title: Interleukin-22 but not interleukin-17 provides protection to hepatocytes during acute liver inflammation.
abstract: The cytokine interleukin-22 (IL-22) is primarily expressed by T helper 17 (Th17) CD4(+) T cells and is highly upregulated during chronic inflammatory diseases. IL-22 receptor expression is absent on immune cells, but is instead restricted to the tissues, providing signaling directionality from the immune system to the tissues. However, the role of IL-22 in inflammatory responses has been confounded by data suggesting both pro- and anti-inflammatory functions. Herein, we provide evidence that during inflammation, IL-22 played a protective role in preventing tissue injury. Hepatocytes from mice deficient in IL-22 were highly sensitive to the detrimental immune response associated with hepatitis. Additionally, IL-22-expressing Th17 cells provided protection during hepatitis in IL-22-deficient mice. On the other hand, interleukin-17 (IL-17), which is coexpressed with IL-22 and can induce similar cellular responses, had no observable role in liver inflammation. Our data suggest that IL-22 serves as a protective molecule to counteract the destructive nature of the immune response to limit tissue damage.
authors.affiliation: Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Zenewicz
authors.forename: George D
authors.initials: GD
authors.lastname: Yancopoulos
authors.forename: David M
authors.initials: DM
authors.lastname: Valenzuela
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Murphy
authors.forename: Margaret
authors.initials: M
authors.lastname: Karow
authors.forename: Richard A
authors.initials: RA
authors.lastname: Flavell
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006505:Hepatitis / Q000276:immunology* / Q000378:metabolism; D022781:Hepatocytes / Q000276:immunology* / Q000378:metabolism; D020381:Interleukin-17 / Q000276:immunology* / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism; D007378:Interleukins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D000097043:Interleukin-22
chemical_list: D020381:Interleukin-17; D015850:Interleukin-6; D007378:Interleukins; D012333:RNA, Messenger; D000097043:Interleukin-22