Search

Summary: Helper T (Th) and regulatory T (Treg) cell differentiation programs promote the eradication of pathogens, while minimizing adverse immune reactions. Here, we found that Nr4a family of nuclear receptors supports Treg cell induction and represses Th1 and Th2 cell differentiation from naive CD4+ T cells. Nr4a factors are transiently induced in CD4+ T cells immediately after antigen stimulation, thereby mediating epigenetic changes. In differentiating Treg cells, Nr4a factors mainly upregulated the early responsive genes in the Treg cell-specifying gene set, either directly or in cooperation with Ets family transcription factors. In contrast, Nr4a factors repressed AP-1 activity by interrupting a positive feedback loop for Batf factor expression, thus suppressing Th2 cell-associated genes. In an allergic airway inflammation model, Nr4a factors suppressed the pathogenesis, mediating oral tolerance. Lastly, pharmacological activation of an engineered Nr4a molecule prevented allergic airway inflammation, indicating that Nr4a factors may be novel therapeutic targets for inflammatory diseases.

High fat diet (HFD) decreases the lifespan of mice, and is a risk factor for several human diseases. Here, we investigated the effects of a HFD on lung epithelial and stem cells and its interaction with aging. Young and old mice were fed with either a standard diet (SD) or a HFD then their trachea and lung were examined for histological changes, inflammation, and mitochondrial function. Their stem cell function was examined using the in vitro organoid/colony forming efficiency (CFE) assay. Aging reduced the number of tracheal basal and alveolar type-2 (AT2) cells. HFD significantly increased the number of AT2 cells. Aging also caused a significant increase in lung inflammation, and HFD caused a similar increase, in young mice. Aging reduced mitochondrial mass and function, and increased reactive oxygen species. In young mice, HFD caused mitochondrial changes similar to the aging-induced changes. Organoid culture of tracheal and lung epithelial cells collected from both young and old HFD-fed mice showed higher CFE compared to SD-fed mice. Switching the HFD to low calorie/fat diet (LCD) efficiently reversed several of the HFD-induced effects. Thus, HFD induces several histological, inflammatory, and functional changes in the lung, and exacerbates the aging-induced lung inflammation and mitochondrial deterioration. LCD can reverse many of the HFD-induced effects. Keywords: High fat diet, Aging, Alveolar cells, Lung stem cells, Mitochondria, Calorie restriction

Background: Interleukin (IL)-23/Th17 axis plays an important role in the pathophysiology of asthma and eczema, however, there are some conflicting data about the effects of this system on allergic airway inflammation. In the present study, we aim to dissect the spatiotemporal differences in the roles of IL-23 in an epicutaneously-sensitized asthma model of mice. Methods: C57BL/6 mice were sensitized to ovalbumin (OVA) by patch application on the skin, followed by airway exposure to aerosolized OVA. During sensitization and/or challenge phase, either a specific neutralizing antibody (Ab) against IL-23 or control IgG was injected intraperitoneally. On days 1 and 8 after the final OVA exposure, airway inflammation and responsiveness to methacholine, immunoglobulin levels in serum, and cytokine release from splenocytes were evaluated. Skin Il23a mRNA levels were evaluated with quantitative RT-PCR. Results: Patch application time-dependently increased the expression of Il23a mRNA expression in the skin. Treatment with the anti-IL-23 Ab during sensitization phase alone significantly reduced the number of eosinophils in bronchoalveolar lavage fluids and peribronchial spaces after allergen challenge compared with treatment with control IgG. Anti-IL-23 Ab also reduced serum levels of OVA-specific IgG1. In contrast, treatment with the anti-IL-23 Ab during the challenge phase alone rather exacerbated airway hyperresponsiveness to methacholine with little effects on airway eosinophilia or serum IgG1 levels. Conclusions: IL-23 expressed in the skin during the sensitization phase plays an essential role in the development of allergic phenotypes, whereas IL-23 in the airways during the challenge phase suppresses airway hy- perresponsiveness.

Background: The role of interleukin (IL)-23 in asthma pathophysiology is still controversial. We examined its role in allergic airway inflammation in response to two distinct antigens using IL-23-deficient mice. Methods: Allergic airway inflammation was evaluated in wild-type and IL-23p19−/− mice. Mice were sensitized to ovalbumin (OVA) or house dust mite (HDM) by intraperitoneal injection of antigen and their airways were then exposed to the same antigen. Levels of antigen-specific immunoglobulins in serum as well as cytokines in bronchoalveolar or peritoneal lavage fluid and lung tissue were determined by enzyme-linked immunosorbent assay and/or quantitative polymerase chain reaction. Results: Deficiency of IL-23p19 decreased eosinophils and Th2 cytokines in bronchoalveolar lavage fluid (BALF) of OVA-treated mice, while it increased BALF eosinophils of HDM-treated mice. Peritoneal injection of OVA with alum, but not of HDM, induced local synthesis of IL-6, IL-10, and IL-23. Systemic production of antigen-specific IgG1 was partially dependent on IL-23. In contrast, airway exposure to HDM, but not to OVA, induced IL-23p19 mRNA expression in the lungs. In IL-23p19-deficient mice, HDM-exposed lungs did not exhibit the induction of IL-17A, which negatively regulates eosinophilic inflammation. Conclusions: Different antigens induced IL-23 at different part of the body in our similar asthma models. Endogenous IL-23 production at the site of antigen sensitization facilitates type-2 immune responses, whereas IL-23 production and subsequent IL-17A synthesis in the airways suppresses allergic inflammation.