Date of Award

2018

Document Type

Thesis

Department

Biology

First Advisor

Dr. Jim Taylor

Second Advisor

Dr. Angela Douglass

Third Advisor

Dr. Myra Houser

Abstract

Background: Acetaminophen (APAP) is a common analgesic that can cause liver injury and death in high doses. Changes in gene expression following APAP overdose may be more sensitive indicators of liver injury than the current clinical indicator, alanine aminotransferase (ALT). The aim of this study was to examine gene expression of Phase I enzymes in pediatric APAP overdose patients with low ALT levels (<75 lU/L), in order to understand the mechanism of APAP toxicity.

Methods: Blood samples were collected from control patients (no APAP exposure; N=5) and APAP overdose patients (N=S). Using the PAXgene system, RNA was extracted from the blood samples and cDNA was synthesized. Quantitative polymerase chain reaction (qPCR) was performed and samples were profiled with an array containing 84 Phase I Enzyme drug metabolism genes.

Results: The low ALT pediatric APAP overdose patients had higher (median [range]) ALT levels (35 [25,48] lU/L) compared to controls (16 [7, 20] IU/L). Three genes had significant downregulation that was later confirmed: GZMB (-2.86 fold, p<0.01I), ALDH6A1 (-2.13 fold, p<0.01), and CYP4F12 (-4.04 fold, p<0,05). Pathway analysis for the three genes pointed to signaling pathways connected to apoptosis, metabolism of valine and leucine (involved in the immune response), and hydroxylation of leukotriene B4 (involved in inflammation).

Conclusion: Dysregulation of Phase I Enzyme drug metabolism pathways has relevance for understanding mechanisms of cell injury in APAP toxicity. Pathway analysis points to the potential for a weakened immune response associated with APAP overdose.

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