Prolonged and progressive neuroinflammation and neurodegeneration are correlated with low-level exposure to chemical warfare agents (CWAs), such as sarin. Civilians surviving terrorist attacks with sarin are likely to be at most risk of these conditions due to the length of time required to administer treatment and the type of treatment currently available. Current US military treatment for CWA organophosphate exposure is a specialized drug combination containing;a drug to regenerate acetylcholinesterase activity;and two drugs to prevent seizures. This treatment must be administered within 40 minutes, after which there is no protection against seizures and progressive neurological damage occurs, including neuroinflammation. An understanding of the underlying causes of the neuroinflammatory response and ensuing cell death are currently lacking. Without this information, drug design and treatment are limited to similar types of drugs. The goal of this proposal is to test the ability of a novel broad-spectrum caspase inhibitor, Q-VD-OPh, to attenuate neuroinflammation and neurodegeneration in sarin treated mice when administered 30 minutes after exposure to sarin. Efficacy will be compared at 48 hours and 14 days with and without the anticonvulsant, diazepam and the negative cell death control, Q-VE-OPh.
The first aim of the study will be to establish neuroinflammatory and cell death markers of sarin exposure in the mice.
Aims two and three will be to determine if Q-VD-OPh can attenuate the progressive sarin-induced cell death and neuroinflammation. Since seizures and neurodegeneration are not mutually exclusive, in aim, 4, we will determine if Q-VD-OPh and diazepam together can be additive in preventing long-term sarin damage. The brain tissues will be analyzed for cytokine expression by multiplex (BioPlex) bead-based and by MALDI-Imaging mass spectrometry for localization of sarin and Q-VD-OPh. Confocal microscopy and immunostaining will be used to analyze tissue sections for specific caspases and other biomarkers of cell death. The medical and health benefits to society of this type of therapy may extend beyond a countermeasure for sarin-exposure for civilians to military applications as well as potentially for stroke, convulsive disorders and other neuropathies that result from trauma, chemical or biological insults.)
Terrorist attacks with sarin and other chemical warfare nerve agents are an ever present threat around the world. Civilian survivors of such attacks are at increased risk of problems associated with inflammation of the brain as well as brain cell death. Treatment of civilians will require development of drugs that can act within a half-hour to hours to days after sarin exposure. The research project outlined here is designed to test a novel drug (Q-VD-OPh) that can inhibit enzymes responsible for killing cells, i.e., caspases, and reduce inflammation by immune cells in the brain. Positive outcomes of the project would be less brain cell death and inflammation at both 48 hours and 14 days following sarin exposure. Further benefits will be the development of an array of inflammatory proteins and specific enzymes of cell death that can be used to drive the discovery of new drugs.