210: Characterization of human interferon subtype and interferon-stimulated gene signatures

Abstract

Type I interferons (IFNs) are expressed by all nucleated cells in response to viral pathogens and modulate innate and adaptive immune responses by stimulating expression of subsets of interferon stimulated genes (ISGs). There are over 1000 ISGs, including more than 60 that are transcription factors (TFs). Type I IFNs share the same receptor complex and are comprised of multiple species, including IFN-beta, IFN-omega, and twelve subtypes of IFN-alpha. Both type I IFNs and the more recently described type III IFNs activate STAT1/STAT2 heterodimers and stimulate additional pathways that translate into antiviral and antiproliferative responses. It is not well understood how the timing and dose of each IFN contributes to these functional outcomes. We hypothesize that expression patterns of TFs will reveal unique functional responses to IFN subtypes, either alone or in combination. Therefore, we designed a quantitative-RT-PCR (qRT-PCR) array for detection of more than 50 TFs that are expressed in response to type I IFN (TF–ISGs). To test our hypothesis, we are characterizing expression of TF-ISGs by respiratory epithelial cells in response to increasing doses of types I and III IFN in a checkerboard pattern at discrete time points within 4 h. In addition, we are correlating expression patterns of TF-ISGs and type I/III IFN (measured with our previously reported qRT-PCR based assay) in human peripheral blood mononuclear cells that have been stimulated with the TLR ligands polyinosinic:polycytidylic acid (poly I:C), lipopolysaccharides (LPS), imiquimod, and CpG oligonucleotides (receptors are RIG-I/TLR3, TLR4, TLR7 and TLR9, respectively). We predict that characterizing expression signatures of IFN subtypes and TF-ISGs will provide insight towards defining functional cellular responses to specific IFN subtypes.