The Biological Functions of T Helper 17 Cell Effector Cytokines in Inflammation  Wenjun Ouyang, Jay K. Kolls, Yan Zheng  Immunity  Volume 28, Issue 4, Pages 454-467 (April 2008) DOI: 10.1016/j.immuni.2008.03.004 Copyright © 2008 Elsevier Inc. Terms and Conditions

Figure 1 Functions of IL-17 and IL-22 during K. pneumonia Infection in the Lung IL-17 and IL-22 are induced rapidly in experimental bacterial pneumonia and are produced by several T cell populations in the lung, including γδ-T cells and NKT cells as well as effector memory αβ CD4+ T cells. IL-17 signaling regulates granulopoiesis, through the regulation of G-CSF, as well as neutrophil recruitment, via the regulation of CXC chemokines by epithelial cells. IL-22 and IL-17 induce antiamicrobial peptides from the same target cells, and IL-22 can augment epithelial repair. This cooperative induction of neutrophil recruitment and this antimicrobial-peptide production augment epithelial-barrier function and are critical for mucosal host defense against Gram-negative bacterial pneumonia. Immunity 2008 28, 454-467DOI: (10.1016/j.immuni.2008.03.004) Copyright © 2008 Elsevier Inc. Terms and Conditions

Figure 2 Potential Functions of IL-17, IL-22, and IL-21 during C. rodentium Infection in the Colon During the early phase of C. rodentium infection, the invasion of attaching-effacing bacteria results in the induction of IL-23. IL-23 promotes early IL-22 production in innate immune cells, especially DCs. IL-22 directly acts on colon epithelial cells to induce antimicrobial peptides, such as Reg-family proteins, and chemokines that recruit leukocytes to the site of infection. IL-22 plays an indispensable role during the early phase of infection in protection of the integrity of the colon epithelial layer and prevention of systemic spreading of the bacteria. In the late phase of infection, the adaptive immunity is essential for the final eradication of the bacteria from the colon. Th17 cells and the effector cytokines IL-17 and IL-21 might have important functions during this phase. Both IL-17 and IL-21 can help the formation of lymph aggregates in the colon and promote the production of bacterial-specific antibodies, which kill and eliminate bacteria. Immunity 2008 28, 454-467DOI: (10.1016/j.immuni.2008.03.004) Copyright © 2008 Elsevier Inc. Terms and Conditions