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Table 1 Mammalian Toll-like receptors [19,20,21]

From: Macrophage polarization in innate immune responses contributing to pathogenesis of chronic kidney disease

Toll-like receptor Expression Ligand Signaling Shaping adaptive immune responses
TLR1a Cell surface
 monocytes/macrophages
 dendritic cells
 B lymphocytes
triacyl lipopeptides
lipoproteins
lipoarabinomannan
MyD88 Th1 responses
TLR2 Cell surface
 monocytes/macrophages
 dendritic cells
 neutrophils
 mast cells
glycolipids
lipopeptides
lipoproteins
lipoteichoic acid
HSP70
β-glucan
zymosan
tGPI-mutin
MyD88 Th17 responses
Treg responses
B cell produce IgM
TLR3 Intracellular compartment
 dendritic cells
 B lymphocytes
dsRNA
poly I:C
TRIF MHC I antigen presentation
TCR co-receptor
CD8 T cell responses
TLR4 Cell surface
 monocytes/macrophages
 dendritic cells
 neutrophils
 mast cells
 B lymphocytes
lipopolysaccharides
HSPs
fibrinogen
virus structural protein
heparan sulfate
hyaluronic acid
Mannan
nickel
opioids
glycoinositolphospholipids
MyD88/TIRAP
TRIF/TRAM
Th1 responses
TNF, IL-6 production
B cell IgM production
TLR5 Cell surface
 monocytes/macrophages
 dendritic cells
flagellin
profilin (controversial)
MyD88 TCR co-receptor
Th1, Th17
B cell IgA production
TLR6a Cell surface
 monocytes/macrophages
 mast cells
 B lymphocytes
diacyl lipopeptides
lipoprotein
LTA
PGN
zymosan
β-glucan
MyD88 Th1 responses
TLR7 Intracellular compartment
 monocytes/macrophages
 dendritic cells
 B lymphocytes
imidazoquinoline compound
thiazoquinoline compound
AZ12441970
loxoribine
bropirimine
ssRNA
short dsRNA
miRNA
MyD88 TCR co-receptor
B cell maturation
Th17 responses
TLR8 Intracellular compartment
 monocytes/macrophages
 dendritic cells
 mast cells
imidazoquinoline
thiazoquinoline
loxoribine
bropirimine
ssRNA(viral)
RNA(bacterial)
miRNA
MyD88 TCR co-receptor
TLR9 Intracellular compartment
 monocytes/macrophages
 dendritic cells
 B lymphocytes
CpG DNA
hemozoin
MyD88 TCR co-receptor
B cell maturation
Th1 responses
TLR10 Cell surface
 monocytes/macrophages
 B lymphocytes
unknown MyD88 unknown
TLR11 Intracellular compartment
 monocytes/macrophages
profilin
profilin-like molecule
MyD88 Th1 responses
IL-12-dependent resistance to T. gondii
TLR12 Intracellular compartment
 monocytes/macrophages
 dendritic cells
profilin MyD88 IL-12-dependent resistance to T. gondii
TLR13 Intracellular compartment
 monocytes/macrophages
 dendritic cells
rRNA MyD88
TAK-1
Antigen cross-presentation
  1. The 13 Toll-like receptors shown here are expressed on the cell surface or within the cell (i.e., in endosomal membranes), by immune cells including monocyte/macrophages, lymphocytes, dendritic cells, and mast cells. Of note, TLR1–10 are expressed in both humans and mice, TLR11–13 are not expressed in humans, while mice express TLR11–13 with TLR10 is non-functional (pseudogene) [19]. These receptors trigger signaling via the pathways shown and the signals shape the response of other immune cells and immune functions as shown. a, indicates the TLR usually functions with formation of heterodimers, i.e., TLR1/TLR2 or TLR2/TLR6
  2. Abbreviations: CD cluster of differentiation, HSP heat shock protein, IL interleukin, MHC major histocompatibility complex, MyD88 myeloid differentiation primary response 88, TAK1 transforming growth factor-Β- activated kinase 1, TCR T-cell receptor, Th T helper, TIR Toll/interleukin-1 receptor, TNF tumor necrosis factor, TRIF TIR domain-containing adaptor protein including IFN-β, TRAM TRIF-related adaptor molecule