Phenotypic and genotypic assessment of concomitant drug-induced toxic effects in liver, kidney and blood.

Several studies have characterized drug-induced toxicity in liver and kidney. However, the majority of these studies have been performed with 'individual' organs in isolation. Separately, little is known about the role of whole blood as a surrogate tissue in drug-induced toxicity. Accordingly, we investigated the 'concurrent' response of liver, kidney and whole blood during a toxic assault. Rats were acutely treated with therapeutics (acetaminophen, rosiglitazone, fluconazole, isoniazid, cyclophosphamide, amphotericin B, gentamicin and cisplatin) reported for their liver and/or kidney toxicity. Changes in clinical chemistry parameters (e.g. AST, urea) and/or observed microscopic tissue damage confirmed induced hepatotoxicity and/or nephrotoxicity by all drugs. Drug-induced toxicity was not confined to an 'individual' organ. Not all drugs elicited significant alterations in phenotypic parameters of toxicity (e.g. ALT, creatinine). Accordingly, the transcriptional profile of the organs was studied using a toxicity panel of 30 genes derived from literature. Each of the test drugs generated specific gene expression patterns which were unique for all three organs. Hierarchical cluster analyses of purported hepatotoxicants and nephrotoxicants each led to characteristic 'fingerprints' (e.g. decrease in Cyp3a1 indicative of hepatotoxicity; increase in Spp1 and decrease in Gstp1 indicative of nephrotoxicity). In whole blood cells, a set of genes was derived which closely correlated with individual drug-induced concomitant changes in liver or kidney. Collectively, these data demonstrate drug-induced multi-organ toxicity. Furthermore, our findings underscore the importance of transcriptional profiling during inadequate phenotypic anchorage and suggest that whole blood may be judiciously used as a surrogate for drug-induced extra-hematological organ toxicity.

Effect of nephrotoxicants and hepatotoxicants on gene expression profile in human peripheral blood mononuclear cells.

Studying peripheral blood transcriptome in the quest for translational markers of toxicity is considered to be an attractive offshoot in the field of toxicogenomics. Moreover, it is acknowledged that, xenobiotics which cause a toxic response through similar mechanisms lead to distinctive gene expression patterns. The current study was undertaken to gauge the response of an accessible surrogate tissue, such as blood, to drug-induced perturbations aimed at deriving gene expression patterns. Human peripheral blood mononuclear cells (hPBMC) were exposed to conventional drugs, with reported kidney and/or liver injury, in order to determine their transcriptomic response. Test drugs were divided into two classes viz., drugs affecting kidney (cyclophosphamide, amphotericin B, gentamicin and cisplatin) and liver (acetaminophen, rosiglitazone, fluconazole and isoniazid). After performing gene expression analysis and hierarchical clustering, signature patterns for the two classes were obtained, with a set of 365 genes that can discriminate the two classes of drugs. Our results imply that transcriptional profile of hPBMC get altered as a consequence of drug exposure and unique patterns indicative of specific organ toxicity can hence be deduced. These signature patterns obtained for drugs could be studied for their qualification to identify drug-induced toxicity.