The polyclonal and antigen-specific IgE and IgG subclass response of mice injected with ovalbumin in alum or complete Freund's adjuvant

Development of an engineered extracellular vesicles-based vaccine platform for combined delivery of mRNA and protein to induce functional immunity

mRNA incorporated in lipid nanoparticles (LNPs) became a new class of vaccine modality for induction of immunity against COVID-19 and ushered in a new era in vaccine development. Here, we report a novel, easy-to-execute, and cost effective engineered extracellular vesicles (EVs)-based combined mRNA and protein vaccine platform (EVX-M+P vaccine) and explore its utility in proof-of-concept immunity studies in the settings of cancer and infectious disease. As a first example, we engineered EVs, natural nanoparticle carriers shed by all cells, to contain ovalbumin mRNA and protein (EVOvaM+P vaccine) to serve as cancer vaccine against ovalbumin-expressing melanoma tumors. EVOvaM+P administration to mice with established melanoma tumors resulted in tumor regression associated with effective humoral and adaptive immune responses. As a second example, we generated engineered EVs that contain Spike (S) mRNA and protein to serve as a combined mRNA and protein vaccine (EVSpikeM+P vaccine) against SARS-CoV-2 infection. EVSpikeM+P vaccine administration in mice and baboons elicited robust production of neutralizing IgG antibodies against RBD (receptor binding domain) of S protein and S protein specific T cell responses. Our proof-of-concept study describes a new platform with an ability for rapid development of combination mRNA and protein vaccines employing EVs for deployment against cancer and other diseases.

Core fucosylation within the Fc-FcγR degradation pathway promotes enhanced IgG levels via exogenous L-fucose

α1,6-Fucosyltransferase (Fut8) is the enzyme responsible for catalyzing core fucosylation. Exogenous L-fucose upregulates fucosylation levels through the GDP-fucose salvage pathway. This study investigated the relationship between core fucosylation and immunoglobulin G (IgG) amounts in serum utilizing WT (Fut8+/+), Fut8 heterozygous knockout (Fut8+/-), and Fut8 knockout (Fut8-/-) mice. The IgG levels in serum were lower in Fut8+/- and Fut8-/- mice compared with Fut8+/+ mice. Exogenous L-fucose increased IgG levels in Fut8+/- mice, while the ratios of core fucosylated IgG versus total IgG showed no significant difference among Fut8+/+, Fut8+/-, and Fut8+/- mice treated with L-fucose. These ratios were determined by Western blot, lectin blot, and mass spectrometry analysis. Real-time PCR results demonstrated that mRNA levels of IgG Fc and neonatal Fc receptor, responsible for protecting IgG turnover, were similar among Fut8+/+, Fut8+/-, and Fut8+/- mice treated with L-fucose. In contrast, the expression levels of Fc-gamma receptor Ⅳ (FcγRⅣ), mainly expressed on macrophages and neutrophils, were increased in Fut8+/- mice compared to Fut8+/+ mice. The effect was reversed by administrating L-fucose, suggesting that core fucosylation primarily regulates the IgG levels through the Fc-FcγRⅣ degradation pathway. Consistently, IgG internalization and transcytosis were suppressed in FcγRⅣ-knockout cells while enhanced in Fut8-knockout cells. Furthermore, we assessed the expression levels of specific antibodies against ovalbumin and found they were downregulated in Fut8+/- mice, with potential recovery observed with L-fucose administration. These findings confirm that core fucosylation plays a vital role in regulating IgG levels in serum, which may provide insights into a novel mechanism in adaptive immune regulation.

Design of Cytotoxic T Cell Epitopes by Machine Learning of Human Degrons

Antigen processing is critical for therapeutic vaccines to generate epitopes for priming cytotoxic T cell responses against cancer and pathogens, but insufficient processing often limits the quantity of epitopes released. We address this challenge using machine learning to ascribe a proteasomal degradation score to epitope sequences. Epitopes with varying scores were translocated into cells using nontoxic anthrax proteins. Epitopes with a low score show pronounced immunogenicity due to antigen processing, but epitopes with a high score show limited immunogenicity. This work sheds light on the sequence-activity relationships between proteasomal degradation and epitope immunogenicity. We anticipate that future efforts to incorporate proteasomal degradation signals into vaccine designs will lead to enhanced cytotoxic T cell priming by these vaccines in clinical settings.

Conserved molecular chaperone PrsA stimulates protective immunity against group A Streptococcus

Group A Streptococcus (GAS) is a significant human pathogen that poses a global health concern. However, the development of a GAS vaccine has been challenging due to the multitude of diverse M-types and the risk of triggering cross-reactive immune responses. Our previous research has identified a critical role of PrsA1 and PrsA2, surface post-translational molecular chaperone proteins, in maintaining GAS proteome homeostasis and virulence traits. In this study, we aimed to further explore the potential of PrsA1 and PrsA2 as vaccine candidates for preventing GAS infection. We found that PrsA1 and PrsA2 are highly conserved among GAS isolates, demonstrating minimal amino acid variation. Antibodies specifically targeting PrsA1/A2 showed no cross-reactivity with human heart proteins and effectively enhanced neutrophil opsonophagocytic killing of various GAS serotypes. Additionally, passive transfer of PrsA1/A2-specific antibodies conferred protective immunity in infected mice. Compared to alum, immunization with CFA-adjuvanted PrsA1/A2 induced higher levels of Th1-associated IgG isotypes and complement activation and provided approximately 70% protection against invasive GAS challenge. These findings highlight the potential of PrsA1 and PrsA2 as universal vaccine candidates for the development of an effective GAS vaccine.

Immunization Effects of a Novel α-Synuclein-Based Peptide Epitope Vaccine in Parkinson's Disease-Associated Pathology

Parkinson's disease (PD) is a chronic neurodegenerative disease that affects the central nervous system, specifically the motor system. It is mainly caused by the loss of dopamine due to the accumulation of α-synuclein (α-syn) protein in the striatum and substantia nigra pars compacta (SNpc). Previous studies have reported that immunization may be a potential preventive strategy for neurodegenerative diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Therefore, the aim of the study was to design an α-syn specific epitope vaccine and investigate its effect in PD-related pathophysiology using an α-syn-induced mouse model. We used an in silico model to identify and design a non-toxic α-syn-based peptide epitope vaccine and, to overcome poor immunogenicity, the vaccine was coupled with immunogenic carrier proteins, i.e., ovalbumin (OVA) and keyhole limpet haemocyanin (KLH). Our results showed that vaccinated PD mouse models, especially with vaccines with carrier proteins, improved in motor functions compared with the non-vaccinated PD model. Additionally, the vaccinated groups showed increased immunoglobulin G (IgG) levels in the spleen and plasma as well as decreased interleukin-10 (IL-10) levels in the plasma. Furthermore, vaccinated groups, especially OVA and KLH groups, showed decrease in α-syn levels and increased dopamine-related markers, i.e., tyrosine hydroxylase (TH), vesicle monoamine transporter 2 (VMAT2), and dopamine transporter (DAT), and autophagy activities in the striatum and SNpc. Lastly, our data showed decreased neuroinflammation by reducing the activation of microglia and astrocytes and pro-inflammatory cytokines in the immunized groups, especially with OVA and KLH carrier proteins. Overall, these results suggest that vaccination, especially with immunogenic carrier proteins, is effective in reducing the accumulation of α-syn aggregates in the brain and ameliorate PD-related pathophysiology. Hence, further development of this approach might have a potential role in preventing the development of PD.

