Targeted deletion of the aryl hydrocarbon receptor in dendritic cells prevents thymic atrophy in response to dioxin
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Abstract
In nearly every species examined, administration of the persistent environmental pollutant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin, TCDD) causes profound immune suppression and thymic atrophy in an aryl hydrocarbon receptor (AhR) dependent manner. Moreover, TCDD alters the development and differentiation of thymocytes, resulting in decreases in the relative proportion and absolute number of double positive (DP, CD4+CD8+) thymocytes, as well as a relative enrichment in the relative proportion and absolute number of double negative (DN, CD4−CD8−) and single-positive (SP) CD4+CD8− and CD4−CD8+ thymocytes. Previous studies suggested that the target for TCDD-induced thymic atrophy resides within the hemopoietic compartment and implicated apoptosis, proliferation arrest of thymic progenitors, and emigration of DN thymocytes to the periphery as potential contributors to TCDD-induced thymic atrophy. However, the precise cellular and molecular mechanisms involved remain largely unknown. Our results show that administration of 10 µg/kg TCDD and 8 mg/kg 2-(1H-indol-3-ylcarbonyl)-4-thiazolecarboxylic acid methyl ester (ITE) induced AhR-dependent thymic atrophy in mice on day 7, whereas 100 mg/kg indole 3-carbinol (I3C) did not. Though our studies demonstrate that TCDD triggers a twofold increase in the frequency of apoptotic thymocytes, TCDD-induced thymic atrophy is not dependent on Fas–FasL interactions, and thus, enhanced apoptosis is unlikely to be a major mechanistic contributor. Finally, our results show that activation of the AhR in CD11c+ dendritic cells is directly responsible for TCDD-induced alterations in the development and differentiation of thymocytes, which results in thymic atrophy. Collectively, these results suggest that CD11c+ dendritic cells play a critical role in mediating TCDD-induced thymic atrophy and disruption of T lymphocyte development and differentiation in the thymus.
Keywords
Involution TCDD ITE I3C AhRd ApoptosisNotes
Acknowledgements
The authors wish to thank the following scientists: Pam Shaw (Fluorescence Cytometry Core) and Britten Postma (Animal Core) for the shared expertise needed to conduct and/or analyze the experiments described in this manuscript.
Author contributions
CAB, JMK, and DMS designed the studies, coordinated the experiments, prepared the figures, and composed the manuscript. SLC performed the qRT-PCR analysis and assisted with experimental harvests. All authors have read and approved the final version of the manuscript.
Funding
Research reported in this publication was supported by the National Institute of Environmental Health Sciences and the National Institute of General Medical Sciences of the National Institutes of Health under Grant numbers R01-ES013784 (DMS), P30-GM103338, P20-GM103546. JMK was supported by the American Association of Immunologists through Careers in Immunology Fellowship. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Supplementary material
References
- Abron JD, Singh NP, Mishra MK, Price RL, Nagarkatti M, Nagarkatti PS, Singh UP (2018) An endogenous aryl hydrocarbon receptor ligand, ITE, induces regulatory T cells and ameliorates experimental colitis. Am J Physiol Gastrointest Liver Physiol 315(2):G220–G230. https://doi.org/10.1152/ajpgi.00413.2017 Google Scholar
