Dissociazione nell'espressione di IL-12 e IL-23 in cellule dendritiche umane. Ruolo nella differenziazione di Th17

Le cellule dendritiche (DC) sono una eterogenea popolazione di cellule immunitarie derivate dal midollo osseo che hanno un ruolo importante nella regolazione della risposta immunitaria innata a numerosi antigeni, inclusi batteri e agenti virali. Le cellule dendritiche sono APC (Antigen Presenting Cell) cruciali per le risposte immunitarie innate e adattative verso gli antigeni e sono importanti anche per il mantenimento della tolleranza immunologica agli autoantigeni (Banchereau and Steinman,1998). Le DC regolano sia la qualit\ue0 che la durata della risposta immunitaria e l\u2019abilit\ue0 delle DC di attivare le cellule T naive dipende dalla loro maturazione che \ue8 determinata principalmente da segnali provenienti dall\u2019incontro con microorganismi patogeni. Una volta attivate dalle DC le cellule T possono completare la risposta immunitaria interagendo con altre cellule come le cellule B per la produzione di anticorpi, con i macrofagi per il rilascio di citochine e con le cellule bersaglio per la lisi. La maturazione delle DC da parte dei microorganismi comporta delle modificazioni che le rendono adatte all\u2019attivazione dei linfociti T naive nei siti della risposta secondaria. In primo luogo le DC mature subiscono una forte riduzione nella capacit\ue0 di catturare l\u2019antigene a favore di una elevata e prolungata espressione dell\u2019antigene in contesto di MHC (Major Histocompatibility Complex). I linfociti T riconoscono gli antigeni presentati in contesto di MHC e questo segnale determina la specificit\ue0 della risposta per l\u2019antigene mediata dalle cellule T, ma in assenza di un secondo segnale stimolatorio, d\ue0 luogo ad anergia (Eagar et al., 2002). Le DC mature esprimono quindi molecole di costimolazione, in particolare B7-1 (CD80) e B7-2 (CD86) che interagiscono con CD28 espresso alla superficie dei linfociti T naive inducendo la loro proliferazione. L\u2019interazione con microorganismi patogeni induce inoltre la produzione di IL-12, da parte delle DC, che determina una polarizzazione nella differenziazione dei linfociti T CD4+ naive in linfociti Th1. I linfociti Th1 producono citochine come IFN-\uf067 che induce prevalentemente risposte cellulari caratterizzate da infiammazione locale e attivazione di macrofagi che portano all\u2019eliminazione di patogeni intracellulari.not availabl

Reciprocal Activating Interaction between Natural Killer Cells and Dendritic Cells

We analyzed the interaction between human peripheral blood natural killer (NK) cells and monocyte-derived immature dendritic cells (DC). Fresh NK cells were activated, as indicated by the induced expression of the CD69 antigen, and their cytolytic activity was strongly augmented by contact with lipopolysaccharide (LPS)-treated mature DC, or with immature DC in the presence of the maturation stimuli LPS, Mycobacterium tuberculosis or interferon (IFN)-α. Reciprocally, fresh NK cells cultured with immature DC in the presence of the maturation stimuli strongly enhanced DC maturation and interleukin (IL)-12 production. IL-2–activated NK cells directly induced maturation of DC and enhanced their ability to stimulate allogeneic naive CD4+ T cells. The effects of NK cells were cell contact dependent, although the secretion of IFN-γ and TNF also contributed to DC maturation. Within peripheral blood lymphocytes the reciprocal activating interaction with DC was restricted to NK cells, because the other lymphocyte subsets were neither induced to express CD69, nor induced to mature in contact with DC. These data demonstrated for the first time a bidirectional cross talk between NK cells and DC, in which NK cells activated by IL-2 or by mature DC induce DC maturation

IFN-gamma and R-848 dependent activation of human monocyte-derived dendritic cells by Neisseria meningitidis adhesin A.

