LPS‐induced transcriptomic changes are detectable in minimal volumes of rat whole blood

Abstract

Whole blood is an easily accessible tissue that allows for non‐invasive, real‐time monitoring of compound exposure and effects. Using blood for transcriptional profiling presents technical challenges, particularly because PAXgene tubes require 2.5mL of blood. We have developed a reproducible method of RNA stabilization and isolation to be used for transcriptional profiling from as little as 25μL of whole blood. To demonstrate the validity of this technique, we used an acute inflammation model and treated rats with lipopolysaccharide (LPS, IV) for 2h. Varied amounts of whole blood (25‐500μL) were collected from each rat and immediately added to Qiazol or collected directly into PAXgene tubes. Both techniques yielded abundant, high‐quality RNA. Total RNA (50ng) was processed using the NuGEN Ovation RNA Amplification System, then hybridized to Affymetrix Rat230_2 microarrays. Statistical analysis of microarray intensity values revealed high correlation between blood collected using PAXgene tubes and all volumes of blood added to Qiazol (r = 0.8, p=0.001, FC=1.5). Expression analysis of both methods showed little discordance in IL‐10 signaling, IFN signaling, and LPS‐induced inflammatory response. The evidence from this novel blood collection technique suggests as little as 25μL of whole blood can be used in preclinical toxicology and pharmacology studies for future identification of novel biomarkers.