Immunostimulatory DNA inhibits IL-4-dependent IgE synthesis by human B cells

Induction of Interleukin-10 Producing Dendritic Cells As a Tool to Suppress Allergen-Specific T Helper 2 Responses

Dendritic cells (DCs) are gatekeepers of the immune system that control induction and polarization of primary, antigen-specific immune responses. Depending on their maturation/activation status, the molecules expressed on their surface, and the cytokines produced DCs have been shown to either elicit immune responses through activation of effector T cells or induce tolerance through induction of either T cell anergy, regulatory T cells, or production of regulatory cytokines. Among the cytokines produced by tolerogenic DCs, interleukin 10 (IL-10) is a key regulatory cytokine limiting und ultimately terminating excessive T-cell responses to microbial pathogens to prevent chronic inflammation and tissue damage. Because of their important role in preventing autoimmune diseases, transplant rejection, allergic reactions, or in controlling chronic inflammation DCs have become an interesting tool to modulate antigen-specific immune responses. For the treatment of allergic inflammation, the aim is to downregulate allergen-specific T helper 2 (Th2) responses and the associated clinical symptoms [allergen-driven Th2 activation, Th2-driven immunoglobulin E (IgE) production, IgE-mediated mast cell and basophil activation, allergic inflammation]. Here, combining the presentation of allergens by DCs with a pro-tolerogenic, IL-10-producing phenotype is of special interest to modulate allergen-specific immune responses in the treatment of allergic diseases. This review discusses the reported strategies to induce DC-derived IL-10 secretion for the suppression of allergen-specific Th2-responses with a focus on IL-10 treatment, IL-10 transduction, and the usage of both whole bacteria and bacteria-derived components. Interestingly, while IL-10-producing DCs induced either by IL-10 treatment or IL-10 transduction are arrested in an immature/semi-mature state, treatment of DCs with live or killed bacteria as well as isolated bacterial components results in the induction of both anti-inflammatory IL-10 and pro-inflammatory, Th1-promoting IL-12 secretion often paralleled by an enhanced expression of co-stimulatory molecules on the stimulated DCs. By the secretion of DC-derived exosomes or CC-chemokine ligand 18, as well as the expression of inhibitory molecules like cytotoxic T lymphocyte-associated antigen 4, TNF receptor superfamily member 4, Ig-like transcript-22/cluster of differentiation 85, or programmed death-1, IL-10-producing DCs have been repeatedly shown to suppress antigen-specific Th2-responses. Therefore, DC-based vaccination approaches hold great potential to improve the treatment of allergic diseases.

Immune modulation of T regulatory cells and IgE responses in horses vaccinated with West Nile virus vaccine combined with a CpG ODN

Hypersensitivity reactions, such as hives or fatal anaphylactic shock, in response to vaccination constitute a health hazard for horses that develop allergies to vaccine components. In such horses vaccination with viral vaccines stimulates an IgE response to non-target antigens. Viral vaccines share contaminating non-target proteins, such as bovine serum albumin (BSA); these antigens can stimulate IgE production with each exposure. We hypothesized that the addition of a CpG oligodeoxynucleotide (ODN) administered in conjunction with a West Nile virus vaccine would decrease the IgE response; through up-regulation of T regulatory cells and T helper 1 cells thus decreasing the potential to induce a type 1 hypersensitivity response. Thirty adult horses were injected with either CpG ODN or control GpC ODN with a killed WNV vaccine. T regulatory cell numbers and BSA specific IgE concentrations were determined pre and post vaccination. Multicolor flow cytometry was used to evaluate expression of CD4, CD25, and intracellular Foxp3 on PBMCs. Serum concentrations of BSA specific IgE were determined by ELISA. Cell culture supernatants from BSA re-stimulated lymphocytes were evaluated for concentrations of IL-2, IL-4, IL-10, and IFN-γ. The inclusion of the CpG ODN significantly increased the differentiation of T regulatory cells in response to antigen in vitro and in vivo. A significant inverse correlation was found between T regulatory cell numbers and serum BSA specific IgE concentrations. These results suggest that we can provide a safer alternate vaccination strategy, particularly for horses that have demonstrated a pro-allergic phenotype.

Therapeutic applications of nucleic acids and their analogues in Toll-like receptor signaling

Toll-like receptors (TLRs) belong to a family of innate immune receptors that detect and clear invading microbial pathogens. Specifically intracellular TLRs such as TLR3, TLR7, TLR8 and TLR9 recognize nucleic acids such as double-stranded RNA, single-stranded RNA and CpG DNA respectively derived from microbial components. Upon infection, nucleic acid sensing TLRs signal within endosomal compartment triggering the induction of essential proinflammatory cytokines and type I interferons to initiate innate immune responses thereby leading to a critical role in the development of adaptive immune responses. Thus, stimulation of TLRs by nucleic acids is a promising area of research for the development of novel therapeutic strategies against pathogenic infection, allergies, malignant neoplasms and autoimmunity. This review summarizes the therapeutic applications of nucleic acids or nucleic acid analogues through the modulation of TLR signaling pathways.

