Stimulation of allergen-loaded macrophages by TLR9-ligand potentiates IL-10-mediated suppression of allergic airway inflammation in mice.
BACKGROUND
Previously, we demonstrated that OVA-loaded macrophages (OVA-Mphi) partially suppress OVA-induced airway manifestations of asthma in BALB/c mice. In vitro studies showed that OVA-Mphi start to produce IL-10 upon interaction with allergen-specific T cells, which might mediate their immunosuppressive effects. Herein, we examined whether IL-10 is essential for the immunosuppressive effects of OVA-Mphi in vivo, and whether ex vivo stimulation of the IL-10 production by OVA-Mphi could enhance these effects.


METHODS
Peritoneal Mphi were loaded with OVA and stimulated with LPS or immunostimulatory sequence oligodeoxynucleotide (ISS-ODN) in vitro. The increase of IL-10 production was examined and, subsequently, ex vivo stimulated OVA-Mphi were used to treat (i.v.) OVA-sensitized mice. To further explore whether Mphi-derived IL-10 mediates the immunosuppressive effects, Mphi isolated from IL-10-/- mice were used for treatment.


RESULTS
We found that stimulation with LPS or ISS-ODN highly increased the IL-10 production by OVA-Mphi (2.5-fold and 4.5-fold increase, respectively). ISS-ODN stimulation of OVA-Mphi significantly potentiated the suppressive effects on allergic airway inflammation. Compared to sham-treatment, ISS-ODN-stimulated OVA-Mphi suppressed the airway eosinophilia by 85% (vs. 30% by unstimulated OVA-Mphi), IL-5 levels in bronchoalveolar lavage fluid by 80% (vs. 50%) and serum OVA-specific IgE levels by 60% (vs. 30%). Importantly, IL-10-/-Mphi that were loaded with OVA and stimulated with ISS-ODN ex vivo, failed to suppress OVA-induced airway inflammation.


CONCLUSIONS
These results demonstrate that Mphi-derived IL-10 mediates anti-inflammatory responses in a mouse model of allergic asthma, which both can be potentiated by stimulation with ISS-ODN.
Vissers
Joost L M
JL
Department of Pharmacology and Pathophysiology, Faculty of Pharmaceutical Sciences, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands. Vissers.j@future-diagnostics.nl
van Esch
Betty C A M
BC
Jeurink
Prescilla V
PV
Hofman
Gerard A
GA
van Oosterhout
Antoon J M
AJ
D000818:Animals; D016753:Interleukin-10 / Q000172:deficiency / Q000276:immunology*; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage*; D010047:Ovalbumin; D012130:Respiratory Hypersensitivity / Q000139:chemically induced / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000276:immunology*
D008070:Lipopolysaccharides; D009838:Oligodeoxyribonucleotides; C495345:TLR4 protein, human; C495371:TLR9 protein, human; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D016753:Interleukin-10; D010047:Ovalbumin