Fig. 2

LPS proinflammatory signaling pathway. LPS binds to host cell surface receptors, and TLR4 is activated and triggers two signaling cascades: The first signaling cascade involving the TIRAP and MyD88 adaptor proteins is induced in the plasma membrane, while the second signaling cascade involving the adaptor proteins TRAM and TRIF begins in the early endocytosis after eyhndocytosis. The transcription and expression of inflammatory cytokine genes are activated through many signal transduction pathways such as NF-κB and AP-1, and inflammatory response is induced to initiate the pathogenic process of bacterial infection. See the text for details. LPS, Lipopolysaccharide; LBP, LPS-binding Protein; TLR4, Toll-like Receptor 4; CD14, Cluster of Differentiation 14; MD2, Medullary Differentiation Protein 2; TRAF6, TNF Receptor-associated Factor 6; TAK,Transforming Growth Factor-β-Activated Kinase 1; IRAK, IL-1R-associated Kinase; TIRAP, TIR-domain-containing Adaptor Protein; MyD88, Myeloid Differentiation Factor 88; MAPK, mitogen-activated protein kinase; TRAM, TRIF-related Adaptor Molecule; TRIF, TIR-domain-containing Adaptor Inducing IFN-β; NF-κB, Nuclear Factor Kappa B; AP-1, Activator Protein 1. IKKi, IKK-related Kinase; IRF3, Interferon Regulatory Factor 3; IL, Interleukin (e.g., IL-1β, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17); TRAF3: TNF Receptor-Associated Factor 3; TBK: TANK-Binding Kinase; MKK3/6: Mitogen-Activated Protein Kinase Kinase 3/6; MEK1/2: MAPK/ERK Kinase 1/2; MKK4/7: Mitogen-Activated Protein Kinase Kinase 4/7; ERK1/2: Extracellular Signal-Regulated Kinase 1/2; JNK: c-Jun N-terminal Kinase; IκB: Inhibitor of NF-κB; NEMO: NF-κB Essential Modulator; CCL2: C–C Motif Chemokine Ligand 2; CXCL8: C-X-C Motif Chemokine Ligand 8. The image was created using BioRender (https://biorender.com/) with publication and licensing rights (Agreement number: TH27WBVDQD)