Jie Bai,1– 3,* Bibo Wu,1– 3,* Shasha Zhao,1– 3,* Gang Wang,1– 3,* Shengfa Su,1– 3 Bing Lu,1– 3 Yinxiang Hu,1– 3 Yichao Geng,1,3 Zhengneng Guo,1– 3 Jun Wan,2,3 Weiwei OuYang,1– 3 Cheng Hu,1– 3 Jie Liu1– 3 1Department of Oncology, The Affiliated Hospital of Guizhou Medical University, Guiyang, People’s Republic of China; 2Department of Oncology, The Affiliated Cancer Hospital of Guizhou Medical University, Guiyang, People’s Republic of China; 3Department of Oncology, School of Clinical Medicine, Guizhou Medical University, Guiyang, People’s Republic of China*These authors contributed equally to this workCorrespondence: Shengfa Su, Department of Oncology, The Affiliated Hospital of Guizhou Medical University, Guiyang, People’s Republic of China, Tel +8613608550432, Fax +86513076, Email sushengfa2005@163.comPurpose: To explore the effect of PD-1 inhibitors combined with irradiation on myocardial injury and the changes of HMGB1-associated inflammatory markers.Methods: Four groups of five mice were used, each groupformed by randomly dividing 20 mice (group A control; group B PD-1 inhibitors; group C Irradiation; group D PD-1 inhibitors+irradiation; n = 5 for each). The mice were treated with either PD-1 inhibitors or a 15 Gy dose of single heart irradiation, or both. Hematoxylin-eosin staining assessed the morphology and pathology of heart tissue; Masson staining assessed heart fibrosis; Tunel staining evaluated heart apoptosis; flow cytometry detected CD3+, CD4+, and CD8+ T lymphocytes in heart tissues; enzyme linked immunosorbent assay evaluated IL-1β, IL-6, and TNF-ɑ of heart tissue; Western blot and quantitative real-time PCR (qPCR) detected the expression of protein and mRNA of HMGB1, TLR-4, and NF-κB p65 respectively.Results: The degree of heart injury, collagen volume fraction (CVF) and apoptotic index (AI) in groups B, C, and D were higher than group A, but the differences between the CVF and AI of group A and group B were not statistical significance (P> 0.05). Similarly, the absolute counts and relative percentage of CD3+ and CD8+ T lymphocytes and the concentrations of IL-1β, IL-6, and TNF-α in heart tissue with group D were significantly higher than the other groups (P< 0.05). In addition, compared with group A, the expression of protein and mRNA of HMGB1 and NF-κB p65 in other groups were higher, and the differences between each group were statistically significant while TLR4 was not. In addition, interaction by PD-1 inhibitors and irradiation was found in inflammatory indicators, especially in the expression of the HMGB1 and CD8+ T lymphocytes.Conclusion: PD-1 inhibitors can increase the expression of HMGB1-associated inflammatory cytokines and aggravate radiation-induced myocardial injury.Keywords: HMGB1, PD-1 inhibitors, radiotherapy, heart injury
