C-type lectins in immune defense against pathogens: the murine DC-SIGN homologue SIGNR3 confers early protection against Mycobacterium tuberculosis infection

Abstract

Host defense against pathogens involves various receptors expressed in cells of the immune system. Upon pathogen recognition, these proteins mediate a plethora of effector functions, such as the secretion of key protective cytokines and other immune mediators. These receptors include C-type lectins (CTLs), which are increasingly being recognized as major players in the host response to microbes. One particular CTL, DCSIGN/CD209, recognizes conserved sugar motifs in a number of viruses, parasites and bacteria. In particular, we and others have shown that DC-SIGN plays an important part in the recognition by dendritic cells and macrophages of Mycobacterium tuberculosis, the causal agent of tuberculosis in humans. Using the mouse as a model

host for M. tuberculosis, we recently showed that the DC-SIGN homologue SIGNR3 mediates protection against the tubercle bacillus, possibly through secretion of the key cytokines interleukin 6 and tumor necrosis factor. Here, we summarize and discuss these findings and their implications for the design of future studies aiming to improve our understanding of the role of DC-SIGN and other C-type lectins in immunity to mycobacteria and other pathogens.