Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in industrialized nations, affecting 30 -50 million people worldwide. The earliest clinical hallmark of AMD is the presence of drusen, extracellular deposits that accumulate beneath the retinal pigmented epithelium. Although drusen nearly always precede and increase the risk of choroidal neovascularization (CNV), the late vision-threatening stage of AMD, it is unknown whether drusen contribute to the development of CNV. Both in patients with AMD and in a recently described mouse model of AMD, early subretinal pigmented epithelium deposition of complement components C3 and C5 occurs, suggesting a contributing role for these inflammatory proteins in the development of AMD. Here we provide evidence that bioactive fragments of these complement components (C3a and C5a) are present in drusen of patients with AMD, and that C3a and C5a induce VEGF expression in vitro and in vivo. Further, we demonstrate that C3a and C5a are generated early in the course of laser-induced CNV, an accelerated model of neovascular AMD driven by VEGF and recruitment of leukocytes into the choroid. We also show that genetic ablation of receptors for C3a or C5a reduces VEGF expression, leukocyte recruitment, and CNV formation after laser injury, and that antibody-mediated neutralization of C3a or C5a or pharmacological blockade of their receptors also reduces CNV. Collectively, these findings establish a mechanistic basis for the clinical observation that drusen predispose to CNV, revealing a role for immunological phenomena in angiogenesis and providing therapeutic targets for AMD.angiogenesis ͉ inflammation ͉ injury A ge-related macular degeneration (AMD) is the leading cause of permanent vision loss among the elderly in many industrialized countries (1). The majority of vision loss due to AMD is a result of pathologic new blood vessels, termed choroidal neovascularization (CNV), invading the retina from the underlying choroid through fractures in Bruch membrane, the extracellular matrix between the choroid and the retinal pigmented epithelium (RPE). The earliest clinical hallmark of AMD is the appearance of drusen (2), localized lipoproteinaceous deposits between the RPE and Bruch membrane. Although their presence is an epidemiological risk factor for the development of CNV (3, 4), the mechanism of how, or whether, drusen provoke CNV remains undefined. Some investigators have suggested that drusen are epiphenomena, whereas others have claimed that drusen constituents act as a focal stimulus for inflammatory cells that secrete angiogenic molecules such as VEGF, and still others have suggested that drusen disturb RPE homeostasis by impairing transport across Bruch membrane (reviewed in ref. 5).Recent work has demonstrated that complement components C3 and C5 are constituents of drusen in patients with AMD (6-9). Their presence, as well as that of the membrane-attack-complex (MAC) C5b-9 and other acute-phase reactant proteins in RPE cells overlying drusen, ha...

We disrupted the fibroblast growth factor (FGF) receptor 2 (FGFR2) gene by introducing a neo cassette into the IIIc ligand binding exon and by deleting a genomic DNA fragment encoding its transmembrane domain and part of its kinase I domain. A recessive embryonic lethal mutation was obtained. Preimplantation development was normal until the blastocyst stage. Homozygous mutant embryos died a few hours after implantation at a random position in the uterine crypt, with collapsed yolk cavity. Mutant blastocysts hatched, adhered, and formed a layer of trophoblast giant cells in vitro, but after prolonged culture, the growth of the inner cell mass stopped, no visceral endoderm formed, and finally the egg cylinder disintegrated. It follows that FGFR2 is required for early postimplantation development between implantation and the formation of the egg cylinder. We suggest that FGFR2 contributes to the outgrowth, differentiation, and maintenance of the inner cell mass and raise the possibility that this activity is mediated by FGF4 signals transmitted by FGFR2. The role of early FGF signaling in pregastrulation development as a possible adaptation to mammalian (amniote) embryogenesis is discussed.

BackgroundPreventing or reducing amyloid-beta (Aβ) accumulation in the brain is an important therapeutic strategy for Alzheimer’s disease (AD). Recent studies showed that the water channel aquaporin-4 (AQP4) mediates soluble Aβ clearance from the brain parenchyma along the paravascular pathway. However the direct evidence for roles of AQP4 in the pathophysiology of AD remains absent.ResultsHere, we reported that the deletion of AQP4 exacerbated cognitive deficits of 12-moth old APP/PS1 mice, with increases in Aβ accumulation, cerebral amyloid angiopathy and loss of synaptic protein and brain-derived neurotrophic factor in the hippocampus and cortex. Furthermore, AQP4 deficiency increased atrophy of astrocytes with significant decreases in interleukin-1 beta and nonsignficant decreases in interleukin-6 and tumor necrosis factor-alpha in hippocampal and cerebral samples.ConclusionsThese results suggest that AQP4 attenuates Aβ pathogenesis despite its potentially inflammatory side-effects, thus serving as a promising target for treating AD.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-015-0056-1) contains supplementary material, which is available to authorized users.

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