We have shown, by using confocal microscopy-based analysis and in vitro functional cellular tests that the amount of fused late endoytic compartments correlates with the potency of in vitro anti-tumor CTL responses, generated with electrofused tumor cell-DC hybridomas. This represents an important tool for predicting the antigen-specific stimulatory capacities of immunohybridomas that can be clinically used as anti-cancer vaccines.
COBISS.SI-ID: 25624281
Resveratrol, a polyphenol with pronounced antioxidative activity induces tolerogenic properties in DCs, especially when added during their in vitro differentiation from human monocytes. It decreases the expression of costimulatory and HLA class II molecules and increases the amount of ILT3 and ILT4 inhibitory molecules on the surface of the treated DCs. Additionally resveratrol decreases production of IL-12p70 and increases the secretion of IL-10. Treated DCs are poor activators of allogeneic T lymphocytes and they induce the onset of Il10-producing T cells.
COBISS.SI-ID: 2729841
Activation of DC-SIGN receptor with its specific ligands during differentiation of DCs from human monocytes, results in a formation of DCs with tolerogenic properties. After their activation with LPS, such DCs can't produce notable amounts of IL-12p70, but increase the production of IL-10. They also increase the expression of inhibitory molecules and are weak inducers of Th1 effector immune responses. During differentiation, the ligation of DC-SIGN down-regulates the STAT6 activation. After activation with LPS such DCs changed their ability to activate STAT1, STAT3, STAT6 and p38 MAPK.
COBISS.SI-ID: 2985329
A novel lectin, isolated from basidiomycete mushroom Clitocybe nebularis and termed C. nebularis lectin (CNL), exhibits an immunostimulatory effect on the most potent antigen presenting cells, the dendritic cells (DCs). Treatment of human monocyte-derived DCs with CNL in doses from 1-10 [micro]g/ml resulted in a dose-dependent induction of overall DC maturation characteristics. Exposure of DCs to CNL for 48h resulted in extensive up-regulation of co-stimulatory molecules CD80, CD86, as well as the maturation marker CD83 and HLA-DR molecules. Such CNL-matured DCs (CNL-DCs) were capable of inducing a Th1-polarized response in naive CD4+CD45RA+ T cells in 5-day allogeneic co-cultures. The allostimulatory potential of CNL-DCs was significantly increased relative to untreated controls, as was their capacity to produce several pro-inflammatory cytokines such as IL-6, IL-8 and TNF-[alpha]. By using a specific TLR4 signaling inhibitor, CLI-095, as well as Myd88 inhibitory peptide, we have shown that DC activation by CNL is completely dependent on the TLR4 activation pathway. Furthermore, activation of TLR4 by CNL was confirmed via TLR4 reporter assay. Measurement of p65 Nf-kB and p38 MAPK phosphorylation levels following CNL stimulation of DCs revealed primarily an increase in Nf-kB activity, with less effect on the induction of p38 MAPK signaling than that of LPS-matured DCs. CNL had the ability to activate human DCs in such a way as to subsequently direct Th1-type T cell responses. Our results encourage the use of mushroom-derived lectins for use in therapeutic strategies, with aims such as to strengthen anti-tumor immune responses.
COBISS.SI-ID: 3099761
Endosomal TLRs play an important role in innate immune response as well as in autoimmune processes. In the therapy of systemic lupus erythematosus, antimalarial drugs chloroquine, hydroxychloroquine, and quinacrine have been used for a long time. Their suppression of endosomal TLR activation has been attributed to the inhibition of endosomal acidification, which is a prerequisite for the activation of these receptors. We discovered that chloroquine inhibits only activation of endosomal TLRs by nucleic acids, whereas it augments activation of TLR8 by a small synthetic compound, R848. Wedetected direct binding of antimalarials to nucleic acids by spectroscopic experiments and determined their cellular colocalization. Further analysis revealed that other nucleic acid-binding compounds, such as propidium iodide, also inhibited activation of endosomal TLRs and colocalized with nucleic acidsto endosomes. We found that imidazoquinolines, which are TLR7/8 agonists,inhibit TLR9 and TLR3 even in the absence of TLR7 or TLR8, and their mechanism of inhibition is similar to the antimalarials. In contrast to bafilomycin, none of the tested antimalarials and imidazoquinolines inhibited endosomal proteolysis or increased the endosomal pH, confirming that inhibition of pH acidification is not the underlying cause of inhibition. We conclude that the direct binding of inhibitors to nucleic acids mask their TLR-binding epitope and may explain the efficiency of those compounds in the treatment of autoimmune diseases.
COBISS.SI-ID: 2971761