Publications by authors named "Xavier Guillonneau"

47 Publications

Reproducing diabetic retinopathy features using newly developed human induced-pluripotent stem cell-derived retinal Müller glial cells.

Glia 2021 Mar 8. Epub 2021 Mar 8.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

Muller glial cells (MGCs) are responsible for the homeostatic and metabolic support of the retina. Despite the importance of MGCs in retinal disorders, reliable and accessible human cell sources to be used to model MGC-associated diseases are lacking. Although primary human MGCs (pMGCs) can be purified from post-mortem retinal tissues, the donor scarcity limits their use. To overcome this problem, we developed a protocol to generate and bank human induced pluripotent stem cell-derived MGCs (hiMGCs). Using a transcriptome analysis, we showed that the three genetically independent hiMGCs generated were homogeneous and showed phenotypic characteristics and transcriptomic profile of pMGCs. These cells expressed key MGC markers, including Vimentin, CLU, DKK3, SOX9, SOX2, S100A16, ITGB1, and CD44 and could be cultured up to passage 8. Under our culture conditions, hiMGCs and pMGCs expressed low transcript levels of RLPB1, AQP4, KCNJ1, KCJN10, and SLC1A3. Using a disease modeling approach, we showed that hiMGCs could be used to model the features of diabetic retinopathy (DR)-associated dyslipidemia. Indeed, palmitate, a major free fatty acid with elevated plasma levels in diabetic patients, induced the expression of inflammatory cytokines found in the ocular fluid of DR patients such as CXCL8 (IL-8) and ANGPTL4. Moreover, the analysis of palmitate-treated hiMGC secretome showed an upregulation of proangiogenic factors strongly related to DR, including ANG2, Endoglin, IL-1β, CXCL8, MMP-9, PDGF-AA, and VEGF. Thus, hiMGCs could be an alternative to pMGCs and an extremely valuable tool to help to understand and model glial cell involvement in retinal disorders, including DR.
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http://dx.doi.org/10.1002/glia.23983DOI Listing
March 2021

Modifications to the classical rat aortic ring model to allow vascular degeneration studies.

STAR Protoc 2021 Mar 21;2(1):100281. Epub 2021 Jan 21.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

The classical aortic ring model is well suited for deciphering pro-angiogenic processes. Here, we propose simple modifications of the standard protocol to study various anti-angiogenic processes from growth arrest to capillary degeneration. Aortic rings are cultured under basal conditions for 6 days to allow physiological vessel sprouting and then split into treatment groups to follow capillary growth or degeneration for an additional 2 days.
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http://dx.doi.org/10.1016/j.xpro.2020.100281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7821348PMC
March 2021

PDGF Receptor Alpha Signaling Is Key for Müller Cell Homeostasis Functions.

Int J Mol Sci 2021 Jan 25;22(3). Epub 2021 Jan 25.

Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-Universität München, D-82152 Planegg-Martinsried, Germany.

Müller cells, the major retinal macroglia, are key to maintaining vascular integrity as well as retinal fluid and ion homeostasis. Although platelet derived growth factor (PDGF) receptor expression in Müller glia has been reported earlier, their actual role for Müller cell function and intimate interaction with cells of the retinal neurovascular unit remains unclear. To close this gap of knowledge, Müller cell-specific PDGF receptor alpha (PDGFRα) knockout (KO) mice were generated, characterized, and subjected to a model of choroidal neovascularization (CNV). PDGFRα-deficient Müller cells could not counterbalance hypoosmotic stress as efficiently as their wildtype counterparts. In wildtypes, the PDGFRα ligand PDGF-BB prevented Müller cell swelling induced by the administration of barium ions. This effect could be blocked by the PDGFR family inhibitor AC710. PDGF-BB could not restore the capability of an efficient volume regulation in PDGFRα KO Müller cells. Additionally, PDGFRα KO mice displayed reduced rod and cone-driven light responses. Altogether, these findings suggest that Müller glial PDGFRα is central for retinal functions under physiological conditions. In contrast, Müller cell-specific PDGFRα KO resulted in less vascular leakage and smaller lesion areas in the CNV model. Of note, the effect size was comparable to pharmacological blockade of PDGF signaling alone or in combination with anti-vascular endothelial growth factor (VEGF) therapy-a treatment regimen currently being tested in clinical trials. These data imply that targeting PDGF to treat retinal neovascular diseases may have short-term beneficial effects, but may elicit unwarranted side effects given the putative negative effects on Müller cell homeostatic functions potentially interfering with a long-term positive outcome.
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http://dx.doi.org/10.3390/ijms22031174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7865899PMC
January 2021

Insulin inhibits inflammation-induced cone death in retinal detachment.

J Neuroinflammation 2020 Nov 26;17(1):358. Epub 2020 Nov 26.

Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France.

Background: Rhegmatogenous retinal detachment (RD) involving the macula is a major cause of visual impairment despite high surgical success rate, mainly because of cone death. RD causes the infiltration of activated immune cells, but it is not clear whether and how infiltrating inflammatory cells contribute to cone cell loss.

Methods: Vitreous samples from patients with RD and from control patients with macular hole were analyzed to characterize the inflammatory response to RD. A mouse model of RD and retinal explants culture were then used to explore the mechanisms leading to cone death.

Results: Analysis of vitreous samples confirms that RD induces a marked inflammatory response with increased cytokine and chemokine expression in humans, which is closely mimicked by experimental murine RD. In this model, we corroborate that myeloid cells and T-lymphocytes contribute to cone loss, as the inhibition of their accumulation by Thrombospondin 1 (TSP1) increased cone survival. Using monocyte/retinal co-cultures and TSP1 treatment in RD, we demonstrate that immune cell infiltration downregulates rod-derived cone viability factor (RdCVF), which physiologically regulates glucose uptake in cones. Insulin and the insulin sensitizers rosiglitazone and metformin prevent in part the RD-induced cone loss in vivo, despite the persistence of inflammation CONCLUSION: Our results describe a new mechanism by which inflammation induces cone death in RD, likely through cone starvation due to the downregulation of RdCVF that could be reversed by insulin. Therapeutic inhibition of inflammation and stimulation of glucose availability in cones by insulin signaling might prevent RD-associated cone death until the RD can be surgically repaired and improve visual outcome after RD.

