Immunomodulatory effects of feeding with Bifidobacterium longum on allergen-induced lung inflammation in the mouse.
BACKGROUND
The intestinal microbiota has important effects on host immune responses and feeding with certain commensal organisms has anti-inflammatory effects in a variety of diseases, including experimental asthma. The aim of the current study was to examine how robust the effects of feeding with the commensal strain, Bifidobacterium longum (Bif) were on the pulmonary responses to allergen sensitization and challenge.


METHODS
BALB/c mice were given two intraperitoneal injections of ovalbumin (10 μg in alum) on days 0 and 7 and were fed daily with Bif or vehicle from days 0-14. Challenges with ovalbumin (10 μg) were administered intra-nasally once on day 14 or three times on days 14, 15 and 16 and the lung inflammatory response was assessed one day later.


RESULTS
Bif feeding attenuated airway inflammation following a single ovalbumin challenge, reducing bronchoalveolar lavage (BAL) eosinophilia, BAL fluid IL-4 protein and BAL cell IL-4 and IFN-γ mRNA levels. However, BAL fluid IL-5 protein was increased. There was an accompanying increase in lung regulatory T cells assessed by flow cytometry. Responses to triple challenge with ovalbumin were much less affected by Bif feeding, including unchanged cytokine levels, ovalbumin-specific IgE and airway hyperresponsiveness to methacholine.


CONCLUSIONS
These results show modest immunoregulatory effects of oral feeding with Bif with inhibition of certain components of allergen-induced airway inflammation that is associated with the expansion of regulatory T cells in the lungs but that is overcome by repeated allergen exposure.
Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Cork, Ireland.
John
J
MacSharry
Caitlin
C
O'Mahony
Karim Hamdy
KH
Shalaby
Barbara
B
Sheil
Harry
H
Karmouty-Quintana
Fergus
F
Shanahan
James G
JG
Martin
D000485:Allergens / Q000276:immunology; D000818:Animals; D001644:Bifidobacterium; D016535:Bronchial Hyperreactivity / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D004195:Disease Models, Animal; D018836:Inflammation Mediators / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin; D011014:Pneumonia / Q000139:chemically induced / Q000382:microbiology / Q000503:physiopathology*; D019936:Probiotics / Q000494:pharmacology*
D000485:Allergens; D018836:Inflammation Mediators; D010047:Ovalbumin