Enhanced Vaccine Immunogenicity Enabled by Targeted Cytosolic Delivery of Tumor Antigens into Dendritic Cells

Molecular vaccines comprising antigen peptides and inflammatory cues make up a class of therapeutics that promote immunity against cancer and pathogenic diseases but often exhibit limited efficacy. Here, we engineered an antigen peptide delivery system to enhance vaccine efficacy by targeting dendritic cells and mediating cytosolic delivery. The delivery system consists of the nontoxic anthrax protein, protective antigen (PA), and a single-chain variable fragment (scFv) that recognizes the XCR1 receptor on dendritic cells (DCs). Combining these proteins enabled selective delivery of the N-terminus of lethal factor (LFN) into XCR1-positive cross-presenting DCs. Incorporating immunogenic epitope sequences into LFN showed selective protein translocation in vitro and enhanced the priming of antigen-specific T cells in vivo. Administering DC-targeted constructs with tumor antigens (Trp1/gp100) into mice bearing aggressive B16-F10 melanomas improved mouse outcomes when compared to free antigen, including suppressed tumor growth up to 58% at 16 days post tumor induction (P < 0.0001) and increased survival (P = 0.03). These studies demonstrate that harnessing DC-targeting anthrax proteins for cytosolic antigen delivery significantly enhances the immunogenicity and antitumor efficacy of cancer vaccines.

Design of Cytotoxic T Cell Epitopes by Machine Learning of Human Degrons

Antigen processing is critical for producing epitope peptides that are presented by HLA molecules for T cell recognition. Therapeutic vaccines aim to harness these epitopes for priming cytotoxic T cell responses against cancer and pathogens, but insufficient processing often reduces vaccine efficacy through limiting the quantity of epitopes released. Here, we set out to improve antigen processing by harnessing protein degradation signals called degrons from the ubiquitin-proteasome system. We used machine learning to generate a computational model that ascribes a proteasomal degradation score between 0 and 100. Epitope peptides with varying degron activities were synthesized and translocated into cells using nontoxic anthrax proteins: protective antigen (PA) and the N-terminus of lethal factor (LFN). Immunogenicity studies revealed epitope sequences with a low score (<25) show pronounced T-cell activation but epitope sequences with a higher score (>75) provide limited activation. This work sheds light on the sequence-activity relationships between proteasomal degradation and epitope immunogenicity, through conserving the epitope region but varying the flanking sequence. We anticipate that future efforts to incorporate proteasomal degradation signals into vaccine designs will lead to enhanced cytotoxic T cell priming by vaccine therapeutics in clinical settings.

Translational regulation of TFH cell differentiation and autoimmune pathogenesis

Little is known regarding T cell translational regulation. We demonstrate that T follicular helper (TFH) cells use a previously unknown mechanism of selective messenger RNA (mRNA) translation for their differentiation, role in B cell maturation, and in autoimmune pathogenesis. We show that TFH cells have much higher levels of translation factor eIF4E than non-TFH CD4+ T cells, which is essential for translation of TFH cell fate-specification mRNAs. Genome-wide translation studies indicate that modest down-regulation of eIF4E activity by a small-molecule inhibitor or short hairpin RN impairs TFH cell development and function. In mice, down-regulation of eIF4E activity specifically reduces TFH cells among T helper subtypes, germinal centers, B cell recruitment, and antibody production. In experimental autoimmune encephalomyelitis, eIF4E activity down-regulation blocks TFH cell participation in disease pathogenesis while promoting rapid remission and spinal cord remyelination. TFH cell development and its role in autoimmune pathogenesis involve selective mRNA translation that is highly druggable.

Effective Model of Food Allergy in Mice Sensitized with Ovalbumin and Freud's Adjuvant

To better explore the pathophysiology of FA and its therapy, we aimed to establish a simple and practicable FA model with Freund's adjuvant and introduce an easy and reliable laboratory evaluation method for assessment of inflammation in intestinal segments at different anatomical locations. BALB/c mice were sensitized with ovalbumin combined with Freund's adjuvant. Complete Freund's adjuvant was chosen for the first sensitization and two weeks later incomplete Freund's adjuvant was used for a second sensitization. Two weeks later, the sensitized mice were challenged with 50 mg ovalbumin every other day. After the 6 challenge, all mice were assessed for systemic anaphylaxis, and then sacrificed for sample collection. All sensitized mice showed anaphylactic symptoms and markedly increased levels of serum ovalbumin-specific IgE and IgG1. The activity of mast cell protease-1 (mMCPT-1) was significantly increased in the serum and interstitial fluid of the duodenum, jejunum, ileum, and colon. A successful FA model was established, of which inflammation occurred in the duodenum, jejunum, ileum, and colon. This model provides a reliable and simple tool for analysis of the mechanism of FA and methods of immunotherapy. Moreover, combined detection of ovalbumin-specific antibody and local mMCPT-1 levels could potentially be used as the major indicator for assessment of food allergy.

Immunomodulatory effect of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in allergic conditions in vitro and in vivo

We found that strawberry extract suppressed immunoglobulin (Ig) E production in vitro and in vivo, and identified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as one of the IgE suppressor in the extract. We report here the effect of GAPDH on various Ig productions in vitro and in vivo. GAPDH suppressed IgE and enhanced IgA, IgG and IgM productions in ovalbumin (OVA)-stimulated human peripheral blood mononuclear cells. Oral administration of GAPDH at 10 mg/kg/day to OVA-induced allergy model mice tended to decrease total IgE level and increase total IgA and IgG levels in sera, and also decreased OVA-specific IgE and IgG levels. It is known that the increase of total IgA as well as the decrease of total and specific IgE is important for alleviating allergic symptoms. In addition, GAPDH accelerated IgA production and increased some cytokine secretions such as IL-4, TGF-β1 and IFN-γ in the OVA-immunized mice spleen lymphocytes. These cytokines involved in the class-switching, IgA enhancement, and IgE suppression, respectively, supporting above results. Our study suggests a possibility that oral administration of GAPDH may induce the immunomodulation in allergic responses.

Biodegradable Cationic Polycarbonates as Vaccine Adjuvants

In this study, biodegradable cationic polycarbonate and polylactide block copolymers were synthesized and successfully used as novel vaccine adjuvants to provide enhanced anticancer immunity. The polymers formed nanoparticles with the model vaccine, ovalbumin (OVA), and the immunostimulant toll-like receptor 3 agonist poly(I:C) (a synthetic analog of the double-stranded RNA). Higher uptake of poly(I:C) by the bone marrow-derived dendritic cells and macrophages and OVA by dendritic cells was observed when delivered using the polymer adjuvant. In vivo experiments showed that these nanoparticles remained longer in the subcutaneous injection site as compared to OVA alone and led to higher production of anti-OVA specific antibodies with prolonged immunostimulation. When OVA was combined with poly(I:C) that was either co-entrapped in the same particles or as separate particles, a comparable level of anti-OVA IgG1 antibodies and interleukin-6 (IL-6) was produced in mouse blood plasma, and a similar level of cytotoxic T lymphocyte (CTL) response in mice was stimulated as compared to OVA/Alum particles. Furthermore, tumor rejection in the mice that were vaccinated for 9 months with the formulations containing the polymer adjuvant was stronger than the other treatment groups without the polymer. Notably, the cationic polycarbonates were not associated with any adverse in vivo effects. Thus, these biodegradable polymers may be promising substitutes for aluminum-based adjuvants in vaccine formulations.