Trial Registration: ClinicalTrials.gov NCT03318588.
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http://dx.doi.org/10.1186/s12974-020-02039-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7694924PMC
November 2020

[On the inflammatory origins of AMD].

Med Sci (Paris) 2020 Oct 7;36(10):886-892. Epub 2020 Oct 7.

Sorbonne Université, Inserm, CNRS, Institut de la vision, 17 rue Moreau, F-75012 Paris, France.

Age-related macular degeneration (AMD) is a complex, highly heritable, multifactorial disease caused by the interplay of age and genetic and environmental risk factors. No treatment has yet been found to treat the slowly progressing atrophic form of AMD. All forms of AMD are invariably associated with an accumulation of mononuclear phagocytes (MP) in the subretinal space, a family of cells that include inflammatory and resident macrophages. We here present an overview of the inflammatory process occurring in AMD and discuss the origin of MPs and the consequences of their accumulation in the subretinal space. Finally, we will review the role played by the established risk factors for AMD to promote the switch from beneficial inflammation in early stage to a deleterious inflammation in the advanced stage of the disease.
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http://dx.doi.org/10.1051/medsci/2020159DOI Listing
October 2020

The 10q26 Risk Haplotype of Age-Related Macular Degeneration Aggravates Subretinal Inflammation by Impairing Monocyte Elimination.

Immunity 2020 08;53(2):429-441.e8

Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France. Electronic address:

A minor haplotype of the 10q26 locus conveys the strongest genetic risk for age-related macular degeneration (AMD). Here, we examined the mechanisms underlying this susceptibility. We found that monocytes from homozygous carriers of the 10q26 AMD-risk haplotype expressed high amounts of the serine peptidase HTRA1, and HTRA1 located to mononuclear phagocytes (MPs) in eyes of non-carriers with AMD. HTRA1 induced the persistence of monocytes in the subretinal space and exacerbated pathogenic inflammation by hydrolyzing thrombospondin 1 (TSP1), which separated the two CD47-binding sites within TSP1 that are necessary for efficient CD47 activation. This HTRA1-induced inhibition of CD47 signaling induced the expression of pro-inflammatory osteopontin (OPN). OPN expression increased in early monocyte-derived macrophages in 10q26 risk carriers. In models of subretinal inflammation and AMD, OPN deletion or pharmacological inhibition reversed HTRA1-induced pathogenic MP persistence. Our findings argue for the therapeutic potential of CD47 agonists and OPN inhibitors for the treatment of AMD.
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http://dx.doi.org/10.1016/j.immuni.2020.07.021DOI Listing
August 2020

Disruption of profilin1 function suppresses developmental and pathological retinal neovascularization.

J Biol Chem 2020 07 22;295(28):9618-9629. Epub 2020 May 22.

Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Angiogenesis-mediated neovascularization in the eye is usually associated with visual complications. Pathological angiogenesis is particularly prominent in the retina in the settings of proliferative diabetic retinopathy, in which it can lead to permanent loss of vision. In this study, by bioinformatics analyses, we provide evidence for elevated expression of actin-binding protein PFN1 (profilin1) in the retinal vascular endothelial cells (VECs) of individuals with proliferative diabetic retinopathy, findings further supported by gene expression analyses for PFN1 in experimentally induced abnormal retinal neovascularization in an oxygen-induced retinopathy murine model. We observed that in a conditional knockout mouse model, postnatal deletion of the gene in VECs leads to defects in tip cell activity (marked by impaired filopodial protrusions) and reduced vascular sprouting, resulting in hypovascularization during developmental angiogenesis in the retina. Consistent with these findings, an investigative small molecule compound targeting the PFN1-actin interaction reduced random motility, proliferation, and cord morphogenesis of retinal VECs and experimentally induced abnormal retinal neovascularization In summary, these findings provide the first direct evidence that PFN1 is required for formation of actin-based protrusive structures and developmental angiogenesis in the retina. The proof of concept of susceptibility of abnormal angiogenesis to small molecule intervention of PFN1-actin interaction reported here lays a conceptual foundation for targeting PFN1 as a possible strategy in angiogenesis-dependent retinal diseases.
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http://dx.doi.org/10.1074/jbc.RA120.012613DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363146PMC
July 2020

Rescue of Defective Electroretinographic Responses in Dp71-Null Mice With AAV-Mediated Reexpression of Dp71.

Invest Ophthalmol Vis Sci 2020 02;61(2):11

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Purpose: To study the potential effect of a gene therapy, designed to rescue the expression of dystrophin Dp71 in the retinas of Dp71-null mice, on retinal physiology.

Methods: We recorded electroretinograms (ERGs) in Dp71-null and wild-type littermate mice. In dark-adapted eyes, responses to flashes of several strengths were measured. In addition, flash responses on a 25-candela/square meters background were measured. On- and Off-mediated responses to sawtooth stimuli and responses to photopic sine-wave modulation (3-30 Hz) were also recorded. After establishing the ERG phenotype, the ShH10-GFP adeno-associated virus (AAV), which has been previously shown to target specifically Müller glial cells (MGCs), was delivered intravitreously with or without (sham therapy) the Dp71 coding sequence under control of a CBA promoter. ERG recordings were repeated three months after treatment. Real-time quantitative PCR and Western blotting analyses were performed in order to quantify Dp71 expression in the retinas.

Results: Dp71-null mice displayed reduced b-waves in dark- and light-adapted flash ERGs and smaller response amplitudes to photopic rapid-on sawtooth modulation and to sine-wave stimuli. Three months after intravitreal injections of the ShH10-GFP-2A-Dp71 AAV vector, ERG responses were completely recovered in treated eyes of Dp71-null mice. The functional rescue was associated with an overexpression of Dp71 in treated retinas.

Conclusions: The present results show successful functional recovery accompanying the reexpression of Dp71. In addition, this experimental model sheds light on MGCs influencing ERG components, since previous reports showed that aquaporin 4 and Kir4.1 channels were mislocated in MGCs of Dp71-null mice, while their distribution could be normalized following intravitreal delivery of the same ShH10-GFP-2A-Dp71 vector.
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http://dx.doi.org/10.1167/iovs.61.2.11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7326481PMC
February 2020

CD36 Deficiency Inhibits Retinal Inflammation and Retinal Degeneration in Knockout Mice.

