C3- and CR3-dependent microglial clearance protects photoreceptors in retinitis pigmentosa

Complement activation has been implicated as contributing to neurodegeneration in retinal and brain pathologies, but its role in retinitis pigmentosa (RP), an inherited and largely incurable photoreceptor degenerative disease, is unclear. We found that multiple complement components were markedly up-regulated in retinas with human RP and the rd10 mouse model, coinciding spatiotemporally with photoreceptor degeneration, with increased C3 expression and activation localizing to activated retinal microglia. Genetic ablation of C3 accelerated structural and functional photoreceptor degeneration and altered retinal inflammatory gene expression. These phenotypes were recapitulated by genetic deletion of CR3, a microglia-expressed receptor for the C3 activation product iC3b, implicating C3-CR3 signaling as a regulator of microglia–photoreceptor interactions. Deficiency of C3 or CR3 decreased microglial phagocytosis of apoptotic photoreceptors and increased microglial neurotoxicity to photoreceptors, demonstrating a novel adaptive role for complement-mediated microglial clearance of apoptotic photoreceptors in RP. These homeostatic neuroinflammatory mechanisms are relevant to the design and interpretation of immunomodulatory therapeutic approaches to retinal degenerative disease.

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Complement C3- and CR3-dependent microglial clearance protects photoreceptors in retinitis pigmentosa

10.1101/504647 ◽

2018 ◽

Author(s):

Sean M. Silverman ◽

Wenxin Ma ◽

Xu Wang ◽

Lian Zhao ◽

Wai T. Wong

Keyword(s):

Retinitis Pigmentosa ◽

Complement Activation ◽

Complement C3 ◽

Photoreceptor Degeneration ◽

Therapeutic Approaches ◽

Complement Components ◽

Genetic Ablation ◽

Microglial Phagocytosis

AbstractComplement activation has been implicated as an inflammatory driver of neurodegeneration in retinal and brain pathologies. However, its involvement and influence of photoreceptor degeneration in retinitis pigmentosa (RP), an inherited, largely incurable blinding disease, is unclear. We discover that markedly upregulated retinal expression of multiple complement components coincided spatiotemporally with photoreceptor degeneration in both the rd10 mouse model and in human specimens of RP, with increased complement C3 expression and activation localizing to infiltrating microglia near photoreceptors. Genetic ablation of C3 in the rd10 background resulted in accelerated structural and functional photoreceptor degeneration and altered retinal expression of inflammatory genes. These effects were phenocopied by the genetic deletion of CR3, a microglia-expressed receptor for the C3 activation product C3b, implicating an adaptive microglial-mediation mechanism involving C3-CR3 interaction. Deficiency of either C3 or CR3 resulted in deficient microglial phagocytosis of apoptotic photoreceptors in vivo, as well as increased microglial neurotoxicity to photoreceptors in vitro. These findings demonstrate a novel adaptive role for complement activation in RP that facilitates microglial clearance of apoptotic photoreceptors, without which increased proinflammatory microglial neurotoxicity ensues. These positive contributions of complement via microglial-mediated mechanisms are important in the design of immunomodulatory therapeutic approaches to neurodegeneration.One Sentence SummaryComplement activation mediates adaptive neuroprotection for photoreceptors by facilitating C3-CR3 dependent microglial clearance of apoptotic cells.

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Microglial phagocytosis and activation underlying photoreceptor degeneration is regulated by CX3CL1‐CX3CR1 signaling in a mouse model of retinitis pigmentosa

Glia ◽

10.1002/glia.23016 ◽

2016 ◽

Vol 64 (9) ◽

pp. 1479-1491 ◽

Cited By ~ 63

Author(s):

Matthew K. Zabel ◽

Lian Zhao ◽

Yikui Zhang ◽

Shaimar R. Gonzalez ◽

Wenxin Ma ◽

...

