Activation of human B cells by phosphorothioate oligodeoxynucleotides

Considerations in the Preclinical Assessment of the Safety of Antisense Oligonucleotides

The nucleic acid therapeutics field has made tremendous progress in the past decades. Continuous advances in chemistry and design have led to many successful clinical applications, eliciting even more interest from researchers including both academic groups and drug development companies. Many preclinical studies in the field focus on improving the delivery of antisense oligonucleotide drugs (ONDs) and/or assessing their efficacy in target tissues, often neglecting the evaluation of toxicity, at least in early phases of development. A series of consensus recommendations regarding regulatory considerations and expectations have been generated by the Oligonucleotide Safety Working Group and the Japanese Research Working Group for the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use S6 and Related Issues (WGS6) in several white papers. However, safety aspects should also be kept in sight in earlier phases while screening and designing OND to avoid subsequent failure in the development phase. Experts and members of the network "DARTER," a COST Action funded by the Cooperation in Science and Technology of the EU, have utilized their collective experience working with OND, as well as their insights into OND-mediated toxicities, to generate a series of consensus recommendations to assess OND toxicity in early stages of preclinical research. In the past few years, several publications have described predictive assays, which can be used to assess OND-mediated toxicity in vitro or ex vivo to filter out potential toxic candidates before moving to in vivo phases of preclinical development, that is, animal toxicity studies. These assays also have the potential to provide translational insight since they allow a safety evaluation in human in vitro systems. Yet, small preliminary in vivo studies should also be considered to complement this early assessment. In this study, we summarize the state of the art and provide guidelines and recommendations on the different tests available for these early stage preclinical assessments.

Post-genomic platform for development of oligonucleotide vaccines against RNA viruses: diamond cuts diamond

The coronavirus pandemic has starkly demonstrated the need to create highly effective vaccines against various viral diseases. The emerging new platforms for vaccine creation (adenovirus vectors and mRNA vaccines) have shown their worth in the fight against the prevention of coronavirus infection. However, adenovirus vectors and mRNA vaccines have a serious disadvantage: as a rule, only the S protein of the coronavirus is presented as an antigen. This tactic for preventing infection allows the ever-mutating virus to escape quickly from the immunity protection provided by such vaccines. Today, viral genomic databases are well-developed, which makes it possible to create new vaccines on a fundamentally new post-genomic platform. In addition, the technology for the synthesis of nucleic acids is currently experiencing an upsurge in demand in various fields of molecular biology. The accumulated experience suggests that the unique genomic sequences of viruses can act as antigens that trigger powerful humoral and cellular immunity. To achieve this effect, the following conditions must be created: the structure of the nucleic acid must be single-stranded, have a permanent 3D nanostructure, and have a unique sequence absent in the vaccinated organism. Oligonucleotide vaccines are able to resist the rapidly changing genomic sequences of RNA viruses by using conserved regions of their genomes to generate a long-term immune response, acting according to the adage that a diamond cuts a diamond. In addition, oligonucleotide vaccines will not contribute to antibody-dependent enhanced infection, since the nucleic acid of the coronavirus is inside the viral particle. It is obvious that new epidemics and pandemics caused by RNA viruses will continue to arise periodically in the human population. The creation of new, safe, and effective platforms for the production of vaccines that can flexibly change and adapt to new subtypes of viruses is very urgent and at this moment should be considered as a strategically necessary task.

The Immunomodulatory Functions of Various CpG Oligodeoxynucleotideson CEF Cells and H9N2 Subtype Avian Influenza Virus Vaccination

CpG oligodeoxynucleotides (CpG ODN) present adjuvant activities for antigen proteins, which can induce humoral and cellular immune responses to antigens. However, the immunomodulatory functions of CpG ODNs with different sequences are very different. In this paper, six CpG ODNs with different sequences were designed based on CpG2007 as a template. Through the screening of CEF cells in vitro, the stimulating activity of CpG ODNs was determined. Then, two selected CpG ODN sequence backbones were modified by substituting the oxygen with sulfur (S-CpG) and verifying the immune activity. Next, to prove the feasibility of S-CpG as an immune potentiator, two immune models with or without white oil adjuvant were prepared in 20-day-old chicken vaccinations. The screening experiment in vitro showed that the inducing roles of CpG ODN 4 and 5 could strongly stimulate various immune-related molecular expressions. Additionally, CpG ODN 4 and 5 with sulfation modification significantly induced various cytokines’ expressions. Furthermore, CpG ODN 4 and 5 induced the strongly humoral and cellular immune responses during vaccination, in which white oil, as an adjuvant, could significantly improve the immune effect of CpG ODN. These results provide an important experimental basis for exploring the structural characteristics and vaccine immunity of CpG ODN.

Preclinical Safety Assessment of Therapeutic Oligonucleotides

During the last decade, therapeutic oligonucleotide drugs (OND) have witnessed a tremendous development in chemistry and mechanistic understanding that have translated into successful clinical applications. Depending on the specific OND mechanism, chemistry, and design, the DMPK and toxicity properties can vary significantly between different OND classes and delivery approaches, the latter including lipid formulations or conjugation approaches to enhance productive OND uptake. At the same time, with the only difference between compounds being the nucleobase sequence, ONDs with same mechanism of action, chemistry, and design show relatively consistent behavior, allowing certain extrapolations between compounds within an OND class. This chapter provides a summary of the most common toxicities, the improved mechanistic understanding and the safety assessment activities performed for therapeutic oligonucleotides during the drug discovery and development process. Several of the considerations described for therapeutic applications should also be of value for the scientists mainly using oligonucleotides as research tools to explore various biological processes.

The role of bacterial DNA containing CpG motifs in diseases

Bacterial DNA containing unmethylated CpG motifs can activate immune cells to release proinflammatory cytokines. Here, the role of bacterial DNA containing CpG motifs in diseases with a focus on arthritis is discussed. Our studies demonstrate that the intraarticular injection of bacterial DNA and oligodeoxynucleotides containing CpG motifs (CpG ODN) induced arthritis. The induction of arthritis involves the role of macrophages over other cells such as neutrophils, NK cells, and lymphocytes. TNF-α and TNFRI play an important role in the development of arthritis. NF-κB also plays a critical regulatory role in arthritis. Systemic anti-inflammatory treatment, along with antibiotic therapy, has beneficial effects on the course and the outcome of bacterial arthritis. Thus, future treatment strategies for bacterial arthritis should include attempts to minimizing bacterial growth while blocking the proinflammatory effects of the bacterial DNA. Significant therapeutic efficiency has also been shown by CpG ODN-mediated Th1 immune activation in mouse models of cancer, infectious disease, and allergy/asthma.

Oligonucleotide IMT504 Improves Glucose Metabolism and Controls Immune Cell Mediators in Female Diabetic NOD Mice

Type 1 diabetes occurs as a consequence of progressive autoimmune destruction of beta cells. A potential treatment for this disease should address the immune attack on beta cells and their preservation/regeneration. The objective of this study was to elucidate whether the immunomodulatory synthetic oligonucleotide IMT504 was able to ameliorate diabetes in NOD mice and to provide further understanding of its mechanism of action. We found that IMT504 restores glucose homeostasis in a diabetes mouse model similar to human type 1 diabetes, by regulating expression of immune modulatory factors and improving beta cell function. IMT504 treatment markedly improved fasting glycemia, insulinemia, and homeostatic model assessment of beta cell function (HOMA-Beta cell) index. Moreover, this treatment increased islet number and decreased apoptosis, insulitis, and CD45⁺ pancreas-infiltrating leukocytes. In a long-term treatment, we observed improvement of glucose metabolism up to 9 days after IMT504 cessation and increased survival after 15 days of the last IMT504 injection. We postulate that interleukin (IL)-12B (p40), possibly acting as a homodimer, and Galectin-3 (Gal-3) may function as mediators of this immunomodulatory action. Overall, these results validate the therapeutic activity of IMT504 as a promising drug for type 1 diabetes and suggest possible downstream mediators of its immunomodulatory effect.

