Mariella Bockstahler1, Andrea Fischer1, Ziya Kaya1,2, Antje Beling3,4, Carl Christoph Goetzke3,4, Hannah Louise Neumaier3, Martina Sauter5, Meike Kespohl3,4, Anna-Maria Müller1, Christin Meckes1, Christian Salbach1, Mirjam Schenk6, Arnd Heuser7, Ulf Landmesser8,4, January Weiner9, Benjamin Meder1,2, Lorenz Lehmann1,2,10, Adelheid Kratzer8,4, Karin Klingel5, Hugo A Katus1,2. 1. Medizinische Klinik für Innere Medizin III: Kardiologie, Angiologie und Pneumologie, Universitätsklinikum Heidelberg, Germany (M.B., A.F., A.-M.M., C.M., C.S., B.M., L.L., H.A.K., Z.K.). 2. Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), partner side Heidelberg/Mannheim, Heidelberg, Germany (B.M., L.L., H.A.K., Z.K.). 3. Institute of Biochemistry (C.C.G., H.L.N., M.K., A.B.), Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health (BIH), Germany. 4. Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), partner side Berlin, Germany (C.C.G., M.K., U.L., A.K., A.B.). 5. Cardiopathology, Institute for Pathology and Neuropathology, University Hospital Tübingen, Germany (M.S., K.K.). 6. Institute of Pathology, University of Bern, Switzerland (M.S.). 7. Core Unit Pathophysiology (A.H.), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany. 8. Medizinische Klinik für Kardiologie Campus Benjamin Franklin (U.L., A.K.), Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health (BIH), Germany. 9. Core Unit Bioinformatics (J.W.), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany. 10. Cardio-Oncology Unit, University Hospital of Heidelberg and German Cancer Research Center (DKFZ), Heidelberg, Germany (L.L.).
Abstract
BACKGROUND: Immune checkpoint inhibitor (ICI) therapy is often accompanied by immune-related pathology, with an increasing occurrence of high-risk ICI-related myocarditis. Understanding the mechanisms involved in this side effect could enable the development of management strategies. In mouse models, immune checkpoints, such as PD-1 (programmed cell death protein 1), control the threshold of self-antigen responses directed against cardiac TnI (troponin I). We aimed to identify how the immunoproteasome, the main proteolytic machinery in immune cells harboring 3 distinct protease activities in the LMP2 (low-molecular-weight protein 2), LMP7 (low-molecular-weight protein 7), and MECL1 (multicatalytic endopeptidase complex subunit 1) subunit, affects TnI-directed autoimmune pathology of the heart. METHODS: TnI-directed autoimmune myocarditis (TnI-AM), a CD4+ T-cell-mediated disease, was induced in mice lacking all 3 immunoproteasome subunits (triple-ip-/-) or lacking either the gene encoding LMP2 and LMP7 by immunization with a cardiac TnI peptide. Alternatively, before induction of TnI-AM or after establishment of autoimmune myocarditis, mice were treated with the immunoproteasome inhibitor ONX 0914. Immune parameters defining heart-specific autoimmunity were investigated in experimental TnI-AM and in 2 cases of ICI-related myocarditis. RESULTS: All immunoproteasome-deficient strains showed mitigated autoimmune-related cardiac pathology with less inflammation, lower proinflammatory and chemotactic cytokines, less interleukin-17 production, and reduced fibrosis formation. Protection from TnI-directed autoimmune heart pathology with improved cardiac function in LMP7-/- mice involved a changed balance between effector and regulatory CD4+ T cells in the spleen, with CD4+ T cells from LMP7-/- mice showing a higher expression of inhibitory PD-1 molecules. Blocked immunoproteasome proteolysis, by treatment of TLR2 (Toll-like receptor 2)-engaged and TLR7 (Toll-like receptor 7)/TLR8 (Toll-like receptor 8)-engaged CD14+ monocytes with ONX 0914, diminished proinflammatory cytokine responses, thereby reducing the boost for the expansion of self-reactive CD4+ T cells. Correspondingly, in mice, ONX 0914 treatment reversed cardiac autoimmune pathology, preventing the induction and progression of TnI-AM when self-reactive CD4+ T cells were primed. The autoimmune signature during experimental TnI-AM, with high immunoproteasome expression, immunoglobulin G deposition, interleukin-17 production in heart tissue, and TnI-directed humoral autoimmune responses, was also present in 2 cases of ICI-related myocarditis, demonstrating the activation of heart-specific autoimmune reactions by ICI therapy. CONCLUSIONS: By reversing heart-specific autoimmune responses, immunoproteasome inhibitors applied to a mouse model demonstrate their potential to aid in the management of autoimmune myocarditis in humans, possibly including patients with ICI-related heart-specific autoimmunity.