Keyword(s):

Mouse Model ◽

Retinitis Pigmentosa ◽

Photoreceptor Degeneration ◽

Microglial Phagocytosis

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The cGMP-Dependent Protein Kinase 2 Contributes to Cone Photoreceptor Degeneration in the Cnga3-Deficient Mouse Model of Achromatopsia

International Journal of Molecular Sciences ◽

10.3390/ijms22010052 ◽

2020 ◽

Vol 22 (1) ◽

pp. 52

Author(s):

Mirja Koch ◽

Constanze Scheel ◽

Hongwei Ma ◽

Fan Yang ◽

Michael Stadlmeier ◽

...

Keyword(s):

Protein Kinase ◽

Mouse Model ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Cone Photoreceptor ◽

Photoreceptor Degeneration ◽

Dependent Protein Kinase ◽

Genetic Ablation ◽

Cgmp Dependent Protein Kinase ◽

Dependent Protein

Mutations in the CNGA3 gene, which encodes the A subunit of the cyclic guanosine monophosphate (cGMP)-gated cation channel in cone photoreceptor outer segments, cause total colour blindness, also referred to as achromatopsia. Cones lacking this channel protein are non-functional, accumulate high levels of the second messenger cGMP and degenerate over time after induction of ER stress. The cell death mechanisms that lead to loss of affected cones are only partially understood. Here, we explored the disease mechanisms in the Cnga3 knockout (KO) mouse model of achromatopsia. We found that another important effector of cGMP, the cGMP-dependent protein kinase 2 (Prkg2) is crucially involved in cGMP cytotoxicity of cones in Cnga3 KO mice. Virus-mediated knockdown or genetic ablation of Prkg2 in Cnga3 KO mice counteracted degeneration and preserved the number of cones. Analysis of markers of endoplasmic reticulum stress and unfolded protein response confirmed that induction of these processes in Cnga3 KO cones also depends on Prkg2. In conclusion, we identified Prkg2 as a novel key mediator of cone photoreceptor degeneration in achromatopsia. Our data suggest that this cGMP mediator could be a novel pharmacological target for future neuroprotective therapies.

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History of IgA Nephropathy Mouse Models

Journal of Clinical Medicine ◽

10.3390/jcm10143142 ◽

2021 ◽

Vol 10 (14) ◽

pp. 3142

Author(s):

Batoul Wehbi ◽

Virginie Pascal ◽

Lina Zawil ◽

Michel Cogné ◽

Jean-Claude Aldigier

Keyword(s):

Iga Nephropathy ◽

Small Animal ◽

Experimental Models ◽

Murine Models ◽

Therapeutic Approaches ◽

Complement Components ◽

Simple Description ◽

Primary Glomerulonephritis ◽

History Of ◽

Small Animal Models

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world. It was first described in 1968 by Jean Berger and Nicole Hinglais as the presence of intercapillary deposits of IgA. Despite this simple description, patients with IgAN may present very broad clinical features ranging from the isolated presence of IgA in the mesangium without clinical or biological manifestations to rapidly progressive kidney failure. These features are associated with a variety of histological lesions, from the discrete thickening of the mesangial matrix to diffuse cell proliferation. Immunofluorescence on IgAN kidney specimens shows the isolated presence of IgA or its inconsistent association with IgG and complement components. This clinical heterogeneity of IgAN clearly echoes its complex and multifactorial pathophysiology in humans, inviting further analyses of its various aspects through the use of experimental models. Small-animal models of IgAN provide the most pertinent strategies for studying the multifactorial aspects of IgAN pathogenesis and progression. Although only primates have the IgA1 subclass, several murine models have been developed in which various aspects of immune responses are deregulated and which are useful in the understanding of IgAN physiopathology as well as in the assessment of IgAN therapeutic approaches. In this manuscript, we review all murine IgAN models developed since 1968 and discuss their remarkable contribution to understanding the disease.