GrpE Immunization Protects Against Ureaplasma urealyticum Infection in BALB/C Mice

Nucleotide exchange factor (GrpE), a highly conserved antigen, is rapidly expressed and upregulated when Ureaplasma urealyticum infects a host, which could act as a candidative vaccine if it can induce an anti-U. urealyticum immune reaction. Here, we evaluated the vaccine potential of recombinant GrpE protein adjuvanted by Freund's adjuvant (FA), to protect against U. urealyticum genital tract infection in a mouse model. After booster immunization in mice with FA, the GrpE can induced both humoral and cellular immune response after intramuscular injection into BALB/c mice. A strong humoral immune response was detected in the GrpE-immunized mice characterized by production of high titers of antigen-specific serum IgG (IgG1, IgG2a, and IgG3) antibodies. At the same time, the GrpE also induced a Th1-biased cytokine spectrum with high levels of IFN-γ and TNF-α after re-stimulation with immunogen GrpE in vitro, suggesting that GrpE could trigger the Th1 response when used for vaccination in the presence of FA. Although GrpE vaccination in the presence of a Th1-type adjuvant-induced had readily detectable Th1 responses, there wasn't increase inflammation in response to the infection. More importantly, the robust immune responses in mice after immunization with GrpE showed a significantly reduced U. urealyticum burden in cervical tissues. Histopathological analysis confirmed that tissues of GrpE-immunized BALB/c mice were protected against the pathological effects of U. urealyticum infection. In conclusion, this study preliminarily reveals GrpE protein as a promising new candidate vaccine for preventing U. urealyticum reproductive tract infection.

A Computationally Optimized Broadly Reactive Antigen Subtype-Specific Influenza Vaccine Strategy Elicits Unique Potent Broadly Neutralizing Antibodies against Hemagglutinin

Computationally optimized broadly reactive Ags (COBRA) targeting H1 elicit a broad cross-reactive and cross-neutralizing Ab response against multiple H1N1 viral strains. To assess B cell breadth, Mus musculus (BALB/c) Ab-secreting cells elicited by a candidate COBRA hemagglutinin (HA) (termed P1) were compared with Ab-secreting cells elicited by historical H1N1 vaccine strains. In addition, to evaluate the Ab response elicited by P1 HA at increased resolution, a panel of P1 HA-specific B cell hybridomas was generated following immunization of mice with COBRA P1 and the corresponding purified mAbs were characterized for Ag specificity and neutralization activity. Both head- and stem-directed mAbs were elicited by the P1 HA Ag, with some mAbs endowed with Ab-dependent cell-mediated cytotoxicity activity. P1 HA-elicited mAbs exhibited a wide breadth of HA recognition, ranging from narrowly reactive to broadly reactive mAbs. Interestingly, we identified a P1 HA-elicited mAb (1F8) exhibiting broad hemagglutination inhibition activity against both seasonal and pandemic H1N1 influenza strains. Furthermore, mAb 1F8 recognized an overlapping, but distinct, epitope compared with other narrowly hemagglutination inhibition-positive mAbs elicited by the P1 or wild-type HA Ags. Finally, P1 HA-elicited mAbs were encoded by distinct H chain variable and L chain variable gene segment rearrangements and possessed unique CDR3 sequences. Collectively, the functional characterization of P1 HA-elicited mAbs sheds further insights into the underlying mechanism(s) of expanded Ab breadth elicited by a COBRA HA-based immunogen and advances efforts toward design and implementation of a more broadly protective influenza vaccine.

Ovalbumin Epitope SIINFEKL Self-Assembles into a Supramolecular Hydrogel

Here we show that the well-known ovalbumin epitope SIINFEKL that is routinely used to stimulate ovalbumin-specific T cells and to test new vaccine adjuvants can form a stable hydrogel. We investigate properties of this hydrogel by a range of spectroscopic and imaging techniques demonstrating that the hydrogel is stabilized by self-assembly of the peptide into nanofibres via stacking of β-sheets. As peptide hydrogels are known to stimulate an immune response as adjuvants, the immunoactive properties of the SIINFEKL peptide may also originate from its propensity to self-assemble into a hydrogel. This finding requires a re-evaluation of this epitope in adjuvant testing.

Efficacy comparison of adjuvants in PcrV vaccine against Pseudomonas aeruginosa pneumonia

Vaccination against the type III secretion system of P. aeruginosa is a potential prophylactic strategy for reducing the incidence and improving the poor prognosis of P. aeruginosa pneumonia. In this study, the efficacies of three different adjuvants, Freund's adjuvant (FA), aluminum hydroxide (alum) and CpG oligodeoxynucleotide (ODN), were examined from the viewpoint of inducing PcrV-specific immunity against virulent P. aeruginosa. Mice that had been immunized intraperitoneally with recombinant PcrV formulated with one of the above adjuvants were challenged intratracheally with a lethal dose of P. aeruginosa. The PcrV-FA immunized group attained a survival rate of 91%, whereas the survival rates of the PcrV-alum and PcrV-CpG groups were 73% and 64%, respectively. In terms of hypothermia recovery after bacterial instillation, PcrV-alum was the most protective, followed by PcrV-FA and PcrV-CpG. The lung edema index was lower in the PcrV-CpG vaccination group than in the other groups. PcrV-alum immunization was associated with the greatest decrease in myeloperoxidase in infected lungs, and also decreased the number of lung bacteria to a similar number as in the PcrV-FA group. There was less neutrophil recruitment in the lungs of mice vaccinated with PcrV-alum or PcrV-CpG than in those of mice vaccinated with PcrV-FA or PcrV alone. Overall, in terms of mouse survival the PcrV-CpG vaccine, which could be a relatively safe next-generation vaccine, showed a comparable effect to the PcrV-alum vaccine.

The Immunomodulatory Role of Adjuvants in Vaccines Formulated with the Recombinant Antigens Ov-103 and Ov-RAL-2 against Onchocerca volvulus in Mice

BACKGROUND

In some regions in Africa, elimination of onchocerciasis may be possible with mass drug administration, although there is concern based on several factors that onchocerciasis cannot be eliminated solely through this approach. A vaccine against Onchocerca volvulus would provide a critical tool for the ultimate elimination of this infection. Previous studies have demonstrated that immunization of mice with Ov-103 and Ov-RAL-2, when formulated with alum, induced protective immunity. It was hypothesized that the levels of protective immunity induced with the two recombinant antigens formulated with alum would be improved by formulation with other adjuvants known to enhance different types of antigen-specific immune responses.

METHODOLOGY/ PRINCIPAL FINDINGS

Immunizing mice with Ov-103 and Ov-RAL-2 in conjunction with alum, Advax 2 and MF59 induced significant levels of larval killing and host protection. The immune response was biased towards Th2 with all three of the adjuvants, with IgG1 the dominant antibody. Improved larval killing and host protection was observed in mice immunized with co-administered Ov-103 and Ov-RAL-2 in conjunction with each of the three adjuvants as compared to single immunizations. Antigen-specific antibody titers were significantly increased in mice immunized concurrently with the two antigens. Based on chemokine levels, it appears that neutrophils and eosinophils participate in the protective immune response induced by Ov-103, and macrophages and neutrophils participate in immunity induced by Ov-RAL-2.