Front Immunol 2019 8;10:3032. Epub 2020 Jan 8.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

CD36, a member of the class B scavenger receptor family, participates in Toll-like receptor signaling on mononuclear phagocytes (MP) and can promote sterile pathogenic inflammation. We here analyzed the effect of CD36 deficiency on retinal inflammation and photoreceptor degeneration, the hallmarks of age-related macular degeneration (AMD), that characterize mice. We analyzed subretinal MP accumulation, and cone- and rod-degeneration in light-challenged and aged, CD36 competent or deficient, hyper-inflammatory mice, using histology and immune-stained retinal flatmounts. Monocytes (Mo) were subretinally adoptively transferred to evaluate their elimination rate from the subretinal space and Interleukin 6 (IL-6) secretion from cultured Mo-derived cells (MdCs) of the different mouse strains were analyzed. CD36 deficient mice were protected against age- and light-induced subretinal inflammation and associated cone and rod degeneration. CD36 deficiency in MPs inhibited their prolonged survival in the immune-suppressive subretinal space and reduced the exaggerated IL-6 secretion observed in MPs that we previously showed leads to increased subretinal MP survival. deficiency significantly protected hyperinflammatory mice against subretinal MP accumulation and associated photoreceptor degeneration. The observed CD36-dependent induction of pro-inflammatory IL-6 might be at least partially responsible for the prolonged MP survival in the immune-suppressive environment and its pathological consequences on photoreceptor homeostasis.
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http://dx.doi.org/10.3389/fimmu.2019.03032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960398PMC
November 2020

IL-1β induces rod degeneration through the disruption of retinal glutamate homeostasis.

J Neuroinflammation 2020 Jan 3;17(1). Epub 2020 Jan 3.

Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012, Paris, France.

Background: Age-related macular degeneration is characterized by the accumulation of subretinal macrophages and the degeneration of cones, but mainly of rods. We have previously shown that Mononuclear Phagocytes-derived IL-1β induces rod photoreceptor cell death during experimental subretinal inflammation and in retinal explants exposed to IL-1β but the mechanism is unknown.

Methods: Retinal explants were culture in the presence of human monocytes or IL-1β and photoreceptor cell survival was analyzed by TUNEL labeling. Glutamate concentration and transcription levels of gene involved in the homeostasis of glutamate were analyzed in cell fractions of explant cultured or not in the presence of IL-1β. Glutamate receptor antagonists were evaluated for their ability to reduce photoreceptor cell death in the presence of IL1-β or monocytes.

Results: We here show that IL-1β does not induce death in isolated photoreceptors, suggesting an indirect effect. We demonstrate that IL-1β leads to glutamate-induced rod photoreceptor cell death as it increases the extracellular glutamate concentrations in the retina through the inhibition of its conversion to glutamine in Müller cells, increased release from Müller cells, and diminished reuptake. The inhibition of non-NMDA receptors completely and efficiently prevented rod apoptosis in retinal explants cultured in the presence of IL-1β or, more importantly, in vivo, in a model of subretinal inflammation.

Conclusions: Our study emphasizes the importance of inflammation in the deregulation of glutamate homeostasis and provides a comprehensive mechanism of action for IL-1β-induced rod degeneration.
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http://dx.doi.org/10.1186/s12974-019-1655-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942287PMC
January 2020

Evidence of the involvement of dystrophin Dp71 in corneal angiogenesis.

Mol Vis 2019 14;25:714-721. Epub 2019 Nov 14.

Institut De La Vision, Sorbonne Universités, UPMC Univ Paris 06, UMR_S, 968, Paris, France, Paris, France.

Purpose: The aim of this study was to define the role of dystrophin Dp71 in corneal angiogenesis.

Methods: Inflammation-induced corneal neovascularization experiments were performed in -null mice and C57BL/6J wild-type mice.

Results: The corneal neovascular area covered by neovascularization was larger in the injured corneas of the -null mice compared to the corneas of the wild-type mice: 40.72% versus 26.33%, respectively (p<0.005). Moreover, increased angiogenesis was associated with a high expression of vascular endothelial growth factor (VEGF). Similarly, aortic ring assays showed a significant enhancement of the neovascular area.

Conclusions: These results suggest that dystrophin Dp71 could play an important role as a negative regulator of corneal angiogenesis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6857772PMC
June 2020

Glucagon-like Peptide 1 Receptor Agonists, Diabetic Retinopathy and Angiogenesis: The AngioSafe Type 2 Diabetes Study.

J Clin Endocrinol Metab 2020 04;105(4)

Center for Interdisciplinary Research in Biology (CIRB), College de France - Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM), Paris Sciences et Lettres (PSL) Research University, Paris, France.

Aims: Recent trials provide conflicting results on the association between glucagon-like peptide 1 receptor agonists (GLP-1RA) and diabetic retinopathy (DR). The aim of the AngioSafe type 2 diabetes (T2D) study was to determine the role of GLP-1RA in angiogenesis using clinical and preclinical models.

Methods: We performed two studies in humans. In study 1, we investigated the effect of GLP-1RA exposure from T2D diagnosis on the severity of DR, as diagnosed with retinal imaging (fundus photography). In study 2, a randomized 4-week trial, we assessed the effect of liraglutide on circulating hematopoietic progenitor cells (HPCs), and angio-miRNAs.We then studied the experimental effect of Exendin-4, on key steps of angiogenesis: in vitro on human endothelial cell proliferation, survival and three-dimensional vascular morphogenesis; and in vivo on ischemia-induced neovascularization of the retina in mice.

Results: In the cohort of 3154 T2D patients, 10% displayed severe DR. In multivariate analysis, sex, disease duration, glycated hemoglobin (HbA1c), micro- and macroangiopathy, insulin therapy and hypertension remained strongly associated with severe DR, while no association was found with GLP-1RA exposure (o 1.139 [0.800-1.622], P = .47). We further showed no effect of liraglutide on HPCs, and angio-miRNAs. In vitro, we demonstrated that exendin-4 had no effect on proliferation and survival of human endothelial cells, no effect on total length and number of capillaries. Finally, in vivo, we showed that exendin-4 did not exert any negative effect on retinal neovascularization.

