Prolonged eosinophil production after allergen exposure in IFN-gammaR KO mice is IL-5 dependent.
ABSTRACT Asthma is a T helper 2 (Th2)-driven inflammatory process characterized by eosinophilia. Prolonged airway eosinophilia is commonly observed in asthma exacerbations. Our aim was to evaluate whether eosinophilia in prolonged allergic inflammation is associated with a continuous supply of new eosinophils to the airways, and how this is regulated. Ovalbumin (OVA)-sensitized interferon-gamma receptor knockout mice (IFN-gammaR KO), known to maintain a long-lasting eosinophilia after allergen exposure, were compared to wild type (wt) controls. Animals were exposed to OVA or phosphate-buffered saline on three consecutive days, and bone marrow (BM), blood and bronchoalveolar lavage (BAL) samples were collected 24 h, 7 and 21 days later. Newly produced cells were labelled using bromodeoxyuridine (BrdU). Serum IL-5 was measured and its role was investigated by administration of a neutralizing anti-IL-5 antibody. In-vitro eosinophilopoiesis was examined in both groups by a colony-forming assay. Allergen challenge increased eosinophils in BM, blood and BAL, in both IFN-gammaR KO and wt mice, both 24 h and 7 days after the last allergen exposure. At 21 days after the last exposure, only IFN-gammaR KO mice maintained significantly increased eosinophil numbers. Approximately 50% of BAL granulocytes in IFN-gammaR KO were produced during the last 6 days. Interleukin (IL)-5 concentration was increased in IFN-gammaR KO mice, and anti-IL-5 reduced eosinophil numbers in all compartments. Increased numbers of eosinophil colonies were observed in IFN-gammaR KO mice after allergen exposure versus controls. In this model of a Th2-driven prolonged allergic eosinophilia, new eosinophils contribute to the extended inflammation in the airways by enhanced BM eosinophilopoiesis in an IL-5-dependent manner.
Article: Expansion of CD4(+) CD25(+) and CD25(-) T-Bet, GATA-3, Foxp3 and RORγt cells in allergic inflammation, local lung distribution and chemokine gene expression.[show abstract] [hide abstract]
ABSTRACT: Allergic asthma is associated with airway eosinophilia, which is regulated by different T-effector cells. T cells express transcription factors T-bet, GATA-3, RORγt 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-2'-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(+), RORγt(+) 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 RORγt(+) 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.PLoS ONE 01/2011; 6(5):e19889. · 4.09 Impact Factor