A soluble recombinant form of Neisseria meningitidis adhesin A (NadADelta351-405), proposed as a constituent of anti-meningococcal B vaccines, is here shown to specifically interact with and immune-modulate human monocyte-derived dendritic cells (mo-DCs). After priming with IFN-gamma and stimulation with NadADelta351-405, mo-DCs strongly up-regulated maturation markers CD83, CD86, CD80, and HLA-DR, secreted moderate quantities of TNF-alpha, IL-6, and IL-8, and produced a slight, although significant, amount of IL-12p70. Costimulation of mo-DCs with NadADelta351-405 and the imidoazoquinoline drug R-848, believed to mimic bacterial RNA, increased CD86 in an additive way, but strongly synergized the secretion of IL-12p70, IL-1, IL-6, TNF-alpha, and MIP-1alpha, especially after IFN-gamma priming. CD86/CD80 overexpression correlated with the occupation of high-(kd approximately 80 nM) and low-(kd approximately 4 muM) affinity binding sites for NadADelta351-405. Alternatively, secretion of IL-12p70 and TNF-alpha, IL-6, and IL-8 corresponded to the occupation of high- or low-affinity receptors, respectively. Mo-DCs matured by IFN-gamma and NadADelta351-405 supported the proliferation of naive CD4+ T lymphocytes, inducing the differentiation of both IFN-gamma and IL-4 producing phenotypes. Our data show that NadA not only is a good immunogen but is as well endowed with a proimmune, self-adjuvating, activity

Mono-DCs treated with IFN-γ were labeled with Smethionine (A and B) or unlabeled (C and D) and stimulated with different combinations of MDP, Pam2C, and Pam3C, with or without R848

After 18 h, supernatants were immunoprecipitated with anti–IL-12 p35, anti–IL-23 p19, or anti–IL-12/23 p40 mAbs and resolved in nonreducing SDS-PAGE (A and B), or were evaluated for IL-12 p75, IL-23, and IL-10 by ELISA (C). In D, cells were lysed at 3, 6, and 12 h, and mRNA accumulation was determined using the QuantiGene multiplex assay. Results in A and B are representative of those obtained in three independent experiments with cells derived from different donors. Data in C are mean ± SE values from mono-DCs derived from three different donors. Results in D were obtained with cells from two different donors and are expressed as the mean ± SD of triplicate cultures. Inverted triangles indicate not done.<p><b>Copyright information:</b></p><p>Taken from "Differential regulation of interleukin 12 and interleukin 23 production in human dendritic cells"</p><p></p><p>The Journal of Experimental Medicine 2008;205(6):1447-1461.</p><p>Published online 9 Jun 2008</p><p>PMCID:PMC2413040.</p><p></p

Mono-DCs treated with IFN-γ or left untreated were labeled with Smethionine (A) or unlabeled (B–E) and stimulated with β-glucan or Pam2C, or with a combination of β-glucan Pam2C, with or without R848

After 18 h, supernatants were immunoprecipitated with anti–IL-12 p35, anti–IL-23 p19, or anti–IL-12/23 p40 mAbs and resolved in nonreducing SDS-PAGE (A) and tested for IL-23, IL-12 p75, and IL-10 production by ELISA (B–D) and for mRNA accumulation using the QuantiGene multiplex assay (E). Results in A are representative of four independent experiments. Results in B are mean ± SE values from mono-DCs derived from 18 donors. Results in C represent individual IL-23 levels from mono-DCs derived from 21 different donors. Results in D are mean ± SE values from five experiments. Results in E are mean ± SD ( = 3) mRNA accumulation in cells derived from three separate donors and lysed at 3 h (right column of each triplet), 6 h (middle column of each triplet), and 12 h (right column of each triplet). Inverted triangles indicate not done.<p><b>Copyright information:</b></p><p>Taken from "Differential regulation of interleukin 12 and interleukin 23 production in human dendritic cells"</p><p></p><p>The Journal of Experimental Medicine 2008;205(6):1447-1461.</p><p>Published online 9 Jun 2008</p><p>PMCID:PMC2413040.</p><p></p