Expansion of CD4+CD25+ and CD25- T-Bet, GATA-3, Foxp3 and RORγt Cells in Allergic Inflammation, Local Lung Distribution and Chemokine Gene Expression.

Allergic asthma is associated with airway eosinophilia, which is regulated by different T-effector cells. T cells express transcription factors T-bet, GATA-3, RORct and Foxp3, representing Th1, Th2, Th17 and Treg cells respectively. No study has directly determined the relative presence of each of these T cell subsets concomitantly in a model of allergic airway inflammation. In this study we determined the degree of expansion of these T cell subsets, in the lungs of allergen challenged mice. Cell proliferation was determined by incorporation of 5-bromo-29-deoxyuridine (BrdU) together with 7- aminoactnomycin (7-AAD). The immunohistochemical localisation of T cells in the lung microenvironments was also quantified. Local expression of cytokines, chemokines and receptor genes was measured using real-time RT-PCR array analysis in tissue sections isolated by laser microdissection and pressure catapulting technology. Allergen exposure increased the numbers of T-bet⁺, GATA-3⁺, RORγt⁺ and Foxp3⁺ cells in CD4⁺CD25⁺ and CD4⁺CD25⁺ T cells, with the greatest expansion of GATA-3⁺ cells. The majority of CD4⁺CD25⁺ T-bet⁺, GATA-3⁺, RORct⁺ and Foxp3⁺ cells had incorporated BrdU and underwent proliferation during allergen exposure. Allergen exposure led to the accumulation of T-bet⁺, GATA-3⁺ and Foxp3⁺ cells in peribronchial and alveolar tissue, GATA-3⁺ and Foxp3⁺ cells in perivascular tissue, and RORct⁺ cells in alveolar tissue. A total of 28 cytokines, chemokines and receptor genes were altered more than 3 fold upon allergen exposure, with expression of half of the genes claimed in all three microenvironments. Our study shows that allergen exposure affects all T effector cells in lung, with a dominant of Th2 cells, but with different local cell distribution, probably due to a distinguished local inflammatory milieu. [ABSTRACT FROM AUTHOR]