title: Α-galactosylceramide analogs with weak agonist activity for human iNKT cells define new candidate anti-inflammatory agents.
abstract: CD1d-restricted natural killer T cells with invariant T cell receptor α chains (iNKT cells) are a unique lymphocyte subset that responds to recognition of specific lipid and glycolipid antigens. They are conserved between mice and humans and exert various immunoregulatory functions through their rapid secretion of a variety of cytokines and secondary activation of dendritic cells, B cells and NK cells. In the current study, we analyzed the range of functional activation states of human iNKT cells using a library of novel analogs of α-galactosylceramide (αGalCer), the prototypical iNKT cell antigen. Measurement of cytokines secreted by human iNKT cell clones over a wide range of glycolipid concentrations revealed that iNKT cell ligands could be classified into functional groups, correlating with weak versus strong agonistic activity. The findings established a hierarchy for induction of different cytokines, with thresholds for secretion being consistently lowest for IL-13, higher for interferon-γ (IFNγ), and even higher for IL-4. These findings suggested that human iNKT cells can be intrinsically polarized to selective production of IL-13 by maintaining a low level of activation using weak agonists, whereas selective polarization to IL-4 production cannot be achieved through modulating the strength of the activating ligand. In addition, using a newly designed in vitro system to assess the ability of human iNKT cells to transactivate NK cells, we found that robust secondary induction of interferon-γ secretion by NK cells was associated with strong but not weak agonist ligands of iNKT cells. These results indicate that polarization of human iNKT cell responses to Th2-like or anti-inflammatory effects may best be achieved through selective induction of IL-13 and suggest potential discrepancies with findings from mouse models that may be important in designing iNKT cell-based therapies in humans.
authors.affiliation: Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bricard
authors.forename: Manjunatha M
authors.initials: MM
authors.lastname: Venkataswamy
authors.forename: Karl O A
authors.initials: KO
authors.lastname: Yu
authors.forename: Jin S
authors.initials: JS
authors.lastname: Im
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Ndonye
authors.forename: Amy R
authors.initials: AR
authors.lastname: Howell
authors.forename: Natacha
authors.initials: N
authors.lastname: Veerapen
authors.forename: Petr A
authors.initials: PA
authors.lastname: Illarionov
authors.forename: Gurdyal S
authors.initials: GS
authors.lastname: Besra
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Young-Tae
authors.initials: YT
authors.lastname: Chang
authors.forename: Steven A
authors.initials: SA
authors.lastname: Porcelli
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D023201:CD40 Ligand / Q000378:metabolism; D015195:Drug Design; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005434:Flow Cytometry / Q000379:methods; D005699:Galactosylceramides / Q000819:agonists / Q000737:chemistry*; D006017:Glycolipids / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D018793:Interleukin-13 / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008956:Models, Chemical; D055611:Natural Killer T-Cells / Q000187:drug effects*; D018418:Th2 Cells / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D005699:Galactosylceramides; D006017:Glycolipids; D018793:Interleukin-13; C493154:alpha-galactosylceramide; D023201:CD40 Ligand; D015847:Interleukin-4