Pre-Exposure Gene Expression in Baboons with and without Pancytopenia after Radiation Exposure

Abstract

Radiosensitivity differs in humans and likely among primates. The reasons are not well known. We examined pre-exposure gene expression in baboons (n = 17) who developed haematologic acute radiation syndrome (HARS) without pancytopenia or a more aggravated HARS with pancytopenia after irradiation. We evaluated gene expression in a two stage study design where stage I comprised a whole genome screen for messenger RNAs (mRNA) (microarray) and detection of 667 microRNAs (miRNA) (real-time quantitative polymerase chain reaction (qRT-PCR) platform). Twenty candidate mRNAs and nine miRNAs were selected for validation in stage II (qRT-PCR). None of the mRNA species could be confirmed during the validation step, but six of the nine selected candidate miRNA remained significantly different during validation. In particular, miR-425-5p (receiver operating characteristic = 0.98; p = 0.0003) showed nearly complete discrimination between HARS groups with and without pancytopenia. Target gene searches of miR-425-5p identified new potential mRNAs and associated biological processes linked with radiosensitivity. We found that one miRNA species examined in pre-exposure blood samples was associated with HARS characterized by pancytopenia and identified new target mRNAs that might reflect differences in radiosensitivity of irradiated normal tissue.

Nonhuman primates as models for the discovery and development of radiation countermeasures

“…In addition to rhesus and cynomolgus macaques, several studies have been conducted using baboons (Papio sp) to investigate radiation injuries resulting from exposure to X-rays [9], 60 Co γ-radiation [10,11], and mixed field (neutron and γ-photon) irradiation [12]. In recent years, various studies have reported significant biomarkers for radiation injuries using the baboon model [13–17]. Furthermore, a number of promising radiation countermeasures under development for H-ARS are being tested in NHPs for efficacy and pharmacokinetics/pharmacodynamics (Table 2).…”

Persistent mRNA and miRNA expression changes in irradiated baboons

“…Then, the baboons were placed in restraint chairs, sitting orthogonally, front to a horizontal and homogeneous field of gamma rays delivered by a 60 Co source (IRDI 4000; Alsthom, Levallois, France) to perform either total body irradiation (TBI) or partial body irradiation (PBI). In order to attain different patterns of PBI, a 20 cm thick lead screen was used to shield different parts of the body (for details see 20 , 21 . Two baboons were exposed to 5 Gy TBI and two others to 2.5 Gy TBI.…”

“…Two baboons were exposed to 5 Gy TBI and two others to 2.5 Gy TBI. Eight different exposure patterns were simulated and two baboons were exposed per pattern which summed up to 14 baboons receiving PBI (for details see 20 , 21 ) corresponding to an equivalent TBI dose of 2.5 or 5 Gy. Two dose rates were used (8 cGy/min for 5 Gy TBI and 5 Gy 50% PBI, and 32 cGy/min for all other situations) because the Cobalt 60 source was changed during this study.…”

“…The mid-line tissue (right anterior iliac crest) dose in air was measured with an ionization chamber. Delivered doses were monitored by alumina powder thermoluminescent dosimeters placed on different cutaneous areas (thorax, thoracic and lumbar vertebrae, head, tibia, femur, femoral head, for details see 20 , 21 ).…”

Overcoming challenges in human saliva gene expression measurements

“…Our group has extensive experience in the isolation of RNA from whole blood, its cellular subgroups and biopsies of different tissue sources [20][21][22][23][24] . We recently became interested in isolating RNA from saliva.…”