Bacteriophage-Based Vaccines: A Potent Approach for Antigen Delivery

Vaccines are considered one of the most important bioproducts in medicine. Since the development of the smallpox vaccine in 1796, several types of vaccines for many diseases have been created. However, some vaccines have shown limitations as high cost and low immune responses. In that regard, bacteriophages have been proposed as an attractive alternative for the development of more cost-effective vaccines. Phage-displayed vaccines consists in the expression of antigens on the phage surface. This approach takes advantage of inherent properties of these particles such as their adjuvant capacity, economic production and high stability, among others. To date, three types of phage-based vaccines have been developed: phage-displayed, phage DNA and hybrid phage-DNA vaccines. Typically, phage display technology has been used for the identification of new and protective epitopes, mimotopes and antigens. In this context, phage particles represent a versatile, effective and promising alternative for the development of more effective vaccine delivery systems which should be highly exploited in the future. This review describes current advances in the development of bacteriophage-based vaccines, with special attention to vaccine delivery strategies. Moreover, the immunological aspects of phage-based vaccines, as well as the applications of phage display for vaccine development, are explored. Finally, important challenges and the future of phage-bases vaccines are discussed.

SARS-CoV-2 will constantly sweep its tracks: a vaccine containing CpG motifs in 'lasso' for the multi-faced virus

During the current COVID-19 pandemic, the global ratio between the dead and the survivors is approximately 1 to 10, which has put humanity on high alert and provided strong motivation for the intensive search for vaccines and drugs. It is already clear that if we follow the most likely scenario, which is similar to that used to create seasonal influenza vaccines, then we will need to develop improved vaccine formulas every year to control the spread of the new, highly mutable coronavirus SARS-CoV-2. In this article, using well-known RNA viruses (HIV, influenza viruses, HCV) as examples, we consider the main successes and failures in creating primarily highly effective vaccines. The experience accumulated dealing with the biology of zoonotic RNA viruses suggests that the fight against COVID-19 will be difficult and lengthy. The most effective vaccines against SARS-CoV-2 will be those able to form highly effective memory cells for both humoral (memory B cells) and cellular (cross-reactive antiviral memory T cells) immunity. Unfortunately, RNA viruses constantly sweep their tracks and perhaps one of the most promising solutions in the fight against the COVID-19 pandemic is the creation of 'universal' vaccines based on conservative SARS-CoV-2 genome sequences (antigen-presenting) and unmethylated CpG dinucleotides (adjuvant) in the composition of the phosphorothioate backbone of single-stranded DNA oligonucleotides (ODN), which can be effective for long periods of use. Here, we propose a SARS-CoV-2 vaccine based on a lasso-like phosphorothioate oligonucleotide construction containing CpG motifs and the antigen-presenting unique ACG-containing genome sequence of SARS-CoV-2. We found that CpG dinucleotides are the most rare dinucleotides in the genomes of SARS-CoV-2 and other known human coronaviruses, and hypothesized that their higher frequency could be responsible for the unwanted increased lethality to the host, causing a ‘cytokine storm’ in people who overexpress cytokines through the activation of specific Toll-like receptors in a manner similar to TLR9-CpG ODN interactions. Interestingly, the virus strains sequenced in China (Wuhan) in February 2020 contained on average one CpG dinucleotide more in their genome than the later strains from the USA (New York) sequenced in May 2020. Obviously, during the first steps of the microevolution of SARS-CoV-2 in the human population, natural selection tends to select viral genomes containing fewer CpG motifs that do not trigger a strong innate immune response, so the infected person has moderate symptoms and spreads SARS-CoV-2 more readily. However, in our opinion, unmethylated CpG dinucleotides are also capable of preparing the host immune system for the coronavirus infection and should be present in SARS-CoV-2 vaccines as strong adjuvants.

Complement Receptor Type 1 (CR1, CD35), the Inhibitor of BCR-Mediated Human B Cell Activation, Differentially Regulates TLR7, and TLR9 Induced Responses

The complement system and Toll-like receptors (TLRs) are essential contributors of innate immunity. Separate activation of these systems has been shown to play a role in initiating and shaping the adaptive immune response, however the modulation of various B cell functions by the simultaneous involvement of these two systems has not yet been uncovered. We demonstrate here that occupancy of complement receptor type 1 (CR1, CD35) by its natural, complement component C3-derived ligand significantly and dose dependently reduces the TLR9-induced expression of activation markers, cytokine production, proliferation, and antibody production by human B cells, but has no effect on the TLR7-induced functions. The synergistic response to the simultaneous engagement of either TLR9 or TLR7 along with the BCR however, is significantly inhibited by CR1 occupancy. Our findings imply that both under physiological and pathological conditions, when complement- and TLR-activating microbial and damage products are present in the B cell environment, the cooperation between CR1 and TLR7 or TLR9 provides additional levels of the regulation of human B cell functions.

A proliferation-inducing ligand (APRIL) induced hyper-production of IgA from tonsillar mononuclear cells in patients with IgA nephropathy

IgA nephropathy (IgAN) is a tonsil-related disease. We previously showed that oligodeoxynucleotides with CpG (CpG-ODN) and B-cell activation factor (BAFF) are involved in hyperproduction of IgA from tonsillar mononuclear cells of patients with IgAN (IgAN-TMCs). In this study, we focused on a proliferation-inducing ligand (APRIL), homologous to BAFF. IgAN-TMCs produced more APRIL than non IgAN-TMCs in the presence of both CpG-ODN and control-ODN. TLR9 expression was higher in B-cells of IgAN-TMCs, and treatment with CpG-ODN enhanced transmembrane activator and CAML interactor (TACI) expression. IgA production from IgAN-TMCs was inhibited by APRIL neutralization antibody or TACI blocking antibody, and enhanced by co-treatment of APRIL and CpG-ODN. Serum APRIL levels were higher in patients with IgAN, and decreased after tonsillectomy. These findings suggest that APRIL is involved in the hyperproduction of IgA from IgAN-TMCs, and that CpG-ODN enhanced APRIL-induced IgA production by increasing TACI expression on B-cells of IgAN-TMCs.

Recognizing conserved non-canonical localization patterns of toll-like receptors in tissues and across species

Toll-like receptors (TLR) 1, 2, 4, 5 and 6 were originally characterized as exclusively expressed on the cell surface and TLR 3, 7, 8 and 9 were said to be localized to the endosomes. However, continued research in this area shows that TLR localization may be altered across cell-types, and in response to stimulation, age or disease. Mucosal surfaces must remain tolerant to the commensal flora and thus intracellular or basal lateral localization of TLRs at mucosal surfaces may be necessary to prevent induction of an inflammatory response to commensal flora while still allowing the possibility for the receptors to prime an immune response when a pathogen has crossed the epithelial barrier. Here, we highlight the research specifying 'non-canonical' localization of TLRs in human and animal mucosal tissues and blood-derived cells, while excluding cultured polarized immortalized cells. Reports that only indicate TLR gene/protein expression and/or responsiveness to agonists have been excluded unless the report also indicates surface/intracellular distribution in the cell. Understanding the tissue- and species-specific localization of these specific pattern recognition receptors will lead to a greater appreciation of the way in which TLR ligands promote innate immunity and influence the adaptive immune response. A more comprehensive understanding of this information will potentially aid in the exploitation of the therapeutic or adjuvant potential of selectively localized TLRs and in opening new perspectives in understanding the basis of immunity.

