Podcasts about cpg dna

The pathomechanisms of the progression of chronic kidney diseases involve progressive glomerulosclerosis with renal parenchymal cell loss by proapoptotic factors. Tumor necrosis factor-alpha (TNF-α) is a proapoptotic cytokine that is produced by macrophages as well as by a variety of cell types. TNF-α signaling regulates cell survival and death. Like in other inflammatory renal diseases, the increased intrarenal TNF-α expression contributes to the disease progression of Alport nephropathy, “a non-inflammatory” murine CKD model. I show that TNF-α expressed by podocytes as well as by infiltrating leukocytes progressively activates renal parenchymal cells, inducing apoptotic pathways that can trigger glomerulosclerosis in Alport disease. The blockade of TNF-α by etanercept prolonged mean survival of Col4a3-deficient mice. The beneficial effect on life span was associated with a significant improvement of the glomerulosclerosis, proteinuria, and the glomerular filtration rate (GFR). In particular, etanercept treatment significantly increased the number of glomerular podocytes (WT-1 and nephrin co-staining) and the renal mRNA expression of nephrin and podocin without affecting markers of renal inflammation. The increased number of podocytes was consistent with less TUNEL-positive podocytes that undergo apoptosis. Importantly, exogenous signals, e.g. infections or toxins, have the potential to regulate the influx of immune cells including dendritic cells, macrophages, neutrophils, and T cells. Here I report a large influx of leukocyte subsets that are mostly dendritic cells and macrophages in Col4a3-deficient mice as compared to wildtype mice. While bacterial endotoxin treatment had no effect on the renal disease progression, bacterial cytosine-guanine (CpG)-DNA exacerbated all aspects of Alport nephropathy and reduced the overall life span of Col4a3-deficient mice. This effect of CpG-DNA was associated with a significant increase of renal CD11b+/Ly6Chigh macrophages, intrarenal production of TNF-α, iNOS, IL-12, and CXCL10. CpG-DNA switched intrarenal macrophages from non-activated phenotype (M2) towards the classically activated form (M1). These M1 macrophages increased the secretion of TNF-α, which accelerated the disease progression of Alport nephropathy by inducing podocyte loss. Taken together, I demonstrated that TNF-α is a crucial cytokine which induces podocyte loss in the natural course of the progression of Alport nephropathy. Moreover, the expression of TNF-α is enhanced by selective exogenous factors, e.g. TLR9 activation, which alter the phenotype of renal macrophages towards the M1 phenotype. TNF-α blockade might therefore represent a novel therapeutical option to delay the progression of Alport nephropathy and potentially of other forms of glomerulosclerosis in non-inflammatory and inflammatory conditions.

Non-CpG-DNA and 3P-RNA activated mesangial cells to produce inflammatory cytokines and type 1 interferons in TLR-independent manner. Both ligands induced similar gene expression patterns in mesangial cells. This data unravelled the existence of TLR-independent pathways and production of type1 interferons in mesangial cells. These results substantiate the idea that, immune complexes that are associated with nucleic acids can activate glomerular cells via TLR-independent manner, which leads to glomerular inflammation. Furthermore, exposure of non-CpG-DNA and 3P-RNA in MRLlpr/lpr mice aggravated the disease pathology in different manner. Even though 3P-RNA and non-CpG-DNA induced similar gene expression in mesangial cells but in vivo both ligands aggravated the disease in different fashion. 3P-RNA induced type I IFN signaling and decreased the number of regulatory T cells while non-CpG-DNA induced plasma cell expansion, lymphoproliferation and splenomegaly. However, both ligands induced the production of dsDNA autoantibodies and increased the glomerular deposition of IgG. These data suggest that viral 3P-RNA and non-CpG-DNA differently modulate autoimmunity but still both aggravate autoimmune tissue injury by activating non-immune cells at the tissue level