Conclusions: The AngioSafe T2D studies provide experimental and clinical data confirming no effect of GLP-1RA on angiogenesis and no association between GLP-1 exposure and severe DR.
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http://dx.doi.org/10.1210/clinem/dgz069DOI Listing
April 2020

Mo-derived perivascular macrophage recruitment protects against endothelial cell death in retinal vein occlusion.

J Neuroinflammation 2019 Jul 27;16(1):157. Epub 2019 Jul 27.

INSERM, CNRS, Institut de la Vision, 17 rue Moreau, Sorbonne Université, UPMC Univ Paris 06, F-75012, Paris, France.

Background: To decipher the role of monocyte-derived macrophages (Mφs) in vascular remodeling of the occluded vein following experimental branch retinal vein occlusion (BRVO).

Methods: The inflammation induced by laser-induced BRVO on mice retina was evaluated at different time points by RT-PCR looking at inflammatory markers mRNA level expression, Icam-1, Cd11b, F4/80, Ccl2, and Ccr2 and by quantification of Iba1-positive macrophage (Mφ) density on Iba1-stained retinal flatmount. Repeated intraperitoneal EdU injection combined with liposome clodronate-induced monocyte (Mo) depletion in wildtype mice was used to differentiate Mo-derived Mφs from resident Mφs. Liposome clodronate Mo-depleted wildtype mice and Ccr2-deficient mice were used to evaluate the role of all CCR2 and CCR2 Mo-derived Mφs on EC apoptosis in the occluded vein.

Results: cd11b, ICAM-1, F4/80, Ccl2, and Ccr2 mRNA expression were increased 1, 3, and 7 days after vein occlusion. The number of parenchymal (parMφs) and perivascular (vasMφs) macrophages was increased 3 and 7 days after BRVO. The systemic depletion of all circulating Mos decreased significantly the BRVO-induced parMφs and vasMφs macrophage accumulation, while the deletion of CCR2-inflammatory Mo only diminished the accumulation of parMφs, but not vasMφs. Finally, apoptotic ECs of the vein were more numerous in fully depleted, liposome clodronate-treated mice, than in Ccr2 mice that only lack the recruitment of CCR2 inflammatory Mos.

Conclusions: BRVO triggers the recruitment of blood-derived parMφs and vasMφs. Interestingly, vasMφs accumulation was independent of CCR2. The observation that the inhibition of the recruitment of all infiltrating Mφs increases the vein EC apoptosis, while CCR2 deficiency does not, demonstrates that CCR2 Mo-derived vasMφs protect the ECs against apoptosis in the occluded vein.
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http://dx.doi.org/10.1186/s12974-019-1547-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6660930PMC
July 2019

Expression and localization of dystrophins and β-dystroglycan in the hypothalamic supraoptic nuclei of rat from birth to adulthood.

Acta Histochem 2019 Feb 28;121(2):218-226. Epub 2018 Dec 28.

Equipe de Neurochimie, LBPO, Faculté des Sciences Biologiques, USTHB, Alger, Algeria.

Dystrophins (Dps) are the sub-membranous proteins that work via the dystrophin-associated proteins complex, which comprises β-dystroglycan (β-DG), a cell surface receptor for extracellular matrix. Recently, we have revealed β-DG decrease and central function impairment of supraoptic nucleus (SON) in Dp71 deficient adult mice, opening the question on the profiles of Dps and β-DG during SON development. At birth and the age of 10, 20 and 60 days, we examined the expression by RT-PCR and Western-blotting, and the distribution by immunohistochemistry of Dps and β-DG. Also, we analyzed, by immunohistochemistry and Western-blotting, the neuropeptide, arginine vasopressin (AVP), in the SON at the different ages. At birth, Dp71 and to a lesser extends, Dp140 and Dp427, and also β-DG are revealed in the SON. They are localized in the magnocellular neurons (MCNs), astrocytes and vessels. From birth to adulthood, the AVP raise in the SON coincides with the progressive increase of Dp71 level while the level of Dp140 and Dp427 increased only at D20, D10 post-natal development, respectively, and β-DG expression did not change. Moreover, the location of Dps or/and β-DG in the cell compartments was modified during development: at D10, Dps appeared in the astrocytes end-feet surrounding MCNs, and at D20, Dps and β-DG codistributed in the astrocytes end-feet, surrounding MCNs and vessels. Such a distribution marks the first steps of post-natal SON development and may be considered essential in the establishment of structural plasticity mechanisms in SON, where astrocyte end-feet, vessels, magnocellular neurons, are physiologically associated. The disappearance of β-DG in the MCNs nucleus marks the adulthood SON and suggests that the complex of Dps associating β-DG is required for the nucleoskeleton function in the post-natal development.
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http://dx.doi.org/10.1016/j.acthis.2018.12.001DOI Listing
February 2019

Chronic exposure to tumor necrosis factor alpha induces retinal pigment epithelium cell dedifferentiation.

J Neuroinflammation 2018 Mar 16;15(1):85. Epub 2018 Mar 16.

Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012, Paris, France.

Background: The retinal pigment epithelium (RPE) is a monolayer of pigmented cells with important barrier and immuno-suppressive functions in the eye. We have previously shown that acute stimulation of RPE cells by tumor necrosis factor alpha (TNFα) downregulates the expression of OTX2 (Orthodenticle homeobox 2) and dependent RPE genes. We here investigated the long-term effects of TNFα on RPE cell morphology and key functions in vitro.

Methods: Primary porcine RPE cells were exposed to TNFα (at 0.8, 4, or 20 ng/ml per day) for 10 days. RPE cell morphology, phagocytosis, barrier- and immunosuppressive-functions were assessed.

Results: Chronic (10 days) exposure of primary RPE cells to TNFα increases RPE cell size and polynucleation, decreases visual cycle gene expression, impedes RPE tight-junction organization and transepithelial resistance, and decreases the immunosuppressive capacities of the RPE. TNFα-induced morphological- and transepithelial-resistance changes were prevented by concomitant Transforming Growth Factor β inhibition.

