IRF5 and systemic lupus erythematosus: Signaling through type I IFN (interferon) receptor (IFNαRII) is a molecular hallmark of SLE and LN, and several single-nucleotide polymorphisms related to the genes involved in the downstream signal transduction pathways (STAT4, IRF5, IRF7) seem to be involved in the expression of IFN stimulated genes (ISGs) affecting key functions of innate and acquired immunity and, possibly, of resident renal cells [12,15].