B, Total BALF cell numbers were increased after 3 and 6 weeks of HDM exposure compared to saline controls and were even higher after Rapa treatment compared to HDM. Rapamycin treatment prevented this increase in IgE after HDM re-exposure, but dexamethasone treatment did not. HDM-specific IgG1 was increased in HDM exposed mice after 6 weeks of rest/recovery (group 2). There was no further increase in IgG1 after HDM re-exposure. Accordingly, neither rapamycin nor dexamethasone treatment suppressed HDM-specific IgG1 levels in the serum (group 3). Open in a separate window Figure 2 Protocol 1- Allergic sensitization, inflammatory cell numbers in the BALF, and AHR NVP-BHG712 after HDM re-exposure. Total numbers of macrophages and eosinophils were increased after HDM re-exposure (group 3), but not in HDM rest NVP-BHG712 (group 2) animals in the BALF. Total neutrophil numbers in the BALF were slightly increased after HDM re-exposure in Rapa treated mice. Rapa did not suppress HDM-induced increases in eosinophils. Eosinophil numbers were lower in Dex treated mice compared to HDM re-exposed and Rapa treated groups, but still higher then saline control (Lung effector T cells (CD44+Foxp3?) were increased after HDM re-exposure and attenuated by Rapa and Dex (CD44+Foxp3? effector cells, as a percentage of total CD4+ T cells were increased in all HDM re-exposed groups and not suppressed by Rapa or Dex (Levels of INF- appeared to be lower after rapamycin (Rapa) treatment in HDM re-exposed mice, but were not statistically different between any of the groups (P-S6, a downstream mediator of mTOR complex 1 signaling, was increased in HDM re-exposed mice (group 3) and this was blocked by rapamycin (Rapa) treatment (Total CD4+ T cells were increased after 6 weeks of HDM and suppressed by rapamycin (Rapa) and dexamethasone (Dex) (CD69+Foxp3? activated T cells, when assessed as a percentage of total CD4+ T cells, were increased after HDM exposure and unaffected by Rapa and Dex (CD44+Foxp3? effector T cells, when expressed as a percentage of total CD4+ T cells, were increased after HDM exposure and attenuated by Rapa and Dex (Total lung regulatory T cells (Foxp3+CD25+) were increased after chronic HDM exposure and suppressed by Rapa and Dex (The ratio of regulatory T cells Foxp3+CD25+ to CD44+Foxp3? effector T cells was decreased in HDM exposed mice compared to saline controls (they still suggest that rapamycin could have direct effects on B cells, which could account for the decreases in IgE levels in our model and therefore reduce sensitization to HDM, despite increased IL-4. When we assessed B cells in the lung tissue, there was a trend towards a decrease in B cells in both studies after rapamycin treatment. Despite being non-significant, we cannot exclude that this minor decrease in lung B cell levels could contribute to the observed decrease in IgE levels. The source of the IL-4 increase is unclear in our model since T cells, which are one of the primary sources of IL-4, were reduced. Other cells including eosinophils, basophils, and mast cells can secrete IL-4 , but whether these cells are playing a role in enhancing IL-4 levels in our model is unclear. Also in our study, eotaxin 1, an NVP-BHG712 important epithelial cell derived eosinophil chemokine, remained elevated in the BALF with rapamycin treatment, which may explain why eosinophil numbers were not suppressed. This NVP-BHG712 was also true in our previous acute study in which Mouse monoclonal to CEA rapamycin treatment did not suppress airway inflammation nor eotaxin 1 levels once sensitization was established . More recent studies have indicated an important role for regulatory T cells in the resolution of allergic airway disease , , ..