Macrophages are an essential component of the innate immune response and adaptive immunity. These cells display a great deal of phenotypic plasticity in order to fulfill their diverse functions. The functional phenotypes of macrophage have been conceptually divided into two classes, namely the M1 and the M2 subtypes. The regulation of macrophage polarization has been extensively studied at the transcriptional, epigenetic, and translational levels and many critical protein mediators have been identified to take part in this cellular event. However, recent evidence indicates that a new type of molecule, noncoding RNAs (ncRNAs), plays a similarly important role in the differential activation of macrophages. This chapter includes a concise summary of the characterization and core protein mediators of macrophage polarization. Furthermore, it reviews in detail the biology of ncRNAs, including miRNAs and lncRNAs, and how they can participate in this process.
