Here we show that the LPS stimulus induced a stronger homogeneous maturation
effect, while the hypoxia stimulus showed a diverse degree of response. It is well known that in activating innate immunity, LPS induces DC maturation by ligand-driven Toll-like receptor (TLR) activation . Our current results show that LPS and hypoxia induced mean fluorescence of mature phenotype DC markers differently from non-stimulated iDCs, but examining these markers individually to compare the two stimuli we found a down-regulation of CD86 for only hypoxia DC. Also, only CD40 and CD83 were expressed to the same degree for both hypoxia and LPS stimulation, whereas for the other surface markers (CD80, CD86, CD54 and HLA-DR) LPS induced Talazoparib price a significant up-regulation Selleckchem LDK378 at least two times greater than did hypoxia. Recently, Jantsch et al.  described similar
results with an increase in CD80, CD86 and major histocompatibility complex (MHC)-II expression in DCs treated with LPS together with hypoxia, compared to cells treated only with LPS. In contrast, CD80 and CD86 expression decreased slightly under hypoxia alone, whereas MHC-II expression remained unchanged. Sekar et al.  generated plasmacytoid-like DC, attenuated IFN-γ production and decreased CD86 as well as MHC-I surface exposure under hypoxia. These findings suggest that LPS probably promotes a more conventional DC profile, while hypoxia appears to create an imbalance in plasmacytoid-like DC phenotypes [28, 29]. ABC transporters 4-Aminobutyrate aminotransferase are described fully in nephrotoxicity models in kidney transplantation, modulating the pharmacokinetics of many immunosuppressors. It is also known that P-glycoprotein is involved in DC maturation. Pendse et al.  defined a novel role for Pgp in DC maturation, identifying this transporter as a potential novel therapeutic target in allotransplantation. Schroeijers et al.  showed that human monocyte-derived DCs express Pgp at all maturation stages, and that they are up-regulated during DC maturation. Randolph et al.  found that Langerhans cells express Pgp and observed that their blockade
inhibited migration of these cells. Although there is some consistent literature in this field, the precise role of Pgp and MRP1 in DC migration and maturation is, as yet, not known precisely, especially under hypoxia . Concerning our results, the immunofluorescence staining that revealed higher expression of Pgp and MRP1 in DC LAMP-positive mDCs versus iDCs suggested initially that Pgp plays a role in the maturation of iDCs under hypoxia. To explore further the mechanisms involved in DC maturation under hypoxia, and taking into account the potential role of ABC transporters in this process, we were tempted to analyse the role of the ABC transporters. The addition of three specific inhibitors shifted the ratio of mature and immature DCs achieved after hypoxia or LPS stimuli.