title: Divergent pro- and antiinflammatory roles for IL-23 and IL-12 in joint autoimmune inflammation.
abstract: Interleukin (IL) 23 is a heterodimeric cytokine composed of a p19 subunit and the p40 subunit of IL-12. IL-23 affects memory T cell and inflammatory macrophage function through engagement of a novel receptor (IL-23R) on these cells. Recent analysis of the contribution of IL-12 and IL-23 to central nervous system autoimmune inflammation demonstrated that IL-23 rather than IL-12 was the essential cytokine. Using gene-targeted mice lacking only IL-12 (p35-/-) or IL-23 (p19-/-), we show that the specific absence of IL-23 is protective, whereas loss of IL-12 exacerbates collagen-induced arthritis. IL-23 gene-targeted mice did not develop clinical signs of disease and were completely resistant to the development of joint and bone pathology. Resistance correlated with an absence of IL-17-producing CD4+ T cells despite normal induction of collagen-specific, interferon-gamma-producing T helper 1 cells. In contrast, IL-12-deficient p35-/- mice developed more IL-17-producing CD4+ T cells, as well as elevated mRNA expression of proinflammatory tumor necrosis factor, IL-1beta, IL-6, and IL-17 in affected tissues of diseased mice. The data presented here indicate that IL-23 is an essential promoter of end-stage joint autoimmune inflammation, whereas IL-12 paradoxically mediates protection from autoimmune inflammation.
authors.affiliation: Discovery Research, DNAX Research Inc, Palo Alto, CA 94304, USA.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Murphy
authors.forename: Claire L
authors.initials: CL
authors.lastname: Langrish
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Wendy
authors.initials: W
authors.lastname: Blumenschein
authors.forename: Terrill
authors.initials: T
authors.lastname: McClanahan
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kastelein
authors.forename: Jonathon D
authors.initials: JD
authors.lastname: Sedgwick
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Cua
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000209:etiology* / Q000276:immunology / Q000628:therapy; D024043:Collagen Type II / Q000276:immunology; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000502:physiology*; D020381:Interleukin-17 / Q000096:biosynthesis; D053759:Interleukin-23; D053760:Interleukin-23 Subunit p19; D007378:Interleukins / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D024043:Collagen Type II; C508841:Il23a protein, mouse; D020381:Interleukin-17; D053759:Interleukin-23; D053760:Interleukin-23 Subunit p19; D007378:Interleukins; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12; D007371:Interferon-gamma