- Benson JM, Shepherd DM (2011a) Aryl hydrocarbon receptor activation by TCDD reduces inflammation associated with Crohn’s disease. Toxicol Sci 120(1):68–78. https://doi.org/10.1093/toxsci/kfq360 Google Scholar
- Benson JM, Shepherd DM (2011b) Dietary ligands of the aryl hydrocarbon receptor induce anti-inflammatory and immunoregulatory effects on murine dendritic cells. Toxicol Sci 124(2):327–338Google Scholar
- Benson J, Beamer C, Seaver B, Shepherd D (2012a) Indole-3-carbinol exerts sex-specific effects in murine colitis. Eur J Inflamm 10(3):335–346Google Scholar
- Benson JM, Beamer CA, Seaver BP, Shepherd DM (2012b) Indole-3-carbinol exerts sex-specific effects in murine colitis. Eur J Inflamm 10(3):335–346. https://doi.org/10.1177/1721727x1201000309 Google Scholar
- Birnbaum LS (1986) Distribution and excretion of 2,3,7,8-tetrachlorodibenzo-p-dioxin in congenic strains of mice which differ at the Ah locus. Drug Metab Dispos Biol Fate Chem 14(1):34–40Google Scholar
- Bjeldanes LF, Kim J-Y, Grose KR, Bartholomew JC, Bradfield CA (1991) Aromatic hydrocarbon responsiveness-receptor agonists generated from indole-3-carbinol in vitro and in vivo: comparisons with 2,3,7,8-tetrachlorodibenzo-p-dioxin. Proc Natl Acad Sci 88(21):9543–9547Google Scholar
- Bonasio R, Scimone ML, Schaerli P, Grabie N, Lichtman AH, von Andrian UH (2006) Clonal deletion of thymocytes by circulating dendritic cells homing to the thymus. Nat Immunol 7(10):1092–1100. https://doi.org/10.1038/ni1385 Google Scholar
- Boule LA, Burke CG, Jin G-B, Lawrence BP (2018a) Aryl hydrocarbon receptor signaling modulates antiviral immune responses: ligand metabolism rather than chemical source is the stronger predictor of outcome. Sci Rep 8(1):1826Google Scholar
- Boule LA, Burke CG, Jin GB, Lawrence BP (2018b) Aryl hydrocarbon receptor signaling modulates antiviral immune responses: ligand metabolism rather than chemical source is the stronger predictor of outcome. Sci Rep 8(1):1826. https://doi.org/10.1038/s41598-018-20197-4 Google Scholar
- Camacho IA, Nagarkatti M, Nagarkatti PS (2002) 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induces Fas-dependent activation-induced cell death in superantigen-primed T cells. Arch Toxicol 76(10):570–580Google Scholar
- Camacho IA, Nagarkatti M, Nagarkatti PS (2004) Evidence for induction of apoptosis in T cells from murine fetal thymus following perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Toxicol Sci 78(1):96–106Google Scholar
- Camacho IA, Singh N, Hegde VL, Nagarkatti M, Nagarkatti PS (2005a) Treatment of mice with 2,3,7,8-tetrachlorodibenzo-p-dioxin leads to aryl hydrocarbon receptor-dependent nuclear translocation of NF-kappaB and expression of Fas ligand in thymic stromal cells and consequent apoptosis in T cells. J Immunol 175(1):90–103Google Scholar
- Camacho IA, Singh N, Hegde VL, Nagarkatti M, Nagarkatti PS (2005b) Treatment of mice with 2,3,7,8-tetrachlorodibenzo-p-dioxin leads to aryl hydrocarbon receptor-dependent nuclear translocation of NF-κB and expression of Fas ligand in thymic stromal cells and consequent apoptosis in T cells. J Immunol 175(1):90–103Google Scholar
- Comment CE, Blaylock BL, Germolec DR et al (1992) Thymocyte injury after in vitro chemical exposure: potential mechanisms for thymic atrophy. J Pharmacol Exp Ther 262(3):1267–1273Google Scholar
- Connor K, Finley B (2003) Naturally occurring ah-receptor agonists in foods: implications regarding dietary dioxin exposure and health risk. Hum Ecol Risk Assess 9(7):1747–1763Google Scholar
- De Heer C, Verlaan AP, Penninks AH, Vos JG, Schuurman HJ, Van Loveren H (1994) Time course of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced thymic atrophy in the Wistar rat. Toxicol Appl Pharmacol 128(1):97–104Google Scholar
