[Recognition of pathogens by innate immunity]

The contributions of NK (natural killer) cells, DCs (dendritic cells), PRRs (pathogen recognition receptors), and PAMPs (pathogen-associated molecular patterns) recognized by PRRs as well as the participation of intracellular signaling pathways in innate immunity are shown. The possible involvement of a newly described group of immune cells, IKDCs (interferon-producing DCs), in innate immunity which show both NK and DC activity is presented. This review describes the mechanisms of innate immunity with the likely participation of autophagy initiated after endosomal TLR7 (Toll-like receptor 7) activation. Autophagy is able to remove intracellular bacteria or viruses by stimulating type I IFNs (interferons). A balance between PRR, especially TLR, activation and inactivation is crucial to avoid an excessive inflammatory response, as occurs in autoimmune and infectious diseases. Apart from SOCS (suppressor of cytokine signaling proteins) or Tollip (Toll-interacting protein), the possible contribution of microRNA in the regulation of innate immunity is described. The discovery of miRNA is one of the major scientific milestones in recent years and has revolutionized the way we look at many different modes of gene regulation.