Janus kinases (Jaks) play an important role in signal transduction via cytokine receptors. Tyk2 is a Janus kinase, and we developed tyk2-deficient mice to study the requirement for tyk2 in vivo. Tyk2-deficient mice show no overt developmental abnormalities; however, they display a lack of responsiveness to a small amount of IFNalpha, although a high concentration of IFNalpha can fully transduce its signal even in the absence of tyk2. Furthermore, IL-12-induced T cell function is defective in these mice. In contrast, these mice respond normally to IL-6 and IL-10, both of which activate tyk2 in vitro. These observations demonstrate that tyk2 plays only a restricted role in mediating IFNalpha-dependent signaling while being required in mediating IL-12-dependent biological responses.

Background: IL-6 signaling is a key component of inflammatory diseases.Results: Modified DNA aptamers that inhibit IL-6 signaling were discovered and optimized.Conclusion: Modified aptamers are stable in serum and block the interaction of IL-6 with its receptor IL-6Rα.Significance: Modified aptamers are a new class of antagonist with properties potentially suitable for clinical treatment of inflammation.

Glucocorticoids, such as dexamethasone (Dex), have been used as in vitro inducers of adipogenesis. However, the roles of the glucocorticoid receptor (GR) in adipogenesis have not been well characterized yet. Here we show that inhibition of GR activity using the GR antagonist RU486 prevents human mesenchymal stem cell (hMSC) and mouse embryonic fibroblast (MEF) differentiation into adipocytes. Moreover, in MEFs isolated from GR knockout (GRnull) and GRdim mice deficient in GR DNA-binding activity, adipogenesis was blocked. We identified GRE sites in the first intron of KLF15 by bioinformatical promoter analysis and confirmed their functional relevance by demonstrating GR interaction by chromatin immunoprecipitation. Moreover transfection of MEFs with siRNA for KLF15 significantly attenuated the expressions of adipogenic-marker genes and the lipid accumulation. Our results provide a new mechanism for understanding glucocorticoids dependent adipogenesis and that GR promotes adipogenesis via KLF15 gene expression as a transcriptional direct target.

Changes in the expression of arginase and their association with nitrosative stress were investigated using an asthmatic model previously established in NC/Nga mice with mite extract. Mite crude extract (100 microg/day) from Dermatophagoides farinae was administered intranasally for 5 consecutive days (day 0-4), and a single challenge was performed on day 11. On day 12, upregulation of the mRNA expression of inducible types of nitric oxide synthase (iNOS) and increases in immunohistochemical staining for iNOS and nitrotyrosine were observed. However, the level of nitrite + nitrate was unchanged. An increase in enzymatic activity, upregulation of mRNA expression, and immunostaining for arginase I was detected in the lung tissue and serum. Moreover, increases in both arginase I and II were revealed by immunoblotting. Goblet cell hyperplasia in bronchial epithelial cells and increasing collagen synthesis around the bronchus were also observed. These results suggested that an increase in arginase may lead to decreased availability of arginine for nitric oxide synthase and may contribute to the remodeling of the lung.

The expression of arginase I has been a focus of research into the pathogenesis of experimental asthma, because arginase deprives nitric oxide synthase (NOS) of arginine and therefore participates in the attenuation of bronchodilators such as nitric oxide (NO). The present study used an intranasal mite-induced NC/Nga mouse model of asthma to investigate the contribution of arginase to the asthma pathogenesis, using an arginase inhibitor, N -hydroxy-nor-L-arginine (nor-NOHA). The treatment with nor-NOHA inhibited the increase in airway hyperresponsiveness (AHR) and the number of eosinophils in bronchoalveolar lavage fluid. NOx levels in the lung were elevated despite suppressed NOS2 mRNA expression. Accompanied by the attenuated activity of arginase, the expression of arginase I at both the mRNA and protein level was downregulated. The levels of mRNA for T helper 2 cytokines such as IL-4, IL-5, and IL-13, and for chemotactants such as eotaxin-1 and eotaxin-2, were reduced. Moreover, the accumulation of inflammatory cells and the ratio of goblet cells in the bronchiole were decreased. The study concluded that the depletion of NO caused by arginase contributes to AHR and inflammation, and direct administration of an arginase inhibitor to the airway may be beneficial and could be of use in treating asthma due to its antiinflammatory and airway-relaxing effects, although it is not clear whether the anti-inflammatory effect is direct or indirect. experimental asthma; arginase inhibitor; nor-NOHA