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ABSTRACT: CpG DNA is extremely effective at protecting primary B cells or B cell lines against apoptosis induced by multiple different
stimuli. These protective effects are mediated through a chloroquine-sensitive pathway and are associated with increased activity
of NF-κB and increased expression of the anti-apoptotic factor, BCLXL. This anti-apoptotic property of CpG DNA is yet another manifestation of its important role in regulating lymphocyte homeostasis.
It seems likely that the anti-apoptotic effects of CpG DNA contribute to its remarkable efficacy as a vaccine adjuvant.
Springer Seminars in Immunopathology 04/2012; 22(1):55-61. · 4.17 Impact Factor
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ABSTRACT: Microbial infections trigger a multiplicity of responses in the host via innate immune sensors, including the Toll-like receptors (TLRs). TLR7 and TLR8, located in endosomes, detect pathogen-derived RNA, which can be mimicked by synthetic single-stranded oligoribonucleotides (ORNs). Detailed analysis of the immunostimulatory properties of numerous silencing RNAs (siRNAs) revealed that almost all tested siRNAs with a phosphodiester backbone actively stimulated cytokine production in human peripheral blood immune cells, but not all of them did contain previously described guanosine/uridine TLR7 or adenosine/uridine TLR8 motifs. By analysis of sequence variants of these siRNAs (as single- or double-strands), we were able to identify a new immunostimulatory, non-uridine-rich TLR7 motif that is present in many published siRNAs. Interestingly, the activity of this motif is dependent on the backbone chemistry. Phosphorothioate ORNs containing the motif did not stimulate immune activation, whereas phosphodiester ORNs of the same sequence induced a strong TLR7-biased immune response with high amounts of interferon-alpha. Using TLR7- and Myd88-deficient mice, we demonstrated that stimulation by ORNs containing this motif was TLR7 dependent. Our findings are of therapeutic relevance as this motif is present in many siRNA sequences and will to contribute to the immunostimulatory properties of unmodified siRNAs.
Oligonucleotides 06/2011; · 2.80 Impact Factor
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ABSTRACT: Microbial infections trigger a multiplicity of responses in the host via innate immune sensors, including the Toll-like receptors (TLRs). TLR7 and TLR8, located in endosomes, detect pathogen-derived RNA, which can be mimicked by synthetic single-stranded oligoribonucleotides (ORNs). Detailed analysis of the immunostimulatory properties of numerous silencing RNAs (siRNAs) revealed that almost all tested siRNAs with a phosphodiester backbone actively stimulated cytokine production in human peripheral blood immune cells, but not all of them did contain previously described guanosine/uridine TLR7 or adenosine/uridine TLR8 motifs. By analysis of sequence variants of these siRNAs (as single- or double-strands), we were able to identify a new immunostimulatory, non-uridine-rich TLR7 motif that is present in many published siRNAs. Interestingly, the activity of this motif is dependent on the backbone chemistry. Phosphorothioate ORNs containing the motif did not stimulate immune activation, whereas phosphodiester ORNs of the same sequence induced a strong TLR7-biased immune response with high amounts of interferon-alpha. Using TLR7- and Myd88-deficient mice, we demonstrated that stimulation by ORNs containing this motif was TLR7 dependent. Our findings are of therapeutic relevance as this motif is present in many siRNA sequences and will to contribute to the immunostimulatory properties of unmodified siRNAs.
Nucleic acid therapeutics. 06/2011; 21(3):201-14.
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ABSTRACT: Synthetic oligodeoxynucleotides (ODN) containing CpG motifs signal through TLR9 and activate innate immunity resulting in protection against a variety of parasitic, bacterial and viral pathogens in mouse models. However, few studies have demonstrated protection in humans and large animals. In the present investigations, we evaluated protection by CpG ODN in a parainfluenza-3 (PI-3) virus infection in neonatal lambs. Subcutaneous (SC) injection of CpG ODN induced high levels of 2'5'-A synthetase and significantly reduced PI-3 virus shedding in newborn lambs. Furthermore, pre-treatment of newborn lambs with SC CpG ODN 2 days, but not 6 days prior to the virus challenge was protective. In contrast, intratracheal (IT) administration of CpG ODN induced 2'5'-A synthetase but had no significant impact on PI-3 virus shedding in nasal secretions. We conclude that a systemic administration of CpG ODN and the timing of the treatment are critical for the protection of neonatal lambs against a respiratory viral infection.