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A multi-stem cell basis for craniosynostosis and calvarial mineralization

10.21203/rs.3.rs-1061838/v1 ◽

2021 ◽

Author(s):

Matthew Greenblatt ◽

Seoyeon Bok ◽

Alisha Yallowitz ◽

Jason McCormick ◽

Michelle Cung ◽

...

Keyword(s):

Stem Cell ◽

Endochondral Ossification ◽

Distinct Form ◽

Therapeutic Approaches ◽

Genetic Ablation ◽

Cell Lineages ◽

Specific Fraction ◽

Maladaptive Response ◽

Suture Fusion ◽

Stem Cell Populations

Abstract Craniosynostosis is a group of disorders of premature calvarial sutural fusion. An incomplete understanding of the calvarial stem cells (CSCs) that produce fusion-driving osteoblasts has limited the development of non-surgical therapeutic approaches for craniosynostosis. Here we show that both physiologic calvarial mineralization and pathologic calvarial fusion in craniosynostosis reflect the interaction of two separate stem cell lineages; a recently reported CathepsinK (CTSK) lineage CSC (CTSK+ CSC)1 and a separate Discoidin domain-containing receptor 2 (DDR2) lineage stem cell (DDR2+ CSC) identified in this study. Deletion of Twist1, a gene associated with human craniosynostosis2,3, solely in CTSK+ CSCs is sufficient to drive craniosynostosis, however the sites destined to fuse surprisingly display a marked depletion of CTSK+ CSCs and a corresponding expansion of DDR2+ CSCs. This DDR2+ CSC expansion is a direct maladaptive response to CTSK+ CSC depletion, as partial suture fusion occurred after genetic ablation of CTSK+ CSCs. This DDR2+ CSC is a specific fraction of DDR2+ lineage cells that displayed full stemness features, establishing the presence of two distinct stem cell lineages in the sutures, with each population contributing to physiologic calvarial mineralization. DDR2+ CSCs mediate a distinct form of endochondral ossification where an initial cartilage template is formed but the recruitment of hematopoietic marrow is absent. Direct implantation of DDR2+ CSCs into suture sites was sufficient to induce fusion, and this phenotype was prevented by co-transplantation of CTSK+ CSCs. Lastly, the human counterparts of DDR2+ CSCs and CTSK+ CSCs are present in calvarial surgical specimens and display conserved functional properties in xenograft assays. The interaction between these two stem cell populations provides a new biologic interface to modulate calvarial mineralization and suture patency.

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Dynamic in vivo quantification of rod photoreceptor degeneration using fluorescent reporter mouse models of retinitis pigmentosa

Experimental Eye Research ◽

10.1016/j.exer.2019.107895 ◽

2020 ◽

Vol 190 ◽

pp. 107895 ◽

Cited By ~ 2

Author(s):

Harry O. Orlans ◽

Alun R. Barnard ◽

Robert E. MacLaren

Keyword(s):

Retinitis Pigmentosa ◽

Mouse Models ◽

Rod Photoreceptor ◽

Photoreceptor Degeneration ◽

Fluorescent Reporter ◽

Reporter Mouse

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Fyn-tau Ablation Modifies PTZ-Induced Seizures and Post-seizure Hallmarks of Early Epileptogenesis

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2020.592374 ◽

2020 ◽

Vol 14 ◽

Author(s):

Marson Putra ◽

Sreekanth Puttachary ◽

Guanghao Liu ◽

Gloria Lee ◽

Thimmasettappa Thippeswamy

Keyword(s):

