Abstract 789: The role of the cardio-splenic axis in doxorubicin-induced exacerbation of hypertension-associated cardiomyopathy

Abstract Introduction: Doxorubicin (DOX), a commonly used chemotherapeutic agent in childhood cancers, is associated with significant cardiotoxic side. Hypertension is a known risk factor for heart failure in DOX-treated childhood cancer survivors. This study utilizes a "two-hit" mouse model, wherein juvenile DOX exposure amplifies adult-onset hypertension-associated cardiomyopathy. We hypothesize that hypertension mobilizes DOX-induced immunosenescent cells from the spleen to the heart via the cardio-splenic axis, contributing to cardiac dysfunction. The primary objective was to delineate the role of the cardio-splenic axis and CCR2+ immune cell recruitment in DOX/hypertension-induced cardiomyopathy. Methods: Male C57BL/6N mice (5 weeks old) were treated with DOX (4 mg/kg/week) or saline for 3 weeks, followed by a 5-week recovery period. Subsequently, hypertension was induced with angiotensin II (ANG II; 1.4 mg/kg/day) or saline for 14 days. Cardiac function was assessed via echocardiography, and gene expression of inflammatory and immune recruitment markers in the heart and spleen was quantified using real-time PCR. Flow cytometry was performed to evaluate changes in splenic immune cell subpopulations, focusing on CCR2+ immune cells. To assess the functional role of CCR2, the effects of DOX/hypertension on cardiac function were assessed in CCR2 knockout mice. Results: Low-dose DOX treatment alone did not cause significant cardiac dysfunction in young C57BL/6N mice. However, ANG II-induced hypertension markedly exacerbated cardiac dysfunction in DOX-treated mice, as evidenced by a significant reduction in cardiac output and a remarkable inflammatory/fibrotic remodeling. DOX treatment disrupted splenic immune cell populations, with an increase of CCR2+ immune cells. ANG II-induced hypertension further compounded this effect by causing splenic contraction in DOX-treated mice. ANG II-induced hypertension upregulated gene expression of CCR2 in the heart and reduced it in the spleen of DOX-treated mice, suggesting that CCR2+ cells were mobilized to the heart via the cardio-splenic axis. CCR2 knockout mice were protected against DOX/hypertension-induced cardiac dysfunction, as KO mice maintained cardiac output compared to wild-type mice, underscoring the critical role of CCR2-mediated innate immune responses in the observed cardiac dysfunction. Conclusions: These findings demonstrate that DOX-induced CCR2+ immune alterations exacerbate hypertension-associated cardiomyopathy via the cardio-splenic axis. Our data suggest that hypertension mobilizes CCR2+ immune cells from the spleen to the heart, driving inflammatory responses and cardiac dysfunction. Genetic deletion of CCR2+ cells protects against these effects, highlighting CCR2 as a potential therapeutic target to mitigate DOX/hypertension-induced cardiac dysfunction. Citation Format: MARY RAPHEL DANIEL, Benu George, Marianne K.O Grant, Korbyn J.V. Dahlquist, Christina D. Camell, Beshay N. Zordoky. The role of the cardio-splenic axis in doxorubicin-induced exacerbation of hypertension-associated cardiomyopathy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 789.