Table 1.
Role of Toll-like Receptors in Bacterial Lung Infection Using Gene-Deficient Mice
| Pneumonia Caused by | Phenotype* |
Adaptive Immune Response† | Reference | |||||
|---|---|---|---|---|---|---|---|---|
| Survival | Inflammation‡ | Neutrophil Influx§ | Lung Bacterial Burden | Bacterial Dissemination|| | ||||
| TLR | ||||||||
| TLR2 | Streptococcus pneumoniae | NA | ↓ | NA | NA | NA | ND | 8 |
| Legionella pneumophila | ↓ | NA | NA | ↑ | NA | 10 | ||
| Acinetobacter baumannii | NA | NA, IL-6 (↑) | NA | ↑ | NA | ND | 12 | |
| Mycobacterium tuberculosis (acute) | NA | ↓ | ND | NA | NA | NA on T-cell activation | 15 | |
| Mycobacterium tuberculosis (chronic) | ↓ | ↑ | ↑ | ↑ | ND | ↓ Treg accumulation | 16 | |
| Brucella melitensis | NA | ND | ND | ↑ | NA | ↓ IgG production | 11 | |
| Francisella tularensis | ↓ | ↓ | ND | ↑ | ↑ | ND | 13 | |
| Burkholderia pseudomallei | ↑ | ↓ | ND | ↓ | ↓ | ND | 14 | |
| TLR4 | Acinetobacter baumannii | ND | ↓ | ↓ | ↑ | ↑ | ND | 22 |
| Haemophilus influenzae | ND | ↓ | ↓ | ↑ | ND | ND | 20 | |
| Klebsiella pneumoniae | ↓ | ↓ | ND | ↑ | ↑ | ND | 19 | |
| Klebsiella pneumoniae | ND | ND | ND | ND | ND | Induces IL-17 production from both CD4+ and CD8+ T cells | 26 | |
| Streptococcus pneumoniae | ↓ | ↑ | ND | ↑ | NA | ND | 23 | |
| Mycobacterium tuberculosis (acute) | NA | NA | ND | NA | ND | ND | 15 | |
| Mycobacterium tuberculosis (chronic) | ↓ | ↑ | ↑ | ↑ | ↑ | ND | 25 | |
| TLR5 | Legionella pneumophila | ND | ↑ | ↓ | NA | ND | ND | 30 |
| TLR9 | Klebsiella pneumoniae | ↓ | ND | NA | ↑ | ↑ | ↓ DC accumulation and activation | 31 |
| Legionella pneumophila | ↓ | ND | NA | ↑ | NA | ↓ Accumulation and activation of DC and CD4+ T cells | 32 | |
| Staphylococcus aureus | ↑ | ND | NA | ↓ | ND | ND | 34 | |
| Pseudomonas aeruginosa | ↑ | ↓ | ↑ | ↓ | ND | ND | 33 | |
| TLR adaptors |
||||||||
| MyD88 | Escherichia coli | ND | ND | ↓ | ND | ND | ND | 74 |
| Klebsiella pneumoniae | ↓ | ↓ | ↓ | ↑ | ↑ | ND | 27 | |
| Legionella pneumophila | ↓ | ↓ | ↓ | ↑ | ↑ | ND | 10 | |
| Pseudomonas aeruginosa | ↓ | ↓ Early, ↑ late | ↓ | ↑ | ↑ | ND | 9 | |
| Staphylococcus aureus | NA | NA | ↓ | NA | NA | ND | 9 | |
| Burkholderia pseudomallei | ↓ | NA | ↓ | ↑ | ↑ | ND | 40 | |
| TIRAP/Mal | Klebsiella pneumoniae | ↓ | ↓ | ↓ | ↑ | ↑ | ND | 75 |
| Pseudomonas aeruginosa | NA | NA | NA | NA | NA | ND | 75 | |
| TRIF | Escherichia coli | NA | ND | ↓ | ↑ | ↑ | ND | 74 |
| Klebsiella pneumoniae | ↓ | ↓ | ↓ | ↑ | ↑ | ND | 27 | |
| Burkholderia pseudomallei | NA | ND | ND | ND | ND | ND | 40 | |
Definition of abbreviations: DC = dendritic cell; NA = not altered significantly; ND = not determined; TIRAP = Toll-IL-1R domain-containing adapter protein; TLR = Toll-like receptor; Treg = regulatory T cell; TRIF = TIR-domain–containing adapter-inducing IFN-β.
Phenotype was determined using gene-deficient (or mutant) mice after infection.
Adaptive immune response was determined using gene-deficient (or mutant) mice after infection.
Inflammation was determined in lungs based on different parameters after infection.
Neutrophil influx was determined in bronchoalveolar lavage fluid and/or lung parenchyma.
Bacterial dissemination was ascertained as bacterial presence or growth in blood, spleen, or liver.