Table 1.

Pathogenic PAMPs, host cell PRRs, and relevant signaling pathways.

PAMPs	Class of PRR	PRR location	Signaling pathway
Lipopolysaccharide (LPS)	TLR4, NLRP3	Cell membrane surface/cytoplasmic	NF-κB signaling, NLRP inflammasome, TRIF signaling
Outer membrane protein (Omp)	TLRs	Cell membrane surface	NF-κB signaling
Porin	TLRs	Cell membrane surface	NF-κB signaling
Lipoteichoic acid (LTA)	TLRs	Cell membrane surface	NF-κB signaling
Peptidoglycan	TLRs, NLRs NLRPs	Cell membrane surface/cytoplasmic	NF-κB signaling, NLRP inflammasome
Flagellin	TLR5, NLRC4	Cell membrane surface/cytoplasmic	NF-κB signaling
Nucleic acid	TLRs, NLRs, NLRPs, AIM2, STING	Cell membrane surface/cytoplasmic	NF-κB signaling, IRF3 signaling, NLRP inflammasome, AIM inflammasome, IRF3 signaling
Protein	TLRs, NLRs, NLRPs	Cell membrane surface/cytoplasmic	NF-κB signaling, MAPK signaling, IRF signaling, NLRP inflammasome

TLR, toll-like receptor; NLR, nucleotide-binding oligomerization domain-like receptor; NLRP, NLR thermal protein domain associated protein; AIM, absent in melanoma; STING, stimulator of interferon genes.