Abstract P3064: Cytotoxic T-cells Drive Doxorubicin Induced Cardiac Fibrosis And Systolic Dysfunction

Abstract

Background: Doxorubicin (DR), the most commonly prescribed chemotherapy, results in dose-dependent cardiotoxicity and heart failure (HF), and patients respond less frequently to standard HF treatments. DR causes oxidative stress and myocyte death, both potent inducers of a T-cell immune response and cardiac inflammation in other causes of HF. However, mechanistic depth on the immune response elicited by DR is limited. We hypothesized that an aberrant T-cell immune response secondary to cardiac damage by DR contributes to DR-induced HF and cardiac remodeling. Methods and Results: We treated wild type (WT) and T-cell deficient ( Tcra -/- ) mice with 5.0 mg/kg DR or PBS weekly by intraperitoneal injection for 4 or 8 weeks. We found at both time points Tcra -/- mice had preserved ejection fraction (EF) by echocardiography and decreased cardiac fibrosis by picrosirius red staining, compared to WT. At 8 weeks, Tcra -/- mice had fewer TUNEL + cardiac cells than WT mice. DR treated mice had increased frequency of activated effector CD8 + CD62L lo CD44 hi cells in the cardiac draining lymph nodes, increased circulating CD8 + T-cells, and cardiac CD8 + T-cell infiltration at both time points. Histologic analysis demonstrated localization of CD8 + T-cells adjacent to cardiac fibroblasts (CFB) in the hearts of DR treated mice. Targeted antibody depletion of CD8 + but not CD4 + cells prior to 4 week DR treatment resulted in improved EF and decreased cardiac fibrosis. Moreover, cardiac CD8 + T-cells expressed higher IFNγ in vivo in DR compared to PBS treated mice, and DR hearts had increased gene expression of the IFNγ inducible chemokines Cxcl9 and Cxcl10 . Ex vivo DR (0.1 μg/mL) treatment of CD8 + T-cells during TCR activation with αCD3/CD28 increased IFNγ expression at the protein and transcript level. The same dose of DR also increased surface expression of ICAM-1 on CFB, and CD8 + T-cells adhered to DR treated CFB in vitro in greater numbers than untreated CFB, and induced more αSMA expression. Lastly, in patients treated with DR, plasma levels of CXCL9 and CXCL10 correlated with decreases in EF after 3 months of treatment. Conclusion: These data outline a novel CD8 T-cell-driven inflammatory mechanism in DR cardiotoxicity, driven by IFNγ-inducible chemokines in animal models and patients.