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 (<i>FDXR</i>, <i>DDB2</i>, <i>POU2AF1</i>, <i>WNT3</i>) 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 For quantitative Real-Time-PCR (qRT-PCR), peripheral whole blood was withdrawn before and on days 1, 3, and 10 after irradiation.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 <i>18S rRNA</i> and <i>PUM1</i> 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. <i>18S rRNA</i> revealed significantly (<i>p</i> = .0005) about two-fold higher variance of raw Ct-values than <i>PUM1</i>. DGE was calculated for all genes except <i>WNT3</i> (undetectable in most animals). All genes revealed a slight up-regulation over time in most animals, but DGE &gt; 2 regarding <i>FDXR</i> or <i>DDB2</i> and concomitant downregulation of <i>POU2AF1</i> (DGE &lt; 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.