ABSTRACT
This chapter reviews the contribution of pattern recognition receptors (PRRs) and nucleotide-binding oligomerization domain-like receptors (NLRs) to innate immune defense of the intestinal mucosa, focusing on toll-like receptors (TLRs) and NLRs. It discusses the genetic imbalances in pattern recognition that may contribute to inflammatory bowel diseases. Pathogen recognition is accomplished by PRRs that recognize highly conserved, pathogen-associated molecular patterns (PAMPs). TLRs comprise a major group of PRRs and have a key role in the innate cell recognition of PAMPs, leading to the induction of pro- and anti-inflammatory genes, phagocytosis, and control of adaptive immune responses. TLRs are expressed predominantly on cells that are the first to encounter the invading threat. NLRs comprise a second group of evolutionarily conserved host defense PRRs encoded in both animal and plant genomes. The interaction between commensal microbes and the intestinal epithelium induces TLR signaling that promotes barrier preservation, cell survival, and restitution.
