Proteome and Secretome Analysis Reveals Differential Post-Transcriptional Regulation of Toll-Like Receptor Responses

Toll-like receptors (TLRs) are essential sensors in innate immunity and among the first to detect invading pathogens. Many studies of TLR responses have focused on the intracellular signaling events that occur upon receptor stimulation. However, proteins released from the cell play a key role in cell-cell communication during an immune response. We have used mass spectrometry-based proteomic methods to investigate both the intracellular and extracellular responses of macrophages stimulated with individual TLR2, TLR4, and TLR7 ligands and whole pathogens. We performed global quantitative analyses of the mouse macrophage proteome and secretome using stable isotope labeling with amino acids and high-resolution mass spectrometry.