Conclusions: Our results indicate that chronic TNFα-exposure is sufficient to alter RPE morphology and impede cardinal features that define the differentiated state of RPE cells with striking similarities to the alterations that are observed with age in neurodegenerative diseases such as age-related macular degeneration.
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http://dx.doi.org/10.1186/s12974-018-1106-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857126PMC
March 2018

On phagocytes and macular degeneration.

Prog Retin Eye Res 2017 Nov 7;61:98-128. Epub 2017 Jun 7.

Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012, Paris, France. Electronic address:

Age related macular degeneration (AMD) is a complex multifactorial disease caused by the interplay of age and genetic and environmental risk factors. A common feature observed in early and both forms of late AMD is the breakdown of the physiologically immunosuppressive subretinal environment and the protracted accumulation of mononuclear phagocytes (MP). We here discuss the origin and nature of subretinal MPs, the mechanisms that lead to their accumulation, the inflammatory mediators they produce as well as the consequences of their chronic presence on photoreceptors, retinal pigment epithelium and choroid. Recent advances highlight how both genetic and environmental risk factors directly promote subretinal inflammation and tip the balance from a beneficial inflammation that helps control debris accumulation to detrimental chronic inflammation and destructive late AMD. Finally, we discuss how changes in life style or pharmacological intervention can help to break the vicious cycle of inflammation and degeneration, restore the immunosuppressive properties of the subretinal space, and reestablish homeostasis.
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http://dx.doi.org/10.1016/j.preteyeres.2017.06.002DOI Listing
November 2017

Complement Factor H Inhibits CD47-Mediated Resolution of Inflammation.

Immunity 2017 02;46(2):261-272

Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012 Paris, France. Electronic address:

Variants of the CFH gene, encoding complement factor H (CFH), show strong association with age-related macular degeneration (AMD), a major cause of blindness. Here, we used murine models of AMD to examine the contribution of CFH to disease etiology. Cfh deletion protected the mice from the pathogenic subretinal accumulation of mononuclear phagocytes (MP) that characterize AMD and showed accelerated resolution of inflammation. MP persistence arose secondary to binding of CFH to CD11b, which obstructed the homeostatic elimination of MPs from the subretinal space mediated by thrombospsondin-1 (TSP-1) activation of CD47. The AMD-associated CFH(H402) variant markedly increased this inhibitory effect on microglial cells, supporting a causal link to disease etiology. This mechanism is not restricted to the eye, as similar results were observed in a model of acute sterile peritonitis. Pharmacological activation of CD47 accelerated resolution of both subretinal and peritoneal inflammation, with implications for the treatment of chronic inflammatory disease.
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http://dx.doi.org/10.1016/j.immuni.2017.01.006DOI Listing
February 2017

Col4a1 mutation generates vascular abnormalities correlated with neuronal damage in a mouse model of HANAC syndrome.

Neurobiol Dis 2017 Apr 3;100:52-61. Epub 2017 Jan 3.

INSERM, U968, Institut de la Vision, Paris F-75012, France; Sorbonne Universités, UPMC Univ Paris 06, UMR_S968, Institut de la Vision, Paris, F-75012, France; CNRS UMR7210, Institut de la Vision, Paris 75012, France. Electronic address:

The HANAC syndrome is caused by mutations in the gene coding for collagen4a1, a major component of blood vessel basement membranes. Ocular symptoms include an increase in blood vessel tortuosity and occasional hemorrhages. To examine how vascular defects can affect neuronal function, we analyzed the retinal phenotype of a HANAC mouse model. Heterozygous mutant mice displayed both a thinning of the basement membrane in retinal blood vessels and in Bruch's membrane resulting in vascular leakage. Homozygous mice had additional vascular changes, including greater vessel coverage and tortuosity. This greater tortuosity was associated to higher expression levels of vascular endothelial growth factor (VEGF). These major changes to the blood vessels were correlated with photoreceptor dysfunction and degeneration. The neuronal damage was associated with reactive gliosis in astrocytes and Müller glial cells, and by the migration of microglial cells into the outer retina. This study illustrates how vascular changes can trigger neuronal degeneration in a new model of HANAC syndrome that can be used to further study dysfunctions of neurovascular coupling.

Summary Statement: This study provides a phenotypic analysis of a novel mouse model of HANAC syndrome focusing on the retinal aspect. It recapitulates most of the aspects of the human disease and is therefore a great tool to study and to address this condition.
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http://dx.doi.org/10.1016/j.nbd.2016.12.014DOI Listing
April 2017

Lebecetin, a C-type lectin, inhibits choroidal and retinal neovascularization.

FASEB J 2017 03 14;31(3):1107-1119. Epub 2016 Dec 14.

Sorbonne Universités, Université Pierre et Marie Curie, INSERM, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, France;

Angiogenesis is a cause of visual impairment and blindness in the wet form of age-related macular degeneration and in ischemic retinopathies. Current therapies include use of anti-VEGF agents to reduce choroidal neovascularization (CNV) and edema. These treatments are effective in most cases, but spontaneous or acquired resistance to anti-VEGF and possible adverse effects of long-term VEGF inhibition in the retina and choroid highlight a need for additional alternative therapies. Integrins αvβ3 and αvβ5, which regulate endothelial cell proliferation and stabilization, have been implicated in ocular angiogenesis. Lebecetin (LCT) is a 30-kDa heterodimeric C-type lectin that is isolated from venom and interacts with α5β1- and αv-containing integrins. We previously showed that LCT inhibits human brain microvascular endothelial cell adhesion, migration, proliferation, and tubulogenesis. To evaluate the inhibitory effect of LCT on ocular angiogenesis, we cultured aortic and choroidal explants in the presence of LCT and analyzed the effect of LCT on CNV in the mouse CNV model and on retinal neovascularization in the oxygen-induced retinopathy model. Our data demonstrate that a single injection of LCT efficiently reduced CNV and retinal neovascularization in these models.-Montassar, F., Darche, M., Blaizot, A., Augustin, S., Conart, J.-B., Millet, A., Elayeb, M., Sahel, J.-A., Réaux-Le Goazigo, A., Sennlaub, F., Marrakchi, N., Messadi, E., Guillonneau, X. Lebecetin, a C-type lectin, inhibits choroidal and retinal neovascularization.
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http://dx.doi.org/10.1096/fj.201600351RDOI Listing
March 2017

Activated monocytes resist elimination by retinal pigment epithelium and downregulate their OTX2 expression via TNF-α.

