title: Necrosis-Induced Sterile Inflammation Mediated by Interleukin-1α in Retinal Pigment Epithelial Cells.
abstract: Endogenous danger signals released from necrotic cells contribute to retinal inflammation. We have now investigated the effects of necrotic cell extracts prepared from ARPE-19 human retinal pigment epithelial cells (ANCE) on the release of proinflammatory cytokines and chemokines by healthy ARPE-19 cells. ANCE were prepared by subjection of ARPE-19 cells to freeze-thaw cycles. The release of various cytokines and chemokines from ARPE-19 cells was measured with a multiplex assay system or enzyme-linked immunosorbent assays. The expression of interleukin (IL)-1α and the phosphorylation and degradation of the endogenous nuclear factor-κB (NF-κB) inhibitor IκB-α were examined by immunoblot analysis. Among the various cytokines and chemokines examined, we found that ANCE markedly stimulated the release of the proinflammatory cytokine IL-6 and the chemokines IL-8 and monocyte chemoattractant protein (MCP)-1 by ARPE-19 cells. ANCE-induced IL-6, IL-8, and MCP-1 release was inhibited by IL-1 receptor antagonist and by an IKK2 inhibitor (a blocker of NF-κB signaling) in a concentration-dependent manner, but was not affected by a pan-caspase inhibitor (Z-VAD-FMK). Recombinant IL-1α also induced the secretion of IL-6, IL-8, and MCP-1 from ARPE-19 cells, and IL-1α was detected in ANCE. Furthermore, ANCE induced the phosphorylation and degradation of IκB-α in ARPE-19 cells. Our findings thus suggest that IL-1α is an important danger signal that is released from necrotic retinal pigment epithelial cells and triggers proinflammatory cytokine and chemokine secretion from intact cells in a manner dependent on NF-κB signaling. IL-1α is therefore a potential therapeutic target for amelioration of sterile inflammation in the retina.
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.|Department of Ophthalmology, First Hospital of Jilin University, Jilin, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Orita
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.
authors.forename: Koh-Hei
authors.initials: KH
authors.lastname: Sonoda
mesh_terms: D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D018836:Inflammation Mediators / Q000378:metabolism*; D053582:Interleukin-1alpha / Q000494:pharmacology*; D009336:Necrosis; D055213:Retinal Pigment Epithelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*
chemical_list: D018925:Chemokines; D017077:Culture Media, Conditioned; D016207:Cytokines; C508584:IL1A protein, human; D018836:Inflammation Mediators; D053582:Interleukin-1alpha