Detachment of photoreceptors from the retinal pigment epithelium is seen in various retinal disorders, resulting in photoreceptor death and subsequent vision loss. Cell death results in the release of endogenous molecules that activate molecular platforms containing caspase-1, termed inflammasomes. Inflammasome activation in retinal diseases has been reported in some cases to be protective and in others to be detrimental, causing neuronal cell death. Moreover, the cellular source of inflammasomes in retinal disorders is not clear. Here, we demonstrate that patients with photoreceptor injury by retinal detachment (RD) have increased levels of cleaved IL-1β, an end product of inflammasome activation. In an animal model of RD, photoreceptor cell death led to activation of endogenous inflammasomes, and this activation was diminished by Rip3 deletion. The major source of Il1b expression was found to be infiltrating macrophages in the subretinal space, rather than dying photoreceptors. Inflammasome inhibition attenuated photoreceptor death after RD. Our data implicate the infiltrating macrophages as a source of damaging inflammasomes after photoreceptor detachment in a RIP3-dependent manner and suggest a novel therapeutic target for treatment of retinal diseases.

Ocular neovascularization, including age-related macular degeneration (AMD), is a primary cause of blindness in individuals of industrialized countries. With a projected increase in the prevalence of these blinding neovascular diseases, there is an urgent need for new pharmacological interventions for their treatment or prevention. Increasing evidence has implicated eicosanoid-like metabolites of long-chain polyunsaturated fatty acids (LCPUFAs) in the regulation of neovascular disease. In particular, metabolites generated by the cytochrome P450 (CYP)-epoxygenase pathway have been shown to be potent modulators of angiogenesis, making this pathway a reasonable previously unidentified target for intervention in neovascular ocular disease. Here we show that dietary supplementation with ω-3 LCPUFAs promotes regression of choroidal neovessels in a well-characterized mouse model of neovascular AMD. Leukocyte recruitment and adhesion molecule expression in choroidal neovascular lesions were down-regulated in mice fed ω-3 LCPUFAs. The serum of these mice showed increased levels of anti-inflammatory eicosanoids derived from eicosapentaenoic acid and docosahexaenoic acid. 17,18-epoxyeicosatetraenoic acid and 19,20-epoxydocosapentaenoic acid, the major CYP-generated metabolites of these primary ω-3 LCPUFAs, were identified as key lipid mediators of disease resolution. We conclude that CYP-derived bioactive lipid metabolites from ω-3 LCPUFAs are potent inhibitors of intraocular neovascular disease and show promising therapeutic potential for resolution of neovascular AMD.choroidal neovascularization | immune cell recruitment | PPARγ | adhesion molecules | epoxy-metabolites

Matrix metalloproteinase-9 (MMP-9) plays a critical role in tissue remodeling under both physiological and pathological conditions. Although MMP-9 expression is low in most cells and is tightly controlled, the mechanism of its regulation is poorly understood. We utilized mouse embryonic fibroblasts (MEFs) that were nullizygous for the catalytic ␣ subunit of AMP-activated protein kinase (AMPK), which is a key regulator of energy homeostasis, to identify AMPK as a suppressor of MMP-9 expression. Total AMPK␣ deletion significantly elevated MMP-9 expression compared with wild-type (WT) MEFs, whereas single knock-out of the isoforms AMPK␣1 and AMPK␣2 caused minimal change in the level of MMP-9 expression. The suppressive role of AMPK on MMP-9 expression was mediated through both its activity and presence. Matrix metalloproteinase-9 (MMP-9, 2 gelatinase B) degrades denatured collagens and native collagen type IV, which is a major component of the extracellular matrix (ECM) and basement membranes (1). Under normal circumstances, the degradation of the ECM by MMP-9 is a tightly controlled process involved in physiological wound healing and embryo development (1, 2). Conversely, aberrant degradation of ECM by excess MMP-9 expression results in the pathologic destruction of connective tissue seen in cancer, arterial sclerosis, and rheumatoid arthritis (1, 3). Therefore, under physiological conditions, regulated MMP-9 expression is low (1), but the mechanisms behind this are obscure.AMP-activated protein kinase (AMPK) is a serine/threonine kinase, which regulates energy homeostasis and metabolic stress (4). AMPK acts as a sensor of cellular energy status and maintains the balance between ATP production and consumption. In mammals, AMPK exists as a heterotrimer with ␣, ␤, and ␥ subunits, each of which is encoded by two or three genes (␣1, ␣2, ␤1, ␤2, ␥1, ␥2, and ␥3). The ␣ subunit possesses catalytic activity, whereas the ␤ and ␥ subunits are regulatory and maintain the stability of the heterotrimer complex. The importance of AMPK␣ is illustrated by the fact that dual deficiency of AMPK␣1 and AMPK␣2 is embryonic lethal (5).Recent evidence suggests that AMPK has a much wider range of functions, including the regulation of cell growth, cell proliferation, cell polarity, and autophagy (6, 7). Because these functions are closely linked to the pathology of MMP-9-related diseases, including cancer, arterial sclerosis, and rheumatoid arthritis, we hypothesized that AMPK regulates MMP-9 expression. To address this, in the present study, we utilized AMPK␣-deficient mouse embryonic fibroblasts (MEFs) to investigate the effect of the genetic deletion and activation of AMPK on MMP-9 expression. EXPERIMENTAL PROCEDURESAntibodies, Recombinant Proteins, and Reagents-All antibodies, except for MMP-9 (Abcam, Cambridge, MA) and AMPK␣2 (Santa Cruz Biotechnology, Santa Cruz, CA), were purchased from Cell Signaling (Beverly, MA). Recombinant mouse TNF-␣, MMP-9, and MMP-2 proteins were obtained from R&D Systems (