IgG4-related sclerosing disease, an emerging entity: a review of a multi-system disease

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a recently defined emerging entity characterized by a diffuse or mass forming inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosclerosis and obliterative phlebitis. IgG4-RSD usually affects middle aged and elderly patients, with a male predominance. It is associated with an elevated serum titer of IgG4, which acts as a marker for this recently characterized entity. The prototype is IgG4-related sclerosing pancreatitis or autoimmune pancreatitis (AIP). Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, however practically any organ can be involved, including upper aerodigestive tract, lung, aorta, mediastinum, retroperitoneum, soft tissue, skin, central nervous system, breast, kidney, and prostate. Fever or constitutional symptoms usually do not comprise part of the clinical picture. Laboratory findings detected include raised serum globulin, IgG and IgG4. An association with autoantibody detection (such as antinuclear antibodies and rheumatoid factor) is seen in some cases. Steroid therapy comprises the mainstay of treatment. Disease progression with involvement of multiple organ-sites may be encountered in a subset of cases and may follow a relapsing-remitting course. The principal histopathologic findings in several extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, along with atrophy and destruction of tissues. Immunohistochemical staining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). IgG4-RSD may potentially be rarely associated with the development of lymphoma and carcinoma. However, the nature and pathogenesis of IgG4-RSD are yet to be fully elucidated and provide immense scope for further studies.

Allergic rhinitis: an update on disease, present treatments and future prospects

Allergic rhinitis (AR) is an inflammation of nasal mucosa mediated by IgE-associated processes occurring independently, or concurrently with asthma. AR is characterized by sensitization-formation and expression of antigen specific IgE, followed by inflammation in two phases. The early phase response involves cross linking of IgE molecules leading to degranulation of mast cells and release of preformed mediators such as histamine and tryptase, or newly synthesized mediators such as prostaglandins and leukotrienes. The late phase response is predominated by the presence of eosinophils, lymphocytes, cytokines, and adhesion molecules. Newer insights reveal that the whole phenomenon of immunological inflammation is intricately knit with neural pathways, which strongly influence the process. Furthermore, AR can impact psychological health and vice versa. Classical pharmacotherapy of AR includes use of oral or topical antihistamines, oral antileukotrienes, topical corticosteroids, mast cell stabilizers, decongestants, and an anticholinergic agent. Among immunomodulatory treatments, immunotherapy is gaining widespread use, while antibody treatment is restricted mainly to resistant cases. Several small molecules with improved safety profile, or targeting novel mechanisms are in the clinical research. Newer antihistamines and corticosteroids with improved safety profile and antagonists of the prostaglandin D(2) (CRTH2) receptors are likely to be available for clinical use in the near future. Lack of properly validated animal models and complexities associated with clinical evaluation are some of the challenges facing the researchers in AR. Comprehensive understanding of immunological and neurological processes in AR would facilitate the future quest for more effective and safer management of this disease.

What is IgG4? A review of the biology of a unique immunoglobulin subtype

PURPOSE OF REVIEW

Recent descriptions of the group of clinical disorders collectively defined as IgG4-related systemic disease (IgG4-RSD) have prompted this review of the unique biology of the IgG4 antibody. This article will discuss IgG4 structure and function, the unique phenomenon of half-antibody exchange, and the implications of IgG4 biology for its proposed role in immunologic diseases.

RECENT FINDINGS

IgG4 antibodies have unique structural and functional properties and undergo 'half-antibody exchange' in vivo, resulting in recombined antibodies composed of two different binding specificities. The production of IgG4 antibodies appears to be driven in part by T helper 2 (Th2) cytokines that mediate allergic responses and IgE production. Although serum IgG4 levels in healthy individuals vary significantly, data from multiple sclerosis (MS) patients suggest tight regulation of individual IgG4 levels over time. IgG4-RSD represents a diverse group of clinical disorders unified by elevated IgG4 levels and specific histopathologic findings. A key unanswered question is whether IgG4, a relatively weak activator of effector cells, is pathogenic in these disorders.

SUMMARY

IgG4 is a unique antibody biologically and structurally. Increased understanding of its precise role in the clinical syndromes that comprise IgG4-RSD may ultimately elucidate the underlying pathogenesis.

Therapeutic manipulation of immune tolerance in allergic disease

Immune tolerance - the adaptation of the immune system to external antigens or allergens - might be therapeutically manipulated to restore normal immunity in conditions such as allergy, asthma and autoimmune diseases. The field of allergen-specific immunotherapy is experiencing exciting and novel developments for the treatment of allergic and autoimmune diseases, and recent insights into the reciprocal regulation and counter-balance between different T-cell subsets is foreseen to facilitate new strategies for immunointervention. This Review highlights current knowledge of immunomodulatory therapies for the manipulation of immune tolerance and highlights recent approaches to improve allergen-specific immunotherapy for the treatment of allergic diseases.

Immune Mechanisms and Therapeutic Potential of CpG Oligodeoxynucleotides

Unmethylated CpG motifs in bacterial DNA and synthetic oligodeoxynucleotides activate immune cells that express Toll-like Receptor 9. Activation through this receptor triggers cellular signaling that leads to production of a proinflammatory and a Th1-type, antigen-specific immune response. The immunostimulatory effects of CpG oligodeoxynucleotides confer protection against infectious disease, allergy and cancer in animal models, and clinical trials have been initiated. However, CpG oligodeoxynucleotides may exacerbate disease in some situations. We will review current concepts in the mechanisms of activating Toll-like Receptor 9 with CpG oligodeoxynucleotides and highlight opportunities for using large animal models to better determine the mechanisms of action.

Allergen extract-induced interleukin-10 in human memory B cells inhibits immunoglobulin E production

BACKGROUND

Elevated specific IgE antibody levels are common in atopic individuals, caused by T-helper type 2-dominated B cell activation. The induction of antigen-specific IL-10 secreting T cells is discussed as an important mechanism during specific immunotherapy. By contrast the presence and function of B cell-derived IL-10 is not well defined yet.

