Oxidative Stress Increases Endogenous Complement-Dependent Inflammatory and Angiogenic Responses in Retinal Pigment Epithelial Cells Independently of Exogenous Complement Sources

Trakkides, Timon-Orest; Schäfer, Nicole; Reichenthaler, Maria; Kühn, Konstanze; Brandwijk, Ricardo; Toonen, Erik J. M.; Urban, Florian; Wegener, Joachim; Enzmann, Volker; Pauly, Diana

doi:10.3390/antiox8110548

Cited by 30 publications

(70 citation statements)

References 65 publications

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“…FH downregulation leads to an increase in C3 mRNA levels, followed by accumulation of C3 in the extracellular compartment. In parallel, we detected a slight reduction of secreted FH after H 2 O 2 pre-treatment, a phenomenon previously observed in H 2 O 2 -treated ARPE19 cells 53 . In the afore mentioned study, in which RPE cells were treated with 500 µM H 2 O 2 , FH accumulates intracellularly, while in a different study, exposure to a mild and short oxidative insult (150 µM for 90 minutes) does not result in intracellular accumulation 54 .…”

Section: Discussionsupporting

confidence: 85%

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

Armento

Honisch

Panagiotakopoulou

et al. 2020

Sci Rep

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polymorphisms in the complement factor H (CFH) gene, coding for the factor H protein (fH), can increase the risk for age-related macular degeneration (AMD). AMD-associated CFH risk variants, Y402H in particular, impair FH function leading to complement overactivation. Whether this alone suffices to trigger AMD pathogenesis remains unclear. in AMD, retinal homeostasis is compromised due to the dysfunction of retinal pigment epithelium (Rpe) cells. to investigate the impact of endogenous fH loss on Rpe cell balance, we silenced CFH in human hTERT-RPE1 cells. FH reduction led to accumulation of C3, at both RNA and protein level and increased RPE vulnerability toward oxidative stress. Mild hydrogen-peroxide exposure in combination with CFH knock-down led to a reduction of glycolysis and mitochondrial respiration, paralleled by an increase in lipid peroxidation, which is a key aspect of AMD pathogenesis. in parallel, cell viability was decreased. the perturbations of energy metabolism were accompanied by transcriptional deregulation of several glucose metabolism genes as well as genes modulating mitochondrial stability. our data suggest that endogenously produced fH contributes to transcriptional and metabolic homeostasis and protects Rpe cells from oxidative stress, highlighting a novel role of fH in AMD pathogenesis. Retinal pigment epithelium (RPE) cells are crucial for the maintenance of retinal homeostasis. RPE cells are located on a thin membrane called Bruch´s membrane (BM), and together provide a barrier between the neuroretina and the choroid capillary network. In addition, RPE cells fulfil several key functions, such as phagocytosis of the photoreceptor outer segments, transport of nutrients, preservation of the retinal structure and, most importantly, due to their high antioxidant capacity, RPE cells protect the retina from photo-oxidation and oxidative damage 1. RPE dysfunction and degeneration are key features of age-related macular degeneration (AMD), a complex degenerative disease, and the primary cause of blindness in the elderly population 2. AMD is characterized by a progressive degeneration of the macula, the cone-rich area of the retina, where damage in this area leads to central vision loss and ultimately blindness 3. The aetiology of AMD involves ageing processes, genetic predisposition and environmental factors, however a full understanding of AMD pathogenesis is lacking, which makes drug discovery challenging 4. A defining hallmark of AMD is the presence of deposits, called drusen, between the BM and the RPE layer 5. In the presence of drusen or altered extracellular matrix (ECM) of BM, the functionality of RPE cells may be impaired 6. The retinal microenvironment is already highly oxidized in physiological conditions, due to a very high energy demand and photo-oxidation. Ageing processes, in combination with external stressors including smoking or a high fat diet 7,8 , force RPE cells to deal with excessive levels of oxidative stress. Disturbed RPE cell homeostasis, and in particular RPE cell ...

