The long-term objective of this proposal is to gain an understanding of cellular activation mechanisms involved in septic shock. Septic shock results from the severe inflammation induced by conserved and often integral structural components of microbes, such as the lipopolysaccharides (LPS) of Gram-negative bacteria. The inflammatory process is characterized by an initial and then sustained phase that normally ends when there is a resolution of the inflammatory trigger. The activation of macrophages by these specific pattern molecules of microbial origin is an important part of the inflammatory cascade. A major characteristic of macrophage activation is the production of pro-inflammatory cytokines, bioactive lipids, degradative enzymes, etc. Great progress has been made in defining the receptors for many microbial pattern molecules and the signaling mechanisms of these receptors in macrophages and other cells. However, the molecular mechanisms that lead to the sustention and end of cellular activation are largely unknown. The major focus for this grant period is to study the regulation mechanisms during the sustained and ending phases of macrophage activation. We will study the effects of early changes in the expression of signaling molecules, transcription factors, and microRNA (miRNA) on late gene expression in activated macrophages. A combination of cellular biology, molecular biology, biochemical, and genetic approaches will be used to study this topic. The proposed work will fill in some gaps in our understanding of the cellular activation mechanisms that occur in sepsis. Since extended inflammation is believed to contribute to the severe inflammation accompanying septic shock, new insights into the means by which inflammatory activation of cells are sustained and ended will eventually lead to an understanding of how the duration and intensity of inflammation are controlled in vivo. Understanding the process of inflammatory responses will help to develop therapeutic procedures for the treatment of septic shock. PUBLIC HEALTH RELEVENCE: The objective of this proposal is to gain an understanding of cellular activation mechanisms involved in septic shock. The current focus is to understand whether and how the early changes in the expression of signaling effector proteins, transcription factors, and microRNA (miRNA) affect late gene expression, as well as to understand the role of the p38 family members in macrophage activation. The proposed work will fill in some gaps in our understanding of the cellular activation mechanisms that occur in sepsis, which should provide useful information for developing new treatments for septic shock.