[alpha]-Galactosylceramide suppresses murine eosinophil production through interferon-[gamma]-dependent induction of NO synthase and CD95

• Published in: British journal of pharmacology 2015-07, Vol.172 (13), p.3313
• Main Authors: Gaspar-Elsas, Maria Ignez, Queto, Túlio, Masid-de-Brito, Daniela, Vieira, Bruno Marques, Luca, Bianca, Cunha, Fernando Queiroz, Xavier-Elsas, Pedro
• Format: Article
• Language: English
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/bph.13126

Background and Purpose [alpha]-Galactosylceramide ([alpha]-GalCer), a pleiotropic immunomodulator with therapeutic potential in neoplastic, autoimmune and allergic diseases, activates invariant natural killer T-cells throughCD1-restricted receptors for [alpha]-GalCer on antigen-presenting cells, inducing cytokine secretion. However the haemopoietic effects of [alpha]-GalCer remain little explored. Experimental Approach [alpha]-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-[gamma], along with the effects of lymphocytes; IFN-[gamma]; caspase and iNOS inhibitors; non-steroidal anti-inflammatory drugs (NSAIDs) and LTD4; and dexamethasone. Key Results [alpha]-GalCer (10-6-10-8M) suppressed IL-5-stimulated eosinopoiesis by inducing apoptosis. [alpha]-GalCer pretreatment in vivo (100µg·kg-1, i.v.) suppressed colony formation by GM-CSF-stimulated bone marrow progenitors in semi-solid cultures. [alpha]-GalCer and dexamethasone synergistically promoted eosinophil maturation. Suppression of eosinophil production by [alpha]-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 [alpha]-GalCer. Responsiveness was restored with splenic lymphocytes. Experiments with (i) IFN-[gamma]-deficient bone marrow, alone or co-cultured with spleen T-cells from wild-type, but not from CD1d-deficient, donors; (ii) IFN-[gamma] neutralization; and (iii) recombinant IFN-[gamma], showed that these effects of [alpha]-GalCer were mediated by IFN-[gamma]. Effects of [alpha]-GalCer on eosinophil production were blocked by LTD4 and NSAIDs. Conclusions and Implications [alpha]-GalCer activation of IFN-[gamma]-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.