Abstract
Human Interferon (IFN) lambda 3 (IFN-λ3) and IFN-λ4 are closely linked at the IFNL locus and show association with several diseases in genetic studies. Since they are only ~30% identical to each other, to better understand their roles in disease phenotypes, comparative studies are needed. Monocytes are precursors to macrophages (monocyte-derived macrophages; MDMs) that get differentiated under the influence of various immune factors, including IFNs. In a recent study, we characterized lipopolysaccharide-activated M1 and M2-MDMs that were differentiated in presence of IFN-λ3 or IFN-λ4. In this study, we performed transcriptomics on these M1 and M2-MDMs to further understand their molecular phenotypes. We identified over 760 genes that were reciprocally regulated by IFN-λ3 and IFN-λ4, additionally we identified over 240 genes that are significantly affected by IFN-λ4 but not IFN-λ3. We observed that IFN-λ3 was more active in M2-MDMs while IFN-λ4 showed superior response in M1-MDMs. Providing a structural explanation for these functional differences, molecular modeling showed differences in expected interactions of IFN-λ3 and IFN-λ4 with the extracellular domain of IFN-λR1. Further, pathway analysis showed several human infectious diseases and even cancer-related pathways being significantly affected by IFN-λ3 and/or IFN-λ4 in both M1 and M2-MDMs.