Comparative immunology, microbiology and infectious diseases 12/2010; 33(6):e111-7. · 2.99 Impact Factor
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ABSTRACT: Unmethylated deoxycytidyl-deoxyguanosin dinucleotide (CpG)-containing oligodeoxynucleotides (ODNs) have been well characterized as agonists for Toll-like receptor 9. We here describe a new class of CpG ODNs, the so-called P-Class, which combines preferred properties of known CpG ODN classes. This P-Class contains two palindromic sequences, enabling it to form concatamers, multimeric units, where each molecule is bound via Watson-Crick basepairing to a second and a third palindrome. The type I interferon-inducing potency and efficacy of the double-palindromic P-Class ODN is substantially higher than that of previously described C-Class ODNs, and they stimulate superior cytokine production upon in vivo application. The multimeric structures of the P-Class can be resolved to monomers and dimers by formulation in low-salt buffer, retaining the strong and potent immune effects. Taken together, we have discovered a novel class of CpG ODNs, the P-Class, with promising superior activity for disease application.
Oligonucleotides 04/2010; 20(2):93-101. · 2.80 Impact Factor
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ABSTRACT: The ability of the host to distinguish between self and foreign nucleic acids is one of the critical factors contributing to the recognition of pathogens by Toll-like receptors (TLRs). Under certain circumstances, eukaryotic self-RNA may reach TLR-containing compartments allowing for self-recognition. Specific modifications were previously demonstrated to suppress immune activation when placed at several positions in an immune stimulatory RNA or silencing RNA (siRNA). However, we show that even a simple natural modification such as a single 2'-O-methylation at different nucleotide positions throughout a sequence derived from a self-RNA strongly interferes with TLR-mediated effects. Such a single modification can even have an inhibitory effect in vitro and in vivo when placed in a different than the immune stimulatory RNA strand acting as suppressive RNA. Several safeguard mechanisms appear to have evolved to avoid cellular TLR-mediated activation by self-RNAs that may under other circumstances result in inflammatory or autoimmune responses. This knowledge can be used to include as few as a single 2'-O-methyl modification at a specific position in a siRNA sense or anti-sense strand to avoid TLR immune effects.
International Immunology 04/2009; 21(5):607-19. · 3.41 Impact Factor
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ABSTRACT: Toll-like receptor 9 (TLR9) agonists have demonstrated substantial potential as vaccine adjuvants, and as mono- or combination therapies for the treatment of cancer and infectious and allergic diseases. Commonly referred to as CpG oligodeoxynucleotides (ODN), TLR9 agonists directly induce the activation and maturation of plasmacytoid dendritic cells and enhance differentiation of B cells into antibody-secreting plasma cells. Preclinical and early clinical data support the use of TLR9 agonists as vaccine adjuvants, where they can enhance both the humoral and cellular responses to diverse antigens. In mouse tumor models TLR9 agonists have shown activity not only as monotherapy, but also in combination with multiple other therapies including vaccines, antibodies, cellular therapies, other immunotherapies, antiangiogenic agents, radiotherapy, cryotherapy, and some chemotherapies. Phase I and II clinical trials have indicated that these agents have antitumor activity as single agents and enhance the development of antitumor T-cell responses when used as therapeutic vaccine adjuvants. CpG ODN have shown benefit in multiple rodent and primate models of asthma and other allergic diseases, with encouraging results in some early human clinical trials. Although their potential clinical contributions are enormous, the safety and efficacy of these TLR9 agonists in humans remain to be determined.
Advanced drug delivery reviews 02/2009; 61(3):195-204. · 11.96 Impact Factor
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Veterinary Immunology and Immunopathology - VET IMMUNOL IMMUNOPATHOL. 01/2009; 128(1):312-312.