OBJECTIVE

We investigated whether type-I allergen extracts induce IL-10 expression in human B cells and analysed its functional role on IgE production.

METHODS

Human peripheral B cells were stimulated with grass pollen, house dust mite (HDM) (Dermatophagoides pteronyssimus; Der p) and dog allergen extract. Expression of IL-10 by activated human B cells was determined by flow cytometric analysis and ELISA. Functional analysis considering immunoglobulin production was assayed by ELISA.

RESULTS

The allergen extracts studied induced IL-10 expression in B cells. However, the ability to induce IL-10 differed between the allergen extracts. The most potent allergen extract was dog (169+/-28 pg/mL), followed by grass pollen (141+/-10 pg/mL) and HDM allergen (125+/-11 pg/mL). Upon allergen extract stimulation only CD27 expressing memory B cells produced IL-10 and co-expressed the very early activation antigen CD69. The addition of allergen extracts to B cells activated by anti-CD40 and IL-4 selectively inhibited IgE which was dependent on allergen extract-induced IL-10. By contrast the other immunoglobulin subclasses like IgA, IgG or IgM were not altered upon allergen extract challenge.

CONCLUSION

Our data indicate that allergen-activated memory B cells can modulate IgE production through secretion of IL-10.

Immunostimulatory sequence CpG elicits Th1-type immune responses in inflammatory skin lesions in an atopic dermatitis murine model

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease, for which no fundamental therapy exists. Immunostimulatory sequence CpG (ISS CpG) has potential in reducing susceptibility to allergic diseases and reversing established allergic reactions.

OBJECTIVE

To investigate the effects of ISS CpG in the prevention and treatment of AD in an AD murine model.

METHODS

BALB/c mice were epicutaneously exposed to ovalbumin (OVA) for 3 or 4 weeks with a 2-week resting period between each exposure week. ISS i.d. injection was given either on the 1st day of each exposure week (in the prevention experiment) or 3 days before and on the 1st, 4th and 7th day of the last exposure week (in the treatment experiment). Skin biopsy and blood were obtained at the end of the experiments.

RESULTS

ISS CpG treatment increased drastically mRNA expression of proinflammatory and Th1-type cytokines and chemokines in OVA-treated skin both in the prevention and treatment experiments. The suppressing effect of ISS CpG on Th2-type cytokines and chemokines was weak and limited to IL-13 and CCL24 in the treatment experiment. No significant reduction in OVA-elicited infiltration of eosinophils and T cells in the skin was seen after ISS administration but infiltration of plasmacytoid dendritic cells was absent in ISS CpG-treated skin. In contrast, ISS injection elicited dramatic infiltration of F4/80+ and CCR5+ cells into the dermis and subcutaneous tissue.

CONCLUSION

Due to unwanted side effects and minor beneficial effects in our model, administration of ISS CpG may not be suitable for the treatment of AD in humans.

Translational mini-review series on Toll-like receptors: Toll-like receptor ligands as novel pharmaceuticals for allergic disorders

Characterization of the Toll-like receptor (TLR) family and associated signalling pathways provides a key molecular basis for our understanding of the relationship between exposure to microbial products and susceptibility to immune-mediated disorders. Indeed, ligation of TLR controls innate and adaptive immune responses by inducing synthesis of pro- as well as anti-inflammatory cytokines and activation of effector as well as regulatory lymphocytes. TLRs are therefore considered as major targets for the development of vaccine adjuvants, but also of new immunotherapies. Herein, we review the potential of TLR ligands as a novel class of pharmaceuticals for the prevention or treatment of allergic disorders.

Update on toll-like receptor ligands and allergy: implications for immunotherapy

Innate responses to microbes are mediated in large part via toll-like receptors (TLRs) that recognize a diverse family of ligands produced by viruses, bacteria, and fungi. Great effort has been directed toward translating this knowledge into the development of therapies for the prevention and treatment of diseases, including those fueled by allergic (Th2-biased) hypersensitivities. In this review, we consider the ways in which ligands for different TLRs influence the allergic phenotype. In addition, an update on safety and efficacy data from clinical trials of allergic patients treated with TLR9 ligand-based interventions is provided. Finally, recent experimental results that help elucidate how ambient TLR ligand exposures influence allergic risk and their relevance to the development of TLR ligand-based therapeutics are discussed. Investigations presented within this opinion paper suggest that several TLR ligands could have clinical utility in the treatment of allergic diseases, whereas other TLR ligands appear less attractive, as they facilitate development of Th2-biased hypersensitivities in murine studies.

TLR9-based immunotherapy for allergic disease

A significant amount of data generated over the last few years supports the contention that Toll-like receptor (TLR) 9-based immunotherapy is effective in the prevention and treatment of animal models of allergic disorders. We will review here our experience with two distinct therapeutic strategies: TLR9-based immunomodulation and TLR9-based vaccination. Immunomodulation of allergic inflammation by TLR9 ligand (TLR9-L) is transient. It prevents both the early and late phases of the allergic reaction in experimental models of allergic asthma, rhinitis, and conjunctivitis. It also reverses ongoing allergic inflammation. Indoleamine 2.3-dioxygenase, the rate-limiting enzyme of tryptophan, is induced by TLR9-L and mediates, in part, these anti-inflammatory effects. TLR9-based immunomodulation is independent of allergens and, therefore, has a potential therapeutic advantage in a broad spectrum of allergic patients. On the other hand, TLR9-based vaccination therapy is an allergen-specific mode of immunotherapy, which provides long-term inhibition of allergen-specific hypersensitivities. Current clinical trials with TLR9-based immunotherapy demonstrate high immunogenic and therapeutic efficacy, as well as improved safety when compared with conventional allergen desensitization. Thus, if proven efficient, therapeutic strategies with TLR9-L may revolutionize the current treatment of allergic diseases.