CONCLUSIONS/SIGNIFICANCE

The mechanism of protective immunity induced by Ov-103 and Ov-RAL-2, with the adjuvants alum, Advax 2 and MF59, appears to be multifactorial with roles for cytokines, chemokines, antibody and specific effector cells. The vaccines developed in this study have the potential of reducing the morbidity associated with onchocerciasis in humans.

Ganoderma formosanum polysaccharides attenuate Th2 inflammation and airway hyperresponsiveness in a murine model of allergic asthma

Allergic asthma is an inflammatory disease of the airways mediated by Th2 immune responses and characterized by airway hyperresponsiveness (AHR). Fungi of the genus Ganoderma are basidiomycetes that have been used in traditional Asian medicine for centuries. We recently found that PS-F2, a polysaccharide fraction purified from the submerged culture broth of Ganoderma formosanum, stimulates the activation of dendritic cells and primes a T helper 1 (Th1)-polarized adaptive immune response. This study was designed to investigate whether the Th1 adjuvant properties of PS-F2 could suppress the development of allergic asthma in a mouse model. BALB/c mice were sensitized by repeated immunization with chicken ovalbumin (OVA) and alum, followed by intranasal challenge of OVA to induce acute asthma. PS-F2 administration during the course of OVA sensitization and challenge effectively prevented AHR development, OVA-specific IgE and IgG1 production, bronchial inflammation, and Th2 cytokine production. Our data indicate that PS-F2 has a potential to be used for the prevention of allergic asthma.

Immunomodulatory properties of the vaccine adjuvant alum

Alum, the most common adjuvant in non-living vaccines, has a record of successful use in human vaccination where it promotes antibody-mediated protective immunity. However, alum is a poor inducer of cellular immune responses. The mechanism underlying the selective enhancement of humoral immunity is still not well understood. Here, to provide an insight into its mode of action, recent findings regarding innate immune responses induced by alum and their impact on adaptive immunity are described, with a particular emphasis on early recognition of alum, including NLRP3 and PI3 kinase activation, adjuvant-induced cell death and the release of endogenous danger signals. Expanding our knowledge of alum-induced immunomodulation will greatly enhance our capacity to rationally develop novel adjuvants with specific properties.

An efficient single prime protocol for the induction of antigen-induced airways inflammation

There are a number of mouse models of allergic airway inflammation used to delineate various aspects of asthma. One of the hurdles with using mice is their natural resistance to developing a Th2 allergic response. This is often overcome by double priming with the allergen and an adjuvant. Here we report on an efficient 11day, single antigen/alum priming protocol that is sufficient to sensitise mice for the development of Th2-mediated inflammation in the lung following antigen challenge.

Transcutaneous immunization system using a hydrotropic formulation induces a potent antigen-specific antibody response

Background

Transcutaneous immunization (TCI) is a novel vaccination strategy, which is expected to have therapeutic applications. However, to develop effective TCI systems, a simple, non-invasive and safe transdermal formulation is required. This study developed a novel TCI system utilizing the co-administration of a liposoluble absorption enhancer, propylene glycol monocaprylate (PGMC) and hydrosoluble protein antigen without pretreatment of any typical adjuvants and disruption of the skin. Novel transdermal formulations were also prepared with sodium salicylate (NaSal) as a hydrotropic agent to improve the solubility of poorly water-soluble substances.

Methodology/Principal Findings

The TCI system, which used a transdermal formulation containing hen lysozyme (HEL) and PGMC, solubilized with NaSal, resulted in a substantial HEL-specific antibody response in an HEL dose-dependent manner even in the absence of potent adjuvants, such as cholera toxin (CT). We also investigated whether NaSal activates antigen-presenting cells in vitro to clarify the mechanisms of antibody production by the hydrotropic formulation. NaSal enhanced the expression of MHC class II molecules and increased the production of IL-12 and TNF-α in dendritic cells, which were stimulated by lipopolysaccharide in vitro, indicating that NaSal had an effective adjuvant-like property. Moreover, the use of NaSal in the TCI system did not induce an HEL-specific, IgE-dependent anaphylactic reaction.

Conclusion/Significance

Our TCI system using a hydrotropic formulation effectively and safely induced the intended immune response, and this system thus represents a new advantageous method that will result in improved TCI strategies.

How aluminum adjuvants could promote and enhance non-target IgE synthesis in a genetically-vulnerable sub-population

Aluminum-containing adjuvants increase the effectiveness of vaccination, but their ability to augment immune responsiveness also carries the risk of eliciting non-target responses, especially in genetically susceptible individuals. This study reviews the relevant actions of aluminum adjuvants and sources of genetic risk that can combine to adversely affect a vulnerable sub-population. Aluminum adjuvants promote oxidative stress and increase inflammasome activity, leading to the release of IL-1β, IL-18, and IL-33, but not the important regulatory cytokine IL-12. In addition, they stimulate macrophages to produce PGE₂, which also has a role in regulating immune responses. This aluminum-induced cytokine context leads to a T(H)2 immune response, characterized by the further release of IL-3, IL-4, IL-5, IL-9, IL-13, and IgE-potentiating factors such as sCD23. Genetic variants in cytokine genes, such as IL-4, IL-13, IL-33, and IL-18 influence the response to vaccines in children and are also associated with atopy. These genetic factors may therefore define a genetically-vulnerable sub-population, children with a family history of atopy, who may experience an exaggerated T(H)2 immune response to aluminum-containing vaccines. IL-4, sCD23, and IgE are common factors for both atopy and the immune-stimulating properties of aluminum adjuvants. IL-4 is critical in the production of IgE and total IgE up-regulation. IL-4 has also been reported to induce the production of sCD23 and trigger resting sIgM+, sIgD+ B-cells to switch to sIgE+ B-cells, making them targets for IgE-potentiating factors. Further, the actions of IgE-potentiating factors on sIgE+ B-cells are polyclonal and unrestricted, triggering their differentiation into IgE-forming plasma cells. These actions provide a mechanism for aluminum-adjuvant promotion and enhancement of non-target IgE in a genetically vulnerable sub-population. Identification of these individuals may decrease the risk of adverse events associated with the use of aluminum-containing vaccines.

A single exposure to iron oxide nanoparticles attenuates antigen-specific antibody production and T-cell reactivity in ovalbumin-sensitized BALB/c mice

Background:

Superparamagnetic iron oxide nanoparticles have been used in clinical applications as a diagnostic contrasting agent. Previous studies showed that iron oxide nanoparticles deposited in the liver and spleen after systemic administration. The present study investigated the effect of iron oxide nanoparticles on antigen-specific immune responses in mice sensitized with the T cell-dependent antigen ovalbumin (OVA).

Methods:

BALB/c mice were intravenously administered with a single dose of iron oxide nanoparticles (10–60 mg Fe/kg) 1 hour prior to OVA sensitization, and the serum antibody production and splenocyte reactivity were examined 7 days later.