Aging Cell 2017 Feb 22;16(1):173-182. Epub 2016 Sep 22.

Institut de la Vision, 17 rue Moreau, 75012, Paris, France.

Orthodenticle homeobox 2 (OTX2) controls essential, homeostatic retinal pigment epithelial (RPE) genes in the adult. Using cocultures of human CD14 blood monocytes (Mos) and primary porcine RPE cells and a fully humanized system using human-induced pluripotent stem cell-derived RPE cells, we show that activated Mos markedly inhibit RPEOTX2 expression and resist elimination in contact with the immunosuppressive RPE. Mechanistically, we demonstrate that TNF-α, secreted from activated Mos, mediates the downregulation of OTX2 and essential RPE genes of the visual cycle among others. Our data show how subretinal, chronic inflammation and in particular TNF-α can affect RPE function, which might contribute to the visual dysfunctions in diseases such as age-related macular degeneration (AMD) where subretinal macrophages are observed. Our findings provide important mechanistic insights into the regulation of OTX2 under inflammatory conditions. Therapeutic restoration of OTX2 expression might help revive RPE and visual function in retinal diseases such as AMD.
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http://dx.doi.org/10.1111/acel.12540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5242302PMC
February 2017

Subretinal mononuclear phagocytes induce cone segment loss via IL-1β.

Elife 2016 07 20;5. Epub 2016 Jul 20.

Sorbonne Universités, UPMC University Paris 06, INSERM, CNRS, Paris, France.

Photo-transduction in cone segments (CS) is crucial for high acuity daytime vision. For ill-defined reasons, CS degenerate in retinitis pigmentosa (RP) and in the transitional zone (TZ) of atrophic zones (AZ), which characterize geographic atrophy (GA). Our experiments confirm the loss of cone segments (CS) in the TZ of patients with GA and show their association with subretinal CD14(+)mononuclear phagocyte (MP) infiltration that is also reported in RP. Using human and mouse MPs in vitro and inflammation-prone Cx3cr1(GFP/GFP) mice in vivo, we demonstrate that MP-derived IL-1β leads to severe CS degeneration. Our results strongly suggest that subretinal MP accumulation participates in the observed pathological photoreceptor changes in these diseases. Inhibiting subretinal MP accumulation or Il-1β might protect the CS and help preserve high acuity daytime vision in conditions characterized by subretinal inflammation, such as AMD and RP.
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http://dx.doi.org/10.7554/eLife.16490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4969036PMC
July 2016

Association of Choroidal Interleukin-17-Producing T Lymphocytes and Macrophages with Geographic Atrophy.

Ophthalmologica 2016 10;236(1):53-8. Epub 2016 Jun 10.

Unitx00E9; de Recherche Clinique Lariboisix00E8;re Saint-Louis, AP-HP, Paris, France.

Purpose: To evaluate the presence of interleukin-17 (IL-17)-producing cells in patients with geographic atrophy (GA).

Methods: In this short report, we analyzed IL-17, CD3, and IBA-1 expression by immunohistochemistry on paraffin-embedded sections from 13 donors with a known history of GA, confirmed by fundus appearance and histology, and 7 age-matched control donors.

Results/conclusion: We showed that IL-17+ cells are found near areas of retinal pigmented epithelium atrophy in the eyes of GA patients. IL-17+ cells mainly localized to CD3+ cells, which identifies T lymphocytes, as well as IBA-1+ cells, which identifies mononuclear phagocytes. Therefore, IL-17 could be involved in the pathological mechanisms that contribute to the degeneration observed in GA.
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http://dx.doi.org/10.1159/000446587DOI Listing
January 2017

CC5 and CC8, two homologous disintegrins from Cerastes cerastes venom, inhibit in vitro and ex vivo angiogenesis.

Int J Biol Macromol 2016 May 4;86:670-80. Epub 2016 Feb 4.

Laboratoire des Venins et Biomolécules Thérapeutiques LR11IPT08, Institut Pasteur de Tunis, 13, Place Pasteur, 1002 Tunis, Tunisia; Université de Tunis el Manar, 1068 Tunis, Tunisia; Faculté de Médecine de Tunis, Tunis, Tunisia.

Angiogenesis constitutes a fundamental step in tumor progression. Thus, targeting tumour angiogenesis has been identified to be promising in cancer treatment. In this work, CC5 and CC8, two highly homologous disintegrins isolated from the venom Cerastes cerastes viper from the south of Tunisia, were assessed for their anti-angiogenic effect by testing their ability to interfere with viability, adhesion, migration and angiogenesis of Human Microvascular Endothelial Cells, HMEC-1 and HBMEC. We found that CC5 and CC8 displayed pro-apoptotic potential in HMEC-1 cells. Anoïkis like induced by these two disintegrins was evidenced by cell detachment, down regulation of FAK/AKT/PI3K axis and caspase activation. In addition, both CC5 and CC8 exhibited in vitro anti-adhesive, anti-migratory and anti-proliferative effects on endothelial cells HBMEC. These effects appeared to require RGD and/or WGD loops disintegrin. CC5 and CC8 also inhibited tube-formation on matrigel and displayed potent anti-angiogenic activities as assessed ex vivo, using both the embryo chick chorioallantoic membrane model (CAM) and rat aortic ring assay. Altogether our results demonstrate that CC5 and CC8, are potent inhibitors of angiogenesis, by disrupting αvβ3 and α5β1 binding. The use of CC5 and/or CC8 could provide a beneficial tool to inhibit abnormal angiogenesis and to induce cancer regression.
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http://dx.doi.org/10.1016/j.ijbiomac.2016.02.008DOI Listing
May 2016

Altered astrocyte morphology and vascular development in dystrophin-Dp71-null mice.

Glia 2016 May 29;64(5):716-29. Epub 2015 Dec 29.

Institut De La Vision, Sorbonne Universités, UPMC Univ Paris 06, UMR_S, 968, Paris, F-75012, France.

