title: The delayed pulmonary syndrome following acute high-dose irradiation: a rhesus macaque model.
abstract: Several radiation dose- and time-dependent tissue sequelae develop following acute high-dose radiation exposure. One of the recognized delayed effects of such exposures is lung injury, characterized by respiratory failure as a result of pneumonitis that may subsequently develop into lung fibrosis. Since this pulmonary subsyndrome may be associated with high morbidity and mortality, comprehensive treatment following high-dose irradiation will ideally include treatments that mitigate both the acute hematologic and gastrointestinal subsyndromes as well as the delayed pulmonary syndrome. Currently, there are no drugs approved by the Food and Drug Administration to counteract the effects of acute radiation exposure. Moreover, there are no relevant large animal models of radiation-induced lung injury that permit efficacy testing of new generation medical countermeasures in combination with medical management protocols under the FDA animal rule criteria. Herein is described a nonhuman primate model of delayed lung injury resulting from whole thorax lung irradiation. Rhesus macaques were exposed to 6 MV photon radiation over a dose range of 9.0-12.0 Gy and medical management administered according to a standardized treatment protocol. The primary endpoint was all-cause mortality at 180 d. A comparative multiparameter analysis is provided, focusing on the lethal dose response relationship characterized by a lethal dose50/180 of 10.27 Gy [9.88, 10.66] and slope of 1.112 probits per linear dose. Latency, incidence, and severity of lung injury were evaluated through clinical and radiographic parameters including respiratory rate, saturation of peripheral oxygen, corticosteroid requirements, and serial computed tomography. Gross anatomical and histological analyses were performed to assess radiation-induced injury. The model defines the dose response relationship and time course of the delayed pulmonary sequelae and consequent morbidity and mortality. Therefore, it may provide an effective platform for the efficacy testing of candidate medical countermeasures against the delayed pulmonary syndrome.
authors.affiliation: *University of Maryland, School of Medicine, Department of Radiation Oncology; †Statistician, Rockville, MD.
authors.forename: Michael
authors.initials: M
authors.lastname: Garofalo
authors.forename: Alexander
authors.initials: A
authors.lastname: Bennett
authors.forename: Ann M
authors.initials: AM
authors.lastname: Farese
authors.forename: Jamie
authors.initials: J
authors.lastname: Harper
authors.forename: Amanda
authors.initials: A
authors.lastname: Ward
authors.forename: Cheryl
authors.initials: C
authors.lastname: Taylor-Howell
authors.forename: Wanchang
authors.initials: W
authors.lastname: Cui
authors.forename: Allison
authors.initials: A
authors.lastname: Gibbs
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lasio
authors.forename: William
authors.initials: W
authors.lastname: Jackson
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: MacVittie
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D005355:Fibrosis; D006403:Hematologic Tests; D008168:Lung / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D008253:Macaca mulatta; D008297:Male; D009929:Organ Size / Q000187:drug effects / Q000528:radiation effects; D010100:Oxygen / Q000378:metabolism; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D017564:Radiation Pneumonitis / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D012119:Respiration / Q000187:drug effects / Q000528:radiation effects; D015996:Survival Rate; D013909:Thorax / Q000528:radiation effects; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D003907:Dexamethasone; D010100:Oxygen