Sustained desensitization to bacterial Toll-like receptor ligands after resolution of respiratory influenza infection.
The World Health Organization estimates that lower respiratory tract infections (excluding tuberculosis) account for approximately 35% of all deaths caused by infectious diseases. In many cases, the cause of death may be caused by multiple pathogens, e.g., the life-threatening bacterial pneumonia observed in patients infected with influenza virus. The ability to evolve more efficient immunity on each successive encounter with antigen is the hallmark of the adaptive immune response. However, in the absence of cross-reactive T and B cell epitopes, one lung infection can modify immunity and pathology to the next for extended periods of time. We now report for the first time that this phenomenon is mediated by a sustained desensitization of lung sentinel cells to Toll-like receptor (TLR) ligands; this is an effect that lasts for several months after resolution of influenza or respiratory syncytial virus infection and is associated with reduced chemokine production and NF-kappaB activation in alveolar macrophages. Although such desensitization may be beneficial in alleviating overall immunopathology, the reduced neutrophil recruitment correlates with heightened bacterial load during secondary respiratory infection. Our data therefore suggests that post-viral desensitization to TLR signals may be one possible contributor to the common secondary bacterial pneumonia associated with pandemic and seasonal influenza infection.
Didierlaurent
Arnaud
A
Kennedy Institute of Rheumatology, Imperial College London, London W6 8LH, England, UK. a.didierlaurent@imperial.ac.uk
Goulding
John
J
Patel
Seema
S
Snelgrove
Robert
R
Low
Lionel
L
Bebien
Magali
M
Lawrence
Toby
T
van Rijt
Leonie S
LS
Lambrecht
Bart N
BN
Sirard
Jean-Claude
JC
Hussell
Tracy
T
D000818:Animals; D001424:Bacterial Infections / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016207:Cytokines / Q000276:immunology / Q000494:pharmacology; D004847:Epithelial Cells / Q000276:immunology; D005260:Female; D005408:Flagellin / Q000494:pharmacology; D008024:Ligands; D008070:Lipopolysaccharides / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D009976:Orthomyxoviridae Infections / Q000276:immunology*; D011550:Pseudomonas aeruginosa; D012137:Respiratory System / Q000276:immunology; D012141:Respiratory Tract Infections / Q000276:immunology*; D013296:Streptococcus pneumoniae; D051193:Toll-Like Receptors / Q000276:immunology*
D016207:Cytokines; D008024:Ligands; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051193:Toll-Like Receptors; D005408:Flagellin