title: Eosinophil-Associated Gene Pathways but not Eosinophil Numbers are Differentially Regulated between Synchrotron Microbeam Radiation Treatment and Synchrotron Broad-Beam Treatment by 48 Hours Postirradiation.
abstract: Synchrotron microbeam radiation treatment (MRT) is a preclinical radiotherapy technique with considerable clinical promise, although some of the underlying radiobiology of MRT is still not well understood. In recently reported studies, it has been suggested that MRT elicits a different tumor immune profile compared to broad-beam treatment (BB). The aim of this study was to investigate the effects of synchrotron MRT and BB on eosinophil-associated gene pathways and eosinophil numbers within and around the tumor in the acute stage, 48 h postirradiation. Balb/C mice were inoculated with EMT6.5 mouse mammary tumors and irradiated with microbeam radiation (112 and 560 Gy) and broad-beam radiation (5 and 9 Gy) at equivalent doses determined from a previous in vitro study. After tumors were collected 24 and 48 h postirradiation, RNA was extracted and quantitative PCR performed to assess eosinophil-associated gene expression. Immunohistochemistry was performed to detect two known markers of eosinophils: eosinophil-associated ribonucleases (EARs) and eosinophil major basic protein (MBP). We identified five genes associated with eosinophil function and recruitment (Ear11, Ccl24, Ccl6, Ccl9 and Ccl11) and all of them, except Ccl11, were differentially regulated in synchrotron microbeam-irradiated tumors compared to broad-beam-irradiated tumors. However, immunohistochemical localization demonstrated no significant differences in the number of EAR- and MBP-positive eosinophils infiltrating the primary tumor after MRT compared to BB. In conclusion, our work demonstrates that the effects of MRT on eosinophil-related gene pathways are different from broad-beam radiation treatment at doses previously demonstrated to be equivalent in an in vitro study. However, a comparison of the microenvironments of tumors, which received MRT and BB, 48 h after exposure showed no difference between them with respect to eosinophil accumulation. These findings contribute to our understanding of the role of differential effects of MRT on the tumor immune response.
authors.affiliation: a  Department of Obstetrics and Gynaecology, The University of Melbourne, Level 7, The Royal Women's Hospital, Parkville, Victoria 3052, Australia;|b  Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Jalan Hospital, Selangor, Malaysia;
authors.forename: M J
authors.initials: MJ
authors.lastname: Ibahim
authors.affiliation: a  Department of Obstetrics and Gynaecology, The University of Melbourne, Level 7, The Royal Women's Hospital, Parkville, Victoria 3052, Australia;
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.affiliation: c  School of Applied Sciences, RMIT University, Melbourne, Victoria 3001, Australia;|d  William Buckland Radiotherapy Centre, Alfred Hospital, Melbourne, Victoria 3004, Australia;
authors.forename: J C
authors.initials: JC
authors.lastname: Crosbie
authors.affiliation: e  The Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia; and.|f  CSIRO Materials Science and Engineering, Clayton, Victoria 3168, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Stevenson
authors.affiliation: a  Department of Obstetrics and Gynaecology, The University of Melbourne, Level 7, The Royal Women's Hospital, Parkville, Victoria 3052, Australia;
authors.forename: L
authors.initials: L
authors.lastname: Cann
authors.affiliation: a  Department of Obstetrics and Gynaecology, The University of Melbourne, Level 7, The Royal Women's Hospital, Parkville, Victoria 3052, Australia;
authors.forename: P
authors.initials: P
authors.lastname: Paiva
authors.affiliation: a  Department of Obstetrics and Gynaecology, The University of Melbourne, Level 7, The Royal Women's Hospital, Parkville, Victoria 3052, Australia;
authors.forename: P A
authors.initials: PA
authors.lastname: Rogers
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects; D016207:Cytokines / Q000276:immunology*; D004307:Dose-Response Relationship, Radiation; D004804:Eosinophils / Q000166:cytology* / Q000276:immunology* / Q000528:radiation effects; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology / Q000528:radiation effects; D007958:Leukocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000473:pathology* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*; D015398:Signal Transduction / Q000276:immunology / Q000528:radiation effects; D017356:Synchrotrons; D016896:Treatment Outcome
chemical_list: D016207:Cytokines