| Receptor Number |
Expression |
Recognition site |
Target Organism |
| TLR 1 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium endocervix, ectocervix, vagina, uterine NK cells, vascular endothelial cells, and smooth muscle cells in cervical stroma as well as uterus [12] |
LPS, PGN, flagellin |
Bacteria [60,84] |
| TLR 2 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, cervix, vagina, smooth muscle cells of cervix and vagina, endometrial stromal cells, uterine NK cells. Highest levels in fallopian tubes and cervix [12] |
LPS, PGN, flagellin (heterodimers in TLR1 or TLR6 complexes recognize microbial components) |
Bacteria [85,86] |
| TLR 3 |
Constitutive expression in tissue samples from fallopian tubes, endometrium, cervix, and vagina. Other expression in epithelial cells of fallopian tubes, endometrium endocervix, ectocervix, and vagina. Also in stromal fibroblasts of vagina, endocervix and in uterine NK cells [12] |
Nucleic acids
(ds RNA) |
Virus[60,87] |
| TLR 4 |
Constitutive expression in fallopian tubes, endometrium cervix, vagina, declines from fallopian tubes to vagina, although presence in epithelial cells debated [12] |
LPS, heat shock protein 60, glycoinositolphospholipids of protozoa, viral envelope proteins, activates NK and other immune response [84] |
Bacteria, Virus [84] |
| TLR 5 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, vagina, endocervix [12] |
flagellin |
Bacteria [88] |
| TLR 6 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, endocervix, ectocervix, vagina, uterine NK cells and stroma fibroblasts in vagina [12] |
LPS, PGN, flagellin |
Bacteria [12]
Fungi [60] |
| TLR 7 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, cervix, vagina, uterine NK cells and endometrial stroma [12] |
Nucleic acid (ss RNA) |
Virus [23,89] |
| TLR 8 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, cervix, vagina, and endometrial stroma [12] |
Nucleic acid
(ss RNA) |
Virus [23] |
| TLR 9 |
Constitutive expression in epithelial cells of fallopian tubes, endometrium, cervix, vagina, and endometrial stroma [12] |
Nucleic acid (unmethylated deoxytidyl-phosphate-deoxyguanosine components of both bacterial and viral genomes) |
Bacteria and viruses [90] |
| TLR 10 |
Constitutive expression in fallopian tubes, human NK cells; possibly in endometrial epithelia and stroma [12,91] |
Ligand unknown |
Recognition unknown [12] |
ds = double-stranded; LPS = lipopolysaccharide; NK = natural killer; PGN = peptidoglycan; RNA = ribonucleic acid; ss = single-stranded; TLR = toll-like receptor |
