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Polyinosinic-polycytidylic Acid (polyinosinic-polycytidylic + acid)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Modulation of 2B4 (CD244) activity and regulated SAP expression in human NK cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2007
Johanna Endt
Abstract The adapter protein SAP is important for the signal transduction of the family of SLAM-related receptors (SRR), which have important immune-modulating functions. The importance of SAP and SRR for a functional immune reaction becomes obvious in patients suffering from X-linked lymphoproliferative disease, which is characterized by non-functional SAP. Here we investigate the regulation of SAP expression in human NK cells. We demonstrate that SAP mRNA expression and protein levels are low in freshly isolated resting NK cells. IL-2 stimulation leads to an up-regulation of SAP expression, which can be enhanced by IL-12, the stimulation of TLR3 by polyinosinic-polycytidylic acid (poly(I:C))and to a lesser extent by IFN-,. EAT-2, a SAP-related adapter protein, is already detectable in resting NK cells and does not change its expression after IL-2 stimulation. The regulation of SAP has functional consequences for the stimulation of NK cell cytotoxicity by 2B4. In resting NK cells, 2B4 stimulation can only enhance NK cell lysis when co-triggered with other activating NK cell receptors. In IL-2-activated NK cells with high SAP expression the triggering of 2B4 alone is sufficient to induce NK cell cytotoxicity, demonstrating a correlation between the regulated SAP expression and the function of 2B4. [source]

Inhibitory effect of the polyinosinic-polycytidylic acid/cationic liposome on the progression of murine B16F10 melanoma

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2006
Taku Fujimura
Abstract Cellular proteins, retinoic acid inducible gene-I and Toll-like receptor 3, sense dsRNA including polyinosinic-polycytidylic acid (PIC) to stimulate innate immune response. The local administration of PIC has been demonstrated to be effective in anti-tumor immunotherapy. However, the effects of PIC delivered cross the cell membrane have not yet been examined. To address this issue, we used a complex of PIC and cationic liposome (PIC liposome) and examined its anti-tumor effects in vitro and in vivo. PIC liposome could directly suppress the growth of B16F10 melanoma in vitro and repeated peritumoral injections of PIC liposome inhibited melanoma growth in a dose-dependent manner. This treatment induced tyrosinase-related protein-2 (TRP-2)-tetramer+ CD8+ cells in the lymph nodes. As the mechanism for its anti-tumor immune response, we showed that the intradermal injection of PIC liposome induced the maturation of dendritic cells (DC). Moreover, the intratumoral injection of immature DC after treatment with PIC liposome significantly increased the number of TRP-2-specific IFN-,-producing cells in the lymph nodes as well as spleen, which resulted in an augmentation of the anti-tumor immune response. These studies demonstrate the potential of peritumoral injection of PIC liposome as immunotherapy for malignant melanoma. [source]

TLR3-mediated signal induces proinflammatory cytokine and chemokine gene expression in astrocytes: Differential signaling mechanisms of TLR3-induced IP-10 and IL-8 gene expression

GLIA, Issue 3 2006
Chanhee Park
Abstract Viral infection is one of the leading causes of brain encephalitis and meningitis. Recently, it was reported that Toll-like receptor-3 (TLR3) induces a double-stranded RNA (dsRNA)-mediated inflammatory signal in the cells of the innate immune system, and studies suggested that dsRNA may induce inflammation in the central nervous system (CNS) by activating the CNS-resident glial cells. To explore further the connection between dsRNA and inflammation in the CNS, we have studied the effects of dsRNA stimulation in astrocytes. Our results show that the injection of polyinosinic-polycytidylic acid (poly(I:C)), a synthetic dsRNA, into the striatum of the mouse brain induces the activation of astrocytes and the expression of TNF-,, IFN-,, and IP-10. Stimulation with poly(I:C) also induces the expression of these proinflammatory genes in primary astrocytes and in CRT-MG, a human astrocyte cell line. Furthermore, our studies on the intracellular signaling pathways reveal that poly(I:C) stimulation activates I,B kinase (IKK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) in CRT-MG. Pharmacological inhibitors of nuclear factor-,B (NF-,B), JNK, ERK, glycogen synthase kinase-3, (GSK-3,), and dsRNA-activated protein kinase (PKR) inhibit the expression of IL-8 and IP-10 in astrocytes, indicating that the activation of these signaling molecules is required for the TLR3-mediated chemokine gene induction. Interestingly, the inhibition of PI3 kinase suppressed the expression of IP-10, but upregulated the expression of IL-8, suggesting differential roles for PI3 kinase, depending on the target genes. These data suggest that the TLR3 expressed on astrocytes may initiate an inflammatory response upon viral infection in the CNS. © 2005 Wiley-Liss, Inc. [source]

Toll-like receptor 3 agonist poly(I:C)-induced antiviral response in human corneal epithelial cells

IMMUNOLOGY, Issue 1 2006
Ashok Kumar
Summary The objective of this study was to examine the expression of Toll-like receptor 3 (TLR3) by human corneal epithelial cells (HCECs) and to determine whether exposure to the TLR3 agonist polyinosinic-polycytidylic acid [poly(I:C)]induces an antiviral response in these cells. Fluorescence-activated cell sorter (FACS) analysis revealed TLR3 to be constitutively expressed and distributed intracellularly in HCECs. Stimulation of HCECs with the TLR3 agonist poly(I:C) induced the activation of nuclear factor (NF)-,B and production of the proinflammatory cytokine interleukin (IL)-6 and the chemokine IL-8. Upon exposure to poly(I:C), HCECs initiated a potent antiviral response resulting in an increase of interferon (IFN)-, mRNA expression (7-fold). Poly(I:C) stimulation also up-regulated mRNA expression of the antiviral chemokine IFN-, inducible protein 10 (IP10), myxovirus resistance gene A and 2,,5,-oligoadenylate synthetase (5-, 10- and 9-fold, respectively), and secretion of IP10. These responses were also induced by exogenously added type 1 IFNs, but could not be blocked by pretreatment of the cells with anti-TLR3 monoclonal antibody, suggesting that the receptor was not expressed on the cell surface. Furthermore, incubation of HCECs with an endosomal acidification inhibitor, chloroquine, markedly inhibited poly(I:C)-mediated IFN-, expression in HCECs. These results suggest that corneal epithelial cells are important sentinels of the corneal innate immune system against viral infection, and that stimulation of TLR3 can induce the expression of key proinflammatory cytokines and chemokines and antiviral genes that help in the defence of the cornea against viral infection. [source]