University of Montana
Biomarkers of Organophosphate-Adducted Proteins
Charles Mark Thompson
The short-term goals of this application are to identify adducted and altered protein biomarkers that correlate with organophosphate (OP) insecticide exposure and to use these biomarkers to generate antibodies to validate the biomarker detection in biological fluids. Over 100 million pounds of OP insecticides are used each year and lead to over 25,000 reports to poison control centers each year, including 10,000 involving children under age six. These reports, however, only account for acute poisoning events and do not include low dose or chronic exposures.
In addition to general exposure and food contamination, the safety of OPs is a large public health concern because OPs share certain chemical traits, structure and biological mechanism in common with nerve gas agents. These concerns are elevated by an array of neurologic and non-neurologic sequelae that have been reported in connection with exposure to OPs.
To combat, monitor and provide therapeutic intervention, a blood cholinesterase test (BCT) has been conducted as a first indicator of exposure. However, the test is limited and inadequate to assess OP exposure. Its shortcomings have been identified by a U.S. Environmental Protection Agency (EPA) report that questions the merit of the BCT and suggests the need to examine true biomarkers of exposure. At this time, there is a serious void in effective tests of OP exposure. New tests are needed that are sensitive, selective, operate in real time and are based on reliable, well-characterized OP-biomarkers derived from exacting molecular events that correlate with cellular, tissue, organ or systemic toxicity.
The long range goal of our research has been to identify OP-adducted and/or OP-altered protein biomarkers that are associated with OP-induced sequelae and to develop diagnostic methods and tests that assess the human health risk and aid therapeutic action. We have addressed the following specific aims:
- Show that OP's result in highly specific OP-AChE adducts that can be identified and differentiated by antibodies.
- Identify and characterize OP-adducted protein biomarkers in SH-SY5Y neuroblastoma cells using OP-reporter molecules.
- Identify and characterize OP-protein biomarkers from human saliva, human serum and human erythrocytes.
Prepare customized antibodies that recognize OP-adducted proteins identified in SA-II and SA-III and develop efficient diagnostic tests to identify and quantify OP-protein adducts.