The immune checkpoint regulator CD40 potentiates myocardial inflammation

Immune checkpoint therapeutics including CD40 agonists have tremendous promise to elicit antitumor responses in patients resistant to current therapies. Conventional immune checkpoint inhibitors (PD-1/PD-L1, CTLA-4 antagonists) are associated with serious adverse cardiac events including life-threatening myocarditis. However, little is known regarding the potential for CD40 agonists to trigger myocardial inflammation or myocarditis. Here, we leverage genetic mouse models, single cell sequencing, and cell depletion studies to demonstrate that an anti-CD40 agonist antibody reshapes the cardiac immune landscape through activation of CCR2+ macrophages and subsequent recruitment of effector memory CD8 T-cells. We identify a positive feedback loop between CCR2+ macrophages and CD8 T-cells driven by IL12b, TNF, and IFN-γ signaling that promotes myocardial inflammation and show that prior exposure to CD40 agonists sensitizes the heart to secondary insults and accelerates LV remodeling. Collectively, these findings highlight the potential for CD40 agonists to promote myocardial inflammation and potentiate heart failure pathogenesis. To reveal the cardiac immune landscape of CD40 agonist treated mice, we performed CITE-sequencing (CITE-seq) of heart tissue from control (C57BL6J treated with Rat IgG antibodies, n=4) and anti-CD40 (C57BL6J treated with anti-CD40 agonist antibodies, n=4) mice. We constructed 2 libraries (control: L1; disease: 2) from DRAQ5+DAPI- cells purified from pooled enzymatically digested hearts by FACS.