Die beiden Pathogen-assoziierten molekularen Muster, CpG-Oligonukleotide, als Imitate bakterieller DNA, und LPS, sind in der Lage, das menschliche Immunsystem zu stimulieren. Vor Entdeckung der Toll-like Rezeptoren konnte nicht zwischen direkten und indirekten Effekten von CpG-Oligonukleotiden und LPS auf Zellen des menschlichen Immunsystems unterschieden werden. Durch die Entdeckung der Toll-like Rezeptoren und vor allem die Charakterisierung von TLR9 als Rezeptor für CpG und TLR4 als Rezeptor für LPS entstand die Möglichkeit, die Zielzellen von PAMPs an Hand der Expression der dazugehörigen Rezeptoren zu definieren. Dendritische Zellen sind im Immunsystem des Menschen essenziell für die Auslösung einer Immunantwort. Sie sind in der Lage, eindringende Pathogene an Hand von PAMPs schnell und sicher zu erkennen, und daraufhin eine passende Immunantwort zu initiieren. Zwei Subpopulationen von dendritischen Zellen konnten kürzlich im peripheren Blut identifiziert werden: Plasmazytoide dendritische Zellen (PDC) und myeloide dendritische Zellen (MDC). In der vorliegenden Arbeit wurden die Unterschiede zwischen PDC und MDC in ihren Reaktionen auf CpG-Oligonukleotide, LPS und CD40 Ligand charakterisiert. Funktionelle Untersuchungen zeigten, dass nur PDC und nicht MDC direkte Zielzellen von CpG-ODN im humanen Immunsystem darstellen, während LPS MDC aktiviert, jedoch nicht PDC. Damit konsistent konnte auf molekularbiologischer Ebene nachgewiesen werden, dass PDC TLR9 exprimieren, jedoch nicht TLR4, während MDC den für die Erkennung von LPS notwendigen Rezeptor TLR4 besitzen, aber TLR9 nicht exprimieren. In gemischten Populationen reagierten auch myeloide dendritische Zellen auf CpG-Oligodesoxynukleotide, was auf eine indirekte Aktivierung durch plasmazytoide dendritische Zellen hinweist. PDC reagierten nach Stimulation mit ODN 2006 mit einer Hochregulation von Reifemarkern und kostimulatorischer Moleküle, der Expression von Chemokinrezeptoren, der Produktion proinflammatorischer Chemokine und einer verminderten Apoptoserate. Nach Stimulation mit ODN 2216 sezernierten sie große Mengen IFN-α, während ODN 2006 für die Induktion von IFN-α eine Kostimulation mit CD40 Ligand benötigte. Weder ODN 2006, ODN 2216 oder CD40 Ligand alleine waren in der Lage, IL-12 in PDC zu induzieren, die synergistische Stimulation von PDC mit CpG-ODN und CD40 Ligand führen jedoch zur Produktion großer Mengen an IL-12. Unter optimaler Stimulation mit ODN 2006 und CD40 Ligand können PDC damit gleichzeitig IL-12 und IFN-α produzieren. Das Verhältnis der produzierten Zytokine ist dabei abhängig vom Differenzierungsgrad der PDC. Durch zunehmende Ausreifung der PDC mit IL-3 verschiebt sich nach der Stimulation das Produktionsverhältnis an sezernierten Zytokinen zugunsten von IL-12. Ausreifung mit ODN 2006 ermöglicht PDC, zudem naive allogene CD4 Zellen zu aktivieren, und induziert in Kokulturen IL-12-abhängig ein Th1-gerichtetes Zytokinprofil in den CD4 T-Zellen. IFN-α schien dabei eine geringe Rolle zu spielen. Durch die Charakterisierung der PDC als TLR9-tragende Zielzelle für CpG-DNA, trägt diese Arbeit entscheidend dazu bei, die PDC als Schlüsselzelle für die physiologischen Wirkungen von TLR9-Liganden zu identifizieren und zu verstehen. Dies ist von hoher Relevanz für die Entwicklung therapeutischer Anwendungen von CpG-ODN in der Tumortherapie, Asthmabehandlung, Infektionsprophylaxe und als Adjuvans bei Impfungen.

Nucleic acids that occur free or as immune complexes may trigger immune activation leading to aggravation of diseases with autoimmune predisposition. TLR3 and TLR 9 represent receptors that signal for viral and bacterial nucleic acids respectively. pI:C RNA, a synthetic double stranded RNA with identical properties to that viral origin activates TLR3 led to aggravation of lupus nephritis, a form of immune complex glomerulonephritis, in pre-existing lupus in MRLlpr/lpr mice. Exposure to pI:C RNA (a structural analogue of viral dsRNA) can aggravate lupus nephritis through TLR3 on antigen-presenting cells and glomerular mesangial cells. pI:C RNA–induced cytokine and chemokine production represents a major mechanism in this context. Likewise, CpG DNA a classical activator for TLR-9 led to disease aggravation in this mouse model albeit, through mechanisms that shared some commonality as well as differences to that observed with pI:C RNA. Apparently, pathogen associated immunomodulation relates to the cell-type-specific expression pattern of the respective pattern-recognition receptor. dsRNA-induced disease activity is independent of B cell activation and humoral antichromatin immunity in experimental SLE and therefore differs from CpG-DNA–induced autoimmunity. These findings contribute to the understanding of pathogen-associated modulation of autoimmunity but may also be involved in the pathogenesis of other types of inflammatory kidney diseases, e.g., flares of IgA nephropathy, renal manifestations of chronic hepatitis C virus infection, and renal vasculitis. Further, besides signifying the role of foreign and self-DNA as a pathogenic factor in autoimmune disease activity in lupus, this detailed study reveals, that certain synthetic G-rich nucleic acids may potentially block nucleic acid specific TLR functions and thus prove beneficial in arresting disease activity during progressive systemic lupus. One such G-rich DNA employed in this study has proven to be beneficial and suppressed systemic lupus in MRLlpr/lpr mouse model. Thus, modulating the CpG-DNA - TLR9 pathway may offer new opportunities for the understanding and treatment of lupus.

Tue, 27 Jul 2004 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/2492/ https://edoc.ub.uni-muenchen.de/2492/1/Bock_Carmen_Maria.pdf Bock, Carmen Maria