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Several interleukin (IL) family members have been demonstrated to be involved in doxorubicin (DOX)-induced cardiac injury. This study aimed to investigate the role of IL-22 in DOX-induced cardiac injury and explore its possible mechanisms. In this study, mice were given DOX, and the cardiac expression and sources of IL-22 were determined. Then, IL-22 was knocked out to observe the effects on DOX-induced cardiac injury in mice. In addition, the p38 mitogen-activated protein kinase (MAPK) pathway was inhibited, macrophages were depleted and adoptively transferred, and Fizz3 was up-regulated in mice to explore the mechanisms. The results showed that cardiac IL-22 expression was significantly increased by DOX treatment and was mostly derived from cardiac macrophages. IL-22 knockout significantly reduced cardiac vacuolization and the expression of cardiomyocyte injury markers in both serum and left ventricular tissue and improved cardiac function in DOX-treated mice. In addition, IL-22 knockout reversed DOX-induced cardiac M1 macrophage/M2 macrophage imbalance, reduced oxidative stress and protected against cardiomyocyte apoptosis. p38 MAPK pathway inhibition with SB203580 and macrophage depletion further alleviated the above effects in DOX-treated IL-22-knockout mice. The effects were stronger IL-22-knockout mice with adoptive transfer of WT macrophages than in those with adoptive transfer of IL-22-knockout macrophages. Furthermore, increasing the expression of Fizz3 reduced cardiomyocyte apoptosis and alleviated cardiac dysfunction. Our results may suggest that IL-22 knockout alleviate DOX-induced oxidative stress and cardiac injury by inhibiting macrophage differentiation and thereby increasing the expression of Fizz3. Reductions in IL-22 expression may be beneficial for clinical chemotherapy in tumor patients.

Several interleukin (IL) family members have been demonstrated to be involved in doxorubicin (DOX)-induced cardiac injury. This study aimed to investigate the role of IL-22 in DOX-induced cardiac injury and explore its possible mechanisms. In this study, mice were given DOX, and the cardiac expression and sources of IL-22 were determined. Then, IL-22 was knocked out to observe the effects on DOX-induced cardiac injury in mice. In addition, the p38 mitogen-activated protein kinase (MAPK) pathway was inhibited, macrophages were depleted and adoptively transferred, and Fizz3 was up-regulated in mice to explore the mechanisms. The results showed that cardiac IL-22 expression was significantly increased by DOX treatment and was mostly derived from cardiac macrophages. IL-22 knockout significantly reduced cardiac vacuolization and the expression of cardiomyocyte injury markers in both serum and left ventricular tissue and improved cardiac function in DOX-treated mice. In addition, IL-22 knockout reversed DOX-induced cardiac M1 macrophage/M2 macrophage imbalance, reduced oxidative stress and protected against cardiomyocyte apoptosis. p38 MAPK pathway inhibition with SB203580 and macrophage depletion further alleviated the above effects in DOX-treated IL-22-knockout mice. The effects were stronger IL-22-knockout mice with adoptive transfer of WT macrophages than in those with adoptive transfer of IL-22-knockout macrophages. Furthermore, increasing the expression of Fizz3 reduced cardiomyocyte apoptosis and alleviated cardiac dysfunction. Our results may suggest that IL-22 knockout alleviate DOX-induced oxidative stress and cardiac injury by inhibiting macrophage differentiation and thereby increasing the expression of Fizz3. Reductions in IL-22 expression may be beneficial for clinical chemotherapy in tumor patients., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)