Methods: Female Balb/c mice were sensitized and challenged with ovalbumin or PBS for a total of 20 days. Lung tissues from both groups were harvested and examined for protein and mRNA expression of TREM-2. DCs were sorted using autoMACS and FACS to determine TREM-2 -positive lung DC subsets.
Results: Sensitization and challenge with ovalbumin resulted in increased airway hyper-responsiveness, mucus secretion, airway eosinophilia, and total IgE in serum and BALF. TREM-2 mRNA expression in whole lung was significantly higher (p<0.05) in the allergen-sensitized and challenged mice which was associated with increased protein expression in the lungs. Analysis of CD11c+MHC-IIhi lung DCs revealed that the OVA-sensitized and challenged group had greater density of cells that were CD11b+CD103- and CD11b+CD103+ compared to the control. TREM-2 expression was significantly higher (p<0.01) on the CD11b+CD103+ cells when compared to the CD11b+CD103- cells.
Conclusions: Allergen-sensitization and challenge increases the expression of TREM-2 in the airways and on the surface of lung DC subsets which may contribute to increased airway inflammation in allergic asthma.