Abstract
Macrophage activation is a dynamic process that results in diverse functional outcomes ranging from immunoregulation to inflammation. The proinflammatory, or M1, response is a complex, bimodal progression composed of a "prime," classically through IFN-gamma, and "trigger," such as LPS. To characterize the physiological response of M1 activation, a systems biology approach was applied to determine the intracellular proteome bioprofiles of IFN-gamma-and LPS-treated primary human macrophages. Our goal was to develop intracellular proteomic fingerprints to serve as novel correlates of macrophage priming and/or activation to augment the existing approaches of analyzing secreted cytokines and cell-surface protein expression. The majority of the proteome, approximately 78%, remained stable during activation, representing the core proteome. In contrast, three distinct patterns defined response proteomes: IFN-gamma-specific, LPS-specific, or IFN-gamma- and LPS-shared or M1-specific. Although steady-state expression levels of proteins involved in energy metabolism and immune response were increased during priming and triggering, changes in protein and fatty acid metabolism, signaling, and transport pathways were most apparent. Unique proteomic fingerprints distinguish among IFN-gamma-specific, LPS-specific, or M1-specific activation states and provide a clear molecular, archeological profile to infer recent history of cells, as well as correlates for chronic macrophage activation in health and disease.