Immunostimulatory Sequences Regulate Interferon-inducible Genes but not Allergic Airway Responses

RATIONALE

1018 ISS is a synthetic oligonucleotide containing immunostimulatory CpG motifs. In animal studies, 1018 ISS effectively inhibited Th2-mediated lung inflammation, including eosinophil infiltration, and airway hyperresponsiveness.

OBJECTIVES

To evaluate whether 1018 ISS has activity in subjects with allergic asthma.

METHODS

Forty subjects (n = 21, 1018 ISS; n = 19, placebo) were enrolled in a randomized, double-blind, placebo-controlled, parallel-group study to examine safety, pharmacologic activity, and efficacy of 1018 ISS on allergen-induced airway responses. Subjects received 36 mg of 1018 ISS or placebo by nebulization weekly for 4 wk.

MEASUREMENTS

Allergen inhalation challenge was performed 24 h after the 2nd and 4th doses to measure the early and late fall in FEV(1). Sputum cells and peripheral blood mononuclear cells were collected before and after dosing, and gene expression was measured by quantitative polymerase chain reaction.

MAIN RESULTS

Treatment with 1018 ISS significantly increased expression of interferon (IFN)-gamma and IFN-inducible genes, such as IFN-gamma-inducible 10 kD protein (IP10), monokine induced by IFN-gamma (MIG), IFN-stimulated gene (ISG)-54, monocyte chemotactic protein (MCP)-1, and MCP-2 from cells collected postdose (p < 0.05). There was no attenuation of the early or late decrease in FEV(1) after 1018 ISS compared with placebo, nor a reduction in allergen-induced sputum eosinophils or Th2-related gene expression measured in sputum cells.

CONCLUSIONS

This study demonstrated that 1018 ISS is safe and pharmacologically active in the respiratory tract of asthmatics but, at this dose regimen, did not inhibit a fall in FEV(1) or other key features of the response to inhaled allergen challenge. This suggests that induction of IFN and IFN-inducible genes alone is not sufficient to inhibit allergen-induced responses in asthmatic subjects.

Toll-like receptor ligands and atopy: a coin with at least two sides

Allergic disease prevalence rates have increased dramatically in affluent countries over the last half century. One proposed explanation is that decreased exposures to microbes caused by modern public health practices has led to deficiencies in an important source of immune education and a consequent increase in the risk of pathogenic immune responses to environmental antigens. Recently, it has become clear that innate responses to microbes are mediated in large part by Toll-like receptors (TLRs), which recognize a diverse family of ligands produced by viruses, bacteria, and fungi. In this perspectives article we will review experimental evidence suggesting that TLRs also play a dominant role in innate responses to noninfectious immunostimulatory materials present in environments of daily living. We will further discuss how ligands for different TLRs can polarize the T(H) bias of adaptive responses in opposing directions. Finally, we will consider how TLRs might contribute to the genesis of atopy and the clinical potential of pharmacologic interventions that target TLRs for the prevention and treatment of allergic diseases.

Common human Toll-like receptor 9 polymorphisms and haplotypes: association with atopy and functional relevance

BACKGROUND

Toll-like receptor 9 (TLR9) is a pattern-recognition receptor that detects unmethylated CpG motifs prevalent in bacterial and viral DNA. TLR9 stimulation is a key event after bacterial infection, triggering innate immunity and T-helper type 1 skewed adaptive immunity. Synthetic CpG-oligodeoxynucleotides (CpG-ODNs) represent a promising and novel class of immune adjuvants for allergy treatment, vaccination, and cancer therapy. However, common functional TLR9 gene variants could interfere with the clinical utilization of CpG-ODN in immunotherapy. Recently, a possible association of TLR9 polymorphism C-1237T with asthma has been reported.

OBJECTIVE

The aim of the present study was to investigate whether TLR9 polymorphisms or haplotypes have functional relevance and are associated with atopy.

METHODS

We genotyped five common TLR9 single-nucleotide polymorphisms (SNPs) in promoter, exon, and intron regions of the gene in 527 healthy blood donors, and estimated four common haplotypes. The total IgE and specific IgE levels against the most common aeroallergens were measured (n=303). IFN-alpha production by plasmacytoid dendritic cells (pDCs) was analysed after stimulation with TLR9 ligand CpG-ODN (n=220).

RESULTS

No significant influence of common TLR9 polymorphisms and haplotypes on the total and specific IgE levels was found. Functional analysis of CpG-ODN-induced IFN-alpha did not indicate a significant role for common TLR9 gene polymorphisms in TLR9 function.

CONCLUSION

We conclude that common genetic differences in the TLR9 gene exert no major influence on allergy susceptibility, and are unlikely to have on impact on clinical application of CpG-ODNs.

Cytokine and Ig-production by CG-containing sequences with phosphorodiester backbone and dumbbell-shape

BACKGROUND

Immunostimulatory oligodeoxynucleotides (CpG-ODN) usually contain phosphorothioate (PS) backbones for nucleotide protection, which may result in some nonspecific side-effects like prolongation of coagulation time.

