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. 2012 Feb 15;188(4):1924-32.
doi: 10.4049/jimmunol.1100767. Epub 2012 Jan 11.

IL-21 promotes the pathologic immune response to pneumovirus infection

Rosanne Spolski  1 , Lu Wang, Chi-Keung Wan, Cynthia A Bonville, Joseph B Domachowske, Hyoung-Pyo Kim, Zuxi Yu, Warren J Leonard
Affiliations

IL-21 promotes the pathologic immune response to pneumovirus infection

Rosanne Spolski et al. J Immunol. .

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.

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Figures

Figure 1
Figure 1. IL-21 is expressed by lung CD4+ T cells following PVM infection
(A and B) C57BL/6 WT mice were inoculated with PVM, sacrificed at indicated time points, lung RNA isolated from lung tissue, and RT-PCR analysis of the PVM SH (A) and Il21 (B) genes was performed. Shown are values ± S.E.M. relative to Rpl7 expression (n = 5 for each time point). (C-F) Il21-mCherry transgenic reporter mice (TG) or WT littermates were infected with PVM, lung cells were isolated 6 days later, and IL-21 expression measured by flow cytometry after surface staining with anti-CD4 and anti-TCRβ. A representative experiment is shown in (C), (D) and (E); the experiment was performed 3 times with similar results. (F) Summary of 3 experiments.
Figure 2
Figure 2. Reduced lung inflammatory pathology in PVM-infected Il21r-/- mice
Representative lung sections (stained with H & E) from either uninfected (CTL) or PVM-infected WT and Il21r-/- mice. (A) Compared to the Il21r-/- mice, WT lungs showing severe cell infiltration at days 5 and 6 after PVM inoculation. Scale bar, 100 μm for all panels. (B) Higher magnification views shows the inflammatory cells include lymphocytes (arrows) and neutrophils (arrowhead). Scale bar = 20 μm.
Figure 3
Figure 3. Reduced cellular infiltration in lungs of Il21r-/- mice in response to PVM infection
Total number of cells in BAL fluid (A) or of cells isolated from one lobe of the lung (B) were measured at the indicated time points after PVM infection of WT or Il21r-/- mice. The total number of neutrophils was calculated after analyzing the percent Ly6G+CD11b+ cells in either the BAL fluid (C) or lung (D). (E and F) RNA was isolated from the other lung lobe in these mice and RT-PCR was used to evaluate the relative levels of MMP8 or S100A8 mRNA in the lungs of these PVM-infected mice. Shown are the means ± S.E.M from one of three experiments with similar results (n = 5-8 mice per group).
Figure 4
Figure 4. Lymphocyte infiltration in response to PVM infection is diminished in Il21r-/- mice
Flow cytometry was used to assess the total number of CD4+ T cells (A), CD8+ T cells (B), γδ T cells (C), and NK cells (D) in lungs of WT and Il21r-/- mice. Total cells were calculated from the % of each population and the total cell number isolated from one lung lobe. IFNγ-producing cells were stained after PMA/ionomycin/Golgi Plug incubation for 4 hr after isolation. The % of IFNγ+CD8+ T cells is shown in (E) and the calculated value of total IFNγ+CD8+ T cells is displayed in (F). Shown are the means ± S.E.M. for one of three experiments with similar results (n = 5-8 mice per group).
Figure 5
Figure 5. Levels of Th17 cytokines are similar but IL-6 levels are reduced in lung tissue of PVM-infected Il21r-/- mice
(A-F) Lung RNA was isolated from WT and Il21r-/- mice after PVM infection and relative levels of mRNA encoding IL-17A (A), IL-22 (B), TNFα (C), IFNγ (D), IL-1β (E), and IL-6 (F) were quantitated by RT-PCR. IL-6 protein levels in BAL fluid (G) or lung homogenate (H) were measured by ELISA. Shown are the means ± S.E.M. from one of three experiments with similar results (n = 5-8 mice per group).
Figure 6
Figure 6. Induction of CXCL1 mRNA and protein levels in response to PVM infection are diminished in lung tissue from Il21r-/- mice
(A-D) Lung RNA was isolated from WT and Il21r-/- mice after PVM infection and relative levels of mRNA encoding the chemokines CXCL1 (A), CXCL10 (B), CCL3 (C), and CXCL2 (D) were quantitated by RT-PCR. (E and F) CXCL1 protein levels were measured by ELISA in BAL fluid (E) or in equal amounts (25ug) of protein from lung homogenates (F) of WT and Il21r-/- mice. Shown are the means ± S.E.M. from one of three experiments with similar results (n = 5-8 mice per group).
Figure 7
Figure 7. Cellular infiltration and cytokine production in lung-draining lymph nodes after PVM infection of WT and Il21r-/- mice
(A) Total cellularity was measured in mediastinal lymph nodes either before or at day 6 after PVM infection. (B and C) Flow cytometry was used to assess the total number of CD4+ (B) or CD8+ (C) T cells based on the % of each population and the total cell number. (D-H) MLN RNA was isolated and relative levels of the indicated cytokines were measured by RT-PCR. Shown are pooled data from 3 independent experiments.
Figure 8
Figure 8. IL-21 increases lung cellularity and induces IL-6 production
(A-C) Total cellularity was measured in BAL fluid (A) and lungs (B) of WT and IL-21 transgenic mice (TG21). The % neutrophils was determined by flow cytometry of Ly6G+CD11b+ cells (C). (D-F) Lung RNA was isolated and relative levels of Cxcl1 (D), Il6 (E) and Mmp8 (F) mRNA were measured by RT-PCR. (G, H) Splenic dendritic cells were isolated and stimulated in vitro with IL-21 for 5 h, at which time Il6 mRNA was measured by RT-PCR (G) and IL-6 protein was measured at 16 h by ELISA (H).
Figure 9
Figure 9. Prolonged survival after PVM infection in Il21r-/- mice or in WT mice treated with an IL-21R/Fc fusion protein
(A) WT and Il21r-/- mice were infected with PVM and their survival was monitored daily over the next 3 weeks. Infection of the long-term survivor was documented by confirming sero-conversion to PVM antigens (SMART-M12, El Cerrito, CA; data not shown). Statistical significance was evaluated using Kaplan-Meier survival curve (GraphPad Prism). n= 19 mice per group. (B) RT-PCR evaluation of the PVM SH gene in total lung RNA. Shown are the means ± S.E.M. from one of three experiments with similar results (n = 5-8 mice per group). (C and E) WT mice received 50 μg of either IL-21R/Fc or control Fc intratracheally one day prior to and 2 days post-inoculation with PVM and their survival was monitored. Mice in (C) and (E) received 60 pfu and 12 pfu, respectively, of PVM intranasally. In (C), p = .001 and in (E) p = .039, with 10 mice per group in each panel. (D and F) PVM SH expression was determined by RT-PCR of total lung RNA at day 6 after PVM infection. (D) corresponds to the experiment in (C) and (F) corresponds to the experiment in (E). Shown are the means ± S.E.M. from 5 mice in each group.
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References

