Biology subjects

Rimner, A.

Publications and source records attributed to Rimner, A..

2 recordsLinked to original sources

bioRxiv2021

Radiation Exposure of the Base of the Heart Accelerates Coronary Atherosclerosis

Clinical studies have identified cardiac exposure as an independent predictor for cardiovascular mortality in patients treated with radiation therapy (RT) for thoracic malignancies. Although the mechanisms are not completely understood, the available evidence indicate that direct injury to the coronary arteries endothelium is implicated. In these studies we tested the hypothesis that different areas of the heart are more sensitive to the effects of RT on the formation of atherosclerotic plaque in apolipoprotein E deficient (ApoE-/-) mice, a well validated model of atherosclerosis. MethodsApoE-/- mice on a high fat diet (HFD) received 16Gy cardiac irradiation targeted to the whole or partial (apical or basal) region of the heart at 9 weeks or 16 weeks of age. Atherosclerotic lesions and inflammatory changes in the hearts as compared to control unirradiated mice were assessed eight weeks following radiation. ResultsAfter either basal or whole heart RT at 9 weeks of age the number of subendocardial atherosclerotic lesions at the heart base was higher as compared to unirradiated mice. Irradiation of the apex did not increase the number of subendocardial atherosclerotic lesions in any region. After basal RT at 16 weeks of age the number of coronary and subendocardial atherosclerotic lesions was higher as compared to controls. Neither apical or whole heart RT had an impact on the development or acceleration of lesions in the basal region of the hearts of 16 week old mice, thus demonstrating the adverse impact of basal irradiation. Infiltration of inflammatory cells (CD45+ and CD3+) and enhanced expression of endothelial adhesion molecules (CD31), were differentially and locally regulated based upon the site of irradiation. In support of a role of eicosanoid mediators for base or whole heart atherogenic irradiation effects, apex irradiation eicosanoid mediators are not clearly atherogenic, in contrast to eicosanoid mediators detected in serum after base heart irradiation. These results indicate that the base of the heart is significantly more prone to the development of atherosclerotic lesions in the coronary arteries post-RT. ConclusionOur results indicate that the base of the heart is more susuceptible to development of RT-induced atherosclerotic lesions and therefore avoidance from RT direct exposure to this area may reduce the risk for atherosclerotic disease in patients undergoing RT.

cancer biology↗

bioRxiv2019

Serum Alpha-2-Macroglobulin as an intrinsic radioprotective factor in patients undergoing thoracic radiation therapy

ObjectiveTo investigate the impact of alpha-2-macroglobulin (A2M), a suspected intrinsic radioprotectant, on radiation pneumonitis and esophagitis. Additionally, we establish multifactorial predictive models for pneumonitis and esophagitis.\n\nMaterials/MethodsBaseline A2M levels were obtained for 258 patients prior to thoracic radiotherapy (RT). Dose-volume characteristics were extracted from treatment plans. Spearmans correlation (Rs) test was used to correlate A2M levels, smoking status and dosimetric variables with toxicities. Esophagitis and pneumonitis prediction models were built using least absolute shrinkage and selection operator (LASSO) logistic regression on 1000 bootstrapped datasets. Models were built using 2/3 of the data for training and 1/3 for validation.\n\nResultsThere were 36 (14.0%) patients with grade [≥]2 pneumonitis and 61 (23.6%) with grade [≥]2 esophagitis. The median A2M level was 191 mg/dL (range: 94-511). Never/former/current smoker status was 47 (18.2%)/179 (69.4%)/32 (12.4%). We found a significant correlation between baseline A2M levels and esophagitis (Rs=-0.18/p=0.003) and between A2M and smoking status (former or current) (Rs=0.13/p=0.04) but not between A2M and pneumonitis. On univariate analysis, significant parameters for grade [≥]2 esophagitis included number of fractions (Rs=0.47/p<0.0001), treatment days (Rs=0.44/p<0.0001), chemotherapy use (Rs=0.40/p<0.0001), dose per fraction (Rs=-0.34/p<0.0001), total dose (Rs=0.29/p<0.0001), age (Rs=-0.22/p=0.0003), and several dosimetric variables in esophagus with Rs>0.5 (p<0.0001). For pneumonitis, significant clinical parameters were treatment days (Rs=0.24/p=0.0001), chemotherapy use (Rs=0.22/p=0.0004), number of fractions (Rs=0.21/p=0.0007), dose per fraction (Rs=-0.18/p=0.0035), and total dose (Rs=0.15/p=0.013). The most significant dosimetric variable in lung and heart was D70 (Rs=0.28/p<0.0001) and max dose (Rs=0.27/p<0.0001), respectively. LASSO bootstrap logistic regression models on the validation data resulted in the area under the receiver operating characteristic curve of 0.84 and 0.75 for esophagitis and pneumonitis, respectively.\n\nConclusionOur findings show an association of higher A2M values with lower risk of radiation esophagitis and smoking status. Multivariate predictive models also confirmed a role of heart dose in the risk of pneumonitis.

cancer biology↗