Evidence for multiple cell death pathways during development of experimental cytomegalovirus retinitis in mice with retrovirus-induced immunosuppression: apoptosis, necroptosis, and pyroptosis

J Virol. 2012 Oct;86(20):10961-78. doi: 10.1128/JVI.01275-12. Epub 2012 Jul 25.

Abstract

AIDS-related human cytomegalovirus (HCMV) retinitis remains a major ophthalmologic problem worldwide. Although this sight-threatening disease is well characterized clinically, many pathogenic issues remain unresolved, among them a basic understanding of the relative roles of cell death pathways during development of retinal tissue destruction. Using an established model of experimental murine cytomegalovirus (MCMV) retinitis in mice with retrovirus-induced immunosuppression (MAIDS), we initially investigated MCMV-infected eyes for evidence of apoptosis-associated molecules in mice with MAIDS of 4 weeks' (MAIDS-4) and 10 weeks' (MAIDS-10) duration, which were resistant and susceptible to retinal disease, respectively, but which harbored equivalent amounts of infectious MCMV. Whereas MCMV-infected eyes of MAIDS-4 mice showed little evidence of apoptosis-associated molecules, MCMV-infected eyes of MAIDS-10 mice showed significant amounts of tumor necrosis factor alpha (TNF-α), TNF receptors 1 and 2, active caspase 8, active caspase 3, TNF-related apoptosis-inducing ligand (TRAIL), TRAIL-R(DR5), Fas, and Fas ligand mRNAs and/or proteins, all detected at peak amounts prior to development of most severe retinal disease. Immunohistochemical staining showed macrophages, granulocytes (neutrophils), Müller cells, and microglial cells as TNF-α sources. Remarkably, quantification of apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assay suggested that apoptosis contributed minimally to retinal disease in MCMV-infected eyes of MAIDS-10 mice. Subsequent studies demonstrated that MCMV-infected eyes of MAIDS-10 mice, but not MAIDS-4 mice, showed evidence of significant increases in molecules associated with two additional cell death pathways, necroptosis (receptor-interacting protein 1 [RIP1] and RIP3 mRNAs) and pyroptosis (caspase 1, interleukin 1β [IL-1β], and IL-18 mRNAs). We conclude that apoptosis, necroptosis, and pyroptosis participate simultaneously during MAIDS-related MCMV retinitis, and all may play a role during AIDS-related HCMV retinitis.

Publication types

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

MeSH terms

  • Animals
  • Apoptosis*
  • Caspase 1 / biosynthesis
  • Caspase 3 / biosynthesis
  • Caspase 8 / biosynthesis
  • Cytomegalovirus Retinitis / complications
  • Cytomegalovirus Retinitis / immunology
  • Cytomegalovirus Retinitis / pathology*
  • Fas Ligand Protein / biosynthesis
  • Fas Ligand Protein / genetics
  • Female
  • Granulocytes / metabolism
  • Interleukin-18 / biosynthesis
  • Interleukin-18 / genetics
  • Interleukin-1beta / biosynthesis
  • Interleukin-1beta / genetics
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microglia / metabolism
  • Murine Acquired Immunodeficiency Syndrome / complications
  • Murine Acquired Immunodeficiency Syndrome / pathology*
  • Murine Acquired Immunodeficiency Syndrome / virology
  • Muromegalovirus
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinases / biosynthesis
  • Receptors, Tumor Necrosis Factor / biosynthesis
  • Retina / pathology
  • Retina / virology
  • TNF-Related Apoptosis-Inducing Ligand / biosynthesis
  • Tumor Necrosis Factor-alpha / biosynthesis

Substances

  • Fas Ligand Protein
  • Interleukin-18
  • Interleukin-1beta
  • RNA, Messenger
  • Receptors, Tumor Necrosis Factor
  • TNF-Related Apoptosis-Inducing Ligand
  • Tnfsf10 protein, mouse
  • Tumor Necrosis Factor-alpha
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Caspase 3
  • Caspase 8
  • Caspase 1