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Section: Discussionsupporting

confidence: 85%

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

Armento

Honisch

Panagiotakopoulou

et al. 2020

Sci Rep

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“…Immunostaining was performed as described previously [ 22 ]. PBS-washed, paraformaldehyde-fixated (4%, 20 min; Merck, # 100496) hpRPE cells were blocked 3% BSA (Carl Roth, Karlsruhe, Germany, #8076/ PBS-T, 1 h).…”

Section: Methodsmentioning

confidence: 99%

“…The RPE acts as a regulatory, secretory epithelium supporting the retina. It locally secretes complement components as C1q, complement factor B (CFB), complement component 4 (C4), CFI, and CFH [ 20 , 21 , 22 , 23 ]. We and others showed that complement secretion is modified by external stress [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

“…It locally secretes complement components as C1q, complement factor B (CFB), complement component 4 (C4), CFI, and CFH [ 20 , 21 , 22 , 23 ]. We and others showed that complement secretion is modified by external stress [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Additionally, generation of complement activation products, such as anaphylatoxins and opsonins, by healthy and stressed RPE cells independent of any external complement source is described [ 21 , 24 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

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Properdin Modulates Complement Component Production in Stressed Human Primary Retinal Pigment Epithelium Cells

et al. 2020

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The retinal pigment epithelium (RPE) maintains visual function and preserves structural integrity of the retina. Chronic dysfunction of the RPE is associated with retinal degeneration, including age-related macular degeneration (AMD). The AMD pathogenesis includes both increased oxidative stress and complement dysregulation. Physiological sources of oxidative stress in the retina are well known, while complement sources and regulation are still under debate. Using human primary RPE (hpRPE) cells, we have established a model to investigate complement component expression on transcript and protein level in AMD-risk and non-risk hpRPE cells. We evaluated the effect of properdin, a complement stabilizer, on the hpRPE cell-dependent complement profile exposed to oxidative stress. hpRPE cells expressed complement components, receptors and regulators. Complement proteins were also stored and secreted by hpRPE cells. We associated AMD-risk single nucleotide polymorphisms with an increased secretion of complement factors D (CFD) and I (CFI). Furthermore, we detected hpRPE cell-associated complement activation products (C3a, C5a) independent of any extracellularly added complement system. Exogenous properdin increased the mRNA expression of CFI and CFD, but decreased levels of complement components (C1Q, C3), receptors (C3AR, C5AR1, CD11B) and inflammation-associated transcripts (NLRP3, IL1B) in hpRPE cells exposed to oxidative stress. This properdin effect was time-dependently counter regulated. In conclusion, our data unveiled a local, genotype-associated complement component production in hpRPE cells, regulated by exogenous properdin. The local complement production and activation via blood-independent mechanisms can be a new therapeutic target for AMD.

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“…Oxidative stress and chronic inflammation are also responsible for the damage to retinal pigment epithelium (RPE) that contribute to several retinal degenerative diseases, such as age-related macular degeneration or Stargardt disease. Trakkides et al [5], for the first time, reported that oxidative stress induced an increased expression of the complement regulators (CFH) and properdin and the central complement protein C3 in RPE cells independent of an external complement source. These increases are, on the other hand, associated with inflammasome activation that, subsequently, enhanced secretion of proinflammatory and proangiogenic factors.…”

mentioning

confidence: 99%

Oxidative Stress and Inflammation as Targets for Novel Preventive and Therapeutic Approches in Non Communicable Diseases

Nediani¹,

Giovannelli

2020

Antioxidants

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Oxidative Stress Increases Endogenous Complement-Dependent Inflammatory and Angiogenic Responses in Retinal Pigment Epithelial Cells Independently of Exogenous Complement Sources

Cited by 30 publications

References 65 publications

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

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

Properdin Modulates Complement Component Production in Stressed Human Primary Retinal Pigment Epithelium Cells

Oxidative Stress and Inflammation as Targets for Novel Preventive and Therapeutic Approches in Non Communicable Diseases

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