title: Deletion of FADD in macrophages and granulocytes results in RIP3- and MyD88-dependent systemic inflammation.
abstract: Myeloid cells, which include monocytes, macrophages, and granulocytes, are important innate immune cells, but the mechanism and downstream effect of their cell death on the immune system is not completely clear. Necroptosis is an alternate form of cell death that can be triggered when death receptor-mediated apoptosis is blocked, for example, in stimulated Fas-associated Death Domain (FADD) deficient cells. We report here that mice deficient for FADD in myeloid cells (mFADD-/-) exhibit systemic inflammation with elevated inflammatory cytokines and increased levels of myeloid and B cell populations while their dendritic and T cell numbers are normal. These phenotypes were abolished when RIP3 deficiency was introduced, suggesting that systemic inflammation is caused by RIP3-dependent necroptotic and/or inflammatory activity. We further found that loss of MyD88 can rescue the systemic inflammation observed in these mice. These phenotypes are surprisingly similar to that of dendritic cell (DC)-specific FADD deficient mice with the exception that DC numbers are normal in mFADD-/- mice. Together these data support the notion that innate immune cells are constantly being stimulated through the MyD88-dependent pathway and aberrations in their cell death machinery can result in systemic effects on the immune system.
authors: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, California, United States of America.
authors: Suruchi N
authors: SN
authors: Schock
authors: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, California, United States of America.
authors: Jennifer A
authors: JA
authors: Young
authors: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, California, United States of America.
authors: Tina H
authors: TH
authors: He
authors: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, California, United States of America.
authors: Yuefang
authors: Y
authors: Sun
authors: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, California, United States of America.
authors: Astar
authors: A
authors: Winoto
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D003713:Dendritic Cells / Q000378:metabolism / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D053200:Fas-Associated Death Domain Protein / Q000502:physiology*; D005260:Female; D006098:Granulocytes / Q000378:metabolism / Q000473:pathology*; D007249:Inflammation / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D019426:Integrases / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D053594:Myeloid Differentiation Factor 88 / Q000502:physiology*; D009336:Necrosis; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology
chemical_list: C505534:Fadd protein, mouse; D053200:Fas-Associated Death Domain Protein; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse; C045073:Cre recombinase; D019426:Integrases