04-001 Sigma-AldrichAnti-JAK2 Antibody, clone 8E10.2

Recombinant adenovirus-engineered dendritic cells (Ad.DCs) are potent immunologic adjuvants of antiviral and anticancer vaccines. The effectiveness of Ad.DC-based vaccines may depend on the ability of Ad.DCs to crosstalk with natural killer (NK) cells and to activate, polarize, and bridge innate and adaptive immunity. We investigated, for the first time, whether and how human Ad.DCs activate NK cells, and compared the Ad.DC function with that of immature DCs and matured DCs (mDCs). We found that adenovirus transduction and lipopolysaccharide/interferon-gamma-induced maturation increased expression of transmembrane tumor necrosis factor (TNF) and trans-presented (trans) interleukin-15 (IL-15) on DCs, leading to enhanced NK cell activation without enhancing DC susceptibility to NK cell-mediated killing. This crosstalk enhanced NK cell CD69 expression, interferon-gamma secretion, proliferation, and antitumor activities, with Ad.DCs being significantly more effective than immature DCs, but less effective than mDCs. The Ad.DC and mDC crosstalk with NK cells was largely prevented by physical separation of DCs and NK cells, and neutralization of total TNF and IL-15, but not by selective sequestration of soluble TNF. These findings demonstrate that both Ad.DCs and mDCs can efficiently promote innate immune functions by activation of NK cells through the cooperative activities of tmTNF and trans-IL-15 mediated by cell-to-cell contact.

Both astrocytes in the central nervous system and fibroblasts in somatic tissues are not only the major sources of extracellular matrix components but also of matrix metalloproteinases (MMPs), a family of enzymes directly involved in extracellular matrix breakdown. We have analyzed the regulation of the expression of MMPs and TIMPs (tissue inhibitors of metalloproteinases) in human primary astrocytes stimulated with oncostatin M (OSM) and other extracellular mediators in comparison with normal human dermal fibroblasts. It was found that OSM induced/enhanced transcription of MMP-1 (interstitial collagenase) and MMP-3 (stromelysin 1) in astrocytes, and MMP-1, MMP-9 (gelatinase B), and TIMP-1 in fibroblasts. Analysis of the signal transduction leading to activation of the MMP-1 gene revealed the presence of an OSM-responsive element (OMRE) encompassing the AP-1 binding site and the signal transducer and activator of transcription (STAT) binding element, which mediate activation by OSM. OMRE is also present in the TIMP-1 gene promoter and, although there are some differences in these two motifs, both appear to be targets for the simultaneous action of OSM-induced nuclear effectors. The induced enhancement of transcription by synergistically acting AP-1 and STAT binding elements in response to OSM is Raf-dependent. Cross-talk between the mitogen-activated protein kinase and JAK-STAT pathways is required to achieve maximal induction of the OMRE-driven transcription by OSM.