DSP30 enhances the immunosuppressive properties of mesenchymal stromal cells and protects their suppressive potential from lipopolysaccharide effects: A potential role of adenosine

Multipotent mesenchymal stromal cells (MSC) are imbued with an immunosuppressive phenotype that extends to several immune system cells. In this study, we evaluated how distinct Toll-like receptor (TLR) agonists impact immunosuppressive properties of bone marrow (BM)-MSC and explored the potential mechanisms involved. We show that TLR4 stimulation by lipopolysaccharide (LPS) restricted the ability of MSC to suppress the proliferation of T lymphocytes, increasing the gene expression of interleukin (IL)-1β and IL-6. In contrast, stimulation of TLR9 by DSP30 induced proliferation and the suppressive potential of BM-MSC, coinciding with reducing tumor necrosis factor (TNF)-α expression, increased expression of transforming growth factor (TGF)-β1, increased percentages of BM-MSC double positive for the ectonucleotidases CD39+CD73+ and adenosine levels. Importantly, following simultaneous stimulation with LPS and DSP30, BM-MSC's ability to suppress T lymphocyte proliferation was comparable with that of non-stimulated BM-MSC levels. Moreover, stimulation of BM-MSC with LPS reduced significantly the gene expression levels, on co-cultured T lymphocyte, of IL-10 and interferon (IFN)γ, a cytokine with potential to enhance the immunosuppression mediated by MSC and ameliorate the clinical outcome of patients with graft-versus-host disease (GVHD). Altogether, our findings reiterate the harmful effects of LPS on MSC immunosuppression, besides indicating that DSP30 could provide a protective effect against LPS circulating in the blood of GVHD patients who receive BM-MSC infusions, ensuring a more predictable immunosuppressive effect. The novel effects and potential mechanisms following the stimulation of BM-MSC by DSP30 might impact their clinical use, by allowing the derivation of optimal "licensing" protocols for obtaining therapeutically efficient MSC.

Complement Receptor Type 1 Suppresses Human B Cell Functions in SLE Patients

Complement receptors (CRs) play an integral role in innate immunity and also function to initiate and shape the adaptive immune response. Our earlier results showed that complement receptor type 1 (CR1, CD35) is a potent inhibitor of the B cell receptor- (BCR-) induced functions of human B lymphocytes. Here we show that this inhibition occurs already at the initial steps of B cell activation since ligation of CR1 reduces the BCR-induced phosphorylation of key signaling molecules such as Syk and mitogen activated protein kinases (MAPKs). Furthermore, our data give evidence that although B lymphocytes of active systemic lupus erythematosus (SLE) patients express lower level of CR1, the inhibitory capacity of this complement receptor is still maintained and its ligand-induced clustering results in significant inhibition of the main B cell functions, similar to that found in the case of healthy individuals. Since we have found that reduced CR1 expression of SLE patients does not affect the inhibitory capacity of the receptor, our results further support the therapeutical potential of CD35 targeting the decrease of B cell activation and autoantibody production in autoimmune patients.

Pleiotropic action of CpG-ODN on endothelium and macrophages attenuates angiogenesis through distinct pathways

There is an integral relationship between vascular cells and leukocytes in supporting healthy tissue homeostasis. Furthermore, activation of these two cellular components is key for tissue repair following injury. Toll-like receptors (TLRs) play a role in innate immunity defending the organism against infection, but their contribution to angiogenesis remains unclear. Here we used synthetic TLR9 agonists, cytosine-phosphate-guanosine oligodeoxynucleotides (CpG-ODN), to investigate the role of TLR9 in vascular pathophysiology and identify potential therapeutic translation. We demonstrate that CpG-ODN stimulates inflammation yet inhibits angiogenesis. Regulation of angiogenesis by CpG-ODN is pervasive and tissue non-specific. Further, we noted that synthetic CpG-ODN requires backbone phosphorothioate but not TLR9 activation to render and maintain endothelial stalk cells quiescent. CpG-ODN pre-treated endothelial cells enhance macrophage migration but restrain pericyte mobilisation. CpG-ODN attenuation of angiogenesis, however, remains TLR9-dependent, as inhibition is lost in TLR9 deficient mice. Additionally, CpG-ODNs induce an M1 macrophage phenotype that restricts angiogenesis. The effects mediated by CpG-ODNs can therefore modulate both endothelial cells and macrophages through distinct pathways, providing potential therapeutic application in ocular vascular disease.

Extracellular Release of CD11b by TLR9 Stimulation in Macrophages

CpG-DNA upregulates the expression of pro-inflammatory cytokines, chemokines and cell surface markers. Investigators have shown that CD11b (integrin αM) regulates TLR-triggered inflammatory responses in the macrophages and dendritic cells. Therefore, we aimed to identify the effects of CpG-DNA on the expression of CD11b in macrophages. There was no significant change in surface expression of CD11b after CpG-DNA stimulation. However, CD11b was released into culture supernatants after stimulation with phosphorothioate-backbone modified CpG-DNA such as PS-ODN CpG-DNA 1826(S). In contrast, MB-ODN 4531 and non-CpG-DNA control (regardless of backbone type and liposome-encapsulation) failed to induce release of CD11b. Therefore, the context of the CpG-DNA sequence and phosphorothioate backbone modification may regulate the effects of CpG-DNA on CD11b release. Based on inhibitor studies, CD11b release is mediated by p38 MAP kinase activation, but not by the PI3K and NF-κB activation. CD11b release is mediated by lysosomal degradation and by vacuolar acidification in response to CpG-DNA stimulation. The amount of CD11b in the exosome precipitant was significantly increased by CpG-DNA stimulation in vivo and in vitro depending on TLR9. Our observations perhaps give more insight into understanding of the mechanisms involved in CpG-DNA-induced immunomodulation in the innate immunity.

Hepatitis B virus therapy: What’s the future holding for us?

Hepatitis B is one of the leading causes of liver cancer worldwide and unfortunately the number of people affected with hepatitis B virus (HBV) infection is still on the rise. Although the HBV has been known to cause fatal illness since decades but the population effected by this lethal virus have still only a few options for its management. The major treatment strategies include interferons and nucleos(t)ide analogues. These agents have so far produced unsatisfactory results in terms of complete virus eradication. Interferons cannot be used for long term therapy because of their potential side effects. Prolong treatment with nucleos(t)ide analogues has also been reported to cause serious side effects besides the increasing resistance by the virus. The need for new innovative solutions for treatment of HBV has been realized by global research institutes and pharmaceutical industry. Present review focuses in detail on the new ideas that are being transformed into therapeutic tools for use as future therapies in HBV infection. Modern drug designing and screening methods have made the drug discovery process shorter and more reliable. HBV therapeutics will take a new turn in coming years owing to these intelligent drug designing and screening methods. Future therapy of HBV is aiming to include the use of vaccines (both prophylactic and therapeutic), immunomodulators such as antibodies, non-nucleoside antivirals such as RNAi and inhibitors of viral life cycle.

Patients with chronic lymphocytic leukaemia (CLL) differ in the pattern of CTLA-4 expression on CLL cells: the possible implications for immunotherapy with CTLA-4 blocking antibody

Recently, systemic administration of a human monoclonal antibody directed against cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expressed on circulating T cells in patients with chronic lymphocytic leukaemia (CLL) has been considered. Also, CLL cells have been shown to express CTLA-4, increased levels of which in the leukaemic compartment are a predictor of good clinical outcome. Since both CLL and Treg microenvironment cells can be targeted by the CTLA-4 blocking antibody in this immunotherapy approach, the investigation of the functional effect of CTLA-4 blockade on CLL cells might be of potential clinical relevance. The main aim of this study was to examine the effect of CTLA-4 blockade on proliferation activity and apoptosis of CLL cells in patients with low and high CTLA-4 expression. We found that in the high CTLA-4-expressing CLL group, CTLA-4 blockade on the CLL cell surface resulted in a significant increase in the median percentages of Ki67⁺ cells and a tendency to decrease in the proportion of apoptotic cells. In contrast, in the low CTLA-4 expressors, CTLA-4 blockade did not affect the proliferation activity or the frequency of apoptosis. This study reports for the first time the different effect of CTLA-4 blockade on CLL cells in CLL patients depending on the levels of CTLA-4 expression. CTLA-4 blockade seems to induce pro-survival signals in leukaemic cells from CLL patients exhibiting high CTLA-4 expression, suggesting that an immunotherapy approach based on the systemic use of monoclonal anti-CTLA-4 antibodies could be an unfavourable strategy for some CLL patients.