OBJECTIVE

The aim of the present study was to investigate the immunomodulatory potential of DNA molecules without PS backbones. Thus, we designed phosphorodiester (PO) molecules with a dumbbell-like covalently-closed structure (dSLIM-30L1).

METHODS

We analyzed their effects on peripheral blood mononuclear cells (PBMC) from spontaneous high and low immunoglobulin (Ig)E producer (allergic and nonallergic donors) in comparison with linear CpG-ODN (lin-30L1) with PS backbones, using enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

We observed a decrease of spontaneous IgE levels in PBMC from high IgE producer of approximately 27% with both dSLIM-30L1 and lin-30L1. In addition, both molecules enhanced the production of IgA, IgM and IgG1/IgG2, but with a slightly different pattern. Both molecules stimulated the secretion of the T(H)1-like cytokines interleukin (IL)-2, interferon-gamma and IL-12p40 and the pro-inflammatory cytokine IL-6. The immunomodulatory potential of dSLIM-30L1 and lin-30L1 was also effective in PBMC from nonallergic donors, as was confirmed for IL-2, IL-12p40, IgG1/IgG2 and IgM.

CONCLUSION

Our data show an inhibition of IgE production but also enhancement of the inflammatory cytokine response in PBMC from allergic and nonallergic donors by covalently-closed PO-based dSLIM-30L1 with a pattern similar to that of linear PS-based lin-30L1, while avoiding PS-modifications and thus PS-mediated side-effects. Whether such molecules are useful for the treatment of allergic diseases will need further clarification by appropriate in vivo studies.

A point of view: HIV-1/AIDS is an allergy but CpG ODN treatments may inhibit virus replication and reactivate the adaptive immunity--hypothesis and implications

Reevaluation of the increase in the levels of IgE and IL-4 in sera of HIV-1 infected and AIDS patients led to the suggestion that AIDS resembles allergy. Studies on the properties of the viral shed gp120 revealed that it resemble environmental allergens in their ability to induce hematopoietic cells to release large amounts of Th2 cytokines, inhibitors of the patients adaptive immune response. Yet, induction of TLR9+ plasmacytoid DCs by CpG ODNs cause the release of type I interferons, inhibitors of HIV-1 replication and IL-4 release from hematopoietic cells. CpG ODN binding to TLR+ B cells inhibits IgE synthesis and reactivates the failing adaptive immunity. The possible use of CpG ODNs as treatment to patients is discussed.

CpG ODNs treatments of HIV-1 infected patients may cause the decline of transmission in high risk populations - a review, hypothesis and implications

The Joint United Nations Program on HIV-1/AIDS (UNAIDS) announced its goal to stop HIV-1 transmission by antiviral (HAART) treatment of patients since at the end of 2003 the number of people living with HIV-1 was 38 million, 25 million in the sub-Saharan region of Africa. The present review deals with a new approach to simultaneously treat HIV-1/AIDS patients in HIV-1 endemic regions with CpG oligodeoxynucleotides (ODNs) and people at high risk of infection with a vaccine containing CpG ODNs combined with synthetic HIV-1 peptides by intranasal and intradermal applications. During HIV-1 infection a gradual increase in the levels of IL-4 and IgE in the patients' serum, was reported. It was suggested that such an increase of the cytokine IL-4 and the IgE immunoglobulin are interconnected and may serve as indicators for the coming stage of AIDS. It was also suggested that the IL-4 and IgE increase in the serum of HIV-1 infected people resemble the increase of IL-4 and IgE levels in allergic patients that were exposed to endogenous or environmental allergens [Becker, Virus Genes 28, 5--18, 2004]. Indeed, it was reported that the HIV-1 virions' shed gp120 molecules, which contain a superantigen (superallergen) domain that enables the viral glycoprotein to bind the V(H)3 domain of IgE molecules that are bound to FcepsilonRI+ hematopoietic cells [basophils, mast cells, dendritic cells (DCs) and plasmacytoid DCs (pDCs)]. Such interaction was reported to induce the hematopoietic cells to release large amounts of Th2 cytokines IL-4, IL-5, IL-10 and IL-13. These findings led to the hypothesis [Op. cit.] that the cure of HIV-1/AIDS patients requires the induction of endogenous synthesis of type I interferons (INF alpha and beta) with a bacterial CpG rich DNA that will induce the patients' pDCs to release large amounts of type I IFNs. Under these conditions HIV-1 replication in polarized to Th2 cells is inhibited. Type I IFNs reactivate the patients' inhibited Th1 cells to synthesize IL-2 and IL-12 cytokines that activate the maturation of CTL precursors. The unmethylated bacterial DNA activates B synthesis to switch to IgG and IgA synthesis. The novel drug CpG ODNs is being tested for the prevention and the treatment of allergic humans and in the experimental system of allergic mice. It was also reported that treatment of mice with CpG ODN prior to or after retrovirus infections protected and cured, respectively, the retrovirus infection. It was also reported that CpG ODNs treatments of mice exposed to allergen protected them against the development of the allergic response. Phase I treatment of healthy people with CpG ODNs provided information on the safety of these compounds. The CpG ODNs A and B bind to Toll like receptors that are present in pDCs and B cells, respectively, CpG ODN - A is the ligand for TLR9+ pDCs and induce the release of large amounts of IFN-alpha, beta. CpG ODN-B is the ligand for TLR9+ in B cells and induce the synthesis of IgG and IgA. CpG ODN-C contains motifs from CpG ODNs A and B and is more active. The present review is based on findings from studies that reported that CpG ODNs treatment of retrovirus infected mice, monkeys and allergic mice prevented the virus and allergens caused diseases, respectively. Based on these studies, a hypothesis is presented that treatment of HIV-1 infected and AIDS patients with CpG ODN-A and B or CpG ODN-C have the potential to inhibit IL-4 synthesis and release from FcrepsilonRI+ hematopoietic cells by inducing TLR9+ pDCs to release large amounts of type I IFNs. TLR9+ B cells are induced by CpG ODN-B to switch from IgE to IgG, IgA synthesis. In addition, type I IFNs (alpha, beta) have the capacity to inhibit HIV-1 replication in polarized Th2 cells. Type I IFNs reactivate the patients' Th1 cells to synthesize IL-2 and IL-12 cytokines, activators of the precursor cytotoxic T cells (CTLs), leading to the reactivation of the inhibited adaptive immune response. Antiviral CTLs have the ability to clear the virus infection. The present novel approach to the treatment and of HIV-1/AIDS patients with CpG ODNs may prevent HIV-1 transmission and the AIDS pandemic if controlled studies on the treatments with CpG ODNs of HIV-1 infected people will be done by international and private agencies and companies to define the effective treatment regime and the efficacy of the treatments to HIV-1 infected people at different times post-infection. It is also hypothesized that in order to stop HIV-1 transmission in HIV-1 endemic regions the people at high risk of HIV-1 infection should be treated at the same time as HIV-1 infected people with a vaccine containing synthetic CpG-ODNs combined with synthetic HIV-1 peptides, compatible with the major HLA haplotypes of the regional population. The vaccine may be self-applied by people at high risk of infection by the intra-nasal route and by intra-dermal application as a "peplotion vaccine". The stimulation of the antiviral CTL response by HIV-1 infected people and the active antiviral immune response in the vaccinated population may lead to a decline in HIV-1 transmission and may be a model for control of the HIV-1/AIDS pandemic.

