Bacterial-induced protection against allergic inflammation through a multicomponent immunoregulatory mechanism.

Abstract

BACKGROUND:

Airborne microbial products have been reported to promote immune responses that suppress asthma, yet how these beneficial effects take place remains controversial and poorly understood.

METHODS:

We exposed mice to the bacterium Escherichia coli and subsequently induced allergic airway inflammation through sensitization and intranasal challenge with ovalbumin.

RESULTS:

Pulmonary exposure to the bacterium Escherichia coli leads to a suppression of allergic airway inflammation. This immune modulation was neither mediated by the induction of a T helper 1 (Th1) response nor regulatory T cells; however, it was dependent on Toll-like receptor 4 (TLR4) but did not involve TLR desensitisation. Dendritic cell migration to the draining lymph nodes and activation of T cells was unaffected by prior exposure to E. coli, while dendritic cells in the lung displayed a less activated phenotype and had impaired antigen presentation capacity. Consequently, in situ Th2 cytokine production was abrogated. The suppression of airway hyper-responsiveness was mediated through the recruitment of gd T cells; however, the suppression of dendritic cells and T cells was mediated through a distinct mechanism that could not be overcome by the local administration of activated dendritic cells, or by the in vivo administration of tumour necrosis factor a.

CONCLUSION:

Our data reveal a localized immunoregulatory pathway that acts to protect the airways from allergic inflammation.

• Authors: Chiara Nembrini, Anke Sichelstiel, Jan Kisielow, Michael Kurrer, Manfred Kopf, Benjamin J Marsland
• Journal: Thorax (Thorax) Vol. 66 Issue 9 Pg. 755-63 (Sep 2011) ISSN: 1468-3296 [Electronic] England
• PMID: 21422039 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Outer Membrane Proteins
• TLR protein, bacteria

Topics

• Animals
• Asthma (immunology, pathology, prevention & control)
• Bacterial Outer Membrane Proteins (immunology, metabolism)
• Bronchoalveolar Lavage Fluid (cytology, immunology)
• Dendritic Cells (immunology)
• Disease Models, Animal
• Escherichia coli (immunology, isolation & purification, metabolism)
• Flow Cytometry
• Immunomodulation (immunology)
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Th2 Cells (immunology)