Medline ® Abstracts for References 1,2

Innate immunity provides a first line of host defence against infection through microbial recognition and killing while simultaneously activating a definitive adaptive immune response. Toll-like receptors (TLRs) are principal mediators of rapid microbial recognition and function mainly by detection of structural patterns that do not exist in the host. TLR2 and TLR4 were the first members of this innate immune receptor family to be strongly implicated in antibacterial host defence. Following the initial description of the mammalian TLR family, susceptibility to infection with numerous human microbial pathogens has been intensively studied using mice with engineered deletions of each of these molecules. While it has become quite clear that TLR activation is necessary for optimal host defence, a comprehensive understanding of the mechanisms by which this family of pattern recognition receptors engages protective immunity, particularly the adaptive response, is still evolving.

Toll-like receptors (TLRs) are evolutionarily conserved innate receptors expressed in various immune and non-immune cells of the mammalian host. TLRs play a crucial role in defending against pathogenic microbial infection through the induction of inflammatory cytokines and type I interferons. Furthermore, TLRs also play roles in shaping pathogen-specific humoral and cellular adaptive immune responses. In this review, we describe the recent advances in pathogen recognition by TLRs and TLR signaling.