IL-21 effects on human IgE production in response to IL-4 or IL-13

In human atopic disease, IgE sensitizes the allergic response, while IgG4 is protective. Because IL-4 and IL-13 trigger switch recombination to both IgE and IgG4, additional agents must regulate the balance between these isotypes to influence susceptibility or tolerance to atopy. In this report, we define in vitro conditions leading to activation or inhibition of human IgE and IgG4 production by IL-21. IL-21 reduced IL-4-driven IgE synthesis by mitogen-stimulated human PBMC. IL-21 inhibition of human IgE production was not a direct effect on B cells, was not seen following B cell activation with IL-13, and was overcome by CD40 ligation. Neither IFN-gamma, IL-10, IL-12, CD40L expression, nor apoptosis was responsible for the inhibitory effect. In contrast, IL-21-stimulated secretion of IgG4 from PBMC. Our findings indicate that IL-21 may influence the production of both human IgE and IgG4, and thus contribute to the regulation of atopic reactions.

Immunostimulatory DNA reverses established allergen-induced airway remodeling

To determine whether immunostimulatory sequences of DNA (ISS) can reverse established airway remodeling, mice that had developed airway remodeling following 3 mo of repetitive OVA challenges, were treated with ISS for 1-3 mo. Systemic administration of ISS to mice that had already developed established airway remodeling significantly reduced the degree of airway collagen deposition (assessed by lung collagen content, peribronchial trichrome staining, and immunostaining with anticollagen type III and type V Abs). ISS reduced bronchoalveolar lavage and lung levels of TGF-beta1 and reduced the number of TGF-beta1-positive eosinophils and TGF-beta1-positive mononuclear cells recruited to the airway. In vitro studies demonstrated that ISS inhibited TGF-beta1 expression by macrophages (RAW 264.7 cell line and bone marrow-derived macrophages). In addition, ISS significantly reduces lung levels of expression of the chemokine thymus- and activation-regulated chemokine, as well as the number of peribronchial CD4(+) lymphocytes that express Th2 cytokines that promote peribronchial fibrosis. Overall, these studies demonstrate that ISS can reverse features of airway collagen deposition by reducing levels of lung TGF-beta1, as well as by reducing levels of the chemokine thymus- and activation-regulated chemokine and the numbers of peribronchial CD4(+) lymphocytes that drive the ongoing Th2 immune response.

Use of immunostimulatory liposome-nucleic acid complexes in allergen-specific immunotherapy of dogs with refractory atopic dermatitis - a pilot study

This pilot study evaluated the effects of immunostimulatory liposome-plasmid-DNA complexes combined with specific allergens for immunotherapy of refractory canine atopic dermatitis. Seven dogs with previously diagnosed atopic dermatitis and unsatisfactory response to at least 12 months of conventional allergen-specific immunotherapy underwent a series of six intradermal injections (weeks 0, 2, 4, 6, 10 and 14), with patient-specific allergen extracts contained in cationic liposome-DNA complexes. Degree of pruritus was assessed on a visual analogue scale. Lesion scores were determined using the Canine Atopic Dermatitis Extent and Severity Index (CADESI) and medication usage was recorded at weeks 0 and 14. Canine cytokine mRNA expression in peripheral blood mononuclear cells collected prior to treatment and at the completion of the study was determined for IFN-gamma, IL-4, TNF and IL-10 genes using quantitative reverse transcription competitive polymerase chain reaction. Repeated intradermal injections of specific allergens incorporated into liposome-nucleic acid complexes were well tolerated in all seven dogs. There was a significant improvement in pruritus scores (P = 0.0277) and concurrent significant decrease in IL-4 production (P = 0.0428) at the completion of the trial compared to pretreatment values. Medication scores, CADESI and production of other cytokines did not change significantly with treatment. These early results suggest that antigen-specific immunotherapy using a novel liposome-nucleic acid complex vaccine may be beneficial for treatment of established atopic dermatitis in dogs using lower antigen doses. Further investigations in larger numbers of dogs with earlier stages of disease are warranted.

