title: Chronic inflammatory cardiomyopathy of interferon γ-overexpressing transgenic mice is mediated by tumor necrosis factor-α.
abstract: We recently described a model of inflammatory cardiomyopathy in interferon (IFN)-γ overexpressing transgenic mice stably circulating IFN-γ in the serum referred to as SAP--IFN-γ mice. SAP-IFN-γ transgenic mice show cardiac infiltration by mononuclear leukocytes, culminating in dilated cardiomyopathy characterized by an increase of left ventricular end diastolic diameter and reduction of fractional shortening. We hypothesized that the pathological mechanism underlying SAP-IFN-γ cardiomyopathy might be mediated by (auto)immune processes or tumor necrosis factor (TNF)-α synthesis from IFN-γ-activated macrophages. To verify these hypotheses, we crossed SAP-IFN-γ transgenic mice with immunodeficient Rag1(-/-) or TNF-α(-/-) knockout mice and analyzed the cardiac phenotype of the resulting double-mutant offspring. Immunodeficient Rag1(-/-) SAP-IFN-γ mice had a decreased impaired life span and intensive cardiac inflammatory reactions, showing that the cardiotoxic IFN-γ effect operative in SAP-IFN-γ mice was not mediated by an adaptive immune mechanism. SAP-IFN-γ TNF-α(-/-) hearts showed virtually no histopathological alterations, a significant reduction of cardiac infiltration by CD11c(+) dendritic cells and F4/80(+) macrophages, almost complete normalization of cardiac troponin T levels in serum and of left ventricular end diastolic diameter and fractional shortening, and a dramatic increase of life span, compared with SAP-IFN-γ transgenic controls. Thus, myocarditis and cardiomyopathy developing in IFN-γ-overexpressing transgenic mice is, to a significant degree, mediated by TNF-α. TNF-α-mediated cardiotoxicity in SAP-IFN-γ transgenic mice is independent of changes of apoptosis.
authors: Department of Laboratory Medicine, Robert Bosch-Hospital, Stuttgart, Germany.
authors: Michael
authors: M
authors: Torzewski
authors: Philip
authors: P
authors: Wenzel
authors: Hartmut
authors: H
authors: Kleinert
authors: Christoph
authors: C
authors: Becker
authors: Jasmin
authors: J
authors: El-Masri
authors: Elena
authors: E
authors: Wiese
authors: Moritz
authors: M
authors: Brandt
authors: Andrea
authors: A
authors: Pautz
authors: Laura
authors: L
authors: Twardowski
authors: Edgar
authors: E
authors: Schmitt
authors: Thomas
authors: T
authors: Münzel
authors: Kurt
authors: K
authors: Reifenberg
mesh_terms: D056704:Adaptive Immunity / Q000502:physiology*; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000276:immunology; D015551:Autoimmunity / Q000502:physiology; D002908:Chronic Disease; D016207:Cytokines / Q000378:metabolism; D004452:Echocardiography; D005260:Female; D020868:Gene Silencing / Q000502:physiology; D006505:Hepatitis / Q000276:immunology; D007371:Interferon-gamma / Q000378:metabolism*; D053208:Kaplan-Meier Estimate; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009205:Myocarditis / Q000276:immunology*; D010641:Phenotype; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000502:physiology*
chemical_list: D016207:Cytokines; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D000410:Alanine Transaminase