The transcription factor interferon regulatory factor 5 (IRF5) has previously been implicated in the onset of the autoimmune disorder systemic lupus erythrematosus (SLE). Elevated levels of inflammatory cytokines are a common characteristic of SLE, and are believed to contribute to both autoantibody production and wide spread inflammation.  Upon activation, cytoplasmic IRF5 translocates to the nucleus to initiate pro-inflammatory gene transcription.   To achieve nuclear translocation, IRF5 relies on two nuclear localization signals located in the N’ and C’ termini of the protein.  To investigate the therapeutic potential of IRF5 inhibition, we have developed two unique cell-penetrating peptides.  Upon treatment with these inhibitors, we show IRF5 is excluded from the nucleus, while IRF7 and NFkB nuclear translocation were unaffected following activation.  We have investigated the impact of IRF5 inhibition in a variety of cell lines as well as primary peripheral blood mononuclear cells. The inhibitors show no impact on cell cycle, viability, or IRF5 protein levels.  As IRF5 has previously been linked to expression of IgG subtypes in mice, we utilized the IRF5 inhibitors to examine the impact of IRF5 inhibition in the Ramos B cell line.  Interestingly, we found no impact of the inhibitors on surface IgG expression.  In THP1 cells, however, a marked reduction in inflammatory cytokine expression was seen following stimulation with LPS and IFNg.   These data highlight the potential of targeting IRF5 in order to reduce the inflammatory signature characteristic of SLE patients.