BACKGROUND: Immune checkpoint inhibitor (ICI) therapy is often accompanied by immune-related pathology, with an increasing occurrence of high-risk ICI-related myocarditis. Understanding the mechanisms involved in this side effect could enable the development of management strategies. In mouse models, immune checkpoints, such as PD-1 (programmed cell death protein 1), control the threshold of self-antigen responses directed against cardiac TnI (troponin I). We aimed to identify how the immunoproteasome, the main proteolytic machinery in immune cells harboring 3 distinct protease activities in the LMP2 (low-molecular-weight protein 2), LMP7 (low-molecular-weight protein 7), and MECL1 (multicatalytic endopeptidase complex subunit 1) subunit, affects TnI-directed autoimmune pathology of the heart. METHODS: TnI-directed autoimmune myocarditis (TnI-AM), a CD4+ T-cell-mediated disease, was induced in mice lacking all 3 immunoproteasome subunits (triple-ip-/-) or lacking either the gene encoding LMP2 and LMP7 by immunization with a cardiac TnI peptide. Alternatively, before induction of TnI-AM or after establishment of autoimmune myocarditis, mice were treated with the immunoproteasome inhibitor ONX 0914. Immune parameters defining heart-specific autoimmunity were investigated in experimental TnI-AM and in 2 cases of ICI-related myocarditis. RESULTS: All immunoproteasome-deficient strains showed mitigated autoimmune-related cardiac pathology with less inflammation, lower proinflammatory and chemotactic cytokines, less interleukin-17 production, and reduced fibrosis formation. Protection from TnI-directed autoimmune heart pathology with improved cardiac function in LMP7-/- mice involved a changed balance between effector and regulatory CD4+ T cells in the spleen, with CD4+ T cells from LMP7-/- mice showing a higher expression of inhibitory PD-1 molecules. Blocked immunoproteasome proteolysis, by treatment of TLR2 (Toll-like receptor 2)-engaged and TLR7 (Toll-like receptor 7)/TLR8 (Toll-like receptor 8)-engaged CD14+ monocytes with ONX 0914, diminished proinflammatory cytokine responses, thereby reducing the boost for the expansion of self-reactive CD4+ T cells. Correspondingly, in mice, ONX 0914 treatment reversed cardiac autoimmune pathology, preventing the induction and progression of TnI-AM when self-reactive CD4+ T cells were primed. The autoimmune signature during experimental TnI-AM, with high immunoproteasome expression, immunoglobulin G deposition, interleukin-17 production in heart tissue, and TnI-directed humoral autoimmune responses, was also present in 2 cases of ICI-related myocarditis, demonstrating the activation of heart-specific autoimmune reactions by ICI therapy. CONCLUSIONS: By reversing heart-specific autoimmune responses, immunoproteasome inhibitors applied to a mouse model demonstrate their potential to aid in the management of autoimmune myocarditis in humans, possibly including patients with ICI-related heart-specific autoimmunity.
Authors: Han Zhu; Francisco X Galdos; Daniel Lee; Sarah Waliany; Yuhsin Vivian Huang; Julia Ryan; Katherine Dang; Joel W Neal; Heather A Wakelee; Sunil A Reddy; Sandy Srinivas; Lih-Ling Lin; Ronald M Witteles; Holden T Maecker; Mark M Davis; Patricia K Nguyen; Sean M Wu Journal: Circulation Date: 2022-06-28 Impact factor: 39.918