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ABSTRACT: Prokaryotic DNA has long been recognized as immunostimulatory. In the last decade the role played by CpG motifs (nucleotide sequence motifs centered on a cytosine-guanine dinucleotide) in bacterial and viral DNA has been elucidated. CpG motifs are detected by the innate immune pattern recognition receptor Toll-like receptor (TLR) 9, the ligation of which activates multiple signal cascades in responding cells. A restricted pattern of TLR9 expression to certain dendritic cells and B cells appears to provide relative specificity in responses, especially in comparison to other TLR ligands. TLR9 activation induces a Th1-like pattern of cytokine release which led to interest in the use of synthetic CpG oligodeoxynucleotides (CpG ODN) for the prevention and treatment of Th2-associated atopic disorders such as asthma. Interestingly, Th1 cytokines do not appear to be necessary for a therapeutic response in preclinical models of atopic asthma. Additional potential mechanisms of action include induction of regulatory-type responses (involving interleukin-10 release), and expression of indoleamine 2,3-dioxygenase. CpG ODN have been shown to prevent and reverse antigen-induced eosinophilic airway inflammation in animal models; human trials are ongoing with encouraging early results when used as a ragweed vaccine adjuvant in allergic upper airway disease.
Drug News & Perspectives 11/2008; 21(8):434-9. · 2.21 Impact Factor
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ABSTRACT: Single-stranded viral RNA (ssRNA) was recently identified as the natural ligand for TLR7 and TLR8. ssRNA sequences from viruses, as well as their synthetic analogues stimulate innate immune responses in immune cells from humans and mice, but their immunostimulatory activity has not been investigated in ruminants. In the present investigations, we tested whether synthetic RNA oligoribonucleotides (ORN) can activate immune cells from cattle. In vitro incubation of bovine peripheral blood mononuclear cells (PBMCs) with ORN-induced production of IL-12, IFN-gamma and TNF-alpha. No significant induction of IFN-alpha was observed. Depletion of CD14+ cells from PBMC abrogated the IL-12 response and consequently the IFN-gamma response, suggesting that CD14+ cells are required for PBMC immune activation with ORN. Consistent with these findings, the putative receptors for ORN (TLR7 and TLR8) were expressed at higher levels in the CD14+ fraction than the CD14- PBMC fraction. Pre-treatment of PBMC with bafilomycin (an inhibitor of phagosomal acidification) prior to stimulation with ORN abolished the cytokine responses, confirming that the receptor(s) which mediate the ORN-induced responses are intracellular. These results demonstrate for the first time that the TLR7/8 agonist ORN's have strong immune stimulatory effects in cattle, and suggest that further investigation on the potential of TLR7/8 ligands to activate innate and adaptive immune responses in domestic animals are warranted.
Veterinary Immunology and Immunopathology 09/2008; 126(3-4):273-82. · 2.08 Impact Factor
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ABSTRACT: The immune stimulatory effects of synthetic CpG DNA, on porcine peripheral blood mononuclear cells (PBMC) have been reported, but little is known about CpG-induced responses in other lymphoid tissues of pigs. We investigated innate immune responses induced by CpG DNA in cells from blood, lymph nodes (LN) and spleens of pigs. Porcine PBMC and lymph node cells (LNC) were stimulated in vitro with three classes (A-, B- and C-class) of CpG oligodeoxynucleotides (ODNs), and a non-CpG control ODN. All three classes of CpG ODNs induced significant production of IFNalpha, TNFalpha, IL-1, IL-6 and IL-12 in PBMC. In contrast, in LNC, only IL-12 was stimulated by all three classes of CpG ODNs, while IFNalpha, and IL-6 were induced by A- and C-class ODNs. No TNFalpha was induced in LNC by any of the ODNs. Significant lymphocyte proliferation was induced in PBMC by all three classes of CpG ODNs and non-CpG control. However, in LNC, B- and C-class ODNs induced significant proliferation, while no proliferation was seen with A-class and non-CpG control ODN. All three classes of ODNs induced NK-like cytotoxicity in PBMC and spleen cells, but were less effective in inducing NK cytotoxicity in LNC. We then investigated the reasons for the relatively poor CpG-induced responses in LNC. Our investigations revealed that LNC had a lower frequency of IFNalpha-secreting cells and expressed low levels of TLR9 mRNA compared to PBMC. We conclude that the lower number of IFNalpha-secreting cells and receptor expression may contribute to the attenuated responses in LNC following stimulation with CpG ODN.