Results:

The serum levels of OVA-specific IgG₁ and IgG_2a were significantly attenuated by treatment with iron oxide nanoparticles. The production of interferon-γ and interleukin-4 by splenocytes re-stimulated with OVA in culture was robustly suppressed in mice administered with iron oxide nanoparticles. The viability of OVA-stimulated splenocytes was also attenuated. In contrast, treatment with iron oxide nanoparticles did not affect the viability of splenocytes stimulated with concanavalin A, a T-cell mitogen.

Conclusion:

Collectively, these data indicate that systemic exposure to a single dose of iron oxide nanoparticles compromises subsequent antigen-specific immune reactions, including the serum production of antigen-specific antibodies, and the functionality of T cells.

IL-4/STAT6 immune axis regulates peripheral nutrient metabolism and insulin sensitivity

Immune cells take residence in metabolic tissues, providing a framework for direct regulation of nutrient metabolism. Despite conservation of this anatomic relationship through evolution, the signals and mechanisms by which the immune system regulates nutrient homeostasis and insulin action remain poorly understood. Here, we demonstrate that the IL-4/STAT6 immune axis, a key pathway in helminth immunity and allergies, controls peripheral nutrient metabolism and insulin sensitivity. Disruption of signal transducer and activator of transcription 6 (STAT6) decreases insulin action and enhances a peroxisome proliferator-activated receptor α (PPARα) driven program of oxidative metabolism. Conversely, activation of STAT6 by IL-4 improves insulin action by inhibiting the PPARα-regulated program of nutrient catabolism and attenuating adipose tissue inflammation. These findings have thus identified an unexpected molecular link between the immune system and macronutrient metabolism, suggesting perhaps the coevolution of these pathways occurred to ensure access to glucose during times of helminth infection.

Macaque sperm coating protein DEFB126 facilitates sperm penetration of cervical mucus

BACKGROUND

Sperm coating protein beta-defensin 126 (DEFB126) is adsorbed onto the entire surface of macaque sperm in the caudal epididymis and is retained on viable sperm collected from the cervix and the uterine lumen of mated female macaques. We investigated the role of sperm coating protein DEFB126 in cervical mucus penetration (CMP).

METHODS

Cervical mucus (CM) was collected from peri-ovulatory female macaques and loaded into CMP chambers. Sperm were introduced to CMP chambers following treatment with either polyclonal antibodies raised to DEFB126 or seminal plasma proteins (SPPs), 1 mM caffeine+1 mM dibutyryl cyclic adenosine monophosphate (dbcAMP) (induces release of DEFB126 from sperm surface), neuraminidase (NMase) or poly-L-lysine (PLP). Following removal of DEFB126 or SPPs from the sperm surface, sperm were treated with concentrated DEFB126 or concentrated SPPs prior to being introduced to CMP chambers. The numbers of sperm that penetrated and traversed CM were scored over 6 min.

RESULTS

Treatment of sperm with anti-DEFB126 antibodies, 1 mM caffeine+1 mM dbcAMP, NMase, and PLP resulted in similar and significant levels of inhibition of sperm CMP, whereas addition of anti-SPPs antibodies had no effect. In experiments where DEFB126 and SPPs were removed, CMP capability of sperm was restored by addition of DEFB126 back to the sperm surface, whereas treatment of sperm with concentrated SPPs slightly inhibited sperm penetration.

CONCLUSIONS

DEFB126 and its high negative charge appears to be critical for the movement of sperm through CM in the macaque, while SPPs adhered to the sperm surface offer no advantage in CMP.

Vitamin A deficiency decreases and high dietary vitamin A increases disease severity in the mouse model of asthma

The Th1/Th2 paradigm has become an important issue in the pathogenesis of asthma, characterized by normal Th1 and elevated Th2 cytokine expression. Vitamin A deficiency (VAD) can produce a Th1 bias, whereas high-level dietary vitamin A can promote a Th2 bias. We used the OVA exposure mouse model to determine the contributions of vitamin A-deficient, control (4IU/g), and high-level vitamin A (250-IU/g) diets to the development of allergic airway inflammation and hyperresponsiveness. VAD reduced serum IgE and IgG1 responses, pulmonary eosinophilia, and the levels of IL-4 and IL-5 in bronchoalveolar lavage specimens, whereas the 250-IU/g diet increased serum IgE. Also, VAD blocked pulmonary hyperresponsiveness following methacholine challenge while the 250-IU/g diet exacerbated pulmonary hyperresponsiveness. In conclusion, VAD diminished and high-level dietary vitamin A enhanced the development of experimental asthma in this model system. These data suggest that excessive intake of vitamin A may increase the risk or severity of asthma in industrialized countries whereas vitamin A deficiency continues to increase mortality from infectious diseases in developing countries.

Animal models of airway sensitization

Asthma is a complex phenotype that involves multiple mechanisms, including adaptive and innate immunity as well as physiological and mechanical changes in the airways. A cardinal feature of asthma is airway hyperreactivity (AHR), a multifaceted reaction that can only be assessed in vivo. Mouse models of asthma replicate many of the features of human asthma, including AHR, which can be assessed using standard protocols. Examination of AHR in mice has provided important information about human asthma, primarily because the immunology of allergy is easily studied in mice, especially with the availability of reagents including genetically modified mice. In this unit we discuss the induction and measurement of AHR and the two most common methodologies: noninvasive measurement using a whole-body plethysmograph (WBP) and invasive measurement of lung resistance and dynamic compliance.

Enhanced desensitization efficacy by liposomal conjugation of a specific antigen

Since liposomes are known as strong adjuvants, we attempted to use liposomes in immunotherapy as adjuvants, and to achieve desensitization in pre-sensitized mice. At first, we sensitized mice with intraperitoneal injection of model antigen, 100 microg ovalbumin (OVA), with Alum and treated them with liposome composed of distearoylphosphatidylcholine (DSPC) and cholesterol (2:1 as a molar ratio), which was coupled with a small amount of OVA (10 microg OVA in 400 nmol DSPC and 200 nmol cholesterol-liposome was injected into 20 g mouse). It is well known that antigen-specific immunotherapy increases IgG blocking antibodies and decreases in IgE antibodies. The treatment with i.v. injection of OVA-liposome at days 8, 10, and 12 after sensitization strongly suppressed OVA-specific IgE production without affecting IgG level after the boost (100 microg OVA with Alum). Moreover, the treatment with high-density OVA-liposome (10 microg OVA in 80 nmol DSPC and 40 nmol cholesterol-liposome/20 g mouse) not only strongly suppressed IgE levels but also reduced IgG production after the boost of OVA-sensitized mice suggesting the importance of liposomal characteristic in desensitization immunotherapy. Next we reduced the dose of OVA-liposome and the desensitization effect was also observed at the dose of as low as 1 microg OVA on OVA-liposome/mouse. On the contrary, free OVA did not affect the production of both IgG and IgE levels. Biodistribution study indicated that OVA-liposome was highly accumulated in spleen of OVA-sensitized mice compared to control liposome at 3 h after i.v. injection. These results suggest that the liposomal OVA effectively interacts with and desensitizes immune cells, therefore, liposomes coupling with a certain antigen may be effective in allergy immunotherapy.

