Background: Ischemic heart disease is a leading cause of heart failure and despite advanced therapeutic options, morbidity and mortality rates remain high. Although acute inflammation in response to myocardial cell death has been extensively studied, subsequent adaptive immune activity and anti-heart autoimmunity may also contribute to the development of HF. After ischemic injury to the myocardium, dendritic cells (DC) respond to cardiomyocyte necrosis, present cardiac antigen to T cells and potentially initiate a persistent autoimmune response against the heart. Cross-priming DC have the ability to activate both CD4+ helper and CD8 + cytotoxic T cells in response to necrotic cells and may thus be crucial players in exacerbating autoimmunity targeting the heart. This study investigates a role for cross-priming DC in post-MI myocardial impairment through presentation of self-antigen from necrotic cardiomyocytes to cytotoxic CD8 + T cells. Methods: We induced type-2 myocardial infarction (MI)-like ischemic injury in the heart by treatment with a single high dose of the beta-adrenergic agonist isoproterenol. We characterized the DC population in the heart and mediastinal lymph nodes and analyzed long-term cardiac immunopathology and functional decline in wild type and Clec9a -depleted mice lacking DC cross-priming function. Results: A diverse DC population, including cross-priming DC, is present in the heart and activated after ischemic injury. Clec9a -/- mice deficient in DC cross-priming are protected from long-term immune-mediated myocardial damage and decline of cardiac function, likely due to dampened activation of cytotoxic CD8 + T cells. Conclusions: Activation of cytotoxic CD8 + T cells by cross-priming DC contributes to exacerbation of post-ischemic inflammatory damage of the myocardium and corresponding decline in cardiac function. Importantly, this provides novel therapeutic targets to prevent immune-mediated worsening of post-ischemic HF.
Systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) show significant heart involvement and cardiovascular morbidity, which can be due to systemically increased levels of inflammation or direct autoreactivity targeting cardiac tissue. Despite high clinical relevance, cardiac damage secondary to systemic autoimmunity lacks inducible rodent models. Here, we characterise immune-mediated cardiac tissue damage in a new model of SLE induced by topical application of the Toll-like receptor 7/8 (TLR7/8) agonist Resiquimod. We observe a cardiac phenotype reminiscent of autoimmune-mediated dilated cardiomyopathy, and identify auto-antibodies as major contributors to cardiac tissue damage. Resiquimod-induced heart disease is a highly relevant mouse model for mechanistic and therapeutic studies aiming to protect the heart during autoimmunity.
Combination therapy targeting glycolysis and specific RAD51 function shows increased efficacy as compared to standard of care treatments in leukemias.
Activation-Induced Cytidine Deaminase (AID) mutates and modifies the IgH locus. However, it also initiates double-strand breaks (DSBs) throughout the genome. This effect of AID is balanced by RAD51-dependent homologous recombination repair. Importantly, we previously showed that inhibition of RAD51 function by a small-molecule inhibitor leads to cell death of AID-positive neoplastic cells. While we have used AID-RAD51 imbalance as a potential chemotherapy approach, the efficacy of current RAD51 inhibitors can be further improved. Studies have shown a relationship between glycolysis and RAD51 function, and therefore targeting the glycolytic pathway is a viable strategy to enhance RAD51 inhibitor efficacy. Here we show that glycolytic inhibitor 2DG and RAD51 inhibitor DIDS act synergistically to reduce B-lymphocyte human chronic lymphocytic leukemia proliferation ex vivo, and mice xenografted with this cell line showed significant reduction in the tumor burden in the presence of both 2DG and DIDS. These data suggest that the glycolytic pathway and DNA repair can be simultaneously targeted to produce better chemotherapies against B-lymphoid cancers. Citation Format: Muneer G. Hasham, Kin-hoe Chow, John Wilson, Nathan LaBrie, Bryant Perkins, Jane Branca, Thomas Sproule, Derry Roopenian. Targeting glycolysis and RAD51-dependent repair in B-lymphoid cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A115.
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