Jing Zhang ¹ Rodrigue Rizk ² Xiaoping Li ¹ Brandon G. Lee ³ Mason L. Matthies ¹ Kennedy A. Bietz ¹ Kang Kim ⁴ Johnny Huard ⁵ Yadong Wang ⁶ William CW Chen ^1*

• ¹ Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, United States
• ² Department of Computer Science, College of Arts & Sciences, University of South Dakota, Vermillion, South Dakota, United States
• ³ Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
• ⁴ Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
• ⁵ The Linda & Mitch Center for Regenerative and Personalized Medicine, Steadman Philippon Research Institute, Vail, CO, United States
• ⁶ Department of Biomedical Engineering, College of Engineering, Cornell University, Ithaca, New York, United States

Interleukin-10 (IL-10) is a potent immunomodulatory cytokine widely explored as a therapeutic agent for diseases, including myocardial infarction (MI). High-dose IL-10 treatment may not achieve expected outcomes, raising the question of whether IL-10 has dose-dependency, or even uncharted side-effects from overdosing. We hypothesized that IL-10 has dose-dependent effects on macrophage (Mφ) phenotypic transition and cardiac remodeling after MI. Using RAW264.7 monocyte models, we examined whether administering differential doses of exogenous IL-10 (0-1000 ng/mL) perturbs classic M1 (proinflammatory) and M2 (anti-inflammatory) phenotypes of polarized Mφ or even alters the phenotypic transition of prospective M1 and M2 polarization. Compared with 0-ng/mL control, 250-ng/mL IL-10 had the strongest overall effects in decreasing M1 and increasing M2 phenotypes on polarized Mφ while ≥500-ng/mL IL-10 dampened M1 polarization and augmented native IL-10 secretion more effectively than low doses. Using a mouse MI model, we then investigated the impact of single intramyocardial IL-10 administration on cardiac function, structure, and inflammation post-MI. Echocardiography revealed that the 250-ng group had consistently higher contractile function and lower left ventricular (LV) dilatation than the saline control over 6 weeks while ≥1000-ng groups exhibited transient lower LV ejection fraction at 5 days post-MI. Moreover, different doses of IL-10 differentially modulated myocardial gene expression, phagocytic cell infiltration at the infarct, LV fibrosis, and revascularization post-MI, with some, but not all, doses exerting beneficial effects. Our study suggested that IL-10 has an effective dose range on Mφ phenotypes, and intramyocardial IL-10 treatment may trigger cardioprotective or unwanted effects post-MI in a dose-dependent manner.