CCR2 deficiency protects against doxorubicin-induced cardiac dysfunction through enhanced IL12B-dependent autophagy

Doxorubicin (DOX) is a potent chemotherapeutic agent whose antitumor benefits are limited by a well-recognized, dose-dependent cardiotoxicity. While previous studies have implicated inflammatory pathways in DOX-induced cardiomyopathy (DIC), the role of CCR2 in this process remains incompletely defined. This study aims to investigate whether CCR2 deficiency confers cardioprotection against DIC and to uncover the molecular mechanisms involved.

CCR2 knockout (CCR2^⁻/⁻ ) mouse was subjected to both acute and chronic DIC models. Bone marrow transplantation was used to establish the functional contribution of CCR2-deficient macrophages. Autophagic flux was evaluated using complementary approaches, including a tandem mRFP-GFP-LC3 reporter, western blotting, immunofluorescence, and transmission electron microscopy. The mediator linking CCR2-deficient macrophages to cardiomyocytes was identified by proteomics and validated using recombinant IL12B protein and a neutralizing antibody.

CCR2 deficiency substantially improved cardiac function, as evidenced by preserved left ventricular ejection fraction, fractional shortening and reduced serum cardiac injury markers. Mechanistic studies revealed that CCR2^⁻/⁻ hearts exhibited enhanced autophagic flux, with increased LC3B lipidation, autophagosome formation, and clearance of damaged cellular components. Proteomic profiling of cardiac macrophages identified interleukin-12B (IL12B) significantly upregulated in CCR2^⁻/⁻ mouse. Recombinant IL12B protein administration activated cardiomyocyte autophagy through PI3K/Akt/mTOR pathway inhibition and reproduced the cardioprotective effects in WT mouse. Conversely, IL12B neutralization completely abolished CCR2 deficiency-mediated protection.

Our findings identify a novel CCR2-IL12B-autophagy axis that critically regulates DOX-induced cardiotoxicity. CCR2 deficiency promotes IL12B secretion from cardiac macrophages, which directly activates protective autophagy in cardiomyocytes. These results establish CCR2 inhibition and IL12B supplementation as two promising therapeutic strategies to prevent chemotherapy-induced cardiomyopathy, providing a transformative approach to cardio-oncology.