Discovery of Novel Therapeutics Against Shiga and Ricin Toxins

点击翻译按钮获取中文摘要

Shiga toxin (Stx) and ricin, produced by certain E. coli strains and the plant Ricin communicus, respectively, are important causes of human disease and are potential agents of biowarfare. Therapeutic options for persons exposed to these toxins are limited. In particular, antibiotics have no role following ricin exposure and are contraindicated in patients exposed to SIX-producing E. coli. Similarly, there are no specific therapeutics for their inactivation, nor for inhibition of the cell death caused by these toxins. In order to identify potential therapies against Stx, ricin, and other toxins, we previously developed a luciferase-based high throughput screen (HTS) for small molecule inhibitors of toxin susceptibility. Funded by the MRCE, we have thusfar identified several inhibitors of toxin transport. Among these are compounds that inhibit the cytotoxic activity of ricin and Stx against human cells. At the Harvard Institute of Cellular and Chemical Biology (ICCB) and the NIH Molecular Libraries Screening Network (MLSCN), we are undertaking a screen of approximately 200,000 additional compounds to identify those that inhibit toxin transport. In tandem with the above screen, we developed and optimized an HTS assay for the identification of compounds that directly inhibit the enzymatic activity of Stx and ricin. Approximately 100,000 compounds will be screened for their ability to inhibit Stx and ricin activity. These compounds will be prioritized and evaluated for their potential as therapeutic agents. The most promising of these compounds will be subjected to structure-guided optimization of potency, efficacy and pharmacologic properties. Finally, efficacy and toxicity will be determined and optimized in a small animal model of Stx- and ricin-mediated disease. Compounds that inhibit enzymatic activity will be attractive therapeutic candidates. In future studies, the most effective and tolerated of these compounds will be structurally optimized for tolerability, effectiveness, and favorable pharmacological properties both in vitro and in vivo. This project fits well with the mission of the MRCE and has major implications for public health. In the went of their intentional release as bioweapons, these toxins could significance morbidity and mortality. We propose to identify and optimize toxin inhibitors compounds as the first drugs that could be used to prevent or treat individuals exposed to these toxins.