Differential influences of the aryl hydrocarbon receptor on Th17 mediated responses in vitro and in vivo.
The aryl hydrocarbon receptor (AhR) has been attributed with anti-inflammatory effects in the development of pathological immune responses leading to experimental autoimmune encephalomyelitis (EAE) via the induction of regulatory T cells. In agreement with previously published findings, we find that TCDD administration confers protection from EAE, however, this immuno-modulatory effect was not the consequence of de novo Treg generation, but the inhibition of Th17 cell differentiation. Systemic application of FICZ at the time of immunization also reduced EAE pathology albeit to a lesser degree than TCDD. In vitro Th17 differentiation in the presence of AhR agonists, including TCDD, promoted IL-17 and IL-22 expression, but did not induce Treg differentiation. AhR affinity influenced the amounts of IL-17 and IL-22 protein that was secreted by Th17 cells, but did not seem to affect susceptibility to EAE in vivo. Making use of conditional AhR-deficient mice, we show that the anti-inflammatory effect of TCDD depends on AhR activation in both T cells and dendritic cells, further emphasising the ability of TCDD to interfere with T effector cell differentiation in vivo. The dichotomy between the in vivo and in vitro effects of AhR reveals the complexity of the AhR pathway, which has the capacity of affecting different AhR-expressing cell types involved in mounting immune responses, thus participating in defining their outcome.
Division of Molecular Immunology, MRC National Institute for Medical Research, London, United Kingdom.
João H
JH
Duarte
Paola
P
Di Meglio
Keiji
K
Hirota
Helena
H
Ahlfors
Brigitta
B
Stockinger
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D002227:Carbazoles / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000139:chemically induced / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D004785:Environmental Pollutants / Q000494:pharmacology; D005786:Gene Expression Regulation; D007111:Immunity, Cellular / Q000187:drug effects*; D007155:Immunologic Factors / Q000494:pharmacology; D020381:Interleukin-17 / Q000235:genetics / Q000276:immunology*; D007378:Interleukins / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D063308:Myelin-Oligodendrocyte Glycoprotein; D010446:Peptide Fragments; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D058504:Th17 Cells / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D000097043:Interleukin-22
D051792:Basic Helix-Loop-Helix Proteins; D002227:Carbazoles; D004785:Environmental Pollutants; D007155:Immunologic Factors; D020381:Interleukin-17; D007378:Interleukins; D063308:Myelin-Oligodendrocyte Glycoprotein; D010446:Peptide Fragments; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D000097043:Interleukin-22; C111855:6-formylindolo(3,2-b)carbazole; C484722:Ahr protein, mouse; C445081:myelin oligodendrocyte glycoprotein (35-55); C445379:1,2,7,8-tetrachlorodibenzo-p-dioxin