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Rosanne Spolski, Lu Wang, Chi-Keung Wan, Cynthia A Bonville, Joseph B Domachowske, Hyoung-Pyo Kim, Zuxi Yu, Warren J Leonard, IL-21 Promotes the Pathologic Immune Response to Pneumovirus Infection, The Journal of Immunology, Volume 188, Issue 4, February 2012, Pages 1924–1932, https://doi.org/10.4049/jimmunol.1100767
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Abstract
IL-21 is a cytokine with pleiotropic actions, promoting terminal differentiation of B cells, increased Ig production, and the development of Th17 and T follicular helper cells. IL-21 is also implicated in the development of autoimmune disease and has antitumor activity. In this study, we investigated the role of IL-21 in host defense to pneumonia virus of mice (PVM), which initiates an infection in mice resembling that of respiratory syncytial virus disease in humans. We found that PVM-infected mice expressed IL-21 in lung CD4+ T cells. Following infection, Il21r−/− mice exhibited less lung infiltration by neutrophils than did wild-type (WT) mice and correspondingly had lower levels of the chemokine CXCL1 in bronchoalveolar lavage fluid and lung parenchyma. CD8+, CD4+, and γδ T cell numbers were also lower in the lungs of PVM-infected Il21r−/− mice than in infected WT mice, with normal Th17 cytokines but diminished IL-6 production in PVM-infected Il21r−/− mice. Strikingly, Il21r−/− mice had enhanced survival following PVM infection, and moreover, treatment of WT mice with soluble IL-21R-Fc fusion protein enhanced their survival. These data reveal that IL-21 promotes the pathogenic inflammatory effect of PVM and indicate that manipulating IL-21 signaling may represent an immunomodulatory strategy for controlling PVM and potentially other respiratory virus infections.