Syk is indispensable for CpG-induced activation and differentiation of human B cells

B cells are efficiently activated by CpG oligodeoxynucleotides (ODNs) to produce pro-inflammatory cytokines and antibody (Ab). Here, we describe a so far unidentified, spleen tyrosine kinase (Syk)-dependent pathway, which is indispensable for CpG-induced human B cell activation. We show that triggering of B cells by CpG results in Syk and src kinase phosphorylation, proliferation, as well as cytokine and Ab production independent of the BCR. Notably, all these functions are abrogated when Syk is inhibited. We demonstrate that CpG-induced Syk activation originates from the cell surface in a TLR9-dependent manner. While inhibition of Syk does not influence the uptake of CpG ODNs, activation of the kinase is a prerequisite for the delivery of CpG into TLR9-containing endolysosomes and for the CpG-induced up-regulation of TLR9 expression. Our results reveal an alternative, Syk-dependent pathway of CpG-induced B cell stimulation, which is initiated at the plasma membrane and seems to be an upstream requirement for endosomal TLR9-driven B cell proliferation and differentiation.

CTLA-4 affects expression of key cell cycle regulators of G0/G1 phase in neoplastic lymphocytes from patients with chronic lymphocytic leukaemia

Previously, we showed that cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is overexpressed in chronic lymphocytic leukaemia (CLL) and its expression is correlated with the expression of the major regulators of G1 phase progression: cyclins D2 and D3, and cyclin-dependent kinase inhibitory protein 1 (p27 (KIP1) ). In the present study, we blocked CTLA-4 on the surface of both CLL cells and normal B lymphocytes to investigate the impact of CTLA-4 on the expression of the mentioned G1 phase regulators. We found that in CLL patients and in healthy individuals, the median proportions of cyclin D2-positive cells as well as cyclin D3(+) cells significantly decreased following CTLA-4 blockade. Moreover, CTLA-4 blockade led to an increase in the median frequencies of p27 (KIP1) -positive cells, although this increase was marked only in CLL patients. Our study showed that CTLA-4 affects the expression of the key regulators of G1 phase progression in CLL cells as well as in normal B lymphocytes and may contribute to a better understanding of the role of CTLA-4 in the regulation of G1 phase progression.

Perspective of Peptide Vaccine Composed of Epitope Peptide, CpG-DNA, and Liposome Complex Without Carriers

The magnitude and specificity of cell-mediated and humoral immunity are critically determined by peptide sequences; peptides corresponding to the B- or T-cell receptor epitopes are sufficient to induce an effective immune response if delivered properly. Therefore, studies on the screening and application of peptide-based epitopes have been done extensively for the development of therapeutic antibodies and prophylactic vaccines. However, the efficacy of immune response and antibody production by peptide-based immunization is too limited for human application at the present. To improve the efficacy of vaccines, researchers formulated adjuvants such as alum, water-in-oil emulsion, and Toll-like receptor agonists. They also employed liposomes as delivering vehicles to stimulate immune responses. Here, we review our recent studies providing a potent method of epitope screening and antibody production without conventional carriers. We adopted Lipoplex(O), comprising a natural phosphodiester bond CpG-DNA and a specific liposome complex, as an adjuvant. Lipoplex(O) induces potent stimulatory activity in humans as well as in mice, and immunization of mice with several peptides along with Lipoplex(O) without general carriers induces significant production of each peptide-specific IgG2a. Immunization of peptide vaccines against virus-associated antigens in mice has protective effects against the viral infection. A peptide vaccine against carcinoma-associated antigen and the peptide-specific monoclonal antibody has functional effects against cancer cells in mouse models. In conclusion, we improved the efficacy of peptide vaccines in mice. Our strategy can be applied in development of therapeutic antibodies or in defense against pandemic infectious diseases through rapid screening of potent B-cell epitopes.

Production of epitope-specific antibodies using peptide-CpG-ODN-liposome complex without carriers and their application as a cancer vaccine in mice

Low efficacy of peptide vaccines limits their potential application. We developed a powerful strategy to produce epitope-specific antibodies using peptides. Immunization with novel formula into mice showed target-specific prophylactic and therapeutic effects against tumors. Our strategy will be useful for rapid eiptope screening, therapeutic antibody production and cancer vaccine development.

Alternative splice variants of AID are not stoichiometrically present at the protein level in chronic lymphocytic leukemia

Activation-induced deaminase (AID) is a DNA-mutating enzyme that mediates class-switch recombination as well as somatic hypermutation of antibody genes in B cells. Due to off-target activity, AID is implicated in lymphoma development by introducing genome-wide DNA damage and initiating chromosomal translocations such as c-myc/IgH. Several alternative splice transcripts of AID have been reported in activated B cells as well as malignant B cells such as chronic lymphocytic leukemia (CLL). As most commercially available antibodies fail to recognize alternative splice variants, their abundance in vivo, and hence their biological significance, has not been determined. In this study, we assessed the protein levels of AID splice isoforms by introducing an AID splice reporter construct into cell lines and primary CLL cells from patients as well as from WT and TCL1^tg C57BL/6 mice (where TCL1 is T-cell leukemia/lymphoma 1). The splice construct is 5′-fused to a GFP-tag, which is preserved in all splice isoforms and allows detection of translated protein. Summarizing, we show a thorough quantification of alternatively spliced AID transcripts and demonstrate that the corresponding protein abundances, especially those of splice variants AID-ivs3 and AID-ΔE4, are not stoichiometrically equivalent. Our data suggest that enhanced proteasomal degradation of low-abundance proteins might be causative for this discrepancy.

Quantitative and in situ detection of oxidatively generated DNA damage 8,5'-cyclo-2'-deoxyadenosine using an immunoassay with a novel monoclonal antibody

Xeroderma pigmentosum (XP) is a genetic disorder associated with defects in nucleotide excision repair, which eliminates a wide variety of helix-distorting types of DNA damage including sunlight-induced pyrimidine dimers. In addition to skin disease, approximately 30% of XP patients develop progressive neurological disease, which has been hypothesized to be associated with the accumulation of a particular type of oxidatively generated DNA damage called purine 8,5'-cyclo-2'-deoxynucleosides (purine cyclonucleosides). However, there are no currently available methods to detect purine cyclonucleosides in DNA without the need for DNA hydrolysis. In this study, we generated a novel monoclonal antibody (CdA-1) specific for purine cyclonucleosides in single-stranded DNA that recognizes 8,5'-cyclo-2'-deoxyadenosine (cyclo-dA). An immunoassay using CdA-1 revealed a linear dose response between known amounts of cyclo-dA in oligonucleotides and the antibody binding to them. The quantitative immunoassay revealed that treatment with Fenton-type reagents (CuCl(2)/H(2)O(2)/ascorbate) efficiently produces cyclo-dA in DNA in a dose-dependent manner. Moreover, immunofluorescent analysis using CdA-1 enabled the visualization of cyclo-dA in human osteosarcoma cells, which had been transfected with oligonucleotides containing cyclo-dA. Thus, the CdA-1 antibody is a valuable tool for the detection and quantification of cyclo-dA in DNA, and may be useful for characterizing the mechanism(s) underlying the development of XP neurological disease.