Veterinary Immunology and Immunopathology 07/2008; 123(3-4):324-36. · 2.08 Impact Factor
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Alexandra Forsbach,
Jean-Guy Nemorin,
Carmen Montino,
Christian Müller,
Ulrike Samulowitz,
Alain P Vicari,
Marion Jurk,
George K Mutwiri, Arthur M Krieg,
Grayson B Lipford,
Jörg Vollmer
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ABSTRACT: The TLRs 7, 8, and 9 stimulate innate immune responses upon recognizing pathogen nucleic acids. U-rich RNA sequences were recently discovered that stimulate human TLR7/8-mediated or murine TLR7-mediated immune effects. In this study we identified single-stranded RNA sequences containing defined sequence motifs that either preferentially activate human TLR8-mediated as opposed to TLR7- or TLR7/8-mediated immune responses. The identified TLR8 RNA motifs signal via TLR8 and fail to induce IFN-alpha from TLR7-expressing plasmacytoid dendritic cells but induce the secretion of Th1-like and proinflammatory cytokines from TLR8-expressing immune cells such as monocytes or myeloid dendritic cells. In contrast, RNA sequences containing the TLR7/8 motif signal via TLR7 and TLR8 and stimulate cytokine secretion from both TLR7- and TLR8-positive immunocytes. The TLR8-specific RNA sequences are able to trigger cytokine responses from human and bovine but not from mouse, rat, and porcine immune cells, suggesting that these species lack the capability to respond properly to TLR8 RNA ligands. In summary, we describe two classes of single-stranded TLR7/8 and TLR8 RNA agonists with diverse target cell and species specificities and immune response profiles.
The Journal of Immunology 04/2008; 180(6):3729-38. · 5.79 Impact Factor
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Science 03/2008; 319(5863):576-7. · 31.20 Impact Factor
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ABSTRACT: Chronic hepatitis C virus (HCV) infection results from weak or absent T cell responses. Pegylated-interferon-alpha (IFN-alpha) and ribavirin, the standard of care for chronic HCV, have numerous immune effects but are not potent T cell activators. A potent immune activator such as TLR9 agonist CpG oligodeoxynucleotide (CpG) may complement current treatment approaches.
Peripheral blood mononuclear cells (PBMC) obtained from HCV chronic carriers who failed previous treatment and from healthy donors were incubated in vitro with the three main CpG classes (A, B or C), recombinant IFN-alpha-2b (IntronA) and/or ribavirin. Proliferation and cytokine secretion (IFN-alpha, IL-10 and IP-10) were evaluated.
CpG induced proliferation and cytokine secretion in patterns expected for each CpG class with similar group means for HCV and healthy donors. IntronA and ribavirin, alone or together, had no detectable effects. IntronA and C-Class CpG together induced more IFN-alpha than CpG alone in most subjects. IFN-alpha secretion was proportional to the number of plasmacytoid dendritic cells in PBMC from healthy donors but not HCV donors in whom responses were highly heterogeneous.
The strong immune stimulatory effect of CpG on PBMC isolated from treatment-failed HCV patients suggests possible utility alone or in combination with current HCV antiviral treatment.
Journal of Immune Based Therapies and Vaccines 02/2008; 6:3.
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ABSTRACT: Bacterial DNA, but not vertebrate DNA, causes direct stimulation of several components of the vertebrate immune system. This
activation is due to the presence of unmethylated CpG dinucleotides (1), which are present at the expected frequency in bacterial DNA, but are underrepresented (“CpG suppression”) and methylated
in vertebrate DNA (2). The immunostimulatory effects include direct induction of B cell proliferation and immunoglobulin (Ig) secretion (1), as well as activation of monocytes, macrophages, and dendritic cells to upregulate their expression of costimulatory molecules,
which drive immune responses, and secreting a variety of cytokines, including high levels of IL-12 (3,4). These cytokines then, in turn, stimulate natural killer (NK) cells to secrete IFN-γ and to have increased lytic activity
(5). Overall, CpG DNA induces a Th1 like pattern of cytokine production dominated by IL-12 and IFN-γ, with little secretion
of Th2 cytokines (4,5). These effects can also be obtained with synthetic oligonucleotides (ODN) (6,7) or plasmid DNA vectors (8) containing CpG immunostimulatory motifs. From a teleological view, it appears likely that the rapid immune activation in
response to CpG DNA may have evolved as one component of the innate immune defense mechanisms that recognize structural patterns
specific to microbial molecules.