Understanding retinal vascular development is crucial because many retinal vascular diseases such as diabetic retinopathy (in adults) or retinopathy of prematurity (in children) are among the leading causes of blindness. Given the localization of the protein Dp71 around the retinal vessels in adult mice and its role in maintaining retinal homeostasis, the aim of this study was to determine if Dp71 was involved in astrocyte and vascular development regulation. An experimental study in mouse retinas was conducted. Using a dual immunolabeling with antibodies to Dp71 and anti-GFAP for astrocytes on retinal sections and isolated astrocytes, it was found that Dp71 was expressed in wild-type (WT) mouse astrocytes from early developmental stages to adult stage. In Dp71-null mice, a reduction in GFAP-immunopositive astrocytes was observed as early as postnatal day 6 (P6) compared with WT mice. Using real-time PCR, it was showed that Dp71 mRNA was stable between P1 and P6, in parallel with post-natal vascular development. Regarding morphology in Dp71-null and WT mice, a significant decrease in overall astrocyte process number in Dp71-null retinas at P6 to adult age was found. Using fluorescence-conjugated isolectin Griffonia simplicifolia on whole mount retinas, subsequent delay of developing vascular network at the same age in Dp71-null mice was found. An evidence that the Dystrophin Dp71, a membrane-associated cytoskeletal protein and one of the smaller Duchenne muscular dystrophy gene products, regulates astrocyte morphology and density and is associated with subsequent normal blood vessel development was provided.
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http://dx.doi.org/10.1002/glia.22956DOI Listing
May 2016

APOE Isoforms Control Pathogenic Subretinal Inflammation in Age-Related Macular Degeneration.

J Neurosci 2015 Oct;35(40):13568-76

Institut National de la Santé et de la Recherche Médicale, U 968, Paris, F-75012, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche S 968, Institut de la Vision, Paris, F-75012, France, CNRS, Unité Mixte de Recherche 7210, Paris, F-75012, France,

Unlabelled: Contrary to Alzheimer's disease (AD), the APOE2 allele increases and the APOE4 allele reduces the risk to develop age-related macular degeneration (AMD) compared with the most common APOE3 allele. The underlying mechanism for this association with AMD and the reason for the puzzling difference with AD are unknown. We previously demonstrated that pathogenic subretinal mononuclear phagocytes (MPs) accumulate in Cx3cr1-deficient mice due to the overexpression of APOE, interleukin-6, and CC chemokine ligand 2 (CCL2). We here show using targeted replacement mice expressing the human APOE isoforms (TRE2, TRE3, and TRE4) that MPs of TRE2 mice express increased levels of APOE, interleukin-6, and CCL2 and develop subretinal MP accumulation, photoreceptor degeneration, and exaggerated choroidal neovascularization similar to AMD. Pharmacological inhibition of the cytokine induction inhibited the pathogenic subretinal inflammation. In the context of APOE-dependent subretinal inflammation in Cx3cr1(GFP/GFP) mice, the APOE4 allele led to diminished APOE and CCL2 levels and protected Cx3cr1(GFP/GFP) mice against harmful subretinal MP accumulation observed in Cx3cr1(GFP/GFP)TRE3 mice. Our study shows that pathogenic subretinal inflammation is APOE isoform-dependent and provides the rationale for the previously unexplained implication of the APOE2 isoform as a risk factor and the APOE4 isoform as a protective factor in AMD pathogenesis.

Significance Statement: The understanding of how genetic predisposing factors, which play a major role in age-related macular degeneration (AMD), participate in its pathogenesis is an important clue to decipher the pathomechanism and develop efficient therapies. In this study, we used transgenic, targeted replacement mice that carry the three human APOE isoform-defining sequences at the mouse APOE chromosomal location and express the human APOE isoforms. Our study is the first to show how APOE2 provokes and APOE4 inhibits the cardinal AMD features, inflammation, degeneration, and exaggerated neovascularization. Our findings reflect the clinical association of the genetic predisposition that was recently confirmed in a major pooled analysis. They emphasize the role of APOE in inflammation and inflammation in AMD.
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http://dx.doi.org/10.1523/JNEUROSCI.2468-15.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6605380PMC
October 2015

Thinning of the RPE and choroid associated with T lymphocyte recruitment in aged and light-challenged mice.

Mol Vis 2015 2;21:1051-9. Epub 2015 Sep 2.

INSERM, U968, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France ; CNRS, UMR_7210, Paris, France.

Purpose: Thinning of the RPE and the underlying vascular layer, the choroid, is observed with age in many human eye disorders. The reasons for this thinning are ill-defined. Here, we highlight the possible role of T lymphocyte recruitment in choroidoretinal thinning in aged and light-challenged mice.

Methods: In age and light challenge models, we measured chemokine concentrations using enzyme-linked immunosorbent assay and used flow cytometry to characterize lymphocyte populations. We quantified thinning in eye immunosections and RPE65 expression using quantitative PCR.

Results: Age and light challenge led to increased levels of the lymphotactic protein CXCL10 alone (aging) or in conjunction with CXCL9 (light challenge). Increased numbers of CD3+ T lymphocytes, most of them CD8+ cytotoxic T lymphocytes, were also observed in the choroid and retina of old mice and following light challenge. Influx of T lymphocytes was associated with RPE and choroidal thinning and diminished expression of RPE65 mRNA, an essential enzyme of the visual cycle.

Conclusions: The observations from this study suggest that cytotoxic CD8(+) T lymphocytes might participate in choroidal and RPE degeneration and that modulation of T lymphocyte recruitment might be a novel strategy to reduce choroidoretinal dysfunctions observed with age and following photo-oxidative stress.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558476PMC
June 2016

Experimental Branch Retinal Vein Occlusion Induces Upstream Pericyte Loss and Vascular Destabilization.

PLoS One 2015 24;10(7):e0132644. Epub 2015 Jul 24.

INSERM, U968, Paris, F-75012, France; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France; CNRS, UMR_7210, Paris, F-75012, France.

Aims: Branch retinal vein occlusion (BRVO) leads to extensive vascular remodeling and is important cause of visual impairment. Although the vascular morphological changes following experimental vein occlusion have been described in a variety of models using angiography, the underlying cellular events are ill defined.

