| Purpose:The purpose of this study is to investigate the dynamic changes and mechanisms of extracellular histones in mice with RIHD.This study aims to evaluate whether extracellular histones can be used as biomarkers for early warning of RIHD and explore the protective effects of treatments in RIHD such as heparin and tanshinoneⅡ which targets for extracellular histones.Methods:Eighty male C57BL/6 mice were randomly divided into 4 groups: control group,RIHD group,RIHD+heparin treatment group,and RIHD+tanshinone IIA treatment group.Except for the control group,the other three groups were given irradiation with 6MV-X ray of 20 Gy in hearts of mice.The RIHD+heparin treatment group and the RIHD+tanshinone IIA treatment group were respectively given heparin and tanshinone IIA for prevention after radiation.At 0,1,2,4 and 8 weeks after radiation,blood and heart tissues of mice were collected for detection.HE staining and Masson staining were used to observe the structure of heart tissue,and CVF was analyzed quantitatively to determine the pathological manifestations of RIHD.Levels of serum cTnI and CK-MB were detected to evaluate the status of cardiac injury.Levels of plasma extracellular histone and MPO were detected by ELISA.Levels of plasma IL-1β,IL-6,TNF-α and TGF-β1 were detected by Luminex assay.The same method is applied to detect in RIHD+heparin treatment group and RIHD+tanshinone IIA treatment group.Results:Compared with the control group,the myocardium of RIHD group showed no significant changes in HE staining at 1st,4th and 8th week after radiation.The number of neutrophils and lymphocytes in the heart interstitium was increased at 2nd week after radiation and the arrangement of myocardial cells was slightly scattered,and the interstitium was widened.Masson staining showed disordered arrangement of cardiomyocytes,blue staining of collagen fiber deposition in the interstitium of cardiomyocytes and around blood vessels.CVF was significantly higher than that in the control group at 4th and 8th weeks after radiation,but there was no significant change in 1st and 2nd weeks after radiation.The levels of cTnI and CK-MB in RIHD group also showed a time-dependent increase compared with the control group which suggests that there is cardiac injury after radiation.Compared with the control group,levels of extracellular histones and MPO in RIHD group began to increase at 1st week after radiation,reached the peak at 2nd week after radiation,and decreased significantly at 4th and 8th weeks after radiation but were still higher than the baseline level.Levels of IL-1β,IL-6,TNF-α and TGF-β1 also increased significantly.Compared with RIHD group,the application of heparin and tanshinone ⅡA after radiation,the pathology of heart damage performance improved markedly,inflammatory cells infiltration was reduced,CVF and levels of cTnI,CK-MB were decreased.Compared with RIHD group,levels of extracellular histones,MPO,inflammatory factors(IL-1β,IL-6,TNF-α)and TGF-β1 in RIHD+ heparin group and RIHD+ tanshinone IIA group were decreased at different time points,and the differences were statistically significant.Conclusions:Extracellular histones were significantly increased at the early stage of irradiation,which was positively correlated with MPO and inflammatory cytokines,suggesting that inflammatory mediated by extracellular histones was involved in RIHD,and extracellular histones could be used as markers for early warning and monitoring of the occurrence and development of RIHD.Application of heparin and tanshinone ⅡA after radiation can ease the heart damage in RIHD group,and levels of cTnI,CK-MB,extracellular histones,inflammatory factors declined,showed that heparin or tanshinone ⅡA blocked the inflammatory effect of extracellular histones,which can reduce the incidence of RIHD,and extracellular histone can be used as therapeutic targets early for treatment of RIHD. |
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