01/2008: pages 169-172;
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ABSTRACT: Toll-like receptors (TLRs) detect infections by highly conserved components of pathogens that are either not present in our own cells or are normally sequestered in cellular compartments that are inaccessible to the TLRs. Most TLRs are expressed on the cell surface, where they have been shown to detect pathogen-expressed molecules such as lipopolysaccharides and lipopeptides. A subset of TLRs, including TLR3, TLR7, TLR8, and TLR9, are expressed intracellularly within one or more endosomal compartments and detect nucleic acids. Because pathogen and host nucleic acids have very similar structures, these endosomal TLRs may face an extra challenge to induce anti-pathogen immune responses while avoiding the induction of autoimmune diseases. With the rapid growth in understanding of the biology of the TLRs has come an increasing awareness of their effects on autoimmunity, several aspects of which are the focus of this review. First, recent studies have revealed an inappropriate activation of TLR7, TLR8, and TLR9 in systemic lupus erythematosus and several other autoimmune diseases. Secondly, the potential for therapeutic development of TLR antagonists is considered. Finally, with the rapid progress in the development of therapeutic agonists for the TLRs, there is accompanying attention to the theoretical possibility that such therapy may induce autoimmunity or autoimmune diseases.
Immunological Reviews 01/2008; 220:251-69. · 11.15 Impact Factor
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ABSTRACT: Adaptive immunity, which comes about through highly specific recognition of antigenic epitopes on B and T cells, results in
the development of antigen-specific antibodies and cytotoxic T-cell responses. However, these processes rely very heavily
on simultaneous activation of cells of the innate immune system including dendritic cells (DCs), macrophages, and monocytes.
Cells of the innate immune system lack highly specific antigen receptors, but rather rely on a set of pattern recognition
receptors (PRRs), which have a general ability to detect pathogen-associated molecular patterns (PAMPs) that are specific
molecular structures found in pathogens, but not in self tissues (1,2). Many of the PRRs are found in the family of Toll-like receptors (TLR), of which at least 10 types have been identified.
Examples of PAMPs that PRRs detect include endotoxins, flagellin, high mannose proteins, single- and double-stranded viral
ribonucleic acids (RNAs) and the unmethylated CpG dinucleotides in particular base contexts (CpG motifs) that are prevalent
in bacterial and many viral deoxyribonucleic acids (DNAs), but are heavily suppressed and methylated in vertebrate genomes
(1–5). The immune system appears to use the presence of these PAMPs as a “danger signal” that indicates the presence of infection
and activates appropriate defense pathways. Recently there has been broad interest in testing and developing such “danger
signal” ligands of PRRs for immune stimulation, including use as adjuvants to enhance antigen-specific responses.
11/2007: pages 87-110;
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John P Leonard,
Brian K Link,
Christos Emmanouilides,
Stephanie A Gregory,
Daniel Weisdorf,
Jeffrey Andrey,
John Hainsworth,
Joseph A Sparano,
Donald E Tsai,
Sandra Horning, Arthur M Krieg,
George J Weiner
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ABSTRACT: PF-3512676 (formerly CpG 7909) is a novel Toll-like receptor 9-activating oligonucleotide with single-agent antitumor activity that augments preclinical rituximab efficacy. This Phase I trial was designed to investigate the safety, tolerability, and preliminary antitumor activity of PF-3512676 in combination with rituximab.
Patients with relapsed/refractory CD20+ B cell non-Hodgkin's lymphoma received i.v. rituximab (375 mg/m2/week for 4 weeks) and PF-3512676 weekly for 4 weeks either i.v. (0.04, 0.16, 0.32, or 0.48 mg/kg) or s.c. (0.01, 0.04, 0.08, or 0.16 mg/kg). An additional extended-treatment cohort received 4 weeks of 0.24 mg/kg s.c. PF-3512676 in combination with rituximab followed by s.c. PF-3512676 alone weekly for 20 weeks.