The LRP1-independent mechanism of PAI-1-induced migration in CpG-ODN activated macrophages

CpG-oligodeoxynucleotides (CpG-ODNs) induces plasminogen activator inhibitor type-1 (PAI-1) expression in macrophages, leading to enhanced migration through vitronectin. However, the precise role of low-density lipoprotein receptor-related protein 1 (LRP1) in PAI-1 induced migration of macrophages in the inflammatory environment is not known. In this study, we elucidated a novel mechanism describing the altered role of LRP1 in macrophage migration depending on the activation state of the cells. Experimental evidence clearly shows that the blocking of LRP1 function inhibited the PAI-induced migration of resting RAW 264.7 cells through vitronectin but exerted a pro-migratory effect on CpG-ODN-activated cells. We also demonstrate that CpG-ODN downregulates the protein and mRNA levels of LRP1 both in vivo and in vitro, a function that depends on the NF-κB signaling pathway, resulting in reduced internalization of PAI-1. This work illustrates the distinct mechanism that PAI-1-induced migration of CpG-ODN-activated cells through vitronectin depends on the interaction of PAI-1 with vitronectin but not LRP1 unlike in the resting cells, where the migration is LRP1 dependent and vitronectin independent. In conclusion, our experimental results demonstrate the altered function of LRP1 in the migration of resting and activated macrophages in the context of microenvironmental extracellular matrix components.

The potential of 1018 ISS adjuvant in hepatitis B vaccines: HEPLISAV™ review

Hepatitis B (HBV) virus infects the liver, and upon chronic infection, can cause liver cirrhosis and hepatocellular carcinoma. Despite universal vaccination programs against the virus, HBV still affects over 2 billion people worldwide, with over 240 million developing a chronic infection. While current alum-adjuvanted vaccines have shown efficacy in promoting seroprotection in healthy adults, 5-10% of immune-competent populations fail to achieve long-lasting seroprotection from these formulations. Furthermore, a large proportion of immunocompromised patients fail to achieve seroprotective antibody titers after receiving these vaccines. A novel vaccine candidate, HEPLISAV™, uses immunostimulatory sequences (ISS), in its formulation that helps induce a robust humoral and cell mediated immunity against HBV. In Phase III clinical trials, HEPLISAV™ has been shown to elicit seroprotective antibody titers with fewer immunizations. Similar safety profiles are demonstrated when compared with current HBV vaccines. For these reasons, HEPLISAV™ is an attractive vaccine to combat this global disease.

Immune stimulating photoactive hybrid nanoparticles for metastatic breast cancer

A therapeutic technology that combines the phototoxic and immune-stimulating ability of photodynamic therapy (PDT) with the widespread effectiveness of the immune system can be very promising to treat metastatic breast cancer. We speculated that the knowledge of molecular mechanisms of existing multi-component therapies could provide clues to aid the discovery of new combinations of an immunostimulant with a photosensitizer (PS) using a nanoparticle (NP) delivery platform. Therapeutic challenges when administering therapeutic combinations include the choice of dosages to reduce side effects, the definitive delivery of the correct drug ratio, and exposure to the targets of interest. These factors are very difficult to achieve when drugs are individually administered. By combining controlled release polymer-based NP drug delivery approaches, we were able to differentially deliver zinc phthalocyanine (ZnPc) based PS to metastatic breast cancer cells along with CpG-ODN, a single-stranded DNA that is a known immunostimulant to manage the distant tumors in a temporally regulated manner. We encapsulated ZnPc which is a long-wavelength absorbing PS within a polymeric NP core made up of poly(d,l-lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG). After coating the outside of the polymeric core with gold NPs (AuNPs), we further modified the AuNP surface with CpG-ODN. In vitro cytotoxicity using 4T1 metastatic mouse breast carcinoma cells shows significant photocytotoxicity of the hybrid NPs containing both ZnPc and CpG-ODN after irradiation with a 660 nm LASER light and this activity was remarkably better than either treatment alone. Treatment of mouse bone marrow derived dendritic cells with the PDT-killed 4T1 cell lysate shows that the combination of PDT with a synergistic immunostimulant in a single NP system results in significant immune response, which can be used for the treatment of metastatic cancer.

The proteasome inhibitor carfilzomib functions independently of p53 to induce cytotoxicity and an atypical NF-κB response in chronic lymphocytic leukemia cells

PURPOSE

The proteasome consists of chymotrypsin-like (CT-L), trypsin-like, and caspase-like subunits that cleave substrates preferentially by amino acid sequence. Proteasomes mediate degradation of regulatory proteins of the p53, Bcl-2, and nuclear factor-κB (NF-κB) families that are aberrantly active in chronic lymphocytic leukemia (CLL). CLL remains an incurable disease, and new treatments are especially needed in the relapsed/refractory setting. We therefore investigated the effects of the proteasome inhibitor carfilzomib (CFZ) in CLL cells.

EXPERIMENTAL DESIGN

Tumor cells from CLL patients were assayed in vitro using immunoblotting, real-time polymerase chain reaction, and electrophoretic mobility shift assays. In addition, a p53 dominant-negative construct was generated in a human B-cell line.

RESULTS

Unlike bortezomib, CFZ potently induces apoptosis in CLL patient cells in the presence of human serum. CLL cells have significantly lower basal CT-L activity compared to normal B and T cells, although activity is inhibited similarly in T cells versus CLL. Co-culture of CLL cells on stroma protected from CFZ-mediated cytotoxicity; however, PI3K inhibition significantly diminished this stromal protection. CFZ-mediated cytotoxicity in leukemic B cells is caspase-dependent and occurs irrespective of p53 status. In CLL cells, CFZ promotes atypical activation of NF-κB evidenced by loss of cytoplasmic IκBα, phosphorylation of IκBα, and increased p50/p65 DNA binding, without subsequent increases in canonical NF-κB target gene transcription.

CONCLUSIONS

Together, these data provide new mechanistic insights into the activity of CFZ in CLL and support phase I investigation of CFZ in this disease.

CpG-Induced IFN-α production of plasmacytoid dendritic cells: time and dosage dependence and the effect of structural modifications to the CpG backbone

Plasmacytoid dendritic cells (pDCs) represent a highly specialized immune cell subset and are considered to be the main sentinels against viral infections and play an important role in the development of immune tolerance. pDCs are able to recognize cytosine-phosphate-guanosine (CpG) motifs within microbial DNA, which are unmethylated CG dinucleotides in a certain sequence context and trigger the secretion of interferon (IFN)-α and other proinflammatory cytokines. Here we used the typical class A CpG oligodeoxynucleotide (ODN) 2216, the B-class ODN 2006, and the newly synthesized CpG ODN TM64 to explore the potency and kinetics of IFN-α stimulation of pDC. TM64 CpG ODN has a hexanucleotide sequence TCGTGT that leads to an increased cellular uptake and features a CpG nucleotide within the sequence that leads to a potent specific B-cell stimulation, thus characteristics similar to a class B CpG. Our data reveals that all CpGs act as both dosage- and time-dependent stimuli of IFN-α secretion. The relationship between concentration of the stimulant and the secreted amount of IFN-α is not linear and results in a plateau formation, with saturation kinetics. Alteration to the backbone can change duration and quantity of overall IFN-α secretion.