Suppressive effects of cannabidiol on antigen-specific antibody production and functional activity of splenocytes in ovalbumin-sensitized BALB/c mice

Cannabidiol (CBD) and cannabis-based medicines are potential therapeutic agents. Because the immune system has been widely demonstrated to be affected by psychoactive cannabinoids, such as Delta(9)-tetrahydrocannabinol, the objective of the present studies is to investigate the immunomodulatory effect of CBD, the major non-psychoactive cannabinoid in marijuana. BALB/c mice were intraperitoneally administered with a single dose of CBD (5-20 mg/kg) prior to ovalbumin (OVA) sensitization, and the serum production of antigen-specific antibodies was measured 7 days post OVA sensitization. The serum level of OVA-specific IgM was significantly attenuated by a high dose of CBD (20 mg/kg), and OVA-specific IgG(1) and IgG(2a) by all 3 doses of CBD. Concordantly, splenocytes of mice administered with CBD (5 or 20 mg/kg) produced less IL-2, IL-4 and IFN-gamma than those of vehicle-treated controls, upon ex vivo stimulation with phorbol ester plus calcium ionophore. Likewise, T-cell mitogen (concanavalin A)-induced proliferation of splenocytes was also markedly suppressed in mice administered with CBD. Furthermore, the observed ex vivo effects of CBD on cytokine production and T-cell proliferation were confirmed in splenocytes directly exposed to CBD (1-8 microM) in vitro, indicating a direct effect by CBD. Taken together, the results demonstrated that CBD markedly suppressed antigen-specific antibody production in OVA-sensitized mice, and suggest that CBD-mediated suppression of humoral immunity could be mediated by the impaired functions of splenocytes.

A latex-induced allergic airway inflammation model in mice

Latex allergy is important due to serious health impacts and widespread use of its products. Latex allergic reactions can be induced in skin and mucosal surfaces including the respiratory tract. The development of murine models of allergic airway inflammation has provided a framework to dissect out the cellular and molecular mechanisms of allergic respiratory inflammation. In this study we have developed a new mouse model of latex allergic airway inflammation using aerosol inhalation. The allergic inflammatory responses were characterized in this model. Mice were injected intraperitoneally with 0, 10, 50, or 200 microg of latex extract and their serum anti-latex IgE titers were determined. In the second stage, a standard protocol of inhalation was designed and three doses of latex extract solutions including 1%, 0.1%, and 0.01% were used to induce allergic airway inflammation. Bronchoalveolar lavage cytokines (IL-5 and IL-13) and serum anti-latex IgE and IgG(1) titers were determined by ELISA. Eosinophil levels in lung, peripheral blood, bronchoalveolar lavage and bone marrow were also evaluated. Histological analysis of lung tissue was also performed after latex inhalation. The aerosol inhalation of 1% latex allergens solution and presensitization with 50 mug of latex in this study resulted in the development of allergic airway inflammation characterized by elevated allergen specific IgE and IgG(1), peripheral blood, bronchoalveolar lavage and bone marrow eosinophilia. Histological analysis of the lung revealed an inflammatory response characterized by eosinophil accumulation. Elevated levels of Th2 cytokines IL-5 and IL-13 also were shown in bronchoalveolar lavage samples. These studies demonstrate that sensitization and subsequent aerosol inhalational challenge of latex allergen extract promotes allergic airway inflammation characterized by elevated IL-5 and IL-13 and eosinophils.

Differential T cell-mediated regulation of CD23 (Fc epsilonRII) in B cells and follicular dendritic cells

Differences in murine follicular dendritic cells (FDC)-CD23 expression under Th1 vs Th2 conditions prompted the hypothesis that T cells help regulate the phenotype of FDCs. FDCs express CD40, suggesting that T cell-CD40L and lymphokines may be involved in regulating FDC-CD23. To test this, highly enriched FDCs were incubated with CD40L trimer or anti-CD40 to mimic T cell signaling in the presence of IFN-gamma or IL-4. Surface expression of CD23 was determined by flow cytometry, whereas mRNA levels of CD23 and its isoforms CD23a and CD23b were independently measured by quantitative PCR. When FDCs were incubated with either CD40L trimer or agonistic anti-CD40 Ab, the expression of FDC-CD23 was increased both at the mRNA and protein levels. Moreover, engagement of FDC-CD40 enhanced mRNA levels for both CD23a and CD23b isoforms. In addition, IFN-gamma substantially enhanced CD23a and CD23b mRNA levels in CD40-stimulated FDCs. Curiously, IL-4 could also up-regulate FDC-CD23a but not -CD23b. Anti-IFN-gamma dramatically inhibited FDC-CD23 in mice immunized with CFA, whereas anti-IL-4 had only a modest inhibitory effect. In contrast with FDCs, IFN-gamma inhibited surface expression of murine B cell-CD23 as well as mRNA for B cell CD23a and -CD23b, whereas IL-4 dramatically enhanced message for both isoforms as well as protein expression. In short, CD23 was regulated very differently in FDCs and B cells. Previous studies suggest that high levels of FDC-CD23 inhibit IgE production, and this IFN-gamma and CD40L-mediated up-regulation of FDC-CD23 may explain, at least in part, why Th1 responses are associated with low IgE responses in vivo.

Mouse strain specificity of the IgE response to the major allergens of Phleum pratense

BACKGROUND

IgE immune responses against major allergens from Phleum pratense in low- and high-responder mouse strains were compared and the influence of alum was assessed, in order to evaluate the effect of the genetic background and adjuvants on IgE reactivity in a mouse model for P. pratense allergy.

METHODS

Different mouse strains and F1 offspring were sensitized with P. pratense pollen extract. Serum IgE levels, the induction of specific IgE antibodies and immediate cutaneous hypersensitivity reactions were monitored by ELISA, Western blot and a skin test, respectively.

RESULTS

All mouse strains investigated mounted an IgE response and exhibited a positive skin test to pollen extract. Differences were seen in the level of total serum IgE and in specific IgE reactivity to different major allergens of P. pratense. Notable differences were seen in IgE reactivity and immediate hypersensitivity against Phl p 1, which were only observed in SJL/j mice. The foremost influence of alum was on total IgE production levels.

CONCLUSIONS

Alum is not necessary as an adjuvant to elicit IgE reactivity against the clinically relevant allergens of P. pratense, since even low-responder mouse strains mounted a hypersensitivity reaction after sensitization without the adjuvant using otherwise identical sensitization strategies. Moreover, when analyzing the allergenicity of a compound, the hypersensitivity response of different mouse strains should be considered, as implicated by the differential results obtained for IgE reactivity against Phl p 1. Lastly, a genetic component may be involved in IgE reactivity to Phl p 1.

Allergen-immunostimulatory oligodeoxynucleotide conjugate: a novel allergoid for immunotherapy

PURPOSE OF REVIEW

To summarize the data of both preclinical studies and initial clinical trials of a novel allergoid for allergen specific immunotherapy. This allergoid consists of allergen covalently coupled to immunostimulatory oligodeoxynucleotide DNA sequences.

RECENT FINDINGS

Recently, immunostimulatory oligodeoxynucleotide sequences, also called unmethylated cytosin-guanine dinucleotide motifs, have been discovered that act as strong T helper 1 response inducing adjuvants in mice. Although mixing allergens with immunostimulatory DNA sequences induces T helper 1 responses in T helper 2 biased mice, the allergens in such mixes could still cause anaphylactic reactions when used in humans which is one of the reasons why immunotherapy has gradually been falling out of favor. Therefore, we made allergen-immunostimulatory oligodeoxynucleotide conjugates and investigated their immunogenicity and allergenicity in animal models of allergy. These conjugates were highly immunogenic for inducing T helper 1-like antiallergen responses and reversed T helper 2 responses and symptoms of asthma in mouse models. They were also less allergenic, as shown by the reaction with human immunoglobulin E antibodies and by histamine release from basophils of allergic patients. Preliminary phase I and II trials in ragweed allergic patients showed that allergen-immunostimulatory oligodeoxynucleotide conjugates are well tolerated, less allergenic and induce immunoglobulin G antiallergen antibodies more rapidly than allergen extracts without significantly increasing the immunoglobulin E titer.

