Interferon regulatory factor 5 expression levels regulate murine lupus in a type-I interferon-independent manner

ABSTRACT: Polymorphisms in the transcription factor interferon regulatory factor 5 (IRF5) are strongly associated in human genetic studies with an increased risk of developing the autoimmune disease systemic lupus erythematosus. However, the biological role of IRF5 in lupus pathogenesis, if any, is not known. In this study we show that IRF5 is absolutely required for disease development in the FcgRIIB-/-Yaa and FcgRIIB-/- lupus models. In contrast to IRF5-sufficient FcgRIIB-/-Yaa mice, IRF5-deficient FcgRIIB-/-Yaa mice do not develop lupus manifestations and have a phenotype comparable to wildtype mice. Strikingly, full expression of IRF5 is required for the development of autoimmunity, as IRF5-heterozygotes had dramatically reduced disease. One effect of IRF5 is to induce the production of the type I interferon IFN-gamma, a cytokine implicated in lupus pathogenesis. To address the mechanism by which IRF5 promotes disease, we evaluated FcgRIIB-/-Yaa mice lacking the type I interferon receptor IFNAR1. Unlike the IRF5-deficient and IRF5-heterozygous FcgRIIB-/-Yaa mice, IFNAR1-deficient FcgRIIB-/-Yaa mice maintained a substantial level of residual disease. Furthermore, in FcgRIIB-/- mice lacking Yaa, IRF5-deficiency also markedly reduced disease manifestations, indicating that the beneficial effects of IRF5 deficiency in FcgRIIB-/-Yaa mice are not due only to inhibition of the enhanced TLR7 signaling associated with the Yaa mutation. Overall, we demonstrate that IRF5 plays an essential role in lupus pathogenesis in murine models and that this is mediated through pathways beyond that of type I interferon production. The fact that even IRF5 heterozygous mice developed minimal disease makes IRF5 a particularly attractive therapeutic target. Serum samples from a total of 70 mice were run on the Utz Lab Whole Protein Autoantigen Array V1.0 (a single-color platform) in order to profile their autoantibodies against a library of autoimmune antigens. All samples were run once with no replicates. The samples consisted of the following groups: For data appearing in Figure 3D, illustrating that mice lacking IRF5 have their autoantibody levels significantly affected: R2Yaa IRF5+/+: 12 R2Yaa IRF5+/-: 11 R2Yaa IRF5-/-: 14 C57BL/6 ("WT" control): 13 Total mice (arrays) for this group: 50 For data appearing in Figure 6D, illustrating that mice lacking Ifnar1 do not have their autoantibody levels significantly affected: R2Yaa Ifnar+/+: 10 R2Yaa Ifnar-/-: 10 Total mice (arrays) for this group: 20

ORGANISM(S): Mus musculus

SUBMITTER: Chih Long Liu 

PROVIDER: E-GEOD-17926 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress