Applicability of a four-gene set for H-ARS severity prediction in peripheral blood samples of irradiated minipigs

The fast diagnosis of the life-threatening acute radiation syndrome is crucial, as the early prediction of the hematological acute radiation syndrome (H-ARS) can save lives. Previously, we validated a four-gene set (FDXR, DDB2, POU2AF1, WNT3) for H-ARS severity prediction in non-human primates and leukemia patients. In this study, we aim to validate this gene set in minipigs as a surrogate model.

12 Göttingen minipigs, irradiated with 1.8 or 2.1 Gray (LD_≈40/30), were examined. METREPOL H-ARS severity degrees were determined using sequential blood cell count changes over time after irradiation. For quantitative Real-Time-PCR (qRT-PCR), peripheral whole blood was withdrawn before and on days 1, 3, and 10 after irradiation. Normalization was performed using 18S rRNA and PUM1 as housekeeping genes (HKG). Differential gene expression (DGE) relative to the pre-irradiated samples was calculated.

All minipigs developed a 2-4 H-ARS-severity degree. 18S rRNA revealed significantly (p = .0005) about two-fold higher variance of raw Ct-values than PUM1. DGE was calculated for all genes except WNT3 (undetectable in most animals). All genes revealed a slight up-regulation over time in most animals, but DGE > 2 regarding FDXR or DDB2 and concomitant downregulation of POU2AF1 (DGE < 0.5) as expected given the H-ARS severity degrees, was not observed.

None of the animals revealed the expected DGE pattern corresponding to a moderate to high H-ARS-severity degree. Hence, the Göttingen minipig did not qualify as another validation model for our specific gene set, which does not argue against their validity for other purposes.