SUMMARY

Allergen-immunostimulatory DNA conjugates induce T helper 1 and down regulate preexisting T helper 2 anti-allergen responses in mice. Initial phase I and II trials in ragweed allergic patients showed that ragweed allergen-DNA conjugates are well tolerated and induce a rapid immunoglobulin G but not E response. The data show that allergen-DNA conjugates are a novel type of allergoid that have great potential for a safe and potent form of allergen specific immunotherapy.

Persistent protective effect of heat-killed Escherichia coli producing "engineered," recombinant peanut proteins in a murine model of peanut allergy

BACKGROUND

Peanut allergy (PNA) is a life-threatening food allergy for which there is no definitive treatment.

OBJECTIVE

We investigated the long-term immunomodulatory effect of heat-killed Escherichia coli producing engineered (mutated) Ara h1, 2, and 3 (HKE-MP123) administered rectally (pr) in a murine model of PNA.

METHODS

Peanut-allergic C3H/HeJ mice received 0.9 (low dose), 9 (medium dose), or 90 (high dose) microg HKE-MP123 pr, HKE-containing vector (HKE-V) alone, or vehicle alone (sham) weekly for 3 weeks. Mice were challenged 2 weeks later. A second and third challenge were performed at 4-week intervals.

RESULTS

After the first challenge, all 3 HKE-MP123 and HKE-V-treated groups exhibited reduced symptom scores (P <.01,.01,.05,.05, respectively) compared with the sham-treated group. Interestingly, only the medium- and high-dose HKE-MP123-treated mice remained protected for up to 10 weeks after treatment accompanied by a significant reduction of plasma histamine levels compared with sham-treated mice (P <.05 and.01, respectively). IgE levels were significantly lower in all HKE-MP123-treated groups (P <.001), being most reduced in the high-dose HKE-MP123-treated group at the time of each challenge. IL-4, IL-13, IL-5, and IL-10 production by splenocytes of high-dose HKE-MP123-treated mice were significantly decreased (P <.01;.001,.001, and.001, respectively), and IFN-gamma and TGF-beta production were significantly increased (P <.001 and.01, respectively) compared with sham-treated mice at the time of the last challenge.

CONCLUSIONS

Treatment with pr HKE-MP123 can induce long-term "downregulation" of peanut hypersensitivity, which might be secondary to decreased antigen-specific T(H)2 and increased T(H)1 and T regulatory cytokine production.

Engineered recombinant peanut protein and heat-killed Listeria monocytogenes coadministration protects against peanut-induced anaphylaxis in a murine model

Peanut allergy (PNA) is the major cause of fatal and near-fatal anaphylactic reactions to foods. Traditional immunotherapy using peanut (PN) protein is not an option for PNA therapy because of the high incidence of adverse reactions. We investigated the effects of s.c. injections of engineered (modified) recombinant PN proteins and heat-killed Listeria monocytogenes (HKLM) as an adjuvant on anaphylactic reactions in a mouse model of PN allergy. PN-allergic C3H/HeJ mice were treated s.c. with a mixture of the three major PN allergens and HKLM (modified (m)Ara h 1-3 plus HKLM). The effects on anaphylactic reactions following PN challenge and the association with Ab levels and cytokine profiles were determined. Although all mice in the sham-treated groups exhibited anaphylactic symptoms with a median symptom score of 3, only 31% of mice in the mAra h 1-3 plus HKLM group developed mild anaphylaxis, with a low median symptom score of 0.5. Alterations in core body temperature, bronchial constriction, plasma histamine, and PN-specific IgE levels were all significantly reduced. This protective effect was markedly more potent than in the mAra h 1-3 protein alone-treated group. HKLM alone did not have any protective effect. Reduced IL-5 and IL-13, and increased IFN-gamma levels were observed only in splenocytes cultures from mAra h 1-3 plus HKLM-treated mice. These results show that immunotherapy with modified PN proteins and HKLM is effective for treating PN allergy in this model, and may be a potential approach for treating PNA.

T cell-independent regulation of IgE antibody production induced by surface-linked liposomal antigen

Control of IgE Ab production is important for the prevention of IgE-related diseases. However, in contrast to the existing information on the induction of IgE production, little is known about the regulation of the production of this isotype, with the exception of the well-documented mechanism involving T cell subsets and their cytokine products. In this study, we demonstrate an alternative approach to interfere with the production of IgE, independent of the activity of T cells, which was discovered during the course of an investigation intended to clarify the mechanism of IgE-selective unresponsiveness induced by surface-coupled liposomal Ags. Immunization of mice with OVA-liposome conjugates induced IgE-selective unresponsiveness without apparent Th1 polarization. Neither IL-12, IL-10, nor CD8(+) T cells participated in the regulation. Furthermore, CD4(+) T cells of mice immunized with OVA-liposome were capable of inducing Ag-specific IgE synthesis in athymic nude mice immunized with alum-adsorbed OVA. In contrast, immunization of the recipient mice with OVA-liposome did not induce anti-OVA IgE production, even when CD4(+) T cells of mice immunized with alum-adsorbed OVA were transferred. In the secondary immune response, OVA-liposome enhanced anti-OVA IgG Ab production, but it did not enhance ongoing IgE production, suggesting that the IgE-selective unresponsiveness induced by the liposomal Ag involved direct effects on IgE, but not IgG switching in vivo. These results suggest the existence of an alternative mechanism not involving T cells in the regulation of IgE synthesis.

Current opinion of immunotherapy for ocular allergy

PURPOSE OF REVIEW

Allergic conjunctivitis is common and may be the most prominent or the only feature of allergies. Immunotherapy has been used as a primary treatment for allergies since the early 1900s. Currently the use of immunotherapy for allergic rhinoconjunctivitis is well established and has been shown to decrease the development of bronchial hyperreactivity and asthma. However, the role of immunotherapy for primary treatment of allergic conjunctivitis is unclear. We reviewed the studies where immunotherapy was used with particular attention to the affects on ocular allergies.

RECENT FINDINGS

There are many schedules and methods of delivering immunotherapy. Recent studies have started to assess ocular symptoms as one of the parameters to monitor efficacy of therapy. They follow the affects of immunotherapy on conjunctival provocation tests, ocular symptoms, or the use of eye drops. The literature suggests that using the various immunotherapy modalities at different schedules, ocular symptoms improved even when immunotherapy was used on a rush schedule.

SUMMARY

The initiation of immunotherapy for allergic rhinoconjunctivitis has been shown to switch the immune response to T helper 1 and thus avoid the progression of other atopic conditions. Current literature shows that using many allergens with different forms of immunotherapy appear to have a significant improvement in ocular allergy symptoms and this can be achieved rapidly and safely in most patients. Whether using immunotherapy early in allergic conjunctivitis will alter the progression of other atopic conditions remains to be investigated.

The Dermatophagoides pteronyssinus group 2 allergen contains a universally immunogenic T cell epitope

The use of T cell epitope-containing peptides for the induction of anergy in allergen sensitization is limited by genetic restriction that could be circumvented by using universally immunogenic epitopes. We attempted to identify such epitopes on Dermatophagoides pteronyssinus group 2 allergen (Der p 2), a major allergen of D. pteronyssinus T cells from BALB/c (H-2(d)), C57BL/6 (H-2(b)), C3H (H-2(k)), and SJL (H-2(s)) mice that were immunized with rDer p 2, recognized an immunodominant region encompassing residues 21-35. A synthetic 21-35 peptide (p21-35) induced strong dose-dependent in vitro T cell proliferation with cells of the four mouse strains and required processing for MHC class II presentation. Substitution of Ile(28) with Ala resulted in reduction of T cell proliferation in each strain. Ile(28) could represent an important MHC class II anchoring residue for T cell response to p21-35. An immunodominant T cell epitope of Der p 2 therefore behaves as a universal epitope and could be a suitable candidate for T cell anergy induction.

Recombinant Dirofilaria immitis polyprotein that stimulates murine B cells to produce nonspecific polyclonal immunoglobulin E antibody

Nonspecific immunoglobulin E (IgE) production is an event characteristically observed in parasitic helminth infections, but its mechanisms are still unclear. To define these mechanisms, we prepared a recombinant Dirofilaria immitis protein (rDiAg) and assessed its effect on nonspecific IgE production. rDiAg preferentially induced nonspecific IgE production, without eliciting specific IgE production, as well as a Th2-type cytokine profile (high interleukin-4 [IL-4] and IL-10 production but low gamma interferon production) in BALB/c mice. rDiAg significantly elicited the proliferative response of naive B cells. This response was not abolished by polymyxin B, an inhibitor of lipopolysaccharide (LPS), and rDiAg normally expanded splenic B cells from LPS nonresponder C3H/HeJ mice. Thus, the mitogenic effect of rDiAg was not due to LPS contamination. rDiAg also enhanced levels of CD23 expression on splenic B cells. Splenic B cells produced marked levels of IgE when cultured with the combination of rDiAg and IL-4 (rDiAg-IL-4), whereas peritoneal B cells produced negligible levels of IgE. rDiAg-IL-4-induced IgE production by splenic B cells was synergistically increased by coculture with peritoneal B cells. rDiAg-driven IL-10 secretion was higher in peritoneal B cells than in splenic B cells. IgE production by splenic B cells cocultured with peritoneal B cells was decreased to a level comparable to that by splenic B cells in the presence of a neutralizing anti-IL-10 monoclonal antibody. Collectively, these results suggest that rDiAg-induced polyclonal expansion and IgE class switching of splenic B cells contribute to nonspecific IgE production and that these responses are enhanced by peritoneal B-cell-derived IL-10.

Oral administration of IL-12 suppresses anaphylactic reactions in a murine model of peanut hypersensitivity

There is no satisfactory therapeutic intervention for peanut allergy, which accounts for most life-threatening food allergic reactions. Since IL-12 has been found to inhibit allergic airway responses in a mouse model of asthma and to cure Th2 cytokine-mediated murine schistosomiasis, we hypothesized that IL-12 treatment might also inhibit peanut allergic reactions. Consequently, we investigated the effects of oral IL-12 treatment in a murine model of peanut allergy and found that oral administration of liposome encapsulated rIL-12 could both prevent and reverse peanut hypersensitivity and could reduce histamine release, peanut-specific serum IgE and IgG1, and fecal IgA levels. Oral IL-12 treatment also increased IFN-gamma but did not decrease IL-4 or IL-5 levels. We conclude that oral rIL-12 treatment has therapeutic as well as preventive effects on peanut allergy, which are associated with increased IFN-gamma production.

Medroxyprogesterone acetate enhances in vivo and in vitro antibody production

In the present study we examine the effects of medroxyprogesterone acetate (MPA) on the specific antibody secretion to T-dependent antigens. Our results show that the in vivo administration of MPA to mice, 7 or 90 days before immunization with sheep red blood cells (SRBC), significantly enhanced both, primary and secondary antibody responses, without affecting delayed-type hypersensitivity (DTH). These effects could be counteracted by the anti-progestin onapristone or ZK 98299 (ZK) suggesting that MPA interacted with progesterone (PRG) receptors to increase B-cell response. To better understand the mechanisms involved in MPA activity we carried out cultures of splenocytes, bone marrow cells or lymph node cells from immunized mice in the presence of MPA, and evaluated the amount of antibody release to supernatants. We found that low doses of MPA (10(-9) M and 10(-10) M) significantly enhanced the in vitro production of specific immunoglobulin G (IgG) antibodies, an effect that appears to involve the interaction of the progestin with PRG receptors, as judged by the inhibition of MPA effects with ZK (10(-8) M) or RU486 (10(-9) M). These receptors were detected by flow cytometry analysis in a proportion of T lymphocytes. Because MPA did not increase the number of immunoglobulin-secreting cells, our findings suggest that MPA enhanced the capacity of individual cells to produce specific immunoglobulin.

Preferential binding of Staphylococcus aureus to skin sites of Th2-mediated inflammation in a murine model

Staphylococcus aureus is found on over 90% of atopic dermatitis skin lesions and is thought to contribute to skin inflammation via the production of potent exotoxins. In contrast, less than 5% of normal subjects harbor S. aureus. This suggests that an atopic immune response itself may play a role in preferential binding of S. aureus to the skin. To examine this issue more directly, we analyzed the S. aureus binding characteristics of skin in mice undergoing different T helper type 1 cell versus T helper type 2 cell inflammatory responses using a novel in vitro bacterial binding assay. BALB/C female mice were first sensitized to ovalbumin with alum or ovalbumin with complete Freund's adjuvant to induce T helper type 2 or T helper type 1 responses, respectively. Mice were then challenged intradermally with either saline (control) or ovalbumin. Forty-eight hours later, skin specimens were obtained from the challenge sites, and the number of S. aureus binding to each skin section was quantitated. Bacterial binding was found to be significantly greater at skin sites of BALB/C mice that had been ovalbumin/alum sensitized compared with ovalbumin/complete Freund's adjuvant sensitized (p < or = 0.01). When compared to the ovalbumin sensitized/challenged skin of wild type BALB/C mice or interferon-gamma gene knockout mice, interleukin-4, but not interferon-gamma, gene knockout mice had significantly less S. aureus binding at their ovalbumin sensitized/challenged skin sites. Mutant S. aureus strains that lacked either fibronectin- or fibrinogen-binding protein expression showed significantly reduced S. aureus binding compared with the parent wild type strain (p < 0.005). Moreover, preincubation of the wild type bacteria with fibronectin or fibrinogen, but not collagen, resulted in significantly less skin binding of S. aureus (p < 0.01). Incubation of skin with interleukin-4, and less so with interferon-gamma, led to more binding of wild type S. aureus but not of an S. aureus mutant deficient in fibronectin binding protein expression. After interleukin-4 incubation, but not interferon-gamma, epidermal immunoreactivity for fibronectin was observed in murine skin explants. These results show that a T helper type 2 inflammatory environment can promote skin binding by S. aureus and that this binding is mediated by fibronectin and fibrinogen.