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IL-22 mediates mucosal host defense against Gram-negative bacterial pneumonia


Emerging evidence supports the concept that T helper type 17 (TH17) cells, in addition to mediating autoimmunity, have key roles in mucosal immunity against extracellular pathogens. Interleukin-22 (IL-22) and IL-17A are both effector cytokines produced by the TH17 lineage, and both were crucial for maintaining local control of the Gram-negative pulmonary pathogen, Klebsiella pneumoniae. Although both cytokines regulated CXC chemokines and granulocyte colony–stimulating factor production in the lung, only IL-22 increased lung epithelial cell proliferation and increased transepithelial resistance to injury. These data support the concept that the TH17 cell lineage and its effector molecules have evolved to effect host defense against extracellular pathogens at mucosal sites.

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Figure 1: Primary HBE cells express IL-22R, and stimulation with IL-22 and IL-17A leads to the upregulation of host defense genes and increases clonogenic frequency.
Figure 2: IL-22 expression is elevated in mice infected with K. pneumoniae, and neutralizing IL-22 leads to decreased bacterial clearance from lung and spleen.
Figure 3: IL-22 and IL-17A regulation of pulmonary cytokines and chemokines in K. pneumoniae infection.
Figure 4: IL-22 production in vivo requires IL-23.
Figure 5: Il23a−/− mice rescued with IL-22, IL-17A and both cytokines have augmented Cxcl1, Cxcl2 and Cxcl9 expression in airways and alveolar epithelium.
Figure 6: IL-22 augments the antimicrobial activity of MTEC cells in vitro.

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The authors would like to acknowledge support from the following Public Health Service grants: 5R01HL079142 (J.K.K.), P50HL084932, and P30DK072506 (J.K.K. and J.M.P.). We would like to thank Y. Iwakura (Center for Experimental Medicine, The Institute of Medical Science, The University of Tokyo) for the Il17a−/− mice, and T. Mak (University Health Network, Toronto) for the Lcn2−/− mice.

Author information




S.J.A. performed all the experiments depicted in Figures 1, 2b,d,e,g,h,3,4,6a–d and g and wrote the manuscript. Y.R.C. performed the experiment depicted in Figure 6f. M.F. and M.Z. performed experiments depicted in Figure 2a,c,f. D.J.A. provided MTECs and assisted in experiments depicted in Figure 6a–c. D.A.P. assisted in experiments depicted in Figures 2g,h and 3. P.J.D. assisted in experiments depicted in Figure 4. F.M. performed experiments depicted in Figure 6e. T.A.R. and K.G. performed in situ hybridization as shown in Figure 5. J.E. performed the experiments with L. monocytogenes (Supplementary Fig. 2). C.A.M. performed the experiments with M. tuberculosis (Supplementary Fig. 1). S.H. provided BAL samples and helpful discussions in experiments depicted in Supplementary Table 1. J.L.K., J.M.P. and M.M.M. supplied HBE cells and helped performed experiments for Figure 1. Y.I. provided Il17A−/− mice, as well as useful discussion in experimental design. J.K.K. was responsible for experimental design, microarray analysis and final manuscript preparation.

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Correspondence to Jay K Kolls.

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Supplementary Figs. 1–6 and Supplementary Table 1 (PDF 165 kb)

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Aujla, S., Chan, Y., Zheng, M. et al. IL-22 mediates mucosal host defense against Gram-negative bacterial pneumonia. Nat Med 14, 275–281 (2008).

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