Recognition of CpG oligodeoxynucleotides by human Toll-like receptor 9 and subsequent cytokine induction

Toll-like receptor 9 (TLR9) recognizes a synthetic ligand, oligodeoxynucleotide (ODN) containing cytosine-phosphate-guanine (CpG). Activation of TLR9 by CpG ODN induces a signal transduction cascade that plays a pivotal role in first-line immune defense in the human body. The three-dimensional structure of TLR9 has not yet been reported, and the ligand-binding mechanism of TLR9 is still poorly understood; therefore, the mechanism of human TLR9 (hTLR9) ligand binding needs to be elucidated. In this study, we constructed several hTLR9 mutants, including truncated mutants and single mutants in the predicted CpG ODN-binding site. We used these mutants to analyze the role of potential important regions of hTLR9 in receptor signaling induced by phosphorothioate (PTO)-modified CpG ODN and CpG ODNs only consist entirely of a phosphodiester (PD) backbone, CpG ODN2006x3-PD that we developed. We found truncated mutants of hTLR9 lost the signaling activity, indicating that both the C- and N-termini of the extracellular domain (ECD) are necessary for the function of hTLR9. We identified residues, His505, Gln510, His530, and Tyr554, in the C-terminal of hTLR9-ECD that are essential for hTLR9 activation. These residues might form positive charged clusters with which negatively charged CpG ODN could interact. Furthermore, we observed ODN-PD induced interleukin-6 (IL-6) through TLR9 in a CpG-sequence-dependent manner in human peripheral blood mononuclear cells and B cells, whereas ODN-PTO induced IL-6 in a CpG-sequence-independent manner. These finding are relevant for the mechanism of hTLR9 activation by CpG ODNs.

Spontaneous production of immunoglobulin M in human epithelial cancer cells

It is well known that B-1 B cells are the main cell type that is responsible for the production of natural immunoglobulin M (IgM) and can respond to infection by increasing IgM secretion. However, we unexpectedly found that some epithelial cells also can express rearranged IgM transcript that has natural IgM characteristics, such as germline-encoded and restricted rearrangement patterns. Here we studied IgM expression in human non-B cells and found that IgM was frequently expressed by many human epithelial cancer cells as well as non-cancer epithelial cells. Moreover, CD79A and CD79B, two molecules that are physically linked to membranous IgM on the surface of B cells to form the B cell antigen receptor complex, were also expressed on the cell surface of epithelial cancer cells and co-located with IgM. Like the natural IgM, the epithelial cancer cell-derived IgM recognized a series of microbial antigens, such as single-stranded DNA, double-stranded DNA, lipopolysaccharide, and the HEp-2 cell antigen. More important, stimulation of the toll-like receptor 9 (TLR9), which mimics bacterial infection, substantially increased the secretion of IgM in human epithelial cancer cells. These findings indicate that human epithelial cancer cells as well as non-cancer epithelial cells can spontaneously produce IgM with natural antibody activity.

Immunization with a hemagglutinin-derived synthetic peptide formulated with a CpG-DNA-liposome complex induced protection against lethal influenza virus infection in mice

Whole-virus vaccines, including inactivated or live-attenuated influenza vaccines, have been conventionally developed and supported as a prophylaxis. These currently available virus-based influenza vaccines are widely used in the clinic, but the vaccine production takes a long time and a huge number of embryonated chicken eggs. To overcome the imperfection of egg-based influenza vaccines, epitope-based peptide vaccines have been studied as an alternative approach. Here, we formulated an efficacious peptide vaccine without carriers using phosphodiester CpG-DNA and a special liposome complex. Potential epitope peptides predicted from the hemagglutinin (HA) protein of the H5N1 A/Viet Nam/1203/2004 strain (NCBI database, AAW80717) were used to immunize mice along with phosphodiester CpG-DNA co-encapsulated in a phosphatidyl-β-oleoyl-γ-palmitoyl ethanolamine (DOPE):cholesterol hemisuccinate (CHEMS) complex (Lipoplex(O)) without carriers. We identified a B cell epitope peptide (hH5N1 HA233 epitope, 14 amino acids) that can potently induce epitope-specific antibodies. Furthermore, immunization with a complex of the B cell epitope and Lipoplex(O) completely protects mice challenged with a lethal dose of recombinant H5N1 virus. These results suggest that our improved peptide vaccine technology can be promptly applied to vaccine development against pandemic influenza. Furthermore our results suggest that potent epitopes, which cannot be easily found using proteins or a virus as an antigen, can be screened when we use a complex of peptide epitopes and Lipoplex(O).

Involvement of long noncoding RNAs in diseases affecting the central nervous system

DNA sequences associated with protein-coding genes have been the primary focus of most genetic analyses of complex human diseases. Although we are rapidly gaining a comprehensive view of the etiology of certain central nervous system disorders, major gaps in our understanding persist. Recent studies have uncovered that many human genomic sequences are transcribed but not translated, generating an astounding diversity of noncoding RNAs (ncRNAs). This awareness should be taken into account when studying human diseases and may have profound implications on the development of novel biomarkers as well as therapies.

Comparison of safety and immunogenicity of two doses of investigational hepatitis B virus surface antigen co-administered with an immunostimulatory phosphorothioate oligodeoxyribonucleotide and three doses of a licensed hepatitis B vaccine in healthy adults 18-55 years of age

BACKGROUND

The currently licensed aluminum-hydroxide-adjuvanted hepatitis B vaccines require three doses over a 6-month period to achieve high rates of protection in adults. We compared tolerability and immunogenicity of two doses of an investigational hepatitis B vaccine using hepatitis B surface antigen adjuvanted with an immunostimulatory phosphorothioate oligodeoxyribonucleotide (HBV-ISS) to three doses of a licensed alum-adjuvanted vaccine (HBV-Eng).

METHODS

In this randomized, observer-blind study, healthy adults received two doses of HBV-ISS at 0 and 4 weeks or three doses of HBV-Eng at 0, 4, and 24 weeks. The primary immunogenicity endpoint was the seroprotection rate (antibody ≥ 10 mIU/mL) 8 weeks after the second dose of HBV-ISS compared to 4 weeks after the third dose of HBV-Eng.

RESULTS

A total of 2415 participants were randomized in a ratio of 3:1 to HBV-ISS (n=1809) and HBV-Eng (n=606). The percentage of subjects exhibiting a seroprotective immune response at the primary time point was significantly higher (95.1%) for HBV-ISS than for HBV-Eng (81.1%). Superiority of the seroprotective rates for HBV-ISS was demonstrated at all time points measured. Geometric mean concentrations were also significantly higher in the HBV-ISS group at all time points measured except at week 28 (24 weeks post-second dose of HBV-ISS and 4 weeks post-third dose HBV-ISS) at which time the antibody concentrations were similar. Both vaccines were welltolerated although injection-site reactions were reported at a higher rate in HBV-ISS recipients.

CONCLUSIONS

A short, two-dose regimen of HBV-ISS induced a superior antibody response than a three-dose regimen of a licensed hepatitis B vaccine and was well tolerated.

Novel regulatory mechanism and functional implication of plasminogen activator inhibitor-1 (PAI-1) expression in CpG-ODN-stimulated macrophages

Macrophages are activated by recognizing bacterial DNA and CpG-oligodeoxynucleotides (CpG-ODNs) through Toll-like receptor-9 (TLR-9). Plasminogen activator inhibitor-1 (PAI-1) has been shown to be an important factor in inflammation-induced macrophage migration which is essential for defense functions. The aim of this study was to demonstrate the molecular mechanism associated with the regulation of PAI-1 expression and its biological significance in CpG-ODN-stimulated mouse macrophages. Our results clearly show that PAI-1 expression in macrophages was highly up-regulated by CpG-ODN-stimulation in vitro and in vivo. The TLR-9-mediated stimulation of PAI-1 expression was independent of the NF-κB pathway and involved the synergistic activation of Sp1 and Elk-1 by the MEK1/2-ERK and JNK signaling pathways. The elevated PAI-1 expression resulted in significantly enhanced transmigration of RAW264.7 cells through vitronectin but not through fibronectin. We suggest that CpG-ODN plays a role in regulating macrophage migration by stimulating the expression of PAI-1, and the migration is modulated depending on the microenvironmental extracellular matrix components.

