Figure 4. Oral immune system. PRRs - pattern recognition receptors, PAMPs - pathogen-associated molecular patterns, DAMPs - damage-associated molecules, TNF-α - tumor necrosis factor-alpha, NF-κB - nuclear factor kappa-light-chain-enhancer of activated B cells, TLRs - Toll-like receptors, CLRs - C-type lectin receptors, NLRs - nucleotide oligomerization domain-like receptors, RLRs - retinoic acid-inducible gene I-like receptors, ALRs - AIM2 (Absent in melanoma 2)-like receptors.