Allergen-independent immunostimulatory sequence oligodeoxynucleotide therapy attenuates experimental allergic rhinitis

While effective for the prevention and treatment of allergic rhinitis (AR) symptoms, currently available medications do not reverse allergen specific hypersensitivities. Therefore, pharmacotherapeutics are not curative and their daily use is often required for years. These investigations were conducted to determine whether immunostimulatory sequence oligodeoxynucleotide (ISS-ODN) delivery protects previously sensitized mice from AR hypersensitivity responses and modulates their allergen specific immune profiles. Mice were first sensitized with ovalbumin (OVA) and alum, twenty-four hr before beginning a series of seven daily intranasal (i.n.) allergen challenges, subsets of mice received a single i.n. or intradermal (i.d.) dose of ISS-ODN or control oligodeoxynucleotide (C-ODN), a single intraperitoneal (i.p.) injection of dexamethasone (DXM), or no intervention. Mice receiving i.d. or i.n. ISS-ODN were found to have attenuated immediate and late phase effector cell responses to i.n. OVA challenge. Specifically, ISS-ODN treated mice had less histamine and cysteinyl leukotriene release and eosinophilic inflammation in their nasal passages than mice treated with C-ODN. In addition, splenocytes from ISS-ODN but not C-ODN treated mice displayed attenuated OVA-specific interleukin (IL)-4, IL-5, and IL-13 but increased interferon-gamma responses. Finally, ISS-ODN was generally a more effective treatment than DXM, both in blunting AR hypersensitivity responses and in shifting T helper 2 Th2-biased immune parameters towards Th1 dominance. As ISS-ODN delivery rapidly attenuated effector cell responses in this AR model in an allergen independent manner, the present results suggest that therapy with ISS-ODN alone may be an effective alternative to corticosteroid medications for the clinical management of AR.

A Novel Approach to Specific Allergy Treatment: The Recombinant Fusion Protein of a Bacterial Cell Surface (S-Layer) Protein and the Major Birch Pollen Allergen Bet v 1 (rSbsC-Bet v 1) Combines Reduced Allergenicity with Immunomodulating Capacity

Counterregulating the disease-eliciting Th2-like immune response of allergen-specific Th lymphocytes by fostering an allergen-specific Th1-like response is a promising concept for future immunotherapy of type I allergy. The use of recombinant allergens combined with more functional adjuvants has been proposed. In this respect, we present a novel approach. The gene sequence encoding the major birch pollen allergen, Bet v 1, was fused with the gene encoding the bacterial cell surface (S-layer) protein of Geobacillus stearothermophilus, resulting in the recombinant protein, rSbsC-Bet v 1. rSbsC-Bet v 1 contained all relevant Bet v 1-specific B and T cell epitopes, but was significantly less efficient to release histamine than rBet v 1. In cells of birch pollen-allergic individuals, rSbsC-Bet v 1 induced IFN-gamma along with IL-10, but no Th2-like response, as observed after stimulation with Bet v 1. Intracellular cytokine staining revealed that rSbsC-Bet v 1 promoted IFN-gamma-producing Th cells. Moreover, rSbsC-Bet v 1 induced IFN-gamma synthesis in Bet v 1-specific Th2 cell clones, and importantly, increased IL-10 production in these cells. In conclusion, genetic fusion of an allergen to S-layer proteins combined reduced allergenicity with immunomodulatory capacity. The strategy described in this work may be generally applied to design vaccines for specific immunotherapy of type I allergy with improved efficacy and safety.

D cyclins in lymphocytes

BACKGROUND

D cyclins are essential for the progression of cells through the G1 phase of the cell cycle. There are three distinct D cyclins. Cyclin D1 has been shown to be expressed by many different types of cells but not by lymphocytes. Cyclins D2 and D3 have been found in lymphocytes.

METHODS

We used high-resolution enzymatic amplification staining technology in conjunction with flow cytometry and confocal microscopy and with immunoblotting to reassess the expression of the D cyclins in human lymphocytes.

RESULTS

Using high-resolution technology for flow cytometry, we found all three D cyclins in quiescent human peripheral blood lymphocytes. Cyclin D1 was expressed in quiescent and activated cells at levels commensurate with those of actively proliferating tumor cell lines. Cyclin D1 was functional inasmuch as it was complexed with CDK4. In the quiescent cells, cyclin D1 was expressed in the cytoplasm but, after activation, was found in the nucleus.

CONCLUSIONS

These findings demonstrate that lymphocytes express cyclin D1 and necessitate a reappraisal of the hypothesis that the D cyclins subsume redundant activities with tissue-specific expression.