Double Knockout ◽

Neuroprotective Effects ◽

Western Blots ◽

Seizure Reduction ◽

Genetic Ablation ◽

Genetic Deletion ◽

Convulsive Seizures ◽

Epilepsy Models ◽

Inwardly Rectifying

Both Fyn and tau have been associated with neuronal hyperexcitability and neurotoxicity in many tauopathies, including Alzheimer's disease (AD). Individual genetic ablation of fyn or tau appears to be protective against aberrant excitatory neuronal activities in AD and epilepsy models. It is, however, still unknown whether ablation of both Fyn and tau can likely elicit more profound anti-seizure and neuroprotective effects. Here, we show the effects of genetic deletion of Fyn and/or tau on seizure severity in response to pentylenetetrazole (PTZ)-induced seizure in mouse models and neurobiological changes 24 h post-seizures. We used Fyn KO (fyn−/−), tau KO (tau−/−), double knockout (DKO) (fyn−/−/tau−/−), and wild-type (WT) mice of the same genetic background. Both tau KO and DKO showed a significant increase in latency to convulsive seizures and significantly decreased the severity of seizures post-PTZ. Although Fyn KO did not differ significantly from WT, in response to PTZ, Fyn KO still had 36 ± 8% seizure reduction and a 30% increase in seizure latency compared to WT. Surprisingly, in contrast to WT, Fyn KO mice showed higher mortality in <20 min of seizure induction; these mice had severe hydrocephalous. None of the tau−/− and DKO died during the study. In response to PTZ, all KO groups showed a significant reduction in neurodegeneration and gliosis, in contrast to WT, which showed increased neurodegeneration [especially, parvalbumin (PV)-GABAergic interneurons] and gliosis. DKO mice had the most reduced gliosis. Immunohistochemically, phospho-tau (AT8, pS199/S202), Fyn expression, as well as Fyn-tau interaction as measured by PLA increased in WT post-PTZ. Moreover, hippocampal Western blots revealed increased levels of AT8, tyrosine phospho-tau (pY18), and phosphorylated Src tyrosine family kinases (pSFK) in PTZ-treated WT, but not in KO, compared to respective controls. Furthermore, PV interneurons were protected from PTZ-induced seizure effects in all KO mice. The levels of inwardly rectifying potassium (Kir 4.1) channels were also downregulated in astrocytes in the WT post-PTZ, while its levels did not change in KO groups. Overall, our results demonstrated the role of Fyn and tau in seizures and their impact on the mediators of early epileptogenesis in PTZ model.

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Genome Editing as a Treatment for the Most Prevalent Causative Genes of Autosomal Dominant Retinitis Pigmentosa

International Journal of Molecular Sciences ◽

10.3390/ijms20102542 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2542 ◽

Cited By ~ 9

Author(s):

Michalitsa Diakatou ◽

Gaël Manes ◽

Beatrice Bocquet ◽

Isabelle Meunier ◽

Vasiliki Kalatzis

Keyword(s):

Retinitis Pigmentosa ◽

Genome Editing ◽

Mutant Allele ◽

Autosomal Dominant ◽

Dominant Negative ◽

Therapeutic Approaches ◽

Autosomal Dominant Retinitis Pigmentosa ◽

Inherited Retinal Dystrophies ◽

Retinal Dystrophies ◽

Type Gene

Inherited retinal dystrophies (IRDs) are a clinically and genetically heterogeneous group of diseases with more than 250 causative genes. The most common form is retinitis pigmentosa. IRDs lead to vision impairment for which there is no universal cure. Encouragingly, a first gene supplementation therapy has been approved for an autosomal recessive IRD. However, for autosomal dominant IRDs, gene supplementation therapy is not always pertinent because haploinsufficiency is not the only cause. Disease-causing mechanisms are often gain-of-function or dominant-negative, which usually require alternative therapeutic approaches. In such cases, genome-editing technology has raised hopes for treatment. Genome editing could be used to (i) invalidate both alleles, followed by supplementation of the wild type gene, (ii) specifically invalidate the mutant allele, with or without gene supplementation, or (iii) to correct the mutant allele. We review here the most prevalent genes causing autosomal dominant retinitis pigmentosa and the most appropriate genome-editing strategy that could be used to target their different causative mutations.

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