Impact/Purpose:

Specifically, this work will support efforts to (1) Identify mechanisms of toxicity for PM constituents/ sources; (2) Develop methods for studying mechanisms of effects in tissue from human subjects exposed to PM; and (3) Apply a molecular profiling and/or proteomics approach to identifying PM-induced changes in humans and animals.

Description:

Exposure of humans and animals to PM results in a number of cellular and physiological changes. However, these may represent only a small subset of the total response to PM since end points are typically chosen on the basis of past experience (the so-called "looking for your keys under the lamp post effect"). More global approaches using techniques such as micro-array have recently identified several genes and cellular pathways that are activated following exposure to PM that were not previously known. This powerful approach can potentially alter our thinking about the mechanisms by which PM causes its effects. However, micro-array technology currently only examines gene expression, not actual proteins, and those cells in which the genes are activated must be studied. This severely limits analysis of plasma or serum from humans or animals exposed to PM since those proteins could have been produced by a number of different cell types (e.g. liver cells, endothelial cells, epithelial cells, macrophages). We are currently using a proteomics instrument recently purchased from Ciphergen to analyze plasma proteins in humans exposed to CAPS. A pilot study of 4 subjects has tentatively tagged several plasma proteins that are only present following exposure to CAPS. A more extensive analysis of a larger sample size is currently underway, after which we will attempt to specifically identify the proteins. Our immediate goal is to identify plasma proteins which are up or down-regulated in humans exposed to CAPS. We anticipate that if there are changes in proteins that have not previously been studied, it will result in the generation of new hypotheses about mechanisms by which PM exerts its effects. It is also our intention to see if changes in specific proteins can be associated with difference in response to PM first in controlled exposure and then in panel studies (i.e. do "responders" have a different phenotype than non-responders). Proteomics approaches also provide a complementary approach to micro-array for in vitro toxicology studies. They allow one to study proteins rather than genes, and also allow one to study post-translational processes. For example, we are currently studying proteins that are phosphorylated following exposure of cells to PM. We also anticipate identifying PM-induced proteins which bind to specific DNA control sequences and proteins which bind to specific cell surface receptors. Finally, we will use a model in vitro epithelial cell system to directly compare genes induced by PM (using micro-array) with proteins induced (using the Ciphergen machine).

Record Details: