Programmed necrosis, not apoptosis, is a key mediator of cell loss and DAMP-mediated inflammation in dsRNA-induced retinal degeneration

Cell Death Differ. 2014 Feb;21(2):270-7. doi: 10.1038/cdd.2013.109. Epub 2013 Aug 16.

Abstract

There is no known treatment for the dry form of an age-related macular degeneration (AMD). Cell death and inflammation are important biological processes thought to have central role in AMD. Here we show that receptor-interacting protein (RIP) kinase mediates necrosis and enhances inflammation in a mouse model of retinal degeneration induced by dsRNA, a component of drusen in AMD. In contrast to photoreceptor-induced apoptosis, subretinal injection of the dsRNA analog poly(I : C) caused necrosis of the retinal pigment epithelium (RPE), as well as macrophage infiltration into the outer retinas. In Rip3(-/-) mice, both necrosis and inflammation were prevented, providing substantial protection against poly(I : C)-induced retinal degeneration. Moreover, after poly(I : C) injection, Rip3(-/-) mice displayed decreased levels of pro-inflammatory cytokines (such as TNF-α and IL-6) in the retina, and attenuated intravitreal release of high-mobility group box-1 (HMGB1), a major damage-associated molecular pattern (DAMP). In vitro, poly(I : C)-induced necrosis were inhibited in Rip3-deficient RPE cells, which in turn suppressed HMGB1 release and dampened TNF-α and IL-6 induction evoked by necrotic supernatants. On the other hand, Rip3 deficiency did not modulate directly TNF-α and IL-6 production after poly(I : C) stimulation in RPE cells or macrophages. Therefore, programmed necrosis is crucial in dsRNA-induced retinal degeneration and may promote inflammation by regulating the release of intracellular DAMPs, suggesting novel therapeutic targets for diseases such as AMD.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Cell Death / drug effects
  • Cell Survival / drug effects
  • Cells, Cultured
  • Inflammation / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Necrosis / metabolism*
  • Poly I-C / pharmacology*
  • RNA, Double-Stranded / pharmacology*
  • Receptor-Interacting Protein Serine-Threonine Kinases / deficiency
  • Receptor-Interacting Protein Serine-Threonine Kinases / metabolism
  • Receptors, Pattern Recognition / drug effects
  • Receptors, Pattern Recognition / metabolism*
  • Retinal Pigment Epithelium / drug effects*
  • Retinal Pigment Epithelium / metabolism*
  • Retinal Pigment Epithelium / pathology

Substances

  • RNA, Double-Stranded
  • Receptors, Pattern Recognition
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk3 protein, mouse
  • Poly I-C