European journal of immunology
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The present study was designed to elucidate the role of Valpha14(+) NKT cells in the host defense against pulmonary infection with Streptococcus pneumoniae using Jalpha281 gene-disrupted mice (Jalpha281KO mice) that lacked this lymphocyte subset. In these mice, pneumococcal infection was severely exacerbated, as shown by the shorter survival time and marked increase of live bacteria in the lung compared to wild-type (WT) mice. The proportion of Valpha14(+) NKT cells, detected by an alpha-galactosylceramide (alpha-GalCer)-loaded CD1d tetramer, increased in thelung after S. pneumoniae infection. ⋯ In support of this finding, macrophage inflammatory protein (MIP)-2 and TNF-alpha synthesis in infected lungs was significantly reduced at 3 h and at both 3 and 6 h, respectively, in Jalpha281KO mice, compared to WT mice. In addition, treatment of mice with alpha-GalCer significantly improved the outcome of this infection. Our results demonstrated MCP-1-dependent recruitment of Valpha14(+) NKT cells and their critical role in early host protection against S. pneumoniae by promoting the trafficking of neutrophils to the site of infection.
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The pathogenesis of human asthma and the development of key features of pulmonary allergy in mouse models has been critically linked to IL-13. Analyses of the receptor components employed by IL-13 have shown that delivery of this cytokine to the airways of naive IL-4Ralpha gene targeted (IL-4Ralpha(-/-)) mice fails to induce disease, suggesting that this membrane protein is critical for transducing IL-13-mediated responses. The current study demonstrates that, in contrast to naive mice, T helper 2 bias, airways hyperreactivity (AHR) and tissue eosinophilia develop in Ovalbumin-sensitized IL-4Ralpha(-/-) mice and that these responses can be inhibited by the IL-13 antagonist sIL-13Ralpha2Fc. ⋯ To determine the role of IL-5 and eosinophils in the development of disease in antigen-exposed IL-4Ralpha(-/-) mice, pulmonary allergy was examined in mice deficient in both factors. IL-4Ralpha/IL-5(-/-) mice were significantly defective in their ability to produce IL-13 and failed to develop AHR, suggesting that IL-5 indirectly regulates AHR in allergic IL-4Ralpha(-/-) mice by an IL-13-dependent mechanism. Collectively, these results demonstrate that IL-13-dependent processes regulating the development of AHR and T helper bias persist in the in the lungs of allergic IL-4Ralpha(-/-) mice.