- Dencker L, Hassoun E, d’Argy R, Alm G (1985) Fetal thymus organ culture as an in vitro model for the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin and its congeners. Mol Pharmacol 27(1):133–140Google Scholar
- Dolciami D, Gargaro M, Cerra B et al (2018) Binding mode and structure-activity relationships of ITE as an aryl hydrocarbon receptor (AhR) agonist. ChemMedChem 13(3):270–279 https://doi.org/10.1002/cmdc.201700669 Google Scholar
- Ehrlich AK, Pennington JM, Bisson WH, Kolluri SK, Kerkvliet NI (2018) TCDD, FICZ, and other high affinity AhR ligands dose-dependently determine the fate of CD4+ T cell differentiation. Toxicol Sci 161(2):310–320. https://doi.org/10.1093/toxsci/kfx215 Google Scholar
- Esser C, Welzel M (1993) Ontogenic development of murine fetal thymocytes is accelerated by 3,3′,4,4′-tetrachlorobiphenyl. Int J Immunopharmacol 15(8):841–852Google Scholar
- Faith RE, Luster MI (1979) Investigations on the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on parameters of various immune functions. Ann N Y Acad Sci 320(1):564–571Google Scholar
- Fernandez-Salguero PM, Hilbert DM, Rudikoff S, Ward JM, Gonzalez FJ (1996) Aryl-hydrocarbon receptor-deficient mice are resistant to 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced toxicity. Toxicol Appl Pharmacol 140(1):173–179. https://doi.org/10.1006/taap.1996.0210 Google Scholar
- Fine JS, Silverstone AE, Gasiewicz TA (1990) Impairment of prothymocyte activity by 2,3,7,8-tetrachlorodibenzo-p-dioxin. J Immunol 144(4):1169–1176Google Scholar
- Fisher MT, Nagarkatti M, Nagarkatti PS (2004) Combined screening of thymocytes using apoptosis-specific cDNA array and promoter analysis yields novel gene targets mediating TCDD-induced toxicity. Toxicol Sci 78(1):116–124. https://doi.org/10.1093/toxsci/kfh058 Google Scholar
- Funatake CJ, Marshall NB, Steppan LB, Mourich DV, Kerkvliet NI (2005) Cutting edge: activation of the aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin generates a population of CD4+ CD25+ cells with characteristics of regulatory T cells. J Immunol 175(7):4184–4188Google Scholar
- Gasiewicz TA, Geiger LE, Rucci G, Neal RA (1983) Distribution, excretion, and metabolism of 2,3,7,8-tetrachlorodibenzo-p-dioxin in C57BL/6J, DBA/2J, and B6D2F1/J mice. Drug Metab Dispos Biol Fate Chem 11(5):397–403Google Scholar
- Gu Y-Z, Hogenesch JB, Bradfield CA (2000) The PAS superfamily: sensors of environmental and developmental signals. Annu Rev Pharmacol Toxicol 40(1):519–561Google Scholar
- Hao N, Whitelaw ML (2013) The emerging roles of AhR in physiology and immunity. Biochem Pharmacol 86(5):561–570. https://doi.org/10.1016/j.bcp.2013.07.004 Google Scholar
- Harrill JA, Layko D, Nyska A et al (2016) Aryl hydrocarbon receptor knockout rats are insensitive to the pathological effects of repeated oral exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. J Appl Toxicol 36(6):802–814. https://doi.org/10.1002/jat.3211 Google Scholar
- Harris M, Moore J, Vos J, Gupta B (1973) General biological effects of TCDD in laboratory animals. Environ Health Perspect 5:101Google Scholar
- Henry EC, Bemis JC, Henry O, Kende AS, Gasiewicz TA (2006) A potential endogenous ligand for the aryl hydrocarbon receptor has potent agonist activity in vitro and in vivo. Arch Biochem Biophys 450(1):67–77. https://doi.org/10.1016/j.abb.2006.02.008 Google Scholar
- Holladay S, Lindstrom P, Blaylock B et al (1991) Perinatal thymocyte antigen expression and postnatal immune development altered by gestational exposure to tetrachlorodibenzo-p-dioxin (TCDD). Teratology 44(4):385–393Google Scholar
- Hubbard TD, Murray IA, Perdew GH (2015) Indole and tryptophan metabolism: endogenous and dietary routes to Ah receptor activation. Drug Metab Dispos 43(10):1522–1535Google Scholar
- Hubert FX, Kinkel SA, Davey GM et al (2011) Aire regulates the transfer of antigen from mTECs to dendritic cells for induction of thymic tolerance. Blood 118(9):2462–2472. https://doi.org/10.1182/blood-2010-06-286393 Google Scholar
- Kamath AB, Xu H, Nagarkatti PS, Nagarkatti M (1997) Evidence for the induction of apoptosis in thymocytes by 2,3,7,8-tetrachlorodibenzo-p-dioxinin vivo. Toxicol Appl Pharmacol 142(2):367–377Google Scholar
- Kamath AB, Nagarkatti PS, Nagarkatti M (1998) Characterization of phenotypic alterations induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin on thymocytes in vivo and its effect on apoptosis. Toxicol Appl Pharmacol 150(1):117–124Google Scholar
- Kamath AB, Camacho I, Nagarkatti PS, Nagarkatti M (1999a) Role of Fas–Fas ligand interactions in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity: increased resistance of thymocytes from Fas-deficient (lpr) and Fas ligand-defective (gld) mice to TCDD-induced toxicity. Toxicol Appl Pharmacol 160(2):141–155. https://doi.org/10.1006/taap.1999.8753 Google Scholar
- Kamath AB, Camacho I, Nagarkatti PS, Nagarkatti M (1999b) Role of Fas–Fas ligand interactions in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity: increased resistance of thymocytes from Fas-deficient (lpr) and Fas ligand-defective (gld) mice to TCDD-induced toxicity. Toxicol Appl Pharmacol 160(2):141–155Google Scholar
- Kerkvliet NI (2002) Recent advances in understanding the mechanisms of TCDD immunotoxicity. Int Immunopharmacol 2(2–3):277–291Google Scholar
- Kerkvliet NI (2012a) TCDD: an environmental immunotoxicant reveals a novel pathway of immunoregulation—a 30-year odyssey. Toxicol Pathol 40(2):138–142. https://doi.org/10.1177/0192623311427710 Google Scholar
- Kerkvliet NI (2012b) TCDD: an environmental immunotoxicant reveals a novel pathway of immunoregulation—a 30-year odyssey. Toxicol Pathol 40(2):138–142Google Scholar
- Kerkvliet NI, Steppan LB, Vorachek W et al (2009) Activation of aryl hydrocarbon receptor by TCDD prevents diabetes in NOD mice and increases Foxp3+ T cells in pancreatic lymph nodes. Immunotherapy 1(4):539–547. https://doi.org/10.2217/imt.09.24 Google Scholar
- Lai ZW, Kremer J, Gleichmann E, Esser C (1994) 3,3′,4,4′-Tetrachlorobiphenyl inhibits proliferation of immature thymocytes in fetal thymus organ culture. Scand J Immunol 39(5):480–488Google Scholar
- Laiosa MD, Wyman A, Murante FG et al (2003) Cell proliferation arrest within intrathymic lymphocyte progenitor cells causes thymic atrophy mediated by the aryl hydrocarbon receptor. J Immunol 171(9):4582–4591Google Scholar
- Lei Y, Ripen AM, Ishimaru N et al (2011) Aire-dependent production of XCL1 mediates medullary accumulation of thymic dendritic cells and contributes to regulatory T cell development. J Exp Med 208(2):383–394. https://doi.org/10.1084/jem.20102327 Google Scholar
- Lundberg K, Grönvik K-O, Goldschmidt TJ, Klareskog L, Dencker L (1990) 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) alters intrathymic T-cell development in mice. Chem Biol Interact 74(1–2):179–193Google Scholar
- Miniero R, De Felip E, Ferri F, Di Domenico A (2001) An overview of TCDD half-life in mammals and its correlation to body weight. Chemosphere 43(4–7):839–844Google Scholar