    1. Spolski R, Leonard WJ. Interleukin-21: Basic Biology and Implications for Cancer and Autoimmunity. Annu Rev Immunol. 2008;26:57–79. - PubMed
    1. Leonard WJ. Cytokines and immunodeficiency diseases. Nat Rev Immunol. 2001;1:200–208. - PubMed
    1. Noguchi M, Yi H, Rosenblatt HM, Filipovich AH, Adelstein S, Modi WS, McBride OW, Leonard WJ. Interleukin-2 receptor gamma chain mutation results in X-linked severe combined immunodeficiency in humans. Cell. 1993;73:147–157. - PubMed
    1. Zeng R, Spolski R, Finkelstein SE, Oh S, Kovanen PE, Hinrichs CS, Pise-Masison CA, Radonovich MF, Brady JN, Restifo NP, Berzofsky JA, Leonard WJ. Synergy of IL-21 and IL-15 in regulating CD8+ T cell expansion and function. J Exp Med. 2005;201:139–148. - PMC - PubMed
    1. Ozaki K, Spolski R, Ettinger R, Kim HP, Wang G, Qi CF, Hwu P, Shaffer DJ, Akilesh S, Roopenian DC, Morse HC, 3rd, Lipsky PE, Leonard WJ. Regulation of B cell differentiation and plasma cell generation by IL-21, a novel inducer of Blimp-1 and Bcl-6. J Immunol. 2004;173:5361–5371. - PubMed

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