The role of toll-like receptors in the pathogenesis of Streptococcus suis

Streptococcus suis is an important agent of swine and human meningitis. Sequence type (ST) 7 emerged in China and was responsible for the human epidemic caused by S. suis in 2005. The virulence of S. suis ST7 is greater than the wild type pathogenic S. suis, ST1; however, the mechanisms for this increased pathogenicity are unknown. The aim of this study was to determine the role of different toll-like receptors (TLRs) involved in regulating the host response to the S. suis infection and to speculate on differing mechanisms used by ST7 strains to induce disease. Here we compared two ST7 strains isolated in the 2005 Sichuan outbreak to two ST1 strains. Our data show TLR2, 6 and 9 are involved in the recognition of heat-killed S. suis independent of the ST type. We found the TLR-dependent cytokine production differed between the two types of strains using whole cell lysate proteins. TLR6 played a greater role in cytokine production induced by the whole cell lysate proteins from the ST7 strain than in that induced by the ST1 strain lysates. The data suggest that mechanisms of inflammation induced by S. suis strains differ where this will be useful in designing efficient strategies in combating streptococcal toxic shock-like syndrome caused by the S. suis ST7 strains.

Production of antibodies with peptide-CpG-DNA-liposome complex without carriers

Background

The screening of peptide-based epitopes has been studied extensively for the purpose of developing therapeutic antibodies and prophylactic vaccines that can be potentially useful for treating cancer and infectious diseases such as influenza virus, malaria, hepatitis B, and HIV. To improve the efficacy of antibody production by epitope-based immunization, researchers evaluated liposomes as a means of delivering vaccines; they also formulated adjuvants such as flagella and CpG-DNA to enhance the magnitude of immune responses. Here, we provide a potent method for peptide-based epitope screening and antibody production without conventional carriers.

Results

We present that a particular form of natural phosphodiester bond CpG-DNA encapsulated in a specific liposome complex (Lipoplex(O)) induces potent immunomodulatory activity in humans as well as in mice. Additionally, Lipoplex(O) enhances the production of IgG2a specific to antigenic protein in mice. Most importantly, immunization of mice with several peptides co-encapsulated with Lipoplex(O) without carriers significantly induces each peptide-specific IgG2a production in a TLR9-dependent manner. A peptide-specific monoclonal antibody produced against hepatocellular carcinoma-associated antigen has functional effects on the cancer cells.

Conclusions

Our overall results show that Lipoplex(O) is a potent adjuvant and that complexes of peptide and Lipoplex(O) are extremely useful for B cell epitope screening and antibody production without carriers. Therefore, our strategy may be promptly used for the development of therapeutic antibodies by rapid screening of potent B cell epitopes.

Novel immunostimulatory phosphodiester oligodeoxynucleotides with CpT sequences instead of CpG motifs

The innate immune system recognizes bacterial DNA as a nonself to induce rapid immune activation. TLR9 recognizes synthetic oligodeoxynucleotides (ODNs) and bacterial DNA containing unmethylated CpG dinucleotides in the context of specific base sequences (CpG-DNA). Here, we demonstrate that phosphorothioate backbone CT-ODN (PS-CT-ODN), a derivative of phosphorothioate backbone CpG-DNA (PS-ODN) with CT sequences substituted for the CG sequences, stimulates IL-8 promoter activation and gene expression. Furthermore, we identified an immunostimulatory phosphodiester bond CT-ODN (PO-CT-ODN) from Staphylococcus aureus chromosomal DNA and found that the PO-CT-ODN induces cytokine production in a TLR9-dependent manner when encapsulated with a proper liposome. Our experimental analyses also demonstrate that the immunostimulatory PO-CT-ODN can act as an adjuvant for the induction of Ag-driven IgG production. Further investigation of the functional role of PO-CT-ODN may support the future application of PO-CT-ODN in immunotherapeutics.

Evaluation of osteoclastogenesis via NFκB decoy/mannosylated cationic liposome-mediated inhibition of pro-inflammatory cytokine production from primary cultured macrophages

PURPOSE

To explore the effect of NFκB activation in macrophages on osteoclastogenesis of bone marrow cells for potential application as a new type of therapy for preventing bone loss.

METHODS

Primary cultured macrophages and bone marrow cells were prepared from mice. As macrophage-targeted carriers, Mannosylated cationic liposomes (Man-liposomes) were prepared and were allowed to form complexes with NFκB decoy (a double-stranded oligonucleotide). Cellular uptake, inhibition of NFκB activation, and cytokine production were evaluated using macrophages. Osteoclastogenesis was investigated using bone marrow cells, which were cultured in the conditioned medium prepared from macrophages with or without Man-liposome/NFκB decoy complexes treatment.

RESULTS

Cellular accumulation of NFκB decoy was enhanced by Man-liposome. NFκB activation in macrophages and TNF-α production were suppressed in macrophages by Man-liposome/NFκB decoy complexes but not by the naked NFκB decoy, Gal-liposome/NFκB decoy complexes, or Man-liposome/random decoy complexes. Osteoclastogenesis of bone marrow cells was induced in the conditioned medium prepared from activated macrophages but not by activated macrophages treated with Man-liposome/NFκB decoy complexes.

CONCLUSION

Osteoclastogenesis induced by activated macrophages could be suppressed by the treatment macrophages with Man-liposome/NFκB decoy complexes. Macrophage-targeted delivery of NFκB decoys using Man-liposomes may be promising in its use for the remediation of bone loss.

Comparison of a bacteriophage-delivered DNA vaccine and a commercially available recombinant protein vaccine against hepatitis B

A bacteriophage lambda DNA vaccine expressing the small surface antigen (HBsAg) of hepatitis B was compared with Engerix B, a commercially available vaccine based on the homologous recombinant protein (r-HBsAg). Rabbits (five per group) were vaccinated intramuscularly at weeks 0, 5 and 10. Antibody responses against r-HBsAg were measured by indirect enzyme-linked immunosorbent assay, by limiting dilutions and by subtyping. Specific lymphocyte proliferation in vitro was also measured. After one vaccination, three of the five phage-vaccinated rabbits showed a strong antibody response, whereas no r-HBsAg-vaccinated animals responded. Following two vaccinations, all phage-vaccinated animals responded and antibody levels remained high throughout the experiment (220 days total). By 2 weeks after the second vaccination, antibody responses were significantly higher (P<0.05) in the phage-vaccinated group in all tests. After three vaccinations, one out of five r-HBsAg-vaccinated rabbit still failed to respond. The recognized correlate of protection against hepatitis B infection is an antibody response against the HBsAg antigen. When combined with the fact that phage vaccines are potentially cheap to produce and stable at a range of temperatures, the results presented here suggest that further studies into the use of phage vaccination against hepatitis B are warranted.

Unmethylated CpG oligodeoxynucleotides activate head kidney leukocytes of Atlantic cod, Gadus morhua

Bacterial DNA and synthetic oligodeoxynucleotides (ODNs) that contain unmethylated CpG motifs are strong inducers of immune response in most mammalian organisms. The use of these synthetic CpG motifs in fish, particularly in salmonids and carp, resulted in the modulation of their immune system. However, much less is known in other species of fish such as gadoids including Atlantic cod, Gadus morhua. Using head kidney (HK) leukocytes of cod in an in vitro study, we determined the effects of some established CpG-ODNs on the cellular responses of the fish immunocytes. Incubation of the HK leukocytes with 2 μM concentration of the CpG-ODNs resulted in enhanced respiratory burst. There were differential effects on the activities of acid phosphatase and cellular myeloperoxidase. Only CpG-ODN 1826 triggered a significant increase in the level of both enzymes. On the other hand, the supernatants derived from the HK leukocytes after incubation with different CpG-ODNs did not possess bactericidal activity against Vibrio anguillarum and Aeromonas salmonicida. This study has shown that CpG-ODNs at low concentrations are able to stimulate respiratory burst in cod but have minimal effects on cellular enzymatic activities and antibacterial action.

