2‑ximab, ameliorated the effect of FHR-3 on ARPE-19 cells.Conclusion Our studies suggest FHR-3 as an exogenous trigger molecule for the RPE cell complosome and as a productive target for a new therapeutic approach using RETC‑2‑ximab for associated degenerative diseases.

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