Cytokine production by dendritic cells genetically engineered to express IL‐4: induction of Th2 responses and differential regulation of IL‐12 and IL‐23 synthesis

Abstract

Japan Arthritis Res Ther 2003, 5(Suppl 3):1 (DOI 10.1186/ar800) Apoptosis is a principal mechanism in metazoans by which superfluous or potentially harmful cells are eliminated. Deregulation of this process leads to a variety of diseases such as cancer and autoimmune diseases. Stimuli that can induce apoptosis are relatively diverse, and include the death factors (Fas ligand, tumor necrosis factor and TRAIL), DNA damage, and oxidative stress. Regardless of the origin of the apoptotic stimulus, commitment to apoptosis leads to activation of caspases, a family of cysteine proteases. Cleavage of a select group of cellular substrates by caspases is responsible for the morphological and biochemical changes that characterize apoptotic cell death. The degradation of nuclear DNA into nucleosomal units is one of the features of apoptotic cell death, and is mediated by a caspase-activated DNase (CAD). Cells deficient in CAD undergo cell death without the DNA fragmentation, but CAD-null mice did not show any adverse phenotypes. A close examination of the apoptotic cells in these mice indicated that apoptotic cells are always in macrophages. It seems that at an early stage of apoptosis, the dying cells present an 'eat me signal' on their surface. This signal is recognized by macrophages for engulfment, and DNase II in the lysosomes of macrophages degrades DNA of apoptotic cells. Mice deficient in both CAD and DNase II genes were established, and the development of various organs was found to be severely impaired in these mutant mice. The mice accumulated a large amount of undigested DNA in macrophages in various tissues during development. This accumulation of DNA in macrophages activated the innate immunity to induce the expression of the interferon β gene. The interferon thus produced seems to be responsible for the impaired tissue development. These results indicate that the degradation of DNA during apoptotic cell death is an essential step of apoptosis to maintain mammalian homeostasis. Osteoarthritis (OA) has been considered a biomechanically driven, degenerative disease of cartilage. However, the OA disease process affects not only the cartilage, but also the entire joint structure; and within the bone, cartilage and synovium of affected joints, profound metabolic changes transpire, which include the production of growth factors, nitric oxide (NO), prostaglandins (PGs), leukotrienes (LTs), IL-1β, tumor necrosis factor alpha, IL-6, and IL-8. The autocrine production of IL-1β by OA cartilage has been of particular interest, since both ex vivo human and in vivo animal studies indicate that IL-1 antagonists effectively attenuate cartilage degradation. Microarray technology has demonstrated differential expression in OA cartilage of a variety of IL-1-induced, NFβB-dependent genes. Among IL-β-induced products of OA cartilage are various eicosanoids, which include E 2 , PGD 2 , LTB 4 , PGF 1α , PGF 2α and thromboxane. Treatment of OA cartilage with cyclooxygenase (COX) inhibitors increases LTB 4 production threefold to five...

Interleukin‐17 as a molecular target in immune‐mediated arthritis: Immunoregulatory properties of genetically modified murine dendritic cells that secrete interleukin‐4

“…Neutralizing IFN␥ has been shown to increase the generation of Th17 cells (28,29). IL-4 DCs produce increased amounts of IL-12 and IFN␥ after stimulation with lipopolysaccharide or CD40L (25). We also evaluated the effect of IL-12 and IFN␥ in our system.…”

“…IL-12 is a potent inducer of IFN␥ (19,30), and it has recently been shown that inhibition of IFN␥ can enhance the development of IL-17-producing T cells (28). IL-4 DCs produce increased quantities of IL-12 and IFN␥, as compared with untransduced DCs, after stimulation with CD40L and lipopolysaccharide (25) (Figure 1A). We therefore evaluated the role of IL-12 and IFN␥ in our system.…”

“…The molecular mechanisms by which IL-4 DCs alter an ongoing immune response in vivo are not yet understood in detail, although previous studies have shown that the polyclonal response of splenic T cells shifts to Th2 after administration of IL-4 DCs. However, there is no evidence for the suppression of IL-12 expression in IL-4 DCs despite a down-regulation of the expression of the IL-23 p19 subunit (25).…”

“…DCs are professional antigen-presenting cells that are capable of activating and regulating T lymphocytes (23). Previous studies in our laboratory have shown that a single injection of bone marrow-derived DCs genetically engineered to express IL-4 reduces the incidence and severity of CIA and alters primary immune responses in vivo (24,25). Such effects were not produced by T cells or by fibroblasts overexpressing IL-4, which suggests that the migratory properties of DCs are required.…”

Fluvastatin reverses endothelial dysfunction and increased vascular oxidative stress in rat adjuvant‐induced arthritis

“…The threshold cycle is the PCR cycle at which an increase in the fluorescent emission above the baseline signal is first detected. Since the values of the threshold cycle decrease proportionally with increased target quantity, they were used to determine the relative cDNA amounts in each sample and to evaluate levels of p22phox, p47phox, gp91phox, and eNOS messenger RNA 1828 HARUNA ET AL (mRNA), which were normalized to the quantity of GAPDH mRNA as described previously (24). Measurement of fluvastatin, adiponectin, and BH 4 .…”