High expression of the immature laminin receptor protein correlates with mutated IGVH status and predicts a favorable prognosis in chronic lymphocytic leukemia

The immature laminin receptor (iLR) is a tumor-associated antigen. We analyzed the expression of iLR on malignant B cells of 134 unselected patient samples with CLL and hypothesized that iLR expression would have prognostic significance due to a differential expression pattern. High ILR expression (cut-off value 30%) was correlated with mutated IGVH status (p<0.0001). Patients with high iLR-expression had a significantly longer time to progression (p=0.039). Combination of CD38, ZAP-70, and iLR by flow cytometry can be used to construct a diagnostic score identifying patients with a median progression free survival of 80 months, if no adverse marker is present.

B cells do not take up bacterial DNA: an essential role for antigen in exposure of DNA to toll-like receptor-9

Murine dendritic cells (DC) and macrophages respond to bacterial CpG DNA through toll-like receptor 9 (TLR9). Although it is frequently assumed that bacterial DNA is a direct stimulus for B cells, published work does not reliably show responses of purified B cells. Here we show that purified splenic B cells did not respond to Escherichia coli DNA with induction of CD86, despite readily responding to single-stranded (ss) phosphodiester CpG oligodeoxynucleotides (ODN). This was due to a combination of weak responses to both long and double-stranded (ds) DNA. B-cell DNA uptake was greatly reduced with increasing DNA length. This contrasts with macrophages where DNA uptake and subsequent responses were enhanced with increasing DNA length. However, when DNA was physically linked to hen egg lysozyme (HEL), HEL-specific B cells showed efficient uptake of DNA, and limited proliferation in response to the HEL-DNA complex. We propose that, in the absence of other signals, B cells have poor uptake and responses to long dsDNA to prevent polyclonal activation. Conversely, when DNA is physically linked to a B-cell receptor (BCR) ligand, its uptake is increased, allowing TLR9-dependent B-cell activation in an antigen-specific manner. We could not generate fragments of E. coli DNA by limited DNaseI digestion that could mimic the stimulatory effect of ss CpG ODN on naïve B cells. We suggest that the frequently studied polyclonal B-cell responses to CpG ODN are relevant to therapeutic applications of phosphorothioate-modified CpG-containing ODN, but not to natural responses to foreign or host dsDNA.

Potential immunological adjuvant of `K'-type CpG-oligodeoxynucleotides enhanced the cell proliferation and IL-6 mRNA transcription in canine B cells

CpG oligodeoxynucleotides (CpG-ODNs) are ligands for toll-like receptor 9 (TLR9), signaling of which plays a role in innate immunity by inducing T helper 1 (TH1)-cell responses and pro-inflammatory cytokine production. The activation of TLR9 signaling is considered to be effective for the therapy of cancer, infectious diseases, and allergies and preclinical studies using CpG-ODNs have been performed in dogs and humans. In order to investigate the precise mechanisms responsible for the effect of CpG-ODNs in dogs, we examined their role in cell proliferation and cytokine gene expression in canine B cells. Canine B cells were collected by a magnetic cell isolation method using anti-CD21 antibody. Flow cytometric analysis for the intracellular CD79α revealed the purity of canine B cells to be as high as 90.2 ± 2.1%. Transcription of TLR2, TLR4, and TLR9 mRNA on canine CD21(+) cells was confirmed by reverse-transcript polymerase chain reaction (RT-PCR). CpG-ODNs induced dose-dependent proliferation of canine CD21(+) cells (P<0.05 compared with control-ODNs) detected by BrdU incorporation. Quantification of IL-6, IL-10, and IL-12p40 mRNA transcription on canine CD21(+) cells revealed that CpG-ODNs enhanced IL-6 mRNA transcription but not IL-10 and IL-12p40 mRNA transcription (P<0.05 compared with control-ODNs). These responses to CpG-ODNs in the canine B cells indicated that CpG-ODNs would be useful as an immunological adjuvant for vaccine in dogs.

A novel method for making human monoclonal antibodies

We have developed a B cell immortalization method for low B cell numbers per well using simultaneous B cell stimulation by CpG2006 and B cell infection by Epstein-Barr virus (EBV), followed by an additional CpG2006 and interleukin-2 (IL-2) stimulus. Using this method, immunoglobulin G (IgG)-producing immortalized B cell lines were generated from peripheral blood IgG⁺CD22⁺ B cells with an efficiency of up to 83%. Antibody can already be obtained from the culture supernatant after 3–4 weeks. Moreover, clonality analysis demonstrated monoclonality in 87% of the resulting immortalized B cell lines. Given the high immortalization efficiency and monoclonality rate, evidence is provided that no further subcloning is necessary. An important application of this B cell immortalization method is the characterization of (autoreactive) antibodies from patients with autoimmune disease. This could eventually lead to the identification of new autoantigens, disease markers or targets for therapy.

Identification and analysis of a CpG motif that protects turbot (Scophthalmus maximus) against bacterial challenge and enhances vaccine-induced specific immunity

Oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs in certain contexts are known to be immunostimulatory in vertebrate systems. CpG ODNs with immune effects have been identified for many fish species but, to our knowledge, not for turbot. In this study, a turbot-effective CpG ODN, ODN 205, was identified and a plasmid, pCN5, was constructed which contains the CpG motif of ODN 205. When administered into turbot via intraperitoneal (i.p.) injection, both ODN 205 and pCN5 could (i) inhibit bacterial dissemination in blood in dose and time dependent manners, and (ii) protect against lethal bacterial challenge. Immunological analyses showed that in vitro treatment with ODN 205 stimulated peripheral blood leukocyte proliferation, while i.p. injection with ODN 205 enhanced the respiratory burst activity, chemiluminescence response, and acid phosphatase activity of turbot head kidney macrophages. pCN5 treatment-induced immune responses similar to those induced by ODN 205 treatment except that pCN5 could also enhance serum bactericidal activity in a calcium-independent manner. To examine whether ODN 205 and pCN5 had any effect on specific immunity, ODN 205 and pCN5 were co-administered into turbot with a Vibrio harveyi subunit vaccine, DegQ. The results showed that pCN5, but not ODN 205, significantly increased the immunoprotective efficacy of DegQ and enhanced the production of specific serum antibodies in the vaccinated fish. Further analysis indicated that vaccination with DegQ in the presence of pCN5 upregulated the expression of the genes encoding MHC class IIalpha, IgM, Mx, and IL-8 receptor. Taken together, these results demonstrate that ODN 205 and pCN5 can stimulate the immune system of turbot and induce protection against bacterial challenge. In addition, pCN5 also possesses adjuvant property and can potentiate vaccine-induced specific immunity.

Toll-Like Receptor Triggering and T-Cell Costimulation Induce Potent Antitumor Immunity in Mice

PURPOSE: To determine the antitumor activity of a novel combination of two immunomodulatory agents that simultaneously direct multiple components of immunity against cancer. EXPERIMENTAL DESIGN: We combined the Toll-like receptor agonist CpG 1826 with a T-cell costimulatory antibody specific for CD137 in an optimal treatment route and dosing schedule against established tumors in two mouse models. Mechanistic insight was gained using gene-deficient mice and cell-depleting antibodies. RESULTS: The combination was shown to eradicate tumors in a large proportion of mice. Crucial roles for CD8(+) T cells, natural killer cells, and IFNs were shown. CpG and anti-CD137 injection led to activation of dendritic cells and optimal expansion of activated T cells in the blood. Macrophages were not necessary for therapeutic effect, and indeed depletion of macrophages in vivo enhanced therapy leading to tumor rejection in 100% of mice, which has not been previously reported in the immunotherapeutic setting. Long-term surviving mice were resistant to tumor rechallenge, demonstrating immunologic memory. In addition, we show, for the first time, that mice lacking B cells have a total loss of a recall response against tumor, suggesting a role for B cells in the induction of antitumor immunologic memory. CONCLUSION: This study provides support for the use of a novel combination of immunomodulatory agents stimulating multiple facets of immunity for the effective immunotherapy of cancer. (Clin Cancer Res 2009;15(24):7624-33).