- Nebert D, Gelboin H (1968) Substrate-inducible microsomal aryl hydroxylase in mammalian cell culture I. Assay and properties of induced enzyme. J Biol Chem 243(23):6242–6249Google Scholar
- Nebert D, Gelboin H (1969) The in vivo and in vitro induction of aryl hydrocarbon hydroxylase in mammalian cells of different species, tissues, strains, and developmental and hormonal states. Arch Biochem Biophys 134(1):76–89Google Scholar
- Nguyen LP, Bradfield CA (2007) The search for endogenous activators of the aryl hydrocarbon receptor. Chem Res Toxicol 21(1):102–116Google Scholar
- Nowell CS, Farley AM, Blackburn CC (2007) Thymus organogenesis and development of the thymic stroma. In: Fairchild PJ (ed) Immunological tolerance. Methods in molecular biology™, vol 380. Humana Press, Totowa, pp 125–162. https://doi.org/10.1007/978-1-59745-395-0_8 Google Scholar
- Nugent LF, Shi G, Vistica BP, Ogbeifun O, Hinshaw SJ, Gery I (2013) ITE, a novel endogenous nontoxic aryl hydrocarbon receptor ligand, efficiently suppresses EAU and T-cell-mediated immunity. Investig Ophthalmol Vis Sci 54(12):7463–7469. https://doi.org/10.1167/iovs.12-11479 Google Scholar
- Okey AB (2007) An aryl hydrocarbon receptor odyssey to the shores of toxicology: the Deichmann lecture, international congress of toxicology-XI. Toxicol Sci 98(1):5–38. https://doi.org/10.1093/toxsci/kfm096 Google Scholar
- Pohjanvirta R (2011) The AH receptor in biology and toxicology. Wiley, New YorkGoogle Scholar
- Poland A, Glover E (1980) 2,3,7,8-Tetrachlorodibenzo-p-dioxin: segregation of toxicity with the Ah locus. Mol Pharmacol 17(1):86–94Google Scholar
- Poland A, Glover E (1990) Characterization and strain distribution pattern of the murine Ah receptor specified by the Ahd and Ahb-3 alleles. Mol Pharmacol 38(3):306–312Google Scholar
- Poland A, Glover E, Kende A (1976) Stereospecific, high affinity binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin by hepatic cytosol. Evidence that the binding species is receptor for induction of aryl hydrocarbon hydroxylase. J Biol Chem 251(16):4936–4946Google Scholar
- Poland A, Palen D, Glover E (1994) Analysis of the four alleles of the murine aryl hydrocarbon receptor. Mol Pharmacol 46(5):915–921Google Scholar
- Proietto AI, van Dommelen S, Zhou P et al (2008) Dendritic cells in the thymus contribute to T-regulatory cell induction. Proc Natl Acad Sci USA 105(50):19869–19874. https://doi.org/10.1073/pnas.0810268105 Google Scholar
- Quintana FJ, Murugaiyan G, Farez MF et al (2010a) An endogenous aryl hydrocarbon receptor ligand acts on dendritic cells and T cells to suppress experimental autoimmune encephalomyelitis. Proc Natl Acad Sci 107(48):20768–20773Google Scholar
- Quintana FJ, Murugaiyan G, Farez MF et al (2010b) An endogenous aryl hydrocarbon receptor ligand acts on dendritic cells and T cells to suppress experimental autoimmune encephalomyelitis. Proc Natl Acad Sci USA 107(48):20768–20773. https://doi.org/10.1073/pnas.1009201107 Google Scholar
- Rhile MJ, Nagarkatti M, Nagarkatti PS (1996) Role of Fas apoptosis and MHC genes in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity of T cells. Toxicology 110(1–3):153–167Google Scholar
- Silkworth J, Antrim L (1985) Relationship between Ah receptor-mediated polychlorinated biphenyl (PCB)-induced humoral immunosuppression and thymic atrophy. J Pharmacol Exp Ther 235(3):606–611Google Scholar
- Silkworth JB, Antrim L, Sack G (1986) Ah receptor mediated suppression of the antibody response in mice is primarily dependent on the Ah phenotype of lymphoid tissue. Toxicol Appl Pharmacol 86(3):380–390Google Scholar
- Silverstone AE, Frazier DE Jr, Fiore NC, Soults JA, Gasiewicz TA (1994a) Dexamethasone, beta-estradiol, and 2,3,7,8-tetrachlorodibenzo-p-dioxin elicit thymic atrophy through different cellular targets. Toxicol Appl Pharmacol 126(2):248–259. https://doi.org/10.1006/taap.1994.1114 Google Scholar
- Silverstone AE, Frazier DE Jr, Gasiewicz TA (1994b) Alternate immune system targets for TCDD: lymphocyte stem cells and extrathymic T-cell development. Exp Clin Immunogenet 11(2–3):94–101Google Scholar
- Singh U, Abron J, Singh N et al (2014) An endogenous aryl hydrocarbon receptor (AhR) ligand, ITE induces regulatory T cells (Tregs) and ameliorates experimental colitis (IRC4P.490). J Immunol 192:60.17Google Scholar
- Singh NP, Singh UP, Rouse M et al (2016) Dietary indoles suppress delayed-type hypersensitivity by inducing a switch from proinflammatory Th17 cells to anti-inflammatory regulatory T cells through regulation of microRNA. J Immunol 196(3):1108–1122. https://doi.org/10.4049/jimmunol.1501727 Google Scholar
- Song J, Clagett-Dame M, Peterson RE et al (2002) A ligand for the aryl hydrocarbon receptor isolated from lung. Proc Natl Acad Sci 99(23):14694–14699Google Scholar
- Staples JE, Murante FG, Fiore NC, Gasiewicz TA, Silverstone AE (1998) Thymic alterations induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin are strictly dependent on aryl hydrocarbon receptor activation in hemopoietic cells. J Immunol 160(8):3844–3854Google Scholar
- Stockinger B (2009) Beyond toxicity: aryl hydrocarbon receptor-mediated functions in the immune system. J Biol 8(7):61. https://doi.org/10.1186/jbiol170 Google Scholar
- Temchura VV, Frericks M, Nacken W, Esser C (2005) Role of the aryl hydrocarbon receptor in thymocyte emigration in vivo. Eur J Immunol 35(9):2738–2747Google Scholar
- Thigpen JE, Faith RE, McConnell EE, Moore JA (1975) Increased susceptibility to bacterial infection as a sequela of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Infect Immun 12(6):1319–1324Google Scholar
- Van Loveren H, Schuurman H-J, Kampinga J, Vos JG (1991) Reversibility of thymic atrophy induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and bis (tri-n-butyltin) oxide (TBTO). Int J Immunopharmacol 13(4):369–377Google Scholar
- Vecchi A, Mantovani A, Sironi M, Luini W, Cairo M, Garattini S (1980) Effect of acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on humoral antibody production in mice. Chem Biol Interact 30(3):337–342Google Scholar
- Vos JG, Moore JA (1974) Suppression of cellular immunity in rats and mice by maternal treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin. Int Arch Allergy Appl Immunol 47(5):777–794Google Scholar
- Walisser JA, Glover E, Pande K, Liss AL, Bradfield CA (2005) Aryl hydrocarbon receptor-dependent liver development and hepatotoxicity are mediated by different cell types. Proc Natl Acad Sci USA 102(49):17858–17863Google Scholar
- Wright EJ, De Castro KP, Joshi AD, Elferink CJ (2017) Canonical and non-canonical aryl hydrocarbon receptor signaling pathways. Curr Opin Toxicol 2:87–92Google Scholar
- Wu L, Shortman K (2005) Heterogeneity of thymic dendritic cells. Semin Immunol 17(4):304–312. https://doi.org/10.1016/j.smim.2005.05.001 Google Scholar
- Yeste A, Nadeau M, Burns EJ, Weiner HL, Quintana FJ (2012) Nanoparticle-mediated codelivery of myelin antigen and a tolerogenic small molecule suppresses experimental autoimmune encephalomyelitis. Proc Natl Acad Sci USA 109(28):11270–11275. https://doi.org/10.1073/pnas.1120611109 Google Scholar