Methods And Results: We here show that laser-induced experimental BRVO in mice leads to a wave of TUNEL-positive endothelial cell (EC) apoptosis in the upstream vascular network associated with a transient edema and hemorrhages. Subsequently, we observe an induction of EC proliferation within the dilated vein and capillaries, detected by EdU incorporation, and the edema resolves. However, the pericytes of the upstream capillaries are severely reduced, which was associated with continuing EC apoptosis and proliferation. The vascular remodeling was associated with increased expression of TGFβ, TSP-1, but also FGF2 expression. Exposure of the experimental animals to hypoxia, when pericyte (PC) dropout had occurred, led to a dramatic increase in endothelial cell proliferation, confirming the vascular instability induced by the experimental BRVO.

Conclusion: Experimental BRVO leads to acute endothelial cells apoptosis and increased permeability. Subsequently the upstream vascular network remains destabilized, characterized by pericyte dropout, un-physiologically high endothelial cells turnover and sensitivity to hypoxia. These early changes might pave the way for capillary loss and subsequent chronic ischemia and edema that characterize the late stage disease.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0132644PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514656PMC
May 2016

Upregulation of P2RX7 in Cx3cr1-Deficient Mononuclear Phagocytes Leads to Increased Interleukin-1β Secretion and Photoreceptor Neurodegeneration.

J Neurosci 2015 May;35(18):6987-96

INSERM, U 968, Paris F-75012, France, Sorbonne Universités, UPMC Univ Paris 06, UMR S 968, Institut de la Vision, Paris, F-75012, France, CNRS, UMR 7210, Paris, F-75012, France,

Photoreceptor degeneration in age-related macular degeneration (AMD) is associated with an infiltration and chronic accumulation of mononuclear phagocytes (MPs). We have previously shown that Cx3cr1-deficient mice develop age- and stress- related subretinal accumulation of MPs, which is associated with photoreceptor degeneration. Cx3cr1-deficient MPs have been shown to increase neuronal apoptosis through IL-1β in neuroinflammation of the brain. The reason for increased IL-1β secretion from Cx3cr1-deficient MPs, and whether IL-1β is responsible for increased photoreceptor apoptosis in Cx3cr1-deficient mice, has not been elucidated. Here we show that Cx3cr1-deficient MPs express increased surface P2X7 receptor (P2RX7), which stimulates IL-1β maturation and secretion. P2RX7 and IL-1β inhibition efficiently blunted Cx3cr1-MP-dependent photoreceptor apoptosis in a monocyte/retina coculture system and in light-induced subretinal inflammation of Cx3cr1-deficient mice in vivo. Our results provide an explanation for increased CX3CR1-dependent IL-1β secretion and suggest that IL-1β or P2RX7 inhibition can help inhibit the inflammation-associated photoreceptor cell loss in late AMD, including geographic atrophy, for which no efficient treatment currently exists.
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http://dx.doi.org/10.1523/JNEUROSCI.3955-14.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6605270PMC
May 2015

Dystrophin Dp71 gene deletion induces retinal vascular inflammation and capillary degeneration.

Hum Mol Genet 2015 Jul 21;24(14):3939-47. Epub 2015 Apr 21.

Institut de la Vision/INSERM/UPMC, Univ Paris 06/CNRS/CHNO des Quinze-Vingts, Paris, France, Ophthalmology Department, Hôpital Lariboisière (AP-HP) 2, Université Paris 7, Sorbonne Paris Cité, rue Ambroise Paré, 75010 Paris, France

We have previously shown that the deletion of the dystrophin Dp71 gene induces a highly permeable blood-retinal barrier (BRB). Given that BRB breakdown is involved in retinal inflammation and the pathophysiology of many blinding eye diseases, here we investigated whether the absence of Dp71 brings out retinal vascular inflammation and vessel loss by using specific Dp71-null mice. The expression of vascular endothelial growth factor (VEGF), quantified by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay methods, was higher in the retina of Dp71-null mice than in wild-type mice. In contrast, no differences were observed in VEGFR-2 and tumor necrosis factor-α expression. Moreover, mRNA expression of water channel, aquaporin 4 (AQP4) was increased after Dp71 deletion. The Dp71 deletion was also associated with the overexpression of intercellular adhesion molecule 1, which is expressed on endothelial cells surface to recruit leukocytes. Consistent with these findings, the total number of adherent leukocytes per retina, assessed after perfusion with fluorescein isothiocyanate-conjugated concanavalin A, was increased in the absence of Dp71. Finally, a significant increase in capillary degeneration quantified after retinal trypsin digestion was observed in mice lacking Dp71. These data illustrate for the first time that the deletion of Dp71 was associated with retinal vascular inflammation, vascular lesions with increased leukocyte adhesion and capillary degeneration. Thus, dystrophin Dp71 could play a critical role in retinal vascular inflammation disease, and therefore represent a potential therapeutic target.
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http://dx.doi.org/10.1093/hmg/ddv132DOI Listing
July 2015

Apolipoprotein E promotes subretinal mononuclear phagocyte survival and chronic inflammation in age-related macular degeneration.

EMBO Mol Med 2015 Feb;7(2):211-26

INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France

Physiologically, the retinal pigment epithelium (RPE) expresses immunosuppressive signals such as FAS ligand (FASL), which prevents the accumulation of leukocytes in the subretinal space. Age-related macular degeneration (AMD) is associated with a breakdown of the subretinal immunosuppressive environment and chronic accumulation of mononuclear phagocytes (MPs). We show that subretinal MPs in AMD patients accumulate on the RPE and express high levels of APOE. MPs of Cx3cr1(-/-) mice that develop MP accumulation on the RPE, photoreceptor degeneration, and increased choroidal neovascularization similarly express high levels of APOE. ApoE deletion in Cx3cr1(-/-) mice prevents pathogenic age- and stress-induced subretinal MP accumulation. We demonstrate that increased APOE levels induce IL-6 in MPs via the activation of the TLR2-CD14-dependent innate immunity receptor cluster. IL-6 in turn represses RPE FasL expression and prolongs subretinal MP survival. This mechanism may account, in part, for the MP accumulation observed in Cx3cr1(-/-) mice. Our results underline the inflammatory role of APOE in sterile inflammation in the immunosuppressive subretinal space. They provide rationale for the implication of IL-6 in AMD and open avenues toward therapies inhibiting pathogenic chronic inflammation in late AMD.
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http://dx.doi.org/10.15252/emmm.201404524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4328649PMC
February 2015