α-Galactosylceramide suppresses murine eosinophil production through interferon-γ-dependent induction of NO synthase and CD95.
OBJECTIVE
α-Galactosylceramide (α-GalCer), a pleiotropic immunomodulator with therapeutic potential in neoplastic, autoimmune and allergic diseases, activates invariant natural killer T-cells throughCD1-restricted receptors for α-GalCer on antigen-presenting cells, inducing cytokine secretion. However the haemopoietic effects of α-GalCer remain little explored.


METHODS
α-GalCer-induced modulation of eosinophil production in IL-5-stimulated bone marrow cultures was examined in wild-type (BALB/c, C57BL/6) mice and their mutants lacking CD1, inducible NOS (iNOS), CD95 and IFN-γ, along with the effects of lymphocytes; IFN-γ; caspase and iNOS inhibitors; non-steroidal anti-inflammatory drugs (NSAIDs) and LTD4 ; and dexamethasone.


RESULTS
α-GalCer (10(-6) -10(-8) M) suppressed IL-5-stimulated eosinopoiesis by inducing apoptosis. α-GalCer pretreatment in vivo (100 μg·kg(-1) , i.v.) suppressed colony formation by GM-CSF-stimulated bone marrow progenitors in semi-solid cultures. α-GalCer and dexamethasone synergistically promoted eosinophil maturation. Suppression of eosinophil production by α-GalCer was prevented by aminoguanidine and was undetectable in bone marrow lacking iNOS, CD95, CD28; or CD1d. Separation on Percoll gradients and depletion of CD3+ cells made bone marrow precursors unresponsive to α-GalCer. Responsiveness was restored with splenic lymphocytes. Experiments with (i) IFN-γ-deficient bone marrow, alone or co-cultured with spleen T-cells from wild-type, but not from CD1d-deficient, donors; (ii) IFN-γ neutralization; and (iii) recombinant IFN-γ, showed that these effects of α-GalCer were mediated by IFN-γ. Effects of α-GalCer on eosinophil production were blocked by LTD4 and NSAIDs.


CONCLUSIONS
α-GalCer activation of IFN-γ-secreting, CD1d-restricted lymphocytes induced iNOS-CD95-dependent apoptosis in developing eosinophils. This pathway is initiated by endogenous regulatory lymphocytes, antagonised by LTD4 , NSAIDs and aminoguanidine, and modified by dexamethasone.
Department of Pediatrics, Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, FIOCRUZ, Rio de Janeiro, Brazil.
Maria Ignez
MI
Gaspar-Elsas
Department of Pediatrics, Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, FIOCRUZ, Rio de Janeiro, Brazil.
Túlio
T
Queto
Department of Immunology, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Daniela
D
Masid-de-Brito
Department of Pediatrics, Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, FIOCRUZ, Rio de Janeiro, Brazil.|Department of Immunology, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Bruno Marques
BM
Vieira
Department of Pediatrics, Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, FIOCRUZ, Rio de Janeiro, Brazil.
Bianca
B
de Luca
Department of Pharmacology, Faculdade de Medicina da USP (FMRP-USP), Ribeirão Preto, Brazil.
Fernando Queiroz
FQ
Cunha
Department of Pharmacology, Faculdade de Medicina da USP (FMRP-USP), Ribeirão Preto, Brazil.
Pedro
P
Xavier-Elsas
D000818:Animals; D055610:Antigens, CD1d / Q000235:genetics; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018106:CD28 Antigens / Q000235:genetics; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects*; D005699:Galactosylceramides / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism*; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000166:cytology; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism*
D055610:Antigens, CD1d; C584692:CD1d antigen, mouse; D018106:CD28 Antigens; D005699:Galactosylceramides; C493154:alpha-galactosylceramide; D019014:fas Receptor; D003907:Dexamethasone; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D015232:Dinoprostone