ICOS cooperates with CD28, IL-2, and IFN-g and modulates activation of human naïve CD4+ T cells

12 páginas, 7 figuras -- PAGS nros. 2601-2612Several sets of data indicate that ICOS regulates cytokine production in activated T cells, but is less effective on naïve T cells. This work evaluates ICOS function in human naïve CD4+ T cells through an assessment of the effect of soluble forms of the ICOS and CD28 physiological ligands on activation driven by anti-CD3 mAb. ICOS strikingly potentiated secretion of IL-2, IFN-γ, IL-10, and TNF-α, but not IL-4, promoted by optimal stimulation of CD3+CD28, and it was the key switching-factor of activation when cells received suboptimal stimulation of CD3+CD28 or stimulation of CD3 alone in the presence of exogenous IL-2. In these conditions, blockade of IL-2 and IFN-γ showed that ICOS builds up a positive feedback loop with IFN-γ, which required IL-2 and was inhibited by IL-4. By contrast, in the absence of CD28 triggering or exogenous IL-2, ICOS-induced costimulation mainly supported expression of TGF-β1 and FoxP3 and differentiation of regulatory T cells capable to inhibit proliferation of naïve CD4+ T cells driven by allogeneic cells. These data suggest that ICOS favors differentiation of Th effector cells when cooperates with appropriate activation stimuli such as CD3+CD28 or CD3+IL-2, whereas it supports differentiation of regulatory T cells when costimulatory signals are insufficientThis work was partially supported by Telethon grant E1170 (Rome), FISM grant 2003/R/20 (Genoa), PRIN Project (MIUR, Rome), Fondazione Cariplo (Milan), Compagnia di San Paolo (Turin), Fondazione Cassa di Risparmio di Cuneo (Cuneo), Regione Piemonte (Turin), and Associazione “Amici di Jean” (Turin)Peer reviewe

Biased binding of Class IA phosphatidyl inositol 3-kinase subunits to Inducible Costimulator (CD278)

15 páginas, 8 figuras, 1 tabla -- PAGS nros. 3065-3079To better understand T lymphocyte costimulation by inducible costimulator (ICOS; H4; CD278), we analyzed proteins binding to ICOS peptides phosphorylated at the Y191MFM motif. Phosphorylated ICOS binds class IA phosphatidyl inositol 3-kinase (PI3-K) p85α, p50-55α and p85β regulatory subunits and p110α, p110δ and p110β catalytic subunits. Intriguingly, T cells expressed high levels of both p110α or p110δ catalytic subunits, yet ICOS peptides, cell surface ICOS or PI3-kinase class IA regulatory subunits preferentially coprecipitated p110α catalytic subunits. Silencing p110α or p110δ partially inhibited Akt/PKB activation induced by anti-CD3 plus anti-ICOS antibodies. However, silencing p110α enhanced and silencing p110δ inhibited Erk activation. Both p110α- and p110δ-specific inhibitors blocked cytokine secretion induced by TCR/CD3 activation with or without ICOS costimulus, but only p110α inhibitors blocked ICOS-induced cell elongation. Thus, p110α and p110δ are essential to optimal T cell activation, but their abundance and activity differentially tune up distinct ICOS signaling pathwaysThis work was supported by grants PI070620 and PI070484 (Fondo de Investigación Sanitaria, Ministerio de Ciencia e Innovación, Spain) and by AIRC (Milan) (to U.D.)Peer reviewe

Expression of functional NK(1) receptors in human alveolar macrophages: superoxide anion production, cytokine release and involvement of NF-κB pathway

1. Substance P (SP) is deeply involved in lung pathophysiology and plays a key role in the modulation of inflammatory-immune processes. We previously demonstrated that SP activates guinea-pig alveolar macrophages (AMs) and human monocytes, but a careful examination of its effects on human AMs is still scarce. 2. This study was undertaken to establish the role of SP in human AM isolated from healthy smokers and non-smokers, by evaluating the presence of tachykinin NK(1) receptors (NK-1R) and SP's ability to induce superoxide anion (O(2)(−)) production and cytokine release, as well as activation of the nuclear factor-κB (NF-κB) pathway. 3. By Western blot analysis and immunofluorescence, we demonstrate that authentic NK-1R are present on human AMs, a three-fold enhanced expression being observed in healthy smokers. These NK-1R are functional, as SP and NK(1) agonists dose-dependently induce O(2)(−) production and cytokine release. In AMs from healthy smokers, SP evokes an enhanced respiratory burst and a significantly increased release of tumor necrosis factor-α as compared to healthy non-smokers, but has inconsistent effects on IL-10 release. The NK(1) selective antagonist CP 96,345 ((2S,3S)-cis-2-diphenylmethyl-N[(2-methoxyphenyl)-methyl]-1-azabicyclo-octan-3-amine)) competitively antagonized SP-induced effects. 4. SP activates the transcription factor NF-κB, a three-fold increased nuclear translocation being observed in AMs from healthy smokers. This effect is receptor-mediated, as it is reproduced by the NK(1) selective agonist [Sar(9)Met(O(2))(11)]SP and reverted by CP 96,345. 5. These results clearly indicate that human AMs possess functional NK-1R on their surface, which are upregulated in healthy smokers, providing new insights on the mechanisms involved in tobacco smoke toxicity