Patients (N = 50) had received a median of three prior therapies (range, 1-11) including rituximab in 80% of patients. Treatment-related adverse events occurred in 11 of 19 (58%) i.v. patients, 15 of 19 (79%) s.c. patients, and all 12 patients in the extended-treatment cohort. Most common adverse events were mild to moderate systemic flu-like symptoms and injection-site reactions (s.c. cohorts only). Grade 3/4 neutropenia occurred in four patients. Objective responses occurred in 12 of 50 (24%) patients overall and in 6 of 12 (50%) patients in the extended-treatment cohort, including 2 patients with rituximab-refractory disease.
Brief or extended-duration PF-3512676 can be safely administered in combination with rituximab in patients with relapsed/refractory non-Hodgkin's lymphoma.
Clinical Cancer Research 11/2007; 13(20):6168-74. · 7.74 Impact Factor
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ABSTRACT: Generation of antigen-specific CD8+ T cell responses is considered optimal for an effective immunotherapy against cancer. In this study, we provide a proof of principle that in vitro observed diminished CD8+ T cell response provided a strong in vivo tumor protection. Immunization with an adenovirus vaccine containing ovalbumin (OVA) gene (Ad5-OVA) strongly induces antigen-specific CD8+ T cell responses measured in vitro using various immunological assays. However, in an attempt to augment the antigenic CD8+ T cell response, coinjection of a TLR9 agonist CpG ODN with the viral vaccine unexpectedly reduced the CD8+ T cell responses measured in vitro but provided a remarkably enhanced tumor protection compared to the CD8+ T cell response generated by Ad5-OVA vaccine alone. Interestingly, despite reduced ex vivo/in vitro CD8+ T cell responses following Ad5-OVA+CpG immunization, immunodepletion studies revealed that the augmented anti-tumor immunity was primarily dependent on CD8+ T cells. The magnitude and effector function of anti-OVA CD8+ T cells remain low following primary and secondary antigenic challenge, presenting a dichotomy between in vitro CD8 T cell responses and in vivo anti-tumor immunity. To examine the impact of CpG ODN, we observed that presence of CpG suppresses the CD8+ T cell proliferation both in vitro and in vivo. These data demonstrate that coadministration of adenovirus vaccine with a TLR9 agonist can generate potentially effective tumor-reactive CD8+ T cells in vivo. In addition, the results indicate that widely used standard immune parameters may not predict the vaccine efficacy containing a TLR9 agonist as adjuvant.
International Journal of Cancer 11/2007; 121(7):1520-8. · 5.44 Impact Factor
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ABSTRACT: Mucosal delivery of CpG oligodeoxynucleotide (ODN) in mice has been shown to induce potent innate immunostimulatory responses and protection against infection. We evaluated the efficacy of CpG ODN in stimulating systemic innate immune responses in sheep following delivery to the pulmonary mucosa. Intrapulmonary (IPM) administration of B-Class CpG ODN in saline induced transient systemic responses which included increased rectal temperatures, elevated serum 2'5'-A synthetase and haptoglobin concentrations. The ODN dose required to induce detectable systemic responses following IPM delivery could be reduced by approximately 80% if the CpG ODN was administered in 30% emulsigen instead of saline. Intrapulmonary B-Class CpG ODN formulated in 30% emulsigen produced similar effects when compared to those seen following SC injection. These responses were CpG ODN-specific since control GpC ODN did not induce any detectable response. Intrapulmonary administration of both B-Class and the newly described C-Class CpG ODN produced similar effects indicating that both classes of CpG ODN were comparably effective in stimulating innate immune system following mucosal delivery. Administration of CpG ODN directly into the lungs or delivery of CpG ODN via an intratracheal (IT) infusion also produced similar systemic responses. These observations support the conclusion that mucosal delivery of CpG ODN is an effective route for induction of systemic acute phase responses and antiviral effector molecules in large animals, and may be helpful in controlling systemic infections.
Veterinary Immunology and Immunopathology 03/2007; 115(3-4):357-68. · 2.08 Impact Factor