Enzymatic amplification staining for single cell analysis: applied to in situ hybridization

Single cell analysis by flow cytometry is a powerful modality for analyzing the expression of a set of molecules. Nevertheless, the most significant deficiency of this technology has been the poor sensitivity of flow cytometry compared to other techniques such as immunoblotting. In order to address this deficiency, we have developed an enzymatic amplification system for flow cytometry that enhances the specific signal by 10-100-fold. Using enzymatic amplification staining (EAS), we and others have been able to assess the expression of molecules that could not be detected otherwise. In this review, we show the capability of this new technology to detect specific RNA expression.

Enzymatic amplification staining for cell surface antigens

Many molecules of biological significance function at very low levels and are difficult to detect with the standard staining procedures for flow cytometric analysis. This unit describes a technology for cell staining that enhances the specific fluorescence signal by as much as 100-fold. The system is based on the enzyme-catalyzed deposition of a tagged molecule. Enzymatic amplification staining is qualitatively different from the inclusion of additional layers of binding molecules because background fluorescence levels are not increased along with the specific signal. The technique is compatible with multicolor staining. An alternate protocol explains the performance of multiple amplifications on the same cell population by adding a peroxide incubation.

Immunostimulatory DNA-based therapeutics for experimental and clinical allergy

Although allergen immunotherapy (IT) has been shown to modulate allergic hypersensitivities, its efficacy is limited. Recently, in various models of experimental allergy, a number of reagents which we have termed immunostimulatory DNA-based therapeutics have proven highly effective in both the prevention and reversal of Th2 mediated hypersensitivity states. These include immunization with gene vaccines, allergen mixed with immunostimulatory oligodeoxynucleotide (ISS-ODN), and physical allergen: ISS-conjugates (AIC), and immunomodulation with ISS-ODN alone. Results from our laboratory have shown that immunostimulatory DNA-based therapeutics may be effective for the reversal of allergic hypersensitivity states in humans and several clinical trials have already been initiated. This review will focus on our laboratory's experience with immunostimulatory DNA-based therapeutics in various murine models of allergy and their potential utility in the treatment of allergic patients.

Immunostimulatory sequence oligodeoxynucleotide-based vaccination and immunomodulation: two unique but complementary strategies for the treatment of allergic diseases

Despite a number of effective pharmaceutical options for the prevention and treatment of the pathophysiologic responses that occur in sensitized patients on allergen exposure, the termination of allergic hypersensitivities remains an elusive therapeutic goal. Traditional immunotherapy with allergen extracts is the only currently used intervention that has been shown to induce allergen tolerance, but it has a limited scope of efficacy. However, recent studies suggest that immunostimulatory sequence oligodeoxynucleotide (ISS-ODN) -based interventions might offer an alternative and potentially more effective means for extinguishing T (H)2-biased hypersensitivities. Three basic ISS-ODN -based immunotherapeutic strategies have been studied to date. Immunization with allergen mixed with ISS- ODN, immunization with allergen -ISS- ODN conjugates, and immunomodulation with ISS- ODN alone all have proved efficacy in the attenuation of the allergic phenotype in mice. Preliminary results with allergen -ISS- ODN conjugate vaccines in allergic patients have also been encouraging. This article will provide our perspective on the application of ISS-ODN -based vaccination and immunomodulation to the treatment of atopic diseases and the immunologic basis for their antiallergic activities.

CpG motifs as possible adjuvants for the treatment of allergic diseases

DNA containing unmethylated CpG motifs and synthetic oligodeoxynucleotides derived thereof (CpG ODN) have intensively been investigated for their immunostimulatory properties in the recent past. CpG ODN were shown to induce strong Th1 immune responses in mammals. The downregulation of the antigen-driven Th2 response of type I allergies represents one important therapeutic goal of specific immunotherapy (SIT). Hence, CpG ODN represent promising substances which support the modification of the pathogenic Th2 immune profile toward a Th1 profile when used as adjuvants for SIT. This article discusses how the use of CpG ODN in immunotherapeutics could improve the treatment of type I allergy.

Optimized conjugation ratios lead to allergen immunostimulatory oligodeoxynucleotide conjugates with retained immunogenicity and minimal anaphylactogenicity

BACKGROUND

Immunotherapy has gradually fallen out of favor for the treatment of many allergic diseases because of the overall convenience, safety, and efficacy of medications. However, investigations suggest that allergen/immunostimulatory sequence oligodeoxynucleotide (ISS-ODN) conjugates (AICs) might have improved safety and efficacy compared with allergen extracts.

OBJECTIVE

We determined whether changes in the ISS-ODN conjugation ratio would effect the immunogenicity and allergenicity of AIC.

METHODS

Immunogenicity was determined by means of AIC vaccination of mice, followed by analysis of antigen-specific antibody and cytokine responses. The allergenicity of AIC was determined in mast cell release studies and in murine models of anaphylaxis and the Arthus reaction.

RESULTS

AIC induced a stronger immune response than allergen alone or allergen mixed with ISS-ODN, but higher-level ISS-ODN conjugation reduced its immunogenicity modestly. In mast cell degranulation studies AIC was approximately 100-fold less allergenic than native allergen, with stepwise increases in the ODN conjugation ratio leading to stepwise decreases in allergenicity. In anaphylaxis studies death rates were reduced from 100% with native allergen challenge to as low as 0% with high-ratio ISS-ODN AIC challenge. Similar results were obtained in an Arthus reaction model.

CONCLUSION

These investigations establish that AIC is both significantly more immunogenic and less allergenic than native allergens and the techniques used might have further utility for the standardization and optimization of AIC formulations for use in allergic patients.